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Purpose: Treatment response assessment for gliomas currently uses changes in tumour size as measured with T 1 - and T 2 -weighted MRI. However, changes in tumour size may occur many weeks after therapy completion and are confounded by radiation treatment effects. Advanced MRI techniques sensitive to tumour physiology may provide complementary information to evaluate tumour response at early timepoints during therapy. The objective of this review is to provide a summary of the history and current knowledge regarding advanced MRI techniques for early treatment response evaluation in glioma., Methods: The literature survey included perfusion MRI, diffusion-weighted imaging, quantitative magnetization transfer imaging, and chemical exchange transfer MRI. Select articles spanning the history of each technique as applied to treatment response evaluation in glioma were chosen. This report is a narrative review, not formally systematic., Results: Chemical exchange saturation transfer imaging potentially offers the earliest method to detect tumour response due to changes in metabolism. Diffusion-weighted imaging is sensitive to changes in tumour cellularity later during radiotherapy and is prognostic for progression-free and overall survival. Substantial evidence suggests that perfusion MRI can differentiate between tumour recurrence and treatment effect, but consensus regarding acquisition, processing, and interpretation is still lacking. Magnetization transfer imaging shows promise for detecting subtle white matter damage which could indicate tumour invasion, but more research in this area is needed., Conclusion: Advanced MRI techniques show potential for early treatment response assessment, but each technique alone lacks specificity. Multiparametric imaging may be necessary to aid biological interpretation and enable treatment guidance., Competing Interests: Declarations Ethical approval The studies used to generate the figures in this article were granted ethics approval by our institution’s Research Ethics Board. Consent to participate Written informed consent was obtain from all individual participants in the studies used for the figures in this article, including consent to publish anonymized data. Consent to publish See above. Competing interests LSPL has accepted travel expenses from Elekta. AS has research grants with Elekta, BrainLab, and Seagen Inc. He has been a consultant for Elekta and BrainLab. He has received honoraria for educational seminars from Elekta, Varian, BrainLab, AstraZeneca, Seagen Inc, Cerapedics, CarboFIX, and Servier. He has also accepted travel expenses from Elekta, BrainLab, and Cerapedics. He is the President of the International Stereotactic Radiosurgery Society (ISRS). SD serves as the Provincial Lead for CNS Cancers at Ontario Health (Cancer Care Ontario). He receives royalties from Oxford University Press and research funding from Synaptive, VPiX and Cure51. He is a speaker for the American Association of Neurological Surgeons and Congress of Neurological Surgeons and is on the advisory board of the Subcortical Surgery Group. PJM, GJS, and AZL have no relevant financial or non-financial interests to disclose., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Pyroglutamic acidosis (PGA) or 5-Oxoprolinuria is an uncommon and often overlooked cause of high anion gap metabolic acidosis (HAGMA). This case highlights the importance of systematically approaching HAGMA, and to consider PGA as a differential diagnosis when medications that disrupt the γ-glutamyl cycle such as flucloxacillin and paracetamol are present., Competing Interests: Aaron Yee Shuen See, Asthon Zheng‐Boon Lau, Srivathsan Thiruvengadam have none to declare., (© 2024 The Author(s). Clinical Case Reports published by John Wiley & Sons Ltd.)

Chemoradiotherapy is the standard treatment after maximal safe resection for glioblastoma (GBM). Despite advances in molecular profiling, surgical techniques, and neuro-imaging, there have been no major breakthroughs in radiotherapy (RT) volumes in decades. Although the majority of recurrences occur within the original gross tumor volume (GTV), treatment of a clinical target volume (CTV) ranging from 1.5 to 3.0 cm beyond the GTV remains the standard of care. Over the past 15 years, the incorporation of standard and functional MRI sequences into the treatment workflow has become a routine practice with increasing adoption of MR simulators, and new integrated MR-Linac technologies allowing for daily pre-, intra- and post-treatment MR imaging. There is now unprecedented ability to understand the tumor dynamics and biology of GBM during RT, and safe CTV margin reduction is being investigated with the goal of improving the therapeutic ratio. The purpose of this review is to discuss margin strategies and the potential for adaptive RT for GBM, with a focus on the challenges and opportunities associated with both online and offline adaptive workflows. Lastly, opportunities to biologically guide adaptive RT using non-invasive imaging biomarkers and the potential to define appropriate volumes for dose modification will be discussed., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)