Materials and Methods: Contrast was injected mtravenously, with image acquisition started at three times the circulation time to ensure adequate mixing. Axial CT images of the pelvis and lower extremities were then obtained to evaluate for deep venous thrombosis. Ultra- sound was also performed to compare the accuracy of CT diagnosis.

Results: The presence of deep venous thrombosis produces a spectrum of findings which will be described. There is good correlation between the accuracy of CT and ultrasound in deep venous thrombosis diagnosis. Conclusion: The CT signs produced by lower extremity deep venous thrombosis are consistent and accurate. CT evaluation may be helpful in the sonographically difficult patients as well as patients receiving multiple pelvic scans who are at high risk for deep venous thrombosis.

P-19 Epidural Anesthesia for Pain Control in Uterine Artery Embolization Hadeer H. Shaikhly, MD, University of Connecticut Health Cen- ter, Farmington, CT, Robert S. Feld, MD, Ducksoo Kim, MD, Michael R. Tesoro, MD, Mark Wolf, MD Purpose: To evaluate the effectiveness of epidural anesthesia in pre- venting or limiting the pain occurring during and several hours after uterine artery embolization (UAE). Materials and Methods: Intravenous narcotics, often with a patient-control pump, and parenteral anti-inflammatory agents have been the mainstay of pain management m fibroid embolotherapy in large reported series, with epidural anesthesia used occasionally. Im- pressed with the results of epidural anesthesia, we began to use this method of analgesia routinely and herein report the pain response of patients undergoing UAE in whom epidural anesthesia was the sole or primary analgesic technique. After their procedure, patients were asked to grade their pain from one to ten (ten being the most severe). Results: All women undergoing UAE with epidural anesthesia graded their pain 2 or lower. There were no complications directly related to the epidural anesthesia. Conclusion: Epidural anesthesia effectively manages pain in UAE.

P-20 CT Character ist ics of Pediatr ic Appendici t is Raul N. Uppot, MD, Medical Center of Delaware/Christiana Care,, Newark, DE, Vinay K. Gheyi, MD, Jugesh I. Cheema, MD, Sharon W. Gould, MD

Purpose: A pictorial exhibit of CT findings of appendicitis in the pediatric population. Materials and Methods: CT scans of pediatric patients presenting with appendicitis between 1995 and 1998 are collected and presented for their findings. Cases ilhistrating false positives and false negatives will also be presented. Results: The difficulty in diagnosing appendicitis on CT in the pediatric populataon correlates with the difficulty in visualizing the appendix. The difficulty in finding the appendix may be related to the smaller size of the appendix, the lack of periappendicular fat, and inadequate bowel opacification. Evaluation of appendiceal diameter, wall thickness, pres- ence or absence of appendicolith, and pericecal inflammation can be useful in diagnosing appendicitis in the pediatric population. Conclusion: CT evaluation of appendiceal diameter, wall thickness, presence or absence of appendicolith, and pericecal inflammation can be useful in diagnosing appendicitis in the pediatric population.

P-21 Thyroid Acropachy Robert L. Cirillo, Jr, MD, Rochester General Hospital, Rochester, NY, Roman M. Kowalchuk, MD, PhD, Philip S. Piasecki, MD, Francis A. Burgener, MD The object of this scientific exhibit is to review and illustrate the epidemiological, clinical, and radiological manifestations of thyroid acropachy. Thyroid acropachy is a typical, though rare, sequela of thyroid disease, seen in approximately 1% of patients with Graves' disease. It usually occurs several years after the onset of hyperthy- roidism, although it may be the initial manifestation. It may occur while the patient is euthyroid, hyper-, or hypothyroid and commonly occurs in conjunction with exophthalmos and pretibial myxedema.

The radiographic findings of thyroid acropachy are characteristic and unique to this condition. Periosteal new bone formation is seen in the middiaphyseal regions of the metatarsal, metacarpals, and proximal and middle phalanges. The periostitis is usually irregular, asymmetric, and prominent on the radial side of the bone. The periostitis tends to be dense with a feathery contour, although is can appear lacy. The eti- ology of thyroid acropachy appears to be related to long-acting thyroid stimulator (LATS) and human thyroid stimulator (HTS). Thyroid acropachy may be confused with malignant processes such as hypertrophic osteoarthropathy, as well as pachydermoperiostosls, hy- pervitaminosis A, periosteal bone formation associated with acrome- galy, and traumatic and infectious periostitis. The condition can be easily overlooked because it usually causes no symptoms or disability. Radiologists should be aware of the radiographic findings.

P-22 Imaging Features of Chondrosarcomas Wendy E. McCurdy, MD, University of Nebraska Medical Center, Omaha, NE, Craig W. Walker, MD, Timothy E. Moore, MD

Purpose: To demonstrate Imaging features of chondrosarcomas in the context of diagnosis, surgical planning, and identification of recurrence. Principal Information: Although CT and radiographs are useful in the diagnosis of chondrosarcomas, MR/can demonstrate specific features that not only characterize them as cartilage containing but sug- gest benign or malignant features. The excellent conspicnity of both benign and malignant cartilage facihtates identification of the extent of tumor and aids m identification of recurrent tumor. Representattve ex- arnples of pathologically proven primary and secondary chondrosarcomas are presented in addition to nonconventional chondrosarcomas. These cases illustrate radiologic features that contribute to the diagnosis, sur- gical planning, and identification of recurrent tumor.

Conclusion: 1. Hyaline cartilage-containing tumors can be difficult to characterize

histologically. They have characteristics that often enable better MR characterization than can be obtained with most skeletal neoplasms. An understanding of the pathophysiology of these lesions combined with the application of basic MR principles can result in radiologic opinions that significantly affect patient management.

2. MR/is useful for demonstrating the local extent of chondrosar- comas for the purpose of surgical planning.

3. MR/has benefit as a means of detecting recurrent chondrosarcomas.

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