Quantitation of regional cerebral blood flow by single photon emission computed tomography of CBF-tracer combined with whole-brain CBF: a comparison between 123I-IMP and 99mTc-HMPAO in healthy volunteers

A simple, noninvasive method of measuring cerebral blood flow (CBF) that uses single-photon emission computed tomography (SPECT) of CBF-tracer and whole brain CBF obtained by xenon-133 (133Xe) clearance technique was developed. In nine healthy volunteers, SPECT data were normalized to the count density of 123I-IMP or 99mTc-HMPAO uptake in the whole-brain, and then converted to the absolute units of CBF by multiplying average 133Xe-CBF in the whole brain. The CBF values measured by 99mTc-HMPAO CBF-SPECT was significantly lower in the high flow regions of cortical gray matter (bilateral frontal lobe; p < 0.05 and right occipital lobe; p < 0.05), and was significantly higher in the bilateral white matter (p < 0.05 or 0.01) and the cerebellum (p < 0.005) compared with the flow values measured by 123I-IMP CBF-SPECT. Whereas, the IMP-CBF values were significantly lower in the bilateral striatum (p < 0.02 or 0.05) compared with the HMPAO-CBF values. Good correlations were found between IMP-CBF and the HMPAO-CBF values in the cortical gray matter (rs = 0.761; p < 0.001, n = 108), the white matter (rs = 0.739; p < 0.001, n = 18) and the cerebellum (rs = 0.731; p < 0.001, n = 18). In the striatum (rs = 0.58; p < 0.05, n = 18) and the thalamus (rs = 0.628; p < 0.05, n = 18), the correlations between IMP-CBF and HMPAO-CBF values were inferior to those of the other three regions.(ABSTRACT TRUNCATED AT 250 WORDS)