Contralateral Posterior Putaminal ¹⁸F-Fluorodopa Uptake in Mild Stage Parkinson’s Disease: A PET/CT Study

Objective: Previous studies revealed that 18F-FDOPA uptake was significantly decreased in the subregions of striatum contralateral to the side with predominant symptoms and was helpful for improving the early diagnostic accuracy of PD. However, in these studies, more than half of the PD patients already have bilateral motor symptoms (mH stage≥2). This study was aimed to extend previous findings to a milder disease stage. Methods: Sixteen PD patients with only mild and unilateral motor symptoms (mH stage=1 and disease duration≤2 years) and 22 healthy controls were involved. Striatal 18F-FDOPA uptake was analyzed using a ratio approach. Results: The SORs in the subregions of the contralateral striatum, including caudate, anterior putamen and posterior putamen were significantly decreased in the mild stage PD patients. The SOR for the contralateral posterior putamen had the largest area under the receiver operating characteristic curve (0.963) and separated mild stage PD patients from healthy controls with a sensitivity of 93.75% and a specificity of 95.45% when the cut-off value of <2.160 was selected. Conclusion: These data indicate that contralateral posterior putaminal 18F-FDOPA uptake may represent a potential marker for early diagnosis of PD, especially in patients with only mild and unilateral motor symptoms.