CT vs. MRCP in choledocholithiasis jaundice.

Science.gov (United States)

Petrescu, I; Bratu, A M; Petrescu, S; Popa, B V; Cristian, D; Burcos, T

2015-01-01

Obstructive jaundice can raise problems to diagnostic imaging. The radiologist must choose the most appropriate examination that delivers the most important diagnostic information because the differences between a lithiasic obstruction and a tumoral one are vital. This information helps the surgeon speed up the process of decision-making, because the treatment may be very different in relation to the nature of the obstruction. This study tries to demonstrate the diagnostic accuracy of computed tomography (CT) and magnetic resonance cholangiopancreatography (MRCP) in detecting the obstacle in the common bile duct (CBD) and the possibility of establishing the lithiasic nature of the obstruction. A retrospective analysis was analyzed during an interval of 18 months that included jaundice patients admitted in the General Surgery Department of "Coltea" Clinical Hospital. They were examined by CT scanning and by MRCP, being suspected of choledocholithiasis. 63 patients were included in the study, 34 females and 29 males. 33 CT scans and 30 MRCP exams were performed. CT scan is useful in detecting residual or iterative choledocholithiasis in patients after cholecystectomy, contrast enhanced CT (CECT), being able to differentiate between lithiasic and non-lithiasic obstruction. MRCP delivers important anatomic details of the biliary tree; it is superior to CT in diagnosing the hepatocholedochal lithiasis; MRCP tends to replace endoscopic retrograde cholangiopancreatography (ERCP)--the diagnostic "gold standard" reducing the number of unnecessary invasive diagnostic procedures.

Diagnostic value of high strength MRCP in the obstructive jaundice

International Nuclear Information System (INIS)

Yang Yang; Dong Yuhai; Yin Jie; Lv Guoyi

2007-01-01

Objective: To evaluate the diagnostic value of high strength MRCP in patients with obstructive jaundice. Methods: Routine MRI and MRCP examination on 161 patients with obstructive jaundice were carded out with 1.5T Siemens super-conductive magnetic resonance machine. Of them, 103 cases were benign lesions and 58 were malignant after surgical and ERCP pathological confirmation. Results: The diagnostic accuracy of MRCP was 100%, with the qualitative diagnostic accuracy at 90.2%. Conclusion: MRCP was the best method in diagnosing patients with obstructive jaundice, the concerned performances of MRCP could provide the dependable basis for surgical operation project. (authors)

Magnetic resonance cholangiographic (MRCP) features of ischemic-type biliary lesions (ITBL). A case-control study; Magnetresonanz-Cholangiografie (MRCP) bei Patienten mit Ischemic-Type Biliary Lesions (ITBL). Eine Fall-Kontroll-Studie

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Collettini, F.; Kroencke, T.J.; Renz, D.M.; Bucourt, M. de; Poellinger, A. [Charite, Berlin (Germany). Klinik fuer Radiologie; Heidenhain, C.; Neuhaus, P. [Charite, Berlin (Germany). Klinik fuer Allgemein-, Visceral- und Transplantationschirurgie CVK

2011-08-15

Purpose: To evaluate the spectrum of MR cholangiography (MRCP) features of ischemic-type biliary lesions (ITBL) after orthotopic liver transplantation (OLT). Materials and Methods: 30 patients (16 m, 14 f) with an average age of 52 years (9 - 69 y) were examined in two 1.5 MR units using breath-hold 2D-SS-FSE-sequences and 3D-MRCP sequences. 20 of the 30 patients had an established ITBL, and the remaining 10 patients were post-OLT controls. MRCPs were evaluated independently by two experienced radiologists that were blinded to the clinical history as well as the results of other imaging modalities. All images were analyzed for the presence of 16 different pathological features. Differences between ITBL patients and controls were analyzed using the Mann-Whitney-U Test. Inter-rater variability was tested using the Cohen's Kappa test. Results: Abnormal findings of bile ducts were seen in all patients. The most common findings were (in percentage for reader 1/2) intrahepatic bile duct dilatation (95 %/95 %) and extrahepatic bile duct stenoses (95 %/85 %), followed by intrahepatic main duct stenoses (90 %/95 %) and segmental duct stenoses (85 %/85 %). Differences between ITBL patients and controls were significant for most of the analyzed features (Mann-Whitney-U test, p < 0.05). For 12 of 16 features, there was substantial or almost perfect agreement (K = 0.61 - 1.00), for 2 of 16 features moderate agreement (K = 0.41- 0.60) and for 2 of 16 features fair agreement (K < 0.40). Conclusion: In patients with ITBL, MR cholangiography reveals characteristic features that may allow differentiation from other biliary complications after liver transplantation. (orig.)

Evaluation fo MR cholangio-pancreatography in the diagnosis of pancreaticobiliary diseases. In comparison with ERCP

International Nuclear Information System (INIS)

Saito, Masayuki; Watahiki, Hajime; Yamamoto, Hideaki

1995-01-01

The clinical usefulness of MR cholangio-pancreatography (MRCP) by fast spin echo method was compared with that of endoscopic retrograde cholangio pancreatography (ERCP). In MRCP, favorable images of bile and pancreatic ducts were obtained in 66.7% (78/117) and bile duct images in 16.2% (19/117), showing the overall efficacy rate of 92.9% (97/117). Seventy-seven of these images were compared with simultaneously obtained favorable ERCP images. The excellent and favorable rate of MRCP reached 84.5% (65/77), showing clinical usefulness of MRCP. Obscure images were considered due to insufficient breath-hold time. (S.Y.)

MR cholangiopancreatography. Comparison of images obtained with 1.0 and 1.5 tesla units

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Yasui, Masayasu; Ito, Katsuyoshi; Koike, Shinji; Matsunaga, Naofumi

2002-01-01

The purpose of this study was to compare the image quality and visualization obtained in MR cholangiopancreatography (MRCP) using different high-field strength (1.0 vs. 1.5 Tesla) MR units and to assess the effect of field strength on MRCP. This study population included 10 healthy volunteers and 37 patients suspected of having pancreatobiliary diseases. MRCP images were obtained using two MR units with different high-field strengths (1.0 and 1.5 Tesla), with half-Fourier acquisition single-shot turbo spin-echo (HASTE) and rapid acquisition by relaxation enhancement (RARE) sequences. The image quality and visualization of each portion of the pancreatobiliary system were graded and recorded using a four-point scale. Additionally, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured. The SNR and CNR in HASTE sequences acquired with the 1.5 Tesla (T) unit were significantly higher than those acquired with the 1.0 T unit (p=0.001). In qualitative analysis, there were no statistically significant differences in image quality or visualization of the ducts in either HASTE or RARE sequences between 1.0 T and 1.5 T. Our study showed that visual image quality provided by MRCP was equivalent at 1.0 and 1.5 T. (author)

MR cholangiopancreatography in children: feasibility, safety, and initial experience

International Nuclear Information System (INIS)

Delaney, Lisa; Karmazyn, Boaz; Akisik, M.F.; Jennings, S.G.; Applegate, Kimberly E.

2008-01-01

The indications for MR cholangiopancreatography (MRCP) in children, and its safety and findings, might differ from those in adults and are not well described. To investigate the safety, feasibility, and accuracy of MRCP in children. We reviewed all prospective MRCP reports, noting the indication, the use of secretin, endoscopic retrograde cholangiopancreatography (ERCP) findings, and patient outcomes. Two readers reviewed each MRCP study by consensus to rate duct visualization and compare pancreatic duct sizes before and after secretin administration (paired t-test). The likelihood of a normal versus an abnormal MRCP study was compared by gender, pancreatitis as the primary indication, secretin use, and whether ERCP was performed (Fisher's exact test), as well as age (t-test). A total of 85 MRCP studies were performed in children (mean age 10.3 years), most commonly for evaluation of pancreatitis (n=47, 55%); 41 (48%) used secretin and 39 (46%) used a negative oral contrast agent. Of the 85 studies, 72 (85%) had excellent image quality and 43 were normal. ERCP was performed after 16 of the 85 MRCP studies (19%); the diagnoses were concordant with those of MRCP in 13 (81%). There were 42 abnormal MRCP studies, and these were more likely to be in girls (P=0.03) and in children who had undergone ERCP (P<0.01). Secretin and the negative oral contrast agent were well-tolerated. Secretin improved duct visualization (P<0.001). MRCP safely and accurately depicted pancreaticobiliary anatomy in children. The use of secretin improved visualization of the pancreatic duct. (orig.)

Magnetic resonance cholangiographic (MRCP) features of ischemic-type biliary lesions (ITBL). A case-control study

International Nuclear Information System (INIS)

Collettini, F.; Kroencke, T.J.; Renz, D.M.; Bucourt, M. de; Poellinger, A.; Heidenhain, C.; Neuhaus, P.

2011-01-01

Purpose: To evaluate the spectrum of MR cholangiography (MRCP) features of ischemic-type biliary lesions (ITBL) after orthotopic liver transplantation (OLT). Materials and Methods: 30 patients (16 m, 14 f) with an average age of 52 years (9 - 69 y) were examined in two 1.5 MR units using breath-hold 2D-SS-FSE-sequences and 3D-MRCP sequences. 20 of the 30 patients had an established ITBL, and the remaining 10 patients were post-OLT controls. MRCPs were evaluated independently by two experienced radiologists that were blinded to the clinical history as well as the results of other imaging modalities. All images were analyzed for the presence of 16 different pathological features. Differences between ITBL patients and controls were analyzed using the Mann-Whitney-U Test. Inter-rater variability was tested using the Cohen's Kappa test. Results: Abnormal findings of bile ducts were seen in all patients. The most common findings were (in percentage for reader 1/2) intrahepatic bile duct dilatation (95 %/95 %) and extrahepatic bile duct stenoses (95 %/85 %), followed by intrahepatic main duct stenoses (90 %/95 %) and segmental duct stenoses (85 %/85 %). Differences between ITBL patients and controls were significant for most of the analyzed features (Mann-Whitney-U test, p < 0.05). For 12 of 16 features, there was substantial or almost perfect agreement (K = 0.61 - 1.00), for 2 of 16 features moderate agreement (K = 0.41- 0.60) and for 2 of 16 features fair agreement (K < 0.40). Conclusion: In patients with ITBL, MR cholangiography reveals characteristic features that may allow differentiation from other biliary complications after liver transplantation. (orig.)

Secretin-stimulated MR cholangio-pancreatography in the evaluation of asymptomatic patients with non-specific pancreatic hyperenzymemia

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Donati, Francescamaria, E-mail: fra.donati@katamail.co [2nd Department of Radiology, Pisa University-Hospital, Via Paradisa 2, I-56124 Pisa (Italy); Boraschi, Piero; Gigoni, Roberto; Salemi, Simonetta [2nd Department of Radiology, Pisa University-Hospital, Via Paradisa 2, I-56124 Pisa (Italy); Faggioni, Lorenzo; Bertucci, Cristina; Cecchi, Claudia; Bartolozzi, Carlo [Diagnostic and Interventional Radiology, University of Pisa, Via Rome 67, I-56126 Pisa (Italy); Falaschi, Fabio [2nd Department of Radiology, Pisa University-Hospital, Via Paradisa 2, I-56124 Pisa (Italy)

2010-08-15

Purpose: To assess the diagnostic value of secretin-stimulated MRCP (SS-MRCP) compared with conventional MRCP in asymptomatic patients with mild elevations of pancreatic enzymes. Materials and methods: Eighty asymptomatic patients with pancreatic hyperenzymemia underwent MR imaging at 1.5 T-device (Signa EXCITE, GE Healthcare). After the acquisition of axial T1w,T2w sequences, and conventional MRCP, SS-MRCP was performed using a single-slice coronal breath-hold, thick-slab, SSFSE T2w sequence, repeated every 30 s up to 15 min following intravenous injection of secretin (Secrelux, Sanochemia). Results: On the basis of the standards of reference, our final diagnoses were: negative findings (n = 23), pancreas divisum (n = 22), mild chronic pancreatitis (n = 14), inflammatory ampullary stenosis (n = 3), juxtapapillary duodenal diverticulum (n = 1), small cystic lesions (<1 cm) (n = 22; 5/22 cases associated with pancreas divisum). The image quality of SS-MRCP was significantly higher than that of conventional MRCP (p < 0.0001). Standards of reference did not differ significantly from of SS-MRCP findings (p = 0.5), while was statistically different from those of conventional MRCP (p < 0.0001). A significant difference was found between conventional MRCP and SS-MRCP findings (p < 0.0001). Conclusion: In asymptomatic patients with non-specific pancreatic hyperenzymemia SS-MRCP may represent the best non-invasive diagnostic technique, since it gives morphological and functional information.

Value of selective MIP reconstructions of respiratory triggered 3D-TSE-MR cholangiography on a workstation versus standard MIP reconstructions and single-shot MRCP

International Nuclear Information System (INIS)

Schaible, R.; Textor, J.; Kreft, B.; Schild, H.; Neubrand, M.

2001-01-01

Comparison of anatomical visualisation and diagnostic value of selective MIP reconstructions of respiratory triggered 3D-TSE-MRCP versus standard MIP reconstructions and single-shot MRCP. Material and Methods: 50 patients with pancreaticobiliary disease were examined at 1.5 Tesla (ACS NT II, Philips Medical Systems) using a breath-hold single-shot (SS) and a respiratory triggered 3D-TSE-MRCP technique in 12 standard MIP projections. Additional selective MIP reconstructions with different slice thickness (2, 4, 10 cm) and projections were performed on a workstation. Visualization of the pancreaticobiliary system and the diagnostic value of the examinations were analysed. Results: Single-shot and 3D-TSE in standard projections showed comparable anatomical visualisation. On selective MIP reconstructions the biliary system (SS p [de

MRCP in the evaluation of pancreaticobiliary disease in children

International Nuclear Information System (INIS)

Arcement, C.M.; Meza, M.P.; Arumanla, S.; Towbin, R.B.

2001-01-01

Background. Radiologic assessment of pancreaticobiliary ductal disease (PBDD) in children currently consists of physiologic tests (radionuclide examinations) or invasive anatomic studies (ERCP and PTC). An accurate noninvasive and reproducible examination that can direct the subsequent need for more invasive studies would be helpful in this patient group. Objective. To determine the effectiveness of MRCP as a screening tool for PBBD in the pediatric population. Materials and methods. Over the last year, 33 patients ranging from 7 months to 20 years of age were prospectively evaluated with MRCP on a 1.5 T magnet. One patient was examined twice, several months apart. Thirteen patients had liver transplants. Coronal SPGR and heavily T-2W FSE cross-sectional images were obtained. Standard and oblique 2- to 6-cm-thick slab SSFSE (single-shot fast spin echo) acquisition and 3D MIP reconstruction of 2D FSE images were obtained in the planes of the CBD and pancreatic duct. Nine studies were performed with the patient under sedation with chloral hydrate or nembutal and fentanyl with quiet respiration, and the non-sedated patients were assessed with single breath hold or quiet respiration. Three patients received secretin. MRCP results were correlated with ERCP (9), PTC (7), liver biopsy (13), clinical information (6), surgery (3), and autopsy (2). Results. All 34 studies performed were considered diagnostic. Periportal fluid, proximal bowel fluid, and gallbladder distention did not significantly diminish the diagnostic information in any cases. Motion artifact did not cause serious degradation in image quality. MRCP depicted abnormalities including stones, stricture, intraductal tumor, and extrinsic compression, all of which were confirmed at ERCP, PTC (two unsuccessful in patients with non-dilated ducts by MRCP), surgery, liver biopsy, and autopsy. There were no false-negative examinations. Normal pancreatic studies performed to exclude pancreas divisum were followed

MRCP in the evaluation of pancreaticobiliary disease in children

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Arcement, C.M.; Meza, M.P.; Arumanla, S.; Towbin, R.B. [Children' s Hospital of Pittsburgh, Dept. of Radiology, Pittsburgh, PA (United States)

2001-02-01

Background. Radiologic assessment of pancreaticobiliary ductal disease (PBDD) in children currently consists of physiologic tests (radionuclide examinations) or invasive anatomic studies (ERCP and PTC). An accurate noninvasive and reproducible examination that can direct the subsequent need for more invasive studies would be helpful in this patient group. Objective. To determine the effectiveness of MRCP as a screening tool for PBBD in the pediatric population. Materials and methods. Over the last year, 33 patients ranging from 7 months to 20 years of age were prospectively evaluated with MRCP on a 1.5 T magnet. One patient was examined twice, several months apart. Thirteen patients had liver transplants. Coronal SPGR and heavily T-2W FSE cross-sectional images were obtained. Standard and oblique 2- to 6-cm-thick slab SSFSE (single-shot fast spin echo) acquisition and 3D MIP reconstruction of 2D FSE images were obtained in the planes of the CBD and pancreatic duct. Nine studies were performed with the patient under sedation with chloral hydrate or nembutal and fentanyl with quiet respiration, and the non-sedated patients were assessed with single breath hold or quiet respiration. Three patients received secretin. MRCP results were correlated with ERCP (9), PTC (7), liver biopsy (13), clinical information (6), surgery (3), and autopsy (2). Results. All 34 studies performed were considered diagnostic. Periportal fluid, proximal bowel fluid, and gallbladder distention did not significantly diminish the diagnostic information in any cases. Motion artifact did not cause serious degradation in image quality. MRCP depicted abnormalities including stones, stricture, intraductal tumor, and extrinsic compression, all of which were confirmed at ERCP, PTC (two unsuccessful in patients with non-dilated ducts by MRCP), surgery, liver biopsy, and autopsy. There were no false-negative examinations. Normal pancreatic studies performed to exclude pancreas divisum were followed

Normal pancreatic exocrine function does not exclude MRI/MRCP chronic pancreatitis findings.

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Alkaade, Samer; Cem Balci, Numan; Momtahen, Amir Javad; Burton, Frank

2008-09-01

Abnormal pancreatic function tests have been reported to precede the imaging findings of chronic pancreatitis. Magnetic resonance imaging (MRI) with magnetic resonance cholangiopancreatography (MRCP) is increasingly accepted as the primary imaging modality for the detection of structural changes of early mild chronic pancreatitis. The aim of this study was to evaluate MRI/MRCP findings in patients with symptoms consistent with chronic pancreatitis who have normal Secretin Endoscopic Pancreatic Function test. A retrospective study of 32 patients referred for evaluation of chronic abdominal pain consistent with chronic pancreatitis and reported normal standard abdominal imaging (ultrasound, computed tomography, or MRI). All patients underwent Secretin Endoscopic Pancreatic Function testing and pancreatic MRI/MRCP at our institution. We reviewed the MRI/MRCP images in patients who had normal Secretin Endoscopic Pancreatic Function testing. MRI/MRCP images were assessed for pancreatic duct morphology, gland size, parenchymal signal and morphology, and arterial contrast enhancement. Of the 32 patients, 23 had normal Secretin Endoscopic Pancreatic Function testing, and 8 of them had mild to marked spectrum of abnormal MRI/MRCP findings that were predominantly focal. Frequencies of the findings were as follows: pancreatic duct stricture (n=3), pancreatic duct dilatation (n=3), side branch ectasia (n=4), atrophy (n=5), decreased arterial enhancement (n=5), decreased parenchymal signal (n=1), and cavity formation (n=1). The remaining15 patients had normal pancreatic structure on MRI/MRCP. Normal pancreatic function testing cannot exclude abnormal MRI/MRCP especially focal findings of chronic pancreatitis. Further studies needed to verify significance of these findings and establish MRI/MRCP imaging criteria for the diagnosis of chronic pancreatitis.

The role of MR cholangiopancreatography in acute abdominal pain (a case study)

International Nuclear Information System (INIS)

Obradovic, G.

2000-01-01

Rapid technological advances have resulted in improved Magnetic Resonance Imaging (MRI) of the abdomen. In particular, the development of single breath hold sequences have led to a resurgence in imaging of the binary tree and pancreatic duct. For this reason, Magnetic Resonance Cholangiopancreatography (MRCP) is recognised as a valuable tool which is safe, fast and noninvasive. This case study demonstrates that MRCP could identify the intrahepatic duct obstruction adequately, so that the appropriate course of management could be readily instigated. In addition, the excellent quality of MR imaging will lead to an increase in referrals for MRCP if the modality is available and there are no patient contra-indications. Copyright (1999) Australian Institute of Radiography

Differential diagnosis of benign and malignant intraductal papillary mucinous tumors of the pancreas: MR cholangiopancreatography and MR angiography

International Nuclear Information System (INIS)

Choi, Byung Se; Kim, Tae Kyoung; Kim, Ah Young; Kim, Kyoung Won; Park, Sung Won; Kim, Pyo Nyun; Ha, Kyun Kwon; Lee, Moon Gyu; Kim, Song Cheol

2003-01-01

To compare the usefulness of magnetic resonance cholangiopancreatography (MRCP) and MR angiography (MRA) in differentiating malignant from benign intraductal papillary mucinous tumors of the pancreas (IPMTs), and to determine the findings which suggest malignancy. During a 6-year period, 46 patients with IPMT underwent MRCP. Morphologically, tumor type was classified as main duct, branch duct, or combined. The diameter of the main pancreatic duct (MPD), the extent of the dilated MPD, and the location and size of the cystic lesion, septum, and communicating channel were assessed. For all types of IPMTs, enhanced mural nodules and portal vein narrowing were evaluated at MRA. Combined-type IPMTs were more frequently malignant (78%) than benign (42%) (p<0.05). Compared with benign lesions, malignant lesions were larger, and the caliber of the communicating channel was also larger (p < 0.05). Their dilated MPD was more extensive and of greater diameter (p<0.05), and the presence of mural nodules was more frequent (p<0.001). Combined MRCP and MRA might be useful for the differential diagnosis of malignant and benign IPMTs of the pancreas

The Impact of Gd-Eob-Dtpa-Enhanced MR Cholangiography in Biliary Diseases: Comparison with T2-Weighted MR Cholangiopancreatography

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Evrim Özmen

2016-06-01

Full Text Available Background: Contrast enhanced magnetic resonance cholangiography is a novel technique and promising method in demonstrating biliary tree anatomy and evaluating biliary disorders. However, to date, there are a limited number of studies that have focused on the impact of this technique. Aims: We aimed to evaluate the additional role of contrast enhanced MR cholangiography (MRC and compare contrast enhanced MRC with T2-weighted (w magnetic resonance cholangiopancreatography (MRCP in the diagnosis of biliary disorders. Study Design: Diagnostic accuracy study. Methods: The T2w-MRCP and contrast enhanced MRC sequences of 31 patients whose gold standard test results were available were scored visually for the existence of pathological findings with regard to any of the biliary diseases. Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA was used as the contrast agent. The correlation values were determined according to the statistical analysis made from those scores and the sensitivity, specificity and accuracy values of each sequence were detected as well. Results: We detected that the correlation values with gold standard methods of contrast enhanced MRC sequences were significantly higher than the ones of T2w-MRCP sequences. The correlation ratios of T2w-MRCP sequences were between 26 and 34%, while those for contrast enhanced MRC sequences were between 81 and 83% for the first reader and the correlation ratios of T2w-MRCP sequences were between 10 and 61%, whereas those of contrast enhanced MRC were between 79 and 81% for the second reader The mean sensitivity, specificity and accuracy values of T2w-MRCP sequences were 14.3-42.5%, 85-89.2% and 59.3-72.5%, respectively, while the mean sensitivity, specificity and accuracy values of contrast enhanced MRC sequences were 100%, 86.7% and 93.2-93.3%, respectively. Conclusion: We suggest that obtaining of contrast enhanced MRC sequences in addition to the T2w-MRCP can be useful in

MR imaging of primary sclerosing cholangitis - Additional value of diffusion-weighted imaging and ADC measurement

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Djokicc Kovac, Jelena [Center for Radiology and Magnetic Resonance Imaging, Clinical Center Serbia, Belgrade (Serbia)], e-mail: jelenadjokic2003@yahoo.co.uk; Maksimovic, Ruzica [Center for Radiology and Magnetic Resonance Imaging, Clinical Center Serbia, Belgrade (Serbia); Faculty of Medicine, Univ. of Belgrade, Belgrade (Serbia); Jesic, Rada [Clinic for Gastroenterohepatology, Clinical Center Serbia, Belgrade (Serbia); Faculty of Medicine, Univ. of Belgrade, Belgrade (Serbia); Stanisavljevic, Dejana [Inst. for Statistics, Faculty of Medicine, Univ. of Belgrade, Belgrade (Serbia); Kovac, Bojan [Military Medical Academy, Belgrade (Serbia)

2013-04-15

Background: Primary sclerosing cholangitis (PSC) is a cholestatic liver disease with chronic inflammation and progressive destruction of biliary tree. Magnetic resonance (MR) examination with diffusion-weighted imaging (DWI) allows analysis of morphological liver parenchymal changes and non-invasive assessment of liver fibrosis. Moreover, MR cholangiopancreatography (MRCP), as a part of standard MR protocol, provides insight into bile duct irregularities. Purpose: To evaluate MR and MRCP findings in patients with primary sclerosing cholangitis and to determine the value of DWI in the assessment of liver fibrosis. Material and Methods: The following MR findings were reviewed in 38 patients: abnormalities in liver parenchyma signal intensity, changes in liver morphology, lymphadenopathy, signs of portal hypertension, and irregularities of intra- and extrahepatic bile ducts. Apparent diffusion coefficient (ADC) was calculated for six locations in the liver for b = 800 s/mm{sup 2}. Results: T2-weighted hyperintensity was seen as peripheral wedge-shaped areas in 42.1% and as periportal edema in 28.9% of patients. Increased enhancement of liver parenchyma on arterial-phase imaging was observed in six (15.8%) patients. Caudate lobe hypertrophy was present in 10 (26.3%), while spherical liver shape was noted in 7.9% of patients. Liver cirrhosis was seen in 34.2% of patients; the most common pattern was micronodular cirrhosis (61.5%). Other findings included lymphadenopathy (28.9%), signs of portal hypertension (36.7%), and bile duct irregularities (78.9%). The mean ADCs (x10{sup -3} mm{sup 2}/s) were significantly different at stage I vs. stages III and IV, and stage II vs. stage IV. No significant difference was found between stages II and III. For prediction of stage {>=}II and stage {>=}III, areas under receiver-operating characteristic curves were 0.891 and 0.887, respectively. Conclusion: MR with MRCP is a necessary diagnostic procedure for diagnosis of PSC and

Evaluation of date syrup as an oral negative contrast agent for MRCP.

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Govindarajan, Arunkumar; Lakshmanan, Prakash Manikka; Sarawagi, Radha; Prabhakaran, Velu

2014-11-01

The purpose of this study was to compare the in vitro effects of date syrup with those of other contrast agents by qualitative and quantitative analysis and in vivo evaluation of the use of date syrup to improve the quality of MRCP images. Phantoms containing date syrup, ferumoxsil, pineapple juice, and water were imaged by 1.5-T MRI with T2-weighted and MRCP sequences, and signal-to-noise ratios were calculated. Biochemical analysis of date syrup was performed to find the nature of iron in it, and the iron content was quantified by energy-dispersive x-ray spectroscopy. Sixty patients underwent MRCP before and 30 minutes after ingestion of 100 mL of date syrup. Unenhanced and contrast-enhanced images were scored for gastrointestinal tract signal suppression and visualization of various pancreaticobiliary structures. In vitro evaluation showed that images obtained with date syrup had a signal-to-noise ratio comparable to that of images obtained with ferumoxsil in T2-weighted and MRCP sequences. The iron concentration in date syrup was 2.6 mg/dL, and it was in ferric form. Images obtained after oral contrast administration had statistically significant improvement in gastrointestinal tract signal suppression (p Date syrup can be used as a negative oral contrast agent for gastrointestinal tract signal suppression during MRCP and for improving visualization of various pancreaticobiliary structures.

Gadopentetate dimeglumine-enhanced MR cholangiopancreatography in infants with cholestasis

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Lee, Mi-Jung; Kim, Myung-Joon [Yonsei University, College of Medicine, Department of Radiology and Research Institute of Radiological Science, Severance Children' s Hospital, Seoul (Korea, Republic of); Severance Pediatric Liver Disease Research Group, Seoul (Korea, Republic of); Yoon, Choon-Sik [Yonsei University, College of Medicine, Department of Radiology, Gangnam Severance Hospital, Seoul (Korea, Republic of); Chung, Yong Eun [Yonsei University, College of Medicine, Department of Radiology and Research Institute of Radiological Science, Severance Children' s Hospital, Seoul (Korea, Republic of); Han, Seok Joo [Yonsei University, College of Medicine, Department of Pediatric Surgery, Severance Children' s Hospital, Seoul (Korea, Republic of); Severance Pediatric Liver Disease Research Group, Seoul (Korea, Republic of); Koh, Hong [Yonsei University, College of Medicine, Department of Pediatric Gastroenterology, Hepatology, and Nutrition, Severance Children' s Hospital, Seoul (Korea, Republic of); Severance Pediatric Liver Disease Research Group, Seoul (Korea, Republic of)

2011-04-15

Biliary atresia (BA) is a progressive, obliterative cholangiopathy that occurs in neonates with hepatic portoenterostomy the treatment of choice, but early surgery is important for optimum outcomes. MRI, including MR cholangiopancreatography (MRCP) may be a diagnostically useful alternative to US, but the heavily T2-weighted sequences used include not only bile duct signals, but also other heterogeneously high signal intensities from surrounding structures. To evaluate the effects of gadolinium when used to decrease background signal intensity on T2-weighted MR cholangiopancreatography (MRCP) in infants and to evaluate the qualitative improvement of the depiction of the common bile duct (CBD) for evaluating neonatal cholestasis. Our Institutional Review Board approved this prospective study. MRCP was performed with gadopentetate dimeglumine injection using a 1.5-T scanner. Pre- and postcontrast MRCP images were compared. Forty-nine infants (male:female = 21:28; age 0-12 months, mean 2.3) were included. The final diagnoses were biliary atresia (BA) in 28 cases and non-BA in 21. Quantitative analysis was conducted using region-of-interest measurements of mean signal intensities of the liver, pancreatic head and gallbladder (if defined). Qualitative analysis was performed by four radiologists who subjectively scored image confidence in the presence of CBD on a 4-point scale (0 for definitely absent, 1 for probably absent, 2 for probably present, and 3 for definitely present). The signal-to-noise ratios were significantly decreased in the liver and pancreatic head after contrast medium enhancement (mean 5.7{yields}4.0 in liver and mean 44.9{yields}12.7 in the pancreatic head; P < 0.0001), and this finding was constant in both the BA and the non-BA group. The mean confidence score in the presence of CBD decreased in the BA group (0.9{yields}0.5; P < 0.0001), but did not change significantly in the non-BA group (2.0{yields}2.1; P = 0.459) after contrast medium

The diagnostic value of MRI and MRCP in congenital duct cysts and complications

International Nuclear Information System (INIS)

Xiao Fang; Huang Suiqiao; Hu Tao

2009-01-01

Objective: To investigate the value of MRI and MRCP in diagnosis of congenital duct cysts and their complications. Methods: The MRI and MRCP of 29 cases of congenital duct cyst verified by pathological findings were analyzed retrospectively. Results: In 29 cases of Congenital choledochocele, 10 of which are type lb and 7 were Ic, appearing as the focal choledochal ecstasis, which were connected with the bile duct tree and displayed by MRCP. 10 cases were type IV and 2 are type V, appearing as the multiple cholangiectasis extrahepaticly and/or intrahepaticly and displayed by MRCP as the multiple cystoid with different sizes. There were 7 cases with complication of calculus, 4 in type Ib and 3 in type IV, appearing as single or multiple non-enhanced lesion with clear border. There were 3 cases with complication of tumors, 1 cholangiocarcinoma in type IV and type V respectively, appearing as the enhanced nodus within the wall of dilatant bile duct, 1 gallbladder carcinoma in type lb with multiple liver metastasis. The interruption of distal choledochocele was demonstrated in the complication of biliary atresia in 1 of type V. There was pancreatitis in 1 of type IV. The diagnosis and typing of choledochocele can be accurately made by MRI combined with MRCP, and complications were easily and clearly showed. The accuracy rate for location of choledochocele was 100%. Conclusion: There is an important value for MRI and MRCP examination in diagnosis of congenital bile duct cysts and their complications. (authors)

Utility of MRCP in clinical decision making of suspected choledocholithiasis: An institutional analysis and literature review.

Science.gov (United States)

Badger, Wesley R; Borgert, Andrew J; Kallies, Kara J; Kothari, Shanu N

2017-08-01

The ideal treatment algorithm for suspected choledocholithiasis is not yet well defined. Imaging options include magnetic resonance cholangiopancreatography (MRCP), endoscopic retrograde cholangiopancreatography (ERCP), and intraoperative cholangiogram (IOC). MRCP is diagnostic, while the other two modalities can also be therapeutic. Each of these modalities for diagnosis and treatment carries its own set of risks, benefits, and institutional costs. We hypothesized that there would be a significant difference between the biochemical profiles and characteristics of patients who undergo ERCP vs. MRCP vs. operative intervention as the initial choice of treatment/imaging modality. We performed a retrospective review of the electronic medical records for all patients with a coded diagnosis of choledocholithiasis from 2011 to 2014. The initial diagnostic modality was assessed for each hospital encounter. The statistical characteristics of MRCP as compared to fluoroscopic imaging of the biliary tree (ERCP, IOC) were analyzed. Overall, 527 hospital encounters were identified. Initial intervention included ERCP in 63%, MRCP in 12%, and cholecystectomy in 25% of patients. Patients undergoing cholecystectomy first, compared to MRCP or ERCP, tended to have lower values for alkaline phosphatase (P utility in this patient population should be questioned. Further research is needed to better define the pretest characteristics which would predict which patients do not need further intervention after MRCP as well as defining the most cost-effective strategy. Copyright © 2016 Elsevier Inc. All rights reserved.

Assessment of MRI and MRCP in diagnosis of biliary cystadenoma and cystadenocarcinoma

International Nuclear Information System (INIS)

Lewin, Maite; Arrive, Lionel; Tubiana, Jean-Michel; Mourra, Najat; Flejou, Jean-Francois; Honigman, Isabelle; Parc, Rolland

2006-01-01

Magnetic resonance imaging (MRI) and magnetic resonance cholangio-pancreatography (MRCP) features were analyzed in the diagnosis of seven surgically resected hepatobiliary cystic tumors with reference to histopathological data. Homogeneity, size, location, signal intensity, presence or absence of septa and/or nodules and MRCP features of the lesions were studied. Histological evidence demonstrated six biliary cystadenoma (BCA) including four pseudo-ovarian stroma (POS) and one biliary cystadenocarcinoma (BCAC). Cystic lesions (3-15 cm in diameter) were homogeneous in the six BCA, heterogeneous in the one BCAC, and were located in the left and right liver, respectively. On T2-weighted images all lesions were hyperintense. On T1-weighted images hypointensity was found in three BCA (all serous fluid, including one POS), isointensity was found in the three others (two mucinous and one hemorrhagic fluid, including three POS) and in the one BCAC (containing mucinous fluid). Septas were present in all cases and nodules only in the one BCAC. On MRCP a hyperintense cystic lesion was found in all cases and a bile ducts dilatation in two BCA and the one BCAC. Gadolinium-enhanced MRI in combination with MRCP is a valuable tool for the diagnosis of BCA or BCAC. However, no specific information is gained for POS detection. (orig.)

On the appearance of bile in clinical MR cholangiopancreatography

International Nuclear Information System (INIS)

Haakansson, K.; Christoffersson, J.O.; Leander, P.; Ekberg, O.; Haakansson, H.O.

2002-01-01

Purpose: To study the appearance of bile in clinical MR cholangiopancreatography (MRCP) with special reference to its chemical and physical properties. Material and Methods: Gallbladder bile was collected during surgery from 38 patients and studied with respect to chemical constituents. The relaxation rates 1/T1 and 1/T2 of bile were also determined in vitro. In 16 of these 38 patients, abdominal imaging was performed using MRCP as well as T1-weighted GE sequences. Results: For 9 of the 13 chemical parameters studied, a positive significant correlation with 1/T1 as well as 1/T2 was found. The median relaxation rates 1/T1 and 1/T2 were 0.76 and 1.48/s, respectively. The corresponding ranges were 0.38-3.13/s and 0.70-5.75/s, respectively. On the MRCP images a few patients showed gallbladder of poor visibility due to low signal-to-noise ratio. This coincided with a high relaxation rate 1/T2 of bile. On the T1-weighted GE sequences a few patients showed hyperintense gallbladder relative to liver, coinciding with high relaxation rates 1/T1 of bile. Conclusion: Bile was found to show a large interindividual variation with respect to relaxation rates 1/T1 and 1/T2. The relaxation rates increased with increasing amounts of substances in the bile. For some patients (11%) MRCP imaging is unsuccessful due to high relaxation rate of bile

The exploratory development of A self-made oral Gd-DTPA solution for low field MRCP in children

International Nuclear Information System (INIS)

Sheng Mao; Zhou Min; Gu Zhicheng; Wu Jizhi; Guo Wanliang; Ni Yongbiao; Fang Lin

2010-01-01

Objective: To evaluate the value of ingestion self-made Gd-DTPA solutin for low field magnetic resonance cholangiopancreatography (MRCP) (0.35T) in children. Methods: Phantom experiments were performed to select the optimal concentration of Gd-DTPA to be used as an oral negative contrast agent in low field MRCP. Twenty children suspected of celiac disease were performed with MRCP before and after ingestion Gd-DTPA solution. Signal intensity measurements of gastroduodenal lumens, pancreatobiliary ducts, and image quality scores were obtained systematically before and after contrast ingestion. Results: The selected Gd-DTPA concentration was 1.992 mmol/L. Ingestion of 80 ml solution eliminated or suppressed efficiently the gastroduodenal signal intensity, improving the MRCP image quality scores (P<0.01) significantly in children. Conclusion: 1.992 mmol/L self-made Gd-DTPA solutin can suppress or eliminate water signals from gastrointestinal tract and improve the quality of low field MRCP image in children. (authors)

PLAB and UK graduates’ performance on MRCP(UK) and MRCGP examinations: data linkage study

Science.gov (United States)

Wakeford, Richard

2014-01-01

Objectives To assess whether international medical graduates passing the two examinations set by the Professional and Linguistic Assessments Board (PLAB1 and PLAB2) of the General Medical Council (GMC) are equivalent to UK graduates at the end of the first foundation year of medical training (F1), as the GMC requires, and if not, to assess what changes in the PLAB pass marks might produce equivalence. Design Data linkage of GMC PLAB performance data with data from the Royal Colleges of Physicians and the Royal College of General Practitioners on performance of PLAB graduates and UK graduates at the MRCP(UK) and MRCGP examinations. Setting Doctors in training for internal medicine or general practice in the United Kingdom. Participants 7829, 5135, and 4387 PLAB graduates on their first attempt at MRCP(UK) Part 1, Part 2, and PACES assessments from 2001 to 2012 compared with 18 532, 14 094, and 14 376 UK graduates taking the same assessments; 3160 PLAB1 graduates making their first attempt at the MRCGP AKT during 2007-12 compared with 14 235 UK graduates; and 1411 PLAB2 graduates making their first attempt at the MRCGP CSA during 2010-12 compared with 6935 UK graduates. Main outcome measures Performance at MRCP(UK) Part 1, Part 2, and PACES assessments, and MRCGP AKT and CSA assessments in relation to performance on PLAB1 and PLAB2 assessments, as well as to International English Language Testing System (IELTS) scores. MRCP(UK), MRCGP, and PLAB results were analysed as marks relative to the pass mark at the first attempt. Results PLAB1 marks were a valid predictor of MRCP(UK) Part 1, MRCP(UK) Part 2, and MRCGP AKT (r=0.521, 0.390, and 0.490; all PIELTS scores correlated significantly with later performance, multiple regression showing that the effect of PLAB1 (β=0.496) was much stronger than the effect of IELTS (β=0.086). Changes to PLAB pass marks that would result in international medical graduate and UK medical graduate equivalence were assessed in two

PLAB and UK graduates' performance on MRCP(UK) and MRCGP examinations: data linkage study.

Science.gov (United States)

McManus, I C; Wakeford, Richard

2014-04-17

To assess whether international medical graduates passing the two examinations set by the Professional and Linguistic Assessments Board (PLAB1 and PLAB2) of the General Medical Council (GMC) are equivalent to UK graduates at the end of the first foundation year of medical training (F1), as the GMC requires, and if not, to assess what changes in the PLAB pass marks might produce equivalence. Data linkage of GMC PLAB performance data with data from the Royal Colleges of Physicians and the Royal College of General Practitioners on performance of PLAB graduates and UK graduates at the MRCP(UK) and MRCGP examinations. Doctors in training for internal medicine or general practice in the United Kingdom. 7829, 5135, and 4387 PLAB graduates on their first attempt at MRCP(UK) Part 1, Part 2, and PACES assessments from 2001 to 2012 compared with 18,532, 14,094, and 14,376 UK graduates taking the same assessments; 3160 PLAB1 graduates making their first attempt at the MRCGP AKT during 2007-12 compared with 14,235 UK graduates; and 1411 PLAB2 graduates making their first attempt at the MRCGP CSA during 2010-12 compared with 6935 UK graduates. Performance at MRCP(UK) Part 1, Part 2, and PACES assessments, and MRCGP AKT and CSA assessments in relation to performance on PLAB1 and PLAB2 assessments, as well as to International English Language Testing System (IELTS) scores. MRCP(UK), MRCGP, and PLAB results were analysed as marks relative to the pass mark at the first attempt. PLAB1 marks were a valid predictor of MRCP(UK) Part 1, MRCP(UK) Part 2, and MRCGP AKT (r=0.521, 0.390, and 0.490; all PIELTS scores correlated significantly with later performance, multiple regression showing that the effect of PLAB1 (β=0.496) was much stronger than the effect of IELTS (β=0.086). Changes to PLAB pass marks that would result in international medical graduate and UK medical graduate equivalence were assessed in two ways. Method 1 adjusted PLAB pass marks to equate median performance of PLAB

Noninvasive investigation of exocrine pancreatic function: Feasibility of cine dynamic MRCP with a spatially selective inversion-recovery pulse.

Science.gov (United States)

Yasokawa, Kazuya; Ito, Katsuyoshi; Tamada, Tsutomu; Yamamoto, Akira; Hayashida, Minoru; Tanimoto, Daigo; Higaki, Atsushi; Noda, Yasufumi; Kido, Ayumu

2015-11-01

To investigate the feasibility of noncontrast-enhanced cine dynamic magnetic resonance cholangiopancreatography (MRCP) with a spatially selective inversion-recovery (IR) pulse for evaluating exocrine pancreatic function in comparison with the N-benzoyl-L-tyrosyl-p-aminobenzoic acid (BT-PABA) test as a pancreatic exocrine function test. Twenty subjects with or without chronic pancreatitis were included. MRCP with a spatially selective IR pulse was repeated every 15 seconds for 5 minutes to acquire a total of 20 images (cine-dynamic MRCP). The median and mean frequency of the observation (the number of times) and the moving distance (mean secretion grading scores) of pancreatic juice inflow on cine-dynamic MRCP were compared with a BT-PABA test. The urinary PABA excretion rate (%) had significant positive correlations with both the mean secretion grade (r = 0.66, P = 0.002) and frequency of secretory inflow (r = 0.62, P = 0.004) in cine dynamic MRCP. Both the mean frequency of observations of pancreatic secretory inflow (1.4 ± 1.6 times vs. 14.3 ± 4.2 times, P Cine dynamic MRCP with a spatially selective IR pulse may have potential for estimating the pancreatic exocrine function noninvasively as a substitute for the BT-PABA test. © 2015 Wiley Periodicals, Inc.

MR elastography in primary sclerosing cholangitis: correlating liver stiffness with bile duct strictures and parenchymal changes.

Science.gov (United States)

Bookwalter, Candice A; Venkatesh, Sudhakar K; Eaton, John E; Smyrk, Thomas D; Ehman, Richard L

2018-04-07

To determine correlation of liver stiffness measured by MR Elastography (MRE) with biliary abnormalities on MR Cholangiopancreatography (MRCP) and MRI parenchymal features in patients with primary sclerosing cholangitis (PSC). Fifty-five patients with PSC who underwent MRI of the liver with MRCP and MRE were retrospectively evaluated. Two board-certified abdominal radiologists in agreement reviewed the MRI, MRCP, and MRE images. The biliary tree was evaluated for stricture, dilatation, wall enhancement, and thickening at segmental duct, right main duct, left main duct, and common bile duct levels. Liver parenchyma features including signal intensity on T2W and DWI, and hyperenhancement in arterial, portal venous, and delayed phase were evaluated in nine Couinaud liver segments. Atrophy or hypertrophy of segments, cirrhotic morphology, varices, and splenomegaly were scored as present or absent. Regions of interest were placed in each of the nine segments on stiffness maps wherever available and liver stiffness (LS) was recorded. Mean segmental LS, right lobar (V-VIII), left lobar (I-III, and IVA, IVB), and global LS (average of all segments) were calculated. Spearman rank correlation analysis was performed for significant correlation. Features with significant correlation were then analyzed for significant differences in mean LS. Multiple regression analysis of MRI and MRCP features was performed for significant correlation with elevated LS. A total of 439/495 segments were evaluated and 56 segments not included in MRE slices were excluded for correlation analysis. Mean segmental LS correlated with the presence of strictures (r = 0.18, p duct strictures. Segments with increased LS show T2 hyperintensity, DWI hyperintensity, and post-contrast hyperenhancement. Global liver stiffness shows a moderate correlation with number of segmental strictures and significantly correlates with spleen stiffness, splenomegaly, and varices.

Comparison of 2D and 3D sequences for MRCP. Clinical value of the different techniques; Vergleich von 2D- und 3D-Sequenzen fuer die MRCP. Klinischer Stellenwert der einzelnen Techniken

Energy Technology Data Exchange (ETDEWEB)

Wallnoefer, A.M.; Herrmann, K.A.; Zech, C.J.; Gourtsoyianni, S.; Reiser, M.F.; Schoenberg, S.O. [Klinikum Grosshadern der Ludwig-Maximilian-Universitaet Muenchen (Germany). Institut fuer Klinische Radiologie; Beuers, U. [Klinikum Grosshadern der Ludwig-Maximilian-Universitaet Muenchen (Germany). Klinik fuer Innere Medizin II

2005-11-01

Magnetic resonance cholangio-pancreaticograpy (MRCP) is a non-invasive imaging modality of the pancreatico-biliary system which plays an increasingly important role in the clinical and diagnostic workup of patients with biliary or pancreatic diseases. The present review is designed to give an overview of the currently available and appropriate sequences, their technical background, as well as new developments and their relevance to the various clinical issues and challenges. The impact of the latest technical innovations, such as integrated parallel imaging techniques and navigator-based respiratory triggering, on the diagnostic capacities of MRCP is discussed. In this context, the individual value of RARE, T2w single shot turbo/fast spin echo (SSFSE) and the recently introduced 3D T2w turbo/fast spin echo sequences (T2w 3D-T/FSE) is reviewed. RARE imaging may be preferred in severely ill patients with limitations in cooperation, SSFSE is particularly effective in differentiating benign and malignant stenosis, and 3D-FSE offers additional advantages in the detection of small biliary concrements. (orig.) [German] Die Magnetresonanzcholangiopankreatikographie (MRCP) ist eine nichtinvasive Untersuchungsmethode des pankreatikobiliaeren Systems, die heute einen festen Platz in der klinischen Diagnostik eingenommen hat. Die vorliegende Arbeit gibt einen Ueberblick ueber die derzeit gaengigen Sequenzen, ihre technischen Grundlagen sowie ihre jeweilige Bedeutung in den verschiedenen klinischen Einsatzgebieten und Fragestellungen. Darueber hinaus werden die Bedeutung der parallelen Bildgebung, der navigatorbasierten Atemtriggerung und der neu eingefuehrten dreidimensionalen Sequenzen fuer die MRCP sowie ihre moeglichen Einsatzgebiete behandelt. Fuer die MRCP haben die 3 gaengigen Sequenzen, die SS-RARE-Sequenz, die T2w-single-shot-fast-spin-echo- (SSFSE) und die 3D-FSE-Sequenz spezifische Vor- und Nachteile. Die SS-RARE-Sequenz ist aufgrund der sehr kurzen Messzeit bei

An increased flip angle in late phase Gd-EOB-DTPA MRI shows improved performance in bile duct visualization compared to T2w-MRCP

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Stelter, Lars, E-mail: lars.stelter@charite.de [Klinik für Radiologie, Charité – Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); Freyhardt, Patrick, E-mail: patrick.freyhardt@charite.de [Klinik für Radiologie, Charité – Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); Grieser, Christian, E-mail: christian.grieser@charite.de [Klinik für Radiologie, Charité – Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); Walter, Thula, E-mail: thula.walter@charite.de [Klinik für Radiologie, Charité – Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); Geisel, Dominik, E-mail: dominik.geisel@charite.de [Klinik für Radiologie, Charité – Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); Baur, Alexander, E-mail: alexander.baur@charite.de [Klinik für Radiologie, Charité – Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin (Germany); and others

2014-10-15

Highlights: • EOB-MRC acquired with a flip angle of 35° revealed a better diagnostic performance compared to T2w-MRCP. • EOB-MRC increased the readers’ confidence in identifying anatomic variations of the biliary tree. • As EOB-MRC comprises functional information it is a valuable adjunct to T2w-MRCP. - Abstract: Objectives: To estimate the additional value of an increased flip angle of 35° in late phase Gd-EOB-DTPA-enhanced magnetic resonance cholangiography, as compared to T2w-MRCP. Methods: 40 adult patients underwent Gd-EOB-DTPA enhanced MRI of the liver including a T2-weighted 3D TSE MRCP (T2w-MRCP) as well as a late phase T1-weighted THRIVE sequences applying a flip angle of 35° (fa35). Two experienced observers evaluated the images regarding the delineation of the different biliary regions using a three-point grading system. A five-point scale was applied to determine the readers’ confidence in identifying anatomical variations of the biliary tree. ROI analysis was performed to compare the signal-to-noise (SNR) and contrast-to-noise (CNR) ratios. Results: The quality for visualizing the biliary tree differed between T2w-MRCP and fa35 (p = <0.001). Late phase EOB-MRC was rated as good for delineating the entire biliary system, whereas T2w-MRCP received an overall poor rating. Especially the depiction of the intrahepatic bile ducts was estimated as problematic in T2w-MRCP. T2w-MRCP and fa35 revealed a discordant assessment of anatomical variations in 12.5% of the cases, comprising a generally higher confidence level for fa35 (4.0 ± 1.1 vs. 2.2 ± 1.2, p = <0.001). SNR proofed to be significantly higher in fa35 (p = <0.001), whereas T2w-MRCP revealed a significantly higher CNR (<0.001). Conclusions: Gd-EOB-DTPA enhanced magnetic resonance cholangiography acquired with a flip angle of 35° revealed a better diagnostic performance compared to T2w-MRCP and might be a valuable adjunct in assessing functional bile duct abnormalities.

Magnetic Resonance Imaging Including Magnetic Resonance Cholangiopancreatography for Tumor Localization and Therapy Planning in Malignant Hilar Obstructions

International Nuclear Information System (INIS)

Haenninen, E.L.

2005-01-01

PURPOSE: To assess image quality and overall accuracy of magnetic resonance imaging (MRI), including two magnetic cholangiopancreatography (MRCP) techniques, for the diagnostics and preoperative work-up of malignant hilar obstructions. MATERIAL AND METHODS: Thirty-one patients with malignant hilar obstructions (hilar cholangiocarcinoma, n=30; hepatocellular carcinoma, n=1) received MRCP by two techniques (single-shot thick-slab and multisection thin-slice MRCP) and unenhanced and contrast material-enhanced MRI. MR assessment included the evaluation of image quality and visualization of bile ducts (5-point scale), and the classification of tumor status. MR results were subsequently correlated with the results from surgery and pathology. RESULTS: The maximum intensity projections of multisection thin-slice MRCP had significantly more artifacts compared to MRCP in the single-shot thick-slab technique, and overall image quality of single-shot thick-slab MRCP was rated significantly superior compared to multisection thin-slice MRCP (4.4 ± 0.7 and 4.1 ± 0.9, respectively). Moreover, ductal visualization of different parts of the biliary system was rated superior with single-shot thick-slab MRCP. In contrast, the original data from multisection thin slice MRCP facilitated visualization of periductal lesions and adjacent structures. Overall MR accuracy for the assessment of tumor status, periductal infiltration, and lymph node metastases was 90%, 87%, and 66%, respectively. CONCLUSION: For evaluation of malignant hilar obstructions, MRCP by the single-shot thick-slab technique had superior image quality and fewer artifacts; in contrast, besides sole biliary visualization, multisection MRCP depicted complementary adjacent parenchymal and periductal structures. We therefore recommend MRI, with a combination of both MRCP techniques, for the diagnostic work-up and therapy planning of malignant hilar obstructions

The role of MRI in evaluation of acute pancreatitis

International Nuclear Information System (INIS)

Baba, Maiko; Munechika, Horotsugu

2003-01-01

The purpose of this study is to assess the role of MRI in acute pancreatitis. The findings of MPD (main pancreatic duct) and CBD (common bile duct) on MR cholangiopancreatography (MRCP) images were retrospectively reviewed in 60 patients with acute pancreatitis. The patients were divided into two groups; severe and mild pancreatitis, according to the criteria of Japanese group of investigation for pancreatic diseases. T2 weighed MR images were compared with contrast-enhanced CT images for evaluation of severity of the disease. MRCP images were also compared with endoscopic retrograde cholangiopancreatography (ERCP) images for evaluation of MPD and CBD. CBD was more clearly demonstrated by MRCP than MPD. Both MPD and CBD were more clearly seen in the mild group than in the severe group. A few false-negative cases were seen in MRCP. T2 weighed MR images were almost the same as contrast-enhanced CT images in diagnosis of acute pancreatitis. MRCP is useful for evaluation of CBD in severe cases and for evaluation of both CBD and MPD in mild cases of acute pancreatitis. The severity of disease can be evaluated by combination of T2 weighted MR images and MRCP alternative to contrast-enhanced CT. (author)

Fast MR imaging for evaluating the pancreaticobiliary system

International Nuclear Information System (INIS)

Takehara, Yasuo

1999-01-01

Due to physiological movement clinical MR applications for abdominal organs got off to a very slow start compared to MR imaging of other organs. However, with recent cutting-edge hardware technologies such as high performance gradient systems and phased-array capability, as well as software innovations including short TR fast spoiled gradient recalled acquisition in the steady state (GRASS), snapshot imaging such as single shot fast spin echo sequence (SSFSE) and echo planar imaging (EPI), scan times have been further reduced to make breath-hold imaging clinically viable and to enable semi-fluoroscopic, kinematic imaging recognition. The elimination of physiological motion has contributed to the significant improvement in image quality, or more specifically, the physiological motion that had long been problematic has been turned into a source of physiological information about pancreaticobiliary pathologies. In this article, the author reviewed the current status of fast MR technologies for examining pancreaticobiliary pathologies, stressing the functional and physiological aspects of the corresponding anatomy. The technologies included secretin MRCP, which became a powerful tool when combined with kinematic imaging

An incidental case of biliary fascioliasis with subtle clinical findings: US and MRCP findings

International Nuclear Information System (INIS)

Önder, Hakan; Ekici, Faysal; Adin, Emin; Kuday, Suzan; Gümüş, Hatice; Bilici, Aslan

2013-01-01

Fascioliasis is a disease caused by the trematode Fasciola hepatica. Cholangitis is a common clinical manifestation. Although fascioliasis may show various radiological and clinical features, cases without biliary dilatation are rare. We present unique ultrasound (US) and magnetic resonance cholangiopancreatography (MRCP) findings of a biliary fascioliasis case which doesn’t have biliary obstruction or cholestasis. Radiologically, curvilinear parasites compatible with juvenile and mature Fasciola hepatica within the gallbladder and common bile duct were found. The parasites appear as bright echogenic structures with no acoustic shadow on US and hypo-intense curvilinear lesions on T2 weighted MRCP images. Imaging studies may significantly contribute to the diagnosis of patients with subtle clinical and laboratory findings, particularly in endemic regions

Comparison between magnetic resonance cholangiopancreatography (MRCP) and endoscopic retrograde cholangiopancreatography (ERCP); Comparacion entre calongiografia por resonancia magnetica (CPRM) y colangiografia retrograda endoscopia (CPRE)

Energy Technology Data Exchange (ETDEWEB)

Pulpeiro, J. R.; Armesto, V. [Clinica Nosa Senora dos Ollos Grandes. Lugo (Spain); Lopez-Roses, L.; Lancho, A.; Gonzalez, A. [Hospital Xeral. Lugo (Spain)

2000-07-01

To assess the correlation between magnetic resonance cholangiopancreatography (MRCP) and endoscopic retrograde cholangiopancreatography (ERCP). The authors carried out a prospective study of 71 patients suspected of having biliary diseases. MRCP was performed, followed by ERCP.MRCP was done with a 1.5-T system using hypergradients, abdominal phase array coil and single-shot fast spin-echo (SSFSE) sequences with maximum signal intensity in T2-weighted images. This sequence only provides images of the fluids, similar to those obtained with ERCP. The results of ERCP were employed as a reference standard. Thirty patients were found to have stenosis (19 malignant and 11 benign). 25 had choledocholithiasis and 16 showed no abnormal findings. The correlation was complete in patients with stenosis. MRCP detected 23 cases of choledocholithiasis (ERCP was normal in the remaining two patients, but calculi were discovered on shpincterotomy). MRCP confirmed the normal condition of the bile duct in 12 of the 16 patients free of biliary disease (2 patients in whom ERCP had been normal had been diagnosed as having bile duct dilatation due to choledocholithiasis 24 hours and 10 days earlier, respectively, and two cases of presented ectasia due to fibrosis of the sphincter of Oddi showed good emptying during ERCP). MRCP using SSFSE is highly correlated with ERCP, which should be reserved for cases in which the diagnosis is in doubt or endoscopic management is necessary. (Author) 25 refs.

Biliary anatomy in potential right hepatic lobe living donor liver transplantation (LDLT): The utility of CT cholangiography in the setting of inconclusive MRCP

International Nuclear Information System (INIS)

McSweeney, Sean E.; Kim, Tae Kyoung; Jang, Hyun-Jung; Khalili, Korosh

2012-01-01

Objective: To determine the utility of CT cholangiography (CT-Ch) in preoperative evaluation of the biliary anatomy of living-donor liver transplantation (LDLT) donors when magnetic resonance cholangiopancreatography (MRCP) is inconclusive. Materials and methods: Over a 2-year period, 22 potential living liver donors underwent contrast-enhanced CT-Ch for preoperative evaluating biliary anatomy due to inconclusive results on MRCP and subsequently donated their right hepatic lobe. Nineteen of them underwent intraoperative cholangiography and were included in this study. Two radiologists retrospectively reviewed both MRCP and CT-Ch with 1-month interval and documented the types of bile duct branching patterns and visualization score of intrahepatic bile ducts (4-point scale). Results: There were no complications associated with CT-Ch examinations. CT-Ch was concordant with the reference standard in 18/19 (95%) including 7/8 typical branching type and 11/11 anomalous branching types. MRCP was concordant with the reference standard in 14/19 (74%) including 4/8 typical branching types and 10/11 anomalous branching types. The discordant case by CT-Ch was the identification of a tiny accessory right intrahepatic duct joining the common bile duct which was not visualized on intraoperative cholangiography. CT-Ch showed higher visualization score (mean, 3.9) than MRCP (mean, 2.6) (P < .001). Conclusion: CT-Ch can be effectively used for the depiction of the branching pattern of the bile duct at the hepatic hilum when MRCP is inconclusive.

Postprandial changes in secretory flow of pancreatic juice in the main pancreatic duct: evaluation with cine-dynamic MRCP with a spatially selective inversion-recovery (IR) pulse.

Science.gov (United States)

Yasokawa, Kazuya; Ito, Katsuyoshi; Tamada, Tsutomu; Yamamoto, Akira; Hayashida, Minoru; Torigoe, Teruyuki; Tanimoto, Daigo; Higaki, Atsushi; Noda, Yasufumi; Kido, Ayumu

2016-12-01

To evaluate the influence of oral ingestion on the secretory flow dynamics of physiological pancreatic juice within the main pancreatic duct in healthy subjects by using cine-dynamic MRCP with spatially-selective inversion-recovery (IR) pulse non-invasively. Thirty-eight healthy subjects were investigated. MRCP with spatially-selective IR pulse was repeated every 15 s for 5 min to acquire a total of 20 images (cine-dynamic MRCP). A set of 20 MRCP images was repeatedly obtained before and after liquid oral ingestion every 7 min (including 2-min interval) for 40 min (a total of seven sets). Secretion grade of pancreatic juice on cine-dynamic MRCP was compared before and after oral ingestion using the nonparametric Wilcoxon signed-rank test. Median secretion grades of pancreatic juice at 5 min (score = 2.15), 12 min (score = 1.95) and 19 min (score = 2.05) after ingestion were significantly higher than that before ingestion (score = 1.40) (P = 0.004, P = 0.032, P = 0.045, respectively). Secretion grade of pancreatic juice showed a maximum peak of 2.15 at 5 min after ingestion. Thereafter, the secretion grade of pancreatic juice tended to gradually decline. Non-invasive cine-dynamic MRCP using spatially-selective IR pulse showed potential for evaluating postprandial changes in the secretory flow dynamics of pancreatic juice as a physiological reaction. • Secretion grade of pancreatic juice at cine-dynamic MRCP after ingestion was evaluated. • Secretion grade was significantly increased within 19 min after liquid meal ingestion. • Secretion grade showed maximum peak of 2.15 at 5 min after ingestion. • Postprandial changes in pancreatic juice flow can be assessed by cine-dynamic MRCP.

Magnetic Resonance Cholangiopancreatography: Image Quality, Ductal Morphology, and Value of Additional T2- and T1-weighted Sequences for the Assessment of Suspected Pancreatic Cancer

International Nuclear Information System (INIS)

Lopez Haenninen, E.; Ricke, H.; Amthauer, H.; Roettgen, R.; Boehmig, M.; Langrehr, J.; Pech, M.; Denecke, T.; Rosewicz, S.; Felix, R.

2005-01-01

Purpose: To assess image quality and duct morphology on magnetic resonance cholangiopancreatography (MRCP) and also the value of additional T2- and T1-weighted sequences for differentiation of benignity and malignancy in patients with suspected pancreatic tumors. Material and Methods: One-hundred-and-fourteen patients received MRCP and unenhanced and contrast material-enhanced MR imaging. MR results were analyzed independently by two blinded readers, and subsequently correlated with the results from surgery, biopsy, and follow-up. Assessment included the evaluation of image quality, duct visualization and morphology, and the differentiation of pancreatic lesion status (benign versus malignant).Results: Overall, 49 patients had benign final diagnoses, while 65 had a malignant diagnosis. Image quality of single-shot thick-slab MRCP was rated significantly better than the MIP images of multisection MRCP. With MRCP alone, the two readers' accuracy in the assessment of pancreatic lesion status was 72% (95% CI, 64% to 83%) and 69% (95% CI, 56% to 77%), respectively; with the addition of T2- and T1-weighted images the accuracy significantly improved to 89% (95% CI, 82% to 95%) and 84% (95% CI, 77% to 92%) for readers 1 and 2, respectively. Conclusion: Single-shot thick-slab MRCP and multisection MRCP provide complementary results; however, single-shot MRCP had superior image quality. Moreover, assessment of ductal morphology with MRCP alone facilitated the diagnosis of different pathologic conditions of the pancreatobiliary system in the majority of patients. However, with the addition of T2- and T1-weighted sequences the overall diagnostic accuracy was significantly improved and thus we consider that a comprehensive MR approach should comprise both MRCP techniques and parenchymal sequences

Usefulness of MR cholangiopancreatography after intravenous morphine administration

International Nuclear Information System (INIS)

Lee, So Jung; Ko, Ji Ho; Cho, Young Duk; Jung, Mi Hee; Yoon, Byung Chull

2007-01-01

We wanted to assess the usefulness of MRCP after intravenous morphine administration in the evaluation of the hepatopancreatic pancreatico-biliary ductal system. We studied 15 patients who were suspected of having disease of hepatopancreatic ductal system and they did not have any obstructive lesion on ultrasonography and/or CT. MRCP was acquired before and after morphine administration (0.04 mg/kg, intravenously). Three radiologists scored the quality of the images of the anatomic structures in the hepatopancreatic ductal system. We directly compared the quality of the images obtained with using the two methods and the improvement of the artifacts by pulsatile vascular compression. The MRCP images obtained after intravenous morphine administration were better than those obtained before morphine administration for visualizing the hepatopancreatic ductal system. On direct comparison, the MRCP images obtained after morphine administration were better in 12 cases, equivocal in two cases, and the images before morphine administration were better in only one case. In three patients, MRCP before morphine injection showed signal loss at the duct across the pulsatile hepatic artery. In two of three patients, MRCP after morphine injection showed no signal loss in this ductal area. MRCP after intravenous morphine administration enables physicians to see the hepatopancreatic ductal system significantly better and the artifacts caused by pulsation of the hepatic artery can be avoided

MR cholangio-pancreatography using an open, low magnetic field of 0.2 Tesla. Early clinical results and comparison with a higher magnetic field (1.5 Tesla) and with ERCP

International Nuclear Information System (INIS)

Wacker, Q.; Branding, G.; Wolf, K.J.; Zimmer, T.; Faiss, S.

1997-01-01

Aim: To evaluate MR cholangio-pancreatography (MRCP) using an open low magnetic field apparatus in normals and in patients with mechanical cholestasis. Methods: MRCP was performed on five normals and on 30 patients, using both an 0.2 Tesla and 1.5 Tesla apparatus. With the low field system, rapid acquisition by relaxation enhancement was used, for the high field system, half Fourier acquisition single shot turbo spin-echo sequences were used. In all patients, sonography and ERCP of PTC was performed; 23 underwent surgery. Results: In all normals it was possible to show the bile duct, hepatic duct, gall bladder and intrahepatic ducts of the first order. Using the high field system, second order ducts could be shown and sometimes third order ducts. In the patients, MRCP, using either system, demonstrated all 21 obstructive sites due to tumours or stenoses. Stones were shown in 69% by the low field system and in 88% by the high field system. Conclusion: MRCP can be successfully carried out using the low field system. In the presence of mechanical cholestasis, image quality is adequate for the localisation of stenoses and occlusions, and using an open magnet, is suitable for planning further intervention. (orig.) [de

Postprandial changes in secretory flow of pancreatic juice in the main pancreatic duct: evaluation with cine-dynamic MRCP with a spatially selective inversion-recovery (IR) pulse

International Nuclear Information System (INIS)

Yasokawa, Kazuya; Ito, Katsuyoshi; Tamada, Tsutomu; Yamamoto, Akira; Hayashida, Minoru; Torigoe, Teruyuki; Tanimoto, Daigo; Higaki, Atsushi; Noda, Yasufumi; Kido, Ayumu

2016-01-01

To evaluate the influence of oral ingestion on the secretory flow dynamics of physiological pancreatic juice within the main pancreatic duct in healthy subjects by using cine-dynamic MRCP with spatially-selective inversion-recovery (IR) pulse non-invasively. Thirty-eight healthy subjects were investigated. MRCP with spatially-selective IR pulse was repeated every 15 s for 5 min to acquire a total of 20 images (cine-dynamic MRCP). A set of 20 MRCP images was repeatedly obtained before and after liquid oral ingestion every 7 min (including 2-min interval) for 40 min (a total of seven sets). Secretion grade of pancreatic juice on cine-dynamic MRCP was compared before and after oral ingestion using the nonparametric Wilcoxon signed-rank test. Median secretion grades of pancreatic juice at 5 min (score = 2.15), 12 min (score = 1.95) and 19 min (score = 2.05) after ingestion were significantly higher than that before ingestion (score = 1.40) (P = 0.004, P = 0.032, P = 0.045, respectively). Secretion grade of pancreatic juice showed a maximum peak of 2.15 at 5 min after ingestion. Thereafter, the secretion grade of pancreatic juice tended to gradually decline. Non-invasive cine-dynamic MRCP using spatially-selective IR pulse showed potential for evaluating postprandial changes in the secretory flow dynamics of pancreatic juice as a physiological reaction. (orig.)

Postprandial changes in secretory flow of pancreatic juice in the main pancreatic duct: evaluation with cine-dynamic MRCP with a spatially selective inversion-recovery (IR) pulse

Energy Technology Data Exchange (ETDEWEB)

Yasokawa, Kazuya; Ito, Katsuyoshi; Tamada, Tsutomu; Yamamoto, Akira; Hayashida, Minoru; Torigoe, Teruyuki; Tanimoto, Daigo; Higaki, Atsushi; Noda, Yasufumi; Kido, Ayumu [Kawasaki Medical School, Department of Diagnostic Radiology, Kurashiki, Okayama (Japan)

2016-12-15

To evaluate the influence of oral ingestion on the secretory flow dynamics of physiological pancreatic juice within the main pancreatic duct in healthy subjects by using cine-dynamic MRCP with spatially-selective inversion-recovery (IR) pulse non-invasively. Thirty-eight healthy subjects were investigated. MRCP with spatially-selective IR pulse was repeated every 15 s for 5 min to acquire a total of 20 images (cine-dynamic MRCP). A set of 20 MRCP images was repeatedly obtained before and after liquid oral ingestion every 7 min (including 2-min interval) for 40 min (a total of seven sets). Secretion grade of pancreatic juice on cine-dynamic MRCP was compared before and after oral ingestion using the nonparametric Wilcoxon signed-rank test. Median secretion grades of pancreatic juice at 5 min (score = 2.15), 12 min (score = 1.95) and 19 min (score = 2.05) after ingestion were significantly higher than that before ingestion (score = 1.40) (P = 0.004, P = 0.032, P = 0.045, respectively). Secretion grade of pancreatic juice showed a maximum peak of 2.15 at 5 min after ingestion. Thereafter, the secretion grade of pancreatic juice tended to gradually decline. Non-invasive cine-dynamic MRCP using spatially-selective IR pulse showed potential for evaluating postprandial changes in the secretory flow dynamics of pancreatic juice as a physiological reaction. (orig.)

Implementing statistical equating for MRCP(UK) Parts 1 and 2.

