Quantitative Cerebrovascular Reserve Measured by Acetazolamide-Challenged Dynamic CT Perfusion in Ischemic Adult Moyamoya Disease: Initial Experience with Angiographic Correlation

K.H. Kang; H.S. Kim; S.Y. Kim

doi:10.3174/ajnr.A1129

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Fig 1.
ROIs drawn in a reference CT image (A) and vessel-removed MTT map (B). The ROIs were placed on cortical regions in the MCA territory, EBZ, ACA territory, and putamen in the section of BG level around the foramen of Monro.
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Fig 2.
A 48-year-old woman with transient ischemic attack (case 16). A, Anteroposterior view of right internal carotid arteriogram shows severe stenosis in the proximal M1 portion of MCA with developed BMVs (modified Suzuki stage II). B, Anteroposterior view of left internal carotid arteriogram shows occlusion of distal ICA without antegrade flow (modified Suzuki stage IV). CBF maps before (C) and after (D) ACZ administration show decreased CVR in the left anterior EBZ (white arrow) and MCA territory (black arrow) ipsilateral to the hemisphere with higher modified Suzuki stage compared with contralateral hemisphere with lower modified Suzuki stage. Corresponding SPECT before (E) and after (F) ACZ administration show decreased CVR in the same areas.
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Fig 3.
Scatterplot between baseline MTT and PCs of CBF and angiographic stages in the anterior EBZ. A, Angiographic stage versus MTT in the EBZ. B, Angiographic stage versus PC of CBF in the EBZ.
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Fig 4.
Clustered box-and-whisker graphs show the differences in the mean values of hemodynamic parameters according to the presence of BMVs in each vascular territory. A, BMV versus normalized CBV. B, BMV versus normalized CBF. C, BMV versus normalized MTT. D, BMV versus PC of CBF.

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Table 1:

Clinical data of 16 adult patients with ischemic Moyamoya diseases

Patient No.	Age/Sex	Clinical Symptoms	Duration of TIA	Bypass Surgery
1	39/F	TIA	12 months	EIAB
2	44/M	Headache, TIA	7 months	Negative^*
3	33/F	Headache, TIA	8 months	Negative^*
4	64/F	Headache, TIA	4 months	Negative^*
5	66/F	Headache, TIA	2 months	EIAB
6	32/M	Headache, TIA	24 months	Negative^*
7	36/M	TIA	24 months	Negative^*
8	45/F	TIA	1 month	Negative^*
9	42/F	TIA	7 months	Negative^*
10	39/F	TIA	36 months	Negative^*
11	56/F	Headache, TIA	1 month	Negative^*
12	31/F	TIA	24 months	EIAB
13	35/F	Headache, TIA	12 months	Negative^*
14	37/M	TIA	8 months	EIAB
15	42/M	TIA	11 months	Negative^*
16	48/F	TIA	1 month	Negative^*

Note:—TIA indicates transient ischemic attack; EIAB, external internal arterial bypass; F, female; M, male.
* Negative indicates a patient who did not have vascular bypass surgery.

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Table 2:

Modified Suzuki angiographic stages

Stages	Angiographic Findings
I	Mild-to-moderate stenosis around carotid bifurcation with absent or slightly developed ICA Moyamoya:^* almost all of both ACA and MCA branches are opacified in antegrade fashion
II	Severe stenosis around carotid bifurcation or occlusion of either of proximal ACA or MCA with well-developed ICA Moyamoya:^* either ACA or MCA branches or both are clearly defective, but at least several of ACA or MCA branches remain opacified in antegrade fashion
III	Occlusion of both proximal ACA and MCA with well-developed ICA Moyamoya:^* only a few of either ACA or MCA branches or both are faintly opacified in antegrade fashion through the meshwork of ICA Moyamoya
IV	Complete occlusion of both proximal ACA and MCA with absent or small amount of ICA Moyamoya:^* without opacification of either ACA or MCA branches in antegrade fashion

Note:—Data were modified from the staging system proposed by Suzuki and Takaku.¹ When the proximal ACA was hypoplastic, stage was determined by evaluating the proximal MCA involvement, opacification of MCA branches, and degree of development of ICA Moyamoya. ICA indicates internal carotid artery; ACA, anterior cerebral artery; MCA, middle cerebral artery.
* ICA Moyamoya indicates Moyamoya vessels at or around the terminal part of the ICA.

