Article Figures & Data
Figures
- Fig 1.
Examples and prevalence of circle of Willis anomalies that hamper collateral function. Prevalence is derived from studies by using an external diameter of 1 mm as a threshold for hypoplasia of collateral arteries. A1 indicates the precommunicating part of the anterior cerebral artery; M1, main trunk of the middle cerebral artery; P1, precommunicating part of the posterior cerebral artery; BA, basilar artery; and VA, vertebral artery.
- Fig 2.
TCCD sonogram of the circle of Willis in the left temporal window and axial scanning plane at the level of the mesencephalon. The ipsilateral (left) M1, P1 (red), and A1 (blue) are shown. The contralateral (right) M1 and P1 (blue) and A1 (red) are also shown.
- Fig 3.
Doppler spectra.
A, Spectrum shows blood flow reversal in the A1 during ipsilateral carotid compression indicating functional patency of the AcoA.
B, Spectrum shows blood flow velocity increase of more than 20% in the P1 during ipsilateral carotid compression indicating functional patency of the PcoA.
- Fig 4.
3D TOF MR angiograms.
A, Angiogram of the circle of Willis with the complete anterior configuration shows the AcoA (arrow).
B, Angiogram of the circle of Willis with the complete posterior configuration shows the right and left PcoAs (arrows)
Tables
- TABLE 1:
MR angiography compared with conventional angiography for the detection of intracranial collaterals
Author* No. of Subjects AcoA PcoA Sensitivity, % Specificity, % Sensitivity, % Specificity, % Patrux et al (4) 54 89 100 81 100 Stock et al (5) 62 67 73 75 93 * Numbers in parentheses are reference citations.
Number of findings Detection with MR Angiography* Detection with TCCD* Total Yes No Observer 1 Yes 105 5 110 No 18 22 40 Total 123 27 150 Observer 2 Yes 107 9 116 No 16 18 34 Total 123 27 150 Diagnostic discrimination Measure Observer 1† Observer 2† Sensitivity, % 85 (79, 92) 87 (81, 93) Specificity, % 81 (62, 94) 67 (46, 84) Positive predictive value, % 95 (90, 99) 92 (86, 96) Negative predictive value, % 55 (39, 71) 53 (35, 70) * Yes indicates functional. No indicates nonfunctional.
† Numbers in parentheses are the 95% confidence intervals.
- TABLE 4:
Percentage of nonvisualized collaterals in 3D time-of-flight MR angiography studies
Study* No. of Subjects Age, y AcoA, % A1, % PcoA, % P1, % Healthy volunteers Krabbe-Hartkamp et al (3) 150 55 19 3 28 2 Current study† 50 51 10 1 22 7 Cerebrovascular patients Patrux et al (4) 54 44 54 5 56 8 Stock et al (5) 62 52 40 4 39 4 Hartkamp et al (23) 75 62 7 3 21 2 Brunereau et al (24) 109 21–82 45 2 44 12 * Numbers in parentheses are reference citations.
† Data were derived from the consensus review.
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