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Sample records for machine perfusion benefits

  1. Does machine perfusion decrease ischemia reperfusion injury?

    Science.gov (United States)

    Bon, D; Delpech, P-O; Chatauret, N; Hauet, T; Badet, L; Barrou, B

    2014-06-01

    In 1990's, use of machine perfusion for organ preservation has been abandoned because of improvement of preservation solutions, efficient without perfusion, easy to use and cheaper. Since the last 15 years, a renewed interest for machine perfusion emerged based on studies performed on preclinical model and seems to make consensus in case of expanded criteria donors or deceased after cardiac death donations. We present relevant studies highlighted the efficiency of preservation with hypothermic machine perfusion compared to static cold storage. Machines for organ preservation being in constant evolution, we also summarized recent developments included direct oxygenation of the perfusat. Machine perfusion technology also enables organ reconditioning during the last hours of preservation through a short period of perfusion on hypothermia, subnormothermia or normothermia. We present significant or low advantages for machine perfusion against ischemia reperfusion injuries regarding at least one primary parameter: risk of DFG, organ function or graft survival. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  2. Machine perfusion for improving outcomes following renal transplant: current perspectives

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    Cannon RM

    2016-03-01

    Full Text Available Robert M Cannon,1 Glen A Franklin1,2 1The Hiram C Polk Jr MD Department of Surgery, University of Louisville, 2Kentucky Organ Donor Affiliates, Louisville, KY, USAAbstract: There is a disparity between the number of kidneys available for transplantation and the number of patients awaiting an organ while on dialysis. The current kidney waiting list in the US contains more than 100,000 patients. This need has led to the inclusion of older donors with worsening renal function, as well as greater utilization of kidneys from non-heartbeating (donation after cardiac death donors. Coinciding with this trend has been a growing interest in technology to improve the function of these more marginal organs, the most important of which currently is machine perfusion (MP of donated kidneys after procurement. While this technology has no standard guidelines currently for comprehensive use, there are many studies that demonstrate higher organ yield and function after a period of MP. Particularly with the older donor and during donation after cardiac death cases, MP may offer some significant benefits. This manuscript reviews all of the current literature regarding MP and its role in renal transplantation. We will discuss both the experience in Europe and the US using machine perfusion for donated kidneys.Keywords: machine perfusion, renal transplantation, kidney pumping, renal failure, organ donation

  3. Lipid peroxidation products in machine perfusion of older donor kidneys

    NARCIS (Netherlands)

    Nagelschmidt, Manfred; Minor, Thomas; Gallinat, Anja; Moers, Cyril; Jochmans, Ina; Pirenne, Jacques; Ploeg, Rutger J.; Paul, Andreas; Treckmann, Juergen

    2013-01-01

    Background: Owing to the shortage of donors, organs with an increased risk potential such as grafts recovered from expanded criteria donors are increasingly being used in transplants. Machine perfusion (MP) technology offers the possibility of determining the biomarkers in the perfusion solution so

  4. Hypothermic Machine Perfusion of Kidney Grafts: Which Pressure is Preferred?

    NARCIS (Netherlands)

    B.M. Doorschodt; M.C.J.M. Schreinemachers; M. Behbahani; S. Florquin; J. Weis; M. Staat; R.H. Tolba

    2011-01-01

    To assess the effect of the perfusion pressure (PP) during machine perfusion (MP) on the preservation quality of kidney grafts, we compared mean PPs of 25 and 30 mmHg using a porcine autotransplantation model. After assessment of the microcirculation, animals underwent left nephrectomy. Thereafter,

  5. Lipid peroxidation products in machine perfusion of older donor kidneys

    NARCIS (Netherlands)

    Nagelschmidt, Manfred; Minor, Thomas; Gallinat, Anja; Moers, Cyril; Jochmans, Ina; Pirenne, Jacques; Ploeg, Rutger J.; Paul, Andreas; Treckmann, Juergen

    Background: Owing to the shortage of donors, organs with an increased risk potential such as grafts recovered from expanded criteria donors are increasingly being used in transplants. Machine perfusion (MP) technology offers the possibility of determining the biomarkers in the perfusion solution so

  6. Ex Situ Normothermic Machine Perfusion of Donor Livers

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    Karimian, Negin; Matton, Alix P.M.; Westerkamp, Andrie C.; Burlage, Laura C.; op den Dries, Sanna; Leuvenink, Henri G.D.; Lisman, Ton; Uygun, Korkut; Markmann, James F.; Porte, Robert J.

    2015-01-01

    In contrast to conventional static cold preservation (0-4 °C), ex situ machine perfusion may provide better preservation of donor livers. Continuous perfusion of organs provides the opportunity to improve organ quality and allows ex situ viability assessment of donor livers prior to transplantation. This video article provides a step by step protocol for ex situ normothermic machine perfusion (37 °C) of human donor livers using a device that provides a pressure and temperature controlled pulsatile perfusion of the hepatic artery and continuous perfusion of the portal vein. The perfusion fluid is oxygenated by two hollow fiber membrane oxygenators and the temperature can be regulated between 10 °C and 37 °C. During perfusion, the metabolic activity of the liver as well as the degree of injury can be assessed by biochemical analysis of samples taken from the perfusion fluid. Machine perfusion is a very promising tool to increase the number of livers that are suitable for transplantation. PMID:26067131

  7. The Groningen hypothermic liver perfusion pump : Functional evaluation of a new machine perfusion system

    NARCIS (Netherlands)

    van der Plaats, A.; Maathuis, M. H. J.; Hart, N. A. 't; Bellekom, A. A.; Hofker, H. S.; van der Houwen, E. B.; Verkerke, G. J.; Leuvenink, H. G. D.; Verdonck, P.; Ploeg, R. J.; Rakhorst, G.

    2006-01-01

    To improve preservation of donor livers, we have developed a portable hypothermic machine perfusion (HMP) system as an alternative for static cold storage. A prototype of the system was built and evaluated on functionality. Evaluation criteria included 24 h of adequate pressure controlled perfusion,

  8. Oxygenated machine perfusion preservation of predamaged kidneys with HTK and Belzer machine perfusion solution: An experimental study in pigs

    NARCIS (Netherlands)

    Manekeller, S.; Leuvenink, Henri; Sitzia, M.; Minor, T.

    2005-01-01

    The objective of the present study was to evaluate the recently proposed aerobic machine preservation with the noncolloidal HTK solution by comparison with the colloidal Belzer machine perfusion solution (MPS) after procurement of marginal kidneys from non-heart-beating donors. Kidneys were harveste

  9. Oxygenated machine perfusion preservation of predamaged kidneys with HTK and Belzer machine perfusion solution : An experimental study in pigs

    NARCIS (Netherlands)

    Manekeller, S; Leuvenink, H; Sitzia, M; Minor, T

    2005-01-01

    The objective of the present study was to evaluate the recently proposed aerobic machine preservation with the noncolloidal HTK solution by comparison with the colloidal Belzer machine perfusion solution (MPS) after procurement of marginal kidneys from non-heart-beating donors. Kidneys were harveste

  10. [The Application of Machine Perfusion on Clinical Liver Transplantation].

    Science.gov (United States)

    Ren, Fenggang; Zhu, Haoyang; Yan, Xiaopeng; Liu, Chang; Zhang, Xiaogang; Lv, Yi

    2015-11-01

    Liver transplantation is the only way to treat end-stage liver disease. In order to overcome the shortage of donor, marginal donors have been used widely, which bring about a series of problems. Machine perfusion can stimulate the circulation in vivo and is beneficial for the protection of liver. It could also improve the graft function and reduce postoperative complications, which makes it a hot spot in recent years. The aim of this study is to summarize the current status and prospects of application of machine perfusion on clinical liver transplantation.

  11. End-ischemic machine perfusion reduces bile duct injury in donation after circulatory death rat donor livers independent of the machine perfusion temperature

    NARCIS (Netherlands)

    Westerkamp, Andrie C.; Mahboub, Paria; Meyer, Sophie L.; Hottenrott, Maximilia; Ottens, Petra J.; Wiersma-Buist, Janneke; Gouw, Annette S. H.; Lisman, Ton; Leuvenink, Henri G. D.; Porte, Robert J.

    2015-01-01

    A short period of oxygenated machine perfusion (MP) after static cold storage (SCS) may reduce biliary injury in donation after cardiac death (DCD) donor livers. However, the ideal perfusion temperature for protection of the bile ducts is unknown. In this study, the optimal perfusion temperature for

  12. Protective mechanisms of end-ischemic cold machine perfusion in DCD liver grafts.

    Science.gov (United States)

    Schlegel, Andrea; de Rougemont, Olivier; Graf, Rolf; Clavien, Pierre-Alain; Dutkowski, Philipp

    2013-02-01

    The aim of this study was to identify protective mechanisms of cold machine perfusion in liver grafts donated after cardiac death. Pig livers exposed to 60-min warm ischemia were cold stored for 7 h or treated after 6-h cold storage with 1-h hypothermic oxygenated perfusion (HOPE) through the portal vein. Different physical (perfusion pressure) and chemical (oxygen, mitochondrial transition pore inhibition) parameters were analyzed during machine perfusion to dissect key steps of mechanism. HOPE treatment led to a significant slowdown of mitochondrial respiration rate during 1-h machine perfusion. After reperfusion following low pressure HOPE, mitochondrial injury, nuclear injury, Kupffer cell activation and endothelial injury were significantly improved, as tested on an isolated liver perfusion model. In contrast, machine perfusion with deoxygenated perfusate showed no protection from hepatocyte injury and Kupffer cell activation. However, endothelial injury was also prevented by low pressure machine perfusion in the absence of oxygen. Perfusion with higher pressure provoked endothelial damage and Kupffer cell activation. The mechanisms of protection by hypothermic machine perfusion appear to be at least twofold. First, oxygenation under hypothermic conditions protects from mitochondrial and nuclear injury by downregulation of mitochondrial activity before reperfusion. Second, cold perfusion itself, under low pressure conditions, prevents endothelial damage, independently of oxygen. Copyright © 2012 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

  13. Addressing the Donor Liver Shortage with EX VIVO Machine Perfusion

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    Maria-Louisa Izamis

    2012-01-01

    Full Text Available Despite a critical shortage of viable donor livers for transplantation, only a fraction of the available organs are used. Donor organ defects, which in the majority of cases are caused by extensive exposure to ischemia, cannot be reversed by static cold storage, the current gold standard of organ preservation. In this review, the role of machine perfusion (MP in the recovery of non-transplantable ischemic donor organs is discussed. Though still in the experimental phase, various models of MP have consistently demonstrated that ischemic donor organs can be recovered to a transplantable state through continuous perfusion. MP can also provide dynamic quantitative assessments of the extent of ischemia, in addition to predicting the likelihood of organ recovery. Continued endeavors to translate MP into clinical use and eventually incorporate it into routine donor organ care will have a significant impact on the quality and availability of transplantable donor organs.

  14. Machine perfusion enhances hepatocyte isolation yields from ischemic livers.

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    Izamis, Maria-Louisa; Perk, Sinem; Calhoun, Candice; Uygun, Korkut; Yarmush, Martin L; Berthiaume, François

    2015-10-01

    High-quality human hepatocytes form the basis of drug safety and efficacy tests, cell-based therapies, and bridge-to-transplantation devices. Presently the only supply of cells derives from an inadequate pool of suboptimal disqualified donor livers. Here we evaluated whether machine perfusion could ameliorate ischemic injury that many of these livers experience prior to hepatocyte isolation. Non-heparinized female Lewis rat livers were exposed to an hour of warm ischemia (34°C) and then perfused for 3h. Five different perfusion conditions that utilized the cell isolation apparatus were investigated, namely: (1) modified Williams Medium E and (2) Lifor, both with active oxygenation (95%O(2)/5%CO(2)), as well as (3) Lifor passively oxygenated with ambient air (21%O(2)/0.04%CO(2)), all at ambient temperatures (20 ± 2°C). At hypothermic temperatures (5 ± 1°C) and under passive oxygenation were (4) University of Wisconsin solution (UW) and (5) Vasosol. Negative and positive control groups comprised livers that had ischemia (WI) and livers that did not (Fresh) prior to cell isolation, respectively. Fresh livers yielded 32 ± 9 million cells/g liver while an hour of ischemia reduced the cell yield to 1.6 ± 0.6 million cells/g liver. Oxygenated Williams Medium E and Lifor recovered yields of 39 ± 11 and 31 ± 2.3 million cells/g liver, respectively. The passively oxygenated groups produced 15 ± 7 (Lifor), 13 ± 7 (Vasosol), and 10 ± 6 (UW)million cells/g liver. Oxygenated Williams Medium E was most effective at sustaining pH values, avoiding the accumulation of lactate, minimizing edematous weight gain and producing bile during perfusion. Machine perfusion results in a dramatic increase in cell yields from livers that have had up to an hour of warm ischemia, but perfusate choice significantly impacts the extent of recovery. Oxygenated Williams Medium E at room temperature is superior to Lifor, UW and Vasosol, largely facilitated by its high oxygen content and low

  15. Metabolomic perfusate analysis during kidney machine perfusion: the pig provides an appropriate model for human studies.

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    Jay Nath

    Full Text Available Hypothermic machine perfusion offers great promise in kidney transplantation and experimental studies are needed to establish the optimal conditions for this to occur. Pig kidneys are considered to be a good model for this purpose and share many properties with human organs. However it is not established whether the metabolism of pig kidneys in such hypothermic hypoxic conditions is comparable to human organs.Standard criteria human (n = 12 and porcine (n = 10 kidneys underwent HMP using the LifePort Kidney Transporter 1.0 (Organ Recovery Systems using KPS-1 solution. Perfusate was sampled at 45 minutes and 4 hours of perfusion and metabolomic analysis performed using 1-D 1H-NMR spectroscopy.There was no inter-species difference in the number of metabolites identified. Of the 30 metabolites analysed, 16 (53.3% were present in comparable concentrations in the pig and human kidney perfusates. The rate of change of concentration for 3-Hydroxybutyrate was greater for human kidneys (p<0.001. For the other 29 metabolites (96.7%, there was no difference in the rate of change of concentration between pig and human samples.Whilst there are some differences between pig and human kidneys during HMP they appear to be metabolically similar and the pig seems to be a valid model for human studies.

  16. Determination of an adequate perfusion pressure for continuous dual vessel hypothermic machine perfusion of the rat liver

    NARCIS (Netherlands)

    't Hart, Nils A.; der van Plaats, Arjan; Leuvenink, Henri G. D.; van Goor, Harry; Wiersema-Buist, Janneke; Verkerke, Gijsbertus J.; Rakhorst, Gerhard; Ploeg, Rutger J.

    Hypothermic machine perfusion (HMP) provides better protection against ischemic damage of the kidney compared to cold-storage. The required perfusion pressures needed for optimal HMP of the liver are, however, unknown. Rat livers were preserved in University of Wisconsin organ preservation solution

  17. Impact of Temperature on Porcine Liver Machine Perfusion From Donors After Cardiac Death.

    Science.gov (United States)

    Nassar, Ahmed; Liu, Qiang; Farias, Kevin; Buccini, Laura; Baldwin, William; Bennett, Ana; Mangino, Martin; Irefin, Samuel; Cywinski, Jacek; Okamoto, Toshihiro; Diago Uso, Teresa; Iuppa, Giuseppe; Soliman, Basem; Miller, Charles; Quintini, Cristiano

    2016-10-01

    Normothermic machine perfusion (NMP) has been introduced as a promising technology to preserve and possibly repair marginal liver grafts. The aim of this study was to compare the effect of temperature on the preservation of donation after cardiac death (DCD) liver grafts in an ex vivo perfusion model after NMP (38.5°C) and subnormothermic machine perfusion (SNMP, 21°C) with a control group preserved by cold storage (CS, 4°C). Fifteen porcine livers with 60 min of warm ischemia were preserved for 10 h by NMP, SNMP or CS (n = 5/group). After the preservation phase all livers were reperfused for 24 h in an isolated perfusion system with whole blood at 38.5°C to simulate transplantation. At the end of transplant simulation, the NMP group showed significantly lower hepatocellular enzyme level (AST: 277 ± 69 U/L; ALT: 22 ± 2 U/L; P production was significantly higher in the NMP group (219 ± 43 mL; P < 0.01) compared to both SNMP (49 ± 84 mL) and CS (12 ± 16 mL) with no significant difference between the latter two groups. Histologically, the NMP livers showed preserved cellular architecture compared to the SNMP and CS groups. NMP was able to recover DCD livers showing superior hepatocellular integrity, biliary function, and microcirculation compared to SNMP and CS. SNMP showed some significant benefit over CS, yet has not shown any advantage over NMP.

  18. Chronic renoprotective effect of pulsatile perfusion machine RM3 and IGL-1 solution in a preclinical kidney transplantation model

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    Thuillier Raphael

    2012-11-01

    Full Text Available Abstract Background Machine perfusion (MP of kidney graft provides benefits against preservation injury, however decreased graft quality requires optimization of the method. We examined the chronic benefits of MP on kidney grafts and the potential improvements provided by IGL-1 solution. Method We used an established autotransplantation pig kidney model to study the effects of MP against the deleterious effects of warm ischemia (WI: 60 minutes followed by 22 hours of cold ischemia in MP or static cold storage (CS followed by autotransplantation. MPS and IGL-1 solutions were compared. Results Animal survival was higher in MPS-MP and both IGL groups. Creatinine measurement did not discriminate between the groups, however MPS-MP and both IGL groups showed decreased proteinuria. Chronic fibrosis level was equivalent between the groups. RTqPCR and immunohistofluorescent evaluation showed that MP and IGL-1 provided some protection against epithelial to mesenchymal transition and chronic lesions. IGL-1 was protective with both MP and CS, particularly against chronic inflammation, with only small differences between the groups. Conclusion IGL-1 used in either machine or static preservation offers similar levels of protection than standard MP. The compatibility of IGL-1 with both machine perfusion and static storage could represent an advantage for clinical teams when choosing the correct solution to use for multi-organ collection. The path towards improving machine perfusion, and organ quality, may involve the optimization of the solution and the correct use of colloids.

  19. Kidney transplantation after oxygenated machine perfusion preservation with Custodiol-N solution.

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    Minor, Thomas; Paul, Andreas; Efferz, Patrik; Wohlschlaeger, Jeremias; Rauen, Ursula; Gallinat, Anja

    2015-09-01

    Custodiol-N, a new preservation solution, has been shown particularly suitable for hypothermic machine perfusion preservation (HMP) in isolated porcine kidneys. These preliminary results should be confirmed in an actual transplant model in vivo. Kidney function after 21 h of HMP was studied in an autotransplant model using Landrace pigs (25-30 kg; n = 6 per group). Perfusion was performed with oxygenated perfusate, using either Custodiol-N solution including 50 g/l dextran 40 (CND) or kidney perfusion solution 1 (KPS-1) as gold standard. Viability of the grafts was followed for 1 week after bilateral nephrectomy in the recipient pigs. HMP with CND resulted in less acute tubular injury, evaluated by levels of fatty acid-binding protein and better clearance function during the first 24 h after Tx than with KPS-1 (P perfusate for renal machine perfusion.

  20. End-ischemic machine perfusion reduces bile duct injury in donation after circulatory death rat donor livers independent of the machine perfusion temperature.

    Science.gov (United States)

    Westerkamp, Andrie C; Mahboub, Paria; Meyer, Sophie L; Hottenrott, Maximilia; Ottens, Petra J; Wiersema-Buist, Janneke; Gouw, Annette S H; Lisman, Ton; Leuvenink, Henri G D; Porte, Robert J

    2015-10-01

    A short period of oxygenated machine perfusion (MP) after static cold storage (SCS) may reduce biliary injury in donation after cardiac death (DCD) donor livers. However, the ideal perfusion temperature for protection of the bile ducts is unknown. In this study, the optimal perfusion temperature for protection of the bile ducts was assessed. DCD rat livers were preserved by SCS for 6 hours. Thereafter, 1 hour of oxygenated MP was performed using either hypothermic machine perfusion, subnormothermic machine perfusion, or with controlled oxygenated rewarming (COR) conditions. Subsequently, graft and bile duct viability were assessed during 2 hours of normothermic ex situ reperfusion. In the MP study groups, lower levels of transaminases, lactate dehydrogenase (LDH), and thiobarbituric acid reactive substances were measured compared to SCS. In parallel, mitochondrial oxygen consumption and adenosine triphosphate (ATP) production were significantly higher in the MP groups. Biomarkers of biliary function, including bile production, biliary bicarbonate concentration, and pH, were significantly higher in the MP groups, whereas biomarkers of biliary epithelial injury (biliary gamma-glutamyltransferase [GGT] and LDH), were significantly lower in MP preserved livers. Histological analysis revealed less injury of large bile duct epithelium in the MP groups compared to SCS. In conclusion, compared to SCS, end-ischemic oxygenated MP of DCD livers provides better preservation of biliary epithelial function and morphology, independent of the temperature at which MP is performed. End-ischemic oxygenated MP could reduce biliary injury after DCD liver transplantation. © 2015 American Association for the Study of Liver Diseases.

  1. Criteria for viability assessment of discarded human donor livers during ex vivo normothermic machine perfusion.

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    Michael E Sutton

    Full Text Available Although normothermic machine perfusion of donor livers may allow assessment of graft viability prior to transplantation, there are currently no data on what would be a good parameter of graft viability. To determine whether bile production is a suitable biomarker that can be used to discriminate viable from non-viable livers we have studied functional performance as well as biochemical and histological evidence of hepatobiliary injury during ex vivo normothermic machine perfusion of human donor livers. After a median duration of cold storage of 6.5 h, twelve extended criteria human donor livers that were declined for transplantation were ex vivo perfused for 6 h at 37 °C with an oxygenated solution based on red blood cells and plasma, using pressure controlled pulsatile perfusion of the hepatic artery and continuous portal perfusion. During perfusion, two patterns of bile flow were identified: (1 steadily increasing bile production, resulting in a cumulative output of ≥ 30 g after 6 h (high bile output group, and (2 a cumulative bile production <20 g in 6 h (low bile output group. Concentrations of transaminases and potassium in the perfusion fluid were significantly higher in the low bile output group, compared to the high bile output group. Biliary concentrations of bilirubin and bicarbonate were respectively 4 times and 2 times higher in the high bile output group. Livers in the low bile output group displayed more signs of hepatic necrosis and venous congestion, compared to the high bile output group. In conclusion, bile production could be an easily assessable biomarker of hepatic viability during ex vivo machine perfusion of human donor livers. It could potentially be used to identify extended criteria livers that are suitable for transplantation. These ex vivo findings need to be confirmed in a transplant experiment or a clinical trial.

  2. Xeno- and auto-perfusion of rabbit kidney. Machine perfusion with blood at 37 degrees C

    DEFF Research Database (Denmark)

    Jørgensen, K A; Kemp, E; Barfort, P;

    1985-01-01

    Five rabbit kidneys were perfused with human blood and another five with their own blood in a re-circulating oxygenated system at 37 degrees C. The flow decreased to 2 ml/min. within 30 min. in all xenoperfusions, while none of the autoperfused had decreased to this level by 60 min. Endothelial...

  3. Functional Human Liver Preservation and Recovery by Means of Subnormothermic Machine Perfusion

    NARCIS (Netherlands)

    Bruinsma, Bote G.; Avruch, James H.; Weeder, Pepijn D.; Sridharan, Gautham V.; Uygun, Basak E.; Karimian, Negin G.; Porte, Robert J.; Markmann, James F.; Yeh, Heidi; Uygun, Korkut

    2015-01-01

    There is currently a severe shortage of liver grafts available for transplantation. Novel organ preservation techniques are needed to expand the pool of donor livers. Machine perfusion of donor liver grafts is an alternative to traditional cold storage of livers and holds much promise as a modality

  4. Criteria for Viability Assessment of Discarded Human Donor Livers during Ex Vivo Normothermic Machine Perfusion

    NARCIS (Netherlands)

    Sutton, Michael E.; op den Dries, Sanna; Karimian, Negin; Weeder, Pepijn D.; de Boer, Marieke T.; Wiersema-Buist, Janneke; Gouw, Annette S. H.; Leuvenink, Henri G. D.; Lisman, Ton; Porte, Robert J.

    2014-01-01

    Although normothermic machine perfusion of donor livers may allow assessment of graft viability prior to transplantation, there are currently no data on what would be a good parameter of graft viability. To determine whether bile production is a suitable biomarker that can be used to discriminate vi

  5. Normothermic Machine Perfusion Reduces Bile Duct Injury and Improves Biliary Epithelial Function in Rat Donor Livers

    NARCIS (Netherlands)

    Op den Dries, Sanna; Karimian, Negin; Westerkamp, Andrie C; Sutton, Michael E; Kuipers, Michiel; Wiersema-Buist, Janneke; Ottens, Petra J; Kuipers, Jeroen; Giepmans, Ben N; Leuvenink, Henri G D; Lisman, Ton; Porte, Robert J

    BACKGROUND: Bile duct injury may occur during liver procurement and transplantation, especially in livers donated after circulatory death (DCD). Normothermic machine perfusion (NMP) has been shown to reduce hepatic injury, compared to static cold storage (SCS). However, it is unknown whether NMP

  6. Effect of continuous hypothermic machine perfusion transport system (AirdriveTM) on canine kidney preservation

    Institute of Scientific and Technical Information of China (English)

    Hu Xiaopeng; Xue Wenrui; Zhang Qiang; Wang Wei; Zhang Jiqing; Zhang Xiaodong

    2014-01-01

    Background Organ preservation keeps the quality of the organs under prolonged ischemia.Continuous machine perfusions are gaining an important position in clinical research and practice.The aim of this study was to evaluate the protective effect of continuous hypothermic machine perfusion transport system (AirdriveTM) on cold ischemic injury of canine kidney.Methods Ten kidneys of five healthy preserving canines were taken out after general anesthesia.Five kidneys were stored using common cold preservation (CCP group) by immersing it in the organ preservation solution,mixed with water and ice,and kept in a cold room at 4℃.The other five kidneys were stored using continuous machine perfusion preservation (CMP group) and were placed into the AirdriveTM continuous machine perfusion device at room temperature.The renal tissues were examined by histopathology,electron microscopy,and mitochondrial activity check at different time points.Results Histologic sections showed that the structures of the ten renal tissues were similar during the first 24 hours.After 48 hours,the CCP group showed more pronounced changes,as the renal tubular epithelial cells were more obvious than those in the glomeruli.Oxygen consumption rate of state Ⅲ and Ⅳ respiration in the CCP group decreased after 12-48 hours and increased at 48 hours,respectively,when compared to the CMP group (P <0.05).Cortex respiratory control ratio and phosphorus oxygen ratio were significantly higher in the CMP group at 48 hours.Conclusion With prolonged storage time,the effect of continuous hypothermic machine perfusion transport system is better than that of common cold preservation on canine kidney.

  7. SPECT Myocardial Blood Flow Quantitation Concludes Equivocal Myocardial Perfusion SPECT Studies to Increase Diagnostic Benefits.

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    Chen, Lung-Ching; Lin, Chih-Yuan; Chen, Ing-Jou; Ku, Chi-Tai; Chen, Yen-Kung; Hsu, Bailing

    2016-01-01

    Recently, myocardial blood flow quantitation with dynamic SPECT/CT has been reported to enhance the detection of coronary artery disease in human. This advance has created important clinical applications to coronary artery disease diagnosis and management for areas where myocardial perfusion PET tracers are not available. We present 2 clinical cases that undergone a combined test of 1-day rest/dipyridamole-stress dynamic SPECT and ECG-gated myocardial perfusion SPECT scans using an integrated imaging protocol and demonstrate that flow parameters are capable to conclude equivocal myocardial perfusion SPECT studies, therefore increasing diagnostic benefits to add value in making clinical decisions.

  8. Use of the new preservation solution Custodiol-N supplemented with dextran for hypothermic machine perfusion of the kidney.

    Science.gov (United States)

    Gallinat, Anja; Lüer, Bastian; Swoboda, Sandra; Rauen, Ursula; Paul, Andreas; Minor, Thomas

    2013-04-01

    Custodiol-N is a new preservation solution specifically designed to prevent free radical-induced tissue alterations and to protect vascular integrity of the graft. Thus, Custodiol-N appears particularly suitable as base solution for oxygenated machine preservation and its putative benefit for renal preservation by hypothermic machine perfusion (HMP) was investigated using a porcine in vitro model. Kidneys were retrieved from German Landrace pigs and preserved for 20 h by pulsatile oxygenated HMP on a Lifeport kidney transporter (syst. pressure 30 mmHg, 30cycles/min). Each graft was randomly assigned to the use of one of the following preservation solutions: Custodiol-N solution supplemented with 50 g/l dextran 40 (CND) or kidney perfusion solution 1 (KPS-1). Renal viability was evaluated upon reperfusion in vitro with diluted autologous blood from the donor for 120 min at 37°C. After 2h of postischemic reperfusion CND-preserved kidneys exhibited significantly higher renal blood flow and urine production. Oxygen consumption was also higher in the CND group than in KPS-1 kidneys. Clearance of creatinine increased during reperfusion of CND kidneys but declined in KPS-1 grafts ending in significantly higher values in CND kidneys. No differences between the groups were seen for enzyme release or fractional excretion of sodium. In conclusion the data presented provide first experimental evidence for adequate organ protective potential of CND in HMP as compared to the gold standard KPS-KPS-11.

  9. Ex vivo normothermic machine perfusion is safe, simple, and reliable: results from a large animal model.

    Science.gov (United States)

    Nassar, Ahmed; Liu, Qiang; Farias, Kevin; D'Amico, Giuseppe; Tom, Cynthia; Grady, Patrick; Bennett, Ana; Diago Uso, Teresa; Eghtesad, Bijan; Kelly, Dympna; Fung, John; Abu-Elmagd, Kareem; Miller, Charles; Quintini, Cristiano

    2015-02-01

    Normothermic machine perfusion (NMP) is an emerging preservation modality that holds the potential to prevent the injury associated with low temperature and to promote organ repair that follows ischemic cell damage. While several animal studies have showed its superiority over cold storage (CS), minimal studies in the literature have focused on safety, feasibility, and reliability of this technology, which represent key factors in its implementation into clinical practice. The aim of the present study is to report safety and performance data on NMP of DCD porcine livers. After 60 minutes of warm ischemia time, 20 pig livers were preserved using either NMP (n = 15; physiologic perfusion temperature) or CS group (n = 5) for a preservation time of 10 hours. Livers were then tested on a transplant simulation model for 24 hours. Machine safety was assessed by measuring system failure events, the ability to monitor perfusion parameters, sterility, and vessel integrity. The ability of the machine to preserve injured organs was assessed by liver function tests, hemodynamic parameters, and histology. No system failures were recorded. Target hemodynamic parameters were easily achieved and vascular complications were not encountered. Liver function parameters as well as histology showed significant differences between the 2 groups, with NMP livers showing preserved liver function and histological architecture, while CS livers presenting postreperfusion parameters consistent with unrecoverable cell injury. Our study shows that NMP is safe, reliable, and provides superior graft preservation compared to CS in our DCD porcine model. © The Author(s) 2014.

  10. A basic consideration for porcine liver preservation using a novel continuous machine perfusion device.

    Science.gov (United States)

    Shigeta, T; Matsuno, N; Huai-Che, H; Obara, H; Mizunuma, H; Hirano, T; Uemoto, S; Enosawa, S

    2012-05-01

    The aims of this study were to compare extracellular and intracellular-type University of Wisconsin (UW) solutions for liver grafts and to assess oxygenation in this perfusion system. The organ preservation system consisted of 3 circulating systems for the portal vein, hepatic artery, and maintenance of the perfusion solution. The portal vein or hepatic artery system had a roller pump, a flow meter, and a pressure sensor. In this study, we perfused livers with UW or extracellular type UW-gluconate at 4°C-6°C for 4 hours. The flow rates at the entrance were 0.5 mL/min/g liver in the portal vein and 0.2 mL/min/liver in the hepatic artery. Orthotopic liver transplantation was performed in pigs: group 1-a, grafts procured after acute hemorrhagic shock were preserved by a solution without O(2); group 1-b, grafts were preserved with O(2); group 2-a, grafts were perfused using intracellular type solution (UW); and group 2-b, grafts were perfused using extracellular-type solution (UW-gluconate). Effluent aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) levels in group 1-b were lower than those in group 1-a. Survival rates in group 2-a and group 2-b were 1/4 and 3/3, respectively. Effluent AST and LDH levels in the perfusate of group 2-b were lower than group 2-a. Histological study revealed necrosis of hepatocytes and sinusoidal congestion in group 2-a. A beneficial effect of extracellular-type solution with oxygenation in a novel continuous machine preservation system yielded well-preserved liver graft function. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. Perfusion-diffusion mismatch: does it identify who will benefit from reperfusion therapy?

    Science.gov (United States)

    Powers, William J

    2012-06-01

    A method to determine which patients would benefit from reperfusion therapies after 4.5 h would greatly add to our ability to reduce the disability caused by stroke. The goal of magnetic resonance perfusion-diffusion imaging in hyperacute ischemic stroke is to identify regions of the brain that will die if untreated and will live and regain function if quickly reperfused. The clinical value of perfusion-diffusion imaging in hyperacute ischemic stroke can be proven only by demonstrating empirically in a randomized controlled trial (RCT) that there is an improvement in patient outcome that depends on the use of the neuroimaging modality to guide therapy. To date, there have been only a few RCTs that have evaluated whether perfusion-diffusion imaging can identify a subgroup of patients with ischemic stroke more than 4.5 h from onset in whom the overall benefit from reperfusion therapy outweighs the risk. None have met the rigorous design requirements of the three-group study necessary to adequately test this hypothesis, and none have even met their own criteria for demonstrating a clinical benefit. While studies are not sufficient to conclusively disprove the hypothesis there are no RCT data to support it, and thus, the clinical value of MRI perfusion-diffusion imaging in this setting remains unproven. It is worthy of further investigation in rigorously designed RCTs. However, the risks of symptomatic intracerebral hemorrhage with reperfusion therapies in acute ischemic stroke are proven. Unless RCT data are forthcoming to demonstrate that MRI perfusion-diffusion mismatch improves clinical outcome, it should not be used to guide delayed reperfusion therapy.

  12. Twelve-Hour Hypothermic Machine Perfusion for Donor Heart Preservation Leads to Improved Ultrastructural Characteristics Compared to Conventional Cold Storage.

    Science.gov (United States)

    Michel, Sebastian G; La Muraglia, Glenn M; Madariaga, Maria Lucia L; Titus, James S; Selig, Martin K; Farkash, Evan A; Allan, James S; Anderson, Lisa M; Madsen, Joren C

    2015-01-01

    BACKGROUND Hypothermic machine perfusion of donor hearts has the theoretical advantage of continuous aerobic metabolism and washes out toxic metabolic byproducts. Here, we studied the effect of hypothermic machine perfusion on cardiac myocyte integrity when hearts are preserved for longer ischemic times (12 hours). MATERIAL AND METHODS Pig hearts were harvested and stored in Celsior® solution for 12 hours using either conventional cold storage on ice (12 h CS, n=3) or pulsatile perfusion with the Paragonix Sherpa Perfusion™ Cardiac Transport System at different flow rates (12 h PP, n=3 or 12 h PP low flow, n=2). After cold preservation, hearts were reperfused using an LV isovolumic Langendorff system. Controls (n=3) were reperfused immediately after organ harvest. Biopsies were taken from the apex of the left ventricle before storage, after storage and after reperfusion to measure ATP and endothelin-1 content in the tissue. TUNEL staining for signs of apoptosis and electron microscopy of the donor hearts were performed. RESULTS 12 h PP hearts showed significantly more weight gain than 12 h CS and controls after preservation. Pulsatile perfused hearts showed less ATP depletion, lower endothelin-1 levels and less apoptosis after preservation compared to CS. Electron microscopy showed damaged muscle fibers, endothelial cell rupture, and injury of mitochondria in the 12 h CS group, while machine perfusion could preserve the cell structures. CONCLUSIONS Hypothermic machine perfusion of donor hearts can preserve the cell structures better than conventional cold storage in prolonged ischemic times. Hypothermic pulsatile perfusion may therefore enable longer preservation times of donor hearts. Whether this method is able to avoid primary graft failure after orthotopic heart transplantation remains to be evaluated in further studies.

  13. Channelized relevance vector machine as a numerical observer for cardiac perfusion defect detection task

    Science.gov (United States)

    Kalayeh, Mahdi M.; Marin, Thibault; Pretorius, P. Hendrik; Wernick, Miles N.; Yang, Yongyi; Brankov, Jovan G.

    2011-03-01

    In this paper, we present a numerical observer for image quality assessment, aiming to predict human observer accuracy in a cardiac perfusion defect detection task for single-photon emission computed tomography (SPECT). In medical imaging, image quality should be assessed by evaluating the human observer accuracy for a specific diagnostic task. This approach is known as task-based assessment. Such evaluations are important for optimizing and testing imaging devices and algorithms. Unfortunately, human observer studies with expert readers are costly and time-demanding. To address this problem, numerical observers have been developed as a surrogate for human readers to predict human diagnostic performance. The channelized Hotelling observer (CHO) with internal noise model has been found to predict human performance well in some situations, but does not always generalize well to unseen data. We have argued in the past that finding a model to predict human observers could be viewed as a machine learning problem. Following this approach, in this paper we propose a channelized relevance vector machine (CRVM) to predict human diagnostic scores in a detection task. We have previously used channelized support vector machines (CSVM) to predict human scores and have shown that this approach offers better and more robust predictions than the classical CHO method. The comparison of the proposed CRVM with our previously introduced CSVM method suggests that CRVM can achieve similar generalization accuracy, while dramatically reducing model complexity and computation time.

  14. Machine perfusion versus cold storage of livers: a meta-analysis.

    Science.gov (United States)

    Liu, Sushun; Pang, Qing; Zhang, Jingyao; Zhai, Mimi; Liu, Sinan; Liu, Chang

    2016-12-01

    Different organ preservation methods are key factors influencing the results of liver transplantation. In this study, the outcomes of experimental models receiving donation after cardiac death (DCD) livers preserved through machine perfusion (MP) or static cold storage (CS) were compared by conducting a meta-analysis. Standardized mean difference (SMD) and 95% confidence interval (CI) were calculated to compare pooled data from two animal species. Twenty-four studies involving MP preservation were included in the meta-analysis. Compared with CS preservation, MP can reduce the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and hyaluronic acid (HA) and the changes in liver weight. By contrast, MP can enhance bile production and portal vein flow (PVF). Alkaline phosphatase (ALP) levels and histological changes significantly differed between the two preservation methods. In conclusion, MP of DCD livers is superior to CS in experimental animals.

  15. Cost-Benefit Analysis of Computer Resources for Machine Learning

    Science.gov (United States)

    Champion, Richard A.

    2007-01-01

    Machine learning describes pattern-recognition algorithms - in this case, probabilistic neural networks (PNNs). These can be computationally intensive, in part because of the nonlinear optimizer, a numerical process that calibrates the PNN by minimizing a sum of squared errors. This report suggests efficiencies that are expressed as cost and benefit. The cost is computer time needed to calibrate the PNN, and the benefit is goodness-of-fit, how well the PNN learns the pattern in the data. There may be a point of diminishing returns where a further expenditure of computer resources does not produce additional benefits. Sampling is suggested as a cost-reduction strategy. One consideration is how many points to select for calibration and another is the geometric distribution of the points. The data points may be nonuniformly distributed across space, so that sampling at some locations provides additional benefit while sampling at other locations does not. A stratified sampling strategy can be designed to select more points in regions where they reduce the calibration error and fewer points in regions where they do not. Goodness-of-fit tests ensure that the sampling does not introduce bias. This approach is illustrated by statistical experiments for computing correlations between measures of roadless area and population density for the San Francisco Bay Area. The alternative to training efficiencies is to rely on high-performance computer systems. These may require specialized programming and algorithms that are optimized for parallel performance.

  16. Machine perfusion in liver transplantation as a tool to prevent non-anastomotic biliary strictures: Rationale, current evidence and future directions.

    Science.gov (United States)

    Weeder, Pepijn D; van Rijn, Rianne; Porte, Robert J

    2015-07-01

    The high incidence of non-anastomotic biliary strictures (NAS) after transplantation of livers from extended criteria donors is currently a major barrier to widespread use of these organs. This review provides an update on the most recent advances in the understanding of the etiology of NAS. These new insights give reason to believe that machine perfusion can reduce the incidence of NAS after transplantation by providing more protective effects on the biliary tree during preservation of the donor liver. An overview is presented regarding the different endpoints that have been used for assessment of biliary injury and function before and after transplantation, emphasizing on methods used during machine perfusion. The wide spectrum of different approaches to machine perfusion is discussed, including the many different combinations of techniques, temperatures and perfusates at varying time points. In addition, the current understanding of the effect of machine perfusion in relation to biliary injury is reviewed. Finally, we explore directions for future research such as the application of (pharmacological) strategies during machine perfusion to further improve preservation. We stress the great potential of machine perfusion to possibly expand the donor pool by reducing the incidence of NAS in extended criteria organs. Copyright © 2015 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

  17. A simplified subnormothermic machine perfusion system restores ischemically damaged liver grafts in a rat model of orthotopic liver transplantation

    Directory of Open Access Journals (Sweden)

    Berendsen Tim A

    2012-05-01

    Full Text Available Abstract Background Liver donor shortages stimulate the development of strategies that incorporate damaged organs into the donor pool. Herein we present a simplified machine perfusion system without the need for oxygen carriers or temperature control, which we validated in a model of orthotopic liver transplantation. Methods Rat livers were procured and subnormothermically perfused with supplemented Williams E medium for 3 hours, then transplanted into healthy recipients (Fresh-SNMP group. Outcome was compared with static cold stored organs (UW-Control group. In addition, a rat liver model of donation after cardiac death was adapted using a 60-minute warm ischemic period, after which the grafts were either transplanted directly (WI group or subnormothermically perfused and transplanted (WI-SNMP group. Results One-month survival was 100% in the Fresh-SNMP and UW-Control groups, 83.3% in the WI-SNMP group and 0% in the WI group. Clinical parameters, postoperative blood work and histology did not differ significantly between survivors. Conclusion This work demonstrates for the first time in an orthotopic transplantation model that ischemically damaged livers can be regenerated effectively using practical subnormothermic machine perfusion without oxygen carriers.

  18. Physiologic benefits of pulsatile perfusion during mechanical circulatory support for the treatment of acute and chronic heart failure in adults.

    Science.gov (United States)

    Guan, Yulong; Karkhanis, Tushar; Wang, Shigang; Rider, Alan; Koenig, Steven C; Slaughter, Mark S; El Banayosy, Aly; Undar, Akif

    2010-07-01

    A growing population experiencing heart failure (100,000 patients/year), combined with a shortage of donor organs (less than 2200 hearts/year), has led to increased and expanded use of mechanical circulatory support (MCS) devices. MCS devices have successfully improved clinical outcomes, which are comparable with heart transplantation and result in better 1-year survival than optimal medical management therapies. The quality of perfusion provided during MCS therapy may play an important role in patient outcomes. Despite demonstrated physiologic benefits of pulsatile perfusion, continued use or development of pulsatile MCS devices has been widely abandoned in favor of continuous flow pumps owing to the large size and adverse risks events in the former class, which pose issues of thrombogenic surfaces, percutaneous lead infection, and durability. Next-generation MCS device development should ideally implement designs that offer the benefits of rotary pump technology while providing the physiologic benefits of pulsatile end-organ perfusion.

  19. Ex Vivo Machine Perfusion in VCA with a Novel Oxygen Carrier System to Enhance Graft Preservation and Immunologic Outcomes

    Science.gov (United States)

    2016-12-01

    the utilization of this new preservation technology in composite tissue allotransplants (CTAs). The experiments were successful in showing the role...a new application of our technology previously and successfully performed in both porcine and human liver allografts. Machine Perfusion of the...current standard of care. Both groups were followed for 7 days. The VRAM grafts were biopsied on days 2, 4 and 7. An end-study necropsy was performed

  20. Applicability of Combined Use of Extracorporeal Support and Temperature-Controlled Machine Perfusion Preservation for Liver Procurement of Donors After Cardiac Death in Pigs.

    Science.gov (United States)

    Hagiwara, M; Matsuno, N; Meng, L T; Furukori, M; Watanabe, K; Shonaka, T; Imai, K; Obara, H; Nishikawa, Y; Furukawa, H

    2016-05-01

    The use of grafts from donors after cardiac death (DCD) would greatly contribute to the expansion of the donor organ pool. The objective of this study is to determine the benefits of extracorporeal membrane oxygenation (ECMO) and subnormothermic machine perfusion (MP) with rewarming in a large animal model of DCD liver. After cardiac arrest, the abdominal aorta and the inferior vena cava were cannulated and connected to an ECMO circuit. Porcine livers were perfused in situ with ECMO at 22°C for 60 minutes after 60 minutes of cardiac death. Then the livers were perfused for 4 hours by MP as a graft viability test. In group 1, non-in situ ECMO and grafts were preserved hypothermic MP. In group 2, non-in situ ECMO and grafts were preserved subnormothermic rewarming MP. In group 3, we used ECMO and subnormothermic rewarming MP. To assess potential methods and effect, effluent enzymes were measured. Portal vein and hepatic artery pressure during MP were evaluated. Effluent enzyme of AST, alanine aminotransferase and LDH as viability markers were significantly low (aspartate aminotransferase, 2899, 2292, and 972 IU/L; alanine aminotransferase, 134, 140, and 72 IU/L; and lactate dehydrogenase, 4354, 4455, and 1855 IU/L in each group, respectively). Portal vein and hepatic artery pressure during preservation came down smoothly in group 3 compared with group 1. The combined use of in situ subnormothermic ECMO and machine preservation with rewarming is more essential for the recovery and resuscitating function of DCD liver grafts. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Hypothermic oxygenated machine perfusion prevents arteriolonecrosis of the peribiliary plexus in pig livers donated after circulatory death.

    Directory of Open Access Journals (Sweden)

    Sanna Op den Dries

    Full Text Available BACKGROUND: Livers derived from donation after circulatory death (DCD are increasingly accepted for transplantation. However, DCD livers suffer additional donor warm ischemia, leading to biliary injury and more biliary complications after transplantation. It is unknown whether oxygenated machine perfusion results in better preservation of biliary epithelium and the peribiliary vasculature. We compared oxygenated hypothermic machine perfusion (HMP with static cold storage (SCS in a porcine DCD model. METHODS: After 30 min of cardiac arrest, livers were perfused in situ with HTK solution (4°C and preserved for 4 h by either SCS (n = 9 or oxygenated HMP (10°C; n = 9, using pressure-controlled arterial and portal venous perfusion. To simulate transplantation, livers were reperfused ex vivo at 37°C with oxygenated autologous blood. Bile duct injury and function were determined by biochemical and molecular markers, and a systematic histological scoring system. RESULTS: After reperfusion, arterial flow was higher in the HMP group, compared to SCS (251±28 vs 166±28 mL/min, respectively, after 1 hour of reperfusion; p = 0.003. Release of hepatocellular enzymes was significantly higher in the SCS group. Markers of biliary epithelial injury (biliary LDH, gamma-GT and function (biliary pH and bicarbonate, and biliary transporter expression were similar in the two groups. However, histology of bile ducts revealed significantly less arteriolonecrosis of the peribiliary vascular plexus in HMP preserved livers (>50% arteriolonecrosis was observed in 7 bile ducts of the SCS preserved livers versus only 1 bile duct of the HMP preserved livers; p = 0.024. CONCLUSIONS: Oxygenated HMP prevents arteriolonecrosis of the peribiliary vascular plexus of the bile ducts of DCD pig livers and results in higher arterial flow after reperfusion. Together this may contribute to better perfusion of the bile ducts, providing a potential advantage in the post

  2. Gaseous oxygen persufflation or oxygenated machine perfusion with Custodiol-N for long-term preservation of ischemic rat livers?

    Science.gov (United States)

    Stegemann, Judith; Hirner, Andreas; Rauen, Ursula; Minor, Thomas

    2009-02-01

    The aim of the present study was to evaluate the potential benefit of two different techniques for the provision of tissue aerobiosis upon cold preservation of marginal livers from non-heart beating donors using a recently developed improved preservation solution. Rat livers were harvested 30 min after cardiac arrest, flushed via the portal vein and cold-stored in HTK or modified HTK-solution (Custodiol-N) for 18 h at 4 degrees C. Other organs were flushed with Custodiol-N and subjected to aerobic conditions by either vascular systemic oxygen persufflation (VSOP) of the cold stored organ or hypothermic machine perfusion (HMP) with oxygenated Custodiol-N. Viability of the livers was assessed after 18 h of preservation by warm reperfusion in vitro for 120 min. Free radical mediated lipid peroxidation was significantly abrogated by the use of Custodiol-N in all groups compared with HTK. Custodiol-N improved enzyme leakage upon reperfusion and histological integrity, but had no impact on functional recovery (bile production, energetic status). However, VSOP further minimized enzyme release during the whole reperfusion period, led to a rise in hepatic bile production and enhanced recovery of energy charge (pVSOP. During the first 45min of reperfusion, leakage of ALT and LDH was also reduced by MP but deteriorated thereafter and became significantly higher compared to Custodiol-N at the end of the experiment. In conclusion, the results of the present study recommend the use of gaseous oxygen persufflation to improve tissue integrity and functional recovery of predamaged livers.

  3. Normothermic machine perfusion reduces bile duct injury and improves biliary epithelial function in rat donor livers.

    Science.gov (United States)

    Op den Dries, Sanna; Karimian, Negin; Westerkamp, Andrie C; Sutton, Michael E; Kuipers, Michiel; Wiersema-Buist, Janneke; Ottens, Petra J; Kuipers, Jeroen; Giepmans, Ben N; Leuvenink, Henri G D; Lisman, Ton; Porte, Robert J

    2016-07-01

    Bile duct injury may occur during liver procurement and transplantation, especially in livers from donation after circulatory death (DCD) donors. Normothermic machine perfusion (NMP) has been shown to reduce hepatic injury compared to static cold storage (SCS). However, it is unknown whether NMP provides better preservation of bile ducts. The aim of this study was to determine the impact of NMP on bile duct preservation in both DCD and non-DCD livers. DCD and non-DCD livers obtained from Lewis rats were preserved for 3 hours using either SCS or NMP, followed by 2 hours ex vivo reperfusion. Biomarkers of bile duct injury (gamma-glutamyltransferase and lactate dehydrogenase in bile) were lower in NMP-preserved livers compared to SCS-preserved livers. Biliary bicarbonate concentration, reflecting biliary epithelial function, was 2-fold higher in NMP-preserved livers (P < 0.01). In parallel with this, the pH of the bile was significantly higher in NMP-preserved livers (7.63 ± 0.02 and 7.74 ± 0.05 for non-DCD and DCD livers, respectively) compared with SCS-preserved livers (7.46 ± 0.02 and 7.49 ± 0.04 for non-DCD and DCD livers, respectively). Scanning and transmission electron microscopy of donor extrahepatic bile ducts demonstrated significantly decreased injury of the biliary epithelium of NMP-preserved donor livers (including the loss of lateral interdigitations and mitochondrial injury). Differences between NMP and SCS were most prominent in DCD livers. Compared to conventional SCS, NMP provides superior preservation of bile duct epithelial cell function and morphology, especially in DCD donor livers. By reducing biliary injury, NMP could have an important impact on the utilization of DCD livers and outcome after transplantation. Liver Transplantation 22 994-1005 2016 AASLD.

  4. Machine-learning based comparison of CT-perfusion maps and dual energy CT for pancreatic tumor detection

    Science.gov (United States)

    Goetz, Michael; Skornitzke, Stephan; Weber, Christian; Fritz, Franziska; Mayer, Philipp; Koell, Marco; Stiller, Wolfram; Maier-Hein, Klaus H.

    2016-03-01

    Perfusion CT is well-suited for diagnosis of pancreatic tumors but tends to be associated with a high radiation exposure. Dual-energy CT (DECT) might be an alternative to perfusion CT, offering correlating contrasts while being acquired at lower radiation doses. While previous studies compared intensities of Dual Energy iodine maps and CT-perfusion maps, no study has assessed the combined discriminative power of all information that can be generated from an acquisition of both functional imaging methods. We therefore propose the use of a machine learning algorithm for assessing the amount of information that becomes available by the combination of multiple images. For this, we train a classifier on both imaging methods, using a new approach that allows us to train only from small regions of interests (ROIs). This makes our study comparable to other - ROI-based analysis - and still allows comparing the ability of both classifiers to discriminate between healthy and tumorous tissue. We were able to train classifiers that yield DICE scores over 80% with both imaging methods. This indicates that Dual Energy Iodine maps might be used for diagnosis of pancreatic tumors instead of Perfusion CT, although the detection rate is lower. We also present tumor risk maps that visualize possible tumorous areas in an intuitive way and can be used during diagnosis as an additional information source.

  5. One or 4 h of "in-house" reconditioning by machine perfusion after cold storage improve reperfusion parameters in porcine kidneys.

    Science.gov (United States)

    Gallinat, Anja; Efferz, Patrik; Paul, Andreas; Minor, Thomas

    2014-11-01

    In-house machine perfusion after cold storage (hypothermic reconditioning) has been proposed as convenient tool to improve kidney graft function. This study investigated the role of machine perfusion duration for early reperfusion parameters in porcine kidneys. Kidney function after cold preservation (4 °C, 18 h) and subsequent reconditioning by one or 4 h of pulsatile, nonoxygenated hypothermic machine perfusion (HMP) was studied in an isolated kidney perfusion model in pigs (n = 6, respectively) and compared with simply cold-stored grafts (CS). Compared with CS alone, one or 4 h of subsequent HMP similarly and significantly improved renal flow and kidney function (clearance and sodium reabsorption) upon warm reperfusion, along with reduced perfusate concentrations of endothelin-1 and increased vascular release of nitric oxide. Molecular effects of HMP comprised a significant (vs CS) mRNA increase in the endothelial transcription factor KLF2 and lower expression of endothelin that were observed already at the end of one-hour HMP after CS. Reconditioning of cold-stored kidneys is possible, even if clinical logistics only permit one hour of therapy, while limited extension of the overall storage time by in-house machine perfusion might also allow for postponing of transplantation from night to early day work. © 2014 Steunstichting ESOT.

  6. Machine Perfusion of Porcine Livers with Oxygen-Carrying Solution Results in Reprogramming of Dynamic Inflammation Networks

    Directory of Open Access Journals (Sweden)

    David Sadowsky

    2016-11-01

    Full Text Available Background: Ex vivo machine perfusion (MP can better preserve organs for transplantation. We have recently reported on the first application of a MP protocol in which liver allografts were fully oxygenated, under dual pressures and subnormothermic conditions, with a new hemoglobin-based oxygen carrier solution specifically developed for ex vivo utilization. In those studies, MP improved organ function post-operatively and reduced inflammation in porcine livers. Herein, we sought to refine our knowledge regarding the impact of MP by defining dynamic networks of inflammation in both tissue and perfusate. Methods: Porcine liver allografts were preserved either with MP (n = 6 or with cold static preservation (CSP; n = 6, then transplanted orthotopically after 9 h of preservation. Fourteen inflammatory mediators were measured in both tissue and perfusate during liver preservation at multiple time points, and analyzed using Dynamic Bayesian Network (DyBN inference to define feedback interactions, as well as Dynamic Network Analysis (DyNA to define the time-dependent development of inflammation networks.Results: Network analyses of tissue and perfusate suggested an NLRP3 inflammasome-regulated response in both treatment groups, driven by the pro-inflammatory cytokine interleukin (IL-18 and the anti-inflammatory mediator IL-1 receptor antagonist (IL-1RA. Both DyBN and DyNA suggested a reduced role of IL-18 and increased role of IL-1RA with MP, along with increased liver damage with CSP. DyNA also suggested divergent progression of responses over the 9 h preservation time, with CSP leading to a stable pattern of IL-18-induced liver damage and MP leading to a resolution of the pro-inflammatory response. These results were consistent with prior clinical, biochemical, and histological findings after liver transplantation. Conclusion: Our results suggest that analysis of dynamic inflammation networks in the setting of liver preservation may identify novel

  7. Broiler chickens can benefit from machine learning: support vector machine analysis of observational epidemiological data.

    Science.gov (United States)

    Hepworth, Philip J; Nefedov, Alexey V; Muchnik, Ilya B; Morgan, Kenton L

    2012-08-07

    Machine-learning algorithms pervade our daily lives. In epidemiology, supervised machine learning has the potential for classification, diagnosis and risk factor identification. Here, we report the use of support vector machine learning to identify the features associated with hock burn on commercial broiler farms, using routinely collected farm management data. These data lend themselves to analysis using machine-learning techniques. Hock burn, dermatitis of the skin over the hock, is an important indicator of broiler health and welfare. Remarkably, this classifier can predict the occurrence of high hock burn prevalence with accuracy of 0.78 on unseen data, as measured by the area under the receiver operating characteristic curve. We also compare the results with those obtained by standard multi-variable logistic regression and suggest that this technique provides new insights into the data. This novel application of a machine-learning algorithm, embedded in poultry management systems could offer significant improvements in broiler health and welfare worldwide.

  8. Are minimized perfusion circuits the better heart lung machines? Final results of a prospective randomized multicentre study.

    Science.gov (United States)

    El-Essawi, A; Hajek, T; Skorpil, J; Böning, A; Sabol, F; Ostrovsky, Y; Hausmann, H; Harringer, W

    2011-11-01

    Minimized perfusion circuits (MPCs), although aiming at minimizing the adverse effects of cardiopulmonary bypass, have not yet gained popularity. This can be attributed to concerns regarding their safety, as well as lack of sufficient evidence of their benefit. Described is a randomized, multicentre study comparing the MPC - ROCsafeRX to standard cardiopulmonary bypass in patients undergoing elective coronary artery bypass grafting and/ or aortic valve replacement. Five hundred patients were included in the study (252 randomized to the ROCsafeRX group and 248 to standard cardiopulmonary bypass). Both groups were well matched for demographic characteristics and type of surgery. No operative mortality and no device-related complications were encountered. Transfusion requirement (333 ± 603 vs. 587 ± 1010 ml; p=0.001), incidence of atrial fibrillation (16.3% vs. 24.2%; p=0.03) and the incidence of major adverse events (9.1% vs. 16.5%; p=0.02) were all in favour of the MPC group. These results confirm both the safety and efficacy of the ROCsafeRX MPC for a large variety of cardiac patients. Minimized perfusion circuits should, therefore, play a greater role in daily practice so that as many patients as possible can benefit from their advantages.

  9. What is the benefit of CT-based attenuation correction in myocardial perfusion SPET?

    Science.gov (United States)

    Apostolopoulos, Dimitrios J; Savvopoulos, Christos

    2016-01-01

    In multimodality imaging, CT-derived transmission maps are used for attenuation correction (AC) of SPET or PET data. Regarding SPET myocardial perfusion imaging (MPI), however, the bene����t of CT-based AC (CT-AC) has been questioned. Although most attenuation-related artifacts are removed by this technique, new false defects may appear while some true perfusion abnormalities may be masked. The merits and the drawbacks of CT-AC in MPI SPET are reviewed and discussed in this editorial. In conclusion, CT-AC is most helpful in men, overweight in particular, and in those with low or low to intermediate pre-test probability of coronary artery disease (CAD). It is also useful for the evaluation of myocardial viability. In high-risk patients though, CT-AC may underestimate the presence or the extent of CAD. In any case, corrected and non-corrected images should be viewed side-by-side and both considered in the interpretation of the study.

  10. Successful Outflow Reconstruction to Salvage Traumatic Hepatic Vein-Caval Avulsion of a Normothermic Machine Ex-Situ Perfused Liver Graft: Case Report and Management of Organ Pool Challenges

    National Research Council Canada - National Science Library

    Athanasopoulos, Panagiotis G; Hadjittofi, Christopher; Dharmapala, Arinda Dinesh; Orti-Rodriguez, Rafael Jose; Ferro, Alessandra; Nasralla, David; Konstantinidou, Sofia K; Malagó, Massimo

    2016-01-01

    .... A 59-year-old woman with cirrhosis due to primary sclerosing cholangitis was offered an ex-situ machine perfused graft with unnoticed severe injury of the suprahepatic vasculature due to road traffic accident...

  11. Negative impact of prolonged cold storage time before machine perfusion preservation in donation after circulatory death kidney transplantation.

