Fig. 3

Examples of extreme discrepant results between the two software (a, b) and between the expert reading and either of the two software (c). a A 80-year-old man with de novo Parkinson’s disease presenting with bradykinesia, right hand resting tremor and upper arm rigidity, mainly on the right side. The diagnosis is confirmed at 1-y follow-up visit with moderate response to L-DOPA therapy. On DAT SPECT, the experts report reduced tracer uptake in both putamina, mainly on the left side, consistent with clinical presentation. BasGanV2 (upper right) identifies normal caudate uptake but significantly reduced putamen uptake bilaterally. This finding is missed by Datquant® that even shows SBR values at the upper limit of normalcy (upper left). The two images in the lower part of a are examples of ROI drawing on the basal ganglia and background, the latter partially falling outside the brain in the right image. Of note, Datquant® correctly highlights a reduced ratio between putamen and caudate uptake (z-score − 3.47 on the left side) thus confirming that the bias is introduced by the background ROI. On left, for Datquant®, the position of patient SBR (y-axis) is shown in red in the graph, while gray points report values in normal subjects and the gray lines represent the mean with upper and lower limits of normal distribution, respectively, according to age (x-axis). This is shown for each of the four nuclei On right, for BasGanV2, the patient SBRs of either the two caudate nuclei or the two putamen are reported together, the right side in green and the left side in red; the black line represents the mean of normal controls with respect to age (x-axis), while the red and the green line report the 90% and 97% confidence level of the normal distribution, respectively. The two images on right are examples of ROI drawing on the basal ganglia and background. b A 60-year-old man with essential tremor. The diagnosis is confirmed at 1-y follow-up visit with moderate response to propranolol therapy. On DAT SPECT, the experts report a normal scan. This is confirmed by Datquant® analysis (mid-left), whereas BasGanV2 (mid-right) identifies borderline SBR values for caudate and significantly reduced SBR for putamen bilaterally. Other details as in a. c A 80-year-old man with de novo Parkinson’s disease presenting with bradykinesia, both resting and intention tremor at upper arms, with prevalence on the right side, constipation and REM sleep behavior disorder. The diagnosis is confirmed at 1-y follow-up visit with good response to L-DOPA therapy. On DAT SPECT, the experts report reduced tracer uptake in both putamina, mainly on the left side, consistent with clinical diagnosis. On the contrary, both Datquant® (bottom left) and BasGanV2 (bottom right) identify normal caudate and putamen SBRs. Other details as in a