Edward L. Siegel

Vena caval occlusion after bird’s nest filter placement

BACKGROUND Inferior vena caval thrombosis as a result of intracaval barrier devices occurs in 6.5% of patients with Greenfield filters. The incidence is less well defined in patients in whom birds nest filters have been placed. We reviewed our experience with birds nest filters to determine the incidence of filter-induced caval thrombosis. METHODS The records of 140 patients with birds nest filters were reviewed, living patients were interviewed, and the inferior vena cava examined in 37 patients by duplex scanning. RESULTS Ninety-three patients were available for evaluation. Five of these patients were found to have caval thrombosis by duplex scanning and 2 had clinical symptoms and signs compatible with caval thrombosis. The majority of these patients were on anticoagulants at the time of filter thrombosis. CONCLUSION The incidence of filter-induced vena caval thrombosis in patients with birds nest filters (7%) is comparable with that of Greenfield filters. Because of the catastrophic manifestations of this complication and the increasing application of vena caval filters, the role of these filters in the treatment of thrombotic disease needs further critical evaluation.

The role of transjugular intrahepatic portosystemic shunts in the management of patients with end-stage liver disease*

BACKGROUND Transjugular intrahepatic portosystemic shunt (TIPS) has been reported to successfully treat complications of portal hypertension; however, not all reports have been favorable. METHODS Forty patients underwent 41 attempts to place a TIPS. All patients but 1 had a Wallstent placed. RESULTS Thirty-nine procedures (95%) were successful. Thirty-one patients were treated for gastrointestinal bleeding, and 9 for refractory ascites. The average fall in portal pressure was 13.7 +/- 0.9 mm Hg. Major postprocedure complications included 4 deaths. Minor problems included liver capsular perforation, fever, self-limited bleeding, and a pseudoaneurysm. Follow-up evaluation revealed that by 5 months, 50% of the shunts developed a portal-venous-to-right-atrial pressure gradient requiring balloon dilatation or a new stent. The 1-year actuarial patient survival was 72%. Eighteen patients were candidates for orthotopic liver transplantation (OLT) and 5 have been transplanted. CONCLUSIONS TIPS may be best used for stabilization, prior to OLT or as a temporizing measure prior to elective shunt surgery.

CLINICAL EXPERIENCE IN THE USE OF PHOTOSTIMULABLE PHOSPHOR RADIOGRAPHIC SYSTEMS

The experience with CR systems gained at the three institutions described in this report demonstrates numerous advantages over the conventional screen-film system. These include: (1) a reduction in the radiation exposure delivered to the patient (25% to 50%); (2) a decrease in the number of repeat examinations needed, especially in portable units where technical difficulties are common with screen-film examinations; this is attributable to the linear, wider dynamic range of CR systems compared with screen-film combinations; (3) the capability to archive electronically all images by means of a digital optical storage system; (4) automatic electronic setting of the laser scanner for the latitude and sensitivity on each image; (5) the digital images are available for transmission to all image display workstations on a local or wide-area network; and (6) the ability to adjust interactively the display parameters to best depict images and pathology as well as salvage technically suboptimal examinations. Several disadvantages of CR systems compared with conventional screen-film examinations have also been identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Is the role of transjugular intrahepatic portosystemic shunts limited in the management of patients with end-stage liver disease?

BACKGROUND Transjugular intrahepatic portosystemic shunts (TIPS) are an established method for the treatment of the complications of portal hypertension. Recent reports have suggested that TIPS require frequent follow-up and may interfere with orthotopic liver transplantation (OLT). METHODS Retrospective chart review was performed of ultrasound studies, angiographic studies, and complications of the first 100 patients treated consecutively with TIPS from February 1992 through October 1995. RESULTS Ninety-seven patients had functional TIPS. Thirty-one percent of patients treated emergently survived, significantly less than the 96% survival of elective patients. Fifty percent of the shunts were found to require angioplasty by 5 months. Seventeen patients treated with OLT did well, without intraoperative bleeding problems, and are alive. CONCLUSIONS The TIPS method treats successfully the complications of portal hypertension but requires careful follow-up. The technique may be used prior to OLT. For non-OLT candidates, the cost effectiveness of TIPS versus surgical shunting remains in question.

