Pleural Pointillism And Early Contrast Enhancement As Imaging Biomarkers Of Pleural Malignancy

Background: Pleural malignancy (PM) may be occult on imaging morphology. Pleural Pointillism (PP), at Diffusion-Weighted Imaging (DWI) and Early Contrast Enhancement (ECE), at contrast-enhanced MRI are functional MRI biomarkers. PP is a simple, rapid visual exam but is restricted to the inferior pleura. ECE can assess the entire pleura but takes ~14min. Here we deployed a 2-step approach to examine their combined performance. Methods: 38 patients with suspected PM, recruited to DIAPHRAGM (ISRCTN10079972) and pre-EDIT feasibility studies (NCT03319186) had DWI and CE-T1-weighted, 3T MRI prior to pleural biopsy. PP and ECE were assessed by 2 reporters, blinded to final diagnosis and the other9s results. PP was defined as inhomogeneous pleural hyperintensity at b1000 DWI. ECE was defined as a peak in signal intensity in 1+ pleural ROI at/before 4.5min post-contrast at CE-MRI. If PP was present the case was classed as malignant. If PP was absent, ECE was examined, if present the case was classed as malignant. If both were negative the case was classed as benign. Results: 27/38 (71%) had PM. Diagnostic performance of PP, ECE and combined PP-ECE is reported in Table 1. Inter-observer agreement of ECE (K 0.864) and PP (K 0.819) was excellent. Mean case analysis time was 8 min. Conclusions: A 2-step approach reduced analysis time compared to ECE alone. Sensitivity and NPV were marginally increased at the cost of a potential reduction in specificity. Larger validation studies are warranted.