6A-7 KETINOBLASTOMA= ULTRASOUND, MAGNETIC RESONANCE IMAGING OR COMPUTED TOMOGRAPHY? Bradley S. Shore, M.D., Daisy Gupta, Kundan L. Gupta, M. D. Tulane University Medical Center, New Orleans, Louisiana 70112 pgrpose: To determine the sensitivity and specificity of MRt in the evaluation of retinoblastoma and associated hemorrlaage when compared to ul trasound and CT. Materials and methods: 32 pediatric orbital lesions were evaluated with fundascopie exam, 10 MHz orbitni ultrasound, computed tomography and a 1.5 Tesia GE MRI scanner with Gd- enhancement. Results: 6 cases of choroidal hemorrhage and 21 retinoblastomas were identified. All cases detected by US and clinical exam were detected by enhanced MR[ imaging. Conclusion: Both MRI and US were found to be equally sensitive in detecting intraocniar hemorrhage and retinoblastoma. CT clearly demonstrated calcification differences in ivIRI signs1 characteristics are sufficient to differentiate hemorrhage and tumor. Contrast MRI increases the sensitivity and specificity of detection of hemorrhage and tumor. Both US and MR imaging are complimentary in the i r evaluation of intraocular lesions and correlated we3 with the fundoscopic and clinical exam.

6A-8 THE ROLE OF CHEST RADIOGRAPHY IN DETERMINING MALFUNCTION AND COMPLICATIONS OF GARDIOVERTER-DEFIBRILLATOR SYSTEMS IMPLANTED WITHOUT THORACOTOMY, /ktul Guota. MD. HC Zegel, MD, VS Dravid, MD, ML Turner, DO, DB Freiman, MD, SJ Nierenberg, MD, University of Pennsylvania Healtf System- Presbyterian Medical Center, Philadelphia, PA

puroose: To quantify frequency snd etiology of complication of non-thoracoton]y implanted cardiovertsr defibrillator systems [ICD] and to delineate the role of chest radiography [CXR] in assessing these complications.

Methods: Between May 1992 and December 1995, 437 consecutive patients hsd ICO placement. Routim follow-up included external device testing st 6 wks post-plscement, and every 3 months tbereafter. CXR was obtaine( annually and at time of complication. Retrospective radiographic review was performed on all patients with clin[ea complications. ; .

Results: There were 45 complications (10.3%) clinically diagnosed: lead/patch fracture in 15 (33%), electrie~ lead dysfunction in 8 (18%), infection in 8 (18%), lead retraction in 6 (13%), patch fold in 2 (5%), hemtoma in 2 (5~A and other in 4 (8%).

Eighteen complications (40%) were radiographically evident. Lead retraction, hematoma, patch fol, patch migration, and "twiddler" syndrome were radiographically confirmed in 100% cases. The average time for th~e~ complications to develop was 68 days; 92% ocourring within 23 days.

Conversely, only 27% of lead fraetures, 13% of electdca[ lead dysfunction, and 13% of infection eoul( be radiographically confirmed. These cocured an average of 579 days post ICD.

Conclusion: CXR plays a secondary role in the diagnosis of ICD complications, and is particularly limited beyon( one month after placement. CXR may be helpful in the first month, ss early coctplicat[ons are the mo~ radiographically apparent.

7-1 GAZE DWELL TIMES ON MULTIPLE ACUTE TRAUMA INJUR/ES, David M. Kueim, M.D., K.S. Berbaum, Ph.D., G.Y. El Khoury, M.D., E.A. Franken, Jr.,M.D., D.D. Dorfman, Ph.D., E.M. Miller, B.S.E., R.T. Caldwell, M.F.A., The University of Iowa, Iowa City, IA Purvose: A previous study has shown that subtle fractures are missed in multi-trauma patients because other fractures are detected. This is an example of the satisfaction of search (SOS) effect. In the current study, gaze dwell time was used to determine vchether these errors occurred because of faulty visual scanning, recognition, or decision making. Methods: Gaze dwell time on acute musculoskeletal injuries was examined in ten matched pairs of cases, both members of each pair demonstrating the same abnormality: buz with only one member demonstrating a second abnormality. Tea radiologists served as readers. Results: On the basis of the previous study, these errors were expected to be caused largeiy by recognition error, rather thma by scanning or decision error. Preliminary analysis of those dwell times associated with SOS errors were quite long, suggesting faulty decision making. Condusiom.: The SOS effect in mu~culoskeletal traumainvolves a reduction in true positive rates without change in false positive rates for the common abnormality in each pair of cases in the SOS paradigm. This SOS effect is not caused by scanning, but rather may be based largely on decision error and recognition.

