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R K Zeman

Publications and source records attributed to R K Zeman.

At least 73 records · Page 4Linked to original sources
PubMed1991

Gallstone lithotripsy: results when number of stones is excluded as a criterion for treatment.

The Siemens Lithostar Plus protocol (Siemens Medical Systems, Iselin, NJ) allows investigators to perform gallstone lithotripsy on patients regardless of the number of stones they have, provided the stones occupy less than 50% of the gallbladder lumen. The purpose of this study was to determine the interrelationships between stone burden, fragmentation response, and stone-free rates when treatment is not limited to three stones or fewer. Of 200 patients initially examined, 80 (40%) underwent lithotripsy. The mean number of treatments per patient was 2.1, and the mean number of shock waves per patient was 7386. In 60 patients in whom 6-month follow-up was available, the overall stone-free rate, based on actual results, was 32% (19/60). The stone-free rates for solitary stones, two or three stones, and four or more stones were 50%, 12%, and 26%, respectively. Regardless of number of stones, patients who ultimately became stone free had significantly smaller mean fragment size (0.25 cm) 2 weeks after lithotripsy than did those who did not become stone free (0.51 cm). Retrospective volume analysis showed that seven (47%) of 15 patients with multiple stones occupying less than 2000 mm3 were stone free; none became stone free when this volume was exceeded. Lithotripsy remains a practical option for patients with solitary stones. Comparable stone-free rates to those achieved for solitary stones can be obtained in patients with multiple stones, regardless of their number, provided treatment is aggressive and the stone aggregate is less than 2000 mm3.

Adult↗
PubMed1991

Improved detection of small cavernous hemangiomas of the liver with high-resolution three-headed SPECT.

The purpose of this study was to review our experience with 99mTc-red blood cell scintigraphy for diagnosis of cavernous hemangiomas of the liver using a new three-headed, high-resolution dedicated SPECT system. Of 19 patients referred with a total of 38 lesions seen on CT, US, or MRI, 14 patients had 24 lesions that were hemangioma-positive with SPECT (all true-positives). Six of these 14 patients also had 9 hemangioma-negative lesions; all were less than or equal to 1.3 cm in size and false-negative. The remaining five patients had hemangioma-negative lesions only (1 false-negative, 4 true-negatives). Two hemangiomas were seen by SPECT that were not detected by CT, US, or MR. The sensitivity for hemangiomas greater than or equal to 1.4 cm. was 100% (20/20). The sensitivity was 33% for lesions 0.9-1.3 cm, and 20% for lesions less than or equal to 0.8 cm. The smallest hemangioma detected was 0.5 cm. These results show a definite improvement in sensitivity with high-resolution triple-headed SPECT over previously reported results using single-headed SPECT. High-resolution SPECT has improved our ability to detect small cavernous hemangiomas of the liver.

Erythrocytes↗
PubMed1991

Gallbladder imaging. The state of the art.

Cholelithiasis and its sequelae are readily identified by the myriad imaging techniques available. Understanding the technical issues and correlation of specific findings with the clinical symptoms is essential for accurate diagnosis.

Acute Disease↗
PubMed1990

Visibility of gallstone fragments at US and fluoroscopy: implications for monitoring gallstone lithotripsy.

To assess the value of ultrasound (US), fluoroscopy, and spot radiography in the detection, counting, and measurement of gallstone fragments during lithotripsy, in vitro visibility studies were conducted on fragments from 20 stones. Fluoroscopic visibility was evaluated during and after lithotripsy on 185 fragments placed in an anthropomorphic phantom. Three US experiments were performed on the fragments to study the visibility of fragments as a function of size, the accuracy of the count with large numbers of fragments, and the ability of observers to detect and count fragments larger than both 4 mm and 5 mm. With fluoroscopy, fragment detection rates ranged from 20% (fragments larger than 2.5 mm) to 80% (fragments larger than 4.5 mm). With US, all fragments larger than 1.5 mm were detected, and US was significantly better than fluoroscopy and spot radiography for detection of fragments 2.5 mm or smaller. US was also more accurate than fluoroscopy (11% vs 59% error) in the assessment of the number of fragments. When fragments larger than 4 mm or 5 mm were being counted with US, 92% of the fragments were visualized. The results suggest that US is more accurate for monitoring gallstone lithotripsy than fluoroscopy or spot radiography.

Cholelithiasis↗
PubMed1990

Relationship between stone motion, targeting, and fragmentation during experimental biliary lithotripsy.

In vitro experiments in an anthropomorphic phantom were performed to clarify the relationship between stone motion, targeting, and fragmentation. Stone motion was minimized by pinning the stone against the dependent wall of a mock gallbladder cavity during shock wave treatment. Fragmentation was most effective (probably due to increased cavitation effects) when the shock wave traversed fluid at the point of its impact with a stone. The results suggest that treatment with the patient in the supine or oblique position may produce a better outcome than treatment in the prone position. Buoyant stones exhibited the greatest motion, which was often to-and-fro in nature. Although restricting the size of the mock gallbladder cavity reduced stone motion, maintaining a 1-cm fluid path was beneficial for achieving optimal pulverization.

