Noninvasive quantitation of rat cerebral blood flow using (99m)Tc-HMPAO—assessment of input function with dynamic chest planar imaging

BACKGROUND: Cerebral blood flow (CBF) quantitation using technetium-99m hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) generally requires assessment of input function by arterial blood sampling, which would be invasive for small animals. We therefore performed chest dynamic planar imaging, instead of arterial blood sampling, to estimate the input function and establish noninvasive quantitation method of rat CBF using the image-derived input function. RESULTS: Integrated radioactivity concentration in the heart-blood pool on planar images (AUC(Blood)-planar) was identical to that in arterial blood samples (AUC(Blood)-sampling). Radioactivity concentration in the brain determined by SPECT imaging (C(Brain)-SPECT) was identical to that using brain sampling (C(Brain)-sampling). Noninvasively calculated CBF obtained by dividing C(Brain)-SPECT by AUC(Blood)-planar was well correlated with conventionally estimated CBF obtained by dividing C(Brain)-sampling by AUC(Blood)-sampling. CONCLUSION: Rat CBF could be noninvasively quantitated using (99m)Tc-HMPAO chest dynamic planar imaging and head SPECT imaging without arterial blood sampling.