    Science.gov (United States)

    Paloyo, Siegfredo; Sageshima, Junichiro; Gaynor, Jeffrey J; Chen, Linda; Ciancio, Gaetano; Burke, George W

    2016-10-01

    Kidney grafts are often preserved initially in static cold storage (CS) and subsequently on hypothermic machine perfusion (MP). However, the impact of CS/MP time on transplant outcome remains unclear. We evaluated the effect of prolonged CS/MP time in a single-center retrospective cohort of 59 donation after circulatory death (DCD) and 177 matched donation after brain death (DBD) kidney-alone transplant recipients. With mean overall CS/MP times of 6.0 h/30.0 h, overall incidence of delayed graft function (DGF) was higher in DCD transplants (30.5%) than DBD transplants (7.3%, P time (P = 0.0002), male recipient (P = 0.02), and longer MP time (P = 0.08) were associated with higher DGF incidence. In evaluating the joint effects of donor type (DBD vs. DCD), CS time (time (time ≥36 h (P = 0.003) across each donor type and CS time stratum, whereas the unfavorable effect of CS time ≥6 h (P = 0.01) is primarily seen among DCD recipients. Prolonged cold ischemia time had no unfavorable effect on renal function or graft survival at 12mo post-transplant. Long CS/MP time detrimentally affects early DCD/DBD kidney transplant outcome when grafts were mainly preserved by MP; prolonged CS time before MP has a particularly negative impact in DCD kidney transplantation.

  12. Impact of Subnormothermic Machine Perfusion Preservation in Severely Steatotic Rat Livers: A Detailed Assessment in an Isolated Setting.

    Science.gov (United States)

    Okamura, Y; Hata, K; Tanaka, H; Hirao, H; Kubota, T; Inamoto, O; Kageyama, S; Tamaki, I; Yermek, N; Yoshikawa, J; Uemoto, S

    2016-11-10

    The current drastic shortage of donor organs has led to acceptance of extended-criteria donors for transplantation, despite higher risk of primary nonfunction. Here, we report the impact of subnormothermic machine perfusion (SMP) preservation on the protection of >50% macrosteatotic livers. Dietary hepatic steatosis was induced in Wistar rats via 2-day fasting and subsequent 3-day re-feeding with a fat-free, carbohydrate-rich diet. This protocol induces 50-60% macrovesicular steatosis, which should be discarded when preserved via cold storage (CS). The fatty livers were retrieved and preserved for 4 h using either CS in histidine-tryptophan-ketoglutarate or SMP in polysol solution. Graft functional integrity was evaluated via oxygenated ex vivo reperfusion for 2 h at 37°C. SMP resulted in significant reductions in not only parenchymal alanine aminotransferase (p protein-1 (p disadvantages associated with steatosis. SMP could protect 50-60% macrosteatotic livers from preservation/reperfusion injury, and may thus represent a new means for expanding available donor pools.

  13. Comparison of Aerobic Preservation by Venous Systemic Oxygen Persufflation or Oxygenated Machine Perfusion of Warm-Ischemia-Damaged Porcine Kidneys.

    Science.gov (United States)

    Kalenski, Julia; Mancina, Elina; Paschenda, Pascal; Beckers, Christian; Bleilevens, Christian; Tóthová, Ľubomíra; Boor, Peter; Gross, Dominik; Tolba, René H; Doorschodt, Benedict M

    2016-01-01

    The global shortage of donor organs for transplantation has necessitated the expansion of the organ pool through increased use of organs from less ideal donors. Venous systemic oxygen persufflation (VSOP) and oxygenated machine perfusion (OMP) have previously demonstrated beneficial results compared to cold storage (CS) in the preservation of warm-ischemia-damaged kidney grafts. The aim of this study was to compare the efficacy of VSOP and OMP for the preservation of warm-ischemia-damaged porcine kidneys using the recently introduced Ecosol preservation solution compared to CS using Ecosol or histidine-tryptophan-ketoglutarate solution (HTK). Kidneys from German Landrace pigs (n = 5/group) were retrieved and washed out with either Ecosol or HTK after 45 min of clamping of the renal pedicle. As controls, kidneys without warm ischemia, cold stored for 24 h in HTK, were employed. Following 24 h of preservation by VSOP, OMP, CS-Ecosol, or CS-HTK, renal function and damage were assessed during 1 h using the isolated perfused porcine kidney model. During reperfusion, urine production was significantly higher in the VSOP and OMP groups than in the CS-HTK group; however, only VSOP could demonstrate lower urine protein concentrations and fractional excretion of sodium, which did not differ from the non-warm-ischemia-damaged control group. VSOP, CS-Ecosol, and controls showed better maintenance of the acid-base balance than CS-HTK. Reduced lipid peroxidation, as reflected in postreperfusion tissue thiobarbituric acid-reactive substance levels, was observed in the VSOP group compared to the OMP group, and the VSOP and CS-Ecosol groups had concentrations similar to the controls. The ratio of reduced to oxidized glutathione was higher in the VSOP, OMP, and CS-Ecosol groups than in the CS-HTK group and controls, with a higher ratio in the VSOP than in the OMP group. VSOP was associated with mitigation of oxidative stress in comparison to OMP and CS. Preservation of warm

  14. Role of perfusion medium, oxygen and rheology for endoplasmic reticulum stress-induced cell death after hypothermic machine preservation of the liver.

    Science.gov (United States)

    Manekeller, Steffen; Schuppius, Andrea; Stegemann, Judith; Hirner, Andreas; Minor, Thomas

    2008-02-01

    Recently, the endoplasmic reticulum (ER) has been disclosed as subcellular target reactive to ischaemia/reperfusion and possibly influenced by hypothermic machine preservation. Here, the respective role of perfusate, perfusion itself, and the effect of continuous oxygenation to trigger ER-stress in the graft should be investigated. Livers were retrieved 30 min after cardiac arrest of male Wistar rats and preserved by cold storage (CS) in histidine-tryptophan-ketoglutarate (HTK) for 18 h at 4 degrees C. Other organs were subjected to aerobic conditions either by oxygenated machine perfusion with HTK (MP-HTK) or Belzer solution (MP-Belzer) at 4 degrees C or by venous insufflation of gaseous oxygen during cold storage (VSOP). Viability of livers was evaluated upon reperfusion in vitro according to previously validated techniques for 120 min at 37 degrees C. Oxygenation during preservation (MP-HTK, MP-Belzer or VSOP) concordantly improved functional recovery (bile flow, ammonia clearance), reduced parenchymal enzyme leakage and histological signs of necrosis and significantly attenuated mitochondrial induction of apoptosis (cleavage of caspase 9) compared to CS. However, MP with either medium produced about 500% elevated protein expression of CHOP/GADD153, suggesting pro-apoptotic ER-stress responses, paralleled by a significant elevation of caspase-12 enzyme activity compared to CS or VSOP. Although MP also promoted a slight (20%) induction of the cytoprotective ER-protein Bax inhibitor protein (BI-1), prevailing of proapoptotic reactions was seen by increased cleavage of caspase-3 and poly (ADP-Ribase)-polymerase (PARP) in both MP-groups. Endoplasmic stress activation is conjectured a specific side effect of long-term machine preservation irrespective of the medium, actually promoting cellular apoptosis via activation of caspase-12. The simple insufflation of gaseous O2 may be considered a feasible alternative, apparently indifferent to the endoplasmic reticulum.

  15. An ex vivo comparison of adenosine and lidocaine solution and University of Wisconsin solution for hypothermic machine perfusion of porcine kidneys: potential for development.

    Science.gov (United States)

    Hamaoui, Karim; Aftab, Adeel; Gowers, Sally; Boutelle, Martyn; Cook, Terry; Rudd, Donna; Dobson, Geoffrey P; Papalois, Vassilios

    2017-02-01

    The optimal hypothermic machine perfusion (HMP) solution has not yet been developed. An adenosine and lidocaine (AL) solution has been shown to be protective in cardiac preservation. The aim of the present study was to examine a modified AL solution with low Ca(2+), 16 mM Mg(2+), and 4% albumin on kidney preservation compared with University Wisconsin solution (UW). Twenty donation of organs after cardiac death porcine kidneys underwent HMP for 10 h (AL, n = 10; UW, n = 10) and then 2 h of normothermic reperfusion. Perfusion dynamics, functional parameters, histology, and real-time microdialysis were used to assess kidney responses and viability. During HMP, modified AL-perfused kidneys maintained higher flow rates (21.5 versus 17.9 mL/min/100 g, P = 0.01), with perfusion flow index during the first 3 h 25% greater than with UW (AL = 0.50 ± 0.2, UW = 0.40 ± 0.17 mL/min/100 g/mmHg; P = 0.03), followed by an increase in UW kidneys which was not significantly different to AL over the remaining 7 h (0.54 versus 0.55 mL/min/100 g/mmHg, respectively). During warm reperfusion, there were no significant differences between the two HMP groups in creatinine clearance, oxygen, and glucose consumption between groups. Modified AL kidneys had significantly lower perfusate lactates (3.1 versus 4.1 mmol/L, P = 0.04) during reperfusion and lower cortical lactate levels (AL = 0.66 ± 0.31, UW = 0.89 ± 0.53 mM, P = 0.33). Histology showed similar degrees of reperfusion injury. We conclude that HMP with modified AL solution showed improved perfusion compared with UW and lower perfusate lactate levels during warm reperfusion. Further modification of the AL composition is warranted and may lead to more rapid kidney stabilization and improved graft viability assessment, potentially expanding donor pools. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Gradual Rewarming with Gradual Increase in Pressure during Machine Perfusion after Cold Static Preservation Reduces Kidney Ischemia Reperfusion Injury.

    Directory of Open Access Journals (Sweden)

    Paria Mahboub

    Full Text Available In this study we evaluated whether gradual rewarming after the period of cold ischemia would improve organ quality in an Isolated Perfused Kidney Model. Left rat kidneys were statically cold stored in University of Wisconsin solution for 24 hours at 4°C. After cold storage kidneys were rewarmed in one of three ways: perfusion at body temperature (38°C, or rewarmed gradually from 10°C to 38°C with stabilization at 10°C for 30 min and rewarmed gradually from 10°C to 38°C with stabilization at 25°C for 30 min. In the gradual rewarming groups the pressure was increased stepwise to 40 mmHg at 10°C and 70 mmHg at 25°C to counteract for vasodilatation leading to low perfusate flows. Renal function parameters and injury biomarkers were measured in perfusate and urine samples. Increases in injury biomarkers such as aspartate transaminase and lactate dehydrogenase in the perfusate were lower in the gradual rewarming groups versus the control group. Sodium re-absorption was improved in the gradual rewarming groups and reached significance in the 25°C group after ninety minutes of perfusion. HSP-70, ICAM-1, VCAM-1 mRNA expressions were decreased in the 10°C and 25°C groups. Based on the data kidneys that underwent gradual rewarming suffered less renal parenchymal, tubular injury and showed better endothelial preservation. Renal function improved in the gradual rewarming groups versus the control group.

  17. Designing Green Stormwater Infrastructure for Hydrologic and Human Benefits: An Image Based Machine Learning Approach

    Science.gov (United States)

    Rai, A.; Minsker, B. S.

    2014-12-01

    Urbanization over the last century has degraded our natural water resources by increasing storm-water runoff, reducing nutrient retention, and creating poor ecosystem health downstream. The loss of tree canopy and expansion of impervious area and storm sewer systems have significantly decreased infiltration and evapotranspiration, increased stream-flow velocities, and increased flood risk. These problems have brought increasing attention to catchment-wide implementation of green infrastructure (e.g., decentralized green storm water management practices such as bioswales, rain gardens, permeable pavements, tree box filters, cisterns, urban wetlands, urban forests, stream buffers, and green roofs) to replace or supplement conventional storm water management practices and create more sustainable urban water systems. Current green infrastructure (GI) practice aims at mitigating the negative effects of urbanization by restoring pre-development hydrology and ultimately addressing water quality issues at an urban catchment scale. The benefits of green infrastructure extend well beyond local storm water management, as urban green spaces are also major contributors to human health. Considerable research in the psychological sciences have shown significant human health benefits from appropriately designed green spaces, yet impacts on human wellbeing have not yet been formally considered in GI design frameworks. This research is developing a novel computational green infrastructure (GI) design framework that integrates hydrologic requirements with criteria for human wellbeing. A supervised machine learning model is created to identify specific patterns in urban green spaces that promote human wellbeing; the model is linked to RHESSYS model to evaluate GI designs in terms of both hydrologic and human health benefits. An application of the models to Dead Run Watershed in Baltimore showed that image mining methods were able to capture key elements of human preferences that could

  18. Ex Vivo Machine Perfusion in CTA with a Novel Oxygen Carrier System to Enhance Graft Preservation and Immunologic Outcomes

    Science.gov (United States)

    2015-10-01

    adipose and muscular tissues. The control group showed early contraction bands within the muscular tissue within the initial period (4 hours). These...Enhance Graft Preservation and Immunologic Outcomes” PRINCIPAL INVESTIGATOR: Paulo Fontes, MD CONTRACTING ORGANIZATION: University of Pittsburgh...Perfusion in CTA with a Novel Oxygen Carrier System to Enhance Graft 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-13-2-0061 5c. PROGRAM ELEMENT

  19. Metabolic Characteristics of Human Hearts Preserved for 12 Hours by Static Storage, Antegrade Perfusion or Retrograde Coronary Sinus Perfusion

    Science.gov (United States)

    Cobert, Michael L.; Merritt, Matthew E.; West, LaShondra M.; Ayers, Colby; Jessen, Michael E.; Peltz, Matthias

    2014-01-01

    Objective(s) Machine perfusion of donor hearts is a promising strategy to increase the donor pool. Antegrade perfusion is effective but can lead to aortic valve incompetence and non-nutrient flow. Experience with retrograde coronary sinus perfusion of donor hearts has been limited. We tested the hypothesis that retrograde perfusion could support myocardial metabolism over an extended donor ischemic interval. Methods Human hearts from donors rejected or not offered for transplantation were preserved for 12 hours in University of Wisconsin Machine Perfusion Solution by: 1. Static hypothermic storage 2. Hypothermic antegrade machine perfusion or 3. Hypothermic retrograde machine perfusion. Myocardial oxygen consumption (MVO2), and lactate accumulation were measured. Ventricular tissue was collected for proton (1H) and phosphorus-31 (31P) magnetic resonance spectroscopy (MRS) to evaluate the metabolic state of the myocardium. Myocardial water content was determined at end-experiment. Results Stable perfusion parameters were maintained throughout the perfusion period with both perfusion techniques. Lactate/alanine ratios were lower in perfused hearts compared to static hearts (pperfused groups. High energy phosphates were better preserved in both perfused groups (pperfused (80.2±.8%) compared to both antegrade perfused (76.6±.8%, p=.02) and static storage hearts (76.7±1%, p=.02). Conclusions In conclusion, machine perfusion by either the antegrade or the retrograde technique can support myocardial metabolism over long intervals. Machine perfusion appears promising for long term preservation of human donor hearts. PMID:24642559

  20. Machine Translation

    Institute of Scientific and Technical Information of China (English)

    张严心

    2015-01-01

    As a kind of ancillary translation tool, Machine Translation has been paid increasing attention to and received different kinds of study by a great deal of researchers and scholars for a long time. To know the definition of Machine Translation and to analyse its benefits and problems are significant for translators in order to make good use of Machine Translation, and helpful to develop and consummate Machine Translation Systems in the future.

  1. Renal perfusion scintiscan

    Science.gov (United States)

    Renal perfusion scintigraphy; Radionuclide renal perfusion scan; Perfusion scintiscan - renal; Scintiscan - renal perfusion ... supply the kidneys. This is a condition called renal artery stenosis. Significant renal artery stenosis may be ...

  2. 电子产品自动灌胶机PLC控制系统的研究%Research on PLC Control System in Electronic Products Automatic Glue Perfusion Machine

    Institute of Scientific and Technical Information of China (English)

    李光兰

    2013-01-01

    Recently,the electronic information industry is developing rapidly,electronic products have been widely used in various fields.Increasingly high demand for electronic products packaging insulation,vibration-proof and waterproof performance.In the meanwhile,the capacity requirement of control system in glue perfusion equipment also increasingly higher.A technology based on PLC control electronics automatic glue perfusion machine system was designed.This system has the characteristics of less investment,easy to operate,speed fast,precise control and high quality etc.It plays a significance effort to improve the product efficiency and reduce the cost of production.%目前电子信息产业正在高速发展,电子产品已在各个领域中广泛应用,对电子产品封装的绝缘、防振、防水性能的要求越来越高,对灌胶设备的自动化控制系统的能力要求也越来越高.我国多数电子产品生产企业在灌封胶时,大多处于手工操作或半自动化控制阶段,对于批量生产的企业来讲工作效率低,耗费人力大,精度差.研究了一种基于PLC控制的电子产品自动灌胶系统,该系统具有投资少、操作简单、速度快、控制精确与质量高等特点,对提高企业的生产效率、降低生产成本具有重要意义.

  3. Pulmonary ventilation/perfusion scan

    Science.gov (United States)

    V/Q scan; Ventilation/perfusion scan; Lung ventilation/perfusion scan ... A pulmonary ventilation/perfusion scan is actually two tests. They may be done separately or together. During the perfusion scan, a health care provider injects ...

  4. 离体猪肝机械灌注模型的建立及其在高强度聚焦超声研究中的意义%Establishment of an isolated porcine liver machine perfusion model for high-intensity focused ultrasound studies

    Institute of Scientific and Technical Information of China (English)

    卜锐; 邹建中; 银丽; 伍烽; 孟世和; 刘芳; 赵欣; 焦娇; 杨含

    2012-01-01

    Objective To explore the feasibility of establishing an isolated porcine liver machine perfusion model and assess its value in high-intensity focused ultrasound studies. Methods Twenty-one isolated porcine livers were perfused with autologous blood for 4 h through dual vessels (portal vein and hepatic artery) cannulation using an extracorporeal circulation machine under a subnormothermic perfusion condition. The perfusion model was assessed by monitoring the liver color, texture, liver weight gain, hemodynamic parameters, color Doppler flow imaging, bile output and histopathology. Results Nineteen isolated porcine livers were successfully cannulated with dual vessels, and failure of hepatic artery intubation occurred in two porcine livers. After machine perfusion for i h, the isolated livers maintained a soft texture with stable hemodynamic levels within relative normal physiological ranges. The bile output was more than 3 ml/h within the initial 3 h of perfusion. Histopathological examination demonstrated no morphological or structural changes of the liver tissues. Conclusion The isolated porcine liver perfusion model is stable and feasible, and can be used for high-intensity focused ultrasound studies.%目的 探讨建立离体猪肝机械灌注模型的可行性及在高强度聚焦超声(HIFU)基础研究中的意义.方法 对屠宰场获取的21例猪肝以双血管(经门静脉和肝动脉)、自体血灌注液、体外循环机离体灌注4h,监测肝脏的颜色、质地、质量、血流动力学(流量及压力)、彩色多普勒超声影像、胆汁分泌量、组织病理学变化以评价灌注效果.结果 19例猪肝同时经门静脉和肝动脉插管成功,2例肝动脉插管失败.灌注后4h肝脏质地柔软、血流动力学各参数稳定且保持在相对正常的生理范围内,灌注3h内胆汁分泌量>3 ml/h,组织病理学显示脏组织总体无形态结构的改变.结论 离体猪肝机械灌注模型是稳定、可行的,能满

  5. Current perspectives in transplant medicine: hypothermic oxygenated perfusion

    Directory of Open Access Journals (Sweden)

    Michel SG

    2016-11-01

    Full Text Available Sebastian G Michel,1 Joren C Madsen2,3 1Department of Cardiac Surgery, Ludwig-Maximilians-University, Munich, Germany; 2Department of Surgery, Center for Transplantation Sciences, 3Division of Cardiac Surgery, Department of Surgery, Massachusetts General Hospital, Boston, MA, USA Abstract: The purpose of this review was to provide an update on hypothermic oxygenated perfusion as a preservation technique for whole organ allografts. Clinical and experimental data in heart, lung, liver, kidney, and pancreas/islet transplantation are summarized with a special emphasis on marginal donors and donation after circulatory death. The rationale behind hypothermic machine perfusion as well as its advantages and disadvantages compared to conventional cold storage and the competing technique, normothermic machine perfusion, are reviewed. Keywords: organ transplantation, organ preservation, hypothermic perfusion

  6. Cochlear perfusion with a viscous fluid.

    Science.gov (United States)

    Wang, Yi; Olson, Elizabeth S

    2016-07-01

    The flow of viscous fluid in the cochlea induces shear forces, which could provide benefit in clinical practice, for example to guide cochlear implant insertion or produce static pressure to the cochlear partition or wall. From a research standpoint, studying the effects of a viscous fluid in the cochlea provides data for better understanding cochlear fluid mechanics. However, cochlear perfusion with a viscous fluid may damage the cochlea. In this work we studied the physiological and anatomical effects of perfusing the cochlea with a viscous fluid. Gerbil cochleae were perfused at a rate of 2.4 μL/min with artificial perilymph (AP) and sodium hyaluronate (Healon, HA) in four different concentrations (0.0625%, 0.125%, 0.25%, 0.5%). The different HA concentrations were applied either sequentially in the same cochlea or individually in different cochleae. The perfusion fluid entered from the round window and was withdrawn from basal scala vestibuli, in order to perfuse the entire perilymphatic space. Compound action potentials (CAP) were measured after each perfusion. After perfusion with increasing concentrations of HA in the order of increasing viscosity, the CAP thresholds generally increased. The threshold elevation after AP and 0.0625% HA perfusion was small or almost zero, and the 0.125% HA was a borderline case, while the higher concentrations significantly elevated CAP thresholds. Histology of the cochleae perfused with the 0.0625% HA showed an intact Reissner's membrane (RM), while in cochleae perfused with 0.125% and 0.25% HA RM was torn. Thus, the CAP threshold elevation was likely due to the broken RM, likely caused by the shear stress produced by the flow of the viscous fluid. Our results and analysis indicate that the cochlea can sustain, without a significant CAP threshold shift, up to a 1.5 Pa shear stress. Beside these finding, in the 0.125% and 0.25% HA perfusion cases, a temporary CAP threshold shift was observed, perhaps due to the presence and

  7. Cochlear perfusion with a viscous fluid

    Science.gov (United States)

    Wang, Yi; Olson, Elizabeth S.

    2016-01-01

    The flow of viscous fluid in the cochlea induces shear forces, which could provide benefit in clinical practice, for example to guide cochlear implant insertion or produce static pressure to the cochlear partition or wall. From a research standpoint, studying the effects of a viscous fluid in the cochlea provides data for better understanding cochlear fluid mechanics. However, cochlear perfusion with a viscous fluid may damage the cochlea. In this work we studied the physiological and anatomical effects of perfusing the cochlea with a viscous fluid. Gerbil cochleae were perfused at a rate of 2.4 μL/min with artificial perilymph (AP) and sodium hyaluronate (Healon, HA) in four different concentrations (0.0625%, 0.125%, 0.25%, 0.5%). The different HA concentrations were applied either sequentially in the same cochlea or individually in different cochleae. The perfusion fluid entered from the round window and was withdrawnfrom basal scala vestibuli, in order to perfuse the entire perilymphatic space. Compound action potentials (CAP) were measured after each perfusion. After perfusion with increasing concentrations of HA in the order of increasing viscosity, the CAP thresholds generally increased. The threshold elevation after AP and 0.0625% HA perfusion was small or almost zero, and the 0.125% HA was a borderline case, while the higher concentrations significantly elevated CAP thresholds. Histology of the cochleae perfused with the 0.0625% HA showed an intact Reissner’s membrane, while in cochleae perfused with 0.125% and 0.25% HA Reissner’s membrane (RM) was torn. Thus, the CAP threshold elevation was likely due to the broken of RM, which likely caused by the shear stress produced by the flow of the viscous fluid. Our results and analysis indicate that the cochlea can sustain, without a significant CAP threshold shift, up to a 1.5 Pa shear stress. Beside these finding, in the 0.125% and 0.25% HA perfusion cases, a temporary CAP threshold shift was observed

  8. Hydroxyethyl starch solution for extracorporeal tissue perfusion.

    Science.gov (United States)

    Taeger, Christian D; Friedrich, Oliver; Drechsler, Caroline; Weigand, Annika; Hobe, Frieder; Geppert, Carol I; Münch, Frank; Birkholz, Torsten; Buchholz, Rainer; Horch, Raymund E; Präbst, Konstantin

    2016-11-04

    In the field of free flap transfer in reconstructive surgery, the trans- or replanted tissue always undergoes cell damage during ischemia to a more or less strong extent. In previous studies we already showed that conserving muscle transplants by means of extracorporeal perfusion over a period of 6 hours by using a crystalloid solution for perfusion. However, we observed significant edema formation. In this study we aimed at reducing the edema formation by using an iso-oncotic colloid as perfusion solution. This way we wanted to evaluate a possible new application of hydroxyl-ethyl starch in an extracorporeal setup to exploit potential benefits of the colloid.Examined parameters include the muscles' functionality with external field stimulation, histological examination and edema formation. Perfused muscles showed a statistically significant higher ability to exert force compared to nonperfused ones. These findings can be confirmed using Annexin V as marker for cell damage, as perfusion of muscle tissue limits damage significantly compared to nonperfused tissue. Substituting the electrolyte perfusion solution with a colloidal one shows the tendency to reduce the edema formation however without statistical significance.

  9. Abdominal perfusion computed tomography.

    Science.gov (United States)

    Ogul, Hayri; Bayraktutan, Ummugulsum; Kizrak, Yesim; Pirimoglu, Berhan; Yuceler, Zeynep; Sagsoz, M Erdem; Yilmaz, Omer; Aydinli, Bulent; Ozturk, Gurkan; Kantarci, Mecit

    2013-02-01

    The purpose of this article is to provide an up to date review on the spectrum of applications of perfusion computed tomography (CT) in the abdomen. New imaging techniques have been developed with the objective of obtaining a structural and functional analysis of different organs. Recently, perfusion CT has aroused the interest of many researchers who are studying the applicability of imaging modalities in the evaluation of abdominal organs and diseases. Per-fusion CT enables fast, non-invasive imaging of the tumor vascular physiology. Moreover, it can act as an in vivo biomarker of tumor-related angiogenesis.

  10. The benefits of prone SPECT myocardial perfusion imaging in reducing both artifact defects and patient radiation exposure; Beneficio da aquisicao de imagem na posicao Prona em perfusao miocardica com SPECT para reducao de artefatos e exposicao do paciente a radiacao

    Energy Technology Data Exchange (ETDEWEB)

    Stathaki, Maria; Koukouraki, Sophia; Papadaki, Emmanouela; Tsaroucha, Angeliki; Karkavitsas, Nikolaos, E-mail: mariast_cha@yahoo.gr [Department of Nuclear Medicine, University Hospital of Heraklion, Crete (Greece)

    2015-10-15

    Background: Prone imaging has been demonstrated to minimize diaphragmatic and breast tissue attenuation. Objectives: To determine the role of prone imaging on the reduction of unnecessary rest perfusion studies and coronary angiographies performed, thus decreasing investigation time and radiation exposure. Methods: We examined 139 patients, 120 with an inferior wall and 19 with an anterior wall perfusion defect that might represented attenuation artifact. Post-stress images were acquired in both the supine and prone position. Coronary angiography was used as the 'gold standard' for evaluating coronary artery patency. The study was terminated and rest imaging was obviated in the presence of complete improvement of the defect in the prone position. Quantitative interpretation was performed. Results were compared with clinical data and coronary angiographic findings. Results: Prone acquisition correctly revealed defect improvement in 89 patients (89/120) with inferior wall and 12 patients (12/19) with anterior wall attenuation artifact. Quantitative analysis demonstrated statistically significant difference in the mean summed stress scores (SSS) of supine and mean SSS of prone studies in patients with disappearing inferior wall defect in the prone position and patent right coronary artery (true negative results). The mean difference between SSS in supine and in prone position was higher with disappearing than with remaining defects. Conclusion: Technetium-99m (Tc-99m) tetrofosmin myocardial perfusion imaging with the patient in the prone position overcomes soft tissue attenuation; moreover it provides an inexpensive, accurate approach to limit the number of unnecessary rest perfusion studies and coronary angiographies performed. (author)

  11. Perfusion Linearity and Its Applications

    CERN Document Server

    Pianykh, Oleg

    2010-01-01

    Perfusion analysis computes blood flow parameters (blood volume, blood flow, mean transit time) from the observed flow of contrast agent, passing through the patient's vascular system. Perfusion deconvolution has been widely accepted as the principal numerical tool for perfusion analysis, and is used routinely in clinical applications. This extensive use of perfusion in clinical decision-making makes numerical stability and robustness of perfusion computations vital for accurate diagnostics and patient safety. The main goal of this paper is to propose a novel approach for validating numerical properties of perfusion algorithms. The approach is based on Perfusion Linearity Property (PLP), which we find in perfusion deconvolution, as well as in many other perfusion techniques. PLP allows one to study perfusion values as weighted averages of the original imaging data. This, in turn, uncovers hidden problems with the existing deconvolution techniques, and may be used to suggest more reliable computational approac...

  12. Dutch perfusion incident survey.

    Science.gov (United States)

    Groenenberg, Ingrid; Weerwind, Patrick W; Everts, Peter A M; Maessen, Jos G

    2010-09-01

    Cardiopulmonary bypass procedures remain complex, involving many potential risks. Therefore, a nationwide retrospective study was conducted to gain insight into the number of incidents and accidents in Dutch adult perfusion practice. An anonymous postal survey (85 questions about hardware, disposables, fluids and medication, air emboli, anticoagulation, practice, and safety measures) was sent to all Dutch perfusionists involved in adult cardiovascular perfusion during 2006 and 2007. To guarantee complete anonymity, respondents were asked to return the survey to a notary who discarded personal information. The net response rate was 72% and covered 23,500 perfusions. Individual respondents performed 240 ± 103 perfusions during the 2-year study period and had 13.8 ± 8.7 years of practical experience. The incident rate was 1 per 15.6 perfusions and the adverse event rate was 1 per 1,236 perfusions. The three most reported incidents were: (1) persistent inability to raise the activated coagulation time above 400s during perfusion (184 incidents); (2) an allergic or anaphylactic reaction to drugs, fluids, or blood products (114 incidents); and (3) clotting formation in the extracorporeal circuit (74 incidents). Furthermore, pre-bypass safety measures showed no statistically significant association with the reported incidents. In comparison with data from the recent literature, the reported number of incidents is high. Nevertheless, the adverse outcome rate is well matched to other published surveys. The relatively high response rate conveys the impression that the Dutch perfusionist is vigilant and willing to report incidents. Hence, a web-based Dutch perfusion incident registration system is recommended.

  13. When Machines Design Machines!

    DEFF Research Database (Denmark)

    2011-01-01

    Until recently we were the sole designers, alone in the driving seat making all the decisions. But, we have created a world of complexity way beyond human ability to understand, control, and govern. Machines now do more trades than humans on stock markets, they control our power, water, gas...... and food supplies, manage our elevators, microclimates, automobiles and transport systems, and manufacture almost everything. It should come as no surprise that machines are now designing machines. The chips that power our computers and mobile phones, the robots and commercial processing plants on which we...... depend, all are now largely designed by machines. So what of us - will be totally usurped, or are we looking at a new symbiosis with human and artificial intelligences combined to realise the best outcomes possible. In most respects we have no choice! Human abilities alone cannot solve any of the major...

  14. Warm vs. cold perfusion techniques to rescue rodent liver grafts.

    Science.gov (United States)

    Schlegel, Andrea; Kron, Philipp; Graf, Rolf; Dutkowski, Philipp; Clavien, Pierre-Alain

    2014-12-01

    A variety of liver perfusion techniques have been proposed to protect liver grafts prior to implantation. We compared hypothermic and normothermic oxygenated perfusion techniques in a rat liver transplant model, using higher risk grafts obtained after cardiac arrest (DCD). Rat livers were subjected to 30 or 60 min in situ warm ischemia, without application of heparin. Livers were excised and stored for 4 h at 4°C, mimicking DCD organ procurement, followed by conventional organ transport. In experimental groups, DCD liver grafts received a 4 h normothermic oxygenated perfusion through the portal vein and the hepatic artery instead of cold storage. The perfusate consisted of either full blood or leukocyte-depleted blood (normothermic groups). Other livers underwent hypothermic oxygenated perfusion (HOPE) for 1 h after warm ischemia and 4 h cold storage (HOPE group). Liver injury was assessed during machine perfusion and after isolated liver reperfusion, and by orthotopic liver transplantation (OLT). DCD livers, subjected to normothermic perfusion, disclosed reduced injury and improved survival compared to cold storage after limited warm ischemia of 30 min (70%; 7/10), but failed to protect from lethal injury in grafts exposed to 60 min warm ischemia (0%; 0/10). This finding was consistent with Kupffer and endothelial cell activation in cold stored and normothermic perfused livers. In contrast, HOPE protected from hepatocyte and non-parenchymal cell injury and led to 90% (9/10) and 63% (5/8) animal survival after 30 and 60 min of donor warm ischemia, respectively. This is the first evidence that HOPE is superior to normothermic oxygenated perfusion in a clinically relevant model through modulation of the innate immunity and endothelial cell activation. Copyright © 2014 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

  15. Perfusion based cell culture chips

    DEFF Research Database (Denmark)

    Heiskanen, Arto; Emnéus, Jenny; Dufva, Martin

    2010-01-01

    Performing cell culture in miniaturized perfusion chambers gives possibilities to experiment with cells under near in vivo like conditions. In contrast to traditional batch cultures, miniaturized perfusion systems provide precise control of medium composition, long term unattended cultures and ti...

  16. Arterial and portal venous liver perfusion using selective spin labelling MRI

    Energy Technology Data Exchange (ETDEWEB)

    Schalkx, Hanke J.; Petersen, Esben T.; Veldhuis, Wouter B.; Leeuwen, Maarten S. van; Bosch, Maurice A.A.J. van den [University Medical Center Utrecht, Department of Radiology, HP E.01.132, Postbus 85500, Utrecht (Netherlands); Peters, Nicky H.G.M. [Atrium Medical Center Parkstad, Department of Radiology, Heerlen (Netherlands); Pluim, Josien P.W.; Stralen, Marijn van [University Medical Center Utrecht, Image Sciences Institute, Utrecht (Netherlands)

    2015-06-01

    To investigate the feasibility of selective arterial and portal venous liver perfusion imaging with spin labelling (SL) MRI, allowing separate labelling of each blood supply. The portal venous perfusion was assessed with a pulsed EPISTAR technique and the arterial perfusion with a pseudo-continuous sequence. To explore precision and reproducibility, portal venous and arterial perfusion were separately quantified in 12 healthy volunteers pre- and postprandially (before and after meal intake). In a subgroup of 6 volunteers, the accuracy of the absolute portal perfusion and its relative postprandial change were compared with MRI flow measurements of the portal vein. The portal venous perfusion significantly increased from 63 ± 22 ml/100g/min preprandially to 132 ± 42 ml/100g/min postprandially. The arterial perfusion was lower with 35 ± 22 preprandially and 22 ± 30 ml/100g/min postprandially. The pre- and postprandial portal perfusion using SL correlated well with flow-based perfusion (r{sup 2} = 0.71). Moreover, postprandial perfusion change correlated well between SL- and flow-based quantification (r{sup 2} = 0.77). The SL results are in range with literature values. Selective spin labelling MRI of the portal venous and arterial blood supply successfully quantified liver perfusion. This non-invasive technique provides specific arterial and portal venous perfusion imaging and could benefit clinical settings where contrast agents are contraindicated. (orig.)

  17. Continuous plasma perfusion of dual cartridges in series: rationale and early clinical experience.

    Science.gov (United States)

    Sun, Liang; Yan, Peng-Bo; Zhang, Yu-Hua; Wei, Lu-Qing; Li, Guo-Qiang

    2016-12-01

    To improve the efficiency of plasma perfusion on eliminating plasma paraquat (PQ), we designed continuous plasma perfusion of dual cartridges in series (CPPDCS) on Diapact Braun CRRT machine. The goals of this study were to evaluate the effective of CPPDCS on paraquat removal in patients with acute paraquat intoxication. Our results show that the PQ clearance rate of dual cartridges was significantly higher than that of single cartridge at 1st, 2nd, 3(rd), and 4th plasma perfusion. Compared with single-cartridge plasma perfusion, CPPDCS significantly reduced the frequency of cartridge replacement, shorten the time of perfusion. These results indicate that CPPDCS is effective than plasma perfusion of single cartridge on PQ clearance rate and may provide an effective treatment for PQ poisoning.

  18. Extremity perfusion for sarcoma

    NARCIS (Netherlands)

    Hoekstra, Harald Joan

    2008-01-01

    For more than 50 years, the technique of extremity perfusion has been explored in the limb salvage treatment of local, recurrent, and multifocal sarcomas. The "discovery" of tumor necrosis factor-or. in combination with melphalan was a real breakthrough in the treatment of primarily irresectable ext

  19. Extremity perfusion for sarcoma

    NARCIS (Netherlands)

    Hoekstra, Harald Joan

    2008-01-01

    For more than 50 years, the technique of extremity perfusion has been explored in the limb salvage treatment of local, recurrent, and multifocal sarcomas. The "discovery" of tumor necrosis factor-or. in combination with melphalan was a real breakthrough in the treatment of primarily irresectable

  20. SUBMERGED PERFUSION BIOREACTOR

    DEFF Research Database (Denmark)

    2010-01-01

    to flow out of the body. USE - A biological device for cell culturing, enzymatic reactions or filtering of fluid (claimed). ADVANTAGE - The device has simple setup without the need of external pumping mechanisms to obtain a perfusion flow system. DETAILED DESCRIPTION - A biological device comprises a body...

  1. Possibilities of differentiation of solitary focal liver lesions by computed tomography perfusion

    Directory of Open Access Journals (Sweden)

    Irmina Sefić Pašić

    2015-08-01

    Full Text Available Aim To evaluate possibilities of computed tomography (CT perfusion in differentiation of solitary focal liver lesions based on their characteristic vascularization through perfusion parameters analysis. Methods Prospective study was conducted on 50 patients in the period 2009-2012. Patients were divided in two groups: benign and malignant lesions. The following CT perfusion parameters were analyzed: blood flow (BF, blood volume (BV, mean transit time (MTT, capillary permeability surface area product (PS, hepatic arterial fraction (HAF, and impulse residual function (IRF. During the study another perfusion parameter was analyzed: hepatic perfusion index (HPI. All patients were examined on Multidetector 64-slice CT machine (GE with application of perfusion protocol for liver with i.v. administration of contrast agent. Results In both groups an increase of vascularization and arterial blood flow was noticed, but there was no significant statistical difference between any of 6 analyzed parameters. Hepatic perfusion index values were increased in all lesions in comparison with normal liver parenchyma. Conclusion Computed tomography perfusion in our study did not allow differentiation of benign and malignant liver lesions based on analysis of functional perfusion parameters. Hepatic perfusion index should be investigated in further studies as a parameter for detection of possible presence of micro-metastases in visually homogeneous liver in cases with no lesions found during standard CT protocol

  2. Low dose CT perfusion using k-means clustering

    Science.gov (United States)

    Pisana, Francesco; Henzler, Thomas; Schönberg, Stefan; Klotz, Ernst; Schmidt, Bernhard; Kachelrieß, Marc

    2016-03-01

    We aim at improving low dose CT perfusion functional parameters maps and CT images quality, preserving quantitative information. In a dynamic CT perfusion dataset, each voxel is measured T times, where T is the number of acquired time points. In this sense, we can think about a voxel as a point in a T-dimensional space, where the coordinates of the voxels would be the values of its time attenuation curve (TAC). Starting from this idea, a k-means algorithm was designed to group voxels in K classes. A modified guided time-intensity profile similarity (gTIPS) filter was implemented and applied only for those voxels belonging to the same class. The approach was tested on a digital brain perfusion phantom as well as on clinical brain and body perfusion datasets, and compared to the original TIPS implementation. The TIPS filter showed the highest CNR improvement, but lowest spatial resolution. gTIPS proved to have the best combination of spatial resolution and CNR improvement for CT images, while k-gTIPS was superior to both gTIPS and TIPS in terms of perfusion maps image quality. We demonstrate k-means clustering analysis can be applied to denoise dynamic CT perfusion data and to improve functional maps. Beside the promising results, this approach has the major benefit of being independent from the perfusion model employed for functional parameters calculation. No similar approaches were found in literature.

  3. Machine-Aided Indexing for NASA STI.

    Science.gov (United States)

    Wilson, John

    1987-01-01

    Describes the use of machine aided indexing as part of NASA's information systems. The discussion covers reasons for incorporating machine aided indexing, the lexical dictionary used, subject switching, natural language processing, benefits to the system, and possible future developments. (CLB)

  4. Is misery perfusion still a predictor of stroke in symptomatic major cerebral artery disease?

    Science.gov (United States)

    Yamauchi, Hiroshi; Higashi, Tatsuya; Kagawa, Shinya; Nishii, Ryuichi; Kudo, Takashi; Sugimoto, Kanji; Okazawa, Hidehiko; Fukuyama, Hidenao

    2012-08-01

    Studies in the 1990s demonstrated that misery perfusion is a predictor of subsequent stroke in medically treated patients with symptomatic major cerebral artery disease. A recent randomized controlled trial demonstrated no benefit of bypass surgery for such patients. In this light, outcome in patients with misery perfusion has regained interest. The purpose of this study was to determine whether misery perfusion is still a predictor of subsequent stroke despite recent improvements in medical treatment for secondary prevention of stroke, and if so, whether the predictive value of misery perfusion has changed in recent years. We prospectively studied 165 non-disabled patients with symptomatic atherosclerotic internal carotid artery or middle cerebral artery occlusive diseases who underwent positron emission tomography from 1999 to 2008. Misery perfusion was defined as decreased cerebral blood flow, increased oxygen extraction fraction and decreased ratio of cerebral blood flow to blood volume in the hemisphere supplied by the diseased artery. All patients were followed up for 2 years until stroke recurrence or death. Bypass surgery was performed in 19 of 35 patients with and 16 of 130 patients without misery perfusion. The 2-year incidence of ipsilateral ischaemic stroke was six and four patients with and without misery perfusion, including two and one after surgery, respectively (P misery perfusion and 12 patients without (P misery perfusion in whole sample was 6.3 (95% confidence interval 1.7-22.4, P misery perfusion or bypass surgery did not differ. Between these periods, patients without misery perfusion demonstrated a decrease in stroke rate (from 16.2% to 0%), but patients with misery perfusion did not (26.3 and 25.0%). In symptomatic major cerebral artery disease, misery perfusion remains a predictor of subsequent stroke, although the recurrence rate was lower than the previous study. In patients without misery perfusion, the risk of stroke was reduced

  5. Perfusion abnormalities in hemimegalencephaly.

    Science.gov (United States)

    Wintermark, P; Roulet-Perez, E; Maeder-Ingvar, M; Moessinger, A C; Gudinchet, F; Meuli, R

    2009-04-01

    Cerebrovascular changes are rarely discussed in patients with hemimegalencephaly. These alterations have previously been associated with epileptical activity. We report the case of a 36-week gestation neonate presenting with total right hemimegalencephaly, as demonstrated by a magnetic resonance imaging (MRI) performed in the first days of life. Perfusion-weighted imaging displayed a clear hypervascularization of the right hemisphere. Diffusion-tensor imaging showed an arrangement of white matter fibers concentrically around the ventricle on the right hemisphere. AngioMRI showed an obvious asymmetry in the size of the middle cerebral arteries, with the right middle cerebral artery being prominent. The baby was free of clinical seizures during his first week of life. An electroencephalogram at that time displayed an asymmetric background activity, but no electrical seizures. Perfusion anomalies in hemimegalencephaly may not necessarily be related to epileptical activity, but may be related to vessel alterations. (c) Georg Thieme Verlag KG Stuttgart, New York.

  6. Whole tumour perfusion of peripheral lung carcinoma: evaluation with first-pass CT perfusion imaging at 64-detector row CT

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y. [Department of Radiology, West China Hospital, Sichuan University, Chengdu, Sichuan (China); Yang, Z.-G. [Department of Radiology, West China Hospital, Sichuan University, Chengdu, Sichuan (China); National Key Laboratory of Biotherapy Center, West China Hospital, Sichuan University, Chengdu, Sichuan (China)], E-mail: yangzg1117@yahoo.com.cn; Chen, T.-w.; Deng, Y.-p.; Yu, J.-q.; Li, Z.-l. [Department of Radiology, West China Hospital, Sichuan University, Chengdu, Sichuan (China)

    2008-06-15

    Aim: To prospectively assess the feasibility of a whole-tumour perfusion technique using 64-detector row computed tomography (CT) and to analyse the variation of CT perfusion parameters in different histological types, sizes, and metastases in patients with peripheral lung carcinoma. Methods and materials: Ninety-seven pathologically proved peripheral lung carcinomas (less than 5 cm in largest diameter) underwent dynamic contrast-enhanced CT using a 64-detector row CT machine. Small amounts of iodinated contrast medium with a sharp bolus profile (50 ml, 6-7 ml/s), and 12 repeated fast acquisitions encompassing the entire tumour lesion were adopted to quantify perfusion of the whole-tumour during first-pass of contrast medium. Four kinetic parameters, including perfusion, peak enhancement intensity (PEI), time to peak (TTP), and blood volume (BV), were measured and statistically compared among different histological types, sizes, and metastases. Results: Mean values for perfusion, PEI, TTP, and BV of the 97 lung carcinomas were 57.5 {+-} 45.4 ml/min/ml (range 5.9-243 ml/min/ml), 53.4 {+-} 40.6 HU (range 10.3-234.4 HU), 34 {+-} 11 s (range 11-60 s), and 30.1 {+-} 21.7 ml/100 g (range 3.9-113.4 ml/100 g), respectively. No statistical differences were found between the histological types regarding the perfusion parameters (p > 0.05). Perfusion, PEI, and BV of stage T2 tumours were significantly lower than those of stage T1 tumours (all p < 0.05), whereas no statistically significant differences was found between other stages of tumours (all p > 0.05). Perfusion of the tumours with distant metastasis was significantly higher than that of the tumours without distant metastasis (p < 0.05), but there was no statistically significant difference between nodal metastasis positive and negative groups (p > 0.05). Conclusion: The present study of first-pass perfusion imaging using 64-detector row CT could provide a feasible method for assessment of whole-tumour perfusion. CT

  7. Machine learning with R cookbook

    CERN Document Server

    Chiu, Yu-Wei

    2015-01-01

    If you want to learn how to use R for machine learning and gain insights from your data, then this book is ideal for you. Regardless of your level of experience, this book covers the basics of applying R to machine learning through to advanced techniques. While it is helpful if you are familiar with basic programming or machine learning concepts, you do not require prior experience to benefit from this book.

  8. Perfusion Based Cell Culture Chips

    Science.gov (United States)

    Heiskanen, A.; Emnéus, J.; Dufva, M.

    Performing cell culture in miniaturized perfusion chambers gives possibilities to experiment with cells under near in vivo like conditions. In contrast to traditional batch cultures, miniaturized perfusion systems provide precise control of medium composition, long term unattended cultures and tissue like structuring of the cultures. However, as this chapter illustrates, many issues remain to be identified regarding perfusion cell culture such as design, material choice and how to use these systems before they will be widespread amongst biomedical researchers.

  9. Perfusion based cell culture chips

    DEFF Research Database (Denmark)

    Heiskanen, Arto; Emnéus, Jenny; Dufva, Martin

    2010-01-01

    and tissue like structuring of the cultures. However, as this chapter illustrates, many issues remain to be identified regarding perfusion cell culture such as design, material choice and how to use these systems before they will be widespread amongst biomedical researchers.......Performing cell culture in miniaturized perfusion chambers gives possibilities to experiment with cells under near in vivo like conditions. In contrast to traditional batch cultures, miniaturized perfusion systems provide precise control of medium composition, long term unattended cultures...

  10. Virtual machine vs Real Machine: Security Systems

    Directory of Open Access Journals (Sweden)

    Dr. C. Suresh Gnana Das

    2009-08-01

    Full Text Available This paper argues that the operating system and applications currently running on a real machine should relocate into a virtual machine. This structure enables services to be added below the operating system and to do so without trusting or modifying the operating system or applications. To demonstrate the usefulness of this structure, we describe three services that take advantage of it: secure logging, intrusion prevention and detection, and environment migration. In particular, we can provide services below the guest operating system without trusting or modifying it. We believe providing services at this layer are especially useful for enhancing security and mobility. This position paper describes the general benefits and challenges that arise from running most applications in a virtual machine, and then describes some example services and alternative ways to provide those services.

  11. Sustainable machining

    CERN Document Server

    2017-01-01

    This book provides an overview on current sustainable machining. Its chapters cover the concept in economic, social and environmental dimensions. It provides the reader with proper ways to handle several pollutants produced during the machining process. The book is useful on both undergraduate and postgraduate levels and it is of interest to all those working with manufacturing and machining technology.

  12. Machine Learning and Radiology

    Science.gov (United States)

    Wang, Shijun; Summers, Ronald M.

    2012-01-01

    In this paper, we give a short introduction to machine learning and survey its applications in radiology. We focused on six categories of applications in radiology: medical image segmentation, registration, computer aided detection and diagnosis, brain function or activity analysis and neurological disease diagnosis from fMR images, content-based image retrieval systems for CT or MRI images, and text analysis of radiology reports using natural language processing (NLP) and natural language understanding (NLU). This survey shows that machine learning plays a key role in many radiology applications. Machine learning identifies complex patterns automatically and helps radiologists make intelligent decisions on radiology data such as conventional radiographs, CT, MRI, and PET images and radiology reports. In many applications, the performance of machine learning-based automatic detection and diagnosis systems has shown to be comparable to that of a well-trained and experienced radiologist. Technology development in machine learning and radiology will benefit from each other in the long run. Key contributions and common characteristics of machine learning techniques in radiology are discussed. We also discuss the problem of translating machine learning applications to the radiology clinical setting, including advantages and potential barriers. PMID:22465077

  13. Perfusion Bioreactor Module

    Science.gov (United States)

    Morrison, Dennis R.

    1990-01-01

    Perfusion bioreactor module, self-contained, closed-loop cell-culture system that operates in microgravity or on Earth. Equipment supports growth or long-term maintenance of cultures of human or other fragile cells for experiments in basic cell biology or process technology. Designed to support proliferation (initially at exponential rates of growth) of cells in complex growth medium and to maintain confluent cells in defined medium under conditions optimized to permit or encourage selected functions of cells, including secretion of products of cells into medium.

  14. Measuring myocardial perfusion

    DEFF Research Database (Denmark)

    Qayyum, A A; Kastrup, J

    2015-01-01

    -pass of non-ionic and ionic contrast agents, respectively. Absolute quantification with CMR has yet to be established in routine clinical practice, while CT has yet to prove its diagnostic and prognostic value. The upcoming years may change the way we diagnose and treat patients suspected of having CAD......Recently, focus has changed from anatomical assessment of coronary arteries towards functional testing to evaluate the effect of stenosis on the myocardium before intervention. Besides positron-emission tomography (PET), cardiac MRI (CMR), and cardiac CT are able to measure myocardial perfusion...

  15. Noncontact blood perfusion mapping in clinical applications

    Science.gov (United States)

    Iakovlev, Dmitry; Dwyer, Vincent; Hu, Sijung; Silberschmidt, Vadim

    2016-04-01

    Non-contact imaging photoplethysmography (iPPG) to detect pulsatile blood microcirculation in tissue has been selected as a successor to low spatial resolution and slow scanning blood perfusion techniques currently employed by clinicians. The proposed iPPG system employs a novel illumination source constructed of multiple high power LEDs with narrow spectral emission, which are temporally modulated and synchronised with a high performance sCMOS sensor. To ensure spectrum stability and prevent thermal wavelength drift due to junction temperature variations, each LED features a custom-designed thermal management system to effectively dissipate generated heat and auto-adjust current flow. The use of a multi-wavelength approach has resulted in simultaneous microvascular perfusion monitoring at various tissue depths, which is an added benefit for specific clinical applications. A synchronous detection algorithm to extract weak photoplethysmographic pulse-waveforms demonstrated robustness and high efficiency when applied to even small regions of 5 mm2. The experimental results showed evidences that the proposed system could achieve noticeable accuracy in blood perfusion monitoring by creating complex amplitude and phase maps for the tissue under examination.

  16. Ex Vivo Perfusion Characteristics of Donation After Cardiac Death Kidneys Predict Long-Term Graft Survival.

    Science.gov (United States)

    Sevinc, M; Stamp, S; Ling, J; Carter, N; Talbot, D; Sheerin, N

    2016-12-01

    Ex vivo perfusion is used in our unit for kidneys donated after cardiac death (DCD). Perfusion flow index (PFI), resistance, and perfusate glutathione S-transferase (GST) can be measured to assess graft viability. We assessed whether measurements taken during perfusion could predict long-term outcome after transplantation. All DCD kidney transplants performed from 2002 to 2014 were included in this study. The exclusion criteria were: incomplete data, kidneys not machine perfused, kidneys perfused in continuous mode, and dual transplantation. There were 155 kidney transplantations included in the final analysis. Demographic data, ischemia times, donor hypertension, graft function, survival and machine perfusion parameters after 3 hours were analyzed. Each perfusion parameter was divided into 3 groups as high, medium, and low. Estimated glomerular filtration rate was calculated at 12 months and then yearly after transplantation. There was a significant association between graft survival and PFI and GST (P values, .020 and .022, respectively). PFI was the only independent parameter to predict graft survival. A low PFI during ex vivo hypothermic perfusion is associated with inferior graft survival after DCD kidney transplantation. We propose that PFI is a measure of the health of the graft vasculature and that a low PFI indicates vascular disease and therefore predicts a worse long-term outcome. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Machine musicianship

    Science.gov (United States)

    Rowe, Robert

    2002-05-01

    The training of musicians begins by teaching basic musical concepts, a collection of knowledge commonly known as musicianship. Computer programs designed to implement musical skills (e.g., to make sense of what they hear, perform music expressively, or compose convincing pieces) can similarly benefit from access to a fundamental level of musicianship. Recent research in music cognition, artificial intelligence, and music theory has produced a repertoire of techniques that can make the behavior of computer programs more musical. Many of these were presented in a recently published book/CD-ROM entitled Machine Musicianship. For use in interactive music systems, we are interested in those which are fast enough to run in real time and that need only make reference to the material as it appears in sequence. This talk will review several applications that are able to identify the tonal center of musical material during performance. Beyond this specific task, the design of real-time algorithmic listening through the concurrent operation of several connected analyzers is examined. The presentation includes discussion of a library of C++ objects that can be combined to perform interactive listening and a demonstration of their capability.

  18. Myocardial perfusion modeling using MRI

    DEFF Research Database (Denmark)

    Larsson, H B; Fritz-Hansen, T; Rostrup, Egill

    1996-01-01

    In the present study, it is shown that it is possible to quantify myocardial perfusion using magnetic resonance imaging in combination with gadolinium diethylenetriaminopentaacetic acid (Gd-DTPA). Previously, a simple model and method for measuring myocardial perfusion using an inversion recovery...

  19. Myocardial perfusion modeling using MRI

    DEFF Research Database (Denmark)

    Larsson, H B; Fritz-Hansen, T; Rostrup, Egill

    1996-01-01

    In the present study, it is shown that it is possible to quantify myocardial perfusion using magnetic resonance imaging in combination with gadolinium diethylenetriaminopentaacetic acid (Gd-DTPA). Previously, a simple model and method for measuring myocardial perfusion using an inversion recovery...

  20. Simple machines

    CERN Document Server

    Graybill, George

    2007-01-01

    Just how simple are simple machines? With our ready-to-use resource, they are simple to teach and easy to learn! Chocked full of information and activities, we begin with a look at force, motion and work, and examples of simple machines in daily life are given. With this background, we move on to different kinds of simple machines including: Levers, Inclined Planes, Wedges, Screws, Pulleys, and Wheels and Axles. An exploration of some compound machines follows, such as the can opener. Our resource is a real time-saver as all the reading passages, student activities are provided. Presented in s

  1. Perfusion measurement in acute pancreatitis using dynamic perfusion MDCT.

    Science.gov (United States)

    Bize, Pierre E; Platon, Alexandra; Becker, Christoph D; Poletti, Pierre-Alexandre

    2006-01-01

    Our objective was to determine whether MDCT with perfusion imaging could help in assessing the severity of acute pancreatitis in the initial phase of the disease. One hundred six patients with abdominal pain were prospectively enrolled in this study. Patients were separated into two groups: P1 (severe) and P2 (mild) acute pancreatitis. Mean perfusion value was 24.8 mL/100 mL/min in the P1 group and 50.5 mL/100 mL/min in the P2 group (p = 0.0016, significant). Our preliminary data suggest that pancreatic perfusion measurement using MDCT with perfusion imaging could help in assessing the severity of acute pancreatitis.

  2. Placental perfusion - a human alternative

    DEFF Research Database (Denmark)

    Mose, Tina; Knudsen, Lisbeth E

    2006-01-01

    Foetal exposures to environmental and medicinal products have impact on the growth of the foetus (e.g. cigarette smoke) and development of organs (e.g. methylmercury and Thalidomide). Perfusion studies of the human term placenta enable investigation of placental transport of chemical substances...... between the mother and foetus. Dual perfusion of a single cotyledon in the human placenta can contribute to a better understanding of the placental barrier, transport rate and mechanisms of different substances and placental metabolism. The perfusion system has recently been established in Copenhagen...

  3. Electric machine

    Science.gov (United States)

    El-Refaie, Ayman Mohamed Fawzi [Niskayuna, NY; Reddy, Patel Bhageerath [Madison, WI

    2012-07-17

    An interior permanent magnet electric machine is disclosed. The interior permanent magnet electric machine comprises a rotor comprising a plurality of radially placed magnets each having a proximal end and a distal end, wherein each magnet comprises a plurality of magnetic segments and at least one magnetic segment towards the distal end comprises a high resistivity magnetic material.

  4. Multi-detector CT perfusion

    Directory of Open Access Journals (Sweden)

    Ashraf M. Enite

    2016-09-01

    Conclusion: CTP is a promising non-invasive technique assessing the efficacy, predicting early response to local treatment therapies and monitoring tumor recurrence. It assesses the degree of post therapy tumor perfusion especially the degree of arterialization.

  5. Ocular perfusion pressure in glaucoma.

    Science.gov (United States)

    Costa, Vital P; Harris, Alon; Anderson, Douglas; Stodtmeister, Richard; Cremasco, Fernanda; Kergoat, Helene; Lovasik, John; Stalmans, Ingborg; Zeitz, Oliver; Lanzl, Ines; Gugleta, Konstantin; Schmetterer, Leopold

    2014-06-01

    This review article discusses the relationship between ocular perfusion pressure and glaucoma, including its definition, factors that influence its calculation and epidemiological studies investigating the influence of ocular perfusion pressure on the prevalence, incidence and progression of glaucoma. We also list the possible mechanisms behind this association, and discuss whether it is secondary to changes in intraocular pressure, blood pressure or both. Finally, we describe the circadian variation of ocular perfusion pressure and the effects of systemic and topical medications on it. We believe that the balance between IOP and BP, influenced by the autoregulatory capacity of the eye, is part of what determines whether an individual will develop optic nerve damage. However, prospective, longitudinal studies are needed to better define the role of ocular perfusion pressure in the development and progression of glaucoma.

  6. The Machine within the Machine

    CERN Multimedia

    Katarina Anthony

    2014-01-01

    Although Virtual Machines are widespread across CERN, you probably won't have heard of them unless you work for an experiment. Virtual machines - known as VMs - allow you to create a separate machine within your own, allowing you to run Linux on your Mac, or Windows on your Linux - whatever combination you need.   Using a CERN Virtual Machine, a Linux analysis software runs on a Macbook. When it comes to LHC data, one of the primary issues collaborations face is the diversity of computing environments among collaborators spread across the world. What if an institute cannot run the analysis software because they use different operating systems? "That's where the CernVM project comes in," says Gerardo Ganis, PH-SFT staff member and leader of the CernVM project. "We were able to respond to experimentalists' concerns by providing a virtual machine package that could be used to run experiment software. This way, no matter what hardware they have ...

  7. Machine Learning

    CERN Document Server

    CERN. Geneva

    2017-01-01

    Machine learning, which builds on ideas in computer science, statistics, and optimization, focuses on developing algorithms to identify patterns and regularities in data, and using these learned patterns to make predictions on new observations. Boosted by its industrial and commercial applications, the field of machine learning is quickly evolving and expanding. Recent advances have seen great success in the realms of computer vision, natural language processing, and broadly in data science. Many of these techniques have already been applied in particle physics, for instance for particle identification, detector monitoring, and the optimization of computer resources. Modern machine learning approaches, such as deep learning, are only just beginning to be applied to the analysis of High Energy Physics data to approach more and more complex problems. These classes will review the framework behind machine learning and discuss recent developments in the field.

