Search PubMed⌕ Search

Biomedical subjects

R L Baron

Publications and source records attributed to R L Baron.

At least 91 records · Page 5Linked to original sources
PubMed1991

Sonography of the gallbladder: significance of striated (layered) thickening of the gallbladder wall.

Sonographic identification of thickening of the gallbladder wall that consists of multiple striations (alternate hypoechoic and hyperechoic layers) has been considered strong evidence of the presence of acute cholecystitis. We studied 27 patients in whom sonograms showed striated thickening of the gallbladder wall to determine the diagnostic significance of this finding. Striations were classified as focal or diffuse. Sonograms were correlated with pathologic findings in 16 patients and with clinical diagnoses and laboratory findings in 11. Patients were categorized as having cholecystitis with or without gangrene or edema of the gallbladder wall unrelated to gallbladder disease. Striated thickening of the gallbladder wall was due to cholecystitis in 10 patients, and all 10 had gangrenous changes at surgery or at pathologic examination. Striations were focal in eight of these patients and diffuse in two. Striated thickening of the gallbladder wall was due to edema of the wall unrelated to gallbladder disease in 17 patients. Causes included congestive heart failure (n = 4), renal failure (n = 5), liver disease (hepatic failure [n = 1], hepatitis [n = 6]), ascites (n = 2), hypoalbuminemia (n = 3), pancreatitis (n = 1), blockage of the lymphatic/venous drainage of the gallbladder (n = 2), and prominent Rokitansky-Aschoff sinuses (n = 1). More than one abnormality was present in five patients. Striations were focal in 11 of these patients and diffuse in six. The sonographic finding of striated gallbladder wall thickening is no more specific for cholecystitis than the observation of gallbladder wall thickening by itself, and it may occur in a variety of diseases. However, in the clinical setting of acute cholecystitis, the presence of striations suggests gangrenous changes in the gallbladder. The extent of the striations (focal or diffuse) is not useful in predicting the cause of the striated gallbladder wall thickening.

Acute Disease↗
PubMed1991

Gangrenous cholecystitis: new observations on sonography.

We studied 25 patients with gangrenous cholecystitis and observed a new sonographic finding--striated thickening of the gallbladder wall--and three patterns of pericholecystic fluid collections. Heterogeneous thickening of the gallbladder wall was characterized by either multiple striations (alternating hypoechoic and hyperechoic layers) or irregular mass-like protrusions projecting into the gallbladder lumen. We observed striated thickening far more frequently (in 10 of 25 patients) than other findings reported previously as being associated with gangrenous cholecystitis, such as intraluminal membranes (1 in 25 patients) and masslike protrusions into the gallbladder lumen (1 in 25 patients). Although the sensitivity and specificity of this finding cannot be determined by our study, we believe that mural striations in cases of acute cholecystitis should raise the question of gangrenous changes. Additionally, we found that two subtypes of pericholecystic fluid collections (types II and III) were associated with gallbladder wall perforation and abscess formation more frequently than type I collections.

Adult↗
PubMed1991

Computed tomography of the biliary tree.

Computed tomography clearly demonstrates the spectrum of biliary tract disease and can be useful as a screening examination and as a problem solving tool in patients with complex biliary disease processes. Tailoring of CT examinations for specific indications and attention to CT techniques for evaluating the biliary tract are necessary to maximize the utility of CT in these cases.

Biliary Tract↗
PubMed1990

Differentiating pelvic veins and enlarged lymph nodes: optimal CT techniques.

A study was done to find the best technique of administering contrast material intravenously to enable differentiation of pelvic veins and enlarged lymph nodes on computed tomographic (CT) scans. Seventy-eight patients with suspected pelvic malignancies were evaluated with CT. After precontrast scans were obtained at a selected pelvic level, 150 mL of contrast material was injected as a two-phase bolus; images were obtained at the same level 1.5, 3, 5, and 7 minutes after initiation of the bolus. Mean pelvic venous enhancement was maximal between 3 and 7 minutes in all the patients. Venous attenuation changes did not correlate with the presence of cardiac or peripheral vascular disease, but there was significantly less enhancement in patients with diabetes mellitus. The time of maximum vein enhancement begins at 3 minutes and continues for at least 4 minutes. A delayed technique of scanning the pelvis may be preferable to rapid scanning to optimize enhancement of the pelvic veins.

