What is a Dopamine Transporter (DAT) scan?

From the Guidelines

A Dopamine Transporter (DAT) scan is a valuable test used to differentiate Parkinsonian syndromes from essential tremor and drug-induced tremor by demonstrating abnormality early in the disease course, as evidenced by the binding of I-123 ioflupane to dopamine transporters 1. The procedure involves the use of a radioactive tracer, such as I-123 ioflupane, which binds to the dopamine transporters in the brain, allowing for the visualization of the integrity of dopamine-producing neurons. Key points about DAT scans include:

• They can demonstrate the loss of presynaptic dopaminergic neurons in Parkinson's disease (PD) by showing decreased radiotracer uptake in the striatum, usually in a posterior to anterior direction from the putamen to the caudate nuclei 1.
• A normal I-123 ioflupane SPECT/CT essentially excludes Parkinsonian syndromes, making it a useful tool in clinically uncertain cases to guide appropriate treatment decisions 1.
• DAT scans can distinguish Parkinson's disease from essential tremor and drug-induced parkinsonism, as Parkinson's shows reduced dopamine transporter activity in specific brain regions 1. The role of DAT scans in the evaluation of patients with suspected PD is significant, and emerging new nuclear medicine tracers, such as 11C-raclopride-PET and I-123-iodobenzamide SPECT scans, may further enhance the diagnostic capabilities in the future 1.

From the FDA Drug Label

Ioflupane I 123 Injection is indicated as an adjunct to other diagnostic evaluations for striatal dopamine transporter visualization using single photon emission computed tomography (SPECT) brain imaging in adult patients with: suspected Parkinsonian syndromes (PS) or suspected dementia with Lewy bodies (DLB). Ioflupane I 123 Injection is a radioactive diagnostic agent indicated as an adjunct to other diagnostic evaluations for striatal dopamine transporter visualization using single photon emission computed tomography (SPECT) brain imaging in adult patients with: suspected Parkinsonian syndromes (PS) or suspected dementia with Lewy bodies (DLB). Ioflupane I 123 Injection is a radioactive diagnostic agent indicated as an adjunct to other diagnostic evaluations for striatal dopamine transporter visualization using single photon emission computed tomography (SPECT) brain imaging in adult patients with: suspected Parkinsonian syndromes (PS) or suspected dementia with Lewy bodies (DLB) 2, 2, 2.

A Dopamine Transporter (DAT) scan is a type of brain imaging test that uses single photon emission computed tomography (SPECT) to visualize the striatal dopamine transporter in adult patients with suspected Parkinsonian syndromes (PS) or dementia with Lewy bodies (DLB).

• It involves the use of a radioactive diagnostic agent, such as Ioflupane I 123 Injection.
• The test is used as an adjunct to other diagnostic evaluations to help diagnose or rule out these conditions.

From the Research

Definition and Purpose of Dopamine Transporter (DAT) Scan

• A DAT scan is a medical imaging test that measures the availability of dopamine transporters in the brain, providing a measure of dopamine terminal function and detecting striatal dopamine deficiency states [(3,4)].
• The primary purpose of a DAT scan is to support or refute a diagnosis of dopamine-deficient parkinsonism, such as idiopathic Parkinson's disease (PD) and atypical neurodegenerative parkinsonian disorders [(3,5,6,4,7)].

Diagnostic Applications of DAT Scan

• DAT scans can help differentiate between neurodegenerative and non-neurodegenerative parkinsonism, as well as essential tremor (ET) [(5,6)].
• The scan can detect subclinical dopaminergic dysfunction in subjects at risk for PD, such as relatives of patients, susceptibility gene mutation carriers, and subjects with late-onset hyposmia or sleep disorders [(3,4,7)].
• A normal DAT scan can help exclude nondopamine-deficient syndromes, such as dystonic and severe essential tremors, drug-induced and psychogenic parkinsonism [(3,6,4)].

Imaging Techniques and Interpretation

• DAT scans can be performed using positron emission tomography (PET) or single photon emission computed tomography (SPECT) [(3,4,7)].
• Reduced levels of baseline striatal DAT availability on PET or SPECT scanning should be regarded as supportive rather than diagnostic of dopamine-deficient parkinsonism 3.
• The presence of normal DAT availability on imaging can help categorize "subjects without evidence of dopamine deficiency" (SWEDDs) who may mimic PD 3.