Science.gov (United States)

McManus, I C; Chis, Liliana; Fox, Ray; Waller, Derek; Tang, Peter

2014-09-26

The MRCP(UK) exam, in 2008 and 2010, changed the standard-setting of its Part 1 and Part 2 examinations from a hybrid Angoff/Hofstee method to statistical equating using Item Response Theory, the reference group being UK graduates. The present paper considers the implementation of the change, the question of whether the pass rate increased amongst non-UK candidates, any possible role of Differential Item Functioning (DIF), and changes in examination predictive validity after the change. Analysis of data of MRCP(UK) Part 1 exam from 2003 to 2013 and Part 2 exam from 2005 to 2013. Inspection suggested that Part 1 pass rates were stable after the introduction of statistical equating, but showed greater annual variation probably due to stronger candidates taking the examination earlier. Pass rates seemed to have increased in non-UK graduates after equating was introduced, but was not associated with any changes in DIF after statistical equating. Statistical modelling of the pass rates for non-UK graduates found that pass rates, in both Part 1 and Part 2, were increasing year on year, with the changes probably beginning before the introduction of equating. The predictive validity of Part 1 for Part 2 was higher with statistical equating than with the previous hybrid Angoff/Hofstee method, confirming the utility of IRT-based statistical equating. Statistical equating was successfully introduced into the MRCP(UK) Part 1 and Part 2 written examinations, resulting in higher predictive validity than the previous Angoff/Hofstee standard setting. Concerns about an artefactual increase in pass rates for non-UK candidates after equating were shown not to be well-founded. Most likely the changes resulted from a genuine increase in candidate ability, albeit for reasons which remain unclear, coupled with a cognitive illusion giving the impression of a step-change immediately after equating began. Statistical equating provides a robust standard-setting method, with a better

Mucinous cystic neoplasms and serous cystadenomas arising in the body-tail of the pancreas: MR imaging characterization

Energy Technology Data Exchange (ETDEWEB)

Manfredi, Riccardo; Ventriglia, Anna; Mehrabi, Sara; Boninsegna, Enrico; Pozzi Mucelli, Roberto [University of Verona, Department of Radiology, Verona (Italy); Mantovani, William [Provincial Health Services, Department of Public Health and Prevention, Trento (Italy); Zamboni, Giuseppe [University of Verona, Department of Pathology, Verona (Italy); Salvia, Roberto [University of Verona, Department of Surgery, Verona (Italy)

2015-04-01

To identify magnetic resonance (MR)/MR cholangiopancreatography (MRCP) imaging signs helpful in the differential diagnosis between serous cystadenomas (SCAs) and mucinous cystic neoplasms (MCNs), arising from the body/tail of the pancreas. This retrospective study had institutional review board approval and informed consent was waived. Fifty-three patients with non-communicating cystic pancreatic neoplasm of the body/tail, undergoing MR/MRCP, were included. Qualitative image analysis assessed the macroscopic pattern, number of cysts, presence of central scar, contrast enhancement of peripheral wall, and mural nodules. Quantitative analysis assessed the maximum diameter of the neoplasm, thickness of the peripheral wall, and calibre of the upstream main pancreatic duct. Histopathology results revealed that 27/53 (51 %) were SCAs, 26/53 (49 %) were MCNs. Microcystic pattern was observed in 88.2 % of SCAs and 11.8 % of MCNs; macrocystic pattern was observed in 90.5 % of MCNs and 9.5 % of SCAs (p < 0.0001). Central scar was detected in 29.6 % of SCAs and no MCNs (p = 0.003). Contrast enhancement of the peripheral wall was evident in 99.5 % of MCNs and 11.5 % of SCAs (p < 0.0001); mural nodules were depicted in 94.1 % of MCNs and 5.9 % of SCAs (p < 0.0001). Median maximum diameter was 54 mm for MCNs, 32 mm for SCAs (p = 0.001); median wall thickness was 4 mm for MCNs, 2 mm for SCAs (p < 0.0001). Macrocystic pattern, enhancement of a peripheral wall and mural nodules are suggestive of MCNs; whereas microcystic pattern, lack of peripheral wall and central scar are suggestive of SCAs. (orig.)

Focal Pancreatitis Mimicking Pancreatic Mass: Magnetic Resonance Imaging (MRI)/Magnetic Resonance Cholangiopancreatography (MRCP) Findings Including Diffusion-Weighted MRI

International Nuclear Information System (INIS)

Momtahen, A.J.; Balci, N.C.; Alkaade, S.; Akduman, E.I.; Burton, F.R.

2008-01-01

Background: Focal pancreatitis (FP) is a confined inflammation that mimics a pancreatic mass. Its imaging diagnosis is important to avoid unnecessary procedures. Purpose: To describe the spectrum of magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP) and diffusion-weighted MRI (DWI) findings of focal pancreatitis mimicking pancreatic masses. Material and Methods: Findings of MRI/MRCP including DWI with a b value of 0 and 600 s/mm2 in 14 patients with pancreatic masses on MRI were retrospectively reviewed and compared to normal pancreas in 14 patients as a control group. Results: FP revealed hypointense signal intensity (SI) (3/14), hypo- to isointense SI (7/14), or isointense SI (4/14) on T1-weighted images, and hypointense SI (1/14), isointense SI (5/14), iso- to hyperintense SI (7/14), or hyperintense SI (1/14) on T2-weighted images compared to remaining pancreas (RP). MRCP images revealed dilatation of the common bile duct (CBD) and main pancreatic duct (MPD) (5/14), dilatation of the MPD only (3/14), dilatation of the CBD only (3/14), and normal MPD and CBD (3/14). Both FP and RP revealed three types of time-signal intensity curves: 1) rapid rise to a peak, with a rapid decline (FP=2, RP=4), 2) slow rise to a peak, followed by a slow decline (FP=5, RP=4), and 3) slower rise to a peak, with a slow decline or plateau (FP=7, RP=6). Mean apparent diffusion coefficient (ADC) values for FP and RP were 2.09±0.18 and 2.03±0.2x10 -3 mm 2 /s, respectively. ADC values of FP and RP revealed no significant difference. Conclusion: The spectrum of imaging findings of focal pancreatitis on MRI/MRCP including DWI was described. Findings of FP were not distinctive as compared to the remaining pancreas

Evaluation of late stage iatrogenic extrahepatic bile duct stricture by using magnetic resonance cholangiopancreagraphy

International Nuclear Information System (INIS)

Sun Changjin; Zhou Xiangping; Liu Rongbo; Song Bin; Yan Zhihan; Chen Xian; Wang Wentao; Xiong Yan; Xu Minsheng; Gu Jianping

2003-01-01

Objective: To assess the role of magnetic resonance cholangiopancreagraphy (MRCP) in the preoperative evaluation of late stage iatrogenic extrahepatic bile duct stricture. Methods: Eighteen cases, which were diagnosed as late stage iatrogenic extrahepatic bile duct strictures only by MRCP and proved by surgery and pathology, were classified according to Bismuth classification and the surgical operation strategy was planed on the basis of MR cholangiopancreagraphic findings before surgery. The results were compared with surgery. Results: Diagnostic MR Cholangiopancreagrams were acquired in 18 patients. Among all 18 patients, the level of stricture was classified as Bismuth I in 3 patients, Bismuth II in 7 patients, Bismuth III in 3 patients, and Bismuth IV in 3 patients. A Bismuth II stricture was incorrectly classified as a Bismuth III lesion. On the basis of MR cholangiopancreagraphic findings, a surgical operation strategy can be planed. The therapeutic plan anticipated with MRCP matched the actually used procedure in 16 of 18 patients. conclusion: MRCP plays an important role in the evaluation of late stage iatrogenic extrahepatic bile duct stricture

Single dose oral ranitidine improves MRCP image quality: a double-blind study

International Nuclear Information System (INIS)

Bowes, M.T.; Martin, D.F.; Melling, A.; Roberts, D.; Laasch, H.-U.; Sukumar, S.; Morris, J.

2007-01-01

Aim: To investigate the possibility of whether a single 300 mg dose of ranitidine given orally 2-3 h before magnetic resonance cholangiopancreatography (MRCP) could reduce the signal from the stomach and duodenum, and thus increase the conspicuousness of the biliary tree. Materials and methods: Thirty-five volunteers (22 female, 13 male), (age range 21-50) were underwent MRCP in a double-blind, placebo-controlled, randomized, crossover trial on a Philips Intera 1.5 T machine using a phased array surface coil. Imaging was carried out in the coronal oblique plane. Six 40 mm sections were acquired at varying angles to delineate the biliary tree and pancreatic duct. The 70 examinations were blindly scored by three consultants experienced in cholangiography. Results: After ranitidine administration there was a significant decrease in signal from the stomach (mean = 17.7, p = 0.0005, CI 10, 25.3) and duodenum (mean = 18.4, p = 0.0005, 95%CI 9.6, 27.1) with a significant increase in conspicuousness of the distal common duct (mean = 7.7, p = 0.033, 95%CI 0.7, 14.7) and proximal common duct (mean = 8.7, p = 0.010 CI 2.2, 15.2). There were no adverse effects. Conclusion: Oral ranitidine is a cheap and effective agent to decrease signal from the upper gastrointestinal tract and to improve visibility of the biliary tree

Evaluation of pancreatic exocrine insufficiency by cine-dynamic MRCP using spatially selective inversion-recovery (IR) pulse: Correlation with severity of chronic pancreatitis based on morphological changes of pancreatic duct.

Science.gov (United States)

Yasokawa, Kazuya; Ito, Katsuyoshi; Kanki, Akihiko; Yamamoto, Akira; Torigoe, Teruyuki; Sato, Tomohiro; Tamada, Tsutomu

2018-05-01

To evaluate the correlation between the pancreatic exocrine insufficiency estimated by cine-dynamic MRCP using spatially selective IR pulse and the severity stages (modified Cambridge classification) based on morphological changes of the pancreatic duct in patients with suspected chronic pancreatitis. Thirty-nine patients with suspected chronic pancreatitis underwent cine-dynamic MRCP with a spatially selective IR pulse. The secretion grading score (5-point scale) based on the moving distance of pancreatic juice inflow on cine-dynamic MRCP was assessed, and compared with the stage of the severity of chronic pancreatitis based on morphological changes of pancreatic duct. The stage of the severity of chronic pancreatitis based on morphological changes had significant negative correlations with the secretion grade (r=-0.698, P0.70 in 2 (33%) of 6 patients showing normal pancreatic exocrine function. It should be noted that the degree of morphological changes of pancreatic duct does not necessarily reflect the severity of pancreatic exocrine insufficiency at cine-dynamic MRCP in stage 2-3 chronic pancreatitis. Copyright © 2017 Elsevier Inc. All rights reserved.

Vergleich von 2D- und 3D-Sequenzen für die MRCP. Klinischer Stellenwert der einzelnen Techniken

NARCIS (Netherlands)

Wallnoefer, A. M.; Herrmann, K. A.; Beuers, U.; Zech, C. J.; Gourtsoyianni, S.; Reiser, M. F.; Schoenberg, S. O.

2005-01-01

Magnetic resonance cholangio-pancreaticograpy (MRCP) is a non-invasive imaging modality of the pancreatico-biliary system which plays an increasingly important role in the clinical and diagnostic workup of patients with biliary or pancreatic diseases. The present review is designed to give an

[Comparison of 2D and 3D sequences for MRCP. Clinical value of the different techniques].

Science.gov (United States)

Wallnoefer, A M; Herrmann, K A; Beuers, U; Zech, C J; Gourtsoyianni, S; Reiser, M F; Schoenberg, S O

2005-11-01

Magnetic resonance cholangio-pancreaticograpy (MRCP) is a non-invasive imaging modality of the pancreatico-biliary system which plays an increasingly important role in the clinical and diagnostic workup of patients with biliary or pancreatic diseases. The present review is designed to give an overview of the currently available and appropriate sequences, their technical background, as well as new developments and their relevance to the various clinical issues and challenges. The impact of the latest technical innovations, such as integrated parallel imaging techniques and navigator-based respiratory triggering, on the diagnostic capacities of MRCP is discussed. In this context, the individual value of RARE, T2w single shot turbo/fast spin echo (SSFSE) and the recently introduced 3D T2w turbo/fast spin echo sequences (T2w 3D-T/FSE) is reviewed. RARE imaging may be preferred in severely ill patients with limitations in cooperation, SSFSE is particularly effective in differentiating benign and malignant stenosis, and 3D-FSE offers additional advantages in the detection of small biliary concrements.

MR cholangiopancreatography: prospective comparison of a breath-hold 2D projection technique with diagnostic ERCP

International Nuclear Information System (INIS)

Lomas, D.J.; Bearcroft, P.W.P.; Gimson, A.E.

1999-01-01

The aim of this study was to compare prospectively a breath-hold projection magnetic resonance cholangiopancreatography (MRCP) technique with diagnostic endoscopic retrograde cholangiopancreatography (ERCP). Seventy-six patients with suspected strictures or choledocholithiasis were referred for MRCP and subsequent ERCP examination, which were performed within 4 h of each other. The MRCP technique was performed using fat-suppressed rapid acquisition with relaxation enhancement (RARE) projection images obtained in standardised planes with additional targeted projections as required by the supervising radiologist. Two radiologists (in consensus) assessed the MRCP results prospectively and independently for the presence of bile duct calculi, strictures, non-specific biliary dilatation and pancreatic duct dilatation, and recorded a single primary diagnosis. The ERCP was assessed prospectively and independently by a single endoscopist and used as a gold standard for comparison with MRCP. Diagnostic agreement was assessed by the Kappa statistic. The MRCP technique failed in two patients and ERCP in five. In the remaining 69 referrals ERCP demonstrated normal findings in 23 cases, strictures in 19 cases, choledocholithiasis in 9 cases, non-specific biliary dilatation in 14 cases and chronic pancreatitis in 4 cases. The MRCP technique correctly demonstrated 22 of 23 normal cases, 19 strictures with one false positive (sensitivity 100 %, specificity 98 %), all 9 cases of choledocholithiasis with two false positives (sensitivity 100 %, specificity 97 %), 12 of 14 cases of non-specific biliary dilatation and only 1 of 4 cases of chronic pancreatitis. There was overall good agreement for diagnosis based on a kappa value of 0.88. Breath-hold projection MRCP can provide non-invasively comparable diagnostic information to diagnostic ERCP for suspected choledocholithiasis and biliary strictures and may allow more selective use of therapeutic ERCP. (orig.)

MRCP and 3D LAVA imaging of extrahepatic cholangiocarcinoma at 3 T MRI

Energy Technology Data Exchange (ETDEWEB)

Li, N.; Liu, C.; Bi, W.; Lin, X.; Jiao, H. [Shandong Medical Imaging Research Institute, Shandong University, Jinan (China); Zhao, P., E-mail: Gavinsdu@163.com [Department of Radiology, Shandong Provincial Hospital, Shandong University, Jinan (China)

2012-06-15

Extrahepatic cholangiocarcinoma (CCA) is a primary bile duct malignant tumour with poor prognosis. Familiarity with their varied imaging characteristics can be helpful in developing a correct diagnosis and in optimal treatment planning, and thus contribute to a better prognosis. The purpose of this article is to illustrate the typical appearances of extrahepatic CCA on magnetic resonance cholangiopancreatography (MRCP) and three-dimensional (3D) LAVA (liver acquisition with volume acceleration) sequences at 3 T magnetic resonance imaging (MRI), and to discuss the superiority of the two techniques in the diagnosis of CCA.

Secretin-stimulating MRCP in patients with pancreatobiliary maljunction and occult pancreatobiliary reflux: direct demonstration of pancreatobiliary reflux

Energy Technology Data Exchange (ETDEWEB)

Motosugi, Utaroh; Ichikawa, Tomoaki; Araki, Tsutomu [University of Yamanashi, Department of Radiology, Chuo-shi, Yamanashi (Japan); Kitahara, Fumiaki; Sato, Tadashi [University of Yamanashi, First Department of Internal Medicine, Chuo-shi, Yamanashi (Japan); Itakura, Jun; Fujii, Hideki [University of Yamanashi, First Department of Surgery, Chuo-shi, Yamanashi (Japan)

2007-09-15

We propose the hypothesis that the enlargement of the common bile duct (CBD) or gallbladder (GB) that is occasionally demonstrated on magnetic resonance cholangiopancreatography (MRCP) after secretin stimulation is caused by pancreatobiliary reflux. Recently, occult pancreatobiliary reflux (OPR) has been demonstrated in patients without morphological pancreatobiliary maljunction (MPBM). The aim of this study was to evaluate the efficacy of secretin-stimulating MRCP (SMRCP) in the diagnosis of pancreatobiliary reflux. The study included 14 patients with MPBM and 32 patients with a normal pancreatobiliary junction. OPR was evaluated by bile collection and diagnosed in seven of the 32 patients. All the patients underwent SMRCP; the related findings were considered positive when enlargement of the CBD or GB was observed. Positive findings on SMRCP were observed in all MPBM patients. In the patients with normal pancreatobiliary junction, there was significant difference between the mean amylase levels in the patients with positive and negative SMRCP findings (mean, 4,755.7 and 29.7 IU/l). The sensitivity and specificity of SMRCP for diagnosing OPR was 85.7% and 68.0%, respectively. SMRCP provides a non invasive method for excluding PBR and can identify patients who could benefit from bile duct sampling to diagnose OPR. (orig.)

Oral gadopentetate dimeglumine administration as a negative gastrointestinal contrast agent to improve image quality of MR cholangiopancreatography

International Nuclear Information System (INIS)

Chen Yi; Xu Yikai; Zhao Yuhui; Wang Guisheng

2008-01-01

Objective: To choose optimal concentration and volume of Gd-DTPA solution as a oral gastrointestinal negative contrast agent for MRCP. To evaluate the role of Gd-DTPA solution in improving image quality of MRCP. Methods: In vitro experiment: Gd-DTPA solution was made with different concentrations. T 1 WI, T 2 WI, two-dimensional single slice fast spin echo sequence and three-dimensional half-fourier acquisition single-shot fast spin echo sequence were performed to measure the signal intensity of these contrast agents respectively, so Gd-DTPA solution with the optimal concentration can be decided as oral negative gastrointestinal contrast agent on MRCP. Clinical study: The Gd-DTPA solution with optimal concentration and volume was regarded as an oral negative gastrointestinal contrast agent of MRCP. Twenty- four' patients were performed with MRCP before and after (5-10 minutes and 10-15 minutes) administration of oral negative gastrointestinal contrast agent and image quality was analyzed. Statistical analysis was performed using analysis of variance with SPSS 10.0. Results: When the concentration of Gd-DTPA solution was ≤0.01 mol/L, the contrast agent was hyperintense on T 1 WI. On T 2 WI, when the concentration was ≥0.015 mol/L, it was as hypointense as basic ground; On 2D FSE MRCP images, controls were hyperintense and the contrast agent with concentration ranging from 0.0025 mol/L to 0.03 mol/L was hypointense. On 3D HEAST MRCP image, controls were hyperintense and when the concentration of Gd-DTPA was ≥0.01 mol, the contrast agent was hypointense. The Gd-DTPA solution with the concentration of 0.01 mol/L and the volume of 100 ml was chosen as MRCP oral negative gastrointestinal contrast agent. On MRCP images after oral administration of the contrast agent, in 10-15 minutes, the average grade scores within 24 patients of the intrahepatic bile duct, the common hepatic bile duct, the gall bladder, the common bile duct and pancreatic duct (the average grade

Pancreatic changes in patients with primary sclerosing cholangitis: MR cholangiopancreatography and MRI findings

International Nuclear Information System (INIS)

Ozkavukcu, Esra; Erden, Ayse; Erden, Ilhan

2009-01-01

Purpose: To evaluate the possible pancreatic changes and their frequencies in patients with primary sclerosing cholangitis (PSC) on MR cholangiopancreatography (MRCP), and conventional abdominal MRI. Materials and Methods: Patient group consisted of 29 PSC (13 male, 16 female) cases, whereas cohort 1 consisted of 12 female patients with primary biliary cirrhosis, and cohort 2 consisted of 17 patients (6 male, 11 female) with non-immune chronic liver disease. Two radiologists retrospectively evaluated the MR examinations paying special attention to the pancreatic size (atrophy or enlargement), T1- and T2-signal intensity of the pancreas, focal pancreatic lesion, capsule-like rim, peripancreatic edema or fluid, fascial thickening, and pancreatic ducts (dilatation or narrowing). The results are expressed as percentages. Three groups were compared using Pearson chi-square test for each feature. However, only p-value for 'dilatation of the pancreatic duct' was determined, whereas p-value could not be calculated because of the insufficient number of subjects/sequences for the other features. Results: Twelve PSC patients (41.3%) had pancreatic abnormalities. The most common pancreatic changes in PSC patients were decreased T1-signal intensity (44%) and dilatation of the pancreatic duct (13.8%), respectively. Increased T2-signal intensity was also shown in 2 PSC patients (6.9%). Conclusion: Even PSC patients without any sign of pancreatitis, can show MR changes in the pancreatic parenchyma or the pancreatic duct. The etiologies of these changes, and whether they are unique to PSC, are still controversial. Histopathological studies bringing light to these pancreatic changes are needed.

Quality rating of MR-cholangiopancreatography with oral application of iron oxide particles; Wertigkeit der MR-Cholangiopankreatikographie nach Gabe eines oralen eisenhaltigen Kontrastmittels

Energy Technology Data Exchange (ETDEWEB)

Lorenzen, M.; Wedegaertner, U.; Fiehler, J.; Adam, G. [Universitaetsklinikum Hamburg, Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie (Germany)

2003-07-01

the pancreas and 0.66 for the right hepatic duct. Conclusion: Despite the trend toward a better rating of the image quality for all sections of the pancreaticobiliary ductal system with Loesferron{sup circledR}, a significant difference was not found in any ductal section after correction for multiple testing. Thus, we believe that the ingestion of Loeseferron {sup trademark} is not absolutely required prior MRCP. (orig.) [German] Zielsetzung: Vergleichende Untersuchung zur Bildqualitaet der MR-Cholangiopankreatikographie (MRCP) ohne und mit oraler Loeseferron {sup trademark} -Gabe (Eisen (II)-gluconat, Lilly Pharma, Hamburg). Material und Methode: In einer prospektiven Studie wurden in einem Zeitraum von 4 Monaten 52 Patienten mittels MRCP (1,5 T) untersucht. Die 1. Gruppe (n=27) bekam unmittelbar vor der Untersuchung 0,5 l eines eisenhaltigen KM zu trinken. Bei der 2. Gruppe wurde auf das KM verzichtet. Es wurden 7 RARE-Seq. (40-20 ) und eine hieraus ausgewaehlte 3 mm HASTE (T{sub 2}w+FS) erstellt. Die Qualitaet wurde von zwei Radiologen geblindet und segmentbezogen: Li. und re. Ductus hepaticus (li. DH und re. DH), extrahepatischer Gallengang (DHC), intrapankreatisch verlaufender Gallengang (DHC ip) und Pankreasgang: Kaput (PGKA), Korpus (PGKO), Kauda (PGKU) auf einer Skala (1 - nicht abgrenzbar bis 5 - sehr gut abgrenzbar) beurteilt. Die statistische Auswertung erfolgte mittels SPSS. Fuer den Stichprobenvergleich der jeweiligen Gangabschnitte diente der Wilcoxon-Mann-Whitney-Test mit Alpha-Adjustierung. Ergebnisse: Die Untersuchung mit oralem Kontrastmittel (Loeseferron {sup trademark}) wurde von allen 27 Patienten gut toleriert. Bei allen 52 Patienten konnten saemtliche Sequenzen akquiriert und beurteilt werden. Die Mittelwerte der beurteilten Gangabschnitte ergaben fuer den li, DH 3,28 ohne KM/3,36 mit KM, re. DH 3,26/3,33, DHC 3,46/4,0, iDHC 2,8/3,48, PGKA 2,8/3,24, PGKO 2,84/3,38, PGKU 2,68/3,22 auf der 5-Punkte-Skala. Die Unterschiede mit und ohne KM waren

Magnetic resonance cholangiopancreatography findings of pancreatic diseases: quantitative analysis

International Nuclear Information System (INIS)

Xu Jun; Lu Jianping; Wang Jian; Wang Fei; Liu Qi; Wang Li; Gong Jianguo; Jin Aiguo; Zeng Hao

2004-01-01

Objective: To study the MR cholangiopancreatography (MRCP) characteristics of different pancreatic diseases, and to identify the diagnostic value of MRCP for pancreatic diseases. Methods: One hundred and eleven patients with suspected pancreatic diseases underwent MRCP examination. The MRCP sequences included thick-slice turbo spin echo (TSE) and thin-slice half-Fourier acquisition single shot turbo spin echo (HASTE) sequences. The pancreatic diseases included pancreatic carcinoma (n=46), chronic pancreatitis (n=39), peri-ampullar carcinoma (n=23), and choledocholith (n=3). Results: (1) The abnormal manifestation of pancreatic duct was observed in 37 cases of pancreatic carcinoma, 24 cases of chronic pancreatitis, and 12 cases of peri-ampullar carcinoma. Dilated pancreatic duct with smooth and regular caliber was observed in 33 cases of pancreatic carcinoma, 0 case of chronic pancreatitis, and 12 cases of peri-ampullar carcinoma, and statistical analysis showed significant difference (χ 2 =57.911, P 2 =60.343, P 2 =61.217, P 2 =34.654, P 2 =54.593, P<0.01). Conclusion: Different MRI characteristics were observed in various pancreatic diseases respectively. MRCP can show the subtle differences among the pancreatic diseases, and is very helpful in the diagnosis and differential diagnosis of pancreatic diseases

[Value of MR imaging in the diagnosis of intraductal papillary neoplasm of the bile duct].

Science.gov (United States)

Song, Fengxiang; Zhou, Jun; Shi, Yuxin; Zeng, Mengsu; Zhou, Kangrong; Ding, Yuqin; Cao, Yingli; Zhou, Jianjun

2015-01-01

To analyze the value of MR imaging in diagnosis of intraductal papillary neoplasm of the bile duct (IPN-B). Fourteen patients with intraductal papillary neoplasms of the bile duct confirmed by surgical pathology were included in this study. The patients underwent MR routine plain scanning and enhancement scanning (including T1WI, T2WI with fat suppression, FALSH T1WI, and three-phase enhancement scanning), diffusion weighted imaging(DWI) and magnetic resonance cholangiopancreatography (MRCP) before operation. The imaging data were reviewed and analyzed retrospectively in comparison with the surgical and pathological results. In these patients, 7 cases had tumors located in the left lobe, 2 cases had tumors in both the left and right lobes, 2 cases in the hepatic hilum, 2 cases in the common bile duct, and 1 case in both the right lobe and the common bile duct. Solitary or multiple intraductal masses could be found in 12 cases, with 11 cases appeared as papillary masses and one case as flat mass. In the other two cases the tumor was not visible (one case had too many stones, and in another case the tumor was too small). The tumors in the 12 cases showed hypointensity on T1WI and hyperintensity on T2WI. On the dynamic contrast-enhanced MRI, 11 cases showed mild and one showed moderate enhancement in arterial phase, and all the cases showed mildly and gradually delayed enhancement. On DWI, the lesion areas showed high signal intensity in all the cases, and the ADC value of the tumor area (1.697×10(-3)mm(2)/s) was significantly lower than that of the normal bile (3.973×10(-3)mm(2)/s) (t = -10.94, P invisible tumors ). In the 3 cases with aneurysmal bile dilatation, the multiple directions of MRCP images helped to find the communication between the aneurysmal dilatation and the bile duct. All the cases showed significant proximal bile duct dilatation (the extent of dilatation >100%), and 9 cases also showed distal bile duct dilatation. Bile duct stones were noted in 6

Comparison of respiratory-triggered 3-D fast spin-echo and single-shot fast spin-echo radial slab MR cholangiopancreatography images in children

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Chavhan, Govind B.; Almehdar, Abeer; Gupta, Sumeet [The Hospital for Sick Children and University of Toronto, Department of Diagnostic Imaging, Toronto (Canada); Moineddin, Rahim [University of Toronto, Department of Family and Community Medicine, Toronto (Canada); Babyn, Paul S. [Royal University Hospital, Department of Medical Imaging, Saskatoon (Canada)

2013-09-15

The two most commonly performed magnetic resonance cholangiopancreatography (MRCP) sequences, 3-D fast spin-echo (3-D FSE) and single-shot fast spin-echo radial slabs (radial slabs), have not been compared in children. The purpose of this study was to compare 3-D FSE and radial slabs MRCP sequences on a 3-T scanner to determine their ability to show various segments of pancreaticobiliary tree and presence of artifacts in children. We reviewed 79 consecutive MRCPs performed in 74 children on a 3-T scanner. We noted visibility of major ducts on 3-D FSE and radial slabs. We noted the order of branching of ducts in the right and left hepatic ducts and the degree of visibility of the pancreatic duct. Statistical analysis was performed using McNemar and signed rank tests. There was no significant difference in the visibility of major bile ducts and the order of branching in the right hepatic lobe between sequences. A higher order of branching in the left lobe was seen on radial slabs than 3-D FSE (mean order of branching 2.82 versus 2.27; P-value = 0.0002). The visibility of pancreatic duct was better on radial slabs as compared to 3-D FSE (mean value of 1.53 vs. 0.90; P-value < 0.0001). 3-D FSE sequence was artifact-free in 25/79 (31.6%) MRCP exams as compared to radial slabs, which were artifact-free in 18/79 (22.8%) MRCP exams (P-value = 0.0001). There is no significant difference in the visibility of major bile ducts between 3-D FSE and radial slab MRCP sequences at 3-T in children. However, radial slab MRCP shows a higher order of branching in the left hepatic lobe and superior visibility of the pancreatic duct than 3-D FSE. (orig.)

Tuberculosis 2: Pathophysiology and microbiology of pulmonary ...

African Journals Online (AJOL)

2005-08-01

Aug 1, 2005 ... February 2013 Downloaded from www.southsudanmedicaljournal.com. MaIN arTIClES. 10. Tuberculosis 2: Pathophysiology and microbiology of pulmonary tuberculosis. Robert L. Serafino Wania MBBS, MrCP, MSc (Trop Med). Pathophysiology. Inhalation of Mycobacterium tuberculosis leads to one of.

Graduates of different UK medical schools show substantial differences in performance on MRCP(UK Part 1, Part 2 and PACES examinations

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Mollon Jennifer

2008-02-01

Full Text Available Abstract Background The UK General Medical Council has emphasized the lack of evidence on whether graduates from different UK medical schools perform differently in their clinical careers. Here we assess the performance of UK graduates who have taken MRCP(UK Part 1 and Part 2, which are multiple-choice assessments, and PACES, an assessment using real and simulated patients of clinical examination skills and communication skills, and we explore the reasons for the differences between medical schools. Method We perform a retrospective analysis of the performance of 5827 doctors graduating in UK medical schools taking the Part 1, Part 2 or PACES for the first time between 2003/2 and 2005/3, and 22453 candidates taking Part 1 from 1989/1 to 2005/3. Results Graduates of UK medical schools performed differently in the MRCP(UK examination between 2003/2 and 2005/3. Part 1 and 2 performance of Oxford, Cambridge and Newcastle-upon-Tyne graduates was significantly better than average, and the performance of Liverpool, Dundee, Belfast and Aberdeen graduates was significantly worse than average. In the PACES (clinical examination, Oxford graduates performed significantly above average, and Dundee, Liverpool and London graduates significantly below average. About 60% of medical school variance was explained by differences in pre-admission qualifications, although the remaining variance was still significant, with graduates from Leicester, Oxford, Birmingham, Newcastle-upon-Tyne and London overperforming at Part 1, and graduates from Southampton, Dundee, Aberdeen, Liverpool and Belfast underperforming relative to pre-admission qualifications. The ranking of schools at Part 1 in 2003/2 to 2005/3 correlated 0.723, 0.654, 0.618 and 0.493 with performance in 1999–2001, 1996–1998, 1993–1995 and 1989–1992, respectively. Conclusion Candidates from different UK medical schools perform differently in all three parts of the MRCP(UK examination, with the

Diagnostic value of MRI for hepatic hilar cholangiocarcinoma

International Nuclear Information System (INIS)

Wang Zhen; Zuo Yujiang; Sun Lihui; Zhou Jian; Shen Bingqi

2010-01-01

Objective: To investigate the value of MRI in the diagnosis of hepatic hilar cholangiocarcinoma. Methods: Sixty-four patients with hepatic hilar cholangiocarcinomas confirmed by surgery or pathology underwent MRI using a 1.5-T superconductive MR system including conventional unenhanced MRI, MRCP and dynamic contrast-enhanced MRI with Gd-DTPA. Results: Dilatation of the intrahepatic biliary tree with narrowing, occlusion or filling defects in the hepatic hilar bile ducts was noted in all 64 cases. Unenhanced MR[ showed T 1 - and T 2 -hyperintense hilar masses in 42 patients and was normal in the remaining 22 patients. The hilar masses demonstrated slow, progressive and delayed enhancement patterns. There was enhancement of the thickened bile duct wall with luminal narrowing in the 22 patients without hilar masses. Conclusion: The characteristic MRI findings of enhancing hepatic hilar mass and bile duct wall thickening together with MRCP are valuable for diagnosing hepatic hilar cholangiocarcinomas. (authors)

A prospective pilot study: Can the biliary tree be visualized in children younger than 3 months on Magnetic Resonance Cholangiopancreatography?

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Siles, Pascale [La Timone Children' s Hospital, Department of Radiology, Marseille (France); Aschero, Audrey; Gorincour, Guillaume; Bourliere-Najean, Brigitte; Petit, Philippe [La Timone Children' s Hospital, Department of Pediatric Radiology, Marseille (France); Roquelaure, Bertrand [La Timone Children' s Hospital, Department of Pediatrics, Marseille (France); Delarue, Arnauld [La Timone Children' s Hospital, Department of Pediatric Surgery, Marseille (France)

2014-09-15

Magnetic resonance cholangiopancreatography (MRCP) could aid in the diagnosis of biliary atresia, a hepatic pathology with thin, irregular or interrupted biliary ducts. There is little published evidence of MRCP appearances in normal neonates and young infants. To assess the use of MR cholangiopancreatography in visualizing the biliary tree in neonates and infants younger than 3 months with no hepatobiliary disorder, and to assess this visibility in relationship to the child's age, weight, and sedation and fasting states. Between December 2008 and October 2010 our department performed MRI of the brain, orbits and face on 16 full-term neonates and infants. Each child was younger than 3 months (90 days) and without any hepatobiliary disorders. The children were scanned with a respiratory-gated 0.54 x 0.51 x 0.4-mm{sup 3} 3-D MRCP sequence. We used a reading grid to assess subjectively the visibility of the extrahepatic bile ducts along with extrahepatic bile duct confluence. The visibility of the extrahepatic bile duct confluence was assessed against age, weight, and sedation and fasting states. The extrahepatic bile duct confluence was seen in 10 children out of 16 (62.5%). In the neonate sub-group (corrected age younger than 30 days), the MRCP was technically workable and the extrahepatic bile duct confluence was seen in four cases out of eight (50%). This visualization was up to 75% in the subgroup older than 30 days. However, statistically there was no significant difference in visibility of the extrahepatic bile duct confluence in relationship to age, weight or MRCP performance conditions (feeding, fasting or sedation). The complete normal biliary system (extrahepatic bile duct confluence included) is not consistently visualized in infants younger than 3 months old on non-enhanced MRCP. Thus the use of MRCP to exclude a diagnosis of biliary atresia is compromised at optimal time of surgery. (orig.)

A prospective pilot study: Can the biliary tree be visualized in children younger than 3 months on Magnetic Resonance Cholangiopancreatography?

International Nuclear Information System (INIS)

Siles, Pascale; Aschero, Audrey; Gorincour, Guillaume; Bourliere-Najean, Brigitte; Petit, Philippe; Roquelaure, Bertrand; Delarue, Arnauld

2014-01-01

Magnetic resonance cholangiopancreatography (MRCP) could aid in the diagnosis of biliary atresia, a hepatic pathology with thin, irregular or interrupted biliary ducts. There is little published evidence of MRCP appearances in normal neonates and young infants. To assess the use of MR cholangiopancreatography in visualizing the biliary tree in neonates and infants younger than 3 months with no hepatobiliary disorder, and to assess this visibility in relationship to the child's age, weight, and sedation and fasting states. Between December 2008 and October 2010 our department performed MRI of the brain, orbits and face on 16 full-term neonates and infants. Each child was younger than 3 months (90 days) and without any hepatobiliary disorders. The children were scanned with a respiratory-gated 0.54 x 0.51 x 0.4-mm 3 3-D MRCP sequence. We used a reading grid to assess subjectively the visibility of the extrahepatic bile ducts along with extrahepatic bile duct confluence. The visibility of the extrahepatic bile duct confluence was assessed against age, weight, and sedation and fasting states. The extrahepatic bile duct confluence was seen in 10 children out of 16 (62.5%). In the neonate sub-group (corrected age younger than 30 days), the MRCP was technically workable and the extrahepatic bile duct confluence was seen in four cases out of eight (50%). This visualization was up to 75% in the subgroup older than 30 days. However, statistically there was no significant difference in visibility of the extrahepatic bile duct confluence in relationship to age, weight or MRCP performance conditions (feeding, fasting or sedation). The complete normal biliary system (extrahepatic bile duct confluence included) is not consistently visualized in infants younger than 3 months old on non-enhanced MRCP. Thus the use of MRCP to exclude a diagnosis of biliary atresia is compromised at optimal time of surgery. (orig.)

Pineapple juice labeled with gadolinium: a convenient oral contrast for magnetic resonance cholangiopancreatography

International Nuclear Information System (INIS)

Coppens, Emmanuel; Metens, Thierry; Winant, Catherine; Matos, Celso

2005-01-01

The aim of our study was to prepare in vitro a pineapple juice (PJ) solution labeled with a minimal gadolinium concentration working as a negative contrast agent in heavily T2-weighted imaging and to assess that solution in vivo as a negative oral contrast agent for magnetic resonance cholangiopancreatography (MRCP). Three PJs were compared in vitro according to their T2. Increasing concentrations of gadolinium (Gd)-DOTA in PJ were assessed in vitro for T2 reduction. Single-shot turbo spin echo T2-weighted MR cholangiopancreatograms were obtained for 35 patients with suspected biliopancreatic duct disease, before and after ingestion of the PJ/Gd-DOTA solution. Signal intensity (SI) measurements of gastroduodenal lumens, pancreatobiliary ducts, and image quality scores were obtained systematically before and after contrast ingestion. The in vitro selected Gd-DOTA concentration in the PJ was 2.76 mmol/l. Ingestion of 180 ml of PJ labeled with 1 ml of Gd-DOTA eliminated efficiently the gastroduodenal SI in MRCP, improving significantly the rates of complete visualization of the pancreatobiliary ducts (P<0.01) and the MRCP image quality scores (P<0.05). All patients easily ingested the contrast solution and found the solution palatable. PJ labeled with gadolinium constituted an efficient and convenient negative oral contrast agent for MRCP. (orig.)

Pineapple juice labeled with gadolinium: a convenient oral contrast for magnetic resonance cholangiopancreatography

Energy Technology Data Exchange (ETDEWEB)

Coppens, Emmanuel; Metens, Thierry; Winant, Catherine; Matos, Celso [Hopital Erasme, Universite Libre de Bruxelles, Department of Radiology, Division of Magnetic Resonance, Brussels (Belgium)

2005-10-01

The aim of our study was to prepare in vitro a pineapple juice (PJ) solution labeled with a minimal gadolinium concentration working as a negative contrast agent in heavily T2-weighted imaging and to assess that solution in vivo as a negative oral contrast agent for magnetic resonance cholangiopancreatography (MRCP). Three PJs were compared in vitro according to their T2. Increasing concentrations of gadolinium (Gd)-DOTA in PJ were assessed in vitro for T2 reduction. Single-shot turbo spin echo T2-weighted MR cholangiopancreatograms were obtained for 35 patients with suspected biliopancreatic duct disease, before and after ingestion of the PJ/Gd-DOTA solution. Signal intensity (SI) measurements of gastroduodenal lumens, pancreatobiliary ducts, and image quality scores were obtained systematically before and after contrast ingestion. The in vitro selected Gd-DOTA concentration in the PJ was 2.76 mmol/l. Ingestion of 180 ml of PJ labeled with 1 ml of Gd-DOTA eliminated efficiently the gastroduodenal SI in MRCP, improving significantly the rates of complete visualization of the pancreatobiliary ducts (P<0.01) and the MRCP image quality scores (P<0.05). All patients easily ingested the contrast solution and found the solution palatable. PJ labeled with gadolinium constituted an efficient and convenient negative oral contrast agent for MRCP. (orig.)

LOCUS MR: Localization of unaffected spins in MR tomography and MR spectroscopy

International Nuclear Information System (INIS)

Matthael, D.; Haase, A.

1986-01-01

Different pulse sequences have been proposed for localized in vivo MR spectroscopy. For localized MR tomography and MR spectroscopy, a method is proposed, dubbed LOCUS (LOCalization of Unaffected Spins) MR. The method uses the initial saturation of regions surrounding the region of interest (ROI) in the presence of gradients. This is followed by a conventional MR study of the unaffected ROI. In animals, human extremities, and phantoms, proton MR studies demonstrated that the method provides an optimal signal-to-noise ratio, an easily variable ROI, and ROI shim. The method can be combined with two- and three-dimensional imaging, and it allows localized measurement of MR parameters. The multinuclear capability is discussed

Imaging diagnosis of intraductal papillary mucinous tumor of the pancreas

International Nuclear Information System (INIS)

Zhang Huimao; Lai Ying; Yang Shuqin; Yang Haishan; Murakami, K.

2005-01-01

Objective: To explore the diagnostic value of intraductal papillary mucinous tumor (IPMT) of the pancreas, and to assess its clinical and characteristic radiological features. Methods: Thirty-six cases with IPMT who underwent CT and MRI with plain and contrast enhancement before operation were reviewed. The clinical presentation and characteristic imaging findings of main duct type (8 cases) and branch duct type (28 cases) were retrospectively reviewed. Results: Typical imaging findings of main duct type were segmental or diffuse dilation of MPD (diameter was over 9 mm) with enhanced mural nodules after contrast medium administration. MR cholangiopancreatography (MRCP) showed dilation of MPD with flat/nodule filling defects in 4 cases and MPD dilatation in the head side in 2 cases. Branch duct type was more frequently located in the head or uncinate. Typical imaging findings of branch duct type were unilocular or multilocular cystic tumors with septa, mural nodules, and MPD dilatation. MRCP showed septa in 24 cases, filling defects in 15 cases, and MPD dilatation in 8 cases. Communication between the cystic lesion and the MPD was demonstrated in 19 cases by MRCP. Conclusion: It is extremely important to accurately make the diagnosis of IPMT for planning the surgical strategy. MRCP is a noninvasive and useful method in detecting and making definite diagnosis of IPMT. (authors)

MR-guided MR arthrography of the shoulder

International Nuclear Information System (INIS)

Tratting, S.; Breitenseher, M.; Pretterklieber, M.; Kontaxis, G.; Rand, T.; Imhof, H.

1996-01-01

Purpose: To develop an MR-guided technique for joint puncture in MR arthrography of the shoulder and to confirm the intracapsular position of the needle tip by visualization of the flow of contrast media into the joint. Materials and methods: Three unfixed human shoulder joint specimens were examined on a 1.0 T unit. The optimal point of entrance and depth for joint puncture were estimated by means of MR-compatible markers on the skin. Needle orientation and localization of the needle tip (MR-compatible 22-gauge needle) in the shoulder joint were monitored by rapid localizer gradient-echo sequences in two orthogonal planes. To confirm the intracapsular position of the needle tip, diluted gadolinium-DTPA was administered via a long connecting tube and the flow of contrast media into the joint was viewed directly on an LCD screen using real-time MR imaging (local look technique). Results: The MR-compatible markers on the skin allowed determination of the optimal point of entrance and estimation of the depth for joint puncture. Passive visualization of the MR-compatible needle due to spin dephasing and signal loss provided adequate localization of the intra-articular needle tip position in all specimens, although significant artefacts were present on rapid localizer gradient-echo sequences with an increase in width of the apparent needle shaft. Real-time MR imaging of the flow of contrast media was possible using the local look technique and the LCD screen of the MR unit and allowed confirmation of the intracapsular position. Conclusion: MR-guided joint puncture and real-time MR-assisted contrast media application results in improved MR arthrography and may replace conventional fluoroscopic guidance. (orig.) [de

Imaging of the intrabiliary rupture of hepatic hydatid cysts

International Nuclear Information System (INIS)

Liu Wenya; Wang Jian; Liu Xinli

2009-01-01

Objective: To discuss the imaging features of ultrasonography (USG), CT /CT cholangiography (CTC), MR/MR cholangiopancreatography (MRCP) and endoscopic retrograde cholangiopancreatography (ERCP) of the hepatic hydatid cysts ruptured into biliary duct, and to evaluate the diagnostic efficacy of different modalities. Methods: Fifty one cases of hepatic hydatid cysts with intrabiliary rupture were divided into 4 groups according to imaging modality used to study these cases. 46 cases, 41 cases, 35 cases and 14 cases were examined by USG, CT, MRCP and ERCP respectively. Comparison of the imaging findings from different imaging modalities with surgical results were made to evaluate the efficacy of each imaging modality. Analysis of χ 2 were performed for the positive predictive value among the 4 groups. Results: The positive predictive values of these four methods in diagnosing the intrabiliary rupture of liver hydatid cyst were 67.4% (31/46), 80.5% (33/41), 94.3% (33/35)and respectively (χ 2 =13.1370, P<0.05). There were statistical difference between USG and 100.0% (14/14) MRCP (P<0.0084). The direct manifestations of intrabiliary rupture of hepatic hydatid cysts on USG, CT, MRCP and ERCP were as following: (1) Communication break point was seen in 3/46,3/41,9/35 and 13/14 eases respectively; (2) Increased biliary density due to the presence of membrane of echinococcus cysts and daughter cysts were seen in 5/46, 6/41,6/35 and 8/14 cases respectively; (3) Lesions adjacent to bile duct, gall bladder wall thickening, and/or interruption of bile duct, remote biliary dilatation were seen in 24/46, 26/41, 31/35 and 8/14 of cases respectively. Indirect signs included: (1) Cyst collapse, increased cyst fluid density were seen in 30/46, 33/41, 27/35 and 0/14 of cases respectively; (2) Detached membrane signs were seen in 21/46, 24/41,22/35 and 0/14; (3) Dilatation of adjacent hepatic bile duct were seen in 30/46, 29/41, 34/35 and 6/14 of cases respectively. Conclusions: Both

The effect of mastication on human motor preparation processing: a study with CNV and MRCP.

Science.gov (United States)

Sakamoto, Kiwako; Nakata, Hiroki; Honda, Yukiko; Kakigi, Ryusuke

2009-07-01

To clarify the effect of mastication on motor preparation processing using electroencephalography (EEG), we investigated the effect of mastication on contingent negative variation (CNV) and reaction time (RT) in Experiment 1, and movement-related cortical potentials (MRCPs) in Experiment 2. The twelve subjects performed four CNV or MRCP sessions, and in the Mastication condition chewed a gum base during the resting period between sessions, Pre (before chewing) and Post 1, 2, and 3 (after chewing). In the Control condition, the subjects performed the same sessions without chewing gum during the intervals between sessions on another day. In Experiment 1, the mean amplitudes of the early- and late-CNV were significantly larger in Mastication than Control at Post 2 and Post 3. RT also differed significantly between Mastication and Control at Post 3. By contrast, in Experiment 2, there were no significant differences between Mastication and Control for the mean amplitudes of MRCPs including Bereitschaftspotential (BP) and negative slope (NS') in any session. These results suggest that mastication influences cognitive processing reflected by CNV with stimulus-triggered movement, rather than motor-related processing reflected by MRCPs relating to self-initiated movement, and provide evidence concerning the mechanisms for the effect of mastication on the human brain.

MR-imaging of anterior tibiotalar impingement syndrome: Agreement, sensitivity and specificity of MR-imaging and indirect MR-arthrography

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Haller, Joerg [Department of Radiology, Hanusch Hospital, Heinrich Collin-Strasse 30, A-1140 Vienna (Austria); Ludwig Boltzmann Institute for Osteology, Hanusch Hospital, Heinrich Collin-Strasse 30, A-1140 Vienna (Austria); Bernt, Reinhard [Department of Radiology, Hanusch Hospital, Heinrich Collin-Strasse 30, A-1140 Vienna (Austria)]. E-mail: reinhard.bernt@wgkk.sozvers.at; Seeger, Thomas [Department of Trauma Surgery, Hanusch Hospital, Heinrich Collin-Strasse 30, A-1140 Vienna (Austria); Weissenbaeck, Alexander [Department of Trauma Surgery, Hanusch Hospital, Heinrich Collin-Strasse 30, A-1140 Vienna (Austria); Tuechler, Heinrich [Ludwig Boltzmann Institute for Hematology, Hanusch Hospital, Heinrich Collin-Strasse 30, A-1140 Vienna (Austria); Resnick, Donald [Department of Radiology, VA Medical Center, UCSD, 3350 La Jolla Village Dr, San Diego, CA 92161 (United States)

2006-06-15

Objective: To clarify the role of MR-imaging in the diagnosis of anterior ankle impingement syndromes. Materials and methods: We prospectively examined 51 consecutive patients with chronic ankle pain by MR-imaging. Arthroscopy was performed in 29 patients who previously underwent non-enhanced MR-imaging; in 11 patients, indirect MR-arthrography additionally was performed. MR-examinations were correlated with clinical findings; MR and arthroscopy scores were statistically compared, agreement was measured. Results: Arthroscopy demonstrated granulation tissue in the lateral gutter (38%) and anterior recess (31%), lesions of the anterior tibiofibular (31%) and the anterior talofibular ligament (21%) as well as intraarticular bodies (10%). Stenosing tenosynovitis and a ganglionic cyst were revealed as extraarticular causes for chronic ankle pain by MR-examination (17%). Agreement of MR-imaging and arthroscopy was fair for the anterior talofibular ligament and the anterior joint cavity (kappa 0.40). Major discrepancy was found for non-enhanced MR scans (kappa 0.49) when compared with indirect MR-arthrography (kappa 0.03) in the anterior cavity. The sensitivity for lesions of the anterior talofibular and calcaneofibular ligament and the anterior cavity (0.91-0.87) detected by MR-imaging was superior in comparison to lesions of the anterior tibiofibular ligament and anteromedial cavity (0.50-0.24). Conclusion: MR-imaging provides additional information about the mechanics of chronic ankle impingement rather than an accurate diagnosis of this clinical entity. The method is helpful in differentiating extra- from intra-articular causes of ankle impingement. Indirect MR-arthrography has little or no additional value in patients with ankle impingement syndrome.

MR-imaging of anterior tibiotalar impingement syndrome: Agreement, sensitivity and specificity of MR-imaging and indirect MR-arthrography

International Nuclear Information System (INIS)

Haller, Joerg; Bernt, Reinhard; Seeger, Thomas; Weissenbaeck, Alexander; Tuechler, Heinrich; Resnick, Donald

2006-01-01

Objective: To clarify the role of MR-imaging in the diagnosis of anterior ankle impingement syndromes. Materials and methods: We prospectively examined 51 consecutive patients with chronic ankle pain by MR-imaging. Arthroscopy was performed in 29 patients who previously underwent non-enhanced MR-imaging; in 11 patients, indirect MR-arthrography additionally was performed. MR-examinations were correlated with clinical findings; MR and arthroscopy scores were statistically compared, agreement was measured. Results: Arthroscopy demonstrated granulation tissue in the lateral gutter (38%) and anterior recess (31%), lesions of the anterior tibiofibular (31%) and the anterior talofibular ligament (21%) as well as intraarticular bodies (10%). Stenosing tenosynovitis and a ganglionic cyst were revealed as extraarticular causes for chronic ankle pain by MR-examination (17%). Agreement of MR-imaging and arthroscopy was fair for the anterior talofibular ligament and the anterior joint cavity (kappa 0.40). Major discrepancy was found for non-enhanced MR scans (kappa 0.49) when compared with indirect MR-arthrography (kappa 0.03) in the anterior cavity. The sensitivity for lesions of the anterior talofibular and calcaneofibular ligament and the anterior cavity (0.91-0.87) detected by MR-imaging was superior in comparison to lesions of the anterior tibiofibular ligament and anteromedial cavity (0.50-0.24). Conclusion: MR-imaging provides additional information about the mechanics of chronic ankle impingement rather than an accurate diagnosis of this clinical entity. The method is helpful in differentiating extra- from intra-articular causes of ankle impingement. Indirect MR-arthrography has little or no additional value in patients with ankle impingement syndrome

MR-fluid yield surface determination in disc-type MR rotary brakes

International Nuclear Information System (INIS)

Farjoud, Alireza; Vahdati, Nader; Fah, Yap Fook

2008-01-01

Magneto-rheological (MR) fluids are currently attracting a great deal of attention because of their unique rheological behavior. Many devices have been designed using MR fluids, and of potential interest here are disc-type MR rotary brakes. The plug flow region in MR devices is defined as the region where the fluid is not flowing. The plug flow region plays an important role in design and analysis of MR devices. In MR dampers, the damping coefficient is a function of the plug thickness. In MR valves, the plug thickness is used to control the flow rate through, and the pressure drop across, the MR valve. A MR clutch is performing at the highest efficiency when the entire MR gap is the plug region. For an MR rotary brake, the highest restraining torque is obtained when the entire gap is the plug region as far as there are no wall slip effects. In this paper, using the Bercovier and Engelman constitutive model, the MR fluid flow in disc-type MR brakes is modeled to determine the plug flow region. The resulting system of equations is solved numerically. It is shown that the existence of a plug flow region in the brake will affect the control torque ratio. Better estimation of the plug flow region results in better estimation of the viscous torque

Synthesis and characterization of magneto-rheological (MR fluids for MR brake application

Directory of Open Access Journals (Sweden)

Bhau K. Kumbhar

2015-09-01

Full Text Available Magneto rheological (MR fluid technology has been proven for many industrial applications like shock absorbers, actuators, etc. MR fluid is a smart material whose rheological characteristics change rapidly and can be controlled easily in presence of an applied magnetic field. MR brake is a device to transmit torque by the shear stress of MR fluid. However, MR fluids exhibit yield stress of 50–90 kPa. In this research, an effort has been made to synthesize MR fluid sample/s which will typically meet the requirements of MR brake applications. In this study, various electrolytic and carbonyl iron powder based MR fluids have been synthesized by mixing grease as a stabilizer, oleic acid as an antifriction additive and gaur gum powder as a surface coating to reduce agglomeration of the MR fluid. MR fluid samples based on sunflower oil, which is bio-degradable, environmentally friendly and abundantly available have also been synthesized. These MR fluid samples are characterized for determination of magnetic, morphological and rheological properties. This study helps identify most suitable localized MR fluid meant for MR brake application.

Anatomic variants of the pancreatic duct and their clinical relevance: an MR-guided study in the general population

International Nuclear Information System (INIS)

Buelow, Robin; Thiel, Robert; Thamm, Patrick; Messner, Philip; Hosten, Norbert; Kuehn, Jens-Peter; Simon, Peter; Lerch, Markus M.; Mayerle, Julia; Voelzke, Henry

2014-01-01

To investigate the frequency of pancreatic duct (PD) variants and their effect on pancreatic exocrine function in a population-based study using non-invasive secretin-stimulated magnetic resonance cholangiopancreatography (sMRCP). Nine hundred and ninety-five volunteers, 457 women and 538 men, aged 51.9 ± 13.4 years, underwent navigator-triggered, T2-weighted, 3D turbo spin echo MRCP on a 1.5 T system after 1 unit/kg secretin administration. Two readers evaluated images for PD variants. Pancreatic exocrine function and morphological signs of chronic pancreatitis such as abnormalities of the main PD, side branch dilatation, and pancreatic cysts were evaluated and related to PD variants using a Kruskal-Wallis test and post hoc analysis. Of all sMRCP, 93.2 % were of diagnostic quality. Interobserver reliability for detection of PD variants was found to be kappa 0.752 (95 %CI, 0.733 - 0.771). Normal PD variants were observed in 90.4 % (n = 838/927). Variants of pancreas divisum was identified in 9.6 % (n = 89/927). Abnormalities of the main PD, side branch dilatation, and pancreatic cysts were observed in 2.4 %, 16.6 %, and 27.7 %, respectively, and were not significantly different between pancreas divisum and non-divisum group (P = 0.122; P = 0.152; P = 0.741). There was no association between PD variants and pancreatic exocrine function (P = 0.367). PD variants including pancreas divisum are not associated with morphological signs of chronic pancreatitis or restriction of pancreatic exocrine function. (orig.)

Anatomic variants of the pancreatic duct and their clinical relevance: an MR-guided study in the general population

Energy Technology Data Exchange (ETDEWEB)

Buelow, Robin; Thiel, Robert; Thamm, Patrick; Messner, Philip; Hosten, Norbert; Kuehn, Jens-Peter [University Medicine, Ernst Moritz Arndt University Greifswald, Department of Radiology and Neuroradiology, Greifswald (Germany); Simon, Peter; Lerch, Markus M.; Mayerle, Julia [University Medicine, Ernst Moritz Arndt University Greifswald, Division of Gastroenterology and Department of Medicine A, Greifswald (Germany); Voelzke, Henry [University Medicine, Ernst Moritz Arndt University Greifswald, Institute for Community Medicine, Greifswald (Germany)

2014-12-15

To investigate the frequency of pancreatic duct (PD) variants and their effect on pancreatic exocrine function in a population-based study using non-invasive secretin-stimulated magnetic resonance cholangiopancreatography (sMRCP). Nine hundred and ninety-five volunteers, 457 women and 538 men, aged 51.9 ± 13.4 years, underwent navigator-triggered, T2-weighted, 3D turbo spin echo MRCP on a 1.5 T system after 1 unit/kg secretin administration. Two readers evaluated images for PD variants. Pancreatic exocrine function and morphological signs of chronic pancreatitis such as abnormalities of the main PD, side branch dilatation, and pancreatic cysts were evaluated and related to PD variants using a Kruskal-Wallis test and post hoc analysis. Of all sMRCP, 93.2 % were of diagnostic quality. Interobserver reliability for detection of PD variants was found to be kappa 0.752 (95 %CI, 0.733 - 0.771). Normal PD variants were observed in 90.4 % (n = 838/927). Variants of pancreas divisum was identified in 9.6 % (n = 89/927). Abnormalities of the main PD, side branch dilatation, and pancreatic cysts were observed in 2.4 %, 16.6 %, and 27.7 %, respectively, and were not significantly different between pancreas divisum and non-divisum group (P = 0.122; P = 0.152; P = 0.741). There was no association between PD variants and pancreatic exocrine function (P = 0.367). PD variants including pancreas divisum are not associated with morphological signs of chronic pancreatitis or restriction of pancreatic exocrine function. (orig.)

Value of new MR techniques in MR-PET; Stellenwert neuer MR-Techniken in der MR-PET

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Attenberger, U.I.; Schoenberg, S.O. [Universitaetsmedizin Mannheim, Medizinische Fakultaet Mannheim der Universitaet Heidelberg, Institut fuer klinische Radiologie und Nuklearmedizin, Mannheim (Germany); Quick, H.H. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Institut fuer Medizinische Physik, Erlangen (Germany); Guimaraes, A. [Massachusetts General Hospital, Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown (United States); Catalano, O. [University of Naples Federico II, Naples (Italy); Morelli, J.N. [The Johns Hopkins Hospital, The Russell H. Morgan Department of Radiology and Radiological Science, Baltimore (United States)

2013-12-15

The unparalleled soft tissue contrast of magnetic resonance imaging (MRI) and the functional information obtainable with 18-F fluorodeoxyglucose positron emission tomography (FDG-PET) render MR-PET well-suited for oncological and psychiatric imaging. The lack of ionizing radiation with MRI also makes MR-PET a promising modality for oncology patients requiring frequent follow-up and pediatric patients. Lessons learned with PET computed tomography (CT) over the last few years do not directly translate to MR-PET. For example, in PET-CT the Hounsfield units derived from CT are used for attenuation correction (AC). As 511 keV photons emitted in PET examinations are attenuated by the patient's body CT data are converted directly to linear attenuation coefficients (LAC); however, proton density measured by MRI is not directly related to the radiodensity or LACs of biological tissue. Thus, direct conversion to LAC data is not possible making AC more challenging in simultaneous MRI-PET scanning. In addition to these constraints simultaneous MRI-PET acquisitions also improve on some solutions to well-known challenges of hybrid imaging techniques, such as limitations in motion correction. This article reports on initial clinical experiences with simultaneously acquired MRI-PET data, focusing on the potential benefits and limitations of MRI with respect to motion correction as well as metal and attenuation correction artefacts. (orig.) [German] Die klinische Implementierung der neuen Hybridtechnologie MR-Positronenemissionstomographie (MR-PET) bietet durch die Kombination aus hochaufloesender Morphologie, Funktion und Metabolismus bisher ungeahnte diagnostische Moeglichkeiten, die nicht nur fuer die Diagnose und die Verlaufskontrolle onkologischer und psychiatrischer Erkrankungen von hoher Bedeutung sind. Verglichen mit der PET-CT wird dies mit reduzierter Strahlenbelastung fuer den Patienten moeglich, was wiederum insbesondere fuer Patienten in der Tumornachsorge, die

MRI diagnosis and preoperative evaluation for hepatic hilar tumor

International Nuclear Information System (INIS)

Liu Yulin; Kong xiangquan; Xu Haibo; Xiao Xuehong; Liu Dingxi; Peng Zhenjun

2004-01-01

Objective: To investigate the value of the all-in-one MR scanning in the diagnosis and preoperative evaluation of hepatic hilar tumor. Methods: Forty-two cases of hepatic hilar tumors were examined with a 1.5 T superconductive MR system, including hepatocellular carcinoma (HCC, n=12), hilar cholangiocarcinoma (HC, n=22), and hilar metastasis (n=8). Besides the precontrast MRI and MRCP, all cases underwent consecutive dynamic contrast-enhanced MR scanning. The whole liver dynamic contrast-enhanced MR was performed with the first bolus injection of Gd-DTPA (10 ml), and 15 minutes later, 3D DCE MRA was performed with additional injection of Gd-DTPA (15-20 ml) (0.15-0.20 mmol/kg). The contrast time-signal curve of liver and tumor was drawn, and arterial and portal venous phase images were reconstructed with MIP. MR appearances were compared with surgical findings and pathology. Results: Consecutive DCE scanning was successfully performed in all cases. The contrast time-signal curve of HCC showed type I and II (10/12, 83.3%), and the curve of HC showed type III and IV (21/22, 95.4%), whereas the curve of metastasis was various. The difference of tumor peak transit time (PT) between HCC group and HC group was significant (P<0.05). The vascular invasion in HCC group appeared as arterial-portal vein fistula (2/12, 16.7%), portal vein infiltration (3/24, 12.5%), and occlusion by tumor thrombosis (4/24, 16.7%). However, the vascular invasion in HC group showed spiral artery (5/22, 22.7%), portal vein infiltration (5/44, 11.4%), portal vein central narrowing (8/44, 18.2%) and occlusion (11/44, 25.0%). All metastasis had no vascular invasion expect one gall bladder carcinoma with right portal vein infiltration. The accuracy of preoperative evaluation with MRI in HCC group and HC group was 83.3% (10/12) and 86.4% (19/22), respectively. The accuracy of preoperative evaluation in all hilar tumors was 78.6% (33/42). Conclusion: Consecutive DCE was a safe and useful technique in MR

MR/PET quantification tools: Registration, segmentation, classification, and MR-based attenuation correction

Science.gov (United States)

Fei, Baowei; Yang, Xiaofeng; Nye, Jonathon A.; Aarsvold, John N.; Raghunath, Nivedita; Cervo, Morgan; Stark, Rebecca; Meltzer, Carolyn C.; Votaw, John R.

2012-01-01

Purpose: Combined MR/PET is a relatively new, hybrid imaging modality. A human MR/PET prototype system consisting of a Siemens 3T Trio MR and brain PET insert was installed and tested at our institution. Its present design does not offer measured attenuation correction (AC) using traditional transmission imaging. This study is the development of quantification tools including MR-based AC for quantification in combined MR/PET for brain imaging. Methods: The developed quantification tools include image registration, segmentation, classification, and MR-based AC. These components were integrated into a single scheme for processing MR/PET data. The segmentation method is multiscale and based on the Radon transform of brain MR images. It was developed to segment the skull on T1-weighted MR images. A modified fuzzy C-means classification scheme was developed to classify brain tissue into gray matter, white matter, and cerebrospinal fluid. Classified tissue is assigned an attenuation coefficient so that AC factors can be generated. PET emission data are then reconstructed using a three-dimensional ordered sets expectation maximization method with the MR-based AC map. Ten subjects had separate MR and PET scans. The PET with [11C]PIB was acquired using a high-resolution research tomography (HRRT) PET. MR-based AC was compared with transmission (TX)-based AC on the HRRT. Seventeen volumes of interest were drawn manually on each subject image to compare the PET activities between the MR-based and TX-based AC methods. Results: For skull segmentation, the overlap ratio between our segmented results and the ground truth is 85.2 ± 2.6%. Attenuation correction results from the ten subjects show that the difference between the MR and TX-based methods was <6.5%. Conclusions: MR-based AC compared favorably with conventional transmission-based AC. Quantitative tools including registration, segmentation, classification, and MR-based AC have been developed for use in combined MR

MR/PET quantification tools: Registration, segmentation, classification, and MR-based attenuation correction

Energy Technology Data Exchange (ETDEWEB)

Fei, Baowei, E-mail: bfei@emory.edu [Department of Radiology and Imaging Sciences, Emory University School of Medicine, 1841 Clifton Road Northeast, Atlanta, Georgia 30329 (United States); Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia 30322 (United States); Department of Mathematics and Computer Sciences, Emory University, Atlanta, Georgia 30322 (United States); Yang, Xiaofeng; Nye, Jonathon A.; Raghunath, Nivedita; Votaw, John R. [Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia 30329 (United States); Aarsvold, John N. [Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia 30329 (United States); Nuclear Medicine Service, Atlanta Veterans Affairs Medical Center, Atlanta, Georgia 30033 (United States); Cervo, Morgan; Stark, Rebecca [The Medical Physics Graduate Program in the George W. Woodruff School, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Meltzer, Carolyn C. [Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia 30329 (United States); Department of Neurology and Department of Psychiatry and Behavior Sciences, Emory University School of Medicine, Atlanta, Georgia 30322 (United States)

2012-10-15

Purpose: Combined MR/PET is a relatively new, hybrid imaging modality. A human MR/PET prototype system consisting of a Siemens 3T Trio MR and brain PET insert was installed and tested at our institution. Its present design does not offer measured attenuation correction (AC) using traditional transmission imaging. This study is the development of quantification tools including MR-based AC for quantification in combined MR/PET for brain imaging. Methods: The developed quantification tools include image registration, segmentation, classification, and MR-based AC. These components were integrated into a single scheme for processing MR/PET data. The segmentation method is multiscale and based on the Radon transform of brain MR images. It was developed to segment the skull on T1-weighted MR images. A modified fuzzy C-means classification scheme was developed to classify brain tissue into gray matter, white matter, and cerebrospinal fluid. Classified tissue is assigned an attenuation coefficient so that AC factors can be generated. PET emission data are then reconstructed using a three-dimensional ordered sets expectation maximization method with the MR-based AC map. Ten subjects had separate MR and PET scans. The PET with [{sup 11}C]PIB was acquired using a high-resolution research tomography (HRRT) PET. MR-based AC was compared with transmission (TX)-based AC on the HRRT. Seventeen volumes of interest were drawn manually on each subject image to compare the PET activities between the MR-based and TX-based AC methods. Results: For skull segmentation, the overlap ratio between our segmented results and the ground truth is 85.2 ± 2.6%. Attenuation correction results from the ten subjects show that the difference between the MR and TX-based methods was <6.5%. Conclusions: MR-based AC compared favorably with conventional transmission-based AC. Quantitative tools including registration, segmentation, classification, and MR-based AC have been developed for use in combined MR/PET.

MR/PET quantification tools: Registration, segmentation, classification, and MR-based attenuation correction

International Nuclear Information System (INIS)

Fei, Baowei; Yang, Xiaofeng; Nye, Jonathon A.; Raghunath, Nivedita; Votaw, John R.; Aarsvold, John N.; Cervo, Morgan; Stark, Rebecca; Meltzer, Carolyn C.

2012-01-01

Purpose: Combined MR/PET is a relatively new, hybrid imaging modality. A human MR/PET prototype system consisting of a Siemens 3T Trio MR and brain PET insert was installed and tested at our institution. Its present design does not offer measured attenuation correction (AC) using traditional transmission imaging. This study is the development of quantification tools including MR-based AC for quantification in combined MR/PET for brain imaging. Methods: The developed quantification tools include image registration, segmentation, classification, and MR-based AC. These components were integrated into a single scheme for processing MR/PET data. The segmentation method is multiscale and based on the Radon transform of brain MR images. It was developed to segment the skull on T1-weighted MR images. A modified fuzzy C-means classification scheme was developed to classify brain tissue into gray matter, white matter, and cerebrospinal fluid. Classified tissue is assigned an attenuation coefficient so that AC factors can be generated. PET emission data are then reconstructed using a three-dimensional ordered sets expectation maximization method with the MR-based AC map. Ten subjects had separate MR and PET scans. The PET with ["1"1C]PIB was acquired using a high-resolution research tomography (HRRT) PET. MR-based AC was compared with transmission (TX)-based AC on the HRRT. Seventeen volumes of interest were drawn manually on each subject image to compare the PET activities between the MR-based and TX-based AC methods. Results: For skull segmentation, the overlap ratio between our segmented results and the ground truth is 85.2 ± 2.6%. Attenuation correction results from the ten subjects show that the difference between the MR and TX-based methods was <6.5%. Conclusions: MR-based AC compared favorably with conventional transmission-based AC. Quantitative tools including registration, segmentation, classification, and MR-based AC have been developed for use in combined MR/PET.

MR-based source localization for MR-guided HDR brachytherapy

Science.gov (United States)

Beld, E.; Moerland, M. A.; Zijlstra, F.; Viergever, M. A.; Lagendijk, J. J. W.; Seevinck, P. R.

2018-04-01

For the purpose of MR-guided high-dose-rate (HDR) brachytherapy, a method for real-time localization of an HDR brachytherapy source was developed, which requires high spatial and temporal resolutions. MR-based localization of an HDR source serves two main aims. First, it enables real-time treatment verification by determination of the HDR source positions during treatment. Second, when using a dummy source, MR-based source localization provides an automatic detection of the source dwell positions after catheter insertion, allowing elimination of the catheter reconstruction procedure. Localization of the HDR source was conducted by simulation of the MR artifacts, followed by a phase correlation localization algorithm applied to the MR images and the simulated images, to determine the position of the HDR source in the MR images. To increase the temporal resolution of the MR acquisition, the spatial resolution was decreased, and a subpixel localization operation was introduced. Furthermore, parallel imaging (sensitivity encoding) was applied to further decrease the MR scan time. The localization method was validated by a comparison with CT, and the accuracy and precision were investigated. The results demonstrated that the described method could be used to determine the HDR source position with a high accuracy (0.4–0.6 mm) and a high precision (⩽0.1 mm), at high temporal resolutions (0.15–1.2 s per slice). This would enable real-time treatment verification as well as an automatic detection of the source dwell positions.

Generation of structural MR images from amyloid PET: Application to MR-less quantification.

Science.gov (United States)

Choi, Hongyoon; Lee, Dong Soo

2017-12-07

Structural magnetic resonance (MR) images concomitantly acquired with PET images can provide crucial anatomical information for precise quantitative analysis. However, in the clinical setting, not all the subjects have corresponding MR. Here, we developed a model to generate structural MR images from amyloid PET using deep generative networks. We applied our model to quantification of cortical amyloid load without structural MR. Methods: We used florbetapir PET and structural MR data of Alzheimer's Disease Neuroimaging Initiative database. The generative network was trained to generate realistic structural MR images from florbetapir PET images. After the training, the model was applied to the quantification of cortical amyloid load. PET images were spatially normalized to the template space using the generated MR and then standardized uptake value ratio (SUVR) of the target regions was measured by predefined regions-of-interests. A real MR-based quantification was used as the gold standard to measure the accuracy of our approach. Other MR-less methods, a normal PET template-based, multi-atlas PET template-based and PET segmentation-based normalization/quantification methods, were also tested. We compared performance of quantification methods using generated MR with that of MR-based and MR-less quantification methods. Results: Generated MR images from florbetapir PET showed visually similar signal patterns to the real MR. The structural similarity index between real and generated MR was 0.91 ± 0.04. Mean absolute error of SUVR of cortical composite regions estimated by the generated MR-based method was 0.04±0.03, which was significantly smaller than other MR-less methods (0.29±0.12 for the normal PET-template, 0.12±0.07 for multiatlas PET-template and 0.08±0.06 for PET segmentation-based methods). Bland-Altman plots revealed that the generated MR-based SUVR quantification was the closest to the SUVR values estimated by the real MR-based method. Conclusion

MR tractography

International Nuclear Information System (INIS)

Kinosada, Yasutomi; Okuda, Yasuyuki; Ono, Mototsugu

1993-01-01

We developed a new noninvasive technique to visualize the anatomical structure of the nerve fiber system in vivo, and named this technique magnetic resonance (MR) tractography and the acquired image an MR tractogram. MR tractography has two steps. One is to obtain diffusion-weighted images sensitized along axes appropriate for depicting the intended nerve fibers with anisotropic water diffusion MR imaging. The other is to extract the anatomical structure of the nerve fiber system from a series of diffusion-weighted images by the maximum intensity projection method. To examine the clinical usefulness of the proposed technique, many contiguous, thin (3 mm) coronal two-dimensional sections of the brain were acquired sequentially in normal volunteers and selected patients with paralyses, on a 1.5 Tesla MR system (Signa, GE) with an ECG-gated Stejskal-Tanner pulse sequence. The structure of the nerve fiber system of normal volunteers was almost the same as the anatomy. The tractograms of patients with paralyses clearly showed the degeneration of nerve fibers and were correlated with clinical symptoms. MR tractography showed great promise for the study of neuroanatomy and neuroradiology. (author)

MR-guided biopsies

International Nuclear Information System (INIS)

Gehl, H.B.; Frahm, C.

1998-01-01

Biopsies were the first 'intervention' under MR guidance. After initial difficulties concerning ferromagnetic biopsy instruments and the design of MR scanners, the latest technological improvements rendered MR guidance for biopsies more feasible. In this article we illustrate present-day clinical experience in the field of abdominal, breast and bone biopsy. Important aspects regarding the different designs of 'interventional' MR scanners and the visualization of instruments for biopsy are discussed. (orig.) [de

Correction of distortion of MR pictures for MR-guided robotic sterotactic procedures

International Nuclear Information System (INIS)

Jonckheere, E.A.; Kwoh, Y.S.

1988-01-01

Ever since magnetic resonance (MR) invaded the medical imaging field, it has played an increasingly important role and is even currently being considered for stereotactic guidance of probes in the brain. While MR pictures indeed convey more clinical information than CT, the geometry of MR pictures is, unfortunately, not as accurate as the geometry of CT pictures. In other words, if a square grid phantom is scanned, then the CT picture will show a square grid, while the MR picture will rather reveal a distorted grid. This distortion is primarily due to small variations in the static magnetic field. This small distortion does not impede radiological diagnosis; however, it is a source of concern if one contemplates utilizing the MR pictures for accurate stereotactic positioning of a probe at a very precise point in the brain. Another area of application where the distortion of the MR picture should be compensated for is the superposition of CT and MR pictures so that both informations could be used for diagnosis or stereotactic purposes. This paper essentially addresses the nonlinear distortion of MR pictures and how it could be compensated for through software manipulation of the MR picture

MR Imaging-Guided Attenuation Correction of PET Data in PET/MR Imaging.

Science.gov (United States)

Izquierdo-Garcia, David; Catana, Ciprian

2016-04-01

Attenuation correction (AC) is one of the most important challenges in the recently introduced combined PET/magnetic resonance (MR) scanners. PET/MR AC (MR-AC) approaches aim to develop methods that allow accurate estimation of the linear attenuation coefficients of the tissues and other components located in the PET field of view. MR-AC methods can be divided into 3 categories: segmentation, atlas, and PET based. This review provides a comprehensive list of the state-of-the-art MR-AC approaches and their pros and cons. The main sources of artifacts are presented. Finally, this review discusses the current status of MR-AC approaches for clinical applications. Copyright © 2016 Elsevier Inc. All rights reserved.

Ankle ligamints : comparison of MR arthrography with conventional MR imaging in amputated feet

International Nuclear Information System (INIS)

Yoo, Jae Sung; Lee, Sang Yong; Lee, Jeong Min; Han, Young Min; Chung, Kyung Ho; Kim, CHong Soo

2001-01-01

To compare magnetic resonance (MR) arthrography with conventional MR imaging in the evaluation of ankle ligaments. Eight freshly amputated human feet underwent conventional MR imaging and MR arthrography. For the former, 1.5-T magnets in the axial, coronal and sagittal planes were used, and T1-weighted sequences were obtained. Following the injection of 6-10 ml of diluted contrast media (Gd-DTPA 1:250), T1-weighted images were obtained in the same positions as conventional MR images. Paired conventional MR imaging and MR arthrography of each ankle ligament were rated on a five-point scale, and to reflect inter-group differences a Wilcoxon singed-rank test was used to compare the different measurements (p<0.05). In two ankles, MR images of the ligaments were correlated with ankle dissection. Anterior and posterior talofibular ligaments were more clearly revealed by MR arthrography than by conventional MR imaging, while calcaneofibular ligaments showed no difference between these two modalities. With regard to deltoid ligaments, visualization of the anterior and posterior tibiotalar ligament was much improved when contrast material was used to outline the ligament's articular aspect. Visualization of the posterior inferior tibiofibular ligament and inferior transverse ligament were also improved when the use of contrast material provided delineation of the articular side of the ligaments and separated them from adjacent bone. In addition, MR arthography was very useful for indentification of the posterior intermalleolar ligament, though its use did not enhance visualization of the calcaneofibular, tibiocalcaneal, spring or tibiospring ligaments. MR arthrography accurately revealed the anatomic details of ankle ligaments, and may therefore be more useful than conventional Mr imaging for evaluation of these structures

Quantification of pancreatic exocrine function with secretin-enhanced magnetic resonance cholangiopancreatography: normal values and short-term effects of pancreatic duct drainage procedures in chronic pancreatitis. Initial results

International Nuclear Information System (INIS)

Bali, M.A.; Sztantics, A.; Metens, T.; Matos, C.; Arvanitakis, M.; Delhaye, M.; Deviere, J.

2005-01-01

The aim of this study was to quantify pancreatic exocrine function in normal subjects and in patients with chronic pancreatitis (CP) before and after pancreatic duct drainage procedures (PDDP) with dynamic secretin-enhanced magnetic resonance (MR) cholangiopancreatography (S-MRCP). Pancreatic exocrine secretions [quantified by pancreatic flow output (PFO) and total excreted volume (TEV)] were quantified twice in ten healthy volunteers and before and after treatment in 20 CP patients (18 classified as severe, one as moderate, and one as mild according to the Cambridge classification). PFO and TEV were derived from a linear regression between MR-calculated volumes and time. In all subjects, pancreatic exocrine fluid volume initially increased linearly with time during secretin stimulation. In controls, the mean PFO and TEV were 6.8 ml/min and 97 ml; intra-individual deviations were 0.8 ml/min and 16 ml. In 10/20 patients with impaired exocrine secretions before treatment, a significant increase of PFO and TEV was observed after treatment (P<0.05); 3/20 patients presented post-procedural acute pancreatitis and a reduced PFO. The S-MRCP quantification method used in the present study is reproducible and provides normal values for PFO and TEV in the range of those obtained from previous published intubation studies. The initial results in CP patients have demonstrated non-invasively a significant short-term improvement of PFO and TEV after PDDP. (orig.)

Do carotid MR surface coils affect PET quantification in PET/MR imaging?

International Nuclear Information System (INIS)

Willemink, Martin J; Eldib, Mootaz; Leiner, Tim; Fayad, Zahi A; Mani, Venkatesh

2015-01-01

To evaluate the effect of surface coils for carotid MR imaging on PET quantification in a clinical simultaneous whole-body PET/MR scanner. A cylindrical phantom was filled with a homogeneous 2L water-FDG mixture at a starting dose of 301.2MBq. Clinical PET/MR and PET/CT systems were used to acquire PET-data without a coil (reference standard) and with two carotid MRI coils (Siemens Special Purpose 8-Channel and Machnet 4-Channel Phased Array). PET-signal attenuation was evaluated with Osirix using 51 (PET/MR) and 37 (PET/CT) circular ROIs. Mean and maximum standardized uptake values (SUVs) were quantified for each ROI. Furthermore, SUVs of PET/MR and PET/CT were compared. For validation, a patient was scanned with an injected dose of 407.7MBq on both a PET/CT and a PET/MR system without a coil and with both coils. PET/MR underestimations were -2.2% (Siemens) and -7.8% (Machnet) for SUVmean, and -1.2% (Siemens) and -3.3% (Machnet) for SUVmax, respectively. For PET/CT, underestimations were -1.3% (Siemens) and -1.4% (Machnet) for SUVmean and -0.5% (both Siemens and Machnet) for SUVmax, respectively using no coil data as reference. Except for PET/CT SUVmax values all differences were significant. SUVs differed significantly between PET/MR and PET/CT with SUVmean values of 0.51-0.55 for PET/MR and 0.68-0.69 for PET/CT, respectively. The patient examination showed that median SUVmean values measured in the carotid arteries decreased from 0.97 without a coil to 0.96 (Siemens) and 0.88 (Machnet). Carotid surface coils do affect attenuation correction in both PET/MR and PET/CT imaging. Furthermore, SUVs differed significantly between PET/MR and PET/CT.

Mr imaging and mr spectroscopy of brain metastases by mr perfusion

International Nuclear Information System (INIS)

Weber, Marc-Andre; Lichy, M.P.; Thilmann, C.; Guenther, M.; Bachert, P.; Delorme, S.; Schad, L.R.; Debus, J.; Schlemmer, H.P.; Maudsley, A.A.

2003-01-01

In follow-up examinations of irradiated brain metastases conventional contrast-enhanced morphological MR imaging is often unable to distinguish between transient radiation effects, radionecrosis, and tumor recurrence. To evaluate changes of relative cerebral blood flow (rCBF) in irradiated brain metastases arterial spin-labeling techniques (ASL) were applied and compared to the outcome of 1 H MR spectroscopy and spectroscopic imaging ( 1 H MRS, SI). Patients and methods In 2 patients follow-up examinations of irradiated brain metastases were performed on a 1.5-T tomograph (average single dose: 20 Gy/80% isodose). Relative CBF values of gray matter (GM), white matter (WM), and metastases (Met) were measured by means of the ASL techniques ITS-FAIR and Q2TIPS. 1 H MRS was performed with PRESS 1500/135. In both patients with initially hyperperfused metastases (Met/GM >1) the reduction of rCBF after stereotactic radiosurgery indicated response to treatment - even if the contrast-enhancing region increased - while increasing rCBF values indicated tumor progression. The findings were confirmed by 1 H MRS, SI and subsequent follow-up. The ASL techniques ITS-FAIR and Q2TIPS are able to monitor changes of rCBF in irradiated brain metastases. The two cases imply a possible role for ASL-MR perfusion imaging and 1 H MR spectroscopy in differentiating radiation effects from tumor progression. (orig.) [de

Deep Learning MR Imaging-based Attenuation Correction for PET/MR Imaging.

Science.gov (United States)

Liu, Fang; Jang, Hyungseok; Kijowski, Richard; Bradshaw, Tyler; McMillan, Alan B

2018-02-01

Purpose To develop and evaluate the feasibility of deep learning approaches for magnetic resonance (MR) imaging-based attenuation correction (AC) (termed deep MRAC) in brain positron emission tomography (PET)/MR imaging. Materials and Methods A PET/MR imaging AC pipeline was built by using a deep learning approach to generate pseudo computed tomographic (CT) scans from MR images. A deep convolutional auto-encoder network was trained to identify air, bone, and soft tissue in volumetric head MR images coregistered to CT data for training. A set of 30 retrospective three-dimensional T1-weighted head images was used to train the model, which was then evaluated in 10 patients by comparing the generated pseudo CT scan to an acquired CT scan. A prospective study was carried out for utilizing simultaneous PET/MR imaging for five subjects by using the proposed approach. Analysis of covariance and paired-sample t tests were used for statistical analysis to compare PET reconstruction error with deep MRAC and two existing MR imaging-based AC approaches with CT-based AC. Results Deep MRAC provides an accurate pseudo CT scan with a mean Dice coefficient of 0.971 ± 0.005 for air, 0.936 ± 0.011 for soft tissue, and 0.803 ± 0.021 for bone. Furthermore, deep MRAC provides good PET results, with average errors of less than 1% in most brain regions. Significantly lower PET reconstruction errors were realized with deep MRAC (-0.7% ± 1.1) compared with Dixon-based soft-tissue and air segmentation (-5.8% ± 3.1) and anatomic CT-based template registration (-4.8% ± 2.2). Conclusion The authors developed an automated approach that allows generation of discrete-valued pseudo CT scans (soft tissue, bone, and air) from a single high-spatial-resolution diagnostic-quality three-dimensional MR image and evaluated it in brain PET/MR imaging. This deep learning approach for MR imaging-based AC provided reduced PET reconstruction error relative to a CT-based standard within the brain compared

MR imaging of prostate cancer; MR-Tomographie des Prostatakarzinoms

Energy Technology Data Exchange (ETDEWEB)

Heuck, A.; Scheidler, J.; Sommer, B.; Graser, A. [Radiologisches Zentrum Muenchen-Pasing (Germany); Mueller-Lisse, U.G. [Institut fuer Klinische Radiologie, Universitaet Muenchen (Germany); Massmann, J. [Gemeinschaftspraxis Pathologie, Muenchen (Germany)

2003-06-01

Accurate diagnosis and staging of prostate cancer (PC) is developing into an important health care issue in light of the high incidence of PC and the improvements in stage-adapted therapy. The purpose of this paper is to provide an overview on the current role of MR imaging and MR spectroscopy in the diagnosis and staging of PC.Material and methods Pertinent literature was searched and evaluated to collect information on current clinical indications, study techniques, diagnostic value, and limitations of magnetic resonance imaging and spectroscopy. Major indications for MR imaging of patients with supected PC are to define tumor location before biopsy when clinical or TRUS findings are inconclusive, and to provide accurate staging of histologically proven PC to ascertain effective therapy. Current MR imaging techniques for the evaluation of PC include multiplanar high-resolution T2-weighted FSE and T1-weighted SE sequences using combined endorectal and phased-array coils. Using these techniques, the reported accuracy of MR imaging for the diagnosis of extracapsular tumor extension ranges between 82 and 88% with sensitivities between 80 and 95%, and specificities between 82 and 93%. Typical MR findings of PC in different stages of disease, as well as diagnostic problems, such as chronic prostatitis, biopsy-related hemorrhage and therapy-related changes of prostatic tissue are discussed. In addition, the current perspectives and limitations of MR spectroscopy in PC are summarized. Current MR imaging techniques provide important diagnostic information in the pretherapeutic workup of PC including a high staging accuracy, and is superior to TRUS. (orig.) [German] Der Diagnostik des Prostatakarzinoms kommt wegen seiner hohen Inzidenz und den verbesserten stadienadaptierten Therapiemoeglichkeiten eine grosse Bedeutung zu. Dabei spielen bildgebende Verfahren bei den klinisch oft unzureichend diagnostizierbaren Faellen eine wesentliche Rolle fuer die praetherapeutische

Interventional MR: vascular applications.

Science.gov (United States)

Smits, H F; Bos, C; van der Weide, R; Bakker, C J

1999-01-01

Three strategies for visualisation of MR-dedicated guidewires and catheters have been proposed, namely active tracking, the technique of locally induced field inhomogeneity and passive susceptibility-based tracking. In this article the pros and cons of these techniques are discussed, including the development of MR-dedicated guidewires and catheters, scan techniques, post-processing tools, and display facilities for MR tracking. Finally, some of the results obtained with MR tracking are discussed.

MR anatomy of the joints: an MR-cadaveric correlative study: part I. wrist

Energy Technology Data Exchange (ETDEWEB)

Kang, Heung Sik [Seoul National University College of Medicine, Seoul (Korea, Republic of); Donald Resnick [University of California, San Diego (United States)

1991-07-15

To acquire the anatomic information necessary for correct interpretation of MR images of the wrist, transverse, coronal, and sagittal MR images of 3 fresh cadaveric wrists were obtained and, subsequently, sectioned along the MR imaging planes. For the precise correlation of anatomic features depicted with MR and with specimen section, cadaveric wrists were fixed in a rectangular cardboard box using paraffin and frozen after MR imaging. High contrast and spatial resolution enabled delineation of small structures including tendons, nerves, vessels, and ligaments, as well as osseous structures. Transverse images provided the best delineation of the carpal tunnel, tendons, nerves, and vessels. Coronal images permitted optimal visualization of triangular fibrocartilage and lunotriquetral and scapholunate ligaments. We conclude that MR imaging accurately and reliably displays the anatomy of the wrist.

PET/MR in oncology: an introduction with focus on MR and future perspectives for hybrid imaging

Science.gov (United States)

Balyasnikova, Svetlana; Löfgren, Johan; de Nijs, Robin; Zamogilnaya, Yanna; Højgaard, Liselotte; Fischer, Barbara M

2012-01-01

After more than 20 years of research, a fully integrated PET/MR scanner was launched in 2010 enabling simultaneous acquisition of PET and MR imaging. Currently, no clinical indication for combined PET/MR has been established, however the expectations are high. In this paper we will discuss some of the challenges inherent in this new technology, but focus on potential applications for simultaneous PET/MR in the field of oncology. Methods and tracers for use with the PET technology will be familiar to most readers of this journal; thus this paper aims to provide a short and basic introduction to a number of different MRI techniques, such as DWI-MR (diffusion weighted imaging MR), DCE-MR (dynamic contrast enhanced MR), MRS (MR spectroscopy) and MR for attenuation correction of PET. All MR techniques presented in this paper have shown promising results in the treatment of patients with solid tumors and could be applied together with PET increasing the amount of information about the tissues of interest. The potential clinical benefit of applying PET/MR in staging, radiotherapy planning and treatment evaluation in oncology, as well as the research perspectives for the use of PET/MR in the development of new tracers and drugs will be discussed. PMID:23145362

Magnetic resonance cholangiopancreatography in the diagnosis of pancreas divisum: a systematic review and meta-analysis.

Science.gov (United States)

Rustagi, Tarun; Njei, Basile

2014-08-01

This study aimed to perform a structured meta-analysis of all eligible studies to assess the overall diagnostic use of magnetic resonance cholangiopancreatography (MRCP) alone or with secretin enhancement (secretin-enhanced MRCP [S-MRCP]) in the detection of pancreas divisum. Two authors independently performed a comprehensive search of PubMed, MEDLINE, and the Cochrane Library from inception to September 2013. Studies were included if they allowed construction of 2 × 2 contingency tables of MRCP and/or S-MRCP compared with criterion standard. DerSimonian-Laird random effect models were used to estimate the pooled sensitivity, specificity, specificity, and quantitative receiver operating characteristics. Of 51 citations, 10 studies with 1474 patients were included. Secretin-enhanced MRCP had a higher overall diagnostic performance than MRCP (S-MRCP: pooled sensitivity, 86% [95% confidence interval (CI), 77%-93%]; specificity, 97% [95% CI, 94%-99%]; and area under the curve, 0.93 ± 0.056 compared with MRCP: sensitivity, 52% [95% CI, 45%-59%]; specificity, 97% [95% CI, 94%-99%]; and area under the curve, 0.76 ± 0.104). Pooled diagnostic odds ratios were 72.19 (95% CI, 5.66-938.8) and 23.39 (95% CI, 7.93-69.02) for S-MRCP and MRCP, respectively. Visual inspection of the funnel plot showed low potential for publication bias. Secretin-enhanced MRCP has a much higher diagnostic accuracy than MRCP and should be preferred for diagnosis of pancreas divisum.

MR angiography, MR imaging and proton MR spectroscopy in-vivo assessment of skeletal muscle ischemia in diabetic rats.

Directory of Open Access Journals (Sweden)

Stefano Delli Pizzi

Full Text Available To prospectively evaluate the feasibility of using magnetic resonance (MR techniques for in-vivo assessing a rat diabetic model of limb ischemia. Unilateral hind limb ischemia was induced by ligation of the iliac-femoral artery in male streptozotocin-treated and non-diabetic control rats. Four weeks after ligation, rats underwent MR Angiography (MRA, T(1-weighted and Short Time Inversion Recovery (STIR sequences and muscle Proton MR Spectroscopy ((1H-MRS on both hind limbs. After MR examinations, immunoblotting and immunofluorescence analysis were performed. MRA showed a signal void due to flow discontinuation distal to the artery ligation. T(1-weighted and STIR images showed, respectively, the presence of tissue swelling (p = 0.018 for non-diabetic; p = 0.027 for diabetic rats and signal hyperintensity in tissue affected by occlusion. Mean total creatine/water for the occluded limb was significantly lower than for the non-occluded limbs in both non-diabetic (5.46×10(-4 vs 1.14×10(-3, p = 0.028 and diabetic rats (1.37×10(-4 vs 1.10×10(-3; p = 0.018. MR Imaging and (1H-MRS changes were more pronounced in diabetic than in non-diabetic occluded limbs (p = 0.032. MR findings were confirmed by using histological findings. Combined MR techniques can be used to demonstrate the presence of structural and metabolic changes produced by iliac-femoral artery occlusion in rat diabetic model of limb ischemia.

MR and MR arthrography to identify degenerative and posttraumatic diseases in the shoulder joint

International Nuclear Information System (INIS)

Lee, Shi-Uk; Lang, Philipp

2000-01-01

MR imaging provides a comprehensive evaluation of a wide spectrum of both intraarticular and extraarticular pathology of the shoulder. MR imaging enables the detection or exclusion of degenerative and posttraumatic diseases of the shoulder with a reasonable accuracy. MR arthrography is useful in the visualization of subtle anatomic details and further improves the differentiation. In this article, findings of MR imaging and MR arthrography of degenerative and posttraumatic shoulder diseases (impingement syndrome, rotator cuff tears, and glenohumeral instability) has been reviewed

MR evaluation of CSF fistulae

International Nuclear Information System (INIS)

Gupta, V.; Goyal, M.; Mishra, N.; Gaikwad, S.; Sharma, A.

1997-01-01

Purpose: To evaluate the role of MR imaging in the localisation of cerebrospinal fluid (CSF) fistulae. Material and Methods: A total of 36 consecutive unselected patients with either clincally proven CSF leakage (n=26) or suspected CSF fistula (n=10) were prospectively evaluated by MR. All MR examinations included fast spin-echo T2-weighted images in the 3 orthogonal planes. Thin-section CT was performed following equivocal or negative MR examination. MR and CT findings were correlated with surgical results in 33 patients. Results: CSF fistula was visualised as a dural-bone defect with hyperintense fluid signal continuous with that in the basal cisterns on T2-weighted images. MR was positive in 26 cases, in 24 of which the fistula was confirmed surgically. In 2 patients the CSF leakage was directly demonstrated on MR. MR sensitivity of 80% compared favourably with the reported 46-81% of CT cisternography (CTC). No significant difference in MR sensitivity in detecting CSF fistula was found between active and inactive leaks. (orig.)

Normal anatomy and MR findings of fetal main organs at MR imaging

International Nuclear Information System (INIS)

Xia Liming; Zou Mingli; Feng Dingyi; Hu Junwu; Qi Jianpin; Wang Chengyuan

2005-01-01

Objective: To investigate normal anatomy and MR findings of fetal main organs. Methods: Forty-seven fetus underwented fast MR imaging, SSFSE sequence was used, the normal anatomy and MR findings of fetal main organs was observed in different gestational age. The organs included: brain, lungs, heart, liver, spleen, gastrointestinal tract, urinary collecting systems, bladder, bones, spine, and subcutaneous fat. Results: Results of MR in 47 fetus showed that the main organs had developed by 20-week-old fetus, about 20 weeks gestation, cerebral cortical surface was smooth, no cortical gyri and sulci, then cortical gyri and sulci developed slowly. The lungs, trachea, bronchus, gastrointestinal tract, renal collecting system and bladder showed high signal intensity; the heart, great vessels, liver, spleen, bones and muscles appeared hypointense; the kidneys appeared isointense, the spine had developed and subcutaneous fat was seen in 20-week-old fetus, the subcutaneous fat increased with fetus maturating. Conclusion: Normal anatomy and MR findings of fetal main organs were clearly showed by fast MR imaging, and they are different from the newborns. (authors)

MR imaging of articular cartilage; Gelenkknorpel in der MR-Tomographie

Energy Technology Data Exchange (ETDEWEB)

Schaefer, F.K.W.; Muhle, C.; Heller, M.; Brossmann, J. [Kiel Univ. (Germany). Klinik fuer Diagnostische Radiologie

2001-04-01

MR imaging has evolved to the best non-invasive method for the evaluation of articular cartilage. MR imaging helps to understand the structure and physiology of cartilage, and to diagnose cartilage lesions. Numerous studies have shown high accuracy and reliability concerning detection of cartilage lesions and early changes in both structure and biochemistry. High contrast-to-noise ratio and high spatial resolution are essential for analysis of articular cartilage. Fat-suppressed 3D-T{sub 1} weighted gradient echo and T{sub 2}-weighted fast spin echo sequences with or without fat suppression are recommended for clinical routine. In this article the anatomy and pathology of hyaline articular cartilage and the complex imaging characteristics of hyaline cartilage will be discussed. (orig.) [German] Die MR-Tomographie hat sich zur besten nichtinvasiven bildgebenden Methode fuer die Untersuchung von Gelenkknorpel entwickelt. Die MR-Tomographie liefert einen Beitrag zum Verstaendnis der Knorpelstruktur und der Physiologie sowie zur Diagnostik von Knorpelschaeden. Zahlreiche MR-Studien konnten eine hohe Genauigkeit und Zuverlaessigkeit bei der Detektion chondraler Laesionen sowie frueher Veraenderungen struktureller und biochemischer Natur zeigen. Neben einem hohen Kontrast/Rausch-Verhaeltnis ist fuer die Gelenkknorpelanalyse eine hohe raeumliche Aufloesung erforderlich. Im klinischen Routinebetrieb empfehlen sich fuer die Erkennung von Knorpellaesionen besonders fettunterdrueckte 3D-T{sub 1}-gewichtete Gradientenecho- und T{sub 2}-gewichtete Fastspinecho-Sequenzen mit oder ohne Fettunterdrueckung. Die vorliegende Arbeit geht auf die Anatomie und Pathologie des hyalinen Gelenkknorpels ein und diskutiert das komplexe MR-Signalverhalten. (orig.)

MR morphology of triangular fibrocartilage complex: correlation with quantitative MR and biomechanical properties

Energy Technology Data Exchange (ETDEWEB)

Bae, Won C.; Chang, Eric Y.; Chung, Christine B. [VA San Diego Healthcare System, Radiology Service, San Diego, CA (United States); University of California-San Diego, Department of Radiology, San Diego, CA (United States); Ruangchaijatuporn, Thumanoon [Mahidol University, Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine Ramathibodi Hospital, Rachathewi, Bangkok (Thailand); Biswas, Reni; Du, Jiang; Statum, Sheronda [University of California-San Diego, Department of Radiology, San Diego, CA (United States)

2016-04-15

To evaluate pathology of the triangular fibrocartilage complex (TFCC) using high-resolution morphologic magnetic resonance (MR) imaging, and compare with quantitative MR and biomechanical properties. Five cadaveric wrists (22-70 years) were imaged at 3 T using morphologic (proton density weighted spin echo, PD FS, and 3D spoiled gradient echo, 3D SPGR) and quantitative MR sequences to determine T2 and T1rho properties. In eight geographic regions, morphology of TFC disc and laminae were evaluated for pathology and quantitative MR values. Samples were disarticulated and biomechanical indentation testing was performed on the distal surface of the TFC disc. On morphologic PD SE images, TFC disc pathology included degeneration and tears, while that of the laminae included degeneration, degeneration with superimposed tear, mucinous transformation, and globular calcification. Punctate calcifications were highly visible on 3D SPGR images and found only in pathologic regions. Disc pathology occurred more frequently in proximal regions of the disc than distal regions. Quantitative MR values were lowest in normal samples, and generally higher in pathologic regions. Biomechanical testing demonstrated an inverse relationship, with indentation modulus being high in normal regions with low MR values. The laminae studied were mostly pathologic, and additional normal samples are needed to discern quantitative changes. These results show technical feasibility of morphologic MR, quantitative MR, and biomechanical techniques to characterize pathology of the TFCC. Quantitative MRI may be a suitable surrogate marker of soft tissue mechanical properties, and a useful adjunct to conventional morphologic MR techniques. (orig.)

MR morphology of triangular fibrocartilage complex: correlation with quantitative MR and biomechanical properties

International Nuclear Information System (INIS)

Bae, Won C.; Chang, Eric Y.; Chung, Christine B.; Ruangchaijatuporn, Thumanoon; Biswas, Reni; Du, Jiang; Statum, Sheronda

2016-01-01

To evaluate pathology of the triangular fibrocartilage complex (TFCC) using high-resolution morphologic magnetic resonance (MR) imaging, and compare with quantitative MR and biomechanical properties. Five cadaveric wrists (22-70 years) were imaged at 3 T using morphologic (proton density weighted spin echo, PD FS, and 3D spoiled gradient echo, 3D SPGR) and quantitative MR sequences to determine T2 and T1rho properties. In eight geographic regions, morphology of TFC disc and laminae were evaluated for pathology and quantitative MR values. Samples were disarticulated and biomechanical indentation testing was performed on the distal surface of the TFC disc. On morphologic PD SE images, TFC disc pathology included degeneration and tears, while that of the laminae included degeneration, degeneration with superimposed tear, mucinous transformation, and globular calcification. Punctate calcifications were highly visible on 3D SPGR images and found only in pathologic regions. Disc pathology occurred more frequently in proximal regions of the disc than distal regions. Quantitative MR values were lowest in normal samples, and generally higher in pathologic regions. Biomechanical testing demonstrated an inverse relationship, with indentation modulus being high in normal regions with low MR values. The laminae studied were mostly pathologic, and additional normal samples are needed to discern quantitative changes. These results show technical feasibility of morphologic MR, quantitative MR, and biomechanical techniques to characterize pathology of the TFCC. Quantitative MRI may be a suitable surrogate marker of soft tissue mechanical properties, and a useful adjunct to conventional morphologic MR techniques. (orig.)

MR morphology of triangular fibrocartilage complex: correlation with quantitative MR and biomechanical properties.

Science.gov (United States)

Bae, Won C; Ruangchaijatuporn, Thumanoon; Chang, Eric Y; Biswas, Reni; Du, Jiang; Statum, Sheronda; Chung, Christine B

2016-04-01

To evaluate pathology of the triangular fibrocartilage complex (TFCC) using high-resolution morphologic magnetic resonance (MR) imaging, and compare with quantitative MR and biomechanical properties. Five cadaveric wrists (22-70 years) were imaged at 3 T using morphologic (proton density weighted spin echo, PD FS, and 3D spoiled gradient echo, 3D SPGR) and quantitative MR sequences to determine T2 and T1rho properties. In eight geographic regions, morphology of TFC disc and laminae were evaluated for pathology and quantitative MR values. Samples were disarticulated and biomechanical indentation testing was performed on the distal surface of the TFC disc. On morphologic PD SE images, TFC disc pathology included degeneration and tears, while that of the laminae included degeneration, degeneration with superimposed tear, mucinous transformation, and globular calcification. Punctate calcifications were highly visible on 3D SPGR images and found only in pathologic regions. Disc pathology occurred more frequently in proximal regions of the disc than distal regions. Quantitative MR values were lowest in normal samples, and generally higher in pathologic regions. Biomechanical testing demonstrated an inverse relationship, with indentation modulus being high in normal regions with low MR values. The laminae studied were mostly pathologic, and additional normal samples are needed to discern quantitative changes. These results show technical feasibility of morphologic MR, quantitative MR, and biomechanical techniques to characterize pathology of the TFCC. Quantitative MRI may be a suitable surrogate marker of soft tissue mechanical properties, and a useful adjunct to conventional morphologic MR techniques.

MR imaging of normal bone marrow; Obraz MR prawidlowego szpiku kostnego

Energy Technology Data Exchange (ETDEWEB)

Stajgis, M.; Paprzycki, W. [Osrodek Diagnostyki Obrazowej IR, Akademia Medyczna, Poznan (Poland)

1994-12-31

Principles of MR bone marrow imaging on the basis of retrospective analysis of MR examinations of bone marrow in different anatomic sites in 200 patients have been discussed. Significance of different physiologic factors and processes such as age, steatosis, osteoporosis, conversion and reconversion, which influence on MR bone marrow images, have been emphasized. T1-weighted images obtained with spin-echo sequences give the most of information about bone marrow structure in MR. Thorough knowledge of bone marrow physiology and clinical status of the patient is indispensable in correct interpretation of hypointensive lesions on T1-weighted images. When presence of disseminated bone marrow disease is suspected, authors propose routine imaging of lumbar vertebral column, pelvis and proximal parts of femoral bones. (author) 7 refs, 7 figs

MR imaging of rhabdomyolysis

International Nuclear Information System (INIS)

Zagoria, R.J.; Karstaedt, N.; Koubek, T.D.

1986-01-01

The use of magnetic resonance (MR) imaging in two cases of rhabdomyolysis, one resulting from prolonged muscle compression and one from electrical burns, is described. The involved muscles were clearly demonstrated with MR. Recognition and assessment of the extent of rhabdomyolysis are important since life-threatening sequelae including severe metabolic disorders are possible. In one case, spin-echo and inversion-recovery MR imaging provided greater detail of muscle abnormalities than did 99mTc-pyrophosphate radionuclide scanning. Both cases illustrate the usefulness of MR in evaluation of skeletal muscle disorders

MR imaging and MR angiography in popliteal artery entrapment syndrome

International Nuclear Information System (INIS)

Atilla, S.; Akpek, S.; Yuecel, C.; Tali, E.T.; Isik, S.; Ilgit, E.T.

1998-01-01

Popliteal artery entrapment (PAE) syndrome is an uncommon congenital anomaly seen in young adults causing ischemic symptoms in the lower extremities. It is the result of various types of anomalous relationships between the popliteal artery and the neighboring muscular structures. The purpose of this study was to define the role of MR imaging combined with MR angiography in the diagnosis of PAE cases. Four cases with segmental occlusion and medial displacement of popliteal artery in digital subtraction angiography (DSA) examinations were diagnosed as PAE syndrome by MR imaging and MR angiography. The DSA and MRA images are compared. All of the cases showed various degrees of abnormal intercondylar insertion of the medial head of the gastrocnemius muscle. The MR images showed detailed anatomy of the region revealing the cause of the arterial entrapment. Subclassification of the cases were done and fat tissue filling the normal localization of the muscle was evaluated. The DSA and MRA images demonstrated the length and localization of the occluded segment and collateral vascular developments equally. It is concluded that angiographic evaluation alone in PAE syndrome might result in overlooking the underlying cause of the arterial occlusion, which in turn leads to unsuccessful therapy procedures such as balloon angioplasty. Magnetic resonance imaging combined with MR angiography demonstrates both the vascular anatomy and the variations in the muscular structures in the popliteal fossa successfully, and this combination seems to be the most effective way of evaluating young adults with ischemic symptoms suggesting PAE syndrome. (orig.)

Accuracy of 3-Tesla MR and MR arthrography in diagnosis of meniscal retear in the post-operative knee

Energy Technology Data Exchange (ETDEWEB)

Magee, Thomas [NSI, Merritt Island, FL (United States); University of Central Florida School of Medicine, Orlando, FL (United States)

2014-08-15

This study assesses the accuracy of 3-Tesla (3-T) conventional MR imaging, 3-T MR arthrography, and the combined use of conventional MR and MR arthrography in the diagnosis of meniscal retears as compared with arthroscopy. The study also assess whether there are false-negative cases in which injected contrast does not extend into the meniscus despite a meniscal retear being seen on arthroscopy. One hundred consecutive knee MR arthrograms performed on patients with previous knee surgery were reviewed retrospectively. 3-T conventional MR imaging, 3-T MR arthrography, and the combined use of conventional MR and MR arthrography were assessed for meniscal retears as compared with arthroscopy. The criterion used to diagnose a meniscal retear on MR arthrogram was injected contrast tracking into the meniscus. All patients underwent second-look arthroscopy. Seventy-four patients had conventional MR findings consistent with a meniscal retear. In 83 of the 100 patients, intraarticular contrast helped in demonstrating a retear. In ten patients, there were MR findings consistent with a meniscal retear despite intra-articular contrast not tracking into the meniscus. Ninety-four of the 100 patients had meniscal retears on second-look arthroscopy. Three-Tesla conventional MR examination was 78 % sensitive and 75 % specific, MR arthrogram examination was 88 % sensitive and 100 % specific, and the combined use of MR and MR arthrogram imaging was 98 % sensitive and 75 % specific in the diagnosis of a meniscal retear. The combined use of 3-T MR and MR arthrography allows for high sensitivity and specificity in meniscal retear detection. In some patients, intraarticular contrast will not track into a meniscal retear. When MR findings are consistent with a meniscal retear but contrast does not extend into the meniscus, a meniscal retear is likely. (orig.)

Von Mr Classic zu Mr Nerd: Wie Forschende soziale Medien nutzen

Directory of Open Access Journals (Sweden)

Doreen Siegfried

2014-12-01

Full Text Available Unter Wissenschaftlerinnen und Wissenschaftlern lassen sich vier Typen differenzieren, die ein signifikant unterschiedliches Verhalten in ihrer Nutzung und ihrer Einstellung gegenüber Social-Web-Anwendungen zeigen: Ms Maker, Mr Tech, Mr Classic und Mr Nerd. Grundlage für die Identifizierung dieser Social-Media-Typen ist die Auswertung von 778 Online-Fragebögen, die von Anfang September bis Mitte Oktober 2013 erhoben wurden. Erfragt wurde die Nutzung von Social-Media-Instrumenten für die tägliche Arbeit in Forschung, Lehre, Administration und Wissenschaftskommunikation. Neben Intensität und Kontext der Nutzung von Web-2.0-Diensten wurden auch die Gründe für Nutzung bzw. Nicht-Nutzung einzelner Kanäle sowie generelle Einstellungen gegenüber Social-Media-Werkzeugen erfragt. Among scientists, four types of personality can be identified whose usage and attitude towards social web applications show significant variations: Ms Maker, Mr Tech, Mr Classic and Mr Nerd. This typification is based on 778 online questionnaires received between September and October 2013. The survey sampled the usage of social media tools for daily routines in research, teaching, administrative work and scholarly communication. The survey asked questions about the intensity and the context in which Web 2.0 services are used, about the reasons for (not using certain channels, and about general attitudes towards social media tools.

Functional MR imaging on an open 1T MR imaging system: exploiting the advantages of an open MR imaging system for functional MR imaging

NARCIS (Netherlands)

van de Giessen, E.; Groot, P. F. C.; Booij, J.; van den Brink, W.; Veltman, D. J.; Nederveen, A. J.

2011-01-01

Open MR imaging scanners are designed for imaging of specific patient groups that cannot be routinely scanned with conventional MR imaging scanners (eg, patients with obesity and claustrophobia). This study aims to determine whether BOLD sensitivity on an open 1T scanner is adequate for fMRI for

MR spectroscopy in dementia; MR-Spektroskopie bei Demenz

Energy Technology Data Exchange (ETDEWEB)

Hauser, T.; Gerigk, L.; Giesel, F.; Schuster, L.; Essig, M. [Deutsches Krebsforschungszentrum (DKFZ) Heidelberg, Abteilung E010, Radiologie, Heidelberg (Germany)

2010-09-15

With an increasingly aging population we are faced with the problem of an increasing number of dementia patients. In addition to clinical, neuropsychological and laboratory procedures, MRI plays an important role in the early diagnosis of dementia. In addition to various morphological changes functional changes can also help in the diagnosis and differential diagnosis of dementia. Overall the diagnosis of dementia can be improved by using parameters from MR spectroscopy. This article focuses on MR spectroscopic changes in the physiological aging process as well as on changes in mild cognitive impairment a precursor of Alzheimer's dementia, in Alzheimer's dementia, frontotemporal dementia, vascular dementia and Lewy body dementia. (orig.) [German] Angesichts einer immer aelter werdenden Bevoelkerung sind wir mit dem Problem einer zunehmenden Zahl an Demenzerkrankungen konfrontiert. Neben klinischen, neuropsychologischen und laborchemischen Verfahren spielt die MRT zur Fruehdiagnostik einer Demenz eine wichtige Rolle. Morphologische Veraenderungen wie auch verschiedene funktionelle Verfahren helfen bei der Diagnostik und Differenzialdiagnostik einer Demenz. Insgesamt kann mittels MR-spektroskopischer Parameter die Diagnostik einer Demenz verbessert werden. In diesem Artikel soll auf MR-spektroskopische Veraenderungen im Rahmen des physiologischen Alterungsprozesses eingegangen werden. Ferner werden speziell Veraenderungen bei leichter kognitiver Beeintraechtigung, einer Vorform der Alzheimer-Demenz, bei Alzheimer-, frontotemporaler, vaskulaerer und Lewy-Koerper-Demenz eroertert. (orig.)

3.0 T conventional hip MR and hip MR arthrography for the acetabular labral tears confirmed by arthroscopy

Energy Technology Data Exchange (ETDEWEB)

Tian, Chun-Yan [Department of Radiology, Peking University Third Hospital, 49 North Garden Road, Haidian District, Beijing 100191 (China); Wang, Jian-Quan [Department of Sports Medicine, Peking University Third Hospital, 49 North Garden Road, Haidian District, Beijing 100191,PR China (China); Zheng, Zhuo-Zhao, E-mail: zzhuozhao@aliyun.com [Department of Radiology, Peking University Third Hospital, 49 North Garden Road, Haidian District, Beijing 100191 (China); Ren, A.-Hong [Department of Radiology, Beijing Daxing Hospital, 26 West Huangcun Road, Daxing District, Beijing 102600 (China)

2014-10-15

Highlights: • MR is the preferred imaging modality for diagnosing acetabular labral tears. • The diagnostic performance of MR arthrography are superior than conventional hip MR. • The hip MR arthrography is recommended for diagnosing acetabular labral lesions. - Abstract: Objective: To evaluate the value of hip MR for diagnosing acetabular labrum tears, and to further compare the diagnostic performances of conventional MR with MR arthrography in acetabular labrum tears. Methods: 90 patients undergoing both hip MR examination and subsequent hip arthroscopy were retrospectively evaluated. Of these patients, 34 accepted both conventional MR and MR arthrography; while the other 56 only underwent conventional MR examination. All hip MR images were independently reviewed by two radiologists, and further compared with the results of hip arthroscopy. Results: 59 of 90 patients were confirmed with acetabular labral tears by hip arthroscopy and 31 without tears. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of conventional MR for evaluating the acetabular labral tears were 61.0%, 77.4%, 83.7% and 51.1% (radiologist A), and 66.1%, 74.2%, 82.9% and 53.4% (radiologist B), respectively, with good consistency between the two observers (K = 0.645). The sensitivity, specificity, PPV and NPV of MR arthrography for assessing the acetabular labral tears were 90.5%, 84.6%, 90.5% and 84.6% (radiologist A), and 95.2%, 84.6%, 90.9% and 91.7% (radiologist B), respectively, with excellent good consistency between the two observers (K = 0.810). The sensitivity and NPV of MR arthrography for diagnosing the acetabular labral tears were significantly higher than those of conventional MR (both P < 0.05). Conclusion: Hip MR arthrography is a reliable evaluation modality for diagnosing the acetabular labral tears, and its diagnostic performance is superior to that of conventional MR at 3.0 T.

MR-guided pain therapy: principles and clinical applications; MR-gesteuerte Schmerztherapie: Prinzipien und klinische Applikationen

Energy Technology Data Exchange (ETDEWEB)

Fritz, J.; Pereira, P.L. [Diagnostische Radiologie, Eberhard-Karls-Universitaet, Tuebingen (Germany)

2007-09-15

X-ray fluoroscopy and computed tomography are frequently used to perform percutaneous interventions in pain therapy. The development of MR-compatible therapy needles now allows these interventions to be performed under MR imaging guidance. MR-guided interventions may be performed using most clinical MR scanners; however, systems with an open configuration are advantageous. Multiplanar pre- and intra-procedural MR imaging provides the interventionalist with essential information, such as evaluation of anatomy and pathology, as well as the planning of the procedure and monitoring of fluid distribution without the use of contrast agents. With the use of non-ionizing radiation, interventional MR imaging is especially suited for the treatment of children and young adults as well as for serial injection therapy. For spinal MR interventions, passive needle visualization is an easily achievable and reliable method. The resulting needle artifact is influenced by several factors such as the alloy of the needle, the strength of the static magnetic field, the sequence type, the spatial orientation of the therapy needle as well as the echo time and may further be optimized during the intervention by alteration of the last three factors. Fast acquisition techniques and image processing allow for continuous, near real-time MR imaging (so-called MR fluoroscopy) and interactive needle navigations, comparable to X-ray fluoroscopy and CT fluoroscopy. The purpose of this review is to illustrate and discuss general concepts of interventional MR imaging. A spectrum of interventional MR imaging procedures in spinal pain therapy is described and illustrated, including procedures such as lumbar facet joint injections, sacroiliac joint injections, lumbar spinal nerve root infiltrations and drug delivery to the lumbar sympathetic chain. (orig.)

MR imaging of colorectal carcinomas using an MR endoscopic coil

International Nuclear Information System (INIS)

Murano, Akihiko; Kido, Choichiro; Sasaki, Fumio; Nakamura, Tsuneya; Kobayashi, Semi; Katoh, Tomoyuki; Hirai, Takashi

1994-01-01

Diagnosis of the depth of wall invasion by rectal carcinoma using MR endoscopy was performed in ten resected specimens, including five rectal carcinomas, three colon carcinomas, two normal gastric wall. In addition, the gastric wall of a pig was examined. MR imaging was done with a 1.5-T Signa Advantage (GE Medical System) system, with the surface coil of the MR endoscope acting as the receiver coil. Five layers could be distinguished in the bowel wall: mucosa, submucosa and muscularis propria divided into circular muscle, longitudinal muscle and intervening connective tissue. Tumors had almost the same signal intensity as muscle. The MR images of colon carcinomas, rectal carcinomas, and extrinsically metastatic involvement of the sigmoid colon by rectal carcinoma all correlated well with the pathological findings. The normal structure of the gastric wall was similar to that of the colon. 3D-fast Spoiled Grass (SPGR) sequence has a fairly short scanning time. Thus, the possibility of precise clinical diagnosis by this method was suggested. (author)

Current status of MR colonography.

LENUS (Irish Health Repository)

Thornton, Eavan

2010-01-01

The search for an acceptable colorectal cancer screening examination has led to the development of virtual colonoscopy, which includes both computed tomographic (CT) colonography and magnetic resonance (MR) colonography. As indicated by the much larger number of published studies on CT colonography than on MR colonography, multidetector CT appears to be more suitable for colorectal screening than does MR colonography, in part reflecting the ease and speed of performing CT, as well as the increased spatial resolution, decreased cost, and wider availability of CT colonography. The main advantage of MR colonography over CT colonography is that it does not use ionizing radiation, which has important implications for colorectal cancer screening. The use of dark-lumen MR colonography to screen patients for colorectal cancer as well as other abdominopelvic disease could make it more attractive than CT. With the integration of 3.0-T MR colonography, fecal tagging, and parallel imaging into research and clinical settings, new MR colonography protocols must be optimized. Future MR colonography research should address issues such as image characteristics, presence of artifacts, management of specific absorption rate, and hardware-related modifications.

MR-assisted PET Motion Correction for eurological Studies in an Integrated MR-PET Scanner

Science.gov (United States)

Catana, Ciprian; Benner, Thomas; van der Kouwe, Andre; Byars, Larry; Hamm, Michael; Chonde, Daniel B.; Michel, Christian J.; El Fakhri, Georges; Schmand, Matthias; Sorensen, A. Gregory

2011-01-01

Head motion is difficult to avoid in long PET studies, degrading the image quality and offsetting the benefit of using a high-resolution scanner. As a potential solution in an integrated MR-PET scanner, the simultaneously acquired MR data can be used for motion tracking. In this work, a novel data processing and rigid-body motion correction (MC) algorithm for the MR-compatible BrainPET prototype scanner is described and proof-of-principle phantom and human studies are presented. Methods To account for motion, the PET prompts and randoms coincidences as well as the sensitivity data are processed in the line or response (LOR) space according to the MR-derived motion estimates. After sinogram space rebinning, the corrected data are summed and the motion corrected PET volume is reconstructed from these sinograms and the attenuation and scatter sinograms in the reference position. The accuracy of the MC algorithm was first tested using a Hoffman phantom. Next, human volunteer studies were performed and motion estimates were obtained using two high temporal resolution MR-based motion tracking techniques. Results After accounting for the physical mismatch between the two scanners, perfectly co-registered MR and PET volumes are reproducibly obtained. The MR output gates inserted in to the PET list-mode allow the temporal correlation of the two data sets within 0.2 s. The Hoffman phantom volume reconstructed processing the PET data in the LOR space was similar to the one obtained processing the data using the standard methods and applying the MC in the image space, demonstrating the quantitative accuracy of the novel MC algorithm. In human volunteer studies, motion estimates were obtained from echo planar imaging and cloverleaf navigator sequences every 3 seconds and 20 ms, respectively. Substantially improved PET images with excellent delineation of specific brain structures were obtained after applying the MC using these MR-based estimates. Conclusion A novel MR-based MC

MR imaging of the pelvis

International Nuclear Information System (INIS)

Hricak, H.

1987-01-01

MR imaging, CT, and US should be viewed as complementary studies for imaging the pelvis. MR imaging is relatively expensive, not widely available, and requires special facilities. However, it is noninvasive and offers a large field-of-view, direct imaging in all three orthogonal planes and excellent soft-tissue contrast. Surgical clips, which present a problem with other imaging modalities, do not create significant MR image artifacts. Image degradation due to bowel motion can be minimized by bowel preparation and/or the administration of glucagon. The value of MR imaging of the pelvis is in staging rather than diagnosis of pelvic neoplasms. The accuracy, sensitivity, and specificity of MR imaging in staging prostate or bladder tumors exceed those of US and CT. In prostate carcinoma, MR imaging can be used to evaluate periprostatic tumor extension, especially to the bladder base, rectum, or seminal vesicles. For early transcapsular extension, however, the accuracy of transrectal US reportedly surpasses that of MR imaging. In bladder carcinoma, the value of MR imaging is in direct tumor visualization, the ability to differentiate between tumor and normal bladder wall, and the evaluation of bladder tumors located at the dome of the bladder base, where imaging in the sagittal plane is essential. In the evaluation of benign entities of the female pelvis, US remains the preferred screening modality. The use of MR imaging is reserved for cases of infertility or for planning myomectomy when knowledge of the exact number, size, and location of tumors is essential. MR imaging is useful in evaluating patients with amenorrhea or any suspected congenital anomalies. The main application of MR imaging of the female pelvis is in the staging of neoplasms, including endometrial and cervical carcinomas

MR imaging of the brain: tumors

International Nuclear Information System (INIS)

Sartor, K.

1999-01-01

The radiologic modality that most likely provides the imaging information needed in a patient suspected of having a brain tumor is MR imaging. A brain tumor can be reliably ruled out if the MR examination is performed properly and experts interpret the results as negative. If there is a tumor, however, its exact location and topography must be determined. Important for therapy and prognosis are also tumor properties such as histologic type and grade, as well as effects on adjacent brain structures. Although potentially a noninvasive method of in vivo neuropathology, MR is still far from being sufficiently specific, as dissimilar lesions may look the same despite the use of refined imaging protocols. The evolution of MR imaging continues, however, making further methodologic improvement likely. Presently, advanced methods, such as diffusion- and perfusion-weighted MR imaging, functional MR imaging, neuronavigation based on MR imaging data, and the use of MR imaging during surgery (intraoperative MR imaging), influence the way patients are treated. Likewise, follow-up imaging (monitoring) of tumor patients by MR has become more effective, and experience has shown how to distinguish reactive changes from recurrent tumor. In the future, MR imaging may gain importance in the development of novel therapeutic concepts. (orig.)

Safety issues and updates under MR environments

Energy Technology Data Exchange (ETDEWEB)

Kim, Soo Jung; Kim, Kyung Ah, E-mail: bellenina@daum.net

2017-04-15

Highlights: • Unexpected biological effects can occur within stronger magnetic fields. • MR safety for MR conditional items is not guaranteed beyond the tested conditions. • Updated knowledge about MR-related safety is important for a safe MR environment. - Abstract: Magnetic resonance (MR) imaging is a useful imaging tool with superior soft tissue contrast for diagnostic evaluation. The MR environments poses unique risks to patients and employees differently from ionizing radiation exposure originated from computed tomography and plain x-ray films. The technology associated with MR system has evolved continuously since its introduction in the late 1970s. MR systems have advanced with static magnetic fields, faster and stronger gradient magnetic fields and more powerful radiofrequency transmission coils. Higher field strengths of MR offers greater signal to noise capability and better spatial resolution, resulting in better visualization of anatomic detail, with a reduction in scan time. With the rapid evolution of technology associated with MR, we encounter new MR-related circumstances and unexpected dangerous conditions. A comprehensive update of our knowledge about MR safety is necessary to prevent MR-related accidents and to ensure safety for patients and staff associated with MR. This review presents an overview about MR-related safety issues and updates.

Imaging manifestation of hepatocellular carcinoma with bile duct tumor thrombi

International Nuclear Information System (INIS)

Liu Qingyu; Chen Jianyu; Liang Biling; Hu Tao

2008-01-01

Objective: To analyze the imaging features of hepatocellular carcinoma(HCC) with bile duct tumor thrombi. Methods: Thirteen patients with bile duct tumor thrombi proved pathologically underwent imaging examination. MR and CT were performed in 3 cases, and 2 cases had CT only and 8 cases had MRI only. Ultrasonography(US) was performed in all 13 patients. The accuracy of bile duct tumor thrombi detection was compared between US, CT and MRI with Fisher test. Results: Liver tumors and bile duct tumor thrombi were demonstrated in all patients on CT or MRI. Presence of intraluminal soft tissue mass was found in four of five cases on CT, and mild enhancement of the intraluminal mass in the arterial phase was noted, dilated bile duct distal to tumor thrombi was detected in all five patients. Eleven Tumor thrombi showed slight low signal intensity on T 1 WI, slight high signal intensity on T 2 WI, and mild to moderate contrast enhancement on the contrast-enhanced MR images. The MRCP findings of tumor thrombi were as follows: interruption, stricture of the bile ducts or irregular filling defect in the bile ducts with dilated intrahepatic ducts, bile duet was abruptly interrupted or showed a 'rat-tail' stricture (n=5); the common bile duct was filled with tumor thrombi, intrahepatic bile duct dilatation and missing common bile duct was noted on MRCP (n=2). Bile duct tumor thrombi were correctly diagnosed in 7 cases on US, and 12 cases on CT or MRI. Six cases were misdiagnosed or miss-diagnosed on US, and 4 cases were misdiagnosed on CT or MRI. There was no significant difference between US and CT/MRI in diagnosis of bile duct tumor thrombi (P=0.270). Conclusion: CT or MR imaging is useful for the diagnosis of HCC with biliary tumor thrombi and for evaluating the extension of thrombi. (authors)

Quality of MR thermometry during palliative MR-guided high-intensity focused ultrasound (MR-HIFU) treatment of bone metastases

NARCIS (Netherlands)

Lam, Mie K; Huisman, Merel; Nijenhuis, Robbert J; van den Bosch, Maurice; Viergever, Max A; Moonen, Chrit Tw; Bartels, LW

2015-01-01

BACKGROUND: Magnetic resonance (MR)-guided high-intensity focused ultrasound has emerged as a clinical option for palliative treatment of painful bone metastases, with MR thermometry (MRT) used for treatment monitoring. In this study, the general image quality of the MRT was assessed in terms of

Motion correction in simultaneous PET/MR brain imaging using sparsely sampled MR navigators

DEFF Research Database (Denmark)

Keller, Sune H; Hansen, Casper; Hansen, Christian

2015-01-01

BACKGROUND: We present a study performing motion correction (MC) of PET using MR navigators sampled between other protocolled MR sequences during simultaneous PET/MR brain scanning with the purpose of evaluating its clinical feasibility and the potential improvement of image quality. FINDINGS......: Twenty-nine human subjects had a 30-min [(11)C]-PiB PET scan with simultaneous MR including 3D navigators sampled at six time points, which were used to correct the PET image for rigid head motion. Five subjects with motion greater than 4 mm were reconstructed into six frames (one for each navigator...

Accuracy and interobserver agreement between MR-non-expert radiologists and MR-experts in reading MRI for suspected appendicitis

Energy Technology Data Exchange (ETDEWEB)

Leeuwenburgh, Marjolein M.N., E-mail: m.m.leeuwenburgh@amc.uva.nl [Department of Surgery, Academic Medical Center, University of Amsterdam (Netherlands); Department of Radiology, Academic Medical Center, University of Amsterdam (Netherlands); Wiarda, Bart M. [Department of Radiology, Alkmaar Medical Center, Alkmaar (Netherlands); Jensch, Sebastiaan [Department of Radiology, Sint Lucas Andreas Hospital, Amsterdam (Netherlands); Wouter van Es, H. [Department of Radiology, Sint Antonius Hospital, Nieuwegein (Netherlands); Stockmann, Hein B.A.C. [Department of Surgery, Kennemer Gasthuis, Haarlem (Netherlands); Gratama, Jan Willem C. [Department of Radiology, Gelre Hospitals, Apeldoorn (Netherlands); Cobben, Lodewijk P.J. [Department of Radiology, Haaglanden Medical Center, Leidschendam (Netherlands); Bossuyt, Patrick M.M. [Department of Clinical Epidemiology, Academic Medical Center, University of Amsterdam (Netherlands); Boermeester, Marja A. [Department of Surgery, Academic Medical Center, University of Amsterdam (Netherlands); Stoker, Jaap [Department of Radiology, Academic Medical Center, University of Amsterdam (Netherlands)

2014-01-15

Objective: To compare accuracy and interobserver agreement between radiologists with limited experience in the evaluation of abdominal MRI (non-experts), and radiologists with longer MR reading experience (experts), in reading MRI in patients with suspected appendicitis. Methods: MR imaging was performed in 223 adult patients with suspected appendicitis and read independently by two members of a team of eight MR-inexperienced radiologists, who were trained with 100 MR examinations previous to this study (non-expert reading). Expert reading was performed by two radiologists with a larger abdominal MR experience (>500 examinations) in consensus. A final diagnosis was assigned after three months based on all available information, except MRI findings. We estimated MRI sensitivity and specificity for appendicitis and for all urgent diagnoses separately. Interobserver agreement was evaluated using kappa statistics. Results: Urgent diagnoses were assigned to 147 of 223 patients; 117 had appendicitis. Sensitivity for appendicitis was 0.89 by MR-non-expert radiologists and 0.97 in MR-expert reading (p = 0.01). Specificity was 0.83 for MR-non-experts versus 0.93 for MR-expert reading (p = 0.002). MR-experts and MR-non-experts agreed on appendicitis in 89% of cases (kappa 0.78). Accuracy in detecting urgent diagnoses was significantly lower in MR-non-experts compared to MR-expert reading: sensitivity 0.84 versus 0.95 (p < 0.001) and specificity 0.71 versus 0.82 (p = 0.03), respectively. Agreement on urgent diagnoses was 83% (kappa 0.63). Conclusion: MR-non-experts have sufficient sensitivity in reading MRI in patients with suspected appendicitis, with good agreement with MR-expert reading, but accuracy of MR-expert reading was higher.

Accuracy and interobserver agreement between MR-non-expert radiologists and MR-experts in reading MRI for suspected appendicitis

International Nuclear Information System (INIS)

Leeuwenburgh, Marjolein M.N.; Wiarda, Bart M.; Jensch, Sebastiaan; Wouter van Es, H.; Stockmann, Hein B.A.C.; Gratama, Jan Willem C.; Cobben, Lodewijk P.J.; Bossuyt, Patrick M.M.; Boermeester, Marja A.; Stoker, Jaap

2014-01-01

Objective: To compare accuracy and interobserver agreement between radiologists with limited experience in the evaluation of abdominal MRI (non-experts), and radiologists with longer MR reading experience (experts), in reading MRI in patients with suspected appendicitis. Methods: MR imaging was performed in 223 adult patients with suspected appendicitis and read independently by two members of a team of eight MR-inexperienced radiologists, who were trained with 100 MR examinations previous to this study (non-expert reading). Expert reading was performed by two radiologists with a larger abdominal MR experience (>500 examinations) in consensus. A final diagnosis was assigned after three months based on all available information, except MRI findings. We estimated MRI sensitivity and specificity for appendicitis and for all urgent diagnoses separately. Interobserver agreement was evaluated using kappa statistics. Results: Urgent diagnoses were assigned to 147 of 223 patients; 117 had appendicitis. Sensitivity for appendicitis was 0.89 by MR-non-expert radiologists and 0.97 in MR-expert reading (p = 0.01). Specificity was 0.83 for MR-non-experts versus 0.93 for MR-expert reading (p = 0.002). MR-experts and MR-non-experts agreed on appendicitis in 89% of cases (kappa 0.78). Accuracy in detecting urgent diagnoses was significantly lower in MR-non-experts compared to MR-expert reading: sensitivity 0.84 versus 0.95 (p < 0.001) and specificity 0.71 versus 0.82 (p = 0.03), respectively. Agreement on urgent diagnoses was 83% (kappa 0.63). Conclusion: MR-non-experts have sufficient sensitivity in reading MRI in patients with suspected appendicitis, with good agreement with MR-expert reading, but accuracy of MR-expert reading was higher

PET/MR Imaging in Gynecologic Oncology.

Science.gov (United States)

Ohliger, Michael A; Hope, Thomas A; Chapman, Jocelyn S; Chen, Lee-May; Behr, Spencer C; Poder, Liina

2017-08-01

MR imaging and PET using 2-Deoxy-2-[ 18 F]fluoroglucose (FDG) are both useful in the evaluation of gynecologic malignancies. MR imaging is superior for local staging of disease whereas fludeoxyglucose FDG PET is superior for detecting distant metastases. Integrated PET/MR imaging scanners have great promise for gynecologic malignancies by combining the advantages of each modality into a single scan. This article reviews the technology behind PET/MR imaging acquisitions and technical challenges relevant to imaging the pelvis. A dedicated PET/MR imaging protocol; the roles of PET and MR imaging in cervical, endometrial, and ovarian cancers; and future directions for PET/MR imaging are discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

A 16-channel MR coil for simultaneous PET/MR imaging in breast cancer

International Nuclear Information System (INIS)

Dregely, Isabel; Lanz, Titus; Mueller, Matthias F.; Metz, Stephan; Kuschan, Marika; Nimbalkar, Manoj; Ziegler, Sibylle I.; Nekolla, Stephan G.; Schwaiger, Markus; Bundschuh, Ralph A.; Haase, Axel

2015-01-01

To implement and evaluate a dedicated receiver array coil for simultaneous positron emission tomography/magnetic resonance (PET/MR) imaging in breast cancer. A 16-channel receiver coil design was optimized for simultaneous PET/MR imaging. To assess MR performance, the signal-to-noise ratio, parallel imaging capability and image quality was evaluated in phantoms, volunteers and patients and compared to clinical standard protocols. For PET evaluation, quantitative 18 F-FDG PET images of phantoms and seven patients (14 lesions) were compared to images without the coil. In PET image reconstruction, a CT-based template of the coil was combined with the MR-acquired attenuation correction (AC) map of the phantom/patient. MR image quality was comparable to clinical MR-only examinations. PET evaluation in phantoms showed regionally varying underestimation of the standardised uptake value (SUV; mean 22 %) due to attenuation caused by the coil. This was improved by implementing the CT-based coil template in the AC (<2 % SUV underestimation). Patient data indicated that including the coil in the AC increased the SUV values in the lesions (21 ± 9 %). Using a dedicated PET/MR breast coil, state-of-the-art MRI was possible. In PET, accurate quantification and image homogeneity could be achieved if a CT-template of this coil was included in the AC for PET image reconstruction. (orig.)

Abdominal MR angiography

International Nuclear Information System (INIS)

Wegmueller, H.; Vock, P.

1993-01-01

The two techniques currently most often used for MR angiography, those based on time-of-flight effects and on phase-contrast, are introduced, and our results with three-dimensional phase contrast angiography of the abdomen are presented. Several basic differences from other imaging procedures render MR angiography clinically useful for screening for renal artery stenosis in critical situations, such as renal failure or intolerance to contrast agents. In the future, the spectrum of applications of MR angiography will broaden and include other indications, such as portal venous hypertension and follow-up studies after surgical portal systemic shunting. (orig.) [de

Visit of Mr. Susumu Yoda, Japanese Atomic Energy Commission, Mr. Nobuo Natsume, Vice-President, Central Research Institute of Electric Power Industry, Japan (CRIEPI), Mr. Nobuya Yoshiki, CRIEPI, Mrs. Seiko Ichikawa, Interpreter, with Mr. Taylor of CERN, visiting SM18

CERN Multimedia

Laurent Guiraud

2000-01-01

Visit of Mr. Susumu Yoda, Japanese Atomic Energy Commission, Mr. Nobuo Natsume, Vice-President, Central Research Institute of Electric Power Industry, Japan (CRIEPI), Mr. Nobuya Yoshiki, CRIEPI, Mrs. Seiko Ichikawa, Interpreter, with Mr. Taylor of CERN, visiting SM18

MR myelography of sacral meningeal cysts

International Nuclear Information System (INIS)

Tsuchiya, K.; Katase, S.; Hachiya, J.

1999-01-01

Purpose: To describe the findings of sacral meningeal cysts (SMCs) on MR myelography and assess its value for the diagnosis of SMCs. Material and Methods: We evaluated the MR images and MR myelograms obtained from 10 patients with SMC. MR myelograms were obtained using a 2D or 3D single-shot fast spin-echo sequence. In 5 patients, X-ray myelograms and postmyelographic CT images were compared with the MR myelograms. Results: A total of 33 SMCs were diagnosed within the spinal canal and/or sacral foramen. MR myelograms clearly revealed each cyst as a well-defined mass showing hyperintensity (10 cysts) or isointensity (23 cysts) compared to cerebrospinal fluid. MR myelograms demonstrated SMCs better than X-ray myelograms and postmyelographic CT images in 3 of the 5 patients. Conclusion: MR myelography can be an adjunct to conventional imaging techniques when surgical treatment is indicated, because it can precisely delineate the extent of SMCs. (orig.)

Characterization of a prototype MR-compatible Delta4 QA system in a 1.5 tesla MR-linac

Science.gov (United States)

de Vries, J. H. W.; Seravalli, E.; Houweling, A. C.; Woodings, S. J.; van Rooij, R.; Wolthaus, J. W. H.; Lagendijk, J. J. W.; Raaymakers, B. W.

2018-01-01

To perform patient plan quality assurance (QA) on a newly installed MR-linac (MRL) it is necessary to have an MR-compatible QA device. An MR compatible device (MR-Delta4) has been developed together with Scandidos AB (Uppsala, Sweden). The basic characteristics of the detector response, such as short-term reproducibility, dose linearity, field size dependency, dose rate dependency, dose-per-pulse dependency and angular dependency, were investigated for the clinical Delta4-PT as well as for the MR compatible version. All tests were performed with both devices on a conventional linac and the MR compatible device was tested on the MRL as well. No statistically significant differences were found in the short-term reproducibility (tesla magnetic field of the Elekta MR-linac

MR imaging of the shoulder

International Nuclear Information System (INIS)

Fritts, H.M.; Craig, E.; Kyle, R.; Strefling, M.; Miller, D.; Heithoff, K.; Schellhas, K.

1988-01-01

Magnetic resonance (MR) imaging (1.5-T unit) was performed in over 600 shoulders to evaluate shoulder pain. Ultrasound (US) and arthrography were performed in over 100 patients. Surgery was performed in over 75 patients. MR imaging offers information not well evaluated with other modalities, including bony impingement, tendinitis, bursitis, and osseous abnormalities, such as primary arthritis, avascular necrosis, occult fractures, and tumors. US and MR findings correlate well with surgical findings for medium to large rotator cuff tears. MR imaging with T2 weighting is superior for differentiating small tears from associated tendinitis. An algorithm for cost-effective shoulder imaging integrating US, MR imaging, arthrography, and computed tomographic arthrography are presented

MR appearance of central neurocytoma

International Nuclear Information System (INIS)

Chang, K.H.; Han, M.H.; Kim, D.G.; Chi, J.G.; Suh, D.C.; Kim, S.J.; Cha, S.H.; Han, M.C.

