Double inversion recovery MRI of subcortical band heterotopia and its variations

Background and Purpose: Subcortical band heterotopia (SBH) is a malformation of cortical development diagnosed via MRI. Currently, patients with SBH are classified according to Di Donato's classification. We aimed to show a variation of SBH and the usefulness of double inversion recovery (DIR) images. Methods: We retrospectively reviewed the MRI findings of 28 patients with SBH. The patients were classified according to Donato's classification by using conventional MR images, and their DIR findings were reviewed. Results: Of 28 patients, 20 were grade 1 and 8 were grade 2 according to Di Donato's classification. In 15 of 28 patients, the following four types of atypical MRI findings were detected: asymmetry distribution (four cases), coexistence of thin and thick SBH (five cases), and DIR faint abnormal signal intensity in subcortical white matter (five cases) and in deep white matter (five cases). The latter two types were detected on DIR alone and have not been reported. Additionally, these were identified only in the mild group (Di Donato's classification 1-1 or 1-2). Conclusion: DIR is a useful MRI sequence for detecting faint white matter signal abnormalities, and it can aid in the accurate classification of SBH and identification of its variations, which may reflect the pathology of SBH.