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Sample records for single-plane contrast ventriculography

  1. Digital subtraction ventriculography for assessment of global and regional leftventricular parameters in comparison to conventional contrast ventriculography

    International Nuclear Information System (INIS)

    Eichstaedt, H.; Langer, M.; Felix, R.

    1984-01-01

    Since May 1982 we studied more than 100 patients with heart diseases by means of digital angiography, out of them 46 patients with a history of transmural myocardial infarction were selected. Urografin 76, 30 ml, was administered at a flow rate of 18 ml/s by means of a catheter in the superior vena cava during digital subtraction ventriculography. Results were compared with conventional contrast ventriculograms. The correlation coefficient was r=0.93 (p 0.001) for determination of ejection fraction with both methods. The data in individual cases suggest that DSV is more sensitive than conventional contrast ventriculography in determination of severely reduced ejection fractions. The methods are practically identical in qualitative evaluation of disorders of regional wall motion in the anterolateral region, while DSV is more sensitive than conventional ventriculography in evaluating the apical region. Sensitivity was 85.7% when the two methods were compared in evaluation of the inferior region of the left ventricle. Both methods are identical in demonstration of severely deformed ventricles. Digital subtraction ventriculography may replace conventional contrast ventriculography in some of situations discussed above. (orig.)

  2. Ventriculography and cisternography with water-soluble contrast media in infants with myelomeningocele

    International Nuclear Information System (INIS)

    Yamada, H.; Nakamura, S.; Tanaka, Y.; Tajima, M.; Kageyama, N.

    1982-01-01

    Fifty-four newborn infants with myelomeningocele and hydrocephalus were studied by ventriculography using water-soluble contrast media; 20 were also studied by metrizamide myeloencephalography and computerized tomographic (CT) cisternography. Ventriculography suggested that the aqueduct was patent in all cases. Outflow of contrast medium from the fourth ventricle was slow in most cases, complete obstruction was seen in 15%, communication was delayed at the outlet in 54%, and rather free communication was observedin 31%. Metrizamide myeloencephalography and CT cisternography suggested a partial block at the level of the ambient cisterns in approximately one-third of infants. These findings support the concept that flow of cerebrospinal fluid is reduced in several areas. Aqueductal stenosis was not considered an important factor in hydrocephalus, while the most important site of obstruction was felt to be the lowest portion of the fourth ventricle

  3. Clinical experience with a non-ionic contrast medium (ultravist) in left ventriculography

    International Nuclear Information System (INIS)

    Lee, Ghi Jai; Park, Jae Hyung; Soe, Gwy Suk; Hong, Ju Hee; Han, Man Chung

    1988-01-01

    Non-ionic contrast medium, iopromide (Ultravist), was compared with ionic contrast medium, ioxitalamate (Telebrix), for efficacy and safety in 63 patients undergoing left ventriculography. In all patients, adverse symptoms and signs including pain, heat sense, nausea, vomiting, etc., were checked during and shortly after the injection. Blood pressure, heart rate, EKG and left ventricular pressure were also monitored during the study, and CBC, UA, BUN and creatinine were checked before and 24 hours after the study. The cineangiographic films were analysed and compared by 2 radiologists for the quality. Serious adverse effect did not occur in any case. Minor effects, especially nausea, were lee frequently caused by non-ionic contrast medium than by ionic contrast medium, and heat sense to non-ionic contrast medium was less severe than to ionic contrast medium. Except slightly elevated LVEDP at 1,5 minutes after the study in patients given ionic contrast medium, there was no significant change of electrophysiologic parameters and laboratory findings in both groups. In regard to image quality, there was no significant difference between ionic and non-ionic contrast medium. Thus non-ionic contrast medium, iopromide, appears to be safer for use in left ventriculography than the conventional ionic contrast medium, particularly in those patients at high risk of adverse effects.

  4. Segmental wall-motion analysis in the right anterior oblique projection: comparison of exercise equilibrium radionuclide ventriculography and exercise contrast ventriculography

    International Nuclear Information System (INIS)

    Brady, T.J.; Thrall, J.H.; Keyes, J.W. Jr.; Brymer, J.F.; Walton, J.A.; Pitt, B.

    1980-01-01

    Thirty-nine patients with known or suspected coronary artery disease were studied at rest and during supine bicycle exercise with radionuclide and contrast left ventriculography. Analysis of regional wall motion was made by visual evaluation of the five standard 30 0 right anterior oblique (RAO) wall segments in the contrast images and the corresponding 10 0 RAO radionuclide segments. The radionuclide studies were evaluated independently by three observers using a five-point grading system. The interobserver wall-motion grading agreed completely in more than 80% of segments at rest and exercise, and agreed within one wall-motion grade in more than 95% of segments. The comparison of wall-motion grades between radionuclide and contrast ventriculograms showed complete agreement in 86% of segments at rest and in 78% during exercise, and agreement within one wall-motion grade in 97% of rest and 96% of exercise segments. Visual evaluation of 10 0 RAO rest and exercise radionuclide ventriculograms compares favorably with rest and exercise 30 0 RAO contrast ventriculograms and demonstrates satisfactory interobserver agreement

  5. Measurement of left ventricular ejection fraction using gated 99mTc-sestamibi myocardial planar images: Comparison to contrast ventriculography

    International Nuclear Information System (INIS)

    Parker, D.A.; Lloret, R.L.; Barilla, F.; Douthat, L.; Gheorghiade, M.

    1991-01-01

    Using the new myocardial perfusion agent 99mTc-sestamibi and multigated acquisition on a nuclear medicine gamma camera, the left ventricular ejection fraction (LVEF) was derived in 13 patients with coronary artery disease (CAD). Cross-sectional activity profiles were used to measure the left ventricle from end-diastolic and end-systolic images. Several different geometric methods were then utilized to derive ejection fractions from the nuclear data. Comparison of the resultant ejection fractions to those obtained from contrast ventriculography showed significant correlation for all geometric methods (P less than 0.01, Sy X x = 6.2 to 9.6). The authors conclude that in patients with CAD one or more of these simple geometric methods can provide a useful estimate of the LVEF when performing 99mTc-sestamibi multigated myocardial perfusion imaging

  6. Cardiac ventriculography

    International Nuclear Information System (INIS)

    Hillis, L.D.; Grossman, W.

    1986-01-01

    Cardiac ventriculography has been used extensively to define the anatomy of the ventricles and related structures in patients with congenital, valvular, coronary, and cardiomyopathic heart disease. Specifically, left ventriculography may provide valuable information about global and segmental left ventricular function, mitral valvular incompetence, and the presence, location, and severity of a number of other abnormalities, including ventricular septal defect and hypertrophic cardiomyopathy. As a result, it should be a routine part of catheterization in patients being evaluated for coronary artery disease, aortic or mitral valvular disease, unexplained left ventricular failure, or congenital heart disease. Similarly, right ventriculography may provide information about global and segmental right ventricular function and can be especially helpful in patients with congenital heart disease

  7. Dedicated radial ventriculography pigtail catheter

    Energy Technology Data Exchange (ETDEWEB)

    Vidovich, Mladen I., E-mail: miv@uic.edu

    2013-05-15

    A new dedicated cardiac ventriculography catheter was specifically designed for radial and upper arm arterial access approach. Two catheter configurations have been developed to facilitate retrograde crossing of the aortic valve and to conform to various subclavian, ascending aortic and left ventricular anatomies. The “short” dedicated radial ventriculography catheter is suited for horizontal ascending aortas, obese body habitus, short stature and small ventricular cavities. The “long” dedicated radial ventriculography catheter is suited for vertical ascending aortas, thin body habitus, tall stature and larger ventricular cavities. This new design allows for improved performance, faster and simpler insertion in the left ventricle which can reduce procedure time, radiation exposure and propensity for radial artery spasm due to excessive catheter manipulation. Two different catheter configurations allow for optimal catheter selection in a broad range of patient anatomies. The catheter is exceptionally stable during contrast power injection and provides equivalent cavity opacification to traditional femoral ventriculography catheter designs.

  8. Determination of left ventricular volume using gated blood pool tomography comparison with contrast ventriculography

    International Nuclear Information System (INIS)

    Lu Ping; Mo Lijun; Liu Xiujie

    1992-01-01

    48 patients with cardiac disease were studied with gated blood pool tomography to determine left ventricular volume at end diastole, end-systole and ejection fraction. The volumes were calculated from serial short-axis tomograms by multiplying the number of pixels and the known volume of each pixel. Excellent correlation was found between blood pool tomography and contrast ventriculographic volume. At end-diastole, r = 0.91 (P < 0.01); at end-systole, r = 0.95 (P < 0.01); for left ventricular ejection fraction, r 0.90 (P < 0.01). The results suggest that gated blood pool tomography is a promising noninvasive and direct method for measuring left ventricular volume

  9. Quantitative analysis of cardiac function: Comparison of electrocardiogram dual gated single photon emission tomography, planar radionuclide ventriculogram and contrast ventriculography in the determination of LV volume and ejection fraction

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    Ziada, G.; Abdel-Dayem, H.M.; Higazy, E.; Mohamed, M.M.; Bahar, R.; Hayat, N.; Yousof, A.M.

    1987-03-01

    A dual gated tomography (DGT) program for end systolic and end diastolic acquisition and subsequent processing for calculation of LVEF, end diastolic and end systolic volumes (EDV, ESV) has been evaluated in 20 healthy volunteers (25 years-40 years) and 45 patients (25 years-60 years): 20 with ischaemic heart disease and 25 with valvular heart disease (VHD). All had biplane multigated blood pool (MUGA) studies in the 40/sup 0/ LAO projection using in vivo /sup 99m/Tc-R BCs, immediately followed by DG. The results in the patients group were correlated with contrast ventriculography (CV). In the volunteer group, the normal values for LVEF, EDV and ESV measured with DGT were found to be 63%+10%, 91 ml + 6 ml and 30 ml + 6ml and r value for the LVEF=0.91 compared with MUGA. In the IHD group, r values compared with CV were 0.915 and 0.97 for the EDV and ESV and 0.934 for the LVEF. Compared with the MUGA, the r value for LVEF was 0.883. In the VHD group, r values were 0.98 for both the EDV and ESV and 0.948 for the LVEF (P<0.002) compared with CV and 0.789 for the LVEF compared with the MUGA. We feel that DGT is an accurate and reproducible technique for LV function measurements.

  10. Physical aspects of nuclear ventriculography

    International Nuclear Information System (INIS)

    Alpert, N.M.; Chesler, D.A.; Burnham, C.A.; McKusick, K.A.; Pohost, G.; Dinsmore, R.E.; Brownell, G.L.

    1976-01-01

    The use of edge enhancement and computer motion display improves the detection of regional wall motion abnormalities in the LV. Improved gating and processing techniques should improve the accuracy of ventricular volume vs time measurements. It is hoped that the simulations described will aid in the development of new instrumentation for the collection and analysis of nuclear ventriculographie data

  11. Computed tomography and/or ventriculography

    International Nuclear Information System (INIS)

    Wende, S.; Kishikawa, T.; Huewel, N.; Kazner, E.; Grumme, T.; Lanksch, W.

    1982-01-01

    It is discussed if in intracranial tumors, especially in tumors of the posterior cranial fossa, a CT and/or a ventriculography should be practiced. We have made investigations of 134 patients, 93 of whom were children up to 14 years of age. Each case was undertaken computed tomography as well as ventriculography. The results are clearly demonstrating the superiority of computed tomography compared with ventriculography. Ventriculography is a surgical intervention stressing the patients, side-effects may occur, and sometimes serious complications are caused. Modern computed tomography is producing pictures of high quality, which are highly sufficient for neurosurgical intervention. Very rarely additional angiography has to be performed. The diagnosis of intracranial tumors can fully be established by computed tomography, whereas ventriculography is no longer necessary. (orig.) [de

  12. Scintigraphic ventriculography and stress testing

    International Nuclear Information System (INIS)

    Goris, M.L.; Hung, J.; Debusk, R.F.

    1982-01-01

    Scintigraphic stress ventriculography yields information which is complex and defies description by the difference in ejection fraction between rest and maximum exercise only. The complexity results in part from the ''derived'' nature of the ejection fraction measurement, which is physiologically secondary to stroke volume and end-diastolic volume. Furthermore, the nature of the stress test in which the pulse (stress) is not independent from the response forces an analysis which considers ''when'' as much as ''what'' happens. Automation in data processing, however, has made oversimplification unnecessary and allows a more exhaustive but correct analysis

  13. Evaluation of left ventricular function using digital subtraction ventriculography

    International Nuclear Information System (INIS)

    Yiannikas, J.; Detrano, R.

    1986-01-01

    Digital subtraction ventriculography following injections of contrast via peripheral veins provides excellent images to assess left ventricular function. The images are essentially identical to those following DCV, but allow more uniform mixing of contrast in the left ventricular chamber. Furthermore, few, if any, cardiac arrhythmias occur, hence obviating difficulties that arise from DCV. The spatial resolution of the method is such that regional wall motion assessment of ventricular function is more accurate than that of other noninvasive imaging methods. The use of video-densitometry allows accurate assessment of left ventricular function even when the left ventricular cavity is nonsymmetrically deformed and aneurysmal. In the setting of the cardiac catheterization laboratory, digital ventriculography may provide a safer means of assessing left ventricular function when critical coronary or myocardial disease is present and allows multiple assessments of ventricular function during the same study. Although excellent correlations with standard ventriculography have been noted by all workers, significant discrepancies still exist in individual patients, particularly in the calculations of end diastolic volumes. In the authors experience and in those of most workers, the largest discrepancies existed in patients in whom suboptimal studies are included for analysis. The most frequent reason for the occasional suboptimal study as with all digital subtraction work is the misregistration that results from motion

  14. Preoperative prediction of reversible myocardial asynergy by postexercise radionuclide ventriculography

    International Nuclear Information System (INIS)

    Rozanski, A.; Berman, D.; Gray, R.; Diamond, G.; Raymond, M.; Prause, J.; Maddahi, J.; Swan, H.J.; Matloff, J.

    1982-01-01

    Myocardial asynergy is sometimes reversed by coronary bypass, and a noninvasive method of predicting which assess are reversible would be desirable. To assess whether changes in myocardial wall motion observed immediately after exercise can differentiate reversible from nonreversible myocardial asynergy, we evaluated 53 patients by radionuclide ventriculography before and after exercise and again at rest after coronary bypass surgery. Preoperative improvement in wall motion immediately after exercise was highly predictive of the surgical outcome (average chance-corrected agreement, 91 per cent). At surgery the asynergic segments that had improved after exercise were free of grossly apparent epicardial scarring. The accuracy of these predictions for postoperative improvement was significantly greater (P less than 0.01) than that of analysis of Q waves on resting electrocardiography (average chance-corrected agreement, 40 per cent). In contrast, preoperative changes in left ventricular ejection fraction after exercise were not predictive of postoperative resting ejection fraction. We conclude that postexercise radionuclide ventriculography can be used to identify reversible resting myocardial asynergy. This test should prove effective in predicting which patients with myocardial asynergy are most likely to benefit from aortocoronary revascularization

  15. Improved method of static radionuclide ventriculography

    International Nuclear Information System (INIS)

    Davidzon, G.S.; Myasnik, B.N.

    1988-01-01

    A method of 2-stage recording of radionuclide ventriculography has been proposed, the second stage being shifted to a certain time interval, i.e. a delay line is introduced between a synchronizing device and computer. Particular attention is drawn to a choice of delay time depending on a computer memory volume: in a small memory volume delay time must be approximately one-third of the patient's R-R interval

  16. Radionuclide exercise ventriculography and levels of workload

    International Nuclear Information System (INIS)

    Wynchank, S.

    1982-01-01

    The wealth of useful information made available from the utilization of radionuclide cardiological investigations by non-invasive means is outlined and reasons for investigating results obtained under conditions of increased heart workload are explained. The lack of an accepted protocol for the determination of exercise levels is noted. A format for obtaining increasing heart loads dependent on increasing pulse rate is offered, with justification. Exercise radionuclide ventriculography examinations can be conducted which are simple, reproducible and allow appropriate levels of stress in patients who can benefit from such investigations

  17. Right-sided phase abnormalities on gated blood pool ventriculography: Demonstration of six different patterns

    International Nuclear Information System (INIS)

    Bahar, R.H.; Abdel-Dayem, H.M.; Ziada, G.; Al-Suhali, A.; Constantinides, C.; Nair, K.M.

    1986-01-01

    Phase pattern abnormalities on multiple gated blood pool ventriculography are better reported for the left ventricle (LV) than for the right side of the heart. In a study of 92 patients who also underwent contrast ventriculography, the authors identified six different patterns of right-sided phase abnormalities and their causes: right bundle-branch block, causing delayed phase in the entire right ventricle (RV); ischemic right coronary artery disease, causing delayed phase in the inferior RV wall; pericardial effusion, causing an L-shaped area of delayed phase to the right of the septum and below the LV; pulmonary hypertension, causing delayed phase in the pulmonary infundibulum; tricuspid regurgitation, causing a crescentic area of delayed phase around and below the right RV and extending below the LV as well, and atrial septal defect causing an abnormally large auricular phase

  18. Application of radionuclide ventriculography to cardiac screening

    International Nuclear Information System (INIS)

    Lindsay, J. Jr.; Milner, M.R.; Chandeysson, P.L.; Rodman, D.J.; Okin, P.M.; Goldstein, S.A.

    1989-01-01

    Screening asymptomatic individuals for latent coronary disease often requires sequential testing because exercise electrocardiography typically produces more false positive than true positive results in a population with a low prevalence of coronary disease. Cardiac scintigraphy is a technique that may be employed as a confirmatory test in lieu of coronary arteriography to further evaluate the significance of a positive exercise electrocardiogram. Radionuclide ventriculography was employed in 98 asymptomatic individuals who were considered to be at moderate risk of heart disease after risk factor analysis and exercise electrocardiography. Seventeen (17%) patients had an abnormal study and underwent cardiac catheterization. Seven had coronary artery disease, two had cardiomyopathy, and eight were normal. Eighty-one (83%) patients had a normal study. Because the sensitivity of radionuclide ventriculography is 63-80%, it was postulated that 2 to 5 individuals with disease were missed. Thus, from a population with an 11-14% prevalence of disease, two subsets were identified. A large subset in which a prevalence of 2-6% could be estimated was separated from a much smaller one in which a prevalence of approximately 50% was demonstrated

  19. Potassium cardioplegia: early assessment by radionuclide ventriculography

    International Nuclear Information System (INIS)

    Ellis, R.J.; Born, M.; Feit, T.; Ebert, P.A.

    1978-01-01

    Left ventricular function was evaluated by single pass /sup 99m/Tc radionuclide ventriculography when potassium cardioplegia was combined with hypothermia. In 35 patients undergoing myocardial revascularization (3 CABG/patient) in which potassium cardioplegia at 4 0 C was used, no patient developed a myocardial infarction either by electrocardiogram or /sup 99m/Tc pyrophosphate imaging in the postoperative period. In 22 patients, aortic cross-clamp time was greater than 60 min, and the ejection fraction by the single pass radionuclide technique was 50% preoperatively and 53% postoperatively (NS). Wall motion in the single RAO view was not worse postoperatively. No patient required any inotropic agents in the immediate postoperative period. It appears that no significant ventricular impairment occurred in the immediate postoperative period (48 to 72 hours) when potassium cardioplegia combined with hypothermia was used for a 60-minute period

  20. Equilibrium radionuclide ventriculography: Comparison with echo-ventriculography and digital subtraction angiocardiography, evaluation of multiparameters

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    Hoer, G; Standke, R; Klepzig, H Jr; Maul, F D; Tuengerthal, S; Tezak, S; Reifarth, N; Kanemoto, N; Happ, J; Baum, R P

    1986-09-01

    Subsequent to the discussion of technical prerequisites (fully-automated, reproducible multiparameter-analysis (MPA), rest, exercise) which is followed by remarks concerning the pathophysiology of ischemic left ventricular functional disorders in diastole and systole, the following points are considered: 1) comparative results of RNV, cineventriculoangiography, echo-ventriculography and intraveneous digital subtraction angiocardiography; 2) 'normal' values of RNV in MPA; 3) heart and pulmonary diseases (coronary artery disease with sensitivity and specificity of MPA), chronic obstructive pulmonary disease, chronic aortic insufficiency, hypertension; 4) summary of, and prospects for future potentialities (software, clinical indications).

  1. Factor analysis for exercise stress radionuclide ventriculography

    International Nuclear Information System (INIS)

    Hirota, Kazuyoshi; Yasuda, Mitsutaka; Oku, Hisao; Ikuno, Yoshiyasu; Takeuchi, Kazuhide; Takeda, Tadanao; Ochi, Hironobu

    1987-01-01

    Using factor analysis, a new image processing in exercise stress radionuclide ventriculography, changes in factors associated with exercise were evaluated in 14 patients with angina pectoris or old myocardial infarction. The patients were imaged in the left anterior oblique projection, and three factor images were presented on a color coded scale. Abnormal factors (AF) were observed in 6 patients before exercise, 13 during exercise, and 4 after exercise. In 7 patients, the occurrence of AF was associated with exercise. Five of them became free from AF after exercise. Three patients showing AF before exercise had aggravation of AF during exercise. Overall, the occurrence or aggravation of AF was associated with exercise in ten (71 %) of the patients. The other three patients, however, had disappearance of AF during exercise. In the last patient, none of the AF was observed throughout the study. In view of a high incidence of AF associated with exercise, the factor analysis may have the potential in evaluating cardiac reverse from the viewpoint of left ventricular wall motion abnormality. (Namekawa, K.)

  2. Do we need ventriculography in the era of computed tomography

    International Nuclear Information System (INIS)

    Wende, S.; Kishikawa, T.; Huewel, N.; Kazner, E.; Grumme, T.; Lanksch, W.

    1982-01-01

    The question is posed whether in the investigation of intracranial tumors, particularly in the posterior cranial fossa, CT and/or ventriculography should be practiced. We investigated 134 patients (93 were children up to the age of 14 years), all of whom had both computed tomography and ventriculography. The results clearly demonstrate the superiority of CT compared with centriculography. Ventriculography is a surgical intervention with risk for the patient; side effects may occur and serious complications can sometimes arise. Modern CT is producing pictures of high quality which are entirely sufficient for neurosurgical intervention. Very rarely does additional angiography have to be performed. The diagnosis of intracrenial tumor can be fully established by CT and ventriculogrphy is no longer necessary. (orig.)

  3. A method for measuring three-dimensional mandibular kinematics in vivo using single-plane fluoroscopy

    Science.gov (United States)

    Chen, C-C; Lin, C-C; Chen, Y-J; Hong, S-W; Lu, T-W

    2013-01-01

    Objectives Accurate measurement of the three-dimensional (3D) motion of the mandible in vivo is essential for relevant clinical applications. Existing techniques are either of limited accuracy or require the use of transoral devices that interfere with jaw movements. This study aimed to develop further an existing method for measuring 3D, in vivo mandibular kinematics using single-plane fluoroscopy; to determine the accuracy of the method; and to demonstrate its clinical applicability via measurements on a healthy subject during opening/closing and chewing movements. Methods The proposed method was based on the registration of single-plane fluoroscopy images and 3D low-radiation cone beam CT data. It was validated using roentgen single-plane photogrammetric analysis at static positions and during opening/closing and chewing movements. Results The method was found to have measurement errors of 0.1 ± 0.9 mm for all translations and 0.2° ± 0.6° for all rotations in static conditions, and of 1.0 ± 1.4 mm for all translations and 0.2° ± 0.7° for all rotations in dynamic conditions. Conclusions The proposed method is considered an accurate method for quantifying the 3D mandibular motion in vivo. Without relying on transoral devices, the method has advantages over existing methods, especially in the assessment of patients with missing or unstable teeth, making it useful for the research and clinical assessment of the temporomandibular joint and chewing function. PMID:22842637

  4. Assessment of ventricular function by radionuclide ventriculography in hyperthyroidism

    International Nuclear Information System (INIS)

    Dong Weiyu; He Pinyu; Zhuang Weite

    1996-01-01

    Left ventricular(LV) and right ventricular(RV) function were determined using radionuclide ventriculography in 50 patients with hyperthyroidism. LVEF, LVPFR, SV of the hyperthyroidism group were decreased in comparison with the normal group (P<0.01), whereas CO of the hyperthyroidism patients were higher than that of normal (P<0.01). Except LVPER, the LVEF, SV had significant difference between two groups. Compared to normal group, RVEF, RVPER, RVPFR were also decreased (P<0.01). Besides 30 cases of the hyperthyroidism were examined by impedance cardiogram (ICG) and impedance pulmonary rheogram (IPR), all showed closely correlation with the parameters determined by ventriculography. There was the involvement of right ventricular function insufficiency, especially in ejection phase. When compared with pre-therapy, pos-therapy cases showed significant improvement in EF, PER, PFR of left and right ventricular

  5. Radionuclide ventriculography in children with Duchenne muscular dystrophy

    International Nuclear Information System (INIS)

    Tian Jiahe

    1992-01-01

    The ventricular functions of 22 children with Duchenne disease(DD) were studied by radionuclide multi-gated ventriculography using in-vivo labeled 99m Tc-RBC and compared with those of 30 age-matched normal children, 20 congenital heart disease and 7 congestive cardiomyopathy. 21 parameters were evaluated, including RV and LV EF, systolic and diastolic functions and phase distribution, etc. It was found that the DD patients showed several specific cardiac functional alterations, i.e, slight but significant abnormality in both systolic and diastolic function, special phase delay at post-lateral segment of LV in 81.8% of the patients. It is concluded that (1) all DD patients have definite evidence of heart injury; (2) the injury is mainly on the left side of the heart, influencing entire cardiac cycle; (3) there is specific phase abnormality in DD patients; (4) the radionuclide ventriculography is of great value in monitoring of these cardiac functional changes

  6. Results of radionuclide ventriculography in normal children and adolescents

    International Nuclear Information System (INIS)

    Reich, O.; Krejcir, M.; Ruth, C.

    1989-01-01

    In order to assess the range of normal values in radionuclide ventriculography, 53 normal children and adolescents were selected in retrospect. All were exdamined by radionuclide angiocardiography on account of clinical and echocardiographical suspicion of congenital heart disease with a left-to-right shunt; a significant shunt was, however, excluded. In all patients, after equilibration of the radiopharmaceutical the ventricular function was examined by radionuclide ventriculography. The usual volume, time and rate characteristics were evaluated. The normal range was defined as the mean ±2 standard deviations which is 47 to 72% for the ejection fraction of the left ventricle and 31 to 56% for the ejection fraction of the right ventricle. (author). 2 tabs., 18 refs

  7. Quantification of in vivo implant wear in total knee replacement from dynamic single plane radiography

    Science.gov (United States)

    Teeter, Matthew G.; Seslija, Petar; Milner, Jaques S.; Nikolov, Hristo N.; Yuan, Xunhua; Naudie, Douglas D. R.; Holdsworth, David W.

    2013-05-01

    An in vivo method to measure wear in total knee replacements was developed using dynamic single-plane fluoroscopy. A dynamic, anthropomorphic total knee replacement phantom with interchangeable, custom-fabricated components of known wear volume was created, and dynamic imaging was performed. For each frame of the fluoroscopy data, the relative location of the femoral and tibial components were determined, and the apparent intersection of the femoral component with the tibial insert was used to calculate wear volume, wear depth, and frequency of intersection. No difference was found between the measured and true wear volumes. The precision of the measurements was ±39.7 mm3 for volume and ±0.126 mm for wear depth. The results suggest the system is capable of tracking wear volume changes across multiple time points in patients. As a dynamic technique, this method can provide both kinematic and wear measurements that may be useful for evaluating new implant designs for total knee replacements.

  8. Evaluation of ventriculography as a supplement to computed tomography

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    Nakstad, P.; Sortland, O.; Hovind, K.

    1982-04-01

    The diagnostic value of ventriculography (VGR) as a supplement to computed tomography (CT) is evaluated in 42 patients. CT was slightly superior for diagnosing expanding lesions and could tell more about the size and nature of the processes in this selected material which includes only lesions adjacent to the ventricular system. VGR yielded more information about the attachment of a tumor to the wall, floor, or roof of the ventricles. Stenosis or occlusion of the Sylvian aqueduct, communicating hydrocephalus, and basal adhesive arachnoiditis were diagnosed by VGR, while the correct diagnosis could be suggested only by CT in these cases.

  9. Quantitative assessment of valvular regurgitation using radionuclide ventriculography

    International Nuclear Information System (INIS)

    Shi Rongfang

    1992-01-01

    Radionuclide ventriculography has been used to assess quantitatively the extent of mitral and aortic regurgitation in 70 patients and compared to echocardiography and the finding of surgery. Two radionuclide parameters were measured: regurgitant index (RI) = left ventricular stroke counts/right ventricular stroke counts; and regurgitant fraction (RF) = left ventricular stroke counts-right ventricular stroke counts/left ventricular stroke counts. In 28 patients without valvular heart disease, the RI was 1.10 ± 0.15 and Rf was 10.3 ± 15.0%, respectively. However, in patients with valvular regurgitation, the RI and RF were 3.41 ± 1.73 and 61.1 ± 21.2%, respectively. A good correlation was found between the results obtained by radionuclide techniques and the findings of surgery and doppler studies. The level of concordance between RI and surgical findings was 91.7%. Follow up studies in 10 patients after valvular replacement surgery showed the RI and RF return to normal. These data suggested that radionuclide ventriculography is very useful for quantitative assessment of valvular regurgitation

  10. Quantification of in vivo implant wear in total knee replacement from dynamic single plane radiography

    International Nuclear Information System (INIS)

    Teeter, Matthew G; Naudie, Douglas D R; Holdsworth, David W; Seslija, Petar; Milner, Jaques S; Nikolov, Hristo N; Yuan Xunhua

    2013-01-01

    An in vivo method to measure wear in total knee replacements was developed using dynamic single-plane fluoroscopy. A dynamic, anthropomorphic total knee replacement phantom with interchangeable, custom-fabricated components of known wear volume was created, and dynamic imaging was performed. For each frame of the fluoroscopy data, the relative location of the femoral and tibial components were determined, and the apparent intersection of the femoral component with the tibial insert was used to calculate wear volume, wear depth, and frequency of intersection. No difference was found between the measured and true wear volumes. The precision of the measurements was ±39.7 mm 3 for volume and ±0.126 mm for wear depth. The results suggest the system is capable of tracking wear volume changes across multiple time points in patients. As a dynamic technique, this method can provide both kinematic and wear measurements that may be useful for evaluating new implant designs for total knee replacements. (paper)

  11. Non-ionic contrast media: are they obligatory?

    International Nuclear Information System (INIS)

    Halva, S.R.

    1993-01-01

    Author presents recommendations for nonionic contrast media application. They are more expensive but less toxic than ionic ones. In order to avoid side effects in many radiological examinations (phlebography, arteriography, coronarography, ventriculography) one should use nonionic contrast media. Another reason for application of nonionic contrast agents is young age of patient or his state of health

  12. Evaluation of planar 3D electrical capacitance tomography: from single-plane to dual-plane configuration

    International Nuclear Information System (INIS)

    Wei, Hsin-Yu; Qiu, Chang-Hua; Soleimani, Manuchehr

    2015-01-01

    Electrical capacitance tomography (ECT) is a non-invasive imaging technique that is sensitive to the dielectric permittivity property of an object. Conventional ECT systems have a circular/cylindrical or rectangular geometry, in which the electrode plates are usually spaced equally around the tank. It is the most common configuration as it can be easily applied to industrial pipelines. However, under some circumstances, the full access to the imaging geometry may not be applicable due to the limitation of the process area. In those cases, and with limited access, planar ECT sensors can fit the process structure if access to only one side is possible. A single-plane ECT configuration has been proposed for such applications. However, the planar array often suffers from a lack of sensitivity and difficulty with depth detection. To better understand these limitations we investigate the imaging performance from the single-plane ECT to dual-plane ECT structure. The limitations and constraints of the planar configuration will also be discussed. Several experiments were conducted using both single-plane and dual-plane configurations to evaluate the potential applications. The initial results are promising, and the quality of the reconstructed images are compared with the real condition for process validation. (paper)

  13. Error analysis of marker-based object localization using a single-plane XRII

    International Nuclear Information System (INIS)

    Habets, Damiaan F.; Pollmann, Steven I.; Yuan, Xunhua; Peters, Terry M.; Holdsworth, David W.

    2009-01-01

    The role of imaging and image guidance is increasing in surgery and therapy, including treatment planning and follow-up. Fluoroscopy is used for two-dimensional (2D) guidance or localization; however, many procedures would benefit from three-dimensional (3D) guidance or localization. Three-dimensional computed tomography (CT) using a C-arm mounted x-ray image intensifier (XRII) can provide high-quality 3D images; however, patient dose and the required acquisition time restrict the number of 3D images that can be obtained. C-arm based 3D CT is therefore limited in applications for x-ray based image guidance or dynamic evaluations. 2D-3D model-based registration, using a single-plane 2D digital radiographic system, does allow for rapid 3D localization. It is our goal to investigate - over a clinically practical range - the impact of x-ray exposure on the resulting range of 3D localization precision. In this paper it is assumed that the tracked instrument incorporates a rigidly attached 3D object with a known configuration of markers. A 2D image is obtained by a digital fluoroscopic x-ray system and corrected for XRII distortions (±0.035 mm) and mechanical C-arm shift (±0.080 mm). A least-square projection-Procrustes analysis is then used to calculate the 3D position using the measured 2D marker locations. The effect of x-ray exposure on the precision of 2D marker localization and on 3D object localization was investigated using numerical simulations and x-ray experiments. The results show a nearly linear relationship between 2D marker localization precision and the 3D localization precision. However, a significant amplification of error, nonuniformly distributed among the three major axes, occurs, and that is demonstrated. To obtain a 3D localization error of less than ±1.0 mm for an object with 20 mm marker spacing, the 2D localization precision must be better than ±0.07 mm. This requirement was met for all investigated nominal x-ray exposures at 28 cm FOV, and

  14. Selective coronarography and ventriculography with Iopamidol in the acute phase of myocardial infarction

    Energy Technology Data Exchange (ETDEWEB)

    Ricci Maccarini, P; Benenati, P M; Bellanti, G; Piscitelli, G

    1988-01-01

    The new techniques for an early treatement of acute myocardial infarction (AMI), such as thrombolysis and percutaneous transluminal angioplasty, often necessitate rapid and accurate radiological evaluation of coronaric lesions and left ventricular function. The aim of the present study was to evaluate both safety and tolerability of selective coronarography (SC) and left ventriculography (LVG), with iopamidol 370 mg I/ml as a contrast medium, in the acute phase of AMI. Thirty-nine patients aged 26-29 years, were examined: 18 group A, within 4 days (mean 2.6+-0.8 SD) and 21, group B, within 5-15 days after AMI (mean 8.8+-3 SD). Contrast media (cm) dosage varied from 150 to 300 ml (2.43-5.5 ml/bw). During the procedure, ECG was continuosly recorded; left ventricular pressure was registered immediately and 30 minutes after cm administration. During the following 9 days ECG tracings and plasmatic cytolysisenzymes were monitored. During the examination no patient complained of any symptoms. After LVG slight elevations in end diastolic pressure were detected in all patients (mean increase 4.7 mmHg), which were not relevant from a clinical point of view. In 11/39 cases ventricular tachycardia was observed, which spontaneously ceased. During SC no change in ECG tracings was registered except in one patient, group A, in whom complete transitory heart block was detected. After SC no alteration in instrumental and biochemical parameters was registered except in one patient, group B, in whom a reinfarction due to right coronaric artery occlusion was observed. In conclusion, these results suggest that both SC and LVG with iopamidol are safe techniques also in the early phase of myocardial infarction. 24 refs.

  15. Validation of single-plane fluoroscopy and 2D/3D shape-matching for quantifying shoulder complex kinematics.

    Science.gov (United States)

    Lawrence, Rebekah L; Ellingson, Arin M; Ludewig, Paula M

    2018-02-01

    Fluoroscopy and 2D/3D shape-matching has emerged as the standard for non-invasively quantifying kinematics. However, its accuracy has not been well established for the shoulder complex when using single-plane fluoroscopy. The purpose of this study was to determine the accuracy of single-plane fluoroscopy and 2D/3D shape-matching for quantifying full shoulder complex kinematics. Tantalum markers were implanted into the clavicle, humerus, and scapula of four cadaveric shoulders. Biplane radiographs were obtained with the shoulder in five humerothoracic elevation positions (arm at the side, 30°, 60°, 90°, maximum). Images from both systems were used to perform marker tracking, while only those images acquired with the primary fluoroscopy system were used to perform 2D/3D shape-matching. Kinematics errors due to shape-matching were calculated as the difference between marker tracking and 2D/3D shape-matching and expressed as root mean square (RMS) error, bias, and precision. Overall RMS errors for the glenohumeral joint ranged from 0.7 to 3.3° and 1.2 to 4.2 mm, while errors for the acromioclavicular joint ranged from 1.7 to 3.4°. Errors associated with shape-matching individual bones ranged from 1.2 to 3.2° for the humerus, 0.5 to 1.6° for the scapula, and 0.4 to 3.7° for the clavicle. The results of the study demonstrate that single-plane fluoroscopy and 2D/3D shape-matching can accurately quantify full shoulder complex kinematics in static positions. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  16. Detection of coronary artery disease by exercise radionuclide ventriculography, (1)

    International Nuclear Information System (INIS)

    Nishimura, Tsunehiko; Saito, Muneyasu; Uehara, Toshiisa; Kozuka, Takahiro

    1982-01-01

    In order to assess the detection of coronary artery disease (CAD) and LV functional reserve, exercise radionuclide ventriculography (ERV) were performed in 80 patients who underwent selective cardiac catneterization for evaluation of chest pain syndrome. 70 patients had CAD (30 patients with angina pectoris and 40 patients with myocardial infarction) and 10 did not. In this study, to obtain accurate data by ERV, its practical consideration were metioned. Radionuclide cardioangiography with sup(99m)Tc-invivo RBC labelling were performed using an Anger camera attached with high-sense collimator and on-line minicomputer system. For data aquisition, multi-gated method were used, especially during exercise, list mode collection was suitable for ERV because of variable R-R intervals. Patient stability was performed with an adjustable shoulder support and hand grip, ECG monitoring system by carbon electrolode was used to obtain during exercise. Exercise protocal was graded bicycle ergometer in supine position. As the results, in the patients of CAD, changes of LVEF from rest to exercise were under 5%, while in normal patients, LVEF increased over 5% in all patients. In 30 patients with angina pectoris, the ERV was abnormal in 25 for a sensitivity of 83.3% and specificity of 100%. The ERV were thought to be superior than stress ECG for the detection of CAD. In conclusion, with increasing clinical application, the use of ERV is rapidly becoming wider-spread but the excellent results were thought to depend upon the careful attention to equipment and exercise procedure. (author)

  17. Exercise radionuclide ventriculography to detect restenosis following coronary angioplasty

    International Nuclear Information System (INIS)

    De Puey, E.G.; Leatherman, L.L.; Dear, W.E.; Leachman, R.D.; Massin, E.K.; Mathur, V.S.; Burdine, J.A.

    1984-01-01

    Forty one patients (pts) underwent semiupright exercise gated radionuclide ventriculography (EGRNV) before, within 3 d after single vessel transluminal coronary angioplasty (TCA), and 4 to 12 mos later, at which time follow-up cardiac catheterization was also performed. Prior to TCA 76% of pts had abnormal EGRNV, as defined by a failure to increase ejection fraction (EF) by 5 points or the development of a new regional wall motion abnormality. Stenosis was reduced from 90 +- 7% to 18 +- 17%. Early after TCA, exercise duration and maximum double product increased (p's 20% but <50%; Group III (n=8): ≥ 50%] Pts with abnormal EGRNV early after TCA were demonstrated to have a greater percent increase in stenosis at late follow-up than pts with normal EGRNV (41 +- 30% vs 19 +- 25%, p<.001). Early after TCA EGRNV was abnormal in 5% of Group I pts vs 75% in Group III (p<.01), and EF increased to a greater degree during exercise in Group I pts (+11.3 +- 7.5 vs +3.5 +- 6.5 points, p<.01). At 4-12 mos EGRNV was abnormal in 27% of Group I vs 88% of Group III (p<.01), and during exercise EF increased in Group I pts (+11.8 +- 7.8 points) but decreased in Group III (-1.9 +- 8.7 points) (p<.0005). The accuracy of abnormal EGRNV in predicting ≥ 50% restenosis was 73% early post-TCA and 77% at 4-12 mos. The authors conclude that EGRNV is a valuable test to verify the success of TCA and to detect subsequent restenosis

  18. Equilibrium radionuclide ventriculography in male patients after transmural myocardial infarction

    Energy Technology Data Exchange (ETDEWEB)

    Nestaval, A; Stanek, V; Malek, I; Kidery, J; Runczik, I [Institut pro Klinickou a Experimentalni Medicinu, Prague (Czechoslovakia); Cernoch, V; Oppelt, A [Institut pro Dalsi Vzdelavani Lekaru a Farmaceutu, Prague (Czechoslovakia)

    1982-12-17

    The ejection fraction of the left ventricle was measured using the method of equilibrium radionuclide ventriculography in 10 healthy males and 57 males after the first transmural myocardial infarction. The examination was effected 4 to 7 months after the event and the sample is representative for males after myocardial infarction who are younger than 65 years and show no signs of heart insufficiency by the time of examination. The resting value of the ejection fraction was 63+-5% in healthy males, 54+-7% in patients with uncomplicated myocardial infarction and 37+-8% in patients with clinical manifestations of heart insufficiency in acute phase. The differences between the groups are statistically significant. In patients with anteroseptal localization of myocardial infarction there was a negative correlation between the ejection fraction on the one hand and the sum of the voltages of Q waves in precordial ECG map and the maximum value of serum creatine kinase in acute phase on the other. The ejection fraction was in correlation to the degree of pulmonary hypertension measured in equal phase during exercise. The ejection fraction was measured in 31 patients under the working load of 50 W; significant changes were not found in healthy males or in patients after myocardial infarction. No changes were found when the state just before discharge from the hospital was compared with his state 6 months after myocardial infarction. The results obtained in compensated patients showed a relative stability of the value of the ejection fraction both during the first 6 months after discharge and under a mild working load. A comparison between the indicators in acute phase and hemodynamic examination after 6 months shows that the value of the ejection fraction is a sensitive indicator of the extent of necrosis and functional lesion of the left ventricle.

  19. Receiver operating characteristic analysis improves diagnosis by radionuclide ventriculography

    International Nuclear Information System (INIS)

    Dickinson, C.Z.; Forman, M.B.; Vaugh, W.K.; Sandler, M.P.; Kronenberg, M.W.

    1985-01-01

    Receiver operating characteristic analysis (ROC) evaluates continuous variables to define diagnostic criteria for the optimal sensitivity (SENS) and specificity (SPEC) of a test. The authors studied exercise-induced chest pain (CP), ST-changes on electrocardiography (ECG) and rest-exercise gated radionuclide ventriculography (RVG) using ROC to clarify the optimal criteria for detecting myocardial ischemia due to coronary artherosclerosis (CAD). The data of 95 consecutive patients studied with coronary angiography, rest-exercise RVG and ECG were reviewed. 77 patients had ''significant'' CAD (≥50% lesions). Exercise-induced CP, ECG abnormalities (ST-T shifts) and RVG abnormalities (change in ejection fraction, 2-view regional wall motion change and relative end-systolic volume) were evaluated to define optimal SENS/SPEC of each and for the combined data. ROC curves were constructed by multiple logistic regression (MLR). By MLR, RVG alone was superior to ECG and CP. The combination of all three produced the best ROC curve for the entire group and for clinical subsets based on the number of diseased vessels and the presence or absence of prior myocardial infarction. When CP, ECG and RVG were combined, the optimal SENS/SPEC for detection of single vessel disease was 88/86. The SENS/SPEC for 3 vessel disease was 93/95. Thus, the application of RVG for the diagnosis of myocardial ischemia is improved with the inclusion of ECG and CP data by the use of a multiple logistic regression model. ROC analysis allows clinical application of multiple data for diagnosing CAD at desired SENS/SPEC rather than by arbitrary single-standard criteria

  20. Echocardiography, ventriculography and coronary angiography in patients just recovering from acute myocardial infarction

    International Nuclear Information System (INIS)

    Goetz, S.

    1983-01-01

    Comparative evaluations were carried out on the basis of ventriculography, echocardiography and corornary angiography that would permit to throw some light on the following issues: Can the changes in overall ventricular function occurring in response to the processes in the infarcted zone be visualised by means of M-mode scans. Which degree of accuracy can be achieved, if attempts are made to establish an echocardiographic diagnosis on the basis of M-mode scans in order to confirm regional contractility disorders revealed by ventriculography. (orig./MG) [de

  1. The cardiomyopathy in Friedreich's ataxia: isotopic ventriculography and myocardial imaging with thallium-201

    International Nuclear Information System (INIS)

    Therriault, L.; Lamoureux, G.; Cote, M.; Plourde, G.; Lemieux, B.

    1984-01-01

    Myocardial scanning after the intravenous administration of Thallium 201 was used to evaluate regional myocardial perfusion in 14 patients with Friedreich's ataxia. Isotopic ventriculography was also used to assess left ventricular contractility. Myocardial images in patients with Friedreich's ataxia were found to be precociously abnormal irrespective of the degree of neurological impairment or of the severity of myocardial hypertrophy

  2. Radionuclide ventriculography for evaluation of left ventricular function in patients after myocardial infarction

    International Nuclear Information System (INIS)

    Sledzevskaya, I.K.; Stroganova, N.P.; Il'yash, M.G.

    1989-01-01

    The use of an expanded set of parameters of radionuclide ventriculography with 99m Tc-prtechnetate, characterizing myocardial function, made it possible to specify radionuclide semiotics of myocardial infarction, to identify 4 cardiodynamic types, and to establish correlation between a degree of cardiodynamic changes and a site of lesion, and the relationship with exercise tolerance

  3. Estimation of single plane unbalance parameters of a rotor-bearing system using Kalman filtering based force estimation technique

    Science.gov (United States)

    Shrivastava, Akash; Mohanty, A. R.

    2018-03-01

    This paper proposes a model-based method to estimate single plane unbalance parameters (amplitude and phase angle) in a rotor using Kalman filter and recursive least square based input force estimation technique. Kalman filter based input force estimation technique requires state-space model and response measurements. A modified system equivalent reduction expansion process (SEREP) technique is employed to obtain a reduced-order model of the rotor system so that limited response measurements can be used. The method is demonstrated using numerical simulations on a rotor-disk-bearing system. Results are presented for different measurement sets including displacement, velocity, and rotational response. Effects of measurement noise level, filter parameters (process noise covariance and forgetting factor), and modeling error are also presented and it is observed that the unbalance parameter estimation is robust with respect to measurement noise.

  4. Assessment of right ventricular function with nonimaging first pass ventriculography and comparison of results with gamma camera studies.

    Science.gov (United States)

    Zhang, Z; Liu, X J; Liu, Y Z; Lu, P; Crawley, J C; Lahiri, A

    1990-08-01

    A new technique has been developed for measuring right ventricular function by nonimaging first pass ventriculography. The right ventricular ejection fraction (RVEF) obtained by non-imaging first pass ventriculography was compared with that obtained by gamma camera first pass and equilibrium ventriculography. The data has demonstrated that the correlation of RVEFs obtained by the nonimaging nuclear cardiac probe and by gamma camera first pass ventriculography in 15 subjects was comparable (r = 0.93). There was also a good correlation between RVEFs obtained by the nonimaging nuclear probe and by equilibrium gated blood pool studies in 33 subjects (r = 0.89). RVEF was significantly reduced in 15 patients with right ventricular and/or inferior myocardial infarction compared to normal subjects (28 +/- 9% v. 45 +/- 9%). The data suggests that nonimaging probes may be used for assessing right ventricular function accurately.

  5. Mosaicing of single plane illumination microscopy images using groupwise registration and fast content-based image fusion

    Science.gov (United States)

    Preibisch, Stephan; Rohlfing, Torsten; Hasak, Michael P.; Tomancak, Pavel

    2008-03-01

    Single Plane Illumination Microscopy (SPIM; Huisken et al., Nature 305(5686):1007-1009, 2004) is an emerging microscopic technique that enables live imaging of large biological specimens in their entirety. By imaging the living biological sample from multiple angles SPIM has the potential to achieve isotropic resolution throughout even relatively large biological specimens. For every angle, however, only a relatively shallow section of the specimen is imaged with high resolution, whereas deeper regions appear increasingly blurred. In order to produce a single, uniformly high resolution image, we propose here an image mosaicing algorithm that combines state of the art groupwise image registration for alignment with content-based image fusion to prevent degrading of the fused image due to regional blurring of the input images. For the registration stage, we introduce an application-specific groupwise transformation model that incorporates per-image as well as groupwise transformation parameters. We also propose a new fusion algorithm based on Gaussian filters, which is substantially faster than fusion based on local image entropy. We demonstrate the performance of our mosaicing method on data acquired from living embryos of the fruit fly, Drosophila, using four and eight angle acquisitions.

  6. Evaluation of segmental left ventricular wall motion by equilibrium gated radionuclide ventriculography.

    Science.gov (United States)

    Van Nostrand, D; Janowitz, W R; Holmes, D R; Cohen, H A

    1979-01-01

    The ability of equilibrium gated radionuclide ventriculography to detect segmental left ventricular (LV) wall motion abnormalities was determined in 26 patients undergoing cardiac catheterization. Multiple gated studies obtained in 30 degrees right anterior oblique and 45 degrees left anterior oblique projections, played back in a movie format, were compared to the corresponding LV ventriculograms. The LV wall in the two projections was divided into eight segments. Each segment was graded as normal, hypokinetic, akinetic, dyskinetic, or indeterminate. Thirteen percent of the segments in the gated images were indeterminate; 24 out of 27 of these were proximal or distal inferior wall segments. There was exact agreement in 86% of the remaining segments. The sensitivity of the radionuclide technique for detecting normal versus any abnormal wall motion was 71%, with a specificity of 99%. Equilibrium gated ventriculography is an excellent noninvasive technique for evaluating segmental LV wall motion. It is least reliable in assessing the proximal inferior wall and interventricular septum.

  7. Right ventriculography as a valid method for the diagnosis of tricuspid insufficiency.

    Science.gov (United States)

    Ubago, J L; Figueroa, A; Colman, T; Ochoteco, A; Rodríguez, M; Durán, C M

    1981-01-01

    The value of right ventriculography in the diagnosis of tricuspid insufficiency (TI) is often questioned because of 1) the high incidence of premature ventricular contractions (PVCs) during injections and 2) interference of the catheter in the valve closure mechanism. In 168 patients a commercially available, not preshaped, balloon-tipped catheter was used for right ventriculography. To avoid the induction of PVCs, the catheter tip was placed in the middle third of the diafragmatic wall of the right ventricle, and the balloon was inflated, becoming trapped by the trabeculae. In this position the catheter's side holes should be located in the inflow chamber. To ensure this correct position, and therefore lack of ectopic beats during angiography, a saline test injection was performed previously in every case. With this technique the incidence of PVCs during ventriculography was only 7.7%. In all but one case, such beats were isolated. The 168 patients were divided into three groups according to their likelihood of experiencing tricuspid interference by the catheter: group 1 included 41 patients with a normal heart or with coronary artery disease. No one from this group had TI. Of group II, 28 patients with right ventricular pressure or volume overload or cardiomyopathy, only 2 had TI, both with a previous clinical diagnosis of regurgitation. Group III contained 99 patients with rheumatic heart disease. Thirty-five of them showed angiographic TI, and 24 of these had this diagnosis confirmed either clinically or at surgery. It is felt that this technique of right ventriculography, with its low incidence of PVCs and slight interference with tricuspid closure, is a valid method for the objective study of the tricuspid valve.

  8. Positive ventriculography and computer assisted tomography of the skull in the evaluation of megalocephaly in newborns and infants

    International Nuclear Information System (INIS)

    Kellermann, K.; Heuser, L.; Bliesener, J.A.

    1979-01-01

    To clarify indications and limits of computer assisted tomography and positive ventriculography the results of both methods were compared with each other retrospectively in 55 macrocephalic newborns and infants. It could be shown that positive ventriculography, even if combined with coronal views, was superseded by computer assisted tomography to only a certain extent. To complete the appropriate diagnosis preoperatively positive ventriculography was necessary most often in patients with paranatal disturbances who had undergone intensive care treatment. The non-invasive method of computer assisted tomography often yielded sufficient information on localisation, size, and nature of the underlying pathologic process. Both methods turned out to be complementary when topographical and functional interrelations of cranial cysts were to be analysed, or when anatomical details had to be demonstrated, especially structures of the midline and of the posterior fossa, which could not be visualized by computer assisted tomography alone. (orig.) [de

  9. Assessment of sistemic ventricle function in corrected transposition of great arteries with Gated SPECT: comparison with radionuclide ventriculography

    International Nuclear Information System (INIS)

    Alexanderson, E.; Espinola, N.; Duenas, D.; Fermon, S.; Acevedo, C.; Martinez, C.

    2002-01-01

    Corrected trasposition of great arteries is a uncommon congenital heart disease where the right ventricle works as the sistemic one. QGS Gated SPECT program was designed to recognize the contours of left ventricle being a good method to evaluate left ventricle ejection fraction. The purpose of this study was to evaluate the right ventricle ejection fraction (RVEF) by gated SPECT using Tc-99mSestaMIBI in comparison with radionuclide ventriculography (RVG) in patients with corrected trasposition of great arteries. Methods: We performed gated SPECT and radionuclide ventriculography within 15 days of each other in 7 adults consecutive patients with the diagnosis of corrected trasposition of great arteries (5 men, 2 women; mean age 47 y). Gated tomographic data, including ventricular volumes and ejection fraction, were processed using QGS automatic algorithm, whereas equilibrium radionuclide ventriculography used standard techniques. Results: We found a good correlation between right ventricle ejection fraction obtained with Gated SPECT compared with equilibrium radionuclide ventriculography. The mean of the RVEF with Gated SPECT was 41.2% compared with 44.2% of RVEF with equilibrium radionuclide ventriculography. Both methods recognized abnormal RVEF in 5 patients ( 50%) with Gated SPECT and abnormal with RVG meanwhile another patient had normal RVEF with RVG and abnormal with Gated SPECT. Conclusion: Quantitative gated tomography, using Tc 99mSestaMIBI, has a good correlation with radionuclide ventriculography for the assessment of right ventricle ejection fraction in patients with corrected trasposition of great arteries. These results support the clinical use of this technique among these patients

  10. Magnetic resonance ventriculography with gadolinium DTPA: report of two cases

    International Nuclear Information System (INIS)

    Siebner, H.R.; Einsiedel, H. von; Conrad, B.

    1997-01-01

    We report intrathecal use of gadolinium DTPA for MRI of the cerebrospinal fluid (CSF). In two patients with leptomeningeal carcinomatosis, we injected 0.01 mmol gadolinium DTPA into the lateral ventricle via an Ommaya device. Coronal T1-weighted images of the head were obtained at 0.2 T prior to and after injection. There was pronounced enhancement of CSF close to the injection site, allowing good delineation of CSF and surrounding brain tissue. No side effects occurred. MRI with intrathecal administration of highly diluted gadolinium DTPA may be a promising alternative to conventional investigation of CSF-filled cavities using iodinated X-ray contrast media or radionuclides. (orig.). With 3 figs

  11. Phase changes caused by hyperventilation stress in spastic angina pectoris analyzed by first-pass radionuclide ventriculography

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jin; Takeda, Tohoru; Ajisaka, Ryuichi; Masuoka, Takeshi; Watanabe, Sigeyuki; Sato, Motohiro; Itai, Yuji [Tsukuba Univ., Ibaraki (Japan). Inst. of Clinical Medicine; Toyama, Hinako; Ishikawa, Nobuyoshi

    1999-02-01

    To understand the effect of hyperventilation (HV) stress in patients with spastic angina, left ventricular (LV) contraction was analyzed by quantitative phase analysis. The study was performed on 36 patients with spastic angina pectoris, including vasospastic angina pectoris (VspAP: 16 patients) and variant angina pectoris (VAP: 20 patients). First-pass radionuclide ventriculography (first-pass RNV) was performed at rest and after HV stress, and standard deviation of the LV phase distribution (SD) was analyzed. The SD was lower in patients with VspAP than in VAP(12.8{+-}1.4 degrees vs. 14.6{+-}2.2 degrees, p<0.005) at rest. After HV stress, the SD (HVSD) tended to increase in VspAP patients (62.5%), whereas the SD decreased in VAP patients (70%). Due to HV stress, the percentage change in SD (%SD) in VspAP patients was 8.9{+-}23.7% whereas that in VAP patients was -9.1{+-}17.3% (p<0.01). Moreover, phase histograms were divided into HVSD increase and HVSD decrease groups. The HVSD increase group had a decrease of HVEF, but the HVSD decrease group tended to have more decreased HVEF than the HVSD increase group. These results indicate that spastic angina pectoris patients show various responses to HV stress. The HVSD increase group might have additional myocardial ischemia due to regional coronary spasm. In contrast, in the HVSD decrease group severe LV dysfunction or diffuse wall motion abnormality might have been generated, and this caused a reduction in the SD value. Phase analysis would therefore add new information regarding electrocardiographically silent myocardial ischemia due to coronary spasm, and HV stress might increase sensitivity for the detection of abnormalities in quantitative phase analysis, especially in VspAP patients. (author)

  12. Quantitative Computed Tomography Ventriculography for Assessment and Monitoring of Hydrocephalus: A Pilot Study and Description of Method in Subarachnoid Hemorrhage.

    Science.gov (United States)

    Multani, Jasjit Singh; Oermann, Eric Karl; Titano, Joseph; Mascitelli, Justin; Nicol, Kelly; Feng, Rui; Skovrlj, Branko; Pain, Margaret; Mocco, J D; Bederson, Joshua B; Costa, Anthony; Shrivastava, Raj

    2017-08-01

    There is no facile quantitative method for monitoring hydrocephalus (HCP). We propose quantitative computed tomography (CT) ventriculography (qCTV) as a novel computer vision tool for empirically assessing HCP in patients with subarachnoid hemorrhage (SAH). Twenty patients with SAH who were evaluated for ventriculoperitoneal shunt (VPS) placement were selected for inclusion. Ten patients with normal head computed tomography (CTH) findings were analyzed as negative controls. CTH scans were segmented both manually and automatically (by qCTV) to generate measures of ventricular volume. The median manually calculated ventricular volume was 36.1 cm 3 (interquartile range [IQR], 30-115 cm 3 ), which was similar to the median qCTV measured volume of 37.5 cm 3 (IQR, 32-118 cm 3 ) (P = 0.796). Patients undergoing VPS placement demonstrated an increase in median ventricular volume on qCTV from 21 cm 3 to 40 cm 3 on day T-2 and to 51 cm 3 by day 0, a change of 144%. This is in contrast to patients who did not require shunting, in whom median ventricular volume decreased from 16 cm 3 to 14 cm 3 on day T-2 and to 13 cm 3 by day 0, with an average overall volume decrease 19% (P = 0.001). The average change in ventricular volume predicted which patients would require VPS placement, successfully identifying 7 of 10 patients (P = 0.004). Using an optimized cutoff of a change in ventricular volume of 2.5 cm 3 identified all patients who went on to require VPS placement (10 of 10; P = 0.011). qCTV is a reliable means of quantifying ventricular volume and hydrocephalus. This technique offers a new tool for monitoring neurosurgical patients for hydrocephalus, and may be beneficial for use in future research studies, as well as in the routine care of patients with hydrocephalus. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Phase changes caused by hyperventilation stress in spastic angina pectoris analyzed by first-pass radionuclide ventriculography

    International Nuclear Information System (INIS)

    Wu, Jin; Takeda, Tohoru; Ajisaka, Ryuichi; Masuoka, Takeshi; Watanabe, Sigeyuki; Sato, Motohiro; Itai, Yuji; Toyama, Hinako; Ishikawa, Nobuyoshi

    1999-01-01

    To understand the effect of hyperventilation (HV) stress in patients with spastic angina, left ventricular (LV) contraction was analyzed by quantitative phase analysis. The study was performed on 36 patients with spastic angina pectoris, including vasospastic angina pectoris (VspAP: 16 patients) and variant angina pectoris (VAP: 20 patients). First-pass radionuclide ventriculography (first-pass RNV) was performed at rest and after HV stress, and standard deviation of the LV phase distribution (SD) was analyzed. The SD was lower in patients with VspAP than in VAP(12.8±1.4 degrees vs. 14.6±2.2 degrees, p<0.005) at rest. After HV stress, the SD (HVSD) tended to increase in VspAP patients (62.5%), whereas the SD decreased in VAP patients (70%). Due to HV stress, the percentage change in SD (%SD) in VspAP patients was 8.9±23.7% whereas that in VAP patients was -9.1±17.3% (p<0.01). Moreover, phase histograms were divided into HVSD increase and HVSD decrease groups. The HVSD increase group had a decrease of HVEF, but the HVSD decrease group tended to have more decreased HVEF than the HVSD increase group. These results indicate that spastic angina pectoris patients show various responses to HV stress. The HVSD increase group might have additional myocardial ischemia due to regional coronary spasm. In contrast, in the HVSD decrease group severe LV dysfunction or diffuse wall motion abnormality might have been generated, and this caused a reduction in the SD value. Phase analysis would therefore add new information regarding electrocardiographically silent myocardial ischemia due to coronary spasm, and HV stress might increase sensitivity for the detection of abnormalities in quantitative phase analysis, especially in VspAP patients. (author)

  14. Normal left ventricular emptying in coronary artery disease at rest: analysis by radiographic and equilibrium radionuclide ventriculography

    International Nuclear Information System (INIS)

    Denenberg, B.S.; Makler, P.T.; Bove, A.A.; Spann, J.F.

    1981-01-01

    The volume ejected early in systole has been proposed as an indicator of abnormal left ventricular function that is present at rest in patients with coronary artery disease with a normal ejection fraction and normal wall motion. The volume ejected in systole was examined by calculating the percent change in ventricular volume using both computer-assisted analysis of biplane radiographic ventriculograms at 60 frames/s and equilibrium gated radionuclide ventriculograms. Ventricular emptying was examined with radiographic ventriculography in 33 normal patients and 23 patients with coronary artery disease and normal ejection fraction. Eight normal subjects and six patients with coronary artery disease had both radiographic ventriculography and equilibrium gated radionuclide ventriculography. In all patients, there was excellent correlation between the radiographic and radionuclide ventricular emptying curves (r . 0.971). There were no difference in the ventricular emptying curves of normal subjects and patients with coronary artery disease whether volumes were measured by radiographic or equilibrium gated radionuclide ventriculography. It is concluded that the resting ventricular emptying curves are identical in normal subjects and patients with coronary artery disease who have a normal ejection fraction and normal wall motion

  15. Rest and exercise radionuclide ventriculography in the ambulatory monitoring of patients with valvular heart disease

    Energy Technology Data Exchange (ETDEWEB)

    Raichlen, J.S.; Brest, A.N.

    1988-01-01

    Radionuclide angiography serves as a valuable adjunct in the noninvasive evaluation and monitoring of patients with valvular heart disease. Although estimations of regurgitant fractions and the differences between left and right ventricular stroke volumes can be made, the limitations of the techniques do not enable adequate quantitation of the severity of valvular insufficiency to warrant routine use in ambulatory management. The importance of radionuclide ventriculography, however, lies in its ability to examine global ventricular function both at rest and with exercise, thus enabling assessment of the functional reserve of the left and right ventricles. Such data are of considerable value in determining the need for invasive evaluation and the timing of valve replacement in patients with valvular heart disease. 41 references.

  16. Rest and exercise radionuclide ventriculography in the ambulatory monitoring of patients with valvular heart disease

    International Nuclear Information System (INIS)

    Raichlen, J.S.; Brest, A.N.

    1988-01-01

    Radionuclide angiography serves as a valuable adjunct in the noninvasive evaluation and monitoring of patients with valvular heart disease. Although estimations of regurgitant fractions and the differences between left and right ventricular stroke volumes can be made, the limitations of the techniques do not enable adequate quantitation of the severity of valvular insufficiency to warrant routine use in ambulatory management. The importance of radionuclide ventriculography, however, lies in its ability to examine global ventricular function both at rest and with exercise, thus enabling assessment of the functional reserve of the left and right ventricles. Such data are of considerable value in determining the need for invasive evaluation and the timing of valve replacement in patients with valvular heart disease. 41 references

  17. Possibilities of exercise radionuclide ventriculography carried out in equilibrium in the detection of ischaemic heart disease

    Energy Technology Data Exchange (ETDEWEB)

    Csernay, L.; Mester, J.; Edes, I.; Pavics, L.; Gruber, N.; Szasz, K.; Csanady, M.

    1985-08-04

    Authors give account of the initiation of the exercise radionuclide ventriculography and of their diagnostic experiences. In 33 control persons and 20 patients with coronary heart disease verified with coronarography, the left ventricular ejection fraction, the wall motion and the systolic and diastolic volume of the left ventricle were examined at rest and during exercise. A decrease or an increase of not more than 5% of ejection fraction, the exercise induced wall motion abnormalities or an increase of resting wall motion disorder were interpreted as an index of underlying significant coronary stenosis. A sensitivity of 90% and a specificity of 88% of the method were found. Upon the results, which are in good agreement with literary data, the initiation of the method in nuclear medical laboratories equipped with camera-computer system is proposed

  18. Possibilities of exercise radionuclide ventriculography carried out in equilibrium in the detection of ischaemic heart disease

    International Nuclear Information System (INIS)

    Csernay, Laszlo; Mester, Janos; Edes, Istvan; Pavics, Laszlo; Gruber, Noemi; Szasz, Karoly; Csanady, Miklos

    1985-01-01

    Authors give account of the initiation of the exercise radionuclide ventriculography and of their diagnostic experiences. In 33 control persons and 20 patients with coronary heart disease verified with coronarography, the left ventricular ejection fraction, the wall motion and the systolic and diastolic volume of the left ventricle were examined at rest and during exercise. A decrease or an increase of not more than 5% of ejection fraction, the exercise induced wall motion abnormalities or an increase of resting wall motion disorder were interpreted as an index of underlying significant coronary stenosis. A sensitivity of 90% and a specificity of 88% of the method were found. Upon the results, which are in good agreement with literary data, the initiation of the method in nuclear medical laboratories equipped with camera-computer system is proposed. (author)

  19. Importance of adequate exercise in the detection of coronary heart disease by radionuclide ventriculography

    International Nuclear Information System (INIS)

    Brady, T.J.; Thrall, J.H.; Lo, K.; Pitt, B.

