Intravenous 99mTc HM-PAO radionuclide angiography as an adjunct to SPECT assessment of cerebral disease.

An application of intravenous radionuclide angiography as an adjunct to SPECT with 99mTc HM-PAO is presented. From the angiographic sequence a two-dimensional parametric image is generated computing, pixel by pixel, the center of gravity (COG) of the local time curves. This index is independent of blood flow and reflects the relation between transmitted and extravasated activity. COG value, compared in two symmetrical regions analyzed for differences in flow by SPECT, may help to state whether a detected SPECT changed uptake is linearly related or not to the corresponding change of blood flow. All 23 ischemic patients taken into consideration had a similar backflux in symmetrical regions with conspicuous changed uptake. In 3 meningiomas and 2 arteriovenous angiomas it was possible to detect the occurrence of a changed backflux in the lesion suggesting a nonlinearity between blood flow and 99mTc HM-PAO uptake.