Manual segmentation for volumetric analyses was performed using the open source software 3D Slicer version 4.2.2.3 (www.slicer.org). 
3D Slicer
Semi-automatic segmentation was done by four independent neurosurgeons and neuroradiologists using the computer-assisted segmentation tool SmartBrush® (referred to as SB), a semi-automatic user-guided and FDA-approved tumor-outlining program that uses contour expansion. 
SmartBrush
Fully automatic segmentations were performed with the Brain Tumor Image Analysis (BraTumIA, referred to as BT) software.  We compared manual (ground truth, referred to as GT), computer-assisted (SB) and fully-automated (BT) segmentations with regard to: (1) products of two maximum diameters for 2D measurements, (2) the Dice coefficient, (3) the positive predictive value, (4) the sensitivity and (5) the volume error.


 BT achieved a mean Dice coefficient of 0.68.  Significant differences were found for intermodal (BT vs. SB) and for intramodal (four SB expert raters) performances.  The BT and SB segmentations of the contrast-enhancing volumes achieved a high correlation with the GT.  Pearson correlation was 0.8 for BT; however, there were a few discrepancies between raters (BT and SB 1 only).  Additional non-enhancing tumor tissue extending the SB volumes was found with BT in 16/19 cases.  The analysis time for the four expert raters was faster (1 minute and 47 seconds to 3 minutes and 39 seconds) than with BT (5 minutes).


 BT and SB provide comparable segmentation results in a clinical setting.  SB provided similar SPD measures to BT and GT, but differed in the volume analysis in one of the four clinical raters.  A major strength of BT may its independence from human interactions, it can thus be employed to handle large datasets and to associate tumor volumes with clinical and/or molecular datasets ("-omics") as well as for clinical analyses of brain tumor compartment volumes as baseline outcome parameters. 
BT