2018 年 12 巻 9 号 p. 469-474
Purpose: We evaluated the efficacy of 3D time-of-flight MRA (3D-TOF MRA) using parameters optimized to reduce metal artifacts in follow-up imaging of cerebral aneurysm treatment by stent-assisted coiling (SAC).
Methods: The radiological data from seven patients (eight aneurysms) who underwent SAC for unruptured cerebral aneurysms were retrospectively analyzed. Standard MRA (normal TOF: N-TOF) and stent-mode TOF (S-TOF) imaging using various parameters, such as the flip angle, were performed to compare the signal intensity of the parent blood vessel and the stent lumen.
Results: Stent lumen vascular signal intensity for S-TOF was significantly higher than N-TOF in patients with stent alone (P = 0.012, <0.05). The mean signal reduction rate for LVIS Jr. (Terumo Corporation, Tokyo, Japan) was 39.0% ± 9.6%. For similar size stents signal reduction ranged from 26.1% to 48.9%. The signal reduction rate for double LVIS coiling was 73.2%. Although the size of the neck remnant was overestimated in some patients, it was possible to detect a slow flow volume at the aneurysm neck in all patients.
Conclusion: 3D-TOF MRA for blood flow assessment facilitated the visual recognition of the stent lumen after SAC. Confirmations of aneurysmal neck remnants were also possible. However, the results suggest that differences in the mesh intervals for similar sized braided stents influenced the signal intensity, leading to overestimation of residual aneurysm. This should be further investigated in future studies.