    1980-01-01

    Rest and exercise radionuclide ventriculograms were obtained on 77 symptomatic patients without prior documented coronary artery disease (CAD). Coronary artery disease was present by angiograms in 48. Radionuclide ventriculography (RNV) was abnormal in 41 patients (overall sensitivity 85%). In 29 patients with normal coronary arteries, RNV was normal in 24 (specificity 83%). To determine if the exercise level affects sensitivity, the studies were graded for adequacy of exercise. It was considered adequate if patients developed (a) chest pain, or (b) ST segment depression of at least 1 mm, or (c) if they achieved a pressure rate product greater than 250. Among the 48 patients with coronary artery disease, 35 achieved adequate exercise. Thirty-three had an abnormal RNV (sensitivity 94%). In 13 patients who failed to achieve adequate exercise, RNV was abnormal in eight (sensitivity of only 62%). Some patients with coronary artery disease may have a normal ventricular response at inadequate levels of stress

  20. Analysis of cardiac images of radionuclide ventriculography in AT-Type personal computer

    International Nuclear Information System (INIS)

    Lillo, R.; Gonzalez, P.; Ehijo, A.; Otarola, T.M.S.; Ortiz, M.; Silva, A.M.; Ortiz, M.

    1990-01-01

    The goal of this research was to produce software for the processing of Cardiac Phase images in personal computers. The results of standard radionuclide Ventriculography and Fourier analysis, got on gamma camera Ohio Nuclear 410 Sygma and Digital PDP 11/34 computer were coded into ASCII file and then transfered via Smarterm 220/Kermit to an Accel 900 AT PC. After decoding the images they were processed with a program develope in C Lenguaje obtaining the values of Phase Angles in the whole phase images and in regions of interest drawn around the cardiac chambers. The images and values were the same as those obtained by conventional processing in the PDP 11/34 computer. This is considered a first stage for the use of PC to Nuclear Medicine imaging studies. (author)

  1. A prospective comparison between three-dimensional magnetic resonance imaging and ventriculography for target-coordinate determination in frame-based functional stereotactic neurosurgery

    NARCIS (Netherlands)

    Schuurman, P. R.; de Bie, R. M.; Majoie, C. B.; Speelman, J. D.; Bosch, D. A.

    1999-01-01

    OBJECT: The purpose of this prospective study was to compare stereotactic coordinates obtained with ventriculography with coordinates derived from stereotactic computer-reconstructed three-dimensional magnetic resonance (3D-MR) imaging in functional stereotactic procedures. METHODS: In 15

  2. Relative value of clinical variables, bicycle ergometry, rest radionuclide ventriculography and 24 hour ambulatory electrocardiographic monitoring at discharge to predict 1 year survival after myocardial infarction

    NARCIS (Netherlands)

    P.M. Fioretti (Paolo); R.W. Brower (Ronald); M.L. Simoons (Maarten); H.J. ten Katen (Harald); A. Beelen (Anita); T. Baardman (Taco); J. Lubsen (Jacob); P.G. Hugenholtz (Paul)

    1986-01-01

    textabstractThe relative value of predischarge clinical variables, bicycle ergometry, radionuclide ventriculography and 24 hour ambulatory electrocardiographic monitoring for predicting survival during the first year in 351 hospital survivors of acute myocardial infarction was assessed. Discriminant

  3. Intervertebral anticollision constraints improve out-of-plane translation accuracy of a single-plane fluoroscopy-to-CT registration method for measuring spinal motion

    International Nuclear Information System (INIS)

    Lin, Cheng-Chung; Tsai, Tsung-Yuan; Hsu, Shih-Jung; Lu, Tung-Wu; Shih, Ting-Fang; Wang, Ting-Ming

    2013-01-01

    Purpose: The study aimed to propose a new single-plane fluoroscopy-to-CT registration method integrated with intervertebral anticollision constraints for measuring three-dimensional (3D) intervertebral kinematics of the spine; and to evaluate the performance of the method without anticollision and with three variations of the anticollision constraints via an in vitro experiment. Methods: The proposed fluoroscopy-to-CT registration approach, called the weighted edge-matching with anticollision (WEMAC) method, was based on the integration of geometrical anticollision constraints for adjacent vertebrae and the weighted edge-matching score (WEMS) method that matched the digitally reconstructed radiographs of the CT models of the vertebrae and the measured single-plane fluoroscopy images. Three variations of the anticollision constraints, namely, T-DOF, R-DOF, and A-DOF methods, were proposed. An in vitro experiment using four porcine cervical spines in different postures was performed to evaluate the performance of the WEMS and the WEMAC methods. Results: The WEMS method gave high precision and small bias in all components for both vertebral pose and intervertebral pose measurements, except for relatively large errors for the out-of-plane translation component. The WEMAC method successfully reduced the out-of-plane translation errors for intervertebral kinematic measurements while keeping the measurement accuracies for the other five degrees of freedom (DOF) more or less unaltered. The means (standard deviations) of the out-of-plane translational errors were less than −0.5 (0.6) and −0.3 (0.8) mm for the T-DOF method and the R-DOF method, respectively. Conclusions: The proposed single-plane fluoroscopy-to-CT registration method reduced the out-of-plane translation errors for intervertebral kinematic measurements while keeping the measurement accuracies for the other five DOF more or less unaltered. With the submillimeter and subdegree accuracy, the WEMAC method was

  4. Contrast agents for cardiac angiography: effects of a nonionic agent vs. a standard ionic agent

    International Nuclear Information System (INIS)

    Bettmann, M.A.; Bourdillon, P.D.; Barry, W.H.; Brush, K.A.; Levin, D.C.

    1984-01-01

    The effects on cardiac hemodynamics and of a standard contrast agent, sodium methylglucamine diatrizoate [Renografin 76] were compared with the effects of a new nonionic agent (iohexol) in a double-blind study in 51 patietns undergoing coronary angiography and left ventriculography. No significant alteration in measured blood parameters occurred with either contrast agent. Hemodynamic changes occurred with both, but were significantly greater with the standard renografin than with the low-osmolality, nonionic iohexol. After left ventriculography, heart rate increased and peripheral arterial pressure fell with both agents, but less with iohexol. It is concluded that iohexol causes less alteration in cardiac function than does the agent currently most widely used. Nonionic contrast material is likely to improve the safety of coronary angiography, particularly in those patients at greatest risk

  5. Validity of the accuracy of right ventricular volume measurement with single plane Simpson's rule based on a new half-circle model

    International Nuclear Information System (INIS)

    Cui Wei

    2003-01-01

    Objective: Right ventricular volume calculation is the basis of right ventricular function evaluation. The complexity of right ventricular shape makes it more difficult for measuring right ventricular volume, and therefore limits the widespread use of right ventricular function assessment. However, the short-axis view of the right ventricle is usually crescent, and might be assumed as half of a circle. This hypothesis can be applied to calculate right ventricular volume by using the plane Simpson's rule, but the final right ventricular volume should be about half of the original calculated value. The aim of this study was to test the accuracy of right ventricular volume measurement based on this new assumption in human right ventricular casts. Methods: Fifteen human right ventricular casts were obtained within 24 hours after death from 15 subjects who did not have overt cardiac disease. These casts were scanned with Toshiba multislice helical CT (Aquilion) using a scanning protocol similar to clinical practice. Right ventricular sagittal MPR images that correspond to right anterior oblique view were reconstructed later and single-plane Simpson's method was used to calculate right ventricular volumes. The calculated right ventricular volume was defined as the original calculated value divided by 2. The actual right ventricular casts volumes were determined by water displacement method. Results: The actual right ventricular volume was (64.23±24.51) ml, while the calculated volume was (53.18±26.22) ml. The calculated right ventricular volume significantly underestimated the actual volume by (11.05±13.09) ml (t=3.27, P=0.006). However, there was a close correlation between the actual cast volume and the calculated volume (r=0.869, P<0.001), with a regression equation of RV actual volume=21.04+0.812 x RV calculated volume. Conclusion: Right ventricular volume could be calculated accurately with single-plane Simpson's rule based on our new proposed half

  6. Characteristics of 201Tl myocardial SPECT and left ventriculography in patients with acute diagonal branch myocardial infarction

    International Nuclear Information System (INIS)

    Tanaka, Takeshi; Aizawa, Tadanori; Katou, Kazuzo; Ogasawara, Ken; Kirigaya, Hajime

    1993-01-01

    Characteristics of 201 Tl myocardial SPECT and ventriculography were studied in 13 patients with acute diagonal branch myocardial infarction. Rest 201 Tl myocardial SPECT and left ventriculography were underwent in chronic phase. In 5 patients electrocardiogram (ECG) changes in acute phase were not definite. In 6 patients it was difficult to identify the obstructed coronary artery with coronary angiography in acute phase. Mean value of maximum creatine phosphokinese (CPK) was 854 (458-1,774) U/l. It seemed to be difficult to diagnose acute diagonal branch myocardial infarction with ECG and/or coronary angiography. In all patients defects were noted on 201 Tl SPECT. Defects were small and noted in the central anterior wall and not in the septum. In 2 patients defects were noted at apex. In left ventriculography dyskinetic motion was noted in 10 patients; one patient showed apical aneurysm and 3 patients showed anterior wall aneurysm. In 3 patients anterior wall showed akinesis. It was concluded that 201 Tl myocardial SPECT were useful for detecting diagonal branch lesion. In case of diagonal branch myocardial infarction size of defects were small and defects were not noted in the septum, however aneurysmal motion was frequently noted. (author)

  7. Problems in clinical assessment of left ventricular peak filling rate with radionuclide ventriculography

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, Yoshio; Kim, Bong-Ha; Tsuneoka, Yutaka

    1987-02-01

    With an increased clinical application of early peak diastolic filling rate (PFR) using radionuclide ventriculography, problems of its clinical significance have emerged. The study was designed to answer the following questions: 1) accuracy of PFR measurement, 2) normalization of PFR, and 3) whether PFR may reflect left ventricular relaxation rate (LVRR). In measuring PFR, an elevated framing rate was required, and the optimal rate was 20 msec/F. Second sound heart gating technique proved to be complementary to conventional ECG R wave gating technique in the evaluation of left ventricular diastolic volume curves and mean filling rate associated with changes in the range of R-R interval. PFR which was normalized with end-diastolic volume (EDV) did not necessarily reflect measured PFR because of individual differences of EDV. An experiment on the relationship of mitral valve pressure to blood flow in dogs revealed that PFR was influenced by not only LVRR but also left atrial pressure. These results may raise a question of the rationale for using the measurement of PFR, as well as its technical problems, in the objective evaluation of LVRR. (Namekawa, K.).

  8. Effects of AV delay programming on ventricular resynchronisation: role of radionuclide ventriculography

    Energy Technology Data Exchange (ETDEWEB)

    Siegrist, Patrick T.; Comte, Nathalie; Holzmeister, Johannes; Suetsch, Gabor; Koepfli, Pascal; Namdar, Mehdi; Duru, Firat; Brunckhorst, Corinna; Scharf, Christoph [Universitiy Hospital Zurich NUK C 32, Cardiovascular Center, Zurich (Switzerland); Kaufmann, Philipp A. [Universitiy Hospital Zurich NUK C 32, Cardiovascular Center, Zurich (Switzerland); University of Zurich, Zurich Center for Integrative Human Physiology, Zurich (Switzerland)

    2008-08-15

    Optimal atrioventricular delay (AVD) setting for cardiac resynchronisation therapy, i.e. biventricular pacing in patients with heart failure, remains a formidable challenge. Thus, the purpose of this study was to evaluate the effects of different AVD on inter- and intra-ventricular resynchronisation using phase histograms of radionuclide ventriculography (RNV). In 17 consecutive patients (mean age 64 {+-} 6 years), RNV was performed 236 {+-} 350 days after pacemaker implantation for cardiac resynchronisation therapy. Images were acquired during atrial pacing at 80 bpm and during biventricular pacing with AVD ranging from 80 to 160 ms. Inter-ventricular dyssynchrony was measured by the delay between the mean phase angles of the left and right ventricles. Intra-ventricular dyssynchrony was measured by the standard deviation (SD) of left ventricular phase histograms. Left ventricular (LV) ejection fraction (EF) was inversely correlated to LV dyssynchrony (SD of LV phase histogram, R = -0.82, p < 0.0001). However, the increase in LVEF by biventricular pacing (mean +4.4 {+-} 4%) showed only modest correlation to the resulting resynchronisation effect (characterised by a -13 {+-} 8 decrease in LV phase histogram SD, R = -0.38, p < 0.0001). RNV is helpful in optimising pacing parameters for resynchronisation therapy. Varying AVD did not have a major impact on intra- or inter-ventricular resynchronisation. Thus, the benefit of AVD-based LVEF optimisation seems to result from atrioventricular resynchronisation. (orig.)

  9. Regional rates of myocardial fatty acid metabolism: Comparison with coronary angiography and ventriculography

    International Nuclear Information System (INIS)

    Schad, N.; Vattimo, A.; Bertelli, P.

    1990-01-01

    In 50 patients, 1 mCi 123 I phenylpentadecanoic acid (IPPA) was injected at peak ergometric stress and 1500 frames were acquired (1 frame/s) with a high count rate gamma camera. Parametric images of rates of decrease and increase for different time intervals after stress were compared with coronary angiography and LV ventriculography, separately evaluating the 3 main coronary territories: 18/150 territories supplied by normal coronaries presented rather homogeneous regional clearing rates, whereas a gradual decrease in clearing rates towards the end of the territory (frequently with peripheral defects) was seen in all 87/150 territories with significant coronary narrowing. In local correspondence to clearing defects, initial IPPA accumulations could be observed with later onset of clearing between 10 and 25 min. In all 44/150 territories presented abnormal clearing rates, mostly with a patchy pattern, with normal coronary anatomy, but all except one had LV dysfunction and a clinical diagnosis of cardiomyopathy, diabetes mellitus or hypertensive disease. Twenty four of the 41 patients with CAD had, in correspondence to a prior myocardial infarction, minimum or missing metabolic activity frequently in circumscribed zones, partly separated by bridges of still viable tissue with preserved but reduced clearing rates. (orig.)

  10. Regional rates of myocardial fatty acid metabolism: comparison with coronary angiography and ventriculography.

    Science.gov (United States)

    Schad, N; Wagner, R K; Hallermeier, J; Daus, H J; Vattimo, A; Bertelli, P

    1990-01-01

    In 50 patients, 1 mCi 123I phenylpentadecanoic acid (IPPA) was injected at peak ergometric stress and 1500 frames were acquired (1 frame/s) with a high count rate gamma camera. Parametric images of rates of decrease and increase for different time intervals after stress were compared with coronary angiography and LV ventriculography, separately evaluating the 3 main coronary territories: 18/150 territories supplied by normal coronaries presented rather homogeneous regional clearing rates, whereas a gradual decrease in clearing rates towards the end of the territory (frequently with peripheral defects) was seen in all 87/150 territories with significant coronary narrowing. In local correspondence to clearing defects, initial IPPA accumulations could be observed with later onset of clearing between 10 and 25 min. 44/150 territories presented abnormal clearing rates, mostly with a patchy pattern, with normal coronary anatomy, but all except one had LV dysfunction and a clinical diagnosis of cardiomyopathy, diabetes mellitus or hypertensive disease. Twenty four of the 41 patients with CAD had, in correspondence to a prior myocardial infarction, minimum or missing metabolic activity frequently in circumscribed zones, partly separated by bridges of still viable tissue with preserved but reduced clearing rates.

  11. Left ventricle expands maximally preceding end-diastole. Radionuclide ventriculography study

    International Nuclear Information System (INIS)

    Horinouchi, Osamu

    2002-01-01

    It has been considered that left ventricle (LV) expands maximally at the end-diastole. However, is it exactly coincident with this point? This study was aimed to determine whether the maximal expansion of LV coincides with the peak of R wave on electrocardiogram. Thirty-three angina pectoris patients with normal LV motion were examined using radionuclide ventriculography. Data were obtained from every 30 ms backward frame from the peak of R wave. All patients showed the time of maximal expansion preceded the peak of R wave. The intervals from the peak of R wave and the onset of P wave to maximal expansion of LV was 105±29 ms and 88±25 ms, respectively. This period corresponds to the timing of maximal excurtion of mitral valve by atrial contraction, and the centripetal motion of LV without losing its volume before end-diastole may be interpreted on account of the movement of mitral valve toward closure. These findings suggest that LV expands maximally between P and R wave after atrial contraction, preceding the peak of R wave thought conventionally as the end-diastole. (author)

  12. Clinical assessment of first pass radionuclide ventriculography after dipyridamole infusion in patients with coronary artery disease

    International Nuclear Information System (INIS)

    Kanaya, Tohru; Tono-oka, Ichiro; Satoh, Satoshi; Yamaguchi, Yoshiko; Hoshi, Hikaru; Ikeda, Kozue; Tsuiki, Kai; Yasui, Shoji; Komatani, Akio

    1986-01-01

    First pass radionuclide ventriculography (RNV) was performed after dipyridamole (D) infusion in 33 patients with coronary artery disease (CAD) and 15 normal volunteers. RNV findings after D infusion were compared with those of conventional exercise RNV and body surface ECG mapping (MAP). For patients with multiple vessel disease, left ventricular ejection fraction (LVEF) was significantly lower after D infusion than at rest. Wall motion abnormality (WMA) sites induced by D infusion were well coincident with those induced by exercise. Pressure rate product at exercise was significantly higher than that after D infusion, suggesting the different mechanism of the occurrence of WMA after D infusion and at exercise. The incidence of ischemic reaction tended to be higher after D infusion than at exercise in 25 patients with CAD. There was negative correlation between ST depression on MAP after D infusion and LVEF on RNV after D infusion. This RNV after D infusion can be used as a supplement tool to conventional exercise RNV in the evaluation of the degree of coronary artery lesions and preserved left ventricular function. (Namekawa, K.)

  13. Atrial pacing as an alternative to supine exercise (SE) in radionuclide ventriculography (RNV)

    International Nuclear Information System (INIS)

    Le Grand, V.; Wells, S.; O'Neil, W.W.; Jenkins, J.; Gross, M.D.; Vogel, R.

    1984-01-01

    Stress RNV is at times of limited value as many patients cannot achieve a sufficient pressure rate product (PRP). Atrial pacing is a noninvasive alternative to SE by bicycle ergometry. A swallowable electrode attached to a flexible wire is positioned in a retroatrial position in the esophagus and when connected to a variable output stimulator, variable rate (120, 140, 160 beats/min) atrial pacing ventriculography (APV) can be performed. RNV is performed in the sitting position at rest and at each pacing stage. APV was compared to SE RNV in 4 patients with coronary artery disease (CAD) and 3 normal volunteers (N). Tolerance to APV was excellent with adequate pacing. All subjects reported a minor sensation of chest burning. No arrhythmias occurred. At maximal APV mean PRP was 174 +- 26. The diastolic volumes in APV fell in all patients. Systolic volumes fell in N but not in CAD to APV. A flat EF response to APV was seen in both N and CAD patients. APV is an alternative to SE RNV although PRP remains low. Volume changes in APV are different than in SE RNV and in the interpretation of the results of APV in CAD, changes in systolic and diastolic volumes may be more important than the response of EF

  14. Automated system for ST segment and arrhythmia analysis in exercise radionuclide ventriculography

    International Nuclear Information System (INIS)

    Hsia, P.W.; Jenkins, J.M.; Shimoni, Y.; Gage, K.P.; Santinga, J.T.; Pitt, B.

    1986-01-01

    A computer-based system for interpretation of the electrocardiogram (ECG) in the diagnosis of arrhythmia and ST segment abnormality in an exercise system is presented. The system was designed for inclusion in a gamma camera so the ECG diagnosis could be combined with the diagnostic capability of radionuclide ventriculography. Digitized data are analyzed in a beat-by-beat mode and a contextual diagnosis of underlying rhythm is provided. Each beat is assigned a beat code based on a combination of waveform analysis and RR interval measurement. The waveform analysis employs a new correlation coefficient formula which corrects for baseline wander. Selective signal averaging, in which only normal beats are included, is done for an improved signal-to-noise ratio prior to ST segment analysis. Template generation, R wave detection, QRS window size, baseline correction, and continuous updating of heart rate have all been automated. ST level and slope measurements are computed on signal-averaged data. Arrhythmia analysis of 13 passages of abnormal rhythm by computer was found to be correct in 98.4 percent of all beats. 25 passages of exercise data, 1-5 min in length, were evaluated by the cardiologist and found to be in agreement in 95.8 percent in measurements of ST level and 91.7 percent in measurements of ST slope

  15. Effect of acute postinfusion lipemia and free fatty acids on myocardial contractility: Assessment with radionuclide ventriculography

    Energy Technology Data Exchange (ETDEWEB)

    Ackerman, L; Freeman, M L; Barnes, W E; Kaplan, E; Pacold, I; Loeb, H S; Johnson, B; Reid, R W

    1986-08-01

    Equilibrium gated radionuclide ventriculography was used to valuate the effect of intravenous fat-emulsion overload and excess of free fatty acids (FFA) on left ventricular ejection fraction (LVEF) in 20 patients with and without coronary artery disease (CAD). Fifteen of these patients had normal (>50%) baseline LVEF and 5 had low (<50%) baseline LVEF. From 100 to 150 ml of 20% artificial fat emulsion (Liposyn) was infused over 20-25 min. At the end of the infusion, triglyceridemia reached 820 +- 220 mg% and left ventricular ejection fraction decreased from baseline 62 +- 19% (mean +-SD) to 58 +- 16% (P < 0.05, paired t-test). After completion of Liposyn infusion, 5,000 U of heparin was administered intravenously and monitoring of LVEF was continued. One and one-half hours following heparin administration, plasma FFA levels reached 3.7 + 2.0 mmol/l and LVEF rose to 69 +- 19% (P < 0.001, paired t-test). Our data indicate that acute intravenous fat overload can suppress and high pathophysiologic levels of FFA can increase LVEF. This effect is more uniform and statistically more reliable in patients with normal LVEF. The study failed to demonstrate any significant difference in the effect of this pharmacologic intervention between patients with and without CAD.

  16. Clinical validation of the planar radionuclide ventriculography in patients with right ventricular dysfunction.

    Science.gov (United States)

    Bontemps, L; Merabet, Y; Chevalier, P; Itti, R

    2013-01-01

    Gated radionuclide ventriculography (RNV) may be used for the evaluation of the right ventricular function. However, the accuracy of the method should be clinically validated in patients suffering from diseases with specific pathology of the right ventricle (RV) and with possible left ventricular (LV) interaction. Three groups of 15 patients each, diagnosed with arrhythmogenic right ventricular dysplasia (ARVD), pulmonary artery hypertension (PAH) or atrial septal defect (ASD) were compared to a group of normal subjects. The parameters for both ventricles were evaluated separately (ejection fractions: LVEF and RVEF, and intraventricular synchronism quantified as phase standard deviation: LVPSD and RVPSD) as well as the relation or interdependence of the right to left ventricle (RV/LV volume ratio, LV/RV ejection fraction and stroke volume ratios, and interventricular synchronism). All the variables as a whole were analyzed to identify groups of patients according to their functional behaviour. Significant differences were found between the patients and control group for the RV function while the LV function remained mostly within normal limits. When the RV function was considered, the control group and ASD patient group showed differences regarding the ARVD and PAH patients. On evaluating the RV/LV ratios, differences were found between the control group and the ASD group. In the PAH patients, LV function showed differences in relation to the rest of the groups. RNV is a reliable clinical tool to evaluate RV function in patients with RV abnormality. Copyright © 2013 Elsevier España, S.L. and SEMNIM. All rights reserved.

  17. A study of the global and regional ventricle function using radionuclide ventriculography in the cases of patients with and without KHK under nitrate and placebo

    International Nuclear Information System (INIS)

    Kroth, B.

    1983-01-01

    In a controlled study of 74 patients with coronary heart disease (KHK) or without provable heart disease the ventricle function at rest and under ergonomic load before and after oral administration of nitrates, respectively placebos was studied with the help of radionuclide ventriculography. Radionuclide ventriculography proved itself thereby as a valuable method of high sensitivity for the recognition of KHK. The stress test increases the sensitivity and allows inferences to be made on the extent of the ischemia. The global function at rest is more a parameter for the functional restriction by infarct scars. A quantitative regional evaluation also makes possible the recognition of minor local changes. The additional study after nitrate administration allows a basis for the extent of reversibility in the stress-dependent functional restriction. The effects of a drug therapy become extrinsically presentable as a result of radionuclide ventriculography. (TRV) [de

  18. The value of exercise radionuclide ventriculography in risk stratification after coronary arterial bypass grafting

    International Nuclear Information System (INIS)

    Iskandrian, A.S.; Hakki, A.H.; Goel, I.P.; Mundth, E.D.; Kane, S.; Schenk, C.

    1985-01-01

    Cardiac events after coronary artery bypass surgery (CABG) may be related to left ventricular (LV) function, residual coronary artery diseases (CAD), graft occlusion, and progression of CAD. This study examined the value of rest and exercise (EX) radionuclide ventriculography (RNV) done 3-6 mos after CABG in risk stratification in 212 pts. There were 185 men and 27 women, aged 57 +- 8 years (mean +- SD). During a followup period of up to 4 years, (15 +- 10 months), there were 23 cardiac events; 13 pts died of cardiac causes and 20 had non-fatal acute myocardial infarctions. The pts with and without events did not differ in: clinical presentation after CABG (most were asymptomatic), medications and ECG findings at rest and EX. The pts with events had lower EX systolic blood pressure (p < 0.01); resting LV ejection fraction (EF) (p = 0.002), and EX EF (40 +- 18% vs 54 +- 16%, p = 0.002). The change in EF (rest to EX) was not significantly different (l.6 +- 8.2%, vs 2.1 +- 9.2%). Survival analysis (Cox model) identified the EX EF as the best predictor of death and total events (X/sup 2/ = 4.3 and 2.4, p = 0.04 and 0.07 respectively). Actuarial life table analysis showed that the risk increased as the EX EF decreased when pts were grouped into EX EF ≥ 50, 30-49, and <30%, (p < 0.001, Mantel-Cox). Thus, EX RNA is useful in risk stratification after CABG. The EX LVEF is an important descriptor that categorizes pts into different risks groups. The pts at high risk probably require more aggressive followup and continued medical therapy

  19. Multiplanar lumbopelvic control in patients with low back pain: is multiplanar assessment better than single plane assessment in discriminating between patients and healthy controls?

    Science.gov (United States)

    Nelson-Wong, E; Gallant, P; Alexander, S; Dehmer, K; Ingvalson, S; McClenahan, B; Piatte, A; Poupore, K; Davis, A M

    2016-02-01

    Patients with low back pain (LBP) commonly have lumbopelvic control deficits. Lumbopelvic assessment during sagittal motion is incorporated into commonly used clinical examination algorithms for Treatment Based Classification. The purpose of this study was to investigate whether combined assessment of lumbopelvic control during sagittal and frontal plane motion discriminates between people with and without LBP better than single plane assessment alone. Nineteen patients with LBP and 18 healthy control participants volunteered for this study. The active straight leg raise (ASLR) and active hip abduction (AHAbd) tests were used to assess lumbopelvic control during sagittal and frontal plane motion, respectively. The tests were scored as positive or negative using published scoring criteria. Contingency tables were created for each test alone and for the combined tests (both positive/both negative) with presence/absence of LBP as the reference standard to calculate accuracy statistics of sensitivity (sn), specificity (sp), likelihood (+LR and -LR), and diagnostic odds ratios (OR). Active straight leg raise and AHAbd tests alone had sn of 0·63, 0·74, respectively, sp of 0·61, 0·50, respectively, and OR of 2·7, 2·8, respectively. The combined tests had sn = 0·89, sp = 0·60, and OR = 12·0. Forty percent of patients with LBP had control deficits in both planes of motion. The AHAbd and ALSR tests appear to have greater diagnostic discrimination when used in combination than when used independently. A percentage of patients with LBP had control deficits in both planes, while others demonstrated uniplanar deficits only. These findings highlight the importance of multiplanar assessment in patients with LBP.

  20. Comparison of two-dimensional echocardiography with gated radionuclide ventriculography in the evaluation of global and regional left ventricular function in acute myocardial infarction

    International Nuclear Information System (INIS)

    Van Reet, R.E.; Quinones, M.A.; Poliner, L.R.; Nelson, J.G.; Waggoner, A.D.; Kanon, D.; Lubetkin, S.J.; Pratt, C.M.; Winters, W.L. Jr.

    1984-01-01

    Two-dimensional echocardiography and gated radionuclide ventriculography were performed in 93 patients (66 men, 27 women; mean age 61 years) with 95 episodes of acute myocardial infarction within 48 hours and at 10 days after infarction. Abnormal motion of an inferior or posterior wall segment was seen in 91% of inferoposterior infarctions by echocardiography versus 61% seen by radionuclide ventriculography. Ejection fractions determined by echocardiography and radionuclide ventriculography correlated well (r . 0.82) and did not change from the first 48 hours to 10 days after infarction (0.48 +/- 0.14). Similarly, wall motion score showed minimal change from the first 48 hours to 10 days. In-hospital mortality was 37 and 42% in patients with an ejection fraction of 0.35 or less by echocardiography and radionuclide ventriculography, respectively. No mortality was seen in patients with an ejection fraction above 0.40 by either test. The echocardiographic wall motion score was also predictive of mortality (40 versus 2%; score less than or equal to 0.50 versus greater than 0.50). The 1 year mortality rate in the 81 short-term survivors was 17%. Mortality was lowest in patients with an ejection fraction above 0.49 or wall motion score above (0.79 (2 to 5%) and worse in those with an ejection fraction below 0.36 or wall motion score below 0.51 (36 to 63%) by either technique. Thus in acute myocardial infarction, echocardiography and radionuclide ventriculography provide a comparable assessment of left ventricular function and wall motion in anterior infarction. Echocardiography appears more sensitive in detecting inferoposterior wall motion abnormalities. Both techniques are capable of identifying subgroups of patients with a high risk of death during the acute event and with an equally high mortality rate over a 1 year follow-up period

  1. Cerebrospinal fluid flow abnormalities in patients with neoplastic meningitis. An evaluation using 111In-DTPA ventriculography

    International Nuclear Information System (INIS)

    Grossman, S.A.; Trump, D.L.; Chen, D.C.; Thompson, G.; Camargo, E.E.

    1982-01-01

    Cerebrospinal fluid flow dynamics were evaluated by 111 In-diethylenetriamine pentaacetic acid ( 111 In-DTPA) ventriculography in 27 patients with neoplastic meningitis. Nineteen patients (70 percent) had evidence of cerebrospinal fluid flow disturbances. These occurred as ventricular outlet obstructions, abnormalities of flow in the spinal canal, or flow distrubances over the cortical convexities. Tumor histology, physical examination, cerebrospinal fluid analysis, myelograms, and computerized axial tomographic scans were not sufficient to predict cerebrospinal fluid flow patterns. These data indicate that cerebrospinal fluid flow abnormalities are common in patients with neoplastic meningitis and that 111 In-DTPA cerebrospinal fluid flow imaging is useful in characterizing these abnormalities. This technique provides insight into the distribution of intraventricularly administered chemotherapy and may provide explanations for treatment failure and drug-induced neurotoxicity in patients with neoplastic meningitis

  2. Application of radionuclide ventriculography phase analysis in patients with atrial or ventricular pacing for detecting ventricular abnormal excitation

    International Nuclear Information System (INIS)

    Shi Rongfang; Wang Zhonggan; Li Shengting

    1996-01-01

    The aim of the study was to increase the accuracy of detecting ventricular abnormal excitation. During atrial or ventricular pacing, radionuclide ventriculography phase analysis (RNV-PA) was performed in 17 patients with Wolff-Parkinson-White (W-P-W) syndrome and paroxysmal supra ventricular tachycardia (PSVT) and ventricular tachycardia (PVT). During pacing, detection rate of abnormal excitation by RNV-PA was 95.5%, compared with 68.2% during basic conduction. Atrial or ventricular pacing can significantly increase the detection rate of abnormal excitation by RNV-PA in patients with W-P-W syndrome. It may be a valuable method for identifying the abnormal excitation and estimating the therapeutic effect of ablation

  3. Determination of right ventricular ejection fraction from reprojected gated blood pool SPET: comparison with first-pass ventriculography

    International Nuclear Information System (INIS)

    Bartlett, M.L.; Seaton, D.; McEwan, L.; Fong, W.

    2001-01-01

    Gated blood pool (GBP) studies are widely available and relatively inexpensive. We have previously published a simple and convenient method for measuring left ventricle ejection fraction (EF) with increased accuracy from single-photon emission tomography (SPET) GBP scans. This paper describes an extension of this method by which right ventricular EF may also be measured. Gated SPET images of the blood pool are acquired and re-oriented in short-axis slices. Counts from the left ventricle are excluded from the short-axis slices, which are then reprojected to give horizontal long-axis images. Time-activity curves are generated from each pixel around the right ventricle, and an image is created with non-ventricular pixels ''greyed out''. This image is used as a guide in drawing regions of interest around the right ventricle on the end-diastolic and end-systolic long-axis images. In 28 patients, first-pass ventriculography studies were acquired followed by SPET GBP scans. The first-pass images were analysed a total of four times by two observers and the SPET images were analysed three times each by two observers. The agreement between the two techniques was good, with a correlation coefficient of 0.72 and a mean absolute difference between first-pass and reprojected SPET EFs of 4.8 EF units. Only four of the 28 patients had a difference of greater than 8 EF units. Variability was also excellent for SPET right ventricular EF values. Intra-observer variability was significantly lower for SPET than for first-pass EFs: standard error of the estimate (SEE)=5.1 and 7.3 EF units, respectively (P<0.05). Inter-observer variability was comparable in the two techniques (SEE=5.2 and 6.9 EF units for SPET and first-pass ventriculography, respectively). (orig.)

  4. Intravenous streptokinase therapy in acute myocardial infarction: Assessment of therapy effects by quantitative 201Tl myocardial imaging (including SPECT) and radionuclide ventriculography

    International Nuclear Information System (INIS)

    Koehn, H.; Bialonczyk, C.; Mostbeck, A.; Frohner, K.; Unger, G.; Steinbach, K.

    1984-01-01

    To evaluate a potential beneficial effect of systemic streptokinase therapy in acute myocardial infarction, 36 patients treated with streptokinase intravenously were assessed by radionuclide ventriculography and quantitative 201 Tl myocardial imaging (including SPECT) in comparison with 18 conventionally treated patients. Patients after thrombolysis had significantly higher EF, PFR, and PER as well as fewer wall motion abnormalities compared with controls. These differences were also observed in the subset of patients with anterior wall infarction (AMI), but not in patients with inferior wall infarction (IMI). Quantitative 201 Tl imaging demonstrated significantly smaller percent myocardial defects and fewer pathological stress segments in patients with thrombolysis compared with controls. The same differences were also found in both AMI and IMI patients. Our data suggest a favorable effect of intravenous streptokinase on recovery of left ventricular function and myocardial salvage. Radionuclide ventriculography and quantitative 201 Tl myocardial imaging seem to be reliable tools for objective assessment of therapy effects. (orig.)

  5. Gold-195m first-pass radionuclide ventriculography, thallium-201 single-photon emission CT, and 12-lead ECG stress testing as a combined procedure

    International Nuclear Information System (INIS)

    Kipper, S.L.; Ashburn, W.L.; Norris, S.L.; Rimkus, D.S.; Dillon, W.A.

    1985-01-01

    Graded, sequential, rest/exercise, gold-195m, first-pass ventriculography and thallium-201 (Tl-201) single-photon emission computed tomography (SPECT) were performed simultaneously during a single, electrocardiograph-monitored, bicycle stress test in 24 individuals. The technical aspects and logistics involved in performing this combined radionuclide study are stressed in this preliminary report. Fourteen healthy volunteers each had a normal left ventricular ejection fraction and wall-motion response, along with normal T1-201 perfusion and washout, as determined by both visual and quantitative analysis of the tomographic sections. Each of ten patients with coronary artery disease had at least one abnormality of these parameters. The authors suggest that it is technically feasible to evaluate both cardiac function and myocardial perfusion simultaneously by combing Au-195m ventriculography and Tl-201 SPECT imaging into a single, noninvasive, diagnostic package

  6. How to accurately assess the clinical value of isometric exercise radionuclide ventriculography in diagnosis of coronary artery disease

    International Nuclear Information System (INIS)

    Yang Shunfang; Zhu Huiping; Zeng Jun; Xie Wenhui; Yu Zhichang

    2001-01-01

    To assess the influence of isometric handgrip exercise on left ventricular function by radionuclide ventriculography in patients with coronary artery disease (CAD). Using gated equilibrium radionuclide ventriculography, parameters of left ventricular function were analyzed at rest and during 30% sustained handgrip (HNG) for 5 - 10 minuets in 8 normal control subjects and 38 consecutive CAD patients. All investigated subjects were also performed coronary arteriography within 2 weeks. Results showed that at rest, left ventricular ejection fraction (LVEF), peak filling rate (PFR), end-diastolic volume (EDV), end-systolic volume (ESV) and heart rate (HR) were reduced in one-vessel, two-vessel and three-vessel of stenosis patient group (53.67 +- 5.0)%, (52.47 +- 8.26)%, (52.81 +- 8.89)%; 2.87 +- 0.29, 2.71 +- 0.88, 3.07 +- 0.71 end-diastolic volume per second (EDV/s); 1.36 +- 0.05, 1.34 +- 0.06, 1.34 +- 0.06; 0.62 +-0.06, 0.66 +- 0.06, 0.65 +- 0.1; 69.67 +- 8.14, 72.85 +- 10.5, 76.56 +- 18.04 (min -1 ), respectively, as compared with controls (57 +- 10.45)%, p = NS; 2.94 +- 0.44 (EDV/s), p = NS; 1.38 +- 0.15, p = NS; 0.59 +- 0.11, p = NS; 72.88 +- 8.25 (min -1 ), p = NS, respectively. During HNG exercise using both hands, the indexes were reduced in CAD patients (54.44 +- 5.66)%, (48.84 +- 8.70)%, (45.25 +- 8.69)%; 2.75 +- 0.39, 2.50 +- 0.68, 2.22 +- 0.58 (EDV/s); 1.36 +- 0.05, 1.31 +- 0.06, 1.26 +- 0.07; 0.61 +- 0.07, 0.69 +- 0.06, 0.71 +- 0.09; 81.33 +- 8.92, 84.46 +- 14.29, 90.56 +- 26.54 (min -1 ), respectively, as compared with controls (59.38 +- 9.44)%, p = NS; -1 ), p = NS, respectively. The four protocols of CAD diagnosis were 1. LVEF <55% and ΔPFR < 0 EDV/s at rest (Δ value = during HNG value-rest value); 2. LVEF <55% during HNG and ΔPFR <0 EDV/s; 3. ΔLVEF <0% and ΔPFR <0 EDV/s; 4. ΔEF <0%. Their sensitivity, specificity and accuracy were 45%, 53%, 66%, 76%, 100%, 100%, 87.5%, 87.5%, 54%, 61%, 70%, 78%, respectively. The isomeric exercise radionuclide

  7. Pharmacological radionuclide ventriculography for detection of myocardial contractile reserve in patients after myocardial infarction: head-to-head comparison of low dose dobutamine and low dose dypiridamole

    International Nuclear Information System (INIS)

    Petrasinovic, Z.; Ostojic, M.; Beleslin, B.; Stojkovic, S.; Nedeljkovic, M.; Stankovic, G.; Dikic, A.; Pavlovic, S.; Sobic, D.

    2002-01-01

    Background. Low dose pharmacological stress echocardiography with either dobutamine or dipyridamole infusion has been proposed for recognition of myocardial viability. However, dependence on adequate acoustic window, observer experience, and the mild degree of wall motion changes make the viability assessment by stress echocardiography especially bothersome. The objective of the study was to evaluate the ability of low dose dobutamine and low dose dipyridamole radionuclide ventriculography to detect contractile reserve in patients after myocardial infarction and functional recovery after coronary angioplasty. Methods. The study group consisted of 20 consecutive patients (52±10 years, 17 male) with previous myocardial infarction and resting regional dyssynergy, in whom diagnostic cardiac catheterization revealed significant one-vessel coronary artery stenosis suitable for angioplasty. Each patient underwent equilibrium 99m-Tc radionuclide ventriculography which was performed at rest and during low dose dipyridamole (0.28 mg/kg over 2 minutes) and low dose dobutamine infusion (up to 10 mcg/kg/min). Left ventricular global and regional ejection fractions were determined. Increase of regional ejection fraction for >5% (inferoapical and posterolateral regions) or >10% (anteroseptal regions) during low dose dobutamine and dipyridamole in infarcted regions, as well as in the follow up period, was considered as index of contractile reserve. After 8 weeks of successful angioplasty, resting radionuclide ventriculography was repeated in all patients in order to identify functional recovery of the infarct zone. Results. Out of the 180 analyzed segments (20x9), 90 regional ejection fractions have shown depressed contractility. The mean of the regional ejection fractions showing depressed contractility increased from the resting value of 34±12% to 42±14% in the follow-up period (p=0.06). Of the 90 with baseline dyssynergy, 46 were responders during low-dose dobutamine (51

  8. Comparison of exercise stress testing with dobutamine stress echocardiography and radionuclide ventriculography for diagnosis of coronary artery disease

    International Nuclear Information System (INIS)

    Ozdemir, K.; Kisacik, H.L.; Oguzhan, A.

    1999-01-01

    Dobutamine stress echocardiography, Tc-99m radionuclide ventriculography (RNVG), and exercise stress testing were performed prospectively in 63 patients with suspected coronary artery disease to compare the values of exercise testing, dobutamine stress echocardiography and RNVG in the non-invasive diagnosis of coronary artery disease. The sensitivities of dobutamine stress echocardiography and RNVG were found to be higher than that of exercise testing (93-62%, p 0.05). There were no differences between the sensitivities of the three techniques in multiple vessel disease (p>0.05). The specificities of dobutamine stress echocardiography and RNVG were higher than that of exercise testing (for both of the tests 86-62%, p 0.05). The results of dobutamine stress echocardiography RNVG were concordant with each other in 46 patients (76%, kappa=65%) in sectional analysis. Dobutamine stress echocardiography and RNVG tests were comparable with each other in 85% of the 189 segments (kappa=64%). The expected 5% decrease at peak doses of dobutamine was not detected in stress echocardiography in 25 patients and in RNVG in 26 of the patients. Dobutamine stress echocardiography and RNVG are superior to exercise testing in the diagnosis of single vessel disease and there is no significant difference between the two techniques. When the ejection fraction is considered in dobutamine stress echocardiography and RNVG, it does not make an additional contribution to the diagnosis of coronary artery disease. (author)

  9. Exercise tolerance in mitral stenosis and chronic obstructive pulmonary disease. Evaluation by anaerobic threshold and radionuclide ventriculography

    Energy Technology Data Exchange (ETDEWEB)

    Uenami, Atsushi; Mizuno, Toshikazu; Chiba, Hiroshi; Ohno, Masanori; Wakino, Kouichi; Sawada, Yoshihiro; Ohno, Joichi; Kume, Kiyoshi

    1986-06-01

    Serial radionuclide ventriculography was performed using a newly developed ''real-time'' system, and left ventricular ejection fraction (LVEF), right ventricular ejection fraction (RVEF), stroke volume (SV), and cardiac output (CO) were measured during graded supine exercise in five patients with mitral stenosis (MS), in five patients with chronic obstructive pulmonary disease (COPD) and in five healthy subjects. Simultaneous pulmonary gas exchange analysis permitted determining the anaerobic threshold, which is the point during incremental exercise when lactate begins to accumulate in the blood. LVEF at the anaerobic threshold was not significantly changed in any patient groups and in healthy subjects, but RVEF at the anaerobic threshold was lower in COPD and MS patients as compared with healthy subjects. In MS, SV during exercise was reduced at the anaerobic threshold, but not in COPD or in healthy subjects. In conclusion, reduced working capacity is related to decreased RVEF in both COPD and MS, but the inhibited increase in CO during exercise is also important for the working capacity in MS.

  10. Evaluation of aspirin therapy on intracardiac thrombi using indium-111-oxine platelet scintigraphy, two-dimentional echocardiography and left ventriculography

    International Nuclear Information System (INIS)

    Shibuya, Masanori; Irino, Tadayoshi; Yoshioka, Toshiharu; Sugimoto, Tsuyoshi; Tsuji, Kazuo; Naka, Masashi; Arai, Hidekazu.

    1984-01-01

    Left ventriculography (LVG), two-dimensional echocardiography (2-DE) and indium-111-oxine platelet scintigraphy were performed in five patients with intracardiac thrombi. Thrombi were visible in 7 sites (5 in the ventricle and 2 in the atrium) by platelet scintigraphy, in 4 sites (3 in the ventricle and 1 in the atrium) by 2-DE, and in 4 sites (4 in the ventricle) by LVG. When aspirin was administered to the patients, platelet scintigraphy had become negative for thrombi in 5 sites and false-negative for them in 2 sites. However, thrombi were detected in 6 sites after the withdrawal of aspirin. On the other hand, thrombi were detected in 4 sites by 2-DE, irrespective of the administration of aspirin. Indium-111-oxine platelet scintigraphy has proved to not only have higher sensitivity for detecting thrombi but also to be capable of observing the coagulation status of platelets on the thrombi. It is therefore considered very helpful in assessing anticoagulation therapy. (Namekawa, K)

  11. Can isosorbide dinitrate (ISDN) prevent myocardial ischemia during exercise in patients with coronary artery disease; An assessment with radionuclide ventriculography

    Energy Technology Data Exchange (ETDEWEB)

    Konishi, Tokuji; Koyama, Takao; Aoki, Toshikazu; Okamoto, Shinya; Setsuda, Morimichi; Futagami, Yasuo; Nakano, Takeshi (Mie Univ., Tsu (Japan). School of Medicine)

    1989-12-01

    The effects of sublingual isosorbide dinitrate (ISDN) on left ventricular function during exercise were evaluated in 8 patients with coronary artery disease. ECG gated multistage exercise radionuclide ventriculography (RNV) was performed to assess the global and regional left ventricular function before and after sublingual ISND. Chest pain during exercise was observed in six patients (75%) during exercise but subsided negative ISDN. Left ventricular ejection fraction (LVEF) during stress did not show improved significant change during exercise (from 64.4 {plus minus} 8.7% to 64.6 {plus minus} 8.3%) but increased significantly from 66.0 {plus minus} 6.3% to 69.9 {plus minus} 8.6% after ISDN. Left ventricular end-systolic volume increased during exercise from 56.9 {plus minus} 19.6 ml to 68.0 {plus minus} 15.9 ml, but the increase was suppressed (from 49.1 {plus minus} 11.0 ml to 44.5 {plus minus} 15.5 ml) after ISDN. ISDN prevented not only cardiac symptoms nor ECG changes but also improved abnormal left ventricular function during exercise. (author).

  12. Usefulness of acoustic quantification method in left ventricular volume and ejection fraction. Compared with ventriculography and scintigraphy

    International Nuclear Information System (INIS)

    Shibata, Takahiro; Honda, Youichi; Kashiwagi, Hidehiko

    1996-01-01

    Acoustic quantification method (AQ: on-line automated boundary detection system) has proved to have a good correlation with left ventriculography (LVG) and scintigraphy (SG) in patients with normal left ventricular (LV) function. The aim of this study is to determine whether AQ is also useful in patients with abnormal LV function. We examined 54 patients with LV asynergy. End-diastolic volumes with AQ, LVG and SG were 77, 135, 118 ml. A good correlation was found between AQ and LVG and SG (LVG; r=0.81, SG; r=0.68). End-systolic volumes with AQ, LVG and SG were 38, 64 and 57 ml. Left ventricular volumes obtained from AQ had a good correlation with LVG and SG, but were underestimated. LV ejection fraction obtained from AQ had good correlation with those with LVG and SG (LVG; r=0.84. SG; r=0.77). On-line AQ appears to be a useful noninvasive method for evaluation of the left ventricular ejection fraction, but care must be exercised when estimations of left ventricular volumes are made. (author)

  13. Can the diagnostic accuracy of radionuclide ventriculography during exercise be improved by means of a step-up loading procedure?

    International Nuclear Information System (INIS)

    Ruegenberg, T.

    1985-01-01

    34 patients (31 of whom were coronary heart disease sufferers as proven by angiography) and further 3 patients failing to show symptoms of this disorder were subjected to radionuclide ventriculography carried out with the aid of 99m Tc-labelled erythrocytes in such a way that examinations at rest were directly followed by maximum loading tests. In a second series of examinations a step-up procedure was adopted where initial recordings at rest were followed by preliminary exercise tests using only 25% of the maximum load. The parameters chosen to evaluate the results were heart rate, ejection fraction, maximum velocity of changes in volume, endsystolic and enddiastolic volumes (ESV and EDV) as well as cardiac output. In 23 patients the preliminary exercise test revealed an insufficient increase or even decrease of the ejection fraction that was associated with delayed volume changes, increases in ESV and EDV as well as reductions in cardiac output and in 21 patients it became evident during those examinations that the onset of stenocardiac complaints was preceded by markedly pronounced function disorders in the left ventricle. It was concluded from these findings that the step-up procedure followed here may in some patients provide additional information on the level of myocardial performance. It can thus be assumed to contribute considerably to higher diagnostic accuracy, although it requires no more time than conventional exercise tests and is not associated with additional radiation exposure. (TRV) [de

  14. Attempts at diagnostic differentiation between dilatory cardiomyopathy and coronary heart disease on the basis of radionuclide ventriculography

    International Nuclear Information System (INIS)

    Hefermann, R.

    1989-01-01

    It was the purpose of this study to find out which of the various parameters of radionuclide ventriculography would be suitable to determine whether a patient suffers from dilatory myocardiopathy (MCP) or coronary heart disease (CHD). Two groups of patients were examined using a mathematical procedure known as analysis of discriminance, in which the weights that individual parameters would have in a separation function were determined with the help of a computer programme. On the basis of these data, attempts were made to assign the patients of the different diagnostic groups. The parameters registered at rest, which were FSMIN, EFAFI (end of fast filling) and CONTR (contraction), led to a total of five diagnostic errors, with one case of CHD being classified as CMP and four CMP patients as having CHD. On the basis of the parameters measured during exercise), which were RELAX (relaxation), stroke volume and PETI (peak ejection time), only one CMP patient was erroneously assigned to the CHD group. When the parameters of RNV at rest and during exercise were combined to give FSMINR (minimum of highest factor minus lowest factor at rest), DFSDIFF (difference between F-S at rest and during exercise) and DMINVOL (difference between heart minute volumes at rest and during exercise), the classifications were correct for all of the 30 study participants (100%). This led us to conclude that the RNV parameters chosen permitted reliable diagnostic discriminations to be made between those two groups of patients. (orig./MG) [de

  15. Hemodynamic effects of iodixanol and iohexol during ventriculography in patients with compromised left ventricular function

    NARCIS (Netherlands)

    Bergstra, A; van Dijk, RB; Brekke, O; Orozco, L; den Heijer, P; Crijns, HJGM

    A crossover study was performed to compare the hemodynamic effects of the isoosmolar contrast agent iodixanol (Visipaque(R)) 320 mg I/ml to those of the low-osmolar iohexol (Omnipaque(R)) 350 mg I/ml. The main hypothesis was that iodixanol and iohexol would affect left ventricular end-diastolic

  16. Contrast Materials

    Science.gov (United States)

    ... is mixed with water before administration liquid paste tablet When iodine-based and barium-sulfate contrast materials ... for patients with kidney failure or allergies to MRI and/or computed tomography (CT) contrast material. Microbubble ...

  17. Detection of occult pericardial hemorrhage early after open-heart surgery using technetium-99m red blood cell radionuclide ventriculography

    International Nuclear Information System (INIS)

    Bateman, T.M.; Czer, L.S.; Gray, R.J.; Kass, R.M.; Raymond, M.J.; Garcia, E.V.; Chaux, A.; Matloff, J.M.; Berman, D.S.

    1984-01-01

    Pericardial or mediastinal hemorrhage requiring reoperation occurs in 2% to 5% of patients, usually early (0 to 48 hours), after open-heart surgery. This hemorrhage may be occult, and resulting cardiac tamponade may easily be misinterpreted as ventricular dysfunction, common early postoperatively. In such cases, appropriate and timely intervention may not occur. Of 50 patients evaluated by technetium-99m red blood cell gated equilibrium radionuclide ventriculography (RNV) because of early postoperative cardiogenic shock of uncertain etiology, 17 had unique scintigraphic images suggestive of intrathoracic hemorrhage. Of these 17, 5 had a generalized halo of abnormal radioactivity surrounding small hyperdynamic right and left ventricles, 11 had localized regions of intense blood pool activity outside the cardiac chambers (two with compression of single chambers), and one demonstrated marked radionuclide activity in the right hemithorax (2000 ml of blood at reoperation). Twelve patients had exploratory reoperation for control of hemorrhage as a direct result of the scintigraphic findings, three were successfully treated with fresh frozen plasma and platelet infusions along with medical interventions to optimize cardiac performance, and two patients died in cardiogenic shock (presumed tamponade) without reoperation. In the 12 reoperated patients, all were confirmed to have active pericardial bleeding. Scintigraphic localization of abnormal blood pools within the pericardium corresponded to the sites at which active bleeding was witnessed at reoperation. The abnormal bleeding was etiologically related to the tamponade state, with marked improvement in hemodynamics after reoperation. Nine additional patients were reoperated for presumed tamponade after RNV revealed an exaggerated halo of photon deficiency surrounding the cardiac chambers

  18. Left ventricular performance at rest and during peak exercise in never-treated hypertensive female - an assessment with radionuclide ventriculography

    International Nuclear Information System (INIS)

    Topuzovic, N.; Karner, I.; Rusic, A.; Krstonosic, B.

    2002-01-01

    Aim: The aim of this study was to investigate left ventricular performance and exercise tolerance in never-treated female hypertensive patients. Materials and Methods: Seventeen female patients with newly established, uncomplicated essential hypertension (aged 25 to 57 years) were evaluated with rest-stress radionuclide gated ventriculography, and were compared to 23 age-matched normotensive female volunteers. Results: Mean blood pressure was significantly higher in patients at rest and during exercise than in controls (121±13 vs. 89±7 mm Hg, and 143±11 vs. 122±9 mm Hg, respectively, p 2 , respectively, p<0.01), while ESV was similar in both groups. Ejection fraction (EF) at rest and stress did not differ significantly (54±10 vs. 55±8%, and 70±10 vs. 66±8%, respectively), but % rise in EF during exercise was significantly higher in patients. At rest and during exercise, there were no significant difference in peak ejection rate (PER) and time to PER (TPER) between patients and controls. Patients had similar peak filling rate (PFR) at rest (2.88±0.79 vs. 2.76±0.76 EDV/s) and during exercise (5.85±1.86 vs. 6.21±1.97 EDV/s), in addition to nonsignificant difference in time to PFR (at rest 143±62 vs. 146±42 ms at rest, and 97±20 vs. 91±19 ms during exercise). Conclusion: Female patients with newly diagnosed, never-treated hypertension have preserved maximal exercise performance, systolic function and diastolic function, but they have significant enlargement of EDV and elevated cardiac output during exercise

  19. Comparison between Radionuclide Ventriculography and Echocardiography for Quantification of Left Ventricular Systolic Function in Rats Exposed to Doxorubicin

    Directory of Open Access Journals (Sweden)

    Luciano Fonseca Lemos de Oliveira

    Full Text Available Abstract Background: Radionuclide ventriculography (RV is a validated method to evaluate the left ventricular systolic function (LVSF in small rodents. However, no prior study has compared the results of RV with those obtained by other imaging methods in this context. Objectives: To compare the results of LVSF obtained by RV and echocardiography (ECHO in an experimental model of cardiotoxicity due to doxorubicin (DXR in rats. Methods: Adult male Wistar rats serving as controls (n = 7 or receiving DXR (n = 22 in accumulated doses of 8, 12, and 16 mg/kg were evaluated with ECHO performed with a Sonos 5500 Philips equipment (12-MHz transducer and RV obtained with an Orbiter-Siemens gamma camera using a pinhole collimator with a 4-mm aperture. Histopathological quantification of myocardial fibrosis was performed after euthanasia. Results: The control animals showed comparable results in the LVSF analysis obtained with ECHO and RV (83.5 ± 5% and 82.8 ± 2.8%, respectively, p > 0.05. The animals that received DXR presented lower LVSF values when compared with controls (p < 0.05; however, the LVSF values obtained by RV (60.6 ± 12.5% were lower than those obtained by ECHO (71.8 ± 10.1%, p = 0.0004 in this group. An analysis of the correlation between the LVSF and myocardial fibrosis showed a moderate correlation when the LVSF was assessed by ECHO (r = -0.69, p = 0.0002 and a stronger correlation when it was assessed by RV (r = -0.79, p < 0.0001. On multiple regression analysis, only RV correlated independently with myocardial fibrosis. Conclusion: RV is an alternative method to assess the left ventricular function in small rodents in vivo. When compared with ECHO, RV showed a better correlation with the degree of myocardial injury in a model of DXR-induced cardiotoxicity.

  20. Comparison between radionuclide ventriculography and echocardiography for quantification of left ventricular systolic function in rats exposed to doxorubicin

    International Nuclear Information System (INIS)

    Oliveira, Luciano Fonseca Lemos de; Carvalho, Eduardo Elias Vieira de; Romano, Minna Moreira Dias; Maciel, Benedito Carlos; Simões, Marcus Vinicius

    2017-01-01

    Background: Radionuclide ventriculography (RV) is a validated method to evaluate the left ventricular systolic function (LVSF) in small rodents. However, no prior study has compared the results of RV with those obtained by other imaging methods in this context. Objectives: To compare the results of LVSF obtained by RV and echocardiography (ECHO) in an experimental model of cardiotoxicity due to doxorubicin (DXR) in rats. Methods: Adult male Wistar rats serving as controls (n = 7) or receiving DXR (n = 22) in accumulated doses of 8, 12, and 16 mg/kg were evaluated with ECHO performed with a Sonos 5500 Philips equipment (12-MHz transducer) and RV obtained with an Orbiter-Siemens gamma camera using a pinhole collimator with a 4-mm aperture. Histopathological quantification of myocardial fibrosis was performed after euthanasia. Results: The control animals showed comparable results in the LVSF analysis obtained with ECHO and RV (83.5 ± 5% and 82.8 ± 2.8%, respectively, p > 0.05). The animals that received DXR presented lower LVSF values when compared with controls (p < 0.05); however, the LVSF values obtained by RV (60.6 ± 12.5%) were lower than those obtained by ECHO (71.8 ± 10.1%, p = 0.0004) in this group. An analysis of the correlation between the LVSF and myocardial fibrosis showed a moderate correlation when the LVSF was assessed by ECHO (r = -0.69, p = 0.0002) and a stronger correlation when it was assessed by RV (r = -0.79, p < 0.0001). On multiple regression analysis, only RV correlated independently with myocardial fibrosis. Conclusion: RV is an alternative method to assess the left ventricular function in small rodents in vivo. When compared with ECHO, RV showed a better correlation with the degree of myocardial injury in a model of DXR-induced cardiotoxicity. (author)

  1. Evaluation of aortic and mitral valve regurgitation by radionuclide ventriculography: comparison with the method of Sandler and Dodge

    Energy Technology Data Exchange (ETDEWEB)

    Kress, P.; Geffers, H.; Stauch, M.; Nechwatal, W.; Sigel, H.; Bitter, F.; Adam, W.E.

    1981-01-01

    The present investigation was undertaken to introduce a quantitative scintigraphic method for evaluation of regurgitation and to compare it with the generally accepted quantitative method of Sandler and Dodge. Radionuclide ventriculography was carried out after injection of 20 mCi 99mtechnetium-labeled red blood cells. Time-activity curves were obtained from the left and right ventricular regions. The ratio of end-diastolic-end-systolic count-rate differences for the left and right ventricles was calculated. The ratio (A) was compared with a hemodynamic ratio determined after the method of Sandler and Dodge with the stroke volume of the left ventricle measured angiographically, and the stroke volume of the right ventricle measured by thermodilution. In 33 patients with aortic and mitral valve regurgitation researchers found a correlation of r . 0.75. Due to a broad range of normal values of the sensitivity of the scintigraphic method is low. The specificity seems to be high, however, since in 64 patients with all types of heart diseases there were no false positive results. Comparing the described scintigraphic method with other modern or generally accepted methods, the principal advantages are noninvasiveness, good practicability, and the fact that important additional information about the functional state of the heart is gained. This is important in follow-up studies in patients with chronic valvular incompetence. It seems that this method will become a valuable supplement to heart catheterization in the diagnosis of valvular heart disease and may partially replace invasive methods for measuring the regurgitation fraction.

  2. Evaluation of aortic and mitral valve regurgitation by radionuclide ventriculography: comparison with the method of Sandler and Dodge

    International Nuclear Information System (INIS)

    Kress, P.; Geffers, H.; Stauch, M.; Nechwatal, W.; Sigel, H.; Bitter, F.; Adam, W.E.

    1981-01-01

    The present investigation was undertaken to introduce a quantitative scintigraphic method for evaluation of regurgitation and to compare it with the generally accepted quantitative method of Sandler and Dodge. Radionuclide ventriculography was carried out after injection of 20 mCi 99mtechnetium-labeled red blood cells. Time-activity curves were obtained from the left and right ventricular regions. The ratio of end-diastolic-end-systolic count-rate differences for the left and right ventricles was calculated. The ratio (A) was compared with a hemodynamic ratio determined after the method of Sandler and Dodge with the stroke volume of the left ventricle measured angiographically, and the stroke volume of the right ventricle measured by thermodilution. In 33 patients with aortic and mitral valve regurgitation researchers found a correlation of r . 0.75. Due to a broad range of normal values of the sensitivity of the scintigraphic method is low. The specificity seems to be high, however, since in 64 patients with all types of heart diseases there were no false positive results. Comparing the described scintigraphic method with other modern or generally accepted methods, the principal advantages are noninvasiveness, good practicability, and the fact that important additional information about the functional state of the heart is gained. This is important in follow-up studies in patients with chronic valvular incompetence. It seems that this method will become a valuable supplement to heart catheterization in the diagnosis of valvular heart disease and may partially replace invasive methods for measuring the regurgitation fraction

  3. Comparison between radionuclide ventriculography and echocardiography for quantification of left ventricular systolic function in rats exposed to doxorubicin

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Luciano Fonseca Lemos de; Carvalho, Eduardo Elias Vieira de; Romano, Minna Moreira Dias; Maciel, Benedito Carlos; Simões, Marcus Vinicius, E-mail: msimoes@fmrp.usp.br [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Centro de Cardiologia; O' Connell, João Lucas; Pulici, Érica Carolina Campos [Universidade Federal de Uberlândia (UFU), MG (Brazil)

    2017-01-15

    Background: Radionuclide ventriculography (RV) is a validated method to evaluate the left ventricular systolic function (LVSF) in small rodents. However, no prior study has compared the results of RV with those obtained by other imaging methods in this context. Objectives: To compare the results of LVSF obtained by RV and echocardiography (ECHO) in an experimental model of cardiotoxicity due to doxorubicin (DXR) in rats. Methods: Adult male Wistar rats serving as controls (n = 7) or receiving DXR (n = 22) in accumulated doses of 8, 12, and 16 mg/kg were evaluated with ECHO performed with a Sonos 5500 Philips equipment (12-MHz transducer) and RV obtained with an Orbiter-Siemens gamma camera using a pinhole collimator with a 4-mm aperture. Histopathological quantification of myocardial fibrosis was performed after euthanasia. Results: The control animals showed comparable results in the LVSF analysis obtained with ECHO and RV (83.5 ± 5% and 82.8 ± 2.8%, respectively, p > 0.05). The animals that received DXR presented lower LVSF values when compared with controls (p < 0.05); however, the LVSF values obtained by RV (60.6 ± 12.5%) were lower than those obtained by ECHO (71.8 ± 10.1%, p = 0.0004) in this group. An analysis of the correlation between the LVSF and myocardial fibrosis showed a moderate correlation when the LVSF was assessed by ECHO (r = -0.69, p = 0.0002) and a stronger correlation when it was assessed by RV (r = -0.79, p < 0.0001). On multiple regression analysis, only RV correlated independently with myocardial fibrosis. Conclusion: RV is an alternative method to assess the left ventricular function in small rodents in vivo. When compared with ECHO, RV showed a better correlation with the degree of myocardial injury in a model of DXR-induced cardiotoxicity. (author)

  4. Fourier phase analysis on equilibrium gated radionuclide ventriculography: range of phase spread and cut-off limits in normal individuals

    International Nuclear Information System (INIS)

    Ramaiah, Vijayaraghavan L.; Harish, B.; Sunil, H.V.; Selvakumar, Job; Ravi Kishore, A.G.; Nair, Gopinathan

    2011-01-01

    To define the range of phase spread on equilibrium gated radionuclide ventriculography (ERNV) in normal individuals and derive the cut-off limit for the parameters to detect cardiac dyssynchrony. ERNV was carried out in 30 individuals (age 53±23 years, 25 males and 5 females) who had no history of cardiovascular disease. They all had normal left ventricular ejection fraction (LVEF 55-70%) as determined by echocardiography, were in sinus rhythm, with normal QRS duration (≤120 msec) and normal coronary angiography. First harmonic phase analysis was performed on scintigraphic data acquired in best septal view. Left and right ventricular standard deviation (LVSD and RVSD, respectively) and interventricular mechanical delay (IVMD), the absolute difference of mean phase angles of right and left ventricle, were computed and expressed in milliseconds. Mean + 3 standard deviation (SD) was used to derive the cut-off limits. Average LVEF and duration of cardiac cycle in the study group were 62.5%±5.44% and 868.9±114.5 msec, respectively. The observations of LVSD, RVSD and right and left ventricular mean phase angles were shown to be normally distributed by Shapiro-Wilk test. Cut-off limits for LVSD, RVSD and IVMD were calculated to be 80 msec, 85 msec and 75 msec, respectively. Fourier phase analysis on ERNV is an effective tool for the evaluation of synchronicity of cardiac contraction. The cut-off limits of parameters of dyssynchrony can be used to separate heart failure patients with cardiac dyssynchrony from those without. ERNV can be used to select patients for cardiac resynchronization therapy. (author)

  5. The value of exercise radionuclide ventriculography in risk stratification in patients with known or suspected coronary artery disease

    International Nuclear Information System (INIS)

    Iskandrian, A.S.; Hakki, A.H.; Kane, S.; Schenk, C.

