Emerging Magnetic Resonance Imaging Technologies for Radiation Therapy Planning and Response Assessment

Abstract

Functional and molecular MRI techniques are capable of measuring biologic properties of tumor tissue. Knowledge of these biological properties may improve radiation treatment by more accurately identifying tumor volumes, characterizing radioresistant subvolumes of tumor before radiation therapy (RT), and identifying recurrent disease after RT. Intravoxel incoherent motion MRI, blood oxygenation level-dependent MRI, tissue oxygenation level-dependent MRI, hyperpolarized C MRI, and chemical exchange saturation transfer MRI are relatively new MRI techniques that have shown promise for contributing to RT planning and response assessment. This review critically evaluates these emerging MR techniques, their potential role in RT planning, utility to date, and challenges to integration into the current clinical workflow.

Current multidisciplinary management of brain metastases

“…As a result, other MRI techniques have been investigated to better distinguish between radionecrosis and recurrent BMs, such as MR spectroscopy (in particular, chemical exchange saturation transfer) and perfusion‐weighted MRI to evaluate relative cerebral blood volume and intravoxel incoherent motion, with variable success . Nuclear medicine imaging has also been used to help identify active tumor versus radionecrosis, with particular interest in the use of amino acid tracers in PET‐CTs .…”

“…Cancer April 1, 2020 and recurrent BMs, such as MR spectroscopy (in particular, chemical exchange saturation transfer) and perfusion-weighted MRI to evaluate relative cerebral blood volume and intravoxel incoherent motion, with variable success. [100][101][102][103] Nuclear medicine imaging has also been used to help identify active tumor versus radionecrosis, with particular interest in the use of amino acid tracers in PET-CTs. 98,100 Most studies, however, are small and often do not include pathologic confirmation, making it difficult to determine their true accuracy.…”

Laser‐driven radiation: Biomarkers for molecular imaging of high dose‐rate effects

“…), their detection by noninvasive methods is challenging in cell cultures and even more so in complex organisms. The persisting free radicals generated by high dose‐rate radiation can be measured in cells by: (a) electron spin resonance (ESR) combined with the use of radical‐specific spin traps, provided the latter are biocompatible or (b) spectroscopic methods whereby the effects of the irradiation of free radicals on biomolecules are amenable to in vivo monitoring …”

“…In terms of the minimum quantity of a tracer molecule needed for detection, MR‐based techniques using stable isotopes are less sensitive than PET. However, they are more flexible in terms of setup and can be used to image therapy effects noninvasively as often as clinically necessary after initial and subsequent radiotherapy sessions . Chemotherapy, photodynamic therapy, or other treatments can be equally followed .…”

“…However, they are more flexible in terms of setup and can be used to image therapy effects noninvasively as often as clinically necessary after initial and subsequent radiotherapy sessions. 19 Chemotherapy, photodynamic therapy, or other treatments can be equally followed. 11,[20][21][22] Molecular monitoring of radiation effects by MR allows for translation of laboratory research to the clinic, as parallel in-cell, ex vivo (on biological samples stemming from patients) and in vivo imaging of the effects of radiation can be conducted with the same approach.…”