0 2 - 9 Development and Implementa t ion of an Appropriate- ness Guidel ine for the Use of CT for Suspected Intraabdominal Abscess Nirish R. Lal, MD, University of Michigan Medical Center, Ann Arbor, MI, Ella A. Kazerooni , MD, Robert L. Bree, M D

P u r p o s e : A smal l percentage o f C T examina t ions done to detect intra-abdominal abscess are positive. W e developed and imple- mented an appropriateness guideline to reduce the absolute number of CT examina t ions and increase the posit ive abscess rate.

M a t e r i a l s a n d Methods: A mult idiscipl inary team developed an evidence-based guidel ine for the use of C T for suspected abscess. A control group consis ted o f all patients scanned for suspected ab- scess over s ix-months . The intervent ion group consis ted o f pa- tients scanned in the s ix -months fol lowing guidel ine implementa- tion. Focal fluid collections on C T were reviewed for both groups to determine if they were abscesses . The number and proport ion o f abscesses in each group were compared.

Resu l t s : There were 263 CT scans for suspected abscess during the control period, 75 exams (28.5%; 90% CI 24-33) with focal fluid, and 25(9.5%; 90% CI 7 -12) with abscess. Dur ing the inter- vent ion period 238 scans were performed, 54 (23%; 90% CI 18- 27) hav ing fluid and 41 (17%; 90% CI 13-21) with abscess.

Conclus ion: A guideline was successful at decreasing the number of CT scans and increasing the proport ion o f posit ive CT scans for abdominal abscess. As with other inpatient util ization interven- tions, practices need to assess the cost-benefi t t rade-off o f guide- line implementa t ion in complex clinical problems.

0 2 - 1 0 Understanding DROC Methodology: A Sof tware Toolki t for a N e w Dif ferent ial ROC Techn ique Nelson S. Howard, University of Pennsylvania Hospital, Philadel- phia, PA, Dev P. Chakraborty, PhD

P u r p o s e : The recent ly in t roduced differential receiver operat ing characteris t ic (DROC) m e t hod involves v iewing pairs o f images o f the same patient, one f rom each modal i ty . The obse rver ' s tasks are to (a) m a k e a diagnosis : abnormal or normal and (b) se- lect the modal i ty that yields greater conf idence in the diagnosis . D R O C has the potential advantage o f increased sensi t iv i ty to smal l image qual i ty differences. This presenta t ion will descr ibe a pre l iminary sof tware package (Visua l -DROC), developed us ing H T M L , C, and IDL, which al lows a researcher to unders tand, perform, and analyze D R O C exper iments .

M e t h o d s : V i sua l -DROC allows the user to select either a "re- searcher" mode or a "research-subject" mode. The former allows a researcher to learn about D R O C methodo logy and to des ign future D R O C studies. The latter mode leads a prospective research subject th rough training sessions.

Resu l t s : The focus of the software is on unders tanding various as- pects o f D R O C methodology: the task, reader training, data analy- sis, and statistics. The software is i l lustrated with normal m a m m o - grams, superimposed on which are artificial specks, fibers, or nod- ules. A wavelet compress ion a lgor i thm ( A W A R E ) is used to s imulate a different modali ty. The software has been successful ly tested on a number of observers .

Conc lus ions : The new software can be a useful tool to conduct D R O C exper iments .

Disc losure S t a t emen t : Supported in part by NIH R01-CA-75145.

02 -11 T h e U s e of C e n t r a l i z e d D a t a b a s e to F a c i l i t a t e Resi- d e n c y P r o g r a m A d m i n i s t r a t i o n Michael M. Ambrosino, MD, New York University Medical Center, New York, NY, Jeffrey V. Chapnick, MD, Nancy R. Fefferman, MD, Joseph C. Veniern, MD, PhD, Albert F. Keegan, M D

Purpose : The development and implementat ion of an integrated, centralized database for radiology residency program administration.

M a t e r i a l s a n d Methods: The sys tem was developed as a rela- tional database with Microsof t Access 97. Microsof t Word 97 ob- jects were l inked to the database as an adjunct for more sophisti- cated text edi t ing/formatt ing capability. The sys tem imports resi- dent background informat ion f rom ERAS files. Accessibi l i ty is p lanned through the depar tmental web site to supplement the de- par tmental local area network.

Resu l t s : The des ign phase is complete and implementa t ion is un- derway. Response f rom the p rogram director and faculty has been positive. The implemented portions (resident rotation evaluations, let- ters of recommendat ion, procedure log and conference attendance log) have already become useful daily administrative tools for con- solidating and summar iz ing resident per formance and activity; over 80 percent o f traditional paperwork and filing can potentially be el iminated.

Conclusion: The implemented portions of the system have proven to be valuable tools for the centralized adminis t ra t ion o f our residency program. The redundant, parallel legacy paper sys tems will be elimi- nated once the networked version is available to the entire faculty. As implementation proceeds and new modules come on line, we antici- pate even greater gains in eff iciency and convenience.

