Modifications of fractional uptake method for 123I-IMP

We intended to improve the fractional uptake (FU) method which was developed to quantify cerebral blood flow using 123I-IMP without blood sampling. The quantification of cardiac output (CO) using first-pass data was adapted to FU method while the original FU method used CO which was estimated from the body surface area of patients. Time-radioactivity curves of the lungs and brain were separately obtained by a small-field-of-view gamma camera. In 24 cases, mean cerebral blood flow (mCBF) obtained by the modified FU method showed the better correlation (r=0.833, p<0.001) to mCBF measured by the Patlak plot with 99mTc-HMPAO than the original FU method (r=0.667, p<0.01). With these modifications, the reliability of FU method could be improved and the modified FU method might be performed in the other institutions. (author)