Anatomical biomarker is missing link in Parkinson’s progression

Visualization of Parkinson’s disease (PD) development may now be possible by identifying dopaminergic nigrosomes, or the lack thereof, according to a study published Aug. 6 in Neurology.

Researchers including Penny A. Gowland, PhD, a physics professor from the Sir Peter Magnetic Resonance Centre at University of Nottingham in Nottingham, U.K., have developed an MR technique utilizing powerful 7T scanners that bring to light the oval shaped nigrosome 1, a substructure of the substantia nigra pars compacta involved in dopamine production. When this area goes dark, Parkinson’s is apparent. This study continues previous research at the center that led to the discovery of the marker, which tips off the earliest declines in dopaminergic cells, the hallmark of PD.

“Many MRI studies have reported [PD]-associated changes in the substantia nigra (SN),” wrote Gowland et al. “However, delineating the boundaries and assessing neurodegeneration in the SN remains challenging. Recently developed ultra-high-field MRI systems produce very high spatial resolution T2-weighted images providing detailed SN morphologic information. Correlation of high-resolution MRI data and histology may enable a more precise definition of the boundaries and substructures of the SN in vivo, and hence a more accurate demonstration of PD pathology.”

For this study, the post-mortem midbrains of three subjects, two healthy controls and one with a Parkinson’s diagnosis, underwent T2-weighted neuroimaging with a 7T MR system. Once nigrosome 1 was identified, in vivo imaging of 10 additional patients with Parkinson’s and eight matched healthy controls was performed to verify if the lack of visible nigrosome 1 correlated with disease progression. MR results showed that this area was hyperintense in healthy controls and consistently hypointense in Parkinson’s patients.

“This study identifies the substructure of the SN that is visible on 7 T T2-weighted images as nigrosome 1,” wrote the authors. “This feature is not observed in patients with PD, suggesting that it could potentially provide a simple, sensitive, and specific diagnostic tool for PD, but future longitudinal, quantitative studies are needed to show whether it can provide a disease progression biomarker.”