Nasopharyngeal carcinoma (NPC) is a common malignancy endemic in South-East Asia. Functional magnetic resonance imaging (fMRI) has been used for prompt detection of treatment response before visible morphological changes in NPC treatment. Among different fMRI techniques, diffusion-weighted imaging (DWI) and dynamic contrast enhancement (DCE) were proved to be more successful in NPC treatment response assessment whilst the application of magnetic resonance spectroscopy (MRS) remains questionable. Apart from discussing the imaging technique, time points for post-treatment response assessments are recommended. Four instead of three months is recommended for prompt identification of non- or partial responders and 6–9 months post-treatment multiparametric MRI is also recommended for effective confirmation of complete responding individuals to avoid residual disease. For future advancement, in addition to the post-treatment response assessment, continuous or longitudinal assessment on the treatment response with the use of magnetic resonance simulator (MR-simulator) or magnetic resonace imaging guided linear accelerator (MR-Linac) tailor-made for radiotherapy (RT) maybe feasible. Longitudinal assessments or predictive radiomics modeling allow spotting out the possibility of treatment failure before the completion or even before the start of treatments. Adaptive instead of salvage treatments can then be prepared, thus reducing the damage and side effects of consecutive cytotoxic treatments.

Magnetic resonance imaging (MRI) is becoming increasingly important in precision radiotherapy owing to its excellent soft-tissue contrast and versatile scan options. Many recent advances in MRI have been shown to be promising for MRI-guided radiotherapy and for improved treatment outcomes. This paper summarizes these advances into six sections: MRI simulators, MRI-linear accelerator hybrid machines, MRI-only workflow, four-dimensional MRI, MRI-based radiomics, and magnetic resonance fingerprinting. These techniques can be implemented before, during, or after radiotherapy for various precision radiotherapy applications, such as tumor delineation, tumor motion management, treatment adaptation, and clinical decision making. For each of these techniques, this paper describes its technical details and discusses its clinical benefits and challenges.