Adult↗
PubMed1990

Normal intrahepatic bile ducts: CT depiction.

Visualization of intrahepatic bile ducts (IHBDs) at computed tomography (CT) has previously been considered evidence of biliary obstruction. The authors have found that hepatic CT enhanced with contrast material and with the use of ceramic scintillation detectors allows frequent visualization of normal IHBDs. One hundred patients without imaging, laboratory, or clinical evidence of hepatobiliary or pancreatic disease were prospectively examined to assess the frequency of visualization, location, and size of IHBDs. IHBDs were visualized in 40% of the patients and had an average size of 2.0 mm in the central part of the liver and 1.8 mm in the peripheral part of the liver. Ducts were seen in the right lobe more often than in the left lobe. There was no statistically significant relationship between visualization of IHBDs and patient age. Demonstration of IHBDs on current CT scanners is a normal finding and does not indicate biliary obstruction.

Bile Ducts, Intrahepatic↗
PubMed1990

CT of the extrahepatic bile ducts: wall thickness and contrast enhancement in normal and abnormal ducts.

Recent reports have described thickening and enhancement of the extrahepatic bile duct wall on CT scans obtained after administration of IV contrast material. We undertook this study to establish parameters for the normal thickness and enhancement of the bile duct wall on CT, and to develop a differential diagnosis for thickening of the duct wall. Routine CT examinations of 100 patients without biliary disease were evaluated prospectively. The common hepatic duct and common bile duct could be visualized in 66% and 82% of cases, respectively; the walls of these ducts could be separately discerned in 59% and 52%. The mean thickness of the duct wall was 1 mm, with a maximal thickness of 1.5 mm. Wall enhancement was similar to (51%), slightly greater than (44%), or markedly greater than (5%) the enhancement of adjacent pancreatic parenchyma. A review of records covering a 5-year period identified 52 patients in whom CT showed thickening of the bile duct wall (greater than or equal to 2 mm). These patients could be categorized by seven underlying diseases, and analysis of the CT scans revealed four general patterns of thickening. Focal, concentric wall thickening in the distal common bile duct was associated with pancreatitis, pancreatic cancer, and common bile duct stones; focal, eccentric thickening tended to occur with cholangiocarcinoma and sclerosing cholangitis. Diffuse, concentric thickening was seen with acute cholangitis; diffuse, eccentric thickening was associated with oriental cholangiohepatitis and sclerosing cholangitis. Thickening of greater than 5 mm was seen only with cholangiocarcinoma. Enhancement of the duct wall in these groups varied and was of no predictive value. In summary, the extrahepatic bile ducts can be visualized in the majority of patients, and the normal duct wall should be 1.5 mm or less in thickness. Contrast enhancement of the duct wall occurs in patients without biliary tract disease and alone is predictive not predictive of pathology. Pancreatitis, pancreatic cancer, common bile duct stones, cholangiocarcinoma, sclerosing cholangitis, acute cholangitis, and oriental cholangiohepatitis are associated with thickening of the duct wall.

Acute Disease↗
PubMed1990

Piezoelectric biliary lithotripsy: an in vitro study of factors affecting gallstone fragmentation.