1993-01-01

To provide a detailed description of the MR appearances of central neurocytoma, MR images of 13 patients with central neurocytoma were retrospectively reviewed and compared with CT examinations. The histology was confirmed by ultrastructural and immunohistochemical studies. In 12 patients the tumors were histologically benign and located in the anterior part of the lateral ventricle, 6 of which extended to the 3rd ventricle. There was one case of a histologically malignant variant involving the thalamus and lateral ventricle. The tumors were primarily solid, but contained cysts (85%, 11/13), calcifications (69%, 9/13), and signal void from tumor vessels (62%, 8/13), frequently producing heterogeneous signal intensity on both T1- and T2-weighted images. Most of the solid portion appeared isointense or slightly hyperintense relative to the cerebral cortex on all MR pulse sequences. Calcifications were iso- or hypointense on MR, making them difficult to characterize with MR alone. Intratumoral hemorrhage was seen in 2 patients on MR but not on CT. Contrast enhancement was variable in degree and pattern. Coronal and sagittal MR images were valuable in evaluating the tumor extent and origin site, and in planning the surgical approach. It is concluded that MR imaging appears to be more useful than CT in the overall evaluation of central neurocytoma, even though calcification is better characterized with CT. (orig.)

First MR images obtained during megavoltage photon irradiation from a prototype integrated linac-MR system

International Nuclear Information System (INIS)

Fallone, B. G.; Murray, B.; Rathee, S.; Stanescu, T.; Steciw, S.; Vidakovic, S.; Blosser, E.; Tymofichuk, D.

2009-01-01

The authors report the first magnetic resonance (MR) images produced by their prototype MR system integrated with a radiation therapy source. The prototype consists of a 6 MV linac mounted onto the open end of a biplanar 0.2 T permanent MR system which has 27.9 cm pole-to-pole opening with flat gradients (40 mT/m) running under a TMX NRC console. The distance from the magnet isocenter to the linac target is 80 cm. The authors' design has resolved the mutual interferences between the two devices such that the MR magnetic field does not interfere with the trajectory of the electron in the linac waveguide, and the radiofrequency (RF) signals from each system do not interfere with the operation of the other system. Magnetic and RF shielding calculations were performed and confirmed with appropriate measurements. The prototype is currently on a fixed gantry; however, in the very near future, the linac and MR magnet will rotate in unison such that the linac is always aimed through the opening in the biplanar magnet. MR imaging was found to be fully operational during linac irradiation and proven by imaging a phantom with conventional gradient echo sequences. Except for small changes in SNR, MR images produced during irradiation were visually and quantitatively very similar to those taken with the linac turned off. This prototype system provides proof of concept that the design has decreased the mutual interferences sufficiently to allow the development of real-time MR-guided radiotherapy. Low field-strength systems (0.2-0.5 T) have been used clinically as diagnostic tools. The task of the linac-MR system is, however, to provide MR guidance to the radiotherapy beam. Therefore, the 0.2 T field strength would provide adequate image quality for this purpose and, with the addition of fast imaging techniques, has the potential to provide 4D soft-tissue visualization not presently available in image-guided radiotherapy systems. The authors' initial design incorporates a

Characterization of a prototype MR-compatible Delta4 QA-system in a 1.5 tesla MR-linac

NARCIS (Netherlands)

de Vries, Wilfred J H; Seravalli, Enrica; Houweling, Anette; Woodings, Simon J; van Rooij, Rob; Wolthaus, Jochem W H; Lagendijk, JJW; Raaymakers, Bas W

2018-01-01

To perform patient plan-quality assurance (QA) on the newly installed MR-Linac (MRL) there was a need for having an MR-compatible QA-device. An MR compatible device (MR-Delta4) was developed together with Scandidos AB (Uppsala, Sweden). The basic characteristics of the detector response

A study of artefacts in simultaneous PET and MR imaging using a prototype MR compatible PET scanner

International Nuclear Information System (INIS)

Slates, R.B.; Farahani, K.; Marsden, P.K.; Taylor, J.; Summers, P.E.; Williams, S.; Beech, J.

1999-01-01

We have assessed the possibility of artefacts that can arise in attempting to perform simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) using a small prototype MR compatible PET scanner (McPET). In these experiments, we examine MR images for any major artefacts or loss in image quality due to inhomogeneities in the magnetic field, radiofrequency interference or susceptibility effects caused by operation of the PET system inside the MR scanner. In addition, possible artefacts in the PET images caused by the static and time-varying magnetic fields or radiofrequency interference from the MR system were investigated. Biological tissue and a T 2 -weighted spin echo sequence were used to examine susceptibility artefacts due to components of the McPET scanner (scintillator, optical fibres) situated in the MR field of view. A range of commonly used MR pulse sequences was studied while acquiring PET data to look for possible artefacts in either the PET or MR images. Other than a small loss in signal-to-noise using gradient echo sequences, there was no significant interaction between the two imaging systems. Simultaneous PET and MR imaging of simple phantoms was also carried out in different MR systems with field strengths ranging from 0.2 to 4.7 T. The results of these studies demonstrate that it is possible to acquire PET and MR images simultaneously, without any significant artefacts or loss in image quality, using our prototype MR compatible PET scanner. (author)

Diagnostic Efficiency of MR Imaging of the Knee. Relationship to time Interval between MR and Arthroscopy

International Nuclear Information System (INIS)

Barrera, M. C.; Recondo, J. A.; Aperribay, M.; Gervas, C.; Fernandez, E.; Alustiza, J. M.

2003-01-01

To evaluate the efficiency of magnetic resonance (MR) in the diagnosis of knee lesions and how the results are influenced by the time interval between MR and arthroscopy. 248 knees studied by MR were retrospectively analyzed, as well as those which also underwent arthroscopy. Arthroscopy was considered to be the gold standard, MR diagnostic capacity was evaluated for both meniscal and cruciate ligament lesions. Sensitivity, specificity and Kappa index were calculated for the set of all knees included in the study (248), for those in which the time between MR and arthroscopy was less than or equal to three months (134) and for those in which the time between both procedures was less than or equal to one month. Sensitivity, specificity and Kappa index of the MR had global values of 96.5%, 70% and 71%, respectively. When the interval between MR and arthroscopy was less than or equal to three months, sensitivity, specificity and Kappa index were 95.5%, 75% and 72%, respectively. When it was less than or equal to one month, sensitivity was 100%, specificity was 87.5% and Kappa index was 91%. MR is an excellent tool for the diagnosis of knee lesions. Higher MR values of sensitivity, specificity and Kappa index are obtained when the time interval between both procedures is kept to a minimum. (Author) 11 refs

Gadolinium-enhanced excretory MR urography: comparison with MR urography using HASTE technique

International Nuclear Information System (INIS)

Jin, Gong Yong; Lee, Jeong Min; Han, Young Min; Cheong, Gyung Ho; Oh, Hee Sul; Kim, Chong Soo; Park, Sung Kwang; Kim, Young Gon

2000-01-01

To compare the feasibility of gadolinium-enhanced excretory MR urography (GEMRU) and conventional MR urography using the half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence in patients with hydronephrosis or non-visualized kidney. Fifteen patients with hydronephrosis or non-visualized kidney, as demonstrated by ultrasonography or intravenous urography, were enrolled in this study. Nine were men and six were women, and their age ranged from 18 to 77 (mean, 60.6) years. For all MR examinations, a 1.5T MR unit was employed. For breath-hold MR urography, the HASTE technique (MRU) was used, and reconstruction involved the use of a maximum intensity-projection (MIP) algorithm. For gadolinium-enhanced excretory MR urography, the fast low angle shot (FLASH) 3-D method was used and images were obtained at 5, 10, 20, and 30 minutes, and reconstruction again involved the use of MIP algorithm. In some cases, additional GEMRU was obtained 24 hour after contrast material injection, and an MIP algorithm was used for reconstruction. MRU and GEMRU were independently interpreted by two radiologists who for quantitative analysis compared SNR with CNR, and at each anatomic level qualitatively analyzed morphologic accuracy and diagnostic value of the lesions. In quantitative analysis, SNR and CNR differences between the two sequences at the renal pelvis and the level of the ureter were not significant (p greater than 0.05). In qualitative analysis, GEMRU was superior to MRU for the assessment of evaluated ureter at each level (p less than 0.05), anatomic anomaly and intrinsic tumor. Ureteral stones, however, were more easily diagnosed with MRU. For assessment of the ureter GEMRU is superior to MRU and has the advantage of evaluating renal function. We believe that for evaluation of the urinary tract, especially the distal ureter, GEMRU may be a valuable adjunct to routine MR urography. (author)

Resitting a high-stakes postgraduate medical examination on multiple occasions: nonlinear multilevel modelling of performance in the MRCP(UK examinations

Directory of Open Access Journals (Sweden)

McManus IC

2012-06-01

Full Text Available Abstract Background Failure rates in postgraduate examinations are often high and many candidates therefore retake examinations on several or even many times. Little, however, is known about how candidates perform across those multiple attempts. A key theoretical question to be resolved is whether candidates pass at a resit because they have got better, having acquired more knowledge or skills, or whether they have got lucky, chance helping them to get over the pass mark. In the UK, the issue of resits has become of particular interest since the General Medical Council issued a consultation and is considering limiting the number of attempts candidates may make at examinations. Methods Since 1999 the examination for Membership of the Royal Colleges of Physicians of the United Kingdom (MRCP(UK has imposed no limit on the number of attempts candidates can make at its Part 1, Part2 or PACES (Clinical examination. The present study examined the performance of candidates on the examinations from 2002/2003 to 2010, during which time the examination structure has been stable. Data were available for 70,856 attempts at Part 1 by 39,335 candidates, 37,654 attempts at Part 2 by 23,637 candidates and 40,303 attempts at PACES by 21,270 candidates, with the maximum number of attempts being 26, 21 and 14, respectively. The results were analyzed using multilevel modelling, fitting negative exponential growth curves to individual candidate performance. Results The number of candidates taking the assessment falls exponentially at each attempt. Performance improves across attempts, with evidence in the Part 1 examination that candidates are still improving up to the tenth attempt, with a similar improvement up to the fourth attempt in Part 2 and the sixth attempt at PACES. Random effects modelling shows that candidates begin at a starting level, with performance increasing by a smaller amount at each attempt, with evidence of a maximum, asymptotic level for

Resitting a high-stakes postgraduate medical examination on multiple occasions: nonlinear multilevel modelling of performance in the MRCP(UK) examinations.

Science.gov (United States)

McManus, I C; Ludka, Katarzyna

2012-06-14

Failure rates in postgraduate examinations are often high and many candidates therefore retake examinations on several or even many times. Little, however, is known about how candidates perform across those multiple attempts. A key theoretical question to be resolved is whether candidates pass at a resit because they have got better, having acquired more knowledge or skills, or whether they have got lucky, chance helping them to get over the pass mark. In the UK, the issue of resits has become of particular interest since the General Medical Council issued a consultation and is considering limiting the number of attempts candidates may make at examinations. Since 1999 the examination for Membership of the Royal Colleges of Physicians of the United Kingdom (MRCP(UK)) has imposed no limit on the number of attempts candidates can make at its Part 1, Part 2 or PACES (Clinical) examination. The present study examined the performance of candidates on the examinations from 2002/2003 to 2010, during which time the examination structure has been stable. Data were available for 70,856 attempts at Part 1 by 39,335 candidates, 37,654 attempts at Part 2 by 23,637 candidates and 40,303 attempts at PACES by 21,270 candidates, with the maximum number of attempts being 26, 21 and 14, respectively. The results were analyzed using multilevel modelling, fitting negative exponential growth curves to individual candidate performance. The number of candidates taking the assessment falls exponentially at each attempt. Performance improves across attempts, with evidence in the Part 1 examination that candidates are still improving up to the tenth attempt, with a similar improvement up to the fourth attempt in Part 2 and the sixth attempt at PACES. Random effects modelling shows that candidates begin at a starting level, with performance increasing by a smaller amount at each attempt, with evidence of a maximum, asymptotic level for candidates, and candidates showing variation in starting

MR cholangiography: usefulness in obstructive jaundice

International Nuclear Information System (INIS)

Bae, Sang Hoon; Lee, In Jae; Nam, Kung Sook; Hong, Myung Sun; Lee, Kyung Hwan; Yun, Ku Sub

1994-01-01

Three-dimensional(3D) magnetic resonance(MR) projection imaging was evaluated as a noninvasive alternative to direct cholangiography for the assessment of its reliability in patients with obstructive jaundice. A heavily T2-weighted gradient-echo sequence(PSIF) was used for 3D MR projection imaging of the biliary system in five healthy volunteers and 25 patients with obstructive jaundice. The 3D images of the bile ducts were formed by stacking consecutive coronal MR images obtained with a fast imaging method to a maximum-intensity projection algorithm. In the volunteers, MR cholangiography could demonstrate the anatomy of the biliary tract in only two subjects. The extrahepatic and intrahepatic bile ducts were well visualized in 23 patients with obstructive jaundice. The leve of obstruction and the grade of dilatation were depicted with MR cholangiography in all cases. And the cause of obstruction could be determined with MR cholangiography in 18 cases, MR cholangiography wa successful in two patients in whom ERCP failed. The gallbladder or dilated pancreatic duct not demonstrated by means of direct cholangiography was demonstrated with MR cholangiography in six cases. MR cholangiography may be a useful adjunctive tool for the noninvasive evaluation of patients with obstructive Jaundice

T2-weighted MR imaging of the liver: Qualitative and quantitative comparison of SPACE MR imaging with turbo spin-echo MR imaging

Energy Technology Data Exchange (ETDEWEB)

Dohan, Anthony, E-mail: anthony.dohan@lrb.aphp.fr [Department of Body and Interventional Imaging, Hôpital Lariboisière, AP-HP, 2 Rue Ambroise Paré, 75475 Paris Cedex 10 (France); Université Paris-Diderot, Sorbonne Paris Cité, 10 Rue de Verdun, 75010 Paris (France); UMR INSERM 965, Hôpital Lariboisière, 2 Rue Amboise Paré, 75010 Paris (France); Gavini, Jean-Philippe, E-mail: jpgavini@gmail.com [Department of Body and Interventional Imaging, Hôpital Lariboisière, AP-HP, 2 Rue Ambroise Paré, 75475 Paris Cedex 10 (France); Université Paris-Diderot, Sorbonne Paris Cité, 10 Rue de Verdun, 75010 Paris (France); Placé, Vinciane, E-mail: vinciane.place@gmail.com [Department of Body and Interventional Imaging, Hôpital Lariboisière, AP-HP, 2 Rue Ambroise Paré, 75475 Paris Cedex 10 (France); Sebbag, Delphine, E-mail: delphinesebbag@gmail.com [Department of Body and Interventional Imaging, Hôpital Lariboisière, AP-HP, 2 Rue Ambroise Paré, 75475 Paris Cedex 10 (France); Université Paris-Diderot, Sorbonne Paris Cité, 10 Rue de Verdun, 75010 Paris (France); Vignaud, Alexandre, E-mail: alexandre.vignaud@cea.fr [LRMN, Neurospin, CEA-SACLAY, Bâtiment 145, 91 191 Gif-sur-Yvette Cedex (France); and others

2013-11-01

Objective: To qualitatively and quantitatively compare T2-weighted MR imaging of the liver using volumetric spin-echo with sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE) with conventional turbo spin-echo (TSE) sequence for fat-suppressed T2-weighted MR imaging of the liver. Materials and methods: Thirty-three patients with suspected focal liver lesions had SPACE MR imaging and conventional fat-suppressed TSE MR imaging. Images were analyzed quantitatively by measuring the lesion-to-liver contrast-to-noise ratio (CNR), and the signal-to-noise ratio (SNR) of main focal hepatic lesions, hepatic and splenic parenchyma and qualitatively by evaluating the presence of vascular, respiratory motion and cardiac artifacts. Wilcoxon signed rank test was used to search for differences between the two sequences. Results: SPACE MR imaging showed significantly greater CNR for focal liver lesions (median = 22.82) than TSE MR imaging (median = 14.15) (P < .001). No differences were found for SNR of hepatic parenchyma (P = .097), main focal hepatic lesions (P = .35), and splenic parenchyma (P = .25). SPACE sequence showed less artifacts than TSE sequence (vascular, P < .001; respiratory motion, P < .001; cardiac, P < .001) but needed a longer acquisition time (228.4 vs. 162.1 s; P < .001). Conclusion: SPACE MR imaging provides a significantly increased CNR for focal liver lesions and less artifacts by comparison with the conventional TSE sequence. These results should stimulate further clinical studies with a surgical standard of reference to compare the two techniques in terms of sensitivity for malignant lesions.

MR imaging of the brachial plexus: comparison between 1.5-T and 3-T MR imaging: preliminary experience

Energy Technology Data Exchange (ETDEWEB)

Tagliafico, Alberto; Neumaier, Carlo Emanuele; Calabrese, Massimo [National Institute for Cancer Research, Department of Radiology, Genova (Italy); Succio, Giulia; Serafini, Giovanni; Ghidara, Matteo [Santa Corona Hospital, Radiology Department, Savona (Italy); Martinoli, Carlo [Universita di Genova, Radiology Department, Genova (Italy)

2011-06-15

To compare 1.5-T and 3-T magnetic resonance (MR) imaging of the brachial plexus. Institutional review board approval and informed consent were obtained from 30 healthy volunteers and 30 consecutive patients with brachial plexus disturbances. MR was prospectively performed with comparable sequence parameters and coils with a 1.5-T and a 3-T system. Imaging protocols at both field strengths included T1-weighted turbo spin-echo (tSE) sequences and T2-weighed turbo spin-echo (tSE) sequences with fat saturation. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) between muscle and nerve were calculated for both field strengths. The visibility of brachial plexus nerve at various anatomic levels (roots, interscalene area, costoclavicular space, and axillary level) was analyzed with a four-point grading scale by two radiologists. MR imaging diagnoses and pathological findings were also compared qualitatively. SNR and CNRs were significantly higher on 3-T MR images than on 1.5-T MR images (Friedman test) for all sequences. Nerve visibility was significantly better on 3-T MR images than on 1.5-T MR images (paired sign test). Pathological findings (n = 30/30) were seen equally well with both field strengths. MR imaging diagnoses did not differ for the 1.5- and 3-T protocols. High-quality MR images of the brachial plexus can be obtained with 3-T MR imaging by using sequences similar to those used at 1.5-T MR imaging. In patients and healthy volunteers, the visibility of nerve trunks and cords at 3-T MR imaging appears to be superior to that at 1.5-T MR imaging. (orig.)

MR imaging of the kidneys: new diagnostic strategies; MR-Bildgebung der Nieren. Neue Ansaetze in der Diagnostik

Energy Technology Data Exchange (ETDEWEB)

Schoenberg, S.O.; Knopp, M.V.; Bock, M.; Floemer, F.; Essig, M.; Hawighorst, H.; Kaick, G. van [Deutsches Krebsforschungszentrum, Heidelberg (Germany). Forschungsschwerpunkt Radiologische Diagnostik; Kallinowski, F. [Heidelberg Univ. (Germany). Chirurgische Universitaetsklinik; Just, A. [Heidelberg Univ. (Germany). 1. Physiologisches Inst.; Laub, G. [Siemens AG, Erlangen (Germany). Unternehmensbereich Medizinische Technik; Prince, M.R [Michigan Univ., Ann Arbor, MI (United States). Dept. of Radiology

1999-05-01

Aim: New diagnostic strategies for evaluation of the kidney by fast MR imaging of renal morphology, multiphase 3D gadolinium MR angiography, MR urography and MR flow measurements. A signal MR examination is designed to grade renovascular disease and assess the hemodynamic and functional significance, detect and characterize renal lesions and evaluate the urinary tract. Results: The combined analysis of morphologic and functional data allows reliable assessment of renal artery stenosis, benign and malignant renal masses and diseases of the renal collecting system and ureters, as well as congenital abnormalities in good agreement to the results of conventional imaging modalities. The improved tissue contrast and additional functional information compensates for the disadvantage of a lower spatial resolution. Conclusion: Combined morphologic and functional MR examination represents a reliable, non-invasive and cost-effective alternative imaging modality for comprehensive diagnostic evaluation of renal disease. (orig.) [Deutsch] Fragestellung: Darstellung neuer diagnostischer Moeglichkeiten im Bereich der Niere mittels schneller Magnetresonanz (MR)-Bildgebung. Methodik: Vorgestellt wird ein kombiniertes morphologisches und funktionelles Untersuchungskonzept bestehend aus schneller morphologischer Bildgebung, multiphasischer 3D-Gadolinium-MR-Angiographie, MR-Urographie und MR-Flussmessung. In einer einzigen MR-Untersuchung sollen vaskulaere Erkrankungen erfasst, eingestuft und auf ihre haemodynamische und funktionelle Signifikanz ueberprueft werden, renale Laesionen detektiert und differenziert sowie die Harnabflusswege beurteilt werden. Ergebnisse: Durch Integration der gewonnenen morphologischen und funktionellen Daten lassen sich Nierenarterienstenosen, benigne und maligne renale Tumoren, Harnabflussstoerungen und kongenitale Fehlbildungen mit aehnlicher Genauigkeit wie in den konventionellen radiologischen Verfahren erfassen. Der Nachteil der geringeren raeumlichen

MR-guided lumbar sympathicolysis

Energy Technology Data Exchange (ETDEWEB)

Koenig, Claudius W.; Schott, Ulrich G.; Pereira, Philippe L.; Truebenbach, Jochen; Claussen, Claus D.; Duda, Stephan H. [Department of Diagnostic Radiology, University of Tuebingen (Germany); Schneider, Wilke [Department of Vascular Surgery, University of Tuebingen (Germany)

2002-06-01

The aim of this study was to demonstrate the feasibility of MR-guided lumbar sympathicolysis (LSL) in a non-selected patient population. One hundred one MR-guided LSL procedures were performed in 89 patients according to Haaga's technique using a horizontally open clinical MR system (0.2 T) and non-ferromagnetic 20-G cannulas (neurolysis, n=93; blockade, n=8). Only gradient-recalled sequences in either single or multislice mode [fast imaging with steady-state precession (FISP) and fast low-angle shot] were applied for anatomical survey and needle guiding. Bupivacaine injection was monitored with MR fluoroscopically. Fluid distribution was subsequently documented in a CT scan in 65 patients. Ninety-one LSL procedures could be successfully completed. Ten patients were not treated using MR due to patient inconvenience, severe motion artifacts (n=4 each), excessive spondylophytes, and retroperitoneal hematoma (n=1 each). One case of ureteral necrosis occurred. Motion artifacts were rated less severe in single-slice FISP sequences and in obese patients. An average of 3.48 sequence measurements were required for definitive needle placement. Average table time was 32.3 min. An MR-guided LSL is feasible and can be performed with acceptable safety and time effort. It can be recommended for repeated sympathetic blockades in younger patients to avoid cumulative irradiation associated with CT guidance. (orig.)

MR-guided lumbar sympathicolysis

International Nuclear Information System (INIS)

Koenig, Claudius W.; Schott, Ulrich G.; Pereira, Philippe L.; Truebenbach, Jochen; Claussen, Claus D.; Duda, Stephan H.; Schneider, Wilke

2002-01-01

The aim of this study was to demonstrate the feasibility of MR-guided lumbar sympathicolysis (LSL) in a non-selected patient population. One hundred one MR-guided LSL procedures were performed in 89 patients according to Haaga's technique using a horizontally open clinical MR system (0.2 T) and non-ferromagnetic 20-G cannulas (neurolysis, n=93; blockade, n=8). Only gradient-recalled sequences in either single or multislice mode [fast imaging with steady-state precession (FISP) and fast low-angle shot] were applied for anatomical survey and needle guiding. Bupivacaine injection was monitored with MR fluoroscopically. Fluid distribution was subsequently documented in a CT scan in 65 patients. Ninety-one LSL procedures could be successfully completed. Ten patients were not treated using MR due to patient inconvenience, severe motion artifacts (n=4 each), excessive spondylophytes, and retroperitoneal hematoma (n=1 each). One case of ureteral necrosis occurred. Motion artifacts were rated less severe in single-slice FISP sequences and in obese patients. An average of 3.48 sequence measurements were required for definitive needle placement. Average table time was 32.3 min. An MR-guided LSL is feasible and can be performed with acceptable safety and time effort. It can be recommended for repeated sympathetic blockades in younger patients to avoid cumulative irradiation associated with CT guidance. (orig.)

Skeletal MR imaging: Correlation with skeletal scintigraphy

International Nuclear Information System (INIS)

Colletti, P.M.; Raval, J.K.; Ford, P.V.; Benson, R.C.; Kerr, R.M.; Boswell, W.D.; Siegel, M.E.; Ralls, P.W.

1987-01-01

Skeletal MR images bone marrow while skeletal scintigraphy uses bone metabolism to demonstrate abnormalities. The purpose of this paper is to correlate these MR and scintigraphic findings. T1 and T2 MR images at 0.5 T were correlated with planar bone scintigraphy (RN) using Tc-99m MDP in 56 patients. Of 23 cases with suspected spinal metastases, 19 were positive by MR imaging, 16 by RN. Individual lesions were shown better by MR imaging in five and by RN in two. These two cases had scoliosis, a potential difficulty with MR imaging. In 14 cases of suspected avascular necrosis (AVN), MR imaging was positive in 13 while RN was positive in ten. One negative case by RN had bilateral AVN by MR imaging. Four skull lesions shown easily by RN were seen only in retrospect on MR images. MR imaging is advantageous in evaluating bones with predominant marrow such as vertebrae or the femoral head, while RN is superior in areas primarily composed of cortical bone such as the skull

Intracranial MR angiography

International Nuclear Information System (INIS)

Davis, W.L.; Blatter, D.D.; Parker, D.L.; Robison, R.O.; Harnsberger, H.R.

1991-01-01

This paper compares the more traditional three-dimensional (3D) time-of-flight MR angiography with a novel new technique, MOTSA, in the evaluation of both normal and abnormal intracranial anatomy. The authors performed sequential, location-matched 3D TOF and MOTSA MR angiography in 10 subjects with normal and 25 with abnormal intracranial anatomy. Images were evaluated for visualization of specific vessels and depiction of pathologic anatomy. All images were subjected to an objective scoring system. Digital angiography was available in 15 of 25 abnormal cases. In the normal cases, large- and small-vessel visualization was improved. Significant improvement in visualization of venous anatomy was also observed. In the abnormal cases, pathologic anatomy was better visualized, providing important diagnostic information. Multiple overlapping thin-slab-acquisition MR angiography demonstrates vessel visualization that is increased over that of 3D TOF MR angiography in both normal and abnormal cases. Because of the decrease in saturation effects and phase dispersion, MOTSA is especially useful in the evaluation of complex intracranial vascular abnormalities

MR of acute subarachnoid hemorrhage

International Nuclear Information System (INIS)

Spickler, E.; Lufkin, R.; Frazee, J.; Lylyk, P.; Vinuela, F.; Bentson, J.; Dion, J.

1987-01-01

Subarachnoid hemorrhage was produced in four Macaca nemestrina monkeys using the technique of Frazee. CT and MR imaging was performed immediately after the procedure and at frequent intervals up to 2 weeks after hemorrhage. The imaging studies were compared with clinical evaluations and pathologic specimens of all animals. Additional human clinical CT/MR studies of subarachnoid hemorrhage were also studied. Acute hemorrhage was recognized on MR images as an increase in signal in the region of clot compared with surrounding cerebrospinal fluid. This most likely reflects T1 shortening due to proton binding rather than a pure paramagnetic effect. While CT is sensitive to the hemoglobin protein in acute hemorrhage, the superior resolution of MR of the basal cisterns results in equal or better definition of acute subarachnoid hemorrhage on MR studies in many cases

Magnetic Resonance (MR) Defecography

Science.gov (United States)

... to a CD or uploaded to a digital cloud server. Magnetic resonance (MR) defecography is a special ... with you. top of page What are the benefits vs. risks? Benefits MR defecography helps assess pelvic ...

MR arthrography of the shoulder: possible indications for clinical use; Einsatzmoeglichkeiten der MR-Arthrographie bei Erkrankungen des Schultergelenkes

Energy Technology Data Exchange (ETDEWEB)

Kreitner, K.F. [Mainz Univ. (Germany). Klinik mit Poliklinik fuer Radiologie; Grebe, P. [Mainz Univ. (Germany). Klinik mit Poliklinik fuer Radiologie; Kersjes, W. [Mainz Univ. (Germany). Klinik mit Poliklinik fuer Radiologie; Runkel, M. [Mainz Univ. (Germany). Klinik fuer Unfallchirurgie; Kirschner, P. [Elisabeth-Hospital, Mainz (Germany). Abt. fuer Unfall- und Wiederherstellungschirurgie St. Vincenz; Schild, H.H. [Mainz Univ. (Germany). Klinik mit Poliklinik fuer Radiologie

1994-02-01

In a prospective study possible indications for MR arthrography of the shoulder were evaluated. 37 patients were examined before and after intraarticular administration of a 2-mmolar solution of Gd-DTPA. MR arthrography was performed if there was no joint effusion and/or an uncertain finding concerning the rotator cuff or the capsulolabral complex on plain MR images. MR arthrography leads to a better demonstration of labrum pathology in 11/22 patients and to a superior delineation of the capsuloligamentous apparatus in 20/22 cases. In 9/15 patients with impingement lesions MR arthrography allowed a differentiation of severe tendinitis from partial and small full-thickness tears of the rotator cuff. MR arthrography of the shoulder joint enhances the accuracy of MR in case of an uncertain finding on plain MR images. (orig.) [Deutsch] In einer prospektiven Studie sollten Einsatzmoeglichkeiten der MR-Arthrographie bei Erkrankungen des Schultergelenkes herausgearbeitet werden. 37 Patienten wurden sowohl nativ als auch nach intraartikulaerer Gabe einer 2mmolaren Gd-DTPA-Loesung untersucht. Voraussetzungen fuer die KM-Gabe waren ein fehlender Gelenkerguss und/oder ein unklarer Befund des Labrum-Kapsel-Komplexes oder der Rotatorenmanschette in der Nativuntersuchung. Durch die MR-Arthrographie wurde bei 11/22 Patienten eine verbesserte Darstellung der Labrumpathologie erzielt; in 20/22 Faellen ergabe sich eine zuverlaessige Beurteilung der Gelenkkapsel. Bei 9/15 Patienten mit Erkrankungen der Rotatorenmanschette konnten Tendinitiden von partiellen und kleinen kompletten Rotatorenmanschettenrupturen sicher differenziert werden. Die MR-Arthrographie des Schultergelenkes fuehrt bei nicht eindeutigen Befunden in der Nativuntersuchung zu einer verbesserten Treffsicherheit der MR-Diagnostik. (orig.)

US and MR imaging of pelvic masses

International Nuclear Information System (INIS)

Angtuaco, T.L.; Boyd, C.M.; Mattison, D.R.; Williamson, M.R.; Sanders, M.M.; Bard, D.S.

1987-01-01

US and MR imaging were compared in benign and malignant pelvic masses to determine where MR imaging may replace US. With regard to benign masses, MR imaging showed a significant advantage only in the imaging of teratomas. In malignancy, US was better than MR imaging in delineating internal architecture. MR imaging was superior in suggesting the origin and extent of masses, especially in large neoplasms. US remains a reliable tool in the initial evaluation of pelvic masses. When US studies are suboptimal, MR imaging should be performed as complementary study. MR imaging may replace US in the initial examination of large masses where US cannot depict the origin and extent

Mr. Ansar Shamsi, Member Finance, Mr. Malik Adalat Khan, Director Finance, Pakistan Atomic Energy Commission

CERN Multimedia

Patrice Loïez

2003-01-01

Photo 01: Mr Ansar Shamsi, Member Finance, Pakistan Atomic Energy Commission (centre), visiting the ATLAS Tile Calorimeter in building 191 with, from left to right, Mr Syed Shaukat Hussain, Pakistan Mission in Geneva and Dr Peter Jenni, ATLAS Spokesperson. Photo 02: Mr Ansar Shamsi, Member Finance, Pakistan Atomic Energy Commission (2nd form left), visiting the ATLAS Tile Calorimeter in building 191 with, from left to right, Mr Syed Shaukat Hussain, Pakistan Mission in Geneva; Dr Peter Jenni, ATLAS Spokesperson; Dr David Jacobs and Dr Philip Bryant, Joint Pakistan-CERN Committee.

MR imaging of prostate cancer

International Nuclear Information System (INIS)

Heuck, A.; Scheidler, J.; Sommer, B.; Graser, A.; Mueller-Lisse, U.G.; Massmann, J.

2003-01-01

Accurate diagnosis and staging of prostate cancer (PC) is developing into an important health care issue in light of the high incidence of PC and the improvements in stage-adapted therapy. The purpose of this paper is to provide an overview on the current role of MR imaging and MR spectroscopy in the diagnosis and staging of PC.Material and methods Pertinent literature was searched and evaluated to collect information on current clinical indications, study techniques, diagnostic value, and limitations of magnetic resonance imaging and spectroscopy. Major indications for MR imaging of patients with supected PC are to define tumor location before biopsy when clinical or TRUS findings are inconclusive, and to provide accurate staging of histologically proven PC to ascertain effective therapy. Current MR imaging techniques for the evaluation of PC include multiplanar high-resolution T2-weighted FSE and T1-weighted SE sequences using combined endorectal and phased-array coils. Using these techniques, the reported accuracy of MR imaging for the diagnosis of extracapsular tumor extension ranges between 82 and 88% with sensitivities between 80 and 95%, and specificities between 82 and 93%. Typical MR findings of PC in different stages of disease, as well as diagnostic problems, such as chronic prostatitis, biopsy-related hemorrhage and therapy-related changes of prostatic tissue are discussed. In addition, the current perspectives and limitations of MR spectroscopy in PC are summarized. Current MR imaging techniques provide important diagnostic information in the pretherapeutic workup of PC including a high staging accuracy, and is superior to TRUS. (orig.) [de

Mr. Wolfgang Petritsch, Austrian Ambassador

CERN Multimedia

Patrice Loïez

2002-01-01

Dr.Peter Schmid/CERN/EP, Dr.Wolfgang Petritsch, Austrian Ambassador, Permanent representative at UN, Mrs.Nora Petritsch, Dr.Kurt Hubner/CERN/AC, Mrs. Frederike Klaus-Salesin, Adviser, Mrs.Andrea Strohmeier, Secretary of the Ambassador, Mr.Heinz Klaus, Attaché, Dr.Theodor Tortschanoff/CERN/LHC, Mr.Peter Storer, Advisor. Dr.Peter Schmid/CERN/EP, Dr.Wolfgang Petritsch, Austrian Ambassador, Permanent representative at UN, Mrs.Nora Petritsch, Dr.Kurt Hubner/CERN/AC, Mrs. Frederike Klaus-Salesin, Adviser, Mrs.Andrea Strohmeier, Secretary of the Ambassador, Mr.Heinz Klaus, Attaché, Dr.Theodor Tortschanoff/CERN/LHC, Mr.Peter Storer, Advisor.

Intracranial tuberculoma: MR imaging

Energy Technology Data Exchange (ETDEWEB)

Salgado, P; Zenteno, M A; Rodriguez-Carbajal, J; Brutto, O.H. del; Talamas, O

1989-09-01

MR studies of 6 patients with intracranial tuberculoma are reviewed. All patients also underwent CT scans which showed hypo- or isodense lesions with abnormal enhancement following contrast administration. MR showed lesions with prolongation of the T1 relaxation time in every case. On the T2-weighted sequences, the signal properties of the tuberculoma varied according to the stage of evolution of the lesion. Incipient tuberculomas appeared as scattered areas of hypointensity surrounded by edema. Mature tuberculomas were composed of a dark necrotic center surrounded by an isointense capsule which was, in turn, surrounded by edema. In one patient, the center of the lesion was hyperintense probably because of liquefaction and pus formation (tuberculous abscess). While both, CT and MR, were equally sensitive in visualizing the intracranial tuberculoma in every patient, MR was slightly superior in demonstrating the extent of the lesion, especially for brainstem tuberculomas. Nevertheless, the potential role for MR diagnosis of intracranial tuberculoma is limited by the fact that other infectious or neoplasic diseases may present similar findings. The diagnosis of intracranial tuberculoma should rest on a proper integration of data from clinical manifestations, cerebrospinal fluid analysis, and neuroimaging studies. (orig.).

Intracranial tuberculoma: MR imaging

International Nuclear Information System (INIS)

Salgado, P.; Zenteno, M.A.; Rodriguez-Carbajal, J.; Brutto, O.H. del; Talamas, O.

1989-01-01

MR studies of 6 patients with intracranial tuberculoma are reviewed. All patients also underwent CT scans which showed hypo- or isodense lesions with abnormal enhancement following contrast administration. MR showed lesions with prolongation of the T1 relaxation time in every case. On the T2-weighted sequences, the signal properties of the tuberculoma varied according to the stage of evolution of the lesion. Incipient tuberculomas appeared as scattered areas of hypointensity surrounded by edema. Mature tuberculomas were composed of a dark necrotic center surrounded by an isointense capsule which was, in turn, surrounded by edema. In one patient, the center of the lesion was hyperintense probably because of liquefaction and pus formation (tuberculous abscess). While both, CT and MR, were equally sensitive in visualizing the intracranial tuberculoma in every patient, MR was slightly superior in demonstrating the extent of the lesion, especially for brainstem tuberculomas. Nevertheless, the potential role for MR diagnosis of intracranial tuberculoma is limited by the fact that other infectious or neoplasic diseases may present similar findings. The diagnosis of intracranial tuberculoma should rest on a proper integration of data from clinical manifestations, cerebrospinal fluid analysis, and neuroimaging studies. (orig.)

Detection and staging of chondromalacia patellae: relative efficacies of conventional MR imaging, MR arthrography, and CT arthrography.

Science.gov (United States)

Gagliardi, J A; Chung, E M; Chandnani, V P; Kesling, K L; Christensen, K P; Null, R N; Radvany, M G; Hansen, M F

1994-09-01

Chondromalacia patellae is a condition characterized by softening, fraying, and ulceration of patellar articular cartilage. We compare the sensitivity, specificity, and accuracy of conventional MR imaging, MR arthrography, and CT arthrography in detecting and staging this abnormality. Twenty-seven patients with pain in the anterior part of the knee were prospectively examined with MR imaging, including T1-weighted (650/16), proton density-weighted (2000/20), T2-weighted (2000/80), and spoiled two-dimensional gradient-recalled acquisition in the steady state (SPGR/)/35 degrees (51/10) with fat saturation pulse sequences. All were also examined with T1-weighted MR imaging after intraarticular injection of dilute gadopentetate dimeglumine and with double-contrast CT arthrography. Each imaging technique was evaluated independently by two observers, who reached a consensus interpretation. The signal characteristics of cartilage on MR images and contour abnormalities noted with all imaging techniques were evaluated and graded according to a modification of the classification of Shahriaree. Twenty-six of the 54 facets examined had chondromalacia shown by arthroscopy, which was used as the standard of reference. The sensitivity, specificity, and accuracy of each imaging technique in the diagnosis of each stage of chondromalacia patellae were determined and compared by using the McNemar two-tailed analysis. Arthroscopy showed that 28 facets were normal. Grade 1 chondromalacia patellae was diagnosed only with MR and CT arthrography in two (29%) of seven facets. Intermediate (grade 2 or 3) chondromalacia patellae was detected in two (13%) of 15 facets with T1-weighted and SPGR MR imaging, in three (20%) of 15 facets with proton density-weighted MR imaging, in seven (47%) of 15 facets with T2-weighted MR imaging, in 11 (73%) of 15 facets with CT arthrography, and in 12 (80%) of 15 facets with MR arthrography. Grade 4 was detected in three (75%) of four facets with T1-, proton

Chondromalacia patellae: diagnosis with MR imaging.

Science.gov (United States)

McCauley, T R; Kier, R; Lynch, K J; Jokl, P

1992-01-01

Most previous studies of MR imaging for detection of chondromalacia have used T1-weighted images. We correlated findings on axial MR images of the knee with arthroscopic findings to determine MR findings of chondromalacia patellae on T2-weighted and proton density-weighted images. The study population included 52 patients who had MR examination of the knee with a 1.5-T unit and subsequent arthroscopy, which documented chondromalacia patellae in 29 patients and normal cartilage in 23. The patellar cartilage was assessed retrospectively for MR signal and contour characteristics. MR diagnosis based on the criteria of focal signal or focal contour abnormality on either the T2-weighted or proton density-weighted images yielded the highest correlation with the arthroscopic diagnosis of chondromalacia. When these criteria were used, patients with chondromalacia were detected with 86% sensitivity, 74% specificity, and 81% accuracy. MR diagnosis based on T2-weighted images alone was more sensitive and accurate than was diagnosis based on proton density-weighted images alone. In conclusion, most patients with chondromalacia patellae have focal signal or focal contour defects in the patellar cartilage on T2-weighted MR images. These findings are absent in most patients with arthroscopically normal cartilage.

MR imaging of septic sacroiliitis

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Stuerzenbecher, A.; Hamm, B.; Bollow, M. [Humboldt-Universitaet, Berlin (DD). Bereich Medizin (Charite); Braun, J. [Freie Univ. Berlin (Germany). Universitaetsklinikum Benjamin Franklin; Paris, S. [Unfallkrankenhaus Berlin (Germany). Dept. of Radiology; Biedermann, T. [Krankenhaus Berlin-Buch (Germany). II. Kinderklinik

2000-08-01

Objective. To investigate the diagnostic value of magnetic resonance (MR) imaging in detecting septic sacroiliitis and to determine whether the MR characteristics allow this entity to be differentiated from sacroiliitis in spondylarthropathy (SpA).Patients and design. The imaging findings of 11 patients with septic sacroiliitis were retrospectively analyzed by two experienced radiologists. Radiographic surveys of the pelvis as well as computed tomography (CT) and MR images of the sacroiliac joints were available in all cases. Seven of the patients additionally underwent a follow-up MR examination. The MR imaging protocol comprised combinations of coronal and transverse T1-weighted spin-echo (SE) or fast SE sequences, T2-weighted gradient-echo (GE) sequences and short tau inversion recovery sequence (STIR) sequences as well as dynamic contrast- enhanced T1-weighted acquisitions.Results. Three patients with a short disease history showed anterior and/or posterior subperiosteal infiltrations (''lava cleft phenomenon''), transcapsular infiltrations of juxta-articular muscle layers, which obscured the fasciae, and periarticular bone marrow edema. The eight patients with more advanced stages of sacroiliitis additionally showed abscess formation, sequestration, and erosion. At follow-up MR examination (n=7) under systemic antibiotic treatment, the morphologic characteristics showed progression (n=1), regression (n=4), unchanged findings (n=1), or a mixed response (n=1). Clinical improvement precedes resolution of the MR findings.Conclusions. Anterior and/or posterior subperiosteal infiltrations and transcapsular infiltrations of juxta-articular muscle layers were depicted in all patients. These MR imaging findings are characteristic of septic sacroiliitis and may be used to differentiate this entity from sacroiliitis in SpA. (orig.)

MR arthrography of the ankle joint

International Nuclear Information System (INIS)

Trattnig, S.; Rand, T.; Breitenseher, M.; Ba-Ssalamah, A.; Schick, S.; Imhof, H.

1999-01-01

Due to its superior soft tissue contrast conventional MRI is the imaging method of choice in the evaluation of ankle joint disorders. Conventional MR imaging can accurately demonstrate normal or acutely injured ligaments; however, in subacute and chronic injury joint fluid necessary for delineation of injured ligaments is absent and MR arthrography should be performed. MR arthrography uses the intraarticular injection of contrast material to distend the joint, yielding improved discrimination of intraarticular structures. This joint distension with MR arthrography is also helpful in the staging of osteochondritis dissecans, since in cases of unstable lesions tracking of contrast material into the interface can be more easily demonstrated. Finally, high contrast and joint distension by MR arthrography improves the detection of intraarticular loose bodies, which often require surgery. MR artrography, although invasive, may provide additional information in various ankle joint disorders. (orig.) [de

Santorinicele: secretin-enhanced magnetic resonance cholangiopancreatography findings before and after minor papilla sphincterotomy

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Boninsegna, Enrico; Manfredi, Riccardo; Ventriglia, Anna; Negrelli, Riccardo; Pedrinolla, Beatrice; Mehrabi, Sara; Pozzi Mucelli, Roberto [University of Verona, Department of Radiology - Policlinico G.B. Rossi, Verona (Italy); Gabbrielli, Armando [University of Verona, Department of Medicine - Policlinico G.B. Rossi, Verona (Italy)

2015-08-15

To evaluate secretin-enhanced MRCP (S-MRCP) findings of patients with pancreas divisum and Santorinicele, before and after minor papilla sphincterotomy. S-MRCP examinations of 519 patients with suspected pancreatic disease were included. Size of the main pancreatic duct, presence and calibre of Santorinicele were evaluated. Duodenal filling was assessed on dynamic images. After sphincterotomy the same parameters and the clinical findings were re-evaluated. Pancreas divisum was depicted in 55/519 patients (11 %) by MRCP and an additional 26/519 by S-MRCP (total 81/519, 16 %). Santorinicele was detected in 7/81 patients (8.6 %) with pancreas divisum by MRCP and an additional 20/81 by S-MRCP (total 27/81, 33 %). Dorsal duct in patients with Santorinicele was significantly larger in the head compared with patients with only pancreas divisum (p < 0.01), in basal conditions (average 2.4 versus 1.9 mm) and after secretin administration (average 3.0 versus 2.4 mm). Duodenal filling was impaired in 11/27 patients (41 %) with Santorinicele. After sphincterotomy significant reduction in size of Santorinicele (-33 %) and dorsal duct (-17 %), increase of pancreatic juice and symptoms improvement were observed. Secretin administration increases the accuracy of MRCP in detecting Santorinicele and demonstrates the impaired duodenal filling. S-MRCP is useful to assess results of sphincterotomy. (orig.)

Inpatient magnetic resonance cholangiopancreatography: does it increase the efficiency in emergency hepatopancreaticobiliary surgery services?

Science.gov (United States)

Milburn, J A; Bailey, J A; Dunn, Wk; Cameron, I C; Gomez, D S

2017-04-01

INTRODUCTION Magnetic resonance cholangiopancreatography (MRCP) is commonly used to evaluate the biliary tree, although indications for patients who require inpatient imaging are not fully defined. The aim of this study was to evaluate inpatient MRCP performed on surgical patients and to devise a treatment pathway for these patients. MATERIAL AND METHODS All adult inpatient MRCP examinations between January 2012 and December 2013 were reviewed. Demographic, clinical and radiological data were collated. RESULTS During the study period, 271 inpatient MRCP were requested, of which 234 examinations were included. The majority of patients were female (n=140) and the median age was 63 years (range 16-93 years). Surgical admissions accounted for 171 (73%) of cases. Indications for inpatient MRCP include gallstone-related complications (n=173; 74%), malignant process (n=17; 7%) and other indications (n=44; 19%). Overall, inpatient MRCP led to further inpatient interventions in 22% (gallstone group, n=32, 18%; patients with malignancy, n=8, 47%; other indications, n=12, 27%). The median duration of inpatient MRCP from request to examination was 2 days (range 0-15 days) and median reporting after examination was 1 day (range 0-14 days). DISCUSSION AND CONCLUSION Improved access and timely reporting of iMRCP may reduce length of hospital stay. Inpatient MRCP also led to further inpatient interventions, in particular, in patients with malignancy.

MR arthrography of the knee

International Nuclear Information System (INIS)

Kramer, J. Jr.; Engel, A. Jr.; Stiglbauer, R.; Prayer, L. Jr.; Hajek, P. Jr.; Imhof, H.

1991-01-01

This paper reports on MR imaging which has gained increasing importance as a diagnostic instrument in orthopedics. The key to joint diagnostics - the evaluation of hyaline articular cartilage - however, has not been touched sufficiently by this development. Fundamental studies were done and 140 patients were examined with MR imaging after intraarticular administration of contrast agent. Hyaline cartilage, cruciate ligaments, and menisci were assessed before and after injection of a 2-mmol/L Gd-DTPA solution, and the results were compared with those of arthroscopy/arthrotomy. MR arthrography provided superior image quality compared with plain MR imaging. This resulted in an improved delineation of intraarticular structures, especially of cartilage defects

Simultaneous PET/MR imaging in a human brain PET/MR system in 50 patients—Current state of image quality

International Nuclear Information System (INIS)

Schwenzer, N.F.; Stegger, L.; Bisdas, S.; Schraml, C.; Kolb, A.; Boss, A.; Müller, M.

2012-01-01

Objectives: The present work illustrates the current state of image quality and diagnostic accuracy in a new hybrid BrainPET/MR. Materials and methods: 50 patients with intracranial masses, head and upper neck tumors or neurodegenerative diseases were examined with a hybrid BrainPET/MR consisting of a conventional 3T MR system and an MR-compatible PET insert. Directly before PET/MR, all patients underwent a PET/CT examination with either [ 18 F]-FDG, [ 11 C]-methionine or [ 68 Ga]-DOTATOC. In addition to anatomical MR scans, functional sequences were performed including diffusion tensor imaging (DTI), arterial spin labeling (ASL) and proton-spectroscopy. Image quality score of MR imaging was evaluated using a 4-point-scale. PET data quality was assessed by evaluating FDG-uptake and tumor delineation with [ 11 C]-methionine and [ 68 Ga]-DOTATOC. FDG uptake quantification accuracy was evaluated by means of ROI analysis (right and left frontal and temporo-occipital lobes). The asymmetry indices and ratios between frontal and occipital ROIs were compared. Results: In 45/50 patients, PET/MR examination was successful. Visual analysis revealed a diagnostic image quality of anatomical MR imaging (mean quality score T2 FSE: 1.27 ± 0.54; FLAIR: 1.38 ± 0.61). ASL and proton-spectroscopy was possible in all cases. In DTI, dental artifacts lead to one non-diagnostic dataset (mean quality score DTI: 1.32 ± 0.69; ASL: 1.10 ± 0.31). PET datasets of PET/MR and PET/CT offered comparable tumor delineation with [ 11 C]-methionine; additional lesions were found in 2/8 [ 68 Ga]-DOTATOC-PET in the PET/MR. Mean asymmetry index revealed a high accordance between PET/MR and PET/CT (1.5 ± 2.2% vs. 0.9 ± 3.6%; mean ratio (frontal/parieto-occipital) 0.93 ± 0.08 vs. 0.96 ± 0.05), respectively. Conclusions: The hybrid BrainPET/MR allows for molecular, anatomical and functional imaging with uncompromised MR image quality and a high accordance of PET results between PET/MR and PET

Simultaneous PET/MR imaging in a human brain PET/MR system in 50 patients-Current state of image quality

Energy Technology Data Exchange (ETDEWEB)

Schwenzer, N.F., E-mail: nina.schwenzer@med.uni-tuebingen.de [Department of Diagnostic and Interventional Radiology, Eberhard-Karls University Tuebingen, Tuebingen (Germany); Stegger, L., E-mail: stegger@gmx.net [Department of Nuclear Medicine and European Institute for Molecular Imaging, University of Muenster, Muenster (Germany); Bisdas, S., E-mail: sbisdas@gmail.com [Department of Diagnostic and Interventional Neuroradiology, Eberhard-Karls University Tuebingen, Tuebingen (Germany); Schraml, C., E-mail: christina.schraml@med.uni-tuebingen.de [Department of Diagnostic and Interventional Radiology, Eberhard-Karls University Tuebingen, Tuebingen (Germany); Kolb, A., E-mail: armin.kolb@med.uni-tuebingen.de [Laboratory for Preclinical Imaging and Imaging Technology of the Werner Siemens-Foundation, Department of Preclinical Imaging and Radiopharmacy, Eberhard-Karls University Tuebingen, Tuebingen (Germany); Boss, A., E-mail: Andreas.Boss@usz.ch [Department of Diagnostic and Interventional Radiology, Eberhard-Karls University Tuebingen, Tuebingen (Germany); Institute of Diagnostic and Interventional Radiology, University Hospital Zuerich, Zuerich (Switzerland); Mueller, M., E-mail: mark.mueller@med.uni-tuebingen.de [Department of Nuclear Medicine, Eberhard-Karls University Tuebingen, Tuebingen (Germany); and others

2012-11-15

Objectives: The present work illustrates the current state of image quality and diagnostic accuracy in a new hybrid BrainPET/MR. Materials and methods: 50 patients with intracranial masses, head and upper neck tumors or neurodegenerative diseases were examined with a hybrid BrainPET/MR consisting of a conventional 3T MR system and an MR-compatible PET insert. Directly before PET/MR, all patients underwent a PET/CT examination with either [{sup 18}F]-FDG, [{sup 11}C]-methionine or [{sup 68}Ga]-DOTATOC. In addition to anatomical MR scans, functional sequences were performed including diffusion tensor imaging (DTI), arterial spin labeling (ASL) and proton-spectroscopy. Image quality score of MR imaging was evaluated using a 4-point-scale. PET data quality was assessed by evaluating FDG-uptake and tumor delineation with [{sup 11}C]-methionine and [{sup 68}Ga]-DOTATOC. FDG uptake quantification accuracy was evaluated by means of ROI analysis (right and left frontal and temporo-occipital lobes). The asymmetry indices and ratios between frontal and occipital ROIs were compared. Results: In 45/50 patients, PET/MR examination was successful. Visual analysis revealed a diagnostic image quality of anatomical MR imaging (mean quality score T2 FSE: 1.27 {+-} 0.54; FLAIR: 1.38 {+-} 0.61). ASL and proton-spectroscopy was possible in all cases. In DTI, dental artifacts lead to one non-diagnostic dataset (mean quality score DTI: 1.32 {+-} 0.69; ASL: 1.10 {+-} 0.31). PET datasets of PET/MR and PET/CT offered comparable tumor delineation with [{sup 11}C]-methionine; additional lesions were found in 2/8 [{sup 68}Ga]-DOTATOC-PET in the PET/MR. Mean asymmetry index revealed a high accordance between PET/MR and PET/CT (1.5 {+-} 2.2% vs. 0.9 {+-} 3.6%; mean ratio (frontal/parieto-occipital) 0.93 {+-} 0.08 vs. 0.96 {+-} 0.05), respectively. Conclusions: The hybrid BrainPET/MR allows for molecular, anatomical and functional imaging with uncompromised MR image quality and a high accordance

MR investigation of recurrent cholesteatomas

Energy Technology Data Exchange (ETDEWEB)

Doyon, D.; Chan, K.Y.; Attia, M.; Halimi, P.; Sigal, R.; Bobin, S.; Sterkers, J.M.

1989-03-01

Nine cases of recurrent petrous cholesteatomas have been studied by a 1.5 T MR unit. Gadolinium was injected in 1 case. In all cases, comparison between MR, CT and clinical findings were made. MR allows for accurate topographic study and assessment of cholesteatomas extension, in particular in the posterior fossa and skull base. Relationships with the internal carotid artery and the jugular vein are clearly depicted.

MR imaging of heterotopic gray matter; Heterotopia istoty szarej mozgu w obrazie MR

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Kryst-Widzgowska, T.; Kozlowski, P.; Poniatowska, R. [Instytut Psychiatrii i Neurologii, Warsaw (Poland)

1994-12-31

Six patients with heterotopic gray matter were evaluated with MR. 5 patients had history of seizures. 4 cases were suspected of the cerebral tumor. In the MR examination areas of heterotopic gray matter were found along the posterior horn of the lateral ventricle on the one side in 4 cases and bilateraly in 2 cases. In 3 cases another brain abnormalities were also detected including: hypoplasia of corpus callosum, hypoplasia of brain hemisphere, cavum septi pellucidi. MR is a modality of choice in the assessment of abnormal gray matter migration. (author). 6 refs, 4 figs.

Imaging of the normal and abnormal pancreaticobiliary system with single-shot MR cholangiopancreatography: a pictorial review

International Nuclear Information System (INIS)

Little, A. F.; Smith, P.J.; Lee, W.K.; Hennessy, O.F.; Lourensz, M.E.; Desmond, P.V.; Banting, S.W.

1999-01-01

Magnetic resonance cholangiopancreatography (MRCP) is a rapidly evolving non-invasive imaging modality that produces images of the pancreatic duct and binary tree without the need for intravenous or oral contrast. The images are equivalent to those from endoscopic retrograde cholangiopancreatography (ERCP), but the non-invasive acquisition avoids the morbidity and mortality associated with diagnostic ERCP. Magnetic resonance cholangiopancreatography is indicated in patients who require only a diagnostic ERCP, who fail an ERCP or who are unable to undergo ERCP due to altered post-surgical anatomy. Other evolving indications include triaging of patients with obstructive jaundice into percutaneous or endoscopic management drainage pathways depending on the site, length and nature of the duct obstruction, thereby potentially decreasing the number of failed or unsuccessful ERCP. Preoperative identification of anomalous binary anatomy and choledocholithiasis prior to laparoscopic cholecystectomy promise to modify the pre-operative and operative management of the patient in order to minimize the risk of duct injury and unnecessary intra-operative dissection and cholangiography. The advantages of the technique include its non-invasiveness, the absence of contrast administration, its relative operator independence and the ability to evaluate both sides of an obstructed duct, thereby accurately evaluating stricture morphology and length. The disadvantages of MRCP compared to ERCP include its lack of an immediate therapeutic solution to duct obstruction, procedural cost, unit availability and the inability to evaluate patients with pacemakers or ferromagnetic implants. Copyright (1999) Blackwell Science Pty Ltd

Cholangiopancreatography for magnetic resonance (CPRM), using T2 - TSE technique and reconstructions 3D - Experience with 38 patients

International Nuclear Information System (INIS)

Esguerra Espinosa, Monica

1997-01-01

Magnetic resonance cholangiopancreatography (MRCP) is a non-invasive diagnostic method for the study of the biliary system that does not require contrast media or exposure to ionising radiation. Thirty-eight patients were studied; five apparently healthy ones only with MRCP; and 33 with possible biliary tract pathology, most of which had both endoscopes retrograde cholangiopancreatogaphy (ERCP) and MRCP: All MRCP's were performed with a 3D - TSE sequence with T2 - weighting, using coronal thin contiguous slices and reconstructions with maximal intensity projections (MIP) on different planes. MRCP allows an excellent anatomic depiction of the biliary tree and pancreatic duct

Serial MR imaging and 1H-MR spectroscopy in monozygotic twins with Tay-Sachs disease.

Science.gov (United States)

Imamura, A; Miyajima, H; Ito, R; Orii, K O

2008-10-01

Four-year-old monozygotic female twins with early onset Tay-Sachs disease are described. The sisters showed similar slowly progressive clinical symptoms and deterioration, however the younger sister also demonstrated intractable myoclonus in the right leg. The serial MR images and (1)H-MR spectroscopy of the brain were obtained in both twins. MR images showed high intensity on T (2)-weighted image in the bilateral white matter, however there were no signal changes in the basal ganglia and thalamus during any of the phases. The ratio of N-acetylaspartate (NAA)/creatine (Cr) was decreased in the both white matter lesions and the corpus striatum, and that of myoinositol (mI)/Cr was increased in the damaged white matter on MR spectroscopy. The elevation of the lactate peak was clearly demonstrated in the left basal ganglia of the younger sister; however it was not shown in cerebral lesions of the elder sister. Changes in metabolites on MR spectroscopy were closely linked to the respective clinical features of each twin. Follow-up examination by (1)H-MR spectroscopy is useful for the evaluation of neuronal changes in children with Tay-Sachs disease.

Classification of bones from MR images in torso PET-MR imaging using a statistical shape model

International Nuclear Information System (INIS)

Reza Ay, Mohammad; Akbarzadeh, Afshin; Ahmadian, Alireza; Zaidi, Habib

2014-01-01

There have been exclusive features for hybrid PET/MRI systems in comparison with its PET/CT counterpart in terms of reduction of radiation exposure, improved soft-tissue contrast and truly simultaneous and multi-parametric imaging capabilities. However, quantitative imaging on PET/MR is challenged by attenuation of annihilation photons through their pathway. The correction for photon attenuation requires the availability of patient-specific attenuation map, which accounts for the spatial distribution of attenuation coefficients of biological tissues. However, the lack of information on electron density in the MR signal poses an inherent difficulty to the derivation of the attenuation map from MR images. In other words, the MR signal correlates with proton densities and tissue relaxation properties, rather than with electron density and, as such, it is not directly related to attenuation coefficients. In order to derive the attenuation map from MR images at 511 keV, various strategies have been proposed and implemented on prototype and commercial PET/MR systems. Segmentation-based methods generate an attenuation map by classification of T1-weighted or high resolution Dixon MR sequences followed by assignment of predefined attenuation coefficients to various tissue types. Intensity-based segmentation approaches fail to include bones in the attenuation map since the segmentation of bones from conventional MR sequences is a difficult task. Most MR-guided attenuation correction techniques ignore bones owing to the inherent difficulties associated with bone segmentation unless specialized MR sequences such as ultra-short echo (UTE) sequence are utilized. In this work, we introduce a new technique based on statistical shape modeling to segment bones and generate a four-class attenuation map. Our segmentation approach requires a torso bone shape model based on principle component analysis (PCA). A CT-based training set including clearly segmented bones of the torso region

Breast cancer staging with MR imaging

International Nuclear Information System (INIS)

Smathers, R.L.; D'Amelio, F.; Stockdale, F.

1989-01-01

Forty-three patients with biopsy-proved breast cancer underwent MR staging of the cervicothoracic spine, lumbosacral spine, liver, and thorax. In all cases, these findings have been compared with the results of clinical staging, laboratory tests, chest radiography, and radionuclide bone scanning. MR imaging was a valuable staging tool for patients with more than minimal breast cancer and indications for radionuclide bone scanning. MR imaging had the greatest clinical importance when it identified thoracic soft-tissue abnormalities, including axillary., lateral thoracic, supraclavicular, and mediastinal lymphadenopathy. The coronal and sagittal views were very valuable for detection of chest wall invasion, sternal involvement, and internal mammary adenopathy. Negative MR staging clinically reassured patients that aggressive local therapy bad curative potential. Positive MR staging avoided inappropriate aggressive local therapy and mastectomy. MR imaging can be recommended for improved breast cancer staging in patients with newly diagnosed breast cancer who have more than minimal disease

Clinical stage T1c prostate cancer: evaluation with endorectal MR imaging and MR spectroscopic imaging.

Science.gov (United States)

Zhang, Jingbo; Hricak, Hedvig; Shukla-Dave, Amita; Akin, Oguz; Ishill, Nicole M; Carlino, Lauren J; Reuter, Victor E; Eastham, James A

2009-11-01

To assess the diagnostic accuracy of endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging for prediction of the pathologic stage of prostate cancer and the presence of clinically nonimportant disease in patients with clinical stage T1c prostate cancer. The institutional review board approved-and waived the informed patient consent requirement for-this HIPAA-compliant study involving 158 patients (median age, 58 years; age range, 40-76 years) who had clinical stage T1c prostate cancer, had not been treated preoperatively, and underwent combined 1.5-T endorectal MR imaging-MR spectroscopic imaging between January 2003 and March 2004 before undergoing radical prostatectomy. On the MR images and combined endorectal MR-MR spectroscopic images, two radiologists retrospectively and independently rated the likelihood of cancer in 12 prostate regions and the likelihoods of extracapsular extension (ECE), seminal vesicle invasion (SVI), and adjacent organ invasion by using a five-point scale, and they determined the probability of clinically nonimportant prostate cancer by using a four-point scale. Whole-mount step-section pathology maps were used for imaging-pathologic analysis correlation. Receiver operating characteristic curves were constructed and areas under the curves (AUCs) were estimated nonparametrically for assessment of reader accuracy. At surgical-pathologic analysis, one (0.6%) patient had no cancer; 124 (78%) patients, organ-confined (stage pT2) disease; 29 (18%) patients, ECE (stage pT3a); two (1%) patients, SVI (stage pT3b); and two (1%) patients, bladder neck invasion (stage pT4). Forty-six (29%) patients had a total tumor volume of less than 0.5 cm(3). With combined MR imaging-MR spectroscopic imaging, the two readers achieved 80% accuracy in disease staging and AUCs of 0.62 and 0.71 for the prediction of clinically nonimportant cancer. Clinical stage T1c prostate cancers are heterogeneous in pathologic stage and volume. MR imaging may

Rickets on MR images

International Nuclear Information System (INIS)

Ecklund, K.; Jaramillo, D.; Doria, A.S.

1999-01-01

Background. The pathologic changes at the physis in patients with rickets have been well demonstrated histologically. Radiographs can depict only the associated osseous abnormalities. Patients and methods. We report two children in whom MR imaging demonstrated rachitic changes in the physeal cartilage beyond the well-recognized bony features. Results. The striking appearance of the physes and the physes of the secondary ossification centers confirm that MR imaging can successfully evaluate the cartilaginous structures of the developing skeleton. Conclusion. Though MR imaging is clearly unnecessary for the diagnosis of rickets, it is important that the typical features are not misinterpreted as other pathology. (orig.)

PET/MR in oncology

DEFF Research Database (Denmark)

Balyasnikova, Svetlana; Löfgren, Johan; de Nijs, Robin

2012-01-01

of the challenges inherent in this new technology, but focus on potential applications for simultaneous PET/MR in the field of oncology. Methods and tracers for use with the PET technology will be familiar to most readers of this journal; thus this paper aims to provide a short and basic introduction to a number...... be applied together with PET increasing the amount of information about the tissues of interest. The potential clinical benefit of applying PET/MR in staging, radiotherapy planning and treatment evaluation in oncology, as well as the research perspectives for the use of PET/MR in the development of new...

MR investigation of recurrent cholesteatomas

International Nuclear Information System (INIS)

Doyon, D.; Chan, K.Y.; Attia, M.; Halimi, P.; Sigal, R.; Bobin, S.; Sterkers, J.M.

1989-01-01

Nine cases of recurrent petrous cholesteatomas have been studied by a 1.5 T MR unit. Gadolinium was injected in 1 case. In all cases, comparison between MR, CT and clinical findings were made. MR allows for accurate topographic study and assessment of cholesteatomas extension, in particular in the posterior fossa and skull base. Relationships with the internal carotid artery and the jugular vein are clearly depicted [fr

MR imaging of pituitary dwarfism

International Nuclear Information System (INIS)

Kashimada, Akio; Machida, Kikuo; Honda, Norinari; Mamiya, Toshio; Takahashi, Taku; Kamano, Tsuyoshi; Muramatsu, Masayuki; Inoue, Yusuke

1993-01-01

Pituitary MR imaging was performed in 32 patients with clinically diagnosed pituitary dwarfism and 12 normal controls. The patients were divided into two groups according to the severity of pituitary dwarfism based on endocrinological data. The two patients with severe dwarfism showed transection of the pituitary stalk, ectopic posterior lobe and atrophy of the anterior lobe on MR imaging, while the 27 patients with mild dwarfism showed no abnormal MR findings of the pituitary gland. The former group corresponds to typical pituitary dwarfism and the latter to partial GH deficiency, which was recently proposed as another type of pituitary dwarfism. In conclusion, pituitary MR imaging may differentiate partial GH deficiency from typical (stalk-transected) pituitary dwarfism. (author)

MR imaging of pituitary dwarfism

Energy Technology Data Exchange (ETDEWEB)

Kashimada, Akio; Machida, Kikuo; Honda, Norinari; Mamiya, Toshio; Takahashi, Taku; Kamano, Tsuyoshi; Muramatsu, Masayuki; Inoue, Yusuke (Saitama Medical School, Kawagoe (Japan). Medical Center)

1993-02-01

Pituitary MR imaging was performed in 32 patients with clinically diagnosed pituitary dwarfism and 12 normal controls. The patients were divided into two groups according to the severity of pituitary dwarfism based on endocrinological data. The two patients with severe dwarfism showed transection of the pituitary stalk, ectopic posterior lobe and atrophy of the anterior lobe on MR imaging, while the 27 patients with mild dwarfism showed no abnormal MR findings of the pituitary gland. The former group corresponds to typical pituitary dwarfism and the latter to partial GH deficiency, which was recently proposed as another type of pituitary dwarfism. In conclusion, pituitary MR imaging may differentiate partial GH deficiency from typical (stalk-transected) pituitary dwarfism. (author).

MR imaging of breast implants.

Science.gov (United States)

Gorczyca, D P

1994-11-01

MR imaging has proved to be an excellent imaging modality in locating free silicone and evaluating an implant for rupture, with a sensitivity of approximately 94% and specificity of 97%. Silicone has a unique MR resonance frequency and long T1 and T2 relaxation times, which allows several MR sequences to provide excellent diagnostic images. The most commonly used sequences include T2-weighted, STIR, and chemical shift imaging (Figs. 3, 13, and 14). The T2-weighted and STIR sequences are often used in conjunction with chemical water suppression. The most reliable findings on MR images for detection of implant rupture include identification of the collapsed implant shell (linguine sign) and free silicone within the breast parenchyma.

Whole heart cine MR imaging of pulmonary veins in patients with congenital heart disease. Comparison with Spin Echo MR imaging

International Nuclear Information System (INIS)

Mitsui, Hideaki; Saito, Haruo; Ishibashi, Tadashi; Takahashi, Shoki; Zuguchi, Masayuki; Yamada, Shogo

2002-01-01

We evaluated the accuracy of Whole Heart Cine (WHC) magnetic resonance (MR) imaging in the depiction of pulmonary veins (PVs) in patients with congenital heart disease (CHD) compared to that of spin echo (SE) MR imaging. Among our 35 patients, 4 patients had anomalous PV return. Detectability of four PVs on each MR examination images were evaluated. MR imaging is an effective modality for the clarification of PVs, and WHC MR imaging is more useful in delineating PV anomalies than SE MR imaging. (author)

MR and CT for malignant hypernephromas

International Nuclear Information System (INIS)

Uhlenbrock, D.; Fischer, C.; Ruehl, G.; Beyer, H.K.; Hummelsheim, P.; Bochum Univ.; Marienhospital, Herne; Bochum Univ.

1987-01-01

Forty patients with histologically confirmed hypernephromas were examined by MR and CT. As regards T-staging, MR had an accuracy of 97 % and CT of 91%; for N-staging, MR had an accuracy of 85% and CT of 91% and, with regard to infiltration of the renal vein, MR was correct in 88% of cases and CT in 81%. MR was most accurate in the pre-operative assessment of tumour spread, demonstrating caval involvement in 100% and lymph node metastases in 97%. On the other hand, infiltration of the renal pelvis could be assessed in only 65% of cases; in 27% the assessment was not possible and in 8% one could not be certain. CT proved to be at its best for staging of lymph nodes, but in 15% it was not possible to identify infiltration of the renal vein. MR was not greatly superior to CT in the preoperative diagnosis and staging of hypernephromas. (orig.) [de

Fast high-resolution MR imaging using the snapshot-FLASH MR sequence

International Nuclear Information System (INIS)

Matthaei, D.; Haase, A.; Henrich, D.; Duhmke, E.

