Is R2* a New MRI Biomarker for the Progression of Parkinson’s Disease? A Longitudinal Follow-Up

Abstract

PurposeTo study changes of iron content in basal ganglia in Parkinson’s disease (PD) through a three-year longitudinal follow-up of the effective transverse relaxation rate R2*, a validated MRI marker of brain iron content which can be rapidly measured under clinical conditions.MethodsTwenty-seven PD patients and 26 controls were investigated by a first MRI (t0). Longitudinal analysis was conducted among the 18 controls and 14 PD patients who underwent a second MRI (t1) 3 years after. The imaging protocol consisted in 6 gradient echo images obtained at different echo-times for mapping R2*. Quantitative exploration of basal ganglia was performed by measuring the variation of R2* [R2*(t1) – R2*(t0)] in several regions of interest.ResultsDuring the three-year evolution of PD, R2* increased in Substantia nigra (SN) (by 10.2% in pars compacta, p = 0.001, and 8.1% in pars reticulata, p = 0.013) and in the caudal putamen (11.4%, p = 0.011), without significant change in controls. Furthermore, we showed a positive correlation between the variation of R2* and the worsening of motor symptoms of PD (p = 0.028).ConclusionSignificant variation of R2* was longitudinally observed in the SN and caudal putamen of patients with PD evolving over a three-year period, emphasizing its interest as a biomarker of disease progression. Our results suggest that R2* MRI follow-up could be an interesting tool for individual assessment of neurodegeneration due to PD, and also be useful for testing the efficiency of disease-modifying treatments.

The Presence and Role of Iron in Mild Traumatic Brain Injury: An Imaging Perspective

“…Several different techniques have been used to study other conditions that implicate abnormal iron deposition including AD and PD. MRI transverse relaxation rates R2 [42][43][44][45] and R2* 43,[46][47][48] correlate with brain iron concentration, although they are affected by tissue fluid content. Field dependent relaxation rate increase imaging (FDRI) 42,49,50 and quantitative susceptibility mapping (QSM) [51][52][53][54][55] are more recent advances in brain iron imaging.…”

Usefulness of Quantitative Susceptibility Mapping for the Diagnosis of Parkinson Disease

“…In addition, in a previous study, significant variation of R2* was longitudinally observed in the caudal putamen of patients with PD evolving during a 3-year period. 46 Therefore, additional longitudinal studies are needed to evaluate the relationship between the iron levels of the putamen and the severity of PD more comprehensively. Our retrospective study has some limitations.…”

Imaging in Parkinson's Disease

“…Over a 3-year follow-up, increased R2* in the substantia nigra correlated with the worsening of motor symptoms of PD, suggesting that R2* may be a biomarker of disease progression in PD (Ulla et al, 2013). Association between high R2* signal and LIDs has yielded inconsistent results either showing a positive (Bunzeck et al, 2013) or no correlations (Wieler, Gee, & Martin, 2015) between iron deposition and motor complications.…”