Virtual MRI-derived SPECT for the visual analysis of Parkinson's disease in early stage.

The differential diagnosis of Parkinson desease versus other forms of pakinsonism is not easy to be achieved. Imaging of dopamine transporter binding by means of nuclear medicine techniques is often used to improve the probability of a correct diagnosis in the early stages. Crucial for this kind of studies is the correct determination of the dopamine transporter receptor density in the posterior part of the putamens. Unfortunately, tomographic images of these structures are strongly affected by the partial-volume effect (PVE). Since its correction is often tricky and difficult to realize, we propose here a method in which the nuclear medicine study is compared to virtual images derived from MRI. This method enhances the accuracy of the nuclear medicine procedure, helping the physician to differentiate between partial-volume effects and real hypofixation of the tracer, in particular in the early phase of the disease.