DaT scan may spot aspiration, pneumonia risk with Parkinson’s
Dopamine activity in key brain region as way of noting swallowing difficulties
A dopamine transporter scan — an exam that visualizes dopaminergic neurons, the nerve cells that are affected in Parkinson’s disease — may help in predicting which patients are at risk of aspiration, when food or liquid enters the lungs instead of the stomach.
Dysphagia, which happens when Parkinson’s causes difficulty swallowing, can lead to aspiration and raises the risk of aspiration pneumonia, a potentially life-threatening complication.
“Our findings can help clinicians identify patients at risk of aspiration earlier, allowing for proactive referral for a detailed swallowing evaluation,” the researchers wrote in “Dopamine transporter imaging to predict the risk of aspiration in patients with Parkinson’s disease,” published in Parkinsonism & Related Disorders.
Aspiration pneumonia is due to food or liquid drawn into the lungs
Aspiration is a common cause of death in Parkinson’s, but current methods used to predict aspiration “are unsuitable for routine implementation owing to time constraints, cost, or insufficient predictive accuracy,” the researchers, all in Japan, wrote.
The team looked at whether a dopamine transporter (DaT) scan could help to more accurately predict patients at aspiration risk. A DaT scan uses single-photon emission computed tomography to track a radioactive tracer injected into the blood. When the tracer enters the brain, it binds to DaT, a protein that pumps dopamine in and out of neurons.
People with Parkinson’s usually have weak or no dopamine signaling in the striatum, a brain region responsible for motor control, and dopamine’s absence in this region results in Parkinson’s motor symptoms. As dysphagia arises in part from a loss of motor control, “the potential of reduced DaT imaging signals to predict aspiration in individual patients with [Parkinson’s disease] appears plausible,” the researchers wrote.
These scientists looked at the medical records of 87 adults with Parkinson’s (mean age, 64), who had a videofluoroscopic swallowing examination and, within the same year, a DaT scan at a hospital in Tokyo. Videofluoroscopy is a dynamic imaging technique that captures X-ray images in real time to visualize the swallowing process.
Lower dopamine activity seen on scan tied with higher aspiration risk
Patients had an average disease duration of 8.3 years, and 13 (14.9%) were found to have aspiration. Compared with those without aspiration, these patients had a lower striatal specific binding ratio (SBR), a measure from the DaT scan that shows dopamine activity in the brain.
Lower SBR values linked with a higher risk of aspiration. Aspiration risk was most accurately predicted by assessing the SBR of dopaminergic neurons in the less affected hemisphere of the brain, referred to as the “better side.”
This measure had a “high” specificity of 93% and a “moderate” sensitivity of 62% at a cutoff value of 2.03, the researchers wrote. Here, specificity refers to how well the DaT scan ruled out aspiration in patients who didn’t have it, while sensitivity refers to how well it identifies patients at risk of aspiration.
Findings suggest that a DaT scan could be useful in predicting aspiration due to Parkinson’s. “These findings are credible because aspiration was confirmed using [videofluoroscopy], the gold standard for evaluating swallowing,” the researchers wrote. By identifying patients at risk, clinicians can refer them for further evaluation.
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