Contouring of prostate tumors on multiparametric MRI: Evaluation of clinical delineations in a multicenter radiotherapy trial

To date no guidelines are available for contouring prostate cancer inside the gland, as visible on multiparametric (mp-) MRI. We assessed inter-institutional differences in interpretation of mp-MRI in the multicenter phase III FLAME trial. We analyzed clinical delineations on mp-MRI and clinical cha...

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Bibliographic Details
Published in:Radiotherapy and oncology 2018-08, Vol.128 (2), p.321-326
Main Authors: van Schie, Marcel A., Dinh, Cuong V., Houdt, Petra J. van, Pos, Floris J., Heijmink, Stijn W.T.J.P., Kerkmeijer, Linda G.W., Kotte, Alexis N.T.J., Oyen, Raymond, Haustermans, Karin, van der Heide, Uulke A.
Format: Article
Language:English
Subjects:
Aged
Aged, 80 and over
Area Under Curve
FLAME
Humans
Magnetic Resonance Imaging - methods
Male
Middle Aged
Multicenter trial
Multiparametric MRI
Neoplasm Grading
Prostate cancer
Prostatic Neoplasms - pathology
Prostatic Neoplasms - radiotherapy
ROC Curve
Tumor delineation
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Summary:To date no guidelines are available for contouring prostate cancer inside the gland, as visible on multiparametric (mp-) MRI. We assessed inter-institutional differences in interpretation of mp-MRI in the multicenter phase III FLAME trial. We analyzed clinical delineations on mp-MRI and clinical characteristics from 260 patients across three institutes. We performed a logistic regression analysis to examine each institute’s weighting of T2w, ADC and Ktrans intensity maps in the delineation of the cancer. As reviewing of all delineations by an expert panel is not feasible, we made a selection based on discrepancies between a published tumor probability (TP) model and each institute’s clinical delineations using Areas Under the ROC Curve (AUC) analysis. Regression coefficients for the three institutes were −0.07, −0.27 and −0.11 for T2w, −1.96, −0.53 and −0.65 for ADC and 0.15, 0.20 and 0.62 for Ktrans, with significant differences between institutes for ADC and Ktrans. AUC analysis showed median AUC values of 0.92, 0.80 and 0.79. Five patients with lowest AUC values were reviewed by a uroradiologist. Regression coefficients revealed considerably different interpretations of mp-MRI in tumor contouring between institutes and demonstrated the need for contouring guidelines. Based on AUC values outlying delineations could efficiently be identified for review.
ISSN:0167-8140
1879-0887
DOI:10.1016/j.radonc.2018.04.015