Morphological Study on Lenticulostriate Arteries in Patients With Middle Cerebral Artery Stenosis at 7 T MRI

Background: Middle cerebral artery (MCA) stenosis affects lenticulostriate arteries (LSAs) that supply the basal ganglia. Increased spatial resolution and signal-to-noise ratio of 7 T could facilitate morphological imaging of very-small-diameter LSAs.

Purpose: To evaluate differences in morphological characteristics of LSA among different MCA stenoses.

Study type: Prospective.

Subjects: We enrolled 161 patients (age: 26-83 years, 115 males) with MCA-M1-segment stenosis, and assigned them to the symptomatic (ischemic stroke on imaging, or transient ischemic attack diagnosed clinically within 90 days) and asymptomatic (mild-to-moderate stenosis, ≤70% diameter reduction and severe stenosis, >70% and ≤99% diameter reductions) groups and further subdivided them into the proximal and distal stenosis subgroups.

Field strength/sequence: 7 T, three-dimensional time-of-flight magnetic resonance angiography (3D TOF-MRA).

Assessment: The number of LSA stems, branches, length, and tortuosity (LSA length/linear distance between LSA start- and endpoints) were evaluated independently in both hemispheres by 3 radiologists with 2-, 10-, and 12-years' experience, and inter-group and inter-subgroup comparisons were undertaken.

Statistical tests: Independent t tests, paired t tests, chi-square test, and multiple linear regression analysis (P < 0.05 indicated statistical significance).

Results: Compared with the asymptomatic group (N = 76), the symptomatic group (N = 85) had significantly fewer LSA branches (7.58 ± 2.31 vs. 9.29 ± 2.37) and shorter length (4.32 ± 0.84 vs. 4.59 ± 0.72 cm). There were no significant intergroup differences in LSA morphological characteristics between the mild-to-moderate and severe-stenosis subgroups (LSA stems: P = 0.457, LSA branches: P = 0.433, LSA length: P = 0.150, and LSA tortuosity: P = 0.613). The proximal stenosis subgroup had significantly fewer (8.08 ± 1.80 vs. 10.64 ± 2.21) and shorter LSA branches (4.43 ± 0.69 vs. 4.76 ± 0.71 cm) than in the distal stenosis subgroup. Multiple linear regression, after false discovery rate correction, showed that symptoms and the MCA-M1-segment-stenosis site (proximal/distal) were significantly associated with LSA and length.

Data conclusion: Having symptoms and a proximal MCA-M1 segment stenosis were associated with fewer LSA branches, whereas stenosis severity did not significantly affect LSA morphological characteristics.

Plain language summary: Lenticulostriate arteries mainly originate from the middle cerebral artery, which 7 T magnetic resonance imaging (MRI) can help visualize effectively. We mainly focused on evaluating lenticulostriate artery stems, branches, length, and tortuosity (length/linear distance between start- and endpoints) among 3 types of middle cerebral artery stenoses (symptomatic and asymptomatic, mild-to-moderate and severe stenosis, and proximal and distal stenosis). Symptomatic patients with proximal MCA stenosis had fewer lenticulostriate artery branches (7.58 ± 2.31 vs. 9.29 ± 2.37 and 8.08 ± 1.80 vs. 10.64 ± 2.21). This research based on the morphological perspective clearly depicted the lenticulostriate artery using 7 T MRI to provide more intuitive results.

Level of evidence: 2 TECHNICAL EFFICACY: Stage 3.