MRI-guided Pelvic Radiation Therapy: A Primer for Radiologists.
Jim ZhongMarta KobusPriyamvada MaitreAnubhav DattaCynthia L EcclesMichael DubecDamien J McHughDavid L BuckleyAndrew ScarsbrookPeter HoskinAnn HenryAnanya ChoudhuryPublished in: Radiographics : a review publication of the Radiological Society of North America, Inc (2023)
Radiation therapy (RT) is a core pillar of oncologic treatment, and half of all patients with cancer receive this therapy as a curative or palliative treatment. The recent integration of MRI into the RT workflow has led to the advent of MRI-guided RT (MRIgRT). Using MRI rather than CT has clear advantages for guiding RT to pelvic tumors, including superior soft-tissue contrast, improved organ motion visualization, and the potential to image tumor phenotypic characteristics to identify the most aggressive or treatment-resistant areas, which can be targeted with a more focal higher radiation dose. Radiologists should be familiar with the potential uses of MRI in planning pelvic RT; the various RT techniques used, such as brachytherapy and external beam RT; and the impact of MRIgRT on treatment paradigms. Current clinical experience with and the evidence base for MRIgRT in the settings of prostate, cervical, and bladder cancer are discussed, and examples of treated cases are illustrated. In addition, the benefits of MRIgRT, such as real-time online adaptation of RT (during treatment) and interfraction and/or intrafraction adaptation to organ motion, as well as how MRIgRT can decrease toxic effects and improve oncologic outcomes, are highlighted. MRIgRT is particularly beneficial for treating mobile pelvic structures, and real-time adaptive RT for tumors can be achieved by using advanced MRI-guided linear accelerator systems to spare organs at risk. Future opportunities for development of biologically driven adapted RT with use of functional MRI sequences and radiogenomic approaches also are outlined. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.
Keyphrases
- contrast enhanced
- magnetic resonance imaging
- radiation therapy
- rectal cancer
- diffusion weighted imaging
- computed tomography
- magnetic resonance
- locally advanced
- prostate cancer
- deep learning
- squamous cell carcinoma
- artificial intelligence
- risk assessment
- adipose tissue
- soft tissue
- high dose
- machine learning
- social media
- type diabetes
- insulin resistance
- skeletal muscle
- metabolic syndrome
- mesenchymal stem cells
- combination therapy
- minimally invasive
- positron emission tomography
- low dose
- bone marrow
- robot assisted
- current status
- high speed
- pet ct