Abstract TP86: Clinical Significance of Gadolinium Enhancement in Non-Hemorrhagic Intracranial Artery Dissection

Background and Purpose: The mechanisms involved in progression of non-hemorrhagic intracranial artery dissection (IAD) are poorly understood. Contrast enhancement of intracranial saccular aneurysms on magnetic resonance vessel wall imaging (VWI) is thought to predict instability. We investigated the relationship between contrast enhancement of dissecting lesions and progression of IADs based on the hypothesis that this finding might predict instability. Methods: A total of 39 IADs in 36 patients (17 women and 19 men; mean age: 49 years) were investigated retrospectively. Three-dimensional T1-weighted fast spin-echo sequences were obtained before and after injection of contrast medium, and the vessel wall/pituitary stalk contrast enhancement ratio (CRstalk) was calculated. Progression of IADs was defined as morphological deterioration; progressive dilatation or stenosis. The relations between IAD progression and potential risk factors, including patient demographic data, IAD morphology, and VWI findings, were investigated by statistical analysis. Results: The mean follow-up period was 9.7 months (range: 1-24 months). Progression was detected in 6 of 39 IADs (15%). Five IADs demonstrated aneurysmal dilatation and the other showed stenosis/occlusion. There were no significant differences of demographic factors between the patients with or without IADs progression. IADs with aneurysmal dilation demonstrated significant morphological deterioration (p=0.01). All IADs without contrast enhancement (n=7) improved within one month. Contrast enhancement corresponded to the pseudo-lumen of dissecting lesions. The CRstalk value was significantly higher in IADs with progression than in stable lesions (1.10 ± 0.09 vs. 0.80 ± 0.05, p =0.01). Conclusions: The pseudo-lumen of dissecting lesions may be identified by contrast enhancement. Quantitative analysis of contrast enhancement could be useful for predicting instability of IADs during follow-up.