Susceptibility-weighted MR imaging (SWI) of basal ganglia iron deposition in the early and advanced stages of Parkinson's disease

Abstract

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease and the first one among the nosological entities of parkinsonism. Susceptibility-weighted imaging (SWI), magnetic resonance imaging (MRI) pulse sequence, which allows the in vivo estimation of the values of iron deposition in different areas of the brain, is a potential technique for the early diagnosis of PD and for the study of the pathogenesis of its complications.Objective: to compare the values of iron deposition in the basal ganglia in Stages II and III PD and to determine the relationship of clinical findings to the level of iron deposition according to the SWI findings.Patients and methods. Twenty-four patients with Hoehn and Yahr Stages II (n=24) and III (n=12) PD were examined. All the patients underwent brain MRI on a Siemens TrioTim (3T) MRI scanner by using pulse sequences T1, T2, SWI and subsequently quantifying the iron deposition (SPIN software). The accumulation of iron is visualized as an area of reduced signal intensity on SWI, and its estimation in accordance with the SPIN program has accordingly a smaller value. The regions of interest on both sides were the dentate nucleus, substantia nigra, red nucleus, putamen, globus pallidus, and head of the caudate nucleus. The examination protocol also included tests using the following scales: the Unified Parkinson's Disease Rating Scale (UPDRS), the Mini-Mental State Examination (MMSE), Frontal Assessment Batter (FAB), Freezing of Gait (FOG), Gait and Balance Scale (GABS), the Epworth Daytime Sleepiness Scale, the Parkinson's Disease Quality of Life Questionnaire (PDQ), the Beck Depression Inventory, and the Clock-Drawing Test.Results and discussion. The investigators found significant (p<0.05) correlations between the clinical picture and the level of iron deposition in the regions of interest in patients with Stage II PD: FOG – left caudate nucleus (r=-0.94); GABS – left caudate nucleus (r=-0.94); and in patients with stage III of the disease: UPDRS (full) – left red nucleus (r=-0.82), right globus pallidus (r=-0,80), left putamen (r=-0,96); UPDRS (Section 2) – left red nucleus (r=-0.77), left globus pallidus (r=-0.84); UPDRS (Section 3) – right putamen (r=-0,85), right globus pallidus (r=-0.78), left globus pallidus (r=-0,92); FOG – left globus pallidus (r=-0.81); GABS – left red nucleus (r=-0.96), left putamen (r=0.82), right putamen (r=-0.89), left globus pallidus (r=-0.82), right globus pallidus (r=-0.85), left caudate nucleus (r=-0.82), right caudate nucleus (r=-0.89); Beck Depression Inventory – right substantia nigra (r=-0.82).Conclusion. SWI measurement of the values of iron deposition in the structures of the extrapyramidal system in PD provides an additional insight into the pathological processes occurring in them.