Abstract
Aims: ¹²³I-ioflupane (DaTSCANT) is used for the differentiation of Parkinson's Syndrome (PS) from parkinsonism without nigrostriatal degeneration in patients with symptoms suggestive of PS. However, there remains some controversy as to the best method to report the resulting images and therefore the aim of this study was to retrospectively compare the visual assessment of ¹²³I-ioflupane with Specific Binding Indices (SBIs) as calculated using quantitative analysis to see if there was a good correlation between what was reported visually and the objective measurements of uptake measured by SBIs.

Methods: The study reviewed the images thirty-one patients with parkinsonism (19 males, mean age 55.3±15 years). Three nuclear medicine consultants visually rated the images, grade 0 for normal to grade 3 for severe abnormality, according to the classification reported by Catafau et al. SBIs were calculated for the striatum and striatal subregions (head of caudate and putamen) quantitatively from two summed consecutive transaxial slices with the most intense striatal binding.

Results: 11 patients (35%) were reported as normal. Of the abnormal scans 3 (15%) were reported as grade 1, 14 (70%) as grade 2 and 3 (15%) as grade 3. The mean nigrostriatal SBI was 3.20±0.91 in the visually assessed normal scans, and reduced to 1.97 ± 0.79 in grade 1, 1.47±0.51 in grade 2 and 0.51±0.27 in grade 3 scans with a similar decrease in all nigrostriatal subregions. The visual assessment grades showed a highly significant negative correlation with SBIs from both the striatum and subregions (mean Spearman's correlation coefficient -0.815, P < 0.0001).

Conclusion: There is a highly significant correlation between semi-quantitative ¹²³I-ioflupane image analysis and visual assessment of the severity of PS.