In vivo MR imaging of hippocampal lesions in multiple sclerosis

Purpose: To investigate whether a recently improved version of the three-dimensional double inversion-recovery (3D-DIR) technique enables the in vivo detection of hippocampal lesions in multiple sclerosis (MS). Materials and Methods: Magnetic resonance images of 16 patients and nine healthy control subjects were acquired at 1.5T. Lesions were scored on 3D-DIR images and were anatomically classified as white matter (WM), cortical, or hippocampal lesions. Associations between hippocampal, cortical, and WM lesion numbers were evaluated. Also, hippocampal lesions were retrospectively assessed on 3D-T2 and hippocampal and brain volumes were measured. Results: No hippocampal lesions were detected in control subjects. By contrast, 14 out of 16 MS patients had at least one hippocampal lesion. The mean number (SD) of hippocampal lesions detected with 3D-DIR was 2.6 +/- 1.8 in MS patients; only 56% of these lesions could be observed on 3D-T2. Conclusion: Hippocampal lesions can be visualized in vivo with 3D-DIR and occur frequently in MS. The ability to visualize hippocampal lesions in vivo is of fundamental importance to future studies focusing on the role of gray matter (GM) damage in cognitive deficits, which are common in MS.