title: Use of diffusion-weighted MRI to modify radiosurgery planning in brain metastases may reduce local recurrence.
abstract: Stereotactic radiosurgery (SRS) is an effective and well tolerated treatment for selected brain metastases; however, local recurrence still occurs. We investigated the use of diffusion weighted MRI (DWI) as an adjunct for SRS treatment planning in brain metastases. Seventeen consecutive patients undergoing complete surgical resection of a solitary brain metastasis underwent image analysis retrospectively. SRS treatment plans were generated based on standard 3D post-contrast T1-weighted sequences at 1.5T and then separately using apparent diffusion coefficient (ADC) maps in a blinded fashion. Control scans immediately post operation confirmed complete tumour resection. Treatment plans were compared to one another and with volume of local recurrence at progression quantitatively and qualitatively by calculating the conformity index (CI), the overlapping volume as a proportion of the total combined volume, where 1 = identical plans and 0 = no conformation whatsoever. Gross tumour volumes (GTVs) using ADC and post-contrast T1-weighted sequences were quantitatively the same (related samples Wilcoxon signed rank test = -0.45, p = 0.653) but showed differing conformations (CI 0.53, p < 0.001). The diffusion treatment volume (DTV) obtained by combining the two target volumes was significantly greater than the treatment volume based on post contrast T1-weighted MRI alone, both quantitatively (median 13.65 vs. 9.52 cm3, related samples Wilcoxon signed rank test p < 0.001) and qualitatively (CI 0.74, p = 0.001). This DTV covered a greater volume of subsequent tumour recurrence than the standard plan (median 3.53 cm3vs. 3.84 cm3, p = 0.002). ADC maps may be a useful tool in addition to the standard post-contrast T1-weighted sequence used for SRS planning.
authors.affiliation: Department of Neurosurgery, The Walton Centre NHS Foundation Trust, Lower Lane, Fazakerley, Liverpool, L9 7LJ, UK. rzakaria@nhs.net.|Institute of Integrative Biology, University of Liverpool, Liverpool, UK. rzakaria@nhs.net.
authors.forename: Rasheed
authors.identifier: 0000-0001-6826-2662
authors.initials: R
authors.lastname: Zakaria
authors.affiliation: Institute of Clinical Radiology, LMU Munich, Munich, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Pomschar
authors.affiliation: Department of Neurosurgery, The Walton Centre NHS Foundation Trust, Lower Lane, Fazakerley, Liverpool, L9 7LJ, UK.|Institute of Translational Medicine, University of Liverpool, Liverpool, UK.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Jenkinson
authors.affiliation: Department of Neurosurgery, LMU Munich, Munich, Germany.
authors.forename: Jörg-Christian
authors.initials: JC
authors.lastname: Tonn
authors.affiliation: Department of Radiation Oncology, LMU Munich, Munich, Germany.|German Cancer Research Centre (DKFZ), Heidelberg, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Belka
authors.affiliation: Institute of Clinical Radiology, LMU Munich, Munich, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Ertl-Wagner
authors.affiliation: Department of Radiation Oncology, LMU Munich, Munich, Germany.|German Cancer Research Centre (DKFZ), Heidelberg, Germany.|German Cancer Consortium (DKTK), Heidelberg, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Niyazi
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000556:secondary; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000556:secondary; D011300:Preoperative Care; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies
keywords: ADC; Brain metastasis; DWI; Planning study; Stereotactic radiosurgery