Objective To evaluate the pathological changes in grey matter nuclei of brain of Par-kinson's disease patients with freezing of gait using magnetic resonance diffusion kurtosis imaging(DKI)combined with amide proton transfer(APT)sequences.Methods A total of 92 Parkinson's disease patients were enrolled as observation group,including 42 patients with freezing of gait and 50 without freezing of gait.An additional 50 healthy individuals were enrolled as control group.All partic-ipants underwent brain scans using a 3.0T MRI system with conventional sequences,DKI and APT protocols.Post processing was performed to delineate regions of interest in bilateral substantia nigra,red nucleus,globus pallidus,caudate nucleus and putamen.DKI parameters included fractional ani-sotropy(FA),mean diffusivity(MD),mean kurtosis(MK),axial kurtosis(Ka)and kurtosis radial(Kr),and APT parameter was asymmetric magnetization transfer rate of amide protons(MTRasym).Results In the affected side of the observation group,MK and Kr values in the substantia nigra,red nucleus,globus pallidus,caudate nucleus and putamen were significantly higher than those in the control group(P＜0.05).In the observation group,MK values in the substantia nigra were significantly higher in patients with freezing of gait compared to those without(P＜0.05).MTRasym values in the affected substantia nigra,red nucleus,globus pallidus,caudate nucleus and putamen were also significantly elevated in the observation group compared to the control group(P＜0.05).MTRasym values in the affected substantia nigra were significantly higher in patients with freezing of gait than those without(P＜0.05).Receiver operating characteristic(ROC)curve analysis showed that MK,Kr and MTRasym values in the affected substantia nigra had significantly larger area under the curve(AUC)for diagnosing Parkinson's disease compared to other grey matter nuclei(P＜0.05).The AUC of the MK value of the substantia nigra on the affected side combined with MTRasym in di-agnosing frozen gait in the observation group was significantly larger than that of single index(P＜0.05).Conclusion Magnetic resonance DKI and APT sequences can provide more characteristics of pathological changes in brain gray matter nuclei associated with Parkinson's disease and frozen gait.Among them,the MK value of the affected substantia nigra combined with MTRasym has im-portant application potential in assisting the clinical diagnosis of Parkinson's disease with frozen gait.