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The Possible Difference of Underlying Pathophysiologies between “Ivy Sign” on Contrast-Enhanced MRI and FLAIR

The Possible Difference of Underlying Pathophysiologies between “Ivy Sign” on Contrast-Enhanced... LETTERS ThePossibleDifferenceof UnderlyingPathophysiologies between “Ivy Sign” on Contrast-Enhanced MRI and FLAIR e read with interest the article by Wang et al titled “Ivy FLAIR in the operativesidewith an increase in cerebrovascular WSign in Moyamoya Disease: A Comparative Study of the reserve on SPECT supports the current hypothesis. FLAIR Vascular Hyperintensity Sign Against Contrast-Enhanced Second, they showed that the ivy sign score on contrast- MR Imaging.” Theresults of thestudy carried outby Wang et al enhanced MR imaging was negatively correlated with CBF in the are agreeable, which show that the ivy sign score on contrast- MCA regioninthe late Suzuki stage. Their speculation was that it enhanced MR imaging was statistically significantly correlated with was because of the imbalance between leptomeningeal collaterals the amount of leptomeningeal collateral from the posterior cerebral and abnormal ICA and Moyamoya vessels; however, posterior cir- culation (posterior cerebral artery stenosis or occlusion) was often artery on digital subtraction angiography, while the ivy sign score on involved in this phase, and various amounts of leptomeningeal col- FLAIR was not. A previous report also speculated that the ivy sign laterals may be present on a case-by-case basis. Therefore, the ivy score on contrast-enhanced MR imaging may correspond to angio- sign on contrast-enhanced MR imaging in the late Suzuki stage graphic cortical microvascularization via leptomeningeal collaterals. may be attributable to maximally dilated pial vasculature, as well as Although the authors did not clearly mention it, their results leptomeningeal collaterals. Further study with the ivy sign distribu- revealed different underlying pathophysiologies between the ivy sign tion and cerebrovascular reserve assessment will be needed to con- on contrast-enhanced MR imaging and FLAIR. Moreover, the ivy firm the different underlying pathophysiologies between the ivy sign on contrast-enhanced MR imaging may not be an alternative to sign on contrast-enhanced MR imaging and FLAIR. that on FLAIR, based on the following opinions derived from their results. First, the ivy sign score on contrast-enhanced MR imaging before surgery was significantly correlated with the postoperative re- REFERENCES vascularization grade. The study speculated that the more leptome- 1. Wang LX,Wang H,Hao FB,et al. Ivy sign in Moyamoya disease: a ningeal collaterals present before surgery, the better the outcome of comparative study of the FLAIR vascular hyperintensity sign against the revascularization operation would be. The ivy sign on contrast- contrast-enhanced MRI. AJNR Am J Neuroradiol 2021;42:694–700 CrossRef Medline enhanced MR imaging may be angiographic cortical microvasculari- 2. Mugikura S, Fujimura M, Takahashi S. Cortical microvascularization zation via leptomeningeal collaterals. However, the ivy sign on and leptomeningeal collaterals in Moyamoya disease. Eur Neurol FLAIR before surgery was not significantly correlated with the post- 2015;73:351–52 CrossRef Medline operative revascularization grade. This result indicates that the ivy 3. Mori N, Mugikura S, Higano S, et al. The leptomeningeal “Ivy Sign” sign on FLAIR may not reflect leptomeningeal collaterals, but the on fluid-attenuated inversion recovery MR imaging in Moyamoya disease: a sign of decreased cerebral vascular reserve? AJNR Am J slow flow of maximally dilated pial vasculature (microscopic cortical Neuroradiol 2009;30:930–35 CrossRefMedline microvascularization) compensates for the decreased perfusion. 4. Kawashima M, Noguchi T, Takase Y, et al. Decrease in leptomenin- Theivy sign may beobserved in the posterior MCA region on geal ivy sign on fluid-attenuated inversion recovery images after FLAIR if the ivy sign on FLAIR reflects leptomeningeal collaterals cerebral revascularization in patients with Moyamoya disease. AJNR from the posterior cerebral artery similar to the ivy sign on con- Am J Neuroradiol 2010;31:1713–18 CrossRef Medline trast-enhanced MR imaging. However, it was more frequently N. Mori Department of Diagnostic Radiology observed in the anterior MCA region than in the posterior MCA Tohoku University Graduate School of Medicine region on FLAIR in our previous study. Did the distribution of Sendai, Japan ivy signs in the study population of Wang et al differ between con- trast-enhanced MR imaging and FLAIR? The ivy sign on FLAIR S. Mugikura Department of Diagnostic Radiology was significantly correlated with the cerebrovascular reserve on Tohoku University Graduate School of Medicine SPECT, suggesting that it may reflect the slow flow of maximally Sendai, Japan dilated pial vasculature. The postoperative decrease in ivy signs on Department of Image Statistics Tohoku Medical Megabank Organization, Tohoku University http://dx.doi.org/10.3174/ajnr.A7176 Sendai, Japan AJNR Am J Neuroradiol 42:E69 Sep 2021 www.ajnr.org E69 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png American Journal of Neuroradiology American Journal of Neuroradiology

The Possible Difference of Underlying Pathophysiologies between “Ivy Sign” on Contrast-Enhanced MRI and FLAIR

American Journal of Neuroradiology , Volume 42 (9) – Sep 1, 2021

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Publisher
American Journal of Neuroradiology
Copyright
© 2021 by American Journal of Neuroradiology
ISSN
0195-6108
eISSN
1936-959X
DOI
10.3174/ajnr.A7176
Publisher site
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Abstract

LETTERS ThePossibleDifferenceof UnderlyingPathophysiologies between “Ivy Sign” on Contrast-Enhanced MRI and FLAIR e read with interest the article by Wang et al titled “Ivy FLAIR in the operativesidewith an increase in cerebrovascular WSign in Moyamoya Disease: A Comparative Study of the reserve on SPECT supports the current hypothesis. FLAIR Vascular Hyperintensity Sign Against Contrast-Enhanced Second, they showed that the ivy sign score on contrast- MR Imaging.” Theresults of thestudy carried outby Wang et al enhanced MR imaging was negatively correlated with CBF in the are agreeable, which show that the ivy sign score on contrast- MCA regioninthe late Suzuki stage. Their speculation was that it enhanced MR imaging was statistically significantly correlated with was because of the imbalance between leptomeningeal collaterals the amount of leptomeningeal collateral from the posterior cerebral and abnormal ICA and Moyamoya vessels; however, posterior cir- culation (posterior cerebral artery stenosis or occlusion) was often artery on digital subtraction angiography, while the ivy sign score on involved in this phase, and various amounts of leptomeningeal col- FLAIR was not. A previous report also speculated that the ivy sign laterals may be present on a case-by-case basis. Therefore, the ivy score on contrast-enhanced MR imaging may correspond to angio- sign on contrast-enhanced MR imaging in the late Suzuki stage graphic cortical microvascularization via leptomeningeal collaterals. may be attributable to maximally dilated pial vasculature, as well as Although the authors did not clearly mention it, their results leptomeningeal collaterals. Further study with the ivy sign distribu- revealed different underlying pathophysiologies between the ivy sign tion and cerebrovascular reserve assessment will be needed to con- on contrast-enhanced MR imaging and FLAIR. Moreover, the ivy firm the different underlying pathophysiologies between the ivy sign on contrast-enhanced MR imaging may not be an alternative to sign on contrast-enhanced MR imaging and FLAIR. that on FLAIR, based on the following opinions derived from their results. First, the ivy sign score on contrast-enhanced MR imaging before surgery was significantly correlated with the postoperative re- REFERENCES vascularization grade. The study speculated that the more leptome- 1. Wang LX,Wang H,Hao FB,et al. Ivy sign in Moyamoya disease: a ningeal collaterals present before surgery, the better the outcome of comparative study of the FLAIR vascular hyperintensity sign against the revascularization operation would be. The ivy sign on contrast- contrast-enhanced MRI. AJNR Am J Neuroradiol 2021;42:694–700 CrossRef Medline enhanced MR imaging may be angiographic cortical microvasculari- 2. Mugikura S, Fujimura M, Takahashi S. Cortical microvascularization zation via leptomeningeal collaterals. However, the ivy sign on and leptomeningeal collaterals in Moyamoya disease. Eur Neurol FLAIR before surgery was not significantly correlated with the post- 2015;73:351–52 CrossRef Medline operative revascularization grade. This result indicates that the ivy 3. Mori N, Mugikura S, Higano S, et al. The leptomeningeal “Ivy Sign” sign on FLAIR may not reflect leptomeningeal collaterals, but the on fluid-attenuated inversion recovery MR imaging in Moyamoya disease: a sign of decreased cerebral vascular reserve? AJNR Am J slow flow of maximally dilated pial vasculature (microscopic cortical Neuroradiol 2009;30:930–35 CrossRefMedline microvascularization) compensates for the decreased perfusion. 4. Kawashima M, Noguchi T, Takase Y, et al. Decrease in leptomenin- Theivy sign may beobserved in the posterior MCA region on geal ivy sign on fluid-attenuated inversion recovery images after FLAIR if the ivy sign on FLAIR reflects leptomeningeal collaterals cerebral revascularization in patients with Moyamoya disease. AJNR from the posterior cerebral artery similar to the ivy sign on con- Am J Neuroradiol 2010;31:1713–18 CrossRef Medline trast-enhanced MR imaging. However, it was more frequently N. Mori Department of Diagnostic Radiology observed in the anterior MCA region than in the posterior MCA Tohoku University Graduate School of Medicine region on FLAIR in our previous study. Did the distribution of Sendai, Japan ivy signs in the study population of Wang et al differ between con- trast-enhanced MR imaging and FLAIR? The ivy sign on FLAIR S. Mugikura Department of Diagnostic Radiology was significantly correlated with the cerebrovascular reserve on Tohoku University Graduate School of Medicine SPECT, suggesting that it may reflect the slow flow of maximally Sendai, Japan dilated pial vasculature. The postoperative decrease in ivy signs on Department of Image Statistics Tohoku Medical Megabank Organization, Tohoku University http://dx.doi.org/10.3174/ajnr.A7176 Sendai, Japan AJNR Am J Neuroradiol 42:E69 Sep 2021 www.ajnr.org E69

Journal

American Journal of NeuroradiologyAmerican Journal of Neuroradiology

Published: Sep 1, 2021

References