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AJNR - American Journal of Neuroradiology

Published ahead of print on October 14, 2008
doi: 10.3174/ajnr.A1316

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Hypercapnia-Induced Cerebral Hyperperfusion: An Underrecognized Clinical Entity

J.M. Pollock^a, A.R. Deibler^a, C.T. Whitlow^a, H. Tan^b, R.A. Kraft^b, J.H. Burdette^a and J.A. Maldjian^a

^a Departments of Radiology, Wake Forest University School of Medicine, Winston-Salem, NC
^b Departments of Biomedical Engineering, Wake Forest University School of Medicine, Winston-Salem, NC

View larger version (61K): [in this window] [in a new window]   Fig 1. Typical clinical ASL map for a normocapnic 57-year-old patient with mild age-related degenerative changes. Normal CBF is depicted throughout GM with a GM CBF mean of 62.9 mL/100 g/min. The pCO2 measured 38.8 mm Hg.

View larger version (61K): [in this window] [in a new window]   Fig 2. ASL CBF perfusion map in a hypocapnic 58-year-old patient suspected of having an acute infarct. No abnormality was detected on conventional imaging, but the patient had marked global hypoperfusion (mean GM CBF, 25.5 mL/100 g/min). ABG showed pCO2 of 34.4 mm Hg.

View larger version (62K): [in this window] [in a new window]   Fig 3. ASL CBF map performed as part of the MR imaging examination demonstrated markedly increased blood flow in all GM and white matter structures consistent with global hyperperfusion (mean GM CBF, 175.2 mL/100 g tissue/min). Chest radiograph from the same date was significant for emphysema, and ABG analysis revealed a pCO2 of 56.3 mm Hg (normal range, 35–45 mm Hg).

View larger version (11K): [in this window] [in a new window]   Fig 4. Graph demonstrates global rates of CBF (mL/100 g/min) in GM, expressed as mean ± SD, for 3 groups (hypercapnia, normocapnia, and hypocapnia) on the basis of ABG measures of pCO2. The asterisk (*) indicates a statistically significant difference from the normocapnia group. The cross () indicates a statistically significant difference between the hypercapnia and hypocapnia groups. Global rates of CBF are 106.1% higher in the hypercapnia group and 38.6% lower in the hypocapnia group compared with normocapnic control subjects.

View larger version (10K): [in this window] [in a new window]   Fig 5. Graph of percent change versus pCO2 for all groups shows a strong linear relationship between global GM CBF and pCO2 with slight differences between male (red) and female (blue) patients.