MRI findings of radiation-induced changes of masticatory muscles: A systematic review

Abstract

BackgroundRadiotherapy to the head and neck regions can result in serious consequences to the temporomandibular joint (TMJ) and chewing muscles. Magnetic resonance imaging (MRI) demonstrates soft-tissue alterations after radiotherapy, such as morphology and signal intensity.ObjectiveThe purpose of this review is to critically and systematically analyse the available evidence regarding the masticatory muscles alterations, as demonstrated on MRI, after radiotherapy for head and neck cancer.Data sourcesElectronic search of MEDLINE, EMBASE, EBM reviews and Scopus.Inclusion criteriaReports of any study design investigating radiation-induced changes in masticatory muscles after radiotherapy in patients with head and neck cancer were included.Results and synthesis methodsAn electronic database search resulted in 162 papers. Sixteen papers were initially selected as potentially relevant studies; however, only four papers satisfied all inclusion criteria. The included papers focused on the MRI appearance of masticatory muscles following radiotherapy protocol. Two papers reported outcome based on retrospective clinical and imaging records, whereas the remaining two papers were case reports. Irradiated muscles frequently show diffuse increase in T2 signal and post-gadolinium enhancement post-irradiation. Also, muscle size changes were reported based on subjective comparison with the contralateral side. The quality of all included papers was considered poor with high risk of bias.ConclusionThere is no evidence that MRI interpretations indicate specific radiation-induced changes in masticatory muscles. There is a clear need for a cohort study comparing patients with pre- and post-radiotherapy MRI.

Limited mouth opening in oral submucous fibrosis: reasons, ramifications, and remedies

“…1). A progressive decrease in the MO even after the cessation of RT (1-3) and linear decrease in MO with an increase in radiation dose (1,3,4) substantiates its deleterious effects. A fact, which is often overlooked in oral submucous fibrosis (OSF), is the direct effect of mucositis on MO (5).…”

Restoration of Facial Form and Lip Competence in a Patient with a Midfacial Defect

“…These may all occur concomitantly. A progressive decrease in the mouth opening after the cessation of radiation therapy and linear decrease in mouth opening with an increase in radiation dose substantiates its deleterious effects. An often overlooked fact in oral submucous fibrosis is the direct effect of mucositis on mouth opening .…”

Texture analysis of T1‐w and T2‐w MR images allows a quantitative evaluation of radiation‐induced changes of internal obturator muscles after radiotherapy for prostate cancer

“…The main innovation of our work, with respect to the previous ones based on MRI muscle evaluation, was in the assessment of textural features, in addition to the simple mean intensity. This approach allowed to quantify the tissue spatial organization within the whole structure before and after irradiation.…”

“…However, stronger changes were found after irradiation and the clear exponential relationship between mean signal intensity and radiation dose resulting from the present study may confirm the hypothesis that high signal intensity can help to detect muscle insult by radiotherapy. The main innovation of our work, with respect to the previous ones based on MRI muscle evaluation, 17,18,20,41 was in the assessment of textural features, in addition to the simple mean intensity. This approach allowed to quantify the tissue spatial organization within the whole structure before and after irradiation.…”

“…In recent years, the analysis of anatomic MRI, such as T2w and T1-w MRI, with and without contrast agent (CA) injection, has been carried out in some studies to assess radiationinduced effects in muscles, especially after radiotherapy for head and neck cancer (HNC). [17][18][19] Pelvic floor muscles were qualitatively evaluated before and after prostate cancer radiotherapy, focusing, in particular, on internal obturator muscles and levator ani muscles. 20 MRI findings revealed an increase in T2-w signal and T1-w contrast enhancement, compatible with a radiation-induced inflammation.…”