Substantia nigra neuromelanin magnetic resonance imaging in de novo Parkinson's disease patients

Abstract

Neuromelanin-sensitive MRI techniques can discriminate PD patients from healthy individuals with high sensitivity and specificity. Our findings are consistent with recent findings showing that PD neuromelanin changes remain stable during the course of the disease.

Comparative Study of MRI Biomarkers in the Substantia Nigra to Discriminate Idiopathic Parkinson Disease

“…These observations are in agreement with previous studies and confirmed that NM imaging is sensitive and specific for detecting nigrostriatal damage in PD. 9,10,17,24 The combination of volume and signal loss slightly increased the diagnostic accuracy. 10 In our study, we found a significant increase in diffusivity and a decrease in FA in the 3T NM ROI in patients with PD, which is congruent with previous studies reporting FA reduction 2-4 and increases in RD 2 and MD.…”

“…9,10,17,24 The combination of volume and signal loss slightly increased the diagnostic accuracy. 10 In our study, we found a significant increase in diffusivity and a decrease in FA in the 3T NM ROI in patients with PD, which is congruent with previous studies reporting FA reduction 2-4 and increases in RD 2 and MD. 5 These changes may be explained by cell lossand microstructural damage-induced changes in cell morphology and density and the destruction of diffusion barriers.…”

“…2,3,19 Second, SN volume on NM-sensitive images is variable across studies, ranging from 128 to 370 mm 3 in HVs and from 96 to 215 mm 3 in PD. 7,10,15,17,24 These differences may be related to the scanner type, magnetic field strength, sequence parameters, image-processing methods, partial volume effect on 2D imaging, or ROI selection methods. 29 Within this context, qualitative measurements such as visual assessment of NM-sensitive images or DNH appear interesting.…”

“…Neuromelanin (NM), a by-product of dopamine that accumulates in dopaminergic neurons, has high signal intensity on T1-weighted spin-echo images due to its paramagnetic properties, 7,8 and several studies have shown reduced NM signal or volume in the SN in PD. 9,10 Because NM accumulates in the substantia nigra pars compacta, NM MR imaging is a promising technique in PD. 11 Histologic studies in PD have shown that depletion of dopaminergic neurons is most pronounced in the caudal and lateral regions of the substantia nigra pars compacta, called nigrosome-1.…”

Biomarkers of Parkinson's disease: recent insights, current challenges, and future prospects

“…83 Recent studies have suggested that neuromelanin decrease (whose paramagnetic properties result in high signal on specific T1-weighted magnetic resonance imaging [MRI]) in the SN and locus coeruleus of PD patients may differentiate between PD patients and healthy controls with high sensitivity and specificity. 84 For a research purpose, imaging studies may further contribute in the delineation of different PD phenotypes at diagnosis. A recent fMRI study demonstrated that the subtype-specific functional networks could discriminate among PD patients with TD and non-TD phenotypes and healthy controls.…”