Abstract
DWI can detect small punctate hyperintense lesions of the hippocampus in patients with TGA. We investigated whether small TGA lesions can be detected more often by increasing the resolution of DWI. 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/mm(2)): 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. 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). Higher DWI resolution increased lesion detectability in patients with TGA. Considering the small size of TGA lesions, the resolution of DWI is an important parameter influencing lesion detectability.
Highlights
AND PURPOSE: DWI can detect small punctate hyperintense lesions of the hippocampus in patients with TGA
Many recent studies have reported that 1- to 5-mm punctuate high-signal intensity lesions have frequently been found in the lateral portion of the hippocampus, that is, the CA1 region, on DWI in TGA.[6,7,8,9,10,11]
Imaging detection of the lesions in TGA may not change the clinical course of this self-resolving disorder or affect treatment planning, an optimal DWI protocol may help to exclude other possible urgent differential diagnoses that might clinically mimic the symptoms of TGA, such as transient ischemic attack, seizure, drug-induced amnesia, and other causes of altered awareness.[12,13,14,15]
Summary
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. The criteria used to diagnose TGA were as follows: 1) the presence of anterograde amnesia, 2) witnessed by an observer, 3) no clouding of consciousness or loss of personal identity recognition, 4) cognitive impairment limited to amnesia, 5) no focal neurologic or epileptic signs, 6) no recent history of head trauma or seizures, and 7) symptom resolution within 24 hours.[3,19]. Twenty-seven of the 31 patients who underwent DWI twice during their first visit to the hospital, and again 2– 4 days after the onset of symptoms, were included in this study. Informed consent was obtained from the patients or their guardians, and our institutional review board approved the study protocol
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