Risk factors of perfusion and diffusion abnormalities on MRI in hemispheric TIA: a case-control study

Abstract

Background: To assess the prevalence and potential predictors of MR diffusion and perfusion abnormalities in a Chinese population with hemispheric transient ischemic attacks (TIA).

Methods: Patients with temporary (<24 hours) focal cerebral dysfunction of probable vascular origin were considered to be potential candidates for this study in the emergency room. Those who were admitted to the stroke center of Shanghai Fourth People's Hospital affiliated to Tongji University between January 2015 and December 2018 were recruited to the present study. MRI, including both diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI), was performed within 7 days after the last symptom attack. Time to maximum of the residue function (Tmax) maps were auto-evaluated using the RAPID software to determine hypoperfusion. Multivariate analysis was used to assess the correlation of MR findings with clinical variables, medical history, cardio-metabolic characteristics, and the ABCD2 scores (age, blood pressure, clinical features, symptom duration and diabetes).

Results: Sixty-six out of 207 patients met the inclusion criteria. Baseline MRI showed DWI lesions in 20 patients (30.3%). The prevalence of MR perfusion Tmax >4 s >0 mL and ≥10 mL were 77.3% (51/66) and 50% (33/66), respectively. Male patients tended to develop DWI lesions after a TIA. Limb weakness was an independent factor associated with MR perfusion abnormalities (Tmax >4 s ≥10 mL) in this Chinese population (adjusted OR =7.41, 95% CI: 1.57-34.89, P=0.011).

Conclusions: Our results suggest that limb weakness is a strong predictor of perfusion abnormalities calculated by RAPID on Tmax maps of hemispheric TIA patients without DWI positive findings. Male patients are more likely to develop cerebral infarction.

Keywords: Magnetic resonance imaging (MRI); correlation analysis; diffusion-weighted imaging; perfusion weighted imaging; risk factors; transient ischemic attack.

Figure 1

Flowchart of patient recruitment. DWI, diffusion-weighted imaging; TIA, transient ischemic attack; PWI, perfusion weighted imaging.

Figure 2

Diffusion and perfusion abnormalities of two TIA patients. (A,B) A 49-year-old male who presented with aphasia and decreased weakness in the left arm, MR scan was completed 13 days after TIA onset. The DWI lesion (A, arrow, areas of visual hyperintensity) was co-registered with the hypoperfusion area on the time to maximum of residue function (Tmax ≥4 s) map (B, arrow, light blue areas). (C,D) an 83-year-old female who presented with aphasia, MR scan was completed 3 hours after TIA onset. The DWI map (C, arrow, no areas of visual hyperintensity) was normal and the same brain area showed low perfusion on the Tmax ≥4 s map (D, arrow, yellow and blue areas). TIA, transient ischemic attack; DWI, diffusion-weighted imaging.