P2‐223: The usefulness of an optimal diffusion‐weighted imaging protocol for lesion detection in transient global amnesia

Abstract

Characteristic punctuate high-signal intensity lesions in the hippocampus on diffusion-weighted imaging (DWI) are typical of transient global amnesia (TGA). The detection rate of these lesions can be improved by up to 85% with optimal magnetic resonance imaging (MRI) parameters and imaging time. Limited evidence suggests that these findings are similar to consecutive patients with TGA in clinical practice. We performed brain MRIs using conventional stroke DWI protocols such as the TGA DWI protocol I and the TGA DWI protocol II by varying resolutions, section thickness and imaging times in consecutive patients with TGA during three periods and retrospectively investigated the medical records and DWI findings in these patients with TGA. The TGA lesion detection rates were analyzed along with the DWI protocols. Clinical and TGA lesion characteristics were also assessed. TGA lesion detection rates were up to 88% with an optimal DWI protocol. Initial DWI at a b-value/section thickness of 2000/3 or 2 mm resulted in the highest first detection rate and the highest lesion detection rate was achieved for DWI with b = 2000 and a section thickness of 3 or 2 mm or b = 3000 and a section thickness of 3 mm at 3 days post onset. Multiple lesions were found within the hippocampus in almost half of the patients but the laterality of the lesion was not significant on DWI. The optimal DWI protocol for detecting lesions in patients with TGA is useful in clinical practice for confirming the diagnosis of TGA patients with clinical findings. Based on these results, an initial DWI with b = 2000 and a section thickness of 3 or 2 mm was essential for detecting TGA lesions. When no lesion was detected by DWI within 24 hours after onset, a follow-up DWI with b = 2000 and a section thickness of 3 or 2 mm was conducted 3 days later.