Interobserver Variability of Quantitative and Qualitative Assessment Using MRI in Malignant Pleural Mesothelioma.

Purpose: To evaluate the interobserver variability associated with quantitative and qualitative MRI assessments of malignant pleural mesothelioma (MPM).

Materials And Methods: Patients with MPM who underwent uniform-protocol preoperative MRI between 2009 and 2014 were included. The MRI-derived tumor volume was estimated. Unidimensional measurements of maximal pleural thickness ( ) and average pleural thickness ( ) on axial MR images; maximal fissural thickness ( ); maximal diaphragmatic thickness ( ); and average diaphragmatic thickness ( ) on sagittal reconstructed images were acquired. Interobserver agreement regarding the American Joint Committee on Cancer (AJCC) tumor stage at each criterion level was assessed by using Cohen κ statistics. Agreement between quantitative measurements was assessed by using Bland-Altman plots and intraclass correlation coefficients (ICCs).

Results: The study cohort included 349 patients (median age, 68 years [age range, 30-90 years), 273 (78%) of whom were men and 203 (58%) of whom had epithelioid-subtype tumors. Qualitative assessment performed by using the AJCC staging criteria (eighth edition) was concordant in 31% of cases and yielded considerable disagreement (κ = 0.177). Inspection of the Bland-Altman plots led to decisive agreement between the two reviewers regarding MRI-derived tumor volume (ICC, 0.979). There was also a good degree of agreement between the two reviewers regarding unidimensional measurements of (ICC, 0.807), (ICC, 0.823), (ICC, 0.787), (ICC, 0.787), and (ICC, 0.659).

Conclusion: Quantitative assessment can enhance the clinical staging of MPM. Compared with qualitative assessment, quantitative assessment has low interobserver variability and could yield a tumor size criterion that is currently lacking in the AJCC clinical staging of MPM.© RSNA, 2020.