Cholelithiasis↗
PubMed1990

Cavitation effects during lithotripsy. Part I. Results of in vitro experiments.

Cavitation effects and microbubble formation are due to the rarefactive (negative pressure) component of shock waves. The in vitro application of shock waves generated by a commercial lithotriptor to an anthropomorphic phantom showed that stone fragmentation occurred more completely in fluid media that support cavitation than in a solid agar-graphite gel. Various fluids (saline, iodinated contrast material, bile) supported different degrees of cavitation. Bile exhibited cavitation at low energy and gave rise to intense microbubble formation at 19 kV. Cavitation increased dramatically with an increase in the rate of generation from 1.0 to 1.8 shock waves per second. The authors conclude that during biliary lithotripsy the environment of a stone will influence the extent of cavitation and fragmentation.

Cholelithiasis↗
PubMed1990

Cavitation effects during lithotripsy. Part II. Clinical observations.

Cavitation effects during biliary lithotripsy can produce sonographically visible microbubbles. The relationship between microbubble formation and clinical outcome of gallstone lithotripsy performed with a commercial lithotriptor was studied in 50 treatments in 29 patients. Microbubble formation in bile was a useful predictor of successful stone fragmentation in 31 of 34 treatments. Microbubble formation in the liver correlated with transient hepatocellular damage (as indicated by a twofold rise in serum transaminase levels) immediately after seven of 10 treatments. Advancing the focal volume of the lithotroptor deeper into the patient (placing the stone at the proximal point of the focal zone) may be a useful strategy for reducing hepatic cavitation effects, which appear to be responsible for temporary hepatocellular damage.

Adult↗
PubMed1989

Environmental designs for reading from imaging work stations: ergonomic and architectural features.

Despite the rapid progress made in the electronic design of imaging work stations for medicine, much less effort has gone into the design of environments in which such systems will be used. Based on studies of radiologist film reading sessions, considerable time will be spent working at such viewing systems. If the rooms in which the work stations are placed are not conducive to comfortable work, it will certainly not favor electronic viewing over film reading. In examining existing reading environments, it is also apparent that they are not optimal, even for film. Since some of the problems for film and electronic viewing overlap, such as heat generation (by the alternators, viewboxes, or work station electronics) and glare from light sources, it should be possible to develop solutions that are applicable to both environments, or to rooms that will feature both viewing systems. This paper will discuss some of the approaches to designing environments in which viewing of images is supported by the room architecture and engineering, rather than being degraded by it. To illustrate these points a design, based on the constraint of a real room size and available architectural materials, will be developed.

Architecture↗
PubMed1989

Rhabdomyolysis: need for high index of suspicion.

Rhabdomyolysis, both traumatic and nontraumatic, may be defined as a triad of skeletal muscle injury, pigmented urine, and acute renal failure. Nontraumatic rhabdomyolysis may be more of a subtle diagnosis and requires a high index of suspicion. Pertinent findings in the history as well as clinical evidence of muscle injury with a marked elevation of creatinine kinase will suggest the diagnosis. A disproportionate elevation of serum creatinine to blood urea nitrogen may also occur. Treatment consists of adequate hydration to help prevent oliguric or anuric renal failure without additional calcium or bicarbonate supplementation in most cases. Radiologic studies involving intravenous contrast media as well as urologic instrumentation should be avoided in the acute setting. With early diagnosis and prompt treatment the prognosis for recovery is excellent.

Acute Kidney Injury↗
PubMed1989

Primary carcinoma of the gallbladder: a pictorial essay.

This paper is an overview of the imaging characteristics of primary carcinoma of the gallbladder, based on the premise that more general knowledge of the imaging patterns of the primary tumor and its modes of spread might increase the likelihood of accurate preoperative diagnosis of this lesion. Primary tumor patterns discussed and illustrated are: (I) an intraluminal mass, (II) focal or diffuse thickening of the gallbladder wall, and (III) replacement of the gallbladder by a mass. Illustrated patterns of tumor spread include direct extension and lymphatic and hematogenous metastases.

Adenocarcinoma↗
PubMed1989

Infected abdominal tumors: percutaneous catheter drainage.

Sixteen patients underwent percutaneous catheter drainage of infected primary (n = 9) or metastatic (n = 7) abdominal tumors. Twelve of the patients improved clinically, as evidenced by defervescence and decrease or normalization of leukocytosis. Four patients did not respond to catheter drainage and required surgery. Three of the twelve who improved underwent operations for attempts at surgical cure or debulking of tumor volume despite an initial "good" response to percutaneous drainage. Of the nine patients who did not undergo surgery after percutaneous drainage, four underwent catheter removal after 5 weeks of drainage and had no recurrence of infection, two remained alive with the catheter in place up to 8 months and 1 year after drainage, and two died with the catheter in place. One patient had the catheter removed inadvertently after 3 weeks of drainage and had recurrences that required replacement of the catheter until his death. The major differences between drainage of necrotic tumors and drainage of standard abscesses were the need for surgery in the majority of the cases and the fact that patients needed the catheters for continued palliation until their death.

