Heschl's gyrus - Anatomic description and methods of identification on magnetic resonance imaging

Purpose: To describe the number, anatomic shape, and location of Heschl's gyrus, to evaluate its relation to hemispheric asymmetries, and to define criteria for identifying it with magnetic resonance imaging (MRI).Methods: The MRI scans of 100 hemispheres from 41 volunteers and 9 patients using MPRAGE sequences in vivo were evaluated and correlated with postmortem MRI scans and anatomic specimens of an additional 18 hemispheres from 9 subjects to discern the anatomic relationships of Heschl's gyrus. Of the 9 patients, two had seizures and Heschl's gyrus cavernomas, which served to mark the specific site of Heschl's gyrus in each of the three orthogonal planes.Results: In 66 hemispheres, MRI showed a single Heschl's gyrus, In 33 hemispheres two Heschl's gyri were identified, with no differences between dominant and non-dominant hemispheres. Heschl's gyrus was best identified by: 1) the typical supratemporal omegaor heart-shape of Heschl's gyrus in sagittal sections; 2) the course of Heschl's gyrus on the transverse slice characterized by the adhaesio interthalamica; and 3) the supratemporal omega-shape of Heschl's gyrus on the coronal slice characterized by the tent-like configuration of the crura of the fornices and the VIIIth cranial nerves.Conclusion: The system presented here allows accurate localization of Heschl's gyrus, as demonstrated in two seizure patients with Heschl's gyrus cavernomas, and may therefore serve as a referential method. In contrast to other reports, no hemispheric asymmetry was found in this study.