1990-01-01

Snapshot, fast low-angle short (FLASH) MR imaging using an accelerated FLASH-MR sequence provides MR images with measuring times far below 1 second. The short TE of this sequence prevents susceptibility artifacts in gradient-echo imaging. In this paper variations of the sequence are shown that provide high resolution images with T1-weighted IR, T2-weighted SE, and chemical shift (CHESS) contrast sequences. METHODS AND MATERIALS: A whole-body 2-T system (Bruker-Medizintechnik) were used in combination with a 60-cm gradient system (providing gradient strength of 5 mT/m) to study healthy volunteers. The measuring time for a 256 x 256 image matrix was 800 msec. This sequence has been used in combination with T1-weighted IR, T2-weighted SE, and CHESS variations

MR-guided direct arthrography of the glenohumeral joint

International Nuclear Information System (INIS)

Soh, E.; Bearcroft, P.W.P.; Graves, M.J.; Black, R.; Lomas, D.J.

2008-01-01

Aim: To evaluate the feasibility of magnetic resonance (MR)-guided direct arthrography of the glenohumeral joint with a 1.5 T MR system, performing the entire procedure in a single MR examination. Materials and methods: MR-guided direct arthrography was performed on 11 patients. MR imaging guidance and interactive MR fluoroscopy, with in-room control and display system, were used for needle placement and contrast medium injection. The outcome measures were success or failure of joint puncture, the time taken for introduction of contrast medium, and the diagnostic quality of the subsequent MR arthrography images. Results: Contrast medium was successfully instilled into the joint and diagnostic quality MR arthrography images were obtained in all cases. The median time from initial placement of the skin marker to introduction of the contrast medium was 17 min (range 11-29 min). There were no immediate post-procedure complications. Conclusion: Accurate needle placement is feasible in a single MR examination on a commercial 1.5 T closed-bore MR system, using an in-room control and display system together with interactive fluoroscopic imaging, and this was used to provide direct MR arthrography in this study

Postictal MR-changes. A rare and important differential diagnosis; Postiktale MR-Veraenderungen. Eine seltene und wichtige Differenzialdiagnose

Energy Technology Data Exchange (ETDEWEB)

Hattingen, E.; Raab, P.; Lanfermann, H.; Zanella, F.E.; Weidauer, S. [Johann-Wolfgang-Goethe-Universitaet Frankfurt/Main, Institut fuer Neuroradiologie, Frankfurt (Germany)

2008-11-15

Postictal MR findings are analyzed in the context of MR morphological differential diagnoses. Postictal MRI was performed in 11 patients. The patterns of MR changes and their differential diagnoses were analyzed. Focal accentuation of signal increase in the cortex was found on T2-weighted images in 90% of these cases, pial enhancement in 70% and signal changes of the pulvinar/thalamus in 40%. The most common differential diagnoses were encephalitis, and in tumor patients carcinomatous involvement of the meninges. Postictal MR changes vary widely and are difficult to differentiate from illnesses such as encephalitis and carcinomatosis involving the meninges. Nevertheless, knowledge of the typical pattern of postictal MR findings and the clinical course may help to avoid mistaken diagnoses. (orig.) [German] Postiktale MR-Veraenderungen werden im Kontext ihrer Differenzialdiagnosen analysiert. Elf Patienten wurden postiktal im MRT untersucht. Ausgewertet wurden die MR-tomographischen Befundmuster und ihre Differenzialdiagnosen. Bei 90% der Patienten fanden sich fokale kortikal betonte Signalsteigerungen in der T2-Wichtung, bei 90% Diffusionseinschraenkungen, bei 70% piale Anreicherungen und bei 40% Signalalterationen des Pulvinars/Thalamus. Haeufigste Differenzialdiagnosen waren die Enzephalitis und bei entsprechender Tumoranamnese die Meningeosis carcinomatosa. Postiktale MR-Veraenderungen sind vielgestaltig und nicht immer leicht von Erkrankungen wie insbesondere der Enzephalitis oder der Meningeosis carcinomatosa zu unterscheiden. Dennoch helfen die Kenntnis typischer postiktaler Befallsmuster und der klinische Verlauf, Fehldiagnosen zu vermeiden. (orig.)

A comparative study of MR imaging scores and MR perfusion imaging in pre-operative grading of intracranial gliomas

International Nuclear Information System (INIS)

Wu Honglin; Chen Junkun; Zhang Zongjun; Lu Guangming; Chen Ziqian; Wang Wei; Ji Xueman; Tang Xiaojun; Li Lin

2005-01-01

Objective: To compare the accuracy of MR imaging scores with MR perfusion imaging in pre-operative grading of intracranial gliomas. Methods: Thirty patients with intracranial gliomas (8 low-grade and 22 high-grade, according to WHO criteria) were examined with MR perfusion imaging pre-operatively. The lesions were evaluated by using an MR imaging score based on nine criteria. rCBV of the lesions were calculated by comparing the CBV of the lesion and that of contralateral normal white matter. The scores and ratios in high-grade and low-grade tumours were compared. Results: The MR imaging score of low grade (grades I and II) gliomas (0.67±0.29) were significantly lower than that of grades III (1.32 ± 0.47) (t=-3.48, P=0.003) and IV (1.56 ± 0.20) (t=-7.36, P=0.000) gliomas. There was no statistical difference when MR imaging scores of grades III and IV gliomas (t=-1.39, P=0.182) were compared. The maximum rCBV ratio of low grade (grades I and II) gliomas (2.38 ± 0.66 ) were significantly lower than that of grades III (5.81 ± 3.20) (t=-3.57, P=0.003) and IV (6.99 ± 2.47) (t=-5.09, P=0.001). There was no statistical difference when rCBV ratios of grades III and IV (t =-0.93, P=0.365) gliomas were compared. The accuracy of MR imaging scores in the noninvasive grading of untreated gliomas was all most the same as that of MR perfusion imaging (90.00% vs 89.29%). Conclusion: The MR imaging scores and MR perfusion imaging are two very useful tools in the evaluation of the histopathologic grade of cerebral gliomas. The overall accuracy in the noninvasive grading of gliomas may be imp roved if MR imaging scores and MR perfusion imaging are combined. (authors)

MR imaging of persistent primitive trigeminal artery

International Nuclear Information System (INIS)

Ashikaga, Ryuichiro; Araki, Yutaka; Ono, Yukihiko; Ishida, Osamu; Mabuchi, Nobuhisa.

1997-01-01

The persistent trigeminal artery is the most common anomaly of the primitive carotid-vertebrobasilar anastomoses. We reviewed MR images and MR angiographies of 11 patients with primitive trigeminal artery. In 8 of the 11 cases, PTA were identified with conventional long TR spin-echo images. In 8 of 11 cases, a hypoplastic basilar trunk associated with PTA was seen on both MR images and MR angiographies. In 7 of 11 cases, a hypoplasia or agenesis of the ipsilateral posterior communicating artery was seen on MR angiographies. (author)

77 FR 65545 - Mr. Jesse S. Capel and Mr. Hilton J. Cochran; EWP LLC; Notice of Transfer of Exemption

Science.gov (United States)

2012-10-29

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 4815-009] Mr. Jesse S. Capel and Mr. Hilton J. Cochran; EWP LLC; Notice of Transfer of Exemption 1. By application filed on July 30, 2012 and supplemented on August 14, 2012, Mr. Jesse S. Capel and Mr. Hilton J. Cochran and EWP...

Molecular MR Imaging Probes

OpenAIRE

MAHMOOD, UMAR; JOSEPHSON, LEE

2005-01-01

Magnetic resonance imaging (MRI) has been successfully applied to many of the applications of molecular imaging. This review discusses by example some of the advances in areas such as multimodality MR-optical agents, receptor imaging, apoptosis imaging, angiogenesis imaging, noninvasive cell tracking, and imaging of MR marker genes.

Gadolinium-enhanced T{sub 1}-weighted MR urography versus T{sub 2}-weighted (HASTE) MR urography in children; Kontrastangehobene T{sub 1}-gewichtete MR-Urographie versus T{sub 2}-gewichtete (HASTE) MR-Urographie im Kindesalter

Energy Technology Data Exchange (ETDEWEB)

Staatz, G.; Nolte-Ernsting, C.C.A.; Haage, P.; Tacke, J.; Guenther, R.W. [Technische Hochschule Aachen (Germany). Klinik fuer Radiologische Diagnostik; Rohrmann, D. [Technische Hochschule Aachen (Germany). Urologische Klinik; Stollbrink, C. [Technische Hochschule Aachen (Germany). Kinderklinik

2001-11-01

Purpose: To evaluate gadolinium-enhanced T{sub 1}-weighted excretory MR urography (EMRU) versus T{sub 2}-weighted (HASTE) MR urography in children with upper urinary tract abnormalities. Patients and Methods: In a prospective study 63 children, aged from 3 weeks to 15 years, underwent MR urography in a 1.5-T scanner. Before and after an intravenous injection of 0.05 mg/kg body weight of furosemide, respiratory-triggered HASTE images were obtained for T{sub 2}-weighted MR urography. EMRU was performed subsequent to i.v. gadolinium injection with respiratory-gated, coronal 3D-gradient-echo sequences. Results: Compared to T{sub 2}-weighted (HASTE) MR urography, gadolinium-enhanced MR urography revealed a superior diagnostic accuracy in non-dilated collecting systems (horseshoe kidneys, ectopic kidneys, duplex systems, single ectopic ureters, ureteroceles). EMRU and T{sub 2}-weighted (HASTE) MRU turned out to be equivalent in the assessment of obstructed but normal functioning upper urinary tracts (UPJ obstructions, megaureters). Non-functioning dilated collecting systems and multicystic dysplastic kidneys were best visualized with use of T{sub 2}-weighted (HASTE) MR urography. Conclusion: Respiratory-gated gadolinium-enhanced T{sub 1}-weighted MRU allows accurate evaluation of most upper urinary tract abnormalities. T{sub 2}-weighted (HASTE) MRU complements GMRU in the evaluation of non-functioning renal units and cystic disease of the kidneys. (orig.) [German] Ziel: Vergleich der kontrastangehobenen T{sub 1}-gewichteten MR-Urographie mit der T{sub 2}-gewichteten (HASTE) MR-Urographie bei Kindern mit Anomalien des oberen Harntraktes. Methoden: In einer prospektiven Studie wurde bei 63 Kindern (3 Wo. - 15J.) eine MR-Urographie (MRU) in einem 1,5-Tesla-Magneten durchgefuehrt. Die T{sub 2}-gewichtete MRU erfolgte vor und nach intravenoeser Injektion von 0,05 mg/kg KG Furosemid mit atemgetriggerten HASTE-Sequenzen. Fuer die T{sub 1}-gewichtete MRU wurden nach

MR-based field-of-view extension in MR/PET: B0 homogenization using gradient enhancement (HUGE).

Science.gov (United States)

Blumhagen, Jan O; Ladebeck, Ralf; Fenchel, Matthias; Scheffler, Klaus

2013-10-01

In whole-body MR/PET, the human attenuation correction can be based on the MR data. However, an MR-based field-of-view (FoV) is limited due to physical restrictions such as B0 inhomogeneities and gradient nonlinearities. Therefore, for large patients, the MR image and the attenuation map might be truncated and the attenuation correction might be biased. The aim of this work is to explore extending the MR FoV through B0 homogenization using gradient enhancement in which an optimal readout gradient field is determined to locally compensate B0 inhomogeneities and gradient nonlinearities. A spin-echo-based sequence was developed that computes an optimal gradient for certain regions of interest, for example, the patient's arms. A significant distortion reduction was achieved outside the normal MR-based FoV. This FoV extension was achieved without any hardware modifications. In-plane distortions in a transaxially extended FoV of up to 600 mm were analyzed in phantom studies. In vivo measurements of the patient's arms lying outside the normal specified FoV were compared with and without the use of B0 homogenization using gradient enhancement. In summary, we designed a sequence that provides data for reducing the image distortions due to B0 inhomogeneities and gradient nonlinearities and used the data to extend the MR FoV. Copyright © 2011 Wiley Periodicals, Inc.

Early evaluation of irradiated parotid glands with intravoxel incoherent motion MR imaging: correlation with dynamic contrast-enhanced MR imaging

International Nuclear Information System (INIS)

Zhou, Nan; Chu, Chen; Dou, Xin; Li, Ming; Liu, Song; Zhu, Lijing; Liu, Baorui; Guo, Tingting; Chen, Weibo; He, Jian; Yan, Jing; Zhou, Zhengyang; Yang, Xiaofeng; Liu, Tian

2016-01-01

Radiation-induced parotid damage is one of the most common complications in patients with nasopharyngeal carcinoma (NPC) undergoing radiotherapy (RT). Intravoxel incoherent motion (IVIM) magnetic resonance (MR) imaging has been reported for evaluating irradiated parotid damage. However, the changes of IVIM perfusion-related parameters in irradiated parotid glands have not been confirmed by conventional perfusion measurements obtained from dynamic contrast-enhanced (DCE) MR imaging. The purposes of this study were to monitor radiation-induced parotid damage using IVIM and DCE MR imaging and to investigate the correlations between changes of these MR parameters. Eighteen NPC patients underwent bilateral parotid T1-weighted, IVIM and DCE MR imaging pre-RT (2 weeks before RT) and post-RT (4 weeks after RT). Parotid volume; IVIM MR parameters, including apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f); and DCE MR parameters, including maximum relative enhancement (MRE), time to peak (TTP), Wash in Rate, and the degree of xerostomia were recorded. Correlations of parotid MR parameters with mean radiation dose, atrophy rate and xerostomia degree, as well as the relationships between IVIM and DCE MR parameters, were investigated. From pre-RT to post-RT, all of the IVIM and DCE MR parameters increased significantly (p < 0.001 for ADC, D, f, MRE, Wash in Rate; p = 0.024 for D*; p = 0.037 for TTP). Change rates of ADC, f and MRE were negatively correlated with atrophy rate significantly (all p < 0.05). Significant correlations were observed between the change rates of D* and MRE (r = 0.371, p = 0.026) and between the change rates of D* and TTP (r = 0.396, p = 0.017). The intra- and interobserver reproducibility of IVIM and DCE MR parameters was good to excellent (intraclass correlation coefficient, 0.633–0.983). Early radiation-induced changes of parotid glands could be evaluated by IVIM and

Rickets on MR images

Energy Technology Data Exchange (ETDEWEB)

Ecklund, K.; Jaramillo, D. [Department of Radiology, Children`s Hospital, Boston, MA (United States); Doria, A.S. [Department of Radiology, Instituto da Crianca - Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo (Brazil)

1999-09-01

Background. The pathologic changes at the physis in patients with rickets have been well demonstrated histologically. Radiographs can depict only the associated osseous abnormalities. Patients and methods. We report two children in whom MR imaging demonstrated rachitic changes in the physeal cartilage beyond the well-recognized bony features. Results. The striking appearance of the physes and the physes of the secondary ossification centers confirm that MR imaging can successfully evaluate the cartilaginous structures of the developing skeleton. Conclusion. Though MR imaging is clearly unnecessary for the diagnosis of rickets, it is important that the typical features are not misinterpreted as other pathology. (orig.) With 6 figs., 6 refs.

Variable stiffness and damping MR isolator

Energy Technology Data Exchange (ETDEWEB)

Zhang, X Z; Wang, X Y; Li, W H; Kostidis, K [University of Wollongong, School of Mechanical, Materials and Mechatronic Engineering, NSW 2522 (Australia)], E-mail: weihuali@uow.edu.au

2009-02-01

This paper presents the development of a magnetorheological (MR) fluid-based variable stiffness and damping isolator for vibration suppressions. The MR fluid isolator used a sole MR control unit to achieve the variable stiffness and damping in stepless and relative large scope. A mathematical model of the isolator was derived, and a prototype of the MR fluid isolator was fabricated and its dynamic behavior was measured in vibration under various applied magnetic fields. The parameters of the model under various magnetic fields were identified and the dynamic performances of isolator were evaluated.

MR imaging of hemimegalencephaly in children

International Nuclear Information System (INIS)

Kalifa, G.; Sellier, N.; Demange, P.; Ponsot, G.; Chiron, C.; Robain, O.

1986-01-01

Hemimegalencephaly is a rare brain malformation characterized by cerebral asymmetry and cortical dysplasia. Affected infants are seen initially with early seizures and a severe encephalopathy. The author report five new cases studied with MR imaging. MR imaging clearly demonstrated brain hemihypertrophy, abnormal gyration, and poor differentiation between gray and white matter. A highly abnormal disposition of the cellular layers was observed. MR imaging turned out to be the most efficient diagnostic method for hemimegalencephaly. The examination may facilitate understanding and classification of this rare entity. Autopsy findings correlated well with MR imaging appearances

MR appearance of hypothalamic hamartoma

Energy Technology Data Exchange (ETDEWEB)

Hahn, F.J.; Leibrock, L.G.; Huseman, C.A.; Makos, M.M.

1988-02-01

Hypothalamic hamartoma is the most common detectable cerebral lesion causing precocious puberty. Two histologically confirmed cases were studied by computerized tomography (CT) and magnetic resonance (MR) imaging. T2 weighted, sagittal MR images were superior to CT in delineating the tumor from surrounding grey matter. The lesion was isointense to grey matter on T1 weighted images allowing exclusion of other hypothalamic tumors. MR will undoubtedly become the imaging modality of choice in the detection of hypothalamic hamartoma.

Retrospective 5-year analysis of MR-guided biopsies in a low-field MR system

International Nuclear Information System (INIS)

Zangos, Stephan; Mueller, C.; Mayer, F.; Naguib, N.N.; Nour-Eldin, N.E.A.; Herzog, C.; Hammerstingl, R.M.; Thalhammer, A.; Mack, M.G.; Vogl, T.J.; Eichler, K.; Hansmann, M.L.

2009-01-01

Purpose: The purpose of this study was to evaluate the safety and clinical value of MR-guided biopsies in an open 0.2 T low-field system. Materials and methods: A total of 322 patients with suspicious lesions of different body regions were biopsied in a low-field MRI system (0.2 T, Concerto, Siemens). The procedures were guided using T1-weighted Flash sequences (TR/TE = 100/9; 70 ). The lesions were repeatedly biopsied using the coaxial technique with a 15-gauge (diameter 2 mm) puncture needle. Complications and biopsy findings were analyzed retrospectively. Results: In all cases the biopsy procedures were successfully performed with MR guidance. In 298 patients diagnosis was able to be confirmed on the basis of the probes. The clinical follow-up showed that in 24 patients the lesions were missed by MR-guided biopsy. From this a sensitivity of 86%, a specificity of 87% and an accuracy of 93% were calculated. In two patients major complications were observed (morbidity rate 0.6%). Conclusion: MR-guided biopsy can be performed safely and precisely in a low-field MR system and are a supplement to US or CT-guided biopsies. (orig.)

MR imaging of carotid webs

International Nuclear Information System (INIS)

Boesen, Mari E.; Eswaradass, Prasanna Venkatesan; Singh, Dilip; Mitha, Alim P.; Menon, Bijoy K.; Goyal, Mayank; Frayne, Richard

2017-01-01

We propose a magnetic resonance (MR) imaging protocol for the characterization of carotid web morphology, composition, and vessel wall dynamics. The purpose of this case series was to determine the feasibility of imaging carotid webs with MR imaging. Five patients diagnosed with carotid web on CT angiography were recruited to undergo a 30-min MR imaging session. MR angiography (MRA) images of the carotid artery bifurcation were acquired. Multi-contrast fast spin echo (FSE) images were acquired axially about the level of the carotid web. Two types of cardiac phase resolved sequences (cineFSE and cine phase contrast) were acquired to visualize the elasticity of the vessel wall affected by the web. Carotid webs were identified on MRA in 5/5 (100%) patients. Multi-contrast FSE revealed vessel wall thickening and cineFSE demonstrated regional changes in distensibility surrounding the webs in these patients. Our MR imaging protocol enables an in-depth evaluation of patients with carotid webs: morphology (by MRA), composition (by multi-contrast FSE), and wall dynamics (by cineFSE). (orig.)

MR imaging of carotid webs

Energy Technology Data Exchange (ETDEWEB)

Boesen, Mari E. [University of Calgary, Department of Biomedical Engineering, Calgary (Canada); Foothills Medical Centre, Seaman Family MR Research Centre, Calgary (Canada); Eswaradass, Prasanna Venkatesan; Singh, Dilip; Mitha, Alim P.; Menon, Bijoy K. [University of Calgary, Department of Clinical Neurosciences, Calgary (Canada); Foothills Medical Centre, Calgary Stroke Program, Calgary (Canada); Goyal, Mayank [Foothills Medical Centre, Calgary Stroke Program, Calgary (Canada); University of Calgary, Department of Radiology, Calgary (Canada); Frayne, Richard [Foothills Medical Centre, Seaman Family MR Research Centre, Calgary (Canada); University of Calgary, Hotchkiss Brain Institute, Calgary (Canada)

2017-04-15

We propose a magnetic resonance (MR) imaging protocol for the characterization of carotid web morphology, composition, and vessel wall dynamics. The purpose of this case series was to determine the feasibility of imaging carotid webs with MR imaging. Five patients diagnosed with carotid web on CT angiography were recruited to undergo a 30-min MR imaging session. MR angiography (MRA) images of the carotid artery bifurcation were acquired. Multi-contrast fast spin echo (FSE) images were acquired axially about the level of the carotid web. Two types of cardiac phase resolved sequences (cineFSE and cine phase contrast) were acquired to visualize the elasticity of the vessel wall affected by the web. Carotid webs were identified on MRA in 5/5 (100%) patients. Multi-contrast FSE revealed vessel wall thickening and cineFSE demonstrated regional changes in distensibility surrounding the webs in these patients. Our MR imaging protocol enables an in-depth evaluation of patients with carotid webs: morphology (by MRA), composition (by multi-contrast FSE), and wall dynamics (by cineFSE). (orig.)

MR-Guided PTA in Experimental Bilateral Rabbit Renal Artery Stenosis and MR Angiography Follow-Up Versus Histomorphometry

International Nuclear Information System (INIS)

Le Blanche, Alain-Ferdinand; Rossert, Jerome; Wassef, Michel; Levy, Bernard; Bigot, Jean-Michel; Boudghene, Frank

2000-01-01

Purpose: To assess in vivo 1) MR-guided percutaneous transluminal renal angioplasty (PTRA) in experimental bilateral rabbit renal artery stenosis (RAS); 2) postprocedural follow-up by gadolinium-enhanced MR angiography versus histomorphometry.Methods: Fifteen male NZW rabbits of mean weight 4.0 kg (range 3.5-4.2 kg) underwent bilateral RAS induction by combined overdilation-deendothelialization with a gadolinium-filled balloon, passively MR-guided by the artifact of a 0.014-inch guidewire. After 4 weeks the rabbits were randomized into two groups: group A (n = 8) underwent right-sided PTRA for treatment of RAS, group B (n = 7) underwent left-sided PTRA. After another 4 weeks the rabbits were killed to assess by histomorphometry recurrent stenosis and contralateral induction injury stenosis lesions. Each step was preceded by gadolinium-enhanced three-dimensional MR angiography, and the cortex-to-aorta (C/A) signal intensity ratio was calculated.Results: RAS induction was successful in all cases. Fourteen arteries developed restenosis and 13 only initial stenosis. MR-guided PTRAs were feasible in 22 arteries (73%). For a successful catheterization of the ostium (20 arteries, 66% success rate), 10-25 steps were required. Five to eight steps were required for balloon localization and inflation for each PTRA. The restenosis effect was reflected by a 16% (12%-27%) decrease in C/A values on MR angiograms (p < 0.05).Conclusion: MR guidance and MR angiography represent a feasible, less invasive alternative for performing and assessing experimental PTRA in RAS

CT and MR imaging of craniopharyngioma

Energy Technology Data Exchange (ETDEWEB)

Tsuda, M. [Tohoku Univ. School of Medicine, Sendai (Japan). Dept. of Radiology; Takahashi, S. [Tohoku Univ. School of Medicine, Sendai (Japan). Dept. of Radiology; Higano, S. [Tohoku Univ. School of Medicine, Sendai (Japan). Dept. of Radiology; Kurihara, N. [Tohoku Univ. School of Medicine, Sendai (Japan). Dept. of Radiology; Ikeda, H. [Tohoku Univ. School of Medicine, Sendai (Japan). Dept. of Neurosurgery; Sakamoto, K. [Tohoku Univ. School of Medicine, Sendai (Japan). Dept. of Radiology

1997-05-01

We reviewed imaging findings of CT and MR imaging in 20 cases of surgically confirmed craniopharyngioma in an attempt to determine their relation to patterns of tumor extent. The relationship between these patterns and the frequency of preoperative CT diagnosis and MR imaging diagnosis according to the surgical diagnosis were determined. The CT technique was superior to MR imaging in the detection of calcification. The MR imaging technique was superior to CT for determining tumor extent and provided valuable information about the relationships of the tumor to surrounding structures. Thus, CT and MR imaging have complementary roles in the diagnosis of craniopharyngiomas. In cases of possible craniopharyngioma, noncontrast sagittal T1-weighted images may enable the identification of the normal pituitary, possibly leading to the correct diagnosis. (orig.)

CT and MR imaging of craniopharyngioma

International Nuclear Information System (INIS)

Tsuda, M.; Takahashi, S.; Higano, S.; Kurihara, N.; Ikeda, H.; Sakamoto, K.

1997-01-01

We reviewed imaging findings of CT and MR imaging in 20 cases of surgically confirmed craniopharyngioma in an attempt to determine their relation to patterns of tumor extent. The relationship between these patterns and the frequency of preoperative CT diagnosis and MR imaging diagnosis according to the surgical diagnosis were determined. The CT technique was superior to MR imaging in the detection of calcification. The MR imaging technique was superior to CT for determining tumor extent and provided valuable information about the relationships of the tumor to surrounding structures. Thus, CT and MR imaging have complementary roles in the diagnosis of craniopharyngiomas. In cases of possible craniopharyngioma, noncontrast sagittal T1-weighted images may enable the identification of the normal pituitary, possibly leading to the correct diagnosis. (orig.)

MR imaging of acute subarachnoid hemorrhage

International Nuclear Information System (INIS)

Spickler, E.; Lufkin, R.B.; Frazee, J.; Lylyk, P.; Vinuela, F.; Bentson, J.R.; Dion, J.E.

1987-01-01

Subarachnoid hemorrhage was produced in four Macaca nemestrina monkeys using the technique of Frazee. CT and MR imaging were performed immediately after the procedure and at frequent intervals up to 2 weeks after hemorrhage. The imaging studies were compared with clinical evaluations and pathologic specimens of all animals. Additional human clinical CT/MR studies of subarachnoid hemorrhage were also studied. Acute hemorrhage was recognized on MR as an increase in signal in the region of clot compared with surrounding cerebrospinal fluid. This most likely reflects T1 shortening due to proton binding rather than a pure paramagnetic effect. While CT is sensitive to the hemoglobin protein in acute hemorrhage, the superior resolution of the basal cisterns on MR images results in equal or better definition of acute subarachnoid hemorrhage on MR in many cases

Fibrolipomatous hamartoma: MR imaging findings

International Nuclear Information System (INIS)

De Maeseneer, M.; Jaovisidha, S.; Lenchik, L.; Witte, D.; Schweitzer, M.E.; Sartoris, D.J.; Resnick, D.

1997-01-01

Objective. To analyze the MR imaging features of fibrolipomatous hamartoma (FLH) of nerves. Design and patients. MR imaging studies from six patients (three men and three women) were retrospectively reviewed by three musculoskeletal radiologists. In four patients, a biopsy of the nerve lesion was performed. In two patients, biopsy data were unavailable and the diagnosis was based on the clinical history combined with the MR imaging findings. Results and conclusion. MR imaging demonstrated fusiform nerve enlargement that was caused by fatty proliferation and thickening of nerve bundles. Nerve bundles appeared as serpentine tubular structures, hypointense on both T1- and T2-weighted images. The degree of fatty proliferation varied among patients. In addition, significant variation in the distribution of fat along the course of the nerves was noted. In three patients, FLH followed the branching pattern of the nerves, a characteristic pathologic finding. In two patients, intramuscular fat deposition (biceps and tibialis posterior muscles) was present. MR imaging findings of FLH are typical, allowing a confident diagnosis. The variation of fatty proliferation among patients and involved nerves as well as the tendency of the abnormalities to follow the branching pattern of the nerves is well demonstrated with MR imaging. FLH may present as an isolated nerve lesion, may be associated with intramuscular fat deposition, or may occur as a feature of macrodystrophia lipomatosa (MDL). (orig.). With 5 figs., 2 tabs

Meniscal tear. Diagnostic errors in MR imaging

International Nuclear Information System (INIS)

Barrera, M. C.; Recondo, J. A.; Gervas, C.; Fernandez, E.; Villanua, J. A.M.; Salvador, E.

2003-01-01

To analyze diagnostic discrepancies found between magnetic resonance (MR) and arthroscopy, and the determine the reasons that they occur. Two-hundred and forty-eight MR knee explorations were retrospectively checked. Forty of these showed diagnostic discrepancies between MR and arthroscopy. Two radiologists independently re-analyzed the images from 29 of the 40 studies without knowing which diagnosis had resulted from which of the two techniques. Their interpretations were correlated with the initial MR diagnosis, MR images and arthroscopic results. Initial errors in MR imaging were classified as either unavoidable, interpretive, or secondary to equivocal findings. Eleven MR examinations could not be checked since their corresponding imaging results could not be located. Of 34 errors found in the original diagnoses, 12 (35.5%)were classified as unavoidable, 14 (41.2%) as interpretative and 8 (23.5%) as secondary to equivocal findings. 41.2% of the errors were avoided in the retrospective study probably due to our department having greater experience in interpreting MR images, 25.5% were unavailable even in the retrospective study. A small percentage of diagnostic errors were due to the presence of subtle equivocal findings. (Author) 15 refs

PET Imaging Stability Measurements During Simultaneous Pulsing of Aggressive MR Sequences on the SIGNA PET/MR System.

Science.gov (United States)

Deller, Timothy W; Khalighi, Mohammad Mehdi; Jansen, Floris P; Glover, Gary H

2018-01-01

The recent introduction of simultaneous whole-body PET/MR scanners has enabled new research taking advantage of the complementary information obtainable with PET and MRI. One such application is kinetic modeling, which requires high levels of PET quantitative stability. To accomplish the required PET stability levels, the PET subsystem must be sufficiently isolated from the effects of MR activity. Performance measurements have previously been published, demonstrating sufficient PET stability in the presence of MR pulsing for typical clinical use; however, PET stability during radiofrequency (RF)-intensive and gradient-intensive sequences has not previously been evaluated for a clinical whole-body scanner. In this work, PET stability of the GE SIGNA PET/MR was examined during simultaneous scanning of aggressive MR pulse sequences. Methods: PET performance tests were acquired with MR idle and during simultaneous MR pulsing. Recent system improvements mitigating RF interference and gain variation were used. A fast recovery fast spin echo MR sequence was selected for high RF power, and an echo planar imaging sequence was selected for its high heat-inducing gradients. Measurements were performed to determine PET stability under varying MR conditions using the following metrics: sensitivity, scatter fraction, contrast recovery, uniformity, count rate performance, and image quantitation. A final PET quantitative stability assessment for simultaneous PET scanning during functional MRI studies was performed with a spiral in-and-out gradient echo sequence. Results: Quantitation stability of a 68 Ge flood phantom was demonstrated within 0.34%. Normalized sensitivity was stable during simultaneous scanning within 0.3%. Scatter fraction measured with a 68 Ge line source in the scatter phantom was stable within the range of 40.4%-40.6%. Contrast recovery and uniformity were comparable for PET images acquired simultaneously with multiple MR conditions. Peak noise equivalent count

Actinomycotic brain infection: registered diffusion, perfusion MR imaging and MR spectroscopy

International Nuclear Information System (INIS)

Wang, Sumei; Wolf, Ronald L.; Woo, John H.; Melhem, Elias R.; Poptani, Harish; Wang, Jiongjiong; O'Rourke, Donald M.; Roy, Subhojit

2006-01-01

Introduction: Actinomycotic brain infection is caused by an organism of the Actinomyces genus. We report here one such case. Methods: The methods used included coregistered diffusion, perfusion and spectroscopic magnetic resonance (MR) imaging. Decreased apparent diffusion coefficient, markedly elevated fractional anisotropy (FA) and reduced cerebral blood flow were observed. MR spectroscopy demonstrated elevated amino acids, acetate and succinate. Elevated FA values may be due to the microstructure of this special brain infection. (orig.)

Hippocampal MR volumetry

Science.gov (United States)

Haller, John W.; Botteron, K.; Brunsden, Barry S.; Sheline, Yvette I.; Walkup, Ronald K.; Black, Kevin J.; Gado, Mokhtar; Vannier, Michael W.

1994-09-01

Goal: To estimate hippocampal volumes from in vivo 3D magnetic resonance (MR) brain images and determine inter-rater and intra- rater repeatability. Objective: The precision and repeatability of hippocampal volume estimates using stereologic measurement methods is sought. Design: Five normal control and five schizophrenic subjects were MR scanned using a MPRAGE protocol. Fixed grid stereologic methods were used to estimate hippocampal volumes on a graphics workstation. The images were preprocessed using histogram analysis to standardize 3D MR image scaling from 16 to 8 bits and image volumes were interpolated to 0.5 mm3 isotropic voxels. The following variables were constant for the repeated stereologic measures: grid size, inter-slice distance (1.5 mm), voxel dimensions (0.5 mm3), number of hippocampi measured (10), total number of measurements per rater (40), and number of raters (5). Two grid sizes were tested to determine the coefficient of error associated with the number of sampled 'hits' (approximately 140 and 280) on the hippocampus. Starting slice and grid position were randomly varied to assure unbiased volume estimates. Raters were blind to subject identity, diagnosis, and side of the brain from which the image volumes were extracted and the order of subject presentation was randomized for each of the raters. Inter- and intra-rater intraclass correlation coefficients (ICC) were determined. Results: The data indicate excellent repeatability of fixed grid stereologic hippocampal volume measures when using an inter-slice distance of 1.5 mm and a 6.25 mm2 grid (inter-rater ICCs equals 0.86 - 0.97, intra- rater ICCs equals 0.85 - 0.97). One major advantage of the current study was the use of 3D MR data which significantly improved visualization of hippocampal boundaries by providing the ability to access simultaneous orthogonal views while counting stereological marks within the hippocampus. Conclusion: Stereological estimates of 3D volumes from 2D MR

MR Spectroscopy and Perfusion MR Imaging Findings of Intracranial Foreign Body Granuloma: a Case Report

Energy Technology Data Exchange (ETDEWEB)

Jang, Seung Won; Kim, Sang Joon; Kim, Sun Mi; Lee, Jeong Hyun; Choi, Choong Gon; Lee, Deok Hee; Lee, Jung Kyo [University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of); Kim, Eun Ju [Philips Healthcare, Seoul (Korea, Republic of)

2010-06-15

We report a case of intracranial foreign body granuloma that showed features of a high grade tumor on magnetic resonance (MR) imaging. However, the relative cerebral blood volume was not increased in the enhancing mass on perfusion MRI and the choline/creatine ratio only slightly increased on MR spectroscopy. The results suggest that the lesion is benign in nature. Perfusion MRI and MR spectroscopy may be helpful to differentiate a foreign body granuloma from a neoplastic condition

Simultaneous PET-MR acquisition and MR-derived motion fields for correction of non-rigid motion in PET

International Nuclear Information System (INIS)

Tsoumpas, C.; Mackewn, J.E.; Halsted, P.; King, A.P.; Buerger, C.; Totman, J.J.; Schaeffter, T.; Marsden, P.K.

2010-01-01

Positron emission tomography (PET) provides an accurate measurement of radiotracer concentration in vivo, but performance can be limited by subject motion which degrades spatial resolution and quantitative accuracy. This effect may become a limiting factor for PET studies in the body as PET scanner technology improves. In this work, we propose a new approach to address this problem by employing motion information from images measured simultaneously using a magnetic resonance (MR) scanner. The approach is demonstrated using an MR-compatible PET scanner and PET-MR acquisition with a purpose-designed phantom capable of non-rigid deformations. Measured, simultaneously acquired MR data were used to correct for motion in PET, and results were compared with those obtained using motion information from PET images alone. Motion artefacts were significantly reduced and the PET image quality and quantification was significantly improved by the use of MR motion fields, whilst the use of PET-only motion information was less successful. Combined PET-MR acquisitions potentially allow PET motion compensation in whole-body acquisitions without prolonging PET acquisition time or increasing radiation dose. This, to the best of our knowledge, is the first study to demonstrate that simultaneously acquired MR data can be used to estimate and correct for the effects of non-rigid motion in PET. (author)

Effect of MR contrast agents on quantitative accuracy of PET in combined whole-body PET/MR imaging

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Lois, Cristina [University of Santiago de Compostela, Department of Particle Physics, Santiago de Compostela (Spain); Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela (Spain); Imaging Science Institute, Tuebingen (Germany); Bezrukov, Ilja [Eberhard Karls University, Laboratory for Preclinical Imaging and Imaging Technology of the Werner Siemens Foundation, Department of Preclinical Imaging and Radiopharmacy, Tuebingen (Germany); Max Plank Institute for Intelligent Systems, Department of Empirical Inference, Tuebingen (Germany); Schmidt, Holger [Eberhard Karls University, Laboratory for Preclinical Imaging and Imaging Technology of the Werner Siemens Foundation, Department of Preclinical Imaging and Radiopharmacy, Tuebingen (Germany); Eberhard Karls University, Diagnostic and Interventional Radiology, Department of Radiology, Tuebingen (Germany); Schwenzer, Nina; Werner, Matthias K. [Eberhard Karls University, Diagnostic and Interventional Radiology, Department of Radiology, Tuebingen (Germany); Kupferschlaeger, Juergen [Eberhard Karls University, Nuclear Medicine, Department of Radiology, Tuebingen (Germany); Beyer, Thomas [Imaging Science Institute, Tuebingen (Germany); cmi-experts GmbH, Zuerich (Switzerland)

2012-11-15

Clinical PET/MR acquisition protocols entail the use of MR contrast agents (MRCA) that could potentially affect PET quantification following MR-based attenuation correction (AC). We assessed the effect of oral and intravenous (IV) MRCA on PET quantification in PET/MR imaging. We employed two MRCA: Lumirem {sup registered} (oral) and Gadovist {sup registered} (IV). First, we determined their reference PET attenuation values using a PET transmission scan (ECAT-EXACT HR+, Siemens) and a CT scan (PET/CT Biograph 16 HI-REZ, Siemens). Second, we evaluated the attenuation of PET signals in the presence of MRCA. Phantoms were filled with clinically relevant concentrations of MRCA in a background of water and {sup 18}F-fluoride, and imaged using a PET/CT scanner (Biograph 16 HI-REZ, Siemens) and a PET/MR scanner (Biograph mMR, Siemens). Third, we investigated the effect of clinically relevant volumes of MRCA on MR-based AC using human pilot data: a patient study employing Gadovist {sup registered} (IV) and a volunteer study employing two different oral MRCA (Lumirem {sup registered} and pineapple juice). MR-based attenuation maps were calculated following Dixon-based fat-water segmentation and an external atlas-based and pattern recognition (AT and PR) algorithm. IV and oral MRCA in clinically relevant concentrations were found to have PET attenuation values similar to those of water. The phantom experiments showed that under clinical conditions IV and oral MRCA did not yield additional attenuation of PET emission signals. Patient scans showed that PET attenuation maps are not biased after the administration of IV MRCA but may be biased, however, after ingestion of iron oxide-based oral MRCA when segmentation-based AC algorithms are used. Alternative AC algorithms, such as AT and PR, or alternative oral contrast agents, such as pineapple juice, can yield unbiased attenuation maps. In clinical PET/MR scenarios MRCA are not expected to lead to markedly increased attenuation

Towards Implementing an MR-based PET Attenuation Correction Method for Neurological Studies on the MR-PET Brain Prototype

Science.gov (United States)

Catana, Ciprian; van der Kouwe, Andre; Benner, Thomas; Michel, Christian J.; Hamm, Michael; Fenchel, Matthias; Fischl, Bruce; Rosen, Bruce; Schmand, Matthias; Sorensen, A. Gregory

2013-01-01

A number of factors have to be considered for implementing an accurate attenuation correction (AC) in a combined MR-PET scanner. In this work, some of these challenges were investigated and an AC method based entirely on the MR data obtained with a single dedicated sequence was developed and used for neurological studies performed with the MR-PET human brain scanner prototype. Methods The focus was on the bone/air segmentation problem, the bone linear attenuation coefficient selection and the RF coil positioning. The impact of these factors on the PET data quantification was studied in simulations and experimental measurements performed on the combined MR-PET scanner. A novel dual-echo ultra-short echo time (DUTE) MR sequence was proposed for head imaging. Simultaneous MR-PET data were acquired and the PET images reconstructed using the proposed MR-DUTE-based AC method were compared with the PET images reconstructed using a CT-based AC. Results Our data suggest that incorrectly accounting for the bone tissue attenuation can lead to large underestimations (>20%) of the radiotracer concentration in the cortex. Assigning a linear attenuation coefficient of 0.143 or 0.151 cm−1 to bone tissue appears to give the best trade-off between bias and variability in the resulting images. Not identifying the internal air cavities introduces large overestimations (>20%) in adjacent structures. Based on these results, the segmented CT AC method was established as the “silver standard” for the segmented MR-based AC method. Particular to an integrated MR-PET scanner, ignoring the RF coil attenuation can cause large underestimations (i.e. up to 50%) in the reconstructed images. Furthermore, the coil location in the PET field of view has to be accurately known. Good quality bone/air segmentation can be performed using the DUTE data. The PET images obtained using the MR-DUTE- and CT-based AC methods compare favorably in most of the brain structures. Conclusion An MR-DUTE-based AC

Evaluation of an automatic MR-based gold fiducial marker localisation method for MR-only prostate radiotherapy

Science.gov (United States)

Maspero, Matteo; van den Berg, Cornelis A. T.; Zijlstra, Frank; Sikkes, Gonda G.; de Boer, Hans C. J.; Meijer, Gert J.; Kerkmeijer, Linda G. W.; Viergever, Max A.; Lagendijk, Jan J. W.; Seevinck, Peter R.

2017-10-01

An MR-only radiotherapy planning (RTP) workflow would reduce the cost, radiation exposure and uncertainties introduced by CT-MRI registrations. In the case of prostate treatment, one of the remaining challenges currently holding back the implementation of an RTP workflow is the MR-based localisation of intraprostatic gold fiducial markers (FMs), which is crucial for accurate patient positioning. Currently, MR-based FM localisation is clinically performed manually. This is sub-optimal, as manual interaction increases the workload. Attempts to perform automatic FM detection often rely on being able to detect signal voids induced by the FMs in magnitude images. However, signal voids may not always be sufficiently specific, hampering accurate and robust automatic FM localisation. Here, we present an approach that aims at automatic MR-based FM localisation. This method is based on template matching using a library of simulated complex-valued templates, and exploiting the behaviour of the complex MR signal in the vicinity of the FM. Clinical evaluation was performed on seventeen prostate cancer patients undergoing external beam radiotherapy treatment. Automatic MR-based FM localisation was compared to manual MR-based and semi-automatic CT-based localisation (the current gold standard) in terms of detection rate and the spatial accuracy and precision of localisation. The proposed method correctly detected all three FMs in 15/17 patients. The spatial accuracy (mean) and precision (STD) were 0.9 mm and 0.5 mm respectively, which is below the voxel size of 1.1 × 1.1 × 1.2 mm3 and comparable to MR-based manual localisation. FM localisation failed (3/51 FMs) in the presence of bleeding or calcifications in the direct vicinity of the FM. The method was found to be spatially accurate and precise, which is essential for clinical use. To overcome any missed detection, we envision the use of the proposed method along with verification by an observer. This will result in a

Evaluation of an automatic MR-based gold fiducial marker localisation method for MR-only prostate radiotherapy.

Science.gov (United States)

Maspero, Matteo; van den Berg, Cornelis A T; Zijlstra, Frank; Sikkes, Gonda G; de Boer, Hans C J; Meijer, Gert J; Kerkmeijer, Linda G W; Viergever, Max A; Lagendijk, Jan J W; Seevinck, Peter R

2017-10-03

An MR-only radiotherapy planning (RTP) workflow would reduce the cost, radiation exposure and uncertainties introduced by CT-MRI registrations. In the case of prostate treatment, one of the remaining challenges currently holding back the implementation of an RTP workflow is the MR-based localisation of intraprostatic gold fiducial markers (FMs), which is crucial for accurate patient positioning. Currently, MR-based FM localisation is clinically performed manually. This is sub-optimal, as manual interaction increases the workload. Attempts to perform automatic FM detection often rely on being able to detect signal voids induced by the FMs in magnitude images. However, signal voids may not always be sufficiently specific, hampering accurate and robust automatic FM localisation. Here, we present an approach that aims at automatic MR-based FM localisation. This method is based on template matching using a library of simulated complex-valued templates, and exploiting the behaviour of the complex MR signal in the vicinity of the FM. Clinical evaluation was performed on seventeen prostate cancer patients undergoing external beam radiotherapy treatment. Automatic MR-based FM localisation was compared to manual MR-based and semi-automatic CT-based localisation (the current gold standard) in terms of detection rate and the spatial accuracy and precision of localisation. The proposed method correctly detected all three FMs in 15/17 patients. The spatial accuracy (mean) and precision (STD) were 0.9 mm and 0.5 mm respectively, which is below the voxel size of [Formula: see text] mm 3 and comparable to MR-based manual localisation. FM localisation failed (3/51 FMs) in the presence of bleeding or calcifications in the direct vicinity of the FM. The method was found to be spatially accurate and precise, which is essential for clinical use. To overcome any missed detection, we envision the use of the proposed method along with verification by an observer. This will result in a

Fast generation of 4D PET-MR data from real dynamic MR acquisitions

International Nuclear Information System (INIS)

Tsoumpas, C; Buerger, C; King, A P; Schleyer, P; Schaeffter, T; Marsden, P K; Mollet, P; Keereman, V; Vandenberghe, S; Schulz, V

2011-01-01

We have implemented and evaluated a framework for simulating simultaneous dynamic PET-MR data using the anatomic and dynamic information from real MR acquisitions. PET radiotracer distribution is simulated by assigning typical FDG uptake values to segmented MR images with manually inserted additional virtual lesions. PET projection data and images are simulated using analytic forward projections (including attenuation and Poisson statistics) implemented within the image reconstruction package STIR. PET image reconstructions are also performed with STIR. The simulation is validated with numerical simulation based on Monte Carlo (GATE) which uses more accurate physical modelling, but has 150x slower computation time compared to the analytic method for ten respiratory positions and is 7000x slower when performing multiple realizations. Results are validated in terms of region of interest mean values and coefficients of variation for 65 million coincidences including scattered events. Although some discrepancy is observed, agreement between the two different simulation methods is good given the statistical noise in the data. In particular, the percentage difference of the mean values is 3.1% for tissue, 17% for the lungs and 18% for a small lesion. The utility of the procedure is demonstrated by simulating realistic PET-MR datasets from multiple volunteers with different breathing patterns. The usefulness of the toolkit will be shown for performance investigations of the reconstruction, motion correction and attenuation correction algorithms for dynamic PET-MR data.

MR of head and neck hemangiomas

International Nuclear Information System (INIS)

Bilaniuk, L.T.; Zimmerman, R.A.; Gusnard, D.A.

1990-01-01

This paper defines the MR characteristics of head and neck hemangiomas and to evaluate the role of MR in their diagnosis and management. Eighteen pediatric and young adult patients with head and neck hemangiomas (six neck, six face, three eyelid, two scalp, and one parotid) underwent high-field-strength 1.5-T MR imaging. Conventional spin-echo sequences with T1 and T2 weighting were performed. In addition, one-third of patients underwent MR angiography and gadolinium enhancement. The hemangiomas were isointense to muscle on T1-weighted images and hyperintense on proton-density and T2-weighted images

Brain MR imaging in child abuse

International Nuclear Information System (INIS)

Sato, Y.; Ellerbroek, C.J.; Alexander, R.; Kao, S.C.S.; Yuh, W.T.C.; Smith, W.L.

1988-01-01

Intracranial injuries represent the most severe manifestation of child abuse. CT of the brain is the current standard for evaluation of these infants; however, MR imaging offers several potential advantages. MR imaging and CT were performed in ten infants who suffered intracranial trauma owing to child abuse. CT was slightly better at demonstrating subarachnoid hemorrhage and had definite advantages for defining fractures. MR imaging was superior in the demonstration of subacute extraaxial hemorrhage, deep brain injuries owing to shearing effects from shaking, and anoxic injuries. MR imaging has a definite complementary role in the evaluation of acute intracranial trauma in child abuse victims

MR spectroscopy in metabolic disorders of the brain; MR-Spektroskopie bei Stoffwechselerkrankungen des Gehirns

Energy Technology Data Exchange (ETDEWEB)

Yilmaz, U. [Universitaetsklinikum des Saarlandes, Klinik fuer Diagnostische und Interventionelle Neuroradiologie, Homburg/Saar (Germany)

2017-06-15

Metabolic disorders of the brain often present a particular challenge for the neuroradiologist, since the disorders are rare, changes on conventional MR are often non-specific and there are numerous differential diagnoses for the white substance lesions. As a complementary method to conventional brain MRI, MR spectroscopy may help to reduce the scope of the differential diagnosis. Entities with specific MR spectroscopy patterns are Canavan disease, maple syrup urine disease, nonketotic hyperglycinemia and creatine deficiency. (orig.) [German] Die Diagnostik metabolischer Erkrankungen des Gehirns stellt eine besondere Herausforderung in der Neuroradiologie dar, da die Erkrankungen insgesamt selten, die bildmorphologischen Befunde haeufig unspezifisch sind und es eine Vielzahl von Differenzialdiagnosen fuer die Veraenderungen der weissen Substanz gibt. Als zusaetzliche Technik kann die MR-Spektroskopie bei Stoffwechselerkrankungen helfen, die Diagnose einzugrenzen. Krankheitsentitaeten, die spezifische Veraenderungen in der Spektroskopie aufweisen, sind der Morbus Canavan, die Ahornsirupkrankheit, die nichtketotische Hyperglyzinaemie und Kreatinmangelsyndrome. (orig.)

MR imaging evaluation of diabetic foot

International Nuclear Information System (INIS)

Beltran, J.; Campanini, D.S.; McCalla, M.; Knight, C.T.

1988-01-01

Fourteen diabetic patients with suspected foot infection and/or neuropathic joint were evaluated with MR imaging to identify the presence and extent of infection and also to exclude coexistent infection in the neuropathic joint. Osteomyelitis (n = 8), abscess (n = 7), septic arthritis (n = 4), tenosynovitis (n = 4), and neuropathic joint (n = 5) were diagnosed with MR imaging. Osteomyelitis and/or abscess were excluded by MR findings in 13 instances. Most patients with infection had one more than one site of involvement. Clinical or surgical confirmation of the MR diagnoses was obtained in all but nine of the infection sites or cases of neuropathic joint. Only one false-negative diagnosis of osteomyelitis was made in this series. It is concluded that MR imaging provided accurate information regarding the presence and extent of infection and that this information was decisive in patient management

MR diagnosis of dural sinus thrombosis

International Nuclear Information System (INIS)

Rovira Canellas, A.; Turon Estrada, A.; Alvarez Sabin, J.; Lozano Sanchez, M.; Castano Duque, Ch.; Grive Isern, E.; Sumalla Sune, J.

1994-01-01

Four adult patients were diagnosed as having dural sinus thrombosis (DST) by means of magnetic resonance (MR). In the three cases of acute thrombosis, MR disclosed diffuse or segmental hyperintensity in the sinuses involved, which persisted regardless of the sequence and orientation of the plane selected. MR angiography (MRA) provided diagnostic information that proved useful in the chronic case, as well as in the two cases in which follow-up was carried out to determine the degree to which permeability was restored to the sinuses involved. MR diagnosis of DST can produce false positives and negatives, the causes of which should be known, as well as the ways to avoid them, in order to prevent diagnostic errors. MR, when applied and interpreted correctly, can be considered the first, and in many cases the only, choice as a diagnostic method in DST. (Author)

Semiautomated spleen volumetry with diffusion-weighted MR imaging.

Science.gov (United States)

Lee, Jeongjin; Kim, Kyoung Won; Lee, Ho; Lee, So Jung; Choi, Sanghyun; Jeong, Woo Kyoung; Kye, Heewon; Song, Gi-Won; Hwang, Shin; Lee, Sung-Gyu

2012-07-01

In this article, we determined the relative accuracy of semiautomated spleen volumetry with diffusion-weighted (DW) MR images compared to standard manual volumetry with DW-MR or CT images. Semiautomated spleen volumetry using simple thresholding followed by 3D and 2D connected component analysis was performed with DW-MR images. Manual spleen volumetry was performed on DW-MR and CT images. In this study, 35 potential live liver donor candidates were included. Semiautomated volumetry results were highly correlated with manual volumetry results using DW-MR (r = 0.99; P volumetry was significantly shorter compared to that of manual volumetry with DW-MR (P volumetry with DW-MR images can be performed rapidly and accurately when compared with standard manual volumetry. Copyright © 2011 Wiley Periodicals, Inc.

MR imaging of rotator cuff tears

International Nuclear Information System (INIS)

Kumagai, Hideo

1992-01-01

A total of 115 patients with clinical symptoms and signs suggesting rotator cuff tears underwent MR imaging with a 1.5-Tesla system. The body coil was used as the receiver coil in 24 patients and a single 10 cm surface coil in 91. Arthrography or MR imaging with intra-articular Gd-DTPA (MR arthrography) was performed in 95 of the 115. T2-weighted images with the body coil showed high signal intensity lesions in rotator cuffs in only seven of the 10 patients who had tears demonstrated by arthrography or MR arthrography. On the other hand, T2-weighted images with the surface coil demonstrated high signal intensity lesions in cuffs in all 27 patients who were diagnosed to have tears by arthrography or MR arthrography. In 12 patietns, T2-wighted images with the surface coil showed high signal intensity lesions in cuffs, while arthrography and MR arthrography did not show tears. Surgery was performed in four of the 12 patients and partial tears were confirmed. A single 10 cm surface coil, 3 mm slice thickness and 2.5 second repetition time seem to account for the fine visualization of cuff tears by the T2-weighted images. These results suggest that T2-weighted images obtained with the surface coil are superior to arthrography and MR arthrography. (author)

MR implant labelling and its use in clinical MRI practice; MR-Implantatkennzeichnungen und ihre Anwendung in der klinischen MRT-Praxis

Energy Technology Data Exchange (ETDEWEB)

Muehlenweg, M. [Krankenhaus Martha-Maria Halle-Doelau, Institut fuer Radiologie, Halle (Saale) (Germany); Schaefers, G. [MR:comp GmbH, Gelsenkirchen (Germany)

2015-08-15

Before a magnetic resonance imaging (MRI) examination, implants in patients must be cleared for MR safety in order to exclude the risk of possible severe injuries and implant malfunction in an MR environment. The general contraindication for measurements of patients with implants still applies; however, in the recent past a way has been found to legally circumvent this contraindication. For this purpose special conditions are required: explicit implant identification and the original manufacturer's labelling are necessary, the required conditions for conditionally MR safe implants must be assured and a risk-benefit analysis with appropriate explanation to the patient has to be performed. This process can be very complex as the implants are often poorly documented and detailed information on the implant MR labelling is also often outdated or not easy to interpret. This article provides information about legal and normative principles of MR measurement of patients with implants. The possible physical interactions with implants will be briefly dealt with as well as possible strategies for better identification and investigation of implants and MR labelling. General approaches for minimizing the risk will be discussed using some examples. The second part deals with the content of MR implant labelling and the current test standards. Furthermore, the additional information from the operating instructions of the MR scanner that are necessary for the interpretation of the MR implant labelling, will be explained. The article concludes with an explanation of the current pattern for MR labelling of implants from the U.S. Food and Drug Administration (FDA) and an exemplary application. (orig.) [German] Implantate in Patienten muessen vor einer MR-Untersuchung auf MR-Sicherheit abgeklaert werden, um moegliche z. T. schwere Verletzungen und Implantatfehlfunktionen in einer MR-Umgebung weitestgehend auszuschliessen. Es gilt unveraendert die generelle Kontraindikation von

Intra-Arterial MR Perfusion Imaging of Meningiomas: Comparison to Digital Subtraction Angiography and Intravenous MR Perfusion Imaging.

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Mark A Lum

Full Text Available To evaluate the ability of IA MR perfusion to characterize meningioma blood supply.Studies were performed in a suite comprised of an x-ray angiography unit and 1.5T MR scanner that permitted intraprocedural patient movement between the imaging modalities. Patients underwent intra-arterial (IA and intravenous (IV T2* dynamic susceptibility MR perfusion immediately prior to meningioma embolization. Regional tumor arterial supply was characterized by digital subtraction angiography and classified as external carotid artery (ECA dural, internal carotid artery (ICA dural, or pial. MR perfusion data regions of interest (ROIs were analyzed in regions with different vascular supply to extract peak height, full-width at half-maximum (FWHM, relative cerebral blood flow (rCBF, relative cerebral blood volume (rCBV, and mean transit time (MTT. Linear mixed modeling was used to identify perfusion curve parameter differences for each ROI for IA and IV MR imaging techniques. IA vs. IV perfusion parameters were also directly compared for each ROI using linear mixed modeling.18 ROIs were analyzed in 12 patients. Arterial supply was identified as ECA dural (n = 11, ICA dural (n = 4, or pial (n = 3. FWHM, rCBV, and rCBF showed statistically significant differences between ROIs for IA MR perfusion. Peak Height and FWHM showed statistically significant differences between ROIs for IV MR perfusion. RCBV and MTT were significantly lower for IA perfusion in the Dural ECA compared to IV perfusion. Relative CBF in IA MR was found to be significantly higher in the Dural ICA region and MTT significantly lower compared to IV perfusion.

CT and MR imaging of the kidney and adrenal glands: MR imaging of the kidney and adrenal glands

International Nuclear Information System (INIS)

Lee, J.K.T.

1987-01-01

The normal anatomy of the kidney is clearly demonstrated with MR imaging. The renal cortex can be differentiated from the renal medulla; renal vessels can also be identified. MR imaging can differentiate cystic from solid lesions. The signal intensity of a renal cell carcinoma varies and overlaps with the signal intensities of renal neoplasms of other etiologies. MR imaging is superior to CT in distinguishing vascular from nonvascular structures. It can distinguish collateral vessels from lymph nodes and can disclose tumoral thrombi. MR imaging can also aid in the differentiation of acute rejection from acute tubular necrosis in renal transplant recipients. Both normal and abnormal adrenal glands can be seen on MR imaging. A normal adrenal gland has a signal intensity higher than or equal to that of muscle but lower than that of fat. T1-weighted images offer excellent antomic resolution; T2-weighted images provide additional information about internal characteristics of adrenal neoplasms. Preliminary data indicate that MR imaging is useful in distinguishing nonfunctioning adenomas from adrenal metastases. The role of MR imaging of the kidney and adrenal gland is discussed

Normal anatomy of the fetus at MR imaging.

Science.gov (United States)

Amin, R S; Nikolaidis, P; Kawashima, A; Kramer, L A; Ernst, R D

1999-10-01

Owing to recent advances in magnetic resonance (MR) imaging, the role of obstetric MR imaging has increased in cases in which the results of ultrasonography are equivocal. Fast MR imaging sequences, such as T2-weighted fast spin-echo (SE), half-Fourier single-shot fast SE, 0.5-signal-acquired single-shot fast SE, and echo-planar imaging, have virtually eliminated the need for fetal premedication, with a concomitant improvement in image resolution and diminished blurring. Artifacts related to maternal respiratory motion and fetal motion no longer limit the anatomic detail that can be demonstrated with MR imaging. With such advances in obstetric MR imaging, knowledge of normal fetal anatomy at MR imaging is essential to detect disease in utero. MR imaging can demonstrate fetal anatomy in detail, especially the brain, thorax, abdomen, pelvis, and vasculature. Major developmental structures of the fetus, particularly the cranial nervous system, naso- and oropharynx, lungs, and major abdominal viscera, can be adequately evaluated with targeted fast MR imaging as early as the beginning of the second trimester. However, MR imaging of the heart remains limited. Fetal MR imaging during the first trimester remains controversial secondary to biosafety issues and is limited due to diminutive fetal size.

MR imaging of acute cervical spine injuries

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyu Hwa; Lee, Jung Hyung; Joo, Yang Goo [School of Medicine, Keimyung University, Daegu (Korea, Republic of)

1995-01-15

To describe magnetic resonance (MR) findings of the patients with acute cervical spinal injury and to assess the usefulness of the MR imagings. We retrospectively reviewed the MR images of 32 patients with acute cervical spinal injury. MR images were obtained with a 2.0 T superconductive MR imaging units (Spectro-20000, Gold-Star, Seoul), using spin-echo and gradient-echo technique. Most of patients were in their 3rd-4th decades and motor vehicle accident was the most frequent cause of acute cervical trauma. We assessed the MR findings with respect to the spinal cord, ligaments, paravertebral soft tissues, intervertebral disk, and bony spine. Spinal cord injury was the most common (65%), where cord swelling, edema, and/or hematoma were demonstrated most frequently at C5-6 level. Traumatic intervertebral disk herniations were the second most common (62.5%) and frequently occurred at the lower cervical levels, mostly at C5-6. Paravertebral soft tissue injury, vertebral body fracture, bone marrow edema and displacement were also well shown on MR images. MR imaging appears to be essential for the evaluation of traumatic disk herniations, spinal cord abnormalities, and injury of paravertebral soft tissue in the acute injury of the cervical spine.

MR imaging of acute cervical spine injuries

International Nuclear Information System (INIS)

Kim, Kyu Hwa; Lee, Jung Hyung; Joo, Yang Goo

1995-01-01

To describe magnetic resonance (MR) findings of the patients with acute cervical spinal injury and to assess the usefulness of the MR imagings. We retrospectively reviewed the MR images of 32 patients with acute cervical spinal injury. MR images were obtained with a 2.0 T superconductive MR imaging units (Spectro-20000, Gold-Star, Seoul), using spin-echo and gradient-echo technique. Most of patients were in their 3rd-4th decades and motor vehicle accident was the most frequent cause of acute cervical trauma. We assessed the MR findings with respect to the spinal cord, ligaments, paravertebral soft tissues, intervertebral disk, and bony spine. Spinal cord injury was the most common (65%), where cord swelling, edema, and/or hematoma were demonstrated most frequently at C5-6 level. Traumatic intervertebral disk herniations were the second most common (62.5%) and frequently occurred at the lower cervical levels, mostly at C5-6. Paravertebral soft tissue injury, vertebral body fracture, bone marrow edema and displacement were also well shown on MR images. MR imaging appears to be essential for the evaluation of traumatic disk herniations, spinal cord abnormalities, and injury of paravertebral soft tissue in the acute injury of the cervical spine

Introduction of a MR-compatible system for extracorporal perfusion of vital organs for MR-guided procedures. First-experiences

International Nuclear Information System (INIS)

Gaffke, Gunnar; Nagel, Stefan; Hegemann, Olaf; Speck, Ulrich; Grosse-Siestrup, Christian; Jungnickel, Kerstin; Stroszczynski, Christian

2009-01-01

Purpose:To represent a MRI-compatible perfusion-system for extracorporeal perfusion of vital organs which permits the realisation of realistic experiments in a MR scanner. Material and methods: We performed MR examinations of explanted porcine livers and MR-guided interventions in porcine livers. Explanted organs were hemo-perfused under physiological conditions during the experiments. MR-sequences for diagnostic and interventional examinations were used. Results:The evaluated system was MRI-compatible. The achieved image quality of the used sequences showed excellent anatomical resolution. Planned experiments can be carried out with relatively low expenditure. Diagnostic as well as interventional investigations can be carried out. The used organs showed a stable function within physiological parameters up to 4 hours. Conclusion:It is possible to perform ex vivo experiments under in vivo conditions with this system. With the used MR-compatible system MR-guided experimental interventions and thermal ablations can be carried out in explanted organs under in vivo conditions. (orig.)

Deep MR to CT synthesis using unpaired data

NARCIS (Netherlands)

Wolterink, Jelmer M.; Dinkla, Anna M.; Savenije, Mark H.F.; Seevinck, Peter R.; van den Berg, Cornelis A.T.; Išgum, Ivana

2017-01-01

MR-only radiotherapy treatment planning requires accurate MR-to-CT synthesis. Current deep learning methods for MR-to-CT synthesis depend on pairwise aligned MR and CT training images of the same patient. However, misalignment between paired images could lead to errors in synthesized CT images. To

Serial MR imaging in Creutzfeldt-Jakob disease

Energy Technology Data Exchange (ETDEWEB)

Uchino, A.; Hata, H.; Ohno, M. (Kyushu Rosai Hospital, Kitakyushu (Japan). Dept. of Radiology); Yoshinaga, M.; Shiokawa, O. (Kyushu Rosai Hospital, Kitakyushu (Japan). Stroke Care Unit)

1991-08-01

Serial magnetic resonance (MR) imagings of two autopsied patients with Creutzfeldt-Jakob disease (CJD) are presented. Both patients showed a dramatic progression of brain atrophy. The initial MR imagings were, however, interpreted as normal except for localized mild cortical atrophy in one patient. When a normal MR image is obtained in a demented middle-aged or aged patient, CJD may still need to be ruled out: follow up MR imaging may be useful. (orig.).

Serial MR imaging in Creutzfeldt-Jakob disease

International Nuclear Information System (INIS)

Uchino, A.; Hata, H.; Ohno, M.; Yoshinaga, M.; Shiokawa, O.

1991-01-01

Serial magnetic resonance (MR) imagings of two autopsied patients with Creutzfeldt-Jakob disease (CJD) are presented. Both patients showed a dramatic progression of brain atrophy. The initial MR imagings were, however, interpreted as normal except for localized mild cortical atrophy in one patient. When a normal MR image is obtained in a demented middle-aged or aged patient, CJD may still need to be ruled out: follow up MR imaging may be useful. (orig.)

MR findings of brainstem injury

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Park, Man Soo; Hwang, Woo Cheol; Park, Choong Ki [Hallym University College of Medicine, Seoul (Korea, Republic of); Suh, Dae Chul [University of Ulsan College of Medicine, Seoul (Korea, Republic of); Kim, Sang Joon [Dankook University of College of Medicine, Cheonan (Korea, Republic of)

1995-02-15

To analyze the characteristics of traumatic brainstem injury by CT and MR. CT and MR studies of 10 patients with traumatic brainstem lesion in MR were retrospectively reviewed, particularly attended to location, signal intensity and associated lesions. CT failed to depict 8 of 10 brainstem lesions. All lesions were detected in MR images with T2-weighted images showing higher detection rate (n = 10) (100%) than T1-weighted images (n = 3) (30%) or CT (n = 2) (20%). The brainstem lesions located in the dorsolateral aspects of the rostral brainstem (mid brain and upper pons) in 7 (70%) cases, in ventral aspects of rostral brain in 2 (20%) cases and in median portion of pons in 1 (10%) case. Corpus callosal (n = 5), lobar white matter (n = 5) diffuse axonal injury, and 2 hemorrhagic lesions in basal ganglia were the associated findings. MR imaging is more helpful than CT in the detection of brainstem injury, especially T2 weighted images. Primary brainstem lesions were typically located in the dorsolateral aspect of rostral brainstem (midbrain and upper pons). Corpus callosum and white matter lesions were frequently associated.

MR evaluation of fetal demise

International Nuclear Information System (INIS)

Victoria, Teresa; Chauvin, Nancy Anne; Johnson, Ann M.; Kramer, Sandra Sue; Epelman, Monica; Capilla, Elena

2011-01-01

Fetal demise is an uncommon event encountered at MR imaging. When it occurs, recognition by the interpreting radiologist is important to initiate appropriate patient management. To identify MR findings of fetal demise. Following IRB approval, a retrospective search of the radiology fetal MR database was conducted searching the words ''fetal demise'' and ''fetal death.'' Fetuses with obvious maceration or no sonographic confirmation of death were excluded. Eleven cases formed the study group. These were matched randomly to live fetuses of similar gestational age. Images were reviewed independently by three pediatric radiologists. The deceased fetus demonstrates decreased MR soft-tissue contrast and definition of tissue planes, including loss of gray-white matter differentiation in the brain. The signal within the cardiac chambers, when visible, is bright on HASTE sequences from the stagnant blood; the heart is small. Pleural effusions and decreased lung volumes may be seen. Interestingly, the fetal orbits lose their anatomical round shape and become smaller and more elliptical; a dark, irregular rim resembling a mask may be seen. Although fetal demise is uncommonly encountered at MR imaging, radiologists should be aware of such imaging findings so prompt management can be instituted. (orig.)

Unusual MR manifestations of neurocysticercosis

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Suh, D.C. (Seoul National Univ. (Republic of Korea). Dept. of Radiology; Woolsan Medical Coll., Seoul (Republic of Korea). Dept. of Radiology); Chang, K.H.; Han, M.H.; Han, M.C.; Kim, C.W. (Seoul National Univ. (Republic of Korea). Dept. of Radiology); Lee, S.R. (Hanyang Univ., Seoul (Republic of Korea). Dept. of Radiology)

1989-11-01

MR and CT features of neurocysticercosis are variable and depend fundamentally on the stage in evolution of the infection, location, number and size of the worm. The authors retrospectively evaluated MR images obtained on a 2.0T superconducting unit in 22 neurocysticercosis patients and observed various MR features including some new findings. A variety of MR findings are presented with special reference to six case reports. The features include: (1) A large simple cyst containing both internal septations and a scolex; (2) suprasellar racemose cysts mimicking other cysts, (3) a fourth ventricular cyst readily depicted by aid of CSF flow-void in the sagittal plane; (4) degenerating cysts showing 'white target' appearance; (5) granulomatous lesions having a 'black target' appearance; and (6) a meningitic form showing Gd-DTPA enhancement of basal cisterns and of a subacute infarct. (orig.).

