High-Resolution 7T MRI of the Human Hippocampus In Vivo

Purpose: To describe an initial experience imaging the human hippocampus in vivo using a 7T magnetic resonance (MR) scanner and a protocol developed for very high field neuroimaging. Materials and Methods: Six normal subjects were scanned on a 7T whole body MR scanner equipped with a 16-channel head coil. Sequences included a full field of view T1-weighted 3D turbo field echo (T1W 3D TFE: time of acquisition (TA) = 08:58), T2*-weighted 2D fast field echo (T2*W 2D FFE: TA = 05:20). and susceptibility-weighted imaging (SWI: TA = 04:20). SWI data were postprocessed using a minimum intensity projection (minIP) algorithm. Total imaging time was 23 minutes. Results: T1W 3D TFE images with 700 mu m isotropic voxels provided excellent anatomic depiction of macroscopic hippocampal structures. T2*W 2D FFE images with 0.5 mm in-plane resolution and 2.5 mm slice thickness provided clear discrimination of the Cornu Ammonis and the compilation of adjacent sublayers of the hippocampus. SWI images (0.5 mm in-plane resolution, 1.0 mm slice thickness) delineated microvenous anatomy of the hippocampus. Conclusion: In vivo 7T MR imaging can take advantage of higher signal-to-noise and novel contrast mechanisms to provide increased conspicuity of hippocampal anatomy.