Factors affecting the fragmentation of gallstones with piezoelectric lithotripsy were studied in vitro, with a goal of providing data that will help direct treatment with piezoelectric lithotriptors. Two hundred fifty-seven stones from 50 patients were treated with the EDAP LT.O1 lithotriptor until all fragments measured 2 mm or less in diameter. The fragmentation process was observed, and two patterns were evident: central fragmentation and peripheral chipping. The majority of stones fragmented centrally. Fragmentation characteristics in different stones from the same patient were compared with those from different patients. Stone diameter, shock-wave frequency and power, and CT appearance were examined and correlated with fragmentation. Gallstones from the same patient showed uniform fragmentation patterns and consistent relationships between fragmentation time and gallstone size, shock-wave frequency, and power. In stones from the same patient, gallstone size had a marked effect on fragmentation time, which correlated with the cube of the stone diameter, and shock-wave frequency and power had a proportional inverse linear relationship with fragmentation time. When controlling for stone size and treatment parameters, stones from multiple patients showed marked differences in fragmentation time, and because of this, poor correlation between stone size and fragmentation time. Stones grouped according to CT pattern and attenuation showed wide variation and no correlation between CT characteristics and fragmentation pattern or fragmentation time. Our results show that a great variability exists in fragmentation time of gallstones, making it impossible to accurately predict fragmentation time at a given stone size. Only rough estimates of longer fragmentation times with increasing stone size can be made. The linear relationships between shock-wave frequency or power and fragmentation time allow one to easily predict the effect of manipulating these variables and to tailor treatment to each patient's tolerance. Finally, CT appearance does not appear to be predictive of fragmentation outcome.

Biomechanical Phenomena↗
PubMed1989

In vitro dissolution of gallstones with MTBE: correlation with characteristics at CT and MR imaging.

The authors undertook a study to determine whether in vitro computed tomography (CT) or magnetic resonance (MR) imaging could enable the prediction of the outcome of gallstone dissolution with methyl tert-butyl ether (MTBE). In vitro CT and MR images were obtained of gallstones removed at surgery from 40 and 30 patients, respectively. The patterns of the gallstones seen on CT scans were categorized as dense, moderately dense, faint, isodense, rimmed, and laminated. Gallstones were categorized by maximal signal intensities seen on T1-weighted MR images. After imaging, gallstones underwent in vitro MTBE dissolution. CT appearances correlated well with dissolution rates. Greatest weight change was noted in gallstones with homogeneously faint and isodense patterns, and least weight change was seen in stones with a homogeneously dense pattern. Rimmed and laminated stones with foci of high attenuation dissolved significantly to 5% or less of the original weight, a finding indicating that such foci do not preclude dissolution. Dissolution rates correlated with attenuation values of homogeneous stones (r = .8) and of the rim portion of rimmed stones (r = .8). No correlation was found between T1-weighted signal intensities on MR images and MTBE dissolution rates.

Cholelithiasis↗
PubMed1989

Comparison of STIR and spin-echo MR imaging at 1.5 T in 90 lesions of the chest, liver, and pelvis.

Short TI inversion recovery (STIR) produces both fat suppression and the additive effect of T1 and T2 mechanisms on tissue brightening, in contrast to the subtractive effect of these two mechanisms on spin-echo sequences. In order to compare STIR and spin-echo imaging, we reviewed 90 lesions detected in 76 consecutive MR studies of the chest, liver, or pelvis performed at 1.5 T with both STIR and double-echo spin-echo techniques. Images were compared for the number of individual lesions detected. Lesion conspicuity was scored by using a subjective scale for each sequence. Lesion size was measured with hand-held calipers, and volume was calculated assuming a prolate ellipse. Because of inherent error in such calculations, lesions were judged to be similar in size (within 20%) or dissimilar (more than 20% difference). The presence of a lesion was proved by direct biopsy in 36 (40%), by tissue pathology from some other focus plus follow-up of the lesion in 37 (41%), or by other imaging plus follow-up in 12 (13%). STIR images detected five (6%) more lesions than spin echo and did not miss any of the lesions detected by spin echo. Conspicuity was greater on STIR images than on spin-echo images in 82 (91%) of the lesions. Twenty-six (29%) of the lesions appeared larger on STIR images than on spin-echo images. For these reasons, STIR may be a useful adjunct to spin echo for body MR in some cases. However, STIR images typically display lower signal-to-noise than spin-echo images do, and all abnormalities (tumor or edema) may appear equally bright on STIR.

Adolescent↗
PubMed1989

MR appearance of gallstones in vitro at 1.5 T: correlation with chemical composition.

