Repeatability of radiotherapy dose-painting prescriptions derived from a multiparametric magnetic resonance imaging model of glioblastoma infiltration

Caterina Brighi; Niels Verburg; Eng-Siew Koh; Amy Walker; Cathy Chen; Sugendran Pillay; Philip C de Witt Hamer; Farhannah Aly; Lois C Holloway; Paul J Keall; David E J Waddington

doi:10.1016/j.phro.2022.06.004

Repeatability of radiotherapy dose-painting prescriptions derived from a multiparametric magnetic resonance imaging model of glioblastoma infiltration

Phys Imaging Radiat Oncol. 2022 Jun 11:23:8-15. doi: 10.1016/j.phro.2022.06.004. eCollection 2022 Jul.

Authors

Caterina Brighi^{1

2}, Niels Verburg^{3

4}, Eng-Siew Koh^{2

5

6}, Amy Walker^{2

5

6}, Cathy Chen⁵, Sugendran Pillay^{5

6

7}, Philip C de Witt Hamer^{3

4}, Farhannah Aly^{2

5

6}, Lois C Holloway^{2

5

6}, Paul J Keall^{1

2}, David E J Waddington^{1

2}

Affiliations

¹ ACRF Image X Institute, Sydney School of Health Sciences, The University of Sydney, Sydney, Australia.
² Ingham Institute for Applied Medical Research, Sydney, Australia.
³ Brain Tumor Center Amsterdam, Amsterdam UMC, Amsterdam, The Netherlands.
⁴ Department of Neurosurgery, Amsterdam UMC, Amsterdam, The Netherlands.
⁵ Liverpool and Macarthur Cancer Therapy Centres, Sydney, Australia.
⁶ South West Sydney Clinical Campus, University of New South Wales, Sydney, Australia.
⁷ Campbelltown Hospital, Sydney, Australia.

Abstract

Background and purpose: Glioblastoma (GBM) patients have a dismal prognosis. Tumours typically recur within months of surgical resection and post-operative chemoradiation. Multiparametric magnetic resonance imaging (mpMRI) biomarkers promise to improve GBM outcomes by identifying likely regions of infiltrative tumour in tumour probability (TP) maps. These regions could be treated with escalated dose via dose-painting radiotherapy to achieve higher rates of tumour control. Crucial to the technical validation of dose-painting using imaging biomarkers is the repeatability of the derived dose prescriptions. Here, we quantify repeatability of dose-painting prescriptions derived from mpMRI.

Materials and methods: TP maps were calculated with a clinically validated model that linearly combined apparent diffusion coefficient (ADC) and relative cerebral blood volume (rBV) or ADC and relative cerebral blood flow (rBF) data. Maps were developed for 11 GBM patients who received two mpMRI scans separated by a short interval prior to chemoradiation treatment. A linear dose mapping function was applied to obtain dose-painting prescription (DP) maps for each session. Voxel-wise and group-wise repeatability metrics were calculated for parametric, TP and DP maps within radiotherapy margins.

Results: DP maps derived from mpMRI were repeatable between imaging sessions (ICC > 0.85). ADC maps showed higher repeatability than rBV and rBF maps (Wilcoxon test, p = 0.001). TP maps obtained from the combination of ADC and rBF were the most stable (median ICC: 0.89).

Conclusions: Dose-painting prescriptions derived from a mpMRI model of tumour infiltration have a good level of repeatability and can be used to generate reliable dose-painting plans for GBM patients.

Keywords: ADC, apparent diffusion coefficient; CSF, cerebrospinal fluid; CTV, clinical target volume; CV, coefficient of variation; DP, dose prescription; DSC, dynamic-susceptibility contrast; Dose-painting; EORTC, European Organisation for Research and Treatment of Cancer; FLAIR, fluid-attenuated inverse recovery; GBM, glioblastoma; GTV, gross tumour volume; Glioblastoma; ICC, intraclass correlation coefficient; Multiparametric MRI; PTV, planned target volume; RC, repeatability coefficient; Radiotherapy; Repeatability; SVZ, subventricular zones; T1CE, T1-weighted post-contrast; TP, tumour probability; VOI, volume of interest; mpMRI, multiparametric MRI; rBF, relative cerebral blood flow; rBV, relative cerebral blood volume; ΔTP, difference in tumour probability between timepoint 2 and timepoint 1; σb2, between-subject variance; σw2, within-subject variance.