Multi-slice CT angiography of small cerebral aneurysms: Is the direction of aneurysm important in diagnosis?

Purpose: Multi-slice CT (MSCT) has great potential in evaluation of vascular structures. Our purpose was to investigate if there is any difference in detection of superiorly, inferiorly and horizontally directed small cerebral aneurysms (<5 mm) on MSCTA compared to digital subtraction angiography (DSA) or surgery. Material and methods: One hundred and three consecutive patients who underwent MSCTA and DSA or surgery were included in the study. MSCTA and DSA results were evaluated independently by two different neuroradiologists who performed aneurysm detection, quantitation, and characterization using 2D multiplanar reconstructions, 3D maximum intensity projection and volume-rendered techniques. Findings: MSCTA detected 49 small cerebral aneurysms (<5 mm) in 37 (36%) of 103 patients. The overall sensitivity, specificity, and accuracy of MSCTA for detecting small aneurysms were 0.85, 0.65, and 0.79, respectively. There was moderate agreement between MSCTA and DSA/surgery for detecting small aneurysms (κ: 0.51). The sensitivity of detecting small aneurysms directed superiorly, inferiorly and horizontally was 0.94, 0.84, and 0.75, respectively. There was no statistically significant difference in detection between small aneurysms directed superiorly, inferiorly and horizontally on MSCTA (P > 0.05). Conclusion: The direction of small cerebral aneurysms is not important in diagnosis on multi-slice CT scanners, although the detection of small cerebral aneurysms with superior or inferior direction is slightly easier than the detection of horizontally directed aneurysms.