  8. Machine learning in virtual screening.

    Science.gov (United States)

    Melville, James L; Burke, Edmund K; Hirst, Jonathan D

    2009-05-01

    In this review, we highlight recent applications of machine learning to virtual screening, focusing on the use of supervised techniques to train statistical learning algorithms to prioritize databases of molecules as active against a particular protein target. Both ligand-based similarity searching and structure-based docking have benefited from machine learning algorithms, including naïve Bayesian classifiers, support vector machines, neural networks, and decision trees, as well as more traditional regression techniques. Effective application of these methodologies requires an appreciation of data preparation, validation, optimization, and search methodologies, and we also survey developments in these areas.

  9. Ex Vivo Lung Perfusion: Establishment and Operationalization in Iran.

    Science.gov (United States)

    Shafaghi, Shadi; Abbasi Dezfuli, Azizollah; Ansari Aval, Zahra; Sheikhy, Kambiz; Farzanegan, Behrooz; Mortaz, Esmaeil; Emami, Habib; Aigner, Clemens; Hosseini-Baharanchi, Fatemeh Sadat; Najafizadeh, Katayoun

    2017-02-01

    Although the number of lung transplants is limited because of general shortage of organ donors, ex vivo lung perfusion is a novel method with 2 main benefits, including better evaluation of lung potential and recovery of injured lungs. The main aim of this study was to establish and operationalize ex vivo lung perfusion as the first experience in Iran. This was a prospective operational research study on 5 cases, including 1 pig from Vienna Medical University and 4 patients from Masih Daneshvari Hospital. All organ donations from brain dead donors were evaluated according to lung transplant or ex vivo lung perfusion criteria from May 2013 to July 2015 in Tehran, Iran. If a donor did not have any sign of severe chest trauma or pneumonia but had poor oxygenation due to possible atelectasis or neurogenic pulmonary edema, their lungs were included for ex vivo lung perfusion. A successful trend in the difference between the pulmonary arterial Po2 and the left atrial Po2 was observed, as well as an increasing pattern in other functional parameters, including dynamic lung compliance and a decreasing trend in pulmonary vascular resistance. These initial trials indicate that ex vivo lung perfusion can lead to remarkable progress in lung transplant in Iran. They also provide several important pieces of guidance for successful ex vivo lung perfusion, including the necessity of following standard lung retrieval procedures and monitoring temperature and pressure precisely. The development of novel methods can provide opportunities for further research studies on lungs of deceased donors and lead to undiscovered findings. By keeping this science up to date in Iran and developing such new and creative methods, we can reveal effective strategies to promote the quality of donor lungs to support patients on transplant wait lists.

  10. Hyperventilation, cerebral perfusion, and syncope

    DEFF Research Database (Denmark)

    Immink, R V; Pott, F C; Secher, N H

    2014-01-01

    the contribution of a low PaCO2 to the early postural reduction in middle cerebral artery blood velocity is transient. HV together with postural stress does not reduce cerebral perfusion to such an extent that TLOC develops. However when HV is combined with cardiovascular stressors like cold immersion or reduced......This review summarizes evidence in humans for an association between hyperventilation (HV)-induced hypocapnia and a reduction in cerebral perfusion leading to syncope defined as transient loss of consciousness (TLOC). The cerebral vasculature is sensitive to changes in both the arterial carbon...

  11. Dynamic CT myocardial perfusion imaging.

    Science.gov (United States)

    Caruso, Damiano; Eid, Marwen; Schoepf, U Joseph; Jin, Kwang Nam; Varga-Szemes, Akos; Tesche, Christian; Mangold, Stefanie; Spandorfer, Adam; Laghi, Andrea; De Cecco, Carlo N

    2016-10-01

    Non-invasive cardiac imaging has rapidly evolved during the last decade due to advancements in CT based technologies. Coronary CT angiography has been shown to reliably assess coronary anatomy and detect high risk coronary artery disease. However, this technique is limited to anatomical assessment, thus non-invasive techniques for functional assessment of the heart are necessary. CT myocardial perfusion is a new CT based technique that provides functional assessment of the myocardium and allows for a comprehensive assessment of coronary artery disease with a single modality when combined with CTA. This review aims to discuss dynamic CT myocardial perfusion as a new technique in the assessment of CAD.

  12. Machine Learning

    Energy Technology Data Exchange (ETDEWEB)

    Chikkagoudar, Satish; Chatterjee, Samrat; Thomas, Dennis G.; Carroll, Thomas E.; Muller, George

    2017-04-21

    The absence of a robust and unified theory of cyber dynamics presents challenges and opportunities for using machine learning based data-driven approaches to further the understanding of the behavior of such complex systems. Analysts can also use machine learning approaches to gain operational insights. In order to be operationally beneficial, cybersecurity machine learning based models need to have the ability to: (1) represent a real-world system, (2) infer system properties, and (3) learn and adapt based on expert knowledge and observations. Probabilistic models and Probabilistic graphical models provide these necessary properties and are further explored in this chapter. Bayesian Networks and Hidden Markov Models are introduced as an example of a widely used data driven classification/modeling strategy.

  13. Noninvasive methods of measuring bone blood perfusion

    OpenAIRE

    Dyke, J. P.; Aaron, R.K.

    2010-01-01

    Measurement of bone blood flow and perfusion characteristics in a noninvasive and serial manner would be advantageous in assessing revascularization after trauma and the possible risk of avascular necrosis. Many disease states, including osteoporosis, osteoarthritis, and bone neoplasms, result in disturbed bone perfusion. A causal link between bone perfusion and remodeling has shown its importance in sustained healing and regrowth following injury. Measurement of perfusion and permeability wi...

  14. Automatic assessment of cardiac perfusion MRI

    DEFF Research Database (Denmark)

    Ólafsdóttir, Hildur; Stegmann, Mikkel Bille; Larsson, Henrik B.W.

    2004-01-01

    In this paper, a method based on Active Appearance Models (AAM) is applied for automatic registration of myocardial perfusion MRI. A semi-quantitative perfusion assessment of the registered image sequences is presented. This includes the formation of perfusion maps for three parameters; maximum up...

  15. Machine testning

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo

    This document is used in connection with a laboratory exercise of 3 hours duration as a part of the course GEOMETRICAL METROLOGY AND MACHINE TESTING. The exercise includes a series of tests carried out by the student on a conventional and a numerically controled lathe, respectively. This document...

  16. Representational Machines

    DEFF Research Database (Denmark)

    Petersson, Dag; Dahlgren, Anna; Vestberg, Nina Lager

    to the enterprises of the medium. This is the subject of Representational Machines: How photography enlists the workings of institutional technologies in search of establishing new iconic and social spaces. Together, the contributions to this edited volume span historical epochs, social environments, technological...

  17. Adding machine and calculating machine

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In 1642 the French mathematician Blaise Pascal(1623-1662) invented a machine;.that could add and subtract. It had.wheels that each had: 1 to 10 marked off along its circumference. When the wheel at the right, representing units, made one complete circle, it engaged the wheel to its left, represents tens, and moved it forward one notch.

  18. Magnetic resonance perfusion imaging without contrast media

    Energy Technology Data Exchange (ETDEWEB)

    Martirosian, Petros; Graf, Hansjoerg; Schick, Fritz [University Hospital of Tuebingen, Section on Experimental Radiology, Tuebingen (Germany); Boss, Andreas; Schraml, Christina; Schwenzer, Nina F.; Claussen, Claus D. [University Hospital of Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany)

    2010-08-15

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

  19. New method for 3D parametric visualization of contrast-enhanced pulmonary perfusion MRI data

    Energy Technology Data Exchange (ETDEWEB)

    Kuder, Tristan A.; Eichinger, Monika; Ley, Sebastian; Puderbach, Michael; Kauczor, Hans-Ulrich [Deutsches Krebsforschungszentrum, Department of Radiology, E010, Heidelberg (Germany); Risse, Frank [Deutsches Krebsforschungszentrum, Department of Medical Physics in Radiology, Heidelberg (Germany); Fink, Christian [Deutsches Krebsforschungszentrum, Department of Radiology, E010, Heidelberg (Germany); Medical Faculty Mannheim - University of Heidelberg, Department of Clinical Radiology, University Hospital Mannheim, Mannheim (Germany)

    2008-02-15

    Three-dimensional (3D) dynamic contrast-enhanced magnetic resonance imaging (3D DCE-MRI) has been proposed for the assessment of regional perfusion. The aim of this work was the implementation of an algorithm for a 3D parametric visualization of lung perfusion using different cutting planes and volume rendering. Our implementation was based on 3D DCE-MRI data of the lungs of five patients and five healthy volunteers. Using the indicator dilution theory, the regional perfusion parameters, tissue blood flow, blood volume and mean transit time were calculated. Due to the required temporal resolution, the volume elements of dynamic MR data sets show a reduced spatial resolution in the z-direction. Therefore, perfusion parameter volumes were interpolated. Linear interpolation and a combination of linear and nearest-neighbor interpolation were evaluated. Additionally, ray tracing was applied for 3D visualization. The linear interpolation algorithm caused interpolation errors at the lung borders. Using the combined interpolation, visualization of perfusion information in arbitrary cutting planes and in 3D using volume rendering was possible. This facilitated the localization of perfusion deficits compared with the coronal orientated source data. The 3D visualization of perfusion parameters using a combined interpolation algorithm is feasible. Further studies are required to evaluate the additional benefit from the 3D visualization. (orig.)

  20. On Implementation path and Benefit Analysis of Footwear Industry“Machine Substitutions”Based on Industry 4.0--Taking Wenzhou Footwear Industry for example%工业4.0环境下的鞋类企业“机器换人”实施路径及效益分析*--以温州地区的鞋企为例

    Institute of Scientific and Technical Information of China (English)

    石娜

    2016-01-01

    Faced with the economic new normal of the"industrial 4"manufacturing transformation and upgrading, footwear en-terprises as the pillar industry of Wenzhou light industrial products carry out“machine substitutions”to improve design and produc-tion capacity, and solve the shortage of workers, thus to further enhance the quality of products and brand connotation and obtain great-er benefits. Through the path and benefit analysis on machine substitutions, the paper provides feasible basis for Wenzhou shoe enter-prises to the full implementation of“machine substitutions”.%在面临“工业4.0”制造业转型升级的经济新常态下,作为温州轻工产品支柱产业的鞋类企业应实施“机器换人”提高设计和生产能力解决用工问题,进而提升产品质量和品牌内涵,获取更大效益。通过对“机器换人”的路径和效益分析,为温州鞋企全面实施“机器换人”提供可行依据。

  1. Machine Learning for Medical Imaging.

    Science.gov (United States)

    Erickson, Bradley J; Korfiatis, Panagiotis; Akkus, Zeynettin; Kline, Timothy L

    2017-01-01

    Machine learning is a technique for recognizing patterns that can be applied to medical images. Although it is a powerful tool that can help in rendering medical diagnoses, it can be misapplied. Machine learning typically begins with the machine learning algorithm system computing the image features that are believed to be of importance in making the prediction or diagnosis of interest. The machine learning algorithm system then identifies the best combination of these image features for classifying the image or computing some metric for the given image region. There are several methods that can be used, each with different strengths and weaknesses. There are open-source versions of most of these machine learning methods that make them easy to try and apply to images. Several metrics for measuring the performance of an algorithm exist; however, one must be aware of the possible associated pitfalls that can result in misleading metrics. More recently, deep learning has started to be used; this method has the benefit that it does not require image feature identification and calculation as a first step; rather, features are identified as part of the learning process. Machine learning has been used in medical imaging and will have a greater influence in the future. Those working in medical imaging must be aware of how machine learning works. (©)RSNA, 2017.

  2. Genesis machines

    CERN Document Server

    Amos, Martyn

    2014-01-01

    Silicon chips are out. Today's scientists are using real, wet, squishy, living biology to build the next generation of computers. Cells, gels and DNA strands are the 'wetware' of the twenty-first century. Much smaller and more intelligent, these organic computers open up revolutionary possibilities. Tracing the history of computing and revealing a brave new world to come, Genesis Machines describes how this new technology will change the way we think not just about computers - but about life itself.

  3. Successful five-day perfusion preservation of the canine kidney.

    Science.gov (United States)

    McAnulty, J F; Ploeg, R J; Southard, J H; Belzer, F O

    1989-01-01

    Over 20 years ago, successful 3-day-perfusion preservation of canine kidneys was obtained. Since then, consistent 5-day preservation has not been reported. In this study, we investigated how the perfusate calcium concentration affected both mitochondrial function and posttransplant viability in dog kidneys preserved for 5 days. Dog kidneys were preserved by machine perfusion (5 degrees C) using a hydroxyethyl starch-gluconate solution that contained either 0.0, 0.5, 1.5, or 5.0 mM calcium. Mitochondria isolated from preserved kidneys has a loss of respiratory control when either 0.0, 1.5, or 5.0 mM calcium were present. However, the use of a perfusate with 0.5 mM calcium preserved the mitochondrial function at levels equivalent to controls for 5 days. Transplantation of kidneys preserved for 5 days with 0.0 or 1.5 mM calcium yielded poor survival (0% and 17%, respectively). The use of a 0.5-mM calcium perfusate increased posttransplant survival to 63% (5 of 8 transplanted). Donor pretreatment of kidneys with chlorpromazine (2.5 mg/kg i.v.) did not improve the function of mitochondria isolated from preserved kidneys but did increase survival in the 1.5-mM calcium group to 67% (4 of 6 transplanted) and in the 0.5 mM calcium group to 100% (7 of 7 transplanted). This is the first report to document consistently successful 5-day preservation of canine kidneys and clearly shows the importance of the perfusate calcium concentration in long-term kidney preservation. The specific mechanism by which calcium or chlorpromazine exert their effect is not known, but it is apparent that excessively high or low concentrations of calcium are damaging to the preserved organ, and an optimal calcium concentration combined with metabolic inhibition of calcium-dependent pathways can significantly improve the function of organs preserved for extended time periods.

  4. Myocardial perfusion modeling using MRI

    DEFF Research Database (Denmark)

    Larsson, H B; Fritz-Hansen, T; Rostrup, Egill

    1996-01-01

    In the present study, it is shown that it is possible to quantify myocardial perfusion using magnetic resonance imaging in combination with gadolinium diethylenetriaminopentaacetic acid (Gd-DTPA). Previously, a simple model and method for measuring myocardial perfusion using an inversion recovery...... turbo-FLASH (fast low-angle shot) sequence and Gd-DTPA has been presented. Here, an extension of the model is presented taking into account fast and slow water exchange between the compartments, enabling the calculation of the unidirectional influx constant (Ki) for Gd-DTPA, the distribution volume...... of Gd-DTPA (lambda), the vascular blood volume (Vb), and the time delay through the coronary arteries (delta T). The model was evaluated by computer simulation and used on experimental results from seven healthy subjects. The results in the healthy volunteers for a region of interest placed...

  5. Dosimetry in myocardial perfusion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Toledo, Janine M.; Trindade, Bruno; Ribeiro, Tarcisio P.C. [Universidade Federal de Minas Gerais (DEN/UFMG), Belo Horizonte (Brazil). Dept. de Engenharia Nuclear. Programa de Pos-Graduacao em Ciencias e Tecnicas Nucleares

    2011-07-01

    This paper conducts a dosimetric investigation on the myocardial perfusion image protocol, together with a literature reviewing, motivated by the significant statistic increasing on mortality, morbidity and disability associated with cardiovascular disease, surpassing infectious diseases. Nuclear Cardiology plays a role n the diagnostic functional evaluation of the heart and in the prognostic of patients with suspected or known cardiac ischemia. In the context of unstable myocardial ischemic syndrome, myocardial perfusion scintigraphy is a non-invasive procedure performed by administering a radiopharmaceutical targeted to the heart. As tool for this study are that the images obtained by thoracic angiotomography and abdominal aorta as a anatomic and functional information for model reproduction in SISCODES - System of Codes for Absorbed Dose Calculations based on Stochastic Methods. Data were manipulated in order to create a voxel computational model of the heart to be running in MCNP - Monte Carlo Neutron Particle Code. . It was assumed a homogeneous distribution of Tl-201 in cardiac muscle. Simulations of the transport of particles through the voxel and the interaction with the heart tissue were performed. As a result, the isodose curves in the heart model are displayed as well as the dose versus volume histogram of the heart muscle. We conclude that the present computational tools can generate doses distributed in myocardial perfusion. (author)

  6. Intestinal perfusion monitoring using photoplethysmography

    Science.gov (United States)

    Akl, Tony J.; Wilson, Mark A.; Ericson, M. Nance; Coté, Gerard L.

    2013-08-01

    In abdominal trauma patients, monitoring intestinal perfusion and oxygen consumption is essential during the resuscitation period. Photoplethysmography is an optical technique potentially capable of monitoring these changes in real time to provide the medical staff with a timely and quantitative measure of the adequacy of resuscitation. The challenges for using optical techniques in monitoring hemodynamics in intestinal tissue are discussed, and the solutions to these challenges are presented using a combination of Monte Carlo modeling and theoretical analysis of light propagation in tissue. In particular, it is shown that by using visible wavelengths (i.e., 470 and 525 nm), the perfusion signal is enhanced and the background contribution is decreased compared with using traditional near-infrared wavelengths leading to an order of magnitude enhancement in the signal-to-background ratio. It was further shown that, using the visible wavelengths, similar sensitivity to oxygenation changes could be obtained (over 50% compared with that of near-infrared wavelengths). This is mainly due to the increased contrast between tissue and blood in that spectral region and the confinement of the photons to the thickness of the small intestine. Moreover, the modeling results show that the source to detector separation should be limited to roughly 6 mm while using traditional near-infrared light, with a few centimeters source to detector separation leads to poor signal-to-background ratio. Finally, a visible wavelength system is tested in an in vivo porcine study, and the possibility of monitoring intestinal perfusion changes is showed.

  7. Ex-vivo lung perfusion.

    Science.gov (United States)

    Sanchez, Pablo G; D'Ovidio, Frank

    2012-10-01

    Lung transplant continues to be hampered by the number of available donors. Ex-vivo lung perfusion (EVLP) has emerged as an essential tool for the reassessment, under a controlled scenario, of lungs that initially did not meet transplantation criteria. The purpose of the current study is to review the most recent clinical and research reports and summarize their findings. Several centers have presented positive data when using ex-vivo perfusion to identify better grafts from the higher risk donor pool. The posttransplant results, when using these organs, are not significantly different from those obtained when using standard criteria donors. In addition, a great amount of research reports have emphasized the potential of ex-vivo perfusion as a platform in reducing the injurious effects of ischemia-reperfusion. EVLP has already proved its value as a tool to identify 'good' lungs from the previously rejected pool. But as new therapeutics arise , EVLP will also prove its value as a reproducible platform for their evaluation.

  8. Simulating Turing machines on Maurer machines

    NARCIS (Netherlands)

    Bergstra, J.A.; Middelburg, C.A.

    2008-01-01

    In a previous paper, we used Maurer machines to model and analyse micro-architectures. In the current paper, we investigate the connections between Turing machines and Maurer machines with the purpose to gain an insight into computability issues relating to Maurer machines. We introduce ways to

  9. Machine Learning in Medicine.

    Science.gov (United States)

    Deo, Rahul C

    2015-11-17

    Spurred by advances in processing power, memory, storage, and an unprecedented wealth of data, computers are being asked to tackle increasingly complex learning tasks, often with astonishing success. Computers have now mastered a popular variant of poker, learned the laws of physics from experimental data, and become experts in video games - tasks that would have been deemed impossible not too long ago. In parallel, the number of companies centered on applying complex data analysis to varying industries has exploded, and it is thus unsurprising that some analytic companies are turning attention to problems in health care. The purpose of this review is to explore what problems in medicine might benefit from such learning approaches and use examples from the literature to introduce basic concepts in machine learning. It is important to note that seemingly large enough medical data sets and adequate learning algorithms have been available for many decades, and yet, although there are thousands of papers applying machine learning algorithms to medical data, very few have contributed meaningfully to clinical care. This lack of impact stands in stark contrast to the enormous relevance of machine learning to many other industries. Thus, part of my effort will be to identify what obstacles there may be to changing the practice of medicine through statistical learning approaches, and discuss how these might be overcome.

  10. On-machine dimensional verification. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rendulic, W.

    1993-08-01

    General technology for automating in-process verification of machined products has been studied and implemented on a variety of machines and products at AlliedSignal Inc., Kansas City Division (KCD). Tests have been performed to establish system accuracy and probe reliability on two numerically controlled machining centers. Commercial software has been revised, and new cycles such as skew check and skew machining, have been developed to enhance and expand probing capabilities. Probe benefits have been demonstrated in the area of setup, cycle time, part quality, tooling cost, and product sampling.

  11. Core benefits

    National Research Council Canada - National Science Library

    Keith, Brian W

    2010-01-01

    This SPEC Kit explores the core employment benefits of retirement, and life, health, and other insurance -benefits that are typically decided by the parent institution and often have significant governmental regulation...

  12. Environmentally Friendly Machining

    CERN Document Server

    Dixit, U S; Davim, J Paulo

    2012-01-01

    Environment-Friendly Machining provides an in-depth overview of environmentally-friendly machining processes, covering numerous different types of machining in order to identify which practice is the most environmentally sustainable. The book discusses three systems at length: machining with minimal cutting fluid, air-cooled machining and dry machining. Also covered is a way to conserve energy during machining processes, along with useful data and detailed descriptions for developing and utilizing the most efficient modern machining tools. Researchers and engineers looking for sustainable machining solutions will find Environment-Friendly Machining to be a useful volume.

  13. Machine Transliteration

    CERN Document Server

    Knight, K; Knight, Kevin; Graehl, Jonathan

    1997-01-01

    It is challenging to translate names and technical terms across languages with different alphabets and sound inventories. These items are commonly transliterated, i.e., replaced with approximate phonetic equivalents. For example, "computer" in English comes out as "konpyuutaa" in Japanese. Translating such items from Japanese back to English is even more challenging, and of practical interest, as transliterated items make up the bulk of text phrases not found in bilingual dictionaries. We describe and evaluate a method for performing backwards transliterations by machine. This method uses a generative model, incorporating several distinct stages in the transliteration process.

  14. Quantification of perfusion and risk stratification by myocardial perfusion SPECT; Quantifizierung der Perfusion und Risikostratifizierung durch die Myokardperfusions-SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, Bernd [Ueberoertliche Gemeinschaft (GbR) fuer diagnostische und interventionelle Radiologie und Nuklearmedizin (DIRANUK), Bielefeld (Germany); Klinikum Bielefeld-Mitte (Germany). Klinik fuer Nuklearmedizin; Schaefer, W.M. [Kliniken Maria Hilf GmbH, Krankenhaus St. Franziskus, Moenchengladbach (Germany). Klinik fuer Nuklearmedizin

    2010-06-15

    Myocardial perfusion SPECT detects flow-limiting coronary artery disease with high sensitivity and specificity, enables semiquantification of severity and extensiveness of myocardial ischemia, and furthermore enables reliable assessment of future cardiac events independently of other clinical and diagnostic parameters. A normal myocardial perfusion SPECT is associated with a favorable prognosis and warrants restrictive patient management. Cardiac risk increases in relation to the severity of perfusion abnormalities. Differentiated analysis of quantitative parameters derived from myocardial perfusion SPECT provides effective risk stratification of patients with a large variety of risk factors. (orig.)

  15. A metabolic index of ischemic injury for perfusion-recovery of cadaveric rat livers.

    Directory of Open Access Journals (Sweden)

    Sinem Perk

    Full Text Available With over 110,000 patients waiting for organ transplantation, the current crisis in organ transplantation is based on a lack of donors after brain-death (DBD. A very large alternative pool of donor organs that remain untapped are the donors after cardiac death (DCD, recovered after cardiac activity has ceased and therefore sustained some ischemic injury. Machine perfusion has been proposed as a novel modality of organ preservation and treatment to render such cadaveric organs, and in particular livers, transplantable. Two key issues that remain unaddressed are how to assess whether a DCD liver is damaged beyond repair, and whether machine perfusion has rendered an injured organ sufficiently viable for transplantation. In this work, we present a metabolic analysis of the transient responses of cadaveric rat livers during normothermic machine perfusion (NMP, and develop an index of ischemia that enables evaluation of the organ ischemic injury level. Further, we perform a discriminant analysis to construct a classification algorithm with >0.98 specificity to identify whether a given perfused liver is ischemic or fresh, in effect a precursor for an index of transplantability and a basis for the use of statistical process control measures for automated feedback control of treatment of ischemic injury in DCD livers. The analyses yield an index based on squared prediction error (SPE as log(SPE >1.35 indicating ischemia. The differences between metabolic functions of fresh and ischemic livers during perfusion are outlined and the metabolites that varied significantly for ischemic livers are identified as ornithine, arginine, albumin and tyrosine.

  16. A metabolic index of ischemic injury for perfusion-recovery of cadaveric rat livers.

    Science.gov (United States)

    Perk, Sinem; Izamis, Maria-Louisa; Tolboom, Herman; Uygun, Basak; Berthiaume, Francois; Yarmush, Martin L; Uygun, Korkut

    2011-01-01

    With over 110,000 patients waiting for organ transplantation, the current crisis in organ transplantation is based on a lack of donors after brain-death (DBD). A very large alternative pool of donor organs that remain untapped are the donors after cardiac death (DCD), recovered after cardiac activity has ceased and therefore sustained some ischemic injury. Machine perfusion has been proposed as a novel modality of organ preservation and treatment to render such cadaveric organs, and in particular livers, transplantable. Two key issues that remain unaddressed are how to assess whether a DCD liver is damaged beyond repair, and whether machine perfusion has rendered an injured organ sufficiently viable for transplantation. In this work, we present a metabolic analysis of the transient responses of cadaveric rat livers during normothermic machine perfusion (NMP), and develop an index of ischemia that enables evaluation of the organ ischemic injury level. Further, we perform a discriminant analysis to construct a classification algorithm with >0.98 specificity to identify whether a given perfused liver is ischemic or fresh, in effect a precursor for an index of transplantability and a basis for the use of statistical process control measures for automated feedback control of treatment of ischemic injury in DCD livers. The analyses yield an index based on squared prediction error (SPE) as log(SPE) >1.35 indicating ischemia. The differences between metabolic functions of fresh and ischemic livers during perfusion are outlined and the metabolites that varied significantly for ischemic livers are identified as ornithine, arginine, albumin and tyrosine.

  17. Adenosine stress protocols for myocardial perfusion imaging

    Directory of Open Access Journals (Sweden)

    Baškot Branislav

    2008-01-01

    Full Text Available Background/Aim. Treadmill test combined with myocardial perfusion scintigraphy (MPS is a commonly used technique in the assessment of coronary artery disease. There are many patients, however, who may not be able to undergo treadmill test. Such patients would benefit from pharmacological stress procedures combined with MPS. The most commonly used pharmacological agents for cardiac stress are coronary vasodilatators (adenosine, dipyridamol and catecholamines. Concomitant low-level treadmill exercise with adenosine pharmacologic stress (AdenoEX during MPS has become commonly used in recent years. A number of studies have demonstrated a beneficial impact of AdenoEX protocol. The aim of the study was, besides introducing into practice the two types of protocols of pharmatological stress test with adenosine, as a preparation for MPS, to compare and monitor the frequency of their side effects to quality, acquisition, as well as to standardize the onset time of acquisition (diagnostic imaging for both protocols. Methods. A total of 130 patients underwent pharmacological stress test with adenosine (vasodilatator. In 108 of the patients we performed concomitant exercise (AdenoEX of low level (50W by a bicycle ergometar. In 28 of the patients we performed Adenosine abbreviated protocol (AdenoSCAN. Side effects of adenosine were followed and compared between the two kinds of protocols AdenoEX and AdenoSCAN. Also compared were image quality and suggested time of acquisition after the stress test. Results. Numerous side effects were found, but being short-lived they did not require any active interventions. The benefit of AdenoEX versus AdenoSCAN included decreased side effects (62% vs 87%, improved safety and patients tolerance, improved target-to-background ratios because of less subdiaphragmatic activity, earlier acquisition, and improved sensitivity. Conclusion. The safety and efficacy of adenosine pharmacological stress is even better with concomitant

  18. Dynamic contrast enhanced MRI for perfusion quantification

    DEFF Research Database (Denmark)

    Andersen, Irene Klærke

    2002-01-01

    to be more robust. Successful brain perfusion quantication based on R1 weighted signals has not previously been reported, due to the poor signal to noise ratio of the images. Initial experiments reported in this thesis show that improved sequence may provide more accurate perfusion estimates in the brain...... with the tissue IRF. To obtain the IRF, the tissue curves and the input curves are deconvolved and perfusion is related to the peak of IRF. In this thesis, a new method for deconvolution of perfusion data is introduced. It is the Gaussian process for deconvolution, GPD. The method is compared to singular value......Magnetic resonance imaging, during bolus passage of a paramagnetic contrast agent, is used world-wide to obtain parameters that reflect the pathological state of tissue. Abnormal perfusion occurs in diseases such as stoke and tumour. Consequently, perfusion quantication could have signi cant...

  19. Ultrasound perfusion signal processing for tumor detection

    Science.gov (United States)

    Kim, MinWoo; Abbey, Craig K.; Insana, Michael F.

    2016-04-01

    Enhanced blood perfusion in a tissue mass is an indication of neo-vascularity and a sign of a potential malignancy. Ultrasonic pulsed-Doppler imaging is a preferred modality for noninvasive monitoring of blood flow. However, the weak blood echoes and disorganized slow flow make it difficult to detect perfusion using standard methods without the expense and risk of contrast enhancement. Our research measures the efficiency of conventional power-Doppler (PD) methods at discriminating flow states by comparing measurement performance to that of an ideal discriminator. ROC analysis applied to the experimental results shows that power Doppler methods are just 30-50 % efficient at perfusion flows less than 1ml/min, suggesting an opportunity to improve perfusion assessment through signal processing. A new perfusion estimator is proposed by extending the statistical discriminator approach. We show that 2-D perfusion color imaging may be enhanced using this approach.

  20. Machine Protection

    CERN Document Server

    Schmidt, R

    2014-01-01

    The protection of accelerator equipment is as old as accelerator technology and was for many years related to high-power equipment. Examples are the protection of powering equipment from overheating (magnets, power converters, high-current cables), of superconducting magnets from damage after a quench and of klystrons. The protection of equipment from beam accidents is more recent. It is related to the increasing beam power of high-power proton accelerators such as ISIS, SNS, ESS and the PSI cyclotron, to the emission of synchrotron light by electron–positron accelerators and FELs, and to the increase of energy stored in the beam (in particular for hadron colliders such as LHC). Designing a machine protection system requires an excellent understanding of accelerator physics and operation to anticipate possible failures that could lead to damage. Machine protection includes beam and equipment monitoring, a system to safely stop beam operation (e.g. dumping the beam or stopping the beam at low energy) and an ...

  1. Quality assessment of a placental perfusion protocol

    DEFF Research Database (Denmark)

    Mathiesen, Line; Mose, Tina; Mørck, Thit Juul;

    2010-01-01

    the placental perfusion model in Copenhagen including control substances. The positive control substance antipyrine shows no difference in transport regardless of perfusion media used or of terms of delivery (n=59, pmarked dextran correspond with leakage criteria (...mlh(-1) from the fetal reservoir) when adding 2 (n=7) and 20mg (n=9) FITC-dextran/100ml fetal perfusion media. Success rate of the Copenhagen placental perfusions is provided in this study, including considerations and quality control parameters. Three checkpoints suggested to determine success rate...

  2. A Metabolic Index of Ischemic Injury for Perfusion-Recovery of Cadaveric Rat Livers

    OpenAIRE

    2011-01-01

    With over 110,000 patients waiting for organ transplantation, the current crisis in organ transplantation is based on a lack of donors after brain-death (DBD). A very large alternative pool of donor organs that remain untapped are the donors after cardiac death (DCD), recovered after cardiac activity has ceased and therefore sustained some ischemic injury. Machine perfusion has been proposed as a novel modality of organ preservation and treatment to render such cadaveric organs, and in partic...

  3. Analysis of machining and machine tools

    CERN Document Server

    Liang, Steven Y

    2016-01-01

    This book delivers the fundamental science and mechanics of machining and machine tools by presenting systematic and quantitative knowledge in the form of process mechanics and physics. It gives readers a solid command of machining science and engineering, and familiarizes them with the geometry and functionality requirements of creating parts and components in today’s markets. The authors address traditional machining topics, such as: single and multiple point cutting processes grinding components accuracy and metrology shear stress in cutting cutting temperature and analysis chatter They also address non-traditional machining, such as: electrical discharge machining electrochemical machining laser and electron beam machining A chapter on biomedical machining is also included. This book is appropriate for advanced undergraduate and graduate mechani cal engineering students, manufacturing engineers, and researchers. Each chapter contains examples, exercises and their solutions, and homework problems that re...

  4. Myocardial perfusion reserve compared with peripheral perfusion reserve : A [13N]ammonia PET study

    NARCIS (Netherlands)

    Scholtens, A. M.; Tio, R. A.; Willemsen, A.; Dierckx, R. A. J. O.; Boersma, Hendrikus; Zeebregts, C. J.; Glaudemans, A. W. J. M.; Slart, R. H. J. A.

    2011-01-01

    INTRODUCTION: [13N]ammonia PET allows quantification of myocardial perfusion. The similarity between peripheral flow and myocardial perfusion is unclear. We compared perfusion flow in the myocardium with the upper limb during rest and adenosine stress [13N]ammonia PET to establish whether peripheral

  5. Development of High-speed Machining Database with Case-based Reasoning

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Applying high-speed machining technology in shop floor has many benefits, such as manufacturing more accurate parts with better surface finishes. The selection of the appropriate machining parameters plays a very important role in the implementation of high-speed machining technology. The case-based reasoning is used in the developing of high-speed machining database to overcome the shortage of available high-speed cutting parameters in machining data handbooks and shop floors. The high-speed machining data...

  6. Myocardial Perfusion Reserve After a PET-Driven Revascularization Procedure : A Strong Prognostic Factor

    NARCIS (Netherlands)

    Slart, Riemer H. J. A.; Zeebregts, Clark J.; Hillege, Hans L.; de Sutter, Johan; Dierckx, Rudi A. J. O.; van Veldhuisen, Dirk J.; Zijlstra, Felix; Tio, Rene A.

    2011-01-01

    Not all patients treated on the basis of PET-proven viability benefit from revascularization. Myocardial perfusion reserve (MPR) predicts survival in patients not undergoing revascularization. In the present study, we investigated whether MPR is related to survival in ischemic heart disease (IHD) pa

  7. Lung perfusion and emphysema distribution affect the outcome of endobronchial valve therapy

    Science.gov (United States)

    Thomsen, Christian; Theilig, Dorothea; Herzog, Dominik; Poellinger, Alexander; Doellinger, Felix; Schreiter, Nils; Schreiter, Vera; Schürmann, Dirk; Temmesfeld-Wollbrueck, Bettina; Hippenstiel, Stefan; Suttorp, Norbert; Hubner, Ralf-Harto

    2016-01-01

    The exclusion of collateral ventilation (CV) and other factors affect the clinical success of endoscopic lung volume reduction (ELVR). However, despite its benefits, the outcome of ELVR remains difficult to predict. We investigated whether clinical success could be predicted by emphysema distribution assessed by computed tomography scan and baseline perfusion assessed by perfusion scintigraphy. Data from 57 patients with no CV in the target lobe (TL) were retrospectively analyzed after ELVR with valves. Pulmonary function tests (PFT), St George’s Respiratory Questionnaire (SGRQ), and 6-minute walk tests (6MWT) were performed on patients at baseline. The sample was grouped into high and low levels at the median of TL perfusion, ipsilateral nontarget lobe (INL) perfusion, and heterogeneity index (HI). These groups were analyzed for association with changes in outcome parameters from baseline to 3 months follow-up. Compared to baseline, patients showed significant improvements in PFT, SGRQ, and 6MWT (all P≤0.001). TL perfusion was not associated with changes in the outcome. High INL perfusion was significantly associated with increases in 6MWT (P=0.014), and high HI was associated with increases in forced expiratory volume in 1 second (FEV1), (P=0.012). Likewise, there were significant correlations for INL perfusion and improvement of 6MWT (r=0.35, P=0.03) and for HI and improvement in FEV1 (r=0.45, P=0.001). This study reveals new attributes that associate with positive outcomes for patient selection prior to ELVR. Patients with high perfusions in INL demonstrated greater improvements in 6MWT, while patients with high HI were more likely to respond in FEV1. PMID:27354783

  8. Transport of benzo[alpha]pyrene in the dually perfused human placenta perfusion model: effect of albumin in the perfusion medium

    DEFF Research Database (Denmark)

    Mathiesen, Line; Rytting, Erik; Mose, Tina

    2009-01-01

    P is lipophilic and studies using cell culture medium in 6-hr placenta perfusions showed minimal transport through the placenta. To increase the solubility of BaP in perfusion medium and to increase physiological relevance, perfusions were also performed with albumin added to the perfusion medium [2 and 30 mg...

  9. Long term perfusion system supporting adipogenesis.

    Science.gov (United States)

    Abbott, Rosalyn D; Raja, Waseem K; Wang, Rebecca Y; Stinson, Jordan A; Glettig, Dean L; Burke, Kelly A; Kaplan, David L

    2015-08-01

    Adipose tissue engineered models are needed to enhance our understanding of disease mechanisms and for soft tissue regenerative strategies. Perfusion systems generate more physiologically relevant and sustainable adipose tissue models, however adipocytes have unique properties that make culturing them in a perfusion environment challenging. In this paper we describe the methods involved in the development of two perfusion culture systems (2D and 3D) to test their applicability for long term in vitro adipogenic cultures. It was hypothesized that a silk protein biomaterial scaffold would provide a 3D framework, in combination with perfusion flow, to generate a more physiologically relevant sustainable adipose tissue engineered model than 2D cell culture. Consistent with other studies evaluating 2D and 3D culture systems for adipogenesis we found that both systems successfully model adipogenesis, however 3D culture systems were more robust, providing the mechanical structure required to contain the large, fragile adipocytes that were lost in 2D perfused culture systems. 3D perfusion also stimulated greater lipogenesis and lipolysis and resulted in decreased secretion of LDH compared to 2D perfusion. Regardless of culture configuration (2D or 3D) greater glycerol was secreted with the increased nutritional supply provided by perfusion of fresh media. These results are promising for adipose tissue engineering applications including long term cultures for studying disease mechanisms and regenerative approaches, where both acute (days to weeks) and chronic (weeks to months) cultivation are critical for useful insight.

  10. Personality factors correlate with regional cerebral perfusion.

    Science.gov (United States)

    O'Gorman, R L; Kumari, V; Williams, S C R; Zelaya, F O; Connor, S E J; Alsop, D C; Gray, J A

    2006-06-01

    There is an increasing body of evidence pointing to a neurobiological basis of personality. The purpose of this study was to investigate the biological bases of the major dimensions of Eysenck's and Cloninger's models of personality using a noninvasive magnetic resonance perfusion imaging technique in 30 young, healthy subjects. An unbiased voxel-based analysis was used to identify regions where the regional perfusion demonstrated significant correlation with any of the personality dimensions. Highly significant positive correlations emerged between extraversion and perfusion in the basal ganglia, thalamus, inferior frontal gyrus and cerebellum and between novelty seeking and perfusion in the cerebellum, cuneus and thalamus. Strong negative correlations emerged between psychoticism and perfusion in the basal ganglia and thalamus and between harm avoidance and perfusion in the cerebellar vermis, cuneus and inferior frontal gyrus. These observations suggest that personality traits are strongly associated with resting cerebral perfusion in a variety of cortical and subcortical regions and provide further evidence for the hypothesized neurobiological basis of personality. These results may also have important implications for functional neuroimaging studies, which typically rely on the modulation of cerebral hemodynamics for detection of task-induced activation since personality effects may influence the intersubject variability for both task-related activity and resting cerebral perfusion. This technique also offers a novel approach for the exploration of the neurobiological correlates of human personality.

  11. Sumatriptan and cerebral perfusion in healthy volunteers.

    Science.gov (United States)

    Scott, A K; Grimes, S; Ng, K; Critchley, M; Breckenridge, A M; Thomson, C; Pilgrim, A J

    1992-04-01

    1. The effect of sumatriptan on regional cerebral perfusion was studied in healthy volunteers. 2. Intravenous sumatriptan (2 mg) had no detectable effect on regional cerebral perfusion as measured using a SPECT system with 99technetiumm labelled hexemethylpropyleneamineoxime. 3. Sumatriptan had no effect on pulse, blood pressure or ECG indices. 4. All six volunteers experienced minor adverse effects during the intravenous infusion.

  12. Regional Cerebral Perfusion in Progressive Supranuclear Palsy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Won Yong; Lee, Ki Hyeong; Yoon, Byung Woo; Lee, Sang Bok; Jeon, Beom S. [Samsung Medical Center, Seoul (Korea, Republic of); Lee, Kyung Han; Lee, Myung Chul [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1996-03-15

    Progressive supranuclear palsy (PSP) is a Parkinson-plus syndrome characterized clinically by supranuclear ophthalmoplegia, pseudobulbar palsy, axial rigidity, bradykinesia, postural instability and dementia. Presence of dementia and lack of cortical histopathology suggest the derangement of cortical function by pathological changes in subcortical structures in PSP, which is supported by the pattern of behavioral changes and measurement of brain metabolism using positron emission tomography. This study was done to examine whether there are specific changes of regional cerebral perfusion in PSP and whether there is a correlation between severity of motor abnormaility and degree of changes in cerebral perfusion. We measured regional cerebral perfusion indices in 5 cortical and 2 subcortical areas in 6 patients with a clinical diagnosis of PSP and 6 healthy age and sex matched controls using Tc-99m-HMPAO SPECT. Compared with age and sex matched controls, only superior frontal regional perfusion index was significantly decreased in PSP (p<0.05). There was no correlation between the severity of the motor abnormality and any of the regional cerebral perfusion indices (p>0.05). We affirm the previous reports that perfusion in superior frontal cortex is decreased in PSP. Based on our results that there was no correlation between severity of motor abnormality and cerebral perfusion in the superior frontal cortex, nonmotoric symptoms including dementia needs to be looked at whether there is a correlation with the perfusion abnormality in superior frontal cortex

  13. Automation of printing machine

    OpenAIRE

    Sušil, David

    2016-01-01

    Bachelor thesis is focused on the automation of the printing machine and comparing the two types of printing machines. The first chapter deals with the history of printing, typesettings, printing techniques and various kinds of bookbinding. The second chapter describes the difference between sheet-fed printing machines and offset printing machines, the difference between two representatives of rotary machines, technological process of the products on these machines, the description of the mac...

  14. Methodology for ventilation/perfusion SPECT

    DEFF Research Database (Denmark)

    Bajc, Marika; Neilly, Brian; Miniati, Massimo;

    2010-01-01

    radiolabeled liquid aerosols are not restricted to the presence of obstructive lung disease. Radiolabeled macroaggregated human albumin is the imaging agent of choice for perfusion scintigraphy. An optimal combination of nuclide activities and acquisition times for ventilation and perfusion, collimators......Ventilation/perfusion single-photon emission computed tomography (V/Q SPECT) is the scintigraphic technique of choice for the diagnosis of pulmonary embolism and many other disorders that affect lung function. Data from recent ventilation studies show that the theoretic advantages of Technegas over......, and imaging matrix yields an adequate V/Q SPECT study in approximately 20 minutes of imaging time. The recommended protocol based on the patient remaining in an unchanged position during the initial ventilation study and the perfusion study allows presentation of matching ventilation and perfusion slices...

  15. Hypothermic perfusion with retrograde outflow during right hepatectomy is safe and feasible.

    Science.gov (United States)

    Reiniers, Megan J; Olthof, Pim B; van Golen, Rowan F; Heger, Michal; van Beek, Adriaan A; Meijer, Ben; Leen, René; van Kuilenburg, André B P; Mearadji, Banafsche; Bennink, Roelof J; Verheij, Joanne; van Gulik, Thomas M

    2017-07-01

    stay. The use of in situ hypothermic perfusion with retrograde outflow appears to be safe and feasible in selected patients with healthy liver parenchyma and may benefit early functional liver regeneration. Future applications of in situ hypothermic perfusion with retrograde outflow include patients with damaged liver parenchyma who would require major hepatic resection with a prolonged vascular inflow occlusion duration. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Cerebral perfusion SPECT in transient ischemic attack

    Energy Technology Data Exchange (ETDEWEB)

    You, D.-L. E-mail: dlyou@mail.kfcc.org.tw; Shieh, F.-Y.; Tzen, K.-Y.; Tsai, M.-F.; Kao, P.-F

    2000-04-01

    Purpose: The purpose of our study is to evaluate the efficacy of cerebral perfusion single photon emission computerized tomography (SPECT) in patients with transient ischemic attack (TIA). Methods: Thirty-seven patients with TIA were collected for study. All patients had transient focal neurological symptoms or signs with complete recovery within 24 h after onset. The patients underwent cerebral perfusion SPECT between 6 h and 11 days after onset, with 10 cases performed within 24 h (group A), nine cases performed between 1 and 3 days (group B), 11 cases performed between 3 and 5 days (group C), and seven cases performed after more than 5 days (group D). A semi-quantitative method was used for analyzing the SPECT data, and the difference ratios between lesion side and contralateral normal side were calculated on each pair of regions of interest. Results: In total, 78.4% (29/37) of patients had reduced perfusion in the cerebral cortical regions or deep nuclei, and the regions with reduced perfusion corresponded with clinical presentations of the patients. The abnormal rate with reduced perfusion was 90.0% in group A, 77.8% in group B, 72.7% in group C and 71.4% in group D. Cross cerebellar diaschisis (CCD) was present in seven patients, and all of the primary cerebral perfusion defects of these patients were located at the territory of left or right middle cerebral artery. Conclusion: Cerebral perfusion SPECT is a potential tool to detect cerebral perfusion defects and CCD in patients with TIA. Although the perfusion defect may persist more than 5 days after onset, we suggest cerebral perfusion SPECT should be performed as soon as possible.

  17. Game-powered machine learning.

    Science.gov (United States)

    Barrington, Luke; Turnbull, Douglas; Lanckriet, Gert

    2012-04-24

    Searching for relevant content in a massive amount of multimedia information is facilitated by accurately annotating each image, video, or song with a large number of relevant semantic keywords, or tags. We introduce game-powered machine learning, an integrated approach to annotating multimedia content that combines the effectiveness of human computation, through online games, with the scalability of machine learning. We investigate this framework for labeling music. First, a socially-oriented music annotation game called Herd It collects reliable music annotations based on the "wisdom of the crowds." Second, these annotated examples are used to train a supervised machine learning system. Third, the machine learning system actively directs the annotation games to collect new data that will most benefit future model iterations. Once trained, the system can automatically annotate a corpus of music much larger than what could be labeled using human computation alone. Automatically annotated songs can be retrieved based on their semantic relevance to text-based queries (e.g., "funky jazz with saxophone," "spooky electronica," etc.). Based on the results presented in this paper, we find that actively coupling annotation games with machine learning provides a reliable and scalable approach to making searchable massive amounts of multimedia data.

  18. Socioeconomic benefits

    African Journals Online (AJOL)

    User

    perception on the benefits of shade trees in coffee production systems in southwestern part of Ethiopia. ... with growing coffee without shade tree plants that included stunted growth which ultimately ...... coffee producers' price risk. J. Inter.

  19. Medicaid Benefits

    Science.gov (United States)

    ... Benefits Close About Us Messages from CMCS Program History Leadership Organization Visit CMS Contact Us Close Home > Medicaid > ... for Coverage LTSS Prescription Drugs About Us Program History Leadership Organization Visit CMS Contact Us State Medicaid & CHIP ...

  20. Electrical machines mathematical fundamentals of machine topologies

    CERN Document Server

    Gerling, Dieter

    2015-01-01

    Electrical Machines and Drives play a powerful role in industry with an ever increasing importance. This fact requires the understanding of machine and drive principles by engineers of many different disciplines. Therefore, this book is intended to give a comprehensive deduction of these principles. Special attention is given to the precise mathematical derivation of the necessary formulae to calculate machines and drives and to the discussion of simplifications (if applied) with the associated limits. The book shows how the different machine topologies can be deduced from general fundamentals, and how they are linked together. This book addresses graduate students, researchers, and developers of Electrical Machines and Drives, who are interested in getting knowledge about the principles of machine and drive operation and in detecting the mathematical and engineering specialties of the different machine and drive topologies together with their mutual links. The detailed - but nevertheless compact - mat...

  1. Laser machining of advanced materials

    CERN Document Server

    Dahotre, Narendra B

    2011-01-01

    Advanced materialsIntroductionApplicationsStructural ceramicsBiomaterials CompositesIntermetallicsMachining of advanced materials IntroductionFabrication techniquesMechanical machiningChemical Machining (CM)Electrical machiningRadiation machining Hybrid machiningLaser machiningIntroductionAbsorption of laser energy and multiple reflectionsThermal effectsLaser machining of structural ceramicsIntrodu

  2. Brain perfusion-CT in acute stroke patients

    Energy Technology Data Exchange (ETDEWEB)

    Wintermark, M. [Dept. of Radiology, Univ. of California, San Francisco (UCSF), CA (United States)

    2005-11-15

    The role of neuro-imaging in the evaluation of acute stroke has changed dramatically in the past decade. Previously, neuro-imaging was used in this setting to provide anatomic imaging that indicated the presence or absence of acute cerebral ischemia and excluded lesions that produce symptoms or signs mimicking those of stroke, such as hemorrhage and neoplasms. More recently, the introduction of thrombolysis has changed the goals of neuro-imaging from providing solely anatomic information to providing physiologic information that could help to determine which patients might benefit from therapy. In particular, significant emphasis has been placed on the delineation of the ischemic penumbra, also called tissue at risk. Modern CT survey, consisting of three indissociable elements: noncontrast CT (NCT) of course, perfusion-CT (PCT) and CT-angiography (CTA), fulfill all the requirements for hyper-acute stroke imaging. CTA can define the occlusion site, depict arterial dissection, grade collateral blood flow, and characterize atherosclerotic disease, whereas PCT accurately delineates the infarct core and the ischemic penumbra. CT offers a number of practical advantages over other cerebral perfusion imaging methods, including its wide availability. Using PCT and CTA to define new individualized strategies for acute reperfusion will allow more acute stroke patients to benefit from thrombolytic therapy. (orig.)

  3. The deleuzian abstract machines

    DEFF Research Database (Denmark)

    Werner Petersen, Erik

    2005-01-01

    production. In Kafka: Toward a Minor Literature, Deleuze and Guatari gave the most comprehensive explanation to the abstract machine in the work of art. Like the war-machines of Virilio, the Kafka-machine operates in three gears or speeds. Furthermore, the machine is connected to spatial diagrams...

  4. Hemodialysis machine technology: a global overview.

    Science.gov (United States)

    Polaschegg, Hans-Dietrich

    2010-11-01

    The market for hemodialysis machines, the background, the current products of manufacturers and the features of hemodialysis machines are described in this article. In addition to the established companies and their products, Chinese manufacturers, and new developments for home hemodialysis, are outlined based on publications available on the internet and patent applications. Here, a critical review of the state of the art questions the medical usefulness of high-tech developments, compared with the benefits of more frequent and/or longer dialysis treatment with comparable simple machines.

  5. Brain/language relationships identified with diffusion and perfusion MRI: Clinical applications in neurology and neurosurgery.

    Science.gov (United States)

    Hillis, Argye E

    2005-12-01

    Diffusion and perfusion MRI have contributed to stroke management by identifying patients with tissue "at risk" for further damage in acute stroke. However, the potential usefulness of these imaging modalities, along with diffusion tensor imaging, can be expanded by using these imaging techniques with concurrent assessment of language and other cognitive skills to identify the specific cognitive deficits that are associated with diffusion and perfusion abnormalities in particular brain regions. This paper illustrates how this combined behavioral and imaging methodology can yield information that is useful for predicting specific positive effects of intervention to restore blood flow in hypoperfused regions of brain identified with perfusion MRI, and for predicting negative effects of resection of particular brain regions or fiber bundles. Such data allow decisions about neurological and neurosurgical interventions to be based on specific risks and benefits in terms of functional consequences.

  6. Fed-batch and perfusion culture processes: economic, environmental, and operational feasibility under uncertainty.

    Science.gov (United States)

    Pollock, James; Ho, Sa V; Farid, Suzanne S

    2013-01-01

    economic and operational benefits that affect the choice between ATF perfusion and fed-batch strategies. Copyright © 2012 Wiley Periodicals, Inc.

  7. Kinematic Analysis of a New Parallel Machine Tool: the Orthoglide

    CERN Document Server

    Wenger, Philippe

    2007-01-01

    This paper describes a new parallel kinematic architecture for machining applications: the orthoglide. This machine features three fixed parallel linear joints which are mounted orthogonally and a mobile platform which moves in the Cartesian x-y-z space with fixed orientation. The main interest of the orthoglide is that it takes benefit from the advantages of the popular PPP serial machines (regular Cartesian workspace shape and uniform performances) as well as from the parallel kinematic arrangement of the links (less inertia and better dynamic performances), which makes the orthoglide well suited to high-speed machining applications. Possible extension of the orthoglide to 5-axis machining is also investigated.

  8. A New Three-DOF Parallel Mechanism: Milling Machine Applications

    CERN Document Server

    Chablat, Damien

    2000-01-01

    This paper describes a new parallel kinematic architecture for machining applications, namely, the orthoglide. This machine features three fixed parallel linear joints which are mounted orthogonally and a mobile platform which moves in the Cartesian x-y-z space with fixed orientation. The main interest of the orthoglide is that it takes benefit from the advantages of the popular PPP serial machines (regular Cartesian workspace shape and uniform performances) as well as from the parallel kinematic arrangement of the links (less inertia and better dynamic performances), which makes the orthoglide well suited to high-speed machining applications. Possible extension of the orthoglide to 5-axis machining is also investigated.

  9. Quantification of myocardial perfusion based on signal intensity of flow sensitized MRI

    Science.gov (United States)

    Abeykoon, Sumeda B.

    maximum percentage deviation is about 5%. Then the SI-method was used in comparison to a delayed enhanced method to qualitatively and quantitatively assess perfusion deficits in an ischemia-reperfusion (IR) mouse model. The infarcted region of the perfusion map is comparable to the hyper intense region of the delayed enhanced image of the IR mouse. The SI method also used to record a chronological comparison of perfusion on delta sarcoglycan null (DSG) mice. Perfusion of DSG and wild-type (WT) mice at ages of 12 weeks and 32 weeks were compared and percentage change of perfusion was estimated. The result shows that in DSG mice perfusion changes considerably. Finally, the SI method was implemented on a 3 Tesla Philip scanner by modifying to data acquisition method. The perfusion obtained in this is consistent with literature values but further adjustment of pulse sequence and modification of numerical solution is needed. The most important benefit of the SI method is that it reduces scan time 30%--40% and lessens motion artifacts of images compared to the T1 method. This study demonstrates that the signal intensity-based ASL method is a robust alternative to the conventional T1-method.

  10. Bubble dynamics in perfused tissue undergoing decompression.

    Science.gov (United States)

    Meisel, S; Nir, A; Kerem, D

    1981-02-01

    A mathematical model describing bubble dynamics in a perfused tissue undergoing decompression is presented, taking into account physical expansion and inward diffusion from surrounding supersaturated tissue as growth promoting factors and tissue gas elimination by perfusion, tissue elasticity, surface tension and inherent unsaturation as resolving driving forces. The expected behavior after a step reduction of pressure of a bubble initially existing in the tissue, displaying both growth and resolution has been demonstrated. A strong perfusion-dependence of bubble resolution time at low perfusion rates is apparent. The model can account for various exposure pressures and saturation fractions of any inert gas-tissue combination for which a set of physical and physiological parameters is available.

  11. Computed Tomography (CT) Perfusion in Abdominal Cancer

    DEFF Research Database (Denmark)

    Hansen, Martin Lundsgaard; Norling, Rikke; Lauridsen, Carsten

    2013-01-01

    Computed Tomography (CT) Perfusion is an evolving method to visualize perfusion in organs and tissue. With the introduction of multidetector CT scanners, it is now possible to cover up to 16 cm in one rotation, and thereby making it possible to scan entire organs such as the liver with a fixed...... table position. Advances in reconstruction algorithms make it possible to reduce the radiation dose for each examination to acceptable levels. Regarding abdominal imaging, CT perfusion is still considered a research tool, but several studies have proven it as a reliable non-invasive technique...... for assessment of vascularity. CT perfusion has also been used for tumor characterization, staging of disease, response evaluation of newer drugs targeted towards angiogenesis and as a method for early detection of recurrence after radiation and embolization. There are several software solutions available...

  12. Dynamic contrast enhanced MRI for perfusion quantification

    DEFF Research Database (Denmark)

    Andersen, Irene Klærke

    2002-01-01

    to be more robust. Successful brain perfusion quantication based on R1 weighted signals has not previously been reported, due to the poor signal to noise ratio of the images. Initial experiments reported in this thesis show that improved sequence may provide more accurate perfusion estimates in the brain....... Images obtained during bolus passage are noisy, and the bolus is not an ideal impulse as it reaches the brain. The brain response to an ideal impulse is called the residual impulse response function, IRF. Thus, the measured tissue curves are expressed as the convolution of the input function...... with the tissue IRF. To obtain the IRF, the tissue curves and the input curves are deconvolved and perfusion is related to the peak of IRF. In this thesis, a new method for deconvolution of perfusion data is introduced. It is the Gaussian process for deconvolution, GPD. The method is compared to singular value...

  13. Improving perfusion quantification in arterial spin labeling for delayed arrival times by using optimized acquisition schemes

    Energy Technology Data Exchange (ETDEWEB)

    Kramme, Johanna [Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen (Germany); Univ. Bremen (Germany). Faculty of Physics and Electronics; Gregori, Johannes [mediri GmbH, Heidelberg (Germany); Diehl, Volker [Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen (Germany); ZEMODI (Zentrum fuer morderne Diagnostik), Bremen (Germany); Madai, Vince I.; Sobesky, Jan [Charite-Universitaetsmedizin Berlin (Germany). Center for Stroke Research Berlin (CSB); Charite-Universitaetsmedizin Berlin (Germany). Dept. of Neurology; Samson-Himmelstjerna, Frederico C. von [Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen (Germany); Charite-Universitaetsmedizin Berlin (Germany). Center for Stroke Research Berlin (CSB); Charite-Universitaetsmedizin Berlin (Germany). Dept. of Neurology; Lentschig, Markus [ZEMODI (Zentrum fuer morderne Diagnostik), Bremen (Germany); Guenther, Matthias [Fraunhofer MEVIS-Institute for Medical Image Computing, Bremen (Germany); Univ. Bremen (Germany). Faculty of Physics and Electronics; mediri GmbH, Heidelberg (Germany)

    2015-07-01

    The improvement in Arterial Spin Labeling (ASL) perfusion quantification, especially for delayed bolus arrival times (BAT), with an acquisition redistribution scheme mitigating the T1 decay of the label in multi-TI ASL measurements is investigated. A multi inflow time (TI) 3D-GRASE sequence is presented which adapts the distribution of acquisitions accordingly, by keeping the scan time constant. The MR sequence increases the number of averages at long TIs and decreases their number at short TIs and thus compensating the T1 decay of the label. The improvement of perfusion quantification is evaluated in simulations as well as in-vivo in healthy volunteers and patients with prolonged BATs due to age or steno-occlusive disease. The improvement in perfusion quantification depends on BAT. At healthy BATs the differences are small, but become larger for longer BATs typically found in certain diseases. The relative error of perfusion is improved up to 30% at BATs > 1500 ms in comparison to the standard acquisition scheme. This adapted acquisition scheme improves the perfusion measurement in comparison to standard multi-TI ASL implementations. It provides relevant benefit in clinical conditions that cause prolonged BATs and is therefore of high clinical relevance for neuroimaging of steno-occlusive diseases.

  14. Vicarious Audiovisual Learning in Perfusion Education

    Science.gov (United States)

    Rath, Thomas E.; Holt, David W.

