Low-Field Portable MRI Detects Developmental Pattern of Ultraearly Cerebral Infarction in aSAH

BACKGROUND: Aneurysmal subarachnoid hemorrhage (aSAH) is an acute cerebrovascular disease. The concept of ultraearly infarction is gaining recognition. The advent of low-field portable magnetic resonance imaging (LF-pMRI) technology offers a promising new avenue for exploration. We aimed to identify the developmental pattern of ultraearly infarction after aSAH with LF-pMRI. METHODS: This was a prospective, observational, single-center cohort study. Data for patients with consecutive subarachnoid hemorrhage admitted to Beijing Tiantan Hospital from January 1, 2024 to July 31, 2024 were obtained. The inclusion criteria were as follows: (1) diagnosis as subarachnoid hemorrhage, (2) patients who underwent computed tomography, computed tomography angiography, and LF-pMRI in the emergency room before treatment of the aneurysm. Patients with comorbidities, angiographically negative subarachnoid hemorrhage, onset time >72 hours, and Hunt-Hess scale score of 5 were excluded. All enrolled patients underwent LF-pMRI on admission to evaluate the occurrence of ultraearly infarction. Primary outcome was the occurrence of unfavorable functional outcomes (modified Rankin Scale score ≥2). Modified Rankin Scale score was identified by physicians at discharge. Patients who received emergency aneurysm treatment and received complete LF-pMRI process during hospitalization were further evaluated for the risk of delayed cerebral ischemia (DCI), which was the secondary outcome. RESULTS: Among 176 patients with aSAH, 14.20% (25/176) were observed ultraearly cerebral infarction, and 28.41% (50/176) developed DCI. Multivariate analyses showed that ultraearly infarction was an independent risk factor for unfavorable functional outcomes (odds ratio, 3.095 [95% CI, 1.304–7.345]; P =0.010). Subsequently, for the secondary outcome, among 92 patients who received emergency aneurysm treatment and underwent a complete LF-pMRI process, 16.30% (15/92) developed ultraearly cerebral infarction, and 54.35% (50/92) developed DCI. Multivariate analyses showed that for patients with aSAH presenting with DCI, ultraearly infarction (odds ratio, 7.027 [95% CI, 1.485–33.253]; P =0.014), modified Rankin Scale score before admission (odds ratio, 3.737 [95% CI, 1.117–12.508]; P =0.032) were independent risk factors. CONCLUSIONS: LF-pMRI can be utilized to detect the occurrence of ultraearly cerebral infarction in patients with aSAH. Those patients with aSAH who experience ultraearly cerebral infarction have a higher risk of DCI and a greater incidence of unfavorable functional outcomes. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04785976.