Abdominal Neoplasms↗
PubMed1989

CT evaluation of suspected hepatic metastases: comparison of techniques for i.v. contrast enhancement.

Although IV injection of contrast material is widely used for detection and follow-up of hepatic metastases on CT, the optimal method of contrast enhancement has not yet been defined. A prospective study was performed in 50 consecutive patients with suspected hepatic metastases. Lesion size and detectability were compared on unenhanced CT scans, scans obtained during a bolus injection of contrast material (early bolus phase), and scans obtained during a rapid infusion after the loading bolus. A total of 60 hepatic lesions were evaluated in 26 patients, 19 with histologic confirmation of metastases and seven with strong supportive evidence. The bolus phase allowed detection of 15% more lesions than did examination during the rapid-infusion phase. Lesion size varied, depending on the timing and method of contrast administration; the largest measurements were obtained during bolus injection of contrast material. In addition, bolus administration of contrast material subjectively resulted in the best lesion detection. Because the three techniques of IV contrast enhancement may produce different size measurements, sequential examinations must be tailored appropriately. Scanning during the bolus phase is technically possible with current CT equipment and is recommended as the primary CT screening examination for hepatic metastases.

Contrast Media↗
PubMed1989

A marked guide wire facilitates esophageal dilatation.

Esophageal dilatation by endoscopists is a commonly performed procedure. The introduction of tapered polyvinyl dilators by Savary has made the procedure even more popular. In the United States, esophageal dilatation with guide wires has been traditionally performed with fluoroscopy. By using a marked guide wire and by adhering to specific safety guidelines, the passage of the guide wire can be precise, even without fluoroscopy, and radiographic definition is not always required. This study describes the new guide wire and the technique.

Dilatation↗
PubMed1988

Pancreatic pseudotumors associated with multifocal idiopathic fibrosclerosis.

Two patients with multifocal idiopathic fibrosclerosis and sclerosing cholangitis developed biliary obstruction due to a fibrotic pancreatic pseudotumor. The masslike fibrosis mimicked pancreatic carcinoma on sonography and cholangio-pancreatography. In one patient sonography was successfully used to assess the response of the pseudotumor to corticosteroid therapy.

Cholangitis↗
PubMed1988

Renal cell carcinoma: dynamic thin-section CT assessment of vascular invasion and tumor vascularity.

Dynamic thin-section computed tomography (CT) was used to evaluate renal cell carcinoma in 80 patients. The lesion was correctly staged with CT in 90% of patients. With use of the dynamic technique, the ipsilateral renal vein was depicted in 99% of patients. Extension of the tumor to the renal vein or the inferior vena cava was correctly detected in 18 of 19 patients. Actual depiction of tumor thrombus was a far more accurate indicator of renal vein invasion than was the identification of isolated renal vein enlargement. Dynamic thin-section CT of the kidney should be considered the routine method for comparison studies with other newer cross-sectional techniques in the evaluation of renal cell carcinoma.

Carcinoma, Renal Cell↗
PubMed1988

Pancreas divisum: thin-section CT.

Twelve patients with known pancreas divisum underwent thin-section computed tomography (CT) to determine the capability of CT to depict this pancreatic anomaly. Focal pancreatic enlargement was present in five patients. Two distinct pancreatic moieties separated by a fat cleft were noted in three patients; a fourth patient had focal atrophy in the distribution of the dorsal pancreas. The two pancreatic moieties were identified at the same craniocaudal level in all four of these patients. The dorsal duct was depicted in all 12 patients, while the short ventral duct was seen in only five of the 12 patients. Failure of the ventral and dorsal pancreatic ducts to fuse was identified in all five patients in whom both ducts were seen. CT may not enable specific diagnosis of pancreas divisum in the majority of patients. If, however, distinct pancreatic moieties or unfused ductal systems are evident, the diagnosis may be confidently suggested.

Adult↗
PubMed1988

CT of the liver: a survey of prevailing methods for administration of contrast material.

The members of the Society of Body Computed Tomography were surveyed to determine the most frequently used method of administering contrast material in CT studies of the liver. The respondents represented CT departments performing liver examinations in 22 institutions. No department relied solely on noncontrast scans. In 12 (54%) of 22 institutions, only contrast-enhanced scans were performed. The preferred dose for enhancement was 150 ml of 60% contrast material. Eight (36%) of the 22 respondents obtained images during the administration of a bolus of contrast material, whereas nine (41%) obtained images during the administration of a sustained drip infusion given after a loading bolus. Follow-up in 1987 revealed that two departments had switched to obtaining images during the administration of a bolus. The availability of CT power injectors and refinements in the rapid-scanning capabilities of CT scanners have increased the popularity of obtaining images of the liver during the administration of a bolus of contrast material. Despite this, in many departments, contrast material is still administered via drip infusion in CT studies of the liver.

Contrast Media↗