  Intracranial aneurysms (IAs) are generally asymptomatic and thus often
discovered incidentally on angiographic scans like 3D DSA, CTA and MRA. Skilled
radiologists achieved a sensitivity of 88% by means of visual detection, which
seems inadequate considering that prevalence of IAs in general population is
3-5%. Deep learning models trained and executed on angiographic scans seem
best-suited for IA detection, however, reported performances across different
modalities is currently insufficient for clinical application. This paper
presents a novel modality agnostic method for detection of IAs. First the
triangulated surfaces of vascular structures were roughly extracted from the
angiograms. For IA detection purpose, the extracted surfaces were randomly
parcellated into local patches and then a translation, rotation and scale
invariant classifier based on deep neural network (DNN) was trained. Test stage
proceeded by mimicking the surface extraction and parcellation at several
random locations, then the trained DNN model was applied for classification,
and the results aggregated into IA detection heatmaps across entire vascular
surface. For training and validation the extracted contours were presented to
skilled neurosurgeon, who marked the locations of IAs. The DNN was trained and
tested using three-fold cross-validation based on 57 DSAs, 5 CTAs and 5 MRAs
and showed a 98.6% sensitivity at 0.2 false positive detections per image.
Experimental results show that proposed approach not only significantly
improved detection sensitivity and specificity compared to state-of-the-art
intensity based methods, but is also modality agnostic and thus better suited
for clinical application.
