Biomedical subjects

S J Schulte

Publications and source records attributed to S J Schulte.

11 recordsLinked to original sources

PubMed1995

Evaluation of a non-breath-hold MR cholangiography technique.

PURPOSE: To evaluate prospectively a non-breath-hold magnetic resonance (MR) cholangiographic technique. MATERIALS AND METHODS: Twenty-nine non-breath-hold, heavily T2-weighted, turbo spin-echo MR cholangiograms were obtained in 28 patients and compared with 28 direct cholangiographic studies in 24 patients. RESULTS: MR cholangiography showed the intrahepatic ducts (IHDs) within the peripheral third of the liver and within the four hepatic segments in 100% of cases with dilated ducts. IHDs were seen in the peripheral third in 82% of cases with nondilated ducts and within the four hepatic segments in 91%. The extrahepatic duct (EHD), dilated and nondilated, was visualized in 90% of cases. Filling defects were identified in the EHD in 71% of cases and in the gallbladder in 100%. All obstructions were identified and their site and character accurately shown in most cases. The presence of IHD dilatation was accurately shown, and estimates of EHD and main pancreatic duct caliber correlated closely with those of direct cholangiography. CONCLUSION: Non-breath-hold MR cholangiography is a reliable method for depiction of the biliary system.

Adult↗

PubMed1995

Dietary induction of cholesterol gallstones in the owl monkey: preliminary findings in a new animal model.

The owl monkey (Aotus nancymae) is a primate with a bile acid and biliary lipid profile resembling that of humans. Aotus spp. are among the rare species, including humans, that spontaneously develop cholesterol gallstones. With dietary induction the owl monkey proved a rapid, reliable model of cholesterol cholelithiasis. Six owl monkeys, three of each sex, were fed a diet supplemented with 1.5% cholesterol for 5 weeks. Each week blood samples were drawn for cholesterol determination, and bile samples were obtained by ultrasound-guided percutaneous aspiration of the gallbladder. Weekly ultrasound imaging documented development of gallbladder sludge in all animals, with eventual stone formation in five of six. At necropsy after 5 weeks consuming the diet, all animals had distinct sludging and/or small stones in the gallbladder, correlating with the ultrasound findings. Plasma cholesterol values remained lower in females but increased markedly in some males to > 1,400 mg/dl. Histologic examination revealed mild, diffuse hepatocellular lipidosis and degeneration in four of six animals. Detailed examination of the gallbladder indicated that transhepatic needle punctures induced minimal focal abnormalities, judged inconsequential. In contrast to rodent models commonly in use, owl monkeys have liver and digestive tract anatomy and bile physiology that is similar to that in humans. These similarities give this model the potential to substantively improve understanding of the pathogenesis, treatment, and prevention of human cholesterol gallstones. This model can provide sequential, simultaneous correlation of plasma and biliary lipids, imaging of gallbladder contents, and physiologic processes.

Animals↗

PubMed1994

The effect of storage on the computed tomography attenuation of gallstones.

RATIONALE AND OBJECTIVES: The effect of storage in five media on the computed tomography (CT) attenuation of gallstones, which might be important to future in vitro studies involving gallstones and their CT characteristics, was determined. METHODS: Gallstones were obtained in bile from cholecystectomy specimens. To establish a range of normal variability in the attenuation measurements of gallstones, 24 stones were scanned three times within a 5-minute interval, with a comparison of the attenuation measurements of individual stones. To determine the effect of storage, five stones from the same gallbladder underwent CT within 48 hours of surgical retrieval and were then placed in native bile, sterile normal saline, sterile water, air, or formalin. The stones were rescanned after 1 week and 4 weeks in storage. Ten sets of five stones were evaluated with a comparison of the attenuation measurements of individual stones. RESULTS: There was an average difference of 10.2 Hounsfield Units (HU) and a maximum difference of 35 HU between the three attenuation measurements of the 24 stones that did not undergo storage. With storage, native bile was the only media where none of the 10 stones varied in attenuation by more than 35 HU. Air and saline had the greatest effect on the attenuation of stones with statistically significant differences after 4 weeks in storage (P < .02). Six of the stones stored in air and three stored in saline decreased in attenuation by more than 35 HU, with maximal decreases of 137 and 79 HU, respectively. Although not statistically significant, two stones in water and one stored in formalin showed more than 35 HU of attenuation change, varying by up to 69 and 47 HU, respectively. CONCLUSIONS: Storage may affect the CT attenuation of gallstones and needs to be considered in any in vitro experiment involving gallstone sand CT correlation. Native bile is the only medium where no stones varied in attenuation more than can be accounted for by normal measurement variation, and thus, is the storage medium of choice.

Air↗

PubMed1992

Patterns of intrahepatic bile duct dilatation at CT: correlation with obstructive disease processes.

