This document summarizes a new computer-aided detection method for intracranial aneurysms that enhances 3D images and highlights potential aneurysms. The method segments arteries from MRI images, determines artery centerlines, and assigns voxels to centerlines. It then colors the anatomical surface from cool to hot based on the change in distance from the centerline, signaling potential aneurysms. An evaluation of 8 subjects found the method detected all 9 true aneurysms with 3.875 false positives per subject on average. The structural information provided by the enhancements could help radiologists better diagnose and plan treatment for aneurysms.

1. Enhanced Image Computer Aided Detection of Intracranial Aneurysms
Karl Diedrich, MS ; John Roberts, PhD ; Dennis Parker, PhD
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University of Utah, Salt Lake City, UT
Introduction Image acquisition, segmentation, and enhancements. Discussion
Traditional aneurysm computer aided Centerline determination The structural information in the three
Image acquisition Artery segmentation
diagnosis (CAD) schemes call potential dimensional image may provide enough
aneurysms by circling the area and the information for radiologists to reject false
radiologists confirm or reject the aneurysm positives and make accurate calls. The
call. Our new artery centerline based method anatomical information in the image is also
enhances the images by coloring the three useful for treatment planning.
dimensional anatomical shaded surface from
cool blue to hot red by increasing aneurysm
likelihood giving finer grained information than
circling potential aneurysms. The system Future work
assists the viewer in diagnosing and Maximum Intensity Projection Projection of arteries Distance from edge (DFE) Centerlines are red in a
•Reducing extra centerlines in round
visualizing aneurysms for treatment planning showing Bright moving arterial segmented by finding cross section. Higher distance from centerline
aneurysms
without forcing the viewer to call or reject an blood in Time of Flight Magnetic smoothest Z-buffer seed and hotter middle values (DFC) image.
aneurysm. Resonance Angiogram. region growing. become centerlines. •Threshold using high DFC over DFE ratio to
remove false positives at artery tips.
•Implement second aneurysm prediction
algorithm using intensity gradients that
enhance round shaped aneurysms.
Materials and Methods •Combine the two aneurysm prediction
•3-D images from Time of Flight MR methods to reduce false positives.
Angiography highlight flowing arterial blood. Assignment •Observer performance study to test the
banding effectiveness of computer enhanced diagnosis
•Segment arteries (tools created in ImageJ)
of intracranial aneurysms.
– Maximum Intensity Projection Z-buffer Cross section of centerline and This image shows the change in DFE
Artery voxels are assigned to the
algorithm identifies artery seed voxels. distance from centerline. Lowest (radius) of the arteries. Black is no
nearest centerline voxel and colored
– Seed intensity histogram method DFC assigns all artery voxels to change, dark blue is a slight change
by DFE to match the centerline.
determines thresholds to grow 3-D centerline voxels. and light blue is more change. Conclusion
segmented arteries from seeds. We developed segmentation, centerline and
•Centerlines are determined using distance Results aneurysm enhancement tools that signal
Subjects Aneurysms Detected Sensitivity False Positives
from edge (DFE) scoring and Dijkstra's aneurysms per subject potential intracranial aneurysms.
shortest paths algorithm finding the lowest 8 9 9 1.0 3.875
cost line through the segmentation. Line length
thresholding removes lines crossing the Unsegmented projections of Segmented change in DFE Thresholding: keep top 8%
arteries leaving the centerlines. aneurysm subjects. colored surface shading. intensity, largest 20% size.
•Voxels are assigned to centerline voxels by Acknowledgements
nearest distance from centerline. •Department of Biomedical Informatics
•The change in the absolute difference • NLM Grant: T15LM007124
between DFE of two centerline points eight
voxels apart is assigned to all voxels •Utah Center for Advanced Imaging Research
belonging to the middle centerline point.
Contact Information
•The DFE change is thresholded by intensity
and size of the signal spot reducing false 2 mm 7 mm
Karl.Diedrich@utah.edu
positives. aneurysm aneurysm
•The images are colored cool blue to hot red
by increasing change in DFE.