0 2 - 1 2 Evaluat ion of Re imbursement Pat terns for Bar ium En- e m a Jay M. Colby, MD, University of Massachusetts Medical Center, Worchester, MA, Alan M. Lucia, M B A

P u r p o s e : The purpose o f this s tudy is to evaluate re imbursement patterns for ba r ium enema among a n u m b e r o f third party payers, in the Northeastern Uni ted States.

Mater ia l a n d Methods : Retrospective evaluation of last one hundred double contrast ba r ium enemas per formed at a mid-s ized universi ty hospital in New England were reviewed. The direct and indirect costs of the study as well as the hospital charges were calculated. Re- imbursemen t f rom a n u m b e r o f different third party payers includ- ing Medicare, Medicaid, indemni ty payers and a number o f H M O s were calculated.

Resu l t s : There is a relat ively broad range o f r e imbur semen t s for ba r i um e n e m a s regionally. The direct and indirect costs are not inconsequent ia l for this study. Knowledge o f actual p a y m e n t for s tudies will encourage radiologis ts to increase eff ic iency and de- crease cost.

Conc lus ion: Reimbur semen t for ba r ium e n e m a s vary amo n g dif- ferent payers. The radiologist should be aware of these differences. This paper will also present the true costs of per forming this study and its relationship to actual charges and re imbursements .

0 3 - 1 3

Changing Pat tern of Mitral Valve Disease: Chest Radiographic Evaluat ion Benigno Soto, MD, Satinder Pal Singh, MD, University of Ala- bama Hospital, Birmingham, AL, Hrudaya P. Nath, M D

P u r p o s e : Over the years we observed a different pattern of radio- graphic abnormali t ies in mitral valve disease (MVD) which now is infrequently due to rheumatic disease. This study was done to deter- mine the chest radiographic manifes ta t ions o f various recently sur- gically proven cases o f M V D and to correlate these f indings with echocardiography.

M a t e r i a l s a n d M e t h o d s : 136 consecut ive cases of surgically proven isolated acquired M V D between 1994 and 1996 were re- v iewed retrospectively. Immedia te preoperative chest radiographs were evaluated and compared with the preoperative echocardiog- raphy and finally with operative f indings.

638

Resul t s : Mitral regurgi tat ion was the mos t c o m m o n valvular ab- normali ty seen in 77% (105/136) fol lowed by mitral s tenosis in 14% (19/136) and combined stenosis and regurgitation in 9% (12/ 136). The majority o f mitral regurgitation was non-rheumatic in ori- gin (88/105). Ches t radiographic f indings in non- rheumat ic nfitral regurgitat ion included cardiac en largement in 67% (59/88), pul- monary venous hyper tens ion in 58% (51/88), and left atrial en- largement in 41% (36/88). The mos t c o m m o n f inding in rheumat ic mitral regurgi tat ion was pu lmonary venous hyper tens ion in 70% (12/17) fol lowed by card iomegaly and left atrial en la rgement seen in 65% (11/17) each. In compar ison, pu lmonary venous hyperten- sion and left atrial enlargement were the c o m m o n f indings seen in 95% and 74% respectively, in patients with mitral stenosis. In 53% of these patients, there was no cardiac enlargement . Ches t radio- graphs underes t imated the left atrial en la rgement detected at echo- cardiography (51% vs. 89%).

Conclus ions : (1) Non-rheumat ic mitral regurgitation is the mos t c o m m o n form of M V D encountered today. (2) Whi le diagnosis o f mitral s tenosis f rom chest radiograph is often possible, d iagnos ing non-rheumat ic mitral regurgi tat ion is difficult. (3) In about 25% of patients with mitral stenosis, the only radiographic abnormal i ty is pu lmonary venous hypertension.

0 3 - 1 4 CT Depict ion of in Situ Vascular Stump Thrombosis Following Pulmonary Resect ion for Cancer Ange la J. Gessner , MD, Thomas Jefferson University Hospital, Philadelphia, PA, Richard J. Wechsler , MD, A n a M. Salazar, MD, Paul W. Spiru, MD, Robert M. Steiner, M D

P u r p o s e : To assess the incidence and s ignif icance o f vascular s tump thrombosis found on C T scans performed fol lowing lung resect ions for carcinoma.

Me thods /Ma te r i a l s : A computer search of C T chest scan reports be tween 1994 and 1997 identif ied 265 scans on 90 patients fol- lowing pu lmonary lobec tomy or pneumonec tomy . These scans were reviewed by two radiologists in concert to identify vascular s tump int ra luminal defects and/or concomitant pu lmonary embol i in other lung segments . The medical records of the involved pa- tients were reviewed for predisposing thrombogenic factors, suspi- c ion o f pu lmonary embol i and adjuvant studies.

Resu l t s : Six patients, all with r ight sided lobec tomy or pneu- monec tomy, were identified as hav ing pu lmonary arterial intralu- minal clot. T h r o m b u s in four patients was only identified at the s tump site without clot e lsewhere in the lung. Pu lmonary emboli were found in two patients without s tump thrombosis, 1 with posi- tive lower extremity Doppler examinat ion, the other having a negative inferior vena cavogram before filter placement.

