Transient Ischemic Attack: Which Determines Diffusion-Weighted Image Positivity?

Diffusion-weighted image (DWI) of magnetic resonance imaging (MRI) can reveal high signal lesion in up to 50% of transient ischemic attack (TIA) patients. However, it is not well-known which factors determine developing DWI positivity. In order to answer this question, we analyzed factors relevant to DWI positivity in TIA patients.We had 257 stroke patients at a university emergency/neurology wards. They were 140 men, 117 women, mean age 72 (45-88) years. Among them, 24 (9.3%) had TIA (14 men, 10 women, mean age 71 [58-82] years). All patients underwent a 1.5T MRI. In 24 TIA patients, we investigated the following parameters in relation with stroke maturation: ABCD2 score, smoking habits, blood profile, HbA1C, dyslipidemia, coagulation factors, carotid echography, electrocardiography, cardiac echography, chest X-ray, neurological symptom/signs, imaging, and recurrence of neurological symptom on follow-up.In 24 TIA patients, 13 (54%) were DWI positive and 11 (46%) were DWI negative. After an extensive analysis, all parameters were not relevant to DWI positivity except for plasma osmolarity, i.e., plasma osmolarity in DWI positive cases (305.3 mOsm/l) is significantly higher than that in DWI negative cases (301.3 mOsm/l) (P = .0064). As for recurrence, 4 of 24 TIA patients recurred. They were 1 (9.0%) of 11 DWI negative cases and 3 (23.1%) of 13 DWI positive cases. Therefore, DWI positive cases recurred more frequently than DWI negative cases did, although it did not reach statistical significance.TIA with DWI positivity in our institute was 54%, closely associated with initial dehydration and might predict stroke recurrence.