Use of the External Jugular Vein Approach for Transvenous Liver Biopsy

Transjugular liver biopsy (TJLB) with use of a right external jugular vein (EJ) approach obviates a deep neck puncture, thereby reducing the risk associated with the procedure in patients with severely disordered coagulation. The EJ approach was successful in 21 of 24 consecutive patients referred for TJLB (88%). The approach was unsuccessful in three cases due to thrombosis or congenital absence of the right EJ. TJLB via the right EJ was successful in all cases in which EJ access could be obtained. In the 21 successful cases, the EJ approach simplified the procedure and shortened its duration. There were no procedure-related complications attributable to the EJ approach. The authors now use the EJ route routinely for patients undergoing TJLB and other transjugular procedures in their laboratory. The EJ approach is particularly recommended in patients with impaired coagulation.

Comparison of iodixanol and ioxaglate for adult aortography and renal/visceral angiography: A phase III clinical trial

RATIONALE AND OBJECTIVES We investigated whether iodixanol offers improved safety or tolerance compared with ioxaglate and evaluated whether iodixanol-enhanced radiographs are diagnostically comparable or superior to those produced with ioxaglate. Iodixanol is a new isosmotic hexa-iodinated nonionic contrast agent being evaluated for intravascular use. METHODS Fifty-four adult patients undergoing renal or visceral angiography, aortography, or both were enrolled in a prospective, randomized, double-blind, two-center study in which iodixanol and ioxaglate were compared. Subjects were monitored for adverse events, injection-associated discomfort, and changes in laboratory parameters and vital signs. Efficacy was measured by the overall quality of angiographic enhancement. RESULTS No serious adverse events occurred during this trial. Mild-to-moderate adverse events were more common in patients receiving ioxaglate (p = .041). Injection-associated pain was reported by three patients receiving ioxaglate and none receiving iodixanol (p = .093). Clinical laboratory and vital-sign data showed no differences between groups, and there was no difference in the overall quality of angiographic visualization (p = .711). CONCLUSION Iodixanol resulted in improved safety and patient tolerability while providing images of equivalent diagnostic efficacy compared with ioxaglate.

Iodixanol and ioxaglate in adult aortography and peripheral arteriography: A phase III clinical trial

RATIONALE AND OBJECTIVES This study compared the safety and efficacy of iodixanol with those of ioxaglate in adult patients undergoing aortography or peripheral arteriography. METHODS Forty-six patients were enrolled in this controlled, randomized, double-blind, two-center study. The patients were monitored for adverse events, injection-related discomfort, and trends in laboratory data or vital signs. Diagnostic efficacy was assessed by the quality of contrast enhancement. RESULTS All procedures were diagnostic, with no significant difference in quality of visualization (p = .205). No significant difference was seen in the number of patients experiencing mild or moderate adverse effects (p = .106). Patients receiving ioxaglate reported a significantly greater incidence of injection-related pain (p = .025). CONCLUSION The results of this study support the conclusion that iodixanol at 320 mg I/kg is safe and effective for adult aortography and peripheral arteriography and causes significantly less injection-related pain than ioxaglate.

Image data compression using a new floating-point digital signal processor

A new dual-ported, floating-point, digital signal processor has been evaluated for compressing 512 and 1,024 digital radiographic images using a full-frame, two-dimensional, discrete cosine transform (2D-DCT). The floating point digital signal processor operates at 49.5 million floating point instructions per second (MFLOPS). The level of compression can be changed by varying four parameters in the lossy compression algorithm. Throughput times were measured for both 2D-DCT compression and decompression. For a 1,024×1,024×10-bit image with a compression ratio of 316∶1, the throughput was 75.73 seconds (compression plus decompression throughput). For a digital fluorography 1,024×1,024×8-bit image and a compression ratio of 26∶1, the total throughput time was 63.23 seconds. For a computed tomography image of 512×512×12 bits and a compression ratio of 10∶1 the throughput time was 19.65 seconds.

HARDCOPY RECORDING TECHNOLOGIES FOR DIGITALLY FORMATTED IMAGE DATA

The hardcopy recording technologies of video cameras, slow-scan (digital spot) recorders, and laser film printers are presented and compared. Slow-scan (digital spot) recorders offer a few advantages when compared with multiformat video cameras. But only laser film printers provide the high-quality hardcopy recordings and speed required by newer digital imaging modalities.