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AJNR - American Journal of Neuroradiology

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American Journal of Neuroradiology 25:88-91, January 2004
© 2004 American Society of Neuroradiology

BRAIN

Prominent Laterality of the Posterior Cerebral Artery at Three-Dimensional Time-of-Flight MR Angiography in M1-Segment Middle Cerebral Artery Occlusion

Akihiro Uemura^a, Toshihiro O’uchi^a, Yoichi Kikuchi^a, Naobumi Yashiro^a, Nobumaro Ihara^a and Kazufusa Shoji^a

^a From the Department of Radiology, Kameda Medical Center, Kamogawa, Japan

Address correspondence to Akihiro Uemura, MD, Department of Radiology, St. Luke’s International Hospital, 9–1 Akashi-cho, Tokyo, 104-8560 Japan

BACKGROUND AND PURPOSE: Three-dimensional time-of-flight MR angiography (3D TOF MRA) often discloses prominent posterior cerebral artery (PCA) laterality in the setting of M1-segment middle cerebral artery (MCA) occlusion. We sought to analyze the implications of prominent PCA laterality at 3D TOF MRA.

METHODS: We retrospectively reviewed 3D TOF MRA and digital subtraction angiography (DSA) findings in 25 patients (12 male, 13 female; mean age, 68.8 years [age range, 29–94 years]) with M1-segment occlusion. The observable laterality of the PCA, determined on the basis of 3D TOF MRA findings, was scored according to distal signal extent and compared with findings of collateral flow from the ipsilateral PCA via the leptomeningeal anastomosis (LMA) at DSA. Frequency of PCA laterality at 3D TOF MRA in patients and that in 56 healthy control subjects was also compared.

RESULTS: The positive predictive value of PCA laterality for the existence of collateral flow was 99.9% and the negative predictive value 30.7%. The distal extent of ipsilateral PCA signal at 3D TOF MRA positively correlated with the grade of collateral flow from the PCA via the LMA (r = 0.802; P < .01). PCA laterality was significantly less common in control subjects (P < .01).

CONCLUSION: Prominent PCA laterality at 3D TOF MRA in patients with M1-segment occlusion represents the existence of collateral flow from the PCA via the LMA.