Imaging of D2 dopamine receptors of patients with Parkinson's disease using single photon emission computed tomography and iodobenzamide I 123.

OBJECTIVE

To test the usefulness of single photon emission computed tomography (SPECT) with iodobenzamide in imaging basal ganglia and to elucidate the postulated upward regulation of the striatal D2 dopamine receptors in patients with early Parkinson's disease.

DESIGN

Fourteen patients with Parkinson's disease and eight control subjects were investigated with SPECT using iodobenzamide labeled with iodine 123 as dopamine receptor ligand.

SETTING

Neurological outpatient service at a university hospital in Kuopio, Finland.

PATIENTS

Fourteen patients with recently diagnosed unilateral, unmedicated Parkinson's disease and eight healthy control subjects.

RESULTS

The SPECT images revealed high uptake of iodobenzamide in the basal ganglia. In the patient group, the accumulation was more intense and the iodobenzamide affinity rate was significantly higher in the striatum contralateral to the parkinsonian symptoms. Also, the basal ganglia-cerebellum ratio was higher in the contralateral hemisphere. In the control group, no significant side-to-side differences were observed.

CONCLUSION

Iodobenzamide with SPECT imaging is useful in evaluating patients with Parkinson's disease. The results also suggest compensatory D2 dopamine receptor upward regulation in the striatum of patients with early unmedicated Parkinson's disease.