Abstract: Objective To evaluate the cerebrovascular reserve (CVR) with 13N-ammonia PET/CT and methazolamide in patients with cerebral ischemic disease. Methods From January, 2014 to December, 2015, basal and stress PET/CT were performed in ten healthy persons and 53 patients with unilateral internal carotid artery or middle cerebral artery stenosis. Radioactive counts were measured on mirror regions of bilateral frontal lobe, parietal lobe, temporal lobe, occipital lobe, basal ganglia and thalamus to calculate the blood flow change rate. Results For the healthy persons, the radioactive distribution of bilateral frontal lobe, parietal lobe, temporal lobe, occipital lobe, basal ganglia and thalamus were roughly symmetrical on both basal and stress PET/CT. The radioactive counts were more in basal ganglia and thalamus than in cortex, and the least in white matter. The radioactive counts were more on stress PET/CT than basal PET/CT, and there was no significant difference between both sides (t=1.552, P=0.132). For the patients, the blood flow perfusion decreased in 39 patients with 126 regions on basal PET/CT, and 49 patients with 183 regions on stress PET/CT. Within the 39 patients who found decreased blood flow perfusion regions, 16 patients were found new regions on stress PET/CT, and 29 regions of 13 patients improved in blood flow perfusion on stress PET/ CT. The blood flow change rate was significantly different between basal and stress PET/CT (t=2.466, P<0.05). Conclusion 13N-ammonia PET/CT cerebral blood flow perfusion imaging combined with methazolamide stress test can evaluate the cerebrovascular reserve in patients with unilateral internal carotid artery or middle cerebral artery stenosis, and is valuable for clinical assessment and early intervention for patients with cerebral ischemic disease.

Key words: cerebral ischemic disease, cerebrovascular reserve, nitrogen radioisotopes graphy, methazolamide, positronemission tomography, computerized tomography