Human hippocampal subfields in young adults at 7.0 T: feasibility of imaging

To establish an imaging approach to visualize the 100-microm-thick hippocampal neuron-generating dentate granule cell layer (DGCL) consistently within a clinically feasible magnetic resonance (MR) imaging duration and to assess its sensitivity by quantifying the likelihood that it will be detected in healthy young adults.

The study was HIPAA compliant and institutional review board approved. All subjects provided written informed consent. Ten healthy volunteers (five male subjects, five female subjects; mean age, 26 years +/- 6 [standard deviation]) were imaged at 7.0 T by using a 24-element head coil array with three-dimensional T1-weighted MR imaging for anatomic reference, followed by T2*-weighted gradient-echo (echo time, 25 msec; repetition time, 944 msec) imaging at 232-microm in-plane resolution (0.05-mm(3) pixels) in coronal and sagittal slabs (17 sections at 1 mm thick) over the hippocampus in 14 minutes. The entire study took 45 minutes.

The DGCL was consistently visible in all 10 enrolled subjects. All larger subfields were visible in excellent detail and contrast in every subject.

The spatial resolution and tissue contrast at high field strength (7.0 T) MR imaging can be used to consistently reveal hippocampal morphology down to 100-microm subfields within a clinically acceptable imaging duration. This imaging technique might be used to detect cellular disarray and degenerative changes in this sensitive circuit earlier than at 1.5 T or even 3.0 T. (c) RSNA, 2010.