Impact of CT based attenuation correction on quantitative assessment of DaTSCAN ((123)I-Ioflupane) imaging in diagnosis of extrapyramidal diseases.

The quality of visually and semi-quantitatively assessed DaTSCAN images is crucial for differential diagnostics of extrapyramidal diseases. Neuroimaging with the use of presynaptic tracers of the dopaminergic system provides evidence of nigrostriatal degeneration and may support the clinical diagnosis of Parkinsonism. During the last two years (2007-2008) we tried to elaborate the optimal methodology of SPECT/CT examination with the use of DaTSCAN ((123)I-Ioflupane), and we sought to evaluate the effect of the reconstruction and attenuation correction method on semi-quantitative measures of relative uptake in the striatum. In a present study, we retrospectively studied DaTSCAN scans of 44 consecutive patients with clinical indications of Parkinson's disease or uncertain Parkinsonian syndromes. The quality of DaTSCAN images reconstructed with the use of ordered-subset expectation maximization reconstruction technique (OSEM) with attenuation correction based on CT maps was found to be superior to that provided by the commonly applied filtered backprojection method (FBP) with Chang attenuation correction. OSEM reconstructed transverse slices were more legible for clinical interpretation because of increased contrast and improved delineation between striatum structures. Semi-quantitative assessments of relative striatum uptake for OSEM reconstructed slices secured better intra-operator reproducibility than that obtained by FBP method.