    2010-01-01

    Abstract: Perfusion technology is a mechanical and visual science traditionally taught with didactic instruction combined with clinical experience. It is difficult to provide perfusion students the opportunity to experience difficult clinical situations, set up complex perfusion equipment, or observe corrective measures taken during catastrophic events because of patient safety concerns. Although high fidelity simulators offer exciting opportunities for future perfusion training, we explore the use of a less costly low fidelity form of simulation instruction, vicarious audiovisual learning. Two low fidelity modes of instruction; description with text and a vicarious, first person audiovisual production depicting the same content were compared. Students (n = 37) sampled from five North American perfusion schools were prospectively randomized to one of two online learning modules, text or video. These modules described the setup and operation of the MAQUET ROTAFLOW standalone centrifugal console and pump. Using a 10 question multiple-choice test, students were assessed immediately after viewing the module (test #1) and then again 2 weeks later (test #2) to determine cognition and recall of the module content. In addition, students completed a questionnaire assessing the learning preferences of today’s perfusion student. Mean test scores from test #1 for video learners (n = 18) were significantly higher (88.89%) than for text learners (n = 19) (74.74%), (p perfusion training on subjects such as equipment setup and operation. Video learning appears to improve cognition and retention of learned content and may play an important role in how we teach perfusion in the future, as simulation technology becomes more prevalent. PMID:21313929

  15. Measurement of myocardial perfusion using magnetic resonance

    DEFF Research Database (Denmark)

    Fritz-Hansen, T.; Jensen, L.T.; Larsson, H.B.

    2008-01-01

    Cardiac magnetic resonance imaging (MRI) has evolved rapidly. Recent developments have made non-invasive quantitative myocardial perfusion measurements possible. MRI is particularly attractive due to its high spatial resolution and because it does not involve ionising radiation. This paper reviews...... myocardial perfusion imaging with MR contrast agents: methods, validation and experiences from clinical studies. Unresolved issues still restrict the use of these techniques to research although clinical applications are within reach Udgivelsesdato: 2008/12/8...

  16. Perfusion magnetic resonance imaging of the liver

    Institute of Scientific and Technical Information of China (English)

    Choon; Hua; Thng; Tong; San; Koh; David; J; Collins; Dow; Mu; Koh

    2010-01-01

    Perfusion magnetic resonance imaging (MRI) studies quantify the microcirculatory status of liver parenchyma and liver lesions, and can be used for the detection of liver metastases, assessing the effectiveness of antiangiogenic therapy, evaluating tumor viability after anticancer therapy or ablation, and diagnosis of liver cirrhosis and its severity. In this review, we discuss the basic concepts of perfusion MRI using tracer kinetic modeling, the common kinetic models applied for analyses, the MR scanning t...

  17. Perfusion visualization and analysis for pulmonary embolism

    Science.gov (United States)

    Vaz, Michael S.; Kiraly, Atilla P.; Naidich, David P.; Novak, Carol L.

    2005-04-01

    Given the nature of pulmonary embolism (PE), timely and accurate diagnosis is critical. Contrast enhanced high-resolution CT images allow physicians to accurately identify segmental and sub-segmental emboli. However, it is also important to assess the effect of such emboli on the blood flow in the lungs. Expanding upon previous research, we propose a method for 3D visualization of lung perfusion. The proposed method allows users to examine perfusion throughout the entire lung volume at a single glance, with areas of diminished perfusion highlighted so that they are visible independent of the viewing location. This may be particularly valuable for better accuracy in assessing the extent of hemodynamic alterations resulting from pulmonary emboli. The method also facilitates user interaction and may help identify small peripheral sub-segmental emboli otherwise overlooked. 19 patients referred for possible PE were evaluated by CT following the administration of IV contrast media. An experienced thoracic radiologist assessed the 19 datasets with 17 diagnosed as being positive for PE with multiple emboli. Since anomalies in lung perfusion due to PE can alter the distribution of parenchymal densities, we analyzed features collected from histograms of the computed perfusion maps and demonstrate their potential usefulness as a preliminary test to suggest the presence of PE. These histogram features also offer the possibility of distinguishing distinct patterns associated with chronic PE and may even be useful for further characterization of changes in perfusion or overall density resulting from associated conditions such as pneumonia or diffuse lung disease.

  18. Machine tool structures

    CERN Document Server

    Koenigsberger, F

    1970-01-01

    Machine Tool Structures, Volume 1 deals with fundamental theories and calculation methods for machine tool structures. Experimental investigations into stiffness are discussed, along with the application of the results to the design of machine tool structures. Topics covered range from static and dynamic stiffness to chatter in metal cutting, stability in machine tools, and deformations of machine tool structures. This volume is divided into three sections and opens with a discussion on stiffness specifications and the effect of stiffness on the behavior of the machine under forced vibration c

  19. Cost-Effectiveness of Hypothermic Machine Preservation Versus Static Cold Storage in Renal Transplantation

    NARCIS (Netherlands)

    Groen, H.; Moers, C.; Smits, J. M.; Treckmann, J.; Monbaliu, D.; Rahmel, A.; Paul, A.; Pirenne, J.; Ploeg, R. J.; Buskens, E.

    2012-01-01

    Static cold storage (CS) is the most widely used organ preservation method for deceased donor kidney grafts but there is increasing evidence that hypothermic machine perfusion (MP) may result in better outcome after transplantation. We performed an economic evaluation of MP versus CS alongside a mul

  20. Twente Optical Perfusion Camera: system overview and performance for video rate laser Doppler perfusion imaging

    NARCIS (Netherlands)

    M. Draijer; E. Hondebrink; T. van Leeuwen; W. Steenbergen

    2009-01-01

    We present the Twente Optical Perfusion Camera (TOPCam), a novel laser Doppler Perfusion Imager based on CMOS technology. The tissue under investigation is illuminated and the resulting dynamic speckle pattern is recorded with a high speed CMOS camera. Based on an overall analysis of the signal-to-n

  1. Twente Optical Perfusion Camera: system overview and performance for video rate laser Doppler perfusion imaging

    NARCIS (Netherlands)

    Draijer, M.; Hondebrink, E.; van Leeuwen, T.; Steenbergen, W.

    2009-01-01

    We present the Twente Optical Perfusion Camera (TOPCam), a novel laser Doppler Perfusion Imager based on CMOS technology. The tissue under investigation is illuminated and the resulting dynamic speckle pattern is recorded with a high speed CMOS camera. Based on an overall analysis of the

  2. Regional cortical hyper perfusion on perfusion CT during postical motor deficit: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Baik, Hye Jin [Dept. of Radiology, Haeundae Paik Hospital, Inje University College of Medicine, Busan (Korea, Republic of)

    2013-08-15

    Postictal neurologic deficit is a well-known complication mimicking the manifestation of a stroke. We present a case of a patient with clinical evidence of Todd's paralysis correlating with reversible postictal parenchymal changes on perfusion CT and magnetic resonance (MR) imaging. In this case, perfusion CT and MR imaging were helpful in the differential diagnosis of stroke-mimicking conditions.

  3. Design of Demining Machines

    CERN Document Server

    Mikulic, Dinko

    2013-01-01

    In constant effort to eliminate mine danger, international mine action community has been developing safety, efficiency and cost-effectiveness of clearance methods. Demining machines have become necessary when conducting humanitarian demining where the mechanization of demining provides greater safety and productivity. Design of Demining Machines describes the development and testing of modern demining machines in humanitarian demining.   Relevant data for design of demining machines are included to explain the machinery implemented and some innovative and inspiring development solutions. Development technologies, companies and projects are discussed to provide a comprehensive estimate of the effects of various design factors and to proper selection of optimal parameters for designing the demining machines.   Covering the dynamic processes occurring in machine assemblies and their components to a broader understanding of demining machine as a whole, Design of Demining Machines is primarily tailored as a tex...

  4. Applied machining technology

    CERN Document Server

    Tschätsch, Heinz

    2010-01-01

    Machining and cutting technologies are still crucial for many manufacturing processes. This reference presents all important machining processes in a comprehensive and coherent way. It includes many examples of concrete calculations, problems and solutions.

  5. Machining with abrasives

    CERN Document Server

    Jackson, Mark J

    2011-01-01

    Abrasive machining is key to obtaining the desired geometry and surface quality in manufacturing. This book discusses the fundamentals and advances in the abrasive machining processes. It provides a complete overview of developing areas in the field.

  6. Women, Men, and Machines.

    Science.gov (United States)

    Form, William; McMillen, David Byron

    1983-01-01

    Data from the first national study of technological change show that proportionately more women than men operate machines, are more exposed to machines that have alienating effects, and suffer more from the negative effects of technological change. (Author/SSH)

  7. Machine medical ethics

    CERN Document Server

    Pontier, Matthijs

    2015-01-01

    The essays in this book, written by researchers from both humanities and sciences, describe various theoretical and experimental approaches to adding medical ethics to a machine in medical settings. Medical machines are in close proximity with human beings, and getting closer: with patients who are in vulnerable states of health, who have disabilities of various kinds, with the very young or very old, and with medical professionals. In such contexts, machines are undertaking important medical tasks that require emotional sensitivity, knowledge of medical codes, human dignity, and privacy. As machine technology advances, ethical concerns become more urgent: should medical machines be programmed to follow a code of medical ethics? What theory or theories should constrain medical machine conduct? What design features are required? Should machines share responsibility with humans for the ethical consequences of medical actions? How ought clinical relationships involving machines to be modeled? Is a capacity for e...

  8. Brain versus Machine Control.

    Directory of Open Access Journals (Sweden)

    Jose M Carmena

    2004-12-01

    Full Text Available Dr. Octopus, the villain of the movie "Spiderman 2", is a fusion of man and machine. Neuroscientist Jose Carmena examines the facts behind this fictional account of a brain- machine interface

  9. Effects of Steroid Hormones on Sex Differences in Cerebral Perfusion.

    Science.gov (United States)

    Ghisleni, Carmen; Bollmann, Steffen; Biason-Lauber, Anna; Poil, Simon-Shlomo; Brandeis, Daniel; Martin, Ernst; Michels, Lars; Hersberger, Martin; Suckling, John; Klaver, Peter; O'Gorman, Ruth L

    2015-01-01

    Sex differences in the brain appear to play an important role in the prevalence and progression of various neuropsychiatric disorders, but to date little is known about the cerebral mechanisms underlying these differences. One widely reported finding is that women demonstrate higher cerebral perfusion than men, but the underlying cause of this difference in perfusion is not known. This study investigated the putative role of steroid hormones such as oestradiol, testosterone, and dehydroepiandrosterone sulphate (DHEAS) as underlying factors influencing cerebral perfusion. We acquired arterial spin labelling perfusion images of 36 healthy adult subjects (16 men, 20 women). Analyses on average whole brain perfusion levels included a multiple regression analysis to test for the relative impact of each hormone on the global perfusion. Additionally, voxel-based analyses were performed to investigate the sex difference in regional perfusion as well as the correlations between local perfusion and serum oestradiol, testosterone, and DHEAS concentrations. Our results replicated the known sex difference in perfusion, with women showing significantly higher global and regional perfusion. For the global perfusion, DHEAS was the only significant predictor amongst the steroid hormones, showing a strong negative correlation with cerebral perfusion. The voxel-based analyses revealed modest sex-dependent correlations between local perfusion and testosterone, in addition to a strong modulatory effect of DHEAS in cortical, subcortical, and cerebellar regions. We conclude that DHEAS in particular may play an important role as an underlying factor driving the difference in cerebral perfusion between men and women.

  10. Effects of Steroid Hormones on Sex Differences in Cerebral Perfusion.

    Directory of Open Access Journals (Sweden)

    Carmen Ghisleni

    Full Text Available Sex differences in the brain appear to play an important role in the prevalence and progression of various neuropsychiatric disorders, but to date little is known about the cerebral mechanisms underlying these differences. One widely reported finding is that women demonstrate higher cerebral perfusion than men, but the underlying cause of this difference in perfusion is not known. This study investigated the putative role of steroid hormones such as oestradiol, testosterone, and dehydroepiandrosterone sulphate (DHEAS as underlying factors influencing cerebral perfusion. We acquired arterial spin labelling perfusion images of 36 healthy adult subjects (16 men, 20 women. Analyses on average whole brain perfusion levels included a multiple regression analysis to test for the relative impact of each hormone on the global perfusion. Additionally, voxel-based analyses were performed to investigate the sex difference in regional perfusion as well as the correlations between local perfusion and serum oestradiol, testosterone, and DHEAS concentrations. Our results replicated the known sex difference in perfusion, with women showing significantly higher global and regional perfusion. For the global perfusion, DHEAS was the only significant predictor amongst the steroid hormones, showing a strong negative correlation with cerebral perfusion. The voxel-based analyses revealed modest sex-dependent correlations between local perfusion and testosterone, in addition to a strong modulatory effect of DHEAS in cortical, subcortical, and cerebellar regions. We conclude that DHEAS in particular may play an important role as an underlying factor driving the difference in cerebral perfusion between men and women.

  11. GPU-accelerated voxelwise hepatic perfusion quantification.

    Science.gov (United States)

    Wang, H; Cao, Y

    2012-09-07

    Voxelwise quantification of hepatic perfusion parameters from dynamic contrast enhanced (DCE) imaging greatly contributes to assessment of liver function in response to radiation therapy. However, the efficiency of the estimation of hepatic perfusion parameters voxel-by-voxel in the whole liver using a dual-input single-compartment model requires substantial improvement for routine clinical applications. In this paper, we utilize the parallel computation power of a graphics processing unit (GPU) to accelerate the computation, while maintaining the same accuracy as the conventional method. Using compute unified device architecture-GPU, the hepatic perfusion computations over multiple voxels are run across the GPU blocks concurrently but independently. At each voxel, nonlinear least-squares fitting the time series of the liver DCE data to the compartmental model is distributed to multiple threads in a block, and the computations of different time points are performed simultaneously and synchronically. An efficient fast Fourier transform in a block is also developed for the convolution computation in the model. The GPU computations of the voxel-by-voxel hepatic perfusion images are compared with ones by the CPU using the simulated DCE data and the experimental DCE MR images from patients. The computation speed is improved by 30 times using a NVIDIA Tesla C2050 GPU compared to a 2.67 GHz Intel Xeon CPU processor. To obtain liver perfusion maps with 626 400 voxels in a patient's liver, it takes 0.9 min with the GPU-accelerated voxelwise computation, compared to 110 min with the CPU, while both methods result in perfusion parameters differences less than 10(-6). The method will be useful for generating liver perfusion images in clinical settings.

  12. Pulmonary artery perfusion versus no pulmonary perfusion during cardiopulmonary bypass in patients with COPD

    DEFF Research Database (Denmark)

    Buggeskov, Katrine B; Sundskard, Martin M; Jonassen, Thomas

    2016-01-01

    INTRODUCTION: Absence of pulmonary perfusion during cardiopulmonary bypass (CPB) may be associated with reduced postoperative oxygenation. Effects of active pulmonary artery perfusion were explored in patients with chronic obstructive pulmonary disease (COPD) undergoing cardiac surgery. METHODS: 90...... patients were randomised to receive pulmonary artery perfusion during CPB with either oxygenated blood (n=30) or histidine-tryptophan-ketoglutarate (HTK) solution (n=29) compared with no pulmonary perfusion (n=31). The coprimary outcomes were the inverse oxygenation index compared at 21 hours after...... starting CPB and longitudinally in a mixed-effects model (MEM). Secondary outcomes were tracheal intubation time, serious adverse events, mortality, days alive outside the intensive care unit (ICU) and outside the hospital. RESULTS: 21 hours after starting CPB patients receiving pulmonary artery perfusion...

  13. Lung perfusion and emphysema distribution affect the outcome of endobronchial valve therapy

    Directory of Open Access Journals (Sweden)

    Thomsen C

    2016-06-01

    Full Text Available Christian Thomsen,1 Dorothea Theilig,2 Dominik Herzog,1 Alexander Poellinger,2 Felix Doellinger,2 Nils Schreiter,3 Vera Schreiter,2 Dirk Schürmann,1 Bettina Temmesfeld-Wollbrueck,1 Stefan Hippenstiel,1 Norbert Suttorp,1 Ralf-Harto Hubner1 1Department of Internal Medicine/Infectious Diseases and Respiratory Medicine, 2Institute of Radiology, 3Institute of Nuclear Medicine, Charité – Universitätsmedizin Berlin, Berlin, Germany Abstract: The exclusion of collateral ventilation (CV and other factors affect the clinical success of endoscopic lung volume reduction (ELVR. However, despite its benefits, the outcome of ELVR remains difficult to predict. We investigated whether clinical success could be predicted by emphysema distribution assessed by computed tomography scan and baseline perfusion assessed by perfusion scintigraphy. Data from 57 patients with no CV in the target lobe (TL were retrospectively analyzed after ELVR with valves. Pulmonary function tests (PFT, St George’s Respiratory Questionnaire (SGRQ, and 6-minute walk tests (6MWT were performed on patients at baseline. The sample was grouped into high and low levels at the median of TL perfusion, ipsilateral nontarget lobe (INL perfusion, and heterogeneity index (HI. These groups were analyzed for association with changes in outcome parameters from baseline to 3 months follow-up. Compared to baseline, patients showed significant improvements in PFT, SGRQ, and 6MWT (all P≤0.001. TL perfusion was not associated with changes in the outcome. High INL perfusion was significantly associated with increases in 6MWT (P=0.014, and high HI was associated with increases in forced expiratory volume in 1 second (FEV1, (P=0.012. Likewise, there were significant correlations for INL perfusion and improvement of 6MWT (r=0.35, P=0.03 and for HI and improvement in FEV1 (r=0.45, P=0.001. This study reveals new attributes that associate with positive outcomes for patient selection prior to ELVR

  14. A Universal Reactive Machine

    DEFF Research Database (Denmark)

    Andersen, Henrik Reif; Mørk, Simon; Sørensen, Morten U.

    1997-01-01

    Turing showed the existence of a model universal for the set of Turing machines in the sense that given an encoding of any Turing machine asinput the universal Turing machine simulates it. We introduce the concept of universality for reactive systems and construct a CCS processuniversal...

  15. Usefulness of myocardial perfusion imaging with exercise testing in children.

    Science.gov (United States)

    Robinson, Brad; Goudie, Brett; Remmert, Jenna; Gidding, Samuel S

    2012-10-01

    Myocardial perfusion imaging (MPI) provides additional clinical information on children with cardiac disease but will not benefit children with chest pain and normal cardiac studies. This study reviewed all technetium-99 m ((99m)Tc) sestamibi stress MPI studies between 2004 and 2010 performed in association with graded exercise testing (86% with bicycle ergometer, 14% with treadmill). A positive test was defined as a perfusion defect or abnormal ventricular function response. Clinical records were reviewed, including follow-up assessment to determine accuracy of MPI interpretation. False-positive and false-negative rates were recorded. A total of 197 patients (mean age, 13.4 ± 3.6 years, 70% male) underwent 218 MPI studies. Group A had 42 patients (43 studies) with isolated chest pain and normal studies. Of the 43 studies, 39 had negative results, and 4 had false-positive results. Group B had 155 patients (175 studies) with known or suspected cardiac disease, and 39 tests (33 patients) had positive results. Whereas 32 studies were considered true-positive, 7 were false-positive. There was one false-negative test. According to the findings, (99m)Tc sestamibi MPI studies are clinically useful but not perfect tests in the setting of known or suspected cardiac disease based on clinical evaluation, electrocardiography (ECG), or echocardiography. Children who had isolated chest pain with a normal ECG and echocardiogram often have false-positive studies.

  16. The Relation Between Perfusion Pattern of Hepatic Artery Perfusion Scintigraphy and Response to Y-90 Microsphere Therapy

    Directory of Open Access Journals (Sweden)

    Bilge Volkan-Salancı

    2013-12-01

    Full Text Available Objective: Hepatic artery perfusion scintigraphy is a routine procedure for patient evaluation before Y-90 radiomicrosphere therapy and mostly used for prediction of extrahepatic leakage. Moreover, it also displays perfusion pattern of tumours, which is an important parameter on success of the therapy. The aim of this study is to assess the relation between the perfusion pattern on hepatic artery perfusion scintigraphy and radiomicrosphere therapy response. Methods: A total of 99 radiomicrosphere therapy applications were carried out in 80 patients (M/F: 55/25. Results: Heterogeneous and diffuse perfusion patterns were observed in 47 patients and 52 patients, respectively. The patients with diffuse perfusion pattern had better therapy response both on FDG PET/CT (p= 0.04 and CT (p=0.008 when compared to those with heterogenous perfusion pattern. Conclusion: Perfusion pattern observed on hepatic artery perfusion scintigraphy may be a successful predictor of early response to radiomicrosphere therapy

  17. A simulator for perfusion training.

    Science.gov (United States)

    Turkmen, A; Rosinski, D; Noyes, N

    2007-11-01

    In this study, a patient simulator was designed and fabricated to train students to respond to various clinical situations associated with heart-lung bypass machine operation and to respond to changes in patient clinical parameters. The students will use the simulator to gain pre-clinical experience. The training system will initially simulate normal heart-lung bypass conditions. During a training session, the instructor will be able to simulate problems that may happen during a real procedure. Some of these problems are stopping of rotation of one of the roller pump heads, abnormal changes in the vital parameters, such as oxygenation level or biochemical values, high blood pressure, and occlusion in arterial or venous lines. The simulator will train students to respond properly to these situations, hence, allowing them to gain clinical experience without impacting patient safety and the outcome of real life procedures. The simulator can also be used for assessment of the students' competency levels.

  18. MACHINE LEARNING TECHNIQUES USED IN BIG DATA

    Directory of Open Access Journals (Sweden)

    STEFANIA LOREDANA NITA

    2016-07-01

    Full Text Available The classical tools used in data analysis are not enough in order to benefit of all advantages of big data. The amount of information is too large for a complete investigation, and the possible connections and relations between data could be missed, because it is difficult or even impossible to verify all assumption over the information. Machine learning is a great solution in order to find concealed correlations or relationships between data, because it runs at scale machine and works very well with large data sets. The more data we have, the more the machine learning algorithm is useful, because it “learns” from the existing data and applies the found rules on new entries. In this paper, we present some machine learning algorithms and techniques used in big data.

  19. GRINDING OF DOUBLE DISC GRINDING MACHINE

    Institute of Scientific and Technical Information of China (English)

    Hu Huiqing

    2005-01-01

    The grinding of two parallel sides of a component is accomplished with the accuracy and higher productivity by passing a blank through the truncated cone shape grinders, which are turned angles. The machine is designated by the name of double disc grinding machine (DDGM). Usually, it is used in the mass production. The relationship between these angles, the accuracy, productivity,allowance and parameters of the machine and technology is explained in detail by math, such as vector analysis, transformation of 3D space coordinates, etc. Therefore, in the aspects of qualitative and quantitative analyses, the grinding potential of DDGM is enormous increased and superior to conventional methods. Furthermore, the theoretical foundation of DDGM grinding design and technology is provided to improve, to expand and to create for future. The established machine design and practical experience of grinding technology will get great benefit by them.

  20. [An automatic system controlled by microcontroller for carotid sinus perfusion].

    Science.gov (United States)

    Yi, X L; Wang, M Y; Fan, Z Z; He, R R

    2001-08-01

    To establish a new method for controlling automatically the carotid perfusion pressure. A cheap practical automatic perfusion unit based on AT89C2051 micro controller was designed. The unit, LDB-M perfusion pump and the carotid sinus of an animal constituted an automatic perfusion system. This system was able to provide ramp and stepwise updown perfusion pattern and has been used in the research of baroreflex. It can insure the precision and reproducibility of perfusion pressure curve, and improve the technical level in corresponding medical field.

  1. [Evaluation of a new technique of extracorporeal perfusion of the swine liver on a swine-primate model].

    Science.gov (United States)

    Beaufigeau, M; Wolf, P; Azimzadeh, A; Godfrin, Y; Beller, J P; Boudjema, K; Jaeck, D; Kieny, R; Cinqualbre, J

    1996-01-01

    With the increasing success of liver transplantation there is an urgent need for developing an artificial liver support system to be used in patients with liver failure. An extracorporeal porcine liver perfusion machine was successfully tested in animals with experimental liver failure. Livers were flushed, removed from 35 kg pigs and placed in a heated sterile cassette. The portal vein and the hepatic artery of the graft were connected to the arterial system of the animals. The perfusion pressure of the hepatic artery was regulated via a pressure-flow computerized feed-back device. The venous flow was reinfused from the hepatic veins of the graft to the jugular vein of the animals. The experimental work consisted in two steps: 1. evaluation of clinical and biological consequences of liver perfusion in healthy animals (Group A = pigs, n = 3; group B = primates, n = 3); 2. evaluation of the efficiency of the liver perfusion in animals with ischemic liver failure (Groupe D = pigs, n = 6). The control group (Group C = pigs, n = 7) consisted of pigs with ischemic liver failure without hepatic support. No major clinical or biological adverse effects are reported in groups A and B excepted a thrombocytmia and a marked increase in serum transaminases levels in group B. Liver function as assessed by the bile flow was good in both groups. Comatose pigs with ischemic hepatic failure (group D) recovered a subnormal neurological status in five out of six cases. Serum ammoniemia level were significantly decreased (from 1076 +/- 163 to 255 +/- 32 umol/l). A decrease in serum bilirubine levels and an improvement in the coagulation profile were observed in the perfused animals. Pigs and primates tolerated the perfusion procedure well and beneficial effects were observed in perfused pigs with experimental liver failure.

  2. Perfusion harmonic imaging of the human brain

    Science.gov (United States)

    Metzler, Volker H.; Seidel, Guenter; Wiesmann, Martin; Meyer, Karsten; Aach, Til

    2003-05-01

    The fast visualisation of cerebral microcirculation supports diagnosis of acute cerebrovascular diseases. However, the commonly used CT/MRI-based methods are time consuming and, moreover, costly. Therefore we propose an alternative approach to brain perfusion imaging by means of ultrasonography. In spite of the low signal/noise-ratio of transcranial ultrasound and the high impedance of the skull, flow images of cerebral blood flow can be derived by capturing the kinetics of appropriate contrast agents by harmonic ultrasound image sequences. In this paper we propose three different methods for human brain perfusion imaging, each of which yielding flow images indicating the status of the patient's cerebral microcirculation by visualising local flow parameters. Bolus harmonic imaging (BHI) displays the flow kinetics of bolus injections, while replenishment (RHI) and diminution harmonic imaging (DHI) compute flow characteristics from contrast agent continuous infusions. RHI measures the contrast agents kinetics in the influx phase and DHI displays the diminution kinetics of the contrast agent acquired from the decay phase. In clinical studies, BHI- and RHI-parameter images were found to represent comprehensive and reproducible distributions of physiological cerebral blood flow. For DHI it is shown, that bubble destruction and hence perfusion phenomena principally can be displayed. Generally, perfusion harmonic imaging enables reliable and fast bedside imaging of human brain perfusion. Due to its cost efficiency it complements cerebrovascular diagnostics by established CT/MRI-based methods.

  3. Machine Readable Passports & The Visa Waiver Programme

    CERN Document Server

    2003-01-01

    From 1 October 2003, all passengers intending to enter the USA on the Visa Waiver Programme (VWP) will be required to present a machine-readable passport (MRP). Passengers travelling to the USA with a non-machine readable passport will require a valid US entry visa. Applying for a US visa is a lengthy process, which can take several weeks or even months. Therefore it is strongly recommended that: • All Visa Waiver nationals who hold a non-machine readable passport should obtain a MRP before their next visit to the USA. • Children travelling on a parent's passport (be it machine readable or non-machine readable) cannot benefit from the Visa Waiver Programme and should obtain their own MRP prior to travelling to the USA or request a visa. What is a Machine Readable Passport (MRP)? A MRP has the holders' personal details, e.g. name, date of birth, nationality and their passport number contained in two lines of text at the base of the photo page. This text may be read by machine. These 2 lines ...

  4. Standardized perfusion value of the esophageal carcinoma and its correlation with quantitative CT perfusion parameter values

    Energy Technology Data Exchange (ETDEWEB)

    Djuric-Stefanovic, A., E-mail: avstefan@eunet.rs [Faculty of Medicine, University of Belgrade, Belgrade (Serbia); Unit of Digestive Radiology (First University Surgical Clinic), Center of Radiology and MR, Clinical Center of Serbia, Belgrade (Serbia); Saranovic, Dj., E-mail: crvzve4@gmail.com [Faculty of Medicine, University of Belgrade, Belgrade (Serbia); Unit of Digestive Radiology (First University Surgical Clinic), Center of Radiology and MR, Clinical Center of Serbia, Belgrade (Serbia); Sobic-Saranovic, D., E-mail: dsobic2@gmail.com [Faculty of Medicine, University of Belgrade, Belgrade (Serbia); Center of Nuclear Medicine, Clinical Center of Serbia, Belgrade (Serbia); Masulovic, D., E-mail: draganmasulovic@yahoo.com [Faculty of Medicine, University of Belgrade, Belgrade (Serbia); Unit of Digestive Radiology (First University Surgical Clinic), Center of Radiology and MR, Clinical Center of Serbia, Belgrade (Serbia); Artiko, V., E-mail: veraart@beotel.rs [Faculty of Medicine, University of Belgrade, Belgrade (Serbia); Center of Nuclear Medicine, Clinical Center of Serbia, Belgrade (Serbia)

    2015-03-15

    Purpose: Standardized perfusion value (SPV) is a universal indicator of tissue perfusion, normalized to the whole-body perfusion, which was proposed to simplify, unify and allow the interchangeability among the perfusion measurements and comparison between the tumor perfusion and metabolism. The aims of our study were to assess the standardized perfusion value (SPV) of the esophageal carcinoma, and its correlation with quantitative CT perfusion measurements: blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability surface area product (PS) of the same tumor volume samples, which were obtained by deconvolution-based CT perfusion analysis. Methods: Forty CT perfusion studies of the esophageal cancer were analyzed, using the commercial deconvolution-based CT perfusion software (Perfusion 3.0, GE Healthcare). The SPV of the esophageal tumor and neighboring skeletal muscle were correlated with the corresponding mean tumor and muscle quantitative CT perfusion parameter values, using Spearman's rank correlation coefficient (r{sub S}). Results: Median SPV of the esophageal carcinoma (7.1; range: 2.8–13.4) significantly differed from the SPV of the skeletal muscle (median: 1.0; range: 0.4–2.4), (Z = −5.511, p < 0.001). The cut-off value of the SPV of 2.5 enabled discrimination of esophageal cancer from the skeletal muscle with sensitivity and specificity of 100%. SPV of the esophageal carcinoma significantly correlated with corresponding tumor BF (r{sub S} = 0.484, p = 0.002), BV (r{sub S} = 0.637, p < 0.001) and PS (r{sub S} = 0.432, p = 0.005), and SPV of the skeletal muscle significantly correlated with corresponding muscle BF (r{sub S} = 0.573, p < 0.001), BV (r{sub S} = 0.849, p < 0.001) and PS (r{sub S} = 0.761, p < 0.001). Conclusions: We presented a database of the SPV for the esophageal cancer and proved that SPV of the esophageal neoplasm significantly differs from the SPV of the skeletal muscle, which represented a sample of healthy

  5. Magnetic resonance imaging of pulmonary perfusion. Technical requirements and diagnostic impact; MRT der Lungenperfusion. Technische Voraussetzungen und diagnostischer Stellenwert

    Energy Technology Data Exchange (ETDEWEB)

    Attenberger, U.I.; Buesing, K.; Schoenberg, S.O.; Fink, C. [Klinikum Mannheim der Universitaet Heidelberg, Institut fuer Klinische Radiologie und Nuklearmedizin, Universitaetsmedizin Mannheim, Mannheim (Germany); Ingrisch, M.; Reiser, M. [Klinikum der Ludwig-Maximilians-Universitaet Muenchen, Institut fuer Klinische Radiologie, Campus Grosshadern, Muenchen (Germany)

    2009-08-15

    With technical improvements in gradient hardware and the implementation of innovative k-space sampling techniques, such as parallel imaging, the feasibility of pulmonary perfusion MRI could be demonstrated in several studies. Dynamic contrast-enhanced 3D gradient echo sequences as used for time-resolved MR angiography have been established as the preferred pulse sequences for lung perfusion MRI. With these techniques perfusion of the entire lung can be visualized with a sufficiently high temporal and spatial resolution. In several trials in patients with acute pulmonary embolism, pulmonary hypertension and airway diseases, the clinical benefit and good correlation with perfusion scintigraphy have been demonstrated. The following review article describes the technical prerequisites, current post-processing techniques and the clinical indications for MR pulmonary perfusion imaging using MRI. (orig.) [German] Mit der Verfuegbarkeit leistungsfaehiger Gradientensysteme und schneller k-Raum-Akquisitionstechniken wie der parallelen Bildgebung konnten verschiedene Studien die Machbarkeit der Lungenperfusionsbildgebung in der MRT zeigen. In der Praxis haben sich dynamische kontrastverstaerkte 3D-Gradientenechosequenzen, wie sie fuer zeitaufgeloeste MR-Angiographien verwendet werden, fuer die Bildgebung der Lungenperfusion etabliert. Hiermit ist es moeglich, die Perfusion der gesamten Lunge mit ausreichend hoher zeitlicher und raeumlicher Aufloesung zu visualisieren. In mehren klinischen Studien konnte bei Patienten mit Lungenembolie, pulmonaler Hypertonie sowie Erkrankungen der Atemwege und des Lungenparenchyms der klinische Nutzen der Lungenperfusions-MRT und die gute Uebereinstimmung mit der Lungenperfusionsszintigraphie nachgewiesen werden. Der folgende Uebersichtsartikel beschreibt die technische Durchfuehrung, Bildnachverarbeitung und die klinischen Anwendungsgebiete der MRT zur Untersuchung der Lungenperfusion. (orig.)

  6. Distribution of lung blood on modified bilateral Glenn shunt evaluated by Tc-99m-MAA lung perfusion scintigraphy

    Science.gov (United States)

    Si, Biao; Luan, Zhao-sheng; Wang, Tong-jian; Ning, Yan-song; Li, Na; Zhu, Meng; Liu, Zhong-min; Ding, Guang-hong; Qiao, Bin

    2016-01-01

    Abstract The aim of the present study was to determine the distribution of lung blood in a modified bilateral Glenn procedure designed in our institute with lung perfusion scintigraphy. Sixteen consecutive patients who underwent modified bilateral Glenn operation from 2011 to 2014 were enrolled in the study. The control group consisted of 7 patients who underwent bidirectional Glenn shunt. Radionuclide lung perfusion scintigraphy was performed using Tc-99m-macro aggregated albumin (MAA) in all patients. For the patients in modified bilateral Glenn group, the time at which the radioactivity accumulation peaked did not differ significantly between the right and left lung field (t = 0.608, P = 0.554). The incidence of perfusion abnormality in each lung lobe also did not differ significantly (P = 0.426 by Fisher exact test). The radioactive counts were higher in the right lung than in the left lung, but the difference was not statistically significant (t = 1.502, P = 0.157). Radioactive perfusion in the lower lung field was significantly greater than that in the upper field (t = 4.368, P lung to that in left lung was significantly lower in the modified bilateral Glenn group (t = 3.686, P = 0.002). Lung perfusion scintigraphy confirmed the benefit of the modified bilateral Glenn shunt with regard to more balanced blood perfusion in both lungs. PMID:27661042

  7. Prediction of ATLS hypovolemic shock class in rats using the perfusion index and lactate concentration.

    Science.gov (United States)

    Choi, Soo Beom; Park, Jee Soo; Chung, Jai Won; Kim, Sung Woo; Kim, Deok Won

    2015-04-01

    It is necessary to quickly and accurately determine Advanced Trauma Life Support (ATLS) hemorrhagic shock class for triage in cases of acute hemorrhage caused by trauma. However, the ATLS classification has limitations, namely, with regard to primary vital signs. This study identified the optimal variables for appropriate triage of hemorrhage severity, including the peripheral perfusion index and serum lactate concentration in addition to the conventional primary vital signs. To predict the four ATLS classes, three popular machine learning algorithms with four feature selection methods for multicategory classification were applied to a rat model of acute hemorrhage. A total of 78 anesthetized rats were divided into four groups for ATLS classification based on blood loss (in percent). The support vector machine one-versus-one model with the Kruskal-Wallis feature selection method performed best, with 80.8% accuracy, relative classifier information of 0.629, and a kappa index of 0.732. The new hemorrhage-induced severity index (lactate concentration/perfusion index), diastolic blood pressure, mean arterial pressure, and the perfusion index were selected as the optimal variables for predicting the four ATLS classes by support vector machine one-versus-one with the Kruskal-Wallis method. These four variables were also selected for binary classification to predict ATLS classes I and II versus III and IV for blood transfusion requirement. The suggested ATLS classification system would be helpful to first responders by indicating the severity of patients, allowing physicians to prepare suitable resuscitation before hospital arrival, which could hasten treatment initiation.

  8. Asynchronized synchronous machines

    CERN Document Server

    Botvinnik, M M

    1964-01-01

    Asynchronized Synchronous Machines focuses on the theoretical research on asynchronized synchronous (AS) machines, which are "hybrids” of synchronous and induction machines that can operate with slip. Topics covered in this book include the initial equations; vector diagram of an AS machine; regulation in cases of deviation from the law of full compensation; parameters of the excitation system; and schematic diagram of an excitation regulator. The possible applications of AS machines and its calculations in certain cases are also discussed. This publication is beneficial for students and indiv

  9. Quantum machine learning.

    Science.gov (United States)

    Biamonte, Jacob; Wittek, Peter; Pancotti, Nicola; Rebentrost, Patrick; Wiebe, Nathan; Lloyd, Seth

    2017-09-13

    Fuelled by increasing computer power and algorithmic advances, machine learning techniques have become powerful tools for finding patterns in data. Quantum systems produce atypical patterns that classical systems are thought not to produce efficiently, so it is reasonable to postulate that quantum computers may outperform classical computers on machine learning tasks. The field of quantum machine learning explores how to devise and implement quantum software that could enable machine learning that is faster than that of classical computers. Recent work has produced quantum algorithms that could act as the building blocks of machine learning programs, but the hardware and software challenges are still considerable.

  10. Precision machine design

    CERN Document Server

    Slocum, Alexander H

    1992-01-01

    This book is a comprehensive engineering exploration of all the aspects of precision machine design - both component and system design considerations for precision machines. It addresses both theoretical analysis and practical implementation providing many real-world design case studies as well as numerous examples of existing components and their characteristics. Fast becoming a classic, this book includes examples of analysis techniques, along with the philosophy of the solution method. It explores the physics of errors in machines and how such knowledge can be used to build an error budget for a machine, how error budgets can be used to design more accurate machines.

  11. Magnetic resonance perfusion imaging evaluation in perfusion abnormalities of the cerebellum after supratentorial unilateral hyperacute cerebral infarction

    Institute of Scientific and Technical Information of China (English)

    Pan Liang; Yunjun Yang; Weijian Chen; Yuxia Duan; Hongqing Wang; Xiaotong Wang

    2012-01-01

    Magnetic resonance imaging (MRI) data of 10 patients with hyperacute cerebral infarction (≤ 6 hours) were retrospectively analyzed. Six patients exhibited perfusion defects on negative enhancement integral maps, four patients exhibited perfusion differences in pseudo-color on mean time to enhance maps, and three patients exhibited perfusion differences in pseudo-color on time to minimum maps. Dynamic susceptibility contrast-enhanced perfusion weighted imaging revealed a significant increase in region negative enhancement integral in the affected hemisphere of patients with cerebral infarction. The results suggest that dynamic susceptibility contrast-enhanced perfusion weighted imaging can clearly detect perfusion abnormalities in the cerebellum after unilateral hyperacute cerebral infarction.

  12. Dynamic perfusion patterns in temporal lobe epilepsy

    Energy Technology Data Exchange (ETDEWEB)

    Dupont, Patrick; Paesschen, Wim van [KU Leuven/UZ Gasthuisberg, Nuclear Medicine, Medical Imaging Center and Neurology, Leuven (Belgium); Zaknun, John J. [International Atomic Energy Agency (IAEA), Nuclear Medicine Section, Division of Human Health, Wagramer Strasse 5, PO BOX 200, Vienna (Austria); University Hospital of Innsbruck, Department of Nuclear Medicine, Innsbruck (Austria); Maes, Alex [KU Leuven/UZ Gasthuisberg, Nuclear Medicine, Medical Imaging Center and Neurology, Leuven (Belgium); AZ Groeninge, Nuclear Medicine, Kortrijk (Belgium); Tepmongkol, Supatporn; Locharernkul, Chaichon [Chulalongkorn University, Nuclear Medicine and Neurology, Bangkok (Thailand); Vasquez, Silvia; Carpintiero, Silvina [Fleni Instituto de Investigaciones Neurologicas, Nuclear Medicine, Buenos Aires (Argentina); Bal, C.S. [All India Institute of Medical Sciences, Nuclear Medicine, New Delhi (India); Dondi, Maurizio [International Atomic Energy Agency (IAEA), Nuclear Medicine Section, Division of Human Health, Wagramer Strasse 5, PO BOX 200, Vienna (Austria); Ospedale Maggiore, Nuclear Medicine, Bologna (Italy)

    2009-05-15

    To investigate dynamic ictal perfusion changes during temporal lobe epilepsy (TLE). We investigated 37 patients with TLE by ictal and interictal SPECT. All ictal injections were performed within 60 s of seizure onset. Statistical parametric mapping was used to analyse brain perfusion changes and temporal relationships with injection time and seizure duration as covariates. The analysis revealed significant ictal hyperperfusion in the ipsilateral temporal lobe extending to subcortical regions. Hypoperfusion was observed in large extratemporal areas. There were also significant dynamic changes in several extratemporal regions: ipsilateral orbitofrontal and bilateral superior frontal gyri and the contralateral cerebellum and ipsilateral striatum. The study demonstrated early dynamic perfusion changes in extratemporal regions probably involved in both propagation of epileptic activity and initiation of inhibitory mechanisms. (orig.)

  13. Stress-only myocardial perfusion scintigraphy

    DEFF Research Database (Denmark)

    Ejlersen, June A; May, Ole; Mortensen, Jesper

    2017-01-01

    OBJECTIVE: Patients with normal stress perfusion have an excellent prognosis. Prospective studies on the diagnostic accuracy of stress-only scans with contemporary, independent examinations as gold standards are lacking. PATIENTS AND METHODS: A total of 109 patients with typical angina and no pre......OBJECTIVE: Patients with normal stress perfusion have an excellent prognosis. Prospective studies on the diagnostic accuracy of stress-only scans with contemporary, independent examinations as gold standards are lacking. PATIENTS AND METHODS: A total of 109 patients with typical angina...... and no previous coronary artery disease underwent a 2-day stress (exercise)/rest, gated, and attenuation-corrected (AC), 99m-technetium-sestamibi perfusion study, followed by invasive coronary angiography. The stress datasets were evaluated twice by four physicians with two different training levels (expert...

  14. Measurement of myocardial perfusion using magnetic resonance

    DEFF Research Database (Denmark)

    Fritz-Hansen, T.; Jensen, L.T.; Larsson, H.B.;

    2008-01-01

    Cardiac magnetic resonance imaging (MRI) has evolved rapidly. Recent developments have made non-invasive quantitative myocardial perfusion measurements possible. MRI is particularly attractive due to its high spatial resolution and because it does not involve ionising radiation. This paper review...... myocardial perfusion imaging with MR contrast agents: methods, validation and experiences from clinical studies. Unresolved issues still restrict the use of these techniques to research although clinical applications are within reach Udgivelsesdato: 2008/12/8......Cardiac magnetic resonance imaging (MRI) has evolved rapidly. Recent developments have made non-invasive quantitative myocardial perfusion measurements possible. MRI is particularly attractive due to its high spatial resolution and because it does not involve ionising radiation. This paper reviews...

  15. Perfusion computed tomography for diffuse liver diseases; Perfusions-CT bei diffusen Lebererkrankungen

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, S.A.; Juchems, M.S. [Universitaetsklinikum Ulm, Klinik fuer Diagnostische und Interventionelle Radiologie, Ulm (Germany)

    2012-08-15

    Perfusion computed tomography (CT) has its main application in the clinical routine diagnosis of neuroradiological problems. Polyphase multi-detector spiral computed tomography is primarily used in liver diagnostics. The use of perfusion CT is also possible for the diagnostics and differentiation of diffuse hepatic diseases. The differentiation between cirrhosis and cirrhosis-like parenchymal changes is possible. It also helps to detect early stages of malignant tumors. However, there are some negative aspects, particularly that of radiation exposure. This paper summarizes the technical basics and possible applications of perfusion CT in cases of diffuse liver disease and weighs up the advantages and disadvantages of the examinations. (orig.) [German] Die Perfusions-CT hat ihren hauptsaechlichen Stellenwert bislang in der klinischen Routinediagnostik bei neuroradiologische Fragestellungen. In der Leberdiagnostik kommt v. a. die mehrphasige Multidetektor-Spiral-CT-Untersuchung zum Einsatz. Die Anwendung der Perfusions-CT ist auch bei der Diagnostik und Differenzierung diffuser Lebererkrankungen moeglich. Die Unterscheidung zwischen einer Leberzirrhose und zirrhoseaehnlichen Parenchymveraenderungen ist mit der Perfusions-CT moeglich. Ebenso liefert sie einen wertvollen Beitrag zur Diagnostik bei der Frueherkennung entstehender maligner Herdbefunde. Diesen Vorteilen stehen jedoch auch einige negative Aspekte gegenueber, insbesondere die relativ hohe Strahlenexposition. Die vorliegende Arbeit soll einen Ueberblick ueber die technischen Grundlagen und die Anwendungsmoeglichkeiten der Perfusions-CT bei diffusen Lebererkrankungen geben sowie die Vor- und Nachteile der Untersuchung gegeneinander abwaegen. (orig.)

  16. Who benefits?

    DEFF Research Database (Denmark)

    Hjorth, Frederik Georg

    2016-01-01

    Cross-border welfare rights for citizens of European Union member states are intensely contested, yet there is limited research into voter opposition to such rights, sometimes denoted ‘welfare chauvinism’. We highlight an overlooked aspect in scholarly work: the role of stereotypes about...... beneficiaries of cross-border welfare. We present results from an original large-scale survey experiment (N=2525) among Swedish voters, randomizing exposure to cues about recipients' country of origin and family size. Consistent with a model emphasizing the role of stereotypes, respondents react to cues about...... recipient identity. These effects are strongest among respondents high in ethnic prejudice and economic conservatism. The findings imply that stereotypes about who benefits from cross-border welfare rights condition public support for those rights....

  17. Perfusion CT in acute stroke; Stellenwert der CT-Perfusion fuer die Therapie des Schlaganfalls

    Energy Technology Data Exchange (ETDEWEB)

    Eckert, Bernd [Asklepios Klinik Altona (Germany). Radiologie und Neuroradiologie; Roether, Joachim [Asklepios Klinik Altona (Germany). Neurologische Abt.; Fiehler, Jens [Universitaetsklinikum Hamburg-Eppendorf, Hamburg (Germany). Klinik und Poliklinik fuer Neuroradiologische Diagnostik und Intervention; Thomalla, Goetz [Universitaetsklinikum Hamburg-Eppendorf, Hamburg (Germany). Klinik und Poliklinik fuer Neurologie, Kopf- und Neurozentrum

    2015-06-15

    Modern multislice CT scanners enable multimodal protocols including non-enhanced CT, CT angiography, and CT perfusion. A 64-slice CT scanner provides 4-cm coverage. To cover the whole brain, a 128 - 256-slice scanner is needed. The use of perfusion CT requires an optimized scan protocol in order to reduce exposure to radiation. As compared to non-enhanced CT and CT angiography, the use of CT perfusion increases detection rates of cerebral ischemia, especially small cortical ischemic lesions, while the detection of lacunar and infratentorial stroke lesions remains limited. Perfusion CT enables estimation of collateral flow in acute occlusion of large intra- or extracranial arteries. Currently, no established reliable thresholds are available for determining infarct core and penumbral tissue by CT perfusion. Moreover, perfusion parameters depend on the processing algorithms and the software used for calculation. However, a number of studies point towards a reduction of cerebral blood volume (CBV) below 2 ml/100 g as a critical threshold that identifies infarct core. Large CBV lesions are associated with poor outcome even in the context of recanalization. The extent of early ischemic signs on non-enhanced CT remains the main parameter from CT imaging to guide acute reperfusion treatment. Nevertheless, perfusion CT increases diagnostic and therapeutic certainty in the acute setting. Similar to stroke MRI, perfusion CT enables the identification of tissue at risk of infarction by the mismatch between infarct core and the larger area of critical hypoperfusion. Further insights into the validity of perfusion parameters are expected from ongoing trials of mechanical thrombectomy in stroke.

  18. Perfusion Quantification Using Gaussian Process Deconvolution

    DEFF Research Database (Denmark)

    Andersen, Irene Klærke; Have, Anna Szynkowiak; Rasmussen, Carl Edward

    2002-01-01

    The quantification of perfusion using dynamic susceptibility contrast MRI (DSC-MRI) requires deconvolution to obtain the residual impulse response function (IRF). In this work, a method using the Gaussian process for deconvolution (GPD) is proposed. The fact that the IRF is smooth is incorporated...... optimized according to the noise level in each voxel. The comparison is carried out using artificial data as well as data from healthy volunteers. It is shown that GPD is comparable to SVD with a variable optimized threshold when determining the maximum of the IRF, which is directly related to the perfusion...

  19. Perfusion lung imaging in the adult respiratory distress syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Pistolesi, M.; Miniati, M.; Di Ricco, G.; Marini, C.; Giuntini, C.

    1986-07-01

    In 29 perfusion lung scans (PLS) of 19 patients with ARDS, 20 of which were obtained within six days from the onset of respiratory symptoms, perfusion abnormalities were the rule. These included focal, nonsegmental defects, mostly peripheral and dorsal, and perfusion redistribution away from the dependent lung zones. PLS were scored for the presence and intensity of perfusion abnormalities and the scores of perfusion redistribution were validated against numerical indices of blood flow distribution per unit lung volume. PLS scores were correlated with arterial blood gas values, hemodynamic parameters, and chest radiographic scores of ARDS. Arterial oxygen tension correlated with the scores of both perfusion defects and redistribution. Perfusion defects correlated better with the radiographic score of ARDS, and perfusion redistribution with PAP and vascular resistance. ARDS patients exhibit peculiar patterns of PLS abnormalities not observed in other disorders. Thus, PLS may help considerably in the detection and evaluation of pulmonary vascular injury in ARDS.

  20. Perspex machine: VII. The universal perspex machine

    Science.gov (United States)

    Anderson, James A. D. W.

    2006-01-01

    The perspex machine arose from the unification of projective geometry with the Turing machine. It uses a total arithmetic, called transreal arithmetic, that contains real arithmetic and allows division by zero. Transreal arithmetic is redefined here. The new arithmetic has both a positive and a negative infinity which lie at the extremes of the number line, and a number nullity that lies off the number line. We prove that nullity, 0/0, is a number. Hence a number may have one of four signs: negative, zero, positive, or nullity. It is, therefore, impossible to encode the sign of a number in one bit, as floating-point arithmetic attempts to do, resulting in the difficulty of having both positive and negative zeros and NaNs. Transrational arithmetic is consistent with Cantor arithmetic. In an extension to real arithmetic, the product of zero, an infinity, or nullity with its reciprocal is nullity, not unity. This avoids the usual contradictions that follow from allowing division by zero. Transreal arithmetic has a fixed algebraic structure and does not admit options as IEEE, floating-point arithmetic does. Most significantly, nullity has a simple semantics that is related to zero. Zero means "no value" and nullity means "no information." We argue that nullity is as useful to a manufactured computer as zero is to a human computer. The perspex machine is intended to offer one solution to the mind-body problem by showing how the computable aspects of mind and, perhaps, the whole of mind relates to the geometrical aspects of body and, perhaps, the whole of body. We review some of Turing's writings and show that he held the view that his machine has spatial properties. In particular, that it has the property of being a 7D lattice of compact spaces. Thus, we read Turing as believing that his machine relates computation to geometrical bodies. We simplify the perspex machine by substituting an augmented Euclidean geometry for projective geometry. This leads to a general

  1. Improved visualization of delayed perfusion in lung MRI

    Energy Technology Data Exchange (ETDEWEB)

    Risse, Frank [Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg (Germany); Eichinger, Monika [Department of Radiology, German Cancer Research Center, Heidelberg (Germany); Kauczor, Hans-Ulrich [Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg (Germany); Semmler, Wolfhard [Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg (Germany); Puderbach, Michael, E-mail: m.puderbach@dkfz.de [Department of Radiology, German Cancer Research Center, Heidelberg (Germany)

    2011-01-15

    Introduction: The investigation of pulmonary perfusion by three-dimensional (3D) dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was proposed recently. Subtraction images are generated for clinical evaluation, but temporal information is lost and perfusion defects might therefore be masked in this process. The aim of this study is to demonstrate a simple analysis strategy and classification for 3D-DCE-MRI perfusion datasets in the lung without omitting the temporal information. Materials and methods: Pulmonary perfusion measurements were performed in patients with different lung diseases using a 1.5 T MR-scanner with a time-resolved 3D-GRE pulse sequence. 25 3D-volumes were acquired after iv-injection of 0.1 mmol/kg KG Gadolinium-DTPA. Three parameters were determined for each pixel: (1) peak enhancement S{sub n,max} normalized to the arterial input function to detect regions of reduced perfusion; (2) time between arterial peak enhancement in the large pulmonary artery and tissue peak enhancement {tau} to visualize regions with delayed bolus onset; and (3) ratio R = S{sub n,max}/{tau} was calculated to visualize impaired perfusion, irrespectively of whether related to reduced or delayed perfusion. Results: A manual selection of peak perfusion images is not required. Five different types of perfusion can be found: (1) normal perfusion; (2) delayed non-reduced perfusion; (3) reduced non-delayed perfusion; (4) reduced and delayed perfusion; and (5) no perfusion. Types II and IV could not be seen in subtraction images since the temporal information is necessary for this purpose. Conclusions: The analysis strategy in this study allows for a simple and observer-independent visualization and classification of impaired perfusion in dynamic contrast-enhanced pulmonary perfusion MRI by using the temporal information of the datasets.

  2. [Design of the Rolling Type Nasal Feeding Perfusion Apparatus].

    Science.gov (United States)

    Yu, Dong; Yang, Yonghuan; Hu, Huiqin; Luo, Hongjun; Feng, Yunhao; Hao, Xiali

    2015-09-01

    At present, the existing problem in nasal feeding perfusion apparatus is laborious and instability. Designing the rolling type perfusion apparatus by using a roller pump, the problem is solved. Compared with the traditional perfusion apparatus, the advantage lies in liquid carrying only need once and simulating human swallowing process. Through testing and verification, the apparatus can be used in nasal feeding perfusion for elderly or patients.

  3. Perfusion MRI in neuro-psychiatric systemic lupus erthemathosus.

    NARCIS (Netherlands)

    Emmer, B.J.; Osch, M.J. van; Wu, O.; Steup-Beekman, G.M.; Steens, S.; Huizinga, T.W.J.; Buchem, M.A. van; Grond, J. van der

    2010-01-01

    PURPOSE: To use perfusion weighted MR to quantify any perfusion abnormalities and to determine their contribution to neuropsychiatric (NP) involvement in systemic lupus erythematosus (SLE). MATERIALS AND METHODS: We applied dynamic susceptibility contrast (DSC) perfusion MRI in 15 active NPSLE, 26 i

  4. Computed tomography perfusion evaluation after extracranial-intracranial bypass surgery

    NARCIS (Netherlands)

    Vos, P.C.; Riordan, A.J.; Smit, E.J.; Jong, H.W. de; Zwan, A. van der; Velthuis, B.K.; Viergever, M.A.; Dankbaar, J.W.

    2015-01-01

    OBJECTIVE: Perfusion imaging is increasingly used for postoperative evaluation of extracranial to intracranial (EC-IC) bypass surgery. Altered hemodynamics and delayed arrival of the contrast agent in the area fed by the bypass can influence perfusion measurement. We compared perfusion asymmetry obt

  5. An alternative method for neonatal cerebro-myocardial perfusion

    Science.gov (United States)

    Luciani, Giovanni Battista; De Rita, Fabrizio; Faggian, Giuseppe; Mazzucco, Alessandro

    2012-01-01

    Several techniques have already been described for selective cerebral perfusion during repair of aortic arch pathology in children. One method combining cerebral with myocardial perfusion has also been proposed. A novel technique is reported here for selective and independent cerebro-myocardial perfusion for neonatal and infant arch surgery. Technical aspects and potential advantages are discussed. PMID:22307393

  6. CT angiography and CT perfusion in acute ischemic stroke

    NARCIS (Netherlands)

    Seeters, T. van

    2016-01-01

    CT angiography and CT perfusion are used in patients with acute ischemic stroke for diagnostic purposes and to select patients for treatment. In this thesis, the reproducibility of CT angiography and CT perfusion is examined, the additional value of CT angiography and CT perfusion for stroke outcome

  7. Computed tomography perfusion evaluation after extracranial-intracranial bypass surgery

    NARCIS (Netherlands)

    Vos, Pieter C.; Riordan, Alan J.; Smit, Ewoud J.; de Jong, Hugo W. A. M.; van der Zwan, Albert; Velthuis, BK; Viergever, Max A.; Dankbaar, Jan Willem

    2015-01-01

    Objective: Perfusion imaging is increasingly used for postoperative evaluation of extracranial to intracranial (EC-IC) bypass surgery. Altered hemodynamics and delayed arrival of the contrast agent in the area fed by the bypass can influence perfusion measurement. We compared perfusion asymmetry obt

  8. Hypothermic machine preservation reduces molecular markers of ischemia/reperfusion injury in human liver transplantation.

    Science.gov (United States)

    Henry, S D; Nachber, E; Tulipan, J; Stone, J; Bae, C; Reznik, L; Kato, T; Samstein, B; Emond, J C; Guarrera, J V

    2012-09-01

    Hypothermic machine perfusion (HMP) is in its infancy in clinical liver transplantation. Potential benefits include diminished preservation injury (PI) and improved graft function. Molecular data to date has been limited to extrapolation of animal studies. We analyzed liver tissue and serum collected during our Phase 1 trial of liver HMP. Grafts preserved with HMP were compared to static cold stored (SCS) transplant controls. Reverse transcription polymerase chain reaction (RT-PCR), immunohistochemistry and transmission electron microscopy (TEM) were performed on liver biopsies. Expression of inflammatory cytokines, adhesion molecules and chemokines, oxidation markers, apoptosis and acute phase proteins and the levels of CD68 positive macrophages in tissue sections were evaluated. RT-PCR of reperfusion biopsy samples in the SCS group showed high expression of inflammatory cytokines, adhesion molecules and chemokines, oxidative markers and acute phase proteins. This upregulation was significantly attenuated in livers that were preserved by HMP. Immunofluorescence showed larger numbers of CD68 positive macrophages in the SCS group when compared to the HMP group. TEM samples also revealed ultrastructural damage in the SCS group that was not seen in the HMP group. HMP significantly reduced proinflammatory cytokine expression, relieving the downstream activation of adhesion molecules and migration of leukocytes, including neutrophils and macrophages when compared to SCS controls.

  9. Pulmonary artery perfusion versus no pulmonary perfusion during cardiopulmonary bypass in patients with COPD

    DEFF Research Database (Denmark)

    Buggeskov, Katrine B; Sundskard, Martin M; Jonassen, Thomas;

    2016-01-01

    INTRODUCTION: Absence of pulmonary perfusion during cardiopulmonary bypass (CPB) may be associated with reduced postoperative oxygenation. Effects of active pulmonary artery perfusion were explored in patients with chronic obstructive pulmonary disease (COPD) undergoing cardiac surgery. METHODS: 90...... starting CPB and longitudinally in a mixed-effects model (MEM). Secondary outcomes were tracheal intubation time, serious adverse events, mortality, days alive outside the intensive care unit (ICU) and outside the hospital. RESULTS: 21 hours after starting CPB patients receiving pulmonary artery perfusion...... with normothermic oxygenated blood had a higher oxygenation index compared with no pulmonary perfusion (mean difference (MD) 0.94; 95% CI 0.05 to 1.83; p=0.04). The blood group had also a higher oxygenation index both longitudinally (MEM, p=0.009) and at 21 hours (MD 0.99; CI 0.29 to 1.69; p=0.007) compared...

  10. Development of a Phantom Tissue for Blood Perfusion Measurements and Noninvasive Blood Perfusion Estimation in Living Tissue

    OpenAIRE

    Mudaliar, Ashvinikumar

    2007-01-01

    A convenient method for testing and calibrating surface perfusion sensors has been developed. A phantom tissue model is used to mimic the non-directional blood flow of tissue perfusion. A computational fluid dynamics (CFD) model was constructed in Fluent to design the phantom tissue and validate the experimental results. The phantom perfusion system was used with a perfusion sensor based on the clearance of thermal energy. A heat flux gage measures the heat flux response of tissue whe...

