Role of Perfusion-Weighted Imaging in a Diffusion-Weighted-Imaging-Negative Transient Ischemic Attack.
OBJECTIVE
The absence of acute ischemic lesions in diffusion-weighted imaging (DWI) in transient ischemic attack (TIA) patients makes it difficult to diagnose the true vascular etiologies. Among patients with DWI-negative TIA, we investigated whether the presence of a perfusion-weighted imaging (PWI) abnormality implied a true vascular event by identifying new acute ischemic lesions in follow-up magnetic resonance imaging (MRI) in areas corresponding to the initial PWI abnormality.


METHODS
The included patients underwent DWI and PWI within 72 hours of TIA and also follow-up DWI at 3 days after the initial MRI. These patients had visited the emergency room between July 2009 and May 2015. Patients who demonstrated initial DWI lesions were excluded. The initial PWI abnormalities in the corresponding vascular territory were visually classified into three patterns: no abnormality, focal abnormality, and territorial abnormality.


RESULTS
No DWI lesions were evident in initial MRI in 345 of the 443 TIA patients. Follow-up DWI was applied to 87 of these 345 DWI-negative TIA patients. Initial PWI abnormalities were significantly associated with follow-up DWI abnormalities: 8 of 43 patients with no PWI abnormalities (18.6%) had new ischemic lesions, whereas 13 of 16 patients with focal perfusion abnormalities (81.2%) had new ischemic lesions in the areas of initial PWI abnormalities [odds ratio (OR)=15.1, 95% confidence interval (CI)=3.6-62.9], and 14 of 28 patients with territorial perfusion abnormalities (50%) had new lesions (OR=3.7, 95% CI=1.2-11.5).


CONCLUSIONS
PWI is useful in defining whether or not the transient neurological symptoms in DWI-negative TIA are true vascular events, and will help to improve the understanding of the pathomechanism of TIA.
Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Sang Hun
SH
Lee
Department of Neurology, Dong-A University Hospital, Dong-A University College of Medicine, Busan, Korea.
Hyun Wook
HW
Nah
Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Bum Joon
BJ
Kim
Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Sung Ho
SH
Ahn
Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Jong S
JS
Kim
Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Dong Wha
DW
Kang
Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. sukwon@amc.seoul.kr.
Sun U
SU
Kwon
focal perfusion abnormality; perfusion-weighted imaging; transient ischemic attacks