    1985-01-01

    This study examined the value of rest and exercise (EX) radionuclide ventriculography (RNV) in risk stratification in 392 pts with suspected or known coronary artery disease who were being evaluated for anginal symptoms. There were 289 men and 203 women, aged 55 +- 12 years (mean +- SD). There were 20 cardiac events in the followup period of up to 4 years (19 +- 10 months): 14 pts died of cardiac causes and 6 had non-fatal acute myocardial infarctions. The pts with and without events did not differ in age, clinical presentation, risk factors, and rest and EX ECGs. However, pts with events had lower EX systolic blood pressure (p < 0.02); lower EX duration; (5.5 +- 2.5 vs 7.6 +- 3.7 minutes, p < 0.0l), lower resting left ventricular (LV) ejection fraction (EF) (p = 0.001), and lower EX EF (35 +- 17% vs 56 +- 15%, p = 0.0001). The change in EF from rest to EX was not significantly different (-0.1 +- 6.1 vs 3 +- 9.9). Univariate survival analysis (Cox model) showed several descriptors related to prognosis: EX EF, rest EF, wall motion and EX duration. Multivariate analysis, however, identified the EX EF as the only significant predictor (X/sup 2/ = 19.9). None of the other variables added independent information to that provided by the EX EF. Actuarial lie table analysis showed that the risk increased as the EX EF decreased, when pts were grouped into those with EXEF ≥ 50%, 30-49%, and <30%., (p = 0.001, Mantel-Cox). Thus, the EX RNV is useful in risk stratification; the EX EF is the best descriptor that categorizes pts into different risk groups

  6. Automated processing of first-pass radioisotope ventriculography data to determine essential central circulation parameters

    Science.gov (United States)

    Krotov, Aleksei; Pankin, Victor

    2017-09-01

    The assessment of central circulation (including heart function) parameters is vital in the preventive diagnostics of inherent and acquired heart failures and during polychemotherapy. The protocols currently applied in Russia do not fully utilize the first-pass assessment (FPRNA) and that results in poor data formalization, while the FPRNA is the one of the fastest, affordable and compact methods among other radioisotope diagnostics protocols. A non-imaging algorithm basing on existing protocols has been designed to use the readings of an additional detector above vena subclavia to determine the total blood volume (TBV), not requiring blood sampling in contrast to current protocols. An automated processing of precordial detector readings is presented, in order to determine the heart strike volume (SV). Two techniques to estimate the ejection fraction (EF) of the heart are discussed.

  7. Clinical assessment of patients with mitral valve prolapse syndrome using radionuclide ventriculography

    International Nuclear Information System (INIS)

    Ochiai, Masakazu; Shirayama, Takeshi; Otsuki, Katsuichi; Adachi, Haruhiko; Nakagawa, Masao.

    1995-01-01

    Left ventricular performance in patients with mitral valve prolapse syndrome (MVP) was evaluated and compared with that in patients with ischemic heart diseases (IHD), consisting of angina pectoris (AP) and old myocardial infarction (OMI). Left ventricular ejection fraction (LVEF) and peak ejection rate (PER) were used as indices of systolic function. Peak filling rate (PFR), filling fraction in the first third of diastole (1/3FF) and time to peak filling (TPF) were used as indices of diastolic function. At rest, LVEF and PER were significantly larger in the MVP group than those in the OMI group. PFR and TPF were shown better diastolic functions in the MVP group than those in the AP or OMI groups. During stress testing, the LVEF of the MVP group increased during exercise, whereas that of the IHD group decreased gradually to the downward response (exercise-induced ischemia). The PFR of the MVP group curved upward during exercise in contrast with the inconstant response of the IHD group. We conclude that chest pain and various symptom in patients with MVP are unrelated to IHD. (author)

  8. Computer analysis of the exercise electrocardiogram and control of radionuclide ventriculography: an optimal statistical decision model for diagnosis of coronary artery disease

    International Nuclear Information System (INIS)

    Hsia, P.W.E.

    1987-01-01

    A new automated technique for the diagnosis of coronary artery disease (CAD) by stress electrocardiography and radionuclide ventriculography (RNV) has been developed. The method employs digital signal processing of the electrocardiogram (ECG) for recognition of ischemic and arrhythmic events. On-line detection of abnormal beats is used for control image acquisition by the gamma camera resulting in improved image quality since only identical beats are included in the composite images of the cardiac cycle. A combined stress ECG analysis which measures ST changes indicative of ischemia, and radionuclide results, which reveal corresponding ejection fraction abnormalities yields greater sensitivity and specificity than either test alone. Digitized data from the electrocardiogram are analyzed in a beat-by-beat mode and a contextual diagnosis of underlying rhythm is given. Template generation, R wave detection, QRS window size, baseline correction, and continuous updating of heart rate are completely automated. A statistical model base on computerized ST segment measurements combined with radionuclide ventriculography data has been developed by using a logistic model with stepwise regression fitting. A previously acquired database of similar measurements was used for designing the model. The most significant parameters were found to be (1) ejection fraction of exercise RNV; (2) difference of ST level between exercise and resting test (stdif); and (3) ejection fraction difference between exercise and resting test. The new parameter stdif, not previously used in ECG interpretation, was found to be of great diagnostic significance

  9. Dose optimisation in single plane interstitial brachytherapy

    DEFF Research Database (Denmark)

    Tanderup, Kari; Hellebust, Taran Paulsen; Honoré, Henriette Benedicte

    2006-01-01

    patients,       treated for recurrent rectal and cervical cancer, flexible catheters were       sutured intra-operatively to the tumour bed in areas with compromised       surgical margin. Both non-optimised, geometrically and graphically       optimised CT -based dose plans were made. The overdose index...... on the       regularity of the implant, such that the benefit of optimisation was       larger for irregular implants. OI and HI correlated strongly with target       volume limiting the usability of these parameters for comparison of dose       plans between patients. CONCLUSIONS: Dwell time optimisation significantly......BACKGROUND AND PURPOSE: Brachytherapy dose distributions can be optimised       by modulation of source dwell times. In this study dose optimisation in       single planar interstitial implants was evaluated in order to quantify the       potential benefit in patients. MATERIAL AND METHODS: In 14...

  10. Right heart ventriculography

    Science.gov (United States)

    Angiography - right heart ... moved forward into the right side of the heart. As the catheter is advanced, the doctor can ... is injected into the right side of the heart. It helps the cardiologist determine the size and ...

  11. Contrast media

    International Nuclear Information System (INIS)

    Decazes, Ph.

    2004-01-01

    The Guerbet firm, which holds 69% of the capital on the contrast media for medical imagery, could sale about 20% of this capital in order to accelerate its development in the United States, one of its next market with the Japan. (O.M.)

  12. Simplified single plane echocardiography is comparable to conventional biplane two-dimensional echocardiography in the evaluation of left atrial volume: a study validated by three-dimensional echocardiography in 143 individuals.

    Science.gov (United States)

    Vieira-Filho, Normando G; Mancuso, Frederico J N; Oliveira, Wercules A A; Gil, Manuel A; Fischer, Cláudio H; Moises, Valdir A; Campos, Orlando

    2014-03-01

    The left atrial volume index (LAVI) is a biomarker of diastolic dysfunction and a predictor of cardiovascular events. Three-dimensional echocardiography (3DE) is highly accurate for LAVI measurements but is not widely available. Furthermore, biplane two-dimensional echocardiography (B2DE) may occasionally not be feasible due to a suboptimal two-chamber apical view. Simplified single plane two-dimensional echocardiography (S2DE) could overcome these limitations. We aimed to compare the reliability of S2DE with other validated echocardiographic methods in the measurement of the LAVI. We examined 143 individuals (54 ± 13 years old; 112 with heart disease and 31 healthy volunteers; all with sinus rhythm, with a wide range of LAVI). The results for all the individuals were compared with B2DE-derived LAVIs and validated using 3DE. The LAVIs, as determined using S2DE (32.7 ± 13.1 mL/m(2)), B2DE (31.9 ± 12.7 mL/m(2)), and 3DE (33.1 ± 13.4 mL/m(2)), were not significantly different from each other (P = 0.85). The S2DE-derived LAVIs correlated significantly with those obtained using both B2DE (r = 0.98; P < 0.001) and 3DE (r = 0.93; P < 0.001). The mean difference between the S2DE and B2DE measurements was <1.0 mL/m(2). Using the American Society of Echocardiography criteria for grading LAVI enlargement (normal, mild, moderate, severe), we observed an excellent agreement between the S2DE- and B2DE-derived classifications (κ = 0.89; P < 0.001). S2DE is a simple, rapid, and reliable method for LAVI measurement that may expand the use of this important biomarker in routine echocardiographic practice. © 2013, Wiley Periodicals, Inc.

  13. Combined evaluation of first-pass radionuclide angiography and epuilibrium radionuclide ventriculography in the diagnosis of coronary artery disease. Pt. 1

    International Nuclear Information System (INIS)

    Knesewitsch, P.; Kleinhans, E.; Buell, U.

    1986-01-01

    The results of 203 patients who underwent first-pass radionuclide angiography (FP), as well as quantitative equilibrium radionuclide ventriculography (qERNV), were stored in a data base system and evaluated statistically. In patients with coronary artery disease (CAD) without previous myocardial infarction (MI), evaluation of global and regional ejection fraction (gEF, rEF) at rest revealed a poor sensitivity of 64% (Rest-qERNV) and 69% (Rest-FP), respectively. In patients with a history of one previous MI, the sensitivity of both methods was equivalent: FP 87% and qERNV 84%. In patients with several MIs, sensitivity was higher than 90%. Concerning localization of MI, remarkable differences between FP and qERNV were found. In posterior wall infarction, the FP sensitivity was 87% and qERNV only 67%, whereas in anterior wall infarction, the results were similar for both methods.: 93% (FP) and 96% (qERNV), respectively. Since 30 0 RAO camera position achieves the best visualization of the anterior and posterior wall, FP is superior to qERNV in the evaluation of posterior wall asynergies. In addition, qERNV often fails to discriminate anterior and posterior wall motion abnormalities. (orig.)

  14. The significance of abnormal systolic blood pressure response during supine ergometer exercise and postexercise in ischemic heart disease, studied by exercise radionuclide ventriculography

    International Nuclear Information System (INIS)

    Ajisaka, Ryuichi; Watanabe, Shigeyuki; Masuoka, Takeshi

    1989-01-01

    Abnormal response to blood pressure (BP) during exercise and postexercise was examined in 169 patients with ischemic heart disease. The patients underwent supine ergometer exercise gated equilibrium radionuclide ventriculography and coronary arteriography. When BP during exercise did not increase by at least 11 mmHg or initially increased but later decreased by more than 10 mmHg, the BP response was defined as abnormal during exercise. A postexercise BP increase of more than 10 mmHg above the peak exercise BP was defined as abnormal during postexercise. Fifteen-one patients (30%) were classified as abnormal (group 1) and the other 118 as normal (group 2). Abnormal BP response fell into three types: (1a) exercise hypotension (n=11), (1b) postexercise hypertension (n=30), and (1c) exercise hypotension with postexercise hypertension (n=10). Both average exercise duration and peak heart rate were significantly lower in groups 1a, 1b, and 1c than group 2. Exercise ST-segment depression was more noticeable in groups 1b and 1c than group 2. However, there was no significant difference in the severitiy of exercise ST-segment depression between groups 1a and 2. A decline in ejection fraction occurred more frequently in groups 1b and 1c than group 2. Patients in groups 1a, 1b, and 1c had more extensive coronary artery disease than did patients in group 2. Medically managed patients having an abnormal BP response had a poorer prognosis than those with a normal BP response. An abnormal BP response during both supine exercise and postexercise was infrequent. The abnormal BP during exercise may be usually associated with impaired exercise tolerance and severe coronary artery disease; and that during postexercise may be closely associated with myocardial ischemia and global left ventricular dysfunction. Postexercise hypertension may be of the same value as exercise hypotension in predicting poor prognosis. (Namekawa, K)

  15. Incremental value of clinical assessment, supine exercise electrocardiography, and biplane exercise radionuclide ventriculography in the prediction of coronary artery disease in men with chest pain

    International Nuclear Information System (INIS)

    Currie, P.J.; Kelly, M.J.; Harper, R.W.; Federman, J.; Kalff, V.; Anderson, S.T.; Pitt, A.

    1983-01-01

    The incremental value of clinical assessment, exercise electrocardiography (ECG) and biplane radionuclide ventriculography (RVG) in the prediction of coronary artery disease (CAD) was assessed in 105 men without myocardial infarction who were undergoing coronary angiography for investigation of chest pain. Independent clinical assessment of chest pain was made prospectively by 2 physicians. Graded supine bicycle exercise testing was symptom-limited. Right anterior oblique ECG-gated first-pass RVG and left anterior oblique ECG-gated equilibrium RVG were performed at rest and exercise. Regional wall motion abnormalities were defined by agreement of 2 of 3 blinded observers. A combined strongly positive exercise ECG response was defined as greater than or equal to 2 mm ST depression or 1.0 to 1.9 mm ST depression with exercise-induced chest pain. A multivariate logistic regression model for the preexercise prediction of CAD was derived from the clinical data and selected 2 variables: chest pain class and cholesterol level. A second model assessed the incremental value of the exercise test in prediction of CAD and found 2 exercise variables that improved prediction: RVG wall motion abnormalities, and a combined strongly positive ECG response. Applying the derived predictive models, 37 of the 58 patients (64%) with preexercise probabilities of 10 to 90% crossed either below the 10% probability threshold or above the 90% threshold and 28 (48%) also moved across the 5 and 95% thresholds. Supine exercise testing with ECG and biplane RVG together, but neither test alone, effectively adds to clinical prediction of CAD. It is most useful in men with atypical chest pain and when the ECG and RVG results are concordant

  16. Myocardial perfusion and left ventricular function during exercise evaluated by 201Tl myocardial scintigraphy and 99mTc radionuclide ventriculography in patients treated with PTCA

    International Nuclear Information System (INIS)

    Honda, Toshio; Jo, Tadafumi; Doiuchi, Junji

    1992-01-01

    To evaluate the effects of percutaneous transluminal coronary angioplasty (PTCA), we investigated myocardial ischemia and left ventricular function during exercise before and after successful PTCA in 30 patients. We used extent and severity scores of 201 thallium ( 201 Tl) exercise myocardial scintigraphy to assess myocardial ischemia and determined global and regional left ventricular ejection fraction (EF and REF) of 99m Tc-RBC exercise radionuclide ventriculography to assess left ventricular function. The extent and severity scores of stress images were significantly less after PTCA than before PTCA. The scores of the redistribution images were unchanged before and after PTCA. Global EF during exercise was significantly higher after PTCA than before PTCA. There was no difference in resting global EF between before and after PTCA. Myocardial ischemia induced by exercise was semi-quantitatively analyzed as transient perfusion defect with severity score. Severity score was significantly less after PTCA than before PTCA. ΔEF, which was obtained by subtraction of resting global EF from exercise one, was significantly higher after PTCA than before PTCA. However, the degree of improvement in myocardial ischemia and left ventricular function varied from patient to patient. In 17 patients with one-vessel left anterior descending artery disease, ΔREF, which was determined by subtracting resting regional EF from exercise one, was significantly higher in septal and apical segments after PTCA than before PTCA. Myocardial ischemia and left ventricular function under exercise were alleviated by PTCA. However, the degree of improvement varied from patient to patient and it might have been affected by various factors including coronary dissection, edema, thrombus, restenosis, spasm, side branch stenosis or occlusion, distal thrombus, and myocardial hibernation. (author)

  17. Comparison of exercise ECG and radionuclide ventriculography in the assessment of myocardial ischemia in patients with isolated stenoses of the left anterior descending artery

    International Nuclear Information System (INIS)

    Klepzig, H. Jr.; Mildenberger, D.; Kaltenbach, M.; Standke, R.; Baum, R.P.; Tezak, S.; Maul, F.D.; Hoer, G.

    1988-01-01

    21 patients with LAD-stenoses of at least 70% and 21 patients with LAD-stenoses and additional intramural anterior wall infarctions were studied. 20 patients without heart disease or after successful transluminal coronary angioplasty and 18 patients with intramural anterior wall infarction after successful transluminal dilatation of the LAD (remaining stenosis maximal 30%) served as controls. The normal range of global and regional left ventricular ejection fraction response to exercise was defined based on the data of 25 further patients without relevant coronary heart disease. Thus, a decrease in global ejection fraction and regional wall motion abnormalities were judged pathological. All patients were comparable with respect to age, ejection fraction at rest and work load. Myocardial ischemia could be detected by the exercise ECG in 81% of all patients without infarction and in 71% of patients with infarction. The corresponding values for global left ventricular ejection fraction were 76% and 81%, respectively, and for regional ejection fraction 95% in both groups. No false-positive exercise ECGs were observed in the healthy controls and 2(11%) in the corresponding group with intramural infaction. The global ejection fraction was pathological in 1(5%) healthy subject without infarction and in 3(17%) corresponding patients with infarction. Sectorial analysis revealed 5 and 22%, respectively. Our findings suggest that the exercise ECG has a limited sensitivity to detect myocardial ischemia in patients with isolated LAD-stenoses and intramural myocardial infarction. Radionuclide ventriculography yields pathological values more often; however, false-positive results also occur more frequently. (orig.) [de

  18. Comparison between radioisotopic ventriculography in balance with Tc99-albumine-DTPA and quantitative gated SPECT with Tc-99m-MIBI for determining the eject fraction of left ventricle

    International Nuclear Information System (INIS)

    Noguera, E. C; Jaime, Adelina; Pamellin, Miriam; Veliz, J

    2002-01-01

    Radionuclide ventriculography (RNV) and electrocardiography gated myocardial perfusion single photon emission computed tomography (GSPECT), can be used to assess the ventricular function.The purpose of this study was:1) to compare left ventricular ejection fraction (LVEF(%) using post-stress or rest gated GSPECT with LVEF by resting RNV and 2) to evaluate the 99m-Tc99m human serum albumin (HAS) with diethylenetriaminepenta-acetic acid (DTPA) (99m-TcHSA-DTPA) as a potential use a as blood pool imaging agent (Au)

  19. Evaluation of right ventricular function using gated equilibrium blood pool radionuclide ventriculography in patients with congenital volume and pressure overload late after surgical repair

    International Nuclear Information System (INIS)

    Hirata, Nobuaki; Sakakibara, Tetsuo; Watanabe, Shinichiro; Nomura, Fumikazu; Akamatsu, Hiroki; Matsumura, Yasushi; Yamamoto, Kazuhiro; Sasaki, Jiro; Kodama, Kazuhisa

    1991-01-01

    The effects of congenital right ventricular pressure and volume overload were studied in 3 patients with pulmonary stenosis, 7 with atrial septal defect and 6 with atrial septal defect plus pulmonary stenosis late after successful surgical correction. Gated equilibrium blood pool radionuclide ventriculography was used to measure right ventricular function at rest and during exercise and to compare it with eight normal subjects. Right ventricular ejection fractions at rest and during exercise were measured to be 61±9% and 66±13%, respectively, in the group with pulmonary stenosis, 49±7% and 54±8% in the group with atrial septal defect, and 65±13% and 69±13% in the group with atrial septal defect plus pulmonary stenosis. The values in the groups with pulmonary stenosis and atrial septal defect plus pulmonary stenosis were significantly higher than the control subjects (45±5% and 51±5%, p<0.01). The peak filling rate at rest and during exercise was also significantly higher in the groups with pulmonary stenosis and atrial septal defect plus pulmonary stenosis than in controls (at rest, 2.72±0.72, 2.53±0.94 vs. 1.64±0.24 p<0.05; during exercise, 4.38±1.23, 4.13±1.18 vs. 2.25±0.62, p<0.01). When patients with right ventricular systolic pressure equal to or greater than left ventricular systolic pressure and those with right ventricular systolic pressure less than left ventricular systolic pressure were compared, the right ventricular ejection fraction and peak filling rate were greater with the higher pressure at rest (71±10% and 3.12±0.81% vs. 55±3% and 2.30±0.27, p<0.05) and during exercise (75±11% and 4.86±1.01 vs. 59±3% and 2.61±0.35, p<0.05). Postoperative right ventricular hyperfunction may be due to preoperative pressure, but not volume, overload. (author)

  20. Development of contrast media

    International Nuclear Information System (INIS)

    Krause, W.

    1993-01-01

    Description of all contrast media (ionic and nonionic monomers, ionic and nonionic dimers) was presented. Chemotoxicity, osmolality and viscosity of some contrast agents were analyzed. The main adverse reactions to ionic and nonionic contrast media were described

  1. Radiographic contrast media

    International Nuclear Information System (INIS)

    Golman, K.; Holtz, E.; Almen, T.

    1987-01-01

    Contrast media are used in diagnostic radiology to enhance the X-ray attenuation between a body structure of interest and the surrounding tissue. A detail becomes perceptible on a roentgenogram only when its contrast exceeds a minimum value in relation to the background. Small areas of interest must have higher contrast than the background. The contrast effect depends on concentration of the contrast media with the body. A high contrast media concentration difference thus gives rise to more morphological details in the radiographs. Contrast media can be divided into negative contrast media such as air and gas which attenuate X-rays less than the body tissues, and positive contrast materials which attenuate X-rays more than the body tissues. The positive contrast media all contain either iodine (atomic number 53) or barium (atomic number 56) and can be divided into water-insoluble and water-soluble contrast media

  2. Effects of ionic and nonionic contrast media on cardiohemodynamics and quality of radiographic image during canine angiography

    International Nuclear Information System (INIS)

    Nakamura, H.; Kurata, M.; Haruta, K.; Takeda, K.

    1994-01-01

    Cardiovascular responses and radiographic image quality during cerebral angiography, aortofemoral angiography and left ventriculography with nonionic ioxilan, iohexol or iopamidol were compared with those of ionic sodium meglumine diatrizoate in pentobarbital anesthetized dogs. Injection of all contrast media caused cardiovascular changes to a greater or lesser degree, e.g., hypotension, bradycardia, tachycardia, a decrease in left ventricular pressure (LVP) and its first derivative (dP/dt), and prolongation of the P-Q and Q-T intervals. Ionic diatrizoate had a greater effect on cardiovascular parameters than nonionic contrast media during angiography in all areas. Moreover, diatrizoate produced cardiac arrhythmias and prominent changes in blood rheology concerned with blood viscosity and deformability of the erythrocyte. The cause of various effects of contrast media seemed to lie mainly in osmolality, viscosity and partially ionic additives. The radiographic image quality of all of the contrast media used was similar, but nonionic ioxilan and iohexol with lower iodine content and low osmolality gave better radio opacity than ionic diatrizoate in cerebral angiography. These results suggested that nonionic contrast media should be recommended as a diagnostic tool for both animals and human patients in poor health

  3. Dual-ROI radionuclide ventriculography

    International Nuclear Information System (INIS)

    Standke, R.; Hoer, G.; Kanemoto, N.; Maul, F.D.

    1981-01-01

    Accurate determination of the left ventricular activity function is the precondition for a quantitative analysis of the ventricular volume function. During the volume reduction period, extra-myocardial tissue penetrates into the ROI of the late diastole. This curve-distorting activity cannot be eliminated by a single-ROI technique. Of the multiple-ROI techniques, the dual-ROI method is the least complex and tedions and involves the least methodological error. At the time of maximum volume change rates, the curve may be distorted if the late diastolic ROI is inaccurately defined. A method is described which uses only the counting rate over the late diastolic ROI and corrects it only on the basis of the counting rate of the late systolic ROI. The time parameters remain uninfluenced by this correction method while the volumetric parameters are corrected. (orig./APR) [de

  4. Usefulness of contrast enhanced cardiac computed tomography in myocardial infarction

    International Nuclear Information System (INIS)

    Morooka, Nobuhiro; Yamada, Zenju; Watanabe, Shigeru

    1982-01-01

    Contrast enhanced cardiac computed tomography (CECT) was performed in 33 patients with transmural myocardial infarction. The anterior wall thickness assessed by CECT was well correlated with that by left ventriculography in RAO projection. When the septal wall thickness was compared between ECG gated and non-gated CECT images, the septal wall thickness by non-gated CECT showed a close coincidence with the diastolic wall thickness by ECG gated CECT. In all patients, the thickness of the septal, anterior and postero-lateral walls was measured. The mean wall thickness in patients of antero-septal infarction was 9.0 +- 1.9 mm for the septal wall, 6.3 +- 1.3 mm for the anterior wall, and 10.0 +- 2.1 mm for the postero-lateral wall. In patients of infero-lateral infarction, the mean wall thickness was 12.2 +- 1.7 mm for the septal wall, 10.8 +- 1.6 mm for the anterior wall and 8.9 +- 1.2 mm for the postero-lateral wall. A filling defect was revealed in the infarcted area when CECT was performed in patients with acute myocardial infarction within 1 week from the onset, and late enhancement was demonstrated by plain CT performed 10 min later. Left ventricular aneurysms were noted in 16 of 23 patients of anteroseptal infarction, and 8 of these 16 had mural thrombi in the left ventricle. Coronary artery calcification was found in 11 of 33 myocardial infarction patients. In patients with aortocoronary bypass graft, the sequential scan (dynamic scan) was shown to be a useful non-invasive method because it showed whether the graft was patent or not. (J.P.N.)

  5. Contrast induced nephropathy

    DEFF Research Database (Denmark)

    Stacul, Fulvio; van der Molen, Aart J; Reimer, Peter

    2011-01-01

    PURPOSE: The Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) has updated its 1999 guidelines on contrast medium-induced nephropathy (CIN). AREAS COVERED: Topics reviewed include the definition of CIN, the choice of contrast medium, the prophylactic me...

  6. Generalized phase contrast:

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin

    Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast...

  7. Perforations during contrast enema

    International Nuclear Information System (INIS)

    Vogel, H.; Steinkamp, U.; Grabbe, E.; Allgemeines Krankenhaus Ochsenzoll, Hamburg

    1983-01-01

    During contrast enema, perforation into the retroperitoneal space can be differentiated from perforation into the peritoneum and perforation into the intestinal wall associated with formation of barium granulomas or submucosal spreading of the contrast medium. Other special forms are perforation with contrast medium embolism of diverticula; of the processus vermiformis; penetration of contrast medium into fistulous systems and from the operated areas. Risk factors are: balloon catheter, intestinal tubes with a hard tip, preternatural anus, excessive enema pressure, contrast medium additions, preceding manipulations, intestinal diseases, advanced age and delegation of manipulations to assistants and unskilled staff. Children are particularly at risk. (orig.) [de

  8. Contrast induced nephropathy

    DEFF Research Database (Denmark)

    Stacul, Fulvio; van der Molen, Aart J; Reimer, Peter

    2011-01-01

    PURPOSE: The Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) has updated its 1999 guidelines on contrast medium-induced nephropathy (CIN). AREAS COVERED: Topics reviewed include the definition of CIN, the choice of contrast medium, the prophylactic me....../min/1.73 m (2) is CIN risk threshold for intravenous contrast medium. • Hydration with either saline or sodium bicarbonate reduces CIN incidence. • Patients with eGFR = 60 ml/min/1.73 m (2) receiving contrast medium can continue metformin normally....

  9. Phase contrast image synthesis

    DEFF Research Database (Denmark)

    Glückstad, J.

    1996-01-01

    A new method is presented for synthesizing arbitrary intensity patterns based on phase contrast imaging. The concept is grounded on an extension of the Zernike phase contrast method into the domain of full range [0; 2 pi] phase modulation. By controlling the average value of the input phase funct...... function and by choosing appropriate phase retardation at the phase contrast filter, a pure phase to intensity imaging is accomplished. The method presented is also directly applicable in dark field image synthesis....

  10. Dialysis and contrast media

    International Nuclear Information System (INIS)

    Morcos, Sameh K.; Thomsen, Henrik S.; Webb, Judith A.W.

    2002-01-01

    In a previous survey we revealed uncertainty among responders about (a) whether or not to perform hemodialysis in patients with severely reduced renal function who had received contrast medium; and (b) when to perform hemodialysis in patients on regular treatment with hemodialysis or continuous ambulatory dialysis who received contrast medium. Therefore, the Contrast Media Safety Committee of The European Society of Urogenital Radiology decided to review the literature and to issue guidelines. The committee performed a Medline search. Based on this, a report and guidelines were prepared. The report was discussed at the Ninth European Symposium on Urogenital Radiology in Genoa, Italy. Hemodialysis and peritoneal dialysis safely remove both iodinated and gadolinium-based contrast media. The effectiveness of hemodialysis depends on many factors including blood and dialysate flow rate, permeability of dialysis membrane, duration of hemodialysis and molecular size, protein binding, hydrophilicity, and electrical charge of the contrast medium. Generally, several hemodialysis sessions are needed to removal all contrast medium, whereas it takes 3 weeks for continuous ambulatory dialysis to remove the agent completely. There is no need to schedule the dialysis in relation to the injection of iodinated or MR contrast media or the injection of contrast agent in relation to the dialysis program. Hemodialysis does not protect poorly functioning kidneys against contrast-medium-induced nephrotoxicity. Simple guidelines are given. (orig.)

  11. Contrast analysis : A tutorial

    NARCIS (Netherlands)

    Haans, A.

    2018-01-01

    Contrast analysis is a relatively simple but effective statistical method for testing theoretical predictions about differences between group means against the empirical data. Despite its advantages, contrast analysis is hardly used to date, perhaps because it is not implemented in a convenient

  12. Contrast agents for MRI

    International Nuclear Information System (INIS)

    Bonnemain, B.

    1994-01-01

    Contrast agents MRI (Magnetic Resonance Imaging) have been developed to improve the diagnostic information obtained by this technic. They mainly interact on T1 and T2 parameters and increase consequently normal to abnormal tissues contrast. The paramagnetic agents which mainly act on longitudinal relaxation rate (T1) are gadolinium complexes for which stability is the main parameter to avoid any release of free gadolinium. The superparamagnetic agents that decrease signal intensity by an effect on transversal relaxation rate (T2) are developed for liver, digestive and lymph node imaging. Many area of research are now opened for optimal use of present and future contrast agents in MRI. (author). 28 refs., 4 tabs

  13. Compressive Phase Contrast Tomography

    International Nuclear Information System (INIS)

    Maia, Filipe; MacDowell, Alastair; Marchesini, Stefano; Padmore, Howard A.; Parkinson, Dula Y.; Pien, Jack; Schirotzek, Andre; Yang, Chao

    2010-01-01

    When x-rays penetrate soft matter, their phase changes more rapidly than their amplitude. Interference effects visible with high brightness sources creates higher contrast, edge enhanced images. When the object is piecewise smooth (made of big blocks of a few components), such higher contrast datasets have a sparse solution. We apply basis pursuit solvers to improve SNR, remove ring artifacts, reduce the number of views and radiation dose from phase contrast datasets collected at the Hard X-Ray Micro Tomography Beamline at the Advanced Light Source. We report a GPU code for the most computationally intensive task, the gridding and inverse gridding algorithm (non uniform sampled Fourier transform).

  14. Generalized Phase Contrast

    CERN Document Server

    Glückstad, Jesper

    2009-01-01

    Generalized Phase Contrast elevates the phase contrast technique not only to improve phase imaging but also to cross over and interface with diverse and seemingly disparate fields of contemporary optics and photonics. This book presents a comprehensive introduction to the Generalized Phase Contrast (GPC) method including an overview of the range of current and potential applications of GPC in wavefront sensing and phase imaging, structured laser illumination and image projection, optical trapping and manipulation, and optical encryption and decryption. The GPC method goes further than the restrictive assumptions of conventional Zernike phase contrast analysis and achieves an expanded range of validity beyond weak phase perturbations. The generalized analysis yields design criteria for tuning experimental parameters to achieve optimal performance in terms of accuracy, fidelity and light efficiency. Optimization can address practical issues, such as finding an optimal spatial filter for the chosen application, ...

  15. Mamografia Espectral de Contraste

    OpenAIRE

    Martins, Inês Santiago; Pereira, Inês; Pacheco, Hugo Pisco; Moutinho, Leonor

    2014-01-01

    A mamografia de contraste é uma aplicação recente possível com a mamografia digital directa, que utiliza contraste iodado endovenoso tendo como princípio a neovascularização induzida no cancro da mama, permitindo obter informação morfológica e funcional. Na mamografia espectral de contraste realiza-se uma aquisição simultânea com alta e baixa energia para cada incidência após administração de contraste iodado endovenoso. É depois feita uma imagem recombinada em que são realçadas as áreas que ...

  16. Aspiration of Barium Contrast

    OpenAIRE

    Fuentes Santos, Cristina; Steen, Bárbara

    2014-01-01

    The aspiration of barium contrast is a rare complication that may occur during studies of the digestive tract. Barium is an inert material that can cause anywhere from an asymptomatic mechanical obstruction to serious symptoms of respiratory distress that can result in patient death. We present the case of a 79-year-old male patient in whom we observed the presence of contrast medium residue in the lung parenchyma as an incidental finding during hospitalization. When the patient’s medical fil...

  17. Aspiration of Barium Contrast

    Directory of Open Access Journals (Sweden)

    Cristina Fuentes Santos

    2014-01-01

    Full Text Available The aspiration of barium contrast is a rare complication that may occur during studies of the digestive tract. Barium is an inert material that can cause anywhere from an asymptomatic mechanical obstruction to serious symptoms of respiratory distress that can result in patient death. We present the case of a 79-year-old male patient in whom we observed the presence of contrast medium residue in the lung parenchyma as an incidental finding during hospitalization. When the patient’s medical file was reviewed, images were found of a barium swallow study that the patient had undergone months earlier, and we were able to observe the exact moment of the aspiration of the contrast material. The patient had been asymptomatic since the test.

  18. Contrast media: future aspects

    International Nuclear Information System (INIS)

    Weinmann, H.J.; Platzek, J.; Schirmer, H.; Pietsch, H.; Carretero, J.; Harto, J.; Medina, J.; Riefke, B.; Martin, J.

    2005-01-01

    In spite of the dramatic development in CT, there was no major breakthrough in the iodinated contrast media development. New agents based on hybrid between MRI and CT compounds may be a new innovative alternative. This new approach may also open new indications such as radiotherapy. (orig.)

  19. Roentgen contrast medium

    International Nuclear Information System (INIS)

    Tamborski, C.

    1989-01-01

    The patent deals with a roentgen contrast medium containing a perfluorinebrominealkylether of the formula C m F 2m+1 OC n F 2n Br dispersed in water, preferentially in the presence of a non-ionic dispersing agent such as a fluorinated amidoaminoxide. 2 tabs

  20. Iodinated contrast media nephrotoxicity

    International Nuclear Information System (INIS)

    Meyrier, A.

    1994-01-01

    In the late seventies, iodinated contrast agents (ICA) were considered to be a major cause of acute iatrogenic renal failure. Over the last decade new contrast agents have been synthesized, nonionic and less hyperosmolar. The incidence of acute renal failure due to ICAs, varies from 3.7 to 70% of cases according to the series, with an average figure of 10.2%. The pathophysiology of ICA nephrotoxicity was mainly studied in laboratory animal models. Three main factors are involved in an inducing ICA-mediated decrease in glomerular filtration rate: reduction of the renal plasma flow, a direct cytotoxic effect on renal tubular cells and erythrocyte alteration leading to intra-renal sludge. Excluding dysglobulinemias with urinary excretion of immunoglobulin light chains, which represent a special case of maximum nephrotoxicity, 4 main risk factors of renal toxicity have been identified in nondiabetic subjects: previous renal failure with serum creatinine levels greater than 140 μmol per liter, extracellular dehydration, age over 60 and use of high doses of ICA and/or repeated ICA injections before serum creatinine levels return to baseline. Preventive measures for avoiding ICA nephrotoxicity are threefold: maintain or restore adequate hydration with saline infusion, stop NSAID treatment several days before ICA administration, and allow a 5 day interval before repeating contrast media injections. New, nonionic and moderately hyperosmolar contrast agents appear to be much less nephrotoxic than conventional ICAs in laboratory animals and in high-risk patients. It is advisable to select such contrast media for investigating high-risk patients. This approach was recently substantiated in well designed, randomized clinical studies which included more than 2 000 patients. (author)

  1. Mamografia com contraste

    OpenAIRE

    Baptista, Rita; Silva, Carina; Reis, Cláudia

    2016-01-01

    O estudo pretendeu apresentar as indicações clínicas, vantagens e princípios da mamografia com contraste, identificar as evoluyções tecnológicas para a mamografia com contraste e caracterizar as práticas e os desafios dos técnicos de radiologia do Hospital de Santarém (único no país a utilizar esta técnica). O cancro da mama é uma das principais causas de morte nas mulheres, em todo o mundo, mas principalmente nos Estados Unidos da América, Canadá, Europa Ocidental e Austrália. Em Portugal, e...

  2. Current iodinated contrast media

    International Nuclear Information System (INIS)

    Stacul, F.

    2001-01-01

    The number of scientific papers on iodinated contrast media is declining. Indeed, comparative trials between high-osmolality and low-osmolality agents largely showed the higher safety and tolerability of the latter, and this is no longer a matter of discussion. Only financial constraints could prevent a total conversion to low-osmolality agents. Research comparing low-osmolality (nonionic monomers, ionic dimer) and iso-osmolality contrast media (nonionic dimers) are still ongoing. Both classes of nonionic compounds proved safer than the ionic dimer. The relative merits of nonionic monomers and nonionic dimers are a matter for debate, and criteria for a selective use of different agents for different procedures could be discussed. (orig.)

  3. Anisotropic contrast optical microscope.

    Science.gov (United States)

    Peev, D; Hofmann, T; Kananizadeh, N; Beeram, S; Rodriguez, E; Wimer, S; Rodenhausen, K B; Herzinger, C M; Kasputis, T; Pfaunmiller, E; Nguyen, A; Korlacki, R; Pannier, A; Li, Y; Schubert, E; Hage, D; Schubert, M

    2016-11-01

    An optical microscope is described that reveals contrast in the Mueller matrix images of a thin, transparent, or semi-transparent specimen located within an anisotropic object plane (anisotropic filter). The specimen changes the anisotropy of the filter and thereby produces contrast within the Mueller matrix images. Here we use an anisotropic filter composed of a semi-transparent, nanostructured thin film with sub-wavelength thickness placed within the object plane. The sample is illuminated as in common optical microscopy but the light is modulated in its polarization using combinations of linear polarizers and phase plate (compensator) to control and analyze the state of polarization. Direct generalized ellipsometry data analysis approaches permit extraction of fundamental Mueller matrix object plane images dispensing with the need of Fourier expansion methods. Generalized ellipsometry model approaches are used for quantitative image analyses. These images are obtained from sets of multiple images obtained under various polarizer, analyzer, and compensator settings. Up to 16 independent Mueller matrix images can be obtained, while our current setup is limited to 11 images normalized by the unpolarized intensity. We demonstrate the anisotropic contrast optical microscope by measuring lithographically defined micro-patterned anisotropic filters, and we quantify the adsorption of an organic self-assembled monolayer film onto the anisotropic filter. Comparison with an isotropic glass slide demonstrates the image enhancement obtained by our method over microscopy without the use of an anisotropic filter. In our current instrument, we estimate the limit of detection for organic volumetric mass within the object plane of ≈49 fg within ≈7 × 7 μm 2 object surface area. Compared to a quartz crystal microbalance with dissipation instrumentation, where contemporary limits require a total load of ≈500 pg for detection, the instrumentation demonstrated here improves

  4. Contrast Invariant SNR

    DEFF Research Database (Denmark)

    Weiss, Pierre; Escande, Paul; Dong, Yiqiu

    We design an image quality measure independent of local contrast changes, which constitute simple models of illumination changes. Given two images, the algorithm provides the image closest to the first one with the component tree of the second. This problem can be cast as a specific convex progra...... algorithms based on interior point methods. The algorithm has potential applications in change detection, color image processing or image fusion. A Matlab implementation is available at http://www.math.univ-toulouse.fr/_weiss/PageCodes.html....

  5. Phase Contrast Imaging

    DEFF Research Database (Denmark)

    1996-01-01

    The invention relates to a method and a system for synthesizing a prescribed intensity pattern based on phase contrast imaging that is not based on the assumption of prior art methods that the pahase shift phi is less than 1 radian. An improved method based on a simple imaging operation...... phasors attain predetermined values for predetermined spatial frequencies, and the phasor value of the specific resolution element of the spatial phase mask corresponds to a distinct intensity level of the image of the resolution element in the intensity pattern, and a spatial phase filter for phase...... shifting of a part of the electromagntic radiation, in combination with an imaging system for generation of the intensity pattern by interference in the image plane of the imaging system between the part of the electromagnetic raidation that has been phase shifted by the phase filter and the remaining part...

  6. Paramagnetic contrast material

    International Nuclear Information System (INIS)

    McNamara, M.T.

    1987-01-01

    Paramagnetic contrast materials have certainly demonstrated clinical utility in a variety of organ systems for improved detection of various neoplastic, inflammatory, infectious, and physiologic abnormalities. Although the more commonly employed extracellular agents, such as Gd-DTPA, have been quite safe and useful, particularly in the CNS, it is almost certain that other substances will achieve more success in various other organs, such as iron oxides in the reticuloendothelial system and persisting extracellular agents in the cardiovascular system. Finally, as MRI technology continues to evolve, producing such exciting new sequences as gradient-echo fast scans, the roles of currently existing and newly discovered paramagnetic pharmaceuticals must be continuously reevaluated both to obtain maximum clinical benefit and to guide the search for newer agents that may further optimize the diagnostic efficacy of MRI

  7. New MR contrast agent

    International Nuclear Information System (INIS)

    Grossman, C.D.; Subramanian, G.; Schneider, R.; Szeverenyi, N.E.; Rosenbaum, A.M.; Gagne, G.; Tillapaugh-Fay, G.; Berlin, R.; Ritter-Hrncirik, C.; Yu, S.

    1990-01-01

    This paper evaluates an MR contrast agent-meglumine tris-(2,6-dicarboxypyridine) gadolinium (III) or gadolinium dipicolinate (Gd-DPC)-produced in-house. Rats were anesthetized with pentobarbital. For renal imaging, bowel motion artifact was minimized with glucagon (0.014 mg/kg, intravenous (IV)). Enhanced images were generated on a 2-T chemical shift imaging system with a 31-cm horizontal bore magnet after IV injection of Gd-DPC (100 μM/kg). Coronal sections of the kidneys and sagittal sections of the brain, 2 mm thick, were made. Six to eight excitations and 128 or 356 phase-encoding steps were used for each image. Control animals were injected with equivalent doses of gadopentetate dimeglumine

  8. Phase Contrast Imaging

    International Nuclear Information System (INIS)

    Menk, Ralf Hendrik

    2008-01-01

    All standard (medical) x-ray imaging technologies, rely primarily on the amplitude properties of the incident radiation, and do not depend on its phase. This is unchanged since the discovery by Roentgen that the intensity of an x-ray beam, as measured by the exposure on a film, was related to the relative transmission properties of an object. However, recently various imaging techniques have emerged which depend on the phase of the x-rays as well as the amplitude. Phase becomes important when the beam is coherent and the imaging system is sensitive to interference phenomena. Significant new advances have been made in coherent optic theory and techniques, which now promise phase information in medical imaging. The development of perfect crystal optics and the increasing availability of synchrotron radiation facilities have contributed to a significant increase in the application of phase based imaging in materials and life sciences. Unique source characteristics such as high intensity, monochromaticity, coherence and high collimating provide an ideal source for advanced imaging. Phase contrast imaging has been applied in both projection and computed tomography modes, and recent applications have been made in the field of medical imaging. Due to the underlying principle of X-ray detection conventional image receptors register only intensities of wave fields and not their phases. During the last decade basically five different methods were developed that translate the phase information into intensity variations. These methods are based on measuring the phase shift φ directly (using interference phenomena), the gradient ∇ φ , or the Laplacian ∇ 2 φ. All three methods can be applied to polychromatic X-ray sources keeping in mind that the native source is synchrotron radiation, featuring monochromatic and reasonable coherent X-ray beams. Due to the vast difference in the coefficients that are driven absorption and phase effects (factor 1,000-10,000 in the energy

  9. The Value of Contrast Echocardiography

    Directory of Open Access Journals (Sweden)

    Shannon C. Treiber

    2016-01-01

    Full Text Available Purpose: There is much evidence-based research proving the effectiveness of contrast echocardiography, but there are still questions and concerns about its specific uses. This study tested the effectiveness of contrast echocardiography in defining the left ventricular endocardial border. Methods: From 30 patients, a total of 60 echocardiograms –– 30 with and 30 without use of contrast –– were retrospectively reviewed by four blinded cardiologists with advanced training in echocardiography. No single cardiologist reviewed contrast and noncontrast images of the same patient. Each set of 30 echocardiograms was then studied for wall-motion scoring. Visualization of left ventricular wall segments and a global visualization confidence level of interpretation were recorded. Results: Of all wall segments (N = 510, 91% were visualized in echocardiograms with use of contrast, whereas 75% of the walls were visualized in echocardiograms without contrast (P < 0.001. Of 30 examinations, 17 contrast echocardiograms were read with high confidence compared to 6 without contrast use (P = 0.004. The number of walls visualized with contrast was increased in 18 patients (60%, whereas noncontrast echocardiograms yielded more visualized walls in 6 patients (20%, P = 0.002. Conclusions: This study demonstrates that contrast is valuable to echocardiographic imaging. Its use should be supported throughout echocardiography clinics and encouraged in certain patients for whom resting and stress echocardiography results without contrast often prove uninterpretable.

  10. Effects of computed tomography contrast medium factors on contrast enhancement

    International Nuclear Information System (INIS)

    Terasawa, Kazuaki; Hatcho, Atsushi; Okuda, Itsuko

    2011-01-01

    The various nonionic iodinated contrast media used in contrast computed tomography (CT) studies differ in terms of their composition, characteristics, and iodine concentration (mgI/ml), as well as the volume injected (ml). Compared with ionic iodinated contrast media, nonionic iodinated contrast media are low-osmolar agents, with different agents having different osmotic pressures. Using a custom-made phantom incorporating a semipermeable membrane, the osmotic flow rate (hounsfield unit (HU)/s) could easily be measured based on the observed increase in CT numbers, and the relationship between the osmotic pressure and the osmotic flow rate could be obtained (r 2 =0.84). In addition, taking the effects of patient size into consideration, the levels of contrast enhancement in the abdominal aorta (AA) and inferior vena cava (IVC) were compared among four types of CT contrast medium. The results showed differences in contrast enhancement in the IVC during the equilibrium phase depending on the type of contrast medium used. It was found that the factors responsible for the differences observed in enhancement in the IVC were the osmotic flow rate and the volume of the blood flow pathways in the circulatory system. It is therefore considered that the reproducibility of contrast enhancement is likely to be reduced in the examination of parenchymal organs, in which scanning must be performed during the equilibrium phase, even if the amount of iodine injected per unit body weight (mgI/kg) is maintained at a specified level. (author)

  11. Contrast-enhanced endoscopic ultrasonography

    DEFF Research Database (Denmark)

    Reddy, Nischita K; Ioncica, Ana Maria; Saftoiu, Adrian

    2011-01-01

    Contrast agents are increasingly being used to characterize the vasculature in an organ of interest, to better delineate benign from malignant pathology and to aid in staging and directing therapeutic procedures. We review the mechanisms of action of first, second and third generation contrast...... agents and their use in various endoscopic procedures in the gastrointestinal tract. Various applications of contrast-enhanced endoscopic ultrasonography include differentiating benign from malignant mediastinal lymphadenopathy, assessment of depth of invasion of esophageal, gastric and gall bladder...

  12. Properties of conventional contrast media

    International Nuclear Information System (INIS)

    Muetzel, W.

    1981-01-01

    A comprehensive overview is given of the properties of contrast media currently used in computed tomography (CT). The chemical structure of the compounds and the physicochemical properties derived therefrom are described. Emphasis is placed on the importance of the physicochemical properties of contrast media for tolerance and the pharmacokinetic behavior of compounds in the body. An outline is given of the basic ideas governing rational use of contrast media in CT, which result from complex, time-dependent distribution of contrast media in different tissue spaces. (Auth.)

  13. The new numbers contrast sensitivity chart for contrast sensitivity measurement

    Directory of Open Access Journals (Sweden)

    Bharkbhum Khambhiphant

    2011-10-01

    Conclusions: These charts show reasonable agreement and can be used interchangeably with the MARS. It is helpful for Thai people who can only read numbers in doing the test. We can use them in routinely contrast sensitivity measurement.

  14. Contrast-enhanced peripheral MRA. Technique and contrast agents

    International Nuclear Information System (INIS)

    Nielsen, Yousef W.; Thomsen, Henrik S.

    2012-01-01

    In the last decade contrast-enhanced magnetic resonance angiography (CE-MRA) has gained wide acceptance as a valuable tool in the diagnostic work-up of patients with peripheral arterial disease. This review presents current concepts in peripheral CE-MRA with emphasis on MRI technique and contrast agents. Peripheral CE-MRA is defined as an MR angiogram of the arteries from the aortic bifurcation to the feet. Advantages of CE-MRA include minimal invasiveness and lack of ionizing radiation. The basic technique employed for peripheral CE-MRA is the bolus-chase method. With this method a paramagnetic MRI contrast agent is injected intravenously and T1-weighted images are acquired in the subsequent arterial first-pass phase. In order to achieve high quality MR angiograms without interfering venous contamination or artifacts, a number of factors need to be taken into account. This includes magnetic field strength of the MRI system, receiver coil configuration, use of parallel imaging, contrast bolus timing technique, and k-space filling strategies. Furthermore, it is possible to optimize peripheral CE-MRA using venous compression techniques, hybrid scan protocols, time-resolved imaging, and steady-state MRA. Gadolinium(Gd)-based contrast agents are used for CE-MRA of the peripheral arteries. Extracellular Gd agents have a pharmacokinetic profile similar to iodinated contrast media. Accordingly, these agents are employed for first-pass MRA. Blood-pool Gd-based agents are characterized by prolonged intravascular stay, due to macromolecular structure or protein binding. These agents can be used for first-pass, as well as steady-state MRA. Some Gd-based contrast agents with low thermodynamic stability have been linked to development of nephrogenic systemic fibrosis in patients with severe renal insufficiency. Using optimized technique and a stable MRI contrast agent, peripheral CE-MRA is a safe procedure with diagnostic accuracy close to that of conventional catheter X

  15. Adriamycin nephrosis and contrast media

    International Nuclear Information System (INIS)

    Thomsen, H.S.; Golman, K.; Hemmingsen, L.; Larsen, S.; Skaarup, P.; Koebenhavns Amts Sygehus, Herlev; Koebenhavns Amts Sygehus, Herlev; Centralsygehuset, Nykoebing Falster; Malmoe Allmaenna Sjukhus

    1990-01-01

    Urine profiles (albumin, glucose, NAG, LDH, GGT and sodium) were followed for 9 days after intravenous injection of either diatrizoate, iohexol, or saline in 27 Wistar rats with nephrosis induced by Adriamycin 42 days before. Another 9 rats exposed to neither Adriamycin nor contrast media served as controls. None of the contrast media caused further increased albuminuria of significance, whereas both induced significantly increased excretion of all 5 tubular components. The excretion of NAG and sodium was significantly higher following diatrizoate than following iohexol. From 24 h post injection there was no significantly greater excretion of any of the components after either diatrizoate or iohexol than after saline among the rats given Adriamycin. At the end of day 9 after contrast medium injection neither serum sodium, potassium, glucose, urea, creatinine, nor albumin revealed any contrast media related changes. Kidney histology showed quantitatively larger lesions in kidneys exposed to Adriamycin and contrast media than in kidneys exposed to Adriamycin and saline. There were no differences between the two contrast media groups. It is thus concluded, that both high osmolar ionic and low osmolar non-ionic contrast media cause temporary tubular dysfunction but no further glomerular dysfunction in rats with nephrosis induced by Adriamycin. The histologic findings indicate that both media may worsen non-reversible renal lesions. (orig.)

  16. Contrast-enhanced endoscopic ultrasonography

    DEFF Research Database (Denmark)

    Reddy, Nischita K; Ioncică, Ana Maria; Săftoiu, Adrian

    2011-01-01

    Contrast agents are increasingly being used to characterize the vasculature in an organ of interest, to better delineate benign from malignant pathology and to aid in staging and directing therapeutic procedures. We review the mechanisms of action of first, second and third generation contrast...... agents and their use in various endoscopic procedures in the gastrointestinal tract. Various applications of contrast-enhanced endoscopic ultrasonography include differentiating benign from malignant mediastinal lymphadenopathy, assessment of depth of invasion of esophageal, gastric and gall bladder...... cancers and visualization of the portal venous system and esophageal varices. In addition, contrast agents can be used to differentiate pancreatic lesions. The use of color Doppler further increases the ability to diagnose and differentiate various pancreatic malignancies. The sensitivity of power Doppler...

  17. Contrast-enhanced peripheral MRA

    DEFF Research Database (Denmark)

    Nielsen, Yousef W; Thomsen, Henrik S

    2012-01-01

    MRI contrast agent is injected intravenously and T1-weighted images are acquired in the subsequent arterial first-pass phase. In order to achieve high quality MR angiograms without interfering venous contamination or artifacts, a number of factors need to be taken into account. This includes magnetic......-state MRA. Gadolinium(Gd)-based contrast agents are used for CE-MRA of the peripheral arteries. Extracellular Gd agents have a pharmacokinetic profile similar to iodinated contrast media. Accordingly, these agents are employed for first-pass MRA. Blood-pool Gd-based agents are characterized by prolonged...... intravascular stay, due to macromolecular structure or protein binding. These agents can be used for first-pass, as well as steady-state MRA. Some Gd-based contrast agents with low thermodynamic stability have been linked to development of nephrogenic systemic fibrosis in patients with severe renal...

  18. Studies of left ventricular volume estimation from single photon emission computed tomography

    International Nuclear Information System (INIS)

    Hiraki, Yoshio; Shimizu, Mitsuharu; Joja, Ikuo; Aono, Kaname; Yanagi, Hidekiyo; Indo, Haruaki; Seno, Yoshimasa; Teramoto, Shigeru; Nagaya, Isao.

    1988-01-01

    We studied the comparative accuracy of 99m Tc cardiac blood pool Single Photon Emission Computed Tomography (SPECT) for the measurement of left ventricular volume in 20 patients undergoing SPECT and single plane contrast left ventriculography (LVG). Left ventricular volume was calculated based on the total number of voxels in left ventricle. End-diastolic left ventricular volume (EDV) and end-systolic left ventricular volume (ESV) calculated from SPECT were compared with those from LVG. SPECT volume values showed a high degree of correlation with those by LVG (r = 0.923 for EDV, r = 0.903 for ESV). We appreciated the usefulness and accuracy of SPECT in measuring left ventricular volume because of its three-dimensional information. (author)

  19. Contrast Media: Are There Differences in Nephrotoxicity among Contrast Media?

    Science.gov (United States)

    2014-01-01

    Iodinated contrast agents are usually classified based upon their osmolality—high, low, and isosmolar. Iodinated contrast agents are also nephrotoxic in some but not all patients resulting in loss of glomerular filtration rate. Over the past 30 years, nephrotoxicity has been linked to osmolality although the precise mechanism underlying such a link has been elusive. Improvements in our understanding of the pathogenesis of nephrotoxicity and prospective randomized clinical trials have attempted to further explore the relationship between osmolality and nephrotoxicity. In this review, the basis for our current understanding that there are little if any differences in nephrotoxic potential between low and isosmolar contrast media will be detailed using data from clinical studies. PMID:24587997

  20. How to misuse echo contrast

    Directory of Open Access Journals (Sweden)

    Missios Anna

    2009-01-01

    Full Text Available Abstract Background Primary intracardiac tumours are rare, there are however several entities that can mimic tumours. Contrast echocardiography has been suggested to aid the differentiation of various suspected masses. We present a case where transthoracic echocardiography completely misdiagnosed a left atrial mass, partly due to use of echo contrast. Case presentation An 80 year-old woman was referred for transthoracic echocardiography because of one-month duration of worsening of dyspnoea. Transthoracic echocardiography displayed a large echodense mass in the left atrium. Intravenous injection of contrast (SonoVue, Bracco Inc., It indicated contrast-enhancement of the structure, suggesting tumour. Transesophageal echocardiography revealed, however, a completely normal finding in the left atrium. Subsequent gastroscopy examination showed a hiatal hernia. Conclusion It is noteworthy that the transthoracic echocardiographic exam completely misdiagnosed what seemed like a left atrial mass, which in part was an effect of the use of echo contrast. This example highlights that liberal use of transoesophageal echocardiography is often warranted if optimal display of cardiac structures is desired.

  1. Multiscale image contrast amplification (MUSICA)

    Science.gov (United States)

    Vuylsteke, Pieter; Schoeters, Emile P.

    1994-05-01

    This article presents a novel approach to the problem of detail contrast enhancement, based on multiresolution representation of the original image. The image is decomposed into a weighted sum of smooth, localized, 2D basis functions at multiple scales. Each transform coefficient represents the amount of local detail at some specific scale and at a specific position in the image. Detail contrast is enhanced by non-linear amplification of the transform coefficients. An inverse transform is then applied to the modified coefficients. This yields a uniformly contrast- enhanced image without artefacts. The MUSICA-algorithm is being applied routinely to computed radiography images of chest, skull, spine, shoulder, pelvis, extremities, and abdomen examinations, with excellent acceptance. It is useful for a wide range of applications in the medical, graphical, and industrial area.

  2. Contrast enhancement CT by iopamidol

    International Nuclear Information System (INIS)

    Mori, Masaki; Makita, Nobue; Yanai, Kyoko

    1984-01-01

    In order to evaluate the contrast enhancement effect and safety of iopamidol (IOP) in CT examination, IOP was compared with angiographin (AG). In the liver and abdominal aorta, peak CT values were obtained earlier and were higher in the group with AG than in the group with IOP. However, CT values in the group with IOP decreased a little more slowly than those in the group with AG. There was no significant difference in the effect on contrast enhancement between the groups. Intravenous injection of IOP caused lower degree of burning sensation than that of AG, and some of the patients with IOP did not feel burning sensation at all. Changes in clinical laboratory values were slight before and after intravenous injection of IOP. These results suggest that IOP is satisfactory in terms of safety and effect on contrast enhancement in CT examination. (Namekawa, K.)

  3. Contrast-guided image interpolation.

    Science.gov (United States)

    Wei, Zhe; Ma, Kai-Kuang

    2013-11-01

    In this paper a contrast-guided image interpolation method is proposed that incorporates contrast information into the image interpolation process. Given the image under interpolation, four binary contrast-guided decision maps (CDMs) are generated and used to guide the interpolation filtering through two sequential stages: 1) the 45(°) and 135(°) CDMs for interpolating the diagonal pixels and 2) the 0(°) and 90(°) CDMs for interpolating the row and column pixels. After applying edge detection to the input image, the generation of a CDM lies in evaluating those nearby non-edge pixels of each detected edge for re-classifying them possibly as edge pixels. This decision is realized by solving two generalized diffusion equations over the computed directional variation (DV) fields using a derived numerical approach to diffuse or spread the contrast boundaries or edges, respectively. The amount of diffusion or spreading is proportional to the amount of local contrast measured at each detected edge. The diffused DV fields are then thresholded for yielding the binary CDMs, respectively. Therefore, the decision bands with variable widths will be created on each CDM. The two CDMs generated in each stage will be exploited as the guidance maps to conduct the interpolation process: for each declared edge pixel on the CDM, a 1-D directional filtering will be applied to estimate its associated to-be-interpolated pixel along the direction as indicated by the respective CDM; otherwise, a 2-D directionless or isotropic filtering will be used instead to estimate the associated missing pixels for each declared non-edge pixel. Extensive simulation results have clearly shown that the proposed contrast-guided image interpolation is superior to other state-of-the-art edge-guided image interpolation methods. In addition, the computational complexity is relatively low when compared with existing methods; hence, it is fairly attractive for real-time image applications.

  4. Iodinated contrast media nephrotoxicity. Nephrotoxicite des produits de contraste iodes

    Energy Technology Data Exchange (ETDEWEB)

    Meyrier, A. (Hopital Avicenne, 93 - Bobigny (France))

    1994-01-01

    In the late seventies, iodinated contrast agents (ICA) were considered to be a major cause of acute iatrogenic renal failure. Over the last decade new contrast agents have been synthesized, nonionic and less hyperosmolar. The incidence of acute renal failure due to ICAs, varies from 3.7 to 70% of cases according to the series, with an average figure of 10.2%. The pathophysiology of ICA nephrotoxicity was mainly studied in laboratory animal models. Three main factors are involved in an inducing ICA-mediated decrease in glomerular filtration rate: reduction of the renal plasma flow, a direct cytotoxic effect on renal tubular cells and erythrocyte alteration leading to intra-renal sludge. Excluding dysglobulinemias with urinary excretion of immunoglobulin light chains, which represent a special case of maximum nephrotoxicity, 4 main risk factors of renal toxicity have been identified in nondiabetic subjects: previous renal failure with serum creatinine levels greater than 140 [mu]mol per liter, extracellular dehydration, age over 60 and use of high doses of ICA and/or repeated ICA injections before serum creatinine levels return to baseline. Preventive measures for avoiding ICA nephrotoxicity are threefold: maintain or restore adequate hydration with saline infusion, stop NSAID treatment several days before ICA administration, and allow a 5 day interval before repeating contrast media injections. New, nonionic and moderately hyperosmolar contrast agents appear to be much less nephrotoxic than conventional ICAs in laboratory animals and in high-risk patients. It is advisable to select such contrast media for investigating high-risk patients. This approach was recently substantiated in well designed, randomized clinical studies which included more than 2 000 patients. (author).

  5. Quantitative contrast-enhanced mammography for contrast medium kinetics studies

    Science.gov (United States)

    Arvanitis, C. D.; Speller, R.

    2009-10-01

    Quantitative contrast-enhanced mammography, based on a dual-energy approach, aims to extract quantitative and temporal information of the tumour enhancement after administration of iodinated vascular contrast media. Simulations using analytical expressions and optimization of critical parameters essential for the development of quantitative contrast-enhanced mammography are presented. The procedure has been experimentally evaluated using a tissue-equivalent phantom and an amorphous silicon active matrix flat panel imager. The x-ray beams were produced by a tungsten target tube and spectrally shaped using readily available materials. Measurement of iodine projected thickness in mg cm-2 has been performed. The effect of beam hardening does not introduce nonlinearities in the measurement of iodine projected thickness for values of thicknesses found in clinical investigations. However, scattered radiation introduces significant deviations from slope equal to unity when compared with the actual iodine projected thickness. Scatter correction before the analysis of the dual-energy images provides accurate iodine projected thickness measurements. At 10% of the exposure used in clinical mammography, signal-to-noise ratios in excess of 5 were achieved for iodine projected thicknesses less than 3 mg cm-2 within a 4 cm thick phantom. For the extraction of temporal information, a limited number of low-dose images were used with the phantom incorporating a flow of iodinated contrast medium. The results suggest that spatial and temporal information of iodinated contrast media can be used to indirectly measure the tumour microvessel density and determine its uptake and washout from breast tumours. The proposed method can significantly improve tumour detection in dense breasts. Its application to perform in situ x-ray biopsy and assessment of the oncolytic effect of anticancer agents is foreseeable.

  6. Ultrasound Contrast Agent Microbubble Dynamics

    NARCIS (Netherlands)

    Overvelde, M.L.J.; Vos, Henk; de Jong, N.; Versluis, Michel; Paradossi, Gaio; Pellegretti, Paolo; Trucco, Andrea

    2010-01-01

    Ultrasound contrast agents are traditionally used in ultrasound-assisted organ perfusion imaging. Recently the use of coated microbubbles has been proposed for molecular imaging applications where the bubbles are covered with a layer of targeting ligands to bind specifically to their target cells.

  7. Color contrasting in radioscopy systems

    International Nuclear Information System (INIS)

    Lopaev, V.P.; Pavlov, S.V.; Nazarenko, V.G.

    1979-01-01

    Transformation principles for achromatic radioscopy control systems to color ones have been considered. Described is the developed ''Gamma 1'' roentgen-TV facility with color contrasting, which is based on the principle of analog conversion of brightness signal to a hue. By means of color channels amplifiers realized are the special amplitude characteristics, permitting in comparison with the common method of analogous transformation to obtain the greater number of hues within the identical range of brightnesses of image under investigation due to introducing purple colors. The investigation of amplitude resolution capability of color contrasting device has shown, that in the case of color contrasting of image the amplitude resolution is 1.7-1.8 time higher than in the case of achromatic one. Defectoscopic sensitivity during the testing of 5-20 mm thick steel products in the process of experimental-production tests turned out to be 1.1-1.3 time higher when using color contrasting of radioscopic image. Realization simplicity, high resolution, noise stability and wide functional possibilities of the facility show the prospects for its using during the quality control of welded joints in products of power engineering

  8. Ionic versus nonionic contrast media

    International Nuclear Information System (INIS)

    Zylak, C.J.; Gafni, A.

