Abstract
BOLD MR imaging combined with a technique for precision control of end-tidal pCO(2) was used to produce quantitative maps of CVR in patients with Moyamoya disease. The technique was validated against measures of disease severity by using conventional angiography; it then was used to study the relationship between CVR, vascular steal, and disease severity. A retrospective analysis comparing conventional angiography with BOLD MR imaging was performed on 11 patients with Moyamoya disease. Iso-oxic cycling of end-tidal pCO(2) between 2 target values was performed during BOLD MR imaging. CVR was calculated as the BOLD signal difference per Delta pCO(2). CVR was correlated with the presence of Moyamoya or pial collaterals and the degree of Moyamoya disease as graded by using a modified Suzuki score. A good correlation between mean CVR and Suzuki score was found for the MCA and ACA territories (Pearson correlation coefficient, -0.7560 and -0.6140, respectively; P < .0001). A similar correlation was found between mean CVR and the presence of pial and Moyamoya collateral vessels for combined MCA and ACA territories (Pearson correlation coefficient, -0.7466; P < .0001). On a voxel-for-voxel basis, there was a greater extent of steal within vascular territories with increasing disease severity (higher modified Suzuki score). Mean CVR was found to scale nonlinearly with the extent of vascular steal. Quantitative measures of CVR show direct correlation with impaired vascular supply as measured by the modified Suzuki score and enable direct investigation of the physiology of autoregulatory reserve, including steal phenomenon, within a given vascular territory.
Highlights
BOLD MR imaging combined with a technique for precision control of end-tidal pCO2 was used to produce quantitative maps of CVR in patients with Moyamoya disease
The technique was validated against measures of disease severity by using conventional angiography; it was used to study the relationship between CVR, vascular steal, and disease severity
Positive; SE ⫽ standard error; SPECT ⫽ single-photon emission CT; TIA ⫽ transient ischemic attack oyamoya disease is a vasculopathy affecting the proximal circle of Willis vessels characterized by progressive narrowing and formation of secondary collaterals
Summary
MR imaging was performed on 11 patients with Moyamoya disease. CVR was calculated as the BOLD signal difference per ⌬pCO2. CVR was correlated with the presence of Moyamoya or pial collaterals and the degree of Moyamaya disease as graded by using a modified Suzuki score. A least-squares regression analysis of the BOLD signal intensity versus the CO2 waveform for each voxel was calculated. CVR for each voxel was calculated according to the following: CVRvoxel ⫽ ⌬S ⫼ ⌬pCO2, where ⌬S is the change in MR signal intensity for a given voxel that occurs between peak and trough CO2 levels and ⌬pCO2 is the change in end-tidal CO2 in mmHg. In healthy brain, CVR is positive, reflectAJNR Am J Neuroradiol 31:862– 67 兩 May 2010 兩 www.ajnr.org
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