Fig 1.
Flow chart of patients included in the study.
Fig 2.
12 areas of bilateral cerebral and cerebellar hemispheres.
Brain MRI of a 76-year-old woman with dizziness. 12 areas on arterial spin labeling images are shown in figures (a), (b), and (c). Figures (d), (e), and (f) are ASL images and figures (g), (h), and (i) are cerebral blood flow map. Figures (a), (d), and (g) show the most superior portion of the bilateral choroid plexus (regions marked by oblique lines in figure (a)). The image slices above the landmark, the choroid plexus in the trigone, are divided into right and left high frontal (RHF, LHF) and parietal (RP, LP) areas, and the lower image slices are divided into the other eight areas; the low frontal (RLF, LLF), temporal (RT, LT), occipital (RO, LO), and cerebellar (RC, LC) areas on both sides.
Fig 3.
Arterial spin labeling (ASL) rank III perfusion abnormality.
MRI of the brain of a 48-year-old woman with left-side motor weakness. The ASL image (a) shows a rank III perfusion abnormality, as hyperintense vessel signals (arrow) and parenchymal perfusion deficits (open arrow) are present in the right parietal area. However, high signal intensity (arrow) visualized by diffusion-weighted imaging (b = 1,000) (b) is detected only in the right frontal white matter and parietal area. Cerebral blood flow (c) and time to peak maps (d) show a mismatched perfusion defect (arrow) in the right parietal area.
Fig 4.
Arterial spin labeling (ASL) rank II and IV perfusion abnormalities.
MRI of the brain of a 78-year-old woman with a left visual field defect. (a) ASL imaging shows a rank IV perfusion abnormality; positive parenchymal perfusion deficits (PPD) in the right occipital area (arrow); (b) Diffusion weighted imaging (b = 1,000) shows a high signal intensity (arrow); (c) cerebral blood flow (CBF) and (d) time to peak (TTP) maps show matched perfusion defects (arrow) in the same area. (a) A rank II perfusion abnormality is visualized as positive hyperintense vessel signals without PPD (open arrow) using ASL imaging, and a normal (open arrow) is seen in the left occipital area on (c) CBF and (d) TTP maps.
Table 1.
Radiologic evaluation of infarcts in 32 patients.
Fig 5.
Distribution of the 384 areas showing perfusion abnormalities, visualized by arterial spin labeling (ASL) imaging and dynamic susceptibility (DSC) perfusion imaging, in the 32 patients with ischemic stroke (r = 0.82, p- = 0.01 by Spearman’s rank test).
ASL-I refers to no PPD or HVS, II refers to no PPD with the presence of HVS, III refers to the presence of both HVS and PPD, and IV refers to the presence of PPD without HVS.
Table 2.
Numbers of areas showing perfusion abnormalities in 32 patients with ischemic stroke (with percentages of the proportions of each ASL rank and each DSC subtype within parentheses), as determined by ASL imaging and DSC perfusion imaging.
ASL rank I refers to no HVS or PPD, II refers to the presence of HVS without PPD, III refers to the presence of HVS and PPD, and IV refers to the presence of PPD without HVS (r = 0.82, p = 0.01 by Spearman’s rank test).
Fig 6.
Receiver operating characteristic curves of the ranking system for arterial spin labeling (ASL) images, using either matched or mismatched perfusion defects (a) on dynamic susceptibility contrast (DSC) perfusion imaging or matched perfusion defects only (b) as the gold standard. The area under the curve (AUC) value was 0.94, and 0.97, respectively. Numbers within parentheses are 95% confidence interval.
Table 3.
Diagnostic performance of the ASL ranking system, using DSC perfusion imaging as the gold standard.
Table 4.
Kappa values of the trichotomous and dichotomous groups described by ASL ranks and DSC subtypes.