I-123-ioflupane quantification in Lewy Body Dementia and Parkinson Disease using xSPECT-derived absolute and relative SUV: an updated analysis

Aim: Quantification of I-123-Ioflupane uptake within basal ganglia using the latest SPECT scanners may add valuable accuracy to diagnosis of nigrostriatal pathway pathologies. We investigated the validity of absolute and relative SUV quantification of I-123-Ioflupane compared to the conventional visual rating in differentiating between normal and pathologic scans in patients investigated for either presumed Lewy Body Dementia (LBD) or Parkinson Disease (PD). Materials and Methods: Hundred eleven individuals (PD, n=79; LBD, n=32) were scanned (Symbia Intevo, Siemens Healthineers) and images reconstructed using conventional iterative reconstruction (Flash 3D) and quantitative xSPECT reconstruction providing SUV values. Data were analyzed using Scenium (Siemens Healthineers) by a co-registration of the individual tomographic data to a reference template followed by the application of a standard set of volumes of interest (VOI) and fully-automated extraction of mean regional counts and SUV values for the left and right caudate nucleus, putamen and striatum, as well as for the occipital region, taken as reference region for the calculation of relative SUV (rSUV). We compared SUV_mean, SUV_max and rSUV in normal and abnormal subgroups for each region of interest and between both groups.

Results: Based on visual rating and relative metric methods, 48/79 (61%) with presumed PD and 14/32 (43%) with LBD scans were scored as abnormal.Absolute SUV_max and rSUV allowed differentiating between normal and pathological DATscan in the caudate nucleus (p<0.005 and p=0.01), putamen (p<0.005 and p<0.005) and striatum (p<0.005 and p<0.005) in PD subgroup and in the putamen (p<0.005 and p<0.005) in LBD subgroup. Absolute SUV_max allowed differentiating between normal and pathological DATscan in the striatum (p<0.005) and rSUV in the caudate nucleus (p<0.005) in LBD subgroup. SUV_mean allowed to differentiate between normal and pathological cases in the striatum (PD: p<0.005, LBD: p<0.005), putamen (PD: p<0.005, LBD: p<0.005) and caudate nucleus (PD: p<0.005, LBD: p=0.006) for both PD and LBD subgroups.Only caudate nucleus SUV_mean and rSUV showed significantly lower values in pathologic LBD compared to PD subgroup.

Conclusions: Quantification of I-123-ioflupane uptake using xSPECT-derived allows differentiating between normal and pathological DATscan in PD and LBD. This has the potential to increase diagnostic accuracy by eliminating background noise bias, as well as increasing DATscan specificity.