I-123-ioflupane quantification in Lewy Body Dementia and Parkinson Disease: Efficient role of xSPECT-derived absolute and relative SUV

Aim: Quantification of I-123-Ioflupane uptake within basal ganglia using the latest SPECT scanners may add valuable accuracy in the diagnosis of nigro-striatal pathway pathologies. We investigated the role of absolute and relative SUV quantification of I-123-Ioflupane in differentiating between normal and pathologic patients investigated for Lewy Body Dementia (LBD) and Parkinson Disease (PD).

Methods: In total, 36 individuals (PD group, n=25 and LBD group, n=11) were scanned (Symbia Intevo, Siemens Healthcare) and images were reconstructed using conventional iterative reconstruction (Flash 3D) and the xSPECT quantitative reconstruction providing SUV values. Data were analyzed using Scenium (Siemens Healthcare) by a coregistration of the individual tomographic data to a reference template followed by the application of a standard set of volumes of interest (VOI). Mean regional counts and absolute SUV values were automatically extracted 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 SUVmean, SUVmax 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, twelve (PD, 48%) and four cases (LBD, 36%) were scored as abnormal. Absolute SUVmax and rSUV allowed to differentiate between normal and pathological DATscan in the caudate nucleus (PD: p=0.013, LBD: p<0.005 and PD: p=0.005, LBD: p<0.005), putamen (PD: p=0.021, LBD: p<0.05 and PD: p<0.005, LBD: p<0.005) and striatum (p=0.017, p=0.047 and p<0.05, <0.005). SUVmean allowed to differentiate between normal and pathological cases in the striatum (p<0.05) but not in the caudate nucleus (p=0.571) in LBD group and the putamen (p=0.056) in PD group.Striatum SUVmax and rSUV showed a trend for higher values in pathologic LBD compared to PD subgroups (7.1±2.8 versus 5.7±1.8, p=0.077 and 3.1±0.6 versus 2.8±0.6, p=0.056, respectively), while SUVmean showed no statically significant difference (p=0.5).

Conclusions: Quantification of I-123-ioflupane uptake using xSPECT-derived values including absolute SUVmax and rSUV allowed to differentiate between normal and pathological DATscan in PD and LBD. This tool has the potential to increase diagnostic accuracy by eliminating the background noise bias, as well as increasing DATscan specificity.