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. 2023 Dec 1;117(5):1145-1152.
doi: 10.1016/j.ijrobp.2023.07.004. Epub 2023 Jul 14.

ReIGNITE Radiation Therapy Boost: A Prospective, International Study of Radiation Oncologists' Accuracy in Contouring Prostate Tumors for Focal Radiation Therapy Boost on Conventional Magnetic Resonance Imaging Alone or With Assistance of Restriction Spectrum Imaging

Asona J Lui  1 , Karoline Kallis  1 , Allison Y Zhong  2 , Troy S Hussain  1 , Christopher Conlin  1 , Leonardino A Digma  3 , Nikki Phan  1 , Ian T Mathews  2 , Deondre D Do  4 , Mariluz Rojo Domingo  4 , Roshan Karunamuni  1 , Joshua Kuperman  5 , Anders M Dale  6 , Ahmed Shabaik  7 , Rebecca Rakow-Penner  8 , Michael E Hahn  5 , Tyler M Seibert  9
Affiliations

ReIGNITE Radiation Therapy Boost: A Prospective, International Study of Radiation Oncologists' Accuracy in Contouring Prostate Tumors for Focal Radiation Therapy Boost on Conventional Magnetic Resonance Imaging Alone or With Assistance of Restriction Spectrum Imaging

Asona J Lui et al. Int J Radiat Oncol Biol Phys. .

Abstract

Purpose: In a phase III randomized trial, adding a radiation boost to tumor(s) visible on MRI improved prostate cancer (PCa) disease-free and metastasis-free survival without additional toxicity. Radiation oncologists' ability to identify prostate tumors is critical to widely adopting intraprostatic tumor radiotherapy boost for patients. A diffusion MRI biomarker, called the Restriction Spectrum Imaging restriction score (RSIrs), has been shown to improve radiologists' identification of clinically significant PCa. We hypothesized that (1) radiation oncologists would find accurately delineating PCa tumors on conventional MRI challenging and (2) using RSIrs maps would improve radiation oncologists' accuracy for PCa tumor delineation.

Methods and materials: In this multi-institutional, international, prospective study, 44 radiation oncologists (participants) and 2 expert radiologists (experts) contoured prostate tumors on 39 total patient cases using conventional MRI with or without RSIrs maps. Participant volumes were compared to the consensus expert volumes. Contouring accuracy metrics included percent overlap with expert volume, Dice coefficient, conformal number, and maximum distance beyond expert volume.

Results: 1604 participant volumes were produced. 40 of 44 participants (91%) completely missed ≥1 expert-defined target lesion without RSIrs, compared to 13 of 44 (30%) with RSIrs maps. On conventional MRI alone, 134 of 762 contour attempts (18%) completely missed the target, compared to 18 of 842 (2%) with RSIrs maps. Use of RSIrs maps improved all contour accuracy metrics by approximately 50% or more. Mixed effects modeling confirmed that RSIrs maps were the main variable driving improvement in all metrics. System Usability Scores indicated RSIrs maps significantly improved the contouring experience (72 vs. 58, p < 0.001).

Conclusions: Radiation oncologists struggle with accurately delineating visible PCa tumors on conventional MRI. RSIrs maps improve radiation oncologists' ability to target MRI-visible tumors for prostate tumor boost.

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Conflict of interest statement

Conflict of Interest Statement:

AJL reports consulting for MIM Software. MEH reports honoraria from Multimodal Imaging Services Corporation and research funding from GE Healthcare. RRP has an equity interest in CorTech Labs and Curemetrix, serves on the Scientific Advisory Board of Imagine Scientific, and receives research funding from GE Healthcare. AMD is a Founder of and holds equity in CorTechs Labs, Inc, and serves on its Scientific Advisory Board. He is a member of the Scientific Advisory Board of Human Longevity, Inc. and receives funding through research agreements with GE Healthcare. TMS reports honoraria from Multimodal Imaging Services Corporation, Varian Medical Systems, and WebMD; he has an equity interest in CorTechs Labs, Inc. and also serves on its Scientific Advisory Board; he has received in-kind research support from GE Healthcare via a research agreement with the University of California San Diego. These companies might potentially benefit from the research results. The terms of these arrangements have been reviewed and approved by the University of California San Diego in accordance with its conflict-of-interest policies.

Figures

Figure 1:
Figure 1:. RSIrs maps improve the accuracy of participant target volumes.
Example target volumes from two patient cases (Case 1: A/B and Case 2: C/D) where participants were provided Conventional MRI alone (T2-weighted, DWI, ADC) (left) images or conventional MRI with RSIrs map (orange heat map) (right). Expert volumes are shown in red in all panes. Select participant volumes are highlighted in shades of blue in (A and C). All participant volumes for each case are displayed in (B and D) as a rainbow heatmap, where the color represents the percentage of participants who included that voxel in their target volume.
Figure 2:
Figure 2:. RSIrs maps reduce the frequency of complete misses by participants.
Complete misses as a percentage of the total attempts per participant on Conventional MRI alone (“Without RSIrs”, red) and with RSIrs (grey). No participant had more complete misses when using RSIrs. The red lines show the magnitude of improvement (reduction in complete misses) for each participant.
Figure 3:
Figure 3:. Summary of System Usability Survey results.
A) Distribution of normalized SUS scores for all participants where figure legend and pink bars highlight Mean (SD). p-value is the result of a two-sided paired t-test. (B and C) 2×2 analysis of number of participants rating the contouring experience B) Acceptable (SUS > 70) and C) Poor (SUS ≤ 50). Percentages are percent of responses rating the contouring experience with RSIrs or without RSIrs and is based on 42 questionnaire responses.
See this image and copyright information in PMC

References

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