  11. Fast Registration of Cardiac Perfusion MRI

    DEFF Research Database (Denmark)

    Stegmann, Mikkel Bille; Larsson, Henrik B. W.

    2003-01-01

    This abstract presents a novel method for registration of cardiac perfusion MRI sequences. By performing complex analyses of variance and clustering in an annotated training set off-line, our method provides real-time segmentation in an on-line setting. This renders the method feasible for live...

  12. Nonrigid registration of myocardial perfusion MRI

    DEFF Research Database (Denmark)

    Ólafsdóttir, Hildur

    2005-01-01

    This paper describes a fully automatic registration of 10 multi-slice myocardial perfusion magnetic resonance image sequences. The registration of these sequences is crucial for the clinical interpretation, which currently is subjected to manual labour. The approach used in this study is a nonrig...

  13. Leukocytes and Perfusion Recovery after Arterial Occlusion

    NARCIS (Netherlands)

    Haverslag, R.T.

    2012-01-01

    The main topic of this thesis is arteriogenesis and the role circulating leukocytes play in this process of perfusion recovery. We have used clinically applicable inhibitors to increase leukocyte attraction and extravasation and discovered previously unknown factors which play a role in

  14. Methodology for ventilation/perfusion SPECT

    DEFF Research Database (Denmark)

    Bajc, Marika; Neilly, Brian; Miniati, Massimo

    2010-01-01

    Ventilation/perfusion single-photon emission computed tomography (V/Q SPECT) is the scintigraphic technique of choice for the diagnosis of pulmonary embolism and many other disorders that affect lung function. Data from recent ventilation studies show that the theoretic advantages of Technegas ov...

  15. Study of lung perfusion in colagenosis

    Energy Technology Data Exchange (ETDEWEB)

    Macedo de Carvalho, A.C.; Calegaro, J.U.M. (Fundacao Hospitalar do Distrito Federal, Distrito Federal (Brazil). Unidade de Medicina Nuclear)

    1982-07-01

    The lung involvement in the various types of colagenosis has been widely described in the literature. However, the study of lung perfusion utilizing radionuclides has been only mentioned in a few papers. With the intention of ascertaining the importance of the lung perfusion scanning in colagenosis, ten cases were studied, seven of which were females and three males, with the following pathologies: 4 rheumatoid arthritis, 4 systemic lupus eritematosous, 1 scleroderma and 1 scleroderma plus dermatomyositis. The ages of the patients varied from 20 to 73 years, and the duration of the disease from 1 month to 39 years. The lung scanning showed perfusion defects in 100% of the cases, not related with the type of colagenosis, duration of the disease, sex or age. On the other hand, the X rays study showed alterations in only 2 patients (20% of the cases). The ventilatory and respiratory functions were tested on 7 patients showing alteration (mixed pattern with predominance of the restrictive factor) in only one (14.3%), while the other patients were normal (85.7%). The importance of the lung perfusion scanning study in all patients with collagen vascular diseases is emphasized.

  16. Simultaneous Multiagent Hyperpolarized 13C Perfusion Imaging

    DEFF Research Database (Denmark)

    von Morze, Cornelius; Bok, Robert A.; Reed, Galen D.

    2014-01-01

    Purpose: To demonstrate simultaneous hyperpolarization and imaging of three 13C-labeled perfusion MRI contrast agents with dissimilar molecular structures ([13C]urea, [13C]hydroxymethyl cyclopropane, and [13C]t-butanol) and correspondingly variable chemical shifts and physiological characteristic...

  17. Simplified prototyping of perfusable polystyrene microfluidics

    Science.gov (United States)

    Tran, Reginald; Ahn, Byungwook; R. Myers, David; Qiu, Yongzhi; Sakurai, Yumiko; Moot, Robert; Mihevc, Emma; Trent Spencer, H.; Doering, Christopher; A. Lam, Wilbur

    2014-01-01

    Cell culture in microfluidic systems has primarily been conducted in devices comprised of polydimethylsiloxane (PDMS) or other elastomers. As polystyrene (PS) is the most characterized and commonly used substrate material for cell culture, microfluidic cell culture would ideally be conducted in PS-based microsystems that also enable tight control of perfusion and hydrodynamic conditions, which are especially important for culture of vascular cell types. Here, we report a simple method to prototype perfusable PS microfluidics for endothelial cell culture under flow that can be fabricated using standard lithography and wet laboratory equipment to enable stable perfusion at shear stresses up to 300 dyn/cm2 and pumping pressures up to 26 kPa for at least 100 h. This technique can also be extended to fabricate perfusable hybrid PS-PDMS microfluidics of which one application is for increased efficiency of viral transduction in non-adherent suspension cells by leveraging the high surface area to volume ratio of microfluidics and adhesion molecules that are optimized for PS substrates. These biologically compatible microfluidic devices can be made more accessible to biological-based laboratories through the outsourcing of lithography to various available microfluidic foundries. PMID:25379106

  18. Nuclear cardiology: Myocardial perfusion and function

    Energy Technology Data Exchange (ETDEWEB)

    Seldin, D.W. (Lahey Clinic Medical Center, Burlington, MA (United States))

    1991-08-01

    Myocardial perfusion studies continue to be a major focus of research, with new investigations of the relationship of exercise-redistribution thallium imaging to diagnosis, prognosis, and case management. The redistribution phenomenon, which seemed to be fairly well understood a few years ago, is now recognized to be much more complex than originally thought, and various strategies have been proposed to clarify the meaning of persistent defects. Pharmacologic intervention with dipyridamole and adenosine has become available as an alternative to exercise, and comparisons with exercise imaging and catheterization results have been described. Thallium itself is no longer the sole single-photon perfusion radiopharmaceutical; two new technetium agents are now widely available. In addition to perfusion studies, advances in the study of ventricular function have been made, including reports of studies performed in conjunction with technetium perfusion studies, new insights into cardiac physiology, and the prognostic and case-management information that function studies provide. Finally, work has continued with monoclonal antibodies for the identification of areas of myocyte necrosis. 41 references.

  19. Clinical application of hepatic CT perfusion

    Institute of Scientific and Technical Information of China (English)

    Liang Zhong; Wen-Jing Wang; Jian-Rong Xu

    2009-01-01

    Complicated changes occur in hemodynamics of hepatic artery and vein, and portal vein under various kinds of pathologic status because of distinct double hepatic blood supply. This article reviews the clinical application of hepatic computed tomography perfusion in some liver diseases.

  20. Asynchronicity of facial blood perfusion in migraine.

    Directory of Open Access Journals (Sweden)

    Nina Zaproudina

    Full Text Available Asymmetrical changes in blood perfusion and asynchronous blood supply to head tissues likely contribute to migraine pathophysiology. Imaging was widely used in order to understand hemodynamic variations in migraine. However, mapping of blood pulsations in the face of migraineurs has not been performed so far. We used the Blood Pulsation Imaging (BPI technique, which was recently developed in our group, to establish whether 2D-imaging of blood pulsations parameters can reveal new biomarkers of migraine. BPI characteristics were measured in migraineurs during the attack-free interval and compared to healthy subjects with and without a family history of migraine. We found a novel phenomenon of transverse waves of facial blood perfusion in migraineurs in contrast to healthy subjects who showed synchronous blood delivery to both sides of the face. Moreover, the amplitude of blood pulsations was symmetrically distributed over the face of healthy subjects, but asymmetrically in migraineurs and subjects with a family history of migraine. In the migraine patients we found a remarkable correlation between the side of unilateral headache and the direction of the blood perfusion wave. Our data suggest that migraine is associated with lateralization of blood perfusion and asynchronous blood pulsations in the facial area, which could be due to essential dysfunction of the autonomic vascular control in the face. These findings may further enhance our understanding of migraine pathophysiology and suggest new easily available biomarkers of this pathology.

  1. Asynchronicity of facial blood perfusion in migraine.

    Science.gov (United States)

    Zaproudina, Nina; Teplov, Victor; Nippolainen, Ervin; Lipponen, Jukka A; Kamshilin, Alexei A; Närhi, Matti; Karjalainen, Pasi A; Giniatullin, Rashid

    2013-01-01

    Asymmetrical changes in blood perfusion and asynchronous blood supply to head tissues likely contribute to migraine pathophysiology. Imaging was widely used in order to understand hemodynamic variations in migraine. However, mapping of blood pulsations in the face of migraineurs has not been performed so far. We used the Blood Pulsation Imaging (BPI) technique, which was recently developed in our group, to establish whether 2D-imaging of blood pulsations parameters can reveal new biomarkers of migraine. BPI characteristics were measured in migraineurs during the attack-free interval and compared to healthy subjects with and without a family history of migraine. We found a novel phenomenon of transverse waves of facial blood perfusion in migraineurs in contrast to healthy subjects who showed synchronous blood delivery to both sides of the face. Moreover, the amplitude of blood pulsations was symmetrically distributed over the face of healthy subjects, but asymmetrically in migraineurs and subjects with a family history of migraine. In the migraine patients we found a remarkable correlation between the side of unilateral headache and the direction of the blood perfusion wave. Our data suggest that migraine is associated with lateralization of blood perfusion and asynchronous blood pulsations in the facial area, which could be due to essential dysfunction of the autonomic vascular control in the face. These findings may further enhance our understanding of migraine pathophysiology and suggest new easily available biomarkers of this pathology.

  2. Perfusion CT in Colorectal Cancer: Comparison of Perfusion Parameters with Tumor Grade and Microvessel Density

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Woong; Jeong, Yong Yeon; Chang, Nam Kyu; Heo, Suk Hee; Hur, Young Hoe; Kang, Heoung Keun [Chonnam National University Hwasun Hospital, Hwasun(Korea, Republic of); Shin, Sang Soo; Lee, Jae Hyuk [Chonnam National University Hospital, Gwangju (Korea, Republic of)

    2012-02-15

    The purpose of this study was to prospectively compare pre-operative computed tomography (CT) perfusion parameters with tumor grade from colorectal adenocarcinoma (CRC) and to correlate pre-operative CT perfusion parameters with microvessel density (MVD) to evaluate angiogenesis in CRC. Pre-operative perfusion CTs were performed with a 64-channel multidetector row CT in 27 patients (17 women and 10 men; age range 32-82 years) who were diagnosed with CRC involving the sigmoid and rectum between August 2006 and November 2007. All patients underwent surgery without pre-operative chemotherapy or radiation therapy. Dynamic perfusion CTs were performed for 65 seconds after intravenous injection of contrast medium (100 mL, 300 mg of iodine per mL, 5 mL/sec). Before surgery, blood flow (BF), blood volume, mean transit time (MTT), and permeability-surface area product were measured in the tumor. After surgery, one gastrointestinal pathologist evaluated tumor grade and performed immunohistochemical staining using CD 34 to determine MVD in each tumor. The Kruskal-Wallis test was used to compare CT perfusion parameters with tumor grade, and Pearson's correlation analysis was used to correlate CT perfusion parameters with MVD. In 27 patients with CRC, tumor grading was as follows: well differentiated (n = 8); moderately differentiated (n = 15); and poorly differentiated (n = 4). BF was higher in moderately differentiated CRC than well differentiated and poorly differentiated CRCs (p = 0.14). MTT was shorter in moderately differentiated than well differentiated and poorly differentiated CRCs (p = 0.039). The MVD was greater in poorly differentiated than well differentiated and moderately differentiated CRCs (p = 0.034). There was no significant correlation between other perfusion parameters and tumor grade. There was no significant correlation between CT perfusion parameters and MVD. BF and MTT measurement by perfusion CT is effective in predicting moderately differentiated CRCs

  3. Media-Augmented Exercise Machines

    Science.gov (United States)

    Krueger, T.

    2002-01-01

    Cardio-vascular exercise has been used to mitigate the muscle and cardiac atrophy associated with adaptation to micro-gravity environments. Several hours per day may be required. In confined spaces and long duration missions this kind of exercise is inevitably repetitive and rapidly becomes uninteresting. At the same time, there are pressures to accomplish as much as possible given the cost- per-hour for humans occupying orbiting or interplanetary. Media augmentation provides a the means to overlap activities in time by supplementing the exercise with social, recreational, training or collaborative activities and thereby reducing time pressures. In addition, the machine functions as an interface to a wide range of digital environments allowing for spatial variety in an otherwise confined environment. We hypothesize that the adoption of media augmented exercise machines will have a positive effect on psycho-social well-being on long duration missions. By organizing and supplementing exercise machines, data acquisition hardware, computers and displays into an interacting system this proposal increases functionality with limited additional mass. This paper reviews preliminary work on a project to augment exercise equipment in a manner that addresses these issues and at the same time opens possibilities for additional benefits. A testbed augmented exercise machine uses a specialty built cycle trainer as both input to a virtual environment and as an output device from it using spatialized sound, and visual displays, vibration transducers and variable resistance. The resulting interactivity increases a sense of engagement in the exercise, provides a rich experience of the digital environments. Activities in the virtual environment and accompanying physiological and psychological indicators may be correlated to track and evaluate the health of the crew.

  4. Volume perfusion CT imaging of cerebral vasospasm: diagnostic performance of different perfusion maps

    Energy Technology Data Exchange (ETDEWEB)

    Othman, Ahmed E. [RWTH Aachen University, Department of Diagnostic and Interventional Neuroradiology, Aachen (Germany); Eberhard Karls University Tuebingen, University Hospital Tuebingen, Department for Diagnostic and Interventional Radiology, Tuebingen (Germany); Afat, Saif; Nikoubashman, Omid; Mueller, Marguerite; Wiesmann, Martin; Brockmann, Carolin [RWTH Aachen University, Department of Diagnostic and Interventional Neuroradiology, Aachen (Germany); Schubert, Gerrit Alexander [RWTH Aachen University, Department of Neurosurgery, Aachen (Germany); Bier, Georg [Eberhard Karls University Tuebingen, University Hospital Tuebingen, Department for Diagnostic and Interventional Neuroradiology, Tuebingen (Germany); Brockmann, Marc A. [RWTH Aachen University, Department of Diagnostic and Interventional Neuroradiology, Aachen (Germany); University Hospital Mainz, Department of Neuroradiology, Mainz (Germany)

    2016-08-15

    In this study, we aimed to evaluate the diagnostic performance of different volume perfusion CT (VPCT) maps regarding the detection of cerebral vasospasm compared to angiographic findings. Forty-one datasets of 26 patients (57.5 ± 10.8 years, 18 F) with subarachnoid hemorrhage and suspected cerebral vasospasm, who underwent VPCT and angiography within 6 h, were included. Two neuroradiologists independently evaluated the presence and severity of vasospasm on perfusion maps on a 3-point Likert scale (0 - no vasospasm, 1 - vasospasm affecting <50 %, 2 - vasospasm affecting >50 % of vascular territory). A third neuroradiologist independently assessed angiography for the presence and severity of vasospasm on a 3-point Likert scale (0 - no vasospasm, 1 - vasospasm affecting < 50 %, 2 - vasospasm affecting > 50 % of vessel diameter). Perfusion maps of cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and time to drain (TTD) were evaluated regarding diagnostic accuracy for cerebral vasospasm with angiography as reference standard. Correlation analysis of vasospasm severity on perfusion maps and angiographic images was performed. Furthermore, inter-reader agreement was assessed regarding findings on perfusion maps. Diagnostic accuracy for TTD and MTT was significantly higher than for all other perfusion maps (TTD, AUC = 0.832; MTT, AUC = 0.791; p < 0.001). TTD revealed higher sensitivity than MTT (p = 0.007). The severity of vasospasm on TTD maps showed significantly higher correlation levels with angiography than all other perfusion maps (p ≤ 0.048). Inter-reader agreement was (almost) perfect for all perfusion maps (kappa ≥ 0.927). The results of this study indicate that TTD maps have the highest sensitivity for the detection of cerebral vasospasm and highest correlation with angiography regarding the severity of vasospasm. (orig.)

  5. Assessment of differential pulmonary blood flow using perfusion magnetic resonance imaging: comparison with radionuclide perfusion scintigraphy.

    Science.gov (United States)

    Molinari, Francesco; Fink, Christian; Risse, Frank; Tuengerthal, Siegfried; Bonomo, Lorenzo; Kauczor, Hans-Ulrich

    2006-08-01

    We sought to assess the agreement between lung perfusion ratios calculated from pulmonary perfusion magnetic resonance imaging (MRI) and those calculated from radionuclide (RN) perfusion scintigraphy. A retrospective analysis of MR and RN perfusion scans was conducted in 23 patients (mean age, 60 +/- 14 years) with different lung diseases (lung cancer = 15, chronic obstructive pulmonary disease = 4, cystic fibrosis = 2, and mesothelioma = 2). Pulmonary perfusion was assessed by a time-resolved contrast-enhanced 3D gradient-echo pulse sequence using parallel imaging and view sharing (TR = 1.9 milliseconds; TE = 0.8 milliseconds; parallel imaging acceleration factor = 2; partition thickness = 4 mm; matrix = 256 x 96; in-plane spatial resolution = 1.87 x 3.75 mm; scan time for each 3D dataset = 1.5 seconds), using gadolinium-based contrast agents (injection flow rate = 5 mL/s, dose = 0.1 mmol/kg of body weight). The peak concentration (PC) of the contrast agent bolus, the pulmonary blood flow (PBF), and blood volume (PBV) were computed from the signal-time curves of the lung. Left-to-right ratios of pulmonary perfusion were calculated from the MR parameters and RN counts. The agreement between these ratios was assessed for side prevalence (sign test) and quantitatively (Deming-regression). MR and RN ratios agreed on side prevalence in 21 patients (91%) with PC, in 20 (87%) with PBF, and in 17 (74%) with PBV. The MR estimations of left-to-right perfusion ratios correlated significantly with those of RN perfusion scans (P lung. Further studies in a larger group of patients are required to fully confirm the clinical suitability of this imaging method.

  6. Machinability of advanced materials

    CERN Document Server

    Davim, J Paulo

    2014-01-01

    Machinability of Advanced Materials addresses the level of difficulty involved in machining a material, or multiple materials, with the appropriate tooling and cutting parameters.  A variety of factors determine a material's machinability, including tool life rate, cutting forces and power consumption, surface integrity, limiting rate of metal removal, and chip shape. These topics, among others, and multiple examples comprise this research resource for engineering students, academics, and practitioners.

  7. Pattern recognition & machine learning

    CERN Document Server

    Anzai, Y

    1992-01-01

    This is the first text to provide a unified and self-contained introduction to visual pattern recognition and machine learning. It is useful as a general introduction to artifical intelligence and knowledge engineering, and no previous knowledge of pattern recognition or machine learning is necessary. Basic for various pattern recognition and machine learning methods. Translated from Japanese, the book also features chapter exercises, keywords, and summaries.

  8. Support vector machines applications

    CERN Document Server

    Guo, Guodong

    2014-01-01

    Support vector machines (SVM) have both a solid mathematical background and good performance in practical applications. This book focuses on the recent advances and applications of the SVM in different areas, such as image processing, medical practice, computer vision, pattern recognition, machine learning, applied statistics, business intelligence, and artificial intelligence. The aim of this book is to create a comprehensive source on support vector machine applications, especially some recent advances.

  9. Machining of titanium alloys

    CERN Document Server

    2014-01-01

    This book presents a collection of examples illustrating the resent research advances in the machining of titanium alloys. These materials have excellent strength and fracture toughness as well as low density and good corrosion resistance; however, machinability is still poor due to their low thermal conductivity and high chemical reactivity with cutting tool materials. This book presents solutions to enhance machinability in titanium-based alloys and serves as a useful reference to professionals and researchers in aerospace, automotive and biomedical fields.

  10. Modelling and simulation of multitechnological machine systems

    Energy Technology Data Exchange (ETDEWEB)

    Holopainen, T. (ed.) [VTT Manufacturing Technology, Espoo (Finland)

    2001-07-01

    The Smart Machines and Systems 2010 (SMART) technology programme 1997-2000 aimed at supporting the machine and electromechanical industries in incorporating the modern technology into their products and processes. The public research projects in this programme were planned to accumulate the latest research results and transfer them for the benefit of industrial product development. The major research topic in the SMART programme was called Modelling and Simulation of Multitechnological Mechatronic Systems. The behaviour of modern machine systems and subsystems addresses many different types of physical phenomena and their mutual interactions: mechanical behaviour of structures, electromagnetic effects, hydraulics, vibrations and acoustics etc. together with associated control systems and software. The actual research was carried out in three separate projects called Modelling and Simulation of Mechtronic Machine Systems for Product Development and Condition Monitoring Purposes (MASI), Virtual Testing of Hydraulically Driven Machines (HYSI), and Control of Low Frequency Vibration of a Mobile Machine (AKSUS). This publication contains the papers presented at the final seminar of these three research projects, held on November 30th at Otaniemi Espoo. (orig.)

  11. Rotating electrical machines

    CERN Document Server

    Le Doeuff, René

    2013-01-01

    In this book a general matrix-based approach to modeling electrical machines is promulgated. The model uses instantaneous quantities for key variables and enables the user to easily take into account associations between rotating machines and static converters (such as in variable speed drives).   General equations of electromechanical energy conversion are established early in the treatment of the topic and then applied to synchronous, induction and DC machines. The primary characteristics of these machines are established for steady state behavior as well as for variable speed scenarios. I

  12. Chaotic Boltzmann machines.

    Science.gov (United States)

    Suzuki, Hideyuki; Imura, Jun-ichi; Horio, Yoshihiko; Aihara, Kazuyuki

    2013-01-01

    The chaotic Boltzmann machine proposed in this paper is a chaotic pseudo-billiard system that works as a Boltzmann machine. Chaotic Boltzmann machines are shown numerically to have computing abilities comparable to conventional (stochastic) Boltzmann machines. Since no randomness is required, efficient hardware implementation is expected. Moreover, the ferromagnetic phase transition of the Ising model is shown to be characterised by the largest Lyapunov exponent of the proposed system. In general, a method to relate probabilistic models to nonlinear dynamics by derandomising Gibbs sampling is presented.

  13. Tribology in machine design

    CERN Document Server

    Stolarski, Tadeusz

    1999-01-01

    ""Tribology in Machine Design is strongly recommended for machine designers, and engineers and scientists interested in tribology. It should be in the engineering library of companies producing mechanical equipment.""Applied Mechanics ReviewTribology in Machine Design explains the role of tribology in the design of machine elements. It shows how algorithms developed from the basic principles of tribology can be used in a range of practical applications within mechanical devices and systems.The computer offers today's designer the possibility of greater stringen

  14. Debugging the virtual machine

    Energy Technology Data Exchange (ETDEWEB)

    Miller, P.; Pizzi, R.

    1994-09-02

    A computer program is really nothing more than a virtual machine built to perform a task. The program`s source code expresses abstract constructs using low level language features. When a virtual machine breaks, it can be very difficult to debug because typical debuggers provide only low level machine implementation in formation to the software engineer. We believe that the debugging task can be simplified by introducing aspects of the abstract design into the source code. We introduce OODIE, an object-oriented language extension that allows programmers to specify a virtual debugging environment which includes the design and abstract data types of the virtual machine.

  15. Electrical machines & drives

    CERN Document Server

    Hammond, P

    1985-01-01

    Containing approximately 200 problems (100 worked), the text covers a wide range of topics concerning electrical machines, placing particular emphasis upon electrical-machine drive applications. The theory is concisely reviewed and focuses on features common to all machine types. The problems are arranged in order of increasing levels of complexity and discussions of the solutions are included where appropriate to illustrate the engineering implications. This second edition includes an important new chapter on mathematical and computer simulation of machine systems and revised discussions o

  16. Machine learning with R

    CERN Document Server

    Lantz, Brett

    2013-01-01

    Written as a tutorial to explore and understand the power of R for machine learning. This practical guide that covers all of the need to know topics in a very systematic way. For each machine learning approach, each step in the process is detailed, from preparing the data for analysis to evaluating the results. These steps will build the knowledge you need to apply them to your own data science tasks.Intended for those who want to learn how to use R's machine learning capabilities and gain insight from your data. Perhaps you already know a bit about machine learning, but have never used R; or

  17. Induction machine handbook

    CERN Document Server

    Boldea, Ion

    2002-01-01

    Often called the workhorse of industry, the advent of power electronics and advances in digital control are transforming the induction motor into the racehorse of industrial motion control. Now, the classic texts on induction machines are nearly three decades old, while more recent books on electric motors lack the necessary depth and detail on induction machines.The Induction Machine Handbook fills industry's long-standing need for a comprehensive treatise embracing the many intricate facets of induction machine analysis and design. Moving gradually from simple to complex and from standard to

  18. Ventilation-perfusion distribution in normal subjects.

    Science.gov (United States)

    Beck, Kenneth C; Johnson, Bruce D; Olson, Thomas P; Wilson, Theodore A

    2012-09-01

    Functional values of LogSD of the ventilation distribution (σ(V)) have been reported previously, but functional values of LogSD of the perfusion distribution (σ(q)) and the coefficient of correlation between ventilation and perfusion (ρ) have not been measured in humans. Here, we report values for σ(V), σ(q), and ρ obtained from wash-in data for three gases, helium and two soluble gases, acetylene and dimethyl ether. Normal subjects inspired gas containing the test gases, and the concentrations of the gases at end-expiration during the first 10 breaths were measured with the subjects at rest and at increasing levels of exercise. The regional distribution of ventilation and perfusion was described by a bivariate log-normal distribution with parameters σ(V), σ(q), and ρ, and these parameters were evaluated by matching the values of expired gas concentrations calculated for this distribution to the measured values. Values of cardiac output and LogSD ventilation/perfusion (Va/Q) were obtained. At rest, σ(q) is high (1.08 ± 0.12). With the onset of ventilation, σ(q) decreases to 0.85 ± 0.09 but remains higher than σ(V) (0.43 ± 0.09) at all exercise levels. Rho increases to 0.87 ± 0.07, and the value of LogSD Va/Q for light and moderate exercise is primarily the result of the difference between the magnitudes of σ(q) and σ(V). With known values for the parameters, the bivariate distribution describes the comprehensive distribution of ventilation and perfusion that underlies the distribution of the Va/Q ratio.

  19. A model system for perfusion quantification using FAIR

    DEFF Research Database (Denmark)

    Andersen, Irene Klærke; Sidaros, Karam; Gesmar, Henrik

    2000-01-01

    Flow-sensitive experiments (FAIR) have been performed on a tube-flow phantom in order to validate quantitative perfusion measurements on humans. A straight-forward correspondence between perfusion and bulk-flow is found. It is shown that the flow phantom model only holds when the slice profiles...... to perfusion values lower than the cortical perfusion in the brain. Thus, the experimental accuracy and the computational methods for quantitative perfusion measurements in vivo can be validated by a tube-flow phantom....

  20. A model system for perfusion quantification using FAIR

    DEFF Research Database (Denmark)

    Andersen, I.K.; Sidaros, Karam; Gesmar, H

    2000-01-01

    Flow-sensitive experiments (FAIR) have been performed on a tube-flow phantom in order to validate quantitative perfusion measurements on humans. A straight-forward correspondence between perfusion and bulk-flow is found. It is shown that the flow phantom model only holds when the slice profiles...... to perfusion values lower than the cortical perfusion in the brain. Thus, the experimental accuracy and the computational methods for quantitative perfusion measurements in vivo can be validated by a tube-flow phantom...

  1. Machine Learning Techniques in Clinical Vision Sciences.

    Science.gov (United States)

    Caixinha, Miguel; Nunes, Sandrina

    2017-01-01

    This review presents and discusses the contribution of machine learning techniques for diagnosis and disease monitoring in the context of clinical vision science. Many ocular diseases leading to blindness can be halted or delayed when detected and treated at its earliest stages. With the recent developments in diagnostic devices, imaging and genomics, new sources of data for early disease detection and patients' management are now available. Machine learning techniques emerged in the biomedical sciences as clinical decision-support techniques to improve sensitivity and specificity of disease detection and monitoring, increasing objectively the clinical decision-making process. This manuscript presents a review in multimodal ocular disease diagnosis and monitoring based on machine learning approaches. In the first section, the technical issues related to the different machine learning approaches will be present. Machine learning techniques are used to automatically recognize complex patterns in a given dataset. These techniques allows creating homogeneous groups (unsupervised learning), or creating a classifier predicting group membership of new cases (supervised learning), when a group label is available for each case. To ensure a good performance of the machine learning techniques in a given dataset, all possible sources of bias should be removed or minimized. For that, the representativeness of the input dataset for the true population should be confirmed, the noise should be removed, the missing data should be treated and the data dimensionally (i.e., the number of parameters/features and the number of cases in the dataset) should be adjusted. The application of machine learning techniques in ocular disease diagnosis and monitoring will be presented and discussed in the second section of this manuscript. To show the clinical benefits of machine learning in clinical vision sciences, several examples will be presented in glaucoma, age-related macular degeneration

  2. Stirling machine operating experience

    Energy Technology Data Exchange (ETDEWEB)

    Ross, B. [Stirling Technology Co., Richland, WA (United States); Dudenhoefer, J.E. [Lewis Research Center, Cleveland, OH (United States)

    1994-09-01

    Numerous Stirling machines have been built and operated, but the operating experience of these machines is not well known. It is important to examine this operating experience in detail, because it largely substantiates the claim that stirling machines are capable of reliable and lengthy operating lives. The amount of data that exists is impressive, considering that many of the machines that have been built are developmental machines intended to show proof of concept, and are not expected to operate for lengthy periods of time. Some Stirling machines (typically free-piston machines) achieve long life through non-contact bearings, while other Stirling machines (typically kinematic) have achieved long operating lives through regular seal and bearing replacements. In addition to engine and system testing, life testing of critical components is also considered. The record in this paper is not complete, due to the reluctance of some organizations to release operational data and because several organizations were not contacted. The authors intend to repeat this assessment in three years, hoping for even greater participation.

  3. Perpetual Motion Machine

    Directory of Open Access Journals (Sweden)

    D. Tsaousis

    2008-01-01

    Full Text Available Ever since the first century A.D. there have been relative descriptions of known devices as well as manufactures for the creation of perpetual motion machines. Although physics has led, with two thermodynamic laws, to the opinion that a perpetual motion machine is impossible to be manufactured, inventors of every age and educational level appear to claim that they have invented something «entirely new» or they have improved somebody else’s invention, which «will function henceforth perpetually»! However the fact of the failure in manufacturing a perpetual motion machine till now, it does not mean that countless historical elements for these fictional machines become indifferent. The discussion on every version of a perpetual motion machine on the one hand gives the chance to comprehend the inventor’s of each period level of knowledge and his way of thinking, and on the other hand, to locate the points where this «perpetual motion machine» clashes with the laws of nature and that’s why it is impossible to have been manufactured or have functioned. The presentation of a new «perpetual motion machine» has excited our interest to locate its weak points. According to the designer of it the machine functions with the work produced by the buoyant force

  4. Machine Intelligence and Explication

    NARCIS (Netherlands)

    Wieringa, Roelf J.

    1987-01-01

    This report is an MA ("doctoraal") thesis submitted to the department of philosophy, university of Amsterdam. It attempts to answer the question whether machines can think by conceptual analysis. Ideally. a conceptual analysis should give plausible explications of the concepts of "machine" and "inte

  5. Microsoft Azure machine learning

    CERN Document Server

    Mund, Sumit

    2015-01-01

    The book is intended for those who want to learn how to use Azure Machine Learning. Perhaps you already know a bit about Machine Learning, but have never used ML Studio in Azure; or perhaps you are an absolute newbie. In either case, this book will get you up-and-running quickly.

  6. Reactive Turing machines

    NARCIS (Netherlands)

    Baeten, J.C.M.; Luttik, B.; Tilburg, P.J.A. van

    2013-01-01

    We propose reactive Turing machines (RTMs), extending classical Turing machines with a process-theoretical notion of interaction, and use it to define a notion of executable transition system. We show that every computable transition system with a bounded branching degree is simulated modulo diverge

  7. Machine Intelligence and Explication

    NARCIS (Netherlands)

    Wieringa, Roel

    1987-01-01

    This report is an MA ("doctoraal") thesis submitted to the department of philosophy, university of Amsterdam. It attempts to answer the question whether machines can think by conceptual analysis. Ideally. a conceptual analysis should give plausible explications of the concepts of "machine" and "inte

  8. Coordinate measuring machines

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo

    This document is used in connection with three exercises of 2 hours duration as a part of the course GEOMETRICAL METROLOGY AND MACHINE TESTING. The exercises concern three aspects of coordinate measuring: 1) Measuring and verification of tolerances on coordinate measuring machines, 2) Traceability...

  9. Simple Machine Junk Cars

    Science.gov (United States)

    Herald, Christine

    2010-01-01

    During the month of May, the author's eighth-grade physical science students study the six simple machines through hands-on activities, reading assignments, videos, and notes. At the end of the month, they can easily identify the six types of simple machine: inclined plane, wheel and axle, pulley, screw, wedge, and lever. To conclude this unit,…

  10. Human Machine Learning Symbiosis

    Science.gov (United States)

    Walsh, Kenneth R.; Hoque, Md Tamjidul; Williams, Kim H.

    2017-01-01

    Human Machine Learning Symbiosis is a cooperative system where both the human learner and the machine learner learn from each other to create an effective and efficient learning environment adapted to the needs of the human learner. Such a system can be used in online learning modules so that the modules adapt to each learner's learning state both…

  11. Machine learning with R

    CERN Document Server

    Lantz, Brett

    2015-01-01

    Perhaps you already know a bit about machine learning but have never used R, or perhaps you know a little R but are new to machine learning. In either case, this book will get you up and running quickly. It would be helpful to have a bit of familiarity with basic programming concepts, but no prior experience is required.

  12. 15 CFR 700.31 - Metalworking machines.

    Science.gov (United States)

    2010-01-01

    ... Drilling and tapping machines Electrical discharge, ultrasonic and chemical erosion machines Forging..., power driven Machining centers and way-type machines Manual presses Mechanical presses, power...

  13. Image analysis of intracranial high perfusion lesion by whole brain one-stop imaging technique with 320 detector rows CT

    Directory of Open Access Journals (Sweden)

    Fei-zhou DU

    2014-03-01

    Full Text Available Objective  The perfusion and vascular architecture features were investigated and evaluated by use of one-stop imaging technique with 320 rows CT for exploring the clinical value of one-stop imaging technique in the diagnosis of intracranial lesions. Methods  The perfusion parameters and vascular architecture of intracranial high perfusion lesions of 52 patients were collected in General Hospital of Chengdu Command from Oct. 2010 to Apr. 2013, who were examined by one-stop imaging technique with 320 rows CT, were retrospectively analyzed. The perfusion values of normal contralateral cerebral tissue were used as control to analyze the perfusion and vascular architecture features of injured parts. Results  Of the 52 patients, there were 16 cases of subacute cerebral infarction, 9 cases of arteriovenous malformation, 7 cases of hemangioma, 12 cases of meningioma, and 8 cases of glioma. All the patients showed elevated CBV and/or CBF and different changes in mean transit time (MTT, time to peak (TTP and delay time (Delay. In the cases of subacute cerebral infarction, the parameters of MTT, TTP and Delay increased. In the cases of arteriovenous malformation, all the parameters decreased. In the cases of hemangioma, the MTT decreased, while TTP and Delay increased. In the cases of glioma, the TTP and Delay increased, while the change of MTT varied. Meanwhile, abnormality of vascular structures was found in all the cases by CT angiography. Conclusion  With whole brain perfusion and one-stop vascular imaging with 320 rows CT, the perfusion characteristics of intracranial lesions can be revealed completely, including blood supply and microcirculation changes in the lesions, and it may be of benefit in guiding the clinical diagnosis and treatment. DOI: 10.11855/j.issn.0577-7402.2014.03.10

  14. LHC Report: machine development

    CERN Multimedia

    Rogelio Tomás García for the LHC team

    2015-01-01

    Machine development weeks are carefully planned in the LHC operation schedule to optimise and further study the performance of the machine. The first machine development session of Run 2 ended on Saturday, 25 July. Despite various hiccoughs, it allowed the operators to make great strides towards improving the long-term performance of the LHC.   The main goals of this first machine development (MD) week were to determine the minimum beam-spot size at the interaction points given existing optics and collimation constraints; to test new beam instrumentation; to evaluate the effectiveness of performing part of the beam-squeezing process during the energy ramp; and to explore the limits on the number of protons per bunch arising from the electromagnetic interactions with the accelerator environment and the other beam. Unfortunately, a series of events reduced the machine availability for studies to about 50%. The most critical issue was the recurrent trip of a sextupolar corrector circuit –...

  15. Micro-machining.

    Science.gov (United States)

    Brinksmeier, Ekkard; Preuss, Werner

    2012-08-28

    Manipulating bulk material at the atomic level is considered to be the domain of physics, chemistry and nanotechnology. However, precision engineering, especially micro-machining, has become a powerful tool for controlling the surface properties and sub-surface integrity of the optical, electronic and mechanical functional parts in a regime where continuum mechanics is left behind and the quantum nature of matter comes into play. The surprising subtlety of micro-machining results from the extraordinary precision of tools, machines and controls expanding into the nanometre range-a hundred times more precise than the wavelength of light. In this paper, we will outline the development of precision engineering, highlight modern achievements of ultra-precision machining and discuss the necessity of a deeper physical understanding of micro-machining.

  16. Introduction to machine learning.

    Science.gov (United States)

    Baştanlar, Yalin; Ozuysal, Mustafa

    2014-01-01

    The machine learning field, which can be briefly defined as enabling computers make successful predictions using past experiences, has exhibited an impressive development recently with the help of the rapid increase in the storage capacity and processing power of computers. Together with many other disciplines, machine learning methods have been widely employed in bioinformatics. The difficulties and cost of biological analyses have led to the development of sophisticated machine learning approaches for this application area. In this chapter, we first review the fundamental concepts of machine learning such as feature assessment, unsupervised versus supervised learning and types of classification. Then, we point out the main issues of designing machine learning experiments and their performance evaluation. Finally, we introduce some supervised learning methods.

  17. Hepatic perfusion changes in an experimental model of acute pancreatitis: Evaluation by perfusion CT

    Energy Technology Data Exchange (ETDEWEB)

    Tutcu, Semra [Department of Surgery, Celal Bayar University, School of Medicine, Manisa (Turkey); Serter, Selim, E-mail: serterselim@gmail.co [Department of Radiology, Celal Bayar University, School of Medicine, Manisa (Turkey); Kaya, Yavuz; Kara, Eray [Department of Surgery, Celal Bayar University, School of Medicine, Manisa (Turkey); Nese, Nalan [Department of Pathology, Celal Bayar University, School of Medicine, Manisa (Turkey); Pekindil, Goekhan [Department of Radiology, Celal Bayar University, School of Medicine, Manisa (Turkey); Coskun, Teoman [Department of Surgery, Celal Bayar University, School of Medicine, Manisa (Turkey)

    2010-08-15

    Purpose: It is known that acute pancreatitis may cause secondary changes in several organs. Liver is one of these involved organs. In different experimental studies hepatic damages were shown histopathologically in acute pancreatitis but there are a few studies about perfusion disorders that accompany these histopathologic changes. Perfusion CT (pCT) provides the ability to detect regional and global alterations in organ blood flow. The purpose of the study was to describe hepatic perfusion changes in experimental acute pancreatitis model with pCT. Materials and methods: Forty Sprague-Dawley rats of both genders with average weights of 250 g were used. Rats were randomized into two groups. Twenty rats were in control group and 20 in acute pancreatitis group. pCT was performed. Perfusion maps were formed by processing the obtained images with perfusion CT software. Blood flow (BF) and blood volume (BV) values were obtained from these maps. All pancreatic and liver tissues were taken off with laparotomy and histopathologic investigation was performed. Student's t test was used for statistical analyses. Results: In pCT we found statistically significant increase in blood volume in both lobes of liver and in blood flow in right lobe of the liver (p < 0.01). Although blood flow in left lobe of the liver increased, it did not reach statistical significance. Conclusion: The quantitative analysis of liver parenchyma with pCT showed that acute pancreatitis causes a significant perfusion changes in the hepatic tissue. Systemic mediators seem to be effective as well as local inflammatory changes in perfusion changes.

  18. Patient satisfaction with coronary CT angiography, myocardial CT perfusion, myocardial perfusion MRI, SPECT myocardial perfusion imaging and conventional coronary angiography

    Energy Technology Data Exchange (ETDEWEB)

    Feger, S.; Rief, M.; Zimmermann, E.; Richter, F.; Roehle, R. [Freie Universitaet Berlin, Department of Radiology, Charite - Universitaetsmedizin Berlin Campus Mitte, Humboldt-Universitaet zu Berlin, Berlin (Germany); Dewey, M. [Freie Universitaet Berlin, Department of Radiology, Charite - Universitaetsmedizin Berlin Campus Mitte, Humboldt-Universitaet zu Berlin, Berlin (Germany); Institut fuer Radiologie, Berlin (Germany); Schoenenberger, E. [Medizinische Hochschule Hannover, Department of Medicine, Hannover (Germany)

    2015-07-15

    To evaluate patient acceptance of noninvasive imaging tests for detection of coronary artery disease (CAD), including single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI), stress perfusion magnetic resonance imaging (MRI), coronary CT angiography (CTA) in combination with CT myocardial stress perfusion (CTP), and conventional coronary angiography (CCA). Intraindividual comparison of perception of 48 patients from the CORE320 multicentre multinational study who underwent rest and stress SPECT-MPI with a technetium-based tracer, combined CTA and CTP (both with contrast agent, CTP with adenosine), MRI, and CCA. The analysis was performed by using a validated questionnaire. Patients had significantly more concern prior to CCA than before CTA/CTP (p < 0.001). CTA/CTP was also rated as more comfortable than SPECT-MPI (p = 0.001). Overall satisfaction with CT was superior to that of MRI (p = 0.007). More patients preferred CT (46 %; p < 0.001) as a future diagnostic test. Regarding combined CTA/CTP, CTP was characterised by higher pain levels and an increased frequency of angina pectoris during the examination (p < 0.001). Subgroup analysis showed a higher degree of pain during SPECT-MPI with adenosine stress compared to physical exercise (p = 0.016). All noninvasive cardiac imaging tests are well accepted by patients, with CT being the preferred examination. (orig.)

  19. First steps in membrane oxygenation and prolonged extracorporeal perfusion in Duesseldorf using the Bramson membrane lung.

    Science.gov (United States)

    Schulte, Hagen D

    2003-05-01

    After a shortened history of conventional closed and open heart surgery, including hypothermia by surface cooling and extracorporeal circulation, the first application of a new membrane oxygenator developed by ML Bramson with an integrated temperature exchange system and a heart-lung machine (HLM) was reported in 1972. The aim was to have an efficient oxygenating and gas exchange artificial lung that allowed prolonged perfusions in patients with cardiogenic shock or acute respiratory insufficiency. After in vitro closed recirculation studies comparing different bubble, vertical screen, and the new membrane oxygenators, the Bramson HLM was used in dog experiments before starting clinical cardiac surgery with routine interventions (closure of an atrial septal defect). The first clinically prolonged support for more than three hours after a double valve replacement in a NYHA class IV patient failed. A partial venoarterial prolonged perfusion for 42 hours and 43 minutes in a 10-year-old girl after surgical correction of a partial av canal defect and postoperative development of consistent lung edema caused by myocardial failure after an ischemic time of 43 minutes was the first successful long-term perfusion case in Europe. These first experiences with the Bramson membrane lung formed the basis, in our group, for further investigations of different perfusion routes and cannulations in animal experiments. Also, scanning electron microscopy studies could be performed with experimentally and clinically used membranes. The development of disposable membrane lung devices, for instance, Lande-Edwards, Kolobow Scimed, and General Electric Peirce membrane lungs, ameliorated and improved the use of these devices considerably. Also, BRAMSON had developed a disposable membrane lung device that had proved to be very effective in animal experiments by 1972, but, unfortunately, this device did not become commercially available.

  20. NASA's online machine aided indexing system

    Science.gov (United States)

    Silvester, June P.; Genuardi, Michael T.; Klingbiel, Paul H.

    1993-01-01

    This report describes the NASA Lexical Dictionary, a machine aided indexing system used online at the National Aeronautics and Space Administration's Center for Aerospace Information (CASI). This system is comprised of a text processor that is based on the computational, non-syntactic analysis of input text, and an extensive 'knowledge base' that serves to recognize and translate text-extracted concepts. The structure and function of the various NLD system components are described in detail. Methods used for the development of the knowledge base are discussed. Particular attention is given to a statistically-based text analysis program that provides the knowledge base developer with a list of concept-specific phrases extracted from large textual corpora. Production and quality benefits resulting from the integration of machine aided indexing at CASI are discussed along with a number of secondary applications of NLD-derived systems including on-line spell checking and machine aided lexicography.

  1. ADAPTABLE DESIGN OF MACHINE TOOLS STRUCTURES

    Institute of Scientific and Technical Information of China (English)

    XU Yanshen; CHEN Yongliang; ZHANG Guojun; GU Peihua

    2008-01-01

    Adaptable design aims to extend the utilities of design and product. The specific methods are developed for practical applications of adaptable design in the design of mechanical structures, including adaptable platform, interface and module designs. Adaptable redesign problems are formulated as adaptable platform design under adaptability bound constraints. Analysis tools are then suggested for the implementation of the redesign of machine tool structures, including variation techniques based sensitivity analysis, similarity-based commonality analysis, performance improvement, and adaptability measures. The specific measure of adaptability for machine tool structures is measured through the quantification of the structural similarity and performance improvement gained from adaptable design. The method provides designers with an approach that brings adaptability into the design process, with considering the cost and benefits of such adaptability. The redesign of CNC spiral bevel gear cutting machine structures has been included to illustrate these concepts and methods.

  2. Retrograde coronary sinus versus aortic root perfusion with cold cardioplegia: randomized study of levels of cardiac enzymes in 40 patients

    Energy Technology Data Exchange (ETDEWEB)

    Guiraudon, G.M.; Campbell, C.S.; McLellan, D.G.; Kostuk, W.J.; Purves, P.D.; MacDonald, J.L.; Cleland, A.G.; Tadros, N.B.

    1986-11-01

    Myocardial injury was assessed with the use of enzyme indexes in 40 patients randomly assigned to one of two groups undergoing coronary artery bypass surgery. Twenty patients received cold cardioplegia delivered by retrograde coronary sinus perfusion and 20 received cardioplegic solution by anterograde aortic root perfusion. Creatine kinase isoenzyme MB and lactate dehydrogenese isoenzyme 1 and isoenzyme 2 assays were carried out on blood samples obtained from the coronary sinus before aortic cross-clamping and 0, 5, and 30 min after aortic unclamping. Levels of these enzymes were also obtained from venous blood samples before aortic cross-clamping and 3, 8, 14, and 20 hr after aortic unclamping and 2, 3, 4, and 5 days after surgery. Preoperative and postoperative hemodynamic measurements (Swan-Ganz catheter) and radionuclide wall motion studies were also obtained for comparison. There was no overall significant difference between the two groups postoperatively in terms of enzyme indexes, hemodynamic measurements, or results of wall motion studies. We conclude that retrograde coronary sinus perfusion is an alternative to aortic root perfusion in delivering cold cardioplegia. More studies are required to determine which subgroup of patients with coronary artery disease may benefit from retrograde coronary perfusion.

  3. CT perfusion: ready for prime time.

    Science.gov (United States)

    Ambrose, Marietta S; Valdiviezo, Carolina; Mehra, Vishal; Lardo, Albert C; Lima, Joao A C; George, Richard T

    2011-02-01

    Advancements in computed tomography (CT) technology have revolutionized clinical practice, particularly regarding the noninvasive assessment of coronary artery disease (CAD). The versatility of cardiac CT has rendered multiple applications including assessment of cardiac structure and function, myocardial viability, and coronary anatomy. The merits of cardiac computed tomography angiography (CTA) have been proven for the detection, and particularly the exclusion, of CAD. However, CTA becomes limited in the presence of significant CAD. Its inability to consistently identify lesion-associated ischemia may necessitate additional radionuclide myocardial perfusion imaging. Myocardial computed tomography perfusion imaging (CTP) has emerged as a useful and convenient method to immediately assess myocardial ischemia. In this review, we discuss the current state of CTP including available technology, its performance to date from current literature, and future challenges to this field.

  4. Staging of moyamoya disease by perfusion SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Kuwabara, Yasuo [Kyushu Univ., Fukuoka (Japan). Hospital; Matsushima, Toshio; Fukui, Masashi

    2001-04-01

    Staging of moyamoya disease, based on angiography and PET have already been established. The authors have established staging of moyamoya disease based on perfusion SPECT, that can be summarized as follows: Stage I, no abnormality is seen at rest or after acetazolamide loading; Stage II, no abnormality is seen at rest, however, a decreased response (blood flow increase rate: <15%) is seen to acetazolamide loading (a, a decreased response is seen only in the frontal lobe; b, a decreased response is seen in regions other than the frontal lobe; and c, a decreased response is seen throughout the cerebrum); Stage III, localized decrease in blood flow (blood flow decrease compared with peripheral tissue: {>=}15%) and marked decrease in response to acetazolamide (blood flow increase rate: <5%) are seen at rest. In Stage III, CT and MRI show no abnormal findings or only mild lesions of the white matter; and Stage IV, multiple decreases in blood flow are seen at rest, and CT and MRI reveal infarctions and severe atrophy at the same sites. The above staging does not require determination of cerebral blood flow, and thus it can be used in children, in whom cerebral blood flow determination is difficult. The authors performed 99m-Tc ECD perfusion SPECT in 25 patients with moyamoya disease for the staging, and compared staging based on angiography with staging based on perfusion SPECT. The results did not show a correlation between the 2 staging methods. A problem inherent in the staging of moyamoya disease based on perfusion SPECT is that the relationship between cerebral blood flow and cerebral radioactivity concentrations may differ depending on the drug used to determine cerebral blood flow. Thus, although the present staging system does not depend on any specific radioactive drug to determine cerebral blood flow, further investigation is necessary to identify a more appropriate drug than those in current use. (K.H.)

  5. Exercise: Benefits of Exercise

    Medline Plus

    Full Text Available ... A-Z > Exercise: Benefits of Exercise: Health Benefits In This Topic Health Benefits Benefits for Everyday Life ... Try Exercise: How to Stay Active The information in this topic was provided by the National Institute ...

  6. Non-contrast MRI perfusion angiosome in diabetic feet

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jie [Cardiovascular Imaging Lab, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Hastings, Mary K.; Mueller, Michael J. [Washington University School of Medicine, The Program in Physical Therapy, St. Louis, MO (United States); Muccigross, David; Hildebolt, Charles F. [Washington University School of Medicine, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Fan, Zhaoyang [Cedars-Sinai Medical Center, Biomedical Imaging Research Institute, Los Angeles, CA (United States); Gao, Fabao [West China Hospital, Sichuan University, Department of Radiology, Chengdu (China); Curci, John [Washington University School of Medicine, The Department of Surgery, St. Louis, MO (United States)

    2015-01-15

    The purpose of this study is to develop a non-contrast magnetic resonance imaging (MRI) approach to evaluate skeletal muscle perfusion in the diabetic foot based on the concept of angiosomes of the foot. Five healthy volunteers and five participants with diabetes (HbA1c = 7.2 ± 1.8 %) without a history of peripheral artery disease were examined. The non-contrast perfusion measurements were performed during a toe flexion challenge. Absolute perfusion maps were created and two regions (medial and lateral) on the maps were segmented based on angiosomes. Regional difference in the perfusion of foot muscle was readily visualized in the MRI perfusion angiosomes during the challenge. In the participants with diabetes, the perfusion during toe flexion challenge was significantly lower than in healthy volunteers (P < 0.01). The average perfusion for the medial plantar region of the right foot was lower in subjects with diabetes (38 ± 9 ml/min/100 g) than in healthy subjects (93 ± 33 ml/min/100 g). Non-contrast MRI perfusion angiosome maps demonstrate the feasibility of determining regional perfusion in foot muscles during toe challenge and may facilitate evaluation of muscle perfusion in diabetic feet. (orig.)

  7. CT perfusion: principles, applications, and problems

    Science.gov (United States)

    Lee, Ting-Yim

    2004-10-01

    The fast scanning speed of current slip-ring CT scanners has enabled the development of perfusion imaging techniques with intravenous injection of contrast medium. In a typical CT perfusion study, contrast medium is injected and rapid scanning at a frequency of 1-2 Hz is used to monitor the first circulation of the injected contrast medium through a 1-2 cm thick slab of tissue. From the acquired time-series of CT images, arteries can be identified within the tissue slab to derive the arterial contrast concentration curve, Ca(t) while each individual voxel produces a tissue residue curve, Q(t) for the corresponding tissue region. Deconvolution between the measured Ca(t) and Q(t) leads to the determination of cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) in brain studies. In this presentation, an important application of CT perfusion in acute stroke studies - the identification of the ischemic penumbra via the CBF/CBV mismatch and factors affecting the quantitative accuracy of deconvolution, including partial volume averaging, arterial delay and dispersion are discussed.

  8. Myocardial perfusion imaging with dual energy CT.

    Science.gov (United States)

    Jin, Kwang Nam; De Cecco, Carlo N; Caruso, Damiano; Tesche, Christian; Spandorfer, Adam; Varga-Szemes, Akos; Schoepf, U Joseph

    2016-10-01

    Dual-energy CT (DECT) enables simultaneous use of two different tube voltages, thus different x-ray absorption characteristics are acquired in the same anatomic location with two different X-ray spectra. The various DECT techniques allow material decomposition and mapping of the iodine distribution within the myocardium. Static dual-energy myocardial perfusion imaging (sCTMPI) using pharmacological stress agents demonstrate myocardial ischemia by single snapshot images of myocardial iodine distribution. sCTMPI gives incremental values to coronary artery stenosis detected on coronary CT angiography (CCTA) by showing consequent reversible or fixed myocardial perfusion defects. The comprehensive acquisition of CCTA and sCTMPI offers extensive morphological and functional evaluation of coronary artery disease. Recent studies have revealed that dual-energy sCTMPI shows promising diagnostic accuracy for the detection of hemodynamically significant coronary artery disease compared to single-photon emission computed tomography, invasive coronary angiography, and cardiac MRI. The aim of this review is to present currently available DECT techniques for static myocardial perfusion imaging and recent clinical applications and ongoing investigations.

  9. Perfusion computed tomography in renal cell carcinoma

    Institute of Scientific and Technical Information of China (English)

    Chandan; J; Das; Usha; Thingujam; Ananya; Panda; Sanjay; Sharma; Arun; Kumar; Gupta

    2015-01-01

    Various imaging modalities are available for the diagnosis, staging and response evaluation of patients with renal cell carcinoma(RCC). While contrast enhanced computed tomography(CT) is used as the standard of imaging for size, morphological evaluation and response assessment in RCC, a new functional imaging technique like perfusion CT(p CT), goes down to the molecular level and provides new perspectives in imaging of RCC. p CT depicts regional tumor perfusion and vascular permeability which are indirect parameters of tumor angiogenesis and thereby provides vital information regarding tumor microenvironment. Also response evaluation using p CT may predate the size criteria used in Response Evaluation Criteria in Solid Tumors, as changes in the perfusion occurs earlier following tissue kinase inhibitors before any actual change in size. This may potentially help in predicting prognosis, better selection of therapy and more accurate and better response evaluation in patients with RCC. This article describes the techniques and role of p CT in staging and response assessment in patients with RCCs.

  10. Perfusion patterns in migraine with aura.

    Science.gov (United States)

    Förster, Alex; Wenz, Holger; Kerl, Hans U; Brockmann, Marc A; Groden, Christoph

    2014-10-01

    Migraine with aura is a common neurological disorder, and differentiation from transient ischemic attack or stroke based on clinical symptoms may be difficult. From an MRI report database we identified 33 patients with migraine with aura and compared these to 33 age-matched ischemic stroke patients regarding perfusion patterns on perfusion-weighted imaging (PWI)-derived maps: time to peak (TTP), mean transit time (MTT), and cerebral blood flow and volume (CBF, CBV). In 18/33 (54.5%) patients with migraine with aura, TTP showed areas of hypoperfusion, most of these not limited to the territory of a specific artery but affecting two or more vascular territories. In patients with migraine with aura, TTP (1.09 ± 0.05 vs. 1.47 ± 0.40, p aura is usually associated with a perfusion deficit not limited to a specific vascular territory, and only a moderate increase of TTP. Thus, hypoperfusion restricted to a single vascular territory in combination with a marked increase of TTP or MTT may be regarded as atypical for migraine aura and suggestive of acute ischemic stroke. © International Headache Society 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  11. Phosphorus NMR of isolated perfused morris hepatomas

    Energy Technology Data Exchange (ETDEWEB)

    Graham, R.A.; Meyer, R.A.; Brown, T.R.; Sauer, L.A.

    1986-03-05

    The authors are developing techniques for the study of perfused solid tumors by NMR. Tissue-isolated solid hepatomas were grown to 1-2 cm diameter as described previously. The arterial supply was isolated and the tumors perfused (0.5 - 1.0 ml/min) in vitro at 25 C with a 15% suspension of red blood cells in Krebs-Henseliet solution. /sup 31/P-NMR spectra were acquired at 162 MHz in a specially-designed NMR probe using a solenoidal coil. Intracellular pH (monitored from the chemical shift of inorganic phosphate) and ATP levels were stable for up to 6 hrs during perfusion. During 30 min of global ischemia, ATP decreased by 75% and pH fell from 7.0 to 6.7. These changes were reversed by 1 hr reperfusion. In addition to ATP and phosphate, the spectra included a large resonance due to phosphomonoesters, as well as peaks consistent with glycerylphosphocholine, glyceryl-phosphoethanolamine, phosphocreatine, NAD, and UDPG. However, the most novel feature of the spectra was the presence of an unidentified peak in the phosphonate region (+ 16.9 ppm). The peak was not present in spectra of muscle, liver, brain, kidney, or fat tissues excised from the same animals. They are presently attempting to identify the compound that gives rise to this peak and to establish its metabolic origin.

  12. Dynamic CT perfusion measurement in a cardiac phantom.

    Science.gov (United States)

    Ziemer, Benjamin P; Hubbard, Logan; Lipinski, Jerry; Molloi, Sabee

    2015-10-01

    Widespread clinical implementation of dynamic CT myocardial perfusion has been hampered by its limited accuracy and high radiation dose. The purpose of this study was to evaluate the accuracy and radiation dose reduction of a dynamic CT myocardial perfusion technique based on first pass analysis (FPA). To test the FPA technique, a pulsatile pump was used to generate known perfusion rates in a range of 0.96-2.49 mL/min/g. All the known perfusion rates were determined using an ultrasonic flow probe and the known mass of the perfusion volume. FPA and maximum slope model (MSM) perfusion rates were measured using volume scans acquired from a 320-slice CT scanner, and then compared to the known perfusion rates. The measured perfusion using FPA (P(FPA)), with two volume scans, and the maximum slope model (P(MSM)) were related to known perfusion (P(K)) by P(FPA) = 0.91P(K) + 0.06 (r = 0.98) and P(MSM) = 0.25P(K) - 0.02 (r = 0.96), respectively. The standard error of estimate for the FPA technique, using two volume scans, and the MSM was 0.14 and 0.30 mL/min/g, respectively. The estimated radiation dose required for the FPA technique with two volume scans and the MSM was 2.6 and 11.7-17.5 mSv, respectively. Therefore, the FPA technique can yield accurate perfusion measurements using as few as two volume scans, corresponding to approximately a factor of four reductions in radiation dose as compared with the currently available MSM. In conclusion, the results of the study indicate that the FPA technique can make accurate dynamic CT perfusion measurements over a range of clinically relevant perfusion rates, while substantially reducing radiation dose, as compared to currently available dynamic CT perfusion techniques.

  13. Efficient Checkpointing of Virtual Machines using Virtual Machine Introspection

    Energy Technology Data Exchange (ETDEWEB)

    Aderholdt, Ferrol [Tennessee Technological University; Han, Fang [Tennessee Technological University; Scott, Stephen L [ORNL; Naughton, III, Thomas J [ORNL

    2014-01-01

    Cloud Computing environments rely heavily on system-level virtualization. This is due to the inherent benefits of virtualization including fault tolerance through checkpoint/restart (C/R) mechanisms. Because clouds are the abstraction of large data centers and large data centers have a higher potential for failure, it is imperative that a C/R mechanism for such an environment provide minimal latency as well as a small checkpoint file size. Recently, there has been much research into C/R with respect to virtual machines (VM) providing excellent solutions to reduce either checkpoint latency or checkpoint file size. However, these approaches do not provide both. This paper presents a method of checkpointing VMs by utilizing virtual machine introspection (VMI). Through the usage of VMI, we are able to determine which pages of memory within the guest are used or free and are better able to reduce the amount of pages written to disk during a checkpoint. We have validated this work by using various benchmarks to measure the latency along with the checkpoint size. With respect to checkpoint file size, our approach results in file sizes within 24% or less of the actual used memory within the guest. Additionally, the checkpoint latency of our approach is up to 52% faster than KVM s default method.