    1988-01-01

    The efficacy and effectiveness of the nonionic contrast media have been established. Widespread usage has been hampered because of the approximate tenfold increase in cost compared with the ionic media. An economic evaluation considering costs and consequences of both interventions (ionic vs nonionic contrast media) was performed; it is a cost effectiveness (CEA) and a cost-benefit analysis (CBA) for the Canadian experience. The results of the CEA demonstrate a value per life-year saved within an acceptable range when compared with value for quality-adjusted life years for programs such as treatment of severe (diastolic≥ 105 mm Hg) and mild (diastolic 95-104 mm Hg) hypertension in men aged 40. The CBA showed a net cost to society when benefits were measured as future treatment costs saved plus productivity gained. However, if people are willing to pay a small amount for the comfort of the new intervention, this will result in a break-even situation

  9. Contrast-enhanced MR angiography

    International Nuclear Information System (INIS)

    Bosmans, H.; Marchal, G.

    1996-01-01

    Despite many optimizations, the current limitations of plain MR angiography include: Saturation that impairs the visualization of veins and arteries with slow flow and spin-dephasing signal voids in locations with turbulent flow. Recently, the use of contrast agents has been proposed to cope with these remaining problems. Because of induced shortening of the T1 of the blood, saturation in the blood vessels is overcome. As a result, arteries and veins are visualized with the same signal intensity, which makes the technique less flow-dependent. In combination with short T1-weighted acquisitions, today CE MRA can be obtained while the patient is holding his breath. This last approach is most promising for abdominal applications since the respiratory motion can be frozen. As these acquisitions also use very short echo times, spin dephasing can be reduced. In conclusion, the use of contrast agents has greatly increased the clinical usefulness of MR angiography. (orig.) [de

  10. Minimum resolvable power contrast model

    Science.gov (United States)

    Qian, Shuai; Wang, Xia; Zhou, Jingjing

    2018-01-01

    Signal-to-noise ratio and MTF are important indexs to evaluate the performance of optical systems. However,whether they are used alone or joint assessment cannot intuitively describe the overall performance of the system. Therefore, an index is proposed to reflect the comprehensive system performance-Minimum Resolvable Radiation Performance Contrast (MRP) model. MRP is an evaluation model without human eyes. It starts from the radiance of the target and the background, transforms the target and background into the equivalent strips,and considers attenuation of the atmosphere, the optical imaging system, and the detector. Combining with the signal-to-noise ratio and the MTF, the Minimum Resolvable Radiation Performance Contrast is obtained. Finally the detection probability model of MRP is given.

  11. Effects of theophyline on contrast

    OpenAIRE

    A.R. Fatahiyan; B. Baqerii; A. Mohseni; A. Makhlouq

    2006-01-01

    Background and purpose: Contrast-induced nephropathy (CN) is one of the most common causes of iatrogenic acute renal failure. In fact CN is the third leading cause of new ARF in hospitalized patients. Radiocontrast-associated ARF is a significant problem in patients with cardiovascular disease. The risk factors for cardiovascular disease also predispose these patients to an increased risk of renal failure. Various strategies have been suggested for preventing CN. Since adenosine may play a ro...

  12. Contrast detail phantom for SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Cabrejas, M.L. de; Arashiro, J G; Giannone, C. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Camuyrano, M; Nohara, G [Universidad de Buenos Aires, Buenos Aires (Argentina). Facultad Ciencias Exactas

    1996-06-01

    A new low variable contrast phantom for single photon emission computed tomography (SPECT) was constructed, tested and compared with other existing phantoms. It contains simulated cylindrical lesions of four different diameters (D{sub i}), embedded in a cylindrical scattering medium and a uniform section to evaluate tomographic uniformity. The concentration of tracer in the simulated lesions and the scattering medium (background) can be varied to simulate hot and cold lesions. Different applications of the phantom were tested, including determination of the minimum object contrast (OCm) necessary to detect lesions as a function of lesion size, lesion type (hot or cold) and acquisition and processing protocols by visual inspection. This parameter allows categorization of instruments comparing an `image quality index` (IQI). Preliminary comparison with the Britten contrast processing method showed that the detectable OCm was of the same order of magnitude, but the presented device seems more suitable for training and intercomparison purposes. The constructed phantom, of simple design, has proved to be useful for acquisition and processing condition evaluation, OCm estimation and external quality control. (author). 11 refs, 4 figs.

  13. Advancing High Contrast Adaptive Optics

    Science.gov (United States)

    Ammons, M.; Poyneer, L.; GPI Team

    2014-09-01

    A long-standing challenge has been to directly image faint extrasolar planets adjacent to their host suns, which may be ~1-10 million times brighter than the planet. Several extreme AO systems designed for high-contrast observations have been tested at this point, including SPHERE, Magellan AO, PALM-3000, Project 1640, NICI, and the Gemini Planet Imager (GPI, Macintosh et al. 2014). The GPI is the world's most advanced high-contrast adaptive optics system on an 8-meter telescope for detecting and characterizing planets outside of our solar system. GPI will detect a previously unstudied population of young analogs to the giant planets of our solar system and help determine how planetary systems form. GPI employs a 44x44 woofer-tweeter adaptive optics system with a Shack-Hartmann wavefront sensor operating at 1 kHz. The controller uses Fourier-based reconstruction and modal gains optimized from system telemetry (Poyneer et al. 2005, 2007). GPI has an apodized Lyot coronal graph to suppress diffraction and a near-infrared integral field spectrograph for obtaining planetary spectra. This paper discusses current performance limitations and presents the necessary instrumental modifications and sensitivity calculations for scenarios related to high-contrast observations of non-sidereal targets.

  14. Electrofluidic systems for contrast management

    Science.gov (United States)

    Rebello, Keith J.; Maranchi, Jeffrey P.; Tiffany, Jason E.; Brown, Christopher Y.; Maisano, Adam J.; Hagedon, Matthew A.; Heikenfeld, Jason C.

    2012-06-01

    Operating in dynamic lighting conditions and in greatly varying backgrounds is challenging. Current paints and state-ofthe- art passive adaptive coatings (e.g. photochromics) are not suitable for multi- environment situations. A semi-active, low power, skin is needed that can adapt its reflective properties based on the background environment to minimize contrast through the development and incorporation of suitable pigment materials. Electrofluidic skins are a reflective display technology for electronic ink and paper applications. The technology is similar to that in E Ink but makes use of MEMS based microfluidic structures, instead of simple black and white ink microcapsules dispersed in clear oil. Electrofluidic skin's low power operation and fast switching speeds (~20 ms) are an improvement over current state-ofthe- art contrast management technologies. We report on a microfluidic display which utilizes diffuse pigment dispersion inks to change the contrast of the underlying substrate from 5.8% to 100%. Voltage is applied and an electromechanical pressure is used to pull a pigment dispersion based ink from a hydrophobic coated reservoir into a hydrophobic coated surface channel. When no voltage is applied, the Young-Laplace pressure pushes the pigment dispersion ink back down into the reservoir. This allows the pixel to switch from the on and off state by balancing the two pressures. Taking a systems engineering approach from the beginning of development has enabled the technology to be integrated into larger systems.

  15. Phase contrast STEM for thin samples: Integrated differential phase contrast.

    Science.gov (United States)

    Lazić, Ivan; Bosch, Eric G T; Lazar, Sorin

    2016-01-01

    It has been known since the 1970s that the movement of the center of mass (COM) of a convergent beam electron diffraction (CBED) pattern is linearly related to the (projected) electrical field in the sample. We re-derive a contrast transfer function (CTF) for a scanning transmission electron microscopy (STEM) imaging technique based on this movement from the point of view of image formation and continue by performing a two-dimensional integration on the two images based on the two components of the COM movement. The resulting integrated COM (iCOM) STEM technique yields a scalar image that is linear in the phase shift caused by the sample and therefore also in the local (projected) electrostatic potential field of a thin sample. We confirm that the differential phase contrast (DPC) STEM technique using a segmented detector with 4 quadrants (4Q) yields a good approximation for the COM movement. Performing a two-dimensional integration, just as for the COM, we obtain an integrated DPC (iDPC) image which is approximately linear in the phase of the sample. Beside deriving the CTFs of iCOM and iDPC, we clearly point out the objects of the two corresponding imaging techniques, and highlight the differences to objects corresponding to COM-, DPC-, and (HA) ADF-STEM. The theory is validated with simulations and we present first experimental results of the iDPC-STEM technique showing its capability for imaging both light and heavy elements with atomic resolution and a good signal to noise ratio (SNR). Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Radiographic contrast media, function and future reassessed

    International Nuclear Information System (INIS)

    Sovak, M.

    1988-01-01

    A brief review is given of the use of radiographic contrast media in cholecysto- and cholangiography, central nervous system imaging, urography and angiography. Other aspects briefly discussed are the use of large i.v. doses of contrast media for CT contrast enhancement and the design theory for improved water soluble contrast media. (U.K.)

  17. Ultrasound contrast agents: an overview.

    Science.gov (United States)

    Cosgrove, David

    2006-12-01

    With the introduction of microbubble contrast agents, diagnostic ultrasound has entered a new era that allows the dynamic detection of tissue flow of both the macro and microvasculature. Underpinning this development is the fact that gases are compressible, and thus the microbubbles expand and contract in the alternating pressure waves of the ultrasound beam, while tissue is almost incompressible. Special software using multiple pulse sequences separates these signals from those of tissue and displays them as an overlay or on a split screen. This can be done at low acoustic pressures (MIdeveloped for myocardial perfusion. In radiology, the most important application is the liver, especially for focal disease. The approach parallels that of dynamic CT or MRI but ultrasound has the advantages of high spatial and temporal resolution. Thus, small lesions that can be indeterminate on CT can often be studied with ultrasound, and situations where the flow is very rapid (e.g., focal nodular hyperplasia where the first few seconds of arterial perfusion may be critical to making the diagnosis) are readily studied. Microbubbles linger in the extensive sinusoidal space of normal liver for several minutes whereas they wash out rapidly from metastases, which have a low vascular volume and thus appear as filling defects. The method has been shown to be as sensitive as three-phase CT. Microbubbles have clinical uses in many other applications where knowledge of the microcirculation is important (the macrocirculation can usually be assessed adequately using conventional Doppler though there are a few important situations where the signal boost given by microbubbles is useful, e.g., transcranial Doppler for evaluating vasospasm after subarachnoid haemorrhage). An important situation where demonstrating tissue devitalisation is important is in interstitial ablation of focal liver lesions: using microbubble contrast agents at the end of a procedure allows immediate evaluation of the

  18. Do intravenous N-acetylcysteine and sodium bicarbonate prevent high osmolal contrast-induced acute kidney injury? A randomized controlled trial.

    Directory of Open Access Journals (Sweden)

    Antonio Jose Inda-Filho

    Full Text Available N-acetylcysteine (NAC or sodium bicarbonate (NaHCO3, singly or combined, inconsistently prevent patients exposed to radiographic contrast media from developing contrast-induced acute kidney injury (CI-AKI.We asked whether intravenous isotonic saline and either NaHCO3 in 5% dextrose or else a high dose of NAC in 5% dextrose prevent CI-AKI in outpatients exposed to high-osmolal iodinated contrast medium more than does saline alone.This completed prospective, parallel, superiority, open-label, controlled, computer-randomized, single-center, Brazilian trial (NCT01612013 hydrated 500 adult outpatients (214 at high risk of developing CI-AKI exposed to ioxitalamate during elective coronary angiography and ventriculography. From 1 hour before through 6 hours after exposure, 126 patients (group 1 received a high dose of NAC and saline, 125 (group 2 received NaHCO3 and saline, 124 (group 3 received both treatments, and 125 (group 4 received only saline.Groups were similar with respect to age, gender, weight, pre-existing renal dysfunction, hypertension, medication, and baseline serum creatinine and serum cystatin C, but diabetes mellitus was significantly less prevalent in group 1. CI-AKI incidence 72 hours after exposure to contrast medium was 51.4% (257/500, measured as serum creatinine > (baseline+0.3 mg/dL and/or serum cystatin C > (1.1 · baseline, and 7.6% (38/500, measured as both serum creatinine and serum cystatin C > (baseline+0.3 mg/dL or > (1.25 · baseline. CI-AKI incidence measured less sensitively was similar among groups. Measured more sensitively, incidence in group 1 was significantly (p<0.05 lower than in groups 2 and 3 but not group 4; adjustment for confounding by infused volume equalized incidence in groups 1 and 3.We found no evidence that intravenous isotonic saline and either NaHCO3 or else a high dose of NAC prevent CI-AKI in outpatients exposed to high osmolal iodinated contrast medium more than does saline alone

  19. Clinical applications of contrast echocardiography

    International Nuclear Information System (INIS)

    Jorge, Leon Galindo

    2005-01-01

    The echocardiography is the technique more used for the diagnosis and pursuit of the cardiovascular illnesses; therefore, their diagnostic precision has acquired a vital importance in the handling of the patients with cardiovascular pathologies. However, with relative frequency, the diagnostic capacity of the echocardiography exam is diminished by limitations of the acoustic window, mainly in-patient with obesity, lung illnesses and alterations of the thoracic wall. This can be obviated with the use of the intra-esophagus echocardiography, although this it is a procedure semi-invasive and not very practical of carrying out in all the patients with problems of acoustic window. In this article the clinical applications are revised more common of the contrast echocardiography

  20. Ultrasound contrast agents: An overview

    International Nuclear Information System (INIS)

    Cosgrove, David

    2006-01-01

    With the introduction of microbubble contrast agents, diagnostic ultrasound has entered a new era that allows the dynamic detection of tissue flow of both the macro and microvasculature. Underpinning this development is the fact that gases are compressible, and thus the microbubbles expand and contract in the alternating pressure waves of the ultrasound beam, while tissue is almost incompressible. Special software using multiple pulse sequences separates these signals from those of tissue and displays them as an overlay or on a split screen. This can be done at low acoustic pressures (MI < 0.3) so that the microbubbles are not destroyed and scanning can continue in real time. The clinical roles of contrast enhanced ultrasound scanning are expanding rapidly. They are established in echocardiography to improve endocardial border detection and are being developed for myocardial perfusion. In radiology, the most important application is the liver, especially for focal disease. The approach parallels that of dynamic CT or MRI but ultrasound has the advantages of high spatial and temporal resolution. Thus, small lesions that can be indeterminate on CT can often be studied with ultrasound, and situations where the flow is very rapid (e.g., focal nodular hyperplasia where the first few seconds of arterial perfusion may be critical to making the diagnosis) are readily studied. Microbubbles linger in the extensive sinusoidal space of normal liver for several minutes whereas they wash out rapidly from metastases, which have a low vascular volume and thus appear as filling defects. The method has been shown to be as sensitive as three-phase CT. Microbubbles have clinical uses in many other applications where knowledge of the microcirculation is important (the macrocirculation can usually be assessed adequately using conventional Doppler though there are a few important situations where the signal boost given by microbubbles is useful, e.g., transcranial Doppler for evaluating

  1. Phase contrast STEM for thin samples: Integrated differential phase contrast

    International Nuclear Information System (INIS)

    Lazić, Ivan; Bosch, Eric G.T.; Lazar, Sorin

    2016-01-01

    It has been known since the 1970s that the movement of the center of mass (COM) of a convergent beam electron diffraction (CBED) pattern is linearly related to the (projected) electrical field in the sample. We re-derive a contrast transfer function (CTF) for a scanning transmission electron microscopy (STEM) imaging technique based on this movement from the point of view of image formation and continue by performing a two-dimensional integration on the two images based on the two components of the COM movement. The resulting integrated COM (iCOM) STEM technique yields a scalar image that is linear in the phase shift caused by the sample and therefore also in the local (projected) electrostatic potential field of a thin sample. We confirm that the differential phase contrast (DPC) STEM technique using a segmented detector with 4 quadrants (4Q) yields a good approximation for the COM movement. Performing a two-dimensional integration, just as for the COM, we obtain an integrated DPC (iDPC) image which is approximately linear in the phase of the sample. Beside deriving the CTFs of iCOM and iDPC, we clearly point out the objects of the two corresponding imaging techniques, and highlight the differences to objects corresponding to COM-, DPC-, and (HA) ADF-STEM. The theory is validated with simulations and we present first experimental results of the iDPC-STEM technique showing its capability for imaging both light and heavy elements with atomic resolution and a good signal to noise ratio (SNR). - Highlights: • First DPC-based atomic resolution images of potential and charge density are obtained. • This is enabled by integration and differentiation of 2D DPC signals, respectively. • Integrated DPC (iDPC) based on 4 quadrant imaging is compared to iCOM imaging. • Noise analysis and comparison with standard STEM imaging modes is provided. • iDPC allows direct imaging of light (C, N, O …) and heavy (Ga, Au …) atoms together.

  2. Phase contrast STEM for thin samples: Integrated differential phase contrast

    Energy Technology Data Exchange (ETDEWEB)

    Lazić, Ivan, E-mail: ivan.lazic@fei.com; Bosch, Eric G.T.; Lazar, Sorin

    2016-01-15

    It has been known since the 1970s that the movement of the center of mass (COM) of a convergent beam electron diffraction (CBED) pattern is linearly related to the (projected) electrical field in the sample. We re-derive a contrast transfer function (CTF) for a scanning transmission electron microscopy (STEM) imaging technique based on this movement from the point of view of image formation and continue by performing a two-dimensional integration on the two images based on the two components of the COM movement. The resulting integrated COM (iCOM) STEM technique yields a scalar image that is linear in the phase shift caused by the sample and therefore also in the local (projected) electrostatic potential field of a thin sample. We confirm that the differential phase contrast (DPC) STEM technique using a segmented detector with 4 quadrants (4Q) yields a good approximation for the COM movement. Performing a two-dimensional integration, just as for the COM, we obtain an integrated DPC (iDPC) image which is approximately linear in the phase of the sample. Beside deriving the CTFs of iCOM and iDPC, we clearly point out the objects of the two corresponding imaging techniques, and highlight the differences to objects corresponding to COM-, DPC-, and (HA) ADF-STEM. The theory is validated with simulations and we present first experimental results of the iDPC-STEM technique showing its capability for imaging both light and heavy elements with atomic resolution and a good signal to noise ratio (SNR). - Highlights: • First DPC-based atomic resolution images of potential and charge density are obtained. • This is enabled by integration and differentiation of 2D DPC signals, respectively. • Integrated DPC (iDPC) based on 4 quadrant imaging is compared to iCOM imaging. • Noise analysis and comparison with standard STEM imaging modes is provided. • iDPC allows direct imaging of light (C, N, O …) and heavy (Ga, Au …) atoms together.

  3. Evaluation of contrast in duplicated radiographs

    International Nuclear Information System (INIS)

    Thunthy, K.H.; Weinberg, R.

    1982-01-01

    This investigation evaluated changes in the contrast of duplicated radiographs made at different ultraviolet light exposures. Increasing ultraviolet light exposure had different effects on the duplicates of originals of different background densities. When correctly exposed, a duplicate radiograph enhanced contrast. When originals had the same contrast but different background densities, their duplicates did not have the same contrast. It was not possible to duplicate accurately all the different contrasts measured on an original. It was possible, however, to produce duplicates with all contrasts greater than those of the original

  4. Binocular contrast discrimination needs monocular multiplicative noise

    Science.gov (United States)

    Ding, Jian; Levi, Dennis M.

    2016-01-01

    The effects of signal and noise on contrast discrimination are difficult to separate because of a singularity in the signal-detection-theory model of two-alternative forced-choice contrast discrimination (Katkov, Tsodyks, & Sagi, 2006). In this article, we show that it is possible to eliminate the singularity by combining that model with a binocular combination model to fit monocular, dichoptic, and binocular contrast discrimination. We performed three experiments using identical stimuli to measure the perceived phase, perceived contrast, and contrast discrimination of a cyclopean sine wave. In the absence of a fixation point, we found a binocular advantage in contrast discrimination both at low contrasts (discrimination mechanisms: a nonlinear contrast transducer and multiplicative noise (MN). A binocular combination model (the DSKL model; Ding, Klein, & Levi, 2013b) was first fitted to both the perceived-phase and the perceived-contrast data sets, then combined with either the nonlinear contrast transducer or the MN mechanism to fit the contrast-discrimination data. We found that the best model combined the DSKL model with early MN. Model simulations showed that, after going through interocular suppression, the uncorrelated noise in the two eyes became anticorrelated, resulting in less binocular noise and therefore a binocular advantage in the discrimination task. Combining a nonlinear contrast transducer or MN with a binocular combination model (DSKL) provides a powerful method for evaluating the two putative contrast-discrimination mechanisms. PMID:26982370

  5. Brute force absorption contrast microtomography

    Science.gov (United States)

    Davis, Graham R.; Mills, David

    2014-09-01

    In laboratory X-ray microtomography (XMT) systems, the signal-to-noise ratio (SNR) is typically determined by the X-ray exposure due to the low flux associated with microfocus X-ray tubes. As the exposure time is increased, the SNR improves up to a point where other sources of variability dominate, such as differences in the sensitivities of adjacent X-ray detector elements. Linear time-delay integration (TDI) readout averages out detector sensitivities on the critical horizontal direction and equiangular TDI also averages out the X-ray field. This allows the SNR to be increased further with increasing exposure. This has been used in dentistry to great effect, allowing subtle variations in dentine mineralisation to be visualised in 3 dimensions. It has also been used to detect ink in ancient parchments that are too damaged to physically unroll. If sufficient contrast between the ink and parchment exists, it is possible to virtually unroll the tomographic image of the scroll in order that the text can be read. Following on from this work, a feasibility test was carried out to determine if it might be possible to recover images from decaying film reels. A successful attempt was made to re-create a short film sequence from a rolled length of 16mm film using XMT. However, the "brute force" method of scaling this up to allow an entire film reel to be imaged presents a significant challenge.

  6. Integral equations with contrasting kernels

    Directory of Open Access Journals (Sweden)

    Theodore Burton

    2008-01-01

    Full Text Available In this paper we study integral equations of the form $x(t=a(t-\\int^t_0 C(t,sx(sds$ with sharply contrasting kernels typified by $C^*(t,s=\\ln (e+(t-s$ and $D^*(t,s=[1+(t-s]^{-1}$. The kernel assigns a weight to $x(s$ and these kernels have exactly opposite effects of weighting. Each type is well represented in the literature. Our first project is to show that for $a\\in L^2[0,\\infty$, then solutions are largely indistinguishable regardless of which kernel is used. This is a surprise and it leads us to study the essential differences. In fact, those differences become large as the magnitude of $a(t$ increases. The form of the kernel alone projects necessary conditions concerning the magnitude of $a(t$ which could result in bounded solutions. Thus, the next project is to determine how close we can come to proving that the necessary conditions are also sufficient. The third project is to show that solutions will be bounded for given conditions on $C$ regardless of whether $a$ is chosen large or small; this is important in real-world problems since we would like to have $a(t$ as the sum of a bounded, but badly behaved function, and a large well behaved function.

  7. Modified Regression Rate Formula of PMMA Combustion by a Single Plane Impinging Jet

    Directory of Open Access Journals (Sweden)

    Tsuneyoshi Matsuoka

    2017-01-01

    Full Text Available A modified regression rate formula for the uppermost stage of CAMUI-type hybrid rocket motor is proposed in this study. Assuming a quasi-steady, one-dimensional, an energy balance against a control volume near the fuel surface is considered. Accordingly, the regression rate formula which can calculate the local regression rate by the quenching distance between the flame and the regression surface is derived. An experimental setup which simulates the combustion phenomenon involved in the uppermost stage of a CAMUI-type hybrid rocket motor was constructed and the burning tests with various flow velocities and impinging distances were performed. A PMMA slab of 20 mm height, 60 mm width, and 20 mm thickness was chosen as a sample specimen and pure oxygen and O2/N2 mixture (50/50 vol.% were employed as the oxidizers. The time-averaged regression rate along the fuel surface was measured by a laser displacement sensor. The quenching distance during the combustion event was also identified from the observation. The comparison between the purely experimental and calculated values showed good agreement, although a large systematic error was expected due to the difficulty in accurately identifying the quenching distance.

  8. Kinematic Measurement of Knee Prosthesis from Single-Plane Projection Images

    Science.gov (United States)

    Hirokawa, Shunji; Ariyoshi, Shogo; Takahashi, Kenji; Maruyama, Koichi

    In this paper, the measurement of 3D motion from 2D perspective projections of knee prosthesis is described. The technique reported by Banks and Hodge was further developed in this study. The estimation was performed in two steps. The first-step estimation was performed on the assumption of orthogonal projection. Then, the second-step estimation was subsequently carried out based upon the perspective projection to accomplish more accurate estimation. The simulation results have demonstrated that the technique archived sufficient accuracies of position/orientation estimation for prosthetic kinematics. Then we applied our algorithm to the CCD images, thereby examining the influences of various artifacts, possibly incorporated through an imaging process, on the estimation accuracies. We found that accuracies in the experiment were influenced mainly by the geometric discrepancies between the prosthesis component and computer generated model and by the spacial inconsistencies between the coordinate axes of the positioner and that of the computer model. However, we verified that our algorithm could achieve proper and consistent estimation even for the CCD images.

  9. Contrast enhanced CT of spinal cord angioma

    International Nuclear Information System (INIS)

    Nakamura, Takahiko; Ebitani, Tsutomu; Honma, Takao; Sofue, Muroto; Nakamura, Shigeru

    1982-01-01

    Contrast enhanced CT on 6 patients with spinal cord angioma showed enhancement in 2 of them. The conditions to produce contrast enhancement were the window width of 100 - 200, and the window level of 0 - 50. In spinal cord angioma, contrast enhanced CT is presently only an adjunct to angiography and myelography. Nevertheless, contrast enhanced CT is useful in the screening test for spinal cord angioma, in the patients who are nonindicated to angiography, and in the postoperative follow-up. (Ueda, J.)

  10. Using Contrastive Rhetoric in the ESL Classroom

    Science.gov (United States)

    Quinn, Janet M.

    2012-01-01

    Contrastive rhetoric studies the writing of second language learners to understand how it is affected by their first language and culture. The field of contrastive rhetoric is as multidimensional as second language writing is complex. It draws on the work of contrastive analysis, anthropology, linguistics, pedagogy, culture studies, translation…

  11. Contrast media are helpful in computerized tomography

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    Contrast media very often can decisively improve the image contrasts, and thus contribute to making the differential diagnosis more specific. This survey of a symposium on the current status of CT refers particularly to the lectures that discussed the use of contrast media for neuroradiology, and the risks involved. (orig.) [de

  12. Effect of intensifying screens to subject contrast

    International Nuclear Information System (INIS)

    Lee, In Ja; Huh, Joon; Kang, Hong Seok; Yoon, Chul Ho

    1990-01-01

    It is an experimental report about object contrast according to the Kinds of screen and obtained results as follows ; 1. In the same object radiography, use acquired the difference of the object contrast between LT-II(CaWO 4 system) and G4(Gd system) screens. 2. object contrast more decreased in Gd system screen than CaWO 4 and object contrast controlled by X-ray tube voltage. 3. The difference of object contrast seen clearly in 80 kVp

  13. Contrast Enhanced US in the Abdomen

    International Nuclear Information System (INIS)

    Chung, Yong Eun; Kim, Ki Whang

    2012-01-01

    Contrast enhanced ultrasound, which was introduced in 1996, has been widely used in Europe and Eastern Asia. Ultrasound contrast agent can be classified as first generation and second generation, depending on the gas within the microbubble. With the first generation contrast agent, the high MI technique was used, and only intermittent scanning was possible due to destruction of the microbubble during scanning. Use of the second generation contrast agent with the low MI technique makes continuous scanning possible. Contrast enhanced US can be used in detection and differentiation of focal liver lesions. It is also helpful for monitoring of radiofrequency ablation and for targeting of US guided biopsy. Currently, because morphologic criteria alone may not reflect the response of the tumor to treatment, new criteria are needed for treatment evaluation after administration of anti-angiogenic agents. Contrast enhanced US could provide quantitative markers for evaluation of the response to treatment via use of dynamic contrast enhanced US. Due to cost-effectiveness, contrast enhanced US is not yet widely used in Korea; however, considering recent issues regarding contrast agent related adverse reaction, such as contrast induced nephropathy and nephrogenic systemic fibrosis, and radiation exposure, contrast enhanced US might be more widely used in Korea, as an alternative imaging modality in the future.

  14. MRI and CT contrast media extravasation

    Science.gov (United States)

    Heshmatzadeh Behzadi, Ashkan; Farooq, Zerwa; Newhouse, Jeffery H.; Prince, Martin R.

    2018-01-01

    Abstract Background: This systematic review combines data from multiple papers on contrast media extravasation to identify factors contributing to increased extravasation risk. Methods: Data were extracted from 17 papers reporting 2191 extravasations in 1,104,872 patients (0.2%) undergoing computed tomography (CT) or magnetic resonance imaging (MRI). Results: Extravasation rates were 0.045% for gadolinium-based contrast agents (GBCA) and nearly 6-fold higher, 0.26% for iodinated contrast agents. Factors associated with increased contrast media extravasations included: older age, female gender, using an existing intravenous (IV) instead of placing a new IV in radiology, in-patient status, use of automated power injection, high injection rates, catheter location, and failing to warm up the more viscous contrast media to body temperature. Conclusion: Contrast media extravasation is infrequent but nearly 6 times less frequent with GBCA for MRI compared with iodinated contrast used in CT. PMID:29489663

  15. Flash Infrared Thermography Contrast Data Analysis Technique

    Science.gov (United States)

    Koshti, Ajay

    2014-01-01

    This paper provides information on an IR Contrast technique that involves extracting normalized contrast versus time evolutions from the flash thermography inspection infrared video data. The analysis calculates thermal measurement features from the contrast evolution. In addition, simulation of the contrast evolution is achieved through calibration on measured contrast evolutions from many flat-bottom holes in the subject material. The measurement features and the contrast simulation are used to evaluate flash thermography data in order to characterize delamination-like anomalies. The thermal measurement features relate to the anomaly characteristics. The contrast evolution simulation is matched to the measured contrast evolution over an anomaly to provide an assessment of the anomaly depth and width which correspond to the depth and diameter of the equivalent flat-bottom hole (EFBH) similar to that used as input to the simulation. A similar analysis, in terms of diameter and depth of an equivalent uniform gap (EUG) providing a best match with the measured contrast evolution, is also provided. An edge detection technique called the half-max is used to measure width and length of the anomaly. Results of the half-max width and the EFBH/EUG diameter are compared to evaluate the anomaly. The information provided here is geared towards explaining the IR Contrast technique. Results from a limited amount of validation data on reinforced carbon-carbon (RCC) hardware are included in this paper.

  16. Contrast media. Safety issues and ESUR guidelines

    Energy Technology Data Exchange (ETDEWEB)

    Thomsen, H.S. (ed.) [Copenhagen Univ. Hospital, Herlev (Denmark). Dept. of Diagnostic Radiology 54E2

    2006-07-01

    In 1994 the European Society of Urogenital Radiology (ESUR) set up a committee to consider the safety of the contrast media used in radiology departments. Since then, the committee has questioned members, reviewed the literature, proposed guidelines, and discussed these proposals with participants at the annual symposia on urogenital radiology. This book represents the end result of this hard work. It contains all of the agreed guidelines, updated when necessary, and thereby comprehensively covers the many different safety issues relating to the diverse contrast media: barium contrast media, iodinated contrast media, MR contrast media (both gadolinium-based extracellular and organ-specific) and ultrasound contrast media. The prevention and treatment of both acute and delayed non-renal adverse reactions as well as the renal adverse reactions are covered in detail. The inclusion of all the ESUR guidelines within one book will offer an invaluable, unique and unparalleled resource. (orig.)

  17. Contrast media. Safety issues and ESUR guidelines

    International Nuclear Information System (INIS)

    Thomsen, H.S.

    2006-01-01

    In 1994 the European Society of Urogenital Radiology (ESUR) set up a committee to consider the safety of the contrast media used in radiology departments. Since then, the committee has questioned members, reviewed the literature, proposed guidelines, and discussed these proposals with participants at the annual symposia on urogenital radiology. This book represents the end result of this hard work. It contains all of the agreed guidelines, updated when necessary, and thereby comprehensively covers the many different safety issues relating to the diverse contrast media: barium contrast media, iodinated contrast media, MR contrast media (both gadolinium-based extracellular and organ-specific) and ultrasound contrast media. The prevention and treatment of both acute and delayed non-renal adverse reactions as well as the renal adverse reactions are covered in detail. The inclusion of all the ESUR guidelines within one book will offer an invaluable, unique and unparalleled resource. (orig.)

  18. Contrast-enhanced harmonic endoscopic ultrasound

    DEFF Research Database (Denmark)

    Săftoiu, A; Dietrich, C F; Vilmann, P

    2012-01-01

    Second-generation intravenous blood-pool ultrasound contrast agents are increasingly used in endoscopic ultrasound (EUS) for characterization of microvascularization, differential diagnosis of benign and malignant focal lesions, and improving staging and guidance of therapeutic procedures. Although...... initially used as Doppler signal enhancers, second-generation microbubble contrast agents are now used with specific contrast harmonic imaging techniques, which benefit from the highly nonlinear behavior of the microbubbles. Contrast-specific modes based on multi-pulse technology are used to perform...... contrast-enhanced harmonic EUS based on a very low mechanical index (0.08 - 0.12). Quantification techniques based on dynamic contrast-enhanced ultrasound have been recommended for perfusion imaging and monitoring of anti-angiogenic treatment, mainly based on time-intensity curve analysis. Most...

  19. Multi-step contrast sensitivity gauge

    Science.gov (United States)

    Quintana, Enrico C; Thompson, Kyle R; Moore, David G; Heister, Jack D; Poland, Richard W; Ellegood, John P; Hodges, George K; Prindville, James E

    2014-10-14

    An X-ray contrast sensitivity gauge is described herein. The contrast sensitivity gauge comprises a plurality of steps of varying thicknesses. Each step in the gauge includes a plurality of recesses of differing depths, wherein the depths are a function of the thickness of their respective step. An X-ray image of the gauge is analyzed to determine a contrast-to-noise ratio of a detector employed to generate the image.

  20. Contrast settling in cerebral aneurysm angiography

    International Nuclear Information System (INIS)

    Wang Zhijie; Hoffmann, Kenneth R; Guterman, Lee R; Wang Zhou; Rudin, Stephen; Meng Hui

    2005-01-01

    During angiography, blood flow is visualized with a radiopaque contrast agent, which is denser than blood. In complex vasculature, such as cerebral saccular aneurysms, the density difference may produce an appreciable gravity effect, where the contrast material separates from blood and settles along the gravity direction. Although contrast settling has been occasionally reported before, the fluid mechanics behind it have not been explored. Furthermore, the severity of contrast settling in cerebral aneurysms varies significantly from case to case. Therefore, a better understanding of the physical principles behind this phenomenon is needed to evaluate contrast settling in clinical angiography. In this study, flow in two identical groups of sidewall aneurysm models with varying parent-vessel curvature was examined by angiography. Intravascular stents were deployed into one group of the models. To detect contrast settling, we used lateral view angiography. Time-intensity curves were analysed from the angiographic data, and a computational fluid dynamic analysis was conducted. Results showed that contrast settling was strongly related to the local flow dynamics. We used the Froude number, a ratio of flow inertia to gravity force, to characterize the significance of gravity force. An aneurysm with a larger vessel curvature experienced higher flow, which resulted in a larger Froude number and, thus, less gravitational settling. Addition of a stent reduced the aneurysmal flow, thereby increasing the contrast settling. We found that contrast settling resulted in an elevated washout tail in the time-intensity curve. However, this signature is not unique to contrast settling. To determine whether contrast settling is present, a lateral view should be obtained in addition to the anteroposterior (AP) view routinely used clinically so as to rule out contrast settling and hence to enable a valid time-intensity curve analysis of blood flow in the aneurysm

  1. Contrast media on abdominal computed tomography

    International Nuclear Information System (INIS)

    Skalpe, I.O.; Oestensen, H.M.

    1984-01-01

    Abdominal computed tomography was performed in 55 patients before and after intravenous injection of 60 ml of a non-ionic (iohexol) or an ionic (metrizoate) contrast medium. The adverse effects were recorded and a series of measurements of attenuation values before and after the contrast medium injection was performed in the aorta and in hepatic and renal parenchyma. Only minor adverse effects were seen with both contrast media, but iohexol was clearly better tolerated than metrizoate. No difference in the enhancement properties was found between the two contrast media. (orig.)

  2. An Improved Image Contrast Assessment Method

    Directory of Open Access Journals (Sweden)

    Yuanyuan Fan

    2013-07-01

    Full Text Available Contrast is an important factor affecting the image quality. In order to overcome the problems of local band-limited contrast, a novel image contrast assessment method based on the property of HVS is proposed. Firstly, the image by low-pass filter is performed fast wavelet decomposition. Secondly, all levels of band-pass filtered image and its corresponding low-pass filtered image are obtained by processing wavelet coefficients. Thirdly, local band-limited contrast is calculated, and the local band-limited contrast entropy is calculated according to the definition of entropy, Finally, the contrast entropy of image is obtained by averaging the local band-limited contrast entropy weighed using CSF coefficient. The experiment results show that the best contrast image can be accurately identified in the sequence images obtained by adjusting the exposure time and stretching gray respectively, the assessment results accord with human visual characteristics and make up the lack of local band-limited contrast.

  3. Contrast enhanced ultrasound in liver imaging

    International Nuclear Information System (INIS)

    Nielsen, Michael Bachmann; Bang, Nanna

    2004-01-01

    Ultrasound contrast agents were originally introduced to enhance the Doppler signals when detecting vessels with low velocity flow or when imaging conditions were sub-optimal. Contrast agents showed additional properties, it was discovered that a parenchymal enhancement phase in the liver followed the enhancement of the blood pool. Contrast agents have made ultrasound scanning more accurate in detection and characterization of focal hepatic lesions and the sensitivity is now comparable with CT and MRI scanning. Further, analysis of the transit time of contrast agent through the liver seems to give information on possible hepatic involvement, not only from focal lesions but also from diffuse benign parenchymal disease. The first ultrasound contrast agents were easily destroyed by the energy from the sound waves but newer agents have proved to last for longer time and hereby enable real-time scanning and make contrast enhancement suitable for interventional procedures such as biopsies and tissue ablation. Also, in monitoring the effect of tumour treatment contrast agents have been useful. A brief overview is given on some possible applications and on different techniques using ultrasound contrast agents in liver imaging. At present, the use of an ultrasound contrast agent that allows real-time scanning with low mechanical index is to be preferred

  4. Polymeric nanoparticles as OCT contrast agents

    Energy Technology Data Exchange (ETDEWEB)

    Al Rawashdeh, Wa' el [RWTH Aachen University, Experimental Molecular Imaging (Germany); Kray, Stefan [RWTH Aachen University, Institute for Semiconductor Electronics (Germany); Pich, Andrij; Pargen, Sascha; Balaceanu, Andreea [RWTH Aachen University, Interactive Material Research (DWI) (Germany); Lenz, Markus; Spoeler, Felix [RWTH Aachen University, Institute for Semiconductor Electronics (Germany); Kiessling, Fabian, E-mail: fkiessling@ukaachen.de; Lederle, Wiltrud [RWTH Aachen University, Experimental Molecular Imaging (Germany)

    2012-12-15

    In this study, the optical properties of two nano-sized polymer colloids in optical coherence tomography (OCT) were compared in vitro with respect to their potential use as contrast agents. We used two types of particles: compact hydrophobic spherical polystyrene (PS) particles and soft water-swollen nanogel (NG) particles both with grafted hydrophilic shell, both prepared at two different sizes (PS at 300 and 150 nm, NG at 300 and 200 nm). The OCT backscattering signals of the particles in a vessel-mimicking highly scattering agar/TiO{sub 2} phantom were compared on either number of particles or weight percent. Larger particles and higher concentrations produced higher OCT contrast. At each concentration tested, a markedly higher contrast was achieved by PS particles than NG particles. PS particles generated a markedly higher OCT contrast than the phantom at concentrations of at least 1 Multiplication-Sign 10{sup 10} or 0.1 % for PS 300 nm and at least 3 Multiplication-Sign 10{sup 11} particles/mL or 0.4 % for PS 150 nm. The contrast generated by NG 300 nm was above the phantom contrast at concentrations of at least 3 Multiplication-Sign 10{sup 11} particles/mL or 1 %, whereas NG 200 nm only at 4 %. At any given weight percent, the differences in OCT contrast between differently sized particles were much less evident than in the comparison based on particle number. PS 300 nm generated also a good contrast ex vivo on chicken muscle tissue. These results strongly suggest that PS spheres have strong potential as intravascular OCT contrast agent, while NG particles need further contrast enhancer for being used as OCT contrast agent.

  5. Motion contrast using optical coherence tomography

    Science.gov (United States)

    Fingler, Jeffrey Paul

    Diagnosis of ophthalmic diseases like age-related macular degeneration is very important for treatment of the disease as well as the development of future treatments. Optical coherence tomography (OCT) is an optical interference technique which can measure the three-dimensional structural information of the reflecting layers within a sample. In retinal imaging, OCT is used as the primary diagnostic tool for structural abnormalities such as retinal holes and detachments. The contrast within the images of this technique is based upon reflectivity changes from different regions of the retina. This thesis demonstrates the developments of methods used to produce additional contrast to the structural OCT images based on the tiny fluctuations of motion experienced by the mobile scatterers within a sample. Motion contrast was observed for motions smaller than 50 nm in images of a variety of samples. Initial contrast method demonstrations used Brownian motion differences to separate regions of a mobile Intralipid solution from a static agarose gel, chosen in concentration to minimize reflectivity contrast. Zebrafish embryos in the range of 3-4 days post fertilization were imaged using several motion contrast methods to determine the capabilities of identifying regions of vascular flow. Vasculature identification was demonstrated in zebrafish for blood vessels of all orientations as small as 10 microns in diameter. Mouse retinal imaging utilized the same motion contrast methods to determine the contrast capabilities for motions associated with vasculature within the retina. Improved contrast imaging techniques demonstrated comparable images to fluorescein angiography, the gold standard of retinal vascular imaging. Future studies can improve the demonstrated contrast analysis techniques and apply them towards human retinal motion contrast imaging for ophthalmic diagnostic purposes.

  6. CHANGE DETECTION VIA SELECTIVE GUIDED CONTRASTING FILTERS

    Directory of Open Access Journals (Sweden)

    Y. V. Vizilter

    2017-05-01

    Full Text Available Change detection scheme based on guided contrasting was previously proposed. Guided contrasting filter takes two images (test and sample as input and forms the output as filtered version of test image. Such filter preserves the similar details and smooths the non-similar details of test image with respect to sample image. Due to this the difference between test image and its filtered version (difference map could be a basis for robust change detection. Guided contrasting is performed in two steps: at the first step some smoothing operator (SO is applied for elimination of test image details; at the second step all matched details are restored with local contrast proportional to the value of some local similarity coefficient (LSC. The guided contrasting filter was proposed based on local average smoothing as SO and local linear correlation as LSC. In this paper we propose and implement new set of selective guided contrasting filters based on different combinations of various SO and thresholded LSC. Linear average and Gaussian smoothing, nonlinear median filtering, morphological opening and closing are considered as SO. Local linear correlation coefficient, morphological correlation coefficient (MCC, mutual information, mean square MCC and geometrical correlation coefficients are applied as LSC. Thresholding of LSC allows operating with non-normalized LSC and enhancing the selective properties of guided contrasting filters: details are either totally recovered or not recovered at all after the smoothing. These different guided contrasting filters are tested as a part of previously proposed change detection pipeline, which contains following stages: guided contrasting filtering on image pyramid, calculation of difference map, binarization, extraction of change proposals and testing change proposals using local MCC. Experiments on real and simulated image bases demonstrate the applicability of all proposed selective guided contrasting filters. All

  7. Comparative evaluation of positive contrast and double contrast gastrography in dogs

    International Nuclear Information System (INIS)

    Dileepkumar, K.M.; Rajankutty, K.; Sarada, Amma T.; Devanand, C.B.; Vijayan, N.

    2012-01-01

    A contrast radiography of stomach with oral barium sulphate suspension 25% (5 mL/kg b.wt positive contrast) and double contrast with oral barium sulphate 25% (3 mL/kg b.wt) followed by air (2 to 10 mL/kg b.wt, negative contrast) was done on six dogs to study the affections of stomach. Contrast radiography using barium sulphate alone was found satisfactory to identify most of the lesions of the stomach. Double contrast radiography using barium sulphate and air, required sedation to control the animals for proper administration. For the diagnosis of mucosal lesions, double contrast radiography was better than barium sulphate alone. Key words: Barium, Contrast radiography, Dog, Double contrast, Stomach

  8. Contrasts agents in magnetic resonance imaging

    International Nuclear Information System (INIS)

    Bonnet, P.A.; Fernandez, J.P.; Milhavet, J.C.; Chapat, J.P.; Almes, C.; Bruel, J.M.; Rouanet, J.P.; Lamarque, J.L.

    1984-01-01

    Changing different parameters involved in imaging procedures, paramagnetic substances provide contrast enhancement in MRI. Contrast agents presently studied in animals and clinical trials, are either salts or complexes of mineral ions either nitroxide stable free radicals. Their development should extend the possibilities of tissular characterization and fonctional or metabolic evaluation of the MRI [fr

  9. Parametric based morphological transformation for contrast ...

    Indian Academy of Sciences (India)

    for contrast enhancement of color images in poor-lighting ... high and low mean brightness value, there is a significant change in the view of the enhanced ... The two most fundamental morphological operations dilation and erosion are defined by ..... Menotti David 2007 Multi-histogram equalization methods for contrast ...

  10. Discrimination of Arabic Contrasts by American Learners

    Science.gov (United States)

    Al Mahmoud, Mahmoud S.

    2013-01-01

    This article reports on second language perception of non-native contrasts. The study specifically tests the perceptual assimilation model (PAM) by examining American learners' ability to discriminate Arabic contrasts. Twenty two native American speakers enrolled in a university level Arabic language program took part in a forced choice AXB…

  11. Comparison and Contrast in Perceptual Categorization

    Science.gov (United States)

    Hampton, James A.; Estes, Zachary; Simmons, Claire L.

    2005-01-01

    People categorized pairs of perceptual stimuli that varied in both category membership and pairwise similarity. Experiments 1 and 2 showed categorization of 1 color of a pair to be reliably contrasted from that of the other. This similarity-based contrast effect occurred only when the context stimulus was relevant for the categorization of the…

  12. Contrast sensitivity abnormalities in deaf individuals

    Directory of Open Access Journals (Sweden)

    Masoud Khorrami-Nejad

    2018-01-01

    Conclusion: Hearing impaired boys are at a greater risk for contrast sensitivity abnormalities than boys with normal hearing. The larger frequency of contrast sensitivity abnormalities in high spatial frequencies than in other frequencies may demonstrate greater defects in the central visual system compared with the periphery in individuals with hearing loss.

  13. Influence of radiographic contrast media on phagocytosis

    International Nuclear Information System (INIS)

    Rasmussen, F.; Georgsen, J.; Grunnet, N.; Aalborg Sygehus

    1988-01-01

    To evaluate the influence of radiographic contrast media (CM) on human polymorphonuclear leucocytes (PML), the ability of these cells to ingest latex particles after in vitro exposure to five different radiographic contrast media was investigated. All CM inhibited the phagocytic properties of PML. The inhibition was dose dependent. The inhibitory effect was partly due to hyperosmolality but CM specific inhibition was also evident. (orig.)

  14. Modeling of ultrasound propagation through contrast agents

    NARCIS (Netherlands)

    Grootens, J.J.F.A.H.; Mischi, M.; Böhmer, M.; Korsten, H.; Aarts, R.M.; Vander Sloten, Jos; Verdonck, Pascal; Nyssen, Marc

    2008-01-01

    In the past years many advances have been made in the detection of ultrasound contrast agents (UCA) by exploiting their nonlinear behavior. However, little attention has been paid to the nonlinear distortion of ultrasound (US) waves propagating through contrast media. The aim of this study is to

  15. Adverse reactions to intravascularly administered contrast media

    International Nuclear Information System (INIS)

    Olin, T.

    1986-01-01

    A hypothesis is formulated about the mechanisms causing adverse reactions to contrast media. Contrast media act in two ways. They stimulate the mast cells to release histamine and leukotrienes, and they inhibit the enzymes which otherwise degrade leukotrienes. Thus individuals, especially those with a history of allergy, are easily exposed to undue amounts of leukotrienes and these are responsible for the adverse reactions. (orig.)

  16. Lesion Contrast Enhancement in Medical Ultrasound Imaging

    DEFF Research Database (Denmark)

    Stetson, Paul F.; Sommer, F.G.; Macovski, A.

    1997-01-01

    Methods for improving the contrast-to-noise ratio (CNR) of low-contrast lesions in medical ultrasound imaging are described. Differences in the frequency spectra and amplitude distributions of the lesion and its surroundings can be used to increase the CNR of the lesion relative to the background...

  17. Contrast configuration influences grouping in apparent motion.

    Science.gov (United States)

    Ma-Wyatt, Anna; Clifford, Colin W G; Wenderoth, Peter

    2005-01-01

    We investigated whether the same principles that influence grouping in static displays also influence grouping in apparent motion. Using the Ternus display, we found that the proportion of group motion reports was influenced by changes in contrast configuration. Subjects made judgments of completion of these same configurations in a static display. Generally, contrast configurations that induced a high proportion of group motion responses were judged as more 'complete' in static displays. Using a stereo display, we then tested whether stereo information and T-junction information were critical for this increase in group motion. Perceived grouping was consistently higher for same contrast polarity configurations than for opposite contrast polarity configurations, regardless of the presence of stereo information or explicit T-junctions. Thus, while grouping in static and moving displays showed a similar dependence on contrast configuration, motion grouping showed little dependence on stereo or T-junction information.

  18. Contrast Agent in Magnetic Resonance Imaging

    DEFF Research Database (Denmark)

    Vu-Quang, Hieu

    2015-01-01

    Nanoparticles have been employed as contrast agent in magnetic resonance imaging (MRI) in order to improve sensitivity and accuracy in diagnosis. In addition, these contrast agents are potentially combined with other therapeutic compounds or near infrared bio-imaging (NIR) fluorophores to obtain...... theranostic or dual imaging purposes, respectively. There were two main types of MRI contrast agent that were synthesized during this PhD project including fluorine containing nanoparticles and magnetic nanoparticles. In regard of fluorine containing nanoparticles, there were two types contrast agent...... cancer cells for cancer diagnosis in MRI. F127-Folate coated SPION were stable in various types of suspension medium for over six months. They could specifically target folate receptor of cancer cells in vitro and in vivo thus enhancing the contrast in MRI T2/T2* weighted images. These are preliminary...

  19. Application of phase contrast imaging to mammography

    International Nuclear Information System (INIS)

    Tohyama, Keiko; Yamada, Katsuhiko; Katafuchi, Tetsuro; Matsuo, Satoru; Morishita, Junji

    2005-01-01

    Phase contrast images were obtained experimentally by using a customized mammography unit with a nominal focal spot size of 100 μm and variable source-to-image distances of up to 1.5 m. The purpose of this study was to examine the applicability and potential usefulness of phase contrast imaging for mammography. A mammography phantom (ACR156 RMI phantom) was imaged, and its visibility was examined. The optical density of the phantom images was adjusted to approximately 1.3 for both the contact and phase contrast images. Forty-one observers (18 medical doctors and 23 radiological technologists) participated in visual evaluation of the images. Results showed that, in comparison with the images of contact mammography, the phantom images of phase contrast imaging demonstrated statistically significantly superior visibility for fibers, clustered micro-calcifications, and masses. Therefore, phase contrast imaging obtained by using the customized mammography unit would be useful for improving diagnostic accuracy in mammography. (author)

  20. Choice of intravenous contrast material for CT

    International Nuclear Information System (INIS)

    Cohen, M.D.; Herman, E.; Herron, D.; White, S.T.; Smith, J.A.; Cory, D.A.

    1989-01-01

    For CT, minor side effects (e.g., nausea, vomiting, pain) following intravenous administration of contrast medium may degrade image quality by causing patient motion or by delaying scanning. The objective of this study was to see if nonionic contrast agents offer advantages in reducing the incidence of such side effects. One hundred five pediatric patients randomly received iohexol (Omnipaque), Iopamidol (Isovue), or diatrizoate sodium (Hypaque). Contrast medium was given in doses of 2 mL/kg body weight (300 mg of iodine per milliliter). The results are presented in the paper

  1. Anaphylactoid reactions after iodinated contrast media

    International Nuclear Information System (INIS)

    Strejcek, J.; Sehr, A.

    1987-01-01

    A survey is presented of data published in the literature on the incidence of undesirable and especially anaphylactoid reactions to intravenously administered iodinated contrast media used in radiodiagnosis, this with regard to age, sex, allergy in the patient's history, previously administered contrast media, possible previous reaction. A detailed description is presented of the assumed mechanisms of these reactions. There does not exist any reliable premedication. It is always indispensable to consider the indications of the examination using iodinated contrast agents and the possibilities of immediate and qualified resuscitation. (author). 2 tabs., 36 refs

  2. Contrast data mining concepts, algorithms, and applications

    CERN Document Server

    Dong, Guozhu

    2012-01-01

    A Fruitful Field for Researching Data Mining Methodology and for Solving Real-Life Problems Contrast Data Mining: Concepts, Algorithms, and Applications collects recent results from this specialized area of data mining that have previously been scattered in the literature, making them more accessible to researchers and developers in data mining and other fields. The book not only presents concepts and techniques for contrast data mining, but also explores the use of contrast mining to solve challenging problems in various scientific, medical, and business domains. Learn from Real Case Studies

  3. The 'humble' bubble: Contrast-enhanced ultrasound

    International Nuclear Information System (INIS)

    Marshall, Gill; Sykes, Anne; Berry, Jonathan; Jonker, Leon

    2011-01-01

    The use of contrast-enhanced ultrasound (CEUS) is increasing within the field of medical imaging. Ultrasonic contrast agent (UCA) contain gas microbubbles similar in size to red corpuscles which provide highly reflective interfaces, enabling dynamic demonstration of echogenic streams of the contrast within the anatomical area of interest on real-time grey scale ultrasound. Longevity of the microbubbles has been improved by changing their composition. The application of CEUS in the UK continues to grow, bringing it into territories historically occupied by computerised tomography (CT) scanning and magnetic resonance imaging (MRI). Hence, the role of CEUS may be of interest to all diagnostic imaging practitioners. Here we summarise the mode of action and use of CEUS, and its role within a range of applications. The potential risks of CEUS are compared to other contrast-enhanced imaging techniques. The benefits of CEUS and its implications for diagnostic imaging practice are also covered.

  4. Contrast effects of a gadolinium filter

    International Nuclear Information System (INIS)

    Burgess, A.E.

    1981-01-01

    Several authors have suggested using heavy metal filters with K edges in the diagnostic energy range to reduce the width of the x-ray spectrum and hence reduce patient radiation exposure. This spectral narrowing also increases subject contrast and permits an increase in tube potential. Results of contrast measurements are presented for a 250 mu gadolinium filter. It was found that aluminum filter contrast could be matched by using 8 to 10 kVp higher potential with the gadolinium filter. Similar results were found for calcium tungstate and rare-earth screens. Measurements were also done to determine skin exposure and mAs ratios for both constant contrast and constant kVp technique conversion methods. A simple theory with one adjustable parameter gives a reasonable fit to the experimental results

  5. Incompatibility of Contrast Medium and Trisodium Citrate

    International Nuclear Information System (INIS)

    Delcour, Christian; Bruninx, Guy

    2013-01-01

    To test the compatibility of trisodium citrate, a catheter lock solution, with iodinated contrast medium. Iohexol, iobitridol, iodixanol, ioxaglate, ioxithalamate, iomeprol, and iopromide were tested. In all tests, 2 ml of contrast medium were mixed with 2 ml of trisodium citrate solution. Iodixanol and ioxaglate provoked a highly viscous gluelike precipitation when mixed with trisodium citrate. A brief transient precipitate was observed with iohexol, iomeprol, and ioxithalamate. Permanent precipitation occurred with iobitridol and iopromide. One must be aware of the potential for precipitation when contrast medium is mixed with trisodium citrate solution. Before trisodium citrate solution is injected, the catheter should be thoroughly flushed with saline if a contrast medium has previously been injected through it.

  6. Manganese(II) chelate contrast media

    International Nuclear Information System (INIS)

    Rocklage, S.M.; Quay, S.C.

    1994-01-01

    New chelate forming compounds for use as contrast media in NMR imaging are described. Especially mentioned are manganese(II) ion chelates of N,N' dipyridoxaldiamine, N,N' diacetic acid, and salts and esters thereof. 1 fig

  7. Application of Contrast Echocardiography in Invasive Cardiology

    Directory of Open Access Journals (Sweden)

    Mustafa Bulut

    2010-12-01

    Full Text Available Contrast echocardiography by rendering better imaging of the borders of cardiac chambers is a useful tool for evaluating cardiac function, mass, myocardial vascularization, microvascular structure (small vessel vasculature and viability. Contrast was first started to be used for patients with suboptimal image quality. It can be used in detecting defects in myocardial blood supply in patients with chest pain and determining the success of interventionalprocedures. It can also be of help in demonstrating myocardial viability after reperfusion treatment in patients who had myocardial infarction. It is expected to be used more widely in invasive cardiology for decision making, guiding and determining the success of the procedures. Advances in imaging techniques , development of contrast materials for evaluation of left system, contrast echocardiography may become a routine clinical practice.

  8. Safety of MR liver specific contrast media

    Energy Technology Data Exchange (ETDEWEB)

    Bellin, Marie-France [Hopital Paul Brousse, Universite Paris 11, Villejuif Cedex (France); Webb, Judith A.W. [St. Bartholomew' s Hospital, Department of Diagnostic Imaging, London (United Kingdom); Molen, Aart J. van der [Leiden University Medical Centre, Department of Radiology, Leiden (Netherlands); Thomsen, Henrik S. [Copenhagen University Hospital at Herlev, Department of Diagnostic Radiology 54E2, Herlev (Denmark); Morcos, Sameh K. [Northern General Hospital, Sheffield Teaching Hospitals NHS Trust, Department of Diagnostic Imaging, Sheffield (United Kingdom)

    2005-08-01

    Over the past few years a number of magnetic resonance (MR) liver specific contrast agents have been introduced. In this report the safety issues of these agents are addressed. A literature search was carried out. Based on the available information, simple guidelines on the safety issue of liver specific contrast agents have been produced by the Contrast Media Safety Committee of the European Society of Urogenital Radiology. The report and guidelines were discussed at the 11th European Symposium on Urogenital Radiology in Santiago de Compostela. Liver specific contrast agents appear in general to be safe and well tolerated. However, the incidence of adverse reactions with iron oxides and the intravenous manganese based agent seems to be slightly higher than with gadolinium based agents. However, no safety information from comparative clinical trials has been published. Guidelines on the safety aspects are presented. (orig.)

  9. Safety of MR liver specific contrast media

    International Nuclear Information System (INIS)

    Bellin, Marie-France; Webb, Judith A.W.; Molen, Aart J. van der; Thomsen, Henrik S.; Morcos, Sameh K.

    2005-01-01

    Over the past few years a number of magnetic resonance (MR) liver specific contrast agents have been introduced. In this report the safety issues of these agents are addressed. A literature search was carried out. Based on the available information, simple guidelines on the safety issue of liver specific contrast agents have been produced by the Contrast Media Safety Committee of the European Society of Urogenital Radiology. The report and guidelines were discussed at the 11th European Symposium on Urogenital Radiology in Santiago de Compostela. Liver specific contrast agents appear in general to be safe and well tolerated. However, the incidence of adverse reactions with iron oxides and the intravenous manganese based agent seems to be slightly higher than with gadolinium based agents. However, no safety information from comparative clinical trials has been published. Guidelines on the safety aspects are presented. (orig.)

  10. Contrast medium-induced nephropathy: the pathophysiology

    DEFF Research Database (Denmark)

    Persson, P B; Tepel, Martin

    2006-01-01

    A widespread, rather general, definition of contrast-induced nephropathy (CIN) is an impairment in renal function occurring within 3 days following the intravascular administration of contrast media (CM) and the absence of an alternative aetiology. In spite of the vast clinical importance of CIN...... haemodynamics, regional hypoxia, auto-, and paracrine factors (adenosine, endothelin, reactive oxygen species) to direct cytotoxic effects. Although these potential mediators of CIN will be discussed separately, several factors may act in concert to perturb kidney function after exposure to contrast media. From...... the current knowledge of the mechanisms causing CIN, it is not possible to recommend a certain class of contrast media, except to avoid large doses of CM of the first generation. From a pathophysiological perspective, volume expansion is effective in avoiding CIN, since water permeability of the collecting...

  11. Basic characteristics of simultaneous color contrast revisited.

    Science.gov (United States)

    Ekroll, Vebjørn; Faul, Franz

    2012-10-01

    In this article, we present evidence supporting the hypothesis that the local mechanism of simultaneous color contrast is the same as the mechanism responsible for the crispening effect and the gamut expansion effect. A theoretically important corollary of this hypothesis is that the basic characteristics of simultaneous contrast are at odds with traditional laws. First, this hypothesis implies that the direction of the simultaneous contrast effect in color space is given by the vector from surround to target and not--as traditionally assumed--by the hue complementary to that of the surround. Second, it implies that the size of the simultaneous contrast effect depends on the difference between the target and surround colors in a way that challenges Kirschmann's fourth law. The widespread belief in the traditional laws, we argue, is due to the confounding influence of temporal adaptation.

  12. Are the nonionic contrast media really safe

    International Nuclear Information System (INIS)

    Seyferth, W.; Zeitler, E.

    1987-01-01

    The authors used a wide variety of ionic and nonionic contrast media in 11,203 patient examinations (angiography, phlebography, CT). Data have been collected in prospective studies since 1982. The rate of mild side effects was reduced by a factor of 2 to 3 for all examinations when nonionic contrast media were used. Angiography may not be suitable for evaluating the safety of contrast media. Because of statistical requirements, the influence of nonionic media on the rate of severe side effects will not be known for some time. The side effects of nonionic contrast media were somewhat delayed, and differed from times reported in the literature: 29% of wide effects were noticed within 15 minutes and 71% between 25 minutes to 72 hours after the study. The final results of the study will have numerous consequences for patient treatment protocols

  13. Death following intravascular administration of contrast media

    International Nuclear Information System (INIS)

    Shehadi, W.H.

    1985-01-01

    Adverse reactions to intravascularly administered contrast media preceding death and the autopsy findings in 44 patients are presented. There is a wide scatter of the age distribution of fatal reactions. The highest incidence is in the 50-70 year age group. Similar observations were obtained from the 405 deaths due to contrast media reported to the Food and Drug Administration of the United States. In the same age group the number of reactions is highest, likewise the autopsy findings. The predominant autopsy findings are pulmonary edema, congestion and hemorrhage; arteriosclerosis, both general and coronary. In the younger age group the autopsy findings are limited mostly to the respiratory tract. Fatal reactions to contrast media occur often without warning and most deaths occur within 15 min to 6 hours. Reactions to contrast media occur without relation to sex or age. (orig.)

  14. Contrast data mining: concepts, algorithms, and applications

    National Research Council Canada - National Science Library

    Dong, Guozhu; Bailey, James

    2013-01-01

    .... Contrasting involves the comparison of one dataset against another. The datasets may represent data of different time periods, spatial locations, or classes, or they may represent data satisfying different conditions...

  15. Instrumentation for contrast echocardiography: technology and techniques.

    Science.gov (United States)

    Kaul, Sanjiv

    2002-11-18

    Contrast echocardiography is the only clinical imaging technique in which the imaging modality (ultrasound) can cause a change in the contrast agent (microbubbles). The change in the contrast agent can range from small oscillations of the microbubbles at a low mechanical index to their disruption at a high mechanical index. The specific mechanical index required to produce these various effects may be different for each contrast agent, depending on the bubble dimension as well as shell and gas characteristics. These alterations in bubbles result in changes in ultrasound backscatter that are specific for the bubbles themselves, rather than for tissue, and are therefore exploited for imaging their presence in tissue. These signal-processing techniques have resulted in an increased signal-to-noise ratio from bubbles vis-à-vis the tissue and have made online assessment of myocardial perfusion possible.

  16. Parametric based morphological transformation for contrast ...

    Indian Academy of Sciences (India)

    rithm is illustrated through the processing of gray scale images and color images with different backgrounds. Keywords. Histogram equalization; image background; mathematical morphology; Weber's ratio. 1. Introduction. Contrast enhancement has a crucial role in image processing applications, such as digital.

  17. Contrast-induced nephropathy after computed tomography

    Directory of Open Access Journals (Sweden)

    Luciano da Silva Selistre

    2015-03-01

    Full Text Available Introduction: Contrast induced nephropathy is the third most prevalent preventable cause of acute kidney injury in hospitalized patients. It defined as an absolute increase in serum creatinine ≥ 0.5 mg/dL and relative ≥ 25% increase. Objective: We studied the risk factors to intravenous injection contrast nephropathy after computed tomography. Methods: We studied 400 patients prospectively. Results: The incidence of contrast induced nephropathy, with an absolute or a relative increase were 4.0% and 13.9%, respectively. Diabetes and cardiac failure were independent risk factors for CIN a relative increase de serum creatinine (O.R.: 3.5 [95% CI: 1.92-6.36], p < 0.01, 2.61 [95% CI: 1.14-6.03%], p < 0.05, respectively. Conclusions: We showed association between uses of intravenous injection contrast after computed tomography with acute injury renal, notably with diabetes and heart failure.

  18. The Future of Contrast-Enhanced Mammography.

    Science.gov (United States)

    Covington, Matthew F; Pizzitola, Victor J; Lorans, Roxanne; Pockaj, Barbara A; Northfelt, Donald W; Appleton, Catherine M; Patel, Bhavika K

    2018-02-01

    The purpose of this article is to discuss facilitators of and barriers to future implementation of contrast-enhanced mammography (CEM) in the United States. CEM provides low-energy 2D mammographic images analogous to digital mammography and contrast-enhanced recombined images that allow assessment of neovascularity similar to that offered by MRI. The utilization of CEM in the United States is currently low but could increase rapidly given the many potential indications for its clinical use.

  19. Contrast agent incompatibility with intravascular medications

    International Nuclear Information System (INIS)

    Irving, H.D.; Burbridge, B.E.

