Abstract No. 384: Inaccessible postoperative abdominal abscess: a new percutaneous drainage technique

Abstract No. 384: Inaccessible postoperative abdominal abscess: a new percutaneous drainage technique

JVIR 䡲 Poster Sessions S153 Purpose: To develop exposure-response relationships in an ex vivo porcine model using a Dual Mode Ultrasound Array (DMUA...

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JVIR 䡲 Poster Sessions

S153

Purpose: To develop exposure-response relationships in an ex vivo porcine model using a Dual Mode Ultrasound Array (DMUA), and correlate DMUA imaging with histopathology. Materials and Methods: Fresh degassed kidneys were stabilized and coupled to a 64-element 3.5 MHz fenestrated DMUA prototype, housing a central 7.5 MHz diagnostic probe. Real-time DMUA and B-mode images were co-registered for comparison. Intensities between 4.0 –10.3 kW/cm2 were delivered at a set depth into the tissue with increasing durations from 250 –1,000 msec and performed in triplicate. Additionally, a set exposure was performed at 2mm increments into tissue to evaluate the effects of attenuation. Kidneys were sectioned and placed in formalin. High resolution images were taken of fresh gross lesions as well as H&E sections and evaluated using Image J. Lesion size and evidence of cavitation were recorded. Results: Exposure of 4.0 kW/cm2 with 500 msec duration achieved tissue coagulation without cavitation, and did not generate an echogenic change on imaging. Tissue coagulation, cavitation and observable echogenic changes occurred at exposures ⱖ 7.3 kW/cm2 with 250 msec duration. Uncontrolled cavitation and irregularly shaped lesions began to occur at an exposure of 7.3 kW/cm2 between 500-750 msec. Lesions ranged from 0.15.8mm2. Increasing depth resulted in less coagulation. Echogenic changes seen on DMUA during lesion formation were more characteristic than those on B-mode of actual lesion shape. The gross lesions correlated well with coagulation seen at histology. Conclusion: Exposure parameters were defined for thermal lesion formation with enough cavitation activity to produce an observable echogenic change on real time DMUA and B-mode imaging. Increasing depth required more power to generate comparable lesions. DMUA imaged the lesions more accurately than B-mode. Actual coagulation seen on histologic examination correlated well with lesion formation observed on both DMUA imaging and gross sectioning.

Musculoskeletal Educational Exhibit

Abstract No. 383

Epidural injection complications: a case-based review E. Antypas1, R. Greene1, R. Silbergleit1, R. Silbergleit2, A. Ortiz3, W. Wong4, J. Handel1; 1Beaumont Health System, Royal Oak, MI; 2University of Michigan, Ann Arbor, MI; 3Winthrop University, Long Island, NY; 4 University of California, San Diego, San Diego, CA

Nonvascular Interventions Abstract No. 384 Inaccessible postoperative abdominal abscess: a new percutaneous drainage technique S. An, C. Yoon, Y. Woo, N. Seong, Y. Kim, Y. Kim, J. Park; Seoul National University Bundang Hospital, Seongnam-si, Republic of Korea Purpose: To assess the technical feasibility and clinical effectiveness of a new percutaneous drainage technique for inaccessible postoperative abdominal abscesses. Materials and Methods: Between April 2005 and April 2011, 14 patients (M:F⫽12:2, mean 58.9 years) underwent percutaneous drainage for inaccessible (subphrenic [n⫽6] and peripancreatic [n⫽8]) postoperative abdominal abscess. In eight patients with indwelling surgical drains, the clogged surgical drains were percutaneously punctured under fluoroscopy guidance. In six patients without indwelling surgical drains, subcutaneous fibrous tracts of previous surgical drains were punctured under US guidance. After guidewires were passed along the surgical drains and fibrous tracts, pigtail drainage catheters (8.5–10.2 F) were placed into the abscess cavities over the guidewires. The medical records were retrospectively reviewed to determine technical success of the procedure, effectiveness of drainage, catheter indwelling duration, and complications. Results: Drainage catheters were successfully placed into the abscess cavities in 13 (92%) patients. In one patient, US-guided puncture of fibrous tract failed. Clinical improvements were evident within 7 days in the 13 patients with successful catheter placement. The abscess cavities were completely obliterated on one-month follow-up CT. The catheter indwelling durations were 18 –57 days (mean 31) in 8 patients with enteric fistulas and 2–24 days (mean 12) in 5 patients without fistulas (p⬍.05). There was no procedure related complication or recurrent abscess during follow-up period (4 –34 months, median 20). Conclusion: Percutaneous drainage using surgical drains or subsequent fibrous tract is a feasible and effective technique for inaccessible postoperative abdominal abscesses. The presence of enteric fistula is associated with prolonged catheter indwelling duration.

Poster Sessions

Learning Objectives: The purpose of this exhibit is to present, in a case-based format, a series of potential complications following epidural injections and catheter placements and provide imaging characteristics that will aid in their recognition and timely diagnosis. Background: Epidural procedures, including epidural steroid injections (ESI) and epidural analgesia catheter (EAC) placement have been shown in the literature to be safe and effective procedures. However, there are several potential complications the operator and/or radiologist need to be able to recognize. Recognition of these complications during the procedure and on post-procedure imaging is important to prevent further morbidity and mortality. Clinical Findings/Procedure Details: A series of epidural injection complications were identified over 10 years and a retro-

spective chart review was performed to obtain clinical history and outcome. We included complications following ESI and EAC. Imaging modalities include MRI, CT and CT myelography. We present the imaging findings and clinical scenarios of five separate categories of complications. These complications include epidural hematoma, osteomyelitis/diskitis, epidural abscess, direct spinal cord puncture and pneumocephalus. Conclusion and/or Teaching Points: Epidural procedures have become a useful and widespread therapy in modern medicine because of their effectiveness in the management of pain and radicular symptoms. To avoid a delay in diagnosis, radiologists need to be aware of potential complications and recognize both their clinical symptoms and imaging characteristics. It is hoped that after review of our case-based educational exhibit, the Radiologist will have a clearer understanding of the potential complications of ESI and EAC and, thus, help prevent future morbidity and mortality from these procedures.