ESTRO 2024 - Abstract Book

S4988

Physics - Radiomics, functional and biological imaging and outcome prediction

ESTRO 2024

[2] Siva S, Jackson P, Kron T, Bressel M, Lau E, Hofman M, Shaw M, Chander S, Pham D, Lawrentschuk N, Wong LM. Impact of stereotactic radiotherapy on kidney function in primary renal cell carcinoma: Establishing a dose–response relationship. Radiotherapy and Oncology. 2016 Mar 1;118(3):540-6.

[3] Wang F, Rudin C, Mccormick TH, Gore JL. Modeling recovery curves with application to prostatectomy. Biostatistics. 2019 Oct 1;20(4):549-64.

[4] Abril-Pla O, Andreani V, Carroll C, Dong L, Fonnesbeck CJ, Kochurov M, Kumar R, Lao J, Luhmann CC, Martin OA, Osthege M. PyMC: a modern, and comprehensive probabilistic programming framework in Python. PeerJ Computer Science. 2023 Sep 1;9:e1516.

767

Digital Poster

Intravoxel Incoherent Motion Analysis of Cervical Cancer tumours on 1.5T MR-Linac

Manasi Ingle 1 , Matthew Blackledge 1 , Andreas Wetscherek 1 , Sophie Alexander 2 , Jayde Nartey 2 , Helen McNair 2 , Shaista Hafeez 2 , Shreerang Bhide 2 , Susan Lalondrelle 2 1 The Institute of Cancer Research, Imaging and Radiotherapy, London, United Kingdom. 2 The Royal Marsden Hospital, Radiotherapy, London, United Kingdom

Purpose/Objective:

MR-Linac platforms such as the Elekta Unity can facilitate the online acquisition of functional imaging of tumours longitudinally during treatment. However, due to the gradient specifications of the machine, it is recommended that no higher than b = 500 s/mm2 images are acquired [1]. Apparent diffusion coefficient (ADC) analysis using low b values can lead to perfusion influencing ADC measurements within regions of interest (ROIs) [2]. Intravoxel incoherent motion (IVIM) based analysis can use information from low b- values to characterise perfusion simultaneously with tissue water diffusivity (D), by modelling perfusion fraction (f) and pseudodiffusion (D*) [2]. Data regarding the use of IVIM for predicting outcome to treatment in cervical cancer is available on diagnostic MRI [3], but to the best of our knowledge there is no available data using IVIM on MR-Linac platforms. Here we present preliminary data in IVIM analysis in cervical cancer on MR-Linac in patients treated with chemoradiotherapy.

Material/Methods:

Between Jan 2021 and August 2022 patients diagnosed with cervical cancer requiring chemoradiotherapy treatment and suitable for MRI scanning were recruited to institutional based studies and imaged on 1.5T Elekta Unity MR-Linac in accordance to guidelines developed by a global research consortium [1] weekly during treatment. MRI sequences are identical in all visits. ROIs include cervical gross tumour volume (GTV) and normal rectal tissue. GTV was contoured on b=500 s/mm2 images, whereas rectal tissue is contoured on b=0 s/mm2. Using an in-house tool, signal intensities within ROIs are measured, and D, f and D* are calculated for each fraction [2]. Means of D, f and D* factors are plotted weekly, and non-parametric t-testing is performed between first and last fractions for each factor.