SPECT imaging of the brain is used for gathering information on dopamine activity when it comes to monitoring patients with Parkinson’s disease. However, scientists have discovered the assumptions of SPECT imaging reflecting the number of dopamine neurons in the substantia nigra are not suitable for monitoring treatment research results.    

The loss of dopamine-producing neurons in the substantia nigra is one of the most substantial changes in the central nervous system in Parkinson’s disease.

“Low dopamine level in the brain is linked with the central motor symptoms of Parkinson’s disease, such as tremor or shaking, muscle stiffness and slowness of movements,” said Valtteri Kaasinen of the University of Turku in a statement.

The method of detecting decreased dopamine activity with SPECT imaging of the brain is used often in diagnosing Parkinson’s disease in Europe and the United States. However, this new study, published in Neurology, shows the correlation between the number of neurons and dopamine activity is not as straightforward.

Researchers found that post-mortem neuron numbers in the substantia nigra were caluculated for patients with Parkinson’s disease who had been examined with dopamine transporter SPECT before death. The amount of neurons cannot be calucuated during a patient’s lifetime because the substantia nigra is located deep within the midbrain where biopsy is impossible in vivo.