K. Murase et al., An alternative approach to estimation of the brain perfusion index for measurement of cerebral blood flow using technetium-99m compounds, EUR J NUCL, 26(10), 1999, pp. 1333-1339
Citations number
18
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Medical Research Diagnosis & Treatment
Cerebral blood flow (CBF) has been quantified non-invasively using the brai
n perfusion index (BPI) determined from radionuclide angiographic data gene
rated by technetium-99m hexamethylpropylene amine oxime (Tc-99m-HMPAO) or t
echnetium-99m ethyl cysteinate dimer (Tc-99m-ECD). The BPI is generally cal
culated using graphical analysis (GA). In the present study, BPI was measur
ed 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 Tc-99m-HMPAO and from those of 20 patients using Tc-99m-ECD. We also
measured BPI using GA. The BPI values obtained by SA (BPIS) (x) and by GA
(BPIG) (y) correlated closely (y=0.708x+0.038, r=0.945 for Tc-99m-HMPAO and
y=0.559x+0.093, r=0.931 for Tc-99m-ECD). However, the BPIG values were und
erestimated by 22.9%+/-6.6% (mean+/-SD) for Tc-99m-HMPAO and by 27.9%+/-7.5
% for Tc-99m-ECD as compared with the BPIS values. The extent of underestim
ation tended to increase with increasing BPIS values. These findings were c
onsidered to be a result of the BPIG values being affected by the first-pas
s extraction fraction of the tracer. We also compared the BPIS and BPIG val
ues with those of CBF measured using N-isopropyl-p-[I-123]iodoamphetamine (
CBFIMP) in 16 patients (six for Tc-99m-HMPAO and ten for Tc-99m-ECD). Altho
ugh both BPIS and BPIG values correlated significantly with the CBFIMP valu
es, the correlation coefficient in BPIS was always better than that in BPIG
(r=0.869 for Tc-99m-HMPAO and r=0.929 for Tc-99m-ECD in BPIS, r=0.629 for
Tc-99m-HMPAO and r=0.856 for Tc-99m-ECD in BPIG). These results suggest tha
t SA can provide a more reliable BPI for quantifying CBF using Tc-99m-HMPAO
or Tc-99m-ECD than the conventional method using GA. Our method will be us
eful especially when using a tracer with a low first-pass extraction fracti
on and/or when performing activation studies using pharmacological interven
tion.