Unilateral Hemispheric Proliferation of Ivy Sign on Fluid-Attenuated Inversion Recovery Images in Moyamoya Disease Correlates Highly with Ipsilateral Hemispheric Decrease of Cerebrovascular Reserve

Case of a 28-year-old man with unsymmetric ivy sign and decreased vascular reserve defined by quantitative SPECT analysis. He had sustained a left TIA. A, FLAIR image showed marked ivy sign in the right hemisphere. B, MRA stages in right and left hemispheres were III and II, respectively. C, Basal brain perfusion SPECT showed mildly decreased CBF in the right hemisphere. D, ACZ stress brain perfusion SPECT showed remarkably decreased CBF in the right hemisphere. E, Quantitative analysis of basal/ACZ stress brain perfusion SPECT. Lower 4 columns show 3D-SSP format view sets of rest CBF, Diamox CBF, vascular reserve, and staging by JFT study from top. Vascular reserve was impaired in most of the right ACA and MCA and in part of the left ACA and MCA territories. The proportions of the stage II area in the right and left hemispheres were 64.9% and 57.9%, respectively. Vascular reserve means in the right and left hemispheres were −9.63 and 2.80, respectively. Vascular reserve less than −30% areas were seen scattered in the right hemisphere. The patient is free from symptoms after cerebral revascularization on the right side.

Quantitative estimation of SPECT in 13 patients with ivy unsymmetric and ivy symmetric distributions. IDH indicates ivy dominant hemisphere; ILDH, ivy less dominant hemisphere. A,B, Proportion of stage II area and mean vascular reserve in IDH and ILDH in patients with an unsymmetric ivy sign (n = 8). A, Proportion of stage II area in IDH and ILDH. Mean proportions of stage II area are 20.71% ± 22.14% in IDH and 13.43% ± 19.91% in ILDH. B, Mean vascular reserve in IDH and ILDH. Mean vascular reserves are 15.06% ± 15.69% in IDH and 23.00% ± 14.59% in ILDH. C,D, Proportion of stage II area and mean vascular reserve in both hemispheres in patients with symmetric ivy sign (n = 5). C, Proportion of stage II area in both hemispheres. Mean proportions of stage II area are 25.64% ± 24.00% in the right hemisphere and 25.64% ± 18.55% in the left hemisphere. D, Mean vascular reserve in both hemispheres. Mean vascular reserves are 12.38% ± 16.69% in the right hemisphere and 15.49% ± 15.77% in the left hemisphere.

A female patient with unsymmetric ivy sign and decreased RI defined by semiquantitative SPECT analysis. She had sustained a right TIA. A, FLAIR image showed marked ivy sign in the left hemisphere. B, Basal brain perfusion SPECT showed decreased CBF in the left hemisphere with an AI of 0.85. C, ACZ stress brain perfusion SPECT showed decreased CBF in the left hemisphere with an AI of 0.73. Semiquantitative analysis of basal/ACZ stress brain perfusion SPECT revealed that rRI decreased in the ivy-dominant hemisphere (RI mean, 0.86). D, Right carotid angiography showed normal filling of vessels in the ACA and MCA regions. E, Left carotid angiography showed delayed filling of vessels in the ACA and MCA regions. A retrograde slow flow of pial vasculature via leptomeningeal collaterals was observed. Regional ACCT in the right and left hemispheres were 3.2 and 5.4 s, respectively (rACCT ratio, 1.69).