"They consist of small (1-2 mm) cystic spaces that follow CSF on all sequences. They are located between the dentate gyrus and the cornu ammonis, at the lateral aspect of the hippocampal region, near the apex of the hippocampal fold 4. On 7T MRI, in healthy adults, their volume was variable and ranged from 0.34 mm3 to 23.8 mm3 (mean ± SD = 5.02 ± 4.09 mm3) 6."