MR staging of malignant musculoskeletal tumors: An experimental study on MR and pathologic correlation of rabbit VX-2 carcinoma

International Nuclear Information System (INIS)

Kang, Heung Sik; Chung, Sung Hoon; KIm, Cheol Woo; Kim, Seong Moon; Im, Jung Gi; Han, Man Chung

1993-01-01

To evaluate the reliability of MR imaging in tissue characterization and depiction of tumor boundaries, we performed MR pathologic correlation using parosteally implanted VX-2 carcinoma in 17 rabbit thighs. T1-weighted, T2-weighted and Gd-DTPA enhanced T1-weighted axial images were obtained 10-30 days after tumor implantation. After the animals were killed, frozen and sectioned along the MR imaging planes, and histopathologic examination were done. For accurate MR pathologic correlation, rabbit were fixed on the cardboard plate to minimize position change during the procedure. Tumor boundaries depicted on MR images were larger than those depicted on the specimen. Small tumors were surrounded by capsule-like loose connective tissue. Loose connective tissue became compact with tumor growth. This connective tissue showed high signal intensity on both T2-weighted and Gd-DTPA enhanced T1-weighted images. Muscle atrophy with fatty tissue accumulation around the tumor also contributed to the high signal intensity on MR images. Peritumoral edema and inflammatory reaction were not remarkable. Six of 8 cases with bone marrow fibrosis were detected on MR images. We concluded that peritumoral loose connective tissue and muscle atrophy exaggerated the size of experimentally induced malignant musculoskeletal tumors on MR images

Questionnaire responses concerning safety issues in MR examination

International Nuclear Information System (INIS)

Yamaguchi-Sekino, Sachiko; Nakai, Toshiharu; Muranaka, Hiroyuki

2011-01-01

Recently, the rising numbers of medical implants and scanners with higher static magnetic field have increased safety concerns for magnetic resonance (MR) examination. To determine future safety focus, we distributed anonymous questionnaires to 3250 members of the Japanese Society for Magnetic Resonance in Medicine (JSMRM) and received 978 responses. Safety issues on the questionnaire concentrated on the handling of patients with implants (Q7-18, appendix), acoustic trauma due to scanning (Q19-21, appendix), and MR compatibility within the scanner room (Q22-25, appendix). Ninety-three percent of respondents indicated they had encountered cases with implants or medical materials of unknown MR compatibility; 21.7% reported heating problems and 15.0%, nerve stimulation problems, in patients with implants during MR examination. Although 88.7% of respondents recognized the term ''MR compatibility'', 68.2% indicated limited detailed understanding of the term. Eleven percent had had cases with suspected acoustic injury from MR scanner noise. Scanner noise levels were not clarified in any way in 37.4% cases, but 69.5% applied ear protection to patients. Labeling of ''MR compatibility'' of equipment brought into the MR scanner room was reported by 71.9%. More than 50% experienced MR compatibility issues related to equipment brought into the MR scanner room. With regard to safety issues on metallic objects which are implanted in MR workers, 88.1% indicated they would continue current operations even the implant is inside the body. Respondents identified lectures and seminars by professional societies, safety training by manufacturers, and information from the Internet and literature as the 3 main sources for up-dating safety information for MR examination. (author)

Craniofacial duplication (diprosopus): CT, MR imaging, and MR angiography findings case report.

Science.gov (United States)

Hähnel, Stefan; Schramm, Peter; Hassfeld, Stefan; Steiner, Hans H; Seitz, Angelika

2003-01-01

Diprosopus is one of the rarest malformations in humans. In addition to the facial structures, the cerebral frontal lobes were duplicated in this case. Three pairs of anterior cerebral arteries were detected, and the rostral parts of the superior sagittal sinus were duplicated. Computed tomography, magnetic resonance (MR) imaging, and MR angiography allowed study of the degree of duplicative changes in diprosopus, especially for planning cosmetic correction. Copyright RSNA, 2002

Breast MR imaging: correlation of high resolution dynamic MR findings with prognostic factors

International Nuclear Information System (INIS)

Lee, Shin Ho; Cho, Nariya; Chung, Hye Kyung; Kim, Seung Ja; Cho, Kyung Soo; Moon, Woo Kyung; Cho, Joo Hee

2005-01-01

We wanted to correlate the kinetic and morphologic MR findings of invasive breast cancer with the classical and molecular prognostic factors. Eighty-seven patients with invasive ductal carcinoma NOS underwent dynamic MR imaging at 1.5 T, and with using the T1-weighted 3D FLASH technique. The morphologic findings (shape, margin, internal enhancement of the mass or the enhancement distribution and the internal enhancement of any non-mass lesion) and the kinetic findings (the initial phase and the delayed phase of the time-signal. Intensity curve) were interpreted using a ACR BI-RADS-MRI lexicon. We correlate MR findings with histopathologic prognostic factors (tumor size, lymph node status and tumor grade) and the immunohistochemically detected biomarkers (ER, PR, ρ 53, c-erbB-2, EGFR and Ki-67). Univariate and multivariate statistical analyses were than performed. Among the MR findings, a spiculated margin, rim enhancement and washout were significantly correlated with the prognostic factors. A spiculated margin was independently associated with the established predictors of a good prognosis (a lower histologic and nuclear grade, positive ER and PR) and rim enhancement was associated with a poor prognosis (a higher histologic and nuclear grade, negative ER and PR). Wash out was a independent predictor of Ki-67 activity. Some of the findings of high resolution dynamic MR imaging were associated with the prognostic factors, and these findings may predict the prognosis of breast cancer

MR imaging of the spine in children

Energy Technology Data Exchange (ETDEWEB)

Duthoy, M.J.; Lund, G.

1988-08-01

MR imaging was reviewed in 66 pediatric spinal cord patients with diagnoses of posterior fossa tumor, primary spinal cord tumor, metastatic disease, neuroectodermal disorder, congenital malformation, trauma, and demyelinating, neurodegenerative, or metabolic disorders. MR proved to be useful in delineating the extent of posterior fossa and cord tumor including metastasis to the cord. MR was of limited value in demyelinating and metabolic disorders. Arnold Chiari malformations, syringomyelia, tethered cord and meningoceles were all easily evaluated using MR.

Value of new MR techniques in MR-PET

International Nuclear Information System (INIS)

Attenberger, U.I.; Schoenberg, S.O.; Quick, H.H.; Guimaraes, A.; Catalano, O.; Morelli, J.N.

2013-01-01

The unparalleled soft tissue contrast of magnetic resonance imaging (MRI) and the functional information obtainable with 18-F fluorodeoxyglucose positron emission tomography (FDG-PET) render MR-PET well-suited for oncological and psychiatric imaging. The lack of ionizing radiation with MRI also makes MR-PET a promising modality for oncology patients requiring frequent follow-up and pediatric patients. Lessons learned with PET computed tomography (CT) over the last few years do not directly translate to MR-PET. For example, in PET-CT the Hounsfield units derived from CT are used for attenuation correction (AC). As 511 keV photons emitted in PET examinations are attenuated by the patient's body CT data are converted directly to linear attenuation coefficients (LAC); however, proton density measured by MRI is not directly related to the radiodensity or LACs of biological tissue. Thus, direct conversion to LAC data is not possible making AC more challenging in simultaneous MRI-PET scanning. In addition to these constraints simultaneous MRI-PET acquisitions also improve on some solutions to well-known challenges of hybrid imaging techniques, such as limitations in motion correction. This article reports on initial clinical experiences with simultaneously acquired MRI-PET data, focusing on the potential benefits and limitations of MRI with respect to motion correction as well as metal and attenuation correction artefacts. (orig.) [de

Field of view extension and truncation correction for MR-based human attenuation correction in simultaneous MR/PET imaging

International Nuclear Information System (INIS)

Blumhagen, Jan O.; Ladebeck, Ralf; Fenchel, Matthias; Braun, Harald; Quick, Harald H.; Faul, David; Scheffler, Klaus

2014-01-01

Purpose: In quantitative PET imaging, it is critical to accurately measure and compensate for the attenuation of the photons absorbed in the tissue. While in PET/CT the linear attenuation coefficients can be easily determined from a low-dose CT-based transmission scan, in whole-body MR/PET the computation of the linear attenuation coefficients is based on the MR data. However, a constraint of the MR-based attenuation correction (AC) is the MR-inherent field-of-view (FoV) limitation due to static magnetic field (B 0 ) inhomogeneities and gradient nonlinearities. Therefore, the MR-based human AC map may be truncated or geometrically distorted toward the edges of the FoV and, consequently, the PET reconstruction with MR-based AC may be biased. This is especially of impact laterally where the patient arms rest beside the body and are not fully considered. Methods: A method is proposed to extend the MR FoV by determining an optimal readout gradient field which locally compensates B 0 inhomogeneities and gradient nonlinearities. This technique was used to reduce truncation in AC maps of 12 patients, and the impact on the PET quantification was analyzed and compared to truncated data without applying the FoV extension and additionally to an established approach of PET-based FoV extension. Results: The truncation artifacts in the MR-based AC maps were successfully reduced in all patients, and the mean body volume was thereby increased by 5.4%. In some cases large patient-dependent changes in SUV of up to 30% were observed in individual lesions when compared to the standard truncated attenuation map. Conclusions: The proposed technique successfully extends the MR FoV in MR-based attenuation correction and shows an improvement of PET quantification in whole-body MR/PET hybrid imaging. In comparison to the PET-based completion of the truncated body contour, the proposed method is also applicable to specialized PET tracers with little uptake in the arms and might reduce the

MR evaluation of brachial plexus injuries

International Nuclear Information System (INIS)

Gupta, R.K.; Jain, R.K.; Mehta, V.S.; Banerji, A.K.

1989-01-01

Ten cases of brachial plexus injury were subjected to magnetic resonance (MR) to demonstrate the roots, trunks, divisions or cord abnormalities. Both normal and abnormal brachial plexuses were imaged in sagittal, axial, coronal and axial oblique planes. Myelography, using water soluble contrast agents, was performed in seven cases. MR demonstrated one traumatic meningocele, one extradural cerebrospinal fluid (CSF) collection, trunk and/or root neuromas in four, focal root fibrosis in two and diffuse fibrosis in the remaining two cases. Results of MR were confirmed at surgery in four cases with neuromas, while myelography was normal in two and was not carried out in the remaining two. In two cases, where MR demonstrated diffuse fibrosis of the brachial plexus, myelography showed C7 and T1 traumatic meningocele in one and was normal in the other. Both these patients showed excellent clinical and electrophysiological correlation with MR findings and in one of them surgical confirmation was also obtained. In the other two cases with focal nerve root fibrosis, myelography was normal in one and showed a traumatic meningocele in another. Operative findings in these cases confirmed focal root fibrosis but no root avulsion was observed although seen on one myelogram. Focal fibrosis, however, was noted at operation in more roots than was observed with MR. Initial experience suggests that MR may be the diagnostic procedure of choice for complete evaluation of brachial plexus injuries. (orig.)

MR imaging of von Hippel-Lindau disease

International Nuclear Information System (INIS)

Sato, Y.; Waziri, M.H.; Smith, W.L.; Frey, E.E.; Franken, E.A.

1986-01-01

Sixteen patients with von Hippel-Lindau disease (VH-L) and 11 asymptomatic family members underwent a total of 29 central nervous system (CNS) and 23 body MR imaging evaluations during a 2-year study period. Nineteen CNS and spinal lesions and nine abdominal visceral lesions were identified on MR imaging and were confirmed at surgery or by other imaging modalities. MR imaging is superior to CT in the evaluation of intraocular vitreous abnormalities and cerebellar and spinal hemangioblastomas because of superior tissue characterization and lack of bone artifacts. MR imaging adequately demonstrated the abdominal visceral lesions. MR imaging is a sensitive and reliable imaging modality for the various lesions of VH-L

Practical Considerations for Clinical PET/MR Imaging.

Science.gov (United States)

Galgano, Samuel; Viets, Zachary; Fowler, Kathryn; Gore, Lael; Thomas, John V; McNamara, Michelle; McConathy, Jonathan

2018-01-01

Clinical PET/MR imaging is currently performed at a number of centers around the world as part of routine standard of care. This article focuses on issues and considerations for a clinical PET/MR imaging program, focusing on routine standard-of-care studies. Although local factors influence how clinical PET/MR imaging is implemented, the approaches and considerations described here intend to apply to most clinical programs. PET/MR imaging provides many more options than PET/computed tomography with diagnostic advantages for certain clinical applications but with added complexity. A recurring theme is matching the PET/MR imaging protocol to the clinical application to balance diagnostic accuracy with efficiency. Copyright © 2017 Elsevier Inc. All rights reserved.

MR imaging of pleural and peritoneal effusion

International Nuclear Information System (INIS)

Shiono, Takahiro; Yoshikawa, Kohki; Takenaka, Eiichi; Hisamatsu, Katsuji

1993-01-01

The purpose of this study was to assess the efficacy of MR imaging in predicting the quality of ascites and pleural effusion. MR examinations of 20 patients with different benign or malignant diseases accompanied with ascites or pleural effusion were retrospectively studied. Results were compared with histopathological findings. On T 1 - and T 2 -weighted images, the MR intensity of the effusion depended mainly on the concentration of protein, whereas on gradient echo images, it depended mainly on the concentration of blood. MR examination was useful in non-invasively differentiating exudative or hemorrhagic effusion from serous effusion. Knowledge or inference of the quality of effusion can direct MR interpretation and may improve diagnostic accuracy. (author)

Changes of renal blood flow after ESWL: Assessment by ASL MR imaging, contrast enhanced MR imaging, and renal resistive index

Energy Technology Data Exchange (ETDEWEB)

Abd Ellah, Mohamed, E-mail: dr_m_hamdy2006@hotmail.co [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Kremser, Christian, E-mail: christian.kremser@i-med.ac.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Pallwein, Leo, E-mail: leo.pallwein-prettner@uki.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Aigner, Friedrich, E-mail: friedrich.Aigner@uki.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Schocke, Michael, E-mail: michael.schocke@i-med.ac.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Peschel, Reinhard, E-mail: reinhard.peschel@uki.a [Innsbruck Medical University, Urology Dept., Anich St. 35, 6020 Innsbruck (Austria); Pedross, Florian, E-mail: florian.pedross@i-med.ac.a [Innsbruck Medical University, Medical Statistics Dept., Anich St. 35, 6020 Innsbruck (Austria); Pinggera, Germar-Michael, E-mail: germar.pinggera@uki.a [Innsbruck Medical University, Urology Dept., Anich St. 35, 6020 Innsbruck (Austria); Wolf, Christian, E-mail: christian.wolf@bkh-reutte.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Alsharkawy, Mostafa A.M., E-mail: drmostafamri@yahoo.co [Assiut University, Radiology Dept., Assiut (Egypt); Jaschke, Werner, E-mail: werner.jaschke@i-med.ac.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Frauscher, Ferdinand, E-mail: ferdinand.frauscher@uki.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria)

2010-10-15

The annual incidence of stone formation is increased in the industrialised world. Extracorporeal shockwave lithotripsy is a non-invasive effective treatment of upper urinary tract stones. This study is aimed to evaluate changes of renal blood flow in patients undergoing extracorporeal shock wave lithotripsy (ESWL) by arterial spin labeling (ASL) MR imaging, contrast enhanced dynamic MR imaging, and renal resistive index (RI). Thirteen patients with nephrolithiasis were examined using MR imaging and Doppler ultrasound 12 h before and 12 h after ESWL. ASL sequence was done for both kidneys and followed by contrast enhanced MR imaging. In addition RI Doppler ultrasound measurements were performed. A significant increase in RI (p < 0.001) was found in both treated and untreated kidneys. ASL MR imaging also showed significant changes in both kidneys (p < 0.001). Contrast enhanced dynamic MR imaging did not show significant changes in the kidneys. ESWL causes changes in RI and ASL MR imaging, which seem to reflect changes in renal blood flow.

MR imaging of the neonatal brain: Pathologic features

International Nuclear Information System (INIS)

McArdle, C.B.; Richardson, C.J.; Nicholas, D.A.; Hayden, C.K.; Amparo, E.G.

1986-01-01

Seventy-three neonates, aged 29-43 weeks since conception, were studied. US and/or CT correlations were obtained in most infants with pathology. In the first 4-5 days after hemorrhage, US and CT were superior to MR imaging, but after that time MR imaging was the single best modality for imaging blood. In early premature infants with very watery white matter, US detected infarction and brain edema that were poorly seen on both MR imaging and CT. However, in late premature and full-term infants, MR imaging was better than CT in distinguishing between normal white matter and infarction. Only MR imaging disclosed delayed myelination in 13 term infants with hydrocephalus and severe asphyxia. MR imaging with play an important role in imaging neonates once MR imaging-compatible monitors and neonatal head coils become widely available

Flair MR imaging in the Detection of subarachnoid hemorrhage : comparison with CT and T1-weighted MR imaging

Energy Technology Data Exchange (ETDEWEB)

Min, Soo Hyun; Kim, Soo Youn; Lee, Ghi Jai; Shim, Jae Chan; Oh, Tae Kyung; Kim, Ho Kyun [College of Medicine, Jnje University, Seoul (Korea, Republic of)

2000-03-01

To compare the findings of fluid-attenuated inversion recovery (FLAIR) MR imaging in the detection of subarachnoid hemorrhage (SAH), with those of precontrast CT and T1-weighted MR imaging. In 13 patients (14 cases) with SAH, FLAIR MR images were retrospectively analyzed and compared with CT (10 patients, 11 cases) and T1-weighted MR images (9 cases). SAH was confirmed on the basis of high density along the subarachnoid space, as seen on precontrast CT, or lumbar puncture. MR imaging was performed on a 1.0T unit. FLAIR MR and CT images were obtained during the acute stage(less than 3 days after ictus) in 10 and 9 cases, respectively, during the subacute stage (4-14 days after ictus) in two cases and one, respectively, and during the chronic stage (more than 15 days after ictus) in two cases and one, respectively. CT was performed before FLAIR MR imaging, and the interval between CT and FLAIR ranged from 24 hours (6 cases) to 2-3 (2 cases) or 4-7 days (3 cases). In each study, the conspicuity of visualization of SAH was graded as excellent, good, fair, or negative at five locations (sylvian fissure, cortical sulci, anterior basal cistern, posterior basal cistern, and perimesencephalic cistern). In all cases, subarachnoid hemorrhages were demonstrated as high signal intensity areas on FLAIR images. The detection rates for SAH on CT and T1-weighted MR images were 100% (11/11) and 89% (8/9), respectively. FLAIR was superior to T1-weighted imaging in the detection of SAH at all sites except the anterior basal cistern (p less than 0.05) and superior to CT in the detection of SAH at the cortical sulci (p less than 0.05). On FLAIR MR images, subarachnoid hemorrhages at all stages are demonstrated as high signal intensity areas; the FLAIR MR sequence is thus considered useful in the detection of SAH. In particular FLAIR is more sensitive than CT for the detection of SAH in the cortical sulci. (author)

Dynamic MR-mammography in invasive lobular breast cancer; Dynamische MR-Mammographie beim invasiv lobulaeren Mammakarzinom bei 1,0 T

Energy Technology Data Exchange (ETDEWEB)

Sittek, H.; Perlet, C.; Kessler, M.; Reiser, M. [Institut fuer Radiologische Diagnostik, Klinikum Grossenhadern, Ludwig-Maximilians-Univ., Muenchen (Germany); Untch, M. [Klinik und Poliklinik fuer Frauenheilkunde und Geburtshilfe, Klinikum Grossenhadern, Ludwig-Maximilians-Univ., Muenchen (Germany)

1998-12-31

Material and Methods: We carried out 1505 MR mammographoes in 1357 patients. Biopsy was indicated in 413 cases. Among the malignancies, 23/214 (10%) were ILC. MR-M was performed with a 1.0 T whole body MRI system with a dynamic FLASH-3D sequence. Relative signal enhancement within lesions detected and morphologic pattern of contrast enhancement (mep) were determined. Three types of mep were distinguished: type 1 without contrast enhancement, type 2 with focal contrast enhancement, and type 3 with diffuse contrast enhancement of the glandular body. Results: Within MR-M alone, 19/23 (82.6%) of ILC were detected due to a mep type 2. Four ILC were false negative on MR-M (2 cases show mep type 1 or mep type 3). The sensitivity of Mx alone was 86.9% (20/23). When both Mx and MR-M were combined, all 23 ILC were detected. The addition of MR-M to Mx may increase sensitivity to about 100% in the detection of ILC. (orig.) [Deutsch] Material und Methode: Im Zeitraum 05/1993 bis 06/1996 fuehrten wir bei 1357 Patientinnen 1505 MR-Mammographien durch. In 413 Faellen wurde eine Probeexzision indiziert. Die histologische Untersuchung ergab in 214 Faellen einen malignen Tumor. Darunter befanden sich 23 ILC. Die MR-M wurden an einem 1,0 T MRT-System (Impact, Siemens, Erlangen) mit einer dynamischen FLASH 3D Sequenz durchgefuehrt. Neben dem prozentualen Anstieg der Signalintensitaet innerhalb einer Laesion haben wir fuer die Diagnostik folgende morphologische Befundmuster (BM) unterschieden: Typ 1: Keine Aufnahme, Typ 2: Fokale Aufnahme, Typ 3: Diffuse Aufnahme des Druesenkoerpers in der MR-M. Ergebnisse: Mit der MR-M konnten 19/23 (82,6%) der ILC anhand einer fokalen Zunahme der Signalintensitaet richtig positiv erkannt werden (BM Typ 2). Vier der ILC waren in der MR-M falsch negativ. In zwei Faellen (2/23) war keine Zunahme der Signalintensitaet zu verzeichnen (BM Typ 1). In zwei weiteren Faellen (2/23) maskierte eine diffuse Signalintensitaetszunahme des Druesenkoerpers (BM Typ 3

Feasibility of MR-guided angioplasty of femoral artery stenoses using real-time imaging and intraarterial contrast-enhanced MR angiography

International Nuclear Information System (INIS)

Paetzel, C.; Zorger, N.; Bachthaler, M.; Voelk, M.; Seitz, J.; Herold, T.; Feuerbach, S.; Lenhart, M.; Nitz, W.R.

2004-01-01

Purpose: To show the feasibility of magnetic resonance (MR) for guided interventional therapy of femoral and popliteal artery stenoses with commercially available materials supported by MR real-time imaging and intraarterial MR angiography. Materials and Methods: Three patients (1 female, 2 male), suffering from symptomatic arterial occlusive disease with stenoses of the femoral (n=2) or popliteal (n=1) arteries were included. Intraarterial digital subtraction angiography was performed in each patient pre- and post-interventionally as standard of reference to quantify stenoses. The degree of the stenoses reached from 71-88%. The MR images were acquired on a 1.5 T MR scanner (Magnetom Sonata; Siemens, Erlangen, Germany). For MR-angiography, a Flash 3D sequence was utilized following injection of 5 mL diluted gadodiamide (Omniscan; Amersham Buchler, Braunschweig, Germany) via the arterial access. Two maximum intensity projections (MIP) were used as road maps and localizer for the interactive positioning of a continuously running 2D-FLASH sequence with a temporal solution of 2 images per second. During the intervention, an MR compatible monitor provided the image display inside the scanner room. Safety guidelines were followed during imaging in the presence of a conductive guidewire. The lesion was crossed by a commercially available balloon catheter (Wanda, Boston Scientific; Ratingen, Germany), which was mounted on a 0.035'' guidewire (Terumo; Leuven, Belgium). The visibility was provided by radiopaque markers embedded in the balloon and was improved by injection of 1 mL gadodiamide into the balloon. After dilation, the result was checked by intraarterial MR angiography and catheter angiography. Results: The stenoses could be correctly localized by intraarterial MR angiography. There was complete correlation between intraarterial MR angiography and digital subtraction angiography. The combination of guidewire and balloon was visible and the balloon was placed

Brain MR imaging in systemic lupus erythematous

Energy Technology Data Exchange (ETDEWEB)

Park, Hyun Ae; Chang, Kee Hyun; Han, Moon Hee; Lee, Kyung Hwon; Kim, Sung Kwon; Lee, Jung Sang [Seoul National University College of Medicine, Seoul (Korea, Republic of); Cha, Sang Hoon [Chungbuk National University College of Medicine, Chungju (Korea, Republic of)

1992-09-15

To present MR imaging findings of intracranial lesions in systemic lupus erythematosus(SLE), a retrospective study was performed on MR images of 33 SLE patients with neurologic symptoms and signs. MR imaging was performed on either a 0.5 T (21 patients) or 2.0 T unit (12 patients), using T1-weighted, proton-density-weighted, and T2-weighted spin echo sequences in all patients. In seven patients, post-contrast T1-weighted images were also obtained after administration of gadopentetate dimeglumine. The main MR findings consisted of focal lesions suggesting ischemia/infarct (15 patients), diffuse brain atrophy (8), and findings associated with infection (4). The MR findings were normal in 11 patients (33%). The focal lesions suggesting ischemia/infarcts presumably secondary to vasculitis were distributed in the cortex or subcortical white matter (7 patients), deep periventricular white matter (3), or in both areas (5). Most of the focal lesions were multiple and small in size. The findings associated with infection were variable and included communicating hydrocephalus, meningeal enhancement, granuloma, etc. MR findings of SLE were non-specific and therefore clinical correlation is needed when evaluating SLE in MR.

Rosen's (M,R) system in process algebra.

Science.gov (United States)

Gatherer, Derek; Galpin, Vashti

2013-11-17

Robert Rosen's Metabolism-Replacement, or (M,R), system can be represented as a compact network structure with a single source and three products derived from that source in three consecutive reactions. (M,R) has been claimed to be non-reducible to its components and algorithmically non-computable, in the sense of not being evaluable as a function by a Turing machine. If (M,R)-like structures are present in real biological networks, this suggests that many biological networks will be non-computable, with implications for those branches of systems biology that rely on in silico modelling for predictive purposes. We instantiate (M,R) using the process algebra Bio-PEPA, and discuss the extent to which our model represents a true realization of (M,R). We observe that under some starting conditions and parameter values, stable states can be achieved. Although formal demonstration of algorithmic computability remains elusive for (M,R), we discuss the extent to which our Bio-PEPA representation of (M,R) allows us to sidestep Rosen's fundamental objections to computational systems biology. We argue that the behaviour of (M,R) in Bio-PEPA shows life-like properties.

MR-guided joint reconstruction of activity and attenuation in brain PET-MR

DEFF Research Database (Denmark)

Mehranian, Abolfazl; Zaidi, Habib; Reader, Andrew J

2017-01-01

by unknown scaling factors. We recently demonstrated that in hybrid PET-MR, the scaling issue of this algorithm can be effectively addressed by imposing MR spatial constraints on the estimation of attenuation maps using a penalized MLAA (P-MLAA(+)) algorithm. With the advent of simultaneous PET-MR systems......, MRI-guided PET image reconstruction has also gained attention for improving the quantitative accuracy of PET images, usually degraded by noise and partial volume effects. The aim of this study is therefore to increase the benefits of MRI information for improving the quantitative accuracy of PET...... as a reference. The simulation results showed that the proposed method can notably improve the visual quality of the PET images by reducing noise while preserving structural boundaries and at the same time improving the quantitative accuracy of the PET images. Our clinical reconstruction results showed...

Does MR imaging effectively replace diagnostic arthroscopy

International Nuclear Information System (INIS)

Ruwe, P.; McCarthy, S.; Wright, J.; Randall, L.; Lynch, K.; Jokyl, P.

1990-01-01

This paper determines if MR imaging reduces the number of diagnostic arthroscopic procedures required in patients with knee complaints and if MR imaging is cost-effective compared with diagnostic arthroscopy. The cohort analysis consists of 100 patients seen in a sports medicine clinic by two orthopedic surgeons who agreed on well-defined criteria for performing MR imaging and arthroscopy. Each orthopedic surgeon referring a patient for MR imaging checked a form regarding the plans for arthroscopy. Outcome analysis was conducted at 6 months

Prostate cancer: a comparative study of {sup 11}C-choline PET and MR imaging combined with proton MR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Yamaguchi, Takako; Lee, Jin; Takahashi, Nobukazu; Oka, Takashi; Shizukuishi, Kazuya; Inoue, Tomio [Yokohama City University School of Medicine, Department of Radiology, Yokohama (Japan); Uemura, Hiroji; Kubota, Yoshinobu [Yokohama City University School of Medicine, Department of Urology, Kanagawa (Japan); Sasaki, Takeshi [Yokohama City University School of Medicine, Department of Pathology, Kanagawa (Japan); Endou, Hisashi [Yokohama City University School of Medicine, Department of Pharmacy, Kanagawa (Japan)

2005-07-01

Prostate cancer is difficult to visualise in its early stages using current imaging technology. The present study aimed to clarify the utility of {sup 11}C-choline PET for localising and evaluating cancer lesions in patients with prostate cancer by conducting a prospective comparison with magnetic resonance (MR) imaging combined with proton MR spectroscopy. PET and MR imaging combined with proton MR spectroscopy were performed in 20 patients with prostate cancer. Correlations among the metabolite ratio of choline + creatine to citrate (Cho+Cr/Ci) on MR spectroscopy, serum PSA and maximum standardised uptake value (SUV{sub max}) of {sup 11}C-choline were assessed. The location of the primary lesion was assessed by the site of SUV{sub max} and the laterality of the highest Cho+Cr/Ci ratio and confirmed by examination of surgical pathology specimens (n=16). PET exhibited a diagnostic sensitivity of 100% (20/20) for primary lesions, while the sensitivities of MR imaging and MR spectroscopy were 60% (12/20) and 65% (13/20), respectively. Weak linear correlations were observed between SUV{sub max} and serum PSA (r=0.52, p<0.05), and between SUV{sub max} and Cho+Cr/Ci ratio (r=0.49, p<0.05). Regarding the localisation of main primary lesions, PET results agreed with pathological findings in 13 patients (81%) ({kappa}=0.59), while MR spectroscopy results were in accordance with pathological findings in eight patients (50%) ({kappa}=0.11). This preliminary study suggests that {sup 11}C-choline PET may provide more accurate information regarding the localisation of main primary prostate cancer lesions than MR imaging/MR spectroscopy. A further clinical study of {sup 11}C-choline PET in a large number of patients suspected of prostate cancer will be necessary to determine the clinical utility of {sup 11}C-choline PET in patients who clinically require biopsy. (orig.)

MR imaging features of craniodiaphyseal dysplasia

Energy Technology Data Exchange (ETDEWEB)

Marden, Franklin A. [Mallinckrodt Institute of Radiology, Washington University Medical Center, 510 South Kingshighway Blvd., MO 63110, St. Louis (United States); Department of Radiology, St. Louis Children' s Hospital, Children' s Place, MO 63110, St. Louis (United States); Wippold, Franz J. [Mallinckrodt Institute of Radiology, Washington University Medical Center, 510 South Kingshighway Blvd., MO 63110, St. Louis (United States); Department of Radiology, St. Louis Children' s Hospital, Children' s Place, MO 63110, St. Louis (United States); Department of Radiology/Nuclear Medicine, F. Edward Hebert School of Medicine, Uniformed Services University of the Health Sciences, MD 20814, Bethesda (United States)

2004-02-01

We report the magnetic resonance (MR) imaging findings in a 4-year-old girl with characteristic radiographic and computed tomography (CT) features of craniodiaphyseal dysplasia. MR imaging exquisitely depicted cranial nerve compression, small foramen magnum, hydrocephalus, and other intracranial complications of this syndrome. A syrinx of the cervical spinal cord was demonstrated. We suggest that MR imaging become a routine component of the evaluation of these patients. (orig.)

MR arthrography: how I do it

International Nuclear Information System (INIS)

Bankaoglu, M.

2012-01-01

Full text: Magnetic resonance imaging has to rely on improving new various sequences and techniques and to get the best imaging quality so magnetic resonance (MR) arthrography is one of the most important technique in the assessment of selected musculoskeletal disorders. It is now widely utilized and considered by most musculoskeletal radiologists and some orthopedists to be an integral part of their clinical practice. The technique include: desired degree of joint distension with contrast medium; markedly improved imaging quality of intra-articular structures with the direct delineation so improved detection of pathology with MRI. As appliance and technique of MR arthrography is completely based on traditional arthrography of X ray. In MR arthrography additional very little amount of Gadolinium based contrast agent is added to the desired mixture of contrast material injected to the joint. As in conventional radiography MR arthrography is used to get extra information for conventional MRI . Practically any joint that can be accessed by a needle can be imaged using MR arthrography but it has been applied to limited number of joints to compare with the traditional arthrography so shoulder, knee, wrist, elbow, ankle, and hip are mostly subjects to do in MR arthrography. The procedure is also less invasive and expensive rather than diagnostic arthroscopy and should carefully indicated because it is not completely noninvasive technique so previous imaging modalities and MRI of the patients should be completed and evaluated well. During or after the procedure there has been no major complication reported by so far but more than two third of patients are known to complain some degree of pain right after or several times later than the procedure. As it is more than twenty years now it has been widely accepted helpful for diagnosis and adds some extra sensitivity to conventional MRI . Up to this time MR arthrography has proven to increase sensitivity of conventional MRI in

Subtraction MR venography acquired from time-resolved contrast-enhanced MR angiography: Comparison with phase-contrast MR venography and single-phase contrast-enhanced MR venography

International Nuclear Information System (INIS)

Jang, Jin Hee; Kim, Bum Soo; KIm, Bom Yi; Choi, Hyun Seok; Jung, So Lyung; Ahn, Kook Jin; Sung, Ji Kyeong

2015-01-01

To evaluate the image characteristics of subtraction magnetic resonance venography (SMRV) from time-resolved contrast-enhanced MR angiography (TRMRA) compared with phase-contrast MR venography (PCMRV) and single-phase contrast-enhanced MR venography (CEMRV). Twenty-one patients who underwent brain MR venography (MRV) using standard protocols (PCMRV, CEMRV, and TRMRA) were included. SMRV was made by subtracting the arterial phase data from the venous phase data in TRMRA. Co-registration and subtraction of the two volume data was done using commercially available software. Image quality and the degree of arterial contamination of the three MRVs were compared. In the three MRVs, 19 pre-defined venous structures (14 dural sinuses and 5 cerebral veins) were evaluated. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the three MRVs were also compared. Single-phase contrast-enhanced MR venography showed better image quality (median score 4 in both reviewers) than did the other two MRVs (p < 0.001), whereas SMRV (median score 3 in both reviewers) and PCMRV (median score 3 in both reviewers) had similar image quality (p ≥ 0.951). SMRV (median score 0 in both reviewers) suppressed arterial signal better than did the other MRVs (median score 1 in CEMRV, median score 2 in PCMRV, both reviewers) (p < 0.001). The dural sinus score of SMRV (median and interquartile range [IQR] 48, 43-50 for reviewer 1, 47, 43-49 for reviewer 2) was significantly higher than for PCMRV (median and IQR 31, 25-34 for reviewer 1, 30, 23-32 for reviewer 2) (p < 0.01) and did not differ from that of CEMRV (median and IQR 50, 47-52 for reviewer 1, 49, 45-51 for reviewer 2) (p = 0.146 in reviewer 1 and 0.123 in reviewer 2). The SNR and CNR of SMRV (median and IQR 104.5, 83.1-121.2 and 104.1, 74.9-120.5, respectively) were between those of CEMRV (median and IQR 150.3, 111-182.6 and 148.4, 108-178.2) and PCMRV (median and IQR 59.4, 49.2-74.9 and 53.6, 43.8-69.2). Subtraction magnetic

Multipurpose simulator ''MR TRIOS'' for reprocessing plant

International Nuclear Information System (INIS)

Mitsui, Takeshi; Uehara, Shigeru; Takata, Hideo; Kamishima, Naoyuki

1993-01-01

MHI (Mitsubishi Heavy Industries) has developed MR TRIOS (Mitsubishi Reprocessing plant TRansient simulation code for Integrated process for Operation Support), the realtime dynamic simulator, for multipurpose use to support the Reprocessing Plant operation in various aspects. MR TRIOS integrates the Simulation Models of the unit process in a Reprocessing Plant, including Shearing, Dissolution, NOx absorption, Accountability and Adjustment and Co-decontamination process, where each Simulation Model has two kinds of models: Process and Control System. MR TRIOS can simulate the process behavior of the unit process in an integrated manner as well as independently. It is supported by MR CONTROL, the simulator control program developed by MHI. From MR TRIOS one can obtain real-time process values, such as temperature, pressure, density, flow rate, and concentration of nuclides, enabling the evaluation of the process dynamic characteristics under various operating conditions. MR TRIOS has proved to be an effective tool for the comprehensive study of the process and system dynamics, for operation technique improvements and for training

High-field MR imaging of tethered cord

International Nuclear Information System (INIS)

Sigal, R.; Bicetre, L.; Blass, C.; Doyon, D.; Pariente, D.

1986-01-01

MR imaging examinations of 12 patients with tethered cord syndrome have been performed on a 1.5-T MR imaging unit. Patients ranged in age from 3 to 60 years. MR findings were compared with those of myelography and metrizamide CT in all cases. Five patients underwent surgical control and postoperative MR imaging. Sagittal and axial sections were obtained using a spin-echo multisection, multiecho technique. T1-axial weighted images (SE 600/25) were sufficient to locate the position of the tip of the conus. They also allowed identification of extraspinal and intraspinal lipomas and clear-cut demarcation form associated tethered cord. Drawbacks of MR imaging were lack of precise depiction of the bone structures and the fact that clear identification of abnormal roots was problematic. The craniovertebral junction was always checked; two asymptomatic Chiari malformations were visualized. This study leads the authors to conclude that MR imaging should be used as the examination of first choice in the management of tethered cord syndrome

MR imaging of posttraumatic spinal ligament injury

International Nuclear Information System (INIS)

Pathria, M.N.; Emery, S.; Masaryk, T.J.; Wilber, R.G.; Bohlman, H.

1988-01-01

The accuracy of MR imaging in the detection of ligamentous injury was evaluated in 29 patients (24 male, five female) with spinal injury resulting in fractures (n=27), evidence of instability (n=11), or neurologic deficit (n=2). MR examinations were performed acutely (average, 7.5 days posttrauma) with T1- and T2-weighted imaging and were blindly evaluated. Subsequently, plain films (n=27), tomograms (n=10), and CT scans (n=22) were evaluated. Eighteen patients underwent surgery. Fourteen patients had torn ligaments as indicated by clinical and surgical findings. MR imaging demonstrated ligament damage in 13. One case imaged 40 days following trauma was not detected. No patients with intact ligaments had evidence of ligamentous damage on MR images. MR imaging demonstrated retropulsed fractures in six patients in whom the posterior longitudinal ligament was intact but displaced from the vertebra. MR imaging was more reliable than radiography and CT for detection of ligamentous injury, and T2- weighted sequences are essential in such cases

Dynamic MR imaging of the musculoskeletal system

International Nuclear Information System (INIS)

Shah, A.S.; Hylton, H.; Hentz, V.R.; Schattner, P.

1991-01-01

This paper reports on dynamic MR imaging which is an MR technique that allows imaging of the musculoskeletal system in motion. Current methods for observing the articulation of muscles and joints are limited to acquisition of stationary images at different spatial orientations. These images are then replayed from computer memory to simulate motion. Unlike stationary acquisition, dynamic MR imaging allows the volume of interest to be subjected to motion and dynamic stress, which is important for detecting stress-induced pathology. To demonstrate the utility of dynamic MR imaging, a system for imaging a moving wrist has been developed. The system consists of apparatus capable of providing simultaneous radialulnar deviation and flexion-extension, and hardware for system control and acquisition gating. The apparatus is mounted on the patient bed and is transferable to a variety of standard clinical MR imaging systems. Images were obtained during motion, and the ability of dynamic MR imaging to accurately image the moving wrist with very little motion artifact was demonstrated

MR guided spatial normalization of SPECT scans

International Nuclear Information System (INIS)

Crouch, B.; Barnden, L.R.; Kwiatek, R.

2010-01-01

Full text: In SPECT population studies where magnetic resonance (MR) scans are also available, the higher resolution of the MR scans allows for an improved spatial normalization of the SPECT scans. In this approach, the SPECT images are first coregistered to their corresponding MR images by a linear (affine) transformation which is calculated using SPM's mutual information maximization algorithm. Non-linear spatial normalization maps are then computed either directly from the MR scans using SPM's built in spatial normalization algorithm, or, from segmented TI MR images using DARTEL, an advanced diffeomorphism based spatial normalization algorithm. We compare these MR based methods to standard SPECT based spatial normalization for a population of 27 fibromyalgia patients and 25 healthy controls with spin echo T 1 scans. We identify significant perfusion deficits in prefrontal white matter in FM patients, with the DARTEL based spatial normalization procedure yielding stronger statistics than the standard SPECT based spatial normalization. (author)

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

Quantification of hepatic steatosis with T1-independent, T2-corrected MR imaging with spectral modeling of fat: blinded comparison with MR spectroscopy.

Science.gov (United States)

Meisamy, Sina; Hines, Catherine D G; Hamilton, Gavin; Sirlin, Claude B; McKenzie, Charles A; Yu, Huanzhou; Brittain, Jean H; Reeder, Scott B

2011-03-01

To prospectively compare an investigational version of a complex-based chemical shift-based fat fraction magnetic resonance (MR) imaging method with MR spectroscopy for the quantification of hepatic steatosis. This study was approved by the institutional review board and was HIPAA compliant. Written informed consent was obtained before all studies. Fifty-five patients (31 women, 24 men; age range, 24-71 years) were prospectively imaged at 1.5 T with quantitative MR imaging and single-voxel MR spectroscopy, each within a single breath hold. The effects of T2 correction, spectral modeling of fat, and magnitude fitting for eddy current correction on fat quantification with MR imaging were investigated by reconstructing fat fraction images from the same source data with different combinations of error correction. Single-voxel T2-corrected MR spectroscopy was used to measure fat fraction and served as the reference standard. All MR spectroscopy data were postprocessed at a separate institution by an MR physicist who was blinded to MR imaging results. Fat fractions measured with MR imaging and MR spectroscopy were compared statistically to determine the correlation (r(2)), and the slope and intercept as measures of agreement between MR imaging and MR spectroscopy fat fraction measurements, to determine whether MR imaging can help quantify fat, and examine the importance of T2 correction, spectral modeling of fat, and eddy current correction. Two-sided t tests (significance level, P = .05) were used to determine whether estimated slopes and intercepts were significantly different from 1.0 and 0.0, respectively. Sensitivity and specificity for the classification of clinically significant steatosis were evaluated. Overall, there was excellent correlation between MR imaging and MR spectroscopy for all reconstruction combinations. However, agreement was only achieved when T2 correction, spectral modeling of fat, and magnitude fitting for eddy current correction were used (r(2

MR imaging of the shoulder

International Nuclear Information System (INIS)

Heuck, A.; Appel, M.; Kaiser, E.; Luttke, G.; Lukas, P.

1990-01-01

This paper evaluates the occurrence, frequency, and significance of increased signal intensity (SI) in the rotator cuff (RC) of normal volunteers suggestive of pathologic findings such as partial tears and tendinitis. Shoulders of 30 volunteers without evidence of prior shoulder disease or trauma were studied. MR imaging at 1.5 T included T1-weighted, proton-density, and T2-weighted spin-echo (SE) and T2*-weighted gradient-echo sequences in axial, oblique coronal, and sagittal planes. Shoulders of 30 cadavers were dissected and studied for correlation with MR findings, five of them after MR examination

Evaluation of Marfan syndrome: MR imaging versus CT

International Nuclear Information System (INIS)

Soulen, R.L.; Fishman, E.K.; Pyeritz, R.E.; Gott, V.L.; Zerhouni, E.A.

1986-01-01

Twenty-five patients with Marfan, syndrome underwent both CT and MR imaging. MR imaging were interpreted in blinded fashion and then compared with CT scans MR imaging was found to be equivalent to CT in the detection of aortic, dural, and hip abnormalities in patients not operated on. MR imaging was superior to CT in the evaluation of postoperative patients because the artifact produced by Bjork-Shirley or St. Jude valves precludes adequate evaluation of the aortic root on CT while producing only a small inferior field distortion (a ''pseudo-ventricular septal defect'') on MR imaging. The absence of radiation exposure is another major advantage of MR imaging in this relatively young population requiring serial studies. The authors conclude that MR imaging is the modality of choice for the evaluation and follow-up of patients with Marfan syndrome and offers an appropriate means of screening their kindred

How to perform and interpret cine MR enterography.

Science.gov (United States)

Wnorowski, Amelia M; Guglielmo, Flavius F; Mitchell, Donald G

2015-11-01

Magnetic resonance (MR) enterography has become a fundamental tool for small bowel evaluation. Multiphasic cine imaging is a useful component of MR enterography evaluation because it provides functional information about bowel motility. Cine MR enterography can be used to evaluate for strictures and adhesions. Bowel motility evaluation has been shown to increase pathologic lesion detection in Crohn's disease and has been incorporated into disease activity scoring systems. Currently, cine MR enterography remains underutilized. The purpose of this article is to outline how to perform and interpret cine MR enterography. The authors describe how to perform a multiphasic balanced steady state free precession sequence using different MR systems and give practical advice on how to display and interpret the cine sequence. Sample cases illustrate how the cine sequence complements standard MR enterography evaluation with T2 -weighted, contrast-enhanced T1 -weighted, and diffusion-weighted imaging. © 2015 Wiley Periodicals, Inc.

MR findings of cerebral palsy

International Nuclear Information System (INIS)

Yoon, Sang Hum; Chang, Seung Kuk; Cho, Mee Young; Park, Dong Woo; Kim, Jong Deok; Eun, Choong Ki

1994-01-01

To evaluate the MR findings of brain damage in cerebral palised patients and to correlate it with gestational age and the time of damage. A retrospective analysis was performed in 40 patients who underwent MR scanning for evaluation of brain lesion in clinically diagnosed cerebral palsy. Authors classified the patients into two groups as premature and full-term and compared MR findings of the two groups. Abnormal MR findings were noted in 28 cases (70%). Five out of 6 patients who had been born prematurely showed isolate periventricular white matter lesions. Twenty-three out of 34 patients who had been born at full-term showed abnormal MR findings. Of these 23 patients, migration anomalies in 7 patients, isolate periventricular white matter lesions in 3 patients, and other combined periventricular subcortical white matter and deep gray matter lesions in 14 patients were seen. At least, 10 patients(43%) of full term group showed abnormal MRI findings reflecting intrauterine brain damage and all 5 patients of premature group showed isolate periventricular white matter lesions suggesting immaturity of brain. MRI is thought to be very useful in the assessment of brain damage for the patients with cerebral palsy by recognizing the location of the lesion and estimating the time of damage

MR findings of cerebral palsy

Energy Technology Data Exchange (ETDEWEB)

Yoon, Sang Hum; Chang, Seung Kuk; Cho, Mee Young; Park, Dong Woo; Kim, Jong Deok; Eun, Choong Ki [Pusan Paik Hospital, Pusan (Korea, Republic of)

1994-11-15

To evaluate the MR findings of brain damage in cerebral palised patients and to correlate it with gestational age and the time of damage. A retrospective analysis was performed in 40 patients who underwent MR scanning for evaluation of brain lesion in clinically diagnosed cerebral palsy. Authors classified the patients into two groups as premature and full-term and compared MR findings of the two groups. Abnormal MR findings were noted in 28 cases (70%). Five out of 6 patients who had been born prematurely showed isolate periventricular white matter lesions. Twenty-three out of 34 patients who had been born at full-term showed abnormal MR findings. Of these 23 patients, migration anomalies in 7 patients, isolate periventricular white matter lesions in 3 patients, and other combined periventricular subcortical white matter and deep gray matter lesions in 14 patients were seen. At least, 10 patients(43%) of full term group showed abnormal MRI findings reflecting intrauterine brain damage and all 5 patients of premature group showed isolate periventricular white matter lesions suggesting immaturity of brain. MRI is thought to be very useful in the assessment of brain damage for the patients with cerebral palsy by recognizing the location of the lesion and estimating the time of damage.

MR imaging of spinal trauma

International Nuclear Information System (INIS)

Buchberger, W.; Springer, P.; Birbamer, G.; Judmaier, W.; Kathrein, A.; Daniaux, H.

1995-01-01

To assess the value of MR imaging in the acute and chronic stages of spinal trauma. 126 MR examinations of 120 patients were evaluated retrospectively. In 15 cases of acute spinal cord injury, correlation of MR findings with the degree of neurological deficit and eventual recovery was undertaken. Cord anomalies in the acute stage were seen in 16 patients. Intramedullary haemorrhage (n=6) and cord transection (n=2) were associated with complete injuries and poor prognosis, whereas patients with cord oedema (n=7) had incomplete injuries and recovered significant neurological function. In the chronic stage, MR findings included persistent cord compression in 8 patients, syringomyelia or post-traumatic cyst in 12, myelomalacia in 6, cord atrophy in 9, and cord transection in 7 patients. In acute spinal trauma, MR proved useful in assessing spinal cord compression and instability. In addition, direct visualisation and characterisation of posttraumatic changes within the spinal cord may offer new possibilities in establishing the prognosis for neurological recovery. In the later stages, potentially remediable causes of persistent or progressive symptoms, such as chronic spinal cord compression or syringomyelia can be distinguished from other sequelae of spinal trauma, such as myelomalacia, cord transection or atrophy. (orig.) [de

Role of MR imaging in chronic wrist pain

Energy Technology Data Exchange (ETDEWEB)

Zanetti, Marco; Saupe, Nadja [University Hospital Balgrist, Department of Radiology, Zurich (Switzerland); Nagy, Ladislav [University Hospital Balgrist, Department of Orthopedic Surgery, Zurich (Switzerland)

2007-04-15

Magnetic resonance (MR) imaging for chronic wrist pain is challenging. Correct assessment of the triangular fibrocartilage, hyaline cartilage, ligaments, and tendons has become mandatory for comprehensive decision making in wrist surgery. The MR technique, potential and limits of MR imaging in patients with chronic wrist pain will be discussed. MR arthrography with injection of gadolinium-containing contrast material into the distal radioulnar joint is suggested for evaluation of the triangular fibrocartilage. The clinically meaningful ulnar-sided peripheral tears are otherwise hard to diagnose. The diagnostic performance of MR imaging for interosseous ligament tears varies considerably. The sensitivity for scapholunate ligament tears is consistently better than for lunotriquetral ligament tears. Gadolinium-enhanced MR imaging is considered to be the best technique for detecting established avascularity of bone, but the assessment of the MR results remains challenging. Most cases of ulnar impaction syndrome have characteristic focal signal intensity changes in the ulnar aspect of the lunate. Avascular necrosis of the lunate (Kienboeck's disease) is characterized by signal changes starting in the proximal radial aspect of the lunate. MR imaging is extremely sensitive for occult fractures. Questions arise if occult posttraumatic bone lesions seen on MR images only necessarily require the same treatment as fractures evident on plain films or computed tomography (CT) images. MR imaging and ultrasound are equally effective for detecting occult carpal ganglia. Carpe bossu (carpal boss) is a bony protuberance of a carpometacarpal joint II and III which may be associated with pain. (orig.)

Role of MR imaging in chronic wrist pain

International Nuclear Information System (INIS)

Zanetti, Marco; Saupe, Nadja; Nagy, Ladislav

2007-01-01

Magnetic resonance (MR) imaging for chronic wrist pain is challenging. Correct assessment of the triangular fibrocartilage, hyaline cartilage, ligaments, and tendons has become mandatory for comprehensive decision making in wrist surgery. The MR technique, potential and limits of MR imaging in patients with chronic wrist pain will be discussed. MR arthrography with injection of gadolinium-containing contrast material into the distal radioulnar joint is suggested for evaluation of the triangular fibrocartilage. The clinically meaningful ulnar-sided peripheral tears are otherwise hard to diagnose. The diagnostic performance of MR imaging for interosseous ligament tears varies considerably. The sensitivity for scapholunate ligament tears is consistently better than for lunotriquetral ligament tears. Gadolinium-enhanced MR imaging is considered to be the best technique for detecting established avascularity of bone, but the assessment of the MR results remains challenging. Most cases of ulnar impaction syndrome have characteristic focal signal intensity changes in the ulnar aspect of the lunate. Avascular necrosis of the lunate (Kienboeck's disease) is characterized by signal changes starting in the proximal radial aspect of the lunate. MR imaging is extremely sensitive for occult fractures. Questions arise if occult posttraumatic bone lesions seen on MR images only necessarily require the same treatment as fractures evident on plain films or computed tomography (CT) images. MR imaging and ultrasound are equally effective for detecting occult carpal ganglia. Carpe bossu (carpal boss) is a bony protuberance of a carpometacarpal joint II and III which may be associated with pain. (orig.)

Multidisciplinary Functional MR Imaging for Prostate Cancer

International Nuclear Information System (INIS)

Kim, Jeong Kon; Jang, Yun Jin; Cho, Gyung Goo

2009-01-01

Various functional magnetic resonance (MR) imaging techniques are used for evaluating prostate cancer including diffusion-weighted imaging, dynamic contrast- enhanced MR imaging, and MR spectroscopy. These techniques provide unique information that is helpful to differentiate prostate cancer from non-cancerous tissue and have been proven to improve the diagnostic performance of MRI not only for cancer detection, but also for staging, post-treatment monitoring, and guiding prostate biopsies. However, each functional MR imaging technique also has inherent challenges. Therefore, in order to make accurate diagnoses, it is important to comprehensively understand their advantages and limitations, histologic background related with image findings, and their clinical relevance for evaluating prostate cancer. This article will review the basic principles and clinical significance of functional MR imaging for evaluating prostate cancer

Drug-induced MR urography: the effects of furosemide and intravenous saline injection on MR urography of obstructed and non-obstructed urinary tract

Energy Technology Data Exchange (ETDEWEB)

Park, Jeong Ha; Lee, Myung Jun; Lee, Chang Joon [National Medical Center, Seoul (Korea, Republic of)

2001-10-01

To determine the usefulness of MR urography technique for the evaluation of urinary systems in patients with obstructed urinary tract and normal volunteers with non-obstructed urinary tract after intravenous normal saline and diuretic injection. Three normal volunteers and 12 patients with urinary tract obstruction [ureteral calculi (n=8), extraurinary mass (n=1), ureteral tumor invasion (n=3)] underwent MR urography using a 1.0T scanner and a 2D non-breath-hold heavily T2-weighted fast spin-cho sequence. These acquisition were post-processed with a maximum intensity projection (MIP) algorithm. Two acquisitions were performed, the first prior to saline solution infusion following standard MR urography procedures, and the second, within 2-3 minutes of the infusion of 250 ml saline solution followed by 20 mg of Lasix administered intravenously. For this latter, drug-induced MR urography procedures were followed. In healthy volunteer (n=3) and those experiencing partial obstruction (n=4) by a urinary stone, drug-induced MR urography provided better images of the urinary tract than did standard MR urography. In those in whom a urinary stone or tumor had caused complete obstruction (n=8), standard MR urography provided good images, as did drug-induced MR urography. In patients with a partially or non-obstructed urinary tract, drug-induced MR urography provided better anatomic and functional details of the kidney and urinary tract than did standard MR urography. In those experiencing complete obstruction of the urinary tract, however, standard or drug-induced MR urography permitted very adequate evaluation of the tract, and drug-induced MR urography was unnecessary.

Intravascular (catheter) MR imaging

International Nuclear Information System (INIS)

Cohen, A.M.; Hurst, G.C.; Katz, D.E.; Dverk, J.L.; Wiesen, E.J.; Czerski, L.W.; Malaya, R.; Bellon, E.M.

1989-01-01

Intravascular MR probes allow excellent spatial resolution and have the potential to detect arterial wall microstructure. Ultrasonic intravascular probes suggest that detailed morphologic information can assist clinical decision making. Catheter MR probes of 2--7 mm outside diameter (OD) were built of copper wire, Teflon, and parts from standard commercial catheters. The probes were connected to the surface coil receiver input of our Picker VISTA 2055HP 1.5-T imaging system. The extant (linear) body coil was used for transmit. Phantoms were constructed of coaxial glass MR tubes, filled with doped water. Watanabe rabbit aorta and human autopsy iliac artery specimens were examined within 4 hours of excision or stored by freezing. In vivo iliac arteries in dogs under general anesthesia were imaged, with percutaneous placement of the probe. Results are presented

Detection of common bile duct stones: comparison between endoscopic ultrasonography, magnetic resonance cholangiography, and helical-computed-tomographic cholangiography

International Nuclear Information System (INIS)

Kondo, Shintaro; Isayama, Hiroyuki; Akahane, Masaaki; Toda, Nobuo; Sasahira, Naoki; Nakai, Yosuke; Yamamoto, Natsuyo; Hirano, Kenji; Komatsu, Yutaka; Tada, Minoru; Yoshida, Haruhiko; Kawabe, Takao; Ohtomo, Kuni; Omata, Masao

2005-01-01

Objectives: New modalities, namely, endoscopic ultrasonography (EUS), magnetic resonance cholangiopancreatography (MRCP), and helical computed-tomographic cholangiography (HCT-C), have been introduced recently for the detection of common bile duct (CBD) stones and shown improved detectability compared to conventional ultrasound or computed tomography. We conducted this study to compare the diagnostic ability of EUS, MRCP, and HCT-C in patients with suspected choledocholithiasis. Methods: Twenty-eight patients clinically suspected of having CBD stones were enrolled, excluding those with cholangitis or a definite history of choledocholithiasis. Each patient underwent EUS, MRCP, and HCT-C prior to endoscopic retrograde cholangio-pancreatography (ERCP), the result of which served as the diagnostic gold standard. Results: CBD stones were detected in 24 (86%) of 28 patients by ERCP/IDUS. The sensitivity of EUS, MRCP, and HCT-C was 100%, 88%, and 88%, respectively. False negative cases for MRCP and HCT-C had a CBD stone smaller than 5 mm in diameter. No serious complications occurred while one patient complained of itching in the eyelids after the infusion of contrast agent on HCT-C. Conclusions: When examination can be scheduled, MRCP or HCT-C will be the first choice because they were less invasive than EUS. MRCP and HCT-C had similar detectability but the former may be preferable considering the possibility of allergic reaction in the latter. When MRCP is negative, EUS is recommended to check for small CBD stones

Overhauser-enhanced MR imaging (OMRI)

DEFF Research Database (Denmark)

Golman, K; Leunbach, I; Ardenkjaer-Larsen, JH

1998-01-01

Purpose. To evaluate a new single-electron contrast agent for Overhauser-enhanced MR imaging. The contrast agents that are currently available give enhancement factors that are too low to make the technique a valid option for routine clinical use. Material and Methods. MR images were generated di...

Cross-calibration of the Siemens mMR

DEFF Research Database (Denmark)

Keller, Sune H; Jakoby, Björn; Svalling, Susanne

2016-01-01

BACKGROUND: We present a quick and easy method to perform quantitatively accurate PET scans of typical water-filled PET plastic shell phantoms on the Siemens Biograph mMR PET/MR system. We perform regular cross-calibrations (Xcal) of our PET systems, including the PET/MR, using a Siemens mCT water...

MR staging of endometrial carcinoma

International Nuclear Information System (INIS)

Innocenti, P.; Agostini, S.; Erroi, C.; Ambrogetti, D.; Cellerini, A.; Nori, J.

1991-01-01

Biopsy is the technique of choice for the definitive diagnosis of endometrial carcinoma. Since lymphatic tumor spread has been demonstrated to depend on the degree of myometrial involvement, the definition of the latter with imaging techniques may significantly affect both pfognosis and therapy. We investigated, by means of MR imaging at 0.5 T, 14 patients with endometrial carcinoma, to assess both tumor stage and myometrial involvement. FIGO staging system was employed, and M parameter evaluated (M0= no myometrial involvement; M1involvement confined to the inner third; M2= Involvement confined to the middle third; M3= involvement of the whole myometrium). Another parameter was the characteristic high signal of the tumor on PD and T2W images. The patients were then operated and MR information was correlated with surgical findings. Overall diagnostic accuracy of MR imaging was 85.7% in tumor staging, and 92.2% in defining M parameter. Tumor spread into adnexa and into cervical canal was poorly demonstrated by MR imaging

Technical errors in MR arthrography

International Nuclear Information System (INIS)

Hodler, Juerg

2008-01-01

This article discusses potential technical problems of MR arthrography. It starts with contraindications, followed by problems relating to injection technique, contrast material and MR imaging technique. For some of the aspects discussed, there is only little published evidence. Therefore, the article is based on the personal experience of the author and on local standards of procedures. Such standards, as well as medico-legal considerations, may vary from country to country. Contraindications for MR arthrography include pre-existing infection, reflex sympathetic dystrophy and possibly bleeding disorders, avascular necrosis and known allergy to contrast media. Errors in injection technique may lead to extra-articular collection of contrast agent or to contrast agent leaking from the joint space, which may cause diagnostic difficulties. Incorrect concentrations of contrast material influence image quality and may also lead to non-diagnostic examinations. Errors relating to MR imaging include delays between injection and imaging and inadequate choice of sequences. Potential solutions to the various possible errors are presented. (orig.)

Technical errors in MR arthrography

Energy Technology Data Exchange (ETDEWEB)

Hodler, Juerg [Orthopaedic University Hospital of Balgrist, Radiology, Zurich (Switzerland)

2008-01-15

This article discusses potential technical problems of MR arthrography. It starts with contraindications, followed by problems relating to injection technique, contrast material and MR imaging technique. For some of the aspects discussed, there is only little published evidence. Therefore, the article is based on the personal experience of the author and on local standards of procedures. Such standards, as well as medico-legal considerations, may vary from country to country. Contraindications for MR arthrography include pre-existing infection, reflex sympathetic dystrophy and possibly bleeding disorders, avascular necrosis and known allergy to contrast media. Errors in injection technique may lead to extra-articular collection of contrast agent or to contrast agent leaking from the joint space, which may cause diagnostic difficulties. Incorrect concentrations of contrast material influence image quality and may also lead to non-diagnostic examinations. Errors relating to MR imaging include delays between injection and imaging and inadequate choice of sequences. Potential solutions to the various possible errors are presented. (orig.)

MR constrained simultaneous reconstruction of activity and attenuation maps in brain TOF-PET/MR imaging

Energy Technology Data Exchange (ETDEWEB)

Mehranian, Abolfazl; Zaidi, Habib [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva (Switzerland)

2014-07-29

The maximum likelihood estimation of attenuation and activity (MLAA) algorithm has been proposed to jointly estimate activity and attenuation from emission data only. Salomon et al employed the MLAA to estimate activity and attenuation from time-of-flight PET data with spatial MR prior information on attenuation. Recently, we proposed a novel algorithm to impose both spatial and statistical constraints on attenuation estimation within the MLAA algorithm using Dixon MR images and a constrained Gaussian mixture model (GMM). In this study, we compare the proposed algorithm with MLAA and MLAA-Salomon in brain TOF-PET/MR imaging.

MR constrained simultaneous reconstruction of activity and attenuation maps in brain TOF-PET/MR imaging

International Nuclear Information System (INIS)

Mehranian, Abolfazl; Zaidi, Habib

2014-01-01

The maximum likelihood estimation of attenuation and activity (MLAA) algorithm has been proposed to jointly estimate activity and attenuation from emission data only. Salomon et al employed the MLAA to estimate activity and attenuation from time-of-flight PET data with spatial MR prior information on attenuation. Recently, we proposed a novel algorithm to impose both spatial and statistical constraints on attenuation estimation within the MLAA algorithm using Dixon MR images and a constrained Gaussian mixture model (GMM). In this study, we compare the proposed algorithm with MLAA and MLAA_Salomon in brain TOF-PET/MR imaging.

Value of MR-guided localization and biopsy in breast lesions; Stellenwert der MR-gestuetzten Lokalisation und Biopsie von Brustlaesionen

Energy Technology Data Exchange (ETDEWEB)

Obenauer, S.; Grabbe, E.; Knollmann, F. [Abt. Diagnostische Radiologie, Georg-August-Univ. Goettingen (Germany)

2006-05-15

Contrast-enhanced dynamic MR mammography can provide important additional diagnostic information when performed for certain indications. When suspicious lesions are identified on MR mammography and cannot be reproduced using other imaging modalities, a decision must be made as to its management, i.e. further diagnostic work-up. One possibility is the short-term follow-up of such findings, resulting in higher costs and a possible delay in the start of treatment of a malignant lesion. An alternative to a follow-up is an MR-guide intervention. MR-compatible equipment has been developed for this purpose. This includes equipment specialized for percutaneous biopsy and preoperative localization. The following is an overview of the diagnostic value of MR-guided biopsy and preoperative localization including the relevant literature. (orig.)

MrGrid: a portable grid based molecular replacement pipeline.

Directory of Open Access Journals (Sweden)

Jason W Schmidberger

Full Text Available BACKGROUND: The crystallographic determination of protein structures can be computationally demanding and for difficult cases can benefit from user-friendly interfaces to high-performance computing resources. Molecular replacement (MR is a popular protein crystallographic technique that exploits the structural similarity between proteins that share some sequence similarity. But the need to trial permutations of search models, space group symmetries and other parameters makes MR time- and labour-intensive. However, MR calculations are embarrassingly parallel and thus ideally suited to distributed computing. In order to address this problem we have developed MrGrid, web-based software that allows multiple MR calculations to be executed across a grid of networked computers, allowing high-throughput MR. METHODOLOGY/PRINCIPAL FINDINGS: MrGrid is a portable web based application written in Java/JSP and Ruby, and taking advantage of Apple Xgrid technology. Designed to interface with a user defined Xgrid resource the package manages the distribution of multiple MR runs to the available nodes on the Xgrid. We evaluated MrGrid using 10 different protein test cases on a network of 13 computers, and achieved an average speed up factor of 5.69. CONCLUSIONS: MrGrid enables the user to retrieve and manage the results of tens to hundreds of MR calculations quickly and via a single web interface, as well as broadening the range of strategies that can be attempted. This high-throughput approach allows parameter sweeps to be performed in parallel, improving the chances of MR success.

MR imaging of central nervous system birth injuries

International Nuclear Information System (INIS)

Heier, L.A.; Zimmerman, R.D.

1991-01-01

This paper reports on head injuries due to birth trauma that have been evaluated with plain radiography, US, and CT. In the past, patient monitoring and transportation difficulties for a neonate have limited the use of MR. Does MR provide more information that would assist the management and prognostic assessment of these patients? An MR examination was requested on all neonates born or transferred to our institution with a documented traumatic delivery. CT and MR studies were compared for seven patients, including three cases of difficult forceps delivery, one case of double footling breech with forceps head extraction, two cases of shoulder dystocias, and one case of vacuum extraction. CT caused underestimation of subdural hematomas and contusions in three of five patients with this injury. The appreciation of a large subdural hematoma at MR resulted in surgical intervention. Both unsuspected cervical cord contusion and complete cord transection were identified on sagittal head MR images. Four of four skull fractures identified at CT were not seen at MR

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

MR tomography of the elbow joint

Energy Technology Data Exchange (ETDEWEB)

Zwaan, M.; Rinast, E.; Weiss, H.D.; Pressler, M.; Vogel, H.

1989-03-01

MR examinations of the elbow joint of three healthy subjects and a comparison with corresponding sections of anatomical preparations show that MR tomography enables not only an excellent differentiation of muscles, tendons and of the articular capsule, but will also visualise vessels and nerve tracts. MR tomography proved superior to the conventional methods in demonstration of separate fragments and inflammatory changes in the bone on examining 11 pathological elbow joints: congenital malformation, osteochondritis dissecans, ostitis, ulnar and radial nerve lesions, completely healed radius fracture and epicondylitis of the radial and ulnar humerus. Epicondylitis could not be demonstrated by MR. Magnetic resonance tomography seems to be the only method that enables direct visualisation of the nerve paths at the elbow joint.

MR imaging of normal bone marrow

International Nuclear Information System (INIS)

Stajgis, M.; Paprzycki, W.

1994-01-01

Principles of MR bone marrow imaging on the basis of retrospective analysis of MR examinations of bone marrow in different anatomic sites in 200 patients have been discussed. Significance of different physiologic factors and processes such as age, steatosis, osteoporosis, conversion and reconversion, which influence on MR bone marrow images, have been emphasized. T1-weighted images obtained with spin-echo sequences give the most of information about bone marrow structure in MR. Thorough knowledge of bone marrow physiology and clinical status of the patient is indispensable in correct interpretation of hypointensive lesions on T1-weighted images. When presence of disseminated bone marrow disease is suspected, authors propose routine imaging of lumbar vertebral column, pelvis and proximal parts of femoral bones. (author)

Rosen's (M,R) system in Unified Modelling Language.

Science.gov (United States)

Zhang, Ling; Williams, Richard A; Gatherer, Derek

2016-01-01

Robert Rosen's (M,R) system is an abstract biological network architecture that is allegedly non-computable on a Turing machine. If (M,R) is truly non-computable, there are serious implications for the modelling of large biological networks in computer software. A body of work has now accumulated addressing Rosen's claim concerning (M,R) by attempting to instantiate it in various software systems. However, a conclusive refutation has remained elusive, principally since none of the attempts to date have unambiguously avoided the critique that they have altered the properties of (M,R) in the coding process, producing merely approximate simulations of (M,R) rather than true computational models. In this paper, we use the Unified Modelling Language (UML), a diagrammatic notation standard, to express (M,R) as a system of objects having attributes, functions and relations. We believe that this instantiates (M,R) in such a way than none of the original properties of the system are corrupted in the process. Crucially, we demonstrate that (M,R) as classically represented in the relational biology literature is implicitly a UML communication diagram. Furthermore, since UML is formally compatible with object-oriented computing languages, instantiation of (M,R) in UML strongly implies its computability in object-oriented coding languages. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Does secretin stimulation add to magnetic resonance cholangiopancreatography in characterising pancreatic cystic lesions as side-branch intraductal papillary mucinous neoplasm?

International Nuclear Information System (INIS)

Purysko, Andrei S.; Gandhi, Namita S.; Veniero, Joseph C.; Walsh, R.M.; Obuchowski, Nancy A.

2014-01-01

To assess the value of secretin during magnetic resonance cholangiopancreatography (MRCP) in demonstrating communication between cystic lesions and the pancreatic duct to help determine the diagnosis of side-branch intraductal papillary mucinous neoplasm (SB-IPMN). This is an IRB-approved, HIPAA-compliant retrospective study of 29 SB-IPMN patients and 13 non-IPMN subjects (control) who underwent secretin-enhanced MRCP (s-MRCP). Two readers blinded to the final diagnosis reviewed three randomised image sets: (1) pre-secretin HASTE, (2) dynamic s-MRCP and (3) post-secretin HASTE. Logistic regression, generalised linear models and ROC analyses were used to compare pre- and post-secretin results. There was no significant difference in median scores for the pre-secretin [reader 1: 1; reader 2: 2 (range -2 to 2)] and post-secretin HASTE [reader 1: 1; reader 2: 1 (range -2 to 2)] in the SB-IPMN group (P = 0.14), while the scores were lower for s-MRCP [reader 1: 0.5 (range -2 to 2); reader 2: 0 (range -1 to 2); P = 0.016]. There was no significant difference in mean maximum diameter of SB-IPMN on pre- and post-secretin HASTE, and s-MRCP (P > 0.05). Secretin stimulation did not add to MRCP in characterising pancreatic cystic lesions as SB-IPMN. (orig.)

