High-Resolution Diffusion-Weighted Imaging Increases Lesion Detectability in Patients with Transient Global Amnesia

BACKGROUND AND PURPOSE: DWI can detect small punctate hyperintense lesions of the hippo-campus in patients with TGA. We investigated whether small TGA lesions can be detected more often by increasing the resolution of DWI. MATERIALS AND METHODS: Of 31 consecutive patients with TGA, 27 underwent DWI, twice at the first visit (range 1.5–22 hours; mean 10 hours) and at follow-up (range 50–87 hours; mean 72.5 hours) after the onset of their symptoms. Each DWI included 2 different spatial resolutions with the same b-value (2000 seconds/mm2): conventional resolution in a 128 128 matrix with 3-mm section thickness and high resolution in a 220 220 matrix with 2-mm section thickness. The number and contrast of hyperintense lesions were compared between the 2 resolutions. RESULTS: Twenty-two of the 27 patients had single or multiple TGA lesions. The total number of lesions detected on conventional and high-resolution DWI was 11 and 22, respectively, at the first visit, and was 24 and 37, respectively, at follow-up. The number of lesions was significantly larger on high-resolution DWI than on conventional resolution at the first visit (P .01) and at the follow-up (P .01). Lesion contrast was significantly increased on high-resolution DWI (P .01). CONCLUSIONS: Higher DWI resolution increased lesion detectability in patients with TGA. Considering th