A preliminary study on amide proton transfer MR imaging at 3.0 T of the substantia nigra and red nucleus in Parkinson disease

Objective: To explore the feasibility of amide proton transfer (APT) MR imaging to detect cerebral abnormality of the substantia nigra and red nucleus in patients with Parkinson disease (PD). Methods: Twenty-seven patients with PD and twenty-three age-matched healthy control subjects were recruited in this study. According to Hoehn&Yahr stages, PD group was divided into two subgroups: early-stage(n=14) and advanced-stage(n=13). PD with right limb onset were seen in 14 patients, and PD with left limb onset in 13 patients. All the PD patients and healthy controls underwent brain APT MR imaging. The magnetic resonance ratio asymmetry (MTRasym) values at 3.5 ppm of bilateral substantia nigra and red nucleus were measured on APT images. MTRasym (3.5 ppm) values of substantia nigra and red nucleus between PD patients and control subjects were compared with independent-samples t test. The difference of MTRasym (3.5 ppm) among normal controls, early-stage PD, and advanced-stage PD patients was assessed with one-way analysis of variance. Paired-samples t test was used to compare the difference of MTRasym (3.5 ppm) in substantia nigra and red nucleus between the side of onset and contralateral side in PD patients. Results: Compared to normal controls, MTRasym(3.5 ppm) values of substantia nigra significantly decreased in PD patients[(0.96±0.35)% vs. (1.20±0.39)% respectively, t= -2.093 P=0.039J. No significant differences in MTRasym (3.5 ppm) values of red nucleus were observed between normal controls and PD patients[(0.97 ±0.36)% vs. (1.09 ±0.38)% respectively, t= -1.148, P=0.254]. Significant differences in MTRasym(3.5ppm) values of these cerebral structures were observed among normal controls, early-stage PD and advanced-stage PD [substantia nigra (1.20±0.30)%, (1.09±0.32)% and (0.81 ±0.37)% respectively, F= 3.954, P=0.022; red nucleus (1.09±0.28)%, (1.21±0.35)% and (0.71±0.33)% respectively, P=7.563, P= 0.001]. MTRasym(3.5 ppm) in substantia nigra showed a consistently decreasing tendency from normal controls to early-stage PD, to advanced-stage PD. MTRasym(3.5 ppm) values of sides of onset and contralateral sides of substantia nigra and red nucleus in PD patients had no significant statistically difference (substantia nigra (0.93±0.33)% vs. (0.99±0.30)%, t= -0.660, P=0.515; red nucleus (1.01± 0.36)% vs. (0.93±0.29)%, t=0.545, P=0.590). Conclusions: APT MR imaging can show sensitively the difference of MTRasym (3.5 ppm) in substantia nigra and red nucleus between early PD patients and normal controls, Thus, APT is a useful tool to diagnose PD and monitor the disease progression.