MR Imaging of Articular Hyaline Cartilage

OpenAIRE

Uetani, Masataka

2005-01-01

MR imaging is still an evolving technique for the diagnosis of joint cartilage lesions. Early morphologic changes in the degenerative cartilage are not reliably diagnosed even with use of tailored MR imaging techniques. The detection of the biochemical changes of cartilage or high-resolution MRI will serve as an important tool for the early diagnosis of cartilage degeneration in near future. Further prospective studies are needed to establish the role of MR imaging in clinical use.

Quantification of Hepatic Steatosis with T1-independent, T2*-corrected MR Imaging with Spectral Modeling of Fat: Blinded Comparison with MR Spectroscopy

Science.gov (United States)

Hines, Catherine D. G.; Hamilton, Gavin; Sirlin, Claude B.; McKenzie, Charles A.; Yu, Huanzhou; Brittain, Jean H.; Reeder, Scott B.

2011-01-01

Purpose: To prospectively compare an investigational version of a complex-based chemical shift–based fat fraction magnetic resonance (MR) imaging method with MR spectroscopy for the quantification of hepatic steatosis. Materials and Methods: This study was approved by the institutional review board and was HIPAA compliant. Written informed consent was obtained before all studies. Fifty-five patients (31 women, 24 men; age range, 24–71 years) were prospectively imaged at 1.5 T with quantitative MR imaging and single-voxel MR spectroscopy, each within a single breath hold. The effects of T2* correction, spectral modeling of fat, and magnitude fitting for eddy current correction on fat quantification with MR imaging were investigated by reconstructing fat fraction images from the same source data with different combinations of error correction. Single-voxel T2-corrected MR spectroscopy was used to measure fat fraction and served as the reference standard. All MR spectroscopy data were postprocessed at a separate institution by an MR physicist who was blinded to MR imaging results. Fat fractions measured with MR imaging and MR spectroscopy were compared statistically to determine the correlation (r2), and the slope and intercept as measures of agreement between MR imaging and MR spectroscopy fat fraction measurements, to determine whether MR imaging can help quantify fat, and examine the importance of T2* correction, spectral modeling of fat, and eddy current correction. Two-sided t tests (significance level, P = .05) were used to determine whether estimated slopes and intercepts were significantly different from 1.0 and 0.0, respectively. Sensitivity and specificity for the classification of clinically significant steatosis were evaluated. Results: Overall, there was excellent correlation between MR imaging and MR spectroscopy for all reconstruction combinations. However, agreement was only achieved when T2* correction, spectral modeling of fat, and magnitude

MR guided percutaneous laser lumbar disk hernia ablation

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, Takuo; Terao, Tohru; Ishibashi, Toshihiro; Yuhki, Ichiro; Harada, Junta; Tashima, Michiko [Jikei Univ., Chiba (Japan). Kashiwa Hospital; Abe, Toshiaki

1998-03-01

An MRI unit for interventional procedure is very useful for minimally invasive surgery of the brain and spine. Percutaneous laser disc decompression (PLDD) utilizing X-ray fluoroscopy is a relatively new less invasive procedure for treatment of lumbar disc herniation. MR guided laser surgery is applied to patients with disc herniation at our department. Approaching the target of the disc protrusion was easily conducted and vaporizing the disc hernia directly using a laser was possible under MR fluoroscopy. The purpose of the present study is to evaluate the usefulness of MR guided percutaneous laser disc hernia ablation (MR-guided PLDHA). As subjects, 36 patients with lumbar disc herniation, including 23 cases with L4/5 involvement and 13 cases with L5/S1 involvement were studied. Among these, 26 were males and 10 were females, age ranging from 24 to 62. We used an open type MR system (Hitachi, Airis 0.3T), a permanent, open configuration MR system. A YAG laser (LaserScope, USA) was used for PLDHA. An MR compatible 18G titanium needle 15 cm in length was used to puncture the herniated discs. The MR compatible needle was clearly visualized, and used to safely and accurately puncture the target herniated disc in each case with multidimensional guidance. Application of the laser was performed with MR guidance. The energy dose from the laser ranged from 800 to 2100 joules. In most cases, signs and symptoms improved in the patients immediately after disc vaporization. The overall success rate was 88.9%. The complication rate was 2.8%, including one case of discitis after PLDHA. MR fluoroscopy sequence permits near real time imaging and provides an easy approach to the therapeutic target of disc herniation. MR guided PLDHA is a minimally invasive procedure and is very useful for the treatment of lumbar disc protrusion. (author)

MR guided percutaneous laser lumbar disk hernia ablation

International Nuclear Information System (INIS)

Hashimoto, Takuo; Terao, Tohru; Ishibashi, Toshihiro; Yuhki, Ichiro; Harada, Junta; Tashima, Michiko; Abe, Toshiaki.

1998-01-01

An MRI unit for interventional procedure is very useful for minimally invasive surgery of the brain and spine. Percutaneous laser disc decompression (PLDD) utilizing X-ray fluoroscopy is a relatively new less invasive procedure for treatment of lumbar disc herniation. MR guided laser surgery is applied to patients with disc herniation at our department. Approaching the target of the disc protrusion was easily conducted and vaporizing the disc hernia directly using a laser was possible under MR fluoroscopy. The purpose of the present study is to evaluate the usefulness of MR guided percutaneous laser disc hernia ablation (MR-guided PLDHA). As subjects, 36 patients with lumbar disc herniation, including 23 cases with L4/5 involvement and 13 cases with L5/S1 involvement were studied. Among these, 26 were males and 10 were females, age ranging from 24 to 62. We used an open type MR system (Hitachi, Airis 0.3T), a permanent, open configuration MR system. A YAG laser (LaserScope, USA) was used for PLDHA. An MR compatible 18G titanium needle 15 cm in length was used to puncture the herniated discs. The MR compatible needle was clearly visualized, and used to safely and accurately puncture the target herniated disc in each case with multidimensional guidance. Application of the laser was performed with MR guidance. The energy dose from the laser ranged from 800 to 2100 joules. In most cases, signs and symptoms improved in the patients immediately after disc vaporization. The overall success rate was 88.9%. The complication rate was 2.8%, including one case of discitis after PLDHA. MR fluoroscopy sequence permits near real time imaging and provides an easy approach to the therapeutic target of disc herniation. MR guided PLDHA is a minimally invasive procedure and is very useful for the treatment of lumbar disc protrusion. (author)

MR urography: examination techniques and clinical applications

Energy Technology Data Exchange (ETDEWEB)

Nolte-Ernsting, C.C.A.; Adam, G.B.; Guenther, R.W. [Technische Hochschule Aachen (Germany). Klinik fuer Radiologische Diagnostik

2001-03-01

Modern MR urography is performed on the basis of two different imaging strategies, which can be used complementarily to cover almost all aspects in the diagnosis of upper urinary tract diseases. The first technique utilizes unenhanced, heavily T2-weighted pulse sequences to obtain static-fluid images of the urinary tract. T2-weighted MR urograms have proved to be excellent in the visualization of the markedly dilated urinary tract, even if the renal excretory function is quiescent. Static-fluid MR urography is less suitable for imaging of disorders that occur in the nondilated collecting system. The second MR urography technique is analogous to the methodology of conventional intravenous pyelography and is, therefore, designated as excretory MR urography. For this purpose, a non-nephrotoxic gadolinium chelate is intravenously administered and after its renal excretion, the gadolinium-enhanced urine is visualized using fast T1-weighted gradient-echo sequences. The combination of gadolinium and low-dose furosemide (5-10 mg) is the key for achieving a uniform distribution of the contrast material inside the entire urinary tract and, secondly, to avoid high endoluminal gadolinium concentrations, which cause signal loss of the urine due to T2{sup *} effects. Gadolinium excretory MR urography allows to obtain high-quality images of both nondilated and obstructed urinary tracts in patients with normal or moderately impaired renal function. This article reviews the principles of T2- and T1-weighted MR urography in detail and informs how to use these techniques safely in potential clinical applications such as chronic urolithiasis, intrinsic and extrinsic tumor diseases, and congenital anomalies. Magnetic resonance urography performed in combination with standard MR imaging offers a potential to reduce the need for invasive retrograde pyelography. Although the economic aspect is still problematic, it is obvious that MR urography will continue to increase its role in

MR imaging of chondramalacia patella

International Nuclear Information System (INIS)

Yulish, B.S.; Montanez, J.; Mulopulos, G.P.; Goodfellow, D.; Dollinger, B.; Bryan, P.J.; Modic, M.T.

1986-01-01

Because of its inherent soft-tissue contrast, MR imaging can distinguish hyaline articular cartilage, fibrocartilage, and cortical and medullary bone, and thus seems a method ideally suited to examine the posterior patellar hyaline articular cartilage. The authors studied the knees of people with suspected chondromalacia patella using MR imagine and compared our findings to normal knees and, where available, results of surgery. They find that we can distinguish swollen cartilage, irregular cartilage, absent cartilage, and bony patellar defects. Joint fluid and meniscal injuries could also be identified. MR imaging is a useful method for evaluation of chondromalacia patella and may reduce the need for arthroscopy and arthrography for diagnosis

MR imaging of the knee

International Nuclear Information System (INIS)

Mink, J.H.

1987-01-01

There is increasing evidence that MR imaging of the knee can accurately evaluate the menisci and the cruciate and collateral ligaments with an accuracy equal to that of conventional anthrography. MR imaging can, as a simple test, definitively assess a wide spectrum of the causes of knee pain, including osteonecrosis/osteochondritis dissecans, chondral and bony fractures, abnormal plicae, and chondromalacia. The presentation focuses on the optimal imaging parameters that will ensure accuracy and maximize patient throughput. The etiology and significance of meniscal signal is discussed, and the criteria for an MR imaging-based diagnosis of meniscal tears, cruciate and collateral ligament and extensor mechanism abnormalities, osteonecrosis, and stress fractures are presented

The use of MR in cardiological diagnostics

International Nuclear Information System (INIS)

Smith, Hans-Joergen

2004-01-01

Image diagnostics is playing an important role in cardiology, and magnetic resonance tomography (MR) is one of many methods used in examinations of the heart. Based on studies of the literature and his own experience the author surveys the potential of MR in today's and tomorrow's diagnostics of heart diseases. Among the image diagnostic methods MR is the one that can give the most extensive information about the heart's anatomy and function. In a non-invasive way and without the use of ionizing radiation, MR can represent the anatomy in selectable planes, visualize and quantify the heart's pumping function and functioning of the cardiac valves, and give detailed information about the regional contractility, blood flow and viability of myocard. MR is capable of giving important and to some extent unique contributions to heart diseases, both congenital and contracted heart disease. Because of failing availability and competence MR is still little used in cardiological diagnostics, but the method undoubtedly has the potential to play a very important role in the future

MR angiography of the TMJ in asymptomatic volunteers

International Nuclear Information System (INIS)

Takagi, Ritsuo; Ohashi, Yasushi; Westesson, P.L.; Togashi, Hirosuke

1998-01-01

To evaluate the vascular anatomy of the temporomandibular joint (TMJ) and surrounding soft tissue non-invasively, we applied magnetic resonance (MR) angiography for delineating the arterial architecture around the TMJ. MR angiograms of the left and right TMJs in asymptomatic volunteers were obtained using 3D/Time-of-flight (TOF) (First Field Echo, TR/TE/FLIP=46 ms/6.8 ms/17 deg) with intravenous contrast. These MR angiograms were compared with experimental angiograms of human TMJ autopsy specimens in order to identify each of the branches of the arteries on the MR angiograms. This study enabled the depiction by MR angiography of arterial vessels around the TMJ region to some degree. In conclusion, MR angiography appears promising as a non-invasive tool to evaluate the vascular anatomy of the TMJ. (author)

Postoperative MR arthography of the shoulder joint; MR-Arthographie des Schultergelenks im postoperativen Patientenkollektiv

Energy Technology Data Exchange (ETDEWEB)

Rand, T. [Einrichtung fuer Magnetresonanz, Ludwig Boltzmann-Inst. fuer Radiologische Tumordiagnostik, Univ. Wien (Austria); Trattnig, S. [Einrichtung fuer Magnetresonanz, Ludwig Boltzmann-Inst. fuer Radiologische Tumordiagnostik, Univ. Wien (Austria); Breitenseher, M. [Einrichtung fuer Magnetresonanz, Ludwig Boltzmann-Inst. fuer Radiologische Tumordiagnostik, Univ. Wien (Austria); Freilinger, W. [Orthopaedisches Krankenhaus Speising (Austria); Cochole, M. [Orthopaedische Abt., Allgemein Oeffentliches Krankenhaus Amstetten (Austria); Imhof, H. [Einrichtung fuer Magnetresonanz, Ludwig Boltzmann-Inst. fuer Radiologische Tumordiagnostik, Univ. Wien (Austria)

1996-12-01

Indications of MR arthrography were analyzed in this prospective study. The aim was to evaluate possible advantages over conventional MRI, establish diagnostic criteria and to analyze its meaning further for the therapeutic management of postoperative patients. MR arthrography was performed in eight patients who had undergone surgical repair of rotator cuff lesions (modified Neer acromioplasty) and in six patients who had undergone arthroscopic therapy of recurrent unidirectional dislocation of the shoulder by combined arthroscopic intra- and extracapsular repair. MR investigations were performed before and after application of a contrast solution (2 mmol Gd-DTPA). All patients suffered from chronic postoperative pain. In patients with rotator cuff lesions, a partial tear could be verified in one patient and excluded in all others. In patients after arthroscopic therapy by combined intra- and extracapsular repair, a radiologically patulous-appearing capsule correlated with clinically recurrent dislocations. In all other patients diagnostic criteria, such as distribution of the intra-articular contrast solution, proliferation of scar tissue, nodular appearance of the glenohumeral ligaments and capsule thickness, correlated with a regular postoperative status. MR arthrography of the shoulder represents a promising method in the evaluation of the postoperative shoulder. It might further improve the evaluation of reactive capsule alterations, scar tissue proliferation, and the labroligamentous complex, as well as the ability to differentiate partial and complete rerupture from degenerative changes of the rotator cuff. (orig.) [Deutsch] In einer prospektiven Studie sollten die Einsatzmoeglichkeiten der MR-Arthrographie am operierten Schultergelenk erfasst werden. Ziel der Studie war einerseits eine gegenueber der konventionellen MR-Untersuchung verbesserten Diagnosestellung und andererseits die Erstellung von fuer die Rezidivdiagnostik relevanten Diagnosekriterien

MR cisternography after intrathecal Gd-DTPA application

International Nuclear Information System (INIS)

Reiche, Werner; Komenda, Yvonne; Steudel, Wolf-Ingo; Schick, Bernhard; Grunwald, Iris; Reith, Wolfgang

2002-01-01

The purpose of this study was to establish and to evaluate MR cisternography after intrathecal Gd-DTPA administration to detect rhinobasal cerebrospinal fluid (CSF) fistulae in patients with suspected CSF rhinorrhoea. Ten patients with suspected CSF rhinorrhoea were examined. The MR cisternography included the following investigation steps: acquisition of nonenhanced fat-suppressed T1-weighted spin-echo (SE) scans of the skull base and the paranasal sinuses, lumbar puncture with administration of 1 ml Gd-DTPA solute with 4 ml NaCl and performance of MR cisternography with the same fat-suppressed T1-weighted sequences as used initially. In 10 patients with suspected CSF rhinorrhoea Gd-DTPA enhanced MR cisternography detected 5 CSF fistulae. In 3 of 5 CSF leaks were located in the cribriform plate and in 2 of 5 sphenoidal. Whereas 4 of these depicted leaks were confirmed surgically, in 1 case the CSF fistula closed spontaneously. In another case, CSF leakage after severe head injury was clinically highly suspected but ceased prior to MR cisternography with inability to detect the temporary fistula. In the remaining 4 patients with serous rhinorrhoea MR cisternography did not provide any evidences for CSF fistulae. Intrathecal Gd-DTPA injection was tolerated excellently. Clinical and EEG examinations showed no gross behavioural or neurological disturbances and no seizure activity, respectively. The MR cisternography after intrathecal administration of Gd-DTPA represents a safe, promising and minimally invasive method for detection of CSF fistulae. This MR investigation provides excellent depiction of CSF spaces and pinpoints CSF fistulae. (orig.)

An MR-compatible neonatal incubator.

Science.gov (United States)

Paley, M N J; Hart, A R; Lait, M; Griffiths, P D

2012-07-01

To develop a neonatal MR-compatible incubator for transporting babies between a neonatal intensive care unit and an MRI unit that is within the same hospital but geographically separate. The system was strapped to a standard MR-compatible patient trolley, which provides space for resuscitation outside the incubator. A constant-temperature exothermic heat pad was used to maintain temperature together with a logging fluoro-optic temperature monitor and alarm system. The system has been designed to accommodate standard knee-sized coils from the major MR manufacturers. The original incubator was constructed from carbon fibre, but this required modification to prevent radiofrequency shading artefacts due to the conducting properties of the carbon fibre. A high-tensile polyester material was used, which combined light weight with high impact strength. The system could be moved onto the patient bed with the coils and infant in place by one technologist. Studies in eight neonatal patients produced high quality 1.5 T MR images with low motion artefacts. The incubator should also be compatible with imaging in 3 T MR systems, although further work is required to establish this. Images were acquired using both rapid and high-resolution sequences, including three-dimensional volumes, proton spectra and diffusion weighting. The incubator provides a safe, quiet environment for neonates during transport and imaging, at low cost.

German Roentgen Society statement on MR imaging of patients with cardiac pacemakers; Positionspapier der Deutschen Roentgengesellschaft (DRG) zu MR-Untersuchungen bei Patienten mit Herzschrittmachern

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Sommer, T. [German Red Cross Hospital Neuwied (Germany). Dept. of Diagnostic and Interventional Radiology; Luechinger, R. [Zuerich Univ. (Switzerland). Inst. for Biomedical Engineering; Barkhausen, J. [University Hospital Luebeck (Germany). Dept. of Radiology and Nuclear Medicine; Gutberlet, M. [Univ. Leipzig - German Heart Center Leipzig (Germany). Dept. of Diagnostic and Interventional Radiology; Quick, H.H. [University Hospital Essen (Germany). Erwin L. Hahn Inst. for MR Imaging, High Field and Hybrid MR Imaging; Fischbach, K. [University Hospital Magdeburg (Germany). Dept. of Radiology and Nuclear Medicine

2015-09-15

The aim of this paper is to inform physicians, especially radiologists and cardiologists, about the technical and electrophysiological background of MR imaging of patients with implanted cardiac pacemakers (PM) and to provide dedicated clinical practice guidelines how to perform MR exams in this patient group. The presence of a conventional PM system is not any more considered an absolute contraindication for MR imaging. The prerequisites for MR imaging on pacemaker patients include the assessment of the individual risk/benefit ratio as well as to obtain full informed consent about the off label character of the procedure and all associated risks. Furthermore the use of special PM-related (e.g. re-programming of the PM) and MRI-related (e.g. limitation of whole body SAR to 2 W/kg) precautions is required and needs to be combined with adequate monitoring during MR imaging using continuous pulsoximetry. MR conditional PM devices are tested and approved for the use in the MR environment under certain conditions, including the field strength and gradient slew rate of the MR system, the maximum whole body SAR value and the presence of MR imaging exclusion zones. Safe MR imaging of patients with MR conditional PM requires the knowledge of the specific conditions of each PM system. If MR imaging within these specific conditions cannot be guaranteed in a given patient, the procedure guidelines for conventional PM should be used. The complexity of MR imaging of PM patients requires close cooperation of radiologists and cardiologists.

MR imaging of sacral and perisacral lesions

International Nuclear Information System (INIS)

Wetzel, L.H.; Levine, E.; Murphey, M.D.

1987-01-01

This exhibit demonstrates the utility of MR imaging in evaluating sacral and perisacral lesions. Thirty-two lesions were studied using a superconducting 1.0-T MR imager. Eleven primary and 13 metastatic tumors, four congenital lesions, and four arachnoid cysts were evaluated. MR did not usually enable a more specific histologic diagnosis than other imaging techniques. However, extraosseous and proximal spinal extent of tumors was well defined without use of oral or intravenous contrast material. MR imaging is an excellent noninvasive technique for evaluating most sacral and perisacral lesions and is particularly helpful when precise tumor extent must be determined for treatment planning

Feasibility of MR urography in patients with urinary diversion

International Nuclear Information System (INIS)

Battal, Bilal; Kocaoglu, Murat; Ilica, Turan; Akgun, Veysel; Aydur, Emin; Dayanc, Murat

2011-01-01

The aims of this study were to determine the diagnostic value of MR urography and to compare the T2- and T1-weighted MR urography techniques in patients with urinary diversion. We retrospectively reviewed 19 MR urograms in 14 patients (13 male and one female, 8–77 years old, mean age: 54.2) with urinary diversion. Magnetic resonance urography examinations were performed with 1.5-T MR scanners. In addition to T2- and T1-weighted MR urography techniques, conventional T1- and T2-weighted axial and coronal sequences were also obtained. Collecting systems were evaluated in five segments (right proximal and distal collecting system, left proximal and distal collecting system and conduit or reservoir). Imaging features of the urinary collecting systems were evaluated with T2- and T1-weighted MR urography images. The clinical, laboratory data and follow-up imaging findings were regarded as standard. A cross table was formed to determine sensitivity, specificity and accuracy of MR urography techniques. T2-weighted MR urography, T1-weighted MR urography and combination of these two techniques could demonstrate 89.01, 87.65 and 93.83% of all collecting system segments, respectively. For the detection of the pathologic urinary segments, sensitivity, specificity and accuracy were 100, 95.29 and 95.6% in T2-weighted MR urography and 100, 93.42 and 93.82% in T1-weighted MR urography, respectively. Sensitivity, specificity and accuracy were 100% in combined T2- and T1-weighted MR urography technique. Magnetic resonance urography is an effective imaging method for the evaluation of the urinary system in patients with urinary diversion. T2-weighted MR urography alone has high sensitivity, specificity and accuracy, does not require intravenous contrast medium and can be obtained in 3–5 min. However, T1-weighted MR urography may provide additional information in some cases.

Epstein-Barr virus encephalitis and encephalomyelitis: MR findings

International Nuclear Information System (INIS)

Shian, W.J.; Chi, C.S.

1996-01-01

The purpose of this project is to investigate the clinical and brain MR characteristics of Epstein-Barr virus (EBV) encephalitis and encephalomyelitis. Clinical and 30 MR findings of 29 patients with EBV encephalitis or encephalomyelitis were retrospectively reviewed. Patients included 24 with encephalitis, 3 with encephalomyelitis, and 2 with brain-stem encephalitis. Altered consciousness, seizures, visual hallucination, and acute psychotic reaction were the common presentations. Eight patients had positive MR findings. These included T2 prolongation over gray and white matter, periventricular leukomalacia, and brain atrophy. Transient T2 prolongation over gray and white matter was found in one patient. Our results indicate that EBV encephalitis and encephalomyelitis have a wide range of both clinical and MR findings. The MR lesions may disappear in a short period, so the timing for the MR scan may be critical. (orig.). With 5 figs., 2 tabs

Epstein-Barr virus encephalitis and encephalomyelitis: MR findings

Energy Technology Data Exchange (ETDEWEB)

Shian, W.J. [Department of Pediatrics, Tao-Yuan Veterans Hospital, No. 100, Sec 3, Cheng-Kung Rd, City of Tao-Yuan, Taiwan (Taiwan, Province of China); Chi, C.S. [Department of Pediatrics, Taichung Veterans General Hospital, Taichung, Taiwan (Taiwan, Province of China)

1996-09-01

The purpose of this project is to investigate the clinical and brain MR characteristics of Epstein-Barr virus (EBV) encephalitis and encephalomyelitis. Clinical and 30 MR findings of 29 patients with EBV encephalitis or encephalomyelitis were retrospectively reviewed. Patients included 24 with encephalitis, 3 with encephalomyelitis, and 2 with brain-stem encephalitis. Altered consciousness, seizures, visual hallucination, and acute psychotic reaction were the common presentations. Eight patients had positive MR findings. These included T2 prolongation over gray and white matter, periventricular leukomalacia, and brain atrophy. Transient T2 prolongation over gray and white matter was found in one patient. Our results indicate that EBV encephalitis and encephalomyelitis have a wide range of both clinical and MR findings. The MR lesions may disappear in a short period, so the timing for the MR scan may be critical. (orig.). With 5 figs., 2 tabs.

MR pancreatography (MRP) for mucin-producing pancreatic tumors

International Nuclear Information System (INIS)

Usuki, Noriaki; Nishimoto, Masaoki; Shima, Tomoko; Hirokawa, Keiko; Tashiro, Takahiko; Saiwai, Shigeo; Miyamoto, Takeshi; Okabe, Sumihiro

1997-01-01

MR pancreatography was performed in 11 patients with mucin-producing pancreatic tumor (main duct type: four and branch duct type: seven) using HASTE with a body phased array coil on a 1.5-T unit. The results of MR pancreatography were compared with imaging of endoscopic retrograde pancreatography (ERP). In all cases, MR pancreatography demonstrated all dilated pancreatic ducts and cysts. ERP did not completely demonstrate dilated ducts and cysts because of mucinous materials. Conspicuity of an intraductal tumor was more excellent by ER pancreatography than MR pancreatography. Therefore MR pancreatography and ER pancreatography are complementary methods in diagnosis for mucin-producing pancreatic tumors. (author)

Comparison of MR-based attenuation correction and CT-based attenuation correction of whole-body PET/MR imaging

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Izquierdo-Garcia, David [Mount Sinai School of Medicine, Translational and Molecular Imaging Institute, New York, NY (United States); Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA (United States); Sawiak, Stephen J. [University of Cambridge, Wolfson Brain Imaging Centre, Cambridge (United Kingdom); Knesaurek, Karin; Machac, Joseph [Mount Sinai School of Medicine, Division of Nuclear Medicine, Department of Radiology, New York, NY (United States); Narula, Jagat [Mount Sinai School of Medicine, Department of Cardiology, Zena and Michael A. Weiner Cardiovascular Institute and Marie-Josee and Henry R. Kravis Cardiovascular Health Center, New York, NY (United States); Fuster, Valentin [Mount Sinai School of Medicine, Department of Cardiology, Zena and Michael A. Weiner Cardiovascular Institute and Marie-Josee and Henry R. Kravis Cardiovascular Health Center, New York, NY (United States); The Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid (Spain); Fayad, Zahi A. [Mount Sinai School of Medicine, Translational and Molecular Imaging Institute, New York, NY (United States); Mount Sinai School of Medicine, Department of Cardiology, Zena and Michael A. Weiner Cardiovascular Institute and Marie-Josee and Henry R. Kravis Cardiovascular Health Center, New York, NY (United States); Mount Sinai School of Medicine, Department of Radiology, New York, NY (United States)

2014-08-15

The objective of this study was to evaluate the performance of the built-in MR-based attenuation correction (MRAC) included in the combined whole-body Ingenuity TF PET/MR scanner and compare it to the performance of CT-based attenuation correction (CTAC) as the gold standard. Included in the study were 26 patients who underwent clinical whole-body FDG PET/CT imaging and subsequently PET/MR imaging (mean delay 100 min). Patients were separated into two groups: the alpha group (14 patients) without MR coils during PET/MR imaging and the beta group (12 patients) with MR coils present (neurovascular, spine, cardiac and torso coils). All images were coregistered to the same space (PET/MR). The two PET images from PET/MR reconstructed using MRAC and CTAC were compared by voxel-based and region-based methods (with ten regions of interest, ROIs). Lesions were also compared by an experienced clinician. Body mass index and lung density showed significant differences between the alpha and beta groups. Right and left lung densities were also significantly different within each group. The percentage differences in uptake values using MRAC in relation to those using CTAC were greater in the beta group than in the alpha group (alpha group -0.2 ± 33.6 %, R{sup 2} = 0.98, p < 0.001; beta group 10.31 ± 69.86 %, R{sup 2} = 0.97, p < 0.001). In comparison to CTAC, MRAC led to underestimation of the PET values by less than 10 % on average, although some ROIs and lesions did differ by more (including the spine, lung and heart). The beta group (imaged with coils present) showed increased overall PET quantification as well as increased variability compared to the alpha group (imaged without coils). PET data reconstructed with MRAC and CTAC showed some differences, mostly in relation to air pockets, metallic implants and attenuation differences in large bone areas (such as the pelvis and spine) due to the segmentation limitation of the MRAC method. (orig.)

Comparison of MR-based attenuation correction and CT-based attenuation correction of whole-body PET/MR imaging

International Nuclear Information System (INIS)

Izquierdo-Garcia, David; Sawiak, Stephen J.; Knesaurek, Karin; Machac, Joseph; Narula, Jagat; Fuster, Valentin; Fayad, Zahi A.

2014-01-01

The objective of this study was to evaluate the performance of the built-in MR-based attenuation correction (MRAC) included in the combined whole-body Ingenuity TF PET/MR scanner and compare it to the performance of CT-based attenuation correction (CTAC) as the gold standard. Included in the study were 26 patients who underwent clinical whole-body FDG PET/CT imaging and subsequently PET/MR imaging (mean delay 100 min). Patients were separated into two groups: the alpha group (14 patients) without MR coils during PET/MR imaging and the beta group (12 patients) with MR coils present (neurovascular, spine, cardiac and torso coils). All images were coregistered to the same space (PET/MR). The two PET images from PET/MR reconstructed using MRAC and CTAC were compared by voxel-based and region-based methods (with ten regions of interest, ROIs). Lesions were also compared by an experienced clinician. Body mass index and lung density showed significant differences between the alpha and beta groups. Right and left lung densities were also significantly different within each group. The percentage differences in uptake values using MRAC in relation to those using CTAC were greater in the beta group than in the alpha group (alpha group -0.2 ± 33.6 %, R 2 = 0.98, p 2 = 0.97, p < 0.001). In comparison to CTAC, MRAC led to underestimation of the PET values by less than 10 % on average, although some ROIs and lesions did differ by more (including the spine, lung and heart). The beta group (imaged with coils present) showed increased overall PET quantification as well as increased variability compared to the alpha group (imaged without coils). PET data reconstructed with MRAC and CTAC showed some differences, mostly in relation to air pockets, metallic implants and attenuation differences in large bone areas (such as the pelvis and spine) due to the segmentation limitation of the MRAC method. (orig.)

MR imaging of pineal cysts

International Nuclear Information System (INIS)

Ahn, Yong Sik; Yu, Hyeon; Kim, Wan Tae; Bae, Jin Woo; Moon, Hee Jung; Shin, Hyun Ja

1999-01-01

To evaluate the incidence and characteristic findings of pineal cyst incidentally detected on magnetic resonance (MR) imaging. Brain MR images obtained in 2432 patients were retrospectively reviewed to determine the incidence and MR findings of pineal cysts, which were evaluated according to their size, shape, location, signal intensity, interval change, contrast enhancement and mass effect on adjacent structures. Cysts were encountered in 107(4.4 %) of 2432 patients evaluated. their size ranged from 1 X 1 X 1 to 15 X 8 X 9 (mean, 5.97 X 3.82 X 4.82)mm. All were spherical (n=53) or oval (n=54) in shape. Their margin was smooth and they were homogeneous in nature. On T1-weighted images, the cysts were seen to be hyperintense (n=57) or isointense (n=50) to cerebrospinal fluid, but less so than brain parenchyma. T2-weighted images showed them to be isointense (n=51)or hyperintense (n=56) to cerebrospinal fluid. The cysts were centrally located in 65 cases and eccentrically in 42. Compression of the superior colliculi of the tectum was demonstrated in 17 cases (15.9 %). NO patients presented clinical symptoms or signs related to either pineal or tectal lesions. Peripheral enhancement around the cyst after Gd-DTPA injection was demonstrated in 51 cases(100 %). Follow-up examinations in 19 cases demonstrated no interval change. The incidence of pineal cysts was 4.4 %. The MR characteristics of simple pineal cysts include: (1) an oval or spherical shape, (2) a smooth outer margin and homogeneous nature, (3) isosignal or slightly high signal intensity to cerebrospinal fluid on whole pulse sequences, (4) ring enhancement after contrast injection, (5) an absence of interval change, as seen during follow up MR study. These MR appearances of pineal cysts might be helpful for differentiating them from pineal tumors

MR findings of cerebral arteriovenous malformations associated with hemorrhage

Energy Technology Data Exchange (ETDEWEB)

Tsuchiya, Kazuhiro (National Defence Medical Coll., Tokorozawa, Saitama (Japan))

1990-10-01

This study was developed to assess the role of magnetic resonance (MR) imaging in the diagnosis of cerebral arteriovenous malformations (AVMs) associated with hemorrhage. MR images were retrospectively reviewed in 10 patients (age 8 to 60 years) who had an AVM with intracerebral or intraventricular hemorrhage. MR imaging was performed at 1.5 T obtaining T{sub 1}- and T{sub 2}-weighted spin-echo images with a slice thickness of 5 mm, and a slice interval of 0-5 mm. The AVM was detected on MR in seven patients (70%), while enhanced CT was positive in six of eight patients (75%). In six patients in whom both the AVM and intracerebral hematoma (ICH) were depicted on MR, the nidi were located not inside but adjacent to the ICH. In three patients, MR disclosed a thin subdural hematoma (SDH) which was not noted on CT. There is little difference in the detectability of AVMs by MR and enhanced CT. However, MR clearly demonstrates the anatomic relationship to associated ICH. A non-traumatic SDH with an ICH demonstrated on MR may indicate the presence of an AVM even when the AVM itself is not apparent. (author).

Utility of MR imaging in pediatric spinal cord injury

International Nuclear Information System (INIS)

Felsberg, G.J.; Tien, R.D.; Osumi, A.K.; Cardenas, C.A.

1995-01-01

We evaluated the utility of MR imaging in pediatric patients with acute and subacute spinal cord injuries. MR imaging of 22 pediatric patients with suspected traumatic spinal cord injuries was reviewed. MR findings were correlated with physical examination and compared to available radiographs and CT examinations performed at time of presentation. Twelve patients had abnormalities on MR imaging. Seven had spinal cord contusions; five contusions were hemorrhagic. Five of seven patients with cord contusion had normal radiographs and CT exams. Six patients with normal radiographs and CT examinations had abnormal MR studies revealing cord contusion, ligamentous injury, disc herniation, and epidural hematoma. MR is useful in initial evaluation of pediatric patients with spinal cord injuries and in prognosis of future neurologic function. In the setting of spinal cord symptomatology and negative radiographic studies, MR imaging should be performed. Surgically correctable causes of cord compression demonstrated by MR imaging include disc herniation, epidural hematoma, and retropulsed fracture fragments. The entity of spinal cord injury without radiographic abnormality is a diagnosis of exclusion which should only be made after radiologic investigation with radiographs, high-resolution thin-section CT, and MR imaging. (orig.)

Interventional and intravascular MR angiography

International Nuclear Information System (INIS)

Ladd, M.E.; Debatin, J.F.

2000-01-01

Magnetic resonance imaging (MRI) has a number of characteristics which make it attractive for guidance of intravascular therapeutic procedures, including high soft tissue contrast, imaging in any arbitrary oblique plane, lack of ionizing radiation, and the ability to provide functional information, such as flow velocity and volume per unit time. For MR guidance of vascular interventions to be safe, catheters and guidewires must be visualized relative to the vascular system and surrounding tissues. A number of approaches for making instruments visible in an MR environment are presented, including both passive and active techniques. Passive techniques depend on contrast agents or susceptibility artifacts, whereas active techniques, including MR tracking, MR profiling, and active field inhomogeneity, use some form of electrical coil built into the instrument. The potential for obtaining high-resolution images of the vessel wall using coils built into a catheter is also discussed. These images provide the capability to distinguish and identify various plaque components. The additional capabilities of MRI could potentially open up new applications beyond those currently performed under X-ray fluoroscopic guidance. (orig.) [de

MR diagnosis of temporomandibular arthrosis

Energy Technology Data Exchange (ETDEWEB)

Suenaga, Shigeaki [Kagoshima Univ. (Japan). Faculty of Dentistry

1996-09-01

This review described lesions of articular disk and its surrounding tissues revealed by MR examination in temporomandibular arthrosis, and problems and limits of the examination. Apparatus and imaging methods: Spin echo method was generally used and gradient echo method was alternatively used. Author`s apparatus was 1.5 tesla Signa, Advantage type, equipped with surface coil for temporomandibular joint. Imaging conditions were T1-weighted spin echo method, T2-weighted fast spin echo method, spoiled GRASS (gradient recalled acquisition in the steady state) method and GRASS method. MR findings of articular disk: MR images of normal and abnormal temporomandibular joint were presented together with computed radiographic findings. The role of dynamic imaging was described for evaluation and analysis of the joint functioning. MR findings of surrounding tissues of the disk: Dynamic MRI of the tissues was found useful to see whether the cause of pain was present inside or outside of the articular capsule. Joint effusion could not be fully imaged in T2-weighted conditions. (K.H.)

MR diagnosis of temporomandibular arthrosis

International Nuclear Information System (INIS)

Suenaga, Shigeaki

1996-01-01

This review described lesions of articular disk and its surrounding tissues revealed by MR examination in temporomandibular arthrosis, and problems and limits of the examination. Apparatus and imaging methods: Spin echo method was generally used and gradient echo method was alternatively used. Author's apparatus was 1.5 tesla Signa, Advantage type, equipped with surface coil for temporomandibular joint. Imaging conditions were T1-weighted spin echo method, T2-weighted fast spin echo method, spoiled GRASS (gradient recalled acquisition in the steady state) method and GRASS method. MR findings of articular disk: MR images of normal and abnormal temporomandibular joint were presented together with computed radiographic findings. The role of dynamic imaging was described for evaluation and analysis of the joint functioning. MR findings of surrounding tissues of the disk: Dynamic MRI of the tissues was found useful to see whether the cause of pain was present inside or outside of the articular capsule. Joint effusion could not be fully imaged in T2-weighted conditions. (K.H.)

Cardiac and vascular imaging with snapshot FLASH MR imaging

International Nuclear Information System (INIS)

Matthaei, D.; Haase, A.; Norris, D.; Leibfritz, D.; Henrich, D.; Duhmke, E.

1989-01-01

Acceleration of fast low-angle-shot (FLASH) MR imaging to about 200 msec measuring time on dedicated MR systems is called snapshot FLASH MR imaging. It snaps real-time series of MR images of the MR relaxation and of physiologic motions with nearly absent motion and susceptibility artifacts. Results in animals (4.7T) and human volunteers (2.0T) show plain vascular and cardiac snapshot FLASH MR images obtained as single shot, triggered reconstructed motion, or real-time films. The reduction of artifacts and the high resolution (triggered, three-dimensional moving heart images are possible) result in favorable applications in myocardial and great vascular disease

Simultaneous acquisition of multislice PET and MR images: initial results with a MR-compatible PET scanner.

Science.gov (United States)

Catana, Ciprian; Wu, Yibao; Judenhofer, Martin S; Qi, Jinyi; Pichler, Bernd J; Cherry, Simon R

2006-12-01

PET and MRI are powerful imaging techniques that are largely complementary in the information they provide. We have designed and built a MR-compatible PET scanner based on avalanche photodiode technology that allows simultaneous acquisition of PET and MR images in small animals. The PET scanner insert uses magnetic field-insensitive, position-sensitive avalanche photodiode (PSAPD) detectors coupled, via short lengths of optical fibers, to arrays of lutetium oxyorthosilicate (LSO) scintillator crystals. The optical fibers are used to minimize electromagnetic interference between the radiofrequency and gradient coils and the PET detector system. The PET detector module components and the complete PET insert assembly are described. PET data were acquired with and without MR sequences running, and detector flood histograms were compared with the ones generated from the data acquired outside the magnet. A uniform MR phantom was also imaged to assess the effect of the PET detector on the MR data acquisition. Simultaneous PET and MRI studies of a mouse were performed ex vivo. PSAPDs can be successfully used to read out large numbers of scintillator crystals coupled through optical fibers with acceptable performance in terms of energy and timing resolution and crystal identification. The PSAPD-LSO detector performs well in the 7-T magnet, and no visible artifacts are detected in the MR images using standard pulse sequences. The first images from the complete system have been successfully acquired and reconstructed, demonstrating that simultaneous PET and MRI studies are feasible and opening up interesting possibilities for dual-modality molecular imaging studies.

MR imaging in hemophilic arthropathy

International Nuclear Information System (INIS)

Baunin, C.; Railhac, J.J.; Younes, I.; Gaubert, J.; DuBoullay, C.; Dirat, G.; Robert, A.

1990-01-01

This paper reports on twenty children with hemophilia examined to determine if MR imaging could be used to assess hemophilic arthropathy. Twenty-eight joints were imaged (17 knees, 10 ankles, 1 elbow) with plain radiography, US, CT, and MR imaging. The results were compared with the surgical view and histologic study of the articular components when synovectomy was done. These results show the usefulness of MR imaging: fluid collections in the joint space were evaluated, and it was possible to distinguish blood from inflammatory fluid. Synovial hypertrophy was appreciated, and findings correlated well with histologic study. Anomalies of articular cartilage, joint-space narrowing, and bone lesions were demonstrated early, when plain radiography findings were still normal

Retroperitoneal fibrosis: findings with MR

International Nuclear Information System (INIS)

Martinez Rodrigo, J.; Marti-Bonnati, L.; Diago, T.; Ferrer, M.D.; Aleixandre, A.; Morote, V.

1993-01-01

Retroperitoneal fibrosis (RF) is an uncommon disease characterized by the presence of a chronic inflammatory reaction, with the formation of fibrous tissue that replaces the normal retroperitoneal tissue, trapping vessels and/or ureters. We present a retrospective review of 3 cases of idiopathic RF studied by means of ultrasound, CT scan and MR imaging, and we assess the features of the MR image, as well as its capacity for characterizing the lesion. We compare the findings obtained with 3 imaging techniques, describing the utility of each one, and their advantages and disadvantages in the assessment of this pathology. In MR, idiopathic RF appears as a hypodense mass in SET1, SE-T2 and STIR sequences. (Author) 9 ref

Valuation of dynamic MR imaging for diagnosis of pituitary microadenomas

International Nuclear Information System (INIS)

Lu Wu; Zhou Shengli; Liu Yusheng

2003-01-01

Objective: To evaluate the use of keyhole dynamic magnetic resonance (MR) imaging in evaluation of pituitary microadenomas. Methods: Fifty-three patients with pituitary microadenomas proved by operation or clinical findings such as headache, amenorrhea, lactating, fat or acromegaly were retrospectively studied on dynamic MR, conventional contrast enhanced MR, and unenhanced MR. Then the image data were analyzed by two experienced doctors who didn't know the details and three degrees were made as follows: grade 0, no evidence of the tumor; grade I, asymmetry signals in the pituitary; and grade II, nodulated or sheets signals in the pituitary. The grading data were compared with statistical methods. Results: In dynamic MR grading system: grade 0 was revealed in 1 patient, grade I in 29 patients and grade II in 23 patients. In conventional enhanced MR: grade 0 in 26 patients, grade I in 17 patients and grade II in 10 patients. In conventional unenhanced MR: grade 0 in 39 patients, grade I in 10 patients and grade II in 4 patients. The diagnostic rate of dynamic MR, conventional enhanced MR, and unenhanced MR was 98.1%, 51.9%, and 26.4%, respectively. (P < 0.005). Dynamic MR can increase the grade of tumor compared to the other two, which is significant statistically. Conclusion: Keyhole dynamic MR can increase the diagnostic accuracy of pituitary microadenomas while decreasing the uncertainty. So dynamic MR should become a routine examination for pituitary microadenoma when suspected by clinical findings but negative in conventional MR

Multiparametric MR assessment of pediatric brain tumors

International Nuclear Information System (INIS)

Tzika, A.A.; Astrakas, L.G.; Zarifi, M.K.; Petridou, N.; Young-Poussaint, T.; Goumnerova, L.; Black, P.McL.; Zurakowski, D.; Anthony, D.C.

2003-01-01

MR assessment of pediatric brain tumors has expanded to include physiologic information related to cellular metabolites, hemodynamic and diffusion parameters. The purpose of this study was to investigate the relationship between MR and proton MR spectroscopic imaging in children with primary brain tumors. Twenty-one patients (mean age 9 years) with histologically verified brain tumors underwent conventional MR imaging, hemodynamic MR imaging (HMRI) and proton MR spectroscopic imaging (MRSI). Fourteen patients also had diffusion-weighted MR imaging (DWMRI). Metabolic indices including choline-containing compounds (Cho), total creatine (tCr) and lipids/lactate (L) were derived by proton MRSI, relative cerebral blood volume (rCBV) by HMRI, and apparent tissue water diffusion coefficients (ADC) by DWMRI. Variables were examined by linear regression and correlation as well as by ANOVA. Cho (suggestive of tumor cellularity and proliferative activity) correlated positively with rCBV, while the relationship between Cho and ADC (suggestive of cellular density) was inverse (P<0.001). The relationship between rCBV and ADC was also inverse (P=0.004). Cho and lipids (suggestive of necrosis and/or apoptosis) were not significantly correlated (P=0.51). A positive relationship was found between lipids and ADC (P=0.002). The relationships between Cho, rCBV, ADC and lipids signify that tumor physiology is influenced by the tumor's physical and chemical environment. Normalized Cho and lipids distinguished high-grade from low-grade tumors (P<0.05). Multiparametric MR imaging using MRSI, HMRI and DWMRI enhances assessment of brain tumors in children and improves our understanding of tumor physiology while promising to distinguish higher- from lower-malignancy tumors, a distinction that is particularly clinically important among inoperable tumors. (orig.)

MR imaging of an intrapericardial pheochromocytoma

International Nuclear Information System (INIS)

Fisher, M.R.; Higgins, C.B.; Andereck, W.

1985-01-01

The magnetic resonance (MR) appearance of an intrapericardial pheochromocytoma is reported, and the role of MR, compared with CT and a 131 I-metaiodobenzylguanidine scan in delineating masses from cardiac and vascular structures in the mediastinum is discussed

MR findings of bowlegs in toddlers

International Nuclear Information System (INIS)

Iwasawa, Tae; Inaba, Yutaka; Kameshita, Kikuo; Nishimura, Gen; Aida, Noriko; Matsubara, Sho

1999-01-01

Background. Toddlers with severe physiologic tibial bowing are considered to be at risk for the development of Blount's disease. Objective. To correlate MR findings of the knee with the clinical outcome in toddlers with severe physiological tibial bowing. Materials and methods. MR findings were evaluated in 22 affected legs of 14 children with severe tibial bowing (mean age 1.9 years). In 18 affected legs, MR findings were compared with the transition of the tibial metaphyseal-diaphyseal angle (MDA) and tibiofemoral angle (TFA) measured serially between 2 and 3 years of age. Results. MR findings of severe tibial bowing comprised undulation of the posteromedial physis of the tibia (3/22), signal alterations in the medial tibial metaphysis (10/22), T2 prolongation in the posteromedial tibial epiphyseal cartilage (14/22) and signal changes in the medial menisci (18/22). The decrease in the TFA was different in the legs with and without increased signal in the epiphyseal cartilage, and the decrease in the MDA was different in the legs with and without physeal undulation. Conclusion. MR imaging findings can predict the retarded resolution of tibial bowing, which may be a risk factor for the development of Blount's disease. (orig.)

Nontraumatic spinal epidural hematomas. MR features

International Nuclear Information System (INIS)

Loevblad, K.O.; Baumgartner, R.W.; Zambaz, B.D.; Remonda, L.; Ozdoba, C.; Schroth, G.

1997-01-01

Purpose: Spinal epidural hematoma (SEH) is a rare clinical entity with a bleak outcome. The aim of our study was to establish the value of MR findings in the diagnosis of nontraumatic SEH. Material and Methods: Seven patients with nontraumatic SEH were examined by MR at 1.5 T. Two patients were under anticoagulation therapy with heparin, and 2 others were taking salicylic acid. One patient had lupus erythematodes with a marked thrombocytopenia. One patient had a spinal arteriovenous malformation. Results: MR imaging permitted the accurate localization of extradural intraspinal expansive lesions which exhibited the characteristic signal intensities of blood. Five patients underwent laminectomy and evacuation of the hematoma. In the acute phase, the hematomas appeared isointense when compared with the spinal cord on T1-weighted images and hyperintense on T2-weighted images. Later the hematomas were hyperintense on T1-weighted images and showed signals identical to those of cerebrospinal fluid (CSF) on T2-weighted images. Conclusion: MR imaging established the exact diagnosis and localization of SEH in all cases. MR also can provide useful information about the age of the hematomas. (orig.)

MR imaging and histopathology of cartilage tumors

Energy Technology Data Exchange (ETDEWEB)

Mizutani, Hirokazu; Ohba, Satoru; Ohtsuka, Takanobu; Matui, Norio; Nakamura, Takaaki (Nagoya City Univ. (Japan). Faculty of Medicine)

1994-05-01

The MR imaging-pathologic correlation of cartilaginous bone tumors and the value of intravenously administered Gd-DTPA enhanced MR imaging was studied. The MR studies were retrospectively reviewed. Thirty-seven cases were examined with 0.5 T and 1.0 T scanner and all cases were pathologically proved. We discussed the following MR findings: signal intensities of tumors, Gd-DTPA features, morphological findings, and associated findings. Hyaline cartilage tumors showed low signal intensity on T[sub 1]-weighted images and very high signal intensity on T[sub 2]-weighted images. Lobulated marginal enhancements were recognized in chondrosarcomas. This may be an important finding to suspect chondrosarcoma. (author).

MR angiography of eddy-current-free MR imaging system with a 3T permanent magnet

International Nuclear Information System (INIS)

Nishimura, H.; Watanabe, S.; Takeuchi, H.

1991-01-01

This paper reports that, the authors main purpose was to evaluate two-dimensional time flight MR angiography in the visualization of vascular structure by using an eddy-current-free 0.3-T permanent magnet MR imaging system. The authors have developed multisection acquisition technique for two-dimensional time-of-flight MR angiography with the use of velocity-compensated gradient echoes. MR angiograms were obtained with a ray-tracing algorithm of the new modified maximum intensity projection at various viewing angles. These angiograms are displayed on cathode-ray tubes in a high-speed cyclic mode to depict the front-rear relation of vessels for better recognition. With an eddy-current-free permanent magnet system, two-dimensional time-of-flight angiography could clearly depict intracranial vascular structure, cervical vessels, and vessels of the extremities with thin-section (2 or 3 mm) acquisition. A high flip angle (90 degrees) with a short TR enabled better differentiation between blood flow and stationary tissues. Stenosis of the carotids could be detected in accordance with digital subtraction angiography

Investigating the generalisation of an atlas-based synthetic-CT algorithm to another centre and MR scanner for prostate MR-only radiotherapy

Science.gov (United States)

Wyatt, Jonathan J.; Dowling, Jason A.; Kelly, Charles G.; McKenna, Jill; Johnstone, Emily; Speight, Richard; Henry, Ann; Greer, Peter B.; McCallum, Hazel M.

2017-12-01

There is increasing interest in MR-only radiotherapy planning since it provides superb soft-tissue contrast without the registration uncertainties inherent in a CT-MR registration. However, MR images cannot readily provide the electron density information necessary for radiotherapy dose calculation. An algorithm which generates synthetic CTs for dose calculations from MR images of the prostate using an atlas of 3 T MR images has been previously reported by two of the authors. This paper aimed to evaluate this algorithm using MR data acquired at a different field strength and a different centre to the algorithm atlas. Twenty-one prostate patients received planning 1.5 T MR and CT scans with routine immobilisation devices on a flat-top couch set-up using external lasers. The MR receive coils were supported by a coil bridge. Synthetic CTs were generated from the planning MR images with (sCT1V ) and without (sCT) a one voxel body contour expansion included in the algorithm. This was to test whether this expansion was required for 1.5 T images. Both synthetic CTs were rigidly registered to the planning CT (pCT). A 6 MV volumetric modulated arc therapy plan was created on the pCT and recalculated on the sCT and sCT1V . The synthetic CTs’ dose distributions were compared to the dose distribution calculated on the pCT. The percentage dose difference at isocentre without the body contour expansion (sCT-pCT) was Δ D_sCT=(0.9 +/- 0.8) % and with (sCT1V -pCT) was Δ D_sCT1V=(-0.7 +/- 0.7) % (mean  ±  one standard deviation). The sCT1V result was within one standard deviation of zero and agreed with the result reported previously using 3 T MR data. The sCT dose difference only agreed within two standard deviations. The mean  ±  one standard deviation gamma pass rate was Γ_sCT = 96.1 +/- 2.9 % for the sCT and Γ_sCT1V = 98.8 +/- 0.5 % for the sCT1V (with 2% global dose difference and 2~mm distance to agreement gamma criteria). The one voxel body contour

MR imaging in cervical hyperextension injuries

International Nuclear Information System (INIS)

Davis, S.J.; Teresi, L.M.; Bradley, W.G. Jr.; Ziemba, M.R.

1990-01-01

This paper reports on cervical hyperextension injuries that are common and often show minimal radiographic abnormalities, even with severe or unstable lesions. MR images and clinical records of 14 patients scanned within 4 months of hyperextension cervical injuries were reviewed. Clinical, radiographic, and MR findings were correlated. Nine patients had acceleration hyperextension whiplash injuries, four with acute cervical disk herniations developing radiculopathy after several weeks. Five patients injured by direct frontal head trauma presented with myelopathy and had MR evidence of cord injury, and four had acute disk herniation

MR imaging and spinal cord injury

International Nuclear Information System (INIS)

Azar-Kia, B.; Fine, M.; Naheedy, M.; Elias, D.

1987-01-01

MR imaging has significantly improved diagnostic capability of spinal cord injuries. Other available diagnostic modalities such as plain films, myelography, CT, and post-CT myelography have failed to consistently show the secific evidence of spinal cord injuries and their true extent. The authors are presenting our experiences with MR imaging in spinal column injury. They have found MR imaging to be the procedure of choice for prognostic evaluation of spinal cord trauma. They are showing examples of recent and old spinal cord injury such as hematomyelia, myelomalacia, transection, spinal cord edema, and cavitation

MR imaging of heterotopic gray matter

International Nuclear Information System (INIS)

Kryst-Widzgowska, T.; Kozlowski, P.; Poniatowska, R.

1994-01-01

Six patients with heterotopic gray matter were evaluated with MR. 5 patients had history of seizures. 4 cases were suspected of the cerebral tumor. In the MR examination areas of heterotopic gray matter were found along the posterior horn of the lateral ventricle on the one side in 4 cases and bilateraly in 2 cases. In 3 cases another brain abnormalities were also detected including: hypoplasia of corpus callosum, hypoplasia of brain hemisphere, cavum septi pellucidi. MR is a modality of choice in the assessment of abnormal gray matter migration. (author)

Rectal cancer: assessment of complete response to preoperative combined radiation therapy with chemotherapy--conventional MR volumetry versus diffusion-weighted MR imaging.

Science.gov (United States)

Curvo-Semedo, Luís; Lambregts, Doenja M J; Maas, Monique; Thywissen, Thomas; Mehsen, Rana T; Lammering, Guido; Beets, Geerard L; Caseiro-Alves, Filipe; Beets-Tan, Regina G H

2011-09-01

To determine diagnostic performance of diffusion-weighted (DW) magnetic resonance (MR) imaging for assessment of complete tumor response (CR) after combined radiation therapy with chemotherapy (CRT) in patients with locally advanced rectal cancer (LARC) by means of volumetric signal intensity measurements and apparent diffusion coefficient (ADC) measurements and to compare the performance of DW imaging with that of T2-weighted MR volumetry. A retrospective analysis of 50 patients with LARC, for whom clinical and imaging data were retrieved from a previous imaging study approved by the local institutional ethical committee and for which all patients provided informed consent, was conducted. Patients underwent pre- and post-CRT standard T2-weighted MR and DW MR. Two independent readers placed free-hand regions of interest (ROIs) in each tumor-containing section on both data sets to determine pre- and post-CRT tumor volumes and tumor volume reduction rates (volume). ROIs were copied to an ADC map to calculate tumor ADCs. Histopathologic findings were the standard of reference. Receiver operating characteristic (ROC) curves were generated to compare performance of T2-weighted and DW MR volumetry and ADC. The intraclass correlation coefficient (ICC) was used to evaluate interobserver variability and the correlation between T2-weighted and DW MR volumetry. Areas under the ROC curve (AUCs) for identification of a CR that was based on pre-CRT volume, post-CRT volume, and volume, respectively, were 0.57, 0.70, and 0.84 for T2-weighted MR versus 0.63, 0.93, and 0.92 for DW MR volumetry (P = .15, .02, .42). Pre- and post-CRT ADC and ADC AUCs were 0.55, 0.54, and 0.51, respectively. Interobserver agreement was excellent for all pre-CRT measurements (ICC, 0.91-0.96) versus good (ICC, 0.61-0.79) for post-CRT measurements. ICC between T2-weighted and DW MR volumetry was excellent (0.97) for pre-CRT measurements versus fair (0.25) for post-CRT measurements. Post-CRT DW MR

MR in plasmocytoma

International Nuclear Information System (INIS)

Linden, A.; Widder, R.; Jungehuelsing, M.; Schicha, H.; Gueckel, C.; Diehl, V.

1992-01-01

In 20 patients with multiple myeloma, the results of MR, X-ray, bone scintigraphy, bone marrow scintigraphy and bone marrow biopsy were compared. MR proved the most sensitive imaging method for the detection of bone marrow infiltration followed by X-ray examinations. Bone marrow scintigraphy and especially bone scintigraphy revealed false negative results more often. These findings were more impressive by the direct comparison of several investigated regions showing different findings of each imaging method. False positive results were not found. In 4 patients false negative results of bone marrow biopsy had to be assumed because of definitely pathological findings by X-ray and MRI. (orig.) [de

Mr Bjarne Mork-Eidem, Director General, Norwegian State Audit

CERN Multimedia

Maximilien Brice

2003-01-01

Photos 01,02: Mr Bjarne Mørk-Eidem, Auditor General of Norway (centre) visiting the ATLAS assembly hall in building 180, with from left to right: Prof. Steinar Stapnes, University of Oslo ; Mr Per Ivar Lied, Permanent Mission of Norway, Geneva ; Prof. Egil Lillestøl, University of Bergen and Mr Jan Otto Jøranli, Office of the Auditor General of Norway, May 2003. Photo 03: Mr Bjarne Mørk-Eidem, Auditor General of Norway (left) visiting the ATLAS assembly hall in building 180, with from left to right: Mr Jan Otto Jøranli, Office of the Auditor General of Norway ; Prof. Steinar Stapnes, University of Oslo and Prof. Egil Lillestøl, University of Bergen, May 2003. Photo 04: Mr Bjarne Mørk-Eidem, Auditor General of Norway, during his visit of the ATLAS assembly hall in building 180, May 2003. Photo 05: From left to right: Mr Jan Otto Jøranli, Office of the Auditor General of Norway ; Mr Bjarne Mørk-Eidem, Auditor General of Norway; Prof. Egil Lillestøl, University of Bergen and Prof. Steinar Stapnes, Univ...

MR imaging and MR spectroscopy for characterization of cardiomyopathies in adolescents - preliminary results

International Nuclear Information System (INIS)

Beer, M.; Buchner, S.; Fuchs, J.; Machann, W.; Ritter, C.O.; Beissert, M.; Darge, K.; Hahn, D.; Koestler, H.; Wirbelauer, J.

2007-01-01

Purpose: Cardiomyopathy is a rare but life-threatening disease in children and adolescents. Recent studies reported morphological, functional or metabolic alterations of the heart. We discuss a combined MR imaging and 31 P MR spectroscopy (MRS) protocol allowing the analysis of interdependencies between these parameters. Since normal values of cardiac MR parameters in this age group are not available, we included studies of age-matched healthy adolescents. Materials and Methods: 2D-CINE was used to assess left ventricular (LV) parameters. Additional 3D-Chemical Shift Imaging (3D-CSI) and Spectral Localization with Optimal Pointspread Function (SLOOP) reconstruction allowed quantification of the cardiac energy metabolism. Patients (n = 4; all male; age 16.8 ± 2.9 years) were included on the basis of an echocardiographic diagnosis of possible cardiomyopathy. The same protocol was applied to healthy young volunteers (n = 4; 1 female, 3 male; age 15.5 ± 0.6 years). Results: The patients had a significantly higher LV mass index compared to the control group (147 ± 41 g/m2 versus 97 ± 16 g/m2; p = 0.04). The other LV parameters (including LV EF with 59 ± 22 % versus 67 ± 10 %) showed no significant differences. The phosphocreatine to adenosine triphosphate ratio (PCr/ATP-ratio) of the patients was reduced to 1.71 ± 0.40 versus 2.44 ± 0.30 (p = 0.01), combined with a tendency towards decreased PCr concentrations of 9.1 ± 2.5 versus 7.9 ± 1.0 mmol/kg. Conclusion: The combination of 31 P MR spectroscopy and MR imaging allows quantitative determination of morphologic, functional and metabolic alterations in adolescents with suspected cardiomyopathy in one examination procedure. The reduction of energy metabolism combined with unaltered global function may indicate a primary role of metabolism in the pathogenesis of cardiomyopathies in adolescents. (orig.)

Gd-DTPA administered MR imaging of intracranial mass lesions

International Nuclear Information System (INIS)

Mihara, Futoshi; Hirakata, Ryosuke; Hasuo, Kanehiro; Yasumori, Kotaro; Yoshida, Kisaku; Kuroiwa, Toshiro; Masuda, Kouji; Fukui, Masashi

1989-01-01

Magnetic resonance (MR) images of 13 intracranial mass lesions taken with the intravenous administration of gadolinium-DTPA were evaluated in comparison with precontrast computed tomography (CT), postcontrast CT, and precontrast MR. In the MR images taken with Gd-DTPA, tumor delineation improved in eight of 13 cases (62%) in comparison with precontrast MR images, and in seven of 13 cases (54%) in comparison with the overall evaluation of precontrast CT, postcontrast CT, and precontrast MR images. Tumor demarcation was unchanged in the remaining cases; no deterioration was observed with Gd-DTPA administration. MR imaging with Gd-DTPA should be performed to better evaluate the extent of intracranial mass lesions and to provide additional information. (author)

An investigation of Saudi Arabian MR radiographers' knowledge and confidence in relation to MR image-quality-related errors

International Nuclear Information System (INIS)

Alsharif, W.; Davis, M.; McGee, A.; Rainford, L.

2017-01-01

Objective: To investigate MR radiographers' current knowledge base and confidence level in relation to quality-related errors within MR images. Method: Thirty-five MR radiographers within 16 MRI departments in the Kingdom of Saudi Arabia (KSA) independently reviewed a prepared set of 25 MR images, naming the error, specifying the error-correction strategy, scoring how confident they were in recognising this error and suggesting a correction strategy by using a scale of 1–100. The datasets were obtained from MRI departments in the KSA to represent the range of images which depicted excellent, acceptable and poor image quality. Results: The findings demonstrated a low level of radiographer knowledge in identifying the type of quality errors and when suggesting an appropriate strategy to rectify those errors. The findings show that only (n = 7) 20% of the radiographers could correctly name what the quality errors were in 70% of the dataset, and none of the radiographers correctly specified the error-correction strategy in more than 68% of the MR datasets. The confidence level of radiography participants in their ability to state the type of image quality errors was significantly different (p < 0.001) for who work in different hospital types. Conclusion: The findings of this study suggest there is a need to establish a national association for MR radiographers to monitor training and the development of postgraduate MRI education in Saudi Arabia to improve the current status of the MR radiographers' knowledge and direct high quality service delivery. - Highlights: • MR radiographers recognised the existence of the image quality related errors. • A few MR radiographers were able to correctly identify which image quality errors were being shown. • None of MR radiographers were able to correctly specify error-correction strategy of the image quality errors. • A low level of knowledge was demonstrated in identifying and rectify image quality errors.

Pseudodynamic MR imaging of temporomandibular joint disorders

International Nuclear Information System (INIS)

Nakasato, Tatsuhiko; Ehara, Shigeru

1992-01-01

Magnetic resonance (MR) imaging of the temporomandibular joint (TMJ) has now been established as a procedure of choice in the evaluation of TMJ disorders. In this study, we evaluated the dynamics of TMJ motion on MR imaging, which resembles arthrography. Sixty-eight TMJs in 38 symptomatic patients and one healthy volunteer were examined using pseudodynamic images with gradient echo sequences using a 0.5 Tesla MR unit and 8 cm circular planar surface coil. For depiction of each compartment of the meniscus, the optimum sequence was 200/15/2 (TR/TE/excitations) with 50 deg or 60 deg flip angle in gradient refocused acquisition in steady-state (GRASS) sequences. Three contiguous slices on sagittal MR images were routinely obtained at 14-18 different phases of the opening cycle and displayed in closed-loop cine fashion. Internal derangement was observed in 57% of 68 joints. The most common type was anterior meniscal displacement without reduction. Sideway and rotational displacements, observed in 10% each, were noted on both sagittal multislice images and axial reference images. As a pseudodynamic MR technique, jaw movement specifically designed to check bite procedure to adjust splints is useful for detecting the exact time of meniscal redisplacement on the second click. After conservative therapy for arthrosis, pseudodynamic MR provided information on changes in the meniscus and condylar relationship. Pseudodynamic MR with multiple phases is suitable for evaluating subtle motion abnormality of the meniscus and for post-therapeutic monitoring. (author)

Pseudodynamic MR imaging of temporomandibular joint disorders

Energy Technology Data Exchange (ETDEWEB)

Nakasato, Tatsuhiko; Ehara, Shigeru (Iwate Medical Coll., Morioka (Japan). School of Medicine)

1992-09-01

Magnetic resonance (MR) imaging of the temporomandibular joint (TMJ) has now been established as a procedure of choice in the evaluation of TMJ disorders. In this study, we evaluated the dynamics of TMJ motion on MR imaging, which resembles arthrography. Sixty-eight TMJs in 38 symptomatic patients and one healthy volunteer were examined using pseudodynamic images with gradient echo sequences using a 0.5 Tesla MR unit and 8 cm circular planar surface coil. For depiction of each compartment of the meniscus, the optimum sequence was 200/15/2 (TR/TE/excitations) with 50 deg or 60 deg flip angle in gradient refocused acquisition in steady-state (GRASS) sequences. Three contiguous slices on sagittal MR images were routinely obtained at 14-18 different phases of the opening cycle and displayed in closed-loop cine fashion. Internal derangement was observed in 57% of 68 joints. The most common type was anterior meniscal displacement without reduction. Sideway and rotational displacements, observed in 10% each, were noted on both sagittal multislice images and axial reference images. As a pseudodynamic MR technique, jaw movement specifically designed to check bite procedure to adjust splints is useful for detecting the exact time of meniscal redisplacement on the second click. After conservative therapy for arthrosis, pseudodynamic MR provided information on changes in the meniscus and condylar relationship. Pseudodynamic MR with multiple phases is suitable for evaluating subtle motion abnormality of the meniscus and for post-therapeutic monitoring. (author).

Cardiac MR imaging: Comparison with echocardiography and dynamic CT

International Nuclear Information System (INIS)

Colletti, P.M.; Norris, S.; Raval, J.; Boswell, W.; Lee, K.; Ralls, P.; Haywood, J.; Halls, J.

1986-01-01

The authors compared gated cardiac MR imaging with two-dimensional and Doppler echocardiography and dynamic CT. Gated cardiac MR imaging (VISTA unit, 0.5 T) was performed in 55 patients with a variety of conditions. Accuracy of diagnosis was compared. CT showed arterial, valvular, and pericardial calcifications not seen on MR imaging. Many lesions were seen as well on CT as on MR imaging. Two-dimensional echocardiography was superior in demonstrating wall motion and valvular disease. MR imaging was superior in demonstrating myocardial structures

Traumatic spinal cord injury in MR imaging; Urazowe przerwanie ciaglosci rdzenia kregowego w obrazie MR

Energy Technology Data Exchange (ETDEWEB)

Bronarski, J.; Wozniak, E. [Stoleczne Centrum Rehabilitacji, Konstancin (Poland)]|[Inst. Psychiatrii i Neurologii, Warsaw (Poland)

1993-12-31

Spinal cord injuries in tetraplegics were briefly discussed on the basis of MR imaging. It was found that severe cervical spine trauma usually results in concussion - the complete transection of the cord is rare. A case of 19 years old male with total cord transection confirmed by MR imaging is described. (author). 5 refs, 3 figs.

WE-H-207B-02: MR-Driven RT Planning

Energy Technology Data Exchange (ETDEWEB)

Cao, M. [UCLA School of Medicine (United States)

2016-06-15

In recent years, steady progress has been made towards the implementation of MRI in external beam radiation therapy for processes ranging from treatment simulation to in-room guidance. Novel procedures relying mostly on MR data are currently implemented in the clinic. This session will cover topics such as (a) commissioning and quality control of the MR in-room imagers and simulators specific to RT, (b) treatment planning requirements, constraints and challenges when dealing with various MR data, (c) quantification of organ motion with an emphasis on treatment delivery guidance, and (d) MR-driven strategies for adaptive RT workflows. The content of the session was chosen to address both educational and practical key aspects of MR guidance. Learning Objectives: Good understanding of MR testing recommended for in-room MR imaging as well as image data validation for RT chain (e.g. image transfer, filtering for consistency, spatial accuracy, manipulation for task specific); Familiarity with MR-based planning procedures: motivation, core workflow requirements, current status, challenges; Overview of the current methods for the quantification of organ motion; Discussion on approaches for adaptive treatment planning and delivery. T. Stanescu - License agreement with Modus Medical Devices to develop a phantom for the quantification of MR image system-related distortions.; T. Stanescu, N/A.

WE-H-207B-02: MR-Driven RT Planning

International Nuclear Information System (INIS)

Cao, M.

2016-01-01

In recent years, steady progress has been made towards the implementation of MRI in external beam radiation therapy for processes ranging from treatment simulation to in-room guidance. Novel procedures relying mostly on MR data are currently implemented in the clinic. This session will cover topics such as (a) commissioning and quality control of the MR in-room imagers and simulators specific to RT, (b) treatment planning requirements, constraints and challenges when dealing with various MR data, (c) quantification of organ motion with an emphasis on treatment delivery guidance, and (d) MR-driven strategies for adaptive RT workflows. The content of the session was chosen to address both educational and practical key aspects of MR guidance. Learning Objectives: Good understanding of MR testing recommended for in-room MR imaging as well as image data validation for RT chain (e.g. image transfer, filtering for consistency, spatial accuracy, manipulation for task specific); Familiarity with MR-based planning procedures: motivation, core workflow requirements, current status, challenges; Overview of the current methods for the quantification of organ motion; Discussion on approaches for adaptive treatment planning and delivery. T. Stanescu - License agreement with Modus Medical Devices to develop a phantom for the quantification of MR image system-related distortions.; T. Stanescu, N/A

MR arthrography of the shoulder: possible indications for clinical use

International Nuclear Information System (INIS)

Kreitner, K.F.; Grebe, P.; Kersjes, W.; Runkel, M.; Kirschner, P.; Schild, H.H.

