Assessment of 99mTc-HM-PAO parameters with SPECT for improved evaluation of blood flow in cerebral lesions.

A method for investigating the linearity between blood flow and distribution of 99mTc-HM-PAO uptake in patients undergoing single photon emission computed tomography (SPECT) is presented. This method, based on particular elaboration techniques of sequential multiple acquisitions, provides a local index: cumulative transit time (CTT) related to all factors, other than blood flow, affecting 99mTc-HM-PAO uptake. Because a correct qualitative blood flow estimation is based on the uniformity of the above factors, the occurrence of a change of this index indicates a nonlinear relation between blood flow and 99mTc-HM-PAO uptake distributions. It was shown that although linearity between blood flow and 99mTc-HM-PAO uptake may be questionable, a qualitative assessment of blood flow was correct in 100% of ischemic patients. In nonischemic patients this percentage fell to 60%.