Same day cerebral perfusion and dopamine transporter imaging for differential diagnosis of cerebral impairment

When cognitive impairment is first evident it can be difficult to distinguish between different conditions such as idiopathic Parkinson's disease and Lewy body dementia. Imaging both cerebral perfusion and dopamine transporter function has been shown to provide accurate differentiation between the most common conditions. At present cerebral perfusion and dopamine transporter imaging is conducted on separate days. Carrying out both scans on the same day has the potential to benefit the patient through the social convenience of one visit to hospital and the earlier availability of results. This work considered whether it was possible to obtain diagnostic quality images from Ioflupane (¹²³I) single positron emission tomography (SPECT) acquired at the same time as or four hours after a Exametazime (^99mTc) SPECT on the same day. Possible changes to the Ioflupane (¹²³I) SPECT acquisition and processing protocols such as a new energy window and use of a resolution recovery algorithm were explored using phantom studies. Initial phantom results show that when a four hour delay between acquisitions is used comparable contrast to noise ratios can be achieved (4.23 vs. 4.63) with an insignificant loss in resolution (11.51 mm vs. 11.35 mm full width at half maximum (FWHM)). An offset energy window (159 keV -5.5% & +15.5%) was found to provide the highest contrast to noise ratio. This work provides a proof of concept for same day imaging.