ESTRO 2023

Session Item

Head and neck

Session Code: 6005

Session Type: Poster (Digital)

Track: Clinical

MRI changes in Muscles of Mastication during radiotherapy: secondary analysis of PREDICT-HN study

Maura O’Connell, Australia

Presentation Number: PO-1205

Abstract

Abstract Title:

MRI changes in Muscles of Mastication during radiotherapy: secondary analysis of PREDICT-HN study

Authors:

Maura O'Connell¹, Tai Ermongkonchai¹, Daniel Xing², Carlos E. Cardenas³, Benjamin Harris⁴, Carly Barbon⁵, Richard Khor⁶, Houda Bahig⁷, Abdallah Sherif Radwan Mohamed⁸, Clifton Fuller⁹, Sweet Ping Ng²

¹Austin Health, Radiation Oncology , Melbourne , Australia; ²Austin Health, Radiation Oncology, Melbourne , Australia; ³University of Alabama at Birmingham, Radiation Oncology, Alabama , USA; ⁴Austin Health , Radiation Oncology, Melbourne , Australia; ⁵MD Anderson Cancer Centre, Speech-Language Pathology, Houston, USA; ⁶Austin Health, Radiation Oncology, Melbourne , Australia; ⁷Centre hospitalier de l'Université de Montréal (CHUM), Radiation Oncology, Montreal, Canada; ⁸MD Anderson Cancer Centre, Radiation Oncology, Houston, USA; ⁹MD Anderson Cancer Centre , Radiation Oncology, Houston, USA

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Purpose or Objective

Patients undergoing radiotherapy treatment for head and neck cancer experience acute and late toxicities relating to inflammation and subsequent fibrosis of masticatory muscles. This study aims to analyse the changes in apparent diffusion co-efficient (ADC) in muscles of mastication in patients undergoing radiotherapy treatment for head and neck cancer.

Material and Methods

This is a secondary analysis of imaging obtained on the PREDICT-HN study. All patients had a pre- and post- radiotherapy MRI scan and weekly MRI scans during radiotherapy treatment. Pterygoid and masseter muscles were contoured on 50 images and an autocontouring model was generated. Contours for the muscles were autogenerated for other timepoints. These contours were checked by 2 radiation oncologists. The volume of each muscle and ADC values were extracted.

Results

Twenty one patients were included in the analysis. 80% of patients had oropharyngeal cancer. Mean ADC in muscles of mastication (masseter and pterygoids) dropped dramatically between the pre-treatment and week 1 MRI scans, and continue to be low during radiotherapy. The ADC in masseters increase in week 5/6 and post-treatment. The median ADC remained lower than baseline for the duration of treatment in both left and right masseter muscles and increased rapidly on the post-treatment MRI imaging (2-months following treatment) . The median ADC in pterygoid muscles initially decreased but overall increased throughout treatment.

Conclusion

ADC MRI changes observed in muscles of mastication of patients undergoing radiotherapy treatment for head and neck cancer has a non-linear trajectory. The degree of ADC changes observed during these on-treatment and post-treatment MRI scans should be correlated with patients' late effects to assess if ADC could be an early marker to predict for trismus and fibrosis.