DaTSCAN Imaging in Aging and Neurodegenerative Disease

Lewy body disease (LBD) is one of the most common neurodegenerative diseases and second only to Alzheimer's disease in terms of prevalence, disability, and societal/financial burden. The phenotypic variability of LBD is striking, as it can manifest as the well-known disorder of Parkinson's disease without (PD) and with dementia (PDD), as well as DLB, MCI, REM sleep behavior disorder (RBD), pure autonomic failure (PAF), and other syndromes.

One biomarker which is both highly sensitive and specific for evolving LBD in the setting of dementia is DaTscan [Ioflupane (123I)] imaging, in which loss of functional dopaminergic neuron terminals in the striatum as assessed by DaTscan reflects underlying LBD in those with dementia and particularly dementia with Lewy bodies (DLB). DaTscan is the one of the first radiopharmaceutical agents available to detect DaT distribution within the brain. DaTscan imaging involves injection of the Ioflupane radioligand followed by imaging using a standard single photon emission computed tomography (SPECT) scanner. DaTscan provides visualization of the dopamine transporter (DaT) distribution within the striata (i.e., striatal uptake, or striatal signal) by SPECT imaging in patients presenting with symptoms or signs suggestive of dopaminergic neurodegeneration.

Most DaTscan studies published to date have been conducted in centers outside of the US. DaTscan has not been studied in the syndrome of MCI, and minimally in corticobasal degeneration (CBD). Very little normative data exists in the aged population either.

The FDA-approved indication is to assist in the evaluation of adult patients with suspected Parkinsonian syndromes (PS). In these patients, DaTscan may be used to help differentiate essential tremor from tremor due to Parkinsonian syndromes (such as idiopathic Parkinson's disease, multiple system atrophy and progressive supranuclear palsy). DaTscan will be used as an adjunct to other diagnostic evaluations. Identifying dopaminergic dysfunction is also important in other settings such as those with cognitive impairment with or without parkinsonism, and in subjects with REM sleep behavior disorder. The findings on DaTscan in subjects with these various disorders will be correlated with clinical diagnoses and other multimodal imaging studies (e.g., MRI, MRS, FDG-PET, and amyloid-PET) to enhance our understanding of neurodegenerative diseases. A subset of subjects will undergo a 2nd DaTscan at least 1 year after the initial scan was performed to determine if changes over time provide any prognostic information.