Cerebral blood flow (CBF) has been quantified non-invasively using the brain perfusion index (BPI) determined from radionuclide angiographic data generated by technetium-99m hexzmethylpropylene amine oxime (99mTc-HMPAO) or technetium-99m ethyl cysteinate dimer (99mTc-ECD). The BPI is generally calculated using graphical analysis (GA). In the present study, BPI was measured using spectral analysis (SA), and its usefulness evaluated in comparison with GA. The BPI was calculated from the sum of spectral data obtained by SA. We applied this method to radionuclide angiographic data collected from the bilateral brain hemispheres of 20 patients with various brain diseases using 99mTc-HMPAO and from those of 20 patients using 99mTc-ECD. We also measured BPI using GA. The BPI values obtained by SA (BPI(S)) (x) and by GA (BPI(G)) (y) correlated closely (y = 0.708x + 0.038, r = 0.945 for 99mTc-HMPAO and y = 0.559x + 0.093, r = 0.931 for 99mTc-ECD). However, the BPI(G) values were underestimated by 22.9% ± 6.6% (mean ± SD) for 99mTc-HMPAO and by 27.9% ± 7.5% for 99mTc-ECD as compared with the BPI(S) values. The extent of underestimation tended to increase with increasing BPI(S) values. These findings were considered to be a result of the BPI(G) values being affected by the first-pass extraction fraction of the tracer. We also compared the BPI(S) and BPI(G) values with those of CBF measured using N-isopropyl-p-[123I]iodoamphetamine (CBF(IMP)) in 16 patients (six for 99mTc-HMPAO and ten for 99mTc-ECD). Although both BPI(S) and BPI(G) values correlated significantly with the CBF(IMP) values, the correlation coefficient in BPI(S) was always better than that in BPI(G) (r = 0.869 for 99mTc-HMPAO and r = 0.929 for 99mTc-ECD in BPI(S), r = 0.629 for 99mTc-HMPAO and r = 0.856 for 99mTc-ECD in BPI(G)). These results suggest that SA can provide a more reliable BPI for quantifying CBF using 99mTc-HMPAO or 99mTc-ECD than the conventional method using GA. Our method will be useful especially when using a tracer with a low first-pass extraction fraction and/or when performing activation studies using pharmacological intervention.
- Brain perfusion index
- Graphical analysis
- Spectral analysis
- Technetium-99m ethyl cysteinate dimer
- Technetium-99m hexamethylpropylene amine oxime
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging