Diagnostic efficacy of perfusion scans interpreted by PISA-PED criteria for pulmonary embolism:comparison with CTPA

Abstract

Objective To compare the diagnostic efficiency of lung perfusion scans in PE interpreted by prospective investigative study of PE diagnosis (PISA-PED) criteria with contrast-enhanced multislice spiral CT pulmonary angiography ( CTPA ).Methods One hundred and four consecutive patients with suspected PE were enrolled. All patients underwent lung perfusion scans,CTPA and chest radiography.Lung perfusion scans were interpreted by PISA-PED criteria.Final diagnosis was confirmed using a composite reference test.Kappa test was used to analyze the degree of agreement between the multimodality images.The differences between the multimodality images were tested for significance using nonparametric test or x2-test.Results PE was finally diagnosed in 55 of the 104 patients.After excluding three patients ( 2.9％ )with non-diagnostic CTPA from analysis,the sensitivity,specificity,positive predictive value and negative predictive value were 92.6％ ( 50/54),83.0％ ( 39/47 ),86.2％ ( 50/58 ),90.7％ ( 39/43 ) respectively for lung perfusion scans,and 96.3％ ( 52/54 ),93.6％ ( 44/47 ),94.5％ ( 52/55 ),95.7％ ( 44/46 ) respectively for CTPA.The agreement rate between the two modalities was 89.1％ (90/101 ; Kappa =0.78,P ＜0.05).In the segment-based analysis,a total of 1664 segments were evaluated.The agreement rate between lung perfusion scans and CTPA was 79.7％ ( 1327/1664; Kappa =0.58,P ＜0.05 ).Conclusions Lung perfusion scans interpreted by PISA-PED criteria can provide diagnostic accuracy comparable to CTPA,and the two modalities both show high efficacy in diagnosing PE.The agreement between lung perfusion scans and CTPA was intermediate on a segment-by-segment basis. Key words: Plumonary embolism; Radionuclide imaging; Tomography, X-ray computed; MAA