Gallstones from 63 patients were evaluated by in vitro 1.5-T MR imaging, with T1- and T2-weighted images, and in 14 cases, a fat-suppression sequence (short-T1 inversion recovery imaging). Subsequent chemical analysis was performed on 43 gallstones. In vitro proton MR spectroscopy was performed on 14 stones. On T1-weighted MR images, foci of increased signal were seen in 46 of 63 stones (faint in 17, moderate in nine, and bright in 20). T2-weighted images showed areas of increased signal in 18 of 63 stones (faint in 15, moderate in three). T1-weighted MR imaging patterns were homogeneously dark (17), homogeneously bright (two), homogeneously faint (three), rimmed (dark rim and bright center, 32), and laminated (nine). Short-T1 inversion recovery imaging suppressed the foci of increased signal in 13 of 14 cases. Despite imaging characteristics suggestive of high lipid content, spectroscopy revealed only a single peak corresponding to a large water-proton signal. The T1 relaxation times of the water were shortened, ranging from 0.006 to 0.92 sec, explaining the increased signal seen on MR images of the gallstones. MR imaging characteristics (signal intensity, relative signal area, or imaging patterns) did not correlate with chemical composition. We hypothesize that different structural relationships must exist within gallstones of similar chemical content that alter the water bonding and hence the MR imaging characteristics.

Cholelithiasis↗
PubMed1989

Biliary complications of pancreatitis.

The biliary complications of pancreatitis include cholestasis, secondary biliary cirrhosis, cholangitis, and pseudocyst or fistula affecting the hepatobiliary system. Of these, the most relevant for radiologists is cholestasis caused by biliary duct stenosis in an inflamed pancreatic head. Radiologic assessment of these complications is based on judicious use of ultrasound, computed tomography, and direct cholangiography. The typical imaging finding of common bile duct stenosis due to chronic pancreatitis is gradual tapered narrowing of the intrapancreatic common bile duct, which can be portrayed by carefully accomplished computed tomography, and ultrasound as well as cholangiography. When combined with clinical assessment, imaging tests can help determine strategies for treatment, which include traditional operations as well as transhepatic, endoscopic, or percutaneous interventions.

Biliary Tract Diseases↗
PubMed1988

Sclerosing cholangitis: CT findings.

The value of computed tomography (CT) in the detection of primary sclerosing cholangitis (PSC) in the intrahepatic and extrahepatic biliary systems was assessed by comparing CT scans of 20 cases of PSC with cholangiographic findings. In 16 of 19 cases of extrahepatic duct disease demonstrated with cholangiography, CT demonstrated abnormalities of the common hepatic duct, or bile duct, including duct stenosis, mural nodularity, duct dilatation, wall thickening, and mural enhancement. CT demonstrated intrahepatic disease in all 20 cases, including duct dilatation, duct stenosis, pruning, and beading. CT was superior to cholangiography in characterization of the status of the intrahepatic duct system in 11 of 20 cases. In addition, CT demonstrated extrabiliary complications of PSC in 12 cases and superimposed cholangiocarcinoma in three cases. While cholangiography remains the standard for diagnosis and follow-up of PSC, CT can provide valuable information about the extent and complications of the disease.

Adult↗
PubMed1988

MR imaging of avascular necrosis of the femoral head: value of small-field-of-view sagittal surface-coil images.

We compared coronal, large-field-of-view, body-coil MR images with sagittal, small-field-of-view, surface-coil images of 30 hips for their sensitivities in establishing the diagnosis of avascular necrosis; spatially localizing the avascular necrosis; and detecting joint-space narrowing, femoral head collapse, articular cartilage fracture, and joint fluid. We also compared the two separate plane/coil combinations for detection of the "double-line" sign (high signal inside a band of low signal, believed to be characteristic for avascular necrosis) and intertrochanteric conversion of hematopoietic marrow to fatty marrow. Coronal, large-field-of-view, body-coil images provided an adequate screening examination for the presence of avascular necrosis (sensitivity of 94%) and were preferred in all cases for mediolateral localization of focal abnormality. They were also better for assessing joint fluid and detecting fatty conversion of marrow. Sagittal, small-field-of-view, surface-coil images were preferred for anteroposterior localization in all cases and for superoinferior localization of focal abnormality in 15 of 18 cases. They detected additional cases of joint-space narrowing, articular cartilage fracture, and the double-line sign missed by coronal, body-coil images. Sagittal, small-field-of-view, surface-coil images are a valuable adjunct to MR evaluation of femoral avascular necrosis because they provide additional information that may be useful for planning surgical therapy.