    1988-01-01

    In vitro and in vivo precipitation of iodinated contrast agents with commonly used medications have been reported. The intent of this in vitro study is to verify these reports and investigate other medications not previously tested. Contrast agents and medications were analyzed with a light spectrometer and observed for visible precipitates for up to 120 minutes. Previously reported incompatibilities were verified, and several new incompatibilities were discovered

  20. Contrast induced hyperthyroidism due to iodine excess

    OpenAIRE

    Mushtaq, Usman; Price, Timothy; Laddipeerla, Narsing; Townsend, Amanda; Broadbridge, Vy

    2009-01-01

    Iodine induced hyperthyroidism is a thyrotoxic condition caused by exposure to excessive iodine. Historically this type of hyperthyroidism has been described in areas of iodine deficiency. With advances in medicine, iodine induced hyperthyroidism has been observed following the use of drugs containing iodine—for example, amiodarone, and contrast agents used in radiological imaging. In elderly patients it is frequently difficult to diagnose and control contrast related hyperthyroidism, as most...

  1. Contrast-induced encephalopathy following cardiac catheterization.

    Science.gov (United States)

    Spina, Roberto; Simon, Neil; Markus, Romesh; Muller, David Wm; Kathir, Krishna

    2017-08-01

    To describe the epidemiology, pathophysiology, clinical presentation, and management of contrast-induced encephalopathy (CIE) following cardiac catheterization. CIE is an acute, reversible neurological disturbance directly attributable to the intra-arterial administration of iodinated contrast medium. The PubMed database was searched and all cases in the literature were retrieved and reviewed. 52 reports of CIE following cardiac catheterization were found. Encephalopathy, motor and sensory disturbances, vision disturbance, opthalmoplegia, aphasia, and seizures have been reported. Transient cortical blindness is the most commonly reported neurological syndrome, occurring in approximately 50% of cases. The putative mechanism involves disruption of the blood brain barrier and direct neuronal injury. Contrast-induced transient vasoconstriction has also been implicated. Symptoms typically appear within minutes to hours of contrast administration and resolve entirely within 24-48 hr. Risk factors may include hypertension, diabetes mellitus, renal impairment, the administration of large volumes of iodinated contrast, percutaneous coronary intervention or selective angiography of internal mammary grafts, and previous adverse reaction to iodinated contrast. Characteristic findings on cerebral imaging include cortical and sub-cortical contrast enhancement on computed tomography (CT). Imaging findings in CIE may mimic subarachnoid hemorrhage or cerebral ischemia; the Hounsfield scale on CT and the apparent diffusion coefficient on magnetic resonance imaging (MRI) are useful imaging tools in distinguishing these entities. In some cases, brain imaging is normal. Prognosis is excellent with supportive management alone. CIE tends to recur, although re-challenge with iodinated contrast without adverse effects has been documented. CIE is an important clinical entity to consider in the differential diagnosis of stroke following cardiac catheterization. Given that prognosis is

  2. Radiculography with reduced amounts of contrast medium

    International Nuclear Information System (INIS)

    Signorini, E.; Caputo, N.; Chiurulla, C.; Ciorba, E.; Pelliccioli, G.P.; Cianciulli, E.

    1984-01-01

    Because of the frequency and seriousness of side effects observed after radiculography, due to, among the other things, the amount of contrast medium, the authors describe a method that gives diagnostically satisfactory results using a low dose of contrast and a tangent-beam technique. Among 106 patients undergoing radiculography with a tangent-beam technique and Iopamidol, only 4 developed mild side effects, namely headache in three cases and headache with nausea in one. (Author)

  3. Contrast adaptation in the Limulus lateral eye

    OpenAIRE

    Valtcheva, Tchoudomira M.; Passaglia, Christopher L.

    2015-01-01

    Luminance and contrast adaptation are neuronal mechanisms employed by the visual system to adjust our sensitivity to light. They are mediated by an assortment of cellular and network processes distributed across the retina and visual cortex. Both have been demonstrated in the eyes of many vertebrates, but only luminance adaptation has been shown in invertebrate eyes to date. Since the computational benefits of contrast adaptation should apply to all visual systems, we investigated whether thi...

  4. Are ionic CAT contrast media still justifiable

    International Nuclear Information System (INIS)

    Witt, H.; Trempenau, B.; Dietz, G.

    1984-01-01

    The authors' clinical results revealed no statistically significant differences of tolerance between the two X-ray contrast media 'Ioxitalamat' and 'Ioglicinat'. Side-effects were found in 4.3% of the cases for both contrast media, a rate which is slightly below the one for urography. However, it must not be overlooked that patients exposed to certain risk faktors such as e.g. relative contraindications were as far as possible excluded from the study. (orig./WU) [de

  5. Microbubbles as contrast agent for in-line x-ray phase-contrast imaging

    International Nuclear Information System (INIS)

    Xi Yan; Zhao Jun; Tang Rongbiao; Wang Yujie

    2011-01-01

    In the present study, we investigated the potential of gas-filled microbubbles as contrast agents for in-line x-ray phase-contrast imaging (PCI) in biomedical applications. When imaging parameters are optimized, the microbubbles function as microlenses that focus the incoming x-rays to form bright spots, which can significantly enhance the image contrast. Since microbubbles have been shown to be safe contrast agents in clinical ultrasonography, this contrast-enhancement procedure for PCI may have promising utility in biomedical applications, especially when the dose of radiation is a serious concern. In this study, we performed both numerical simulations and ex vivo experiments to investigate the formation of the contrast and the effectiveness of microbubbles as contrast agents in PCI.

  6. Assessment of left ventricular volumes by magnetic resonance in comparison with radionuclide angiography, contrast angiography and echocardiography

    DEFF Research Database (Denmark)

    Møgelvang, J; Stokholm, K H; Saunamäki, K

    1992-01-01

    The present study shows that for assessment of LVEF, MRI and the standard methods seem to provide information of similar value. For absolute volume measurements, MRI and RNA are superior to single plane angiography and 2 DE using the modified Simpson-rule. The time consuming transversal MRI method...... quality, which is crucial especially in dilated ventricles containing stagnant or slowly moving blood....

  7. Contrast adaptation in the Limulus lateral eye.

    Science.gov (United States)

    Valtcheva, Tchoudomira M; Passaglia, Christopher L

    2015-12-01

    Luminance and contrast adaptation are neuronal mechanisms employed by the visual system to adjust our sensitivity to light. They are mediated by an assortment of cellular and network processes distributed across the retina and visual cortex. Both have been demonstrated in the eyes of many vertebrates, but only luminance adaptation has been shown in invertebrate eyes to date. Since the computational benefits of contrast adaptation should apply to all visual systems, we investigated whether this mechanism operates in horseshoe crab eyes, one of the best-understood neural networks in the animal kingdom. The spike trains of optic nerve fibers were recorded in response to light stimuli modulated randomly in time and delivered to single ommatidia or the whole eye. We found that the retina adapts to both the mean luminance and contrast of a white-noise stimulus, that luminance- and contrast-adaptive processes are largely independent, and that they originate within an ommatidium. Network interactions are not involved. A published computer model that simulates existing knowledge of the horseshoe crab eye did not show contrast adaptation, suggesting that a heretofore unknown mechanism may underlie the phenomenon. This mechanism does not appear to reside in photoreceptors because white-noise analysis of electroretinogram recordings did not show contrast adaptation. The likely site of origin is therefore the spike discharge mechanism of optic nerve fibers. The finding of contrast adaption in a retinal network as simple as the horseshoe crab eye underscores the broader importance of this image processing strategy to vision. Copyright © 2015 the American Physiological Society.

  8. Clinical evaluation of contrast-enhanced digital mammography and contrast enhanced tomosynthesis--Comparison to contrast-enhanced breast MRI.

    Science.gov (United States)

    Chou, Chen-Pin; Lewin, John M; Chiang, Chia-Ling; Hung, Bao-Hui; Yang, Tsung-Lung; Huang, Jer-Shyung; Liao, Jia-Bin; Pan, Huay-Ben

    2015-12-01

    To compare the diagnostic accuracy of contrast-enhanced digital mammography (CEDM) and contrast-enhanced tomosynthesis (CET) to dynamic contrast enhanced breast MRI (DCE-MRI) using a multireader-multicase study. Institutional review board approval and informed consents were obtained. Total 185 patients (mean age 51.3) with BI-RADS 4 or 5 lesions were evaluated before biopsy with mammography, tomosynthesis, CEDM, CET and DCE-MRI. Mediolateral-oblique and cranio-caudal views of the target breast CEDM and CET were acquired at 2 and 4 min after contrast agent injection. A mediolateral-oblique view of the non-target breast was taken at 6 min. Each lesion was scored with forced BI-RADS categories by three readers. Each reader interpreted lesions in the following order: mammography, tomosynthesis, CEDM, CET, and DCE-MRI during a single reading session. Histology showed 81 cancers and 144 benign lesions in the study. Of the 81 malignant lesions, 44% (36/81) were invasive and 56% (45/81) were non-invasive. Areas under the ROC curve, averaged for the 3 readers, were as follows: 0.897 for DCE-MRI, 0.892 for CET, 0.878 for CEDM, 0.784 for tomosynthesis and 0.740 for mammography. Significant differences in AUC were found between the group of contrast enhanced modalities (CEDM, CET, DCE-MRI) and the unenhanced modalities (all p0.05). CET and CEDM may be considered as an alternative modality to MRI for following up women with abnormal mammography. All three contrast modalities were superior in accuracy to conventional digital mammography with or without tomosynthesis. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  9. Hepatobiliary contrast agents for contrast-enhanced MRI of the liver: properties, clinical development and applications

    International Nuclear Information System (INIS)

    Reimer, Peter; Schneider, Guenter; Schima, Wolfgang

    2004-01-01

    Hepatobiliary contrast agents with uptake into hepatocytes followed by variable biliary excretion represent a unique class of cell-specific MR contrast agents. Two hepatobiliary contrast agents, mangafodipir trisodium and gadobenate dimeglumine, are already clinically approved. A third hepatobiliary contrast agent, Gd-EOB-DTPA, is under consideration. The purpose of this review is to provide an overview on the properties, clinical development and application of these three hepatobiliary contrast agents. Bolus injectable paramagnetic hepatobiliary contrast agents combine established features of extracellular agents with the advantages of hepatocyte specificity. The detection and characterisation of focal liver disease appears to be improved compared to unenhanced MRI, MRI with unspecific contrast agents and contrast-enhanced CT. To decrease the total time spent by a patient in the MR scanner, it is advisable to administer the agent immediately after acquisition of unenhanced T1-w MRI. After infusion or bolus injection (with dynamic FS-T1-w 2D or 3D GRE) of the contrast agent, moderately and heavily T2w images are acquired. Post-contrast T1-w MRI is started upon completion of T2-w MRI for mangafodipir trisodium and Gd-EOB-DTPA as early as 20 min following injection, while gadobenate dimeglumine scans are obtained >60 min following injection. Post-contrast acquisition techniques with near isotropic 3D pulse sequences with fat saturation parallel the technical progress made by MSCT combined with an unparalleled improvement in tumour-liver contrast. The individual decision that hepatobiliary contrast agent one uses is partly based on personal preferences. No comparative studies have been conducted comparing the advantages or disadvantages of all three agents directly against each other. (orig.)

  10. Field strength and dose dependence of contrast enhancement by gadolinium-based MR contrast agents

    International Nuclear Information System (INIS)

    Rinck, P.A.; Muller, R.N.

    1999-01-01

    The relaxivities r 1 and r 2 of magnetic resonance contrast agents and the T 1 relaxation time values of tissues are strongly field dependent. We present quantitative data and simulations of different gadolinium-based extracellular fluid contrast agents and the modulation of their contrast enhancement by the magnetic field to be able to answer the following questions: How are the dose and field dependences of their contrast enhancement? Is there an interrelationship between dose and field dependence? Should one increase or decrease doses at specific fields? Nuclear magnetic relaxation dispersion data were acquired for the following contrast agents: gadopentetate dimeglumine, gadoterate meglumine, gadodiamide injection, and gadoteridol injection, as well as for several normal and pathological human tissue samples. The magnetic field range stretched from 0.0002 to 4.7 T, including the entire clinical imaging range. The data acquired were then fitted with the appropriate theoretical models. The combination of the diamagnetic relaxation rates (R 1 = 1/T 1 and R 2 = 1/T 2 ) of tissues with the respective paramagnetic contributions of the contrast agents allowed the prediction of image contrast at any magnetic field. The results revealed a nearly identical field and dose-dependent increase of contrast enhancement induced by these contrast agents within a certain dose range. The target tissue concentration (TTC) was an important though nonlinear factor for enhancement. The currently recommended dose of 0.1 mmol/kg body weight seems to be a compromise close to the lower limits of diagnostically sufficient contrast enhancement for clinical imaging at all field strengths. At low field contrast enhancement might be insufficient. Adjustment of dose or concentration, or a new class of contrast agents with optimized relaxivity, would be a valuable contribution to a better diagnostic yield of contrast enhancement at all fields. (orig.)

  11. Morphological rational operator for contrast enhancement.

    Science.gov (United States)

    Peregrina-Barreto, Hayde; Herrera-Navarro, Ana M; Morales-Hernández, Luis A; Terol-Villalobos, Iván R

    2011-03-01

    Contrast enhancement is an important task in image processing that is commonly used as a preprocessing step to improve the images for other tasks such as segmentation. However, some methods for contrast improvement that work well in low-contrast regions affect good contrast regions as well. This occurs due to the fact that some elements may vanish. A method focused on images with different luminance conditions is introduced in the present work. The proposed method is based on morphological transformations by reconstruction and rational operations, which, altogether, allow a more accurate contrast enhancement resulting in regions that are in harmony with their environment. Furthermore, due to the properties of these morphological transformations, the creation of new elements on the image is avoided. The processing is carried out on luminance values in the u'v'Y color space, which avoids the creation of new colors. As a result of the previous considerations, the proposed method keeps the natural color appearance of the image.

  12. Nonimmediate hypersensitivity reactions to iodinated contrast media.

    Science.gov (United States)

    Gómez, Enrique; Ariza, Adriana; Blanca-López, Natalia; Torres, Maria J

    2013-08-01

    To provide a detailed analysis of the latest findings on the mechanisms underlying the nonimmediate reactions to iodinated contrast media and comment on the recent advances in diagnosis, focusing on the roles of the skin test, drug provocation test (DPT), and lymphocyte transformation test (LTT). Several studies have reported new findings supporting an important role for T-lymphocytes in the nonimmediate reactions to iodinated contrast media. The LTT has been used as an in-vitro tool for diagnosis, but with variable results. However, the inclusion of autologous monocyte-derived dendritic cells as professional antigen-presenting cells has improved the sensitivity of this test. Regarding in-vivo diagnosis, although skin testing has been routine, it has now been shown that its sensitivity and negative predictive value are low. Recent studies have demonstrated that the DPT is a well tolerated and useful procedure that is necessary to confirm the diagnosis of nonimmediate hypersensitivity reactions to iodinated contrast media. Nonimmediate reactions to contrast media are usually T-cell mediated. Diagnosis is based on skin testing, although its sensitivity and negative predictive value are not optimal. Consequently, drug provocation testing is often needed to confirm the diagnosis and also to seek alternative contrast media that can be tolerated.

  13. Contrast agent choice for intravenous coronary angiography

    International Nuclear Information System (INIS)

    Zeman, H.D.; Siddons, D.P.

    1989-01-01

    The screening of the general population for coronary artery disease would be practical if a method existed for visualizing the extent of occlusion after an intravenous injection of contrast agent. Measurements performed with monochromatic synchrotron radiation x-rays and an iodine containing contrast agent at the Stanford Synchrotron Radiation Laboratory have shown that such an intravenous angiography procedure would be possible with an adequately intense monochromatic x-ray source. Because of the size and cost of synchrotron radiation facilities it would be desirable to make the most efficient use of the intensity available, while reducing as much as possible the radiation dose experienced by the patient. By choosing contrast agents containing elements with a higher atomic number than iodine, it is possible to both improve the image quality and reduce the patient radiation dose, while using the same synchrotron source. By using Si monochromator crystals with a small mosaic spread, it is possible to increase the x-ray flux available for imaging by over an order of magnitude, without any changes in the storage ring or wiggler magnet. The most critical imaging task for intravenous coronary angiography utilizing synchrotron radiation x-rays is visualizing a coronary artery through the left ventricle or aorta which also contains a contrast agent. Calculations have been made of the signal to noise ratio expected for this imaging task for various contrast agents with atomic numbers between that of iodine and bismuth

  14. Use of contrast agents for liver MRI

    International Nuclear Information System (INIS)

    Ward, Janice

    2007-01-01

    Contrast-enhanced MRI is recognised as one of the most accurate imaging methods for investigating diseases of the liver. Uniquely several different types of contrast agents are available for liver MRI. They can be divided into non-specific extracellular fluid space (ECF), hepatocyte specific and reticulo-endothelial system (RES) specific agents. They are used to improve the detection of focal liver lesions by increasing normal-abnormal tissue contrast and to assist in lesion characterisation by demonstrating tissue perfusion and cellular function. ECF-gadolinium (Gd) chelates have been widely used in abdominal MRI for many years. They provide valuable information regarding the vascularisation and perfusion characteristics of lesions and assist in lesion detection, particularly of hypervascular lesions. The hepatocyte and RES-specific agents further improve lesion detection, provide important functional information and allow the distinction between hepatocellular and non-hepatocellular tumours. This article describes the different MR contrast agents and discusses their current status for diagnosing focal liver lesions. The importance of optimised technique and appropriate selection of contrast agent is emphasised

  15. Visibility of minute objects with low contrast

    International Nuclear Information System (INIS)

    Sato, Nobuo

    1982-01-01

    Minimum perceptible contrast was obtained with a penetrameter made of aluminum plates, in which 40 very small holes were perforated. An object can be seen when its contrast exceeds the minimum perceptible contrast. Visual threshold contrast ratio offers minimum perceptible diameter (MPD) which is theoretically obtained from an image contrast corresponding to the technique applied. The MPDs were obtained prior to experiment as a function of system speed, beam quality, exposure range and magnification, which resulted in a reasonable agreement with the experimental results. The visibility of small dot-like objects depends on the granularity as its threshold is governed by the surrounding grainy noise. However it was revealed that MTF was as important as granularity. Dot and lineshaped objects were simulated with small glass beads and nylon fibrils, respectively, in order to make ROC analysis on the different radiographic techniques with a CGR Senograph 500T mammographic unit. The 1.5X magnification technique showed the largest advantage on phantom work basis, but clinical evaluation showed the different weight of the affecting physical factors. The results of ROC analysis were extended to entropy analysis. The visibility in actual mammography depends upon the acutance of images as Xeroradiography proved. (Kako, I.)

  16. Contrast enhanced ultrasound of sentinel lymph nodes

    Directory of Open Access Journals (Sweden)

    XinWu Cui

    2013-03-01

    Full Text Available Sentinel lymph nodes are the first lymph nodes in the region that receive lymphatic drainage from a primary tumor. The detection or exclusion of sentinel lymph node micrometastases is critical in the staging of cancer, especially breast cancer and melanoma because it directly affects patient’s prognosis and surgical management. Currently, intraoperative sentinel lymph node biopsies using blue dye and radioisotopes are the method of choice for the detection of sentinel lymph node with high identification rate. In contrast, conventional ultrasound is not capable of detecting sentinel lymph nodes in most cases. Contrast enhanced ultrasound with contrast specific imaging modes has been used for the evaluation and diagnostic work-up of peripherally located suspected lymphadenopathy. The method allows for real-time analysis of all vascular phases and the visualization of intranodal focal “avascular” areas that represent necrosis or deposits of neoplastic cells. In recent years, a number of animal and human studies showed that contrast enhanced ultrasound can be also used for the detection of sentinel lymph node, and may become a potential application in clinical routine. Several contrast agents have been used in those studies, including albumin solution, hydroxyethylated starch, SonoVue®, Sonazoid® and Definity®. This review summarizes the current knowledge about the use of ultrasound techniques in detection and evaluation of sentinel lymph node.

  17. Moderate Contrast in the Evaluation of Paintings Is Liked More but Remembered Less than High Contrast

    Directory of Open Access Journals (Sweden)

    Katinka Dijkstra

    2017-09-01

    Full Text Available Many visual aspects of paintings, as well as exposure to art and cultural norms, contribute to the aesthetic evaluation of paintings. The current study looked at heightened visual contrast as an important factor in the appreciation of paintings. Participants evaluated abstract digitized paintings that were manipulated in contrast for an appreciation task and were later presented with these paintings in a memory task. The results indicated that for art appreciation, a moderate increase in contrast resulted in the highest appreciation for paintings whereas recognition memory was better for paintings with a higher increase in contrast. These results replicate earlier findings with regard to the role of contrast in aesthetic perception and extend these findings by demonstrating a surprising different effect of contrast manipulation for recognition memory. Confidence with which memory decisions were made was in line with art appreciation decisions not memory performance.

  18. Elevated arousal levels enhance contrast perception.

    Science.gov (United States)

    Kim, Dongho; Lokey, Savannah; Ling, Sam

    2017-02-01

    Our state of arousal fluctuates from moment to moment-fluctuations that can have profound impacts on behavior. Arousal has been proposed to play a powerful, widespread role in the brain, influencing processes as far ranging as perception, memory, learning, and decision making. Although arousal clearly plays a critical role in modulating behavior, the mechanisms underlying this modulation remain poorly understood. To address this knowledge gap, we examined the modulatory role of arousal on one of the cornerstones of visual perception: contrast perception. Using a reward-driven paradigm to manipulate arousal state, we discovered that elevated arousal state substantially enhances visual sensitivity, incurring a multiplicative modulation of contrast response. Contrast defines vision, determining whether objects appear visible or invisible to us, and these results indicate that one of the consequences of decreased arousal state is an impaired ability to visually process our environment.

  19. Contrast Enhanced Spectral Mammography: A Review.

    Science.gov (United States)

    Patel, Bhavika K; Lobbes, M B I; Lewin, John

    2018-02-01

    Contrast-enhanced spectral mammography (CESM) provides low-energy 2D mammographic images comparable to standard digital mammography and a post-contrast recombined image to assess tumor neovascularity similar to magnetic resonance imaging (MRI). The utilization of CESM in the United States is currently low but could increase rapidly given many potential indications for clinical use. This article discusses historical background and literature review of indications and diagnostic accuracy of CESM to date. CESM is a growing technique for breast cancer detection and diagnosis that has levels of sensitivity and specificity on par with contrast-enhanced breast MRI. Because of its similar performance and ease of implementation, CESM is being adopted for multiple indications previously reserved for MRI, such as problem-solving, disease extent in newly diagnosed patients, and evaluating the treatment response of neoadjuvant chemotherapy. Copyright © 2018 Elsevier Inc. All rights reserved.

  20. Reconstruction methods for phase-contrast tomography

    Energy Technology Data Exchange (ETDEWEB)

    Raven, C.

    1997-02-01

    Phase contrast imaging with coherent x-rays can be distinguished in outline imaging and holography, depending on the wavelength {lambda}, the object size d and the object-to-detector distance r. When r << d{sup 2}{lambda}, phase contrast occurs only in regions where the refractive index fastly changes, i.e. at interfaces and edges in the sample. With increasing object-to-detector distance we come in the area of holographic imaging. The image contrast outside the shadow region of the object is due to interference of the direct, undiffracted beam and a beam diffracted by the object, or, in terms of holography, the interference of a reference wave with the object wave. Both, outline imaging and holography, offer the possibility to obtain three dimensional information of the sample in conjunction with a tomographic technique. But the data treatment and the kind of information one can obtain from the reconstruction is different.

  1. X-ray phase-contrast imaging

    Science.gov (United States)

    Endrizzi, Marco

    2018-01-01

    X-ray imaging is a standard tool for the non-destructive inspection of the internal structure of samples. It finds application in a vast diversity of fields: medicine, biology, many engineering disciplines, palaeontology and earth sciences are just few examples. The fundamental principle underpinning the image formation have remained the same for over a century: the X-rays traversing the sample are subjected to different amount of absorption in different parts of the sample. By means of phase-sensitive techniques it is possible to generate contrast also in relation to the phase shifts imparted by the sample and to extend the capabilities of X-ray imaging to those details that lack enough absorption contrast to be visualised in conventional radiography. A general overview of X-ray phase contrast imaging techniques is presented in this review, along with more recent advances in this fast evolving field and some examples of applications.

  2. Contrast media safety-an update

    DEFF Research Database (Denmark)

    Thomsen, Henrik S

    2011-01-01

    The value of contrast agents has for long been documented by their common daily use in imaging departments worldwide. In principle, they should be injected and leave the body immediately after use in the same condition or undergo natural metabolism without making any harm to the patient. However......, this is not the case. It is of utmost importance to reduce the prevalence to as close as possible to zero. This can be done by identifying the patients at risk before administration of contrast agents. For acute non-renal adverse reactions, it is also important to be prepared for treating them instantly. The current...... review is a short state of the art regarding adverse reactions to contrast agents....

  3. Letter contrast sensitivity function of the eye.

    Science.gov (United States)

    Liou, H L; Brennan, N A

    1998-06-01

    To provide empirical data of letter CSF for various levels of defocus under controlled conditions of luminance and age. Corrected distance visual acuities were tested at different levels of contrast and defocus. An experiment was conducted using the Medmont visual acuity tester on 10 young subjects and under normal room lighting. Empirical data of visual acuity were obtained for 7 levels of contrast (5, 10, 15, 25, 40, 60, 80%) and defocus levels of 0, +1 and +2D. A mathematical model was derived (R2=0.995) and this can be used to estimate visual acuity at various contrast levels for defocus of < or =+2D. This information is useful for the clinician as normative data and for further development of optical models to predict visual performance of the eye.

  4. Non-radiological contrast agents (MRI)

    International Nuclear Information System (INIS)

    Bonnemain, B.; Lautrou, J.; Meyer, D.; Doucet, D.

    1987-01-01

    Over the past few years, extensive research has been carried out in an attempt to develop contrast agents that could help improve both the performance (acquisition times) and the diagnostic efficacy of Magnetic Resonance Imaging (MRI) techniques. On the basis of physicochemical and pharmacological criteria discussed in this presentation, a few efficacious, well-tolerated compounds could be developed. Two of them, the gadolinium complexes Gd-DOTA and Gd-DTPA, are currently being tried in man. This first generation of contrast agents, which are aspecific markers of the intravascular space, has been shown to have good diagnostic potential in conventional MRI procedures. The diagnostic contribution of these contrast agents will probably be a most essential factor in new MRI techniques using low field strengh or fast imaging sequences [fr

  5. Contrast agent choice for intravenous coronary angiography

    International Nuclear Information System (INIS)

    Zeman, H.D.; Siddons, D.P.

    1990-01-01

    The screening of the general population for coronary artery disease would be practical if a method existed for visualizing the extent of occlusion after an intravenous injection of contrast agent. Measurements performed with monochromatic synchrotron radiation X-rays and an iodine-containing contrast agent at the Stanford Synchrotron Radiation Laboratory have shown that such an intravenous angiography procedure would be possible with an adequately intense monochromatic X-ray source. Because of the size and cost of synchrotron radiation facilities it would be desirable to make the most efficient use of the intensity available, while reducing as much as possible the radiation dose experienced by the patient. By choosing contrast agents containing elements with a higher atomic number than iodine, it is possible to both improve the image quality and reduce the patient radiation dose, while using the same synchrotron radiation source. By using Si monochromator crystals with a small mosaic spread, it is possible to increase the X-ray flux available for imaging by over an order of magnitude, without any changes in the storage ring or wiggler magnet. The most critical imaging task for intravenous coronary angiography utilizing synchrotron radiation X-rays is visualizing a coronary artery through the left ventricle or aorta which also contain contrast agent. Calculations have been made of the signal to noise ratio expected for this imaging task for various contrast agents with atomic numbers between that of iodine and bismuth. The X-ray energy spectrum of the X-17 superconduction wiggler beam line at the National Synchrotron Light Source at Brookhaven National Laboratory has been used for these calculations. Both perfect Si crystals and Si crystals with a small mosaic spread are considered as monochromators. Contrast agents containing Gd or Yb seem to have about the optimal calculated signal to noise ratio. (orig./HSI)

  6. Applications of energy loss contrast STIM

    International Nuclear Information System (INIS)

    Bench, G.; Saint, A.; Legge, G.J.F.; Cholewa, M.

    1992-01-01

    Scanning Transmission Ion Microscopy (STIM) with energy loss contrast is a quantitative imaging technique. A focussed MeV ion microbeam is scanned over the sample and measured energy losses of residual ions at each beam location are used to provide the contrast in the image. The technique is highly efficient as almost every ion carries useful information from which quantitative data can be obtained. The high efficiency of data collection at present necessitates the use of small beam currents. Therefore small apertures can be used and fine spatial resolution can be achieved. High efficiency also makes it possible to collect large data sets for high definition imaging with a small radiation dose. Owing to the simple relationship between energy loss and areal density, STIM with energy loss contrast can provide a quantitative image that can be used to obtain areal density information on the sample. These areal density maps can be used not only to provide a high resolution image of the sample but also to normalise Particle Induced Xray Emission (PIXE) data. The small radiation dose required to form these areal density maps also allows one to use STIM with energy loss contrast to quantitatively monitor ion beam induced specimen changes caused by higher doses and dose rates used in other microanalytical techniques. STIM with energy loss contrast also provides the possibility of stereo imaging and ion microtomography. STIM has also been used in conjunction with channeling to explore transmission channeling in thin crystals. This paper will discuss these applications of STIM with energy loss contrast and look at further developments from them

  7. Relationship Between Collateral Status, Contrast Transit, and Contrast Density in Acute Ischemic Stroke.

    Science.gov (United States)

    Kawano, Hiroyuki; Bivard, Andrew; Lin, Longting; Spratt, Neil J; Miteff, Ferdinand; Parsons, Mark W; Levi, Christopher R

    2016-03-01

    Collateral circulation is recognized to influence the life expectancy of the ischemic penumbra in acute ischemic stroke. The best method to quantify collateral status on acute imaging is uncertain. We aimed to determine the relationship between visual collateral status, quantitative collateral assessments, baseline computed tomographic perfusion measures, and tissue outcomes on follow-up imaging. Sixty-six consecutive patients with acute ischemic stroke clinically eligible for recanalization therapy and with M1 or M2 middle cerebral artery occlusion were evaluated. We compared the visual collateral scoring with measures of contrast peak time delay and contrast peak density. We also compared these measures for their ability to predict perfusion lesion and infarct core volumes, final infarct, and infarct growth. Shorter contrast peak time delay (P=0.041) and higher contrast peak density (P=0.002) were associated with good collateral status. Shorter contrast peak time delay correlated with higher contrast peak density (β=-4.413; P=0.037). In logistic regression analysis after adjustment for age, sex, onset-computed tomographic time, and occlusion site, higher contrast peak density was independently associated with good collateral status (P=0.009). Multiple regression analysis showed that higher contrast peak density was an independent predictor of smaller perfusion lesion volume (P=0.029), smaller ischemic core volume (P=0.044), smaller follow-up infarct volume (P=0.005), and smaller infarct growth volume (P=0.010). Visual collateral status, contrast peak density, and contrast peak time delay were inter-related, and good collateral status was strongly associated with contrast peak density. Contrast peak density in collateral vessel may be an important factor in tissue fate in acute ischemic stroke. © 2016 American Heart Association, Inc.

  8. Safety of contrast media. Focus on contrast-induced nephropathy (CIN)

    International Nuclear Information System (INIS)

    Kuwatsuru, Ryohei

    2011-01-01

    Despite advances in imaging diagnosis, contrast media still play an important role in diagnosing the existence of the disease, demonstrating the extent of disease, and determining the perfusion of the disease, which is important to make a differential diagnosis. However, the administration of contrast media may cause contrast-induced nephropathy (CIN), especially in patients with renal impairment. It is estimated that 20-30% of patients with renal impairment who received contrast media develop CIN. Though the precise cause of CIN currently remains unknown, almost all injected contrast media are excreted through the kidney and the effects of contrast media on the kidney are easily understood. As CIN is the most common cause of death due to complications after receiving contrast media, prevention of CIN is important. There are several known risk factors for CIN. Patients with renal impairment, diabetes mellitus, and dehydration are at high risk for CIN. Furthermore, a high osmolar contrast media, excessive amount of contrast media, and ionic contrast media are also risk factors for CIN. CIN can be prevented in several ways. Certain drugs seem to be useful to prevent CIN, while others are harmful. Hydration is useful to prevent CIN, although there is no widely acceptable hydration method to prevent CIN. Both sodium bicarbonate and N-acetylcysteine are promising candidates for prevention of CIN. There are few reports to study CIN after intravenous administration, although reports of CIN after percutaneous cardiac intervention (PCI) and angiography are well recognized. In clinical situations, intravenous administration of contrast media is common. Therefore, a study of CIN after intravenous administration of contrast media should be performed. (author)

  9. Global contrast based salient region detection

    KAUST Repository

    Cheng, Ming-Ming

    2011-08-25

    Reliable estimation of visual saliency allows appropriate processing of images without prior knowledge of their contents, and thus remains an important step in many computer vision tasks including image segmentation, object recognition, and adaptive compression. We propose a regional contrast based saliency extraction algorithm, which simultaneously evaluates global contrast differences and spatial coherence. The proposed algorithm is simple, efficient, and yields full resolution saliency maps. Our algorithm consistently outperformed existing saliency detection methods, yielding higher precision and better recall rates, when evaluated using one of the largest publicly available data sets. We also demonstrate how the extracted saliency map can be used to create high quality segmentation masks for subsequent image processing.

  10. Negative contrast peritoneography in the horse

    International Nuclear Information System (INIS)

    Lloyd, K.C.K.; Kerr, L.Y.; Meagher, D.M.; Baker, T.W.; Kurpershoek, C.J.

    1989-01-01

    A method of negative contrast peritoneography using CO 2 peritoneal insufflation technique was investigated in adult horses. Radiographic visualization of anatomic structures in the dorsal abdomen, including the kidneys, portions of the spleen and liver, dorsal stomach and mesenteric root region, was enhanced. Visualization of ventral abdominal structures was not enhanced. Negative contrast peritoneography allowed reduction in the radiographic technique from 140 kVp and 40 mAs before insufflation to 100 kVp and 5–10 mAs following insufflation. The technique was easily and safely performed with minimal patient discomfort and risk

  11. Dynamic contrast enhanced ultrasound for therapy monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, John M. [Department of Medical Biophysics, University of Toronto, Toronto, ON (Canada); Williams, Ross [Imaging Research, Sunnybrook Research Institute, Toronto, ON (Canada); Tremblay-Darveau, Charles; Sheeran, Paul S. [Department of Medical Biophysics, University of Toronto, Toronto, ON (Canada); Milot, Laurent [Department of Medical Imaging, University of Toronto, Toronto, ON (Canada); Bjarnason, Georg A. [Department of Medical Oncology, University of Toronto, and Sunnybrook Odette Cancer Centre, Toronto, ON (Canada); Burns, Peter N., E-mail: burns@sri.utoronto.ca [Department of Medical Biophysics, University of Toronto, Toronto, ON (Canada); Imaging Research, Sunnybrook Research Institute, Toronto, ON (Canada); Department of Medical Imaging, University of Toronto, Toronto, ON (Canada)

    2015-09-15

    Quantitative imaging is a crucial component of the assessment of therapies that target the vasculature of angiogenic or inflamed tissue. Dynamic contrast-enhanced ultrasound (DCE-US) using microbubble contrast offers the advantages of being sensitive to perfusion, non-invasive, cost effective and well suited to repeated use at the bedside. Uniquely, it employs an agent that is truly intravascular. This papers reviews the principles and methodology of DCE-US, especially as applied to anti-angiogenic cancer therapies. Reproducibility is an important attribute of such a monitoring method: results are discussed. More recent technical advances in parametric and 3D DCE-US imaging are also summarised and illustrated.

  12. Laser projection using generalized phase contrast

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin; Rodrigo, Peter John

    2007-01-01

    is introduced. An arbitrary phase shift filter eliminates the need for high-frequency modulation and conjugate phase encoding. This lowers device performance requirements and allows practical implementation with currently available dynamic spatial light modulators. (c) 2007 Optical Society of America.......We demonstrate experimental laser projection of a gray-level photographic image with 74% light efficiency using the generalized phase contrast (GPC) method. In contrast with a previously proposed technique [Alonzo et al., New J. Phys. 9, 132 (2007)], a new approach to image construction via GPC...

  13. Contrast optimization in multiphase arterial spin labeling

    International Nuclear Information System (INIS)

    Paiva, Fernando F.; Paschoal, Andre M.; Tovar-Moll, Fernanda; Moll, Jorge

    2013-01-01

    Multiphase ASL is an effective way to overcome the regional variation of the transit time that difficult the estimation of perfusion values. However, with conventional multiple phases ASL techniques, the ASL contrast at later phases is impaired due to repeated application of excitation pulses and longitudinal relaxation making it difficult to evaluate the tissue perfusion in regions where the transit time is longer. In the present study, we show an improvement of the acquisition scheme by exploring a modulation on the flip angle of the MR acquisition to keep the ASL contrast constant over multiple phases. (author)

  14. Hypersensitivity to contrast media and dyes.

    Science.gov (United States)

    Brockow, Knut; Sánchez-Borges, Mario

    2014-08-01

    This article updates current knowledge on hypersensitivity reactions to diagnostic contrast media and dyes. After application of a single iodinated radiocontrast medium (RCM), gadolinium-based contrast medium, fluorescein, or a blue dye, a hypersensitivity reaction is not a common finding; however, because of the high and still increasing frequency of those procedures, patients who have experienced severe reactions are nevertheless frequently encountered in allergy departments. Evidence on allergologic testing and management is best for iodinated RCM, limited for blue dyes, and insufficient for fluorescein. Skin tests can be helpful in the diagnosis of patients with hypersensitivity reactions to these compounds. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Global contrast based salient region detection

    KAUST Repository

    Cheng, Ming-Ming; Zhang, Guo-Xin; Mitra, Niloy J.; Huang, Xiaolei; Hu, Shi-Min

    2011-01-01

    Reliable estimation of visual saliency allows appropriate processing of images without prior knowledge of their contents, and thus remains an important step in many computer vision tasks including image segmentation, object recognition, and adaptive compression. We propose a regional contrast based saliency extraction algorithm, which simultaneously evaluates global contrast differences and spatial coherence. The proposed algorithm is simple, efficient, and yields full resolution saliency maps. Our algorithm consistently outperformed existing saliency detection methods, yielding higher precision and better recall rates, when evaluated using one of the largest publicly available data sets. We also demonstrate how the extracted saliency map can be used to create high quality segmentation masks for subsequent image processing.

  16. Post-traumatic contrast enhancing brain lesion

    International Nuclear Information System (INIS)

    Kim, Dae Jung; Kim, Hyun Sook; Jeong, Min Sun; Kim, Deok Ryeong; Cho, Young Kwon; Choi, Yun Sun

    2014-01-01

    Only a few studies have been reported on the MR contrast enhancement and the apparent diffusion coefficient (ADC) findings of the post-traumatic lesion of the brain. We report a case of the venous ischemia in the left frontal lobe observed in the MRI obtained one day after the incidence of trauma. Considering the presented slight increase in the ADC, the vasogenic edema was thought to be the major mechanism of the venous ischemia and excitotoxic injury. In spite of a slight increase in the ADC, the hyperintensity in the diffusion weighted imaging and contrast-enhanced areas eventually changed into hemorrhagic lesions.

  17. Post-traumatic contrast enhancing brain lesion

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Jung; Kim, Hyun Sook; Jeong, Min Sun; Kim, Deok Ryeong; Cho, Young Kwon; Choi, Yun Sun [Eulji Hospital, Eulji University College of Medicine, Seoul (Korea, Republic of)

    2014-10-15

    Only a few studies have been reported on the MR contrast enhancement and the apparent diffusion coefficient (ADC) findings of the post-traumatic lesion of the brain. We report a case of the venous ischemia in the left frontal lobe observed in the MRI obtained one day after the incidence of trauma. Considering the presented slight increase in the ADC, the vasogenic edema was thought to be the major mechanism of the venous ischemia and excitotoxic injury. In spite of a slight increase in the ADC, the hyperintensity in the diffusion weighted imaging and contrast-enhanced areas eventually changed into hemorrhagic lesions.

  18. Double contrast barium meal and acetylcysteine

    International Nuclear Information System (INIS)

    Kinnunen, J.; Pietilae, J.; Ahovuo, J.; Mankinen, P.; Tervahartiala, P.

    1989-01-01

    In a prospective double blind study, acetylcysteine, a local and systemic respiratory tract mucolytic agent, or a placebo, were given to 100 patients prior to a double contrast barium meal to decrease the gastric mucus viscosity and to make the mucus layer thinner, in order to permit barium to outline the furrows surrounding the areae gastricae instead of the overlying thick mucus. However, acetylcysteine failed to improve either visualization of the areae gastricae or the general quality of the double contrast barium meal. (orig.)

  19. Contrastive hierarchies, privative features, and Portuguese vowels

    Directory of Open Access Journals (Sweden)

    Joaquim Brandão de Carvalho

    2011-01-01

    Full Text Available Dresher’s (2009 Contrastive hierarchy theory (CHT is intended to provide a unified account of both sides of phonological primes: contrastivity and behaviour. This article explores the point and the possibility of extending CHT, which is based on binary features, to a system of monovalent elements that is much indebted to Schane’s (1984 Particle Phonology. It shows how several aspects of the phonology of European Portuguese nuclei that seem prima facie independent from one another – such as reduction patterns and the inventory of diphthongs and nasal vowels – are constrained by element hierarchy, and, thus, receive a unitary account.

  20. Contrast-Enhanced Ultrasound in Vascular Surgery

    DEFF Research Database (Denmark)

    Bredahl, Kim; Mestre, Xavier Marti; Coll, Ramon Vila

    2017-01-01

    modalities. Ultrasound has only challenged these methods in assessment of carotid disease, aortic aneurysms, venous insufficiency, and thromboembolism and in surveillance of in situ bypasses. These practice patterns may change with the introduction of second-generation ultrasound contrast agents which...... are easy to use, manageable, and safe. This topical review attempts to summarize and highlight the current evidence and future prospects for contrast-enhanced ultrasound in vascular surgery, with a particular focus on opportunities in carotid and lower limb arteriosclerotic disease and surveillance after...

  1. Dynamic contrast enhanced MRI for perfusion quantification

    DEFF Research Database (Denmark)

    Andersen, Irene Klærke

    2002-01-01

    Magnetic resonance imaging, during bolus passage of a paramagnetic contrast agent, is used world-wide to obtain parameters that reflect the pathological state of tissue. Abnormal perfusion occurs in diseases such as stoke and tumour. Consequently, perfusion quantication could have signi cant...... clinical value both in diagnosis and treatment of such pathologies. One approach for perfusion quanti cation involves using the contrast mechanism that a ects the transverse relaxation rates of the magnetization, R2 or R 2 , since this provides the most pronounced effect. However, the linearity between...

  2. The double contrast examination of the colon

    International Nuclear Information System (INIS)

    Welin, S.; Welin, G.

    1980-01-01

    The double contrast method has been modified in order to get a more detailed picture of the mucous membrane of the colon. The method has been employed at Malmoe hospital since 1953. The method and its diagnostic application in cases of adenoids, villiferous tumours, diverticula, Crohn's disease, ulcerating colitis, and deformation of the rectum/sigma junction due to external endometriosis and peritoneal carcinosis are described. The diagnostic values of the double contrast method and colposcopy/biopsy of the colon are compared. The two methods are found to be complementary. (MG) [de

  3. Exogenous contrast agents for thermoacoustic imaging: An investigation into the underlying sources of contrast

    International Nuclear Information System (INIS)

    Ogunlade, Olumide; Beard, Paul

    2015-01-01

    Purpose: Thermoacoustic imaging at microwave excitation frequencies is limited by the low differential contrast exhibited by high water content tissues. To overcome this, exogenous thermoacoustic contrast agents based on gadolinium compounds, iron oxide, and single wall carbon nanotubes have previously been suggested and investigated. However, these previous studies did not fully characterize the electric, magnetic, and thermodynamic properties of these agents thus precluding identification of the underlying sources of contrast. To address this, measurements of the complex permittivity, complex permeability, DC conductivity, and Grüneisen parameter have been made. These measurements allowed the origins of the contrast provided by each substance to be identified. Methods: The electric and magnetic properties of the contrast agents were characterized at 3 GHz using two rectangular waveguide cavities. The DC conductivity was measured separately using a conductivity meter. Thermoacoustic signals were then acquired and compared to those generated in water. Finally, 3D electromagnetic simulations were used to decouple the different contributions to the absorbed power density. Results: It was found that the gadolinium compounds provided appreciable electric contrast but not originating from the gadolinium itself. The contrast was either due to dissociation of the gadolinium salt which increased ionic conductivity or its nondissociated polar fraction which increased dielectric polarization loss or a combination of both. In addition, very high concentrations were required to achieve appreciable contrast, to the extent that the Grüneisen parameter increased significantly and became a source of contrast. Iron oxide particles were found to produce low but measurable dielectric contrast due to dielectric polarization loss, but this is attributed to the coating of the particles not the iron oxide. Single wall carbon nanotubes did not provide measurable contrast of any type

  4. Contextual effects on perceived contrast: figure-ground assignment and orientation contrast.

    Science.gov (United States)

    Self, Matthew W; Mookhoek, Aart; Tjalma, Nienke; Roelfsema, Pieter R

    2015-02-02

    Figure-ground segregation is an important step in the path leading to object recognition. The visual system segregates objects ('figures') in the visual scene from their backgrounds ('ground'). Electrophysiological studies in awake-behaving monkeys have demonstrated that neurons in early visual areas increase their firing rate when responding to a figure compared to responding to the background. We hypothesized that similar changes in neural firing would take place in early visual areas of the human visual system, leading to changes in the perception of low-level visual features. In this study, we investigated whether contrast perception is affected by figure-ground assignment using stimuli similar to those in the electrophysiological studies in monkeys. We measured contrast discrimination thresholds and perceived contrast for Gabor probes placed on figures or the background and found that the perceived contrast of the probe was increased when it was placed on a figure. Furthermore, we tested how this effect compared with the well-known effect of orientation contrast on perceived contrast. We found that figure-ground assignment and orientation contrast produced changes in perceived contrast of a similar magnitude, and that they interacted. Our results demonstrate that figure-ground assignment influences perceived contrast, consistent with an effect of figure-ground assignment on activity in early visual areas of the human visual system. © 2015 ARVO.

  5. Exogenous contrast agents for thermoacoustic imaging: An investigation into the underlying sources of contrast

    Energy Technology Data Exchange (ETDEWEB)

    Ogunlade, Olumide, E-mail: o.ogunlade@ucl.ac.uk; Beard, Paul [Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT (United Kingdom)

    2015-01-15

    Purpose: Thermoacoustic imaging at microwave excitation frequencies is limited by the low differential contrast exhibited by high water content tissues. To overcome this, exogenous thermoacoustic contrast agents based on gadolinium compounds, iron oxide, and single wall carbon nanotubes have previously been suggested and investigated. However, these previous studies did not fully characterize the electric, magnetic, and thermodynamic properties of these agents thus precluding identification of the underlying sources of contrast. To address this, measurements of the complex permittivity, complex permeability, DC conductivity, and Grüneisen parameter have been made. These measurements allowed the origins of the contrast provided by each substance to be identified. Methods: The electric and magnetic properties of the contrast agents were characterized at 3 GHz using two rectangular waveguide cavities. The DC conductivity was measured separately using a conductivity meter. Thermoacoustic signals were then acquired and compared to those generated in water. Finally, 3D electromagnetic simulations were used to decouple the different contributions to the absorbed power density. Results: It was found that the gadolinium compounds provided appreciable electric contrast but not originating from the gadolinium itself. The contrast was either due to dissociation of the gadolinium salt which increased ionic conductivity or its nondissociated polar fraction which increased dielectric polarization loss or a combination of both. In addition, very high concentrations were required to achieve appreciable contrast, to the extent that the Grüneisen parameter increased significantly and became a source of contrast. Iron oxide particles were found to produce low but measurable dielectric contrast due to dielectric polarization loss, but this is attributed to the coating of the particles not the iron oxide. Single wall carbon nanotubes did not provide measurable contrast of any type

  6. Interval between injection of contrast material and positive contrast cheliography affects accurate diagnosis of diaphragmatic hernia

    Directory of Open Access Journals (Sweden)

    Ismail A. Sen

    2015-01-01

    Full Text Available The aim of this study was to evaluate the clinical, surgical and diagnostic imaging findings in 11 cats and 3 dogs with suspected acute and chronic traumatic diaphragmatic hernia, and to compare the results of positive contrast cheliography (peritoneography taken immediately and 5 min after the injection of contrast material. Thoracic and abdominal radiography, ultrasonography, and positive contrast cheliography of all animals were performed. Eight cases were considered as acute and six cases were considered chronic. The contrast images taken immediately after the injection of contrast material revealed the contrast material in the thoracic cavity in 8/8 acute trauma patients, but in none of the chronic cases. In 5/6 of these cases contrast material was seen in the thoracal cavity only in additional images taken after 5 min. One patient was diagnosed with FIP and excluded from the study. Twelve cases had complete resolution and one animal died during the early postoperative period. Our results suggest that positive contrast cheliography performed immediately after the injection of contrast material may not reveal chronic cases of diaphragmatic hernia and a second imaging (or imaging after 5 min is indicated in order not to overlook chronic cases.

  7. Contrast-enhanced angiographic cone-beam computed tomography without pre-diluted contrast medium

    Energy Technology Data Exchange (ETDEWEB)

    Jo, K.I.; Kim, S.R.; Choi, J.H.; Kim, K.H.; Jeon, P. [Sungkyunkwan University School of Medicine, Department of Radiology, Samsung Medical Center, Gangnam-gu, Seoul (Korea, Republic of)

    2015-11-15

    Contrast-enhanced cone-beam computed tomography (CBCT) has been introduced and accepted as a useful technique to evaluate delicate vascular anatomy and neurovascular stents. Current protocol for CBCT requires quantitative dilution of contrast medium to obtain adequate quality images. Here, we introduce simple methods to obtain contrast-enhanced CBCT without quantitative contrast dilution. A simple experiment was performed to estimate the change in flow rate in the internal carotid artery during the procedure. Transcranial doppler (TCD) was used to evaluate the velocity change before and after catheterization and fluid infusion. In addition, 0.3 cm{sup 3}/s (n = 3) and 0.2 cm{sup 3}/s (n = 7) contrast infusions were injected and followed by saline flushes using a 300 mmHg pressure bag to evaluate neurovascular stent and host arteries. Flow velocities changed -15 ± 6.8 % and +17 ± 5.5 % from baseline during catheterization and guiding catheter flushing with a 300 mmHg pressure bag, respectively. Evaluation of the stents and vascular structure was feasible using this technique in all patients. Quality assessment showed that the 0.2 cm{sup 3}/s contrast infusion protocol was better for evaluating the stent and host artery. Contrast-enhanced CBCT can be performed without quantitative contrast dilution. Adequate contrast dilution can be achieved with a small saline flush and normal blood flow. (orig.)

  8. Density contrast indicators in cosmological dust models

    Indian Academy of Sciences (India)

    contrast, which may or may not be monotonically increasing with time. We also find that monotonic- ity seems to be related to the initial conditions of the model, which may be of potential interest in connection with debates regarding gravitational entropy and the arrow of time. 1. Introduction. An important question in ...

  9. Refractive index contrast in porous silicon multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Nava, R.; Mora, M.B. de la; Tagueena-Martinez, J. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Rio, J.A. del [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Temixco, Morelos (Mexico); Centro Morelense de Innovacion y Transferencia Tecnologica, Consejo de Ciencia y Tecnologia del Estado de Morelos (Mexico)

    2009-07-15

    Two of the most important properties of a porous silicon multilayer for photonic applications are flat interfaces and a relative large refractive index contrast between layers in the optical wavelength range. In this work, we studied the effect of the current density and HF electrolyte concentration on the refractive index of porous silicon. With the purpose of increasing the refractive index contrast in a multilayer, the refractive index of porous silicon produced at low current was studied in detail. The current density applied to produce the low porosity layers was limited in order to keep the electrolyte flow through the multilayer structure and to avoid deformation of layer interfaces. We found that an electrolyte composed of hydrofluoric acid, ethanol and glycerin in a ratio of 3:7:1 gives a refractive index contrast around 1.3/2.8 at 600 nm. Several multilayer structures with this refractive index contrast were fabricated, such as dielectric Bragg mirrors and microcavities. Reflectance spectra of the structures show the photonic quality of porous silicon multilayers produced under these electrochemical conditions. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Marginal contrasts and the Contrastivist Hypothesis

    Directory of Open Access Journals (Sweden)

    Daniel Currie Hall

    2016-12-01

    Full Text Available The Contrastivist Hypothesis (CH; Hall 2007; Dresher 2009 holds that the only features that can be phonologically active in any language are those that serve to distinguish phonemes, which presupposes that phonemic status is categorical. Many researchers, however, demonstrate the existence of gradient relations. For instance, Hall (2009 quantifies these using the information-theoretic measure of entropy (unpredictability of distribution and shows that a pair of sounds may have an entropy between 0 (totally predictable and 1 (totally unpredictable. We argue that the existence of such intermediate degrees of contrastiveness does not make the CH untenable, but rather offers insight into contrastive hierarchies. The existence of a continuum does not preclude categorical distinctions: a categorical line can be drawn between zero entropy (entirely predictable, and thus by the CH phonologically inactive and non-zero entropy (at least partially contrastive, and thus potentially phonologically active. But this does not mean that intermediate degrees of surface contrastiveness are entirely irrelevant to the CH; rather, we argue, they can shed light on how deeply ingrained a phonemic distinction is in the phonological system. As an example, we provide a case study from Pulaar [ATR] harmony, which has previously been claimed to be problematic for the CH.

  11. Embedded high-contrast distributed grating structures

    Science.gov (United States)

    Zubrzycki, Walter J.; Vawter, Gregory A.; Allerman, Andrew A.

    2002-01-01

    A new class of fabrication methods for embedded distributed grating structures is claimed, together with optical devices which include such structures. These new methods are the only known approach to making defect-free high-dielectric contrast grating structures, which are smaller and more efficient than are conventional grating structures.

  12. Nature versus Nurture: The Simple Contrast

    Science.gov (United States)

    Davidoff, Jules; Goldstein, Julie; Roberson, Debi

    2009-01-01

    We respond to the commentary of Franklin, Wright, and Davies ("Journal of Experimental Child Psychology, 102", 239-245 [2009]) by returning to the simple contrast between nature and nurture. We find no evidence from the toddler data that makes us revise our ideas that color categories are learned and never innate. (Contains 1 figure.)

  13. Using the phase-space imager to analyze partially coherent imaging systems: bright-field, phase contrast, differential interference contrast, differential phase contrast, and spiral phase contrast

    Science.gov (United States)

    Mehta, Shalin B.; Sheppard, Colin J. R.

    2010-05-01

    Various methods that use large illumination aperture (i.e. partially coherent illumination) have been developed for making transparent (i.e. phase) specimens visible. These methods were developed to provide qualitative contrast rather than quantitative measurement-coherent illumination has been relied upon for quantitative phase analysis. Partially coherent illumination has some important advantages over coherent illumination and can be used for measurement of the specimen's phase distribution. However, quantitative analysis and image computation in partially coherent systems have not been explored fully due to the lack of a general, physically insightful and computationally efficient model of image formation. We have developed a phase-space model that satisfies these requirements. In this paper, we employ this model (called the phase-space imager) to elucidate five different partially coherent systems mentioned in the title. We compute images of an optical fiber under these systems and verify some of them with experimental images. These results and simulated images of a general phase profile are used to compare the contrast and the resolution of the imaging systems. We show that, for quantitative phase imaging of a thin specimen with matched illumination, differential phase contrast offers linear transfer of specimen information to the image. We also show that the edge enhancement properties of spiral phase contrast are compromised significantly as the coherence of illumination is reduced. The results demonstrate that the phase-space imager model provides a useful framework for analysis, calibration, and design of partially coherent imaging methods.

  14. Lexical representation of novel L2 contrasts

    Science.gov (United States)

    Hayes-Harb, Rachel; Masuda, Kyoko

    2005-04-01

    There is much interest among psychologists and linguists in the influence of the native language sound system on the acquisition of second languages (Best, 1995; Flege, 1995). Most studies of second language (L2) speech focus on how learners perceive and produce L2 sounds, but we know of only two that have considered how novel sound contrasts are encoded in learners' lexical representations of L2 words (Pallier et al., 2001; Ota et al., 2002). In this study we investigated how native speakers of English encode Japanese consonant quantity contrasts in their developing Japanese lexicons at different stages of acquisition (Japanese contrasts singleton versus geminate consonants but English does not). Monolingual English speakers, native English speakers learning Japanese for one year, and native speakers of Japanese were taught a set of Japanese nonwords containing singleton and geminate consonants. Subjects then performed memory tasks eliciting perception and production data to determine whether they encoded the Japanese consonant quantity contrast lexically. Overall accuracy in these tasks was a function of Japanese language experience, and acoustic analysis of the production data revealed non-native-like patterns of differentiation of singleton and geminate consonants among the L2 learners of Japanese. Implications for theories of L2 speech are discussed.

  15. Bounding the bias of contrastive divergence learning

    DEFF Research Database (Denmark)

    Fischer, Anja; Igel, Christian

    2011-01-01

    Optimization based on k-step contrastive divergence (CD) has become a common way to train restricted Boltzmann machines (RBMs). The k-step CD is a biased estimator of the log-likelihood gradient relying on Gibbs sampling. We derive a new upper bound for this bias. Its magnitude depends on k...

  16. Phase-contrast X-ray CT

    Energy Technology Data Exchange (ETDEWEB)

    Momose, Atsushi [Hitachi Ltd., Saitama (Japan). Advanced Research Laboratory; Takeda, Tohoru; Itai, Yuji

    1995-12-01

    Phase-contrast X-ray computed tomography (CT) enabling the observation of biological soft tissues without contrast enhancement has been developed. The X-ray phase shift caused by an object is measured and input to a standard CT reconstruction algorithm. A thousand times increase in the image sensitivity to soft tissues is achieved compared with the conventional CT using absorption contrast. This is because the X-ray phase shift cross section of light elements is about a thousand times larger than the absorption cross section. The phase shift is detected using an X-ray interferometer and computer analyses of interference patterns. Experiments were performed using a synchrotron X-ray source. Excellent image sensitivity is demonstrated in the observation of cancerous rabbit liver. The CT images distinguish cancer lesion from normal liver tissue and, moreover, visualize the pathological condition in the lesion. Although the X-ray energy employed and the present observation area size are not suitable for medical applications as they are, phase-contrast X-ray CT is promising for investigating the internal structure of soft tissue which is almost transparent for X-rays. The high sensitivity also provides the advantage of reducing X-ray doses. (author).

  17. Progress in high index contrast integrated optics

    NARCIS (Netherlands)

    Baets, R.G.F.; Bienstman, P.; Bogaerts, W.; Brouckaert, J.; De Backere, P.; Dumon, P.; Roelkens, G.; Scheerlinck, S.; Smit, M.K.; Taillaert, D.; Van Campenhout, J.; Van Laere, F.; Thourhout, Van D.

    2007-01-01

    A large fraction of the recent innovation in integrated optics is enabled by the use of high index contrast structures and devices. The strong confinement achievable in such devices allows for dramatic performance benefits and downscaling. In this paper the progress in this field is reviewed.

  18. Radiculography with water-soluble contraste medium

    International Nuclear Information System (INIS)

    Araujo Pinheiro, R.S. de

    1987-01-01

    The etiologic diagnosis of the lumbar pain is discussed. The radiculography with water-soluble contrast medium is used and 250 cases are studied. Some practical criteria of indication executation and interpretation of the examination are reported. (M.A.C.) [pt

  19. Two Contrasting Concepts of Participatory Leadership.

    Science.gov (United States)

    Harman, Willis W.

    1981-01-01

    Two contrasting concepts of how humans can best manage affairs and express leadership are explored. Both concepts concur in the conviction that bureaucratic/hierarchical management forms are due to be replaced by a better form. The concepts differ in underlying assumptions about the nature of the human mind and of leadership. (CJ)

  20. Cardiac image segmentation for contrast agent videodensitometry

    NARCIS (Netherlands)

    Mischi, M.; Kalker, A.A.C.M.; Korsten, H.H.M.

    2005-01-01

    Indicator dilution techniques are widely used in the intensive care unit and operating room for cardiac parameter measurements. However, the invasiveness of current techniques represents a limitation for their clinical use. The development of stable ultrasound contrast agents allows new applications

  1. International guidelines for contrast-enhanced ultrasonography

    DEFF Research Database (Denmark)

    Nolsøe, Christian Pállson; Lorentzen, Torben

    2016-01-01

    The intent of this review is to discuss and comment on common clinical scenarios in which contrast-enhanced ultrasonography (CEUS) may play a decisive role and to illustrate important points with typical cases. With the advent of CEUS, the scope of indications for ultrasonography has been dramati...

  2. Recent hot topics in contrast media

    DEFF Research Database (Denmark)

    Thomsen, Henrik S

    2011-01-01

    This editorial reviews the way in which the facts related to the safety of iodinated and gadolinium based contrast agents have emerged over the last two decades. This is especially important given their ever increasing usage in modern computed tomographic (CT) and Magnetic resonance imaging (MRI)...

  3. CONTRASTIVE CULTURAL FEATURES IN FL TEACHING.

    Science.gov (United States)

    FISCHER, MILLA

    CONTRASTIVE CULTURAL FEATURES SHOULD BE INCLUDED WITHIN THE FRAMEWORK OF THE GRAMMATICAL LESSON AS A MEANS OF COUNTERBALANCING THE GENERALLY UNSATISFACTORY MATERIAL USED FOR RUSSIAN TEXTS. LESSONS FOR AMERICAN STUDENTS LEARNING RUSSIAN SHOULD INCLUDE PHONOLOGICAL DRILLS ON VOWEL LENGTHS, DISTRIBUTION OF VOICED OBSTRUENTS, AND OBSTRUENT CLUSTERS,…

  4. Contrast agents in magnetic resonance imaging

    International Nuclear Information System (INIS)

    Karadjian, V.

    1987-01-01

    The origine of nuclear magnetic resonance signal is reminded and different ways for contrast enhancement in magnetic resonance imaging are presented, especially, modifications of tissus relaxation times. Investigations have focused on development of agents incorporating either paramagnetic ions or stable free radicals. Pharmacological and toxicological aspects are developed. The diagnostic potential of these substances is illustrated by the example of gadolinium complexes [fr

  5. Contrast-enhanced MRI of the lung

    International Nuclear Information System (INIS)

    Kauczor, Hans-Ulrich; Kreitner, Karl-Friedrich

    2000-01-01

    The lung has long been neglected by MR imaging. This is due to unique intrinsic difficulties: (1) signal loss due to cardiac pulsation and respiration; (2) susceptibility artifacts caused by multiple air-tissue interfaces; (3) low proton density. There are many MR strategies to overcome these problems. They consist of breath-hold imaging, respiratory and cardiac gating procedures, use of short repetition and echo times, increase of the relaxivity of existing spins by administration of intravenous contrast agents, and enrichment of spin density by hyperpolarized noble gases or oxygen. Improvements in scanner performance and frequent use of contrast media have increased the interest in MR imaging and MR angiography of the lung. They can be used on a routine basis for the following indications: characterization of pulmonary nodules, staging of bronchogenic carcinoma, in particular assessment of chest wall invasion; evaluation of inflammatory activity in interstitial lung disease; acute pulmonary embolism, chronic thromboembolic pulmonary hypertension, vascular involvement in malignant disease; vascular abnormalities. Future perspectives include perfusion imaging using extracellular or intravascular (blood pool) contrast agents and ventilation imaging using inhalation of hyperpolarized noble gases, of paramagnetic oxygen or of aerosolized contrast agents. These techniques represent new approaches to functional lung imaging. The combination of visualization of morphology and functional assessment of ventilation and perfusion is unequalled by any other technique

  6. Contrast media safety-an update

    DEFF Research Database (Denmark)

    Thomsen, Henrik S

    2011-01-01

    The value of contrast agents has for long been documented by their common daily use in imaging departments worldwide. In principle, they should be injected and leave the body immediately after use in the same condition or undergo natural metabolism without making any harm to the patient. However...

  7. Internal noise sources limiting contrast sensitivity.

    Science.gov (United States)

    Silvestre, Daphné; Arleo, Angelo; Allard, Rémy

    2018-02-07

    Contrast sensitivity varies substantially as a function of spatial frequency and luminance intensity. The variation as a function of luminance intensity is well known and characterized by three laws that can be attributed to the impact of three internal noise sources: early spontaneous neural activity limiting contrast sensitivity at low luminance intensities (i.e. early noise responsible for the linear law), probabilistic photon absorption at intermediate luminance intensities (i.e. photon noise responsible for de Vries-Rose law) and late spontaneous neural activity at high luminance intensities (i.e. late noise responsible for Weber's law). The aim of this study was to characterize how the impact of these three internal noise sources vary with spatial frequency and determine which one is limiting contrast sensitivity as a function of luminance intensity and spatial frequency. To estimate the impact of the different internal noise sources, the current study used an external noise paradigm to factorize contrast sensitivity into equivalent input noise and calculation efficiency over a wide range of luminance intensities and spatial frequencies. The impact of early and late noise was found to drop linearly with spatial frequency, whereas the impact of photon noise rose with spatial frequency due to ocular factors.

  8. Theory and Contrastive Explanation in Ethnography

    Science.gov (United States)

    Lichterman, Paul; Reed, Isaac Ariail

    2015-01-01

    We propose three interlinked ways that theory helps researchers build causal claims from ethnographic research. First, theory guides the casing and re-casing of a topic of study. Second, theoretical work helps craft a clear causal question via the construction of a contrast space of the topic of investigation. Third, the researcher uses theory to…

  9. Recent hot topics in contrast media

    DEFF Research Database (Denmark)

    Thomsen, Henrik S

    2011-01-01

    This editorial reviews the way in which the facts related to the safety of iodinated and gadolinium based contrast agents have emerged over the last two decades. This is especially important given their ever increasing usage in modern computed tomographic (CT) and Magnetic resonance imaging (MRI...

