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B S Garra

Publications and source records attributed to B S Garra.

At least 37 records · Page 2Linked to original sources
PubMed1992

A comparison of case retrieval times: film versus picture archiving and communications systems.

One of the advantages that a picture archiving and communications system (PACS) is supposed to provide over a film-based operation is improved performance in retrieving images. Although it seems self-evident that this should be so, this experiment was intended to verify this and to provide some time comparisons for the two methods. The experiment consisted of randomly selecting ultrasound and computed tomography cases and determining how long it took to retrieve files at a PACS workstation or in person from the file room. To simulate actual retrieval volumes, a total of 40 cases from current to 6 months old, 20 cases from the past year, and 10 cases more than 1 year old was selected. Results indicate that PACS retrieval can indeed be faster than file room retrieval. However, the difference is less for recent cases than for older cases. For cases 6 or fewer months old, the workstation retrieval was approximately 2.5 minutes faster per case than the film file room. This time difference increased markedly when extended to the 1-year and older-than-1-year groups. This report details the results of this study and provides information about the reliability of the two archives.

Filing↗
PubMed1992

PACS clinical experience at Georgetown University.

Georgetown University Hospital has been operating an image management and communications system (IMACS or PACS) for 3.5 years. This work was initially funded under the Army Medical Research and Development Command Digital Imaging Network Systems (DINS) project. The system was taken from a research system supporting only radiology tasks to one extended to clinical use, and has been used in clinical work for 3 years. This paper will summarize our PACS clinical experience and will describe the operational features implemented and those still necessary.

Computer Systems↗
PubMed1992

Intraoperative bile duct sonography during laparoscopic cholecystectomy: experience with a 12.5-MHz catheter-based US probe.

During elective laparoscopic cholecystectomy, 20 patients underwent intraoperative evaluation of the biliary tract with a commercial 6.2-F, 12.5-MHz catheter-based ultrasound (US) probe. The study tested the feasibility of this technology for mapping the anatomy of the hepatoduodenal ligament and Calot triangle, assessing bile duct integrity, and detecting choledocholithiasis. The duct was studied with a transmural approach, the catheter being placed parallel to, but remaining outside, the bile duct. The common hepatic duct and common bile duct in the vicinity of the cystic duct were seen in all 20 patients; the junction of the cystic duct with the common hepatic duct was seen in nine patients (45%). After the cystic duct was clamped, no sonographic evidence to suggest bile duct injury was noted in any patient. The transmural imaging approach was tested in four pigs in whose common bile duct a single human calculus had been placed. In all instances the size and location of the calculus were accurately detected. Intraoperative US with a catheter-based system is a safe and effective means for interrogation of the extrahepatic biliary tree during laparoscopic cholecystectomy.

Adult↗
PubMed1992

Parameters for predicting electromagnetic lithotripter failure: quality assurance implications.

Despite the extensive use of lithotripsy for treating renal and biliary calculi, there has been little data reported regarding the causes and manifestations of lithotripter failure. The clinical and service records for 145 consecutive treatments performed with the Siemens Lithostar Plus were reviewed. Service record analysis revealed eight failures of shock wave generation during a 10-month period. Six of these failures were subtle and still allowed shock wave generation. There were five in-line ultrasound probe failures during this period. The most useful clinical parameter for predicting lithotripter failure was reduced severity of sonographically evident cavitation bubbles during treatment. Lack of stone fragmentation and unexpectedly low analgesia requirements at high-power levels were less useful in predicting lithotripter failure. All clinical parameters suffered from nonspecificity. Preliminary experience, with an ongoing quality assurance program using a test object hydrophone, suggests this is a useful method of predicting lithotripter function and avoiding compromised treatments.

Equipment Failure↗
PubMed1991

Evaluation of STIR imaging as a complement to spin-echo MR and CT of the porta hepatis/hepatoduodenal ligament.

Short TI inversion-recovery (STIR) imaging provides specific advantages over standard spin-echo (SE) MR sequences by producing additive effects of T1 and T2 brightening of pathology and suppression of the signal from surrounding fat. We retrospectively evaluated 12 patients with abnormalities, primarily neoplastic, of the porta hepatis/hepatoduodenal ligament (PH/HdL) with CT and MR imaging, including SE and STIR imaging. Masses on CT were of slightly decreased density compared to liver and seen in contrast to surrounding fat in the PH/HdL region. On MR, T1-weighted images provided comparable anatomic detail to CT, with masses clearly distinguished from surrounding fat due to the low signal intensity of masses as compared to fat. T2-weighted images clearly depicted intrahepatic lesions because of their high signal intensity relative to liver. Increased signal in extrahepatic lesions made them less distinctly seen from surrounding fat. STIR images best demonstrated tumor relative to fat. In six cases, CT was equivalent in demonstrating pathology to the best MR sequence. At least one MR sequence demonstrated pathology better than CT in 6 of 12 cases. In five of these six cases, the STIR sequence was better than CT. Thus, MR, particularly STIR imaging, provides a useful technique in imaging of PH/HdL pathology.

