A Multicenter Study of Volumetric Computed Tomography for Staging Malignant Pleural Mesothelioma

Abstract

Background Standard imaging modalities are inaccurate in staging malignant pleural mesothelioma (MPM). Single institution studies suggest that volumetric computed tomography (VolCT) is more accurate but labor intensive. We established a multicenter network to test interobserver variability, accuracy (relative to pathologic stage) and prognostic significance of semi-automated VolCT. Methods Six institutions electronically submitted clinical and pathologic data to an established multicenter database on patients with MPM who had surgery. Institutional radiologists reviewed preoperative CT scans for quality then submitted via electronic network (AG mednet) to biostatistical center (BC). Two reference radiologists, blinded to clinical data, performed semi-automated tumor volume calculations using commercially available software (Vitrea Enterprise 6.0), then submitted readings to BC. Study endpoints included: feasibility of network; interobserver variability for VolCT; correlation of tumor volume to pTN stages, and overall survival (OS). Results Of 164 cases, 129 were analyzable and read by reference radiologists. Most tumors were <500cm3. A small bias was observed between readers, as one provided consistently larger measurements than the other (mean difference=47.9, p=.0027), but for 80% of cases, the absolute difference was ≤ 200cm3. Spearman correlation between readers was 0.822. Volume correlated with pTN stages and OS, best defined by 3 groups with average volumes of: 91.2, 245.3, 511.3cm3, associated with median OS of 37, 18, 8 months respectively. Conclusions For the first time, a multicenter network was established and initial correlations of tumor volume to pTN stages and OS shown. A larger multicenter international study is planned to confirm results and refine correlations.

Volumetric assessment in malignant pleural mesothelioma

“…Tumor volume correlated significantly with pathological T stage, pathological N stage, as well as with overall survival. The study group found that dividing the patients into three groups, best defined by average tumor volumes of 91, 245 and 511 cm 3 respectively had prognostic significance superior to traditional clinical T staging, with median survival of 37, 18 and 8 months respectively for the three groupings (40). The finding that patients with a tumor volume of greater than 500 cm 3 have a worse overall survival is in line with previous single-institution studies on tumor volumes in MPM (34,39).…”

“…Proprietary software allowing semiautomatic voxelbased three-dimensional tumor segmentation is now readily available, and was used in the recent multicenter study on CT-derived tumor volume (Vitrea Enterprise, Vital images, Minnetonka, MN, USA) (20,40). This type of software first automatically segments the tumor volume based on adjustable Hounsfield unit (HU) values (20-80 HU), followed by manual correction of the tumor contours by the radiologist.…”

North American Multicenter Volumetric CT Study for Clinical Staging of Malignant Pleural Mesothelioma: Feasibility and Logistics of Setting Up a Quantitative Imaging Study

“…There was a significant correlation of pathological T stage with increase in tumor volume. Tumor volume correlated with pathological T stage and overall survival (the results are being reported in a separate manuscript 11 .…”

“…Secondary objectives included identifying potential sources of interobserver variability associated with tumor volume estimates and clinical T classification as assessed by standard CT, and determining to what degree tumor volume corresponds to pathologic T classification. Additional secondary outcomes, including whether tumor volume corresponds to pathologic N classification or tumor histology and whether it is prognostic for progression-free and/or overall survival, were also assessed and are reported in a separate manuscript 11 .…”

Is Pleurectomy/Decortication Superior to Extrapleural Pneumonectomy for Patients with Malignant Pleural Mesothelioma? A Single-Institutional Experience

“…The IMIG staging system was revised to version 8 in 2017. 23) In addition, the maximum thickness and sum of three-level thickness 24) and CT volume of the tumor 25) were introduced to more precisely reflect the prognosis of patients with MPM. In Japan, data regarding newly diagnosed MPM are being prospectively collected from 2017 to 2018 by the Japanese Joint Committee for Lung Cancer Registration not only to investigate epidemiology and treatment choices, but also in anticipation of the validation of version 8 of the IMIG staging system.…”