  10. Subwavelength Hyperlens Resolution With Perfect Contrast Function

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Repän, Taavi; Zhukovsky, Sergei

    2018-01-01

    , in principle, two sources standing apart at any subwavelength distance can be distinguished. We suggest two feasible designs, the first of which employs the obliquely incident light, while the second one is based on a properly designed metasurface. The concept can be used in high‐contrast subwavelength...

  11. Contrast effects on stop consonant identification.

    Science.gov (United States)

    Diehl, R L; Elman, J L; McCusker, S B

    1978-11-01

    Changes in the identification of speech sounds following selective adaptation are usually attributed to a reduction in sensitivity of auditory feature detectors. An alternative explanation of these effects is based on the notion of response contrast. In several experiments, subjects identified the initial segment of synthetic consonant-vowel syllables as either the voiced stop [b] or the voiceless stop [ph]. Each test syllable had a value of voice onset time (VOT) that placed it near the English voiced-voiceless boundary. When the test syllables were preceded by a single clear [b] (VOT = -100 msec), subjects tended to identify them as [ph], whereas when they were preceded by an unambiguous [ph] (VOT = 100 msec), the syllables were predominantly labeled [b]. This contrast effect occurred even when the contextual stimuli were velar and the test stimuli were bilabial, which suggests a featural rather than a phonemic basis for the effect. To discount the possibility that these might be instances of single-trial sensory adaptation, we conducted a similar experiment in which the contextual stimuli followed the test items. Reliable contrast effects were still obtained. In view of these results, it appears likely that response contrast accounts for at least some component of the adaptation effects reported in the literature.

  12. Representations in Calculus: Two Contrasting Cases.

    Science.gov (United States)

    Aspinwall, Leslie; Shaw, Kenneth L.

    2002-01-01

    Illustrates the contrasting thinking processes of two beginning calculus students' geometric and analytic schemes for the derivative function. Suggests that teachers can enhance students' understanding by continuing to demonstrate how different representations of the same mathematical concept provide additional information. (KHR)

  13. Contrast media osmolality and plasma volume changes

    International Nuclear Information System (INIS)

    Hine, A.L.; Lui, D.; Dawson, P.; Middlesex Hospital, London

    1985-01-01

    A theoretical and experimental study of the plasma volume expansion consequent on the hyperosmolality of contrast media is presented. In the case of the ratio 1.5 media theory and experiment coincide closely but in the case of the ratio 3 media the observed changes exceed the predicted. It is proposed that this is due partly to the slower diffusion of the ratio 3 media out of the intravascular space and partly due to the fact that the osmotic load presented by these media is greater than would be expected from a study of their commercial solutions in which osmolality is reduced by molecular aggregation. The implications for the relative haemodynamic effects of different contrast media are discussed. The osmotic effects of contrast media also play a part in determining the image quality achievable in intravenous digital subtraction angiography (IV-DSA). It is predicted that ratio 3 contrast media will give better quality images in IV-DSA than ratio 1.5 media. (orig.)

  14. Semantics, contrastive linguistics and parallel corpora

    Directory of Open Access Journals (Sweden)

    Violetta Koseska

    2014-09-01

    Full Text Available Semantics, contrastive linguistics and parallel corpora In view of the ambiguity of the term “semantics”, the author shows the differences between the traditional lexical semantics and the contemporary semantics in the light of various semantic schools. She examines semantics differently in connection with contrastive studies where the description must necessary go from the meaning towards the linguistic form, whereas in traditional contrastive studies the description proceeded from the form towards the meaning. This requirement regarding theoretical contrastive studies necessitates construction of a semantic interlanguage, rather than only singling out universal semantic categories expressed with various language means. Such studies can be strongly supported by parallel corpora. However, in order to make them useful for linguists in manual and computer translations, as well as in the development of dictionaries, including online ones, we need not only formal, often automatic, annotation of texts, but also semantic annotation - which is unfortunately manual. In the article we focus on semantic annotation concerning time, aspect and quantification of names and predicates in the whole semantic structure of the sentence on the example of the “Polish-Bulgarian-Russian parallel corpus”.

  15. Contrast enhancement of mail piece images

    Science.gov (United States)

    Shin, Yong-Chul; Sridhar, Ramalingam; Demjanenko, Victor; Palumbo, Paul W.; Hull, Jonathan J.

    1992-08-01

    A New approach to contrast enhancement of mail piece images is presented. The contrast enhancement is used as a preprocessing step in the real-time address block location (RT-ABL) system. The RT-ABL system processes a stream of mail piece images and locates destination address blocks. Most of the mail pieces (classified into letters) show high contrast between background and foreground. As an extreme case, however, the seasonal greeting cards usually use colored envelopes which results in reduced contrast osured by an error rate by using a linear distributed associative memory (DAM). The DAM is trained to recognize the spectra of three classes of images: with high, medium, and low OCR error rates. The DAM is not forced to make a classification every time. It is allowed to reject as unknown a spectrum presented that does not closely resemble any that has been stored in the DAM. The DAM was fairly accurate with noisy images but conservative (i.e., rejected several text images as unknowns) when there was little ground and foreground degradations without affecting the nondegraded images. This approach provides local enhancement which adapts to local features. In order to simplify the computation of A and (sigma) , dynamic programming technique is used. Implementation details, performance, and the results on test images are presented in this paper.

  16. Two new contrast media in coronary angiography

    International Nuclear Information System (INIS)

    Selin, K.; Bjoerk, L.

    1983-01-01

    Amipaque, ioxaglic acid and Isopaque Coronar 300 were compared in a double blind investigation of coronary angiography in patients with ischemic heart disease. Amipaque affected systolic blood pressure and ECG less than the other contrast media. Ioxaglic acid appeared to give more ST and T changes than Isopaque Coronar. (Auth.)

  17. Generalised phase contrast: microscopy, manipulation and more

    DEFF Research Database (Denmark)

    Palima, Darwin; Glückstad, Jesper

    2010-01-01

    Generalised phase contrast (GPC) not only leads to more accurate phase imaging beyond thin biological samples, but serves as an enabling framework in developing tools over a wide spectrum of contemporary applications in optics and photonics, including optical trapping and micromanipulation, optic...

  18. Advanced detection strategies for ultrasound contrast agents

    NARCIS (Netherlands)

    J.M.G. Borsboom (Jerome)

    2005-01-01

    markdownabstract__Abstract__ Ultrasound contrast agent was discovered serendipitously by Gramiak and Shah in I968 when they injected indocyanine green dye into the heart and observed increased echogenicity of the blood containing the dye. Small cavitation bubbles that were formed upon

  19. Nonspherical oscilllations of ultrasound contrast agent microbubbles

    NARCIS (Netherlands)

    Dollet, B.; van der Meer, S.M.; Garbin, V.; Garbin, Valeria; de Jong, N.; Lohse, Detlef; Versluis, Michel

    2008-01-01

    The occurrence of nonspherical oscillations (or surface modes) of coated microbubbles, used as ultrasound contrast agents in medical imaging, is investigated using ultra–high-speed optical imaging. Optical tweezers designed to micromanipulate single bubbles in 3-D are used to trap the bubbles far

  20. Homogenization of High-Contrast Brinkman Flows

    KAUST Repository

    Brown, Donald L.

    2015-04-16

    Modeling porous flow in complex media is a challenging problem. Not only is the problem inherently multiscale but, due to high contrast in permeability values, flow velocities may differ greatly throughout the medium. To avoid complicated interface conditions, the Brinkman model is often used for such flows [O. Iliev, R. Lazarov, and J. Willems, Multiscale Model. Simul., 9 (2011), pp. 1350--1372]. Instead of permeability variations and contrast being contained in the geometric media structure, this information is contained in a highly varying and high-contrast coefficient. In this work, we present two main contributions. First, we develop a novel homogenization procedure for the high-contrast Brinkman equations by constructing correctors and carefully estimating the residuals. Understanding the relationship between scales and contrast values is critical to obtaining useful estimates. Therefore, standard convergence-based homogenization techniques [G. A. Chechkin, A. L. Piatniski, and A. S. Shamev, Homogenization: Methods and Applications, Transl. Math. Monogr. 234, American Mathematical Society, Providence, RI, 2007, G. Allaire, SIAM J. Math. Anal., 23 (1992), pp. 1482--1518], although a powerful tool, are not applicable here. Our second point is that the Brinkman equations, in certain scaling regimes, are invariant under homogenization. Unlike in the case of Stokes-to-Darcy homogenization [D. Brown, P. Popov, and Y. Efendiev, GEM Int. J. Geomath., 2 (2011), pp. 281--305, E. Marusic-Paloka and A. Mikelic, Boll. Un. Mat. Ital. A (7), 10 (1996), pp. 661--671], the results presented here under certain velocity regimes yield a Brinkman-to-Brinkman upscaling that allows using a single software platform to compute on both microscales and macroscales. In this paper, we discuss the homogenized Brinkman equations. We derive auxiliary cell problems to build correctors and calculate effective coefficients for certain velocity regimes. Due to the boundary effects, we construct

  1. Epinephrine inhanced double contrast knee arthrography

    International Nuclear Information System (INIS)

    Lee, Jae Mun; Choi, Byung Ihn

    1981-01-01

    It is well known that double contrast knee arthrography is useful in diagnosis of meniscal lesions and other knee pathology. But intra-articular structures become less well delineated shortly after injection into the knee joint with water soluble contrast media because of rapid absorption and dilution of the injected media. This limits the time when sharply detailed arthrograms are obtainable and precludes repeat delayed arthrogram without reinjection of contrast media. In order to overcome this major disadvantage, the authors used epinephrine which has vasoconstrictive effect and is expected to reduce fluid movement across the synovial membrane temporarily. The authors attempted to compare epinephrine inhanced double contrast arthrographic group, epinephrine(+) group, to the double contrast arthrographic group without epinephrine, epinephrine(-) group, by statistical evaluation. Each group consisted of 35 cases and 7 lateral films of knee joint were taken sequentially 2, 6, 10, 15, 20, 30, and 60 minutes after injection of contrast media, and were assessed by 5 certified radiologists. The results were as follows: 1. The difference of mean score of quality between epinephrine(+) group and epinephrine(-) group was statistically significant at every time interval (ρ value < 0.01 at 2 minutes, ρ < 0.001 at all other time intervals). Epinephrine(+) group was superior to the epinephrine(-) group in quality of film. 2. Numbers of cases above score of 2 which was considered to be of diagnostic quality in evaluating meniscal lesions were larger in epinephrine(+) group than epinephrine(-) group at every time interval. And the difference between two groups was highly significant statistically (ρ < 0.001). 3. Only 43% of cases was above score of 2 at 10 minutes in epinephrine(-) group, but 97% at 10 minutes and 80% at 20 minutes respectively in epinephrine(+) group. Therefore duration for adequate study of arthrogram is prolonged more than two times in epinephrine(+) group

  2. Comparison of neutral oral contrast versus positive oral contrast medium in abdominal multidetector CT

    International Nuclear Information System (INIS)

    Berther, Ralph; Eckhardt, Boris; Zollikofer, Christoph L.; Patak, Michael A.; Erturk, Sukru M.

    2008-01-01

    To determine whether neutral contrast agents with water-equivalent intraluminal attenuation can improve delineation of the bowel wall and increase overall image quality for a non-selected patient population, a neutral oral contrast agent (3% mannitol) was administered to 100 patients referred for abdominal multidetector row computed tomography (MDCT). Their results were compared with those of 100 patients given a positive oral contrast agent. Qualitative and quantitative measurements were done on different levels of the gastrointestinal tract by three experienced readers. Patients given the neutral oral contrast agent showed significant better qualitative results for bowel distension (P<0.001), homogeneity of the luminal content (P<0.001), delineation of the bowel-wall to the lumen (P<0.001) and to the mesentery (P<0.001) and artifacts (P<0.001), leading to a significant better overall image quality (P<0.001) than patients receiving positive oral contrast medium. The quantitative measurements revealed significant better distension (P<0.001) and wall to lumen delineation (P<0.001) for the patients receiving neutral oral contrast medium. The present results show that the neutral oral contrast agent (mannitol) produced better distension, better homogeneity and better delineation of the bowel wall leading to a higher overall image quality than the positive oral contrast medium in a non-selected patient population. (orig.)

  3. Dynamic Contrast-Enhanced Magnetic Resonance Enterography and Dynamic Contrast-Enhanced Ultrasonography in Crohn's Disease

    DEFF Research Database (Denmark)

    Wilkens, Rune; Peters, David A; Nielsen, Agnete Hedemann

    2017-01-01

    Purpose e Cross-sectional imaging methods are important for objective evaluationof small intestinal inflammationinCrohn'sdisease(CD).The primary aim was to compare relative parameters of intestinal perfusion between contrast-enhanced ultrasonography (CEUS) and dynamic contrast-enhanced magnetic...

  4. Contrast enhancement by lipid-based MRI contrast agents in mouse atherosclerotic plaques; a longitudinal study

    NARCIS (Netherlands)

    den Adel, Brigit; van der Graaf, Linda M.; Que, Ivo; Strijkers, Gustav J.; Löwik, Clemens W.; Poelmann, Robert E.; van der Weerd, Louise

    2013-01-01

    The use of contrast-enhanced MRI to enable in vivo specific characterization of atherosclerotic plaques is increasing. In this study the intrinsic ability of two differently sized gadolinium-based contrast agents to enhance atherosclerotic plaques in ApoE(-/-) mice was evaluated with MRI. We

  5. Radionuclide ventriculography during rest and exercise: normal values

    International Nuclear Information System (INIS)

    Ludwig, E.B.; Marroni, B.J.; Achutti, A.C.; Anselmi, O.E.; Rabin, M.

    1983-01-01

    Twenty young volunteers of both sexes were examined by radioisotopic techniques to establish the normal range of ventricular function at rest and the response to a stress test (systolic arterious pressure X cardiac frequency > 25000). (M.A.C.) [pt

  6. Iodinated contrast media and contrast-induced nephropathy: is there a preferred cost-effective agent?

    Science.gov (United States)

    Sharma, Samin K

    2008-05-01

    Over 20 years have passed since the introduction of the tri-iodinated low-osmolar nonionic contrast agents such as iopamidol, iohexol, ioversol and iopromide. During this time, most cardiology practices have switched to these nonionic agents to avoid the nuisance side effects and cardiac adverse events associated with the older ionic contrast agents. Although the improved tolerability of the nonionic agents is generally attributed to their decreased osmolality (approximately half that of the older ionic contrast agents), in fact, these contrast agents also differ from the older agents in their ionicity, viscosity and direct chemotoxicity. The impact of these properties on safety, together with cost differences, should be considered when selecting a contrast agent.

  7. Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner

    International Nuclear Information System (INIS)

    Müller, Mark; Yaroshenko, Andre; Velroyen, Astrid; Tapfer, Arne; Bech, Martin; Pauwels, Bart; Bruyndonckx, Peter; Sasov, Alexander; Pfeiffer, Franz

    2015-01-01

    In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed

  8. Reduced-Contrast Approximations for High-Contrast Multiscale Flow Problems

    KAUST Repository

    Chung, Eric T.; Efendiev, Yalchin

    2010-01-01

    In this paper, we study multiscale methods for high-contrast elliptic problems where the media properties change dramatically. The disparity in the media properties (also referred to as high contrast in the paper) introduces an additional scale that needs to be resolved in multiscale simulations. First, we present a construction that uses an integral equation to represent the highcontrast component of the solution. This representation involves solving an integral equation along the interface where the coefficients are discontinuous. The integral representation suggests some multiscale approaches that are discussed in the paper. One of these approaches entails the use of interface functions in addition to multiscale basis functions representing the heterogeneities without high contrast. In this paper, we propose an approximation for the solution of the integral equation using the interface problems in reduced-contrast media. Reduced-contrast media are obtained by lowering the variance of the coefficients. We also propose a similar approach for the solution of the elliptic equation without using an integral representation. This approach is simpler to use in the computations because it does not involve setting up integral equations. The main idea of this approach is to approximate the solution of the high-contrast problem by the solutions of the problems formulated in reduced-contrast media. In this approach, a rapidly converging sequence is proposed where only problems with lower contrast are solved. It was shown that this sequence possesses the convergence rate that is inversely proportional to the reduced contrast. This approximation allows choosing the reduced-contrast problem based on the coarse-mesh size as discussed in this paper. We present a simple application of this approach to homogenization of elliptic equations with high-contrast coefficients. The presented approaches are limited to the cases where there are sharp changes in the contrast (i.e., the high

  9. Caldera resurgence driven by magma viscosity contrasts.

    Science.gov (United States)

    Galetto, Federico; Acocella, Valerio; Caricchi, Luca

    2017-11-24

    Calderas are impressive volcanic depressions commonly produced by major eruptions. Equally impressive is the uplift of the caldera floor that may follow, dubbed caldera resurgence, resulting from magma accumulation and accompanied by minor eruptions. Why magma accumulates, driving resurgence instead of feeding large eruptions, is one of the least understood processes in volcanology. Here we use thermal and experimental models to define the conditions promoting resurgence. Thermal modelling suggests that a magma reservoir develops a growing transition zone with relatively low viscosity contrast with respect to any newly injected magma. Experiments show that this viscosity contrast provides a rheological barrier, impeding the propagation through dikes of the new injected magma, which stagnates and promotes resurgence. In explaining resurgence and its related features, we provide the theoretical background to account for the transition from magma eruption to accumulation, which is essential not only to develop resurgence, but also large magma reservoirs.

  10. Neurotoxicity of iodinated radiological contrast media

    International Nuclear Information System (INIS)

    Araujo Pinheiro, R.S. de

    1988-01-01

    We studied during the last ten years the neurotoxicity of artificial iodinated contrast media, with prospective clinical and experimental protocols. The experimental investigation in animals aimed to understand the relationship between the intracarotid injection, the subarachnoid application and the integrity of the blood-brain barrier function. The electro physiologic disturbances and the morphologic observation of pial circulation support the evidence that iodinated artificial contrast media induces significant alterations in brain metabolism and in the autoregulation of the blood flow of the encephalon. Even if many of such phenomena may not be apparent at the clinical level, we supposed that they are always present and that their clinical exteriorization is prevented by the immediate and effective action of homeostatic mechanisms. (author)

  11. Contrast Gain Control Model Fits Masking Data

    Science.gov (United States)

    Watson, Andrew B.; Solomon, Joshua A.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    We studied the fit of a contrast gain control model to data of Foley (JOSA 1994), consisting of thresholds for a Gabor patch masked by gratings of various orientations, or by compounds of two orientations. Our general model includes models of Foley and Teo & Heeger (IEEE 1994). Our specific model used a bank of Gabor filters with octave bandwidths at 8 orientations. Excitatory and inhibitory nonlinearities were power functions with exponents of 2.4 and 2. Inhibitory pooling was broad in orientation, but narrow in spatial frequency and space. Minkowski pooling used an exponent of 4. All of the data for observer KMF were well fit by the model. We have developed a contrast gain control model that fits masking data. Unlike Foley's, our model accepts images as inputs. Unlike Teo & Heeger's, our model did not require multiple channels for different dynamic ranges.

  12. Dual-energy contrast-enhanced mammography.

    Science.gov (United States)

    Travieso Aja, M M; Rodríguez Rodríguez, M; Alayón Hernández, S; Vega Benítez, V; Luzardo, O P

    2014-01-01

    The degree of vascularization in breast lesions is related to their malignancy. For this reason, functional diagnostic imaging techniques have become important in recent years. Dual-energy contrast-enhanced mammography is a new, apparently promising technique in breast cancer that provides information about the degree of vascularization of the lesion in addition to the morphological information provided by conventional mammography. This article describes the state of the art for dual-energy contrast-enhanced mammography. Based on 15 months' clinical experience, we illustrate this review with clinical cases that allow us to discuss the advantages and limitations of this technique. Copyright © 2014 SERAM. Published by Elsevier Espana. All rights reserved.

  13. Contrast MR imaging of acute cerebral infarction

    Energy Technology Data Exchange (ETDEWEB)

    Kogame, Saeko; Syakudo, Miyuki; Inoue, Yuichi (Osaka City Univ. (Japan). Faculty of Medicine) (and others)

    1992-04-01

    Thirty patients with acute and subacute cerebral infarction (13 and 17 deep cerebral infarction) were studied with 0.5 T MR unit before and after intravenous injection of Gd-DTPA. Thirteen patients were studied within 7 days after neurological ictus, 17 patients were studied between 7 and 14 days. Two types of abnormal enhancement, cortical arterial and parenchymal enhancement, were noted. The former was seen in 3 of 4 cases of very acute cortical infarction within 4 days after clinical ictus. The latter was detected in all 7 cases of cortical infarction after the 6th day of the ictus, and one patient with deep cerebral infarction at the 12th day of the ictus. Gd-DTPA enhanced MR imaging seems to detect gyral enhancement earlier compared with contrast CT, and depict intra-arterial sluggish flow which was not expected to see on contrast CT scans. (author).

  14. Slovene-English Contrastive Phraseology: Lexical Collocations

    Directory of Open Access Journals (Sweden)

    Primož Jurko

    2010-05-01

    Full Text Available Phraseology is seen as one of the key elements and arguably the most productive part of any language. %e paper is focused on collocations and separates them from other phraseological units, such as idioms or compounds. Highlighting the difference between a monolingual and a bilingual (i.e. contrastive approach to collocation, the article presents two distinct classes of collocations: grammatical and lexical. %e latter, treated contrastively, represent the focal point of the paper, since they are an unending source of translation errors to both students of translation and professional translators. %e author introduces a methodology of systematic classification of lexical collocations applied on the Slovene-English language pair and based on structural (lexical congruence and semantic (translational predictability criteria.

  15. Enhanced renal image contrast by ethanol fixation in phase-contrast X-ray computed tomography.

    Science.gov (United States)

    Shirai, Ryota; Kunii, Takuya; Yoneyama, Akio; Ooizumi, Takahito; Maruyama, Hiroko; Lwin, Thet Thet; Hyodo, Kazuyuki; Takeda, Tohoru

    2014-07-01

    Phase-contrast X-ray imaging using a crystal X-ray interferometer can depict the fine structures of biological objects without the use of a contrast agent. To obtain higher image contrast, fixation techniques have been examined with 100% ethanol and the commonly used 10% formalin, since ethanol causes increased density differences against background due to its physical properties and greater dehydration of soft tissue. Histological comparison was also performed. A phase-contrast X-ray system was used, fitted with a two-crystal X-ray interferometer at 35 keV X-ray energy. Fine structures, including cortex, tubules in the medulla, and the vessels of ethanol-fixed kidney could be visualized more clearly than that of formalin-fixed tissues. In the optical microscopic images, shrinkage of soft tissue and decreased luminal space were observed in ethanol-fixed kidney; and this change was significantly shown in the cortex and outer stripe of the outer medulla. The ethanol fixation technique enhances image contrast by approximately 2.7-3.2 times in the cortex and the outer stripe of the outer medulla; the effect of shrinkage and the physical effect of ethanol cause an increment of approximately 78% and 22%, respectively. Thus, the ethanol-fixation technique enables the image contrast to be enhanced in phase-contrast X-ray imaging.

  16. Evaluation of contrast media for bronchography

    International Nuclear Information System (INIS)

    Thompson, I.M.; Whittlesey, G.C.; Slovis, T.L.; Chang, C.H.; Cullen, M.L.; Philippart, A.I.; Stockmann, P.S.; Adkins, E.S.; Klein, M.D.

    1997-01-01

    Background. Bronchography is occasionally needed for the evaluation and management of some congenital pulmonary anomalies as well as some acquired diseases, usually of the tracheo- bronchial tree. There is currently no effective, approved contrast agent for this imaging tech- nique. Objective. We evaluated five agents (barium sulfate, iohexol, propyliodone oily, propyliodone aqueous, and perflubron) in terms of image quality, histologic changes, and effects on hemodynamics, blood gases, and standard laboratory tests in New Zealand White rabbits. Materials and methods. Animals were anesthetized and intubated. Each contrast agent (0.25 ml/kg) was administered intratracheally. Three animals in each group had intravenous lines placed for blood sampling and blood pressure monitoring and were sacrificed at 1 h. An additional three animals for each agent were sacrificed at 24 h and 1 week after imaging. Blood samples were taken immediately before contrast instillation and at 1 h postbronchography. Fluoroscopic images were recorded on standard VHS video tape and evaluated in blind fashion. Segments of lung tissue and bronchi were obtained for histologic examination. Results. Necrosis and/or inflammatory infiltrates were noted in 78 % of the bronchograms performed with propyliodone aqueous, 67 % with propyliodone oily, 55 % with perflubron, and 33 % with iohexol 120, 240 and 350. No histologic damage was observed with barium. The propyliodones gave the best-quality imaging results and the most histologic changes. Iohexol, in any concentration, gave the least acceptable images and a moderate number of histologic changes. Barium sulfate demonstrated acceptable images with virtually no histologic changes. Conclusion. From the histologic and imaging results, barium is the best available contrast material for bronchography. (orig.). With 6 figs., 4 tabs

  17. Bare quantifier fronting as contrastive topicalization

    Directory of Open Access Journals (Sweden)

    Ion Giurgea

    2015-11-01

    Full Text Available I argue that indefinites (in particular bare quantifiers such as ‘something’, ‘somebody’, etc. which are neither existentially presupposed nor in the restriction of a quantifier over situations, can undergo topicalization in a number of Romance languages (Catalan, Italian, Romanian, Spanish, but only if the sentence contains “verum” focus, i.e. focus on a high degree of certainty of the sentence. I analyze these indefinites as contrastive topics, using Büring’s (1999 theory (where the term ‘S-topic’ is used for what I call ‘contrastive topic’. I propose that the topic is evaluated in relation to a scalar set including generalized quantifiers such as {lP $x P(x, lP MANYx P(x, lP MOSTx P(x, lP “xP(x} or {lP $xP(x, lP P(a, lP P(b …}, and that the contrastive topic is the weakest generalized quantifier in this set. The verum focus, which is part of the “comment” that co-occurs with the “Topic”, introduces a set of alternatives including degrees of certainty of the assertion. The speaker asserts that his claim is certainly true or highly probable, contrasting it with stronger claims for which the degree of probability is unknown. This explains the observation that in downward entailing contexts, the fronted quantified DPs are headed by ‘all’ or ‘many’, whereas ‘some’, small numbers or ‘at least n’ appear in upward entailing contexts. Unlike other cases of non-specific topics, which are property topics, these are quantifier topics: the topic part is a generalized quantifier, the comment is a property of generalized quantifiers. This explains the narrow scope of the fronted quantified DP.

  18. Double contrast arthrography of the shoulder

    International Nuclear Information System (INIS)

    Gasparini, D.

    1991-01-01

    From 1980 to 1989 the author performed 481 double-contrast arthrographic examinations of the shoulder (DCSA). A hundred and forty-two complete and 46 partial rotator cuff tears were demonstrated; 68 of them underwent surgical exploration. Results confirmed DCSA capabilities in detecting both their location (100%) and size (95%). Moreover, thickness (89%) and erosions (94%) in tendon edges and surfaces were demonstrated - that is, all the qualitative information needed to depict degenerative processes. Such evidence may also affect treatment planning

  19. Iodinated contrast agent-induced nephropathy

    International Nuclear Information System (INIS)

    Erley, C.

    2007-01-01

    Contrast-induced nephropathy (CIN) is a well-known complication of therapeutic and diagnostic procedures requiring contrast administration and accounts for 10% of acute renal failure in hospitalized patients. Although the incidence of this complication is relatively low, its consequences can be catastrophic. The development of CIN is associated with increased length of hospital stay, an increased requirement for acute dialysis, and an increased risk of death. Preexisting renal dysfunction, age, diabetes, congestive heart failure, and volume of administered contrast are all associated with a risk of developing CIN. Despite a large number of clinical trials that have evaluated prophylaxis strategies for CIN, no uniform strategies have been developed so far. The use of N-acetyl-L-cysteine (NAC) or theophylline in specific subgroups of patients has been shown to reduce dialysis requirement and mortality in patients undergoing angiographic procedures. Hemofiltration has also shown positive results. In this review we will discuss the epidemiology and the risk factors for CIN and the evidence for commonly employed prophylaxis strategies, and we will provide general recommendations with respect to CIN prevention and management. A practicable strategy to prevent CIN includes: correct identification of individuals at greatest risk, thorough evaluation of whether other diagnostic maneuvers could be employed instead (i.e., sonography), application of low-osmolar contrast media at the minimum acceptable dose, stopping potential nephrotoxic drugs (NSAID), hydration with sodium chloride 0.9% 1 ml/kg per h i.v. 12 h before and after CM application, administration of acetylcysteine 600 mg twice the day before and after (in cases of emergency investigation and high-risk patients 1200 mg i.v.), and theophylline (250-350 mg) the day before and the day after CM application (in cases of emergency investigation 5 mg/kg i.v.). (orig.) [de

  20. Contrast media properties in interventional radiology

    International Nuclear Information System (INIS)

    Laerum, F.; Enge, I.

    1989-01-01

    Potential hazards of the use of contrast media (CM) in interventional radiology are analyzed by looking into each procedure regarding interactions of CM with pharmaceutical additives, with technical equipment possibly affecting CM stability, and special local or systemic demands related to the procedure. Also the impact of these factors upon the physiological mechanisms are taken into account. (H.W.). 32 refs.; 4 figs.; 2 tabs

  1. High contrast laser marking of alumina

    International Nuclear Information System (INIS)

    Penide, J.; Quintero, F.; Riveiro, A.; Fernández, A.; Val, J. del; Comesaña, R.; Lusquiños, F.; Pou, J.

    2015-01-01

    Highlights: • Laser marking of alumina using near infrared (NIR) lasers was experimentally analyzed. • Color change produced by NIR lasers is due to thermally induced oxygen vacancies. • Laser marking results obtained using NIR lasers and green laser are compared. • High contrast marks on alumina were achieved. - Abstract: Alumina serves as raw material for a broad range of advanced ceramic products. These elements should usually be identified by some characters or symbols printed directly on them. In this sense, laser marking is an efficient, reliable and widely implemented process in industry. However, laser marking of alumina still leads to poor results since the process is not able to produce a dark mark, yielding bad contrast. In this paper, we present an experimental study on the process of marking alumina by three different lasers working in two wavelengths: 1064 nm (Near-infrared) and 532 nm (visible, green radiation). A colorimetric analysis has been carried out in order to compare the resulting marks and its contrast. The most suitable laser operating conditions were also defined and are reported here. Moreover, the physical process of marking by NIR lasers is discussed in detail. Field Emission Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy were also employed to analyze the results. Finally, we propose an explanation for the differences of the coloration induced under different atmospheres and laser parameters. We concluded that the atmosphere is the key parameter, being the inert one the best choice to produce the darkest marks

  2. High contrast computed tomography with synchrotron radiation

    Science.gov (United States)

    Itai, Yuji; Takeda, Tohoru; Akatsuka, Takao; Maeda, Tomokazu; Hyodo, Kazuyuki; Uchida, Akira; Yuasa, Tetsuya; Kazama, Masahiro; Wu, Jin; Ando, Masami

    1995-02-01

    This article describes a new monochromatic x-ray CT system using synchrotron radiation with applications in biomedical diagnosis which is currently under development. The system is designed to provide clear images and to detect contrast materials at low concentration for the quantitative functional evaluation of organs in correspondence with their anatomical structures. In this system, with x-ray energy changing from 30 to 52 keV, images can be obtained to detect various contrast materials (iodine, barium, and gadolinium), and K-edge energy subtraction is applied. Herein, the features of the new system designed to enhance the advantages of SR are reported. With the introduction of a double-crystal monochromator, the high-order x-ray contamination is eliminated. The newly designed CCD detector with a wide dynamic range of 60 000:1 has a spatial resolution of 200 μm. The resulting image quality, which is expected to show improved contrast and spatial resolution, is currently under investigation.

  3. V1 mechanisms underlying chromatic contrast detection

    Science.gov (United States)

    Hass, Charles A.

    2013-01-01

    To elucidate the cortical mechanisms of color vision, we recorded from individual primary visual cortex (V1) neurons in macaque monkeys performing a chromatic detection task. Roughly 30% of the neurons that we encountered were unresponsive at the monkeys' psychophysical detection threshold (PT). The other 70% were responsive at threshold but on average, were slightly less sensitive than the monkey. For these neurons, the relationship between neurometric threshold (NT) and PT was consistent across the four isoluminant color directions tested. A corollary of this result is that NTs were roughly four times lower for stimuli that modulated the long- and middle-wavelength sensitive cones out of phase. Nearly one-half of the neurons that responded to chromatic stimuli at the monkeys' detection threshold also responded to high-contrast luminance modulations, suggesting a role for neurons that are jointly tuned to color and luminance in chromatic detection. Analysis of neuronal contrast-response functions and signal-to-noise ratios yielded no evidence for a special set of “cardinal color directions,” for which V1 neurons are particularly sensitive. We conclude that at detection threshold—as shown previously with high-contrast stimuli—V1 neurons are tuned for a diverse set of color directions and do not segregate naturally into red–green and blue–yellow categories. PMID:23446689

  4. Contrast bolus technique with rapid CT scanning

    International Nuclear Information System (INIS)

    Arnold, H.; Kuehne, D.; Rohr, W.; Heller, M.

    1981-01-01

    Twenty-three patients complying with the clinical criteria for brain death were studied by contrast-enhanced CT. In all but one, the great intracranial vessels escaped visualization; accordingly, angiography demonstrated cerebral circulatory arrest. In the remaining case, faint enhancement of the circle of Willis corresponded to angiographic demonstration of the proximal segments of cerebral arteris. Neither in normal brain nor in dead brain did slow CT scanning disclose any postcontrast increase in parenchymal attenuation. An improved technique is proposed to demonstrate the transit of the contrast bolus by rapid CT with image splitting. If cerebral blood flow is preserved, the grey and white matter will enhance significantly following administration of contrast medium. Vice versa, the absence of enhancement confirms brain death, even in instances in which the great cerebral vessels are obscured by hemorrhage or other extensive lesions. Two additional cases of brain death were evaluated by rapid CT scanning. As to brain death, the technique obviates the need for angiography or radionuclide angiography, usually applied in prospective organ donors, because its informative content is superior to that of either method. The CT technique described affords a reliable and safe diagnosis of brain death, and can be interpreted easily. (orig.)

  5. Nephrotoxicity of cyclosporin A and contrast media

    International Nuclear Information System (INIS)

    Thomsen, H.S.; Larsen, S.; Skaarup, P.; Hemmingsen, L.; Dieperink, H.; Golman, K.; Herlev Hospital; Herlev Hospital; Centralsygehuset, Nykoebing Falster; Odense Sygehus; Malmoe Allmaenna Sjukhus

    1989-01-01

    Urine profiles (albumin, glucose, NAG, LDH, GGT and sodium) were followed for 22 h or 8 days after intravenous injection of diatrizoate, iohexol or saline in 30 adult Wistar rats in which nephrotoxicity was induced by daily peroral administration of 25 mg/kg body weight cyclosporin A over a 14-day period. Another 10 rats which had the vehicle of the cyclosporin A solution (placebo) and saline injected intravenously served as controls. The effect of iohexol and saline on the albumin excretion was similar, whereas diatrizoate increased it significantly. Both contrast media caused significantly increased excretion of all three enzymes. The contrast media had no effect on the excretion of glucose and sodium. Except for the fact that the excretion of NAG was significantly higher following iohexol than following diatrizoate 24 to 46 h after injection no significant differences between the two media were found from 24 h after injection among the rats given cyclosporin A. No contrast medium related changes were found by light microscopy of the kidneys. Neither iohexol nor diatrizoate potentiate acute cyclosporin A nephrotoxicity. (orig.)

  6. Radiologic findings of double contrast knee arthrography

    International Nuclear Information System (INIS)

    Choi, Hye Ran; Ahn, Byeong Yeob; Kim, Mi Young; Lee, So Hyun; Suh, Chang Hae; Chung, Won Kyun

    1990-01-01

    The double contrast arthrography of the knee is a highly accurate diagnostic modality in wide rage of the clinical disorders of the knee. It allows radiological assessment of the menisci, the articular cartilages, the synovium and the ligaments. The double contrast knee arthrography was performed in 356 cases at Inha hospital for about 3 years from June 1986 to June 1989. Among them, 115 cases were abnormal, and were analyzed clinically and radiologically with the back ground of the operative finding. The results were as follows ; 1. Of the 115 cases, male were 77 and female 38. Male exceeds female in the ratio of 2 : 1. 2. The age group of 20 - 39 years was commonly involved (60%). 3. The right knee was more commonly involved than the left and the medial meniscus tear was more common (61%). The posterior horn of the meniscus was more frequently torn than the other parts of the meniscus (42%). 4. The incidence of the bucket-handle tear was the most frequent (33%). 5. The cases of the popliteal cyst were 16 (13.9%), and the combined meniscus tears were in 4 cases (25%). 6. The numbers of the discoid meniscus were 9 (7.8%), and all were present in the lateral meniscus, and combined tears were in 4 cases (44.4%). 7. The diagnostic accuracy of the double contrast knee arthrogram was 82.7% compared with operative finding. The false positive examination were 17.3%

  7. Choice and technique of negative contrast in double contrast roentgenography of the stomach

    International Nuclear Information System (INIS)

    Pomakov, P.; Tomov, A.; Popsavov, P.; Tirolska, M.

    1993-01-01

    A comparative study of 8 negative contrast media is performed in 720 patients undergoing double-contrast abdominal biomedical radiography. The following preparations and methods are compared: Unibarit (Roelm, Pharma), CO 2 granulate (Nicholas), Sandosten Calcium + Calcium gluconicum (Sandoz, Pharmachim), Kalinor (Nordmark), dust variation of p. Rivieri, conducted aerophagy, stomach-tube, 'Echo'-lemonade. The average size of the gas bubble of the fornix (cm 2 ), the average volume of the gas collection (ml) and the relationship between the area of the negative contrast image (cm 2 ) and the volume of the gas (ml) is given. Some possibilities for production of domestic negative contrast media are also discussed. 2 tabs., 18 refs. (orig.)

  8. Spectral triangulation molecular contrast optical coherence tomography with indocyanine green as the contrast agent

    OpenAIRE

    Yang, Changhuei; McGuckin, Laura E. L.; Simon, John D.; Choma, Michael A.; Applegate, Brian E.; Izatt, Joseph A.

    2004-01-01

    We report a new molecular contrast optical coherence tomography (MCOCT) implementation that profiles the contrast agent distribution in a sample by measuring the agent's spectral differential absorption. The method, spectra triangulation MCOCT, can effectively suppress contributions from spectrally dependent scatterings from the sample without a priori knowledge of the scattering properties. We demonstrate molecular imaging with this new MCOCT modality by mapping the distribution of indocyani...

  9. Comparative study of pneumocystography, positive contrast cystography and double contrast cystography in dogs

    International Nuclear Information System (INIS)

    Thibaut, J.; Parada, E.; Vargas, L.; Deppe, R.; Born, R.

    1997-01-01

    In order to compare three radiographic techniques: pneumocystography, positive contrast cystography and double contrast cystography, three series of 24 radiographs each in lateral and ventrodorsal projections were made. Six healthy adult male dogs with weight ranging between 7 and 16 kg were used. Food was withheld for 24 hours and two enemas were made before the series of radiographs were taken. Dogs were anaesthetized with sodium thiopental (20 mg/kg i.v.). The contrast medium was introduced through a urethral catheter. Pneumocystography was performed in the first series introducing air (10 ml/kg) in the bladder. Positive contrast cystography was performed in the second series introducing Hypaque M-60% diluted, contributing 100 mg of iodine per ml (10 ml/kg). In the double contrast cystography Hypaque M-60% diluted (10 ml) was introduced, in concentration of 150 mg of iodine per ml. Then air was introduced (10 ml/kg) through a catheter. Plates were taken in both projections at 1 and 10 minutes for each technique. The radiographic plates of each series were analized comparing the characteristics of radiographic density, outline and size. In neumocystography, positive contrast and double contrast cystography, the radiographic density was predominantly low, high and intermediate, respectively. The radiographic outline was mainly regular for the three techniques. With respect to bladder size, there was a decrease of height and an increase of length and width at 10 minutes. Comparing these three radiographic techniques, it can be concluded that the one that best outlines the bladder mucosa is double contrast. Pneumocystography provides the best image for opaque structures and cystography best shows the position of the urinary bladder [es

  10. The contrasting roles of inflammasomes in cancer

    Science.gov (United States)

    He, Qin; Fu, Yu; Tian, Dean; Yan, Wei

    2018-01-01

    Chronic inflammation plays a decisive role at different stages of cancer development. Inflammasomes are oligomeric protein complexes activated in response to pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). PAMPs and DAMPs are released from infected cells, tumors and damaged tissues. Inflammasomes activate and release inflammatory cytokines such as IL-1β and IL-18. The various inflammasomes and inflammatory cytokines and chemokines play contrasting roles in cancer development and progression. In this review, we describe the roles of different inflammasomes in lung, breast, gastric, liver, colon, and prostate cancers and in glioblastomas.

  11. Molecular imaging with targeted contrast ultrasound.

    Science.gov (United States)

    Piedra, Mark; Allroggen, Achim; Lindner, Jonathan R

    2009-01-01

    Molecular imaging with contrast-enhanced ultrasound uses targeted microbubbles that are retained in diseased tissue. The resonant properties of these microbubbles produce acoustic signals in an ultrasound field. The microbubbles are targeted to diseased tissue by using certain chemical constituents in the microbubble shell or by attaching disease-specific ligands such as antibodies to the microbubble. In this review, we discuss the applications of this technique to pathological states in the cerebrovascular system including atherosclerosis, tumor angiogenesis, ischemia, intravascular thrombus, and inflammation. Copyright 2009 S. Karger AG, Basel.

  12. Comparison of the accuracy of three angiographic methods for calculating left ventricular volume measurement

    International Nuclear Information System (INIS)

    Hu Lin; Cui Wei; Shi Hanwen; Tian Yingping; Wang Weigang; Feng Yanguang; Huang Xueyan; Liu Zhisheng

    2003-01-01

    Objective: To compare the relative accuracy of three methods measuring left ventricular volume by X-ray ventriculography: single plane area-length method, biplane area-length method, and single-plane Simpson's method. Methods: Left ventricular casts were obtained within 24 hours after death from 12 persons who died from non-cardiac causes. The true left ventricular cast volume was measured by water displacement. The calculated volume of the casts was obtained with 3 angiographic methods, i.e., single-plane area-length method, biplane area-length method, and single-plane Simpson's method. Results: The actual average volume of left ventricular casts was (61.17±26.49) ml. The left ventricular volume was averagely (97.50±35.56) ml with single plane area-length method, (90.51±36.33) ml with biplane area-length method, and (65.00± 23.63) ml with single-plane Simpson's method. The left ventricular volumes calculated with single-plane and biplane area-length method were significantly larger than that the actual volumes (P 0.05). The left ventricular volumes calculated with single-plane and biplane area-length method were significantly larger than those calculated with single-plane Simpson's method (P 0.05). The over-estimation of left ventricular volume by single plane area-length method (36.34±17.98) ml and biplane area-length method (29.34±15.59) ml was more obvious than that calculated by single-plane Simpson's method (3.83±8.48) ml. Linear regression analysis showed that there was close correlations between left ventricular volumes calculated with single plane area-length method, biplane area-length method, Simpson's method and the true volume (all r>0.98). Conclusion: Single-plane Simpson's method is more accurate than single plane area-length method and biplane area-length method for left ventricular volume measurement; however, both the single-plane and biplane area-length methods could be used in clinical practice, especially in those imaging modality

  13. Contrast enhanced cartilage imaging: Comparison of ionic and non-ionic contrast agents

    International Nuclear Information System (INIS)

    Wiener, Edzard; Woertler, Klaus; Weirich, Gregor; Rummeny, Ernst J.; Settles, Marcus

    2007-01-01

    Our objective was to compare relaxation effects, dynamics and spatial distributions of ionic and non-ionic contrast agents in articular cartilage at concentrations typically used for direct MR arthrography at 1.5 T. Dynamic MR-studies over 11 h were performed in 15 bovine patella specimens. For each of the contrast agents gadopentetate dimeglumine, gadobenate dimeglumine, gadoteridol and mangafodipir trinatrium three patellae were placed in 2.5 mmol/L contrast solution. Simultaneous measurements of T 1 and T 2 were performed every 30 min using a high-spatial-resolution 'MIX'-sequence. T 1 , T 2 and ΔR 1 , ΔR 2 profile plots across cartilage thickness were calculated to demonstrate the spatial and temporal distributions. The charge is one of the main factors which controls the amount of the contrast media diffusing into intact cartilage, but independent of the charge, the spatial distribution across cartilage thickness remains highly inhomogeneous even after 11 h of diffusion. The absolute ΔR 2 -effect in cartilage is at least as large as the ΔR 1 -effect for all contrast agents. Maximum changes were 5-12 s -1 for ΔR 1 and 8-15 s -1 for ΔR 2 . This study indicates that for morphologically intact cartilage only the amount of contrast agents within cartilage is determined by the charge but not the spatial distribution across cartilage thickness. In addition, ΔR 2 can be considered for quantification of contrast agent concentrations, since it is of the same magnitude and less time consuming to measure than ΔR 1

  14. High contrast laser marking of alumina

    Science.gov (United States)

    Penide, J.; Quintero, F.; Riveiro, A.; Fernández, A.; del Val, J.; Comesaña, R.; Lusquiños, F.; Pou, J.

    2015-05-01

    Alumina serves as raw material for a broad range of advanced ceramic products. These elements should usually be identified by some characters or symbols printed directly on them. In this sense, laser marking is an efficient, reliable and widely implemented process in industry. However, laser marking of alumina still leads to poor results since the process is not able to produce a dark mark, yielding bad contrast. In this paper, we present an experimental study on the process of marking alumina by three different lasers working in two wavelengths: 1064 nm (Near-infrared) and 532 nm (visible, green radiation). A colorimetric analysis has been carried out in order to compare the resulting marks and its contrast. The most suitable laser operating conditions were also defined and are reported here. Moreover, the physical process of marking by NIR lasers is discussed in detail. Field Emission Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy were also employed to analyze the results. Finally, we propose an explanation for the differences of the coloration induced under different atmospheres and laser parameters. We concluded that the atmosphere is the key parameter, being the inert one the best choice to produce the darkest marks.

  15. Osteoblastic Metastases Mimickers on Contrast Enhanced CT

    Directory of Open Access Journals (Sweden)

    Fahad Al-Lhedan

    2017-01-01

    Full Text Available Secondary osseous involvement in lymphoma is more common compared to primary bone lymphoma. The finding of osseous lesion can be incidentally discovered during the course of the disease. However, osseous metastases are infrequently silent. Detection of osseous metastases is crucial for accurate staging and optimal treatment planning of lymphoma. The aim of imaging is to identify the presence and extent of osseous disease and to assess for possible complications such as pathological fracture of the load-bearing bones and cord compression if the lesion is spinal. We are presenting two patients with treated lymphoma who were in complete remission. On routine follow-up contrast enhanced CT, there were new osteoblastic lesions in the spine worrisome for metastases. Additional studies were performed for further evaluation of both of them which did not demonstrate any corresponding suspicious osseous lesion. The patients have a prior history of chronic venous occlusive thrombosis that resulted in collaterals formation. Contrast enhancement of the vertebral body marrow secondary to collaterals formation and venous flow through the vertebral venous plexus can mimic the appearance of spinal osteoblastic metastases.

  16. Novel contrast agent for liver and spleen

    International Nuclear Information System (INIS)

    Seltzer, S.E.; Blau, M.; Adams, D.F.; Janoff, A.; Minchey, S.

    1991-01-01

    This paper determines whether the biodistribution and imaging characteristics of a liposome-encapsulated contrast agent, iotrolan-carrying interdigitation fusion (IF) vesicles, were acceptable for a liver-spleen CT contrast agent. IF vesicles with iotrolan in their aqueous phase were prepared by fusing small unilamellar liposomes into larger vesicles. The iodine-to-lipid ratio was 4.7. Biodistribution was measured with I-125 iotrolan-labeled IF vesicles in rats. CT imaging (Somatom Plus, Siemens Medical Systems) was performed in dogs. At the lowest dose (10 mg of iodine and 2.1 mg of lipid per kilogram) 72% of the ID was in the liver, 5% in spleen, and 1% in lungs at 1 hour. At the highest dose, (1,000 mg of iodine and 212 mg of lipid per kilogram), liver values were 68% ID, while spleen rose to 18%, lung 5%. Liver and spleen values stayed at peak for 24 hours then fell; the half-life was 6 days. In dogs, liver and spleen enhancement at 1 hour averaged 652 and 256 HU above baseline per gram of iodine per kilogram, respectively

  17. Magnetic resonance perfusion imaging without contrast media

    International Nuclear Information System (INIS)

    Martirosian, Petros; Graf, Hansjoerg; Schick, Fritz; Boss, Andreas; Schraml, Christina; Schwenzer, Nina F.; Claussen, Claus D.

    2010-01-01

    Principles of magnetic resonance imaging techniques providing perfusion-related contrast weighting without administration of contrast media are reported and analysed systematically. Especially common approaches to arterial spin labelling (ASL) perfusion imaging allowing quantitative assessment of specific perfusion rates are described in detail. The potential of ASL for perfusion imaging was tested in several types of tissue. After a systematic comparison of technical aspects of continuous and pulsed ASL techniques the standard kinetic model and tissue properties of influence to quantitative measurements of perfusion are reported. For the applications demonstrated in this paper a flow-sensitive alternating inversion recovery (FAIR) ASL perfusion preparation approach followed by true fast imaging with steady precession (true FISP) data recording was developed and implemented on whole-body scanners operating at 0.2, 1.5 and 3 T for quantitative perfusion measurement in various types of tissue. ASL imaging provides a non-invasive tool for assessment of tissue perfusion rates in vivo. Images recorded from kidney, lung, brain, salivary gland and thyroid gland provide a spatial resolution of a few millimetres and sufficient signal to noise ratio in perfusion maps after 2-5 min of examination time. Newly developed ASL techniques provide especially high image quality and quantitative perfusion maps in tissues with relatively high perfusion rates (as also present in many tumours). Averaging of acquisitions and image subtraction procedures are mandatory, leading to the necessity of synchronization of data recording to breathing in abdominal and thoracic organs. (orig.)

  18. Adaptive multiscale processing for contrast enhancement

    Science.gov (United States)

    Laine, Andrew F.; Song, Shuwu; Fan, Jian; Huda, Walter; Honeyman, Janice C.; Steinbach, Barbara G.

    1993-07-01

    This paper introduces a novel approach for accomplishing mammographic feature analysis through overcomplete multiresolution representations. We show that efficient representations may be identified from digital mammograms within a continuum of scale space and used to enhance features of importance to mammography. Choosing analyzing functions that are well localized in both space and frequency, results in a powerful methodology for image analysis. We describe methods of contrast enhancement based on two overcomplete (redundant) multiscale representations: (1) Dyadic wavelet transform (2) (phi) -transform. Mammograms are reconstructed from transform coefficients modified at one or more levels by non-linear, logarithmic and constant scale-space weight functions. Multiscale edges identified within distinct levels of transform space provide a local support for enhancement throughout each decomposition. We demonstrate that features extracted from wavelet spaces can provide an adaptive mechanism for accomplishing local contrast enhancement. We suggest that multiscale detection and local enhancement of singularities may be effectively employed for the visualization of breast pathology without excessive noise amplification.

  19. Contrast-induced nephropathy: risks, pathogenetic, prevention

    International Nuclear Information System (INIS)

    Paskalev, D.; Balev, B.

    2006-01-01

    Full text: The aim of the presentation is to review the contrast induced nephropathy ? nature, mechanisms of development, risk factors. Summary of the most important ways of prevention, diagnostics and treatment. The definition of CIN according the European Association of Urogenital Radiology is: 'A condition, in which renal function is impaired (elevation of serum creatinine with more than 25% or 44 μmol/l above the initial level) due to intravasal application of contrast media (CM) within 3 days following the application and when no other etiology factors are present'. We summarize the main risk factors of developing CIN - renal failure, diabetic nephropathy, dehydration, congestive heart failure, high blood pressure, age above 70 yrs, nephrotoxic medicines. The most effective ways of preventing CIN are the good hydratation of the patients and the usage of low-osmolar or iso-osmolar CM. Therapeutic treatment is with no proven preventive effect and currently is not routinely recommended. An early hem dialysis does not decrease the risk level of CIN development in patients with chronic renal failure (CRF). In such patients complete elimination of CM is achieved only after several hem dialyses. Hem filtration reliably decreases the risk of CIN in CRF patients, but is expensive and not widely available. We present a case from our hospital of a patient with diabetic nephropathy, who developed CIN following a coronary angiography

  20. Halftoning for high-contrast imaging

    Directory of Open Access Journals (Sweden)

    Kasper M.

    2011-07-01

    Full Text Available High-contrast instruments, such as SPHERE (upcoming planet finder instrument for the ESO-VLT, or EPICS (planet hunter project for the future E-ELT, will require customized components with spatially varying transmission (e.g. coronagraphs, optical components that reduce the contrast between a companion and its parent star. The goal of these sub-systems is to control the spatial transmission, either in a pupil plane (pupil apodization, or in a focal plane of the instrument (occulting mask, i.e. low-frequency filter. Reliably producing components with spatially varying transmission is not trivial, and different techniques have been already investigated for application to astronomy (e.g. metal deposition with spatially-varying thickness, or high-energy beam sensitive glass using e-beam lithography. We present some results related to the recent development of components with spatially varying transmission using a relatively simple technique analogous to the digital halftoning process used for printing applications.

  1. Quantitative contrast-enhanced optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Winetraub, Yonatan; SoRelle, Elliott D. [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Biophysics Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Liba, Orly [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Zerda, Adam de la [Molecular Imaging Program at Stanford, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Bio-X Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Biophysics Program, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Structural Biology, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, 299 Campus Drive, Stanford, California 94305 (United States)

    2016-01-11

    We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within a voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects.

  2. MRI contrast enhancement using Magnetic Carbon Nanoparticles

    Science.gov (United States)

    Chaudhary, Rakesh P.; Kangasniemi, Kim; Takahashi, Masaya; Mohanty, Samarendra K.; Koymen, Ali R.; Department of Physics, University of Texas at Arlington Team; University of Texas Southwestern Medical Center Team

    2014-03-01

    In recent years, nanotechnology has become one of the most exciting forefront fields in cancer diagnosis and therapeutics such as drug delivery, thermal therapy and detection of cancer. Here, we report development of core (Fe)-shell (carbon) nanoparticles with enhanced magnetic properties for contrast enhancement in MRI imaging. These new classes of magnetic carbon nanoparticles (MCNPs) are synthesized using a bottom-up approach in various organic solvents, using the electric plasma discharge generated in the cavitation field of an ultrasonic horn. Gradient echo MRI images of well-dispersed MCNP-solutions (in tube) were acquired. For T2 measurements, a multi echo spin echo sequence was performed. From the slope of the 1/T2 versus concentration plot, the R2 value for different CMCNP-samples was measured. Since MCNPs were found to be extremely non-reactive, and highly absorbing in NIR regime, development of carbon-based MRI contrast enhancement will allow its simultaneous use in biomedical applications. We aim to localize the MCNPs in targeted tissue regions by external DC magnetic field, followed by MRI imaging and subsequent photothermal therapy.

  3. A new double contrast barium enema

    International Nuclear Information System (INIS)

    Park, Jun Sang; Cho, Won Sik; Lee, Sung Woo; Lee, Mun Gyu; Jeon, Jeong Dong; Jaun, Woo Ki; Han, Chung Yul

    1987-01-01

    A new technic of the barium enema was proposed for the better colonic double contrast study with the average 204ml of 50w/v% barium, applied to 109 serial patients. The barium was introduced to sigmoid colon, and then pushed to a mid transverse colon by the air insufflation through an enema syringe, a new device. An advance to cecum is accomplished by the air insufflation and/or the position change of the patient. The barium transfer method was developed for the best spot film exposure, through colon, by the position change of the patient, the tilting of the x-ray table and the air insufflation with the enema syringe. The mean angle of the x-ray table tilted was -10 .deg. at the beginning the barium enema till the barium sent past the splenic flexure, -15 . deg. for the best lateral view of rectum and -18 .deg. for the bet prone PA view of rectosigmoid colon. This was a simple, better and economic double contrast barium enema for the cooperative patients

  4. Synthesis of Laboratory Ultrasound Contrast Agents

    Directory of Open Access Journals (Sweden)

    Jaemin Oh

    2013-10-01

    Full Text Available Ultrasound Contrast Agents (UCAs were developed to maximize reflection contrast so that organs can be seen clearly in ultrasound imaging. UCAs increase the signal to noise ratio (SNR by linear and non-linear mechanisms and thus help more accurately visualize the internal organs and blood vessels. However, the UCAs on the market are not only expensive, but are also not optimized for use in various therapeutic research applications such as ultrasound-aided drug delivery. The UCAs fabricated in this study utilize conventional lipid and albumin for shell formation and perfluorobutane as the internal gas. The shape and density of the UCA bubbles were verified by optical microscopy and Cryo SEM, and compared to those of the commercially available UCAs, Definity® and Sonovue®. The size distribution and characteristics of the reflected signal were also analyzed using a particle size analyzer and ultrasound imaging equipment. Our experiments indicate that UCAs composed of spherical microbubbles, the majority of which were smaller than 1 um, were successfully synthesized. Microbubbles 10 um or larger were also identified when different shell characteristics and filters were used. These laboratory UCAs can be used for research in both diagnoses and therapies.

  5. Development of organic MRI contrast agents

    International Nuclear Information System (INIS)

    Hayashi, Hiroyuki; Sato, Yuichiro; Karasawa, Satoru; Koga, Noboru

    2008-01-01

    Described are trends of the development in the title since those agents with target properties are awaited for specific organ and regional MRI. The contrast agents alter the relaxation time of water proton to yield the enhanced contrast between organs and tissues with different water volumes. Nowadays Gd-complexes and nano-particle of superparamagnetic iron oxide (Fe(III)) are widely used for enhancing in clinic. Among organic compounds with paramagnetic spin, those possessing nitroxide radical like TEMPO- and PROXYL-radicals have been subject to development by their derivatization. High spin molecules conceivably affect the relaxivity, which, however, is found smaller per spin of synthesized triplet complexes than doublet ones. This has lead to basic approach for molecules restricting water movement due to their hydrogen bond like DNA as a model, for introducing many radicals in high molecular weight compounds, and their polymer, as one of which authors have developed a derivative of hyperbranched polymer (HPS)-TEMPO having the similar relaxivity to gadolinium-diethylenetiamine pentaacetid acid (Gd-DTPA) (R.T.)

  6. The Acquisition of Quantity Contrasts in Guina-ang Bontok

    Science.gov (United States)

    Aoyama, Katsura; Reid, Lawrence A.

    2016-01-01

    This study reports on the acquisition of quantity contrasts in Guina-ang Bontok, an indigenous language spoken in the Philippines. Four-year-old and 5-year-old children's perception and production of quantity contrasts were examined using a pair of names that contrast in the quantity of the medial nasal. Frequencies of the quantity contrast were…

  7. Generalized image contrast enhancement technique based on the Heinemann contrast discrimination model

    Science.gov (United States)

    Liu, Hong; Nodine, Calvin F.

    1996-07-01

    This paper presents a generalized image contrast enhancement technique, which equalizes the perceived brightness distribution based on the Heinemann contrast discrimination model. It is based on the mathematically proven existence of a unique solution to a nonlinear equation, and is formulated with easily tunable parameters. The model uses a two-step log-log representation of luminance contrast between targets and surround in a luminous background setting. The algorithm consists of two nonlinear gray scale mapping functions that have seven parameters, two of which are adjustable Heinemann constants. Another parameter is the background gray level. The remaining four parameters are nonlinear functions of the gray-level distribution of the given image, and can be uniquely determined once the previous three are set. Tests have been carried out to demonstrate the effectiveness of the algorithm for increasing the overall contrast of radiology images. The traditional histogram equalization can be reinterpreted as an image enhancement technique based on the knowledge of human contrast perception. In fact, it is a special case of the proposed algorithm.

  8. Generalized image contrast enhancement technique based on Heinemann contrast discrimination model

    Science.gov (United States)

    Liu, Hong; Nodine, Calvin F.

    1994-03-01

    This paper presents a generalized image contrast enhancement technique which equalizes perceived brightness based on the Heinemann contrast discrimination model. This is a modified algorithm which presents an improvement over the previous study by Mokrane in its mathematically proven existence of a unique solution and in its easily tunable parameterization. The model uses a log-log representation of contrast luminosity between targets and the surround in a fixed luminosity background setting. The algorithm consists of two nonlinear gray-scale mapping functions which have seven parameters, two of which are adjustable Heinemann constants. Another parameter is the background gray level. The remaining four parameters are nonlinear functions of gray scale distribution of the image, and can be uniquely determined once the previous three are given. Tests have been carried out to examine the effectiveness of the algorithm for increasing the overall contrast of images. It can be demonstrated that the generalized algorithm provides better contrast enhancement than histogram equalization. In fact, the histogram equalization technique is a special case of the proposed mapping.

  9. Prolonged retainment of contrast media in renal tumours by oily X-ray contrast media

    International Nuclear Information System (INIS)

    Ryzkov, V.K.; Anisimov, V.N.

    1990-01-01

    In 194 patients with renal tumours an angiographic investigation with the oily X-ray contrast medium Iodolipol was carried out. A selective tropism of oily X-ray contrast media was found in the malignant zones only. The application of the preparation caused no complications. The oily X-ray contrast medium persisted in the tumours over several weeks or months. After embolization of the renal arteria a moderate size reduction of malign tumours in the first 10-14 d was seen. The ability of Iodolipol for a lasting retainment in malign tumour tissue allows a follow-up of the involution of the pathologic focus after arterial embolization of the tumour vessels. (author)

  10. Fast mutual-information-based contrast enhancement

    Science.gov (United States)

    Cao, Gang; Yu, Lifang; Tian, Huawei; Huang, Xianglin; Wang, Yongbin

    2017-07-01

    Recently, T. Celik proposed an effective image contrast enhancement (CE) method based on spatial mutual information and PageRank (SMIRANK). According to the state-of-the-art evaluation criteria, it achieves the best visual enhancement quality among existing global CE methods. However, SMIRANK runs much slower than the other counterparts, such as histogram equalization (HE) and adaptive gamma correction. Low computational complexity is also required for good CE algorithms. In this paper, we novelly propose a fast SMIRANK algorithm, called FastSMIRANK. It integrates both spatial and gray-level downsampling into the generation of pixel value mapping function. Moreover, the computation of rank vectors is speeded up by replacing PageRank with a simple yet efficient row-based operation of mutual information matrix. Extensive experimental results show that the proposed FastSMIRANK could accelerate the processing speed of SMIRANK by about 20 times, and is even faster than HE. Comparable enhancement quality is preserved simultaneously.

  11. Screened Poisson Equation for Image Contrast Enhancement

    Directory of Open Access Journals (Sweden)

    Jean-Michel Morel

    2014-03-01

    Full Text Available In this work we propose a discussion and detailed implementation of a very simple gradient domain method that tries to eliminate the effect of nonuniform illumination and at the same time preserves the images details. This model, which to the best of our knowledge has not been explored in spite of its simplicity, acts as a high pass filter. We show that with a single contrast parameter (which keeps the same value in most experiments, the model delivers state of the art results. They compare favorably to results obtained with more complex algorithms. Our algorithm is designed for all kinds of images, but with the special specification of making minimal image detail alteration thanks to a first order fidelity term, instead of the usual zero order term. Experiments on non-uniform medical images and on hazy images illustrate significant perception gain.

  12. Selective Contrast Adjustment by Poisson Equation

    Directory of Open Access Journals (Sweden)

    Ana-Belen Petro

    2013-09-01

    Full Text Available Poisson Image Editing is a new technique permitting to modify the gradient vector field of an image, and then to recover an image with a gradient approaching this modified gradient field. This amounts to solve a Poisson equation, an operation which can be efficiently performed by Fast Fourier Transform (FFT. This paper describes an algorithm applying this technique, with two different variants. The first variant enhances the contrast by increasing the gradient in the dark regions of the image. This method is well adapted to images with back light or strong shadows, and reveals details in the shadows. The second variant of the same Poisson technique enhances all small gradients in the image, thus also sometimes revealing details and texture.

  13. Contrast media in gall bladder diagnostics

    International Nuclear Information System (INIS)

    Schindler, G.; Frommhold, W.

    1982-01-01

    The justification of conventional X-ray diagnostic of bile ducts is repeatedly questioned by newer examination techniques like sonography and ERC. The indication for oral cholesgraphy is derived from its high-specifity of its statements for gall bladder diagnostic, that is as high as with sonography and does not depend on the experience of the investigator. The importance of the the void exposure is undoubted with correspondence of medicamentary litholysis for calcite identification. Furthermore, Choleocystic kineticals like Ceruletid let recognize better hyper plastic choleocysts like adenomyomatoses. The intravenous choleocyst-cholangiography posesses a clearly limited indication scheme even after introduction of sonography and ERC. The infusion method yields a better compatibility of the contrast medium with a simultaneous increased representation quality of the bile duct, that can be increased by a consequent application of the layer exposure technique. (orig.) [de

  14. CEST and PARACEST MR contrast agents

    International Nuclear Information System (INIS)

    Hancu, Ileana; Dixon, W. Thomas; Woods, Mark; Sherry, A. Dean; Vinogradov, Elena; Lenkinski, Robert E.