Adult↗
PubMed1991

Gallstone lithotripsy: relevant physical principles and technical issues.

A basic understanding of shock wave generation is essential for the radiologist who performs gallstone lithotripsy. Shock waves differ from ordinary acoustic waves in that they have a rapid rise time, a positive pressure component that gives rise to compressive forces approaching 1,000 atm, and a low-amplitude sustained negative pressure (rarefactive) component. Shock waves are created by means of three different types of shock wave generators: spark-gap, electromagnetic, and piezoelectric. The authors describe and compare these three types of shock wave generators with regard to equipment selection. Regardless of how shock waves are generated, they share common interactions with tissue. These interactions are reviewed along with the proposed mechanisms of stone fragmentation.

Cholelithiasis↗
PubMed1991

Gallbladder varices: imaging findings in patients with portal hypertension.

A retrospective review of the medical and imaging records of 50 patients with portal hypertension examined in the authors' department during a 2-year period identified six patients with gallbladder wall varices. Imaging studies performed in these patients included computed tomography (CT) (four patients), duplex and color Doppler flow (five patients), and magnetic resonance (MR) (four patients). Five of six patients with gallbladder varices had portal vein thrombosis. Anechoic areas within the gallbladder wall detected with ultrasonography could be distinguished from intramural edema by using duplex or color Doppler flow imaging in all five patients in whom it was used. Contrast material enhancement of these varices was detected with CT in three patients, two of whom also had adjacent mesenteric collaterals. Gradient-echo MR imaging (fast imaging in steady precession/fast low-angle shot) showed flow-related enhancement within the gallbladder wall in two patients. The presence of gallbladder wall varices may imply the presence of portal vein thrombosis. Since these varices can be a source of major blood loss, surgeons must be made aware of them when operating on patients with portal hypertension.

Adult↗
PubMed1991

Gallstone fragmentation during biliary lithotripsy: effect of stone composition and structure.

In vitro lithotripsy with the Siemens Lithostar was conducted on 36 radiolucent or minimally calcified gallstones housed in an anthropomorphic phantom. The ease and pattern of fragmentation were correlated with global composition for the entire stone, regional or microcomposition (determined by Fourier-transform infrared spectroscopy), and microstructure (determined by scanning electron microscopy). Stones made up of more than 62% cholesterol required 50% more shock waves to pulverize all fragments to 0.3 cm or less than did stones of less than 62% cholesterol (p less than .01). An inverse relationship was found between the number of shock waves needed for fragmentation and the cholesterol content (r = .77). Although a broad range of fragmentation responses occurred, little variation was seen in the ease of fragmentation within stone families. The majority of stones fractured along radially oriented cholesterol plates, but one third of stones treated showed initial chipping or flaking at the periphery before radial fracture. This type of peripheral erosion most often occurred in stones with peripheral pigment rims. These stones required more shock waves and lagged in pulverization compared with more homogeneous cholesterol stones. The efficiency of fragmentation during biliary lithotripsy correlates with the stones' global cholesterol content. A stone's architecture, as reflected by its regional composition and microstructure, partially predicts the mechanism of fragmentation. These in vitro data may be useful in further refining criteria for selecting patients and understanding the fragmentation process.

Bile Pigments↗
PubMed1991

MR imaging of the portal venous system: value of gradient-echo imaging as an adjunct to spin-echo imaging.

We evaluated the use of gradient-echo (GRE) as an adjunct to spin-echo (SE) MR imaging of the portal venous system. GRE imaging was performed in 31 subjects, 15 normal volunteers and 16 patients with documented portal venous disease (15 cases) or suspected disease (one case). Eight of 16 patients had venous thrombosis, five had focal thrombus, and three had complete occlusion. Six patients had extrinsic venous compression by tumor. Of the two other patients, one had an arteriovenous fistula and the other a falsely positive angiogram, suggesting portal vein occlusion. In normal subjects, GRE scans had excellent visualization of the portal venous system with high intravascular signal compared with surrounding tissues. Nine (60%) of 15 normal subjects and three patients had an artifact consisting of a curvilinear area of decreased signal that could mimic clot. In three of five patients with focal thrombus, clot was identified on GRE but not on SE images. In all three patients with occlusion, SE and GRE images demonstrated similar findings. In five of the six patients with extrinsic venous compression by tumor, SE and GRE studies showed similar findings. Of the two patients, an arteriovenous fistula was seen on GRE MR in one, and in the other, patency of the left portal vein was seen on SE and GRE images after angiography had suggested portal vein occlusion. Collateral vessels were seen in nine of 16 patients. In five of nine cases, GRE MR demonstrated more extensive collaterals than did SE MR. In summary, GRE MR provides a useful adjunct to standard SE MR imaging. Benefits include high contrast between vascular structures and surrounding tissues, reduced motion artifact, and rapid scanning within a breath-hold.

