Biomedical subjects
Publications and source records attributed to R K Zeman.
A case of common hepatic duct stricture secondary to hepatic artery chemotherapy infusion is described. CT and endoscopic retrograde cholangiopancreatography (ERCP) may be used in concert to differentiate this entity from other causes of jaundice--namely, hepatic replacement by tumor, porta hepatis adenopathy, and chemotherapy hepatotoxicity.
We prospectively studied 30 patients with postcholecystectomy syndrome to determine the efficacy of biliary scintigraphy in the detection of stenosis of the sphincter of Oddi. All patients underwent endoscopic retrograde cholangiopancreatography (ERCP). Biliary scintigraphy disclosed stenosis of the sphincter by agreement with the ERCP or surgical findings in nine (90%) of ten patients and in eight (100%) of eight patients with biliary obstruction from other causes. Retention of activity at 2 hours in visually prominent ducts was the best predictor of abnormal biliary drainage. Biliary scintigraphy is a useful, noninvasive screening test for the detection of postcholecystectomy biliary obstruction.
Dichromate-induced acute tubular necrosis (ATN) was created in 16 experimental animals and compared with four controls. An increase in cortical echogenicity, greatest on days 4 and 7 after injection, was noted using both histogram analysis and blinded observer readings. These findings closely correlated with proportional outer cortical blood flow. Good interobserver correlation was noted. Based on this experiment, clinical observations, and the literature, we propose that three different entities with different sonographic appearances are included under the term ATN. Drug-induced nephrotoxicity is associated with increased cortical echogenicity; ischemic ATN leads to no change in cortical echogenicity with normal medullary echogenicity; and precipitation of Tamm-Horsfall protein in the pyramids leads to echogenic pyramids with normal cortical echogenicity.
Pancreaticoduodenal lymph node enlargement, regardless of cause, has been a source of imaging confusion because of its propensity to mimic pancreatic malignancy yet not cause biliary obstruction. Thirty-eight patients with pancreaticoduodenal adenopathy were imaged with several methods. Pancreaticoduodenal lymphadenopathy could be distinguished from intrinsic pancreatic abnormality on only 44% (14/32) of CT scans and 54% (6/11) of sonograms. Demonstration of intact tissue planes separating adenopathy from pancreas and, to a lesser degree, extrapancreatic vascular displacement were the most helpful diagnostic signs. Surprisingly, 31% of patients had biliary obstruction. Care must be taken in distinguishing metastatic lymphadenopathy from primary pancreatic tumors. The presence or absence of jaundice should not be considered a helpful sign.
In this article, the pancreas is evaluated with regard to the controversies surrounding this organ from a clinical standpoint, and an approach to imaging modalities is examined. The roles of computed tomography, ultrasound, endoscopic retrograde cholangiopancreatography, and magnetic resonance imaging are put into proper perspective.
The authors present their algorithmic approach to the detection, characterization, and staging of renal masses. Based on classification of urographic findings, the patient may be triaged to the appropriate cross-sectional or invasive imaging modality that will result in the most cost-effective management.
The radiologist needs to be aware of the varied appearance of hepatic mass lesions and be prepared to recommend the most cost-effective imaging approach. In this article, the authors discuss their hepatic imaging experience, common pitfalls, and current recommendations.
Although vast differences exist among the many pelvic malignancies, several unifying concepts emerge from this discussion. First, there is a different role for diagnostic imaging for each type of pelvic malignancy. The radiologist should be aware that although the radiographic findings may be similar, the clinical impact varies greatly with a particular tumor. Second, although clinical staging is notoriously inaccurate, nevertheless diagnostic imaging techniques only improve upon but do not replace it because of false-positive and false-negative results. Third, because of the high false-negative rates of most of the modalities in use, negative studies do not in fact rule out the presence of disease. A surgical procedure may still be needed. Finally, several new techniques, including MRI and transrectal or transurethral ultrasound, may improve the accuracy rates. These developments will probably further enliven the controversies surrounding the radiologic evaluation of pelvic malignancies.
The computed tomographic (CT) and ultrasound (US) appearances of 5 adrenal myelolipomas in 4 patients are reported. The component tissues of a myelolipoma determine its CT and US appearance. A myelolipoma consisting primarily of fat has a characteristic CT and US appearance. A myelolipoma also containing macroscopic quantities of nonfatty material (blood, calcium, or myeloid tissue) may have a nonspecific CT or US appearance if fat is not identified in the lesion. In equivocal cases, needle biopsy may be used to establish the diagnosis of myelolipoma.
