Dopamine transporter SPECT: how to remove subjectivity?

Clinical criteria enable accurate and reliable diagnosis of parkinsonian syndromes when cardinal clinical features are fully developed. Single photon emission computed tomography (SPECT) investigating the striatal dopamine transporter (DAT) status have been suggested to increase the diagnostic accuracy in uncertain parkinsonian syndromes such as isolated tremor symptoms not fulfilling essential tremor criteria, as well as drug-induced, vascular and psychogenetic parkinsonism. Several approaches for the analysis of the striatal DAT distribution have been tested for their ability to analyze and quantify SPECT images. Visual assessment of DAT binding and semiquantitative analysis using region of interests have been recommended by Nuclear Medicine Associations to be incorporated in the routine work-up of DAT-SPECT. Besides these observer dependent approaches, fully automated image-analysis techniques have been validated in the clinical setting. Their potential as tools to improve the diagnostic accuracy in patients presenting with parkinsonian features is reviewed here.