Adolescent↗
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

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

Quantitative ultrasonic detection and classification of diffuse liver disease. Comparison with human observer performance.

A multiparameter ultrasonic tissue characterization system has been developed and tested on several types of diffuse liver disease. The four tissue characterization parameters used are based on the first and second order statistics of the B-scan image. Performance of the system was evaluated using receiver operating characteristic (ROC) analysis and was compared with the performance of experienced human observers viewing B-scan images. The machine-based multiparameter system achieved an area under the ROC curve (Az) of 0.88 for detection of chronic hepatitis in more than 100 proven cases of the disease. This was dramatically better than the performance of human observers (Az = .64, P less than .05) and compares favorably to the performance of other accepted diagnostic tests such as head CT and the PAP smear. For detection of Gaucher's disease, the Az for the system was .92, whereas for separating hepatitis from Gaucher's disease Az was .84. Human observers also did well at these tasks (P greater than .8) using organomegaly as their major criterion for diagnosing Gaucher's disease. For primary biliary cirrhosis the system Az was .80, for glycogen storage disease Az was .94. These results suggest that use of multiparameter tissue characterization can significantly increase the usefulness of ultrasound for evaluation of diffuse liver disease.

Gaucher Disease↗
PubMed1989

Interleukin-2 induces profound reversible cholestasis: a detailed analysis in treated cancer patients.

Interleukin-2 (IL-2)-based immunotherapy is associated with profound reversible cholestasis and hyperbilirubinemia. We performed a nonrandomized retrospective and prospective analysis to determine the incidence, characteristics, clinical course, and nature of the IL-2-induced liver dysfunction in patients with cancer. Patients received IL-2 at a dose of 20,000 to 100,000 units (U)/kg thrice daily for up to 5 days. Fifty-one patients on adjuvant treatment protocols received a mean of 10.18 +/- 2.38 IL-2 doses and 11.67 +/- 4.16 doses were delivered to 210 patients with advanced disease during this period. Retrospective analysis of all patients receiving this therapy revealed increases in the following liver function tests expressed as median, 25th percentile, and 75th percentile (range): bilirubin (mg/dL) 4.5, 2.6, 6.5 (.4 to 38.5); alkaline phosphatase (U/L) 256, 179, 378 (56-1680); SGOT (U/L) 80, 52, 117 (18 to 483); SGPT (U/L) 91, 64, 132 (20-540); prothrombin time 13.4, 12.8, 14.5 (10.8 to 35.4); and albumin (g/dL) values decreased (trough) slightly 3.0, 2.8, 3.2 (2.3 to 3.8). Multiple regression analysis revealed several factors that were significantly associated with the increase in bilirubin when jointly considered (model P2 less than or equal to .001) including total IL-2 dosage, increase in creatinine, alkaline phosphatase, weight, and SGOT. Similar increases were noted in a prospectively evaluated group of 10 patients. A return to normal levels of bilirubin was noted within 5.6 days of stopping IL-2. Fasting serum cholylglycine increased from a mean of 32.3 +/- 1.6 to a peak of 1556.0 +/- 625.0 mg/mL. Although conventional ultrasound examinations were unrevealing, tissue ultrasound examinations revealed a mean scatterer spacing (MSS) increase compared to baseline of .10 +/- .04 (P less than .02) suggesting hepatic edema or an infiltrative process. Further, computerized hepatobiliary nuclear medicine scans revealed a delay in uptake (2.2 +/- 0.5 fold greater) and excretion (8.0 +/- 5.9 fold greater) of technetium-99m labeled disofenin. These findings support the development of profound reversible cholestasis as the primary basis for the elevated bilirubin in patients undergoing IL-2 treatment and may have implications for understanding the jaundice observed in some patients postoperatively as well as that associated with sepsis and other inflammatory disorders. Specifically, the release of IL-2 or the induction of other factors similarly induced by IL-2 may be responsible for these findings. Tissue ultrasound and computerized hepatobiliary scans provide additional noninvasive assessments of liver function and physiology.

Bilirubin↗