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Standard DSC-PWI analyses are based on concrete parameters and values, but an approach that contemplates all points in the time-intensity curves and all voxels in the region-of-interest may provide improved information, and more generalizable models. Therefore, a method of DSC-PWI analysis by means of normalized time-intensity curves point-by-point and voxel-by-voxel is constructed, and its feasibility and performance are tested in presurgical discrimination of glioblastoma and metastasis.In this retrospective study, patients with histologically confirmed glioblastoma or solitary-brain-metastases and presurgical-MR with DSC-PWI (August 2007-March 2020) were retrieved. The enhancing tumor and immediate peritumoral region were segmented on CE-T1wi and coregistered to DSC-PWI. Time-intensity curves of the segmentations were normalized to normal-appearing white matter. For each participant, average and all-voxel-matrix of normalized-curves were obtained. The 10 best discriminatory time-points between each type of tumor were selected. Then, an intensity-histogram analysis on each of these 10 time-points allowed the selection of the best discriminatory voxel-percentile for each. Separate classifier models were trained for enhancing tumor and peritumoral region using binary logistic regressions.A total of 428 patients (321 glioblastomas, 107 metastases) fulfilled the inclusion criteria (256 men; mean age, 60 years; range, 20-86 years). Satisfactory results were obtained to segregate glioblastoma and metastases in training and test sets with AUCs 0.71-0.83, independent accuracies 65-79%, and combined accuracies up to 81-88%.This proof-of-concept study presents a different perspective on brain MR DSC-PWI evaluation by the inclusion of all time-points of the curves and all voxels of segmentations to generate robust diagnostic models of special interest in heterogeneous diseases and populations. The method allows satisfactory presurgical segregation of glioblastoma and metastases.• An original approach to brain MR DSC-PWI analysis, based on a point-by-point and voxel-by-voxel assessment of normalized time-intensity curves, is presented. • The method intends to extract optimized information from MR DSC-PWI sequences by impeding the potential loss of information that may represent the standard evaluation of single concrete perfusion parameters (cerebral blood volume, percentage of signal recovery, or peak height) and values (mean, maximum, or minimum). • The presented approach may be of special interest in technically heterogeneous samples, and intrinsically heterogeneous diseases. Its application enables satisfactory presurgical differentiation of GB and metastases, a usual but difficult diagnostic challenge for neuroradiologist with vital implications in patient management.

e13526 Background: Gal-1 is a β-galactoside binding protein that plays an important role in cancer, promoting cell invasion, proliferation, migration, angiogenesis and evasion of the immune response. Gal-1 is involved in glioma progression and is related to tumor grade and poor clinical outcome. Gal-1 has been implicated in resistance to chemotherapy and as a potential mediator of resistance to anti-VEGF therapy. The aim of our study was to evaluate the prognostic significance of Gal-1 in a homogenous cohort of GB patients and to analyze its potential predictive value of response to bevacizumab at recurrence. Methods: A substudy of GLIOCAT, a multicenter study of newly diagnosed GB patients treated with standard Stupp regimen (previously reported). GLIOCAT enrolled 432 patients between 2005-2014. Tissue was available from 243 cases, from which a tissue microarray (TMA) was constructed. Gal-1 expression in tissue from initial surgery was analyzed by immunohistochemistry. Results were evaluated by three reviewers and quantified by H-score. Expression levels were correlated with clinical outcome, known GB prognostic factors and response to bevacizumab. Results: We defined a cut off for Gal-1 H-Score of >60 (cytoplasm) and >25 (nucleus). HighcytoplasmicGal-1 expression significantly correlated with worse OS and with a trend for shorter PFS. In the multivariate analysis KPS, age, MGMT methylation status and, extent of resection but not Gal-1 expression were independent prognostic factors for survival. Of 92 patients who received bevacizumab at recurrence, only 54 were included in the TMA, and only 1 had low Gal-1 expression. We couldn’t find any relationship with OS or PFS in this population. Conclusions: Gal-1 expression may represent a prognostic factor for GB patients treated with standard therapy. [Table: see text]