Heschl and superior temporal gyri: low signal intensity of the cortex on T2-weighted MR images of the normal brain.

Abstract

To study the normal signal intensity pattern in the primary auditory cortex (first Heschl gyrus [HG]) and the surrounding cortices in the superior temporal gyrus (STG) and middle temporal gyrus (MTG) on T2-weighted magnetic resonance (MR) images. Coronal T2-weighted fast spin-echo MR images in 30 neurologically normal patients (60 hemispheres) were retrospectively analyzed. Two raters evaluated the cortical signal intensity of the first HG and the neighboring STG and compared them with those of the MTG and the subcortical white matter. The cortical signal intensities between the first HG and the STG were also directly compared. Coronal MR images, which included images of the anterior and posterior halves of the first HG, were evaluated separately. All first HGs were hypointense to the MTG and were either iso- or hypointense to the STG. Cortical hypointensity was especially prominent in the posterior half; the first HG was isointense to the white matter in 33 (55%) hemispheres. The STG was hypointense to the MTG in 54 (90%) hemispheres and in the anterior halves of 36 (60%) hemispheres. These findings demonstrate lower signal intensity of the cortex on T2-weighted images in the first HG and surrounding STG compared with that of the MTG.