Single-Photon Emission Computed Tomography (SPECT)

Single Photon Emission Computed Tomography (SPECT) is a neuroimaging technique that uses a combination of computed tomography (CT) and a radioactive material (tracer) to measure regional cerebral blood flow in the brain. SPECT are typically ordered to look for areas of hypoperfusion in the brain.

• SPECT is a nuclear imaging modality that measures radioactivity of gamma rays emitted from radioactive compounds bound to tracers.

• SPECT is often ordered to look for regional changes in blood flow, which may suggest and underlying neurodegenerative etiology.

• DAT-SPECT, or 123I-ioflupane single-photon emission computed tomography (SPECT) assesses DAT uptake in the basal ganglia in vivo.
• By binding to the DAT, 123I-ioflupane allows imaging of the presynaptic terminals in the brain.
• DAT scans are particularly good at differentiating Dementia with Lewy Bodies from Alzheimer's Dementia
  • This is because there is greater reduction of dopamine terminals in the striatum (a cluster of neurons in the subcortical basal ganglia) in DLB, compared to their relative preservation in Alzheimer's.
  • Note that DAT imaging can be abnormal in other neurodegenerative disorders where dopaminergic transmission is affected, including frontotemporal dementia (FTD), corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), and multiple system atrophy (MSA).^[1]

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