Noninvasive measurement of cerebral blood flow with (99m)Tc-hexamethylpropyleneamine oxime single-photon emission computed tomography and 1-point venous blood sampling.

BACKGROUND AND PURPOSE The arterial and venous blood concentration of technetium 99m-labeled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) reaches an equilibration more rapidly than other CBF tracers. We hypothesized that (99m)Tc radioactivity of a venous sample at equilibrium, which is similar to that of an arterial sample, would allow estimation of the integrated input function for the clinical measurement of CBF by use of single-photon emission CT. METHODS In 53 patients with stable cerebrovascular disease, the radioactivity of a venous sample 5 minutes after injection of (99m)Tc-HMPAO was correlated with 5-minute arterial blood radioactivity and the first 5 minutes of the integrated arterial curves of the lipophilic tracer. The measured CBF values were compared with those of xenon 133. RESULTS The radioactivity of 5-minute venous blood was almost equivalent to that of 5-minute arterial blood (r(2) = 0.987; y = 0.993x + 1.63; P : <0.0001). The correlation between the venous blood radioactivity and the integrated arterial lipophilic fraction was excellent (r(2) = 0.935, P : <0.0001). A strong correlation was obtained between (99m)Tc-HMPAO and (133)Xe CBF values (r(2) = 0.825, P : <0.0001). CBF values were reproducible (coefficient of variation, 8.6%). CONCLUSIONS This approach is fast, simple, and an alternative to continuous blood sampling in clinical quantitative (99m)Tc-HMPAO CBF studies.