The authors performed a blinded, retrospective analysis of 100 computed tomographic (CT) scans of patients with proved extrahepatic bile duct obstruction, including primary sclerosing cholangitis (PSC), to determine whether certain patterns of intrahepatic bile duct dilatation are suggestive of specific disease processes. Among 30 patients with benign obstructive disease, CT showed pruning of the intrahepatic ducts in four patients (13%), beading in four (13%), and skip dilatations in one (3%). Among 54 patients with malignant obstructive disease, CT illustrated pruning in eight (15%) patients, beading in 11 (20%), and skip dilatations in two (4%). Among 16 patients with PSC, CT demonstrated pruning in four (25%), beading in two (13%), and skip dilatations in five (31%). The majority of patients with malignant or benign obstructive disease or PSC had intrahepatic duct dilatation in both lobes of the liver. It extended into the periphery in 46 of 54 patients (85%) with malignant obstructive disease, in 20 of 30 (67%) with benign obstructive disease, and in 10 of 16 (63%) with PSC. The CT finding of skip dilatations is strongly suggestive of PSC. The CT findings of pruning and beading are nonspecific and may be observed at CT in patients with bile duct obstruction due to a wide variety of causes. The distribution and extent of intrahepatic duct dilatation at CT do not differ among biliary disease processes.

Bile Duct Neoplasms↗

PubMed1991

Root of the superior mesenteric artery in pancreatitis and pancreatic carcinoma: evaluation with CT.

To determine if changes involving the root of the superior mesenteric artery are specific for neoplasm, the authors retrospectively reviewed 173 computed tomographic (CT) examinations of patients with proved pancreatitis (103 examinations) and pancreatic ductal adenocarcinoma (70 examinations). Streaky infiltration of the fat surrounding the root was seen in 27 of 56 examinations of acute pancreatitis, in four of 24 examinations of chronic pancreatitis, in 12 of 23 examinations of pancreatitis complicated by abscess, and in 25 of 70 examinations of pancreatic carcinoma. Periarterial lymph nodes were visible in 14 with acute pancreatitis, in three with chronic pancreatitis, in six with pancreatic abscess, and in 11 with pancreatic carcinoma. A focal mass extended to within 1 cm of the root in 10 with acute pancreatitis, in two with chronic pancreatitis, in four with pancreatic abscess, and in 24 with pancreatic carcinoma; the mass obliterated the periarterial fat in seven with acute pancreatitis, in one with pancreatic abscess, and in 18 with pancreatic carcinoma. Circumferential encasement occurred in one with chronic pancreatitis, in four with pancreatic abscess, in 14 with pancreatic carcinoma, and in none with acute pancreatitis; nearly all cases of encasement revealed loss of periarterial fat. Thus, these indicators are not specific for neoplasm.

Abscess↗

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

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↗

PubMed1987

Nuclear disaster.

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Animal Feed↗

PubMedDate not supplied

MR of focal liver lesions: comparison of breath-hold and non-breath-hold hybrid RARE and conventional spin-echo T2-weighted pulse sequences.

To compare liver lesion detection rates, tissue signal and noise data, and qualitative parameters for breath-hold (BH) and non-breath-hold (NBH) hybrid rapid acquisition with relaxation enhancement (RARE) and conventional spin-echo (CSE) T2-weighted (CSE-T2) MR sequences, 20 patients were imaged using all three sequences. Lesion detection rates were 73.5% for the CSE-T2 sequence and 81.1% and 88.6% for the BH-RARE and NBH-RARE sequences, respectively (P = .027). Mean lesion-to-liver signal-difference-to-noise ratio for the NBH-RARE sequence was 14.0 +/- 11.5, significantly greater than 9.8 +/- 7.8 obtained for the BH-RARE sequence (P = .050) and 9.0 +/- 6.2 obtained for the CSE-T2 sequence (P = .015). The NBH-RARE sequence demonstrated fewer artifacts and greater overall image quality compared to the CSE-T2 sequence. The NBH-RARE sequence is a useful alternative to the liver signal-difference-to-noise ratio and lesion detection rate and better overall image quality.

Adult↗

PubMedDate not supplied

Mechanical lithotripsy of large gallstones: correlation with CT characteristics.

The CT characteristics of gallstones were correlated with mechanical forces required to fragment calculi in vitro. Forty-two gallstones > or = 11 mm in largest diameter were subjected to in vitro CT scanning and categorized as isodense, faint, laminated, rimmed, or dense as compared with saline. A mechanical lithotripter, attached to a dynamometer, was utilized simulating in vivo technique to accomplish lithotripsy. Significantly more force was required to fracture CT-dense (p < 0.02) and CT-rimmed (p < 0.05) gallstones than was required to fracture CT-isodense gallstones.

Gallstones↗