The Leptomeningeal “Ivy Sign” on Fluid-Attenuated Inversion Recovery MR Imaging in Moyamoya Disease: A Sign of Decreased Cerebral Vascular Reserve?

Abstract

BACKGROUND AND PURPOSE:Moyamoya disease is an idiopathic occlusive cerebrovascular disorder with abnormal microvascular proliferation. We investigated the clinical utility of leptomeningeal high signal intensity (ivy sign) sometimes seen on fluid-attenuated inversion recovery images in Moyamoya disease.

Decrease in Leptomeningeal Ivy Sign on Fluid-Attenuated Inversion Recovery Images after Cerebral Revascularization in Patients with Moyamoya Disease

“…3,4,11,14,15 Because secondary collateral pathways are presumed to be recruited once primary collaterals at the circle of Postoperative change in rVR in the bypass-established hemisphere. The increased rVR rate is significantly higher on the bypass-established hemisphere (A ) than that on the contralateral hemisphere (B ) (P ϭ .0018).…”

“…Two recent studies, 1 of which includes the study reported by our group, revealed that the existence of an ivy sign on a FLAIR image in patients with Moyamoya disease is associated with decreased cerebral VR and development of leptomeningeal collaterals. 3,4 In Moyamoya disease, secondary collaterals are well-developed due to failure of primary collaterals. The recruitment of secondary collaterals is required to supply arterial blood to the ischemic area that has impaired cerebral hemodynamics.…”

“…3 This enhancement mechanism is considered to represent a retrograde slow flow of engorged pial vasculature toward an ischemic area via leptomeningeal collaterals. [1][2][3][4] We recently reported that unilateral hemispheric ivy proliferation is highly correlated with an ipsilateral decrease in VR that is associated with the development of leptomeningeal collaterals in patients with Moyamoya disease. 3 In addition, ivy proliferation was found to decrease in 10 of 18 patients (55.6%) who underwent bypass surgery during the follow-up period.…”

Understanding and Augmenting Collateral Blood Flow During Ischemic Stroke

“…While CT, positron emission tomography, MR perfusion and TCD have all been used to assess leptomeningeal collateral blood flow in a variety of different disorders, the most effective single method to visualize leptomeningeal collateral blood flow in humans remains through angiographic assessment (Mori et al, 2009;Derdeyn et al, 1999;Thurley et al, 2009;Wu et al, 2008). However, a combination of multiple imaging modalities is ideal to gain a greater understanding of blood flow in the ischemic cortex (Bang et al, 2008;Wu et al, 2008;Kim et al, 2009).…”

“…For example, Moyamoya disease is a chronic cerebrovascular disorder caused by progressive stenosis or occlusion of the internal carotid artery, leading to headaches, transient ischemic attacks and stroke (Robertson et al, 1997). Due to the longterm occlusive nature of this disease, leptomeningeal arteries become highly developed and have been shown to be a positive indicator of severity of ischemic symptoms (Mori et al, 2009), and are associated with engorged pial networks and slow blood flow (Chung & Park, 2009). Yamauchi et al (2004) investigated the link between the patterns of collateral circulation and the types of infarcts.…”