Repeatability of diffusion-weighted magnetic resonance imaging in head and neck cancer at a 1.5 T MR-Linac

Jonas Habrich; Simon Boeke; Marcel Nachbar; Konstantin Nikolaou; Fritz Schick; Cihan Gani; Daniel Zips; Daniela Thorwarth

doi:10.1016/j.radonc.2022.07.020

Repeatability of diffusion-weighted magnetic resonance imaging in head and neck cancer at a 1.5 T MR-Linac

Radiother Oncol. 2022 Sep:174:141-148. doi: 10.1016/j.radonc.2022.07.020. Epub 2022 Jul 25.

Authors

Jonas Habrich¹, Simon Boeke², Marcel Nachbar³, Konstantin Nikolaou⁴, Fritz Schick⁵, Cihan Gani⁶, Daniel Zips², Daniela Thorwarth⁷

Affiliations

¹ Section for Biomedical Physics, Department of Radiation Oncology, University of Tübingen, Germany. Electronic address: Jonas.Habrich@med.uni-tuebingen.de.
² German Cancer Consortium (DKTK), Partner Site Tübingen; and German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Radiation Oncology, University of Tübingen, Germany.
³ Section for Biomedical Physics, Department of Radiation Oncology, University of Tübingen, Germany.
⁴ Department of Diagnostic and Interventional Radiology, University of Tübingen, Germany.
⁵ Section for Experimental Radiology, Department of Diagnostic and Interventional Radiology, University of Tübingen, Germany.
⁶ Department of Radiation Oncology, University of Tübingen, Germany.
⁷ Section for Biomedical Physics, Department of Radiation Oncology, University of Tübingen, Germany; German Cancer Consortium (DKTK), Partner Site Tübingen; and German Cancer Research Center (DKFZ), Heidelberg, Germany.

PMID: 35902042
DOI: 10.1016/j.radonc.2022.07.020

Abstract

Background and purpose: Functional information acquired through diffusion-weighted magnetic resonance imaging (DW-MRI) may be beneficial for personalized head and neck cancer (HNC) radiotherapy. Technical validation is required before DW-MRI based radiotherapy interventions can be realized clinically. The aim of this study was to assess the repeatability of apparent diffusion coefficients (ADC) derived from DW-MRI in HNC using echo-planar imaging (EPI) on a 1.5 T MR-Linac.

Material and methods: A total of eleven HNC patients underwent test/retest DW-MRI scans at least once per week during fractionated radiotherapy at the MR-Linac. An EPI DW-MRI test scan (b = 0, 150, 500 s/mm²) was acquired before the start of adaptive MR-guided radiotherapy in addition to an identical retest scan after irradiation. Volumes-of-interest (VOI) were defined manually for parotid (PTs) and submandibular glands (SMs), gross tumor volume (GTV) and lymph nodes (LNs). Mean ADC was calculated for all VOI in all test/retest scans. Absolute/relative repeatability coefficients (RCs/relRCs) as well as intraclass correlation coefficients (ICCs) were determined for all VOIs.

Results: A total of 81 datasets were analyzed. Mean test ADC values were 1380/1416, 950/1010, 1520 and 1344 · 10^-6 mm²/s for left/right SM and PT, GTV and LNs, respectively. Accordingly, RC (relRC) values were determined as 271/281 (19.4/21.8%) and 138/155 (13.3/15.2%), 457 (31.3%) and 310 · 10^-6 mm²/s (23.5%). ICC resulted in 0.80/0.87, 0.97/0.94, 0.75 and 0.83 for left/right SM and PT, GTV and LNs, respectively.

Conclusion: The repeatability of ADC derived from EPI DW-MRI at the 1.5 T MR-Linac appears reasonable to be used for future biologically adapted MR-guided radiotherapy.

Keywords: Diffusion-weighted imaging; Echo-planar imaging; MR guided radiation therapy; MR-Linac; Quantitative MRI; Repeatability.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Diffusion Magnetic Resonance Imaging* / methods
Echo-Planar Imaging
Head and Neck Neoplasms* / diagnostic imaging
Head and Neck Neoplasms* / pathology
Head and Neck Neoplasms* / radiotherapy
Humans
Lymph Nodes / pathology
Magnetic Resonance Imaging
Parotid Gland
Reproducibility of Results