1994-01-01

In a prospective study possible indications for MR arthrography of the shoulder were evaluated. 37 patients were examined before and after intraarticular administration of a 2-mmolar solution of Gd-DTPA. MR arthrography was performed if there was no joint effusion and/or an uncertain finding concerning the rotator cuff or the capsulolabral complex on plain MR images. MR arthrography leads to a better demonstration of labrum pathology in 11/22 patients and to a superior delineation of the capsuloligamentous apparatus in 20/22 cases. In 9/15 patients with impingement lesions MR arthrography allowed a differentiation of severe tendinitis from partial and small full-thickness tears of the rotator cuff. MR arthrography of the shoulder joint enhances the accuracy of MR in case of an uncertain finding on plain MR images. (orig.) [de

Prenatal MR imaging of congenital diaphragmatic hernias: association of MR fetal lung volume with the need for postnatal prosthetic patch repair

Energy Technology Data Exchange (ETDEWEB)

Hagelstein, Claudia; Weidner, Meike; Schoenberg, Stefan O.; Buesing, Karen A.; Neff, K.W. [University of Heidelberg, Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Mannheim (Germany); Zahn, Katrin [University of Heidelberg, Department of Pediatric Surgery, University Medical Center Mannheim, Mannheim (Germany); Weiss, Christel [University of Heidelberg, Department of Medical Statistics and Biomathematics, University Medical Center Mannheim, Mannheim (Germany); Schaible, Thomas [University of Heidelberg, Department of Pediatrics, University Medical Center Mannheim, Mannheim (Germany)

2015-01-15

To assess whether the need for postnatal prosthetic patch repair of the diaphragmatic defect in neonates with a congenital diaphragmatic hernia (CDH) is associated with the antenatal measured observed-to-expected magnetic resonance fetal lung volume (o/e MR-FLV). The o/e MR-FLV was calculated in 247 fetuses with isolated CDH. Logistic regression analysis was used to assess the prognostic value of the individual o/e MR-FLV for association with the need for postnatal patch repair. Seventy-seven percent (77 %) of patients with a CDH (190/247) required prosthetic patch repair and the defect was closed primarily in 23 % (57/247). Patients requiring a patch had a significantly lower o/e MR-FLV (27.7 ± 10.2 %) than patients with primary repair (40.8 ± 13.8 %, p < 0.001, AUC = 0.786). With an o/e MR-FLV of 20 %, 92 % of the patients required patch repair, compared to only 24 % with an o/e MR-FLV of 60 %. The need for a prosthetic patch was further influenced by the fetal liver position (herniation/no herniation) as determined by magnetic resonance imaging (MRI; p < 0.001). Fetal liver position, in addition to the o/e MR-FLV, improves prognostic accuracy (AUC = 0.827). Logistic regression analysis based on the o/e MR-FLV is useful for prenatal estimation of the prosthetic patch requirement in patients with a CDH. In addition to the o/e MR-FLV, the position of the liver as determined by fetal MRI helps improve prognostic accuracy. (orig.)

Functional-anatomic evaluation of dilated uropathies in children using combined MR-nephrography and MR-urography compared to renal scintigraphy; Funktionell-anatomische Diagnostik dilatierter Uropathien bei Kindern mit kombinierter MR-Nephrographie und MR-Urographie im Vergleich zur renalen Isotopennephrographie

Energy Technology Data Exchange (ETDEWEB)

Reither, M. [Abt. fuer bildgebende Diagnostik am Kinderkrankenhaus Park Schoenfeld, Kassel (Germany); Tuerkay, S. [GE Medical Systems Deutschland GmbH, Solingen (Germany)

2004-02-01

Purpose: to evaluate MR-tomographic assessment of split renal function and degree of obstruction compared to diuretic renal scintigraphy, and pathoanatomic imaging of the urinary tract as all in one exam. Patients and methods: in a prospective study 62 children, aged 1 month to 9.5 years, mean 2.8 years, underwent diuretic renal scintigraphy and dynamic MR-nephrography at the same day except for 7 patients with a time interval of 1 day. In all patients we did T2w (water-technique) MR-urography additionally. Results: comparing spilt renal function we found a very close correlation in 54 out of 62 patients (correlation coefficient = 0.95). Due to technical failures 8 cases couldn't be calculated. Comparing degrees of obstruction there was an agreement in 57 out of 62 patients, 3 studies were gradually over-, 2 underestimated. All but one morphologic diagnoses in advance obtained by ultrasound and completed by other imaging modalities later on were confirmed MR-urographically. Though correctly imaged the functionless upper moiety in a renal duplication with ureterocele was misinterpreted at a first glance. (orig.) [German] Ziel: Es sollte geprueft werden, ob die Berechnung der seitengetrennten Nierenfunktion, die Bestimmung des Obstruktionsgrades und die pathoanatomische Darstellung des Harntraktes im Vergleich zur Diurese-Szintigraphie in einem Untersuchungsgang MR-tomographisch zuverlaessig moeglich ist. Patienten und Methode: In einer prospektiven Studie wurden bei 62 Kindern im Alter von 1 Monat bis 9,5 Jahren, Mittelwert 2,8 Jahre, ein Diurese-Szintigramm und eine dynamische MR-Nephrographie am gleichen Tag durchgefuehrt; lediglich bei 7 Patienten lag 1 Tag zwischen beiden Untersuchungen. Alle Patienten erhielten zusaetzlich eine T2w-MR-Urographie in ''Wasserbild''-Technik. Ergebnisse: Beim Vergleich der seitengetrennten Nierenfunktion fand sich eine sehr enge Korrelation bei 54 von insgesamt 62 Patienten (Korrelationskoeffizient = 0

Correlation of angiography and MR imaging in cerebral vasculitis

International Nuclear Information System (INIS)

Cloft, H.J.; Phillips, C.D.; Dix, J.E.; McNulty, B.C.; Kallmes, D.F.; Zagardo, M.T.

1999-01-01

Purpose: MR imaging and cerebral angiography were correlated in patients with primary angiitis of the central nervous system (PACNS) to assess the relative roles of these imaging modalities in the diagnosis. Material and Methods: In 9 patients, MR imaging and angiography were compared with regard to the relative involvement of each major vascular territory. Vascular territories assessed were the anterior, middle, and posterior cerebral arteries, and the posterior fossa. Results: All patients had angiographic findings consistent with vasculitis in multiple vascular territories. MR findings ranged from normal to diffusely abnormal. One patient had a completely normal MR investigation. Of 50 territories affected by vasculitis on angiography, 17 (34%) were normal on MR. Conclusion: Relative to cerebral angiography, MR imaging is a poor indicator of the presence or absence of PACNS. Angiography is indicated when clinical suspicion of PACNS is strong, regardless of the findings on MR. (orig.)

MR imaging of acute transverse myelitis (myelopathy)

Energy Technology Data Exchange (ETDEWEB)

Isoda, Haruo [Hamamatsu Univ., Shizuoka (Japan). School of Medicine; Ramsey, R.G.

1998-05-01

The purpose of our study was to review the MR characteristics of acute transverse myelitis (ATM) retrospectively and to review the literature. The subjects were 26 patients (two males, 24 females). MR examinations were carried out using a 1.5 Tesla scanner. MR imaging in eight of 16 lesions in nine subjects with preexisting MS showed multiple areas of increased signal intensity on T{sub 2}-weighted sagittal images, and 11 lesions had no cord swelling. Twelve of 16 lesions showed heterogeneous enhancement. MR imaging in 10 of 13 lesions in 12 subjects with preexisting HTLV-1 infection, mycoplasma pneumonia infection, hepatitis B vaccinations, and uncertain etiologies revealed fusiform increased signal intensity areas on T{sub 2}-weighted sagittal images and cord swelling. Seven of 11 lesions in the patients who underwent injection of contrast medium showed heterogeneous enhancement, whereas others showed no enhancement. MR examination is recommended for the evaluation of ATM. (author)

MR plaque imaging of the carotid artery

International Nuclear Information System (INIS)

Watanabe, Yuji; Nagayama, Masako

2010-01-01

Atherosclerotic carotid plaque represents a major cause of cerebral ischemia. The detection of vulnerable plaque is important for preventing future cardiovascular events. The key factors in advanced plaque that are most likely to lead to patient complications are the condition of the fibrous cap, the size of the necrotic core and hemorrhage, and the extent of inflammatory activity within the plaque. Magnetic resonance (MR) imaging has excellent soft tissue contrast and can allow for a more accurate and objective estimation of carotid wall morphology and plaque composition. Recent advances in MR imaging techniques have permitted serial monitoring of atherosclerotic disease evolution and the identification of intraplaque risk factors for accelerated progression. The purpose of this review article is to review the current state of techniques of carotid wall MR imaging and the characterization of plaque components and surface morphology with MR imaging, and to describe the clinical practice of carotid wall MR imaging for the determination of treatment plan. (orig.)

MR appearance of skeletal neoplasms following cryotherapy

Energy Technology Data Exchange (ETDEWEB)

Richardson, M.L. [Dept. of Radiology SB-05, Washington Univ., Seattle, WA (United States); Lough, L.R. [Pitts Radiological Associates, Columbia, SC (United States); Shuman, W.P. [Dept. of Radiology, Medical Center Hospital of Vermont, Burlington, VT (United States); Lazerte, G.D. [Dept. of Pathology RC-72, Washington Univ., Medical Center Hospital of Vermont, Burlington, VT (United States); Conrad, E.U. [Dept. of Orthopedic Surgery RK-10, Washington Univ., Medical Center of Vermont, Burlington, VT (United States)

1994-02-01

Cryotherapy is an increasingly popular mode of therapy adjunctive to surgical curettage in the treatment of certain skeletal neoplasms, such as giant cell tumors or chondrosarcomas. The magnetic resonance (MR) findings following cryotherapy have not been previously reported. We reviewed the MR findings in seven patients with skeletal neoplasms following curettage and cryotherapy. In six cases we found a zone of varying thickness extending beyond the surgical margins, corresponding to an area of cryoinjury to medullary bone. This zone displayed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, consistent with the presence of marrow edema. This zone of edema almost certainly reflects underlying thermal osteonecrosis. This zone may vary in size and intensity over time as the area of cryoinjury evolves or resolves. MR is currently the imaging procedure of choice for follow-up of most musculoskeletal neoplasms. Knowledge of the MR findings following cryotherapy should help prevent confusion during the interpretation of follow-up MR examinations. (orig.)

MR appearance of skeletal neoplasms following cryotherapy

International Nuclear Information System (INIS)

Richardson, M.L.; Lough, L.R.; Shuman, W.P.; Lazerte, G.D.; Conrad, E.U.

1994-01-01

Cryotherapy is an increasingly popular mode of therapy adjunctive to surgical curettage in the treatment of certain skeletal neoplasms, such as giant cell tumors or chondrosarcomas. The magnetic resonance (MR) findings following cryotherapy have not been previously reported. We reviewed the MR findings in seven patients with skeletal neoplasms following curettage and cryotherapy. In six cases we found a zone of varying thickness extending beyond the surgical margins, corresponding to an area of cryoinjury to medullary bone. This zone displayed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, consistent with the presence of marrow edema. This zone of edema almost certainly reflects underlying thermal osteonecrosis. This zone may vary in size and intensity over time as the area of cryoinjury evolves or resolves. MR is currently the imaging procedure of choice for follow-up of most musculoskeletal neoplasms. Knowledge of the MR findings following cryotherapy should help prevent confusion during the interpretation of follow-up MR examinations. (orig.)

Reflex sympathetic dystrophy syndrome: MR imaging study

International Nuclear Information System (INIS)

Masciocchi, C.; Fascetti, E.; Bonanni, G.; Calvisi, V.; Buoni, C.; Passariello, R.

1987-01-01

Reflex sympathetic dystrophy syndrome (RSDS) is characterized by pain, swelling, and limitation of motion. The etiology and pathophysiology mechanism have not yet been identified. We considered eight patients with clinical signs of RSDS, in five cases located at the knee joint and in three cases in the hip. In all cases conventional radiography and radionuclide bone scanning were performed before MR imaging. Conventional radiography was negative in three cases while scintigraphy demonstrated the lesion in all patients. MR imaging showed an area of low intensity signal on T1-weighted scans and an increased signal intensity on T2-weighted images. This area is located at the bone marrow and its regular and homogeneous. This specific finding on MR images is due to reflect edema by hyperemia of the bone marrow. The MR imaging diagnosis was confirmed on clinical and radiological follow-up. MR imaging can have a role in the differential diagnosis when other studies are nondiagnostic or nonspecific for RSDS

Value of MR-angiography in brain infarction

International Nuclear Information System (INIS)

Pirronello, Veronica; Capizzano, Aristides A.; Chouela, Carolina L.; Ternak, Alejandro; Ramirez, Susana; Mazzuco, Juan C.

2004-01-01

A retrospective study has been performed in a series of 237 patients, with brain and neck MR and MR angiography techniques. 108/237 (45.5%) patients presented either hemorrhage or lacunar and non lacunar ischemic stroke, 67 of which showed restricted diffusion. Diffusion and perfusion techniques can significantly contribute to study acute stroke. In our series MR angiography showed a 4% sensitivity to detect small arteries pathology. (author)

MR imaging exploration of the pituitary region

International Nuclear Information System (INIS)

Braun, M.; Roland, J.; Moret, C.; Picard, L.

1992-01-01

MR Imaging has become the procedure of choice for the exploration of the pituitary region. MR contrast resolution is far better than the finest CT examination, especially concerning the microadenomas and the neurohypophysis. The present paper concerns, at first the major principles of magnetic resonance imaging, its application for the study of the pituitary region including the use of contrast agent (Gadolinium). Lastly, MR anatomy and physiological variations are presented

MR of experimental cerebral ischemia

International Nuclear Information System (INIS)

DeLaPaz, R.; Steinberg, G.; Rocklage, S.; Glover, G.H.

1990-01-01

This paper reports on MR imaging of cerebral ischemia and treatment with N-methyl-D-aspartate (NMDA) antagonists in an animal model. Forty-four New Zealand white rabbits underwent 1-hour transorbital ICA-MCA-ACA occlusion and pretreatment or immediate posttreatment with systemic dextromethorphan (DM, n = 14), dextrorphan (DX, n = 14), or normal saline (NS, n = 16). Serial MR studies (1.5 T) were performed 1--6 hours after occlusion with T1- and T2-weighted spinecho, IVIM (b = 1,352), gradient recalled acquisition in a steady-state, and chemical shift sequences (for magnetic susceptibility, T2* and T2') and DyDTPA-BMA intravenous contrast material (Salutar). Spatial correlation between MR findings, histologic findings (ischemic neuronal damage), and regional cerebral blood flow (microspheres) was done

MR imaging findings and MR criteria for instability in osteochondritis dissecans of the elbow in children

International Nuclear Information System (INIS)

Jans, Lennart B.O.; Ditchfield, Michael; Anna, Gomez; Jaremko, Jacob L.; Verstraete, Koenraad L.

2012-01-01

Purpose: Osteochondritis dissecans (OCD) of the elbow is an uncommon cause of elbow pain in adolescents and occurs at different locations in the elbow joint. Early diagnosis and treatment may prevent surgery. The aim of the study is to describe the MR imaging features of OCD at initial imaging, and to correlate these findings with surgical findings of stability and instability with arthroscopic findings as the reference standard. Methods: Patients were identified through a keyword search of the radiology information system from 2000 to 2009. Twenty-five patients (26 elbows) with OCD of the elbow were identified (age 10.4–18 years, mean age 14 years). MR studies were retrospectively reviewed by two radiologists in consensus to define MR imaging findings and to determine the presence of previously described MR imaging criteria for OCD instability (i.e., high T2 signal rim, surrounding cysts, high T2 signal fracture line, fluid-filled osteochondral defect). Sensitivity of the individual and combined criteria was calculated. Results: OCD occurred in the capitellum in 24 patients (92%), in the trochlea in 2 patients (8%) and radial head in 1 patient (4%). Loose bodies were identified in 11 (42%) patients. Eighteen patients demonstrated MRI findings in keeping with unstable lesions. In all 11 patients who had surgery the surgical findings of instability correlated with the MRI findings. When combined, the MR criteria were 100% sensitive for instability of OCD lesions of the elbow. Conclusion: The vast majority of OCD of the elbow occurs in the capitellum. When used together, the MR criteria for instability were 100% sensitive for evaluation OCD lesions of the elbow.

Knowledge-based interpretation of cranial MR images

International Nuclear Information System (INIS)

Kuhn, M.H.; Menhardt, W.; Schmidt, K.H.

1987-01-01

A computerized system is described that can be used to evaluate an MR tomogram automatically to support clinical identification of anatomic and pathologic structures and to aid in planning MR measurements. Knowledge from three domains is used for the interpretation of an MR image: nosologic knowledge, knowledge of MR imaging parameters, and anatomic and morphologic knowledge. Nosologic information is used to generate hypotheses about possible pathologies and their locations, based on the signs and symptoms of the patient. With this information, a sequence of interpretation modules, each able to detect substructures in already detected structures with the aid of techniques from image processing, pattern recognition, and artificial intelligence, is generated and executed

Overhauser-enhanced MR imaging (OMRI)

International Nuclear Information System (INIS)

Golman, K.; Leunbach, I.; Ardenkjaer-Larsen, J.H.; Wistrand, L.G.; Petersson, J.S.; Ehnholm, G.J.; Jaervi, A.; Vahasalo, S.

1998-01-01

Purpose: To evaluate a new single-electron contrast agent for Overhauser-enhanced MR imaging. The contrast agents that are currently available give enhancement factors that are too low to make the technique a valid option for routine clinical use. Material and Methods: MR images were generated directly following the injection of the substance into rats. The MR scanner was operated at a main magnetic field of 0.01 T and equipped with a separate rf-transmitter tuned to the electron paramagnetic resonance frequency of the contrast agent. Results: As expected, the images generated show a high level of enhancement in areas where the contrast agent was present, and a maximum enhancement of 60 times the normal proton signal was obtained in the vascular area. The signal-to-noise ratios in the images were superior to those previously attained. Conclusion: The new contrast agent makes it possible to generate MR images with both morphological and functional information at 0.01 T. The signal-to-noise ratios found in the generated images were of the same order as, or better than, those obtained with the standard clinical routine. (orig.)

Evaluation of Nitrogen Uptake and Growth Performance of Advanced Mutant Lines MR219-4 and MR219-9 Grown Under Aerobic Conditions

International Nuclear Information System (INIS)

Shyful Azizi Abdul Rahman; Abdul Rahim Harun; Rusli Ibrahim; Khairuddin Abdul Rahim

2014-01-01

Developing a good crop production management package; drought resistance variety, effective water and nutrient management in rice production practices is crucial for global climate change adaptation. A research project under IAEA RAS5065 (Supporting Climate-Proofing Rice Production Systems (CRiPS) Based on Nuclear Applications) was conducted from 2012 to 2013, in collaboration with MARDI. Two advanced mutant lines, MR219-4 and MR219-9 were used in this research project to evaluate growth, yield potential and fertilizer uptake under different water input condition (flooded and aerobic). The advanced mutant line MR219-9 showed comparable growth, yield and nitrogen uptake under both flooded and aerobic conditions. The yield and yield components are not significantly different from the parent variety (MR219) but total N uptake was lower than MR219 regardless of water regime. The field trial showed that MR219-9 has a better total N content which is comparable to the aerobic rice variety (MRIA 1) and this indicates that this advance mutant line MR219-9 is a potential aerobic rice variety. (author)

Changes of renal blood flow after ESWL: assessment by ASL MR imaging, contrast enhanced MR imaging, and renal resistive index.

Science.gov (United States)

Abd Ellah, Mohamed; Kremser, Christian; Pallwein, Leo; Aigner, Friedrich; Schocke, Michael; Peschel, Reinhard; Pedross, Florian; Pinggera, Germar-Michael; Wolf, Christian; Alsharkawy, Mostafa A M; Jaschke, Werner; Frauscher, Ferdinand

2010-10-01

The annual incidence of stone formation is increased in the industrialised world. Extracorporeal shockwave lithotripsy is a non-invasive effective treatment of upper urinary tract stones. This study is aimed to evaluate changes of renal blood flow in patients undergoing extracorporeal shock wave lithotripsy (ESWL) by arterial spin labeling (ASL) MR imaging, contrast enhanced dynamic MR imaging, and renal resistive index (RI). Thirteen patients with nephrolithiasis were examined using MR imaging and Doppler ultrasound 12h before and 12h after ESWL. ASL sequence was done for both kidneys and followed by contrast enhanced MR imaging. In addition RI Doppler ultrasound measurements were performed. A significant increase in RI (pESWL causes changes in RI and ASL MR imaging, which seem to reflect changes in renal blood flow. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

MR imaging of appendicular musculoskeletal trauma

International Nuclear Information System (INIS)

Kathol, M.H.; Montgomery, W.J.; Yuh, W.T.C.; El-Khoury, G.Y.

1987-01-01

Thirty cases of musculoskeletal trauma to the extremities examined by MR imaging have been reviewed retrospectively. Examples of various injuries will be shown, including disruption of ligament and tendon, muscular tear and edema, hemorrhage (local or diffuse), vascular injury, bone marrow contusion, osteocartilaginous fracture, meniscal tear, and joint fluid. Many of these patients were collegiate athletes, and MR was valuable in establishing a rapid, accurate diagnosis influencing not only treatment but also return to competition. Negative examinations allowed resumption of competition with a high degree of confidence. The advantages and disadvantages of MR in musculo-skeletal trauma are discussed

MR findings in iliotibial band syndrome

International Nuclear Information System (INIS)

Nishimura, G.; Yamato, M.; Tamai, K.; Takahashi, J.; Uetani, M.

1997-01-01

Objective. To elucidate the MR findings in iliotibial band (ITB) syndrome. Design and patients. The subjects comprised four patients (five knees) with lateral knee pain: two athletes and two non-athletes. One non-athlete was engaged in work requiring repetitive knee movement, and the other suffered from Cushing syndrome and had bilateral abnormalities. All patients were suspected of having a lateral meniscal tear prior to MR examination, but physical examination following provisional MR diagnosis warranted the final diagnosis. MR studies included fast spin echo sagittal imaging, fat-saturated fast spin echo proton density coronal imaging, and T2* radial imaging. Twelve normal volunteers were examined. Results and conclusion. Fat-saturated coronal imaging demonstrated an ill-defined, high-intensity area deep to the ITB. T2* radial imaging showed an identical, but less conspicuous, abnormality. The MR finding suggested soft tissue inflammation and/or edema rather than focal fluid collection in the bursae. The signal alteration predominated in the region beneath the posterior fibers of the ITB, thus supporting the current opinion that the posterior fibers of the ITB are tighter against the lateral femoral epicondyle than the anterior fibers. The ITB itself did not show any signal alteration or increased thickness. (orig.). With 4 figs., 1 tab

MR imaging of transient synovitis: differentiation from septic arthritis

International Nuclear Information System (INIS)

Yang, W.J.; Im, S.A.; Lim, G.Y.; Chun, H.J.; Jung, N.Y.; Sung, M.S.; Choi, B.G.

2006-01-01

Transient synovitis is the most common cause of acute hip pain in children. However, MR imaging findings in transient synovitis and the role of MR imaging in differentiating transient synovitis from septic arthritis have not been fully reported. To describe the MR findings of transient synovitis and to determine whether the MR characteristics can differentiate this disease entity from septic arthritis. Clinical findings and MR images of 49 patients with transient synovitis (male/female 36/13, mean age 6.1 years) and 18 patients with septic arthritis (male/female 10/8, mean age 4.9 years) were retrospectively reviewed. MR findings of transient synovitis were symptomatic joint effusion, synovial enhancement, contralateral joint effusion, synovial thickening, and signal intensity (SI) alterations and enhancement in surrounding soft tissue. Among these, SI alterations and enhancement in bone marrow and soft tissue, contralateral joint effusion, and synovial thickening were statistically significant MR findings in differentiating transient synovitis from septic arthritis. The statistically significant MR findings in transient synovitis are contralateral (asymptomatic) joint effusions and the absence of SI abnormalities of the bone marrow. It is less common to have SI alterations and contrast enhancement of the soft tissues. The statistically significant MR findings in septic arthritis are SI alterations of the bone marrow, and SI alterations and contrast enhancement of the soft tissue. Ipsilateral effusion and synovial thickening and enhancement are present in both diseases

MR imaging of the pulmonary vasculature - an update

Energy Technology Data Exchange (ETDEWEB)

Pedersen, Mark R.; Fisher, Mark T. [University of Iowa, Department of Radiology, Carver College of Medicine, Iowa City, Iowa (United States); Beek, Edwin J.R. van [University of Iowa, Department of Radiology, Carver College of Medicine, Iowa City, Iowa (United States); University of Iowa Hospitals and Clinics, JPP 3895, Department of Radiology, Iowa City, Iowa (United States)

2006-06-15

Although the advent of multi-detector row computed tomography (CT) angiography has been at the heart of improving the diagnostic management of pulmonary vascular disease, MR technology has also moved forward. This review outlines the current state of affairs of MR techniques for the assessment of pulmonary vascular diseases such as pulmonary hypertension, pulmonary arteritis and arteriovenous malformations. It highlights the main areas of MR angiography and MR perfusion imaging and discusses novel methods, such as non-contrast enhanced direct thrombus imaging, and will discuss its merits in the context of other diagnostic modalities. (orig.)

Fast FLAIR MR images of intracranial hemorrhage

International Nuclear Information System (INIS)

Chun, Eun Ju; Choi, Hye Young; Cho, Young A; Kim, Wha Young

1998-01-01

The purpose of this study is to evaluate the signal characteristics of intracranial hemorrhage, as seen on fluid attenuated inversion recovery (FLAIR) MR imaging according to various stages, and to compare FLAIR imaging with spin-echo T1- and T2-weighted MR imaging. We retrospectively evaluated fast FLAIR images along with spin-echo T1- and T2 weighted MR images of 32 lesions in 25 patients (12 males and 14 females, aged 3 - 84 yrs) with intracranial hemorrhagic lesions. For imaging, 1.5 T unit was used, and the nature of the lesions was found to be as follows : intracranial hemorrhage (n=15); tumor (n=9); infarction (n=4); arteriovenous malformation (n=3); and arachnoid cyst with hemorrhage (n=1). On the basis of spin-echo MR imaging, lesions were classified as acute, early subacute, late subacute, early chronic, or late chronic stage. The signal characteristics of intracranial hemorrhage were analysed in accordance with each staging, as seen on MR FLAIR imaging, and compared to the staging seen on spin-echo T1- and T-2 weighted MR imaging. The signal intensity of intracranial hemorrhage, as seen on FLAIR imaging, was not characteristic; it was similar to that of T2WI during the acute and subacute stages, and similiar to that of T1WI during the chronic stage. When used together with spin-echo T1- and T2-weighted MR imaging, however, FLAIR imaging may be useful for the classification of chronic intracranial hemorrhage as either early or late stage. (author). 20 refs., 2 tabs., 6 figs

MR imaging of brachial plexus

International Nuclear Information System (INIS)

Carriero, A.; Ciccotosto, C.; Dragani, M.; Manes, L.; Bonomo, L.

1991-01-01

The brachial plexus is a difficult region to evaluate with radiological techniques. MR imaging has great potentials for the depiction of the various anatomical structures of the branchial plexus - i.e., spinal ganglion, ventral nerve rami root exit of the neural foramina, trunks an cordes. Moreover, MR imaging, thanks to its direct multiplanarity, to its excellent soft-tissue contrast, and to its lack of motion artifacts, allows good evaluation of pathologic conditions in the branchial plexus, especially traumas and cancers. On the contrary CT, in spite of its high spatial resolution and good contrast, cannot demonstrate the anatomical structures of the brachial plexus. US detects superficials structures, and conventional radiographs depict only indirect changes in the adjacent lung apex and skeletal structures. From November 1989 to May 1990, 20 normal volunteers (15 males and 5 females; average age: 35 years) were studied with MR imaging. Multisection technique was employed with a dedicated coil and a primary coil. The anatomical structures of the brachial plexus were clearly demonstrated by T1-weighted sequences on the sagittal and axial planes. T2-weighted pulse sequences on the coronal plane were useful for the anatomical definition of the brachial plexus and for eventual tissue characterization. The correct representation of the anatomical structures of the brachial plexus allowed by MR imaging with author's standard technique makes MR imaging the most appropriate exam for the diagnosis of pathologic conditions in the brachial plexus, although its use must be suggested by specific clinical questions

Usefulness of perfusion MR imaging in hyperacute ischemic stroke

International Nuclear Information System (INIS)

Park, Ji Hoon; Kim, Jae Hyoung; Shin, Tae Min; Lee, Eun Ja; Chung, Sung Hoon; Choi, Nack Cheon; Lim, Byeong Hoon; Kim, In One

1998-01-01

Perfusion MR imaging is a new technique for the assessment of acute ischemic stroke. The aim of this study was to evaluate the usefulness of this imaging in hyperacute ischemic stroke in comparison with conventional CT and MR imaging. Eight patients presenting the symptoms of acute ischemic stroke due to middle cerebral artery occlusion were included in this study. Within 2 hours of initial CT scan and 6 hours after the onset of stroke, perfusion MR imaging was performed in all patients using a single-section dynamic contrast-enhanced T2*-weighted imager in conjunction with conventional routine MR imaging and MR angiography. Cerebral blood volume (CBV) maps were then obtained from dynamic MR imaging data by using numerical integration techniques. The findings of CBV maps were compared with those of initial and follow-up CT or MR images. The findings of CBV maps were obviously abnormal in all patients, as compared with normal or focal subtle abnormal findings seen on initial CT and MR images. CBV in the occluded arterial territory was lower in all eight patients;two had focal regions of increased CBV within the affected territory, indicating reperfusion hyperemia. In all patients, regions of abnormal CBV were eventually converted to infarctions on follow-up images. Perfusion MR imaging was useful for the evaluation of hemodynamic change occurring during cerebral perfusion in hyperacute ischemic stroke, and prediction of the final extent of infarction. These results suggest that pertusion MR imaging can play an important role in the diagnosis and management of hyperacute ischemic stroke.=20

High-resolution axial MR imaging of tibial stress injuries

Directory of Open Access Journals (Sweden)

Mammoto Takeo

2012-05-01

Full Text Available Abstract Purpose To evaluate the relative involvement of tibial stress injuries using high-resolution axial MR imaging and the correlation with MR and radiographic images. Methods A total of 33 patients with exercise-induced tibial pain were evaluated. All patients underwent radiograph and high-resolution axial MR imaging. Radiographs were taken at initial presentation and 4 weeks later. High-resolution MR axial images were obtained using a microscopy surface coil with 60 × 60 mm field of view on a 1.5T MR unit. All images were evaluated for abnormal signals of the periosteum, cortex and bone marrow. Results Nineteen patients showed no periosteal reaction at initial and follow-up radiographs. MR imaging showed abnormal signals in the periosteal tissue and partially abnormal signals in the bone marrow. In 7 patients, periosteal reaction was not seen at initial radiograph, but was detected at follow-up radiograph. MR imaging showed abnormal signals in the periosteal tissue and entire bone marrow. Abnormal signals in the cortex were found in 6 patients. The remaining 7 showed periosteal reactions at initial radiograph. MR imaging showed abnormal signals in the periosteal tissue in 6 patients. Abnormal signals were seen in the partial and entire bone marrow in 4 and 3 patients, respectively. Conclusions Bone marrow abnormalities in high-resolution axial MR imaging were related to periosteal reactions at follow-up radiograph. Bone marrow abnormalities might predict later periosteal reactions, suggesting shin splints or stress fractures. High-resolution axial MR imaging is useful in early discrimination of tibial stress injuries.

High-resolution axial MR imaging of tibial stress injuries

Science.gov (United States)

2012-01-01

Purpose To evaluate the relative involvement of tibial stress injuries using high-resolution axial MR imaging and the correlation with MR and radiographic images. Methods A total of 33 patients with exercise-induced tibial pain were evaluated. All patients underwent radiograph and high-resolution axial MR imaging. Radiographs were taken at initial presentation and 4 weeks later. High-resolution MR axial images were obtained using a microscopy surface coil with 60 × 60 mm field of view on a 1.5T MR unit. All images were evaluated for abnormal signals of the periosteum, cortex and bone marrow. Results Nineteen patients showed no periosteal reaction at initial and follow-up radiographs. MR imaging showed abnormal signals in the periosteal tissue and partially abnormal signals in the bone marrow. In 7 patients, periosteal reaction was not seen at initial radiograph, but was detected at follow-up radiograph. MR imaging showed abnormal signals in the periosteal tissue and entire bone marrow. Abnormal signals in the cortex were found in 6 patients. The remaining 7 showed periosteal reactions at initial radiograph. MR imaging showed abnormal signals in the periosteal tissue in 6 patients. Abnormal signals were seen in the partial and entire bone marrow in 4 and 3 patients, respectively. Conclusions Bone marrow abnormalities in high-resolution axial MR imaging were related to periosteal reactions at follow-up radiograph. Bone marrow abnormalities might predict later periosteal reactions, suggesting shin splints or stress fractures. High-resolution axial MR imaging is useful in early discrimination of tibial stress injuries. PMID:22574840

The MR evaluation of pachygyria and associated syndromes

International Nuclear Information System (INIS)

Byrd, S.E.; Radkowski, M.A.; Northwestern Univ., Chicago, IL; Osborn, R.E.

1991-01-01

A retrospective study of 40 children with some form of pachygyria was performed at the Children's Memorial Hospital in Chicago. All children had MR brain scans. The MR findings were analyzed, and correlated with the clinical symptoms and course in all the children. 15 percent had autopsy findings. Based on the clinical, MR and autopsy findings, in conjunction with the medical literature, the following was found: (1) Pachygyria can occur as an isolated entity without an association with lissencephaly. The MR findings in these children consisted of a brain that demonstrated normal opercularization with either focal or diffuse areas of pachygyria without areas of agyria. These children live longer and have less severity of symptoms than the children with lissencephaly. (2) The MR findings in children with lissencephaly consisted of a brain that demonstrated abnormal oper-cularization with areas of total agyria or areas with agyria with pachygyria. (3) The MR findings in 25 percent of the children with poly-microgyria simulated pachygyria. The MR findings of the brain in these children consisted of a 'nubby' appearance to the outer surface of these abnormal gyri which resembled pachygyria but on histologic exam was polymicrogyria. (author). 11 refs.; 7 figs.; 1 tab

Combined PET/MR imaging in neurology

DEFF Research Database (Denmark)

Andersen, Flemming Littrup; Ladefoged, Claes Nøhr; Beyer, Thomas

2014-01-01

AIM: Combined PET/MR systems have now become available for clinical use. Given the lack of integrated standard transmission (TX) sources in these systems, attenuation and scatter correction (AC) must be performed using the available MR-images. Since bone tissue cannot easily be accounted for duri...

Clinical PET/MR Imaging in Oncology

DEFF Research Database (Denmark)

Kjær, Andreas; Torigian, Drew A.

2016-01-01

. The question, therefore, arises regarding what the future clinical applications of PET/MR imaging will be. In this article, the authors discuss ways in which PET/MR imaging may be used in future applications that justify the added cost, predominantly focusing on oncologic applications. The authors suggest...

PET/MR imaging of the pelvis in the presence of endoprostheses

DEFF Research Database (Denmark)

Ladefoged, Claes Nøhr; Andersen, Flemming Littrup; Keller, Sune Høgild

2013-01-01

In combined whole-body PET/MR, attenuation correction (AC) is performed indirectly using the available MR image information and subsequent segmentation. Implant-induced susceptibility artifacts and subsequent signal voids may challenge MR-based AC (MR-AC). We evaluated the accuracy of MR-AC in PE...

Cellular MR Imaging

Directory of Open Access Journals (Sweden)

Michel Modo

2005-07-01

Full Text Available Cellular MR imaging is a young field that aims to visualize targeted cells in living organisms. In order to provide a different signal intensity of the targeted cell, they are either labeled with MR contrast agents in vivo or prelabeled in vitro. Either (ultrasmall superparamagnetic iron oxide [(USPIO] particles or (polymeric paramagnetic chelates can be used for this purpose. For in vivo cellular labeling, Gd3+- and Mn2+- chelates have mainly been used for targeted hepatobiliary imaging, and (USPIO-based cellular imaging has been focused on imaging of macrophage activity. Several of these magneto-pharmaceuticals have been FDA-approved or are in late-phase clinical trials. As for prelabeling of cells in vitro, a challenge has been to induce a sufficient uptake of contrast agents into nonphagocytic cells, without affecting normal cellular function. It appears that this issue has now largely been resolved, leading to an active research on monitoring the cellular biodistribution in vivo following transplantation or transfusion of these cells, including cell migration and trafficking. New applications of cellular MR imaging will be directed, for instance, towards our understanding of hematopoietic (immune cell trafficking and of novel guided (stem cell-based therapies aimed to be translated to the clinic in the future.

Evaluation of fetal anomalies with MR imaging

International Nuclear Information System (INIS)

Benson, R.C.; Platt, L.D.; Colletti, P.M.; Raval, J.K.; Boswell, W.D. Jr.; Halls, J.M.

1987-01-01

Twenty pregnant women underwent MR imaging (0.5 T) after US disclosed a significant fetal anomaly. The ability of MR imaging to depict the abnormalities was assessed. Of 20 abnormalities, 17 were visualized with MR imaging. Abnormalities included conjoined twins, omphalocele, gastroschisis, hydrocephalus, hydronephrosis, fetal ascites, facial teratoma, anencephaly, bladder outlet obstruction, thanatophoric dwarfism, cystic, hygroma, and fetal ovarian cyst. Thirteen of 14 abnormalities in third-trimester fetuses were visualized, as were four of six abnormalities in second-trimester fetuses. Associated polyhydramnios or oligohydramnios was evident in six of six cases. Anomalies were best delineated with T1-weighted sequences. The study suggests that MR imaging is potentially useful as a complementary imaging modality in the evaluation of fetal anomalies

A typical MR imaging of multiple sclerosis

International Nuclear Information System (INIS)

Katagiri, Shinako; Kan, Shinichi; Ikeda, Toshiaki; Nishiyama, Syougo; Nishimaki, Hiroshi; Matsubayashi, Takashi; Hata, Takashi

1995-01-01

MR imaging is very useful in detecting the intracranial lesion of multiple sclerosis (MS). We present six patients of MS with atypical MR imaging findings. Six patients aged 27-56 years (mean 36 years), and sexuality of six patients were 2 men and 4 females. Three patient's clinical course had episodes of optic neuritis. The plaque's size of the predominant lesion of the patients ranged from 3.0 to 9.0 cm in diameter. The plaques were oval, elliptically and other shaped. At acute stage, MR imaging detected perfocal edema and focal mass effect in three cases of our study. Two out of six cases showed multiple irregularly enhancing lesion with Gadolinium-DTPA. Plaques of all cases did not disappear completely in final MR imaging study. (author)

MR findings of cerebral palsy and clinical correlation

Energy Technology Data Exchange (ETDEWEB)

Kim, Sun Ho; Kim, In One; Kim, Woo Sun; Yeon, Kyung Mo [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

1997-04-01

To demonstrate MR findings of cerebral palsy (CP), correlation with clinical findings, and differences between the full-term and pre-term group. Brain MRI of 94 patients with cerebral palsy (CP) were reviewed. The frequency of each MR finding, statistical correlation with clinical findings including type, severity and extent of CP, and differences between the full-term and pre-term group were analyzed. Abnormal MR findings were found in 83 patients(88%), and were as follows : diffuse brain atrophy(30%); periventricular leukomalacia(PVL)(28%); infarction(11%), basal ganglia abnormality(11%); delayed myelination(10%); nonspecific tissue loss or encephalomalacia(9%); and cortical dysplasia(7%). Hemiplegia was the most common condition among patients with infarction, and was found in 80% of this group; diplegia was found in 50% of cases with diffuse brain atrophy, while paraplegia was found in 36% of those with normal MR findings (p < .05). Mild symptoms were dominant in patients with normal MR findings(82%) and in those with infarctions(90%)(p < .05). PVL was the dominant finding in the pre-term group (65%) whereas findings in the full-term group varied; in this group, 38% of MR findings suggested prenatal insults. Possible causative factors were found in 66% of the full-term and 80% of the pre-term group. Perinatal factors were dominant in the pre-term group(81%), whereas prenatal and postnatal factors showed relatively higher frequencies in the full-term group(30% and 24%, respectively). Diffuse brain atrophy and PVL were the most common MR findings. The extent of CP the pre-term correlated well with MR findings. PVL and perinatal factors were dominant in the pre-term group, whereas variable MR findings and relatively higher frequencies of pre- and postnatal factors were found in the full-term group.

MR findings of cerebral palsy and clinical correlation

International Nuclear Information System (INIS)

Kim, Sun Ho; Kim, In One; Kim, Woo Sun; Yeon, Kyung Mo

1997-01-01

To demonstrate MR findings of cerebral palsy (CP), correlation with clinical findings, and differences between the full-term and pre-term group. Brain MRI of 94 patients with cerebral palsy (CP) were reviewed. The frequency of each MR finding, statistical correlation with clinical findings including type, severity and extent of CP, and differences between the full-term and pre-term group were analyzed. Abnormal MR findings were found in 83 patients(88%), and were as follows : diffuse brain atrophy(30%); periventricular leukomalacia(PVL)(28%); infarction(11%), basal ganglia abnormality(11%); delayed myelination(10%); nonspecific tissue loss or encephalomalacia(9%); and cortical dysplasia(7%). Hemiplegia was the most common condition among patients with infarction, and was found in 80% of this group; diplegia was found in 50% of cases with diffuse brain atrophy, while paraplegia was found in 36% of those with normal MR findings (p < .05). Mild symptoms were dominant in patients with normal MR findings(82%) and in those with infarctions(90%)(p < .05). PVL was the dominant finding in the pre-term group (65%) whereas findings in the full-term group varied; in this group, 38% of MR findings suggested prenatal insults. Possible causative factors were found in 66% of the full-term and 80% of the pre-term group. Perinatal factors were dominant in the pre-term group(81%), whereas prenatal and postnatal factors showed relatively higher frequencies in the full-term group(30% and 24%, respectively). Diffuse brain atrophy and PVL were the most common MR findings. The extent of CP the pre-term correlated well with MR findings. PVL and perinatal factors were dominant in the pre-term group, whereas variable MR findings and relatively higher frequencies of pre- and postnatal factors were found in the full-term group

Adaptation of antenna profiles for control of MR guided hyperthermia (HT) in a hybrid MR-HT system

International Nuclear Information System (INIS)

Weihrauch, Mirko; Wust, Peter; Weiser, Martin; Nadobny, Jacek; Eisenhardt, Steffen; Budach, Volker; Gellermann, Johanna

2007-01-01

A combined numerical-experimental iterative procedure, based on the Gauss-Newton algorithm, has been developed for control of magnetic resonance (MR)-guided hyperthermia (HT) applications in a hybrid MR-HT system BSD 2000 3D-MRI. In this MR-HT system, composed of a 3-D HT applicator Sigma-Eye placed inside a tunnel-type MR tomograph Siemens MAGNETOM Symphony (1.5 T), the temperature rise due to the HT radiation can be measured on-line in three dimensions by use of the proton resonance frequency shift (PRFS) method. The basic idea of our iterative procedure is the improvement of the system's characterization by a step-by-step modification of the theoretical HT antenna profiles (electric fields radiated by single antennas). The adaptation of antenna profiles is efficient if the initial estimates are radiation fields calculated from a good a priori electromagnetic model. Throughout the iterative procedure, the calculated antenna fields (FDTD) are step-by-step modified by comparing the calculated and experimental data, the latter obtained using the PRFS method. The procedure has been experimentally tested on homogeneous and inhomogeneous phantoms. It is shown that only few comparison steps are necessary for obtaining a dramatic improvement of the general predictability and quality of the specific absorption rate (SAR) inside the MR-HT hybrid system

MR arthrography of the knee

International Nuclear Information System (INIS)

Kramer, J.; Engel, A. Jr.; Stiglbauer, R. Jr.; Prayer, L. Jr.; Hajek, P. Jr.; Imhof, H.

1991-01-01

This paper demonstrates the diagnostic value of MR arthrography in the assessment of cartilaginous lesions, including osteochondritis dissecans. One hundred thirty-two knees of 125 patients were examined with MR arthrography performed on a 1.5-T magnet with a knee resonator. T1-weighted spin-echo and T2*-weighted three-dimensional gradient-echo sequences were obtained after intraarticular administration of 40 mL of 2-mmol GD-DTPA solution. Seventy-five patients were also imaged without contrast agent. The description of the articular surface was classified into four types: I, normal cartilage surface and thickness; II, surface normal or slightly irregular; III, severe surface irregularities and cartilage defects; and IV, extensive cartilage defects, scar formation. MR findings were correlated with those of arthroscopy/arthrotomy (n = 75)

MR findings of spondylolysis

International Nuclear Information System (INIS)

Ojiri, Hiroya; Fukuda, Kunihiko; Hashimoto, Toru; Doi, Michiko; Irie, Takeo; Tatsuno, Satoshi; Tada, Shinpei; Toyoda, Keiko.

1994-01-01

We reviewed MR images of 50 patients with spondylolisthesis to disclose MR findings of spondylolysis. In almost half of our series, spondylolysis was detected as a low signal intensity band traversing in the pairs interarticularis on both T1 and T2 weighted images. Sagittal images was superior to axial image in detection of the low signal intensity band. In some patients, a focal high signal intensity accompanying the low signal intensity band was considered to be fluid collection within pseudoarthrosis due to spondylolysis on T2-weighted image. (author)

MR findings of spondylolysis

Energy Technology Data Exchange (ETDEWEB)

Ojiri, Hiroya; Fukuda, Kunihiko; Hashimoto, Toru; Doi, Michiko; Irie, Takeo; Tatsuno, Satoshi; Tada, Shinpei (Jikei Univ., Tokyo (Japan). School of Medicine); Toyoda, Keiko

1994-08-01

We reviewed MR images of 50 patients with spondylolisthesis to disclose MR findings of spondylolysis. In almost half of our series, spondylolysis was detected as a low signal intensity band traversing in the pairs interarticularis on both T1 and T2 weighted images. Sagittal images was superior to axial image in detection of the low signal intensity band. In some patients, a focal high signal intensity accompanying the low signal intensity band was considered to be fluid collection within pseudoarthrosis due to spondylolysis on T2-weighted image. (author).

A wavelet multiscale denoising algorithm for magnetic resonance (MR) images

International Nuclear Information System (INIS)

Yang, Xiaofeng; Fei, Baowei

2011-01-01

Based on the Radon transform, a wavelet multiscale denoising method is proposed for MR images. The approach explicitly accounts for the Rician nature of MR data. Based on noise statistics we apply the Radon transform to the original MR images and use the Gaussian noise model to process the MR sinogram image. A translation invariant wavelet transform is employed to decompose the MR 'sinogram' into multiscales in order to effectively denoise the images. Based on the nature of Rician noise we estimate noise variance in different scales. For the final denoised sinogram we apply the inverse Radon transform in order to reconstruct the original MR images. Phantom, simulation brain MR images, and human brain MR images were used to validate our method. The experiment results show the superiority of the proposed scheme over the traditional methods. Our method can reduce Rician noise while preserving the key image details and features. The wavelet denoising method can have wide applications in MRI as well as other imaging modalities

MR imaging of the brain in neurofibromatosis

International Nuclear Information System (INIS)

Kuhn, J.P.; Cohen, M.L.; Duffner, P.K.; Seidel, F.; Harwood-Nash, D.

1986-01-01

Fifteen children and young adults with neurofibromatosis underwent CT and MR imaging (0.5-T superconducting magnet). Seven had optic gliomas and five had other intracranial neoplasms. Before thin-section MR imaging became available, CT was superior for demonstrating the optic nerves, although MR imaging better delineated tumor spread to the optic chiasm and tract. MR imaging was superior for demonstrating other gliomatous lesions associated with neurofibromatosis. Most lesions had long T1 and T2 values and were best seen on T2-weighted images. MR imaging revealed small areas of increased signal intensity on T2-weighted images in nearly half the patients. These lesions were not apparent on CT and were usually located in the globus pallidus, but were seen in many areas of the brain, commonly in the white matter, and in the brain steam and the cerebellar peduncles. Their exact etiology is unknown. Their imaging characteristics are somewhat different from those of gray matter. They may represent hamartomas or areas of glial scarring. Differentiation from a small glioma is presently not possible on a single examination

Excretory MR urography using breathhold three-dimensional FISP: comparison with MR urography using HASTE technique

Energy Technology Data Exchange (ETDEWEB)

Song, Won Kue; Lee, Jeong Min; Jin, Kong Young; Hwang, Ho keung; Han, Young Min [Chonbuk Narional University Hospital, Chonju (Korea, Republic of); Ym, Seong Hee [Namwon Medical Center, Chonju (Korea, Republic of)

2000-09-01

To compare the usefulness of gadolinium-enhanced excretory MR urography using breath-hold three-dimensional fast imaging with steady state precession (3-D FISP) with conventional MR urography using the half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence in the evaluation of obstructive uropathy. Twenty-three patients in whom ultrasonography (US) and/or intravenous urography (IVU) revealed signs of urinary obstruction were enrolled in this study. Fifteen were men and eight were women, and their mean age was 54 (range, 21-80) years. All MR images were obtained using a 1.5T MR unit. MR urography using the HASTE technique (MRU) and gadolinium-enhanced excretory MR urography using the 3D-FISP technique were performed, and in all cases, reconstructions involved maximum intensity projection. For contrast-enhanced MR urography(CEMRU), images were obtained 3, 5, 20, and 30 minutes after the administration of intravenous contrast media, and for selected cases, additional images were obtained until 24 hours after contrast media injection. For qualitative analysis, two experienced radiologists compared CEMRU and MRU in terms of their diagnostic value as regards the level and cause of urinary obstruction, and morphologic accuracy. In addition, signal to noise ration(SNR) and contrast to noise ration (CNR) of the urinary tract at each anatomic level were quantitatively analysed. Quantitative analysis showed that in terms of SNR and CNR of the urinary tract at the level of the mid and distal ureter, CEMRU using 3-D FISP was better than MRU using HASTE (p less than 0.05). Qualitative analysis indicated that for the depiction of the whole length of normal ureter, and detection of the level of obstruction, anatomic anomalies and intrinsic tumors, 3-D FISP was superior to HASTE. There was, however, no difference between these two modalities in the diagnosis of ureteral stone and the degree of hydronephrosis. In addition, 3-D FISP was better than HASTE for the

Excretory MR urography using breathhold three-dimensional FISP: comparison with MR urography using HASTE technique

International Nuclear Information System (INIS)

Song, Won Kue; Lee, Jeong Min; Jin, Kong Young; Hwang, Ho keung; Han, Young Min; Ym, Seong Hee

2000-01-01

To compare the usefulness of gadolinium-enhanced excretory MR urography using breath-hold three-dimensional fast imaging with steady state precession (3-D FISP) with conventional MR urography using the half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence in the evaluation of obstructive uropathy. Twenty-three patients in whom ultrasonography (US) and/or intravenous urography (IVU) revealed signs of urinary obstruction were enrolled in this study. Fifteen were men and eight were women, and their mean age was 54 (range, 21-80) years. All MR images were obtained using a 1.5T MR unit. MR urography using the HASTE technique (MRU) and gadolinium-enhanced excretory MR urography using the 3D-FISP technique were performed, and in all cases, reconstructions involved maximum intensity projection. For contrast-enhanced MR urography(CEMRU), images were obtained 3, 5, 20, and 30 minutes after the administration of intravenous contrast media, and for selected cases, additional images were obtained until 24 hours after contrast media injection. For qualitative analysis, two experienced radiologists compared CEMRU and MRU in terms of their diagnostic value as regards the level and cause of urinary obstruction, and morphologic accuracy. In addition, signal to noise ration(SNR) and contrast to noise ration (CNR) of the urinary tract at each anatomic level were quantitatively analysed. Quantitative analysis showed that in terms of SNR and CNR of the urinary tract at the level of the mid and distal ureter, CEMRU using 3-D FISP was better than MRU using HASTE (p less than 0.05). Qualitative analysis indicated that for the depiction of the whole length of normal ureter, and detection of the level of obstruction, anatomic anomalies and intrinsic tumors, 3-D FISP was superior to HASTE. There was, however, no difference between these two modalities in the diagnosis of ureteral stone and the degree of hydronephrosis. In addition, 3-D FISP was better than HASTE for the

Fundamentals of quantitative dynamic contrast-enhanced MR imaging.

Science.gov (United States)

Paldino, Michael J; Barboriak, Daniel P

2009-05-01

Quantitative analysis of dynamic contrast-enhanced MR imaging (DCE-MR imaging) has the power to provide information regarding physiologic characteristics of the microvasculature and is, therefore, of great potential value to the practice of oncology. In particular, these techniques could have a significant impact on the development of novel anticancer therapies as a promising biomarker of drug activity. Standardization of DCE-MR imaging acquisition and analysis to provide more reproducible measures of tumor vessel physiology is of crucial importance to realize this potential. The purpose of this article is to review the pathophysiologic basis and technical aspects of DCE-MR imaging techniques.

Characteristic MR spectroscopy in fucosidosis: in vitro investigation

Energy Technology Data Exchange (ETDEWEB)

Mamourian, Alex C.; Chawla, Sanjeev; Poptani, Harish [Hospital of the University of Pennsylvania, Department of Radiology, Philadelphia, PA (United States); Hopkin, Jeremy R. [Barrow Neurological Institute, Department of Neuroradiology, Phoenix, AZ (United States)

2010-08-15

Fucosidosis is a rare lysosomal storage disorder that results in the deposition of the sugar fucose within various organs, including the central nervous system. Neuroimaging abnormalities on MR, specifically T2 shortening in the basal ganglia, have been reported as suggestive of fucosidosis. A more recent report of MR spectroscopy (MRS) of one patient provided evidence that MRS is specific for fucosidosis. We present another confirmed case with nearly identical MR spectroscopic findings along with in vitro data that support the contention that MR spectroscopy, in the setting of typical clinical and imaging features, is characteristic for this rare disorder. (orig.)

Characteristic MR spectroscopy in fucosidosis: in vitro investigation

International Nuclear Information System (INIS)

Mamourian, Alex C.; Chawla, Sanjeev; Poptani, Harish; Hopkin, Jeremy R.

2010-01-01

Fucosidosis is a rare lysosomal storage disorder that results in the deposition of the sugar fucose within various organs, including the central nervous system. Neuroimaging abnormalities on MR, specifically T2 shortening in the basal ganglia, have been reported as suggestive of fucosidosis. A more recent report of MR spectroscopy (MRS) of one patient provided evidence that MRS is specific for fucosidosis. We present another confirmed case with nearly identical MR spectroscopic findings along with in vitro data that support the contention that MR spectroscopy, in the setting of typical clinical and imaging features, is characteristic for this rare disorder. (orig.)

MR imaging of neonatal cerebral infarction

International Nuclear Information System (INIS)

McArdle, C.B.; Mehta, S.D.; Kulkarni, M.V.; Keeney, S.A.; Hayden, C.K.; Adcock, E.W. III.

1987-01-01

Twenty-six neonatal infarcts were imaged with 0.6 T and 1.5-T magnets and correlated with US and/or CT. Periventricular leukomalacia (PVL) was seen in six cases: lobar infarction, ten cases; global infarction, six cases; and basal ganglia infarction, four cases. MR imaging was superior to US and CT in detecting hemorrhagic PVL and basal ganglia infarcts. MR demonstrates lobar infarcts better than US and CT because of a wider field of view, specificty, and improved gray and white matter differentiation. US underestimates the extent of brain destruction in global infarcts. These results indicate that MR is the single best imaging modality for detecting ischemic brain injury

Feasibility of simultaneous PET/MR of the carotid artery

DEFF Research Database (Denmark)

Ripa, Rasmus S; Knudsen, Andreas; Hag, Anne Mette F

2013-01-01

The study aimed at comparing PET/MR to PET/CT for imaging the carotid arteries in patients with known increased risk of atherosclerosis. Six HIV-positive men underwent sequential PET/MR and PET/CT of the carotid arteries after injection of 400 MBq of (18)F-FDG. PET/MR was performed a median of 131......) indicating that the luminal (18)F-FDG content had minimal influence on the values. The study shows for the first time that simultaneous PET/MR of the carotid arteries is feasible in patients with increased risk of atherosclerosis. Quantification of (18)F-FDG uptake correlated well between PET/MR and PET...

Proton MR spectroscopy in solitary pulmonary nodules: a preliminary study

International Nuclear Information System (INIS)

Yang Chunshan; Xiao Xiangsheng; Li Huimin; Liu Shiyuan; Li Chengzhou; Li Shenjiang

2005-01-01

Objective: To study the characteristics and the regularities of the metabolites in solitary pulmonary nodules with proton MR spectroscopy, and to investigate the clinical value of MR spectroscopy in differentiating benign from malignant pulmonary nodules. Methods: Sixty-nine patients with solitary pulmonary nodules underwent routine MRI and single-voxel MR spectroscopy using Siemens Vision 1.5 T MR system. MR spectroscopy characteristics and parameters of the metabolites were observed and recorded. Ten pathologic specimens were examined with single-voxel MR spectroscopy. The MR spectroscopy results of the pathologic specimens were compared with those of the solitary pulmonary nodules in vivo. Results: The Cho peak (2.86 ± 1.89) of the malignant nodules was higher than that of the inflammatory (0.87 ± 0.74), tuberculous nodules (0.97 ± 1.09), and hamartoma (0.42 ± 0.53) (P 0.05). Conclusion: MR spectroscopy is reliable in evaluating pulmonary nodules in vivo. The Cho peak, Cho/Cr, and Lac peak of the malignant nodules were higher than those of inflammatory, tuberculous nodules, and hamartoma. MR spectroscopy is helpful in differentiating benign from malignant pulmonary nodules. (authors)

Sacrococcygeal chordoma: MR imaging in 30 patients

Energy Technology Data Exchange (ETDEWEB)

Sung, Mi Sook; Chung, Myung Hee [Catholic University of Korea, Holy Family Hospital, Department of Radiology, Pucheon (Korea); Lee, Gyung Kyu; Kang, Heung Sik [Seoul National University Hospital, Department of Radiology, Seoul (Korea); Kwon, Soon Tae [Chungnam University Hospital, Department of Radiology, Taejun (Korea); Park, Jin Gyoon [Chunnam University Hospital, Department of Radiology, Kwangju (Korea); Suh, Jin Suk [Yonsei University, Severans Hospital, Department of Radiology, Seoul (Korea); Cho, Gil Ho [Yeungnam University Hospital, Department of Radiology, Taegu (Korea); Lee, Sung Moon [Kaemyung University Hospital, Department of Radiology, Taeku (Korea); Resnick, Donald [VA Medical Center, Department of Radiology, San Diego, CA (United States)

2005-02-01

To evaluate MR imaging of sacrococcygeal chordoma. Thirty patients (age range 22-80 years) underwent MR imaging for the diagnosis and preoperative evaluation of sacrococcygeal chordomas. Eight patients had follow-up MR examination after treatment. The MR images were performed with T1- and T2-weighted imaging, and gadolinium (Gd)-enhanced imaging. The MR images were analyzed for the signal intensity, enhancing pattern, tumor size, growth pattern of the soft tissue component, and tumor extension. T1-weighted images showed low signal masses with foci of high signal intensity in 73% of cases. Tumors enhanced in a variety of patterns after the administration of Gd. Soft tissue masses extending anteriorly were seen in all cases with posterior extension in 77% of cases. The posterior masses involved the surrounding muscles and extended toward the greater sciatic notch, appearing with pseudopodia (87%). Sacroiliac joints were involved in 23% of cases. Four lesions showed intraspinal extension and involvement of the posterior spinal muscles above the level of bony involvement. In 6 patients recurrent tumors were found at or around the surgical margin of the tumor 6 months to 5 years after resection of the sacral tumor. In two of the patients, nodular metastases to the pelvic bones and femur were found 1-4 years after initial examination. In conclusion, MR imaging is useful in the diagnosis and preoperative assessment of sacrococcygeal chordoma. Characteristic findings included sacral mass with heterogeneously high signal intensity with crisscrossing septa on long-repetition-time imaging, well-encapsulated pseudopodia-like or lobulated appearance, and gluteal muscle infiltration. Follow-up MR imaging is helpful to assess for recurrent or metastatic lesions of chordomas. (orig.)

PET/MR imaging of head/neck in the presence of dental implants

DEFF Research Database (Denmark)

Ladefoged, Claes; Beyer, Thomas; Keller, Sune

2013-01-01

Aim: In combined PET/MR, attenuation correction (AC) is performed indirectly based on the available MR image information. Implant-induced susceptibility artifacts and subsequent signal voids challenge MR-based AC (MR-AC). We evaluate the accuracy of MR-AC in PET/MR in patients with metallic denta...

Interventional MR imaging: state of the art and future perspectives

International Nuclear Information System (INIS)

Kahn, T.; Moedder, U.

1998-01-01

The concept of MR guidance of invasive diagnostic and minimally invasive therapeutic procedures is based on the excellent morphologic and functional properties of MR imaging. Prerequisites are adequate patient monitoring and adherence to safety guidelines. Fast and ultrafast sequences, temperature quantification, visualization of intravascular devices, thermal stability of contrast media and thermosensitive contrast media are discussed. The spectrum of clinical applications includes biopsies, thermal ablation modalities, vascular applications, MR endoscopy and intraoperative MR imaging. The development of interventional MR imaging is still in its infancy. In the future, MR imaging may play an important role in interventional radiology and minimally invasive therapy. (orig.) [de

MR imaging of cerebral abnormalities in utero.

Science.gov (United States)

Thickman, D; Mintz, M; Mennuti, M; Kressel, H Y

1984-12-01

In view of the lack of ionizing radiation, ability to image in a variety of planes, and high contrast resolution, magnetic resonance (MR) imaging may have a role in obstetrical management. Three fetuses with severe cerebral abnormalities were studied by MR in utero. The findings were correlated with ultrasound examinations and with autopsy results. Ventricular dilatation and progression of hydrocephalus were detected by MR. Although fetal motion may affect image quality, diagnostically useful images were obtained with imaging times of 2.5 min.

Multi-purpose simulator 'MR TRIOS' for reprocessing plant

International Nuclear Information System (INIS)

Mitsui, Takeshi; Ariyoshi, Masahiro

1993-01-01

MHI(Mitsubishi Heavy Industries, Ltd.) has developed MR TRIOS(Mitsubishi Reprocessing plant TRansient simulator of Integrated process for Operation Support), the realtime dynamic simulator, for multipurpose use to support the Reprocessing Plant operation in various aspects. MR TRIOS integrates the simulation models of the unit process in reprocessing plant, including shearing, dissolution, NO x absorption, accountability and adjustment and co-decontamination process, where each simulation model has two kinds of models, one is Process and the other is Control System. MR TRIOS can simulate the process behavior of the above listed unit process in an integrated manner as well as independently. It is realized by MR CONTROL, the simulator control program developed by MHI. We can get from MR TRIOS the real-time process values, such as temperature, pressure, density, flow rate and concentration of eminent nuclides etc. enabling the evaluation of the process dynamic characteristics under various operating conditions. MR TRIOS has been proved to be an effective tool for the comprehensive study of the process and system dynamics, for operation technique improvements and for training. In this report we will show the introductory outline of multi-purpose simulator 'MR TRIOS' for reprocessing plant and also show the possibility to clarify the fundamental technical requirement to realize the effective material accountancy measure for Head-end Area. (author)

Radiologic findings of sacroiliitis : emphasis on MR findings

International Nuclear Information System (INIS)

Yang, Ik; Park, Hai Jung; Lee, Yul; Chung, Soo Young; Park, Jong Ho

1997-01-01

To compare the characteristic MR findings of infectious sacroiliitis (IS) and ankylosing spondylitis (AS). We retrospectively reviewed MR findings in eight patients with IS (pyogenic in six, tuberculosis in two) confirmed by culture and clinical follow-up, and in six with AS by HLA-B27 typing. AA control group of 13 asymptomatic volunteers was formed, and they underwent MRI Findings were analysed for morphology, degree of bone erosion, and adjacent soft tissue change. CT findings of AS in four patients and IS in four were also compared to MR findings. MR characteristics of IS included unilaterality (100%), abnormal cartilage signal intensity (100%), bone marrow change (100%), contrast enhancement (100%), erosion (63%), and soft tissue change (63%). MR findings of AS showed bilaterality (67%), abnormal cartilage signal intensity (80%), bone marrow change (80%), erosion (80%), contrast enhancement (44%) and soft tissue change (10%). CT scan showed bony sclerosis and erosion (86%), and abnormal joint space (71%). MR findings of sacroiliitis were loss of thin zone of a cartilage and erosions on T1-weighted image, and increased signal intensity on T2-weighted image. MRI is regarded as a useful diagnostic method where conventional diagnosis is difficult, and is able to image cartilage abnormalities directly and noninvasively. Significant differences in MR findings between IS and AS were not noted, however

MR findings of central nerocytoma

International Nuclear Information System (INIS)

Lee, Chang Hoon; Kim, Dong Ik; Lee, Byung Hee; Kim, Myung Soon

1997-01-01

Central neurocytoma is a reae neuronal differentiated intraventricular tomor of young adults. The purpose of this study was to evaluate the characteristic MR appearance of central neurocytoma. We retrospectively reviewed MR images of 12 patients with central neurocytoma, confirmed by ultrastructural and immunohistochemical study. We analyzed patient age, and on all sequences, tumor location, extension into the third ventricle, involvement of brain parenchyma, cyst, hemorrhage, vascular signal void and signal intensity ; and egree of Gd-enhancement was examined on MR images, pattern of calcification on CT, and neovascularity, tumor staining on angiography. Age distribution was wide ranging from 26 to 64 years ; the most frequent age group was the fourth decade (five patients). All tumors except one (in the third ventricle) were located in the lateral ventricle and most were seen in the region of the foramen of Monro (10 cases). Tumors showed extension into the third ventricle and involvement of parenchyma in three cases. The internal architecture of the tumor was heterogenous and consisted of cysts (83%), hemorrhage (25%) and vascular signal void (25%). The solid portion of the tumor showed variable signal intensity on T1-weighted images and iso or high signal intensity on T2- and proton density-weighted images. On MR imaging, mild to moderate heterogenous Gd-enhancement was seen in ten cases (83%), and on CT, a spotted, amorphous, nodular pattern of calcifications was seen in seven cases (63%). On angiography, neovasevlarity and tumor staining was seen in three cases (100%). The typical location of the lateral and third ventricles and MR imaging characteristics including variable signal intensity and heterogenous internal architecture are helpful in the diagnosis of central neurocytoma in young adults

A typical MR imaging of multiple sclerosis

Energy Technology Data Exchange (ETDEWEB)

Katagiri, Shinako; Kan, Shinichi; Ikeda, Toshiaki; Nishiyama, Syougo; Nishimaki, Hiroshi; Matsubayashi, Takashi; Hata, Takashi [Kitasato Univ., Sagamihara, Kanagawa (Japan). School of Medicine

1995-06-01

MR imaging is very useful in detecting the intracranial lesion of multiple sclerosis (MS). We present six patients of MS with atypical MR imaging findings. Six patients aged 27-56 years (mean 36 years), and sexuality of six patients were 2 men and 4 females. Three patient`s clinical course had episodes of optic neuritis. The plaque`s size of the predominant lesion of the patients ranged from 3.0 to 9.0 cm in diameter. The plaques were oval, elliptically and other shaped. At acute stage, MR imaging detected perfocal edema and focal mass effect in three cases of our study. Two out of six cases showed multiple irregularly enhancing lesion with Gadolinium-DTPA. Plaques of all cases did not disappear completely in final MR imaging study. (author).

MR findings of wernicke encephalopathy

International Nuclear Information System (INIS)

Yoon, Hyun Ki; Chang, Kee Hyun; Lee, Goo; Han, Moon Hee; Park, Sung Ho; Na, Duk Yull; Song, Chi Sung

1991-01-01

Seven patients (33 to 58 years old) with clinical diagnoses of Wernicke encephalopathy were examined with MR on either a 2.0T (5 cases) or a 0.5T scanner (2 cases) using spin-echo pulse sequences. In 2 patients, follow-up MR studies were performed 1 and 5 weeks after thiamine (vitamine B1) treatment. Five patients (4 chronic alcoholics and 1 with hyperemesis gravidarum) showed atrophy of both mamillary bodies, along with patchy lesions around the third ventricle, medial thalami, tectum of the midbrain, and periaqueductal gray matter. Another patient with hyperemesis of gravidrum demonstrated only slightly atrophic mamillary bodies, and the last patient with severe vomiting after gastrojejunostomy showed only diencephaic/mesencephalic lesions with apparently normal mamillary bodies. A follow-up MR showed a decrease in previously-noted diencephalic/-/mesencephalic lesions but no change in the size of the mamillary bodies. Diencephalic/mesencephalic lesions were well seen as a high-signal intensity on proton-and T2-weighted axial images, while atrophy of the mamillary bodies was seen best on T1-weighted sagittal images. MR imaging is very useful in demonstrating the characteristic lesions of Wernicke encephalopathy and in evaluating the result of treatment on follow-up study

MR angiography

International Nuclear Information System (INIS)

Masaryk, T.J.; Ross, J.S.

1991-01-01

This paper reports on preliminary research and recent clinical experience which indicates that MR angiography can play a role in routine scanning by providing useful information regarding the anatomy of the cerebral circulation. Used in conjunction with conventional spin-echo studies it may improve the overall sensitivity and specificity of MRI in a cost-effective fashion. It does not, however, replace conventional arteriography at this time for either extracranial or intracranial disease. The use of intravascular contrast agents with new fast-scan techniques also provides dynamic information regarding tissue perfusion in a fashion analogous to that of xenon CT. While this work is preliminary, and the exact agents and mathematical models have yet to be defined, the ability to perform parenchymal, angiographic, and physiologic imaging at a single setting is potentially very powerful. Clearly, the role of MR flow techniques deserves further investigation into possible technical refinements, so that accuracy relative to other diagnostic studies and impact upon patient management can be assessed in a meaningful way

Wrist and finger joint MR imaging in rheumatoid arthritis

DEFF Research Database (Denmark)

Klarlund, Mette; Østergaard, Mikkel; Gideon, P

1999-01-01

PURPOSE: To elaborate the best MR imaging protocol for studies in rheumatoid arthritis (RA) and to evaluate the sensitivity and interobserver agreement with respect to detection of bone erosions (MR and radiography) and grading of synovial membrane hypertrophy (MR imaging only). MATERIAL...