An Automated Multiparametric MRI Quantitative Imaging Prostate Habitat Risk Scoring System for Defining External Beam Radiotherapy Boost Volumes

Publication date: Available online 13 June 2018
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Radka Stoyanova, Felix Chinea, Deukwoo Kwon, Isildinha M. Reis, Yohann Tschudi, Nestor A. Parra, Adrian L. Breto, Kyle R. Padgett, Alan Dal Pra, Matthew C. Abramowitz, Oleksandr N. Kryvenko, Sanoj Punnen, Alan Pollack
PurposeTo develop a prostate tumor habitat risk scoring (HRS) system based on multiparametric MRI (mpMRI) referenced to prostatectomy Gleason Score (GS) for automatic delineation of Gross Tumor Volumes (GTVs). A workflow for integration of HRS into radiotherapy (RT) boost volume dose escalation was developed in the framework of a Phase II randomized clinical trial (BLaStM).Materials and MethodsAn automated quantitative mpMRI based 10 point pixel by pixel method was optimized to prostatectomy GSs and volumes using referenced Dynamic Contrast Enhanced and Apparent Diffusion Coefficient sequences. The HRS contours were migrated to the planning CT for boost volume generation.ResultsThere were 51 regions of interest (ROIs) in 12 patients who underwent radical prostatectomy (RP) (26 with GS≥7 and 25 with GS6). The resultant heat maps showed inter- and intra-tumoral heterogeneity. The HRS6 level was significantly associated with RP ROIs (slope 1.09, r=0.767; p<.0001). For predicting the likelihood of cancer, GS≥7 and GS≥8, HRS6 AUCs were 0.718, 0.802 and 0.897, respectively. HRS was superior to the Prostate Imaging, Reporting and Diagnosis System 4/5 classification, wherein the AUCs were 0.62, 0.64 and 0.617, respectively (difference with HR6, p<.0001). HRS maps were created for the first 37 assessable patients on the BLaStM trial. There were an average of 1.38 habitat boost volumes per patient at a total boost volume average of 3.6 cc.ConclusionsAn automated quantitative mpMRI based method was developed to objectively guide dose escalation to high risk habitat volumes based on prostatectomy GS.

Teaser

Prostate multiparamateric MRI has a high sensitivity and specificity for identifying tumor regions in the prostate; but, there is subjectivity in defining high risk 3D volumes that could be boosted, as opposed to entire prostate dose escalation. Registering to prostatectomy Gleason score, a habitat risk score based on pixel by pixel quantitative diffusion and perfusion was developed and then applied to guiding radiotherapy boost volumes in the background of a randomized Phase II clinical trial.


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