Objective To measure changes in the basal ganglia volume, characteristics of neuromelanin in substantia nigra-1 and iron deposition using susceptibility-weighted imaging (SWI) in Parkinson's disease (PD) patients with freezing of gait at different stages, and to explore their value in evaluating these stages.

Methods A total of 178 PD patients with freezing of gait were enrolled. According to Hoehn-Yahr stage, the patients were divided into stage Ⅰ to Ⅱ group (112 cases) and divided into stage Ⅲ to Ⅴ group (66 cases). Additionally, 70 healthy volunteers undergoing routine physical examinations were randomly selected as control group. SWI was used to measure basal ganglia volumes (globus pallidus, putamen and caudate nucleus), disappearance rate of substantia nigra-1 (including bilateral display, unilateral display and bilateral non-display), and iron deposition (phase shift values) among groups. Multivariate logistic regression analysis was conducted to identify imaging factors associated with different stages. Receiver operating characteristic (ROC) curve analysis was performed to calculate the area under the curve (AUC) for assessing the predictive performance of imaging factors.

Results The course of disease in stage Ⅲ to Ⅴ group was significantly longer, and the Parkinson's Comprehensive Assessment Scale (UPDRS) score was significantly higher than that in stage Ⅰ to Ⅱ group (P < 0.05). The volume of pallidum, putamen and caudate nucleus in stage Ⅰ to Ⅱ and stage Ⅲ to Ⅴ groups were significantly lower, and those in stage Ⅲ to Ⅴ group were significantly lower than that in stage Ⅰ to Ⅱ group (P < 0.05); the disappearance rate of substantia nigra-1 and the deposition amount of pallidum iron, putaminal iron as well as caudate iron in stage Ⅰ to Ⅱ and stage Ⅲ to Ⅴ groups were significantly higher, and those in stage Ⅲ to Ⅴ group were significantly higher than that in stage Ⅰ to Ⅱ group (P < 0.05). Logistic regression analysis indicated that decreased caudate nucleus volume (OR=1.856, 95%CI, 1.234 to 2.564, P < 0.001), disappearance of substantia nigra-1 (OR=2.235, 95%CI, 1.657 to 2.659, P < 0.001) and increased iron deposition in the globus pallidus (OR=1.562, 95%CI, 1.234 to 1.989, P < 0.001) were predictors of Hoehn-Yahr staging. ROC showed that the AUC of Hoehn-Yahr stage was 0.889 based on the combination of caudate volume, disappearance of substantia nigra-1 and deposition of pallidum.

Conclusion SWI is an important non-invasive imaging tool for assessing different stages in PD patients with freezing of gait. Caudate nucleus volume, substantia nigra-1 and iron deposition in the globus pallidus are key indicators for predicting Hoehn-Yahr staging.