6 - Ultrashort TE Time-Spatial Labeling Inversion Pulse MR Angiography for the Assessment of Visceral Artery Aneurysms undergoing Endovascular Intervention

Background: This study investigates the improvement in luminal contrast using non-contrast time-spatial Labeling Inversion Pulse (time-SLIP) MRA using ultrashort TE (UTE) for peri-interventional assessment of visceral artery aneurysms (VAA) undergoing endovascular intervention in comparison to steady-state free precession (SSFP) time-SLIP MRA.

Methods: A total of 22 studies performed in 17 consecutive patients with VAA (10 male; age, 64 ± 12 years) were retrospectively evaluated. Two patients underwent MRA studies before endovascular treatment, five before and after treatment, and 10 underwent only post-treatment studies. Interventions included coil embolization combined with Amplatzer vascular plug placement (n=4) or without (n=9) and nitinol-stentgraft placement (n=2). VAA locations were in splenic (n=10), renal (n=4), hepatic (n=2), and superior mesenteric (n=1) arteries. Both UTE and SSFP time-SLIP MRAs were acquired at each study. In pre-treatment studies, region of interests (ROIs) were placed in the abdominal aorta, the aneurysm, and the parent artery proximal to the aneurysm. In post-treatment studies, ROIs were placed in the aorta and the patent arterial segment adjacent to the metal device or in-stentgraft lumen. Measurements included aneurysmal diameters, signal homogeneity reflected by the coefficient of variation in the native aneurysm (CVan) and contrast ratio of the patent segment to the aorta (CRseg). Measurements between the two MRAs were compared with paired t-tests and Pearson's correlation.

Results: Pre-treatment aneurysmal diameters showed no significant difference (22.1 ± 7.1mm for UTE, 22.4 ± 7.3mm, for SSFP, p=0.40) with an excellent correlation (r >0.99, p< 0.01). UTE showed significantly lower CVan (0.11 ± 0.04 vs. 0.15 ± 0.04, p< 0.01) and higher CRseg (0.81 ± 0.26 vs. 0.6 ± 0.20, p< 0.01) than SSFP. In the 5 patients who had serial studies, decrease in CRseg after treatment was significantly less on UTE than SSFP (p< 0.01)

Conclusion: With the advantage of robustness for susceptibility and turbulent flow, UTE time-SLIP MRA provided better signal homogeneity of the native VAAs as well as the contrast of the patent arterial segments after endovascular treatment than SSFP time-SLIP MRA.