174 Chapter 7 in lowered metabolism and need for oxygen. Conclusively, the various metabolic and vascular changes that can occur after radiotherapy highlight the complexity of radiation-induced damage. These complex and multifaceted changes in the brain may partially explain the large individual differences in radiation-induced cognitive decline experienced by patients with brain metastases.20 Non-invasive, sensitive MRI biomarkers are needed to better understand radiotherapy-related changes in the brain and its subsequent effect on neurocognitive functioning. With this in mind, the main aim of the current study was to assess the added value of using physiological imaging techniques to assess CVR, CBF, OEF and CMRO2 in both healthy appearing tissue and malignant tissue before and after stereotactic radiosurgery (SRS) in patients with brain metastases. Acquiring both OEF and CBF in the same scan session can provide insight as to whether changes in brain oxygen metabolism (i.e. CMRO2) occur due to abundant or insufficient blood supply or because the tissue itself has (partly) lost the ability to extract and consume oxygen. The addition of a CVR measurement can give insight into the regulatory state of the tissue at baseline. As a secondary analysis, we investigated cognitive changes after radiotherapy in relation to changes in these physiological MRI parameters on a case-by-case basis. This preliminary study aims to establish a foundational framework for advancing our understanding of radiation-induced brain damage and its relation to cognitive functioning, thereby providing a basis to generate novel hypotheses to guide future research. METHODS Study set-up and population MRI datasets were acquired between October 2022 and February 2023 for the ongoing Assessing and Predicting Radiation Influence on Cognitive Outcome using the cerebrovascular stress Test (APRICOT) study. Participation consists of an elaborate neurocognitive assessment (NCA) and MRI before radiotherapy and approximately three months after radiotherapy. The study population consists of adult patients (≥18 years) with either radiographic and/or histologic proof of metastatic disease in the brain that were referred to the radiotherapy department of the UMC Utrecht for radiotherapy of the brain metastases. Specific in- and exclusion criteria for participation in the APRICOT study are listed in the Supplementary Materials. The study was performed in accordance with the Declaration of Helsinki21 and the UMCU institutional ethical review approved the study (METC# 18-747). Written informed consent was obtained from all participants prior to participation.
RkJQdWJsaXNoZXIy MTk4NDMw