Repeatability of rectal cancer apparent diffusion coefficient measurements on a 1.5 T MR-linac

Hidde Eijkelenkamp; Guus Grimbergen; Brigid McDonald; Reijer Rutgers; Tim Schakel; Casper Beijst; Marielle Philippens; Gert Meijer; Martijn Intven

doi:10.1016/j.phro.2025.100720

Repeatability of rectal cancer apparent diffusion coefficient measurements on a 1.5 T MR-linac

Hidde Eijkelenkamp^*, Guus Grimbergen, Brigid McDonald, Reijer Rutgers, Tim Schakel, Casper Beijst, Marielle Philippens, Gert Meijer, Martijn Intven

^*Corresponding author for this work

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Abstract

The repeatability of the apparent diffusion coefficient (ADC) during radiotherapy for rectal cancer on a 1.5 T MR-linac was investigated by acquiring two sequential diffusion-weighted imaging (DWI) sequences at each fraction. In 109 treatment sessions involving 22 patients, tumors were separately delineated on the b500 images. ADC maps were generated with all b-values (0, 30, 150, and 500 s/mm²) on the MR-linac, and the median ADC values were used in Bland-Altman analyses. A relative repeatability coefficient of 17.0 % was determined, providing a threshold to differentiate between measurement variability and true treatment response. This threshold can be used for potential response monitoring and personalized treatment adjustments.

Original language	English
Article number	100720
Journal	Physics and Imaging in Radiation Oncology
Volume	33
DOIs	https://doi.org/10.1016/j.phro.2025.100720
Publication status	Published - Jan 2025

Keywords

Apparent diffusion coefficient (ADC)
Diffusion-weighted imaging (DWI)
Rectal cancer
Repeatability MR-guided radiotherapy

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title = "Repeatability of rectal cancer apparent diffusion coefficient measurements on a 1.5 T MR-linac",

abstract = "The repeatability of the apparent diffusion coefficient (ADC) during radiotherapy for rectal cancer on a 1.5 T MR-linac was investigated by acquiring two sequential diffusion-weighted imaging (DWI) sequences at each fraction. In 109 treatment sessions involving 22 patients, tumors were separately delineated on the b500 images. ADC maps were generated with all b-values (0, 30, 150, and 500 s/mm2) on the MR-linac, and the median ADC values were used in Bland-Altman analyses. A relative repeatability coefficient of 17.0 % was determined, providing a threshold to differentiate between measurement variability and true treatment response. This threshold can be used for potential response monitoring and personalized treatment adjustments.",

keywords = "Apparent diffusion coefficient (ADC), Diffusion-weighted imaging (DWI), Rectal cancer, Repeatability MR-guided radiotherapy",

author = "Hidde Eijkelenkamp and Guus Grimbergen and Brigid McDonald and Reijer Rutgers and Tim Schakel and Casper Beijst and Marielle Philippens and Gert Meijer and Martijn Intven",

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doi = "10.1016/j.phro.2025.100720",

language = "English",

volume = "33",

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T1 - Repeatability of rectal cancer apparent diffusion coefficient measurements on a 1.5 T MR-linac

AU - Eijkelenkamp, Hidde

AU - Grimbergen, Guus

AU - McDonald, Brigid

AU - Rutgers, Reijer

AU - Schakel, Tim

AU - Beijst, Casper

AU - Philippens, Marielle

AU - Meijer, Gert

AU - Intven, Martijn

PY - 2025/1

Y1 - 2025/1

N2 - The repeatability of the apparent diffusion coefficient (ADC) during radiotherapy for rectal cancer on a 1.5 T MR-linac was investigated by acquiring two sequential diffusion-weighted imaging (DWI) sequences at each fraction. In 109 treatment sessions involving 22 patients, tumors were separately delineated on the b500 images. ADC maps were generated with all b-values (0, 30, 150, and 500 s/mm2) on the MR-linac, and the median ADC values were used in Bland-Altman analyses. A relative repeatability coefficient of 17.0 % was determined, providing a threshold to differentiate between measurement variability and true treatment response. This threshold can be used for potential response monitoring and personalized treatment adjustments.

AB - The repeatability of the apparent diffusion coefficient (ADC) during radiotherapy for rectal cancer on a 1.5 T MR-linac was investigated by acquiring two sequential diffusion-weighted imaging (DWI) sequences at each fraction. In 109 treatment sessions involving 22 patients, tumors were separately delineated on the b500 images. ADC maps were generated with all b-values (0, 30, 150, and 500 s/mm2) on the MR-linac, and the median ADC values were used in Bland-Altman analyses. A relative repeatability coefficient of 17.0 % was determined, providing a threshold to differentiate between measurement variability and true treatment response. This threshold can be used for potential response monitoring and personalized treatment adjustments.

KW - Apparent diffusion coefficient (ADC)

KW - Diffusion-weighted imaging (DWI)

KW - Rectal cancer

KW - Repeatability MR-guided radiotherapy

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U2 - 10.1016/j.phro.2025.100720

DO - 10.1016/j.phro.2025.100720

M3 - Article

AN - SCOPUS:85218881413

SN - 2405-6316

VL - 33

JO - Physics and Imaging in Radiation Oncology

JF - Physics and Imaging in Radiation Oncology

M1 - 100720

ER -

Repeatability of rectal cancer apparent diffusion coefficient measurements on a 1.5 T MR-linac

Abstract

Keywords

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