Supported in part by National Institutes of Health grants R01 CA 42453 and R01 CA 62362.

7-2 ~uant i ta t ive Analys is of t he P l a i n Radiographic Appearance of Eosinophil ie ~ranuloma

k. J . F isher , MD, W. R. Reinus, MD, J . A. Fr ied land, MD, A. J . Wilson, M B C h B

)URPOSE: To quan t i t a t e those fea tures which d is t inguish the p la in rad iographic tppearanee of eosinophilie g ranu loma (EG) from other sol i tary lesions of bone.

IATERIALS AND METHODS: 709 cases of focal bone lesions, inc luding 26 EGs, ,ere ana lyzed according to demographic, anatomic, and p la in radiographic features . "ector analys is of groups of fea tures was done to de te rmine fea tures t h a t were most ms i t ive and specific for E G in contras t to other lesions l i s ted in the da tabase .

E S U L T S : The most common radiographic appearance of E G was a medu l l a ry ased, lyric lesion (100%) , w i th geographic des t ruct ion (76.9%), possessing a lobular m t o u r and wel l -def ined edges (73.1%). Long bone EGs showed these qual i t ies tore al~en t h a n EGs in f ia t bones. Per ios tea l react ion was present in a l l long bone IGs (100%) bug was uncommon elsewhere. 65% of EGs showed no osseous a la rgeuren t and 69% lacked discrete margina t ion . These l a s t two fea tures were npo r t an t in l imi t ing the dif ferent ia l diagnosis. The major different ial diagnoses acluded a n e u r y s m a l and un icamera l bone cysts, nonossifying fibromas, g ian t cell amors and Brodie 's abscesses.

!ONCLUSION: E G has d iverse radiographic appearances . Never theless , a ~latively specific set of rad iographic fea tures can be defined, which wil l ass i s t in adiographic ident i f ica t ion and improve upon descript ions found in the rad iographic t e ra tu re .

7-3 I M A G I N G T E C H N I Q U E S F O R E V A L U A T I O N O F F O R E I G N B O D I E S Erie B. Fdedbar~_ M.D.. T.T. Miller, M.D., R. Staron, M.D., F. Feldman, M.D., Cohimbia-Um'versity-Collegn of Physicians and Surgeons, New York, NY

PURPOSE: To determine the optimum imaging modality for plastic, glass and wood foreign bodies and to determine the usefulness of gradient echo sequences.

METHODS: Pinces of glass of known chemical composition, plastic, and unfinished wood were plaeod in a grid composed of meat as well as in a cadaveric hand. Speoimens were imaged with eoevantioasl radiography, CT, and MRI, including s variety of spin echo and gradient echo sequences. Studies were reviewed indopandantly by three museuloskeletal radiologists.

RESULTS: Wood and plastic foreign bedies were betier visualizod with MRI and CT than with radiographs. In addition, certain types of gla~ were more accurately detncted by MRI and CT.

CONCLUSION: In evaluating glass foreign bodies, radiography should be the initial screening procedure. For wood and plastic foreign bodies, and for clinically suspected glass foreign bodies not detected on radiographs, CT or MR/are the exams of choice. Gradient echo sequences are not as useful as conventional and f~ t spin echo techniques secondary to numerous dephasing a~ifants. Statistical analysis of the findings will be presented.

7-4 GRAD]ENT-RECALLED ECHO VERSUS FAST SPIN-ECHO T2-WEIGHTED MR IMAGING OF THE GLENOID LABRUM, Michael J. Tnite. M.D., A. De Smet, M.D., M. Norris, M.D., J. Orwin, M.D.

Purpose: To compare die sensitivity and specificity of gradient-recalled echo (GRE) and fast spin-echo (FSE) MR images in die evaluation of anteminfodor labral tears.

Methods: Nine patients with tears, and nine age-matched controls, had axial "1'2*- weighted GRE and fat-suppressed T2-weighted FSE images of die shoulder followed by arthroseopy. In a retrospective review, two blinded readers separately graded die anteminfeficr lahrum on die GRE images as tom or normal. After a 4 week interval, the labrum was graded on die FSE images. The MR interpretations were compared with die surgical findings and die sensitivity and specificity calculated. These were compared using a t-test.

Results: For die GRE images, the sensitivity for reader A was .56 and die specificity 1.0, and for reader B they were .78 and .89. For die FSE images, die sensitivity for reader A was .67 (p>.5) while die specificity remained 1.0. Reader B also expedeoced an increase in sensitivity to 1.0 (p>.l) while the specificity was unchanged.

Conclusions: There is a slightly, but not statistically significant, higher sensitivity of fat-anppressed T2-weighted FSE images compared with GRE images for the detection of antcroinferior labral tears.