Parametric imaging of regional cerebral blood flow with the short-lived isotope 195mAu

The use of the short-lived (30 s) isotope 195mAu in brain perfusion studies has been tested on 40 patients and 8 volunteers. The activity of the eluate from the 195mHg/195Au generator was high enough to give good image statistics of brain perfusion after a single bolus injection. The examinations can be repeated after 3 min giving the same quality and without significant background. The use of a low-energy photon peak at 68 keV (Au-K alpha) allows the imaging of brain perfusion in both lateral views with almost no look-through effect. With a modified height-over-area formula for the calculation of regional cerebral blood flow parametric images were obtained of high diagnostic value. The sensitivity and reproducibility of the method has been demonstrated by mental stimulation tests on eight volunteers: after optical stimulation a clear increase of blood flow could be shown in the visual cortex.