Substantia Nigra Volumetry with 3-T MRI in De Novo and Advanced Parkinson Disease.

Background: Magnetization transfer-prepared T1-weighted MRI can depict a hyperintense subregion of the substantia nigra involvedin the degeneration process of Parkinson disease. Purpose: To evaluate quantitative measurement of substantia nigra volume by using MRI to support clinical diagnosis and staging of Parkinson disease. Materials and Methods: In this prospective study, a high-spatial-resolution magnetization transfer-prepared T1-weighted volumetric sequence was performed with a 3-T MRI machine between January 2014 and October 2015 for participants with de novo Parkinson disease, advanced Parkinson disease, and healthy control participants. A reproducible semiautomatic quantification analysis method that entailed mesencephalic intensity as an internal reference was used for hyperintense substantia nigra volumetry normalized to intracranial volume. A general linear model with age and sex as covariates was used to compare the three groups. Results: Eighty participants were evaluated: 20 healthy control participants (mean age +/- standard deviation, 56 years +/- 11; 11women), 29 participants with de novo Parkinson disease (64 years +/- 10; 19 men), and 31 participants with advanced Parkinson disease (60 years +/- 9; 16 women). Volumetric measurement of hyperintense substantia nigra from magnetization transfer-prepared T1-weighted MRI helped differentiate healthy control participants from participants with advanced Parkinson disease (mean difference for ipsilateral side, 64 mm(3) +/- 14, P < .001; mean difference for contralateral side, 109 mm(3) +/- 14, P < .001) and helped distinguish healthy control participants from participants with de novo Parkinson disease (mean difference for ipsilateral side, 45 mm(3) +/- 15, P < .01; mean difference for contralateral side, 66 mm(3) +/- 15, P < .001) and participants with de novo Parkinson disease from those with advanced Parkinson disease (mean difference for ipsilateral side, 20 mm(3) +/- 13, P =.40; mean difference for contralateral side, 43 mm(3) +/- 13, P =.004). Conclusion: Magnetization transfer-prepared T1-weighted MRI volumetry of the substantia nigra helped differentiate the stages of Parkinson disease. (C) RSNA, 2020