and (2) the estimates of the percent probability of pulmo nary embolism (PE) by the investigators. METhODS AND RESULTS In the analysesthatfollow,we discusseachcriterionusedin the PIOPED study for categorical probability assessment. The datareportedherewereobtainedbyisolatingvariouscomponents of the detailed consensus descriptionmade from the V/Q scans by membersof theNuclearMedicineWorkingGroup*andcompar ingtheseto descriptorsof the angiographicfindingsderivedfrom the angiographic findingsdeterminedby thePIOPEDAngiogra phyWorkingGroupt. This is possible since the Angiography Working Group also describedtheir findingson a form intendedfor computerization. This form included a detailed description of the location of any embolusfound.Pulmonazyembolicouldbe describedinthe main puhnonaiy artety (PA), left or right PA and regional lobar, seg mental or peripheral PA depending on the size and location of the embolus. Therefore, it was possible to describe regional findings ontheV/Qscananddeterminewhetherthepatienthadapulmo nary embolus and if its location corresponded to the location of those particular findings on the V/Q scan. In those patients who had PE diagnosed upon angiographyof the first lung studied and thereforeunderwentangiographyof onlyonelung(1),regional correlations were performed in the presentstudyonly for those lungregionsinwhichangiograms wereobtained. A smallnumberofpatients(1)wereunabletocompleteventi lation scans. These patients are not included in this study. Data from the trial (1) were initially reported on the basis of findings from the PIOPED CliniCal Outcome Committee, which reviewednot only the pulmonaryangiogramresults,but also the ‘The PIOPEDNuclear MedidnoWorldng Groupincluded thetoNow@g indMd uals:Abass,4javi, MD,Chakman(Un@,ersfty of Pennsylvan@); A.EdwardCob man, MD(DukeUniversity); Jcny W. Froeilch,MD(HenryFordHospital); Alex anderGottschalk, MD(YaleUniversity); Jak EJuni,MD(Unwesslty ofMichigan); Kenneth fr@McKu&ck, MD(Massa@husetts GeneralHospital); H.DirkSoetman, MD(ValeUniversity); Jamesmini,MD(Hensy FordHospital). titlePIOPEDMgk@grsphy WoddngGroupindudedthefoilowkig k@dMduals: RichardH.Greenspan, MD,Chairman (ValeUntvorslty); N.ReedDunnick, MD (DukoUnWasity); P.C.Shetty. MD(HensyFordHospital); Chñstos Athanasoulls, MD(MasssohusottsGeneral Hospital); KyungJ. Cho,MD(Unlversityof Michigan); GoitlonK McLean, MD(University of Pennsyhania); DonaldF. DennyJr., MD (YaleUniversity). This artide presents an evalua@on of the critena used for cafe gorucalinterpretalion ofthe venthation-perfusion (@/IQ) scans per formed in the PIOPED study. In addition, the correlation of per cent proba@Iftyestimates withthe actual frequency of pulmonary embolism (PE) is presented. Cases which met the PIOPED criteria for various diagnostic categones were SeleCted by corn puterized search of the detailed scan descsiptions that had been done as part ofthe study. The process by wh@hthe scans were described was detailed in Part I ofthis report Most ofthe crftena approp@ately categoiized WQ scans wh@hsabsfied them. How ever, we recommend that three criteria should be reconsidered: I . A single moderate perfusion defect is appropriately cafe gonzed as intermediate,rather than as lowprobability. 2.ExtensniematchedWQabnormalitiesareappropiiate for low probability, provided that the chest radiograph is dear. Onthe otherhand,single-matcheddefects maybe better categonzed as intermediate probability. Aithough due to the smallnumberof cases withthis finding,no definite, stafis@callyfOunded recommendalion can be made. 3. Two segmental mismatches may not be the opbmum threshdd for high probability, and in some cases should be considered for intermediate probability.However,due to the small numberof cases withthis finding,no definite, statistically fOUnded recommendation can be made. We suggest that the revised critena resuffingfrom these adjust ments should now be used forthe interpretalionof WQ scans. J NucIMed1993;34:1119-1126 his study uses the computerized data from the consen sus ventilation-perfusion (V/Q) scan description obtained in the PIOPED study to evaluate retrospectively: (1) the PIOPED criteriafor categoricalinterpretationofV/Q scans ReceivedDecember 14,1992;re@sion acce@1ed March30,19@. Forcorrespondenceor reprintscont@ H.DirkScstman, MD,Dept of R@ ology,Box3808,DukeUniversityMedIcalCenter,Durh@n, NC27710. WQ Sdnligraphy in PIOPED. Part II • Gottschalk at ai. 1119 Ventilation-Perfusion Scintigraphy in the PIOPED Study. Part II. Evaluation of the Scintigraphic Criteria and Interpretations Alexander Gottschalk, H. Dirk Sostman, R. Edward Coleman, Jack E. Juni, James Thrall, Kenneth A. McKusick, Jerry W. Froelich and Abass Alavi Department ofRadiolo@, Michigan State University, East Lat@in& Mkhigan,@ Department ofRadiolo@j, Duke Universiiy Medical Center, Dutham, North Carolina; Depamnent ofRadiology, William Beaumont Hospita4 Royal Oak Michigan; Department ofRadiologv, Massachusetts GeneralHospita4 Boston, Massachusetts;Radiolo@jiImagingAssociates, Swedish Medical Center, Englewood, Colorado; and Depamnent ofRadialo@', Hospital ofthe University of Penn.sylvania, Philad4thia, Pennsylvania by on August 29, 2017. For personal use only. jnm.snmjournals.org Downloaded from