Accelerated Time-of-Flight Magnetic Resonance Angiography with Sparse Undersampling and Iterative Reconstruction for the Evaluation of Intracranial Arteries

OBJECTIVE: To compare the image quality of three-dimensional time-of-flight (TOF) magnetic resonance angiography (MRA) with sparse undersampling and iterative reconstruction (sparse TOF) with that of conventional TOF MRA. MATERIALS AND METHODS: This study included 56 patients who had undergone sparse TOF MRA for intracranial artery evaluation on a 3T MR scanner. Conventional TOF MRA scans were also acquired from 29 patients with matched acquisition times and another 27 patients with matched scanning parameters. The image quality was scored using a five-point scale based on the delineation of arterial vessel segments, artifacts, overall vessel visualization, and overall image quality by two radiologists independently, and the data were analyzed using the non-parametric Wilcoxon signed-rank test. Contrast ratios (CRs) of vessels were compared using the paired t test. Interobserver agreement was calculated using the kappa test. RESULTS: Compared with conventional TOF at the same spatial resolution, sparse TOF with an acceleration factor of 3.5 could reduce acquisition time by 40% and showed comparable image quality. In addition, when compared with conventional TOF with the same acquisition time, sparse TOF with an acceleration factor of 5 could also achieve higher spatial resolution, better delineation of vessel segments, fewer artifacts, higher image quality, and a higher CR (p < 0.05). Good-to-excellent interobserver agreement (κ: 0.65–1.00) was obtained between the two radiologists. CONCLUSION: Compared with conventional TOF, sparse TOF can achieve equivalent image quality in a reduced duration. Furthermore, using the same acquisition time, sparse TOF could improve the delineation of vessels and decrease image artifacts.

LVIS stents for the treatment of small intracranial aneurysms:an efficacy analysis / 中国脑血管病杂志

Objective To investigate the safety and effectiveness of using low-profile visualized intraluminal support (LVIS) stents for the treatment of aneurysms in the small intracranial vessels (diameter <2.5 mm).Methods Between October 2014 and April 2016,the clinical data of all 30 patients with intracranial saccular aneurysm treated with LVIS stents with the small parent arteries <2.5 mm in diameter in Changhai Hospital,the Second Military Medical University were analyzed retrospectively,including 7 ruptured aneurysms and 23 unruptured aneurysms.The anterior circulation aneurysm accounted for 93.3% (n=28),and the diameters of the parent arteries were 1.6-2.4 mm.The complications associated with surgery,angiography,clinical outcomes,and mid-term follow-up data were analyzed.Results The success rate of stent implantation was 100%.Immediate embolization results:Raymond grade Ⅰ in 12 cases (40.0%),Raymond grade Ⅱ in 11 cases (36.7%),and Raymond grade Ⅲ in 7 cases (23.3%).Complications occurred in 2 cases,including one perforating artery occlusion and one intraoperative rupture.Twenty-five patients accepted the angiographic follow-up (Raymond grade Ⅰ in 21 cases,grade Ⅱ in 3 cases,and grade Ⅲ in 1 case).The follow-up time ranged from 4 to 14 months,with an average of 8.1± 2.6 months.One patient had asymptomatic intracranial artery stenosis in the distal end of the stent.No new neurological dysfunction or death occurred.Conclusion The deployment of LVIS stents in small vessels is safe and feasible,the effect of mid-term follow-up is better.However,a larger sample study and long-term follow-up results are needed.