Adult↗
PubMed1988

CT evaluation of gallstones in vitro: correlation with chemical analysis.

With the advent of chemical dissolution and lithotripsy for the treatment of gallstones, use of imaging techniques to determine the chemical composition of gallstones has become important. In vitro CT scans were performed on gallstones removed at surgery from 70 patients. The CT appearances were as follows: dense (20%), faint (10%), isodense with saline (nonvisualized) (26%), rimmed (30%), and laminated (14%). Stones from 50 patients were subjected to chemical analysis, and the results were compared with the appearance of the stones on CT. Among stones grouped by CT appearance, a significant difference in cholesterol content was found, but calcium content did not differ significantly among most groups. The inverse correlation between CT attenuation values and cholesterol was stronger (r = -.82) than the correlation between CT attenuation values and calcium (r = .64). The results show that gallstones can be divided into those with high cholesterol content and those with low cholesterol content on the basis of their appearance on in vitro CT. The differences in the CT findings in many gallstones appear to relate more to cholesterol content than to calcium composition.

Bilirubin↗
PubMed1987

Common bile duct stones: reassessment of criteria for CT diagnosis.

To evaluate the specificity of previously suggested computed tomographic (CT) criteria for diagnosing common bile duct (CBD) stones, CT scans of 38 patients with CBD stones were compared with scans of 32 patients with carcinoma obstructing the CBD and 28 nonobstructed patients. The CBD stone was directly visualized as a target sign or densely calcified structure in 29 of 38 patients with stones (76%); one with carcinoma showed a similar target sign. A rim of increased density in the distal CBD was found without accompanying target sign in six patients with stones (16%), compared with 12 with carcinoma (38%) and 15 nonobstructed patients (54%). Irregular intraluminal densities without a detectable target sign were noted in four patients with stones (11%), compared with eight with carcinoma (25%) and nine nonobstructed patients (32%). Abrupt termination of the CBD without a mass was more common as an isolated finding in patients with carcinoma (31%) than in patients with stones (13%). CT is accurate in detecting CBD stones in certain patient populations, but direct visualization of the stone is required.

Common Bile Duct↗
PubMed1986

Acute inhalation studies with methyl isocyanate vapor. I. Methodology and LC50 determinations in guinea pigs, rats, and mice.

Groups of male and female Fischer 344 rats, B6C3F1 mice, and Hartley guinea pigs were exposed once for 6 hr to mean concentrations of 10.5, 5.4, 2.4, 1.0, or 0 (control) ppm of methyl isocyanate (MIC) vapor. Rats and mice were also exposed to 20.4 ppm of MIC. No deaths occurred in animals exposed to 2.4 or 1.0 ppm. The majority of deaths for the 20.4- and 10.5-ppm groups occurred during postexposure Days 1 through 3, while at 5.4 ppm deaths were observed throughout the 14-day postexposure period. The 6-hr LC50 values (with 95% confidence limits) were 6.1 (4.6 to 8.2) ppm for rats, 12.2 (8.4 to 17.5) ppm for mice, and 5.4 (4.4 to 6.7) ppm for guinea pigs. Notable clinical observations during and immediately following MIC exposure were lacrimation, perinasal/perioral wetness, respiratory difficulty (e.g., mouth breathing), decreased activity, ataxia, and hypothermia. The frequency of clinical signs decreased during the second postexposure week. Body weight losses were common in all species following MIC exposures of 2.4 ppm or greater. At 1.0 ppm, only female mice had body weight depression. Recovery of body weight loss was observed in the 5.4- (guinea pigs only), 2.4- and 1.0-ppm concentration groups. The lungs of all animals that died were discolored. Following microscopic examination of the respiratory tract, deaths were attributed to pulmonary edema and congestion. In a separate study, Fischer 344 rats and Hartley guinea pigs were exposed once for 4 hr to mean concentrations of 36.1, 25.6, 15.2, or 5.2 ppm of MIC vapor. In general, the results were similar to those of the single 6-hr exposure study.

Animals↗