Magnetic resonance is a unique, noninvasive imaging modality which allows direct, multiplanar imaging and the possibility of obtaining biochemical information in vivo. Presently, MR appears most applicable to the evaluation of central nervous system abnormalities. The high sensitivity of MR in the evaluation of intracranial pathology suggests that it may eventually replace CT for many suspected diseases, if future investigations are able to improve its specificity. As previously noted, MR may be more diagnostic than other radiologic studies in the evaluation of suspected Chiari malformation, syringomyelia, congenital abnormalities, tumors of the spinal axis, and disc space infection. In the chest, MR appears to be more accurate than CT in the determination of the extent of mediastinal tumor, but at present cannot replace CT because of the lack of experience in imaging parenchymal nodules and benign diseases. MR of the breast is promising, but the size of the lesion may prove to be a limiting factor with magnetic field strengths commonly being utilized. There are inherent difficulties in the evaluation of cardiac disease with MR, but it offers a noninvasive method of investigating congenital heart disease and may provide valuable information in suspected myocardial ischemia and altered cardiac function. MR provides a new method of evaluating the vascular system, both in terms of providing anatomic information on large and medium-sized vessels and flow analysis. In the abdomen, MR appears to be most sensitive in the evaluation of suspected hepatic masses, but as with the brain, greater specificity will be needed to replace CT. At the present time, MR offers no distinct advantage over conventional imaging modalities in the evaluation of pancreatic disease, it maybe more accurate than CT in the staging of renal cell carcinoma. Larger studies are needed to determine the role of MR in the investigation of retroperitoneal adenopathy and adrenal abnormalities. In the pelvis, MR offers the hope of earlier diagnosis of prostatic carcinoma and may replace CT for staging of prostatic carcinoma and transitional cell carcinoma of the bladder. Limited MR experience with benign disease of the female pelvis suggests that it is currently more accurately evaluated with ultrasound. MR appears to be highly sensitive and specific for the diagnosis of avascular necrosis and may provide an early clue in suspected osteomyelitis. Finally, in vivo MR spectroscopy may provide unique metabolic information that was unobtainable prior to the advent of magnetic resonance, if this proves to be technically feasible.
Numerous radiographic and scintigraphic imaging modalities are now available for evaluating the gastrointestinal system. With a well-formulated plan based on patient history, physical examination, and laboratory values, together with knowledge of patient preparation techniques and consultation, an efficient customized approach to gastrointestinal disease can be accomplished.
The interaction between the various noninvasive and invasive imaging modalities used to evaluate the liver, biliary tract, and pancreas is demonstrated in this article. By understanding this interaction and correlating noninvasive studies, the clinician will avoid diagnostic redundancy and the need for invasive testing may be reduced.
Current modalities and techniques used in imaging of the urinary tract offer prompt and accurate diagnoses as well as treatment in some cases. Careful planning and judgement in the choice of the imaging sequence is important in avoiding redundant or ill-advised tests. Individual tailoring will be necessary in some patients. It is hoped that with the rational use of the diagnostic tools now available and with the continued improvement in MRI technology, safe and accurate diagnoses will be expected in practically all patients with diseases of the urinary tract.
Biliary scintigraphy was used to examine 21 patients who had suspected non-iatrogenic biliary trauma. Seven patients (33%) had scintigraphic evidence of biliary leakage. Ultimately, surgical biliary repair was required for only three of these patients. Visualization of the gallbladder did not occur in eight trauma patients, but only one patient was shown to have cholecystitis. In this series, 16 patients had Tc-99m sulfur colloid scans that offered no significant advantage over cholescintigraphy in the detection of hepatic parenchymal defects. Biliary scintigraphy provides clinically useful information in cases both of blunt and penetrating trauma.
The authors examined 139 patients thought to have early, partial, or intermittent biliary obstruction, using sonography, hepatobiliary scintigraphy, and in selected cases contrast cholangiography. Of 125 patients with a well-established final diagnosis, sonography and scintigraphy disagreed in 29 (23%). Scintigraphy revealed early or low-grade obstruction in 13 patients who had no evidence of dilated ductules, while 7 patients with dilatation from prior stone passage or biliary surgery showed normal clearance. The authors conclude that in a preselected population in whom early or low-grade biliary obstruction may be present, disagreement between sonography and scintigraphy is not rare, and the absence of sonographically detectable dilatation does not exclude obstruction.
The sonographic features of 15 histologically confirmed renal oncocytomas in 14 patients are presented. Lesions were evaluated for homogeneity, echogenicity, margination, venous invasion, and nodal enlargement. Nine were less than 5.5 cm in diameter, homogeneous, and well circumscribed. Three lesions were greater than 8 cm in diameter, contained areas of central necrosis or calcification, and were nonspecific for renal oncocytoma. One of these lesions (12 cm) contained a central scar. Two masses were slightly inhomogeneous and, at best, moderately circumscribed. In no case were metastatic nodes or venous invasion present. Since about 6% of renal cell carcinomas may have this appearance, the homogeneous, well marginated renal mass that is isoechoic with cortex and less than 5.5 cm in diameter is as likely to represent renal cell carcinoma as it is an oncocytoma. Although only present in one of the cases, the central fibrotic scar in a larger mass has been described in oncocytoma and may be the most specific feature. Preoperative investigation with fine-needle aspiration biopsy for cytology may be indicated in an attempt to avoid radical nephrectomy in selected patients.
Many invasive and noninvasive imaging modalities are available to image the biliary tract in suspected surgical jaundice. Technical advances in existing techniques and development of new techniques allow biliary obstruction to be detected in its earliest stages. Criteria for the presence of biliary obstruction include anatomic visualization and measurement of both the intrahepatic and extrahepatic portions of the biliary tree. These criteria will be reviewed and potential diagnostic pitfalls discussed. Anicteric dilatation, disparate dilatation, and segmental obstruction of the biliary tract will be discussed as these entities pose a diagnostic as well as therapeutic challenge. The newer endoscopic and percutaneous interventional techniques will be considered and placed in perspective.
Although initially described as representing collateral venous structures, perirenal cobwebs may be due to a variety of benign and malignant conditions. Six representative cases illustrating the broad differential diagnosis are presented.