Triple-Layer Appearance of Brodmann Area 4 at Thin-Section Double Inversion-Recovery MR Imaging

Abstract

PURPOSE: To investigate whether thin-section axial double inversion-recovery (DIR) brain magnetic resonance (MR) imaging at 3.0 T can help distinguish the primary motor cortex (PMC), or Brodmann area 4, from other selected cortical regions, including the primary sensory cortex (PSC), or Brodmann areas 1-3, on the basis of the presence of a "triple-layer" appearance.

MATERIALS AND METHODS: This prospective study was approved by the institutional review board; informed consent was obtained from patients. This study included 191 patients (94 female, age range, 5-80 years; 97 male, age range, 5-76 years) with normal findings at 3.0-T MR imaging. The presence or absence of a triple-layer appearance within selected cortical regions on DIR images was graded independently by two neuroradiologists as definitely present (grade 2), probably present (grade 1), or definitely absent (grade 0). Ten additional patients with tumors underwent DIR imaging and intraoperative cortical mapping for further validation of the PMC. A myelin-stained brain specimen image in a patient not imaged with DIR was correlated with a representative set of DIR images.

RESULTS: A triple-layer appearance was found in the PMC bilaterally in 184 of 191 patients; grade 0 was assigned in only seven patients, who were all younger than 10 years. Grades were significantly lower in patients younger than 10 years than in others (P < .0001) but were not significantly different between older age groups (P > .0018). Interobserver agreement was excellent (weighted kappa = 0.843). The PMC determined on DIR images was confirmed with cortical mapping in all 10 patients with tumors. Triple-layer appearance was not present in the other cortical regions examined, including the PSC (P < .01). The triple-layer appearance on DIR images corresponded to the myelin band within the PMC present on the myelin-stained specimen image.

CONCLUSION: A triple-layer appearance was found in the PMC at thin-section 3.0-T DIR imaging but not in other examined brain regions and therefore might be useful as an adjunct sign for identification of motor regions.

3.0T MRI의 얇은 절편 이중 반전회복(DIR) 영상에서 일차 운동피질이 세 겹의 층 구조로 보이는 특징적 소견을 이용해 운동피질을 다른 피질 영역과 구별할 수 있는지를 검증한 연구입니다. 정상 소견을 보인 다수의 환자에서 두 신경영상의학 전문의가 이 삼중층 소견의 유무를 독립적으로 판정하고, 뇌종양 환자에서는 수술 중 피질 지도화로 실제 운동피질 위치와 대조했으며, 미엘린 염색 표본과도 비교했습니다. 삼중층 소견은 거의 모든 환자의 양측 일차 운동피질에서 관찰된 반면 일차 감각피질 등 다른 영역에서는 나타나지 않았고, 판독자 간 일치도가 높았으며 수술 중 지도화 결과와도 모두 일치했습니다. 다만 10세 미만 어린이에서는 이 소견이 뚜렷하지 않았고, 조직학적으로는 운동피질 내 미엘린 띠에 해당하는 것으로 확인되었습니다. 이 소견은 수술 전 운동 영역을 확인하는 보조 지표로 활용될 수 있습니다.