Article Figures & Data
Figures
- Fig 1.
DSLA sequence scheme. After the section selective/nonselective labeling pulse, multiphase data acquisition started in a cine-like fashion. Any segmentable gradient-echo readout may be used. Figure depicts FLASH readout with threefold segmentation and flow compensation in the section and read directions. ADC indicates analog-to-digital converter; RF, radio frequency; S, section direction gradient.
- Fig 2.
Determination of ATDs. Left, Original signal intensity-time courses measured in the left and right MCAs. Right, Normalized curves (divided by the respective maximum value). By using linear interpolation between the measured points, the intersection at which the signals reached 50% was determined. Difference was referred to as the ATD (arrows).
- Fig 3.
Patient 30, with an 85% stenosis of the left ICA. Dynamic angiograms of the circle of Willis in foot-to-head projections at 60, 100, 140, 220, 300, and 580 ms after labeling in a-f. In a, the right ICA (upper arrow) and basilar artery (lower arrow) fill first. In b, Collateral flow into the left MCA via the left posterior communicating artery and the anterior communicating artery is shown. In d, Left ICA fills. In f, because of the finite length of the labeled bolus, all vessels but the left ICA and MCA contain unlabeled blood at this late phase.
- Fig 4.
ATDs calculated for the CS (left) and MCA (right) increase significantly with the degree of stenosis (P < .01). Values at 60% and 75% stenosis are those of individual patients.
- Fig 5.
ROC curves for ATDs in the CS. Left, Distinction of control subjects and patients with 30–60% stenosis. Right, Distinction of control subjects and patients with <70% stenoses from those with 70–95% stenosis. ATD of >150 ms proved a high-grade stenosis (specificity, 100%; sensitivity, 56%).
- Fig 6.
Scatterplot of the ATDs calculated for the MCA versus those for the CS. Patients were subdivided by the degree of collateral flow visible on DSLA. Degree of collateralization was determined by subjectively assessing flow in the anterior and posterior communicating arteries. Patients with pronounced collateral flow are in the group in whom MCA ATD was less than CS ATD.
- Fig 7.
In a, DSLA difference images of the circle of Willis in patient 40, with a 95% stenosis before and after endarterectomy. In b, Signal intensity-time courses in the CS. After intervention, arrival time on the affected side was the same as on that the unaffected side (about 125 ms). Amplitudes were not calibrated; hence, higher signal intensity was not associated with higher blood flow or blood volume in a vessel.
Tables
Subject ATD (msec) CS MCA 1 30 10 2 10 20 3 20 20 4 10 20 5 30 −20 6 0 40 7 20 30 8 20 30 9 20 30 10 0 0 All* 16 ± 11 19 ± 17 * Data are the mean ± standard deviation.
Patient Degree of Stenosis (%) ATD (msec) CS CS, After Surgery MCA MCA, After Surgery 11 30 40 10 12 30 20 −100 13 30 100 110 14 30 40 10 15 30 30 −30 16 50 40 40 17 50 80 10 30 20 18 50 140 70 19 50 100 80 20 0 20 60 70 50 11–20* 66 ± 39† 21 ± 57‡ 21 70 100 90 22 70 60 60 23 70 160 50 24 75 50 0 25 80 300 160 26 80 120 0 180 20 27 80 350 70 160 30 28 80 50 20 20 40 29 85 140 −40 50 −60 30 85 600 60 320 10 31 85 50 110 32 85 380 § 320 10 33 90 200 100 34 90 90 180 35 90 170 280 36 90 510 800 37 90 350 180 21–37* 216 ± 170† 180 ± 187‡ 38 95 § 70 39 95 § 0 130 4 40 95 220 40 80 20 38–40* 220 93 ± 32 * Data are the mean or the mean ± standard deviation.
† P < .05.
‡ P < .05.
§ No signal.
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