    2010-01-01

    In this review we describe the status of development for a new class of magnetic resonance (MR) contrast agents, based on chemical exchange saturation transfer (CEST). The mathematics and physics relevant to the description of the CEST effect in MR are presented in an appendix published in the online version only. We discuss the issues arising when translating in vitro results obtained with CEST agents to using these MR agents in in vivo model studies and in humans. Examples are given on how these agents are imaged in vivo. We summarize the status of development of these CEST agents, and speculate about the next steps that may be taken towards the demonstration of CEST MR imaging in clinical applications

  15. CONTRAST ENHANCED SPECTRAL MAMMOGRAPHY (CESM (REVIEW

    Directory of Open Access Journals (Sweden)

    N. I. Rozhkova

    2015-01-01

    Full Text Available The problem of early diagnosis of a breast cancer is extremely actual. Growth of incidence at women from 19 to 39 years increased for 34% over the last 10 years. It defines need of acceleration of development and deployment of the latest technologies of identification of the earliest symptoms of diseases. The x-ray mammography is the conducting method among of all radiological methods of diagnostics. Nevertheless a number of restrictions of method reduces its efficiency. The technologies increasing informational content of x-ray mammography – the leading method of screening – due to use of artificial contrasting and advantages of digital technologies are constantly developed. In this review it is described works, in which the authors having clinical experience of application of CESM – contrastenhanced spectral mammography on representative group of women. Positive sides and restrictions of new technology in comparison with mammography, ultrasonography and MRT are shown in this article.

  16. Gender Contrasts in Negotiation Impasse Rates

    Directory of Open Access Journals (Sweden)

    Michael J. Cotter

    2017-03-01

    Full Text Available This study contrasts the rate of impasse in genders in face-to-face negotiations for newly trained women and men. The empirical study analyzed negotiators’ negotiation impasse rates based on gender using a two-tailed t-test. The bargainers were involved in a series of ten high-stakes, zero-sum game negotiations. A total of 4,855 separate negotiations were examined. Overall, there were no statistically significant differences in the impasse rates of men and women The female rate of impasse was lower than the male rate of impasse, but without any significant differences, the results indicate that there are no gender differences in the abilities of negotiators to arrive at a deal.

  17. MRI contrast agents from molecules to particles

    CERN Document Server

    Laurent, Sophie; Stanicki, Dimitri; Boutry, Sébastien; Lipani, Estelle; Belaid, Sarah; Muller, Robert N; Vander Elst, Luce

    2017-01-01

    This book describes the multiple aspects of (i) preparation of the magnetic core, (ii) the stabilization with different coatings, (iii) the physico-chemical characterization and (iv) the vectorization to obtain specific nanosystems. Several bio-applications are also presented in this book. In the early days of Magnetic Resonance Imaging (MRI), paramagnetic ions were proposed as contrast agents to enhance the diagnostic quality of MR images. Since then, academic and industrial efforts have been devoted to the development of new and more efficient molecular, supramolecular and nanoparticular systems. Old concepts and theories, like paramagnetic relaxation, were revisited and exploited, leading to new scientific tracks. With their high relaxivity payload, the superparamagnetic nanoparticles are very appealing in the context of molecular imaging but challenges are still numerous: absence of toxicity, specificity, ability to cross the biological barriers, etc. .

  18. Process for preparation of MR contrast agents

    DEFF Research Database (Denmark)

    2002-01-01

    The present invention provides a process for the preparation of an MR contrast agent, said process comprising: i) obtaining a solution in a solvent of a hydrogenatable, unsaturated substrate compound and a catalyst for the hydrogenation of said substrate compound; ii) introducing said solution...... in droplet form into a chamber containing hydrogen gas (H2) enriched in para-hydrogen (p-1H2) and/or ortho-deuterium (o-2H2) whereby to hydrogenate said substrate to form a hydrogenated imaging agent; iii) optionally subjecting said hydrogenated imaging agent to a magnetic field having a field strength below...... earth's ambient field strength; iv) optionally dissolving said imaging agent in an aqueous medium; v) optionally separating said catalyst from the solution of said imaging agent in said aqueous medium; vi) optionally separating said solvent from the solution of said imaging agent in said aqueous medium...

  19. Contrastings views on bullying in Schools

    DEFF Research Database (Denmark)

    Hansen, Helle Rabøl

    Contrasting views on bullying in schools Which views on bullying influence teachers intervention strategies? This question is discussed  on the basis of the findings of my empirical study of that aspect of bullying that has to do with the position of the teacher (a quantitative survey...... of the teachers' staff room, observations, interviews and analysis of explicit ‘bullying-politics'). I found contradictions in teachers' definitions of the phenomenon of bullying, in how they describe causality and furthermore in how they would attempt to solve a specific and complicated bullying case....... The informants describe ‘bullying' in general terms that include group dynamic signs, when pressed for a causal explanation, or asked how they would handle a specific case. Most commonly, however, their focus is on the individual bully. In this, the teachers' positions seem to follow the commonplace conception...

  20. Contrast media and pain during peripheral arteriography

    International Nuclear Information System (INIS)

    Hagen, B.; Clauss, W.

    1982-01-01

    Some contrast media (CM) were for inducing pain and heat by an intraindividual comparison in 60 patients with occlusive peripheral arterial disease. A dolorimeter and calorimeter (graduated scales) were employed to register and differentiate the subjective sensations experienced by the patient, while objective reactions (peripheral motoric reactions, circulatory parameters) were recorded by the trialist at the same time. Ioxaglate, an ionic dimer, was distinctly superior to Ioglicinate, an ionic CM. However, the differences were less marked in the comparison with a Ioglicinate-Lidocaine-mixture. Emphasis is given to the fact osmolality is the most important parameter in the development of pain. Potential points at which the intraarterially administered local anaesthetic could attack are discussed. The clinical conclusions include consideration of the cost-effectivity ratios of the tested CM's and a discussion of whether or not modern stanards still justify general anaesthesia for peripheral angiography. (orig.)

  1. Patterns and contrasts in ophthalmic investigation.

    Science.gov (United States)

    Drasdo, N

    1988-01-01

    The Snellen test has been the most popular clinical measurement of spatial vision for over a century, but it does not fully express the visual ability of an individual. For more analytical purposes the information capacity of the visual system may be assessed by tests of contrast sensitivity and peripheral vision. The visual system selectively reduces the spatial information content of the visual field to avoid overloading the limited capacity for perception and decision making in the brain. The ways in which this reduction occurs and the processing of spatial information is of interest in many disciplines, and theoretical knowledge has been accelerated by the study of artificial intelligence. These processes may be investigated in human subjects by psychophysical and electrophysiological techniques. This provides additional information for diagnostic purposes and will form the basis of new systems of clinical investigation.

  2. Contrasts and synergies in different biofuel reports.

    Science.gov (United States)

    Michalopoulos, A; Landeweerd, L; Van der Werf-Kulichova, Z; Puylaert, P G B; Osseweijer, P

    2011-04-06

    The societal debate on biofuels is characterised by increased complexity. This can hinder the effective governance of the field. This paper attempts a quantitative bird's eye meta-analysis of this complexity by mapping different stakeholder perspectives and expected outcomes as seen in the secondary literature on biofuels, along the lines of the People-Planet-Profit framework. Our analysis illustrates the tension between stated and actual drivers of large scale biofuel development, especially for first generation biofuels. Although environmental (Planet) aspects have dominated the biofuel debate, their overall assessment is mostly negative with regard to first generation biofuels. By contrast, economic (Profit) aspects are the only ones that are assessed positively with regard to first generation biofuels. Furthermore, positive and negative assessments of biofuel development are strongly influenced by the differences in focus between different stakeholder clusters. Stakeholders who appear generally supportive to biofuel development (industry) focus relatively more on aspects that are generally assessed as positive (Profit). By contrast, non-supportive stakeholders (NGO's) tend to focus mainly on aspects that are generally assessed as negative (Planet). Moreover, our analysis of reference lists revealed few citations of primary scientific data, and also that intergovernmental organizations produce the most influential publications in the debate. The surprising lack of listed references to scientific (primary) data reveals a need to assess in which arena the transition of scientific data towards secondary publications takes place, and how one can measure its quality. This work should be understood as a first effort to take some control over a complex and contradictory number of publications, and to allow the effective governance of the field through the identification of areas of overlapping consensus and persisting controversy, without reverting to claims on

  3. Extracellular gadolinium contrast agents: Differences in stability

    International Nuclear Information System (INIS)

    Morcos, S.K.

    2008-01-01

    Extracellular gadolinium contrast agents (Gd-CA) are either linear or macrocyclic chelates available as ionic or non-ionic preparations. The molecular structure whether cyclic or linear and ionicity determines the stability of Gd-CA. Linear chelates are flexible open chains which do not offer a strong binding to Gd 3+ . In contrast, the macrocyclic chelates offer a strong binding to Gd 3+ by the virtue of being preorganized rigid rings of almost optimal size to cage the gadolinium atom. Non-ionic preparations are also less stable in comparison to the ionic ones as the binding between Gd 3+ with the negatively charged carboxyl groups is stronger in comparison to that with amides or alcohol in the non-ionic preparations. According to stability constants and kinetic measurements, the most stable Gd-CM is the ionic-macrocyclic chelate Gd-DOTA and the least stable agents are the non-ionic linear chelates gadodiamide and gadoversetamide. In vivo data confirmed the low stability of non-ionic linear chelates but no significant difference was observed amongst the macrocyclic agents whether ionic (Gd-DOTA) or non-ionic such as Gd-HP-DO3A and Gd-BT-DO3A. The stability of Gd-CA seems to be an important factor in the pathogenesis of the serious complication of nephrogenic systemic fibrosis. Gd-CA of low stability are likely to undergo transmetallation and release free Gd ions that deposit in tissue and attract circulating fibrocytes to initiate the process of fibrosis. No cases of NSF have been observed so far after the exclusive use of the stable macrocyclic Gd-CA

  4. Ocularity Feature Contrast Attracts Attention Exogenously

    Directory of Open Access Journals (Sweden)

    Li Zhaoping

    2018-02-01

    Full Text Available An eye-of-origin singleton, e.g., a bar shown to the left eye among many other bars shown to the right eye, can capture attention and gaze exogenously or reflexively, even when it appears identical to other visual input items in the scene and when the eye-of-origin feature is irrelevant to the observer’s task. Defining saliency as the strength of exogenous attraction to attention, we say that this eye-of-origin singleton, or its visual location, is salient. Defining the ocularity of a visual input item as the relative difference between its left-eye input and its right-eye input, this paper shows the general case that an ocularity singleton is also salient. For example, a binocular input item among monocular input items is salient, so is a left-eye-dominant input item (e.g., a bar with a higher input contrast to the left eye than to the right eye among right-eye-dominant items. Saliency by unique input ocularity is analogous to saliency by unique input colour (e.g., a red item among green ones, as colour is determined by the relative difference(s between visual inputs to different photoreceptor cones. Just as a smaller colour difference between a colour singleton and background items makes this singleton less salient, so does a smaller ocularity difference between an ocularity singleton and background items. While a salient colour difference is highly visible, a salient ocularity difference is often perceptually invisible in some cases and discouraging gaze shifts towards it in other cases, making its behavioural manifestation not as apparent. Saliency by ocularity contrast provides another support to the idea that the primary visual cortex creates a bottom-up saliency map to guide attention exogenously.

  5. Contrast optimization in multiphase arterial spin labeling; Otimizacao do contraste em ASL multi-fase

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, Fernando F.; Paschoal, Andre M., E-mail: paiva@ifsc.usp.br [Universidade de Sao Paulo (CIERMag/USP), Sao Carlos, SP (Brazil). Instituto de Fisica; Foerster, Bernd U. [Philips Medical Systems LatAm, Sao Paulo, SP (Brazil); Tovar-Moll, Fernanda; Moll, Jorge [Instituto D' Or de Pesquisa e Ensino, Rio de Janeiro, RJ (Brazil)

    2013-08-15

    Multiphase ASL is an effective way to overcome the regional variation of the transit time that difficult the estimation of perfusion values. However, with conventional multiple phases ASL techniques, the ASL contrast at later phases is impaired due to repeated application of excitation pulses and longitudinal relaxation making it difficult to evaluate the tissue perfusion in regions where the transit time is longer. In the present study, we show an improvement of the acquisition scheme by exploring a modulation on the flip angle of the MR acquisition to keep the ASL contrast constant over multiple phases. (author)

  6. Anaphylactic reaction to iodinated contrast media. Review the relevant loterature

    International Nuclear Information System (INIS)

    Kuwashima, Shigeko; Kitajima, Kazuhiro; Kohno, Tatsuo; Kaji, Yasushi; Takahashi, Tetuya; Seki, Masaya; Sakamoto, Tomoyuki

    2007-01-01

    Recently, iodinated contrast media are necessary for CT examinations and they occupy an important position in the radiological diagnosis. Nonionic contrast media significantly reduce the prevalence of all degree of adverse reaction to contrast media rather than ionic contrast media. So, generally, iodinated contrast media are safe and widely used, but adverse reaction after intravenous iodinated contrast media are not uncommon. Severe and potentially life-threatening reaction occur by using the iodinated contrast media practically. Patients at risk must be identified before the contrast media study, and all possible measures must be taken to deal effectively with spontaneous anaphylactic reactions. We report three cases of anaphylactic reactions by iodinated contrast media on CT. (author)

  7. Accounting for Laser Extinction, Signal Attenuation, and Secondary Emission While Performing Optical Patternation in a Single Plane

    National Research Council Canada - National Science Library

    Brown, C

    2002-01-01

    An optical patternation method is described where the effects of laser extinction and signal attenuation can be corrected for, and where secondary scattering effects are reduced by probing the spray...

  8. L'analyse contrastive: histoire et situation actuelle (Contrastive Analysis: History and Current Situation).

    Science.gov (United States)

    Py, Bernard

    1984-01-01

    It is suggested that it is not between two languages that transfers and interference occur, but within the learner. The learner mediates and constructs this relationship according to acquisition operations, processes, strategies, and stages that contrastive analysis, despite its utility, can neither account for nor predict. (MSE)

  9. High Contrast Vacuum Nuller Testbed (VNT) Contrast, Performance and Null Control

    Science.gov (United States)

    Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.

    2012-01-01

    Herein we report on our Visible Nulling Coronagraph high-contrast result of 109 contrast averaged over a focal planeregion extending from 14 D with the Vacuum Nuller Testbed (VNT) in a vibration isolated vacuum chamber. TheVNC is a hybrid interferometriccoronagraphic approach for exoplanet science. It operates with high Lyot stopefficiency for filled, segmented and sparse or diluted-aperture telescopes, thereby spanning the range of potential futureNASA flight telescopes. NASAGoddard Space Flight Center (GSFC) has a well-established effort to develop the VNCand its technologies, and has developed an incremental sequence of VNC testbeds to advance this approach and itsenabling technologies. These testbeds have enabled advancement of high-contrast, visible light, nulling interferometry tounprecedented levels. The VNC is based on a modified Mach-Zehnder nulling interferometer, with a W configurationto accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters.We give an overview of the VNT and discuss the high-contrast laboratory results, the optical configuration, criticaltechnologies and null sensing and control.

  10. Contrast-induced acute kidney injury: how much contrast is safe?

    LENUS (Irish Health Repository)

    Keaney, John J

    2013-02-14

    Iodinated contrast media (CM) are used in many investigations that a patient may undergo during the course of an in-patient stay. For the vast majority of patients, exposure to CM has no sequelae; however, in a small percentage, it can result in a worsening in renal function termed contrast-induced acute kidney injury (CI-AKI). CI-AKI is one of the leading causes of in-hospital renal dysfunction. It is associated with a significant increase in morbidity and mortality as well as an increased length of hospital stay and costs. Unfortunately, the results of extensive research into pharmacological inventions to prevent CI-AKI remain disappointing. In this article, we briefly outline the pathophysiological mechanisms by which iodinated CM may cause CI-AKI and discuss the evidence for reducing CI-AKI by limiting contrast volumes. In particular, we review the data surrounding the use of contrast volume to glomerular filtration rate ratios, which can be used by clinicians to effectively lower the incidence of CI-AKI in their patients.

  11. Variational contrast enhancement guided by global and local contrast measurements for single-image defogging

    Science.gov (United States)

    Zhou, Li; Bi, Du-Yan; He, Lin-Yuan

    2015-01-01

    The visibility of images captured in foggy conditions is impaired severely by a decrease in the contrasts of objects and veiling with a characteristic gray hue, which may limit the performance of visual applications out of doors. Contrast enhancement together with color restoration is a challenging mission for conventional fog-removal methods, as the degrading effect of fog is largely dependent on scene depth information. Nowadays, people change their minds by establishing a variational framework for contrast enhancement based on a physically based analytical model, unexpectedly resulting in color distortion, dark-patch distortion, or fuzzy features of local regions. Unlike previous work, our method treats an atmospheric veil as a scattering disturbance and formulates a foggy image as an energy functional minimization to estimate direct attenuation, originating from the work of image denoising. In addition to a global contrast measurement based on a total variation norm, an additional local measurement is designed in that optimal problem for the purpose of digging out more local details as well as suppressing dark-patch distortion. Moreover, we estimate the airlight precisely by maximization with a geometric constraint and a natural image prior in order to protect the faithfulness of the scene color. With the estimated direct attenuation and airlight, the fog-free image can be restored. Finally, our method is tested on several benchmark and realistic images evaluated by two assessment approaches. The experimental results imply that our proposed method works well compared with the state-of-the-art defogging methods.

  12. Moderate contrast in the evaluation of paintings is liked more but remembered less than high contrast

    NARCIS (Netherlands)

    K. Dijkstra (Katinka); van Dongen, N.N.N. (Noah N.N.)

    2017-01-01

    textabstractMany visual aspects of paintings, as well as exposure to art and cultural norms, contribute to the aesthetic evaluation of paintings. The current study looked at heightened visual contrast as an important factor in the appreciation of paintings. Participants evaluated abstract digitized

  13. High contrast vacuum nuller testbed (VNT) contrast, performance, and null control

    Science.gov (United States)

    Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.

    2012-09-01

    Herein we report on our Visible Nulling Coronagraph high-contrast result of 109 contrast averaged over a focal plane region extending from 1 - 4 λ/D with the Vacuum Nuller Testbed (VNT) in a vibration isolated vacuum chamber. The VNC is a hybrid interferometric/coronagraphic approach for exoplanet science. It operates with high Lyot stop efficiency for filled, segmented and sparse or diluted-aperture telescopes, thereby spanning the range of potential future NASA flight telescopes. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop the VNC and its technologies, and has developed an incremental sequence of VNC testbeds to advance this approach and its enabling technologies. These testbeds have enabled advancement of high-contrast, visible light, nulling interferometry to unprecedented levels. The VNC is based on a modified Mach-Zehnder nulling interferometer, with a “W” configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. We give an overview of the VNT and discuss the high-contrast laboratory results, the optical configuration, critical technologies and null sensing and control.

  14. Investigation of Pockels Cells Crystal Contrast Ratio Distribution

    Directory of Open Access Journals (Sweden)

    Giedrius Sinkevičius

    2017-07-01

    Full Text Available The BBO Pockel’s cell has been investigated. The investigation results of optimal operating area on the surface of the crystal dependent of intrinsic contrast ratio (ICR and voltage contrast ratio (VCR for Pockel’s cell are presented. The block diagram of Pockel’s cells contrast measurement stand and measurement methodology are introduced and discussed. The graphs of intrinsic contrast ratio distribution on crystal surface, contrast ratio with voltage dependency and voltage contrast ratio distribution on crystal surface with half-wave voltage are presented.

  15. Colorectal liver metastases: contrast agent diffusion coefficient for quantification of contrast enhancement heterogeneity at MR imaging.

    Science.gov (United States)

    Jia, Guang; O'Dell, Craig; Heverhagen, Johannes T; Yang, Xiangyu; Liang, Jiachao; Jacko, Richard V; Sammet, Steffen; Pellas, Theodore; Cole, Patricia; Knopp, Michael V

    2008-09-01

    To describe and determine the reproducibility of a simplified model to quantitatively measure heterogeneous intralesion contrast agent diffusion in colorectal liver metastases. This HIPAA-compliant retrospective study received institutional review board approval, and written informed consent was obtained from 14 patients (mean age, 61 years +/- 9 [standard deviation]; range, 41-78 years), including 10 men (mean age, 65 years +/- 8; range, 47-78 years) and four women (mean age, 54 years +/- 9; range, 41-59 years), with colorectal liver metastases. Magnetic resonance (MR) imaging was performed twice (first baseline MR image [B(1)] and second baseline MR image [B(2)]) in a single target lesion prior to therapy. Dynamic contrast material-enhanced MR imaging was performed by using a saturation-recovery fast gradient-echo sequence. A simplified contrast agent diffusion model was proposed, and a contrast agent diffusion coefficient (CDC) was calculated. The reproducibility of the CDC measurement was evaluated by using the Bland-Altman plot and a linear regression model. The mean CDC was 0.22 mm(2)/sec (range, 0.01-0.73 mm(2)/sec) on B(1) and 0.24 mm(2)/sec (range, 0.01-0.71 mm(2)/sec) on B(2), with an intraclass correlation coefficient of 0.91 (P < .0001). Bland-Altman plot showed good agreement, with a mean difference in measurement pairs of 0.017 mm(2)/sec +/- 0.096. The slope from the linear regression model was 0.89 (95% confidence interval: 0.63, 1.15) and the intercept was 0.01 (95% confidence interval: -0.08, 0.09). The CDC enables a quantitative description of contrast enhancement heterogeneity in lesions. Given the high reproducibility of the CDC metric, CDC appears promising for further qualification as an imaging biomarker of change measurement in response assessment. http://radiology.rsnajnls.org/cgi/content/full/248/3/901/DC1. RSNA, 2008

  16. NON-CONTRAST MAGNETIC RESONANCE UROGRAPHY

    Directory of Open Access Journals (Sweden)

    Arpita C

    2016-07-01

    Full Text Available BACKGROUND AND PURPOSE Magnetic Resonance (MR urography with its optimal contrast resolution and lack of ionizing radiation provides a comprehensive examination of the entire urinary tract noninvasively. MR urography is clinically useful in the evaluation of suspected urinary tract obstruction, haematuria, congenital anomalies, and surgically altered anatomy. It is particularly useful in cases of where there is contraindication of ionizing radiation and in paediatric and pregnant patients. The common MR urographic techniques are: Static-fluid MR urography and excretory MR urography. Static-fluid MR urography uses of heavily T2-weighted sequences to image the urinary tract as a static collection of fluid, can be repeated sequentially (Cine MR urography to better demonstrate the ureters in their entirety and to confirm the presence of fixed stenoses. Excretory MR urography is performed during the excretory phase of enhancement after the intravenous administration of gadolinium-based contrast material; thus, the patient must have sufficient renal function to allow the excretion. Static-fluid and excretory MR urography can be combined with conventional MR imaging for comprehensive evaluation of the urinary tract. The limitations are limited availability, high cost, relatively long examination time, low spatial resolution compared to IVU (Intravenous Urogram and CT Urography; sensitivity to motion (breathing and ureteral peristalsis inherent contraindications like patients with pacemakers, claustrophobia, and relative insensitivity for calcification and ureteric calculi. In this article, an attempt has been made to demonstrate the potential of static-fluid MRU to demonstrate a spectrum of urologic pathology involving the kidneys, ureters, and bladder while discussing the limitations. METHODS Thirty patients with urinary tract abnormalities were evaluated with MR urography performed between May 2014 to April 2016 using routine MR sequences and

  17. Dynamic contrast enhanced MRI in prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Alonzi, Roberto [Marie Curie Research Wing, Mount Vernon Cancer Centre, Rickmansworth Road, Northwood, Middlesex, HA6 2RN (United Kingdom)], E-mail: robertoalonzi@btinternet.com; Padhani, Anwar R. [Paul Strickland Scanner Centre, Mount Vernon Cancer Centre, Rickmansworth Road, Northwood, Middlesex, HA6 2RN (United Kingdom); Synarc Inc. 575 Market Street, San Francisco, CA 94105 (United States)], E-mail: anwar.padhani@paulstrickland-scannercentre.org.uk; Allen, Clare [Department of Imaging, University College Hospital, London, 235 Euston Road, NW1 2BU (United Kingdom)], E-mail: clare.allen@uclh.nhs.uk

    2007-09-15

    Angiogenesis is an integral part of benign prostatic hyperplasia (BPH), is associated with prostatic intraepithelial neoplasia (PIN) and is key to the growth and for metastasis of prostate cancer. Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) using small molecular weight gadolinium chelates enables non-invasive imaging characterization of tissue vascularity. Depending on the technique used, data reflecting tissue perfusion, microvessel permeability surface area product, and extracellular leakage space can be obtained. Two dynamic MRI techniques (T{sub 2}*-weighted or susceptibility based and T{sub 1}-weighted or relaxivity enhanced methods) for prostate gland evaluations are discussed in this review with reference to biological basis of observations, data acquisition and analysis methods, technical limitations and validation. Established clinical roles of T{sub 1}-weighted imaging evaluations will be discussed including lesion detection and localisation, for tumour staging and for the detection of suspected tumour recurrence. Limitations include inadequate lesion characterisation particularly differentiating prostatitis from cancer, and in distinguishing between BPH and central gland tumours.

  18. Diffraction contrast imaging using virtual apertures

    International Nuclear Information System (INIS)

    Gammer, Christoph; Burak Ozdol, V.; Liebscher, Christian H.; Minor, Andrew M.

    2015-01-01

    Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated. In a STEM-based approach, diffraction patterns are recorded for each beam position using a small probe convergence angle. Similarly, a tilt series of TEM dark-field images is acquired. The resulting datasets allow the reconstruction of either electron diffraction patterns, or bright-, dark- or annular dark-field images using virtual apertures. The experimental procedures of both methods are presented in the paper and are applied to a precipitation strengthened and creep deformed ferritic alloy with a complex microstructure. The reconstructed virtual images are compared with conventional TEM images. The major advantage is that arbitrarily shaped virtual apertures generated with image processing software can be designed without facing any physical limitations. In addition, any virtual detector that is specifically designed according to the underlying crystal structure can be created to optimize image contrast. - Highlights: • A dataset containing all structural information of a given position is recorded. • The dataset allows reconstruction of virtual diffraction patterns or images. • Specific virtual apertures are designed to image precipitates in a complex alloy. • Virtual diffraction patterns from arbitrarily small regions can be established. • Using STEM diffraction to record the dataset is more efficient than TEM dark-field

  19. Topical contrast-enhanced magnetic resonance dacryocystography

    International Nuclear Information System (INIS)

    Yoshikawa, Takeshi; Sugimura, Kazuro; Hirota, Shozo

    2000-01-01

    The purpose of this study was to evaluate the usefulness of magnetic resonance dacryocystography (MRD) with topical administration of normal saline solution and diluted Gd-DTPA solution for the assessment of lacrimal outflow disorders. Two T2-weighted sequences and two T1-weighted sequences were evaluated in this study. The 1:100 diluted Gd solution was prepared by diluting Gd-DTPA (Magnevist) with normal saline solution. A phantom study using tube phantoms of various diameters filled with normal saline solution and 1:100 diluted Gd solution was performed. A preliminary study was performed in ten normal volunteers Eighteen patients with lacrimal outflow disorders underwent clinical MRD, and 14 also underwent conventional dacryocystography (CDG). MRD images were evaluated and compared with clinical symptoms and CDG images. In all sequences, MRD could visualize the full length of 0.7 to 1.7 mm diameter tube phantoms and could show all of the normal lacrimal sacs and nasolacrimal ducts. In the clinical study, MRD findings were compatible with the symptoms in 14 patients but were not compatible with CDG findings in half of the cases. Topical contrast-enhanced MRD provided a simple, non-invasive means of obtaining detailed morphological and functional information on the lacrimal drainage apparatus. (author)

  20. Monitoring stem cells in phase contrast imaging

    Science.gov (United States)

    Lam, K. P.; Dempsey, K. P.; Collins, D. J.; Richardson, J. B.

    2016-04-01

    Understanding the mechanisms behind the proliferation of Mesenchymal Stem cells (MSCs) can offer a greater insight into the behaviour of these cells throughout their life cycles. Traditional methods of determining the rate of MSC differentiation rely on population based studies over an extended time period. However, such methods can be inadequate as they are unable to track cells as they interact; for example, in autologous cell therapies for osteoarthritis, the development of biological assays that could predict in vivo functional activity and biological action are particularly challenging. Here further research is required to determine non-histochemical biomarkers which provide correlations between cell survival and predictive functional outcome. This paper proposes using a (previously developed) advanced texture-based analysis algorithm to facilitate in vitro cells tracking using time-lapsed microscopy. The technique was adopted to monitor stem cells in the context of unlabelled, phase contrast imaging, with the goal of examining the cell to cell interactions in both monoculture and co-culture systems. The results obtained are analysed using established exploratory procedures developed for time series data and compared with the typical fluorescent-based approach of cell labelling. A review of the progress and the lessons learned are also presented.

  1. Smart Contrast Agents for Magnetic Resonance Imaging.

    Science.gov (United States)

    Bonnet, Célia S; Tóth, Éva

    2016-01-01

    By visualizing bioactive molecules or biological parameters in vivo, molecular imaging is searching for information at the molecular level in living organisms. In addition to contributing to earlier and more personalized diagnosis in medicine, it also helps understand and rationalize the molecular factors underlying physiological and pathological processes. In magnetic resonance imaging (MRI), complexes of paramagnetic metal ions, mostly lanthanides, are commonly used to enhance the intrinsic image contrast. They rely either on the relaxation effect of these metal chelates (T(1) agents), or on the phenomenon of paramagnetic chemical exchange saturation transfer (PARACEST agents). In both cases, responsive molecular magnetic resonance imaging probes can be designed to report on various biomarkers of biological interest. In this context, we review recent work in the literature and from our group on responsive T(1) and PARACEST MRI agents for the detection of biogenic metal ions (such as calcium or zinc), enzymatic activities, or neurotransmitter release. These examples illustrate the general strategies that can be applied to create molecular imaging agents with an MRI detectable response to biologically relevant parameters.

  2. Simultaneous brightness contrast of foraging Papilio butterflies

    Science.gov (United States)

    Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

    2012-01-01

    This study focuses on the sense of brightness in the foraging Japanese yellow swallowtail butterfly, Papilio xuthus. We presented two red discs of different intensity on a grey background to butterflies, and trained them to select one of the discs. They were successfully trained to select either a high intensity or a low intensity disc. The trained butterflies were tested on their ability to perceive brightness in two different protocols: (i) two orange discs of different intensity presented on the same intensity grey background and (ii) two orange discs of the same intensity separately presented on a grey background that was either higher or lower in intensity than the training background. The butterflies trained to high intensity red selected the orange disc of high intensity in protocol 1, and the disc on the background of low intensity grey in protocol 2. We obtained similar results in another set of experiments with purple discs instead of orange discs. The choices of the butterflies trained to low intensity red were opposite to those just described. Taken together, we conclude that Papilio has the ability to learn brightness and darkness of targets independent of colour, and that they have the so-called simultaneous brightness contrast. PMID:22179808

  3. Improve identification of details in double-contrast examination of the stomach by means of a new contrast medium mixture

    International Nuclear Information System (INIS)

    Tenner, R.

    1984-01-01

    In a contrast medium study, 100 patients were employed for a comparison between the contrast medium Mikropaque liquid and a mixture of Mikropaque HD and Mikropaque liquid in double-contrast examination of the stomach. The special feature of this method was that one and the same stomach was examined in each case with both contrast media. The new contrast media mixture with Mikropaque HD represents a step forward; the contrast could be enhanced in 80% of the cases, and the finely contoured relief became visible in two-thirds of the cases, compared with one-third of the examined patients before this method was introduced. (orig.) [de

  4. Enhancing contrast of magnetic resonance imaging in patients with ...

    African Journals Online (AJOL)

    DTPA), a recent magnetic resonance imaging (MRI) contrast agent, in hepatobiliary system of patients with liver cirrhosis. Methods: Liver cirrhosis patients that underwent contrast MRI examination at Renai Hospital, Taipei City, Taiwan were ...

  5. Method and apparatus to characterize ultrasonically reflective contrast agents

    Science.gov (United States)

    Pretlow, Robert A., III (Inventor)

    1993-01-01

    A method and apparatus for characterizing the time and frequency response of an ultrasonically reflective contrast agent is disclosed. An ultrasonically reflective contrast agent is injected, under constant pressure, into a fluid flowing through a pump flow circuit. The fluid and the ultrasonically reflective contrast agent are uniformly mixed in a mixing chamber, and the uniform mixture is passed through a contrast agent chamber. The contrast agent chamber is acoustically and axially interposed between an ultrasonic transducer chamber and an acoustic isolation chamber. A pulse of ultrasonic energy is transmitted into the contrast agent chamber from the ultrasonic transducer chamber. An echo waveform is received from the ultrasonically reflective contrast agent, and it is analyzed to determine the time and frequency response of the ultrasonically reflective contrast agent.

  6. Positive behavioral contrast across food and alcohol reinforcers.

    OpenAIRE

    McSweeney, F K; Melville, C L; Higa, J

    1988-01-01

    The present study examined behavioral contrast during concurrent and multiple schedules that provided food and alcohol reinforcers. Concurrent-schedule contrast occurred in the responding reinforced by food when alcohol reinforcers were removed. It also occurred in the responding reinforced by alcohol when food was removed. Multiple-schedule contrast appeared for food when alcohol reinforcers were removed, but not for alcohol when food was removed. These results show that behavioral contrast ...

  7. Contrast characteristics of barium preparations and the timing of exposure

    OpenAIRE

    渋谷, 光一; 中桐, 義忠; 東, 義晴; 杉田, 勝彦; 小橋, 高郎; 大倉, 保彦; 丹谷, 延義; 三上, 泰隆; 平木, 祥夫

    1995-01-01

    We studied the relationship between the contrast characteristics of barium suspension and timing of exposure. We poured several kinds of barium preparations on the phantom manufactured by ourselves, and took X-ray pictures continuously by a DSA system. We analyzed each of the characteris-tics of the contrast. The time which was reguired for the contrast to reach the peak (Contrast Peak Time ; CPT) was unrelated with the kind of barium preparations used. It depended on the viscosity of the con...

  8. Contrasting Specific English Corpora: Language Variation

    Directory of Open Access Journals (Sweden)

    María Luisa Carrió Pastor

    2009-12-01

    Full Text Available The scientific community has traditionally considered technical English as neutral and objective, able to transmit ideas and research in simple sentences and specialized vocabulary. Nevertheless, global communication and intense information delivery have produced a range of different ways of knowledge transmission. Although technical English is considered an objective way to transmit science, writers of academic papers use some words or structures with different frequency in the same genre. As a consequence of this, contrastive studies about the use of second languages have been increasingly attracting scholarly attention. In this research, we evidence that variation in language production is a reality and can be proved contrasting corpora written by native writers of English and by non-native writers of English. The objectives of this paper are first to detect language variation in a technical English corpus; second, to demonstrate that this finding evidences the parts of the sentence that are more sensitive to variation; finally, it also evidences the non-standardisation of technical English. In order to fulfil these objectives, we analysed a corpus of fifty scientific articles written by native speakers of English and fifty scientific articles written by non-native speakers of English. The occurrences were classified and counted in order to detect the most common variations. Further analysis indicated that the variations were caused by mother tongue interference in virtually all cases, although meaning was only very rarely obscured. These findings suggest that the use of certain patterns and expressions originating from L1 interference should be considered as correct as standard English.La comunidad científica considera al inglés técnico como un tipo de lenguaje neutral y objetivo, capaz de transmitir ideas y hallazgos en frases simples y vocabulario reconocido por los especialistas de ese campo. Sin embargo, la comunicación global y el

  9. Contrast to Noise Ratio and Contrast Detail Analysis in Mammography:A Monte Carlo Study

    International Nuclear Information System (INIS)

    Metaxas, V; Delis, H; Panayiotakis, G; Kalogeropoulou, C; Zampakis, P

    2015-01-01

    The mammographic spectrum is one of the major factors affecting image quality in mammography. In this study, a Monte Carlo (MC) simulation model was used to evaluate image quality characteristics of various mammographic spectra. The anode/filter combinations evaluated, were those traditionally used in mammography, for tube voltages between 26 and 30 kVp. The imaging performance was investigated in terms of Contrast to Noise Ratio (CNR) and Contrast Detail (CD) analysis, by involving human observers, utilizing a mathematical CD phantom. Soft spectra provided the best characteristics in terms of both CNR and CD scores, while tube voltage had a limited effect. W-anode spectra filtered with k-edge filters demonstrated an improved performance, that sometimes was better compared to softer x-ray spectra, produced by Mo or Rh anode. Regarding the filter material, k-edge filters showed superior performance compared to Al filters. (paper)

  10. Contrast enhanced ultrasound of splenic lymphoma involvement

    International Nuclear Information System (INIS)

    Goerg, Christian; Faoro, Charis; Bert, Tillmann; Tebbe, Johannes; Neesse, Albrecht; Wilhelm, Christian

    2011-01-01

    Objective: The aim of this study was to compare the value of contrast-enhanced ultrasonography (CEUS) with standard B-mode ultrasound (US) for diagnosis of splenic lymphoma involvement. Methods: From 04/2005 to 10/2008 n = 250 lymphoma patients were investigated by standard B-mode US. A homogeneous splenic echotexture was found in 199 patients (79%). To clarify the benefit of CEUS in this group a pilot series was performed with 16 of the 199 lymphoma patients. All patients with an abnormal splenic echotexture on standard B-Mode US (n = 51) including focal hypoechoic splenic lesions (n = 41) and an inhomogeneous splenic texture (n = 10) were studied by CEUS. CEUS data were retrospectively evaluated. The diagnoses included indolent lymphoma (n = 27), aggressive lymphoma (n = 14), and Hodgkin's disease (n = 10). Number and size of lesions were determined by B-mode US and CEUS. The visualisation of splenic lymphoma involvement by CEUS in comparison to B-mode US was classified as worse, equal, or better. Results: All patients with a homogeneous spleen on B-mode US (n = 16) had no visible focal lesions on CEUS. Study patients with focal lesions (n = 41) had a hypoechoic (n = 22) or isoechoic (n = 19) enhancement during the arterial phase, and a hypoechoic enhancement during the parenchymal phase (n = 41). The visualisation of focal splenic lymphoma was equal (n = 32), better (n = 6), or worse (n = 3). In all study patients with an inhomogeneous spleen on B-mode US (n = 10) no focal lesions were found by CEUS and the value of CEUS therefore was classified as worse. Conclusion: CEUS has no clear advantage for diagnosis of splenic lymphoma involvement.

  11. Contrast enhanced ultrasound of splenic lymphoma involvement

    Energy Technology Data Exchange (ETDEWEB)

    Goerg, Christian, E-mail: goergc@med.uni-marburg.de [Medizinische Universitaetsklinik, Baldingerstrasse, 35033 Marburg/Lahn (Germany); Faoro, Charis [Medizinische Universitaetsklinik, Baldingerstrasse, 35033 Marburg/Lahn (Germany); Bert, Tillmann [Zentralklinik Bad Berka GmbH, Robert-Koch-Allee 9, 99437 Bad Berka (Germany); Tebbe, Johannes [Klinikum Lippe-Detmold, Roentgenstrasse 18, 32756 Detmold (Germany); Neesse, Albrecht; Wilhelm, Christian [Medizinische Universitaetsklinik, Baldingerstrasse, 35033 Marburg/Lahn (Germany)

    2011-11-15

    Objective: The aim of this study was to compare the value of contrast-enhanced ultrasonography (CEUS) with standard B-mode ultrasound (US) for diagnosis of splenic lymphoma involvement. Methods: From 04/2005 to 10/2008 n = 250 lymphoma patients were investigated by standard B-mode US. A homogeneous splenic echotexture was found in 199 patients (79%). To clarify the benefit of CEUS in this group a pilot series was performed with 16 of the 199 lymphoma patients. All patients with an abnormal splenic echotexture on standard B-Mode US (n = 51) including focal hypoechoic splenic lesions (n = 41) and an inhomogeneous splenic texture (n = 10) were studied by CEUS. CEUS data were retrospectively evaluated. The diagnoses included indolent lymphoma (n = 27), aggressive lymphoma (n = 14), and Hodgkin's disease (n = 10). Number and size of lesions were determined by B-mode US and CEUS. The visualisation of splenic lymphoma involvement by CEUS in comparison to B-mode US was classified as worse, equal, or better. Results: All patients with a homogeneous spleen on B-mode US (n = 16) had no visible focal lesions on CEUS. Study patients with focal lesions (n = 41) had a hypoechoic (n = 22) or isoechoic (n = 19) enhancement during the arterial phase, and a hypoechoic enhancement during the parenchymal phase (n = 41). The visualisation of focal splenic lymphoma was equal (n = 32), better (n = 6), or worse (n = 3). In all study patients with an inhomogeneous spleen on B-mode US (n = 10) no focal lesions were found by CEUS and the value of CEUS therefore was classified as worse. Conclusion: CEUS has no clear advantage for diagnosis of splenic lymphoma involvement.

  12. Patient safety and adverse events in contrast medium examinations

    International Nuclear Information System (INIS)

    Enge, I.; Edgren, J.

    1989-01-01

    This volume contains six contributions dealing with the properties, safety and economic aspects (lower risks but higher costs of new low-osmonality contrast media compared to the older high-osmonality, ionic ones) of contrast media used in radiology, and risks involved in procedures for administering of radiologic contrast media. (H.W.). refs.; figs.; tabs

  13. Iodine-based contrast media, multiple myeloma and monoclonal gammopathies

    DEFF Research Database (Denmark)

    Stacul, Fulvio; Bertolotto, Michele; Thomsen, Henrik S

    2018-01-01

    OBJECTIVES: Many radiologists and clinicians still consider multiple myeloma (MM) and monoclonal gammopathies (MG) a contraindication for using iodine-based contrast media. The ESUR Contrast Media Safety Committee performed a systematic review of the incidence of post-contrast acute kidney injury...

  14. The effect of defocus on edge contrast sensitivity

    NARCIS (Netherlands)

    Jansonius, NM; Kooijman, AC

    The effect of optical blur (defocus) on edge contrast sensitivity was studied. Edge contrast sensitivity detoriates with fairly small amounts of blur (similar to 0.5 D) and is roughly reduced by half for each dioptre of blur. The effect of blur on edge contrast sensitivity equals the effect of blur

  15. Contrast as denial in multi-dimensional semantics

    NARCIS (Netherlands)

    Spenader, Jennifer; Maier, Emar

    We argue that contrastive statements have the same underlying semantics and affect the context in the same way as denials. We substantiate this claim by giving a unified account of the two phenomena that treats contrast as a subtype of denial. We argue that earlier work on contrast-denial obscured

  16. Contrast-enhanced spectral mammography (CESM) and contrast enhanced MRI (CEMRI): Patient preferences and tolerance.

    Science.gov (United States)

    Hobbs, Max M; Taylor, Donna B; Buzynski, Sebastian; Peake, Rachel E

    2015-06-01

    Contrast-enhanced spectral mammography (CESM) may have similar diagnostic performance to Contrast-enhanced MRI (CEMRI) in the diagnosis and staging of breast cancer. To date, research has focused exclusively on diagnostic performance when comparing these two techniques. Patient experience is also an important factor when comparing and deciding on which of these modalities is preferable. The aim of this study is to compare patient experience of CESM against CEMRI during preoperative breast cancer staging. Forty-nine participants who underwent both CESM and CEMRI, as part of a larger trial, completed a Likert questionnaire about their preference for each modality according to the following criteria: comfort of breast compression, comfort of intravenous (IV) contrast injection, anxiety and overall preference. Participants also reported reasons for preferring one modality to the other. Quantitative data were analysed using a Wilcoxon sign-rank test and chi-squared test. Qualitative data are reported descriptively. A significantly higher overall preference towards CESM was demonstrated (n = 49, P < 0.001), with faster procedure time, greater comfort and lower noise level cited as the commonest reasons. Participants also reported significantly lower rates of anxiety during CESM compared with CEMRI (n = 36, P = 0.009). A significantly higher rate of comfort was reported during CEMRI for measures of breast compression (n = 49, P = 0.001) and the sensation of IV contrast injection (n = 49, P = 0.003). Our data suggest that overall, patients prefer the experience of CESM to CEMRI, adding support for the role of CESM as a possible alternative to CEMRI for breast cancer staging. © 2015 The Royal Australian and New Zealand College of Radiologists.

  17. Contrast-enhanced spectral mammography (CESM) and contrast enhanced MRI (CEMRI): Patient preferences and tolerance

    International Nuclear Information System (INIS)

    Hobbs, Max; Buzynski, Sebastian; Taylor, Donna B.; Peake, Rachel E.

    2015-01-01

    Contrast-enhanced spectral mammography (CESM) may have similar diagnostic performance to Contrast-enhanced MRI (CEMRI) in the diagnosis and staging of breast cancer. To date, research has focused exclusively on diagnostic performance when comparing these two techniques. Patient experience is also an important factor when comparing and deciding on which of these modalities is preferable. The aim of this study is to compare patient experience of CESM against CEMRI during preoperative breast cancer staging. Forty-nine participants who underwent both CESM and CEMRI, as part of a larger trial, completed a Likert questionnaire about their preference for each modality according to the following criteria: comfort of breast compression, comfort of intravenous (IV) contrast injection, anxiety and overall preference. Participants also reported reasons for preferring one modality to the other. Quantitative data were analysed using a Wilcoxon sign-rank test and chi-squared test. Qualitative data are reported descriptively. A significantly higher overall preference towards CESM was demonstrated (n = 49, P < 0.001), with faster procedure time, greater comfort and lower noise level cited as the commonest reasons. Participants also reported significantly lower rates of anxiety during CESM compared with CEMRI (n = 36, P = 0.009). A significantly higher rate of comfort was reported during CEMRI for measures of breast compression (n = 49, P = 0.001) and the sensation of IV contrast injection (n = 49, P = 0.003). Our data suggest that overall, patients prefer the experience of CESM to CEMRI, adding support for the role of CESM as a possible alternative to CEMRI for breast cancer staging.

  18. Computer-aided diagnosis in contrast-enhanced CT colonography: an approach based on contrast

    International Nuclear Information System (INIS)

    Luboldt, Wolfgang; Kroll, Manuela; Vogl, Thomas J.; Mann, Carolin; Vonthein, Reinhard; Stueker, Dietmar; Luz, Oliver; Claussen, Claus D.; Tryon, Cathy L.

    2002-01-01

    Automation in colorectal mass detection is achieved as soon as the voxels representing colorectal masses can be automatically segmented. We tested the Hounsfield (HU) value in intensely contrast enhanced high-resolution CT colonography for automated segmentation of colorectal masses in 18 patients with 35 polyps (28<10 mm, 7 ≥10 mm) and 7 carcinomas. Mean HU values of the colonic wall and masses were determined to deduce a gradient threshold for a segmentation process, which encodes the voxels bordering the colonic lumen with a colour ranging in intensity from 0 to 100% according to the selected gradient threshold range in the volume rendering. The results of the automated segmentation process were superimposed on a virtual double contrast and endoscopic display and validated through correlation with morphology. Mean HU values and their standard deviations for the colonic wall, polyps <10 mm, polyps ≥10 mm and carcinomas were 63±24, 154±38, 116±41 and 108±29 HU, respectively. A gradient threshold ranging from 90 to 160 HU resulted in colour pools in 6 of 7 of polyps ≥10 mm, and 6 of 7 carcinomas that were significant enough to prospectively guide the reader's attention to these masses. Due to the superposition of ''false-positive'' voxels in the projection view, the virtual endoscopic perspective was superior to the virtual double contrast display for controlling the segmentation results. The HU value is promising for automated segmentation of colorectal masses but needs to be combined with morphological parameters to render automated colorectal mass detection more accurate. Further refinements of the method with subsequent analysis of its accuracy, as well as analogue studies with contrast-enhanced MRI, appear warranted. More information at http://www.multiorganscreening.org (orig.)

  19. Effect of static scatterers in laser speckle contrast imaging: an experimental study on correlation and contrast

    Science.gov (United States)

    Vaz, Pedro G.; Humeau-Heurtier, Anne; Figueiras, Edite; Correia, Carlos; Cardoso, João

    2018-01-01

    Laser speckle contrast imaging (LSCI) is a non-invasive microvascular blood flow assessment technique with good temporal and spatial resolution. Most LSCI systems, including commercial devices, can perform only qualitative blood flow evaluation, which is a major limitation of this technique. There are several factors that prevent the utilization of LSCI as a quantitative technique. Among these factors, we can highlight the effect of static scatterers. The goal of this work was to study the influence of differences in static and dynamic scatterer concentration on laser speckle correlation and contrast. In order to achieve this, a laser speckle prototype was developed and tested using an optical phantom with various concentrations of static and dynamic scatterers. It was found that the laser speckle correlation could be used to estimate the relative concentration of static/dynamic scatterers within a sample. Moreover, the speckle correlation proved to be independent of the dynamic scatterer velocity, which is a fundamental characteristic to be used in contrast correction.

  20. Contrast between hypervascularized liver lesions and hepatic parenchyma. Early dynamic PET versus contrast-enhanced CT

    International Nuclear Information System (INIS)

    Freesmeyer, M.; Winkens, T.; Schierz, J.-H.

    2014-01-01

    To detect hypervascularized liver lesions, early dynamic (ED) 18 F-FDG PET may be an alternative when contrast-enhanced (CE) imaging is infeasible. This retrospective pilot analysis compared contrast between such lesions and liver parenchyma, an important objective image quality variable, in ED PET versus CE CT. Twenty-eight hypervascularized liver lesions detected by CE CT [21 (75%) hepatocellular carcinomas; mean (range) diameter 4.9 ± 3.5 (1-14) cm] in 20 patients were scanned with ED PET. Using regions of interest, maximum and mean lesional and parenchymal signals at baseline, arterial and venous phases were calculated for ED PET and CE CT. Lesional/parenchymal signal ratio was significantly higher (P < 0.005) with ED PET versus CE CT at the arterial phase and similar between the methods at the venous phase. In liver imaging, ED PET generates greater lesional-parenchymal contrast during the arterial phase than does CE CT; these observations should be formally, prospectively evaluated. (author)

  1. Comparison of excretory urographic contrast effects of dimeric and monomeric non-ionic iodinated contrast media in dogs

    International Nuclear Information System (INIS)

    Kishimoto, M.; Yamada, K.; Watanabe, A.; Miyamoto, K.; Iwasaki, T.; Miyake, Y.

    2007-01-01

    In excretory urography, the osmolarity of contrast media has rarely been treated as important in veterinary medicine. In this study, the contrast effect of two contrast media (monomeric iohexol and dimeric iodixanol) in the renal cortex and aorta were compared using computed tomography (CT). Five beagle dogs were used and the study employed a cross-over method for each contrast media. The results showed that there was no difference between the media in the aorta, but iodixanol showed higher CT value and a longer contrast effect than iohexol in the renal cortex, in spite of having the same iodine dosage. It is believed that iodixanol, with its low osmolarity, is diluted less by osmotic diuresis than monomeric iohexol. It is important to consider the osmolarity of the contrast media when evaluating the contrast effect, and it is essential to use the same contrast media for each examination, or the renal excretory speed will be under/overestimated

  2. Gadolinium-based contrast agents in pediatric magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gale, Eric M.; Caravan, Peter [Massachusetts General Hospital, Harvard Medical School, Department of Radiology, The Martinos Center for Biomedical Imaging, Boston, MA (United States); Rao, Anil G. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); McDonald, Robert J. [College of Medicine, Mayo Clinic, Department of Radiology, Rochester, MN (United States); Winfeld, Matthew [University of Pennsylvania Perelman School of Medicine, Philadelphia, PA (United States); Fleck, Robert J. [Cincinnati Children' s Hospital Medical Center, Department of Pediatric Radiology, Cincinnati, OH (United States); Gee, Michael S. [MassGeneral Hospital for Children, Harvard Medical School, Division of Pediatric Imaging, Department of Radiology, Boston, MA (United States)

    2017-05-15

    Gadolinium-based contrast agents can increase the accuracy and expediency of an MRI examination. However the benefits of a contrast-enhanced scan must be carefully weighed against the well-documented risks associated with administration of exogenous contrast media. The purpose of this review is to discuss commercially available gadolinium-based contrast agents (GBCAs) in the context of pediatric radiology. We discuss the chemistry, regulatory status, safety and clinical applications, with particular emphasis on imaging of the blood vessels, heart, hepatobiliary tree and central nervous system. We also discuss non-GBCA MRI contrast agents that are less frequently used or not commercially available. (orig.)

  3. The use of new contrast media agents in radiology

    International Nuclear Information System (INIS)

    Zerbe, M.

    1992-01-01

    The purpose of the document is to present the importance of different categories of contrast media in radiography. Ionic and non-ionic contrast media are presented. Pharmacology and pathophysiology of Iodine contrast media with their effects on special organs of the body like the heart, vessels, lungs and nervous systems are explained. Paramagnetic contrast media used in NMR imaging are presented too. Emphasis is made on contrast media based on Gadolinium like Gd-DTPA, Gd-CL3, Gd-EDTA. Actions of Gd-DTPA applied to images in urography are pointed out

  4. The use of contrast media in computer tomography

    International Nuclear Information System (INIS)

    Galanski, M.; Cramer, B.M.; Drewes, G.

    1980-01-01

    There are a variety of applications for contrast media in CT. They can be used for better anatomic demonstration or for showing pathological processes. Nearly all available contrast media may be found useful. Intravenously injected renographic contrast media are most commonly employed. In addition to their inherent contrast, specific pharmaco-kinetic changes may be of diagnostic value. This adds some knowledge of function to the purely morphological information obtained by computer tomography. For this purpose, contrast has to be injected rapidly and a fast scanner must be used (so-called angio-CT). (orig.) [de

  5. JUST Revisited: Panchronic and Contrastive Insights

    Directory of Open Access Journals (Sweden)

    Manuela Romano

    2012-06-01

    Full Text Available Contrastive studies of cognate pragmatic markers involving modality have become increasingly salient in recent times. In describing semantic and discursive differences in different languages and language families, these studies are paving the way for a better understanding of grammaticalization, pragmaticalization and (intersubjectification paths. The present paper aims at contributing to the discussion by means of providing a synchronic and diachronic account of the marker JUST that combines semasiological and onomasiological insights. As thoroughly described in previous studies, JUST is a complex polycentric category in which overlapping nuances have been activated over time. In English and in other languages, the diachronic evolution of JUST involves an increasing semantic expansion from scalar to subjectified meanings and an increasing restriction in grammatical flexibility. However, polysemization and the emergence of grammaticalized readings seem to have gone further in English than in other languages. The present study, situated within the emerging field of panchronic cross-linguistic research on discourse markers, aims at ascertaining why.El estudio contrastivo de los marcadores pragmáticos de modalidad ocupa una posición central en el campo de la gramaticalización, la pragmaticalización y la (intersubjetivización, ya que permite trazar rutas de cambio a través de la descripción de peculiaridades semánticas y discursivas en distintas lenguas y familias lingüísticas. Este trabajo contribuye al debate ofreciendo un análisis semasiológico y onomasiológico del marcador JUST en sincronía y diacronía. Se trata de una categoría policéntrica en la que se han ido activando lecturas cruzadas a lo largo del tiempo. Su evolución está marcada, tanto en inglés como en otras lenguas, por una expansión semántica cada vez mayor, transitando desde lecturas escalares hacia lecturas subjetivizadas, y por una flexibilidad gramatical

  6. A survey of contrast media used in coronary angiograph

    International Nuclear Information System (INIS)

    Weikl, A.; Hubmann, M.

    1982-01-01

    In recent years, various contrast media have been developed for use in coronary angiography. These contrast media may be divided into ionic contrast media of high osmolality, those of low osmolality, and nonionic contrast materials. We conducted our own clinical studies with 40 patients. In random succession a standard contrast medium (ionic, of high osmolality) and a new-generation contrast medium (either nonionic or ionic with low osmolality) were injected into the right and left coronary arteries. After each injection we measured the systolic and diastolic blood pressure using a liquid-filled coronary catheter. In addition, the change in the length of the cardiac cycle was registered in terms of the R-R interval (in ms) and at the same time, leads I, II, and III of the ECG were recorded. We studied the influence of the various contrast media on the activity of ATPase in in vitro experiments, using Lasser and Lang's. When ionic contrast media of low osmolality and nonionic contrast media were utilized the heart rate showed no change. Disturbances of rhythm such as ventricular tachycardia or fibrillation were not observed. All of the contrast media used produced the same ECG changes. These changes can be ascribed to the inhibition of ATPase. The arterial blood pressure was lowered significantly only by ionic contrast media of high osmolality only. (orig.)

  7. Fundamental study of DSA images using gadolinium contrast agent

    International Nuclear Information System (INIS)

    Nagashima, Hiroyuki; Shiraishi, Akihisa; Igarashi, Hitoshi; Sakamoto, Hajime; Sano, Yoshitomo

    2002-01-01

    Most contrast agents used in digital subtraction angiography (DSA) are non-ionic iodinated contrast agents, which can cause severe side effects in patients with contraindications for iodine or allergic reactions to iodine. Therefore, DSA examinations using carbon dioxide gas or examinations done by magnetic resonance imaging (MRI) and ultrasound (US) were carried out in these patients. However, none of these examinations provided mages as clear as those of DSA with an iodinated contrast agent. We experienced DSA examination using a gadolinium contrast agent in a patient contraindicated for iodine. The patient had undergone MRI examination with a gadolinium contrast agent previously without side effects. The characteristics of gadolinium and the iodinated contrast agent were compared, and the DSA images obtained clinically using these media were also evaluated. The signal-to-noise (SN) ratio of the gadolinium contrast agent was the highest at tube voltages of 70 to 80 kilovolts and improved slightly when the image intensifier (I.I.) entrance dose was greater than 300 μR (77.4 nC/kg). The dilution ratios of five iodinated contrast agents showed the same S/N value as the undiluted gadolinium contrast agent. Clinically, the images obtained showed a slight decrease in contrast but provided the data necessary to make a diagnosis and made it possible to obtain interventional radiology (IVR) without any side effects. DSA examinations using a gadolinium contrast agent have some benefit with low risk and are thought to be useful for patients contraindicated for iodine. (author)

  8. Spatiotemporal Characteristics for the Depth from Luminance Contrast

    Directory of Open Access Journals (Sweden)

    Kazuya Matsubara

    2011-05-01

    Full Text Available Images with higher luminance contrast tend to be perceived closer in depth. To investigate a spatiotemporal characteristic of this effect, we evaluated subjective depth of a test stimulus with various spatial and temporal frequencies. For the purpose, the depth of a reference stimulus was matched to that of the test stimulus by changing the binocular disparity. The results showed that the test stimulus was perceived closer with higher luminance contrast for all conditions. Contrast efficiency was obtained from the contrast that provided the subjective depth for each spatiotemporal frequency. The shape of the contrast efficiency function was spatially low-pass and temporally band-pass. This characteristic is different from the one measure for a detection task. This suggests that only subset of contrast signals are used for depth from contrast.

  9. MRI and CT contrast media extravasation: A systematic review.

    Science.gov (United States)

    Heshmatzadeh Behzadi, Ashkan; Farooq, Zerwa; Newhouse, Jeffery H; Prince, Martin R

    2018-03-01

    This systematic review combines data from multiple papers on contrast media extravasation to identify factors contributing to increased extravasation risk. Data were extracted from 17 papers reporting 2191 extravasations in 1,104,872 patients (0.2%) undergoing computed tomography (CT) or magnetic resonance imaging (MRI). Extravasation rates were 0.045% for gadolinium-based contrast agents (GBCA) and nearly 6-fold higher, 0.26% for iodinated contrast agents. Factors associated with increased contrast media extravasations included: older age, female gender, using an existing intravenous (IV) instead of placing a new IV in radiology, in-patient status, use of automated power injection, high injection rates, catheter location, and failing to warm up the more viscous contrast media to body temperature. Contrast media extravasation is infrequent but nearly 6 times less frequent with GBCA for MRI compared with iodinated contrast used in CT.

  10. Addition of lacal anesthetics to contrast media. Pt. 2

    International Nuclear Information System (INIS)

    Nilsson, P.; Almen, T.; Golman, K.; Jonsson, K.; Nyman, U.; Malmoe Allmaenna Sjukhus

    1988-01-01

    The acute intravenous toxicity (i.v. LD 50 ) of solutions of the ratio 1.5 contrast media metrizoate or diatrizoate and the ratio 3.0 contrast medium metrizamide was determined in mice with and without the addition of local anesthetics to the solutions. The two local anesthetics mepivacaine or lidocaine were added to final concentrations up to 2.0 mg/ml of the contrast medium solutions. This corresponds to clinically used concentrations. All additions of local anesthetics to the solutions increased the mortalities caused by the contrast medium solutions. Addition of local anesthetics to a final concentration of 2 mg/ml approximately doubled the acute intravenous toxicity of the contrast media. The ratio 3 contrast media produce less hypertonic solutions than the ratio 1.5 contrast media and should be preferred for angiography because they cause less pain and do not require the addition of local anesthetics which increase the acute toxicity of the solutions. (orig.)

  11. Effects of contrast on smooth pursuit eye movements.

    Science.gov (United States)

    Spering, Miriam; Kerzel, Dirk; Braun, Doris I; Hawken, Michael J; Gegenfurtner, Karl R

    2005-05-20

    It is well known that moving stimuli can appear to move more slowly when contrast is reduced (P. Thompson, 1982). Here we address the question whether changes in stimulus contrast also affect smooth pursuit eye movements. Subjects were asked to smoothly track a moving Gabor patch. Targets varied in velocity (1, 8, and 15 deg/s), spatial frequency (0.1, 1, 4, and 8 c/deg), and contrast, ranging from just below individual thresholds to maximum contrast. Results show that smooth pursuit eye velocity gain rose significantly with increasing contrast. Below a contrast level of two to three times threshold, pursuit gain, acceleration, latency, and positional accuracy were severely impaired. Therefore, the smooth pursuit motor response shows the same kind of slowing at low contrast that was demonstrated in previous studies on perception.

  12. Collapse dynamics of ultrasound contrast agent microbubbles

    Science.gov (United States)

    King, Daniel Alan

    Ultrasound contrast agents (UCAs) are micron-sized gas bubbles encapsulated with thin shells on the order of nanometers thick. The damping effects of these viscoelastic coatings are widely known to significantly alter the bubble dynamics for linear and low-amplitude behavior; however, their effects on strongly nonlinear and destruction responses are much less studied. This dissertation examines the behaviors of single collapsing shelled microbubbles using experimental and theoretical methods. The study of their dynamics is particularly relevant for emerging experimental uses of UCAs which seek to leverage localized mechanical forces to create or avoid specialized biomedical effects. The central component in this work is the study of postexcitation rebound and collapse, observed acoustically to identify shell rupture and transient inertial cavitation of single UCA microbubbles. This time-domain analysis of the acoustic response provides a unique method for characterization of UCA destruction dynamics. The research contains a systematic documentation of single bubble postexcitation collapse through experimental measurement with the double passive cavitation detection (PCD) system at frequencies ranging from 0.9 to 7.1 MHz and peak rarefactional pressure amplitudes (PRPA) ranging from 230 kPa to 6.37 MPa. The double PCD setup is shown to improve the quality of collected data over previous setups by allowing symmetric responses from a localized confocal region to be identified. Postexcitation signal percentages are shown to generally follow trends consistent with other similar cavitation metrics such as inertial cavitation, with greater destruction observed at both increased PRPA and lower frequency over the tested ranges. Two different types of commercially available UCAs are characterized and found to have very different collapse thresholds; lipid-shelled Definity exhibits greater postexcitation at lower PRPAs than albumin-shelled Optison. Furthermore, by altering

  13. Intraindividual assessment of the thoracic aorta using contrast and non-contrast-enhanced MR angiography

    International Nuclear Information System (INIS)

    Tengg-Kobligk, Hendrik von; Gruenberg, K.M.; Giesel, F.L.; Ley-Zaporozhan, J.; Ley, S.; Henninger, V.; Kauczor, H.U.; Radiologische Universitaetsklinik Heidelberg; Boeckler, D.; Krummenauer, F.

    2009-01-01

    To avoid intravenous contrast media application, new MRA sequences using inherent blood contrast are available. The clinical use of these non-contrast-enhanced MRA (non-CE-MRA) sequences is still limited for the aorta. Thus, the goal was to compare a standard CE-MRA with a non-CE-MRA for the thoracic aorta. Ethics committee approval and informed consent were obtained. CE-MRA and non-CE-MRA (1.5T) were performed in the same 50 healthy volunteers (mean age: 48). CE-MRA: GRE-Turbo-Flash-3D (1.2 x 1.2 x 1.6 mm 3 ), 0.15 mmol Gd/kg, TA 22 ± 2sec. Non-CE-MRA: Respiratory-and cardiac-gated, T 2-prepared 3D-trueFISP (1.2 x 1.2 x 1.3 mm 3 ), TA 14 ± 5 min. Assessment included (3 readers, consensus): image quality (sharpness of vessel wall, signal homogeneity, artifacts) at the ascending aorta, arch, descending aorta and supra-aortic vessels. The image quality in the ascending aorta was rated 'excellent' in 78 %, 'moderate' in 22 %, 'poor' in 0 % for non-CE-MRA versus 22 %, 50 %, and 28 % for CE-MRA (Cohen's kappa = 29 %, McNemar p < 0.001). In a comparison of non-CE-MRA versus CE-MRA, the aortic arch and descending aorta showed no significant difference (kappa = 58 %/p = 0.250 and kappa = 100 %/p 1.000, respectively). Supra-aortic vessels were rated 'excellent' 45 %/49 %, 'moderate' 30 %/49 % and 'poor' 13 %/2 %, 12 % of supra-aortic vessels were visualized < 1 cm at non-CE-MRA. (orig.)

  14. Dual Contrast - Magnetic Resonance Fingerprinting (DC-MRF): A Platform for Simultaneous Quantification of Multiple MRI Contrast Agents.

    Science.gov (United States)

    Anderson, Christian E; Donnola, Shannon B; Jiang, Yun; Batesole, Joshua; Darrah, Rebecca; Drumm, Mitchell L; Brady-Kalnay, Susann M; Steinmetz, Nicole F; Yu, Xin; Griswold, Mark A; Flask, Chris A

    2017-08-16

    Injectable Magnetic Resonance Imaging (MRI) contrast agents have been widely used to provide critical assessments of disease for both clinical and basic science imaging research studies. The scope of available MRI contrast agents has expanded over the years with the emergence of molecular imaging contrast agents specifically targeted to biological markers. Unfortunately, synergistic application of more than a single molecular contrast agent has been limited by MRI's ability to only dynamically measure a single agent at a time. In this study, a new Dual Contrast - Magnetic Resonance Fingerprinting (DC - MRF) methodology is described that can detect and independently quantify the local concentration of multiple MRI contrast agents following simultaneous administration. This "multi-color" MRI methodology provides the opportunity to monitor multiple molecular species simultaneously and provides a practical, quantitative imaging framework for the eventual clinical translation of molecular imaging contrast agents.

