The validity and value of a quantitative SPECT reconstruction package (QSPECT) for evaluating multi-center clinical trials

SPECT has the potential to provide parametric functional images, in a"quantitativemanner, for several radiotracers in vivo, as has been widely done with PET. Due to the ready availability of SPECT, in addition to the well-established delivery/transportation of various radio-ligands, SPECT has an advantage for large-scale clinical evaluation. It has, however, been considered that the accuracy and inter-institutional reproducibility of SPECT are not well verified, which is largely attributed to a lack of general consensus of reconstruction procedures (attenuation/scatter correction). We have recently developed a novel method to reconstruct SPECT images from existing projection data including appropriate corrections for scatter and attenuation in the object. We have demonstrated that this program is capable of providing accurate radio-distribution in the brain and thorax regions, and also rest-Diamox CBF using split-dose ¹²³I amphetamine (IMP). Various phantom experiments also supported the validity of inter-institutional reproducibility. These data suggested that QSPECT could be a useful tool for quantitative mapping in clinical research, allowing for large scale clinical evaluations even when using SPECT cameras from different manufacturers.