Speaker
Dr
A. Varrone
Description
Abstract. The development of radioligands for the dopaminergic system has provided suitable imaging biomarkers for clinical research in Parkinson´s disease and related movement disorders. Single photon emission tomography (SPECT) has played an important role as main molecular imaging modality because of the availability of imaging tools such as dopamine transporter (DAT) radioligands for wide clinical use. At present, SPECT imaging of the DAT is the main diagnostic imaging procedure for the assessment of patients with suspected degenerative parkinsonism, providing also reliable quantitative outcome measures that correlate with the severity of the disease. Therefore, DAT SPECT has been also used as an imaging biomarker in clinical trials aimed at evaluating putative disease-modifying effects of different drugs for the treatment of Parkinson´s disease.
Although imaging of the DAT in the striatum is possible with SPECT, visualization and quantification of the DAT in the substantia nigra, the primary site of Parkinson´s disease pathology, is hampered by its limited resolution. Recently, positron emission tomography (PET) has become a more widely available Nuclear Medicine technique. Because of the improved resolution and sensitivity of the most recent PET/CT systems, more widespread application of brain PET as a diagnostic imaging modality could be envisaged in the future. For many years, [18F]fluorodopa has been the most widely acknowledged 18F-labelled PET radioligand for the assessment of the integrity of the dopaminergic terminals and for the evaluation of the progression of the dopaminergic deficit in Parkinson´s disease. Other suitable imaging targets for the assessment of the integrity of the dopaminergic terminals include the DAT and the vescicular monoamine transporter type 2 (VMAT2). This presentation will summarize the main applications of molecular imaging in Parkinson´s disease. The status of the development of 18F-radioligands for the pre-synaptic dopaminergic system will also be discussed, together with the potential advantages of PET imaging biomarkers for clinical research in parkinsonian disorders.