Existing studies regarding Parkinson’s disease classification.

Note: sMRI = structural magnetic resonance imaging, fMRI = functional magnetic resonance imaging, SPECT = single-photon emission computed tomography, PCA = principal component analysis, SVM = support vector machine, ALFF = amplitude of low-frequency fluctuations, ReHo = regional homogeneity, RFCS = regional functional connectivity strength, GM = gray matter, WM = white matter, CSF = cerebrospinal fluid, ICA = independent component analysis, BG = basal ganglia. Existing studies regarding Parkinson’s disease classification.