Conc lus ions : Incidental s tump thrombosis was found in 4% of patients fol lowing pu lmonary resect ion and does not appear to be a r isk factor for pu lmonary embol i sm.

0 3 - 1 5 Plain Film Diagnosis of Congenital Heart Disease Laura M. Fayad, MS, MD, Columbia-Presbyterian Medical Cen- ter, New York, NY, Lawrence M. Boxt, M D

P u r p o s e : To develop a cl inical ly re levant approach to the diag- nosis o f congeni ta l heart d i sease based upon plain f i lm changes caused by ma l fo rma t ions and their phys io logic sequelae.

Materials, M e t h o d s & R esu l t s : In pat ients with heart disease, congeni ta l ma l fo rma t ions cause al terat ions o f cardiac func t ion wh ich resul t in radiographic changes in the appearance o f the hear t and pu lmona ry vasculature . Phys io logic changes resul t in cardiac chambe r dilatat ion and myocard ia l hyper t rophy, both o f which resul t in changes in the appearance o f left and r ight heart border - fo rming structures. Sequent ia l analys is o f these changes in the pos teroanter ior (PA) radiograph, and correlat ion with changes in the sharpness , caliber, and distr ibution of the paren-

chyma l pu lmona ry blood vesse ls provide the basis for e lucidat ing these pa thophys io log ic m e c h a n i s m s , a l lowing d iagnosis o f the congeni ta l mal format ions . No clinical in format ion is a s s u m e d in this formulat ion.

C o n e l u s l o n : A cl inically re levant me thod for d iagnos ing and c lass i fy ing congeni ta l heart d isease is constructed, based upon the PA ches t f i lm presenta t ion o f these mal format ions .

0 3 - 1 6 FDG-PET and CT Assessment of Peripheral and Cen- tral Lung Lesions A n g e l a Lignell i , MD, Columbia Presbyterian Medical Center, New York, NY, John H. Aus t in , MD, Gregory D.N. Pearson, MD, PhD, Chitra Manoj , Ronald L. Van Heer tum, M D

P u r p o s e : To evaluate ma l ignancy of per ipheral vs. central lung les ions by us ing f luorodeoxyg lucose (FDG) PET and C T criteria.

Methods and M a t e r i a l s : Twen ty -one adul t patients , ages 38 to 84 yrs., wi th lung nodules or m a s s e s were studied. Les ions ranged in size f rom l c m to 6 c m at CT. Peripheral lesions were def ined as les ions located a d is tance o f 2.0 cm or less f rom vis- ceral p leura while all other les ions were classif ied as central. Based on ches t CT, les ions were def ined as mal ignan t or ben ign us ing ana tomic criteria wh ich included spicnlat ions, presence and pat tern o f calcif icat ions, shape and size. Standardized uptake value (SUV) of >2.5 was accepted as the ma in F D G - P E T crite- r ion for ma l ignancy . A total o f 11 les ions were classif ied as cen- tral and 10 as peripheral , Final ma l ignancy status was de te rmined by b iopsy or a 2 year m i n i m u m clinical fol low-up. Mal ignan t le- s ions compr i sed 6/11 central les ions and 2/10 peripheral lesions.

Resul t s : PET and CT determination o f likelihood of mal ignancy was concordant in 10/11 o f the central lesions, and 4/10 peripheral lesions. The following table is included to summar ize the results:

CT correct PET correct

Central mal ignant 6/6 6/6

Central ben ign 4/5 5/5

Peripheral mal ignant 2/2 0/2

Peripheral benign 4/8 7/8

Of the 2 mal ignant peripheral lesions both were biopsied with the first lesion d iagnosed as metastat ic renal cancer and the second one as combined large and small cell lung cancer with neuroendo- crine features. For both central and peripheral lesions combined sen- sitivity of CT was found to be 100% and specificity 62%, while for PET overall sensit ivi ty was 75% and specificity 92%.

Cone lus ions : Both CT and PET appear to be concordant in cor- rectly characterizing central lung lesions as mal ignant or benign. For peripheral lesions neither technique is consis tent ly accurate in determining mal ignancy as CT appears to have a lower specificity with respect to PET, but PET in turn has a lower sensitivity. W e plan to expand this series in an at tempt to further delineate whether malignancy of lung lesions may be assessed based on criteria o f lo- cation, me tabo l i sm and anatomic appearance.

0 3 - 1 7 Work.up of Pulmonary Embolism in a Teaching Hospi- tal: Prel iminary Analysis of Data from 683 Pat ients Max P. Rosen, MD, Beth Israel Deaconess Medical Center, Bos- ton, MA, Roger Davis , ScD, Daniel Z. Sands, MD, MPH, W h i t n e y Drake, Karen M. Kuntz , ScD

Purpose: The purpose o f our s tudy is to (1) D o c u m e n t M D s ' ability to accurate ly assess the clinical l ikel ihood of pu lmona ry e m b o l i s m (PE), (2) Ident i fy pat ient and phys ic ian characteris t ics associa ted with an incomple te work-up for PE and (3) As se s s the impac t o f an incomple te work-up for PE on pat ient survival .

639