Perfusion abnormalities in pulmonary embolism studied with perfusion MRI and ventilation-perfusion scintigraphy:: An intra-modality and inter-modality agreement study

Purpose: To compare perfusion magnetic resonance imaging (MRI) and ventilation-perfusion scintigraphy (V-P scan) in the study of perfusion abnormalities in pulmonary embolism (PE) and to compare the PE results to the findings previously reported for pneumonia and chronic obstructive pulmonary disease (COPD), in terms of perfusion abnormalities. Materials and Methods: Dynamic contrast-enhanced MR images and V-P scans of 20 patients with PE, I I patients with acute pneumonia, and 13 patients with exacerbation of COPD were studied. Five categories of perfusion abnormalities within each imaging modality were defined. Intra- and intermodality agreement (kappa values) in the evaluation of perfusion abnormalities were calculated, based on the two observers of each imaging modality (all blinded to each other and true diagnosis). Finally, three categories of perfusion MRI diagnosis (PE. pneumonia. and COPD) were also defined and the inter-observer agreement (kappa value) was calculated. Results: For PE, the intra-modality agreement (kappa value) in the evaluation of perfusion abnormalities was 0.77 for MRI and 0.65 for V-P scan. The inter-modality agreement varied from 0.52 to 0.57, respectively, and was observer-dependent. For the pooled group of PE, pneumonia, and COPD, the intramodality agreement of perfusion abnormalities was 0.76 for MRI and 0.65 for V-P scan, and the inter-modality agreement varied from 0.51 to 0.56. The kappa value for inter-observer agreement for MRI diagnosis was 0.92. Conclusion: Evaluation of perfusion abnormalities in PE, pneumonia, and COPD using perfusion MRI and V-P scan showed a high intra-modality agreement that was higher than the inter-modality agreement. Further studies are now needed In patients presenting with possible PE to evaluate the sensitivity and specificity of the method.