{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T11:33:49Z","timestamp":1788262429676,"version":"build-2803163510"},"reference-count":38,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2026,5,13]],"date-time":"2026-05-13T00:00:00Z","timestamp":1778630400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100009736","name":"Allm\u00e4nna sjukhusets i Malm\u00f6 Stiftelse f\u00f6r bek\u00e4mpande av cancer","doi-asserted-by":"publisher","award":["20211025"],"award-info":[{"award-number":["20211025"]}],"id":[{"id":"10.13039\/501100009736","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Fru Berta Kamprads stiftelse f\u00f6r forskning och bek\u00e4mpning av cancersjukdomar","award":["FBKS2024-4 569"],"award-info":[{"award-number":["FBKS2024-4 569"]}]},{"name":"SUS stiftelser och donationer","award":["241120-3269"],"award-info":[{"award-number":["241120-3269"]}]},{"DOI":"10.13039\/501100003461","name":"Gunnar Nilssons Cancerstiftelse","doi-asserted-by":"publisher","award":["GN-2021-8-225"],"award-info":[{"award-number":["GN-2021-8-225"]}],"id":[{"id":"10.13039\/501100003461","id-type":"DOI","asserted-by":"publisher"}]},{"award":["GN-2021-8-225"],"award-info":[{"award-number":["GN-2021-8-225"]}],"id":[{"id":"https:\/\/ror.org\/00292rj97","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Regionala forskningsmedel S\u00f6dra sjukv\u00e5rdsregionen","award":["Doktorand-2021-0837"],"award-info":[{"award-number":["Doktorand-2021-0837"]}]},{"DOI":"10.13039\/501100002794","name":"Cancerfonden","doi-asserted-by":"publisher","award":["22 0592 JIA"],"award-info":[{"award-number":["22 0592 JIA"]}],"id":[{"id":"10.13039\/501100002794","id-type":"DOI","asserted-by":"publisher"}]},{"award":["22 0592 JIA"],"award-info":[{"award-number":["22 0592 JIA"]}],"id":[{"id":"https:\/\/ror.org\/0527jb766","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Tomography"],"abstract":"<jats:p>Objectives: Early identification of treatment response in brain metastases remains clinically challenging. This study explores tensor-valued diffusion MRI (dMRI), specifically q-space trajectory imaging (QTI), as a novel source of early imaging biomarkers during stereotactic radiotherapy (SRT). Methods: Twenty-six patients with brain metastases were enrolled; thirteen met quality and completeness criteria for QTI analysis (10 responders, three non-responders). MRI was acquired at four time points: before SRT, before final SRT fraction, and at 3 and 6 months post-SRT. QTI-derived metrics included mean diffusivity (MD), fractional anisotropy (FA), microscopic FA (\u00b5FA), and isotropic (MKI) and anisotropic (MKA) diffusional variance. Parameter values within the tumour volume were compared pre- and during SRT and correlated with treatment response from standard MRI follow-up. Overall survival was assessed using Kaplan\u2013Meier analysis. Results: Median survival was 12 months. QTI analysis was feasible with visible changes in the tumour tissue parameter maps over time. Statistically significant differences (p &lt; 0.05) were found between responders and non-responders in FA before treatment. MKI in responders was significantly lower (p &lt; 0.05) during SRT than before. Conclusions: This study presents a first exploration of QTI-derived parameters in a cohort of patients with brain metastases. We demonstrate feasibility and a scalable workflow, supporting further investigation in larger cohorts and in patients with larger or more stable lesions.<\/jats:p>","DOI":"10.3390\/tomography12050071","type":"journal-article","created":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T16:46:18Z","timestamp":1779381978000},"page":"71","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Tensor-Valued Diffusion MRI for Microstructural Assessment During Stereotactic Radiotherapy of Brain Metastases: A Feasibility Study"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1968-4874","authenticated-orcid":false,"given":"Minna","family":"Lerner","sequence":"first","affiliation":[{"name":"Department of Translational Medicine, Medical Radiation Physics, Lund University, Sk\u00e5ne University Hospital Malm\u00f6, SE-205 02 Malm\u00f6, Sweden"},{"name":"Department of Hematology, Oncology and Radiation Physics, Sk\u00e5ne University Hospital, Klinikgatan 5, SE-221 85 Lund, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patrik","family":"Brynolfsson","sequence":"additional","affiliation":[{"name":"Department of Translational Medicine, Medical Radiation Physics, Lund University, Sk\u00e5ne University Hospital Malm\u00f6, SE-205 02 Malm\u00f6, Sweden"},{"name":"Department of Hematology, Oncology and Radiation Physics, Sk\u00e5ne University Hospital, Klinikgatan 5, SE-221 85 Lund, Sweden"},{"name":"Hero Imaging AB, Norra Gimon\u00e4sv\u00e4gen 39, SE-90738 Ume\u00e5, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5251-587X","authenticated-orcid":false,"given":"Filip","family":"Szczepankiewicz","sequence":"additional","affiliation":[{"name":"Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, Barngatan 4, Sk\u00e5ne University Hospital Lund, SE-221 85 Lund, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7217-7054","authenticated-orcid":false,"given":"Joakim","family":"Medin","sequence":"additional","affiliation":[{"name":"Department of Hematology, Oncology and Radiation Physics, Sk\u00e5ne University Hospital, Klinikgatan 5, SE-221 85 Lund, Sweden"},{"name":"Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, Barngatan 4, Sk\u00e5ne University Hospital Lund, SE-221 85 Lund, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9237-1236","authenticated-orcid":false,"given":"Pia C.","family":"Sundgren","sequence":"additional","affiliation":[{"name":"Department of Diagnostic Radiology, Clinical Sciences Lund, Lund University, Sk\u00e5ne University Hospital Lund, SE-221 85 Lund, Sweden"},{"name":"Lund BioImaging Centre (LBIC), Lund University, Klinikgatan 32, SE-221 84 Lund, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6090-6697","authenticated-orcid":false,"given":"Lars E.","family":"Olsson","sequence":"additional","affiliation":[{"name":"Department of Translational Medicine, Medical Radiation Physics, Lund University, Sk\u00e5ne University Hospital Malm\u00f6, SE-205 02 Malm\u00f6, Sweden"},{"name":"Department of Hematology, Oncology and Radiation Physics, Sk\u00e5ne University Hospital, Klinikgatan 5, SE-221 85 Lund, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8683-9971","authenticated-orcid":false,"given":"Sara","family":"Alkner","sequence":"additional","affiliation":[{"name":"Department of Hematology, Oncology and Radiation Physics, Sk\u00e5ne University Hospital, Klinikgatan 5, SE-221 85 Lund, Sweden"},{"name":"Department of Clinical Sciences Lund, Oncology and Pathology, Lund University, S\u00f6lvegatan 19, BMC I12, SE-221 84 Lund, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1016\/j.prro.2022.02.003","article-title":"Radiation Therapy for Brain Metastases: An ASTRO Clinical Practice Guideline","volume":"12","author":"Gondi","year":"2022","journal-title":"Pract. 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