When is a DaTscan (Dopamine Transporter Scan) useful?

From the Guidelines

A DatScan is useful when diagnosing Parkinsonian syndromes, such as Parkinson's disease (PD), multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD), and differentiating them from essential tremor and drug-induced tremor. This is based on the findings of a 2020 study published in the Journal of the American College of Radiology, which highlights the value of I-123 ioflupane SPECT/CT in demonstrating abnormality early in the disease course compared to anatomic imaging such as standard CT or MRI 1. The DatScan works by using a radioactive tracer (ioflupane I-123) that binds to dopamine transporters in the brain, allowing visualization of dopamine activity in the striatum.

Some key points to consider when using a DatScan include:

• A normal I-123 ioflupane SPECT/CT essentially excludes Parkinsonian syndromes 1
• The scan can demonstrate decreased radiotracer uptake in the striatum, usually in a posterior to anterior direction from the putamen to the caudate nuclei 1
• DatScan imaging can help neurologists confirm diagnoses when symptoms are ambiguous or when patients show an unusual presentation or poor response to standard treatments 1
• Patients should inform their doctor about all medications they're taking, as some drugs can interfere with results, and be aware of the procedure's requirements and potential risks, including exposure to a small amount of radiation 1.

Overall, the DatScan is a valuable tool in the diagnosis and differentiation of Parkinsonian syndromes, and its use can help guide treatment decisions and improve patient outcomes, as supported by the most recent and highest quality evidence available 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).

A DatScan is useful in the following situations:

• Suspected Parkinsonian syndromes (PS): to help diagnose and differentiate Parkinson's disease from other parkinsonian syndromes.
• Suspected dementia with Lewy bodies (DLB): to help diagnose and differentiate DLB from other forms of dementia. 2, 2, 2

From the Research

Clinical Scenarios for DatScan Use

DatScan can be useful in several clinical scenarios, including:

• Patients with early subtle symptoms of Parkinson's disease (PD) 3
• Patients with suboptimal response to levodopa 3
• Patients with prominent action tremor 3
• Patients with drug-induced parkinsonism 3, 4
• Patients with lower extremity or other less common parkinsonism clinical presentations 3
• Patients with suspected parkinsonian syndromes, such as essential tremor (ET) 5
• Patients with equivocal signs and symptoms of parkinsonism 6

Diagnostic Utility

DatScan imaging can help determine if nigrostriatal dopaminergic degeneration (NSDD) is present, which can be useful in:

• Differentiating between PD and other non-degenerative parkinsonian disorders, such as essential tremor and dystonic tremor 7
• Detecting presynaptic dopaminergic deficit in early disease 7
• Providing prognostic value for disease progression 7

Limitations

DatScan imaging has limitations, including:

• Limited value in differentiating among degenerative causes of parkinsonism 7
• False negative scans can occur, highlighting the need for clinical follow-up 7
• Clinical assessment remains the most important aspect in evaluating patients with suspected parkinsonism 7, 4