  14. The basic anaesthesia machine.

    Science.gov (United States)

    Gurudatt, Cl

    2013-09-01

    After WTG Morton's first public demonstration in 1846 of use of ether as an anaesthetic agent, for many years anaesthesiologists did not require a machine to deliver anaesthesia to the patients. After the introduction of oxygen and nitrous oxide in the form of compressed gases in cylinders, there was a necessity for mounting these cylinders on a metal frame. This stimulated many people to attempt to construct the anaesthesia machine. HEG Boyle in the year 1917 modified the Gwathmey's machine and this became popular as Boyle anaesthesia machine. Though a lot of changes have been made for the original Boyle machine still the basic structure remains the same. All the subsequent changes which have been brought are mainly to improve the safety of the patients. Knowing the details of the basic machine will make the trainee to understand the additional improvements. It is also important for every practicing anaesthesiologist to have a thorough knowledge of the basic anaesthesia machine for safe conduct of anaesthesia.

  15. The basic anaesthesia machine

    Directory of Open Access Journals (Sweden)

    C L Gurudatt

    2013-01-01

    Full Text Available After WTG Morton′s first public demonstration in 1846 of use of ether as an anaesthetic agent, for many years anaesthesiologists did not require a machine to deliver anaesthesia to the patients. After the introduction of oxygen and nitrous oxide in the form of compressed gases in cylinders, there was a necessity for mounting these cylinders on a metal frame. This stimulated many people to attempt to construct the anaesthesia machine. HEG Boyle in the year 1917 modified the Gwathmey′s machine and this became popular as Boyle anaesthesia machine. Though a lot of changes have been made for the original Boyle machine still the basic structure remains the same. All the subsequent changes which have been brought are mainly to improve the safety of the patients. Knowing the details of the basic machine will make the trainee to understand the additional improvements. It is also important for every practicing anaesthesiologist to have a thorough knowledge of the basic anaesthesia machine for safe conduct of anaesthesia.

  16. Part Machinability Evaluation System

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    In the early design period, estimation of the part or the whole product machinability is useful to consider the function and process request of the product at the same time so as to globally optimize the design decision. This paper presents a part machinability evaluation system, discusses the general restrictions of part machinability, and realizes the inspection of these restrictions with the relation between tool scan space and part model. During the system development, the expansibility and understandability were considered, and an independent restriction algorithm library and a general function library were set up. Additionally, the system has an interpreter and a knowledge manager.

  17. Fundamentals of machine design

    CERN Document Server

    Karaszewski, Waldemar

    2011-01-01

    A forum of researchers, educators and engineers involved in various aspects of Machine Design provided the inspiration for this collection of peer-reviewed papers. The resultant dissemination of the latest research results, and the exchange of views concerning the future research directions to be taken in this field will make the work of immense value to all those having an interest in the topics covered. The book reflects the cooperative efforts made in seeking out the best strategies for effecting improvements in the quality and the reliability of machines and machine parts and for extending

  18. Machine Tool Software

    Science.gov (United States)

    1988-01-01

    A NASA-developed software package has played a part in technical education of students who major in Mechanical Engineering Technology at William Rainey Harper College. Professor Hack has been using (APT) Automatically Programmed Tool Software since 1969 in his CAD/CAM Computer Aided Design and Manufacturing curriculum. Professor Hack teaches the use of APT programming languages for control of metal cutting machines. Machine tool instructions are geometry definitions written in APT Language to constitute a "part program." The part program is processed by the machine tool. CAD/CAM students go from writing a program to cutting steel in the course of a semester.

  19. Analysis of synchronous machines

    CERN Document Server

    Lipo, TA

    2012-01-01

    Analysis of Synchronous Machines, Second Edition is a thoroughly modern treatment of an old subject. Courses generally teach about synchronous machines by introducing the steady-state per phase equivalent circuit without a clear, thorough presentation of the source of this circuit representation, which is a crucial aspect. Taking a different approach, this book provides a deeper understanding of complex electromechanical drives. Focusing on the terminal rather than on the internal characteristics of machines, the book begins with the general concept of winding functions, describing the placeme

  20. Database machine performance

    Energy Technology Data Exchange (ETDEWEB)

    Cesarini, F.; Salza, S.

    1987-01-01

    This book is devoted to the important problem of database machine performance evaluation. The book presents several methodological proposals and case studies, that have been developed within an international project supported by the European Economic Community on Database Machine Evaluation Techniques and Tools in the Context of the Real Time Processing. The book gives an overall view of the modeling methodologies and the evaluation strategies that can be adopted to analyze the performance of the database machine. Moreover, it includes interesting case studies and an extensive bibliography.

  1. Virtual Machine Introspection

    Directory of Open Access Journals (Sweden)

    S C Rachana

    2014-06-01

    Full Text Available Cloud computing is an Internet-based computing solution which provides the resources in an effective manner. A very serious issue in cloud computing is security which is a major obstacle for the adoption of cloud. The most important threats of cloud computing are Multitenancy, Availability, Loss of control, Loss of Data, outside attacks, DOS attacks, malicious insiders, etc. Among many security issues in cloud, the Virtual Machine Security is one of the very serious issues. Thus, monitoring of virtual machine is essential. The paper proposes a Virtual Network Introspection [VMI] System to secure the Virtual machines from Distributed Denial of Service [DDOS] and Zombie attacks.

  2. Virtual Machine Introspection

    Directory of Open Access Journals (Sweden)

    S C Rachana

    2015-11-01

    Full Text Available Cloud computing is an Internet-based computing solution which provides the resources in an effective manner. A very serious issue in cloud computing is security which is a major obstacle for the adoption of cloud. The most important threats of cloud computing are Multitenancy, Availability, Loss of control, Loss of Data, outside attacks, DOS attacks, malicious insiders, etc. Among many security issues in cloud, the Virtual Machine Security is one of the very serious issues. Thus, monitoring of virtual machine is essential. The paper proposes a Virtual Network Introspection [VMI] System to secure the Virtual machines from Distributed Denial of Service [DDOS] and Zombie attacks.

  3. Machine Learning for Hackers

    CERN Document Server

    Conway, Drew

    2012-01-01

    If you're an experienced programmer interested in crunching data, this book will get you started with machine learning-a toolkit of algorithms that enables computers to train themselves to automate useful tasks. Authors Drew Conway and John Myles White help you understand machine learning and statistics tools through a series of hands-on case studies, instead of a traditional math-heavy presentation. Each chapter focuses on a specific problem in machine learning, such as classification, prediction, optimization, and recommendation. Using the R programming language, you'll learn how to analyz

  4. Towards robust deconvolution of low-dose perfusion CT: sparse perfusion deconvolution using online dictionary learning.

    Science.gov (United States)

    Fang, Ruogu; Chen, Tsuhan; Sanelli, Pina C

    2013-05-01

    Computed tomography perfusion (CTP) is an important functional imaging modality in the evaluation of cerebrovascular diseases, particularly in acute stroke and vasospasm. However, the post-processed parametric maps of blood flow tend to be noisy, especially in low-dose CTP, due to the noisy contrast enhancement profile and the oscillatory nature of the results generated by the current computational methods. In this paper, we propose a robust sparse perfusion deconvolution method (SPD) to estimate cerebral blood flow in CTP performed at low radiation dose. We first build a dictionary from high-dose perfusion maps using online dictionary learning and then perform deconvolution-based hemodynamic parameters estimation on the low-dose CTP data. Our method is validated on clinical data of patients with normal and pathological CBF maps. The results show that we achieve superior performance than existing methods, and potentially improve the differentiation between normal and ischemic tissue in the brain.

  5. A Review of the Latent and Manifest Benefits (LAMB) Scale

    Science.gov (United States)

    Muller, Juanita; Waters, Lea

    2012-01-01

    The latent and manifest benefits (LAMB) scale (Muller, Creed, Waters & Machin, 2005) was designed to measure the latent and manifest benefits of employment and provide a single scale to test Jahoda's (1981) and Fryer's (1986) theories of unemployment. Since its publication in 2005 there have been 13 studies that have used the scale with 5692…

  6. Some relations between quantum Turing machines and Turing machines

    CERN Document Server

    Sicard, A; Sicard, Andrés; Vélez, Mario

    1999-01-01

    For quantum Turing machines we present three elements: Its components, its time evolution operator and its local transition function. The components are related with deterministic Turing machines, the time evolution operator is related with reversible Turing machines and the local transition function is related with probabilistic and reversible Turing machines.

  7. Brain perfusion: computed tomography and magnetic resonance techniques.

    Science.gov (United States)

    Copen, William A; Lev, Michael H; Rapalino, Otto

    2016-01-01

    Cerebral perfusion imaging provides assessment of regional microvascular hemodynamics in the living brain, enabling in vivo measurement of a variety of different hemodynamic parameters. Perfusion imaging techniques that are used in the clinical setting usually rely upon X-ray computed tomography (CT) or magnetic resonance imaging (MRI). This chapter reviews CT- and MRI-based perfusion imaging techniques, with attention to image acquisition, clinically relevant aspects of image postprocessing, and fundamental differences between CT- and MRI-based techniques. Correlations with cerebrovascular physiology and potential clinical applications of perfusion imaging are reviewed, focusing upon the two major classes of neurologic disease in which perfusion imaging is most often performed: primary perfusion disorders (including ischemic stroke, transient ischemic attack, and reperfusion syndrome), and brain tumors. © 2016 Elsevier B.V. All rights reserved.

  8. Machining of hard-to-machine materials

    OpenAIRE

    2016-01-01

    Bakalářská práce se zabývá studiem obrábění těžkoobrobitelných materiálů. V první části jsou rozděleny těžkoobrobitelné materiály a následuje jejich analýza. V další části se práce zaměřuje na problematiku obrobitelnosti jednotlivých slitin. Závěrečná část práce je věnovaná experimentu, jeho statistickému zpracování a nakonec následnému vyhodnocení. This bachelor thesis studies the machining of hard-to-machine materials. The first part of the thesis considers hard-to-machine materials and ...

  9. Machine (bulk) harvest

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a summary of machine harvesting activities on Neal Smith National Wildlife Refuge between 1991 and 2008. Information is provided for each year about...

  10. Machine Vision Handbook

    CERN Document Server

    2012-01-01

    The automation of visual inspection is becoming more and more important in modern industry as a consistent, reliable means of judging the quality of raw materials and manufactured goods . The Machine Vision Handbook  equips the reader with the practical details required to engineer integrated mechanical-optical-electronic-software systems. Machine vision is first set in the context of basic information on light, natural vision, colour sensing and optics. The physical apparatus required for mechanized image capture – lenses, cameras, scanners and light sources – are discussed followed by detailed treatment of various image-processing methods including an introduction to the QT image processing system. QT is unique to this book, and provides an example of a practical machine vision system along with extensive libraries of useful commands, functions and images which can be implemented by the reader. The main text of the book is completed by studies of a wide variety of applications of machine vision in insp...

  11. Tests of Machine Intelligence

    CERN Document Server

    Legg, Shane

    2007-01-01

    Although the definition and measurement of intelligence is clearly of fundamental importance to the field of artificial intelligence, no general survey of definitions and tests of machine intelligence exists. Indeed few researchers are even aware of alternatives to the Turing test and its many derivatives. In this paper we fill this gap by providing a short survey of the many tests of machine intelligence that have been proposed.

  12. Metalworking and machining fluids

    Science.gov (United States)

    Erdemir, Ali; Sykora, Frank; Dorbeck, Mark

    2010-10-12

    Improved boron-based metal working and machining fluids. Boric acid and boron-based additives that, when mixed with certain carrier fluids, such as water, cellulose and/or cellulose derivatives, polyhydric alcohol, polyalkylene glycol, polyvinyl alcohol, starch, dextrin, in solid and/or solvated forms result in improved metalworking and machining of metallic work pieces. Fluids manufactured with boric acid or boron-based additives effectively reduce friction, prevent galling and severe wear problems on cutting and forming tools.

  13. mlpy: Machine Learning Python

    CERN Document Server

    Albanese, Davide; Merler, Stefano; Riccadonna, Samantha; Jurman, Giuseppe; Furlanello, Cesare

    2012-01-01

    mlpy is a Python Open Source Machine Learning library built on top of NumPy/SciPy and the GNU Scientific Libraries. mlpy provides a wide range of state-of-the-art machine learning methods for supervised and unsupervised problems and it is aimed at finding a reasonable compromise among modularity, maintainability, reproducibility, usability and efficiency. mlpy is multiplatform, it works with Python 2 and 3 and it is distributed under GPL3 at the website http://mlpy.fbk.eu.

  14. Human-machine interactions

    Science.gov (United States)

    Forsythe, J. Chris; Xavier, Patrick G.; Abbott, Robert G.; Brannon, Nathan G.; Bernard, Michael L.; Speed, Ann E.

    2009-04-28

    Digital technology utilizing a cognitive model based on human naturalistic decision-making processes, including pattern recognition and episodic memory, can reduce the dependency of human-machine interactions on the abilities of a human user and can enable a machine to more closely emulate human-like responses. Such a cognitive model can enable digital technology to use cognitive capacities fundamental to human-like communication and cooperation to interact with humans.

  15. Machine Learning with Distances

    Science.gov (United States)

    2015-02-16

    and demonstrated their usefulness in experiments. 1 Introduction The goal of machine learning is to find useful knowledge behind data. Many machine...212, 172]. However, direct divergence approximators still suffer from the curse of dimensionality. A possible cure for this problem is to combine them...obtain the global optimal solution or even a good local solution without any prior knowledge . For this reason, we decided to introduce the unit-norm

  16. mlpy: Machine Learning Python

    OpenAIRE

    Albanese, Davide; Visintainer, Roberto; Merler, Stefano; Riccadonna, Samantha; Jurman, Giuseppe; Furlanello, Cesare

    2012-01-01

    mlpy is a Python Open Source Machine Learning library built on top of NumPy/SciPy and the GNU Scientific Libraries. mlpy provides a wide range of state-of-the-art machine learning methods for supervised and unsupervised problems and it is aimed at finding a reasonable compromise among modularity, maintainability, reproducibility, usability and efficiency. mlpy is multiplatform, it works with Python 2 and 3 and it is distributed under GPL3 at the website http://mlpy.fbk.eu.

  17. Whole-brain dynamic CT angiography and perfusion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Orrison, W.W. [CHW Nevada Imaging Company, Nevada Imaging Centers, Spring Valley, Las Vegas, NV (United States); College of Osteopathic Medicine, Touro University Nevada, Henderson, NV (United States); Department of Health Physics and Diagnostic Sciences, University of Nevada Las Vegas, Las Vegas, NV (United States); Department of Medical Education, University of Nevada School of Medicine, Reno, NV (United States); Snyder, K.V.; Hopkins, L.N. [Department of Neurosurgery, Millard Fillmore Gates Circle Hospital, Buffalo, NY (United States); Roach, C.J. [School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV (United States); Advanced Medical Imaging and Genetics (Amigenics), Las Vegas, NV (United States); Ringdahl, E.N. [Department of Psychology, University of Nevada Las Vegas, Las Vegas, NV (United States); Nazir, R. [Shifa International Hospital, Islamabad (Pakistan); Hanson, E.H., E-mail: eric.hanson@amigenics.co [College of Osteopathic Medicine, Touro University Nevada, Henderson, NV (United States); Department of Health Physics and Diagnostic Sciences, University of Nevada Las Vegas, Las Vegas, NV (United States); Advanced Medical Imaging and Genetics (Amigenics), Las Vegas, NV (United States)

    2011-06-15

    The availability of whole brain computed tomography (CT) perfusion has expanded the opportunities for analysing the haemodynamic parameters associated with varied neurological conditions. Examples demonstrating the clinical utility of whole-brain CT perfusion imaging in selected acute and chronic ischaemic arterial neurovascular conditions are presented. Whole-brain CT perfusion enables the detection and focused haemodynamic analyses of acute and chronic arterial conditions in the central nervous system without the limitation of partial anatomical coverage of the brain.

  18. Scintigraphic control of blood vessels in regional perfusion with cytostatics

    Energy Technology Data Exchange (ETDEWEB)

    Blazek, J.; Broz, J. (Krajska Nemocnice s Poliklinikou, Ceske Budejovice (Czechoslovakia))

    1982-12-01

    After administration of sup(99m)Tc-MAA or sup(113m)In-MAA into the perfusion system during regional perfusion therapy with cytostatics of malignomas in the maxillo-facial area it is possible to obtain by subsequent scintigraphic visualization of the distribution of radioactivity an accurate topographic picture of the perfusion in the appropriate area. The method is free from complications and there are no contraindications. The paper is supplemented by scintigrams.

  19. Metabolic response of perfused livers to various oxygenation conditions.

    Science.gov (United States)

    Orman, Mehmet A; Ierapetritou, Marianthi G; Androulakis, Ioannis P; Berthiaume, Francois

    2011-12-01

    Isolated liver perfusion systems have been used to characterize intrinsic metabolic changes in liver as a result of various perturbations, including systemic injury, hepatotoxin exposure, and warm ischemia. Most of these studies were done using hyperoxic conditions (95% O(2)) but without the use of oxygen carriers in the perfusate. Prior literature data do not clearly establish the impact of oxygenation, and in particular that of adding oxygen carriers to the perfusate, on the metabolic functions of the liver. Therefore, herein the effects of oxygen delivery in the perfusion system on liver metabolism were investigated by comparing three modes of oxygenation. Rat livers were perfused via the portal and hepatic veins at a constant flow rate of 3 mL/min/g liver in a recirculating perfusion system. In the first group, the perfusate was equilibrated in a membrane oxygenator with room air (21% O(2)) before entering the liver. In the second group, the perfusate was equilibrated with a 95% O(2)/5% CO(2) gas mixture. In the third group, the perfusate was supplemented with washed bovine red blood cells (RBCs) at 10% hematocrit and also equilibrated with the 95% O(2)/5% CO(2) gas mixture. Oxygen and CO(2) gradients across the liver were measured periodically with a blood gas analyzer. The rate of change in the concentration of major metabolites in the perfusate was measured over time. Net extracellular fluxes were calculated from these measurements and applied to a stoichiometric-based optimization problem to determine the intracellular fluxes and active pathways in the perfused livers. Livers perfused with RBCs consumed oxygen at twice the rate observed using hyperoxic (95% O(2)) perfusate without RBCs, and also produced more urea and ketone bodies. At the flow rate used, the oxygen supply in perfusate without RBCs was just sufficient to meet the average oxygen demand of the liver but would be insufficient if it increased above baseline, as is often the case in response to

  20. Lung perfusion CT: The differentiation of cavitary mass

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Han [Department of Radiology, Yonsei University Wonju College of Medicine, 162 Ilsan-dong, Wonju (Korea, Republic of); Kwon, Woocheol [Department of Radiology, Yonsei University Wonju College of Medicine, 162 Ilsan-dong, Wonju (Korea, Republic of)], E-mail: wckwon@yonsei.ac.kr; Kim, Myung Soon; Kim, Young Ju; Lee, Myeong Sub [Department of Radiology, Yonsei University Wonju College of Medicine, 162 Ilsan-dong, Wonju (Korea, Republic of); Yong, Suk Joong [Division of Pulmonology, Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju (Korea, Republic of); Jung, Soon-Hee [Department of Pathology, Yonsei University Wonju College of Medicine, Wonju (Korea, Republic of); Chang, Sei-Jin [Department of Preventive Medicine, Yonsei University Wonju College of Medicine, Wonju (Korea, Republic of); Sung, Ki Joon [Department of Radiology, Yonsei University Wonju College of Medicine, 162 Ilsan-dong, Wonju (Korea, Republic of)

    2010-01-15

    Purpose: To assess the findings of perfusion maps and to evaluate the usefulness of perfusion computed tomography (CT) in the differentiation of cavitary mass. Materials and methods: Fifty-three patients with cavitary lung masses were analyzed. Dynamic chest CT was performed after contrast injection. The volume map, washout map, peak map, and time-to-peak (TTP) map were reformatted using Interactive Data Language (IDL). The perfusion patterns were classified into three scoring groups, and these scorings were repeated after 2-week intervals. Diagnostic confidence levels were assigned by consensus. The kappa statistics was used to determine intraobserver agreement, and Fisher's exact test was used to analyze statistical differences in perfusion scores. Receiver operating characteristic (ROC) analysis was performed to evaluate the usefulness of the perfusion maps. Results: Perfusion maps were reformatted pixel-by-pixel from the time-to-density curve analyses. Pyogenic cavities showed weak washout and slow TTP (69.6%). Conversely, malignant cavities showed strong washout (73.3%). Tuberculous cavities showed low perfusions in the volume and peak maps (66.7%). Intraobserver agreement was excellent. The performance of the combination of CT and perfusion maps was better than that of CT alone. Conclusion: Lung perfusion CT could be a promising and feasible method for differentiation of cavitary mass.

  1. CT perfusion of the liver: principles and applications in oncology.

    Science.gov (United States)

    Kim, Se Hyung; Kamaya, Aya; Willmann, Jürgen K

    2014-08-01

    With the introduction of molecularly targeted chemotherapeutics, there is an increasing need for defining new response criteria for therapeutic success because use of morphologic imaging alone may not fully assess tumor response. Computed tomographic (CT) perfusion imaging of the liver provides functional information about the microcirculation of normal parenchyma and focal liver lesions and is a promising technique for assessing the efficacy of various anticancer treatments. CT perfusion also shows promising results for diagnosing primary or metastatic tumors, for predicting early response to anticancer treatments, and for monitoring tumor recurrence after therapy. Many of the limitations of early CT perfusion studies performed in the liver, such as limited coverage, motion artifacts, and high radiation dose of CT, are being addressed by recent technical advances. These include a wide area detector with or without volumetric spiral or shuttle modes, motion correction algorithms, and new CT reconstruction technologies such as iterative algorithms. Although several issues related to perfusion imaging-such as paucity of large multicenter trials, limited accessibility of perfusion software, and lack of standardization in methods-remain unsolved, CT perfusion has now reached technical maturity, allowing for its use in assessing tumor vascularity in larger-scale prospective clinical trials. In this review, basic principles, current acquisition protocols, and pharmacokinetic models used for CT perfusion imaging of the liver are described. Various oncologic applications of CT perfusion of the liver are discussed and current challenges, as well as possible solutions, for CT perfusion are presented.

  2. Effect of Defocused CO2 Laser on Equine Tissue Perfusion

    Directory of Open Access Journals (Sweden)

    Bergh A

    2006-03-01

    Full Text Available Treatment with defocused CO2 laser can have a therapeutic effect on equine injuries, but the mechanisms involved are unclear. A recent study has shown that laser causes an increase in equine superficial tissue temperature, which may result in an increase in blood perfusion and a stimulating effect on tissue regeneration. However, no studies have described the effects on equine tissue perfusion. The aim of the present study was to investigate the effect of defocused CO2 laser on blood perfusion and to correlate it with temperature in skin and underlying muscle in anaesthetized horses. Differences between clipped and unclipped haircoat were also assessed. Eight horses and two controls received CO2 laser treatment (91 J/cm2 in a randomised order, on a clipped and unclipped area of the hamstring muscles, respectively. The significant increase in clipped skin perfusion and temperature was on average 146.3 ± 33.4 perfusion units (334% and 5.5 ± 1.5°C, respectively. The significant increase in perfusion and temperature in unclipped skin were 80.6 ± 20.4 perfusion units (264% and 4.8 ± 1.4°C. No significant changes were seen in muscle perfusion or temperature. In conclusion, treatment with defocused CO2 laser causes a significant increase in skin perfusion, which is correlated to an increase in skin temperature.

  3. Myocardial Perfusion Spect Imaging in Dextrocardia: A Case Report

    Directory of Open Access Journals (Sweden)

    Semra Özdemir

    2013-08-01

    Full Text Available The myocardial perfusion scintigraphy acquisition and analysis present some technical differences in the rare dextrocardia cases. Here we report a case of a 38 year-old woman with dextrocardia who had been applied myocardial perfusion scintigraphy. Presented case showed that the thoracic and abdominal organs had a mirror image with situs inversus totalis type dextrocardia. The incidence of coronary heart disease and life span of people with situs inversus totalis are the same as the normal population. So we may apply myocardial perfusion scintigraphy to this patient group. The current case is presented in order to remind the special applications of myocardial perfusion SPECT imaging in patients with dextrocardia.

  4. Radionuclide Tracers for Myocardial Perfusion Imaging and Blood Flow Quantification.

    Science.gov (United States)

    deKemp, Robert A; Renaud, Jennifer M; Klein, Ran; Beanlands, Rob S B

    2016-02-01

    Myocardial perfusion imaging is performed most commonly using Tc-99m-sestamibi or tetrofosmin SPECT as well as Rb-82-rubidium or N-13-ammonia PET. Diseased-to-normal tissue contrast is determined by the tracer retention fraction, which decreases nonlinearly with flow. Reduced tissue perfusion results in reduced tracer retention, but the severity of perfusion defects is typically underestimated by 20% to 40%. Compared to SPECT, retention of the PET tracers is more linearly related to flow, and therefore, the perfusion defects are measured more accurately using N-13-ammonia or Rb-82.

  5. Can preoperative myocardial perfusion scintigraphy predict changes in left ventricular perfusion and function after coronary artery bypass graft surgery?

    DEFF Research Database (Denmark)

    Eckardt, Rozy; Kjeldsen, Bo Juel; Johansen, Allan;

    2012-01-01

    OBJECTIVESWe wanted to evaluate whether preoperative myocardial perfusion scintigraphy (MPS) could predict changes in cardiac symptoms and postoperative myocardial perfusion and left ventricular function after coronary artery bypass grafting (CABG).METHODSNinety-two patients with stable angina......%. Before CABG, one patient had normal perfusion; in the rest of them the defects were classified as follows: reversible (60%), partly reversible (27%) and irreversible (12%). Following CABG, 33% had normal perfusion; in the rest the defects were reversible in 29%, partly reversible in 12% and irreversible...... in 26%. Left ventricular ejection fraction (LVEF), which was normal before operation in 45%, improved in 40% of all patients. The increase in LVEF was not related to the preoperative pattern of perfusion defects. Of 30 patients with normalized perfusion after CABG, 29 (97%) had reversible defects...

  6. Perfusion vector - a new method to quantify myocardial perfusion scintigraphy images: a simulation study with validation in patients

    DEFF Research Database (Denmark)

    Minarik, David; Senneby, Martin; Wollmer, Per

    2015-01-01

    Background The interpretation of myocardial perfusion scintigraphy (MPS) largely relies on visual assessment by the physician of the localization and extent of a perfusion defect. The aim of this study was to introduce the concept of the perfusion vector as a new objective quantitative method...... for further assisting the visual interpretation and to test the concept using simulated MPS images as well as patients. Methods The perfusion vector is based on calculating the difference between the anatomical centroid and the perfusion center of gravity of the left ventricle. Simulated MPS images were.......001) but not for patients with infarction. The correlation between the defect size and stress vector magnitude was also found to be significant (p concept of the perfusion vector introduced in this study is shown to have potential in assisting the visual interpretation in MPS studies. Further...

  7. EVALUATION OF MACHINE TOOL QUALITY

    Directory of Open Access Journals (Sweden)

    Ivan Kuric

    2011-12-01

    Full Text Available Paper deals with aspects of quality and accuracy of machine tools. As the accuracy of machine tools has key factor for product quality, it is important to know the methods for evaluation of quality and accuracy of machine tools. Several aspects of diagnostics of machine tools are described, such as aspects of reliability.

  8. An HTS machine laboratory prototype

    DEFF Research Database (Denmark)

    Mijatovic, Nenad; Jensen, Bogi Bech; Træholt, Chresten

    2012-01-01

    This paper describes Superwind HTS machine laboratory setup which is a small scale HTS machine designed and build as a part of the efforts to identify and tackle some of the challenges the HTS machine design may face. One of the challenges of HTS machines is a Torque Transfer Element (TTE) which...

  9. Machining of fiber reinforced composites

    Science.gov (United States)

    Komanduri, Ranga; Zhang, Bi; Vissa, Chandra M.

    Factors involved in machining of fiber-reinforced composites are reviewed. Consideration is given to properties of composites reinforced with boron filaments, glass fibers, aramid fibers, carbon fibers, and silicon carbide fibers and to polymer (organic) matrix composites, metal matrix composites, and ceramic matrix composites, as well as to the processes used in conventional machining of boron-titanium composites and of composites reinforced by each of these fibers. Particular attention is given to the methods of nonconventional machining, such as laser machining, water jet cutting, electrical discharge machining, and ultrasonic assisted machining. Also discussed are safety precautions which must be taken during machining of fiber-containing composites.

  10. Phthalate monoesters in perfusate from a dual placenta perfusion system, the placenta tissue and umbilical cord blood

    DEFF Research Database (Denmark)

    Mose, Tina; Mortensen, Gerda K; Hedegaard, Morten;

    2006-01-01

    Fetal exposure to phthalates may be associated with adverse reproductive effects, including cryptorchidism and decreased semen quality. Information about human placental transfer is needed to qualify the hypotheses. A dual recirculating placenta perfusion system to monitor concentrations of eight...... phthalate monoesters in fetal and maternal perfusates was established. In addition to perfusate background measures of phthalate monoesters, the concentrations in umbilical cord plasma and placenta tissue were measured. Monomethyl phthalate (mMP), monoethyl phthalate (mEP), monobutyl phthalate (m...

  11. Machining of Metal Matrix Composites

    CERN Document Server

    2012-01-01

    Machining of Metal Matrix Composites provides the fundamentals and recent advances in the study of machining of metal matrix composites (MMCs). Each chapter is written by an international expert in this important field of research. Machining of Metal Matrix Composites gives the reader information on machining of MMCs with a special emphasis on aluminium matrix composites. Chapter 1 provides the mechanics and modelling of chip formation for traditional machining processes. Chapter 2 is dedicated to surface integrity when machining MMCs. Chapter 3 describes the machinability aspects of MMCs. Chapter 4 contains information on traditional machining processes and Chapter 5 is dedicated to the grinding of MMCs. Chapter 6 describes the dry cutting of MMCs with SiC particulate reinforcement. Finally, Chapter 7 is dedicated to computational methods and optimization in the machining of MMCs. Machining of Metal Matrix Composites can serve as a useful reference for academics, manufacturing and materials researchers, manu...

  12. Evaluation of cerebral hemodynamics with perfusion CT

    Energy Technology Data Exchange (ETDEWEB)

    Araki, Yuzo; Furuichi, Masahiro; Nokura, Hiroaki [Inuyama Central Hospital, Aichi (Japan); Sakai, Noboru [Gifu Univ. (Japan). School of Medicine

    2002-07-01

    We report on the evaluation of cerebral ischemic lesions with perfusion CT. Cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) of 52 patients mostly with ischemic cerebrovascular disease were analysed using the box-modulation transfer function method with 30 ml of contrast medium intravenously injected at 5 ml/sec. CBF, CBV and MTT of the middle cerebral artery (MCA) territory were 43.5{+-}4.6 ml/100 g/min, 1.9{+-}0.2 ml/100 g and 2.9{+-}0.6 seconds at the unaffected side, and 37.7{+-}7.3 ml/100 g /min, 2.1{+-}0.3 ml/100 g, 3.7{+-}0.9 seconds at the lesion side with stenosis or occlusion in the main MCA trunks or internal carotid artery, respectively. A statistically significant difference was shown in CBF and MTT values. Furthermore, there was a close correlation in CBF values of MCA territories between Xe-CT and perfusion CT (r=0.645, n=76, p<0.0001). MTT showed a positive correlation with CBV in those subjects when MTT was below 4.1 seconds (r=0.526, p<0.0001, n=83). MTT also showed a negative correlation with CBF in those patients when MTT indicated more than 4.1 seconds (r=0.818, p<0.001, n=21). These results suggest that the progression of cerebral ischemia may be classified in 4 stages using perfusion CT. The stages are as follows: stage 0; normal CBF without prolonged MTT and increased CBV, stage 1; relatively increased CBV, stage 2; significantly prolonged MTT, and stage 3; significantly deceased CBF with prolonged MTT. (author)

  13. Pseudoketogenesis in the perfused rat heart

    Energy Technology Data Exchange (ETDEWEB)

    Fink, G.; Desrochers, S.; Des Rosiers, C.; Garneau, M.; David, F.; Daloze, T.; Landau, B.R.; Brunengraber, H.

    1988-12-05

    Ketogenesis is usually measured in vivo by dilution of tracers of (3R)-hydroxybutyrate or acetoacetate. We show that, in perfused working rat hearts, the specific activities of (3R)-hydroxybutyrate and acetoacetate are diluted by isotopic exchanges in the absence of net ketogenesis. We call this process pseudoketogenesis. When hearts are perfused with buffer containing 2.3 mM of (4-3H)- plus (3-14C)acetoacetate, the specific activities of (4-3H) and (3-14C)acetoacetate decrease while C-1 of acetoacetate becomes progressively labeled with 14C. This is explained by the reversibility of reactions catalyzed by mitochondrial 3-oxoacid-CoA transferase and acetoacetyl-CoA thiolase. After activation of labeled acetoacetate, the specific activity of acetoacetyl-CoA is diluted by unlabeled acetoacetyl-CoA derived from endogenous fatty acids or glucose. Acetoacetyl-CoA thiolase partially exchanges 14C between C-1 and C-3 of acetoacetyl-CoA. Finally, 3-oxoacid-CoA transferase liberates weakly labeled acetoacetate which dilutes the specific activity of extracellular acetoacetate. An isotopic exchange in the reverse direction is observed when hearts are perfused with unlabeled acetoacetate plus (1-14C)-, (13-14C)-, or (15-14C)palmitate; here also, acetoacetate becomes labeled on C-1 and C-3. Computations of specific activities of (3R)-hydroxybutyrate, acetoacetate, and acetyl-CoA yield minimal rates of pseudoketogenesis ranging from 19 to 32% of the net uptake of (3R)-hydroxybutyrate plus acetoacetate by the heart.

  14. Demonstration of cerebral perfusion abnormalities in moyamoya disease using susceptibility perfusion- and diffusion-weighted MRI

    Energy Technology Data Exchange (ETDEWEB)

    Adams, W.M.; Laitt, R.D. [Department of Neuroradiology, Central Manchester Healthcare Trust, Oxford Road, Manchester M13 9WL (United Kingdom); Li, K.L.; Jackson, A. [Department of Diagnostic Radiology, University of Manchester, Manchester M13 9PT (United Kingdom); Sherrington, C.R.; Talbot, P. [Department of Neurology, Central Manchester Healthcare Trust, Oxford Road, Manchester M13 9WL (United Kingdom)

    1999-02-01

    We describe the use of diffusion-weighted imaging and perfusion MRI using a contrast-medium bolus in the preoperative investigation for young man presenting with a cerebral ischaemic episode as a manifestation of moyamoya disease. (orig.) With 6 figs., 21 refs.

  15. Non-conventional electrical machines

    CERN Document Server

    Rezzoug, Abderrezak

    2013-01-01

    The developments of electrical machines are due to the convergence of material progress, improved calculation tools, and new feeding sources. Among the many recent machines, the authors have chosen, in this first book, to relate the progress in slow speed machines, high speed machines, and superconducting machines. The first part of the book is dedicated to materials and an overview of magnetism, mechanic, and heat transfer.

  16. Multi-delay arterial spin labeling perfusion MRI in moyamoya disease-comparison with CT perfusion imaging

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Rui [Chinese Academy of Sciences, State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Beijing (China); University of Chinese Academy of Sciences, Graduate School, Beijing (China); UCLA-Beijing Joint Center for Advanced Brain Imaging, Beijing (China); UCLA-Beijing Joint Center for Advanced Brain Imaging, Los Angeles, CA (United States); Yu, Songlin [Capital Medical University, Department of Neurosurgery, Beijing Tiantan Hospital, Beijing (China); University of California Los Angeles, Department of Neurology, Los Angeles (United States); Alger, Jeffry R.; Wang, Danny J.J. [University of California Los Angeles, Department of Neurology, Los Angeles (United States); UCLA-Beijing Joint Center for Advanced Brain Imaging, Beijing (China); UCLA-Beijing Joint Center for Advanced Brain Imaging, Los Angeles, CA (United States); Zuo, Zhentao; Wang, Bo [Chinese Academy of Sciences, State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Beijing (China); Chen, Juan [Beijing Hospital, Department of Radiology, Beijing (China); Wang, Rong; Zhao, Jizong [Capital Medical University, Department of Neurosurgery, Beijing Tiantan Hospital, Beijing (China); An, Jing [Siemens Shenzhen Magnetic Resonance Ltd, Shenzhen (China); Xue, Rong [Chinese Academy of Sciences, State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Beijing (China); UCLA-Beijing Joint Center for Advanced Brain Imaging, Beijing (China); UCLA-Beijing Joint Center for Advanced Brain Imaging, Los Angeles, CA (United States)

    2014-05-15

    To present a multi-delay pseudo-continuous ASL (pCASL) protocol that offers simultaneous measurements of cerebral blood flow (CBF) and arterial transit time (ATT), and to study correlations between multi-delay pCASL and CT perfusion in moyamoya disease. A 4 post-labeling delay (PLD) pCASL protocol was applied on 17 patients with moyamoya disease who also underwent CT perfusion imaging. ATT was estimated using the multi-delay protocol and included in the calculation of CBF. ASL and CT perfusion images were rated for lesion severity/conspicuity. Pearson correlation coefficients were calculated across voxels between the two modalities in grey and white matter of each subject respectively and between normalized mean values of ASL and CT perfusion measures in major vascular territories. Significant associations between ASL and CT perfusion were detected using subjective ratings, voxel-wise analysis in grey and white matter and region of interest (ROI)-based analysis of normalized mean perfusion. The correlation between ASL CBF and CT perfusion was improved using the multi-delay pCASL protocol compared to CBF acquired at a single PLD of 2 s (P < 0.05). There is a correlation between perfusion data from ASL and CT perfusion imaging in patients with moyamoya disease. Multi-delay ASL can improve CBF quantification, which could be a prognostic imaging biomarker in patients with moyamoya disease. (orig.)

  17. Dynamic perfusion CT in brain tumors.

    Science.gov (United States)

    Yeung, Timothy Pok Chi; Bauman, Glenn; Yartsev, Slav; Fainardi, Enrico; Macdonald, David; Lee, Ting-Yim

    2015-12-01

    Dynamic perfusion CT (PCT) is an imaging technique for assessing the vascular supply and hemodynamics of brain tumors by measuring blood flow, blood volume, and permeability-surface area product. These PCT parameters provide information complementary to histopathologic assessments and have been used for grading brain tumors, distinguishing high-grade gliomas from other brain lesions, differentiating true progression from post-treatment effects, and predicting prognosis after treatments. In this review, the basic principles of PCT are described, and applications of PCT of brain tumors are discussed. The advantages and current challenges, along with possible solutions, of PCT are presented.

  18. Distribution of lung blood on modified bilateral Glenn shunt evaluated by Tc-99m-MAA lung perfusion scintigraphy: A retrospective study.

    Science.gov (United States)

    Si, Biao; Luan, Zhao-Sheng; Wang, Tong-Jian; Ning, Yan-Song; Li, Na; Zhu, Meng; Liu, Zhong-Min; Ding, Guang-Hong; Qiao, Bin

    2016-09-01

    The aim of the present study was to determine the distribution of lung blood in a modified bilateral Glenn procedure designed in our institute with lung perfusion scintigraphy. Sixteen consecutive patients who underwent modified bilateral Glenn operation from 2011 to 2014 were enrolled in the study. The control group consisted of 7 patients who underwent bidirectional Glenn shunt. Radionuclide lung perfusion scintigraphy was performed using Tc-99m-macro aggregated albumin (MAA) in all patients. For the patients in modified bilateral Glenn group, the time at which the radioactivity accumulation peaked did not differ significantly between the right and left lung field (t = 0.608, P = 0.554). The incidence of perfusion abnormality in each lung lobe also did not differ significantly (P = 0.426 by Fisher exact test). The radioactive counts were higher in the right lung than in the left lung, but the difference was not statistically significant (t = 1.502, P = 0.157). Radioactive perfusion in the lower lung field was significantly greater than that in the upper field (t = 4.368, P lung to that in left lung was significantly lower in the modified bilateral Glenn group (t = 3.686, P = 0.002). Lung perfusion scintigraphy confirmed the benefit of the modified bilateral Glenn shunt with regard to more balanced blood perfusion in both lungs.

  19. Moderate Versus Deep Hypothermia With Unilateral Selective Antegrade Cerebral Perfusion for Acute Type A Dissection.

    Science.gov (United States)

    Leshnower, Bradley G; Thourani, Vinod H; Halkos, Michael E; Sarin, Eric L; Keeling, William B; Lamias, Mark J; Guyton, Robert A; Chen, Edward P

    2015-11-01

    Despite improved results with surgical therapy for acute type A aortic dissection (ATAAD), there remains a lack of consensus regarding the optimal method of cerebral protection and circulation management during ATAAD. The purpose of this study is to determine whether in the setting of antegrade cerebral perfusion, moderate hypothermic circulatory arrest (MHCA) provides equivalent cerebral and visceral protection as deep hypothermic circulatory arrest (DHCA) for patients undergoing emergent ATAAD repair. A review of the Emory aortic surgery database from 2004 to 2014 identified 288 patients who underwent ATAAD with right axillary artery cannulation, unilateral selective antegrade cerebral perfusion (uSACP), and hypothermic circulatory arrest (HCA). In all, 88 patients underwent HCA at 24 °C or lower (DHCA), and 206 patients underwent HCA at more than 24 °C (MHCA). Major adverse outcomes of death, stroke, temporary neurologic dysfunction, and dialysis-dependent renal failure were examined. The groups were well matched for age and major comorbidities. The DHCA patients underwent HCA at lower temperatures (DHCA 21.6 ± 3.1 °C vs MHCA 27.4 ± 1.6 °C, p 0.05). Moderate HCA with uSACP is an effective circulation management strategy that provides excellent cerebral and visceral protection during emergent ATAAD repair. In the setting of antegrade cerebral perfusion, deep hypothermia does not provide any additional benefit. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  20. A Device for Long-Term Perfusion, Imaging, and Electrical Interfacing of Brain Tissue In vitro

    Science.gov (United States)

    Killian, Nathaniel J.; Vernekar, Varadraj N.; Potter, Steve M.; Vukasinovic, Jelena

    2016-01-01

    Distributed microelectrode array (MEA) recordings from consistent, viable, ≥500 μm thick tissue preparations over time periods from days to weeks may aid in studying a wide range of problems in neurobiology that require in vivo-like organotypic morphology. Existing tools for electrically interfacing with organotypic slices do not address necrosis that inevitably occurs within thick slices with limited diffusion of nutrients and gas, and limited removal of waste. We developed an integrated device that enables long-term maintenance of thick, functionally active, brain tissue models using interstitial perfusion and distributed recordings from thick sections of explanted tissue on a perforated multi-electrode array. This novel device allows for automated culturing, in situ imaging, and extracellular multi-electrode interfacing with brain slices, 3-D cell cultures, and potentially other tissue culture models. The device is economical, easy to assemble, and integrable with standard electrophysiology tools. We found that convective perfusion through the culture thickness provided a functional benefit to the preparations as firing rates were generally higher in perfused cultures compared to their respective unperfused controls. This work is a step toward the development of integrated tools for days-long experiments with more consistent, healthier, thicker, and functionally more active tissue cultures with built-in distributed electrophysiological recording and stimulation functionality. The results may be useful for the study of normal processes, pathological conditions, and drug screening strategies currently hindered by the limitations of acute (a few hours long) brain slice preparations. PMID:27065793

  1. CT perfusion technique for assessment of early kidney allograft dysfunction: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Helck, A.; Notohamiprodjo, M.; Schoen, F.; Nikolaou, K.; Clevert, D.A.; Reiser, M.; Becker, C. [Ludwig-Maximilians-University of Munich, Department of Clinical Radiology, University Hospitals Grosshadern, Munich (Germany); Wessely, M.; Schoenermarck, U.; Fischereder, M. [Ludwig-Maximilians-University of Munich, Department of Internal Medicine IV, Nephrology, University Hospitals Grosshadern, Munich (Germany); Klotz, E. [Siemens Healthcare, Computed Tomography, Forchheim (Germany)

    2013-09-15

    To assess the benefit of quantitative computed tomography (CT) perfusion for differentiating acute tubular necrosis (ATN) and acute rejection (AR) in kidney allografts. Twenty-two patients with acute kidney allograft dysfunction caused by either AR (n = 6) or ATN (n = 16) were retrospectively included in the study. All patients initially underwent a multiphase CT angiography (CTA) protocol (12 phases, one phase every 3.5 s) covering the whole graft to exclude acute postoperative complications. Multiphase CT dataset and dedicated software were used to calculate renal blood flow. Renal biopsy or clinical course of disease served as the standard of reference. Mean effective radiation dose and mean amount of contrast media were calculated. Renal blood flow values were significantly lower (P = 0.001) in allografts undergoing AR (48.3 {+-} 21 ml/100 ml/min) compared with those with ATN (77.5 {+-} 21 ml/100 ml/min). No significant difference (P = 0.71) was observed regarding creatinine level with 5.65 {+-} 3.1 mg/dl in AR and 5.3 {+-} 1.9 mg/dl in ATN. The mean effective radiation dose of the CT perfusion protocol was 13.6 {+-} 5.2 mSv; the mean amount of contrast media applied was 34.5 {+-} 5.1 ml. All examinations were performed without complications. CT perfusion of kidney allografts may help to differentiate between ATN and rejection. (orig.)

  2. Bayesian optimization of perfusion and transit time estimation in PASL-MRI.

    Science.gov (United States)

    Santos, Nuno; Sanches, João; Figueiredo, Patrícia

    2010-01-01

    Pulsed Arterial Spin Labeling (PASL) techniques potentially allow the absolute, non-invasive quantification of brain perfusion and arterial transit time. This can be achieved by fitting a kinetic model to the data acquired at a number of inversion time points (TI). The intrinsically low SNR of PASL data, together with the uncertainty in the model parameters, can hinder the estimation of the parameters of interest. Here, a two-compartment kinetic model is used to estimate perfusion and transit time, based on a Maximum a Posteriori (MAP) criterion. A priori information concerning the physiological variation of the multiple model parameters is used to guide the solution. Monte Carlo simulations are performed to compare the accuracy of our proposed Bayesian estimation method with a conventional Least Squares (LS) approach, using four different sets of TI points. Each set is obtained either with a uniform distribution or an optimal sampling strategy designed based on the same MAP criterion. We show that the estimation errors are minimized when our proposed Bayesian estimation method is employed in combination with an optimal set of sampling points. In conclusion, our results indicate that PASL perfusion and transit time measurements would benefit from a Bayesian approach for the optimization of both the sampling strategy and the estimation algorithm, whereby prior information on the parameters is used.

  3. Perfusion deficits and functional connectivity alterations in patients with post-traumatic stress disorder

    Science.gov (United States)

    Liu, Yang; Li, Baojuan; Zhang, Xi; Zhang, Linchuan; Li, Liang; Lu, Hongbing

    2016-03-01

    To explore the alteration in cerebral blood flow (CBF) and functional connectivity between survivors with recent onset post-traumatic stress disorder (PTSD) and without PTSD, survived from the same coal mine flood disaster. In this study, a processing pipeline using arterial spin labeling (ASL) sequence was proposed. Considering low spatial resolution of ASL sequence, a linear regression method was firstly used to correct the partial volume (PV) effect for better CBF estimation. Then the alterations of CBF between two groups were analyzed using both uncorrected and PV-corrected CBF maps. Based on altered CBF regions detected from the CBF analysis as seed regions, the functional connectivity abnormities in PTSD patients was investigated. The CBF analysis using PV-corrected maps indicates CBF deficits in the bilateral frontal lobe, right superior frontal gyrus and right corpus callosum of PTSD patients, while only right corpus callosum was identified in uncorrected CBF analysis. Furthermore, the regional CBF of the right superior frontal gyrus exhibits significantly negative correlation with the symptom severity in PTSD patients. The resting-state functional connectivity indicates increased connectivity between left frontal lobe and right parietal lobe. These results indicate that PV-corrected CBF exhibits more subtle perfusion changes and may benefit further perfusion and connectivity analysis. The symptom-specific perfusion deficits and aberrant connectivity in above memory-related regions may be putative biomarkers for recent onset PTSD induced by a single prolonged trauma exposure and help predict the severity of PTSD.

  4. Enhanced Visualization of Optimal Cerebral Perfusion Pressure Over Time to Support Clinical Decision Making

    NARCIS (Netherlands)

    Aries, Marcel J H; Wesselink, Robin; Elting, Jan Willem J; Donnelly, Joseph; Czosnyka, Marek; Ercole, Ari; Maurits, Natasha M; Smielewski, Peter

    2016-01-01

    OBJECTIVE: Cerebrovascular reactivity can provide a continuously updated individualized target for management of cerebral perfusion pressure, termed optimal cerebral perfusion pressure. The objective of this project was to find a way of improving the optimal cerebral perfusion pressure methodology b

  5. Machinability evaluation of machinable ceramics with fuzzy theory

    Institute of Scientific and Technical Information of China (English)

    YU Ai-bing; ZHONG Li-jun; TAN Ye-fa

    2005-01-01

    The property parameters and machining output parameters were selected for machinability evaluation of machinable ceramics. Based on fuzzy evaluation theory, two-stage fuzzy evaluation approach was applied to consider these parameters. Two-stage fuzzy comprehensive evaluation model was proposed to evaluate machinability of machinable ceramic materials. Ce-ZrO2/CePO4 composites were fabricated and machined for evaluation of machinable ceramics. Material removal rates and specific normal grinding forces were measured. The parameters concerned with machinability were selected as alternative set. Five grades were chosen for the machinability evaluation of machnable ceramics. Machinability grades of machinable ceramics were determined through fuzzy operation. Ductile marks are observed on Ce-ZrO2/CePO4 machined surface. Five prepared Ce-ZrO2/CePO4 composites are classified as three machinability grades according to the fuzzy comprehensive evaluation results. The machinability grades of Ce-ZrO2/CePO4 composites are concerned with CePO4 content.

  6. MACHINE MOTION EQUATIONS

    Directory of Open Access Journals (Sweden)

    Florian Ion Tiberiu Petrescu

    2015-09-01

    Full Text Available This paper presents the dynamic, original, machine motion equations. The equation of motion of the machine that generates angular speed of the shaft (which varies with position and rotation speed is deduced by conservation kinetic energy of the machine. An additional variation of angular speed is added by multiplying by the coefficient dynamic D (generated by the forces out of mechanism and or by the forces generated by the elasticity of the system. Kinetic energy conservation shows angular speed variation (from the shaft with inertial masses, while the dynamic coefficient introduces the variation of w with forces acting in the mechanism. Deriving the first equation of motion of the machine one can obtain the second equation of motion dynamic. From the second equation of motion of the machine it determines the angular acceleration of the shaft. It shows the distribution of the forces on the mechanism to the internal combustion heat engines. Dynamic, the velocities can be distributed in the same way as forces. Practically, in the dynamic regimes, the velocities have the same timing as the forces. Calculations should be made for an engine with a single cylinder. Originally exemplification is done for a classic distribution mechanism, and then even the module B distribution mechanism of an Otto engine type.

  7. [Analgesia in labor with continuous--drip venous perfusion of ketamine].

    Science.gov (United States)

    Bertoletti, P L; Ciucci, N

    1981-04-01

    A personal opinion on the way analgesia should be piloted in labour is expressed and reference is made to personal results with continuous venous drip perfusion of ketamin with a SIC P77 infusional pump in 110 cases. The data from the series are described and particular attention is given to the behaviour of the drug with respect to uterine dynamics and the incidence of instrumental intervention. Stress is laid on the considerable benefits offered by the method, including reduction of the labour period and good maternal and foetal tolerance.

  8. Exercise: Benefits of Exercise

    Medline Plus

    Full Text Available ... please turn Javascript on. Exercise: Benefits of Exercise Health Benefits One of the Healthiest Things You Can ... yourself. Studies have shown that exercise provides many health benefits and that older adults can gain a ...

  9. Benefits of Physical Activity

    Science.gov (United States)

    ... page from the NHLBI on Twitter. Benefits of Physical Activity Physical activity has many health benefits. These benefits ... of physical activity for your heart and lungs. Physical Activity Strengthens Your Heart and Improves Lung Function When ...

  10. CT perfusion imaging as an early biomarker of differential response to stereotactic radiosurgery in C6 rat gliomas.

    Directory of Open Access Journals (Sweden)

    Timothy Pok Chi Yeung

    Full Text Available BACKGROUND: The therapeutic efficacy of stereotactic radiosurgery for glioblastoma is not well understood, and there needs to be an effective biomarker to identify patients who might benefit from this treatment. This study investigated the efficacy of computed tomography (CT perfusion imaging as an early imaging biomarker of response to stereotactic radiosurgery in a malignant rat glioma model. METHODS: Rats with orthotopic C6 glioma tumors received either mock irradiation (controls, N = 8 or stereotactic radiosurgery (N = 25, 12 Gy in one fraction delivered by Helical Tomotherapy. Twelve irradiated animals were sacrificed four days after stereotactic radiosurgery to assess acute CT perfusion and histological changes, and 13 irradiated animals were used to study survival. Irradiated animals with survival >15 days were designated as responders while those with survival ≤15 days were non-responders. Longitudinal CT perfusion imaging was performed at baseline and regularly for eight weeks post-baseline. RESULTS: Early signs of radiation-induced injury were observed on histology. There was an overall survival benefit following stereotactic radiosurgery when compared to the controls (log-rank P<0.04. Responders to stereotactic radiosurgery showed lower relative blood volume (rBV, and permeability-surface area (PS product on day 7 post-stereotactic radiosurgery when compared to controls and non-responders (P<0.05. rBV and PS on day 7 showed correlations with overall survival (P<0.05, and were predictive of survival with 92% accuracy. CONCLUSIONS: Response to stereotactic radiosurgery was heterogeneous, and early selection of responders and non-responders was possible using CT perfusion imaging. Validation of CT perfusion indices for response assessment is necessary before clinical implementation.

  11. Hepatic perfusion disorders: Etiopathogenesis and related diseases

    Institute of Scientific and Technical Information of China (English)

    Jin-Lin Tian; Jin-Shan Zhang

    2006-01-01

    In this article, we have reviewed the hepatic perfusion disorder (HPD), etiopathogenesis of HPD and corresponding diseases. Review of the literature was based on computer searches (PubMed, Index Medicus)and personal experiences. We considered HPD reflects perfusion differences due to redistribution of arterial blood flow among segments, subsegments and lobes of the liver. The plain CT scan findings of HPD manifests as triangular or wedge-shaped areas of low attenuation.On contrast-enhanced CT scan, HPD manifests multiple (or single) transient wedge-shaped, rotundloid or irregular appearance, homogeneous hyperattenuation (in less cases, hypoattenuation) during the hepatic arterial phase (HAP) and isoattenuated or slightly hyperattenuated areas during the portal arterial phase.Dynamic enhanced magnetic resonance (MR) features are similar to enhanced CT scan. Angiographic findings include non-opacification of portal vein on portograms or wedge-shaped segmental staining in arterial and parenchymal phases on hepatic angiograms. The causes of HPD are arterioportal shunts (APS), intrahepatic vascular compressions and portal vein occlusion,steal phenomenon by hypervascular tumors, vascular variations and any other unknown reasons. It is very important for radiologists to be familiar with the various appearances of HPD to avoid false-positive diagnosis of pseudolesions and not to overestimate the extent of the disease.

  12. Diffusion and perfusion imaging of bone marrow

    Energy Technology Data Exchange (ETDEWEB)

    Biffar, Andreas; Dietrich, Olaf [Josef Lissner Laboratory for Biomedical Imaging, Department of Clinical Radiology, LMU University Hospitals, Grosshadern-Munich (Germany); Sourbron, Steven [Josef Lissner Laboratory for Biomedical Imaging, Department of Clinical Radiology, LMU University Hospitals, Grosshadern-Munich (Germany); Division of Medical Physics, University of Leeds, Leeds (United Kingdom); Duerr, Hans-Roland [Department of Orthopedic Surgery, LMU University Hospitals, Grosshadern-Munich (Germany); Reiser, Maximilian F. [Josef Lissner Laboratory for Biomedical Imaging, Department of Clinical Radiology, LMU University Hospitals, Grosshadern-Munich (Germany); Department of Clinical Radiology, LMU University Hospitals, Grosshadern-Munich (Germany); Baur-Melnyk, Andrea, E-mail: andrea.baur@med.uni-muenchen.de [Department of Clinical Radiology, LMU University Hospitals, Grosshadern-Munich (Germany)

    2010-12-15

    In diffusion-weighted magnetic resonance imaging (DWI), the observed MRI signal intensity is attenuated by the self-diffusion of water molecules. DWI provides information about the microscopic structure and organization of a biological tissue, since the extent and orientation of molecular motion is influenced by these tissue properties. The most common method to measure perfusion in the body using MRI is T1-weighted dynamic contrast enhancement (DCE-MRI). The analysis of DCE-MRI data allows determining the perfusion and permeability of a biological tissue. DWI as well as DCE-MRI are established techniques in MRI of the brain, while significantly fewer studies have been published in body imaging. In recent years, both techniques have been applied successfully in healthy bone marrow as well as for the characterization of bone marrow alterations or lesions; e.g., DWI has been used in particular for the differentiation of benign and malignant vertebral compression fractures. In this review article, firstly a short introduction to diffusion-weighted and dynamic contrast-enhanced MRI is given. Non-quantitative and quantitative approaches for the analysis of DWI and semiquantitative and quantitative approaches for the analysis of DCE-MRI are introduced. Afterwards a detailed overview of the results of both techniques in healthy bone marrow and their applications for the diagnosis of various bone-marrow pathologies, like osteoporosis, bone tumors, and vertebral compression fractures are described.

  13. Electronics Environmental Benefits Calculator

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Electronics Environmental Benefits Calculator (EEBC) was developed to assist organizations in estimating the environmental benefits of greening their purchase,...

  14. Motion correction for improving the accuracy of dual-energy myocardial perfusion CT imaging

    Science.gov (United States)

    Pack, Jed D.; Yin, Zhye; Xiong, Guanglei; Mittal, Priya; Dunham, Simon; Elmore, Kimberly; Edic, Peter M.; Min, James K.

    2016-03-01

    Coronary Artery Disease (CAD) is the leading cause of death globally [1]. Modern cardiac computed tomography angiography (CCTA) is highly effective at identifying and assessing coronary blockages associated with CAD. The diagnostic value of this anatomical information can be substantially increased in combination with a non-invasive, low-dose, correlative, quantitative measure of blood supply to the myocardium. While CT perfusion has shown promise of providing such indications of ischemia, artifacts due to motion, beam hardening, and other factors confound clinical findings and can limit quantitative accuracy. In this paper, we investigate the impact of applying a novel motion correction algorithm to correct for motion in the myocardium. This motion compensation algorithm (originally designed to correct for the motion of the coronary arteries in order to improve CCTA images) has been shown to provide substantial improvements in both overall image quality and diagnostic accuracy of CCTA. We have adapted this technique for application beyond the coronary arteries and present an assessment of its impact on image quality and quantitative accuracy within the context of dual-energy CT perfusion imaging. We conclude that motion correction is a promising technique that can help foster the routine clinical use of dual-energy CT perfusion. When combined, the anatomical information of CCTA and the hemodynamic information from dual-energy CT perfusion should facilitate better clinical decisions about which patients would benefit from treatments such as stent placement, drug therapy, or surgery and help other patients avoid the risks and costs associated with unnecessary, invasive, diagnostic coronary angiography procedures.

  15. Quantifying coronary sinus flow and global LV perfusion at 3T

    Directory of Open Access Journals (Sweden)

    Bloch Karin

    2009-06-01

    Full Text Available Abstract Background Despite the large availability of 3T MR scanners and the potential of high field imaging, this technical platform has yet to prove its usefulness in the cardiac MR setting, where 1.5T remains the established standard. Global perfusion of the left ventricle, as well as the coronary flow reserve (CFR, can provide relevant diagnostic information, and MR measurements of these parameters may benefit from increased field strength. Quantitative flow measurements in the coronary sinus (CS provide one method to investigate these parameters. However, the ability of newly developed faster MR sequences to measure coronary flow during a breath-hold at 3T has not been evaluated. Methods The aim of this work was to measure CS flow using segmented phase contrast MR (PC MR on a clinical 3T MR scanner. Parallel imaging was employed to reduce the total acquisition time. Global LV perfusion was calculated by dividing CS flow with left ventricular (LV mass. The repeatability of the method was investigated by measuring the flow three times in each of the twelve volunteers. Phantom experiments were performed to investigate potential error sources. Results The average CS flow was determined to 88 ± 33 ml/min and the deduced LV perfusion was 0.60 ± 0.22 ml/min·g, in agreement with published values. The repeatability (1-error of the three repeated measurements in each subject was on average 84%. Conclusion This work demonstrates that the combination of high field strength (3T, parallel imaging and segmented gradient echo sequences allow for quantification of the CS flow and global perfusion within a breath-hold.

