Feasibility of Quantification of Intracranial Aneurysm Pulsation with 4D CTA with Manual and Computer-Aided Post-Processing

<div><p>Background and Purpose</p><p>The analysis of the pulsation of unruptured intracranial aneurysms might improve the assessment of their stability and risk of rupture. Pulsations can easily be concealed due to the small movements of the aneurysm wall, making post-processing highly demanding. We hypothesized that the quantification of aneurysm pulsation is technically feasible and can be improved by computer-aided post-processing.</p><p>Materials and Methods</p><p>Images of 14 cerebral aneurysms were acquired with an ECG-triggered 4D CTA. Aneurysms were post-processed manually and computer-aided on a 3D model. Volume curves and random noise-curves were compared with the arterial pulse wave and volume curves were compared between both post-processing modalities.</p><p>Results</p><p>The aneurysm volume curves showed higher similarity with the pulse wave than the random curves (Hausdorff-distances 0.12 vs 0.25, p<0.01). Both post-processing methods did not differ in intra- (r = 0.45 vs r = 0.54, p>0.05) and inter-observer (r = 0.45 vs r = 0.54, p>0.05) reliability. Time needed for segmentation was significantly reduced in the computer-aided group (3.9 ± 1.8 min vs 20.8 ± 7.8 min, p<0.01).</p><p>Conclusion</p><p>Our results show pulsatile changes in a subset of the studied aneurysms with the final prove of underlying volume changes remaining unsettled. Semi-automatic post-processing significantly reduces post-processing time but cannot yet replace manual segmentation.</p></div

Results of the intraobserver (mean±LOA -0.02 ± 0.11 vs. 0.01 ± 0.11, upper row) and interobserver agreements (mean±LOA 0.007 ± 0.11 vs. -0.01 ± 0.12 lower row) for the 2D post-processing (right) and 3D+t post-processing (left).

<p>Results of the intraobserver (mean±LOA -0.02 ± 0.11 vs. 0.01 ± 0.11, upper row) and interobserver agreements (mean±LOA 0.007 ± 0.11 vs. -0.01 ± 0.12 lower row) for the 2D post-processing (right) and 3D+t post-processing (left).</p

Volumetric analyses.

<p>Volumetric analyses.</p

Flow rates of the stented internal carotid artery (solid line) and contralateral internal carotid artery (dotted line).

<p>Horizontal bars and boxes represent mean and mean +/- standard deviation, respectively. Compared to preoperative values, the flow rates of the stented internal carotid artery after carotid artery stenting (CAS) are significantly larger. Compared to preoperative values, the flow rate of the contralateral carotid artery at 3 months after CAS is significantly smaller.</p

Sum of flow rates of the bilateral internal carotid arteries (ICAs) and the basilar artery.

<p>The sum increases after CAS, then decreases over the next 3 months.</p

Relative volume changes of all 14 aneurysms with manual segmentation.

<p>Aneurysms 1, 2, 5, and 8 show a pulsation-like profile. Plot number 15 shows the cumulative pulsation of all aneurysms.</p

Twin intra-pair analyses.

<p>Twin intra-pair analyses.</p

Boxplots of Hausdorff distances between the volume curves and random curves and the pulse wave on the right and left-hand side (0.12 vs 0.25, p<0.01).

<p>Boxplots of Hausdorff distances between the volume curves and random curves and the pulse wave on the right and left-hand side (0.12 vs 0.25, p<0.01).</p

Subjects' demographic data.

<p>Subjects' demographic data.</p

Path diagram representing the structural equation model used to calculate A (additive genetics) and E (unique environmental) factors.

<p>Path diagram representing the structural equation model used to calculate A (additive genetics) and E (unique environmental) factors.</p