Usefulness of Myelin Quantification Using Synthetic Magnetic Resonance Imaging for Predicting Outcomes in Patients With Acute Ischemic Stroke

Background: Synthetic magnetic resonance imaging (MRI) is an innovative MRI technology that enables the acquisition of multiple quantitative values, including T1 and T2 values, proton density, and myelin volume, in a single scan. Although the usefulness of myelin measurement with synthetic MRI has been reported for assessing several diseases, investigations in patients with stroke have not been reported. We aimed to explore the utility of myelin quantification using synthetic MRI in predicting outcomes in patients with acute ischemic stroke.

Methods: Patients with acute ischemic stroke (n=101) with a premorbid modified Rankin Scale score ≤2 were enrolled. We performed MRI with a 3 T scanner, acquiring synthetic MRI data in addition to data acquired using the routine protocol; we measured total myelin volume (TMV) using synthetic MRI software. After hospitalization, a synthetic MRI was performed when the patient's condition was stable, with a median of 7 days from onset to MRI. We examined the factors related to good stroke outcomes (defined by a modified Rankin Scale score of ≤2 at 3 months).

Results: Patients with larger TMV were younger, were more frequently male, and had higher body mass index. In addition, TMV was associated with the severity of white matter hyperintensities and total small vessel burden scores. The patients with good outcomes (n=66) had larger TMVs than those without (144.85±22.19 versus 126.62±21.81 mL, P<0.001). Multivariable analysis revealed that the TMV quartiles were independently associated with good functional outcomes (odds ratio, 2.54 [95% CI, 1.12-6.70]; P=0.025) after adjusting for baseline clinical characteristics including initial stroke severity, acute brain infarct volume, and brain parenchymal volume.

Conclusions: A large TMV quantified using synthetic MRI was independently associated with good functional outcomes after adjusting for several confounding factors. TMV, which suggests the validity of myelin quantification, might be a useful indicator for predicting stroke outcomes.