Evaluation of the sup 11 CO sub 2 positron emission tomographic method for measuring brain pH. II. Quantitative pH mapping in patients with ischemic cerebrovascular diseases

• Published in: Journal of cerebral blood flow and metabolism Vol. 9:6
• Main Authors: Senda, M., Alpert, N.M., Mackay, B.C., Buxton, R.B., Correia, J.A., Weise, S.B., Ackerman, R.H., Dorer, D., Buonanno, F.S.
• Format: Journal Article
• Language: English
• Published: United States 01.12.1989
• Subjects: 550601 - Medicine- Unsealed Radionuclides in Diagnostics; ANIMALS; BETA DECAY RADIOISOTOPES; BETA-PLUS DECAY RADIOISOTOPES; BLOOD FLOW; BODY; BRAIN; CARBON 11; CARBON COMPOUNDS; CARBON DIOXIDE; CARBON ISOTOPES; CARBON OXIDES; CARDIOVASCULAR DISEASES; CELL CONSTITUENTS; CELL MEMBRANES; CENTRAL NERVOUS SYSTEM; CEREBRAL CORTEX; CEREBRUM; CHALCOGENIDES; COMPUTERIZED TOMOGRAPHY; DIAGNOSIS; DIAGNOSTIC TECHNIQUES; DISEASES; EMISSION COMPUTED TOMOGRAPHY; EVEN-ODD NUCLEI; ISCHEMIA; ISOTOPES; LIGHT NUCLEI; MAMMALS; MAN; MATHEMATICAL MODELS; MEMBRANES; MINUTES LIVING RADIOISOTOPES; NERVOUS SYSTEM; NUCLEI; ORGANS; OXIDES; OXYGEN 15; OXYGEN COMPOUNDS; OXYGEN ISOTOPES; PATIENTS; PH VALUE; POSITRON COMPUTED TOMOGRAPHY; PRIMATES; RADIOISOTOPES; RADIOLOGY AND NUCLEAR MEDICINE; TOMOGRAPHY; VASCULAR DISEASES; VERTEBRATES
• ISSN: 0271-678X; 1559-7016
• DOI: 10.1038/jcbfm.1989.120

A practical method has been developed that, using {sup 11}CO{sub 2} and positron emission tomography (PET), computes and maps (a) effective pH (pHt), a weighted average of intra- and extracellular pH, and (b) clearance (K1), product of blood flow and {sup 11}CO{sub 2} extraction. This method, together with measurements of cerebral blood flow (CBF) and oxygen extraction fraction (OEF), was applied to 12 patients with cerebral ischemia or stroke. The regional K1 was positively correlated with CBF (n = +0.78). The k1/CBF ratio, representing the extraction fraction ratio of {sup 11}CO{sub 2} to H2 15O, was negatively correlated with CBF (r = -0.54), suggesting that {sup 11}CO{sub 2} extraction decreases as flow increases. In five acute stroke patients within 2 days of onset, the injured cortex had lower CBF (20.6 ml/min/100 g), higher OEF (78.1%), and lower pHt (6.96) than the contralateral cortex (CBF = 41.4 ml/min/100 g, OEF = 53.3%, pHt = 7.00), suggesting intracellular acidosis with intact cell membranes. In three stroke patients 5-8 days after onset, the injured cortex had higher CBF (60.9 ml/min/100 g), lower OEF (32.0%), and higher pHt (7.12) than the contralateral cortex (CBF = 45.3 ml/min/100 g, OEF = 58.0%, pHt = 7.06), which suggested an increase in extracellular volume compartment reflecting loss of cell membrane integrity. This method provides information on the regional tissue acid-base status and cell membrane integrity, which may be prognostic of tissue viability.