  16. Non-invasive monitoring of peripheral perfusion: an exploration of non-invasive peripheral perfusion monitoring for applications in research & healthcare

    OpenAIRE

    Blaxter, Laurence

    2015-01-01

    The need for real-time, prognostic perfusion data has been widely recognised in clinical practice and academia. Perfusion, the volumetric blood low to tissue, is an important tool for haemodynamic monitoring, since perfusion adequacy is vital to tissue health. Perfusion can serve as both a diagnostic indicator and a fundamental research tool. However, lack of a low cost, easily applied, and non-invasive sensor technology capable of measuring peripheral perfusion in absolute volumetric units i...

  17. Dynamics of cyclic machines

    CERN Document Server

    Vulfson, Iosif

    2015-01-01

    This book focuses on modern methods of oscillation analysis in machines, including cyclic action mechanisms (linkages, cams, steppers, etc.). It presents schematization techniques and mathematical descriptions of oscillating systems, taking into account the variability of the parameters and nonlinearities, engineering evaluations of dynamic errors, and oscillation suppression methods. The majority of the book is devoted to the development of new methods of dynamic analysis and synthesis for cyclic machines that form regular oscillatory systems with multiple duplicate modules.  There are also sections examining aspects of general engineering interest (nonlinear dissipative forces, systems with non-stationary constraints, impacts and pseudo-impacts in clearances, etc.)  The examples in the book are based on the widely used results of theoretical and experimental studies as well as engineering calculations carried out in relation to machines used in the textile, light, polygraphic and other industries. Particu...

  18. Chatter and machine tools

    CERN Document Server

    Stone, Brian

    2014-01-01

    Focussing on occurrences of unstable vibrations, or Chatter, in machine tools, this book gives important insights into how to eliminate chatter with associated improvements in product quality, surface finish and tool wear. Covering a wide range of machining processes, including turning, drilling, milling and grinding, the author uses his research expertise and practical knowledge of vibration problems to provide solutions supported by experimental evidence of their effectiveness. In addition, this book contains links to supplementary animation programs that help readers to visualise the ideas detailed in the text. Advancing knowledge in chatter avoidance and suggesting areas for new innovations, Chatter and Machine Tools serves as a handbook for those desiring to achieve significant reductions in noise, longer tool and grinding wheel life and improved product finish.

  19. Machines and Metaphors

    Directory of Open Access Journals (Sweden)

    Ángel Martínez García-Posada

    2016-10-01

    Full Text Available The edition La ley del reloj. Arquitectura, máquinas y cultura moderna (Cátedra, Madrid, 2016 registers the useful paradox of the analogy between architecture and technique. Its author, the architect Eduardo Prieto, also a philosopher, professor and writer, acknowledges the obvious distance from machines to buildings, so great that it can only be solved using strange comparisons, since architecture does not move nor are the machines habitable, however throughout the book, from the origin of the metaphor of the machine, with clarity in his essay and enlightening erudition, he points out with certainty some concomitances of high interest, drawing throughout history a beautiful cartography of the fruitful encounter between organics and mechanics.

  20. Machine Learning Markets

    CERN Document Server

    Storkey, Amos

    2011-01-01

    Prediction markets show considerable promise for developing flexible mechanisms for machine learning. Here, machine learning markets for multivariate systems are defined, and a utility-based framework is established for their analysis. This differs from the usual approach of defining static betting functions. It is shown that such markets can implement model combination methods used in machine learning, such as product of expert and mixture of expert approaches as equilibrium pricing models, by varying agent utility functions. They can also implement models composed of local potentials, and message passing methods. Prediction markets also allow for more flexible combinations, by combining multiple different utility functions. Conversely, the market mechanisms implement inference in the relevant probabilistic models. This means that market mechanism can be utilized for implementing parallelized model building and inference for probabilistic modelling.

  1. Machine Learning for Security

    CERN Document Server

    CERN. Geneva

    2015-01-01

    Applied statistics, aka ‘Machine Learning’, offers a wealth of techniques for answering security questions. It’s a much hyped topic in the big data world, with many companies now providing machine learning as a service. This talk will demystify these techniques, explain the math, and demonstrate their application to security problems. The presentation will include how-to’s on classifying malware, looking into encrypted tunnels, and finding botnets in DNS data. About the speaker Josiah is a security researcher with HP TippingPoint DVLabs Research Group. He has over 15 years of professional software development experience. Josiah used to do AI, with work focused on graph theory, search, and deductive inference on large knowledge bases. As rules only get you so far, he moved from AI to using machine learning techniques identifying failure modes in email traffic. There followed digressions into clustered data storage and later integrated control systems. Current ...

  2. Extended liver storage. Development and optimization of liver preservation and extracorporeal machine perfusion

    NARCIS (Netherlands)

    Berendsen, T.A.

    2014-01-01

    This work focuses on the improvement of liver graft quality through the use of MP. It has been established that intracellular ATP is a significant measure of the cellular viability of an explanted organ. Chapter 1 examines the relationship between intracellular ATP and cellular viability at differen

  3. Preservation of the liver for transplantation: Machine perfusion-based strategies for extended preservation and recovery

    NARCIS (Netherlands)

    Bruinsma, B.G.

    2015-01-01

    The field of liver transplantation remains burdened by a severe shortage of donor organs. An important limitation to the use of many livers is the ex vivo preservation of the organ, as maintaining the viability of the donor organ while outside the body is essential for successful transplantation. Th

  4. High speed perfusion imaging based on laser speckle fluctuations

    NARCIS (Netherlands)

    Draijer, Matthijs Johannes

    2010-01-01

    Noninvasive methods to visualize blood flow in tissue are important in the clinical environment. Most methods use dynamic speckles to measure the level of perfusion. The most well-known techniques based on these speckle patterns are laser Doppler perfusion imaging (LDPI) and laser speckle contrast a

  5. Perfusion computed tomography evaluation of angiogenesis in liver cancer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Han Feng [Xuanwu Hospital, Capital Medical University, Department of Clinical Pain, Beijing (China); Hospital of North Sichuan Medical College, Department of Radiology, Nanchong City, Sichuan Province (China); Du, Yong; Xu, Xiao Xue; Li, Yang [Hospital of North Sichuan Medical College, Department of Radiology, Nanchong City, Sichuan Province (China); Ni, Jia Xiang [Xuanwu Hospital, Capital Medical University, Department of Clinical Pain, Beijing (China); Zhou, Xiang Ping [West China Hospital, Sichuan University, Department of Radiology, Chengdu City, Sichuan Province (China); Li, Jin Dong [Hospital of North Sichuan Medical College, Department of General Surgery, Nanchong City, Sichuan Province (China); Zhang, Qing [Hospital of North Sichuan Medical College, Department of Ultrasound, Nanchong City, Sichuan Province (China)

    2010-06-15

    To investigate the value of computed tomography (CT) perfusion imaging for assessment of angiogenesis in liver cancer. Twenty-one patients with histologically proven liver cancer underwent CT perfusion examination. We compared the following perfusion parameters in the tumour area versus the non-tumour area: total blood flow (TBF), hepatic arterial perfusion (HAP), hepatic portal perfusion (HPP) and hepatic arterial perfusion index (HAPI). Slices of postoperative specimen were stained with haematoxylin-eosin and anti-CD34 immunohistochemistry. The slices were evaluated with emphasis on the CD34-positive neovasculature in the tumour parenchyma. Tumour microvascular density (MVD) was calculated according to the Weidner method. Pearson correlation was used to detect correlations between tumour MVD and tumour perfusion parameters. TBF and HPP in the tumour area were lower than in the non-tumour area (P < 0.05). HAP and HAPI in the tumour area were higher than those of the non-tumour area (P < 0.05). TBF and HAP in the tumour area correlated with MVD in the tumour (P < 0.05), with correlation coefficients of 0.849 and 0.829, respectively. CT perfusion imaging can quantitatively assess the blood supply and its distribution in liver cancer. TBF or HAP may be a useful parameter in assessing angiogenesis of liver cancer. (orig.)

  6. Magnetic Resonance Perfusion Imaging in the Study of Language

    Science.gov (United States)

    Hillis, Argye E.

    2007-01-01

    This paper provides a brief review of various uses of magnetic resonance perfusion imaging in the investigation of brain/language relationships. The reviewed studies illustrate how perfusion imaging can reveal areas of brain where dysfunction due to low blood flow is associated with specific language deficits, and where restoration of blood flow…

  7. Method, apparatus and software for analyzing perfusion images

    NARCIS (Netherlands)

    Spreeuwers, Lieuwe Jan; Breeuwer, Marcel

    2007-01-01

    The invention relates to a method for analyzing perfusion images, in particular MR pertbsion images, of a human or animal organ including the steps of: (a) defining at least one contour of the organ, and (b) establishing at least one perfusion parameter of a region of interest of said organ within a

  8. Method, apparatus and software for analyzing perfusion images

    NARCIS (Netherlands)

    Spreeuwers, Lieuwe Jan; Breeuwer, Marcel

    2004-01-01

    The invention relates to a method for analyzing perfusion images, in particular MR pertbsion images, of a human or animal organ including the steps of: (a) defining at least one contour of the organ, and (b) establishing at least one perfusion parameter of a region of interest of said organ within a

  9. Perfusion MR imaging for differentiation of benign and malignant meningiomas

    NARCIS (Netherlands)

    Zhang, Hao; Rodiger, Lars A.; Shen, Tianzhen; Miao, Jingtao; Oudkerk, Matthijs

    2008-01-01

    Introduction Our purpose was to determine whether perfusion MR imaging can be used to differentiate benign and malignant meningiomas on the basis of the differences in perfusion of tumor parenchyma and/or peritumoral edema. Methods A total of 33 patients with preoperative meningiomas (25 benign and

  10. A model system for perfusion quantification using FAIR

    DEFF Research Database (Denmark)

    Andersen, I.K.; Sidaros, Karam; Gesmar, H

    2000-01-01

    Flow-sensitive experiments (FAIR) have been performed on a tube-flow phantom in order to validate quantitative perfusion measurements on humans. A straight-forward correspondence between perfusion and bulk-flow is found. It is shown that the flow phantom model only holds when the slice profiles...

  11. Tissue-specific sparse deconvolution for brain CT perfusion.

    Science.gov (United States)

    Fang, Ruogu; Jiang, Haodi; Huang, Junzhou

    2015-12-01

    Enhancing perfusion maps in low-dose computed tomography perfusion (CTP) for cerebrovascular disease diagnosis is a challenging task, especially for low-contrast tissue categories where infarct core and ischemic penumbra usually occur. Sparse perfusion deconvolution has been recently proposed to effectively improve the image quality and diagnostic accuracy of low-dose perfusion CT by extracting the complementary information from the high-dose perfusion maps to restore the low-dose using a joint spatio-temporal model. However the low-contrast tissue classes where infarct core and ischemic penumbra are likely to occur in cerebral perfusion CT tend to be over-smoothed, leading to loss of essential biomarkers. In this paper, we propose a tissue-specific sparse deconvolution approach to preserve the subtle perfusion information in the low-contrast tissue classes. We first build tissue-specific dictionaries from segmentations of high-dose perfusion maps using online dictionary learning, and then perform deconvolution-based hemodynamic parameters estimation for block-wise tissue segments on the low-dose CTP data. Extensive validation on clinical datasets of patients with cerebrovascular disease demonstrates the superior performance of our proposed method compared to state-of-art, and potentially improve diagnostic accuracy by increasing the differentiation between normal and ischemic tissues in the brain.

  12. Scintigraphic assessment of distal extremity perfusion in 17 patients.

    Science.gov (United States)

    Goggin, J M; Hoskinson, J J; Carpenter, J W; Roush, J K; McLaughlin, R M; Anderson, D E

    1997-01-01

    To assess the role of scintigraphic evaluation of distal limb perfusion, the medical records and scintigraphic perfusion images of 17 animals (8 dogs, 2 cats, 2 calves, 4 birds and 1 ferret) with clinical signs of distal limb ischemia were examined retrospectively. Images were obtained at 5 and 10 minutes following injection of 99mTc-MDP, or 99mTc-DTPA. The initial scintigraphic diagnoses of 17 animals included complete ischemia (8/17), partially reduced perfusion (5/17), and normal to increased perfusion (4/17). In 4 of the animals with partially reduced perfusion, follow-up scans indicated progression to complete ischemia (1/4) or normal to increased perfusion (3/4). Nine of 17 animals had a final scintigraphic diagnosis of complete distal limb ischemia, and these animals were either euthanized (5/9) or had limb amputation (4/9). A final diagnosis of complete ischemia was supported with either repeat scanning (3/10), continued clinical observation (6/10) and/or pathological examination (10/10). Clinical signs of ischemia resolved in all (7/17) animals with increased or normal perfusion on their final scan. Scintigraphy provided a safe and noninvasive assessment of distal limb perfusion, which corresponded with clinical outcome.

  13. Advanced Analysis of Nontraditional Machining

    CERN Document Server

    Tsai, Hung-Yin

    2013-01-01

    Nontraditional machining utilizes thermal, chemical, electrical, mechanical and optical sources of energy to form and cut materials. Advanced Analysis of Nontraditional Machining explains in-depth how each of these advanced machining processes work, their machining system components, and process variables and industrial applications, thereby offering advanced knowledge and scientific insight. This book also documents the latest and frequently cited research results of a few key nonconventional machining processes for the most concerned topics in industrial applications, such as laser machining, electrical discharge machining, electropolishing of die and mold, and wafer processing for integrated circuit manufacturing. This book also: Fills the gap of the advanced knowledge of nonconventional machining between industry and research Documents latest and frequently cited research of key nonconventional machining processes for the most sought after topics in industrial applications Demonstrates advanced multidisci...

  14. Machining strategy choice: performance VIEWER

    CERN Document Server

    Tapie, Laurent; Anselmetti, Bernard

    2009-01-01

    Nowadays high speed machining (HSM) machine tool combines productivity and part quality. So mould and die maker invested in HSM. Die and mould features are more and more complex shaped. Thus, it is difficult to choose the best machining strategy according to part shape. Geometrical analysis of machining features is not sufficient to make an optimal choice. Some research show that security, technical, functional and economical constrains must be taken into account to elaborate a machining strategy. During complex shape machining, production system limits induce feed rate decreases, thus loss of productivity, in some part areas. In this paper we propose to analyse these areas by estimating tool path quality. First we perform experiments on HSM machine tool to determine trajectory impact on machine tool behaviour. Then, we extract critical criteria and establish models of performance loss. Our work is focused on machine tool kinematical performance and numerical controller unit calculation capacity. We implement...

  15. Electrical machines diagnosis

    CERN Document Server

    Trigeassou, Jean-Claude

    2013-01-01

    Monitoring and diagnosis of electrical machine faults is a scientific and economic issue which is motivated by objectives for reliability and serviceability in electrical drives.This book provides a survey of the techniques used to detect the faults occurring in electrical drives: electrical, thermal and mechanical faults of the electrical machine, faults of the static converter and faults of the energy storage unit.Diagnosis of faults occurring in electrical drives is an essential part of a global monitoring system used to improve reliability and serviceability. This diagnosis is perf

  16. Refrigerating machine oil

    Energy Technology Data Exchange (ETDEWEB)

    Nozawa, K.

    1981-03-17

    Refrigerating machine oil to be filled in a sealed motorcompressor unit constituting a refrigerating cycle system including an electric refrigerator, an electric cold-storage box, a small-scaled electric refrigerating show-case, a small-scaled electric cold-storage show-case and the like, is arranged to have a specifically enhanced property, in which smaller initial driving power consumption of the sealed motor-compressor and easier supply of the predetermined amount of the refrigerating machine oil to the refrigerating system are both guaranteed even in a rather low environmental temperature condition.

  17. Machine shop basics

    CERN Document Server

    Miller, Rex

    2004-01-01

    Use the right tool the right wayHere, fully updated to include new machines and electronic/digital controls, is the ultimate guide to basic machine shop equipment and how to use it. Whether you're a professional machinist, an apprentice, a trade student, or a handy homeowner, this fully illustrated volume helps you define tools and use them properly and safely. It's packed with review questions for students, and loaded with answers you need on the job.Mark Richard Miller is a Professor and Chairman of the Industrial Technology Department at Texas A&M University in Kingsville, T

  18. Electrical machines & their applications

    CERN Document Server

    Hindmarsh, J

    1984-01-01

    A self-contained, comprehensive and unified treatment of electrical machines, including consideration of their control characteristics in both conventional and semiconductor switched circuits. This new edition has been expanded and updated to include material which reflects current thinking and practice. All references have been updated to conform to the latest national (BS) and international (IEC) recommendations and a new appendix has been added which deals more fully with the theory of permanent-magnets, recognising the growing importance of permanent-magnet machines. The text is so arra

  19. Clojure for machine learning

    CERN Document Server

    Wali, Akhil

    2014-01-01

    A book that brings out the strengths of Clojure programming that have to facilitate machine learning. Each topic is described in substantial detail, and examples and libraries in Clojure are also demonstrated.This book is intended for Clojure developers who want to explore the area of machine learning. Basic understanding of the Clojure programming language is required, but thorough acquaintance with the standard Clojure library or any libraries are not required. Familiarity with theoretical concepts and notation of mathematics and statistics would be an added advantage.

  20. Perpetual Motion Machine

    OpenAIRE

    D. Tsaousis

    2008-01-01

    Ever since the first century A.D. there have been relative descriptions of known devices as well as manufactures for the creation of perpetual motion machines. Although physics has led, with two thermodynamic laws, to the opinion that a perpetual motion machine is impossible to be manufactured, inventors of every age and educational level appear to claim that they have invented something «entirely new» or they have improved somebody else’s invention, which «will function henceforth perpetuall...

  1. Man - Machine Communication

    CERN Document Server

    Petersen, Peter; Nielsen, Henning

    1984-01-01

    This report describes a Man-to-Machine Communication module which together with a STAC can take care of all operator inputs from the touch-screen, tracker balls and mechanical buttons. The MMC module can also contain a G64 card which could be a GPIB driver but many other G64 cards could be used. The soft-ware services the input devices and makes the results accessible from the CAMAC bus. NODAL functions for the Man Machine Communication is implemented in the STAC and in the ICC.

  2. Machine Fault Signature Analysis

    Directory of Open Access Journals (Sweden)

    Pratesh Jayaswal

    2008-01-01

    Full Text Available The objective of this paper is to present recent developments in the field of machine fault signature analysis with particular regard to vibration analysis. The different types of faults that can be identified from the vibration signature analysis are, for example, gear fault, rolling contact bearing fault, journal bearing fault, flexible coupling faults, and electrical machine fault. It is not the intention of the authors to attempt to provide a detailed coverage of all the faults while detailed consideration is given to the subject of the rolling element bearing fault signature analysis.

  3. Research advances in coupling bionic optimization design method for CNC machine tools based on ergonomics

    Directory of Open Access Journals (Sweden)

    Shihao LIU

    2015-06-01

    Full Text Available Currently, most Chinese CNC machine tools' dynamic and static performances have large gap comparing with the similar foreign products, and the CNC machine tools users' human-centered design demand are ignored, which results in that the domestic CNC machine tools' overall competitiveness is relatively low. In order to solve the above problem, the ergonomics and coupling bionics are adopted to study collaborative optimization design method for CNC machine tools based on the domestic and foreign machine tool design method research achievement. The CNC machine tools' "man-machine-environment" interaction mechanism can be built by combining with ergonomic, and then the CNC ergonomic design criteria is obtained. Taking the coupling bionics as theoretical basis, the biological structures "morphology-structure-function-adaptive growth" multiple coupling mechanism can be studied, and the mechanical performance benefits structure can be extracted, then the CNC machine tools structural coupling bionic design technology is obtained by combining with the similarity principle. Combination of CNC machine tools' ergonomic design criteria and coupling bionic design technology, and considering the CNC machine tool performance's interaction and coupling mechanisms, a new multi-objective optimization design method can be obtained, which is verified through CNC machine tools' prototype experiments. The new optimization design method for CNC machine tools can not only help improve the whole machine's dynamic and static performance, but also has a bright prospect because of the "man-oriented" design concept.

  4. [Ocular perfusion pressure and its relevance for glaucoma].

    Science.gov (United States)

    Schmidl, D; Werkmeister, R; Garhöfer, G; Schmetterer, L

    2015-02-01

    Ocular perfusion pressure is defined as the difference between arterial and venous pressure in ocular vessels. In practice, mean arterial pressure is used to substitute for arterial pressure in ocular vessels while intraocular pressure gives an estimate for ocular venous pressure. This results in a value that is easy to calculate and which is of importance since several studies have shown that it is correlated to the prevalence, incidence and progression of primary open angle glaucoma. Today, ocular perfusion pressure is used to estimate individual risks. Since no target value for ocular perfusion pressure can be defined, direct therapeutic intervention is difficult. Still, it has to be kept in mind that lowering intraocular pressure automatically leads to an increase in ocular perfusion pressure. The present article also points out problems and limitations in the concept of ocular perfusion pressure and suggests possible solutions for these problems in the future.

  5. A model system for perfusion quantification using FAIR

    DEFF Research Database (Denmark)

    Andersen, I.K.; Sidaros, Karam; Gesmar, H

    2000-01-01

    of the involved RF pulses are taken into account. A small flow-independent off-set may be present in the data. The off-set is explained by the model. Based on the correspondence between the phantom and the in vivo models, it is shown that the lowest flow values that could be measured in the phantom correspond...... to perfusion values lower than the cortical perfusion in the brain. Thus, the experimental accuracy and the computational methods for quantitative perfusion measurements in vivo can be validated by a tube-flow phantom......Flow-sensitive experiments (FAIR) have been performed on a tube-flow phantom in order to validate quantitative perfusion measurements on humans. A straight-forward correspondence between perfusion and bulk-flow is found. It is shown that the flow phantom model only holds when the slice profiles...

  6. A model system for perfusion quantification using FAIR

    DEFF Research Database (Denmark)

    Andersen, Irene Klærke; Sidaros, Karam; Gesmar, Henrik

    2000-01-01

    of the involved RF pulses are taken into account. A small flow-independent off-set may be present in the data. The off-set is explained by the model. Based on the correspondence between the phantom and the in vivo models, it is shown that the lowest flow values that could be measured in the phantom correspond...... to perfusion values lower than the cortical perfusion in the brain. Thus, the experimental accuracy and the computational methods for quantitative perfusion measurements in vivo can be validated by a tube-flow phantom.......Flow-sensitive experiments (FAIR) have been performed on a tube-flow phantom in order to validate quantitative perfusion measurements on humans. A straight-forward correspondence between perfusion and bulk-flow is found. It is shown that the flow phantom model only holds when the slice profiles...

  7. Impedance plethysmography: a new method for continuous muscle perfusion monitoring.

    Science.gov (United States)

    Concannon, M J; Stewart, D H; Welsh, C F; Puckett, C L

    1991-08-01

    Vigilant postoperative monitoring of the buried muscle flap is critical after free transfer because early diagnosis of vascular insufficiency is essential to allow prompt correction. We have identified a monitoring method utilizing needle electrodes and impedance plethysmography that gives a beat-to-beat representation of muscular perfusion. In 25 New Zealand White rabbits the gastrocnemius muscle was isolated on its vascular pedicle, and two intramuscular needle electrodes were placed. The instantaneous impedance changes of the muscle (corresponding to the pulsatile volume changes of perfusion) were measured and recorded. Using this representation of perfusion, an independent judge was able to correctly diagnose muscular ischemia 100 percent of the time (n = 25). Further, the judge was able to correctly distinguish the ischemia as arterial (n = 10) or venous (n = 10) in origin 100 percent of the time. Additionally, we monitored muscle perfusion transcutaneously in five free muscle flaps and demonstrated a reliable impedance signal that correlated with perfusion.

  8. Design of rotating electrical machines

    CERN Document Server

    Pyrhonen , Juha; Hrabovcova , Valeria

    2013-01-01

    In one complete volume, this essential reference presents an in-depth overview of the theoretical principles and techniques of electrical machine design. This timely new edition offers up-to-date theory and guidelines for the design of electrical machines, taking into account recent advances in permanent magnet machines as well as synchronous reluctance machines. New coverage includes: Brand new material on the ecological impact of the motors, covering the eco-design principles of rotating electrical machinesAn expanded section on the design of permanent magnet synchronous machines, now repo

  9. Assessment of the spatial pattern of colorectal tumour perfusion estimated at perfusion CT using two-dimensional fractal analysis

    Energy Technology Data Exchange (ETDEWEB)

    Goh, Vicky; Sanghera, Bal [Mount Vernon Hospital, Paul Strickland Scanner Centre, Northwood, Middlesex (United Kingdom); Wellsted, David M.; Sundin, Josefin [University of Hertfordshire, Research and Development Support Unit, Hatfield (United Kingdom); Halligan, Steve [University College Hospital, Department of Academic Radiology, London (United Kingdom)

    2009-06-15

    The aim was to evaluate the feasibility of fractal analysis for assessing the spatial pattern of colorectal tumour perfusion at dynamic contrast-enhanced CT (perfusion CT). Twenty patients with colorectal adenocarcinoma underwent a 65-s perfusion CT study from which a perfusion parametric map was generated using validated commercial software. The tumour was identified by an experienced radiologist, segmented via thresholding and fractal analysis applied using in-house software: fractal dimension, abundance and lacunarity were assessed for the entire outlined tumour and for selected representative areas within the tumour of low and high perfusion. Comparison was made with ten patients with normal colons, processed in a similar manner, using two-way mixed analysis of variance with statistical significance at the 5% level. Fractal values were higher in cancer than normal colon (p {<=} 0.001): mean (SD) 1.71 (0.07) versus 1.61 (0.07) for fractal dimension and 7.82 (0.62) and 6.89 (0.47) for fractal abundance. Fractal values were lower in 'high' than 'low' perfusion areas. Lacunarity curves were shifted to the right for cancer compared with normal colon. In conclusion, colorectal cancer mapped by perfusion CT demonstrates fractal properties. Fractal analysis is feasible, potentially providing a quantitative measure of the spatial pattern of tumour perfusion. (orig.)

  10. Tumor perfusion increases during hypofractionated short-course radiotherapy in rectal cancer : Sequential perfusion-CT findings

    NARCIS (Netherlands)

    Janssen, Marco H. M.; Aerts, Hugo J. W. L.; Kierkels, Roel G. J.; Backes, Walter H.; Ollers, Michel C.; Buijsen, Jeroen; Lambin, Philippe; Lammering, Guido

    2010-01-01

    Purpose: The purpose of this study was to investigate perfusion of rectal tumors and to determine early responses to short-course hypofractionated radiotherapy (RT). Material and methods: Twenty-three rectal cancer patients were included, which underwent perfusion-CT imaging before (pre-scan) and af

  11. Qualitative and semi-quantitative evaluation of myocardium perfusion with 3 T stress cardiac MRI.

    Science.gov (United States)

    Yun, Chun-Ho; Tsai, Jui-Peng; Tsai, Cheng-Ting; Mok, Greta S P; Sun, Jing-Yi; Hung, Chung-Lieh; Wu, Tung-Hsin; Huang, Wu-Ta; Yang, Fei-Shih; Lee, Jason Jeun-Shenn; Cury, Ricardo C; Fares, Anas; Nshisso, Lemba Dina; Bezerra, Hiram G

    2015-12-07

    3 T MRI has been adopted by some centers as the primary choice for assessment of myocardial perfusion over conventional 1.5 T MRI. However, there is no data published on the potential additional value of incorporating semi-quantitative data from 3 T MRI. This study sought to determine the performance of qualitative 3 T stress magnetic resonance myocardial perfusion imaging (3 T-MRMPI) and the potential incremental benefit of using a semi-quantitative perfusion technique in patients with suspected coronary artery disease (CAD). Fifty eight patients (41 men; mean age: 59 years) referred for elective diagnostic angiography underwent stress 3 T MRMPI with a 32-channel cardiac receiver coil. The MR protocol included gadolinium-enhanced stress first-pass perfusion (0.56 mg/kg, dipyridamole), rest perfusion, and delayed enhancement (DE). Visual analysis was performed in two steps. Ischemia was defined as a territory with perfusion defect at stress study but no DE or a territory with DE but additional peri-infarcted perfusion defect at stress study. Semi-quantitative analysis was calculated by using the upslope of the signal intensity-time curve during the first pass of contrast medium during dipyridamole stress and at rest. ROC analysis was used to determine the MPRI threshold that maximized sensitivity. Quantitative coronary angiography served as the reference standard with significant stenosis defined as >70 % diameter stenosis. Diagnostic performance was determined on a per-patient and per-vessel basis. Qualitative assessment had an overall sensitivity and specificity for detecting significant stenoses of 77 % and 80 %, respectively. By adding MPRI analysis, in cases with negative qualitative assessment, the overall sensitivity increased to 83 %. The impact of MPRI differed depending on the territory; with the sensitivity for detection of left circumflex (LCx) stenosis improving the most after semi-quantification analysis, (66 % versus 83 %). Pure

  12. Machine speech and speaking about machines

    Energy Technology Data Exchange (ETDEWEB)

    Nye, A. [Univ. of Wisconsin, Whitewater, WI (United States)

    1996-12-31

    Current philosophy of language prides itself on scientific status. It boasts of being no longer contaminated with queer mental entities or idealist essences. It theorizes language as programmable variants of formal semantic systems, reimaginable either as the properly epiphenomenal machine functions of computer science or the properly material neural networks of physiology. Whether or not such models properly capture the physical workings of a living human brain is a question that scientists will have to answer. I, as a philosopher, come at the problem from another direction. Does contemporary philosophical semantics, in its dominant truth-theoretic and related versions, capture actual living human thought as it is experienced, or does it instead reflect, regardless of (perhaps dubious) scientific credentials, pathology of thought, a pathology with a disturbing social history.

  13. Perfusion-decellularized pancreas as a natural 3D scaffold for pancreatic tissue and whole organ engineering

    Science.gov (United States)

    Goh, Saik-Kia; Bertera, Suzanne; Olsen, Phillip; Candiello, Joe; Halfter, Willi; Uechi, Guy; Balasubramani, Manimalha; Johnson, Scott; Sicari, Brian; Kollar, Elizabeth; Badylak, Stephen F.; Banerjee, Ipsita

    2013-01-01

    Approximately 285 million people worldwide suffer from diabetes, with insulin supplementation as the most common treatment measure. Regenerative medicine approaches such as a bioengineered pancreas has been proposed as potential therapeutic alternatives. A bioengineered pancreas will benefit from the development of a bioscaffold that supports and enhances cellular function and tissue development. Perfusion-decellularized organs are a likely candidate for use in such scaffolds since they mimic compositional, architectural and biomechanical nature of a native organ. In this study, we investigate perfusion-decellularization of whole pancreas and the feasibility to recellularize the whole pancreas scaffold with pancreatic cell types. Our result demonstrates that perfusion-decellularization of whole pancreas effectively removes cellular and nuclear material while retaining intricate three-dimensional microarchitecture with perfusable vasculature and ductal network and crucial extracellular matrix (ECM) components. To mimic pancreatic cell composition, we recellularized the whole pancreas scaffold with acinar and beta cell lines and cultured up to 5 days. Our result shows successful cellular engraftment within the decellularized pancreas, and the resulting graft gave rise to strong up-regulation of insulin gene expression. These findings support biological utility of whole pancreas ECM as a biomaterials scaffold for supporting and enhancing pancreatic cell functionality and represent a step toward bioengineered pancreas using regenerative medicine approaches. PMID:23787110

  14. Hybrid machining processes perspectives on machining and finishing

    CERN Document Server

    Gupta, Kapil; Laubscher, R F

    2016-01-01

    This book describes various hybrid machining and finishing processes. It gives a critical review of the past work based on them as well as the current trends and research directions. For each hybrid machining process presented, the authors list the method of material removal, machining system, process variables and applications. This book provides a deep understanding of the need, application and mechanism of hybrid machining processes.

  15. Cybernetic anthropomorphic machine systems

    Science.gov (United States)

    Gray, W. E.

    1974-01-01

    Functional descriptions are provided for a number of cybernetic man machine systems that augment the capacity of normal human beings in the areas of strength, reach or physical size, and environmental interaction, and that are also applicable to aiding the neurologically handicapped. Teleoperators, computer control, exoskeletal devices, quadruped vehicles, space maintenance systems, and communications equipment are considered.

  16. ARM : abstract rewriting machine

    NARCIS (Netherlands)

    J.F.T. Kamperman; H.R. Walters (Pum)

    1993-01-01

    textabstractTerm rewriting is frequently used as implementation technique for algebraic specifications. In this paper we present the abstract term rewriting machine (ARM), which has an extremely compact instruction set and imposes no restrictions on the implemented TRSs. Apart from standard

  17. A "Living" Machine

    Institute of Scientific and Technical Information of China (English)

    N.R.Bogatyrev

    2004-01-01

    Biomimetics (or bionics) is the engineering discipline that constructs artificial systems using biological principles. The ideal final result in biomimetics is to create a living machine. But what are the desirable and non-desirable properties of biomimetic product? Where can natural prototypes be found? How can technical solutions be transferred from nature to technology? Can we use living nature like LEGO bricks for construction our machines? How can biology help us? What is a living machine? In biomimetic practice only some "part" (organ, part of organ, tissue) of the observed whole organism is utilized. A possible template for future super-organism extension for biomimetic methods might be drawn from experiments in holistic ecological agriculture (ecological design, permaculture, ecological engineering, etc. ). The necessary translation of these rules to practical action can be achieved with the Russian Theory of Inventive Problem Solving (TRIZ), specifically adjusted to biology. Thus, permaculture, reinforced by a TRIZ conceptual framework, might provide the basis for Super-Organismic Bionics, which is hypothesized as necessary for effective ecological engineering. This hypothesis is supported by a case study-the design of a sustainable artificial nature reserve for wild pollinators as a living machine.

  18. Of machines and men ...

    CERN Multimedia

    CERN; Daniel Boileau

    1990-01-01

    Engineering and construction at LEP. Committed work and physicists motivation to work on this type of machine. With Guido Altarelli Theory Division Physicist, Ugo Amaldi Delphi Experiment Spokesman, Oscar Barbalat Head of Industry and Technology Liaison Office, Jonathan Ellis Head of Theory Division.

  19. Technology Time Machine 2012

    DEFF Research Database (Denmark)

    Lehner, Wolfgang; Fettweis, Gerhard; Fitzek, Frank

    2013-01-01

    The IEEE Technology Time Machine (TTM) is a unique event for industry leaders, academics, and decision making government officials who direct R&D activities, plan research programs or manage portfolios of research activities. This report covers the main topics of the 2nd Symposium of future...

  20. Training Restricted Boltzmann Machines

    DEFF Research Database (Denmark)

    Fischer, Asja

    Restricted Boltzmann machines (RBMs) are probabilistic graphical models that can also be interpreted as stochastic neural networks. Training RBMs is known to be challenging. Computing the likelihood of the model parameters or its gradient is in general computationally intensive. Thus, training...

  1. Laser machining of explosives

    Science.gov (United States)

    Perry, Michael D.; Stuart, Brent C.; Banks, Paul S.; Myers, Booth R.; Sefcik, Joseph A.

    2000-01-01

    The invention consists of a method for machining (cutting, drilling, sculpting) of explosives (e.g., TNT, TATB, PETN, RDX, etc.). By using pulses of a duration in the range of 5 femtoseconds to 50 picoseconds, extremely precise and rapid machining can be achieved with essentially no heat or shock affected zone. In this method, material is removed by a nonthermal mechanism. A combination of multiphoton and collisional ionization creates a critical density plasma in a time scale much shorter than electron kinetic energy is transferred to the lattice. The resulting plasma is far from thermal equilibrium. The material is in essence converted from its initial solid-state directly into a fully ionized plasma on a time scale too short for thermal equilibrium to be established with the lattice. As a result, there is negligible heat conduction beyond the region removed resulting in negligible thermal stress or shock to the material beyond a few microns from the laser machined surface. Hydrodynamic expansion of the plasma eliminates the need for any ancillary techniques to remove material and produces extremely high quality machined surfaces. There is no detonation or deflagration of the explosive in the process and the material which is removed is rendered inert.

  2. Electrical Discharge Machining.

    Science.gov (United States)

    Montgomery, C. M.

    The manual is for use by students learning electrical discharge machining (EDM). It consists of eight units divided into several lessons, each designed to meet one of the stated objectives for the unit. The units deal with: introduction to and advantages of EDM, the EDM process, basic components of EDM, reaction between forming tool and workpiece,…

  3. The Answer Machine.

    Science.gov (United States)

    Feldman, Susan

    2000-01-01

    Discusses information retrieval systems and the need to have them adapt to user needs, integrate information in any format, reveal patterns and trends in information, and answer questions. Topics include statistics and probability; natural language processing; intelligent agents; concept mapping; machine-aided indexing; text mining; filtering;…

  4. Massively collaborative machine learning

    NARCIS (Netherlands)

    Rijn, van J.N.

    2016-01-01

    Many scientists are focussed on building models. We nearly process all information we perceive to a model. There are many techniques that enable computers to build models as well. The field of research that develops such techniques is called Machine Learning. Many research is devoted to develop comp

  5. Recent Advances on Permanent Magnet Machines

    Institute of Scientific and Technical Information of China (English)

    诸自强

    2012-01-01

    This paper overviews advances on permanent magnet(PM) brushless machines over last 30 years,with particular reference to new and novel machine topologies.These include current states and trends for surface-mounted and interior PM machines,electrically and mechanically adjusted variable flux PM machines including memory machine,hybrid PM machines which uniquely integrate PM technology into induction machines,switched and synchronous reluctance machines and wound field machines,Halbach PM machines,dual-rotor PM machines,and magnetically geared PM machines,etc.The paper highlights their features and applications to various market sectors.

  6. Machine-aided indexing at NASA

    Science.gov (United States)

    Silvester, June P.; Genuardi, Michael T.; Klingbiel, Paul H.

    1994-01-01

    This report describes the NASA Lexical Dictionary (NLD), a machine-aided indexing system used online at the National Aeronautics and Space Administration's Center for AeroSpace Information (CASI). This system automatically suggests a set of candidate terms from NASA's controlled vocabulary for any designated natural language text input. The system is comprised of a text processor that is based on the computational, nonsyntactic analysis of input text and an extensive knowledge base that serves to recognize and translate text-extracted concepts. The functions of the various NLD system components are described in detail, and production and quality benefits resulting from the implementation of machine-aided indexing at CASI are discussed.

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

    Science.gov (United States)

    Martin, Alastair J.; Alexander, Matthew D.; McCoy, David B.; Cooke, Daniel L.; Lillaney, Prasheel; Moftakhar, Parham; Amans, Matthew R.; Settecase, Fabio; Nicholson, Andrew; Dowd, Christopher F.; Halbach, Van V.; Higashida, Randall T.; McDermott, Michael W.; Saloner, David; Hetts, Steven W.

    2016-01-01

    Background and Purpose To evaluate the ability of IA MR perfusion to characterize meningioma blood supply. Methods 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. Results 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. PMID:27802268

  8. Machine Shop Facilities

    Data.gov (United States)

    Federal Laboratory Consortium — Projects at IARC can benefit from Fermilab's experienced machinists, welders, and extensive on-site equipment. Equipment includes conventional and CNC mills, lathes,...

  9. Motherhood and the Machine

    Directory of Open Access Journals (Sweden)

    Miglena Nikolchina

    2014-12-01

    Full Text Available In her conceptualization of the human as defined by the capacity for revolt Kristeva unavoidably touches upon issues of robotization, technology, and the virtual. The concepts of animal and machine, however, although they do appear occasionally and in important ways, are never at the focus of her inquiries and are absent in her “New Forms of Revolt.” Yet these two concepts to a large extent define the field of contemporary philosophical debates of the human giving rise to three major theoretical orientations. On the one hand, there is the trend which tries to come to terms with technological novelties and the merging of human and machine that they imply. This trend unfolds under the rubric of “transhuman” or “posthuman” and of the “enhancement” of man. The second trend predominates in animal studies. Mostly in an ethical perspective but also ontologically, this trend, to which Derrida’s later writing made a significant contribution, questions the idea of the “human exception” and the rigorous distinction between man and animal on which this exception rests. While apparently antagonistic, both trends align the human with the animal and oppose it to technology. The third trend collapses the distinctions on which the previous two rely through the lens of biopolitics: drawing on Heidegger, Kojève, and Foucault, it regards contemporary technological transformations as amounting to the animalization of man.  The human disappears in the animal, in the machine, or in the indistinguishability of the two, confirming what Agamben has described as the inoperativeness of the anthropological machine. The present text turns to Kristeva’s conceptions of motherhood and revolt as introducing a powerful inflection in this tripartite field. Remarkably, it is precisely new sagas of rebellious machines like Battlestar “Galactica” that foreground the relevance of Kristeva’s approach.

  10. Machine learning in image steganalysis

    CERN Document Server

    Schaathun, Hans Georg

    2012-01-01

    "The only book to look at steganalysis from the perspective of machine learning theory, and to apply the common technique of machine learning to the particular field of steganalysis; ideal for people working in both disciplines"--

  11. New Applications of Learning Machines

    DEFF Research Database (Denmark)

    Larsen, Jan

    * Machine learning framework for sound search * Genre classification * Music separation * MIMO channel estimation and symbol detection......* Machine learning framework for sound search * Genre classification * Music separation * MIMO channel estimation and symbol detection...

  12. New Applications of Learning Machines

    DEFF Research Database (Denmark)

    Larsen, Jan

    * Machine learning framework for sound search * Genre classification * Music separation * MIMO channel estimation and symbol detection......* Machine learning framework for sound search * Genre classification * Music separation * MIMO channel estimation and symbol detection...

  13. Hinged Shields for Machine Tools

    Science.gov (United States)

    Lallande, J. B.; Poland, W. W.; Tull, S.

    1985-01-01

    Flaps guard against flying chips, but fold away for tool setup. Clear plastic shield in position to intercept flying chips from machine tool and retracted to give operator access to workpiece. Machine shops readily make such shields for own use.

  14. Stacking for machine learning redshifts applied to SDSS galaxies

    OpenAIRE

    Zitlau, Roman; Hoyle, Ben; Paech, Kerstin; Weller, Jochen; Rau, Markus Michael; Seitz, Stella

    2016-01-01

    We present an analysis of a general machine learning technique called 'stacking' for the estimation of photometric redshifts. Stacking techniques can feed the photometric redshift estimate, as output by a base algorithm, back into the same algorithm as an additional input feature in a subsequent learning round. We shown how all tested base algorithms benefit from at least one additional stacking round (or layer). To demonstrate the benefit of stacking, we apply the method to both unsupervised...

  15. Perfusion Pressure Cerebral Infarct (PPCI) trial

    DEFF Research Database (Denmark)

    Vedel, Anne G.; Holmgaard, Frederik; Rasmussen, Lars Simon

    2016-01-01

    to be caused by emboli, but inadequate blood flow caused by other mechanisms may increase ischaemia in the penumbra or cause watershed infarcts. During cardiopulmonary bypass, blood pressure can be below the lower limit of cerebral autoregulation. Although much debated, the constant blood flow provided...... by the cardiopulmonary bypass system is still considered by many as appropriate to avoid cerebral ischaemia despite the low blood pressure. Methods/design: The Perfusion Pressure Cerebral Infarct trial is a single-centre superiority trial with a blinded outcome assessment. The trial is randomising 210 patients...... with coronary vessel and/or valve disease and who are undergoing cardiac surgery with the use of cardiopulmonary bypass. Patients are stratified by age and surgical procedure and are randomised 1:1 to either an increased mean arterial pressure (70–80 mmHg) or ‘usual practice’ (40–50 mmHg) during cardiopulmonary...

  16. Perfused human organs versus Mary Shelley's Frankenstein

    Directory of Open Access Journals (Sweden)

    Leung Lawrence

    2009-01-01

    Full Text Available Abstract Novel drugs have to go through mandatory pre-clinical testing before they can be approved for use in clinical trials. In essence, it is a form of bench-to-bedside (N2B translational medicine, but the wastage rate of target candidates is immensely high. Effects seen in vitro often do not translate to in vivo human settings. The search is on for better models closer to human physiology to be used in pre-clinical drug screening. The Ex Vivo Metrics© system has been introduced where a human organ is harvested and revitalized in a controlled environment suitable for testing of both drug efficacy and potential toxicity. This commentary expresses the author's views regarding this technology of perfused human organs.

  17. Perfused human organs versus Mary Shelley's Frankenstein.

    Science.gov (United States)

    Leung, Lawrence

    2009-01-23

    Novel drugs have to go through mandatory pre-clinical testing before they can be approved for use in clinical trials. In essence, it is a form of bench-to-bedside (N2B) translational medicine, but the wastage rate of target candidates is immensely high. Effects seen in vitro often do not translate to in vivo human settings. The search is on for better models closer to human physiology to be used in pre-clinical drug screening. The Ex Vivo Metrics system has been introduced where a human organ is harvested and revitalized in a controlled environment suitable for testing of both drug efficacy and potential toxicity. This commentary expresses the author's views regarding this technology of perfused human organs.

  18. Perfusion CT of head and neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Razek, Ahmed Abdel Khalek Abdel, E-mail: arazek@mans.edu.eg; Tawfik, Ahmed Mohamed, E-mail: ahm_m_tawfik@hotmail.com; Elsorogy, Lamiaa Galal Ali, E-mail: lamia2elsorogy@hotmail.com; Soliman, Nermin Yehia, E-mail: nermin_eid@hotmail.com

    2014-03-15

    We aim to review the technique and clinical applications of perfusion CT (PCT) of head and neck cancer. The clinical value of PCT in the head and neck includes detection of head and neck squamous cell carcinoma (HNSCC) as it allows differentiation of HNSCC from normal muscles, demarcation of tumor boundaries and tumor local extension, evaluation of metastatic cervical lymph nodes as well as determination of the viable tumor portions as target for imaging-guided biopsy. PCT has been used for prediction of treatment outcome, differentiation between post-therapeutic changes and tumor recurrence as well as monitoring patient after radiotherapy and/or chemotherapy. PCT has a role in cervical lymphoma as it may help in detection of response to chemotherapy and early diagnosis of relapsing tumors.

  19. Measuring perfusion with light (Conference Presentation)

    Science.gov (United States)

    Jansen, Sanne M. A.; de Bruin, Daniel M.; Faber, Dirk J.; van Leeuwen, Ton G.

    2016-03-01

    There is no gold standard test for perfusion evaluation in surgery. Optical Imaging techniques are able to image tissue at high resolution and in real-time. Laser Speckle Contrast Imaging, Optical Coherence Tomography, Sidestream Darkfield and Incident Darkfield all use the interaction of light with tissue to create an image. To test their feasibility and explore validity in a controlled setting, we created a phantom with the optical properties of tissue and microvascular channels of 30-400 micrometer. With a Hamilton Syringe Pump we mimicked blood flow velocities of 0-20 mm/sec. Images of all different modalities at different blood flow velocities were compared in terms of imaging depth, resoluation and hemodynamic parameters.

  20. Hydrogels for Engineering of Perfusable Vascular Networks.

    Science.gov (United States)

    Liu, Juan; Zheng, Huaiyuan; Poh, Patrina S P; Machens, Hans-Günther; Schilling, Arndt F

    2015-07-14

    Hydrogels are commonly used biomaterials for tissue engineering. With their high-water content, good biocompatibility and biodegradability they resemble the natural extracellular environment and have been widely used as scaffolds for 3D cell culture and studies of cell biology. The possible size of such hydrogel constructs with embedded cells is limited by the cellular demand for oxygen and nutrients. For the fabrication of large and complex tissue constructs, vascular structures become necessary within the hydrogels to supply the encapsulated cells. In this review, we discuss the types of hydrogels that are currently used for the fabrication of constructs with embedded vascular networks, the key properties of hydrogels needed for this purpose and current techniques to engineer perfusable vascular structures into these hydrogels. We then discuss directions for future research aimed at engineering of vascularized tissue for implantation.

  1. Ex vivo lung perfusion in Brazil

    Directory of Open Access Journals (Sweden)

    Luis Gustavo Abdalla

    2016-04-01

    Full Text Available Objective: To evaluate the use of ex vivo lung perfusion (EVLP clinically to prepare donor lungs for transplantation. Methods: A prospective study involving EVLP for the reconditioning of extended-criteria donor lungs, the criteria for which include aspects such as a PaO2/FiO2 ratio < 300 mmHg. Between February of 2013 and February of 2014, the lungs of five donors were submitted to EVLP for up to 4 h each. During EVLP, respiratory mechanics were continuously evaluated. Once every hour during the procedure, samples of the perfusate were collected and the function of the lungs was evaluated. Results: The mean PaO2 of the recovered lungs was 262.9 ± 119.7 mmHg at baseline, compared with 357.0 ± 108.5 mmHg after 3 h of EVLP. The mean oxygenation capacity of the lungs improved slightly over the first 3 h of EVLP-246.1 ± 35.1, 257.9 ± 48.9, and 288.8 ± 120.5 mmHg after 1, 2, and 3 h, respectively-without significant differences among the time points (p = 0.508. The mean static compliance was 63.0 ± 18.7 mmHg, 75.6 ± 25.4 mmHg, and 70.4 ± 28.0 mmHg after 1, 2, and 3 h, respectively, with a significant improvement from hour 1 to hour 2 (p = 0.029 but not from hour 2 to hour 3 (p = 0.059. Pulmonary vascular resistance remained stable during EVLP, with no differences among time points (p = 0.284. Conclusions: Although the lungs evaluated remained under physiological conditions, the EVLP protocol did not effectively improve lung function, thus precluding transplantation.

  2. A Naive-Bayes model observer for detection and localization of perfusion defects in cardiac SPECT-MPI

    Science.gov (United States)

    Parages, Felipe M.; O'Connor, J. Michael; Pretorius, P. Hendrik; Brankov, Jovan G.

    2014-03-01

    Model observers (MO) are widely used in medical imaging to act as surrogates of human observers in task-based image quality evaluation, frequently towards optimization of reconstruction algorithms. In SPECT myocardial perfusion imaging (MPI), a realistic task-based approach involves detection and localization of perfusion defects, as well as a subsequent assessment of defect severity. In this paper we explore a machine-learning MO based on Naive- Bayes classification (NB-MO). NB-MO uses a set of polar-map image features to predict lesion detection, localization and severity scores given by five human readers for a set of simulated 3D SPECT-MPI patients. The simulated dataset included lesions with different sizes, perfusion-reduction ratios, and locations. Simulated projections were reconstructed using two readily used methods namely: FBP and OSEM. For validation, a multireader multi-case (MRMC) analysis of alternative free-response ROC (AFROC) curve was performed for NB-MO and human observers. For comparison, we also report performances of a statistical Hotelling Observer applied on polar-map images. Results show excellent agreement between NB-MO and humans, as well as model's good generalization between different reconstruction treatments.

  3. Design of Sugarcane Peeling Machine

    Directory of Open Access Journals (Sweden)

    Ge Xinfeng

    2015-02-01

    Full Text Available In order to solve the problem that appeared in hand peeling sugarcane, the sugarcane peeling machine is designed, the sugarcane peeling machine includes motor, groove wheel, cutting room, slider crank mechanism, reducer (including belt drive, chain drive and so on. The designed sugarcane peeling machine is simulated, the results show that the sugarcane peeling machine can peel sugarcane successfully with convenient, fast and uniform.

  4. Automatically-Programed Machine Tools

    Science.gov (United States)

    Purves, L.; Clerman, N.

    1985-01-01

    Software produces cutter location files for numerically-controlled machine tools. APT, acronym for Automatically Programed Tools, is among most widely used software systems for computerized machine tools. APT developed for explicit purpose of providing effective software system for programing NC machine tools. APT system includes specification of APT programing language and language processor, which executes APT statements and generates NC machine-tool motions specified by APT statements.

  5. Automatically-Programed Machine Tools

    Science.gov (United States)

    Purves, L.; Clerman, N.

    1985-01-01

    Software produces cutter location files for numerically-controlled machine tools. APT, acronym for Automatically Programed Tools, is among most widely used software systems for computerized machine tools. APT developed for explicit purpose of providing effective software system for programing NC machine tools. APT system includes specification of APT programing language and language processor, which executes APT statements and generates NC machine-tool motions specified by APT statements.

  6. Feature Recognition for Virtual Machining

    OpenAIRE

    Xú, Shixin; Anwer, Nabil; Qiao, Lihong

    2014-01-01

    International audience; Virtual machining uses software tools to simulate machining processes in virtual environments ahead of actual production. This paper proposes that feature recognition techniques can be applied in the course of virtual machining, such as identifying some process problems, and presenting corresponding correcting advices. By comparing with the original CAD model, form errors of the machining features can be found. And then corrections are suggested to process designers. T...

  7. Ex Situ Perfusion of Human Limb Allografts for 24 Hours.

    Science.gov (United States)

    Werner, Nicole L; Alghanem, Fares; Rakestraw, Stephanie L; Sarver, Dylan C; Nicely, Bruce; Pietroski, Richard E; Lange, Paul; Rudich, Steven M; Mendias, Christopher L; Rojas-Pena, Alvaro; Magee, John C; Bartlett, Robert H; Ozer, Kagan

    2017-03-01

    Vascularized composite allografts, particularly hand and forearm, have limited ischemic tolerance after procurement. In bilateral hand transplantations, this demands a 2 team approach and expedited transfer of the allograft, limiting the recovery to a small geographic area. Ex situ perfusion may be an alternative allograft preservation method to extend allograft survival time. This is a short report of 5 human limbs maintained for 24 hours with ex situ perfusion. Upper limbs were procured from brain-dead organ donors. Following recovery, the brachial artery was cannulated and flushed with 10 000 U of heparin. The limb was then attached to a custom-made, near-normothermic (30-33°C) ex situ perfusion system composed of a pump, reservoir, and oxygenator. Perfusate was plasma-based with a hemoglobin concentration of 4 to 6 g/dL. Average warm ischemia time was 76 minutes. Perfusion was maintained at an average systolic pressure of 93 ± 2 mm Hg, flow 310 ± 20 mL/min, and vascular resistance 153 ± 16 mm Hg/L per minute. Average oxygen consumption was 1.1 ± 0.2 mL/kg per minute. Neuromuscular electrical stimulation continually displayed contraction until the end of perfusion, and histology showed no myocyte injury. Human limb allografts appeared viable after 24 hours of near-normothermic ex situ perfusion. Although these results are early and need validation with transplantation, this technology has promise for extending allograft storage times.

  8. A laser speckle imaging technique for measuring tissue perfusion.

    Science.gov (United States)

    Forrester, Kevin R; Tulip, J; Leonard, C; Stewart, C; Bray, Robert C

    2004-11-01

    Laser Doppler imaging (LDI) has become a standard method for optical measurement of tissue perfusion, but is limited by low resolution and long measurement times. We have developed an analysis technique based on a laser speckle imaging method that generates rapid, high-resolution perfusion images. We have called it laser speckle perfusion imaging (LSPI). This paper investigates LSPI output and compares it to LDI using blood flow models designed to simulate human skin at various levels of pigmentation. Results show that LSPI parameters can be chosen such that the instrumentation exhibits a similar response to changes in red blood cell concentration (0.1%-5%, 200 microL/min) and velocity (0-800 microL/min, 1% concentration) and, given its higher resolution and quicker response time, could provide a significant advantage over LDI for some applications. Differences were observed in the LDI and LSPI response to tissue optical properties. LDI perfusion values increased with increasing tissue absorption, while LSPI perfusion values showed a slight decrease. This dependence is predictable, owing to the perfusion algorithms specific to each instrument, and, if properly compensated for, should not influence each instrument's ability to measure relative changes in tissue perfusion.

  9. Influence of ocular perfusion pressure fluctuation on glaucoma

    Directory of Open Access Journals (Sweden)

    Min-Zi Ren

    2015-12-01

    Full Text Available AIM:To investigate the influence of ocular perfusion pressure fluctuation on glaucoma. METHODS:Forty patients with primary open angle glaucoma from January 2013 to June 2015 in our hospital were used as observation group and 40 families were used as control group. Circadian fluctuation of intraocular pressure, blood pressure and ocular perfusion pressure in 24h were determined to obtain systolic ocular perfusion pressure(SOPP, diastolic ocular perfusion pressure(DOPPand mean ocular perfusion pressure(MOPP. Pearson linear correlation was used to analyze the correlation of circadian MOPP fluctuation with cup-disc ratio, mean defect(MDand the picture standard deviation(PSD. RESULTS:The fluctuation of MOPP, SOPP and DOPP of observation group were significantly higher than those of control group(Pr=-0.389, 95%CI:-0.612~-0.082; P=0.011, was positively correlated with PSD(r=0.512, 95%CI:0.139 ~0.782; P=0.008; no correlation was found between it and the vertical cup-disc ratio(r=0.115, 95%CI:0.056~0.369; P=0.355. CONCLUSION:Ocular perfusion pressure fluctuations in patients with primary open angle glaucoma may reflect the severity of the disease and may make the situation aggravating. Therefore through perfusion pressure monitor in 24h may help us understand the ocular blood flow and the development of primary open-angle glaucoma.

  10. Feasibility of perfusion cardiovascular magnetic resonance in paediatric patients

    Directory of Open Access Journals (Sweden)

    Kellenberger Christian

    2009-01-01

    Full Text Available Abstract Aims As coronary artery disease may also occur during childhood in some specific conditions, we sought to assess the feasibility and accuracy of perfusion cardiovascular magnetic resonance (CMR in paediatric patients. Methods and results First-pass perfusion CMR studies were performed under pharmacological stress with adenosine and by using a hybrid echo-planar pulse sequence with slice-selective saturation recovery preparation. Fifty-six perfusion CMR examinations were performed in 47 patients. The median age was 12 years (1 month-18 years, and weight 42.8 kg (2.6-82 kg. General anaesthesia was required in 18 patients. Mean examination time was 67 ± 19 min. Diagnostic image quality was obtained in 54/56 examinations. In 23 cases the acquisition parameters were adapted to patient's size. Perfusion CMR was abnormal in 16 examinations. The perfusion defects affected the territory of the left anterior descending coronary artery in 11, of the right coronary artery in 3, and of the circumflex coronary artery in 2 cases. Compared to coronary angiography, perfusion CMR showed a sensitivity of 87% (CI 52-97% and a specificity of 95% (CI 79-99%. Conclusion In children, perfusion CMR is feasible and accurate. In very young children (less than 1 year old, diagnostic image quality may be limited.

  11. The Neural Support Vector Machine

    NARCIS (Netherlands)

    Wiering, Marco; van der Ree, Michiel; Embrechts, Mark; Stollenga, Marijn; Meijster, Arnold; Nolte, A; Schomaker, Lambertus

    2013-01-01

    This paper describes a new machine learning algorithm for regression and dimensionality reduction tasks. The Neural Support Vector Machine (NSVM) is a hybrid learning algorithm consisting of neural networks and support vector machines (SVMs). The output of the NSVM is given by SVMs that take a

  12. The Neural Support Vector Machine

    NARCIS (Netherlands)

    Wiering, Marco; van der Ree, Michiel; Embrechts, Mark; Stollenga, Marijn; Meijster, Arnold; Nolte, A; Schomaker, Lambertus

    2013-01-01

    This paper describes a new machine learning algorithm for regression and dimensionality reduction tasks. The Neural Support Vector Machine (NSVM) is a hybrid learning algorithm consisting of neural networks and support vector machines (SVMs). The output of the NSVM is given by SVMs that take a centr

  13. Ventilation-perfusion-chest radiography match is less likely to represent pulmonary embolism if perfusion is decreased rather than absent.

