Perfusion deficits detected by arterial spin-labeling in patients with TIA with negative diffusion and vascular imaging

Abstract

Background and purpose: A substantial portion of clinically diagnosed TIA cases is imaging-negative. The purpose of the current study is to determine if arterial spin-labeling is helpful in detecting perfusion abnormalities in patients presenting clinically with TIA.

Materials and methods: Pseudocontinuous arterial spin-labeling with 3D background-suppressed gradient and spin-echo was acquired on 49 patients suspected of TIA within 24 hours of symptom onset. All patients were free of stroke history and had no lesion-specific findings on general MR, DWI, and MRA sequences. The calculated arterial spin-labeling CBF maps were scored from 1-3 on the basis of presence and severity of perfusion disturbance by 3 independent observers blinded to patient history. An age-matched cohort of 36 patients diagnosed with no cerebrovascular events was evaluated as a control. Interobserver agreement was assessed by use of the Kendall concordance test.

Results: Scoring of perfusion abnormalities on arterial spin-labeling scans of the TIA cohort was highly concordant among the 3 observers (W = 0.812). The sensitivity and specificity of arterial spin-labeling in the diagnosis of perfusion abnormalities in TIA was 55.8% and 90.7%, respectively. In 93.3% (70/75) of the arterial spin-labeling CBF map readings with positive scores (≥2), the brain regions where perfusion abnormalities were identified by 3 observers matched with the neurologic deficits at TIA onset.

Conclusions: In this preliminary study, arterial spin-labeling showed promise in the detection of perfusion abnormalities that correlated with clinically diagnosed TIA in patients with otherwise normal neuroimaging results.

Fig 1.

Representative cases from the control cohort. A, A 50-year-old woman was evaluated for dizziness after an automobile crash. No specific findings are reported on the standard MR, DWI, and MRA tests. ASL reading scores are rated 1, 1, 1 by 3 raters. B, A 49-year old woman was evaluated for a chronic headache of unknown cause. No specific findings are reported on the standard MR, DWI, and MRA tests. ASL reading scores are rated 2, 2, 2 by 3 raters.

Fig 2.

Representative cases from the TIA cohort. A, A 75-year-old woman with a history of hypertension and diabetes had an acute onset of transient blurry vision, slurred speech, dysarthria, and word-finding difficulties that lasted for 20–30 minutes. ABCD² score is 5. The standard MR imaging results demonstrate a few nonspecific T2/FLAIR hyperintensities in the cerebral white matter bilaterally. DWI and MRA study results are normal. ASL CBF map shows perfusion deficits in the right MCA region (arrow). ASL reading scores are rated 2, 2, 2 by 3 raters. B, A 57-year old woman with a history of hypertension had right facial droop and right arm numbness for 6 hours. ABCD² score is 3. Nonspecific T2/FLAIR hyperintensities are seen in the cerebral white matter. DWI and MRA study results are normal. ASL CBF map shows perfusion deficits in the regions of the left MCA and left posterior cerebral artery (arrow). ASL scores are rated 2, 2, 2 by 3 raters. C, A 80-year old woman with a history of hyperlipidemia had transient global amnesia, left-sided sensory deficit, and a positive Babinski sign on the left side for 6 hours. ABCD² score is 3. Scattered T2/FLAIR hyperintensities are seen in the periventricular and subcortical white matter on standard MR imaging. DWI and MRA study results are normal. ASL CBF map shows perfusion deficits in the right MCA region (arrow). ASL scores are rated 3, 3, 3 by 3 raters. D, A 57-year-old woman with a history of hypertension had right facial droop and slurred speech for more than 1 hour. ABCD² score was 4. The standard MR, DWI, and MRA study results are normal. ASL reading scores are rated 1, 1, 1 by 3 raters.