Introduction Dopaminergic neuron loss in substantia nigra (SN) in patients with PD is associated with deposits of iron. Susceptibility weighted imaging (SWI) is a high-resolution MR-based imaging technique for quantifying iron depositions in vivo. SWI may be a robust biomarker for clinical characterization of PD.
Methods Forty-two patients with PD were studied with SWI imaging. Average phase shift (radians) and percentage iron deposition of the SN were analysed using SPIN software. SWI data were also compared between PD patients with early (4.0±0.5 PD duration) vs. established PD (7.7±1.9), and according to low (21.2±4.5) vs. high (41.3±8.7) UPDRS-III-assessed motor symptoms severity. Data were interrogated using analysis of covariance (age), relative to healthy controls, and using post hoc univariate tests.
Results PD patients had higher phase shift values (p<0.01) and iron deposition percentage (p<0.001) in the SN bilaterally, compared to healthy controls. Phase shift values were significantly higher in patients with established PD compared to those with early PD (p<0.05) and higher UPDRS-III motor scores (p<0.05).
Conclusions PD patients show higher levels of deposits of iron in SN compared to healthy controls, and increased iron levels in SN are associated with prolonged disease and increased motor disability