Journal of Nuclear Medicine Technology, Vol 26, Issue 3 191-195, Copyright © 1998 by Society of Nuclear Medicine
Measurement of blood radioactivity for quantification of cerebral blood flow using a gamma camera
K Murase, H Fujioka, T Inoue, Y Ishimaru, A Akamune, Y Yamamoto and J Ikezoe
Department of Radiology, Ehime University School of Medicine, Onsen-gun, Japan.
OBJECTIVE: This study was designed to determine whether gamma cameras can
be substituted for well-type scintillation counters in measuring blood
radioactivity counts to be used as an input function for the quantitative
measurement of cerebral blood flow (CBF). METHODS: Twelve different aqueous
123I solutions were prepared by serial dilution of the original
concentration of 281.9 kBq/ml, and the radioactivity count of each dilution
was measured with a gamma camera with the collimator removed, and with a
well-type scintillation counter. When measuring the radioactivity counts
with a gamma camera, static images were acquired using a 128 x 128 matrix
for 5 min, and the regions of interest with 14 x 14 pixels (21 mm x 21 mm)
were defined. RESULTS: There was a good correlation between the results
obtained by these two procedures in the range of concentration between
0.008 kBq/ml and 281.9 kBq/ml (y = 4.245x-2.549, r = 1.0, n = 12, s.e.e. =
7.217 kcpm). There was good agreement between the CBF values (ml/100 g/min)
obtained using the cross-calibration factor (CCF) and blood radioactivity
counts measured with the two procedures (y = 0.990x + 0.552, r = 0.990, n =
231, s.e.e. = 1.340 ml/100 g/min). CONCLUSION: The results suggest that
gamma cameras can be substituted for well-type scintillation counters in
the quantitative measurement of CBF, and make it unnecessary to measure CCF
after routine calibration of a SPECT apparatus.