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Table 3:

The stages of basal Moyamoya vessels

Stages	Angiographic Findings
I	No Moyamoya vessels were seen
II	Moyamoya vessels were localized in the area around the ICA bifurcation, and each vessel was fine and had little contrast
III	Moyamoya vessels had intermediate extension and thickness
IV	Moyamoya vessels extended a great deal, and each one was thick and strongly opacified

Note:—ICA indicates internal carotid artery.

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Table 4:

Correlation coefficient between normalized baseline- and ACZ-challenged CT perfusion parameters and angiographic stages in each vascular territory

Variable	BG^*	ACA^*	MCA^*	EBZ^*
Observer 1
CBV vs AS	0.39^†	0.29	0.29	0.69^†
CBF vs AS	−0.16	−0.24	−0.50^†	−0.33
MTT vs AS	0.47^†	0.39^†	0.52^†	0.68^†
PC of CBV vs AS	−0.36	0.11	−0.29	−0.19
PC of CBF vs AS	−0.65^†	−0.40^†	−0.81^†	−0.82^†
PC of MTT vs AS	0.25	0.32	0.33	0.48^†
Observer 2
CBV vs AS	0.37	0.26	0.31	0.67^†
CBF vs AS	−0.14	−0.27	−0.47^†	−0.31
MTT vs AS	0.46^†	0.38^†	0.53^†	0.64^†
PC of CBV vs AS	−0.33	0.14	−0.29	−0.19
PC of CBF vs AS	−0.69^†	−0.45^†	−0.83^†	−0.79^†
PC of MTT vs AS	0.28	0.34	0.31	0.49^†

Note:—CBV indicates normalized cerebral blood volume; CBF, normalized cerebral blood flow; MTT, normalized mean transit time; PC, percent change; AS, angiographic stage; BG, basal ganglia; ACA, anterior cerebral artery; MCA, middle cerebral artery; EBZ, anterior external border zone.
* Values are Pearson correlation coefficient (r).
† Values are statistically significant (P < .05).

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Table 5:

Differences of the mean values of normalized hemodynamic parameters according to the presence of BMV

Variable	BG		ACA		MCA		EBZ
Variable	BMV(+)	BMV(−)	BMV(+)	BMV(−)	BMV(+)	BMV(−)	BMV(+)	BMV(−)
Observer 1
CBV	1.34	1.22	1.21	1.14	1.06	0.98	1.24^*	1.07^*
CBF	1.27	1.21	0.85	0.97	0.75	0.89	0.78^*	0.99^*
MTT	1.10	1.04	1.45^*	1.21^*	1.46	1.20	1.76^*	1.20^*
PC of CBV	−2%	5%	−5%	−6%	−3%	4%	−11%	−5%
PC of CBF	−29%	−15%	−24%	−17%	−33%^*	−18%^*	−39%^*	−21%^*
PC of MTT	25%	20%	31%	22%	30%	22%	37%	26%
Observer 2
CBV	1.33	1.20	1.22	1.17	1.09	1.01	1.27^*	1.10^*
CBF	1.29	1.19	0.92	0.95	0.77	0.89	0.82^*	0.96^*
MTT	1.11	1.01	1.45^*	1.24^*	1.42	1.22	1.71^*	1.22^*
PC of CBV	−4%	5%	−7%	−9%	−6%	1%	−9%	−4%
PC of CBF	−32%	−16%	−21%	−13%	−32%^*	−19%^*	−33%^*	−19%^*
PC of MTT	27%	24%	35%	27%	27%	19%	34%	27%

Note:—CBV indicates normalized cerebral blood volume; CBF, normalized cerebral blood flow; MTT, normalized mean transit time; PC, percent change; BG, basal ganglia; ACA, anterior cerebral artery; MCA, middle cerebral artery; EBZ, anterior external border zone; BMV, basal Moyamoya vessel.
* Values are statistically significant (P < .05) by using analysis of variance and the multiple comparison test.