  15. Text accessibility by people with reduced contrast sensitivity.

    Science.gov (United States)

    Crossland, Michael D; Rubin, Gary S

    2012-09-01

    Contrast sensitivity is reduced in people with eye disease, and also in older adults without eye disease. In this article, we compare contrast of text presented in print and digital formats with contrast sensitivity values for a large cohort of subjects in a population-based study of older adults (the Salisbury Eye Evaluation). Contrast sensitivity values were recorded for 2520 adults aged 65 to 84 years living in Salisbury, Maryland. The proportion of the sample likely to be unable to read text of different formats (electronic books, newsprint, paperback books, laser print, and LED computer monitors) was calculated using published contrast reserve levels required to perform spot reading, to read with fluency, high fluency, and under optimal conditions. One percent of this sample had contrast sensitivity less than that required to read newsprint fluently. Text presented on an LED computer monitor had the highest contrast. Ninety-eight percent of the sample had contrast sensitivity sufficient for high fluent reading of text (at least 160 words/min) on a monitor. However, 29.6% were still unlikely to be able to read this text with optimal fluency. Reduced contrast of print limits text accessibility for many people in the developed world. Presenting text in a high-contrast format, such as black laser print on a white page, would increase the number of people able to access such information. Additionally, making text available in a format that can be presented on an LED computer monitor will increase access to written documents.

  16. Basic MR relaxation mechanisms and contrast agent design.

    Science.gov (United States)

    De León-Rodríguez, Luis M; Martins, André F; Pinho, Marco C; Rofsky, Neil M; Sherry, A Dean

    2015-09-01

    The diagnostic capabilities of magnetic resonance imaging (MRI) have undergone continuous and substantial evolution by virtue of hardware and software innovations and the development and implementation of exogenous contrast media. Thirty years since the first MRI contrast agent was approved for clinical use, a reliance on MR contrast media persists, largely to improve image quality with higher contrast resolution and to provide additional functional characterization of normal and abnormal tissues. Further development of MR contrast media is an important component in the quest for continued augmentation of diagnostic capabilities. In this review we detail the many important considerations when pursuing the design and use of MR contrast media. We offer a perspective on the importance of chemical stability, particularly kinetic stability, and how this influences one's thinking about the safety of metal-ligand-based contrast agents. We discuss the mechanisms involved in MR relaxation in the context of probe design strategies. A brief description of currently available contrast agents is accompanied by an in-depth discussion that highlights promising MRI contrast agents in the development of future clinical and research applications. Our intention is to give a diverse audience an improved understanding of the factors involved in developing new types of safe and highly efficient MR contrast agents and, at the same time, provide an appreciation of the insights into physiology and disease that newer types of responsive agents can provide. © 2015 Wiley Periodicals, Inc.

  17. [The influence of printing technology conditions on the accuracy and reproducibility of printed contrast panels for assessing contrast sensitivity].

    Science.gov (United States)

    Raabe, T; Jung, U; Wilhelm, H

    2014-08-01

    Contrast studies can provide important knowledge for treatment decisions before surgery or for assessing the driving ability of professional drivers. Accordingly, high demands are placed on contrast panels to obtain reliable and reproducible results. The aim of the study is to find out if the contrast panels on the market meet the requirements. On the basis of measurement evaluation and schematic presentations potential sources of error can be identified. These sources of error may have a decisive influence on the assessment of contrast vision. Far-reaching analyses have shown that three parameters can have a significant influence on the accuracy and reproducibility of printed contrast panels. This holds for certain properties of the printing substrate, the type of representation of display element, and the choice of the colourant. Only the correct interaction between the substrate and the print colour effects an angle-independent contrast. A matt substrate is necessary, which has a low difference to the printed contrast element in respect of glow, so that possible angle differences have no influence on the contrast assessment. The contrast elements of a contrast panel vary in brightness. Conventional methods for typographical representation of different brightnesses use the method of screening. This causes undesirable edges, which weaken in particular the lower-contrast elements unintentionally. Use of special colours can avoid this effect. In the visible wavelength range the studied contrast elements have an irregular absorption behaviour. Because of differences between the lighting surroundings, this can lead to a differentiated stimulation of cones in practice. Appropriate colourants have a constant absorption behaviour. To get representative results of contrast studies the production of contrast panels needs more knowledge about the interaction between paper and colour than is typically required for print products. On the basis of a prototype optimisation

  18. Contrast timing in computed tomography: Effect of different contrast media concentrations on bolus geometry

    International Nuclear Information System (INIS)

    Mahnken, Andreas H.; Jost, Gregor; Seidensticker, Peter; Kuhl, Christiane; Pietsch, Hubertus

    2012-01-01

    Objective: To assess the effect of low-osmolar, monomeric contrast media with different iodine concentrations on bolus shape in aortic CT angiography. Materials and methods: Repeated sequential computed tomography scanning of the descending aorta of eight beagle dogs (5 male, 12.7 ± 3.1 kg) was performed without table movement with a standardized CT scan protocol. Iopromide 300 (300 mg I/mL), iopromide 370 (370 mg I/mL) and iomeprol 400 (400 mg I/mL) were administered via a foreleg vein with an identical iodine delivery rate of 1.2 g I/s and a total iodine dose of 300 mg I/kg body weight. Time-enhancement curves were computed and analyzed. Results: Iopromide 300 showed the highest peak enhancement (445.2 ± 89.1 HU), steepest up-slope (104.2 ± 17.5 HU/s) and smallest full width at half maximum (FWHM; 5.8 ± 1.0 s). Peak enhancement, duration of FWHM, enhancement at FWHM and up-slope differed significantly between iopromide 300 and iomeprol 400 (p 0.05). Conclusions: Low viscous iopromide 300 results in a better defined bolus with a significantly higher peak enhancement, steeper up-slope and smaller FWHM when compared to iomeprol 400. These characteristics potentially affect contrast timing.

  19. Human cerebral blood volume measurements using dynamic contrast enhancement in comparison to dynamic susceptibility contrast MRI

    Energy Technology Data Exchange (ETDEWEB)

    Artzi, Moran [Tel Aviv Sourasky Medical Center, Functional Brain Center, The Wohl Institute for Advanced Imaging, Tel Aviv (Israel); Tel Aviv University, Sackler Faculty of Medicine, Tel Aviv (Israel); Liberman, Gilad; Vitinshtein, Faina; Aizenstein, Orna [Tel Aviv Sourasky Medical Center, Functional Brain Center, The Wohl Institute for Advanced Imaging, Tel Aviv (Israel); Nadav, Guy [Tel Aviv Sourasky Medical Center, Functional Brain Center, The Wohl Institute for Advanced Imaging, Tel Aviv (Israel); Tel Aviv University, Faculty of Engineering, Tel Aviv (Israel); Blumenthal, Deborah T.; Bokstein, Felix [Tel Aviv Sourasky Medical Center, Neuro-Oncology Service, Tel Aviv (Israel); Bashat, Dafna Ben [Tel Aviv Sourasky Medical Center, Functional Brain Center, The Wohl Institute for Advanced Imaging, Tel Aviv (Israel); Tel Aviv University, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv (Israel)

    2015-07-15

    Cerebral blood volume (CBV) is an important parameter for the assessment of brain tumors, usually obtained using dynamic susceptibility contrast (DSC) MRI. However, this method often suffers from low spatial resolution and high sensitivity to susceptibility artifacts and usually does not take into account the effect of tissue permeability. The plasma volume (v{sub p}) can also be extracted from dynamic contrast enhancement (DCE) MRI. The aim of this study was to investigate whether DCE can be used for the measurement of cerebral blood volume in place of DSC for the assessment of patients with brain tumors. Twenty-eight subjects (17 healthy subjects and 11 patients with glioblastoma) were scanned using DCE and DSC. v{sub p} and CBV values were measured and compared in different brain components in healthy subjects and in the tumor area in patients. Significant high correlations were detected between v{sub p} and CBV in healthy subjects in the different brain components; white matter, gray matter, and arteries, correlating with the known increased tissue vascularity, and within the tumor area in patients. This work proposes the use of DCE as an alternative method to DSC for the assessment of blood volume, given the advantages of its higher spatial resolution, its lower sensitivity to susceptibility artifacts, and its ability to provide additional information regarding tissue permeability. (orig.)

  20. Contrast-enhanced voiding urosonography: in vitro evaluation of a second-generation ultrasound contrast agent for in vivo optimization.

    Science.gov (United States)

    Back, Susan J; Edgar, J Christopher; Canning, Douglas A; Darge, Kassa

    2015-09-01

    Pediatric contrast-enhanced ultrasound (CEUS) is primarily performed outside the United States where a track record for safety in intravenous and intravesical applications has been established. Contrast-enhanced voiding urosonography (ceVUS) has also been shown to have a much higher rate of vesicoureteral reflux detection compared to voiding cystourethrography. US contrast agents available in the United States differ from those abroad. Optison® (GE Healthcare, Princeton, NJ) is such an US contrast agent. While Optison® has similar characteristics to other second-generation agents, it has never been used for ceVUS. In vitro optimization of dose and imaging parameters as well as assessment of contrast visualization when delivered in conditions similar to ceVUS are necessary starting points prior to in vivo applications. To optimize the intravesical use of Optison® in vitro for ceVUS before its use in pediatric studies. The experimental design simulated intravesical use. Using 9- and 12-MHz linear transducers, we scanned 20-mL syringes varying mechanical index, US contrast agent concentration (0.25%, 0.5%, 1.0%), solvent (saline, urine, radiographic contrast agent) and time out of refrigeration. We evaluated mechanical index settings and contrast duration, optimized the contrast dose, measured the effect of urine and radiographic contrast agent, and the impact of length of time of contrast outside of the refrigerator on US contrast appearance. We scanned 50-ml saline bags to assess the appearance and duration of US contrast with different delivery systems (injection vs. infusion). Consistent contrast visualization was achieved at a mechanical index of 0.06-0.17 and 0.11-0.48 for the L9 and L12 MHz transducers (P contrast visualization of the microbubbles with a higher transducer frequency. The lowest mechanical index for earliest visible microbubble destruction was 0.21 for the 9 MHz and 0.39 for the 12 MHz (P contrast agent volume to bladder filling was the

  1. Pharmacodynamics and tolerance of X-ray contrast media

    International Nuclear Information System (INIS)

    Schmiedel, E.

    1987-01-01

    The improved tolerance of nonionic contrast media compared with conventional contrast media is mainly due to their lower osmolality and reduced allergoid potential. Tolerance advantages that have been definitely proven are, for example, low-pain contrast medium injection and superior systemic tolerance; side effects of an allergic pattern occur less often. Animals experiments have established that nonionic contrast media exercise a comparatively lower influence on the cardiovascular system. The haemodynamics of pulmonary circulation are less adversely affected on intravenous bolus injection. Reduced potential risk is to be expected especially in cardiac and bronchopulmonary high-risk patients. The reduced nephrotoxicity of nonionic contrast media was definitely established by clinical studies. Further systematic studies will however be required to provide an answer to the question whether this also entails a reduction in the incidence of renal failures induced by contrast media. (orig.) [de

  2. Nonpharmacological Strategies to Prevent Contrast-Induced Acute Kidney Injury

    Directory of Open Access Journals (Sweden)

    Paweena Susantitaphong

    2014-01-01

    Full Text Available Contrast-induced AKI (CI-AKI has been one of the leading causes for hospital-acquired AKI and is associated with independent risk for adverse clinical outcomes including morbidity and mortality. The aim of this review is to provide a brief summary of the studies that focus on nonpharmacological strategies to prevent CI-AKI, including routine identification of at-risk patients, use of appropriate hydration regimens, withdrawal of nephrotoxic drugs, selection of low-osmolar contrast media or isoosmolar contrast media, and using the minimum volume of contrast media as possible. There is no need to schedule dialysis in relation to injection of contrast media or injection of contrast agent in relation to dialysis program. Hemodialysis cannot protect the poorly functioning kidney against CI-AKI.

  3. Effects of radiographic contrast media on the serum complement system

    International Nuclear Information System (INIS)

    Tirone, P.; Boldrini, E.

    1983-01-01

    The authors explored the activation of the complement system produced by a nonionic organic iodine compound, namely iopamidol, which is proposed as a contrast medium for radiographic examination by intravenous and intra-arterial injection. The study was conducted in vitro versus established ionic contrasts (diatrizoate, iothalamate, acetrizoate) and a nonionic compound (metrizamide). The adopted experimental model was the immunohemolytic detector system, in which the immune complex consisted of goat erythrocytes sensitized with the corresponding antibody (hemolysin), and complement (C') was supplied by guinea pig serum. All the products caused complement activation. The results show that nonionic contrast media produce less activation of the complement system than the traditional ionic contrast. Thus the use of nonionic contrast for radiological procedures necessitating the introduction of contrast material into the blood compartment would imply a reduced risk of anaphylactoid reactions. (orig.)

  4. Contrast media in diagnostic radiology. 3. rev. and enlarged ed.

    International Nuclear Information System (INIS)

    Elke, M.; Gueckel, C.; Schmitt, H.E.; Felder, E.; Froehlich, J.M.; Radue, E.W.; Scheidegger, D.; Speck, U.

    1992-01-01

    With the 3rd edition of this book a comprehensive description is provided of all the properties and side-effects of contrast media as well as of the available remedies in mishaps caused by these agents. The individual chapters are headed as follows: (s. table of contents). 1. Introduction. 2. Contrast media for X-ray radiography, MRT, and ultrasonic scanning. 3. Kinetics of X-ray contrast media. 4. Pharamcodynamics of X-ray contrast media. 5. Side-effects of X-ray contrast media and complications encountered in practical radiology. 6. The mobile reanimation unit and the emergency kit. 7. Treatment of reactions to contrast media. 8. Appendix. 9. Bibliography, subject index. (orig./MG) With 25 figs., 5 text tabs., 39 tabs [de

  5. Nephrogenic systemic fibrosis and gadolinium-based contrast media

    DEFF Research Database (Denmark)

    Thomsen, Henrik S; Morcos, Sameh K; Almén, Torsten

    2012-01-01

    PURPOSE: To update the guidelines of the Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) on nephrogenic systemic fibrosis and gadolinium-based contrast media. AREAS COVERED: Topics reviewed include the history, clinical features and prevalence of neph...... guidelines regarding gadolinium contrast agents minimises the risk of NSF • Potential long-term harm from gadolinium accumulation in the body is discussed.......PURPOSE: To update the guidelines of the Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) on nephrogenic systemic fibrosis and gadolinium-based contrast media. AREAS COVERED: Topics reviewed include the history, clinical features and prevalence...... of nephrogenic systemic fibrosis and the current understanding of its pathophysiology. The risk factors for NSF are discussed and prophylactic measures are recommended. The stability of the different gadolinium-based contrast media and the potential long-term effects of gadolinium in the body have also been...

  6. Sentinel node detection in melanomas using contrast-enhanced ultrasound

    DEFF Research Database (Denmark)

    Nielsen, K. Rue; Klyver, H.; Chakera, A. Hougaard

    2009-01-01

    in humans. PURPOSE: To investigate the possible use of CEUS in detecting SN in patients with malignant melanomas (MM), and to improve the method by using different concentrations of contrast agent and various positions of the extremity. MATERIAL AND METHODS: Ten patients with MM on an extremity and one...... healthy volunteer were included. One milliliter of a contrast agent (Sonovue; Bracco, Milan, Italy) was injected subcutaneously on both sides of the scar from the excised tumor. Contrast-enhanced lymph channels and lymph nodes (LNs) were searched for using low-mechanical-index CEUS and by stimulated...... tissue damage, as the contrast agent was not registered for subcutaneous administration. RESULTS: In one patient, two contrast-enhanced inguinal LNs were visualized by CEUS, corresponding to two inguinal SNs found by scintigraphic imaging. No contrast-enhanced lymph channels or LNs were visualized in any...

  7. Magnetic resonance imaging contrast agents: Overview and perspectives

    International Nuclear Information System (INIS)

    Yan Guoping; Robinson, Leslie; Hogg, Peter

    2007-01-01

    Magnetic resonance imaging (MRI) is a non-invasive clinical imaging modality, which has become widely used in the diagnosis and/or staging of human diseases around the world. Some MRI examinations include the use of contrast agents. The categorizations of currently available contrast agents have been described according to their effect on the image, magnetic behavior and biodistribution in the body, respectively. In this field, superparamagnetic iron oxide particles and soluble paramagnetic metal chelates are two main classes of contrast agents for MRI. This review outlines the research and development of MRI contrast agents. In future, the ideal MRI contrast agent will be focused on the neutral tissue- or organ-targeting materials with high relaxivity and specificity, low toxicity and side effects, suitable long intravascular duration and excretion time, high contrast enhancement with low dose in vivo, and with minimal cost

  8. Evaluation of oral abdominal contrast agent containing ferric ammonium citrate

    International Nuclear Information System (INIS)

    Shiga, Toshiko; Kawamura, Yasutaka; Iwasaki, Toshiko

    1991-01-01

    We evaluated the effectiveness of oral MRI contrast agent containing ferric ammonium citrate. Twenty patients were arbitrarily divided into 2 groups according to the given dose of 100 and 200 mg Fe of oral MRI contrast agent. MRI was performed before and immediately after ingesting 300 ml solution of oral MRI contrast agent using a 1.5 T superconducting system (GE: Signa). Each dose of 100 and 200 mg Fe of oral MRI contrast agent produced sufficient enhancement of gastrointestinal tract, enough to make clear the pancreatic contour and porta hepatis. There was no significant change in blood and urine analysis observed after taking oral MRI contrast agent. The use of ferric ammonium citrate as an oral MRI contrast agent seems to add valuable information in performing upper abdominal MRI imaging. (author)

  9. Comparative study of contrast dacryocystogram and nuclear dacryocystogram

    International Nuclear Information System (INIS)

    Chaudhuri, T.K.; Saparoff, G.R.; Dolan, K.D.; Chaudhuri, T.K.

    1975-01-01

    A comparative study was run between conventional radiographic contrast dacryocystogram and radioisotope scan of the lacrimal drainage apparatus (henceforth called ''nuclear dacryocystogram''). A total of 20 contrast dacryocystograms (DCG), 22 irrigations, and 42 nuclear dacryocystograms (DCG) were performed in 21 patients having symptoms of obstruction in the lacrimal drainage system. The study revealed that there was a good correlation between these two diagnostic techniques and nuclear DCG was, perhaps, superior to contrast DCG. (U.S.)

  10. Dual-energy contrast-enhanced spectral mammography (CESM).

    Science.gov (United States)

    Daniaux, Martin; De Zordo, Tobias; Santner, Wolfram; Amort, Birgit; Koppelstätter, Florian; Jaschke, Werner; Dromain, Clarisse; Oberaigner, Willi; Hubalek, Michael; Marth, Christian

    2015-10-01

    Dual-energy contrast-enhanced mammography is one of the latest developments in breast care. Imaging with contrast agents in breast cancer was already known from previous magnetic resonance imaging and computed tomography studies. However, high costs, limited availability-or high radiation dose-led to the development of contrast-enhanced spectral mammography (CESM). We reviewed the current literature, present our experience, discuss the advantages and drawbacks of CESM and look at the future of this innovative technique.

  11. Contrast media in urography, angiography and computerized tomography

    International Nuclear Information System (INIS)

    Taenzer, V.; Zeitler, E.

    1983-01-01

    The fact that new contrast media have been introduced in Germany or are currently undergoing clinical trials prompted the authors to assemble available experiences in a special edition of ''Roentgen-Fortschritte''. Particular prominence is given in the publication to preclinical and clinical experiences with another new non-ionic contrast medium, Iopromide. Experimental and clinical studies both indicate changes in certain clinically pertinent properties of the new contrast media. (orig./MG) [de

  12. Contrast media-associated nephrotoxicity - pathogenenesis and prevention

    International Nuclear Information System (INIS)

    Erley, C.M.; Duda, S.H.

    1997-01-01

    Contrast media-associated nephrotoxicity continues to be a relevant cause of acute renal failure, especially in patients with pre-existing renal insufficiency. Alterations in renal hemodynamics and direct tubular toxicity by contrast media are the primary factors believed to be responsible for contrast media-associated nephrotoxicity. We review recent insights into the pathogenesis of this complication and summarize prophylactic strategies focussing on hydration, vasoactive pharmacological agents, and prophylactic hemodialysis'. (orig.) [de

  13. Prevention of crackle in double contrast examinations of the colon

    International Nuclear Information System (INIS)

    Carvalho, A. de; Madsen, B.

    1981-01-01

    Crackle of the barium contrast during double contrast examinations of the colon probably results from a drying effect due to resoption of water. The duration of the examination should therefore be kept as short as possible and the patient should be well hydrated. The tendency to crackle can be decreased by increasing the molality of the barium enema by suspending barium contrast in 0.4% saline. (Auth.)

  14. Trends and developments in MRI contrast agent research

    International Nuclear Information System (INIS)

    Cavagna, F.M.; Dapra, M.; Castelli, P.M.; Maggioni, F.; Kirchin, M.A.

    1997-01-01

    The currently prevailing trends in industrial contrast agent research for MRI are discussed. Specific mention is made of contrast agents for liver imaging using both static and delayed procedures, of the potential for blood pool agents and the form such agents may take, and of the ultimate challenge for contrast agent R and D: tissue-targeting in a wider sense to both normal and pathologic tissues. (orig.)

  15. On the facular contrast near the solar limb

    International Nuclear Information System (INIS)

    Akimov, L.A.; Belkina, I.L.; Dyatel, N.P.; Marchenko, G.P.

    1987-01-01

    The photographic observations of facular contrasts in the continuum (λ ∼ 5400 A) for the interval of cos Θ ∼ 0.45-0.1, where Θ is the angular distance from the disk center are presented. It is obtained that the facular contrast function is not the same for faint and strong active regions. The mean contrast of faculae increases toward the limb. Previous observations of facular limb darkening are discussed

  16. Evaluation of contrast visual acuity in patients with retinitis pigmentosa

    Science.gov (United States)

    Oomachi, Kazumi; Ogata, Kazuha; Sugawara, Takeshi; Hagiwara, Akira; Hata, Akira; Yamamoto, Shuichi

    2011-01-01

    Background The purpose of this study was to determine visual acuity at different contrast levels under photopic and mesopic conditions in patients with retinitis pigmentosa. Methods Sixty eyes of 31 normal controls, 92 eyes of 52 patients with retinitis pigmentosa without other ocular disorders (RP-1 group), and 20 eyes of 14 patients with retinitis pigmentosa with cataracts and without other ocular disorders (RP-2 group) were studied. Conventional visual acuity was measured using a conventional Landolt ring chart with 100% contrast and luminance of 150 cd/m2. All of the patients with retinitis pigmentosa had a decimal visual acuity better than 1.0. Contrast visual acuity was measured with the same Landolt ring chart with contrasts of 100% and 10% and under photopic (200 cd/m2) and mesopic (10 cd/m2) conditions. Decimal visual acuities were converted to logMAR units for the analyses. Results The 100% contrast visual acuity and the 10% contrast visual acuity determined under both photopic and mesopic conditions were significantly poorer in both the RP-1 and RP-2 groups than in the controls. The differences between the conventional visual acuity and the 100% contrast visual acuity were significantly greater in the RP-1 and RP-2 groups than in the controls under both photopic and mesopic conditions. The differences between the 100% contrast visual acuity and the 10% contrast visual acuity were not significant among the three groups under photopic and mesopic conditions. Conclusion Contrast visual acuities were greatly reduced in patients with retinitis pigmentosa with relatively well preserved conventional visual acuity, and the contrast visual acuity was largely influenced by ambient light levels in patients with retinitis pigmentosa. Although a longitudinal study for confirmation has to be performed, our findings indicate that contrast visual acuity is a better test to follow changes in visual function in patients with retinitis pigmentosa. PMID:22069346

  17. Contrast enhancement of the gyri in herpes simplex encephalitis

    International Nuclear Information System (INIS)

    Schumacher, K.A.; Langer, M.; Langer, R.

    1982-01-01

    A case of herpes simplex encephalitis was examined by computer tomography. Both cerebral hemispheres showed contrast enhancement of the gyri. The cause of this is considered. The increased contrast medium accumulation in the affected areas is probably due to the marked vascular proliferation which can be demonstrated anatomically, and to the rapid escape of contrast from the capillaries into the interstitial spaces. The findings of other authors, which differ somewhat, are discussed. (orig.) [de

  18. Effect of iodinated contrast media on thyroid: a brief review

    Directory of Open Access Journals (Sweden)

    Şerife Mehlika Kuşkonmaz

    2016-04-01

    Full Text Available In parallel to the increased use of computed tomography, iodinated contrast agents are increasingly becoming a source of excess iodide. Iodinated contrast agents may induce thyroid dysfunction in exposed patients, especially in the presence of an underlying thyroid disease. Thus, an ordinary dose of the contrast used for the imaging, can induce hyper or hypothyroidism in a patient with subtle thyroid disease. This review will briefly discuss the physiology of iodine and the clinical evaluation of iodine induced thyroid dysfunction.

  19. Transparency perception: the key to understanding simultaneous color contrast.

    Science.gov (United States)

    Ekroll, Vebjørn; Faul, Franz

    2013-03-01

    The well-known simultaneous color contrast effect is traditionally explained in terms of visual color constancy mechanisms correcting for the confounding influence of ambient illumination on the retinal color signal. Recent research, however, suggests that the traditional gross quantitative laws of simultaneous color contrast, which are readily compatible with this functional explanation, should be revised and replaced by others, which are not readily understandable in terms of this perspective. Here, we show that the revised laws of simultaneous color contrast are well accounted for by an alternative theory explaining the simultaneous contrast effect in terms of mechanisms subserving the perception of transparent media.

  20. Prevention of adverse reactions to intravascular contrast media

    International Nuclear Information System (INIS)

    Soyer, P.; Levesque, M.

    1990-01-01

    The exact mechanisms of adverse reactions to contrast media are still imperfectly known. However, these reactions may be classified as idiosyncratic. Non-idiosyncratic reactions can be prevented by using new, non-ionic contrast agents. Idiosyncratic reactions can be prevented by specific premedication. Patients with a history of idiosyncratic reaction may benefit from corticosteroids and antihistamines administered prophylactically. Patients who seem to be more likely than others to react to contrast media must be premedicated, the risk of reaction being identified and evaluated by questioning. It has recently been suggested that all patients about to receive an intravascular injection of contrast medium should also be premedicated [fr

  1. Dendrimer-based Macromolecular MRI Contrast Agents: Characteristics and Application

    Directory of Open Access Journals (Sweden)

    Hisataka Kobayashi

    2003-01-01

    Full Text Available Numerous macromolecular MRI contrast agents prepared employing relatively simple chemistry may be readily available that can provide sufficient enhancement for multiple applications. These agents operate using a ~100-fold lower concentration of gadolinium ions in comparison to the necessary concentration of iodine employed in CT imaging. Herein, we describe some of the general potential directions of macromolecular MRI contrast agents using our recently reported families of dendrimer-based agents as examples. Changes in molecular size altered the route of excretion. Smaller-sized contrast agents less than 60 kDa molecular weight were excreted through the kidney resulting in these agents being potentially suitable as functional renal contrast agents. Hydrophilic and larger-sized contrast agents were found better suited for use as blood pool contrast agents. Hydrophobic variants formed with polypropylenimine diaminobutane dendrimer cores created liver contrast agents. Larger hydrophilic agents are useful for lymphatic imaging. Finally, contrast agents conjugated with either monoclonal antibodies or with avidin are able to function as tumor-specific contrast agents, which also might be employed as therapeutic drugs for either gadolinium neutron capture therapy or in conjunction with radioimmunotherapy.

  2. Cranial CT revisited: do we really need contrast enhancement?

    International Nuclear Information System (INIS)

    Demaerel, P.; Buelens, C.; Wilms, G.; Baert, A.L.

    1998-01-01

    The aim of this study was to define guidelines for intravenous contrast administration in cranial CT, as currently there are no recent guidelines based on a large series of patients. In 1900 consecutive patients (1480 adults and 420 children) pre- and post-contrast scan was analysed in order to assess the contribution of contrast enhancement to the diagnosis. The findings were grouped according to whether abnormalities were seen on the pre- and/or post-contrast scan, or whether no abnormalities were seen at all. Sensitivity, specificity, positive predictive value, negative predictive value and accurracy of a pre-contrast scan were used to determine validity. Intravenous contrast enhancement only contributes to the diagnosis if a suspicious abnormality is seen on the unenhanced scan or in the appropriate clinical setting (33.6 %). In the remaining patients (65.6 %) there is no diagnostic contribution, except for a small number of abnormalities (0.8 %). These are often anatomical variants and have no therapeutic impact. The number of contrast-enhanced cranial CT examinations can significantly be reduced by using four general guidelines for contrast administration resulting in considerable cost savings without affecting the quality of service to the patient. These guidelines are defined by the clinical findings/presentation or by the findings on the unenhanced scan. The number of contrast-related complications will be reduced, which may have medicolegal implications. These guidelines can be applied in any radiology department. (orig.) (orig.)

  3. Safety of Contrast Material Use During Pregnancy and Lactation.

    Science.gov (United States)

    Puac, Paulo; Rodríguez, Andrés; Vallejo, Carina; Zamora, Carlos A; Castillo, Mauricio

    2017-11-01

    The use of contrast media to image patients who are pregnant has increased during the past decades worldwide. Their use in pregnancy and in patients who are lactating remains a challenging issue for radiologists and other physicians. This article addresses the different types of contrast media that may be used in such patients according to the imaging modality (iodinated contrast media, barium, gadolinium-based, and ultrasound contrast agents), focusing on their adverse effects, potential teratogenic effects, strategies to minimize risks, and current clinical recommendation. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Effect of contrast media iodine concentration on bolus tracking

    International Nuclear Information System (INIS)

    Ishihara, Toshihiro; Hayashi, Takayuki; Nakaya, Yoshihiro; Naoi, Kuniji; Ikeno, Naoya; Kobayashi, Tatsushi; Satake, Mitsuo

    2006-01-01

    Computer-assisted bolus tracking has been confirmed to be a useful technique in computed tomography (CT) imaging and allows images to be captured with automated timing. The inflow of the contrast medium is monitored, and when the contrast medium reaches a predetermined level, CT image capture starts automatically. However, it has been shown that the preset threshold value of contrast medium is affected by its iodine concentration, which causes variations in image capture times. Greater speed in current multislice CT imaging requires that medical technicians pay more attention to setting the timing of image capture during venous examinations by taking into account the iodine concentration in contrast media. (author)

  5. Nanoparticle Contrast Agents for Computed Tomography: A Focus on Micelles

    Science.gov (United States)

    Cormode, David P.; Naha, Pratap C.; Fayad, Zahi A.

    2014-01-01

    Computed tomography (CT) is an X-ray based whole body imaging technique that is widely used in medicine. Clinically approved contrast agents for CT are iodinated small molecules or barium suspensions. Over the past seven years there has been a great increase in the development of nanoparticles as CT contrast agents. Nanoparticles have several advantages over small molecule CT contrast agents, such as long blood-pool residence times, and the potential for cell tracking and targeted imaging applications. Furthermore, there is a need for novel CT contrast agents, due to the growing population of renally impaired patients and patients hypersensitive to iodinated contrast. Micelles and lipoproteins, a micelle-related class of nanoparticle, have notably been adapted as CT contrast agents. In this review we discuss the principles of CT image formation and the generation of CT contrast. We discuss the progress in developing non-targeted, targeted and cell tracking nanoparticle CT contrast agents. We feature agents based on micelles and used in conjunction with spectral CT. The large contrast agent doses needed will necessitate careful toxicology studies prior to clinical translation. However, the field has seen tremendous advances in the past decade and we expect many more advances to come in the next decade. PMID:24470293

  6. The optimal use of contrast agents at high field MRI

    International Nuclear Information System (INIS)

    Trattnig, Siegfried; Pinker, Kathia; Ba-Ssalamah, Ahmed; Noebauer-Huhmann, Iris-Melanie

    2006-01-01

    The intravenous administration of a standard dose of conventional gadolinium-based contrast agents produces higher contrast between the tumor and normal brain at 3.0 Tesla (T) than at 1.5 T, which allows reducing the dose to half of the standard one to produce similar contrast at 3.0 T compared to 1.5 T. The assessment of cumulative triple-dose 3.0 T images obtained the best results in the detection of brain metastases compared to other sequences. The contrast agent dose for dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging at 3.0 T can be reduced to 0.1 mmol compared to 0.2 mmol at 1.5 T due to the increased susceptibility effects at higher magnetic field strengths. Contrast agent application makes susceptibility-weighted imaging (SWI) at 3.0 T clinically attractive, with an increase in spatial resolution within the same scan time. Whereas a double dose of conventional gadolinium-based contrast agents was optimal in SWI with respect to sensitivity and image quality, a standard dose of gadobenate dimeglumine, which has a two-fold higher T1-relaxivity in blood, produced the same effect. For MR-arthrography, optimized concentrations of gadolinium-based contrast agents are similar at 3.0 and 1.5 T. In summary, high field MRI requires the optimization of the contrast agent dose in different clinical applications. (orig.)

  7. Improved specimen reconstruction by Hilbert phase contrast tomography.

    Science.gov (United States)

    Barton, Bastian; Joos, Friederike; Schröder, Rasmus R

    2008-11-01

    The low signal-to-noise ratio (SNR) in images of unstained specimens recorded with conventional defocus phase contrast makes it difficult to interpret 3D volumes obtained by electron tomography (ET). The high defocus applied for conventional tilt series generates some phase contrast but leads to an incomplete transfer of object information. For tomography of biological weak-phase objects, optimal image contrast and subsequently an optimized SNR are essential for the reconstruction of details such as macromolecular assemblies at molecular resolution. The problem of low contrast can be partially solved by applying a Hilbert phase plate positioned in the back focal plane (BFP) of the objective lens while recording images in Gaussian focus. Images recorded with the Hilbert phase plate provide optimized positive phase contrast at low spatial frequencies, and the contrast transfer in principle extends to the information limit of the microscope. The antisymmetric Hilbert phase contrast (HPC) can be numerically converted into isotropic contrast, which is equivalent to the contrast obtained by a Zernike phase plate. Thus, in-focus HPC provides optimal structure factor information without limiting effects of the transfer function. In this article, we present the first electron tomograms of biological specimens reconstructed from Hilbert phase plate image series. We outline the technical implementation of the phase plate and demonstrate that the technique is routinely applicable for tomography. A comparison between conventional defocus tomograms and in-focus HPC volumes shows an enhanced SNR and an improved specimen visibility for in-focus Hilbert tomography.

  8. Contrast media in renal insufficiency - risk and prevention

    International Nuclear Information System (INIS)

    Erley, C.M.; Bader, B.D.

    2000-01-01

    The use of iodinated contrast media (CM) continues to be a common cause of hospital-acquired acute renal failure (ARF) and its development increases the in-hospital mortality significantly. Alterations in renal hemodynamics and direct tubular toxicity by contrast media are the primary factors believed to be responsible for contrast media-associated nephrotoxicity. We review recent insights into the pathogenesis of this complication and summarize prophylacttic strategies focussing on hydration, vasoactive pharmacological agents, alternative contrast media and 'prophylactic hemodialysis'. (orig.) [de

  9. Risk of application of contrast medium in computed tomography

    International Nuclear Information System (INIS)

    Wende, S.; Speck, U.; Schering A.G., Berlin

    1981-01-01

    The paper deals with the risk associated with the application of contrast medium in CT. The risk is to be seen in intolerance reactions, such as allergic or circulatory reactions and neurotoxic side-effects. In this paper the problems of renal failure caused by the injection of contrast medium are given special attention. Furthermore an iodine-induced hyperthyreosis might result. Especially the possible disturbance of the kidney function means that contrast medium should not be applied arbitrarily and that the examination should be done only by experienced staff. Furthermore the indication for the application of contrast medium in CT should be strictly qualified. (orig.) [de

  10. Risk of application of contrast medium in computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Wende, S.; Speck, U.

    1981-06-01

    The paper deals with the risk associated with the application of contrast medium in CT. The risk is to be seen in intolerance reactions, such as allergic or circulatory reactions and neurotoxic side-effects. In this paper the problems of renal failure caused by the injection of contrast medium are given special attention. Furthermore an iodine-induced hyperthyreosis might result. Especially the possible disturbance of the kidney function means that contrast medium should not be applied arbitrarily and that the examination should be done only by experienced staff. Furthermore the indication for the application of contrast medium in CT should be strictly qualified.

  11. Refraction-contrast bone imaging using synchrotron radiation

    International Nuclear Information System (INIS)

    Mori, Koichi; Sekine, Norio; Sato, Hitoshi; Shikano, Naoto; Shimao, Daisuke; Shiwaku, Hideaki; Hyodo, Kazuyuki; Oka, Hiroshi

    2002-01-01

    The X-ray refraction-contrast imaging using synchrotron radiation with some X-ray energies is successfully performed at B120B2 of SPring-8. The refraction-contrast images of bone samples such as human dried proximal phalanx, wrist, upper cervical vertebrae and sella turcica and as mouse proximal femur using the synchrotron X-ray are always better in image contrast and resolution than those of the absorption-contrast images using the synchrotron X-ray and/or the conventional X-ray tube. There is much likeness in the image contrast and resolution of trabeculae bone in the human dried proximal phalanx between X-ray energy of 30 keV at sample-to-film distance of 1 m and those of 40, 50 keV at those of 4,5 m, respectively. High-energy refraction-contrast imaging with suitable sample-to-film distance could reduce the exposure dose in human imaging. In the refraction-contrast imaging of human wrist, upper cervcal vertebrae, sella turcica and mouse proximal femur using the synchrotron X-ray, we can obtain better image contrast and resolution to correctly extract morphological information for diagnosis corresponding to each of the clinical field than those of the absorption-contrast images. (author)

  12. Enhancement pattern of hilar cholangiocarcinoma: Contrast-enhanced ultrasound versus contrast-enhanced computed tomography

    International Nuclear Information System (INIS)

    Xu Huixiong; Chen Lida; Xie Xiaoyan; Xie Xiaohua; Xu Zuofeng; Liu Guangjian; Lin Manxia; Wang Zhu; Lu Mingde

    2010-01-01

    Objective: To compare the enhancement pattern of hilar cholangiocarcinoma on contrast-enhanced ultrasound (CEUS) with that on contrast-enhanced computed tomography (CECT). Methods: Thirty-two consecutive patients with pathologically proven hilar cholangiocarcinomas were evaluated by both low mechanical index CEUS and CECT. The enhancement feature of the tumor, portal vein infiltration, and lesion conspicuity on them was investigated. Results: In the arterial phase, the numbers of the lesions showing hyperenhancement, isoenhancement, and hypoenhancement, were 14 (43.8%), 14 (43.8%), and 4 (12.6%), on CEUS, and 12 (37.5%), 9 (28.1%), and 11 (34.4%), on CECT (P = 0.162). In portal phase, the numbers of the lesions showing hypoenhancement, isoenhancement, and hyperenhancement were 30 (93.8%), 1 (3.1%), and 1 (3.1%), on CEUS, and 23 (71.9%), 8 (25.0%), and 1 (3.1%), on CECT (P = 0.046). The detection rates for portal vein infiltration were 84.2% (16/19) for baseline ultrasound, 89.5% (17/19) for CEUS, and 78.9% (15/19) for CECT (all P > 0.05 between every two groups). CEUS significantly improved the lesion conspicuity in comparison with CECT. CEUS and CECT made correct diagnoses in 30 (93.8%) and 25 (78.1%) lesions prior to pathological examination (P = 0.125). Conclusion: The enhancement pattern of hilar cholangiocarcinoma on CEUS was similar with that on CECT in arterial phase, whereas in portal phase hilar cholangiocarcinoma shows hypoenhancement more likely on CEUS. CEUS and CECT lead to similar results in evaluating portal vein infiltration and diagnosis of this entity.

  13. Enhancement pattern of hilar cholangiocarcinoma: Contrast-enhanced ultrasound versus contrast-enhanced computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Xu Huixiong, E-mail: xuhuixiong@hotmail.co [Department of Medical Ultrasonics, The First Affiliated Hospital, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, 58 Zhongshan Road 2, Guangzhou 510080 (China); Chen Lida; Xie Xiaoyan; Xie Xiaohua; Xu Zuofeng; Liu Guangjian; Lin Manxia; Wang Zhu [Department of Medical Ultrasonics, The First Affiliated Hospital, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, 58 Zhongshan Road 2, Guangzhou 510080 (China); Lu Mingde, E-mail: lumd@21cn.co [Department of Hepatobiliary Surgery, First Affiliated Hospital, Sun Yat-Sen University, 58 Zhongshan Road 2, Guangzhou 510080 (China)

    2010-08-15

    Objective: To compare the enhancement pattern of hilar cholangiocarcinoma on contrast-enhanced ultrasound (CEUS) with that on contrast-enhanced computed tomography (CECT). Methods: Thirty-two consecutive patients with pathologically proven hilar cholangiocarcinomas were evaluated by both low mechanical index CEUS and CECT. The enhancement feature of the tumor, portal vein infiltration, and lesion conspicuity on them was investigated. Results: In the arterial phase, the numbers of the lesions showing hyperenhancement, isoenhancement, and hypoenhancement, were 14 (43.8%), 14 (43.8%), and 4 (12.6%), on CEUS, and 12 (37.5%), 9 (28.1%), and 11 (34.4%), on CECT (P = 0.162). In portal phase, the numbers of the lesions showing hypoenhancement, isoenhancement, and hyperenhancement were 30 (93.8%), 1 (3.1%), and 1 (3.1%), on CEUS, and 23 (71.9%), 8 (25.0%), and 1 (3.1%), on CECT (P = 0.046). The detection rates for portal vein infiltration were 84.2% (16/19) for baseline ultrasound, 89.5% (17/19) for CEUS, and 78.9% (15/19) for CECT (all P > 0.05 between every two groups). CEUS significantly improved the lesion conspicuity in comparison with CECT. CEUS and CECT made correct diagnoses in 30 (93.8%) and 25 (78.1%) lesions prior to pathological examination (P = 0.125). Conclusion: The enhancement pattern of hilar cholangiocarcinoma on CEUS was similar with that on CECT in arterial phase, whereas in portal phase hilar cholangiocarcinoma shows hypoenhancement more likely on CEUS. CEUS and CECT lead to similar results in evaluating portal vein infiltration and diagnosis of this entity.

  14. Neuroimaging: do we really need new contrast agents for MRI?

    International Nuclear Information System (INIS)

    Roberts, T.P.L.; Chuang, N.; Roberts, H.C.

    2000-01-01

    The use of exogenous contrast media in magnetic resonance imaging of the brain has brought dramatic improvement in the sensitivity of detection and delineation of pathological structures, such as primary and metastatic brain tumors, inflammation and ischemia. Disruption of the blood brain barrier leads to accumulation of the intravenously injected contrast material in the extravascular space, leading to signal enhancement. Magnetic resonance angiography benefits from T 1 -shortening effects of contrast agent, improving small vessel depiction and providing vascular visualization even in situations of slow flow. High speed dynamic MRI after bolus injection of contrast media allows tracer kinetic modeling of cerebral perfusion. Progressive enhancement over serial post-contrast imaging allows modeling of vascular permeability and thus quantitative estimation of the severity of blood brain barrier disruption. With such an array of capabilities and ever improving technical abilities, it seems that the role of contrast agents in MR neuroimaging is established and the development of new agents may be superfluous. However, new agents are being developed with prolonged intravascular residence times, and with in-vivo binding of ever-increasing specificity. Intravascular, or blood pool, agents are likely to benefit magnetic resonance angiography of the carotid and cerebral vessels; future agents may allow the visualization of therapeutic drug delivery, the monitoring of, for example, gene expression, and the imaging evaluation of treatment efficacy. So while there is a substantial body of work that can be performed with currently available contrast agents, especially in conjunction with optimized image acquisition strategies, post processing, and mathematical analysis, there are still unrealized opportunities for novel contrast agent introduction, particularly those exploiting biological specificity. This article reviews the current use of contrast media in magnetic resonance

  15. Influence of contrast agent dose and ultrasound exposure on cardiomyocyte injury induced by myocardial contrast echocardiography in rats.

    Science.gov (United States)

    Miller, Douglas L; Li, Peng; Dou, Chunyan; Gordon, David; Edwards, Chris A; Armstrong, William F

    2005-10-01

    To detect specific cardiomyocyte injury induced by myocardial contrast material-enhanced echocardiography (ie, myocardial contrast echocardiography) in rats and to ascertain the influences of contrast material dose and ultrasound exposure on this injury. All animal procedures were approved by the university committee for the use and care of animals. Myocardial contrast echocardiography with 1:4 electrocardiographic (ECG) triggering was performed at 1.5 MHz in 61 anesthetized rats. Evans blue (EB) dye was injected as the vital stain for cardiomyocyte injury. At the start of myocardial contrast echocardiography, which lasted 10 minutes, perflutren lipid microsphere-based contrast material was infused through the tail vein for 5 minutes. Premature heartbeats were counted from the ECG record. The numbers of EB-stained cells counted on sections of heart specimens obtained 24 hours after myocardial contrast echocardiography and then either fresh frozen or embedded in paraffin were determined by using fluorescence microscopy. Results were compared statistically by using t tests and Mann-Whitney rank sum tests. EB-stained cells were concentrated in the anterior region of the myocardium. In the paraffin-embedded specimens, EB-stained cells were often accompanied by but largely separate from areas of inflammatory cell infiltration. At end-systolic triggering with a 50 microL/kg dose of microsphere contrast material, the EB-stained cell count increased with increasing peak rarefactional pressure amplitude, with significantly increased cell counts at 1.6 MPa (P .1). EB-stained cell counts increased with increasing contrast material dose, from 10 to 50 microL/kg, at 2.0 MPa. Cardiomyocyte injury was induced by the interaction of ultrasound pulses with contrast agent microbubbles during myocardial contrast echocardiography in rats, and the numbers of injured cells increased with increasing contrast agent dose and ultrasound exposure. RSNA, 2005

  16. Contrast amplification of the liver parenchyma in the computer tomogram by using intravenous and peroral biliary contrast media

    International Nuclear Information System (INIS)

    Justich, E.; Sager, W.D.; Dietrich, G.; Fotter, R.; Nedden, D. zur; Innsbruck Univ.

    1980-01-01

    If intravenous, biliary contrast media are used, a slight albeit specific enhancement of contrast of the liver parenchyma occurs with the applied dosage, which can be utilised in individual cases, for example for identifying isodense lesions. Contrast amplification by the peroral cholegraphic agent under examination, is insufficient for use in computer tomography of the liver. The use of biliary contrast media usually enables very good visualisation of the extrahepatic bile ducts. Attention is drawn to the possibility of pharmakokinetic studies by means of computer tomography. (orig.) [de

  17. Correlation of contrast agent kinetics between iodinated contrast-enhanced spectral tomosynthesis and gadolinium-enhanced MRI of breast lesions

    International Nuclear Information System (INIS)

    Froeling, Vera; Diekmann, Felix; Renz, Diane M.; Fallenberg, Eva M.; Steffen, Ingo G.; Diekmann, Susanne; Schmitzberger, Florian F.; Lawaczeck, Ruediger

    2013-01-01

    Assessment of contrast agent kinetics in contrast-enhanced MRI (CE-MRI) with gadolinium-containing contrast agents offers the opportunity to predict breast lesion malignancy. The goal of our study was to determine if similar patterns exist for spectral contrast-enhanced digital breast tomosynthesis (CE-DBT) using an iodinated contrast agent. The protocol of our prospective study was approved by the relevant institutional review board and the German Federal Office for Radiation Protection. All patients provided written informed consent. We included 21 women with a mean age of 62.4 years. All underwent ultrasound-guided biopsy of a suspect breast lesion, spectral CE-DBT and CE-MRI. For every breast lesion, contrast agent kinetics was assessed by signal intensity-time curves for spectral CE-DBT and CE-MRI. Statistical comparison used Cohen's kappa and Spearman's rho test. Spearman's rho of 0.49 showed significant (P = 0.036) correlation regarding the contrast agent kinetics in signal intensity-time curves for spectral CE-DBT and CE-MRI. Cohen's kappa indicated moderate agreement (kappa = 0.438). There is a statistically significant correlation between contrast agent kinetics in the signal intensity-time curves for spectral CE-DBT and CE-MRI. Observing intralesional contrast agent kinetics in spectral CE-DBT may aid evaluation of malignant breast lesions. (orig.)

  18. Ionic and non-ionic contrast media used for contrast-enhanced computed tomography in experimental pancreatitis

    International Nuclear Information System (INIS)

    Kivisaari, L.; Nuutinen, P.; Lehtola, A.; Saari, A.; Pitkaeranta, P.; Standertskjoeld-Nordenstam, C.G.; Lempinen, M.; Schroeder, T.; Helsinki Univ. Central Hospital

    1988-01-01

    Contrast enhancement of the pancreas was studied in pigs using dynamic computed tomography in experimental oedematous and haemorrhagic/necrotizing pancreatitis during the first two minutes after injection of an intravenous bolus of non-ionic contrast medium (iohexol). The prospects of separating the two forms of the disease, known to be possible with ionic contrast media, were tested with a non-ionic contrast medium. In the oedematous form, contrast enhancement after 5 hours of the disease was significantly higher than in the haemorrhagic/necrotizing form. Contrast enhancement after 30 hours of disease tended to vary with the severity of the disease, showing that the course of oedematous pancreatitis is dynamic. Intermediate forms occur and follow-up studies are needed during the disease. A non-ionic contrast medium proved as good for separating the two forms of the disease in the early phase as were ionic contrast media. In severely ill patients, non-ionic contrast media should therefore be used. (orig.)

  19. Recent advances in contrast-enhanced magnetic resonance angiography

    International Nuclear Information System (INIS)

    Meaney, J.F.M.; Goyen, M.

    2007-01-01

    Magnetic resonance angiography (MRA) provides a means of visualizing vascular structures noninvasively and is increasingly replacing conventional X-ray angiography in routine use. Contrast-enhanced MRA (CE-MRA), in which gadolinium contrast agents are used to shorten the T1 relaxation, offers increased resolution and higher signal-to-noise ratio compared with earlier flow-dependent [time-of-flight (TOF) or phase-contrast (PC)] techniques. Currently available contrast agents differ in their ability to lower T1 values, and hence the choice of contrast agent is an important consideration in the successful use of CE-MRA. Gadofosveset trisodium (Vasovist, Bayer Schering Pharma AG, Berlin, Germany) is the first of a new class of intravascular contrast agents. This agent is extensively (approximately 85%) and reversibly bound to human serum albumin and is retained within the vasculature thus allowing steady-state imaging to be perform-ed. An additional benefit is that gado0fosveset offers higher relaxivity compared with other contrast agents, thus giving a lower blood T1 values which also makes it ideal for first-pass imaging. Clinical trials have consistently shown that gadofosveset enhanced MRA is more sensitive, specific and accurate than time-of-flight MRA, gives fewer uninterpretable scans and affords greater diagnostic confidence. Intravascular contrast agents such as gadofosveset, therefore, offer the potential for improved vascular imaging. (orig.)

  20. Spatial Long-Range Modulation of Contrast Discrimination

    Science.gov (United States)

    2000-07-01

    details. power p and then divided by the divisive 91 inhibitory input (I) plus an additive constant. That is, R EPR = -- (1) I+a where c is an...contrast and contrast discrimination. Vision Research, 38, 1935 -1945. 18. Solomon, J. A., Watson, A. B. & Morgan, M. J. (1999). Transducer model produces

  1. Contrast-induced nephrotoxicity: possible synergistic effect of stress hyperglycemia.

    LENUS (Irish Health Repository)

    O'Donnell, David H

    2010-07-01

    Oxidative stress on the renal tubules has been implicated as a mechanism of injury in both stress hyperglycemia and contrast-induced nephrotoxicity. The purpose of this study was to determine whether the combination of these effects has a synergistic effect on accentuating renal tubular apoptosis and therefore increasing the risk of contrast-induced nephrotoxicity.

  2. Safety of ultrasound contrast agents in stress echocardiography.

    Science.gov (United States)

    Gabriel, Ruvin S; Smyth, Yvonne M; Menon, Venu; Klein, Allan L; Grimm, Richard A; Thomas, James D; Sabik, Ellen Mayer

    2008-11-01

    Definity and Optison are perflutren-based ultrasound contrast agents used in echocardiography. United States Food and Drug Administration warnings regarding serious cardiopulmonary reactions and death after Definity administration highlighted the limited safety data in patients who undergo contrast stress echocardiography. From 1998 and 2007, 2,022 patients underwent dobutamine stress echocardiography and 2,764 underwent exercise stress echocardiography with contrast at the Cleveland Clinic. The echocardiographic database, patient records, and the Social Security Death Index were reviewed for the timing and cause of death, severe adverse events, arrhythmias, and symptoms. Complication rates for contrast dobutamine stress echocardiography and exercise stress echocardiography were compared with those in a control group of 5,012 patients matched for test year and type who did not receive contrast. Ninety-five percent of studies were performed in outpatients. There were no differences in the rates of severe adverse events (0.19% vs 0.17%, p = 0.7), death within 24 hours (0% vs 0.04%, p = 0.1), cardiac arrest (0.04% vs 0.04%, p = 0.96), and sustained ventricular tachycardia (0.2% vs 0.1%, p = 0.32) between patients receiving and not receiving intravenous contrast, respectively. In conclusion, severe adverse reactions to intravenous contrast agents during stress echocardiography are uncommon. Contrast use does not add to the baseline risk for severe adverse events in patients who undergo stress echocardiography.

  3. Intravenous carbon dioxide as an echocardiographic contrast agent

    NARCIS (Netherlands)

    R.S. Meltzer (Richard); P.W.J.C. Serruys (Patrick); P.G. Hugenholtz (Paul); J.R.T.C. Roelandt (Jos)

    1981-01-01

    textabstractIntravenous carbon dioxide (CO2) was employed to cause echocardiographic contrast in 40 patients. One to 3 cc of medically pure CO2 were agitated with 5 to 8 cc of 5% dextrose in water and rapidly injected into an upper extremity vein. Contrast was obtained in all patients. In 33

  4. Is contrast-enhanced CT indicated in acute head injury

    International Nuclear Information System (INIS)

    Mauser, H.W.; Nieuwenhuizen, O. van; Veiga-Pires, J.A.

    1984-01-01

    The authors discuss the value of intravenous contrast enhancement in CT scanning in acute head injury. In a series of seventy consecutive patients they conclude that no incremental information was obtained by performing contrast-enhanced CT scans in the acute phase of the head injury. (orig.)

  5. Asymptotic expansions for high-contrast linear elasticity

    KAUST Repository

    Poveda, Leonardo A.; Huepo, Sebastian; Calo, Victor M.; Galvis, Juan

    2015-01-01

    We study linear elasticity problems with high contrast in the coefficients using asymptotic limits recently introduced. We derive an asymptotic expansion to solve heterogeneous elasticity problems in terms of the contrast in the coefficients. We study the convergence of the expansion in the H1 norm. © 2015 Elsevier B.V.

  6. A contrast-enhanced ultrasound study of benign and malignant ...

    African Journals Online (AJOL)

    A contrast-enhanced ultrasound study of benign and malignant breast tissue. S Barnard, E Leen, T Cooke, W Angerson. Abstract. Objective. To determine the diagnostic value of haemodynamic contrast-enhanced ultrasound assessment in benign and malignant breast tissue, using histological examination as the reference ...

  7. Hemodynamic and tubular changes induced by contrast media.

    Science.gov (United States)

    Caiazza, Antonella; Russo, Luigi; Sabbatini, Massimo; Russo, Domenico

    2014-01-01

    The incidence of acute kidney injury induced by contrast media (CI-AKI) is the third cause of AKI in hospitalized patients. Contrast media cause relevant alterations both in renal hemodynamics and in renal tubular cell function that lead to CI-AKI. The vasoconstriction of intrarenal vasculature is the main hemodynamic change induced by contrast media; the vasoconstriction is accompanied by a cascade of events leading to ischemia and reduction of glomerular filtration rate. Cytotoxicity of contrast media causes apoptosis of tubular cells with consequent formation of casts and worsening of ischemia. There is an interplay between the negative effects of contrast media on renal hemodynamics and on tubular cell function that leads to activation of renin-angiotensin system and increased production of reactive oxygen species (ROS) within the kidney. Production of ROS intensifies cellular hypoxia through endothelial dysfunction and alteration of mechanisms regulating tubular cells transport. The physiochemical characteristics of contrast media play a critical role in the incidence of CI-AKI. Guidelines suggest the use of either isoosmolar or low-osmolar contrast media rather than high-osmolar contrast media particularly in patients at increased risk of CI-AKI. Older age, presence of atherosclerosis, congestive heart failure, chronic renal disease, nephrotoxic drugs, and diuretics may multiply the risk of CI-AKI.

  8. Effects of iodinated contrast media on blood and endothelium

    International Nuclear Information System (INIS)

    Aspelin, Peter; Stacul, Fulvio; Thomsen, Henrik S.; Morcos, Sameh K.; Molen, Aart J. van der

    2006-01-01

    The aim of the study was to assess the effects of iodinated contrast media on blood components and endothelium based on experimental and clinical studies and to produce clinically relevant guidelines for reducing thrombotic and hematologic complications following the intravascular use of contrast media. A report was drafted after review of the literature and discussions among the members of the Contrast Media Safety Committee of the European Society of Urogenital Radiology. The final report was produced following discussion at the 12th European Symposium on Urogenital Radiology in Ljubljana, Slovenia (2005). Experimental data indicate that all iodinated contrast media produce an anticoagulant effect and that this effect is greater with ionic contrast media. Several of the in vitro and experimental in vivo studies on haematological effects of contrast media have not been confirmed by clinical studies. Low- or iso-osmolar contrast media should be used for diagnostic and interventional angiographic procedures, including phlebography. Meticulous angiographic technique is the most important factor for reducing the thrombotic complications associated with angiographic procedures. Drugs and interventional devices that decrease the risk of thromboembolic complications during interventional procedures minimize the importance of the effects of contrast media. (orig.)

  9. Late adverse reactions to intravascular iodine based contrast media

    DEFF Research Database (Denmark)

    Bellin, Marie-France; Stacul, Fulvio; Webb, Judith A W

    2011-01-01

    DEFINITION: Late adverse reactions (LAR) to contrast media (CM) are defined as reactions occurring 1 h to 1 week after exposure. NEED FOR REVIEW: In view of more prospective studies of LAR and new data about their pathophysiology, the Contrast Medium Safety Committee (CMSC) of the European Societ...

  10. Effects of iodinated contrast media on blood and endothelium

    Energy Technology Data Exchange (ETDEWEB)

    Aspelin, Peter [Karolinska Institute/Huddinge University Hospital, Division of Radiology, Centre for Surgical Sciences, Stockholm (Sweden); Stacul, Fulvio [Institute of Radiology, Trieste (Italy); Thomsen, Henrik S. [Copenhagen University Hospital at Herlev, Department of Diagnostic Radiology 54E2, Herlev (Denmark); Morcos, Sameh K. [Sheffield Teaching Hospitals NHS Trust, Department of Diagnostic Imaging, Northern General Hospital, Sheffield (United Kingdom); Molen, Aart J. van der [Leiden University Medical Centre, Department of Radiology, Leiden (Netherlands)

    2006-05-15

    The aim of the study was to assess the effects of iodinated contrast media on blood components and endothelium based on experimental and clinical studies and to produce clinically relevant guidelines for reducing thrombotic and hematologic complications following the intravascular use of contrast media. A report was drafted after review of the literature and discussions among the members of the Contrast Media Safety Committee of the European Society of Urogenital Radiology. The final report was produced following discussion at the 12th European Symposium on Urogenital Radiology in Ljubljana, Slovenia (2005). Experimental data indicate that all iodinated contrast media produce an anticoagulant effect and that this effect is greater with ionic contrast media. Several of the in vitro and experimental in vivo studies on haematological effects of contrast media have not been confirmed by clinical studies. Low- or iso-osmolar contrast media should be used for diagnostic and interventional angiographic procedures, including phlebography. Meticulous angiographic technique is the most important factor for reducing the thrombotic complications associated with angiographic procedures. Drugs and interventional devices that decrease the risk of thromboembolic complications during interventional procedures minimize the importance of the effects of contrast media. (orig.)

  11. Contrast sensitivity function in Graves' ophthalmopathy and dysthyroid optic neuropathy

    NARCIS (Netherlands)

    Suttorp-Schulten, M. S.; Tijssen, R.; Mourits, M. P.; Apkarian, P.

    1993-01-01

    Contrast sensitivity function was measured by a computer automated method on 38 eyes with dysthyroid optic neuropathy and 34 eyes with Graves' ophthalmopathy only. The results were compared with 74 healthy control eyes. Disturbances of contrast sensitivity functions were found in both groups when

  12. Contrast echocardiography: history, micro bubble characteristics and instrumental techniques

    International Nuclear Information System (INIS)

    Cubides, Carlos; Restrepo, Gustavo; Aristizabal, Dagnovar; Munera, Ana

    2006-01-01

    This article describes the history of contrast echocardiography, the physical characteristics of the contrast agent's micro bubbles, the main instrumental tools (mechanical index, focus and focusing, frame rate), and the echocardiography techniques (second harmonic imaging, fusion harmonic, power pulse inversion imaging, triggered imaging, intermittent harmonic power Doppler, color power angio and acoustic densitometry), actually available for clinical use

  13. Reproducibility of contrast-enhanced transrectal ultrasound of the prostate

    NARCIS (Netherlands)

    Sedelaar, J. P.; Goossen, T. E.; Wijkstra, H.; de la Rosette, J. J.

    2001-01-01

    Transrectal three-dimensional (3-D) contrast-enhanced power Doppler ultrasound (US) is a novel technique for studying possible prostate malignancy. Before studies can be performed to investigate the clinical validity of the technique, reproducibility of the contrast US studies must be proven.

  14. Ultrasound-induced Gas Release from Contrast Agent Microbubbles

    NARCIS (Netherlands)

    Postema, M.A.B.; Postema, Michiel; Bouakaz, Ayache; Versluis, Michel; de Jong, N.

    2005-01-01

    We investigated gas release from two hard-shelled ultrasound contrast agents by subjecting them to high-mechanical index (MI) ultrasound and simultaneously capturing high-speed photographs. At an insonifying frequency of 1.7 MHz, a larger percentage of contrast bubbles is seen to crack than at 0.5

  15. Uncovering Contrast Categories in Categorization with a Probabilistic Threshold Model

    Science.gov (United States)

    Verheyen, Steven; De Deyne, Simon; Dry, Matthew J.; Storms, Gert

    2011-01-01

    A contrast category effect on categorization occurs when the decision to apply a category term to an entity not only involves a comparison between the entity and the target category but is also influenced by a comparison of the entity with 1 or more alternative categories from the same domain as the target. Establishing a contrast category effect…

  16. Contrast-enhanced MR angiography in Leriche's syndrome

    International Nuclear Information System (INIS)

    Link, J.; Steffens, J.C.; Brossmann, J.; Heller, M.; Loose, R.

    1998-01-01

    Purpose: To determine the usefulness of contrast-enhanced MR angiography for the diagnosis of Leriche's syndrome. Material and methods: Leriche's syndrome was seen in 7 patients via DSA. In [dition, contrast-enhanced MR angiography was performed (T R 7.8 ms/T E 2.1 ms, flip angle 30 , slab thickness 116 mm, slice thickness 1.82 mm, 64 partitions, FOV 500x438 mm, matrix 224x512). Results: Diagnosis of Leriche's syndrome was possible by contrast-enhanced MR angiography in each case. Visualisation of the femoral arteries was not possible in two patients by intraarterial DSA, in three other patients there was an insufficient contrast in the femoral arteries with DSA. Contrast-enhanced MR angiography revealed good visualisation of the femoral arteries in these patients. In [dition, contrast-enhanced MR angiography allowed complete visualisation of the patent lower limb arteries. In intraarterial DSA visualisation of the lower limb arteries was achieved reached in only one patient, but was incomplete. Conclusion: Contrast-enhanced MR angiography yielded the correct diagnosis of Leriche's syndrome in all 7 patients. Contrast-enhanced MR angiography was superior to DSA in the assessment of the distal run-off vessels in five of seven patients. (orig.) [de

  17. Practical issues in the prevention and treatment of contrast ...

    African Journals Online (AJOL)

    Kidney dysfunction is a serious complication that can occur following the administration of contrast media (CM). Although the incidence of contrast nephropathy (CN) is low in the general population (1 - 2%) it poses a serious risk to those with impaired kidney function. Other risks include diabetes, old age and dehydration.

  18. Contrast medium-induced nephropathy: Aspects on incidence ...

    African Journals Online (AJOL)

    Contrast media-induced nephropathy (CIN) is a well-known complication of radiological examinations employing iodine contrast media (I-CM). The rapid development and frequent use of coronary interventions and multi-channel detector computed tomography with concomitant administration of relatively large doses of ...

  19. Effect of organic contrast Media on the haematology and Serum ...

    African Journals Online (AJOL)

    Key Words: Contrast media, haematology, serum electrolytes, dogs, xylazine. The effect of contrast media on the hematology and serum electrolyte was determined in five dogs sedated with 2mg/kg of xylazine intramuscular (i.m). A total of 800mg/kg bolus of 76% urograffin was then administered by intravenous injection ...

  20. Asymptotic expansions for high-contrast linear elasticity

    KAUST Repository

    Poveda, Leonardo A.

    2015-03-01

    We study linear elasticity problems with high contrast in the coefficients using asymptotic limits recently introduced. We derive an asymptotic expansion to solve heterogeneous elasticity problems in terms of the contrast in the coefficients. We study the convergence of the expansion in the H1 norm. © 2015 Elsevier B.V.