ISSN:1053-1807    

DOI:10.1002/jmri.1880050302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:1053-1807    

DOI:10.1002/jmri.1880050303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractSuspected pelvic endometrlosis was prospectively evaluated in 31 women with T1‐ and T2‐weighted conventional spin‐echo (CSE) magnetic resonance imaging alone and in combination with Tl‐weighted fat‐suppressed (TIPS) and gadolinium‐enhanced TIPS (Gd‐TlFS) spin‐echo techniques. Images were grouped for interpretation and comparison as follows:(a)CSE alone,(b)CSE/T1FS. and(c)CSE/T1FS/ Gd‐TlFS. All patients underwent surgery within 3 months of imaging, and 21 patients were found to have endometrlosis: 59 endometriomas (26 large and 33 small) and 51 sites of implants were seen. With CSE images, 23 large and six small endometriomas were detected. With CSE/T1FS images, 25 large and 14 small endometriomas were identified. With CSE/ TIFS/Gd‐TlFS Images, 24 large and 14 small endometriomas were detected and ill‐defined areas of enhancement were noted in 22 sites throughout the pelvis. These corresponded to endometriotic implants seen at surgery in 14 sites. The sensitivity, specificity, and accuracy, respectively, for the detection of endometriosis were 76%, 60%, and 71% for CSE, 86%, 50%, and 74% for CSE/T1FS, and 81%, 50%, and 71% for CSE/TlFS/Gd‐TlFS images. No significant differences (P>0.1) between image combinations for correctly identifying patients with and without endometriosis were seen. The difference in sensitivity between CSE and CSE/T1FS and between CSE and CSE/TlFS/Gd‐TlFS images for detecting small endometrioma

ISSN:1053-1807    

DOI:10.1002/jmri.1880050304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:1053-1807    

DOI:10.1002/jmri.1880050305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe aim of the study was to test the hypothesis that magnetic resonance (MR) imaging‐guided and ‐monitored noninvasive ultrasonic surgery can be performed in highly perfused tissues from outside the body. A simulation study was performed to evaluate the optimal sonication parameters. An MR‐compatible positioning device was then used to manipulate a focused ultrasound transducer in an MR imager, which was used to sonicate kidneys of five rabbits at various power levels and different durations. Temperature elevation during sonication was monitored with a T1‐ weighted spoiled gradient‐echo sequence. The simulation study demonstrated that a sharply focused transducer and relatively short sonication times (30 seconds or less) are necessary to prevent damage to the overlying skin and muscle tissue, which have a much lower blood perfusion rate than kidney. The experiments showed that the imaging sequence was sensitive enough to show temperature elevation during sonication, thereby Indicating the location of the beam focus. Histologic evaluations showed that kidney necrosis could be consistently induced without damage to overlying skin and muscle. The study demonstrated that highly perfused tissues such as the renal cortex can be coagulated from outside the body with focused ultrasound and that MR imaging can be used to guide and monitor thi

ISSN:1053-1807    

DOI:10.1002/jmri.1880050306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractTo determine whether signal intensity (SI) of the pancreas that was less than that of liver on Tl‐ weighted fat‐suppressed (T1FS) magnetic resonance (MR) images could be used to help predict the presence of pancreatic disease, three blinded independent observers graded pancreatic SI relative to liver and/or renal cortex in 89 patients on T1PS images. Results were correlated with patient age and diagnosis. Among the 47 patients with a clinically normal pancreas, pancreatic SI was higher than that of liver in 42 and equal to that of liver in the rest, none of whom had evidence of fatty pancreas. These five patients had a mean age of 71 years, compared with 55 years for patients whose pancreas was more intense than liver (P=.02). Of the 42 patients with a clinically abnormal pancreas, only eight had pancreatic SI higher than that of liver. The positive predictive value for normal pancreas of an SI higher than that of liver was 84% and the positive predictive value for abnormal pancreas of an SI less than or equal to that of liver was 88%, with an overall accuracy of 86%. If normal pancreatic SI is defined as higher than that of liver for patients younger than 60 years and as equal to or higher than that of liver for patients older than 60 years, the positive predictive value of normal SI becomes 76%, the positive predictive value of decreased SI becomes 100%, and the overall accuracy becomes 83%. Pancreatic SI less than that of liver correlates highly with pancreatic disease, especially in younger patients. Mildly decreased pancreatic SI, equal to that of nondiseased liver, is common in older persons without clinically apparent pancreatic dise

ISSN:1053-1807    

DOI:10.1002/jmri.1880050307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:1053-1807    

DOI:10.1002/jmri.1880050308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThirty patients with 15 hepatocellular carcinomas, 10 metastases, four hemangiomas, and one cholangiocarcinoma underwent magnetic resonance imaging at 1.5 T with T1‐weighted, T2‐ weighted spin‐echo (SE) images, gradient‐echo (GRE) magnetization transfer (MT) images, and gadolinium‐enhanced T1‐weighted SE and MT‐ GRE images. The MT effect and lesion‐liver contrast‐to‐noise ratio (C/N) were calculated and visual assessment (qualitative analysis) performed for unenhanced and enhanced MT‐GRE images and enhanced Tl‐weighted SE images. The C/N values for hepatic adenocarcinomas (seven metastases and one cholangiocarcinoma) and hemangiomas were larger for enhanced MT‐GRE images (adenocarcinoma, 8.4 ± 2.3 [P<0.01); hemangioma, 24 ± 2.1 [P<0.05]) than for enhanced GRE images (5.0 ± 1.9 and 18 ± 2.7, respectively).These enhancing tumors had the highest scores in the qualitative analysis. Enhanced MT‐GRE images showed no advantage for depiction of hepatocellular carcinom

ISSN:1053-1807    

DOI:10.1002/jmri.1880050309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:1053-1807    

DOI:10.1002/jmri.1880050310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractTo demonstrate that the lipid volume fraction In liver steatosis can be accurately estimated with in vivo hydrogen‐1 magnetic resonance (MR) spectroscopy, the authors developed a calibration procedure based on in vitro MR spectroscopy of lipid extracts from steatotlc liver specimens. The lipid volume fractions determined with the calibration procedure were compared with the results of histomorphometry and with calibrated computed tomographic (CT) data. The volume fraction of fat determined with MR spectroscopy was in good agreement with the CT results, whereas histomorphometry underestimated the amount of hepatic fat. The results indicate that determination of the fat volume fraction in steatotic liver can be achieved noninvasively with MR spectroscop

ISSN:1053-1807    

DOI:10.1002/jmri.1880050311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY