Dopamine D2 receptor imaging with SPECT using IBZM in 16 patients with Parkinson disease.

The striatal D2 receptor was investigated for variability of behavior in 16 patients with Parkinson disease by means of SPECT using 123I-IBZM, a recently synthesized radioligand with high affinity and specificity for this type of receptor. All the patients underwent routine laboratory tests, EEG and cranial CT scanning as well as SPECT. To ensure accurate clinical assessment we used the Hoehn and Yahr, and Webster scales, NUDS and Mini Mental State examination. Our preliminary data indicate: increased uptake by the striatal dopamine receptor in untreated patients with early PD compared with controls (striatum/cerebellum ratio of 1.77 +/- 0.12 vs 1.59 +/- 0.13); a slight but significant lowering of D2 receptor binding when L-Dopa is started (1.49 +/- 0.09); low D2 uptake values in the more severely affected patients; absence of asymmetries in hemiparkinsonism.