    Science.gov (United States)

    Kim, C K; Worsley, D F; Alavi, A

    2000-09-01

    The authors' goal was to determine whether the prevalence of pulmonary embolism in patients with matching ventilation-perfusion (V-Q) defects and chest radiographic opacities differs depending on the degree of perfusion deficit (absent versus decreased). The authors performed a retrospective analysis of the data obtained from the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study. In 233 patients, angiograms were of diagnostic quality for 275 lung zones that showed matching V-Q defects and chest radiographic opacities (triple matches). Of these, V-Q scans and chest radiographs from 217 patients with triple matches in 255 lung zones were retrieved and reviewed. Areas corresponding to chest radiographic opacities were scored as having either decreased perfusion or absent perfusion by consensus. Information regarding the presence or absence of pulmonary embolism in corresponding lung zones was obtained from the PIOPED database. The overall prevalence of pulmonary embolism in all lung zones with triple matches was 27% (69 of 255). Of the 255 areas of triple matches, the perfusion was decreased in 153 (60%) and absent in 102 (40%). The prevalence of pulmonary embolism in areas of triple matches with decreased perfusion and triple matches with absent perfusion was 13% (20 of 153) and 48% (49 of 102), respectively (P = 0.0001 by the chi-square test). When these were divided further by lung zones, triple matches with decreased perfusion and triple matches with absent perfusion in the upper-middle lung zone were associated with a prevalence of 0% (O of 44), and 25% (9 of 36), respectively. The prevalence of pulmonary embolism in areas of triple matches with decreased perfusion and triple matches with absent perfusion in the lower lung zone was 18% (20 of 109), and 61% (40 of 66), respectively. A V-Q/chest radiographic match is less likely to represent pulmonary embolism if perfusion is decreased rather than absent. The overall prevalence of pulmonary

  14. ATST telescope mount: telescope of machine tool

    Science.gov (United States)

    Jeffers, Paul; Stolz, Günter; Bonomi, Giovanni; Dreyer, Oliver; Kärcher, Hans

    2012-09-01

    The Advanced Technology Solar Telescope (ATST) will be the largest solar telescope in the world, and will be able to provide the sharpest views ever taken of the solar surface. The telescope has a 4m aperture primary mirror, however due to the off axis nature of the optical layout, the telescope mount has proportions similar to an 8 meter class telescope. The technology normally used in this class of telescope is well understood in the telescope community and has been successfully implemented in numerous projects. The world of large machine tools has developed in a separate realm with similar levels of performance requirement but different boundary conditions. In addition the competitive nature of private industry has encouraged development and usage of more cost effective solutions both in initial capital cost and thru-life operating cost. Telescope mounts move relatively slowly with requirements for high stability under external environmental influences such as wind buffeting. Large machine tools operate under high speed requirements coupled with high application of force through the machine but with little or no external environmental influences. The benefits of these parallel development paths and the ATST system requirements are being combined in the ATST Telescope Mount Assembly (TMA). The process of balancing the system requirements with new technologies is based on the experience of the ATST project team, Ingersoll Machine Tools who are the main contractor for the TMA and MT Mechatronics who are their design subcontractors. This paper highlights a number of these proven technologies from the commercially driven machine tool world that are being introduced to the TMA design. Also the challenges of integrating and ensuring that the differences in application requirements are accounted for in the design are discussed.

  15. Perfusion-related stimuli for compensatory lung growth following pneumonectomy.

    Science.gov (United States)

    Dane, D Merrill; Yilmaz, Cuneyt; Gyawali, Dipendra; Iyer, Roshni; Ravikumar, Priya; Estrera, Aaron S; Hsia, Connie C W

    2016-07-01

    Following pneumonectomy (PNX), two separate mechanical forces act on the remaining lung: parenchymal stress caused by lung expansion, and microvascular distension and shear caused by increased perfusion. We previously showed that parenchymal stress and strain explain approximately one-half of overall compensation; the remainder was presumptively attributed to perfusion-related factors. In this study, we directly tested the hypothesis that perturbation of regional pulmonary perfusion modulates post-PNX lung growth. Adult canines underwent banding of the pulmonary artery (PAB) to the left caudal (LCa) lobe, which caused a reduction in basal perfusion to LCa lobe without preventing the subsequent increase in its perfusion following right PNX while simultaneously exaggerating the post-PNX increase in perfusion to the unbanded lobes, thereby creating differential perfusion changes between banded and unbanded lobes. Control animals underwent sham pulmonary artery banding followed by right PNX. Pulmonary function, regional pulmonary perfusion, and high-resolution computed tomography of the chest were analyzed pre-PNX and 3-mo post-PNX. Terminally, the remaining lobes were fixed for detailed morphometric analysis. Results were compared with corresponding lobes in two control (Sham banding and normal unoperated) groups. PAB impaired the indices of post-PNX extravascular alveolar tissue growth by up to 50% in all remaining lobes. PAB enhanced the expected post-PNX increase in alveolar capillary formation, measured by the prevalence of double-capillary profiles, in both unbanded and banded lobes. We conclude that perfusion distribution provides major stimuli for post-PNX compensatory lung growth independent of the stimuli provided by lung expansion and parenchymal stress and strain.

  16. PET imaging of cerebral perfusion and oxygen metabolism in stroke

    Energy Technology Data Exchange (ETDEWEB)

    Pointon, O.; Yasaka, M.; Berlangieri, S.U.; Newton, M.R.; Thomas, D.L.; Chan, C.G.; Egan, G.F.; Tochon-Danguy, H.J.; O``Keefe, G.; Donnan, G.A.; McKay, W.J. [Austin Hospital, Melbourne, VIC (Australia). Centre for PET and Depts of Nuclear Medicine and Neurology

    1998-03-01

    Full text: Stroke remains a devastating clinical event with few therapeutic options. In patients with acute stroke, we studied the cerebral perfusion and metabolic patterns with {sup 15}O-CO{sub 2} or H{sub 2}O and {sup 15}O-O{sub 2} positron emission tomography and correlated these findings to the clinical background. Forty three patients underwent 45 studies 0-23 days post-stroke (mean 7 days). Fifteen patients showed luxury perfusion (Group A), 10 had matched low perfusion and metabolism (B) and 3 showed mixed pattern including an area of misery perfusion (C). Seventeen showed no relevant abnormality (D) and there were no examples of isolated misery perfusion. Twelve of the 15 in Group A had either haemorrhagic transformation on CT, re-opening on angiography, or a cardioembolic mechanism. In contrast only 5/10 in Group B, 0/3 in Group C and 2/17 in Group D had these features. Although 7/10 in group B had moderate or large size infarcts on CT the incidence of haemorrhagic transformation was low (2/10) and significant carotid stenoses were more common in those studied (5/8) compared with the other groups. Misery perfusion was not seen beyond five days. Thus, luxury perfusion seems to be related to a cardio-embolic mechanism or reperfusion. Matched low perfusion and metabolism was associated with a low rate of haemorrhagic transformation despite a high incidence of moderate to large size infarcts. Misery perfusion is an early phenomenon in the evolution of ischaemic stroke.

  17. CT Perfusion of the Liver: Principles and Applications in Oncology

    Science.gov (United States)

    Kim, Se Hyung; Kamaya, Aya

    2014-01-01

    With the introduction of molecularly targeted chemotherapeutics, there is an increasing need for defining new response criteria for therapeutic success because use of morphologic imaging alone may not fully assess tumor response. Computed tomographic (CT) perfusion imaging of the liver provides functional information about the microcirculation of normal parenchyma and focal liver lesions and is a promising technique for assessing the efficacy of various anticancer treatments. CT perfusion also shows promising results for diagnosing primary or metastatic tumors, for predicting early response to anticancer treatments, and for monitoring tumor recurrence after therapy. Many of the limitations of early CT perfusion studies performed in the liver, such as limited coverage, motion artifacts, and high radiation dose of CT, are being addressed by recent technical advances. These include a wide area detector with or without volumetric spiral or shuttle modes, motion correction algorithms, and new CT reconstruction technologies such as iterative algorithms. Although several issues related to perfusion imaging—such as paucity of large multicenter trials, limited accessibility of perfusion software, and lack of standardization in methods—remain unsolved, CT perfusion has now reached technical maturity, allowing for its use in assessing tumor vascularity in larger-scale prospective clinical trials. In this review, basic principles, current acquisition protocols, and pharmacokinetic models used for CT perfusion imaging of the liver are described. Various oncologic applications of CT perfusion of the liver are discussed and current challenges, as well as possible solutions, for CT perfusion are presented. © RSNA, 2014 Online supplemental material is available for this article. PMID:25058132

  18. Industrial Inspection with Open Eyes: Advance with Machine Vision Technology

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zheng; Ukida, H.; Niel, Kurt; Ramuhalli, Pradeep

    2015-10-01

    Machine vision systems have evolved significantly with the technology advances to tackle the challenges from modern manufacturing industry. A wide range of industrial inspection applications for quality control are benefiting from visual information captured by different types of cameras variously configured in a machine vision system. This chapter screens the state of the art in machine vision technologies in the light of hardware, software tools, and major algorithm advances for industrial inspection. The inspection beyond visual spectrum offers a significant complementary to the visual inspection. The combination with multiple technologies makes it possible for the inspection to achieve a better performance and efficiency in varied applications. The diversity of the applications demonstrates the great potential of machine vision systems for industry.

  19. State machine analysis of sensor data from dynamic processes

    Energy Technology Data Exchange (ETDEWEB)

    Cook, William R.; Brabson, John M.; Deland, Sharon M.

    2003-12-23

    A state machine model analyzes sensor data from dynamic processes at a facility to identify the actual processes that were performed at the facility during a period of interest for the purpose of remote facility inspection. An inspector can further input the expected operations into the state machine model and compare the expected, or declared, processes to the actual processes to identify undeclared processes at the facility. The state machine analysis enables the generation of knowledge about the state of the facility at all levels, from location of physical objects to complex operational concepts. Therefore, the state machine method and apparatus may benefit any agency or business with sensored facilities that stores or manipulates expensive, dangerous, or controlled materials or information.

  20. Development of Web-based Virtual Training Environment for Machining

    Science.gov (United States)

    Yang, Zhixin; Wong, S. F.

    2010-05-01

    With the booming in the manufacturing sector of shoe, garments and toy, etc. in pearl region, training the usage of various facilities and design the facility layout become crucial for the success of industry companies. There is evidence that the use of virtual training may provide benefits in improving the effect of learning and reducing risk in the physical work environment. This paper proposed an advanced web-based training environment that could demonstrate the usage of a CNC machine in terms of working condition and parameters selection. The developed virtual environment could provide training at junior level and advanced level. Junior level training is to explain machining knowledge including safety factors, machine parameters (ex. material, speed, feed rate). Advanced level training enables interactive programming of NG coding and effect simulation. Operation sequence was used to assist the user to choose the appropriate machining condition. Several case studies were also carried out with animation of milling and turning operations.

  1. Prediction of Machine Tool Condition Using Support Vector Machine

    Science.gov (United States)

    Wang, Peigong; Meng, Qingfeng; Zhao, Jian; Li, Junjie; Wang, Xiufeng

    2011-07-01

    Condition monitoring and predicting of CNC machine tools are investigated in this paper. Considering the CNC machine tools are often small numbers of samples, a condition predicting method for CNC machine tools based on support vector machines (SVMs) is proposed, then one-step and multi-step condition prediction models are constructed. The support vector machines prediction models are used to predict the trends of working condition of a certain type of CNC worm wheel and gear grinding machine by applying sequence data of vibration signal, which is collected during machine processing. And the relationship between different eigenvalue in CNC vibration signal and machining quality is discussed. The test result shows that the trend of vibration signal Peak-to-peak value in surface normal direction is most relevant to the trend of surface roughness value. In trends prediction of working condition, support vector machine has higher prediction accuracy both in the short term ('One-step') and long term (multi-step) prediction compared to autoregressive (AR) model and the RBF neural network. Experimental results show that it is feasible to apply support vector machine to CNC machine tool condition prediction.

  2. Learning Simple Machines through Cross-Age Collaborations

    Science.gov (United States)

    Lancor, Rachael; Schiebel, Amy

    2008-01-01

    In this project, introductory college physics students (noneducation majors) were asked to teach simple machines to a class of second graders. This nontraditional activity proved to be a successful way to encourage college students to think critically about physics and how it applied to their everyday lives. The noneducation majors benefited by…

  3. Learning Simple Machines through Cross-Age Collaborations

    Science.gov (United States)

    Lancor, Rachael; Schiebel, Amy

    2008-01-01

    In this project, introductory college physics students (noneducation majors) were asked to teach simple machines to a class of second graders. This nontraditional activity proved to be a successful way to encourage college students to think critically about physics and how it applied to their everyday lives. The noneducation majors benefited by…

  4. Using example-based machine translation to translate DVD subtitles

    DEFF Research Database (Denmark)

    Flanagan, Marian

    Audiovisual Translation (AVT), and in particular subtitling, has been recognised as an area that could potentially benefit from the introduction of machine translation (followed by post-editing). In recent years the demands on subtitlers have increased, while the payment to subtitlers and time al...

  5. Improved perfusion quantification in FAIR imaging by offset correction

    DEFF Research Database (Denmark)

    Sidaros, Karam; Andersen, Irene K.; Gesmar, Henrik

    2001-01-01

    Perfusion quantification using pulsed arterial spin labeling has been shown to be sensitive to the RF pulse slice profiles. Therefore, in Flow-sensitive Alternating-Inversion Recovery (FAIR) imaging the slice selective (ss) inversion slab is usually three to four times thicker than the imaging...... slice. However, this reduces perfusion sensitivity due to the increased transit delay of the incoming blood with unperturbed spins. In the present article, the dependence of the magnetization on the RF pulse slice profiles is inspected both theoretically and experimentally. A perfusion quantification...

  6. Dual-energy perfusion-CT of pancreatic adenocarcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Klauß, M., E-mail: miriam.klauss@med.uni-heidelberg.de [University of Heidelberg, Dpt. of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 110, 69120 Heidelberg (Germany); Stiller, W., E-mail: wolfram.stiller@med.uni-heidelberg.de [University of Heidelberg, Dpt. of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 110, 69120 Heidelberg (Germany); Pahn, G., E-mail: gregor.pahn@med.uni-heidelberg.de [University of Heidelberg, Dpt. of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 110, 69120 Heidelberg (Germany); Fritz, F., E-mail: franzi.fritz@cegug.org [University of Heidelberg, Dpt. of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 110, 69120 Heidelberg (Germany); Kieser, M., E-mail: meinhard.kieser@med.uni-heidelberg.de [University of Heidelberg, Inst. of Medical Biometry and Informatics, Im Neuenheimer Feld 305, 69120 Heidelberg (Germany); Werner, J., E-mail: jens.werner@med.uni-heidelberg.de [University of Heidelberg, Dpt. of Surgery, Im Neuenheimer Feld 110, 69120 Heidelberg (Germany); Kauczor, H.U., E-mail: hans-ulrich.kauczor@med.uni-heidelberg.de [University of Heidelberg, Dpt. of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 110, 69120 Heidelberg (Germany); Grenacher, L., E-mail: lars.grenacher@med.uni-heidelberg.de [University of Heidelberg, Dpt. of Diagnostic and Interventional Radiology, Im Neuenheimer Feld 110, 69120 Heidelberg (Germany)

    2013-02-15

    Purpose: To evaluate the feasibility of dual-energy CT (DECT)-perfusion of pancreatic carcinomas for assessing the differences in perfusion, permeability and blood volume of healthy pancreatic tissue and histopathologically confirmed solid pancreatic carcinoma. Materials and methods: 24 patients with histologically proven pancreatic carcinoma were examined prospectively with a 64-slice dual source CT using a dynamic sequence of 34 dual-energy (DE) acquisitions every 1.5 s (80 ml of iodinated contrast material, 370 mg/ml, flow rate 5 ml/s). 80 kV{sub p}, 140 kV{sub p}, and weighted average (linearly blended M0.3) 120 kV{sub p}-equivalent dual-energy perfusion image data sets were evaluated with a body-perfusion CT tool (Body-PCT, Siemens Medical Solutions, Erlangen, Germany) for estimating perfusion, permeability, and blood volume values. Color-coded parameter maps were generated. Results: In all 24 patients dual-energy CT-perfusion was. All carcinomas could be identified in the color-coded perfusion maps. Calculated perfusion, permeability and blood volume values were significantly lower in pancreatic carcinomas compared to healthy pancreatic tissue. Weighted average 120 kV{sub p}-equivalent perfusion-, permeability- and blood volume-values determined from DE image data were 0.27 ± 0.04 min{sup −1} vs. 0.91 ± 0.04 min{sup −1} (p < 0.0001), 0.5 ± 0.07 *0.5 min{sup −1} vs. 0.67 ± 0.05 *0.5 min{sup −1} (p = 0.06) and 0.49 ± 0.07 min{sup −1} vs. 1.28 ± 0.11 min{sup −1} (p < 0.0001). Compared with 80 and 140 kV{sub p} the standard deviations of the kV{sub p}120 kV{sub p}-equivalent values were manifestly smaller. Conclusion: Dual-energy CT-perfusion of the pancreas is feasible. The use of DECT improves the accuracy of CT-perfusion of the pancreas by fully exploiting the advantages of enhanced iodine contrast at 80 kV{sub p} in combination with the noise reduction at 140 kV{sub p}. Therefore using dual-energy perfusion data could improve the delineation

  7. CT myocardial perfusion imaging: current status and future directions.

    Science.gov (United States)

    Williams, M C; Newby, D E

    2016-08-01

    Computed tomography (CT) imaging of the heart has advanced rapidly, and it is now possible to perform a comprehensive assessment at a low radiation dose. CT myocardial perfusion imaging can provide additive information to CT coronary angiography, and is particularly useful in patients with heavily calcified coronary arteries or coronary artery stents. A number of protocols are now available for CT myocardial perfusion including static, dynamic, and dual-energy techniques. This review will discuss the current status of CT myocardial perfusion imaging, its clinical application, and future directions for this technology.

  8. Role of magnetic resonance perfusion studies in moyamoya disease

    Directory of Open Access Journals (Sweden)

    Khanna Paritosh

    2004-04-01

    Full Text Available Moyamoya disease, Japanese for ′puff of smoke′, is a rare disease that presents most commonly with recurrent TIAs (transient ischemic attacks / stroke in childhood. Ischemic symptoms in patients with moyamoya disease are usually due to hemodynamically-mediated perfusion failure. Identification of abnormal tissue perfusion is an important aspect of the evaluation of these patients. We present the radiological features including the Magnetic Resonance (MR Perfusion findings illustrating the hemodynamic changes of cerebral ischemia in a case of moyamoya disease.

  9. A Boltzmann machine for the organization of intelligent machines

    Science.gov (United States)

    Moed, Michael C.; Saridis, George N.

    1989-01-01

    In the present technological society, there is a major need to build machines that would execute intelligent tasks operating in uncertain environments with minimum interaction with a human operator. Although some designers have built smart robots, utilizing heuristic ideas, there is no systematic approach to design such machines in an engineering manner. Recently, cross-disciplinary research from the fields of computers, systems AI and information theory has served to set the foundations of the emerging area of the design of intelligent machines. Since 1977 Saridis has been developing an approach, defined as Hierarchical Intelligent Control, designed to organize, coordinate and execute anthropomorphic tasks by a machine with minimum interaction with a human operator. This approach utilizes analytical (probabilistic) models to describe and control the various functions of the intelligent machine structured by the intuitively defined principle of Increasing Precision with Decreasing Intelligence (IPDI) (Saridis 1979). This principle, even though resembles the managerial structure of organizational systems (Levis 1988), has been derived on an analytic basis by Saridis (1988). The purpose is to derive analytically a Boltzmann machine suitable for optimal connection of nodes in a neural net (Fahlman, Hinton, Sejnowski, 1985). Then this machine will serve to search for the optimal design of the organization level of an intelligent machine. In order to accomplish this, some mathematical theory of the intelligent machines will be first outlined. Then some definitions of the variables associated with the principle, like machine intelligence, machine knowledge, and precision will be made (Saridis, Valavanis 1988). Then a procedure to establish the Boltzmann machine on an analytic basis will be presented and illustrated by an example in designing the organization level of an Intelligent Machine. A new search technique, the Modified Genetic Algorithm, is presented and proved

  10. Development of an Ex Vivo, Beating Heart Model for CT Myocardial Perfusion

    NARCIS (Netherlands)

    Pelgrim, Gert Jan; Das, Marco; Haberland, Ulrike; Slump, Cees; Handayani, Astri; van Tuijl, Sjoerd; Stijnen, Marco; Klotz, Ernst; Oudkerk, Matthijs; Wildberger, Joachim E.; Vliegenthart, Rozemarijn

    2015-01-01

    Objective. To test the feasibility of a CT-compatible, ex vivo, perfused porcine heart model for myocardial perfusion CT imaging. Methods. One porcine heart was perfused according to Langendorff. Dynamic perfusion scanning was performed with a second-generation dual source CT scanner. Circulatory pa

  11. Dynamic perfusion CT: Optimizing the temporal resolution for the calculation of perfusion CT parameters in stroke patients

    Energy Technology Data Exchange (ETDEWEB)

    Kaemena, Andreas [Department of Radiology, Charite-Medical University Berlin, Augustenburger Platz 1, D-13353 Berlin (Germany)], E-mail: andreas.kaemena@charite.de; Streitparth, Florian; Grieser, Christian; Lehmkuhl, Lukas [Department of Radiology, Charite-Medical University Berlin, Augustenburger Platz 1, D-13353 Berlin (Germany); Jamil, Basil [Department of Radiotherapy, Charite-Medical University Berlin, Schumannstr. 20/21, D-10117 Berlin (Germany); Wojtal, Katarzyna; Ricke, Jens; Pech, Maciej [Department of Radiology, Charite-Medical University Berlin, Augustenburger Platz 1, D-13353 Berlin (Germany)

    2007-10-15

    Purpose: To assess the influence of different temporal sampling rates on the accuracy of the results from cerebral perfusion CTs in patients with an acute ischemic stroke. Material and methods: Thirty consecutive patients with acute stroke symptoms received a dynamic perfusion CT (LightSpeed 16, GE). Forty millilitres of iomeprol (Imeron 400) were administered at an injection rate of 4 ml/s. After a scan delay of 7 s, two adjacent 10 mm slices at 80 kV and 190 mA were acquired in a cine mode technique with a cine duration of 49 s. Parametric maps for the blood flow (BF), blood volume (BV) and mean transit time (MTT) were calculated for temporal sampling intervals of 0.5, 1, 2, 3 and 4 s using GE's Perfusion 3 software package. In addition to the quantitative ROI data analysis, a visual perfusion map analysis was performed. Results: The perfusion analysis proved to be technically feasible with all patients. The calculated perfusion values revealed significant differences with regard to the BF, BV and MTT, depending on the employed temporal resolution. The perfusion contrast between ischemic lesions and healthy brain tissue decreased continuously at the lower temporal resolutions. The visual analysis revealed that ischemic lesions were best depicted with sampling intervals of 0.5 and 1 s. Conclusion: We recommend a temporal scan resolution of two images per second for the best detection and depiction of ischemic areas.

  12. Engineering molecular machines

    Science.gov (United States)

    Erman, Burak

    2016-04-01

    Biological molecular motors use chemical energy, mostly in the form of ATP hydrolysis, and convert it to mechanical energy. Correlated thermal fluctuations are essential for the function of a molecular machine and it is the hydrolysis of ATP that modifies the correlated fluctuations of the system. Correlations are consequences of the molecular architecture of the protein. The idea that synthetic molecular machines may be constructed by designing the proper molecular architecture is challenging. In their paper, Sarkar et al (2016 New J. Phys. 18 043006) propose a synthetic molecular motor based on the coarse grained elastic network model of proteins and show by numerical simulations that motor function is realized, ranging from deterministic to thermal, depending on temperature. This work opens up a new range of possibilities of molecular architecture based engine design.

  13. Boosting Support Vector Machines

    Directory of Open Access Journals (Sweden)

    Elkin Eduardo García Díaz

    2006-11-01

    Full Text Available En este artículo, se presenta un algoritmo de clasificación binaria basado en Support Vector Machines (Máquinas de Vectores de Soporte que combinado apropiadamente con técnicas de Boosting consigue un mejor desempeño en cuanto a tiempo de entrenamiento y conserva características similares de generalización con un modelo de igual complejidad pero de representación más compacta./ In this paper we present an algorithm of binary classification based on Support Vector Machines. It is combined with a modified Boosting algorithm. It run faster than the original SVM algorithm with a similar generalization error and equal complexity model but it has more compact representation.

  14. Quo vadis, Intelligent Machine?

    Directory of Open Access Journals (Sweden)

    Rosemarie Velik

    2010-09-01

    Full Text Available Artificial Intelligence (AI is a branch of computer science concerned with making computers behave like humans. At least this was the original idea. However, it turned out that this is no task easy to be solved. This article aims to give a comprehensible review on the last 60 years of artificial intelligence taking a philosophical viewpoint. It is outlined what happened so far in AI, what is currently going on in this research area, and what can be expected in future. The goal is to mediate an understanding for the developments and changes in thinking in course of time about how to achieve machine intelligence. The clear message is that AI has to join forces with neuroscience and other brain disciplines in order to make a step towards the development of truly intelligent machines.

  15. Introduction to Machine Protection

    CERN Document Server

    Schmidt, R

    2016-01-01

    Protection of accelerator equipment is as old as accelerator technology and was for many years related to high-power equipment. Examples are the protection of powering equipment from overheating (magnets, power converters, high-current cables), of superconducting magnets from damage after a quench and of klystrons. The protection of equipment from beam accidents is more recent, although there was one paper that discussed beam-induced damage for the SLAC linac (Stanford Linear Accelerator Center) as early as in 1967. It is related to the increasing beam power of high-power proton accelerators, to the emission of synchrotron light by electron-positron accelerators and to the increase of energy stored in the beam. Designing a machine protection system requires an excellent understanding of accelerator physics and operation to anticipate possible failures that could lead to damage. Machine protection includes beam and equipment monitoring, a system to safely stop beam operation (e.g. dumping the beam or stopping ...

  16. Technological requirements of profile machining

    Institute of Scientific and Technical Information of China (English)

    PARK Sangchul; CHUNG Yunchan

    2006-01-01

    The term ‘profile machining’is used to refer to the milling of vertical surfaces described by profile curves. Profile machining requires higher precision (1/1000 mm) than regular 3D machining (1/100 mm) with the erosion of sharp vertices should being especially avoided. Although, profile machining is very essential for making trimming and flangedies, it seldom brought into focus. This paper addresses the technological requirements of profile machining including machining width and depth control,minimizing toolware, and protecting sharp vertices. Issues of controller alarms are also addressed.

  17. Machining fiber-reinforced composites

    Science.gov (United States)

    Komanduri, Ranga

    1993-04-01

    Compared to high tool wear and high costs of tooling of fiber-reinforced composites (FRCs), noncontact material-removal processes offer attractive alternative. Noncontact machining methods can also minimize dust, noise, and extensive plastic deformation and consequent heat generation associated with conventional machining of FRCs, espacially those with an epoxy matrix. The paper describes the principles involved in and the details of machining of FRCs by laser machining, water jet-cutting and abrasive water jet-cutting, and electrical discharge machining of composites, as well as the limitations of each method.

  18. Future database machine architectures

    OpenAIRE

    Hsiao, David K.

    1984-01-01

    There are many software database management systems available on many general-purpose computers ranging from micros to super-mainframes. Database machines as backened computers can offload the database management work from the mainframe so that we can retain the same mainframe longer. However, the database backend must also demonstrate lower cost, higher performance, and newer functionality. Some of the fundamental architecture issues in the design of high-performance and great-capacity datab...

  19. Machine Learning at Scale

    OpenAIRE

    Izrailev, Sergei; Stanley, Jeremy M.

    2014-01-01

    It takes skill to build a meaningful predictive model even with the abundance of implementations of modern machine learning algorithms and readily available computing resources. Building a model becomes challenging if hundreds of terabytes of data need to be processed to produce the training data set. In a digital advertising technology setting, we are faced with the need to build thousands of such models that predict user behavior and power advertising campaigns in a 24/7 chaotic real-time p...

  20. Cost of photochemical machining

    OpenAIRE

    Roy, Rajkumar; Allen, David; Zamora, Oscar

    2004-01-01

    Photochemical machining (PCM), also known as photoetching, photofabrication or photochemical milling, is a non-traditional manufacturing method based on the combination of photoresist imaging and chemical etching. PCM uses techniques similar to those employed for the production of printed circuit boards and silicon integrated circuits. The PCM industry plays a valuable worldwide role in the production of metal precision parts and decorative items. Parts produced by PCM are t...

  1. Austempered Ductile Iron Machining

    Science.gov (United States)

    Pilc, Jozef; Šajgalík, Michal; Holubják, Jozef; Piešová, Marianna; Zaušková, Lucia; Babík, Ondrej; Kuždák, Viktor; Rákoci, Jozef

    2015-12-01

    This article deals with the machining of cast iron. In industrial practice, Austempered Ductile Iron began to be used relatively recently. ADI is ductile iron that has gone through austempering to get improved properties, among which we can include strength, wear resistance or noise damping. This specific material is defined also by other properties, such as high elasticity, ductility and endurance against tenigue, which are the properties, that considerably make the tooling characteristic worse.

  2. Quantum Virtual Machine (QVM)

    Energy Technology Data Exchange (ETDEWEB)

    2016-11-18

    There is a lack of state-of-the-art HPC simulation tools for simulating general quantum computing. Furthermore, there are no real software tools that integrate current quantum computers into existing classical HPC workflows. This product, the Quantum Virtual Machine (QVM), solves this problem by providing an extensible framework for pluggable virtual, or physical, quantum processing units (QPUs). It enables the execution of low level quantum assembly codes and returns the results of such executions.

  3. Agent Based Computing Machine

    Science.gov (United States)

    2005-12-09

    be used in Phase 2 to accomplish the following enhancements. Due to the speed and support of MPI for C/C++ on Beowulf clusters , these languages could...1.7 ABC Machine Formal Definition 24 1.8 Computational Analysis 31 1.9 Programming Concepts 34 1.10 Cluster Mapping 38 1.11 Phase 1 Results 43 2...options for hardware implementation are explored including an emulation with a high performance cluster , a high performance silicon chip and the

  4. Magnetic Electrochemical Finishing Machining

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    How to improve the finishing efficiency and surface roughness have been all along the objective of research in electrochemical polishing. However, the research activity, i.e. during electrochemical polishing, directly introduce the magnetic field to study how the magnetic field influences on the finishing efficiency, quality and the electrochemical process in the field of finishing machining technology, is insufficient. When introducing additional magnetic field in the traditional electrochemical pol...

  5. FMS precision machining

    Energy Technology Data Exchange (ETDEWEB)

    Burnham, M.W.

    1980-01-01

    In evaluating the technical obstacles and accuracy limits to producing a Precision Flexible Manufacturing System, a current system is subjected to an error budget analysis. It is noted that to make complex part geometries with tolerances in the lower thousandths range, machining to tenths is required for process control. Actual parts made to tenths are illustrated, along with a discussion of the requirements for automation and for process control.

  6. Machine on Trial

    Science.gov (United States)

    2012-06-01

    front of the Judge, how did we come to justify the ethical use of such a machine? The Judge called for a recess so that he could further educate ...commerce, where money would change hands, or for the purposes of controlling critical systems.”29 The initial group that set up the ARPANET did not... EBook of Fundamental Principals of the Metaphysic of Morals, May, 2004 [ EBook #5682 translated by Thomas Kingsmill Abbott, 12. http://manybooks.net

  7. Quantification of MRI measured myocardial perfusion reserve in healthy humans: a comparison with positron emission tomography

    DEFF Research Database (Denmark)

    Fritz-Hansen, Thomas; Hove, Jens D; Kofoed, Klaus F

    2008-01-01

    PURPOSE: To validate a noninvasive quantitative MRI technique, the K(i) perfusion method, for myocardial perfusion in humans using (13)N-ammonia PET as a reference method. MATERIALS AND METHODS: Ten healthy males (64 +/- 8 years) were examined with combined PET and MRI perfusion imaging at rest...... and during stress induced by dipyridamole in order to determine the myocardial perfusion reserve. Myocardial and blood time concentration curves obtained by Gd-DTPA-enhanced MRI and (13)N-ammonia PET were fitted by a two-compartment perfusion model. RESULTS: Mean perfusion values (+/-SD) derived from the MRI...... as a quantitative marker for myocardial perfusion in healthy humans....

  8. Electrochemical Discharge Machining Process

    Directory of Open Access Journals (Sweden)

    Anjali V. Kulkarni

    2007-09-01

    Full Text Available Electrochemical discharge machining process is evolving as a promising micromachiningprocess. The experimental investigations in the present work substantiate this trend. In the presentwork, in situ, synchronised, transient temperature and current measurements have been carriedout. The need for the transient measurements arose due to the time-varying nature of the dischargeformation and time varying circuit current. Synchronised and transient measurements revealedthe discrete nature of the process. It also helped in formulating the basic mechanism for thedischarge formation and the material removal in the process. Temperature profile on workpieceand in electrochemical discharge machining cell is experimentally measured using pyrometer,and two varieties of K-type thermocouples. Surface topography of the discharge-affected zoneson the workpiece has been carried out using scanning electron microscope. Measurements andsurface topographical studies reveal the potential use of this process for machining in micronregime. With careful experimental set-up design, suitable supply voltage and its polarity, theprocess can be applied for both micromachining and micro-deposition. It can be extended formachining and or deposition of wide range of materials.

  9. Introduction: Minds, Bodies, Machines

    Directory of Open Access Journals (Sweden)

    Deirdre Coleman

    2008-10-01

    Full Text Available This issue of 19 brings together a selection of essays from an interdisciplinary conference on 'Minds, Bodies, Machines' convened last year by Birkbeck's Centre for Nineteenth-Century Studies, University of London, in partnership with the English programme, University of Melbourne and software developers Constraint Technologies International (CTI. The conference explored the relationship between minds, bodies and machines in the long nineteenth century, with a view to understanding the history of our technology-driven, post-human visions. It is in the nineteenth century that the relationship between the human and the machine under post-industrial capitalism becomes a pervasive theme. From Blake on the mills of the mind by which we are enslaved, to Carlyle's and Arnold's denunciation of the machinery of modern life, from Dickens's sooty fictional locomotive Mr Pancks, who 'snorted and sniffed and puffed and blew, like a little labouring steam-engine', and 'shot out […]cinders of principles, as if it were done by mechanical revolvency', to the alienated historical body of the late-nineteenth-century factory worker under Taylorization, whose movements and gestures were timed, regulated and rationalised to maximize efficiency; we find a cultural preoccupation with the mechanisation of the nineteenth-century human body that uncannily resonates with modern dreams and anxieties around technologies of the human.

  10. Behind the machines

    CERN Document Server

    Laëtitia Pedroso

    2010-01-01

    One of the first things we think about when someone mentions physics is the machines. But behind the machines, there are the men and women who design, build and operate them. In an exhibition at the Thinktank planetarium’s art gallery in Birmingham (UK), Claudia Marcelloni and her husband Neal Hartman—she is a photographer and Outreach Officer for ATLAS, while he is an engineer working on the ATLAS pixel detector—explore the human side of scientists.   The exhibition at the Thinktank Planetarium art gallery, Birmingham (UK). It all began two years ago with the publication of Exploring the mystery of matter, a book about ATLAS. “A Norwegian physicist friend, Heidi Sandaker, saw my photographs and suggested that I display them in a museum. I thought this was an interesting idea, except that the photos consisted entirely of depictions of machinery, with human beings completely absent. For me, showing the people who are behind the machines and the fascination ...

  11. Exercise: Benefits of Exercise

    Medline Plus

    Full Text Available ... version of this page please turn Javascript on. Exercise: Benefits of Exercise Health Benefits One of the Healthiest Things You ... activity campaign from the National Institute on Aging. Exercise or Physical Activity? Some people may wonder what ...

  12. Exercise: Benefits of Exercise

    Medline Plus

    Full Text Available ... Exercise: Benefits of Exercise Health Benefits One of the Healthiest Things You Can Do Like most people, ... active on a regular basis is one of the healthiest things you can do for yourself. Studies ...

  13. Medicare Hospice Benefits

    Science.gov (United States)

    CENTERS for MEDICARE & MEDICAID SERVICES Medicare Hospice Benefits This official government booklet includes information about Medicare hospice benefits: Who’s eligible for hospice care What services are included in hospice ...

  14. Benefits of Exercise

    Science.gov (United States)

    ... start slowly, and find ways to fit more physical activity into your life. To get the most benefit, ... the health benefits of exercise? Regular exercise and physical activity may Help you control your weight. Along with ...

  15. Soft computing in machine learning

    CERN Document Server

    Park, Jooyoung; Inoue, Atsushi

    2014-01-01

    As users or consumers are now demanding smarter devices, intelligent systems are revolutionizing by utilizing machine learning. Machine learning as part of intelligent systems is already one of the most critical components in everyday tools ranging from search engines and credit card fraud detection to stock market analysis. You can train machines to perform some things, so that they can automatically detect, diagnose, and solve a variety of problems. The intelligent systems have made rapid progress in developing the state of the art in machine learning based on smart and deep perception. Using machine learning, the intelligent systems make widely applications in automated speech recognition, natural language processing, medical diagnosis, bioinformatics, and robot locomotion. This book aims at introducing how to treat a substantial amount of data, to teach machines and to improve decision making models. And this book specializes in the developments of advanced intelligent systems through machine learning. It...

  16. Machine Translation Effect on Communication

    DEFF Research Database (Denmark)

    Jensen, Mika Yasuoka; Bjørn, Pernille

    2011-01-01

    Intercultural collaboration facilitated by machine translation has gradually spread in various settings. Still, little is known as for the practice of machine-translation mediated communication. This paper investigates how machine translation affects intercultural communication in practice. Based...... determines communication process largely, our data indicates communication relies more on a dynamic process where participants establish common ground than on reproducibility and grammatical accuracy.......Intercultural collaboration facilitated by machine translation has gradually spread in various settings. Still, little is known as for the practice of machine-translation mediated communication. This paper investigates how machine translation affects intercultural communication in practice. Based...... on communication in which multilingual communication system is applied, we identify four communication types and its’ influences on stakeholders’ communication process, especially focusing on establishment and maintenance of common ground. Different from our expectation that quality of machine translation results...

  17. A Unifying model of perfusion and motion applied to reconstruction of sparsely sampled free-breathing myocardial perfusion MRI

    DEFF Research Database (Denmark)

    Pedersen, Henrik; Ólafsdóttir, Hildur; Larsen, Rasmus

    2010-01-01

    The clinical potential of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is currently limited by respiratory induced motion of the heart. This paper presents a unifying model of perfusion and motion in which respiratory motion becomes an integral part of myocardial perfusion...... quantification. Hence, the need for tedious manual motion correction prior to perfusion quantification is avoided. In addition, we demonstrate that the proposed framework facilitates the process of reconstructing DCEMRI from sparsely sampled data in the presence of respiratory motion. The paper focuses primarily...

  18. Computed tomography angiography and perfusion to assess coronary artery stenosis causing perfusion defects by single photon emission computed tomography

    DEFF Research Database (Denmark)

    Rochitte, Carlos E; George, Richard T; Chen, Marcus Y

    2014-01-01

    AIMS: To evaluate the diagnostic power of integrating the results of computed tomography angiography (CTA) and CT myocardial perfusion (CTP) to identify coronary artery disease (CAD) defined as a flow limiting coronary artery stenosis causing a perfusion defect by single photon emission computed...... tomography (SPECT). METHODS AND RESULTS: We conducted a multicentre study to evaluate the accuracy of integrated CTA-CTP for the identification of patients with flow-limiting CAD defined by ≥50% stenosis by invasive coronary angiography (ICA) with a corresponding perfusion deficit on stress single photon...

  19. Multislice CT brain image registration for perfusion studies

    Science.gov (United States)

    Lin, Zhong Min; Pohlman, Scott; Chandra, Shalabh

    2002-04-01

    During the last several years perfusion CT techniques have been developed as an effective technique for clinically evaluating cerebral hemodynamics. Perfusion CT techniques are capable of measurings functional parameters such as tissue perfusion, blood flow, blood volume, and mean transit time and are commonly used to evaluate stroke patients. However, the quality of functional images of the brain frequently suffers from patient head motion. Because the time window for an effective treatment of stroke patient is narrow, a fast motion correction is required. The purpose of the paper is to present a fast and accurate registration technique for motion correction of multi-slice CT and to demonstrate the effects of the registration on perfusion calculation.

  20. Automatic Characterization of Myocardial Perfusion in Contrast Enhanced MRI

    Science.gov (United States)

    Positano, Vincenzo; Santarelli, Maria Filomena; Landini, Luigi

    2003-12-01

    The use of contrast medium in cardiac MRI allows joining the high-resolution anatomical information provided by standard magnetic resonance with functional information obtained by means of the perfusion of contrast agent in myocardial tissues. The current approach to perfusion MRI characterization is the qualitative one, based on visual inspection of images. Moving to quantitative analysis requires extraction of numerical indices of myocardium perfusion by analysis of time/intensity curves related to the area of interest. The main problem in quantitative image sequence analysis is the heart movement, mainly due to patient respiration. We propose an automatic procedure based on image registration, segmentation of the myocardium, and extraction and analysis of time/intensity curves. The procedure requires a minimal user interaction, is robust with respect to the user input, and allows effective characterization of myocardial perfusion. The algorithm was tested on cardiac MR images acquired from voluntaries and in clinical routine.

  1. Displaying perfusion MRI images as color intensity projections

    CERN Document Server

    Hoefnagels, Friso; Sanchez, Ester; Lagerwaard, Frank J

    2007-01-01

    Dynamic susceptibility-weighted contrast-enhanced (DSC) MRI or perfusion-MRI plays an important role in the non-invasive assessment of tumor vascularity. However, the large number of images provided by the method makes display and interpretation of the results challenging. Current practice is to display the perfusion information as relative cerebral blood volume maps (rCBV). Color intensity projections (CIPs) provides a simple, intuitive display of the perfusion-MRI data so that regional perfusion characteristics are intrinsically integrated into the anatomy structure the T2 images. The ease of use and quick calculation time of CIPs should allow it to be easily integrated into current analysis and interpretation pipelines.

  2. Personal computer aided cerebral perfusion imaging with dynamic CT

    Institute of Scientific and Technical Information of China (English)

    林燕; 高培毅

    2004-01-01

    @@Reports on the clinical implementation of dynamic computerised tomography (CT) perfusion imaging and quantitative measurement have increased dramatically of late.1-8 The advantages of dynamic CT perfusion imaging and quantitative measurement for the diagnosis of acute cerebral infarction have been acknowledged. However, most overseas CT vendors set perfusion imaging software package as an option for graphic workstation at a too high price for domestic practitioners. To foster the domestic implementation and development of this new technology, we have extended the earlier work.1,2 Applying the theory of central volume principle to DICOM 3.0 standard forms of prime CT images, we developed dynamic CT perfusion imaging and quantitative measure-ment programmes for PCs using Visual C+ + in Windows 98 system.

  3. Prematurity and brain perfusion: Arterial spin labeling MRI

    Directory of Open Access Journals (Sweden)

    Domenico Tortora

    2017-01-01

    Conclusions: ASL MRI demonstrated differences in brain perfusion of the basal ganglia between PN and TN. In PN, a positive correlation between CBF and neuromotor outcome was demonstrated in this area.

  4. Decreased myocardial perfusion reserve in diabetic autonomic neuropathy

    DEFF Research Database (Denmark)

    Taskiran, Mustafa; Fritz-Hansen, Thomas; Rasmussen, Verner

    2002-01-01

    The pathophysiological mechanisms responsible for increased cardiovascular mortality in diabetic autonomic neuropathy are unknown. To investigate the effect of autonomic neuropathy on myocardial function, we performed dynamic contrast-enhanced magnetic resonance perfusion imaging during baseline...... conditions and after Dipyridamole-induced vasodilatation in nine type 1 diabetic patients with autonomic neuropathy (AN+), defined by cardiovascular tests, as well as in 10 type 1 diabetic patients without autonomic neuropathy (AN-) and 10 healthy control subjects. Baseline myocardial perfusion index (K...... blood pressure response to Dipyridamole and myocardial perfusion reserve index. We conclude that type 1 diabetic patients with autonomic neuropathy have a decreased myocardial perfusion reserve capacity when challenged with a vasodilatator, a finding that may in part be the pathophysiological substrate...

  5. Associations between muscle perfusion and symptoms in knee osteoarthritis

    DEFF Research Database (Denmark)

    Bandak, E; Boesen, M; Bliddal, H

    2015-01-01

    OBJECTIVE: To investigate the association between muscle perfusion in the peri-articular knee muscles assessed by dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) and symptoms in patients with knee osteoarthritis (KOA). DESIGN: In a cross-sectional setting, muscle perfusion......-MRI and clinical data were analyzed in 94 patients. The typical participant was a woman with a mean age of 65 years, and a body mass index (BMI) of 32 kg/m(2). Reduced multiple regression models analyzing the association between KOOS and DCE-MRI perfusion variables of Total Muscle Volume showed a statistically...... significant association between Nvoxel% and KOOS pain (0.41 (SE 0.14); P = 0.0048). Nvoxel% was defined as the proportion of highly perfused voxels; i.e., the voxels that show an early and rapid increase on the signal intensity vs time curves, reach a plateau state (plateau pattern) and then showing...

  6. Perfusion computed tomography to assist decision making for stroke thrombolysis

    Science.gov (United States)

    Levi, Christopher; Krishnamurthy, Venkatesh; McElduff, Patrick; Miteff, Ferdi; Spratt, Neil J.; Bateman, Grant; Donnan, Geoffrey; Davis, Stephen; Parsons, Mark

    2015-01-01

    The use of perfusion imaging to guide selection of patients for stroke thrombolysis remains controversial because of lack of supportive phase three clinical trial evidence. We aimed to measure the outcomes for patients treated with intravenous recombinant tissue plasminogen activator (rtPA) at a comprehensive stroke care facility where perfusion computed tomography was routinely used for thrombolysis eligibility decision assistance. Our overall hypothesis was that patients with ‘target’ mismatch on perfusion computed tomography would have improved outcomes with rtPA. This was a prospective cohort study of consecutive ischaemic stroke patients who fulfilled standard clinical/non-contrast computed tomography eligibility criteria for treatment with intravenous rtPA, but for whom perfusion computed tomography was used to guide the final treatment decision. The ‘real-time’ perfusion computed tomography assessments were qualitative; a large perfusion computed tomography ischaemic core, or lack of significant perfusion lesion-core mismatch were considered relative exclusion criteria for thrombolysis. Specific volumetric perfusion computed tomography criteria were not used for the treatment decision. The primary analysis compared 3-month modified Rankin Scale in treated versus untreated patients after ‘off-line’ (post-treatment) quantitative volumetric perfusion computed tomography eligibility assessment based on presence or absence of ‘target’ perfusion lesion-core mismatch (mismatch ratio >1.8 and volume >15 ml, core perfusion computed tomography-selected rtPA-treated patients to an Australian historical cohort of non-contrast computed tomography-selected rtPA-treated patients. Of 635 patients with acute ischaemic stroke eligible for rtPA by standard criteria, thrombolysis was given to 366 patients, with 269 excluded based on visual real-time perfusion computed tomography assessment. After off-line quantitative perfusion computed tomography classification

  7. Human males and females body thermoregulation: perfusion effect analysis.

    Science.gov (United States)

    Acharya, Saraswati; Gurung, D B; Saxena, V P

    2014-10-01

    Skin temperature is a common physiological parameter that reflects thermal responses. Blood perfusion is an important part of the physiological processes that the human body undergoes in order to maintain homeostasis. This study focuses on the effect of perfusion on the temperature distribution in human males and females body in different thermal environment. The study has been carried out for one dimensional steady cases using finite element method. The input parameter of the model is the blood perfusion or volumetric flow rate within the tissue. The appropriate physical and physiological parameters together with suitable boundary conditions that affect the heat regulations have been incorporated in the model. The study is to have a better understanding that how does thermoregulation change in human males and females skin layered due to perfusion. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Exercise: Benefits of Exercise

    Medline Plus

    Full Text Available ... version of this page please turn Javascript on. Exercise: Benefits of Exercise Health Benefits One of the Healthiest Things You Can Do ... can do for yourself. Studies have shown that exercise provides many health benefits and that older adults can gain a lot ...

  9. Exercise: Benefits of Exercise

    Science.gov (United States)

    ... version of this page please turn Javascript on. Exercise: Benefits of Exercise Health Benefits One of the Healthiest Things You Can Do ... can do for yourself. Studies have shown that exercise provides many health benefits and that older adults can gain a lot ...

  10. Australian and New Zealand Perfusion Survey: Management and Procedure

    Science.gov (United States)

    Tuble, Sigrid C.; Willcox, Timothy W.; Baker, Robert A.

    2009-01-01

    Abstract: In this report, we will discuss management and procedural aspects of perfusion practice. This report allows us to compare and contrast recent trends and changes in perfusion with historic practices. A survey comprised of 233 single-answer and 12 open-ended questions was sent by e-mail to senior perfusionists or individuals in charge of perfusion in 40 hospital groups. The survey encompasses a review of the perfusion practices for the calendar year of 2003, and respondents were required to answer the survey based on the predominant practice in their institutions. Standard management of routine adult cardiopulmonary bypass (CPB) in 2003 consisted of perfusion strategies that achieved a target temperature of 32.0°C (range, 28.0–35.0°C), a flow index of 2.4 L/min/m2 (range, 1.6–3.0 L/min/m2) during normothermia and 1.8 L/min/m2 (range, 1.2–3.0 L/min/m2) during hypothermia, and a pressure during CPB between 50 (range, 30–65 mmHg) and 70 mmHg (range, 60–95 mmHg). Myocardial protection with blood cardioplegia was used in 77% of the 20,688 CPB cases, whereas in 53% cases, cardiotomy blood was never processed. Pre-operatively, 76% of perfusion groups assessed their patients (21% directly with the patient), and 85% responded that perfusionists performed or participated in a formal pre-bypass checklist. The majority of the perfusion groups used a handwritten perfusion record (62%), 12% used an electronic perfusion record, and 26% used both, whereas more than one half of the groups were involved in quality assurance (79%), incident reporting (74%), audits (62%), research (53%), participating in interdisciplinary meetings (53%), and morbidity and mortality meetings (65%). Only 26% conducted formal perfusion team meetings. This report outlines the status of clinical management and procedural performance for perfusion practices in Australia and New Zealand in 2003. Awareness of these trends will allow perfusionists to assess both individual practices and

  11. Reproducibility of magnetic resonance perfusion imaging.

    Directory of Open Access Journals (Sweden)

    Xiaomeng Zhang

    Full Text Available Dynamic MR biomarkers (T2*-weighted or susceptibility-based and T1-weighted or relaxivity-enhanced have been applied to assess tumor perfusion and its response to therapies. A significant challenge in the development of reliable biomarkers is a rigorous assessment and optimization of reproducibility. The purpose of this study was to determine the measurement reproducibility of T1-weighted dynamic contrast-enhanced (DCE-MRI and T2*-weighted dynamic susceptibility contrast (DSC-MRI with two contrast agents (CA of different molecular weight (MW: gadopentetate (Gd-DTPA, 0.5 kDa and Gadomelitol (P792, 6.5 kDa. Each contrast agent was tested with eight mice that had subcutaneous MDA-MB-231 breast xenograft tumors. Each mouse was imaged with a combined DSC-DCE protocol three times within one week to achieve measures of reproducibility. DSC-MRI results were evaluated with a contrast to noise ratio (CNR efficiency threshold. There was a clear signal drop (>95% probability threshold in the DSC of normal tissue, while signal changes were minimal or non-existent (<95% probability threshold in tumors. Mean within-subject coefficient of variation (wCV of relative blood volume (rBV in normal tissue was 11.78% for Gd-DTPA and 6.64% for P792. The intra-class correlation coefficient (ICC of rBV in normal tissue was 0.940 for Gd-DTPA and 0.978 for P792. The inter-subject correlation coefficient was 0.092. Calculated K(trans from DCE-MRI showed comparable reproducibility (mean wCV, 5.13% for Gd-DTPA, 8.06% for P792. ICC of K(trans showed high intra-subject reproducibility (ICC = 0.999/0.995 and inter-subject heterogeneity (ICC = 0.774. Histograms of K(trans distributions for three measurements had high degrees of overlap (sum of difference of the normalized histograms <0.01. These results represent homogeneous intra-subject measurement and heterogeneous inter-subject character of biological population, suggesting that perfusion MRI could be an imaging biomarker to

  12. PERFUSION SYSTEM CONTROLLER STRATEGIES DURING AN ECMO SUPPORT

    OpenAIRE

    2014-01-01

    In this work modelling and control of Perfusion system is presented. The Perfusion system simultaneously controls the partial pressures during Extra Corporeal Membrane Oxygenation (ECMO) support. The main Problem in ECMO system is exchange of Blood Gases in the Artificial Lung (Oxygenator).It is a highly Nonlinear Process comprising time-varying parameters, and varying time delays, it is currently being controlled manually by trained Perfusionist. The new control strategy implemen...

  13. Perfusion Electronic Record Documentation Using Epic Systems Software.

    Science.gov (United States)

    Steffens, Thomas G; Gunser, John M; Saviello, George M

    2015-12-01

    This paper describes the design and use of Epic Systems software for documentation of perfusion activities as part of the patient electronic medical record. The University of Wisconsin Hospital and Clinics adapted the Anesthesia software module and developed an integrated perfusion/anesthesia record for the documentation of cardiac and non-cardiac surgical procedures. This project involved multiple committees, approvals, and training to successfully implement. This article will describe our documentation options, concepts, design, challenges, training, and implementation during our initial experience.

  14. Whole brain CT perfusion on a 320-slice CT scanner

    Directory of Open Access Journals (Sweden)

    Jai Jai Shiva Shankar

    2011-01-01

    Full Text Available Computed tomography perfusion (CTP has been criticized for limited brain coverage. This may result in inadequate coverage of the lesion, inadequate arterial input function, or omission of the lesion within the target perfusion volume. The availability of 320-slice CT scanners offers whole brain coverage. This minimizes the chances of misregistration of lesions regardless of location, and makes the selection of the arterial input function easy. We present different clinical scenarios in which whole brain CTP is especially useful.

  15. Three-dimensional tumor perfusion reconstruction using fractal interpolation functions.

    Science.gov (United States)

    Craciunescu, O I; Das, S K; Poulson, J M; Samulski, T V

    2001-04-01

    It has been shown that the perfusion of blood in tumor tissue can be approximated using the relative perfusion index determined from dynamic contrast-enhanced magnetic resonance imaging (DE-MRI) of the tumor blood pool. Also, it was concluded in a previous report that the blood perfusion in a two-dimensional (2-D) tumor vessel network has a fractal structure and that the evolution of the perfusion front can be characterized using invasion percolation. In this paper, the three-dimensional (3-D) tumor perfusion is reconstructed from the 2-D slices using the method of fractal interpolation functions (FIF), i.e., the piecewise self-affine fractal interpolation model (PSAFIM) and the piecewise hidden variable fractal interpolation model (PHVFIM). The fractal models are compared to classical interpolation techniques (linear, spline, polynomial) by means of determining the 2-D fractal dimension of the reconstructed slices. Using FIFs instead of classical interpolation techniques better conserves the fractal-like structure of the perfusion data. Among the two FIF methods, PHVFIM conserves the 3-D fractality better due to the cross correlation that exists between the data in the 2-D slices and the data along the reconstructed direction. The 3-D structures resulting from PHVFIM have a fractal dimension within 3%-5% of the one reported in literature for 3-D percolation. It is, thus, concluded that the reconstructed 3-D perfusion has a percolation-like scaling. As the perfusion term from bio-heat equation is possibly better described by reconstruction via fractal interpolation, a more suitable computation of the temperature field induced during hyperthermia treatments is expected.

  16. Rapid donor liver procurement with only aortic perfusion

    Institute of Scientific and Technical Information of China (English)

    Qi-Yuan Lin; KK Chui; AR-Nitin Rao

    2001-01-01

    ATM: to describe a rapid technique for procurement of donor liver with aortic perfusion only (APO). METHODS: Only the aorta is cannulated and perfused with chilled preservation solution. RESULTS: The quality of donor liver can ensure the grafted liver functions. CONCLUSION: The method of APO can simplify the operative procedure, compared with the dual cannulation. It also can minimize the danger of injuring vascular structures and involve less dissection.

  17. Assessment of lung tumor response by perfusion CT.

    Science.gov (United States)

    Coche, E

    2013-01-01

    Perfusion CT permits evaluation of lung cancer angiogenesis and response to therapy by demonstrating alterations in lung tumor vascularity. It is advocated that perfusion CT performed shortly after initiating therapy may provide a better evaluation of physiological changes rather than the conventional size assessment obtained with RECIST. The radiation dose,the volume of contrast medium delivered to the patient and the reproducibility of blood flow parameters remain an issue for this type of investigation.

  18. A Review of Liver Perfusion Method in Toxicology Studies

    Directory of Open Access Journals (Sweden)

    M karami

    2014-06-01

    Full Text Available Introduction: The isolated perfused rat liver is an accepted method in toxicology studies. The isolated perfused rat liver (IPRL is a useful experimental system for evaluating hepatic function without the influence of other organ systems, undefined plasma constituents, and neural-hormonal effects. Methods: The untreated male rats (180-220gr body weight were anesthetised with ether and then surgery with proper method. The abdomen was opened through a midline and one transversal incision and the bile duct was cannulated. Heparin sodium solution (0.5 ml; 500 U/ml in 0.9% NaCl was injected via the abdominal vena cava to prevent blood clotting. The liver inferior venacava was cannulated with PE-10 tubing and secured. The portal vein was immediately cannulated with an 23gr catheter which was secured and then liver was perfused in situ by Krebs- Henseleit buffer (pH 7.4; saturated with 95% O2 and 5% CO2; 37°C at a flow rate of 20 ml/min for 3hr. Temperature, perfusion pressure, flow rate and perfusion fluid pH were closely monitored during the perfusion. Results: Transferase enzymes (ALT, AST alterations can be widely used as a measure of biochemical alterations in order to assess liver damage due to use of drugs such as isoniazid (INH and animal and plant toxins. Accumulated material in gallbladder are valuable samples to assess the level of Glutathione (GSH. Sections of perfused liver tissue can also be effectively analyzed for pathological aspects such as necrosis, fibrosis, cellularity. Conclusion: The isolated perfused rat liver (IPRL is a useful and Sutible experimental system for evaluating hepatic function. In this system, the effects of adjacent organs, on the liver is minimized

  19. Role of Perfusion CT Differentiating Hemangiomas from Malignant Hepatic Lesions

    Directory of Open Access Journals (Sweden)

    Jagjeet Singh

    2014-01-01

    Full Text Available Objective: The purpose of the study was to determine the role of computed tomography (CT perfusion in differentiating hemangiomas from malignant hepatic lesions. Materials and Methods: This study was approved by the institutional review board. All the patients provided informed consent. CT perfusion was performed with 64 multidetector CT (MDCT scanner on 45 patients including 27 cases of metastasis, 9 cases of hepatocellular carcinoma (HCC, and 9 cases of hemangiomas. A 14 cm span of the liver was covered during the perfusion study. Data was analyzed to calculate blood flow (BF, blood volume (BV, permeability surface area product (PS, mean transit time (MTT, hepatic arterial fraction (HAF, and induced residue fraction time of onset (IRFTO. CT perfusion parameters at the periphery of lesions and background liver parenchyma were compared. Results: Significant changes were observed in the perfusion parameters at the periphery of different lesions. Of all the perfusion parameters BF, HAF, and IRFTO showed most significant changes. In our study we found: BF of more than 400 ml/100 g/min at the periphery of the hemangiomas showed sensitivity of 88.9%, specificity of 83.3%, positive predictive value (PPV of 57.1%, and negative predictive value (NPV of 96.7% in differentiating hemangiomas from hepatic malignancy; HAF of more than 60% at the periphery of hemangiomas showed sensitivity of 77.8%, specificity of 86.1%, PPV of 58.3% and NPV of 93.9% in differentiating hemangiomas from hepatic malignancy; IRFTO of more than 3 s at the periphery of hemangiomas showed sensitivity of 77.8%, specificity of 86.1%, PPV of 58.3%, and NPV of 93.9% in differentiating hemangiomas from hepatic malignancy. Conclusion: Perfusion CT is a helpful tool in differentiating hemangiomas from hepatic malignancy by its ability to determine changes in perfusion parameters of the lesions.

  20. CT perfusion image processing: analysis of liver tumors

    OpenAIRE

    D’Antò, Michela

    2013-01-01

    Perfusion CT imaging of the liver has potential to improve evaluation of tumour angiogenesis. Quantitative parameters can be obtained applying mathematical models to Time Attenuation Curve (TAC). However, there are still some difficulties for an accurate quantification of perfusion parameters due, for example, to algorithms employed, to mathematical model, to patient’s weight and cardiac output and to the acquisition system. In this thesis, new parameters and alternative methodologies ab...