Single photon emission computed tomography

What is SPECT?

Single-photon emission computed tomography (SPECT) is a nuclear based imaging technique that uses radioactive tracers to visualise functional brain activity. SPECT imaging is frequently used in combination with anatomical imaging such as computed tomography (CT) or structural magnetic resonance imaging (MRI). The radioisotope tracers are coupled with a biological molecule such as glucose, which is used during cellular metabolism and can be used to highlight areas with changes in metabolic activity. Functional brain activity has been investigated in people with schizophrenia compared to people without schizophrenia to identify regions of increased or decreased metabolic function or blood flow.

What is the evidence for SPECT brain functioning?

Moderate to high quality evidence suggests a large effect of increased striatal presynaptic dopamine function, and a small effect of increased striatal receptor availability in people with schizophrenia compared to controls. There are no difference in striatal dopamine transporter levels. Moderate quality evidence suggests no differences in D2/D3 receptor availability in the thalamus and temporal cortex of unmedicated people with schizophrenia compared to controls. Moderate to low quality evidence also suggests no differences in D2/D3 receptor availability in the substantia nigra.

Moderate to high quality evidence suggests significant reductions in functional activity in the whole brain of schizophrenia patients compared to healthy controls. During cognitive tasks and rest periods, there is a medium to large effect of reduced functional activity in bilateral frontal lobes. Moderate quality evidence suggests increased functional activity in the left temporal lobe during cognitive tasks, but no differences between patients and controls during rest periods.

Moderate to low quality evidence suggests there are associations between dopamine receptor occupancy and clinical improvements following treatment with antipsychotic medications. There is greatest dopamine D2 receptor occupancy with haloperidol (91.9%), then risperidone, olanzapine, clozapine, quetiapine, aripiprazole, ziprasidone, and then amisulpride (85%). First generation antipsychotics in general are associated with higher receptor occupancy in the striatum and temporal cortex than second generation antipsychotics.

March 2019

Last updated at: 2:42 am, 29th November 2019
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NeuRA Libraries

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