Dopamine Transporter Scan (DaTscan)

Abstract

Dopamine transporter scan (DaTscan), as the name implies, is a brain SPECT imaging modality with ¹²³I-ioflupane as the radioactive tracer that has a high binding affinity to striatal dopamine transporters. In 2011, FDA approved the clinical use of DaTscan in the US to help differentiate essential tremor (ET) from tremor due to Parkinson’s disease (PD), multiple system atrophy (MSA), or progressive supranuclear palsy (PSP). Such differentiation could be crucial for certain patients’ clinical diagnosis, choice of pharmacotherapy, and prognostic evaluation (Booij et al., Q J Nucl Med Mol Imaging 56:17–26, 2012; Davidsson et al., Ann Nucl Med 28(9):851–859, 2014; Gayed et al., Clin Nucl Med 40(5):390–393, 2015). A normal DaTscan is characterized by crescent-shaped tracer activity with highest tracer intensity in caudate nuclei tapering into putamen body and tail in both hemispheres. Since dopamine neurons in putamen are more vulnerable to neurodegenerative insults compared to those in caudate nuclei, an abnormal DaTscan manifests asymmetrically decreased tracer activity due to striatal dopamine neuron loss, depending on disease staging, typically initial affecting one of the putamens and then spreading into the contralateral putamen and/or the ipsilateral caudate nuclei and finally the caudate nuclei on both sides (Brooks, Parkinsonism Relat Disord 18S1:S31–S33, 2012; Meles et al., J Nucl Med 58:23–28, 2017; Pagano et al., Clin Med (Lond) 16(4):371–375, 2016). This unique neuroimaging pattern not only helps diagnose PD, but also assists in the differentiation of PD from Parkinsonism associated with or caused by other neurodisorders. Presented in this chapter are selected cases with probable normal DaTscan in patients with ET or neuroleptic-induced Parkinsonism, and abnormal DaTscans due to a variety of underlying causes, including probable early and advanced idiopathic PD, cerebrovascular accident (CVA)/stroke, arteriovenous malformation (AVM), corticobasal degeneration (CBD), PSP, and MSA.