Abstract TMP69: Random Rater Sampling For Deep Learning Algorithm To Segment Acute Ischemic Stroke On Non-contrast Computed Tomography

Abstract

Introduction: The delineation of volume and location of acute ischemic brain tissue (AIBT) on Non-Contrast CT (NCCT) increases the efficiency of endovascular treatment decisions. However, the manual segmentation of the AIBT on NCCT is a challenging task and suffers from low inter-expert agreement. Whether supervised deep convolutional neural networks (CNN) are more accurate than expert raters remain to be determined, and the optimal ground truth segmentation of AIBT is unclear given the low inter-expert agreement. We hypothesized that randomly sampling ground truth segmentations of expert raters would enable the CNN to better approximate an accurate ground truth and increase performance. Methods: The data set consisted of 200 NCCT images (Figure 1a)) of acute ischemic stroke patients presenting within 6-16h and consenting to the DEFUSE3 trial. Three experienced neuroradiologists manually segmented the AIBT (Figure 1b)1.-3.). The aggregated validation sets of 5-fold-cross-validation were used to compare the (i) average inter-expert agreement, the average performance of (ii) three individual CNNs trained on each rater and (iii) one CNN trained with random rater sampling. Results: (iii) Random rater sampling (Figure 1c)) lead to a CNN performance superior to (ii) the average performance of individually trained CNNs. The reliability of a CNN goes beyond the human inter-expert agreement (i) (Surface Dice at Tolerance 5mm: 0.88 versus 0.68 and 0.67, respectively; Table 1). Conclusions: The volume and location of AIBT on NCCT can reliably be segmented by a CNN. The agreement between a randomly chosen rater and the CNN predictions surpasses the inter-expert agreement (Table 1).