Purpose : Chronic, intermittent gastrointestinal bleeding is defined as obscure when routine diagnostic examinat ions of the gastrointes- tinal tract including bar ium and endoscopic studies fail to reveal the cause of bleeding. This can be an extremely fl-ustrating clinical problem with patients having significant bleeding. M any patients had extensive negative work-ups including upper and lower endos- copy, enteroscopy, enteroclysis, and angiography. This study dem- onstrates a novel approach to detect the source o f bleeding.

Ma te r i a l s a n d M e t h o d s : A helical CT examinat ion was performed following oral ingestion of water as a negative contrast agent over a period of one hour prior to the exam instead of barium. Intravenous contrast (150 cc o f nonionic contrast) was injected at a rate o f 5 cc/ sec and arterial and venous phase images were obtained with thin slice CT examinations. 8 patients have been examined to date.

Resul ts : CT was able to detect the source of bleeding in 2 patients where m a n y other tests were unreveal ing. One patient had choles- terol emboli to the small bowel and the other patient had arterio- venous mal format ion of the cecum.

Conclus ions: This type of examina t ion which is noninvas ive compared to other techniques can be ext remely helpful to identify the source of bleeding when other tests are unreveal ing.

0 7 - 5 2 MR Evaluat ion of Pelvic Organ Prolapse: Comparison with Cystoproctography Harpreet K. Pannu, MD, Johns Hopkins Hospital, Baltimore, MD, David A. Bluemke, MD, PhD, B ronwyn Jones, MD, Elliot K. F i shman , M D

In troduct ion: Fluoroscopic cys toproc tography s imula tes natural condi t ions and is of ten pe r fo rmed to evaluate pelvic floor relax- ation. MRI can provide dynami c as well as ana tomic in format ion in these patients . This s tudy eva lua tes the sensi t iv i ty o f M RI for d iagnos ing pelvic organ prolapse demons t ra ted by cystoproc- tography and addit ional ana tomic in format ion revealed by MRI.

Ma te r i a l s a n d M e t h o d s : 15 patients had both studies within an av- erage of 9.6 days (range 0-49). Cystoproctography was performed by opacifying the bladder, small bowel, rec tum and vagina and the patient evacuating on a commode. M R I was performed with the pa- tient supine with knees f lexed and a pelvic coil on a GE 1.5T Signa unit with TR/TE 2000/60, axial/sagittal/coronal 6mm/skip 2rnm slices, 1 NEX, 256 x 192 matrix, B W 32kHz, ETL 16 at rest and with minimal /modera te /maximal straining. Resul ts o f the two stud- ies were compared.

Resul ts : Cystocele Rectocele Enterocele

M R I 10 6 5 (# o f

Cys toproc tography 12 12 7 patients)

MRI showed bu lg ing levator ani in 10 patients , bowel hernia- t ion th rough levator ani musc l e complex in 1 patient, and as- cites in 1 patient .

Conclusion: MRI diagnosed 83% of cystoceles, 50% of rectoceles and 62% of enteroceles. Rectoceles missed were <3cm. M R I pro- vides useful informat ion regarding the levator ani musc le and as- sociated pathologic condit ions that m a y supplement cysto- proctography findings.

0 7 - 5 3 Unenhanced Hel ical CT with Enteric Contrast for the Evaluation of Appendici t is in Children Brian S. Funaki, MD, University of Chicago, Chicago, IL, Alexandra N. Funald, DO, Scott R. Grosskreutz, MD, Clarence N. Funaki, M D

P u r p o s e : The accuracy o f unenhanced helical CT with enteric contrast mater ia l was evaluated in the d iagnos is of appendici t is in ch i ldren

M a t e r i a l s a n d M e t h o d s : Over a 10-month period, 30 consecu- tive chi ldren (ages 5 -17 years, m e a n 11 years) with r ight lower quadrant pa in and suspec ted appendici t is were prospect ively evaluated. Thin-co l l imat ion helical scann ing was per formed after adminis t ra t ion o f enteric contrast material . CT interpretat ions were correlated with surgical pa thology (9 patients) and clinical fo l low-up (21 patients)

Resu l t s : Six CT scans were interpreted as posi t ive for appendici- tis (6 true posi t ives) and 24 CT scans were interpreted as nega t ive for appendici t is (24 true negat ives) . Sensi t ivi ty and specif ici ty were 100%. In 24 scans interpreted as nega t ive for appendici t is , an al ternat ive d iagnos is was made in 17 patients (71%). The m o s t c o m m o n CT diagnos is was mesen te r ic adenitis, wh ich was diag- nosed in 12 patients .

C o n c l u s i o n : U n e n h a n c e d helical CT with enteric contrast mate- rial for the evaluat ion o f appendici t is in chi ldren appears promis- ing. In our s tudy imag ing achieved excel lent accuracy.

0 7 - 5 4 Uti l i ty of Routine Trauma CT in Detect ing Bladder Rup. tures Dorothy M. Pao, BS, University of Michigan Hospitals, Ann Arbor, MI, James H. Ellis, MD, Richard H. Cohan, MD, Melvyn T. Korobkin, M D

P u r p o s e : To determine when cys tography is required fol lowing CT evaluat ion o f t rauma patients with suspected bladder injury.

M a t e r i a l s a n d M e t h o d s : Cys tog rams and abdominopelvic CT ex- aminat ions were reviewed in 54 blunt t rauma patients in w h o m bladder rupture was clinically suspected. Blinded readings o f CT ex- aminat ions were per formed by two genitourinary radiologists. Cys tograms were used as the "'gold standard."

Resul ts : Cystography demonstrated bladder rupture in 10 patients ( seven extraperitoneal [EP] and three intraperitoneal lIP]). On CT, EP and IP fluid was seen in two and two of three patients with IP bladder rupture, in seven and two of seven pat ients with EP blad- der rupture, and in 25 and 14 o f 44 patients without bladder injury. In one patient with IP bladder rupture, the location of pelvic fluid could not be determined. Only a small amount of pelvic IP fluid was present in two patients with IP bladder rupture. Contrast material had been excreted into the bladder in eight patients with bladder in- jury; however , extravasat ion was identified in only four. In two of the four patients without contrast extravasation, the bladder was distended. None of the 12 patients without pelvic fluid at CT had a bladder injury.

Conclusions: The absence o f pelvic fluid on a trauma CT excludes significant bladder injury. Follow-up cystography is not required in these patients. Even when a partially opacified bladder is pass ive ly distended, bladder injury may be present in the absence of CT-de- tected contrast extravasation. IP bladder rupture may be present when only a small amount o f pelvic IP fluid is visualized.

0 8 - 5 5 CNS Lyme Disease: Assessment of Blood Flow on Brain SPECT by Stat ist ical Parametr ic Mapping Lester S. Johnson, MD, PhD, Columbia-Presbyterian Medical Center, New York, NY, Ronald S. Tikofsky, PhD, Vitaly Furman, MS, Joseph J. Burrascano, Jr, MD, Gerald T. Simons, PA, Ronald L. Van Heer tum, M D

Purpose : To evaluate regional cerebral blood flow changes in pa- tients with documented central nervous sys tem (CNS) Lyme disease.

M a t e r i a l s a n d M e t h o d s : Patients with neuropsychiatr ic sy m p to m s and documented L y m e disease (n = 20, all with L y m e antigen/se- rology and/or tick bite plus e ry thema chronica rhigrans) underwent brain SPECT with 99mTc-HMPAO. L y m e patients collectively, as

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