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AJNR - American Journal of Neuroradiology

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American Journal of Neuroradiology 26:76-81, January 2005
© 2005 American Society of Neuroradiology

HEAD AND NECK

Poststenotic Flow and Intracranial Hemodynamics in Patients with Carotid Stenosis: Transoral Carotid Ultrasonography Study

Masahiro Kamouchi^a,c, Kazuhiro Kishikawa^a, Yasushi Okada^a, Tooru Inoue^b, Setsuro Ibayashi^c and Mitsuo Iida^c

^a Department of Cerebrovascular Disease, Cerebrovascular Center and Clinical Research Institute, National Kyushu Medical Center
^b Department of Neurosurgery, Cerebrovascular Center and Clinical Research Institute, National Kyushu Medical Center
^c Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Japan

Address reprint requests to Masahiro Kamouchi, MD, PhD, Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Maidashi 3–1-1, Higashi-ku, Fukuoka 812-8582, Japan

BACKGROUND AND PURPOSE: In severe carotid stenosis, blood supply via the poststenotic internal carotid artery (ICA) and collateral pathways determine cerebral perfusion. We investigated whether poststenotic flow on transoral carotid ultrasonography (TOCU) is predictive of cerebral hemodynamics.

METHODS: Eighty-eight patients with unilateral carotid stenosis underwent TOCU to analyze blood flow velocity and poststenotic diameter of the extracranial ICA. Intracranial collaterals and cerebral hemodynamics were assessed with selective angiography and single photon emission CT.

RESULTS: Poststenotic diameter (P < .0001) and velocities (peak systolic velocity [PSV], time-averaged mean velocity [TMV], end-diastolic velocity [EDV]; all P .009) decreased with stenotic severity. Poststenotic diameter was correlated with PSV (r = 0.36, P = .0005), EDV (r = 0.32, P = .002), and TMV (r = 0.39, P = .0001). Poststenotic flow was significantly lower with collateral pathways than without pathways (P .02) and significantly decreased as the number of the collaterals increased (P < .0001). Flow <5 mL/s indicated collaterals (81% sensitivity, 80% specificity). When flow was <5 mL/s, the asymmetry index in the middle cerebral artery (MCA) territory was significantly low during rest (P = .003) and after acetazolamide challenge (P = .006). Poststenotic flow velocity was associated with baseline (P = .007) and postacetazolamide (P = .0009) MCA asymmetry indexes.

CONCLUSION: Poststenotic ICA flow measured with TOCU reflects collateral flow and cerebral hemodynamics in patients with severe carotid stenosis. This technique may provide new parameters for screening patients with hemodynamically significant carotid stenosis.

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