Different iron-deposition patterns of multiple system atrophy with predominant parkinsonism and idiopathetic Parkinson diseases demonstrated by phase-corrected susceptibility-weighted imaging

Abstract

Background and purpose: MSA-P and IPD have similar clinical presentations that may complicate accurate clinical diagnosis. Different iron-deposition patterns of those 2 diseases have been demonstrated in histopathology. The aim was to demonstrate the different iron-deposition patterns of MSA-P and IPD by using SWI phase images.

Materials and methods: Sixteen patients with IPD, 8 with MSA-P, and 44 age-matched healthy controls underwent SWI of brain. The different phase shifts as well as the high iron percentage of the area in several gray nuclei were statistically evaluated. The putamen was divided into 4 subregions for further analysis.

Results: Patients with MSA-P had significantly higher iron deposition in the putamen and PT compared with those with IPD (P < .05). Moreover, ROC curves indicated slightly more sensitivity in differentiating MSA-P from IPD, by means of the high-iron-deposition-percentage area than the average phase shift (putamen: AUC = 0.88 versus 0.78; PT: AUC = 0.79 versus 0.62). Moreover, the lower inner region of the putamen was the most valuable subregion in differentiating MSA-P from IPD among the 4 subregions (AUC = 0.92 and 0.91 for high-iron-percentage area and average phase shift, respectively).

Conclusions: Higher iron deposition in the putamen and PT may differentiate MSA-P from IPD, but the lower inner region of the putamen may be better compared with the PT and other subregions of the putamen. Moreover, the high iron percentage makes it possible to detect smaller increases in iron content more confidently in comparison with average phase shift.

Fig 1.

A−C, SWI high-passed filtered-phase images show regions of interest: 1 = SN, 2 = RN, 3 = CN, 4 = putamen, 5 = GP, 6 = TH, 7 = PT. D, Highlighted region indicates the high-iron-deposition area in the SN.

Fig 2.

A−C, The patient with MSA-P (C) has higher iron deposition in the putamen (white arrow) and PT (black arrow) rather than the control (A) and the patient with IPD (B). D, Four subregions of the putamen: 1 = upper inner region, 2 = upper outer region, 3 = lower inner region, 4 = lower outer region.

Fig 3.

Plot of high iron percentage and phase shift for each brain region in MSA-P, IPD, and control groups. The asterisk indicates a significant difference between IPD and control groups; the number sign, a significant difference between MSA-P and control groups; the dot, a significant difference between MSA-P and IPD (P < .05, Student-Newman-Keuls test).

Fig 4.

The AUC for iron depositions in 7 deep gray nuclei estimated by 2 methods is intuitively demonstrated in the differentiation of MSA-P from IPD.

Fig 5.

The AUC for iron depositions in 4 subregions of the putamen estimated by 2 methods is intuitively demonstrated in the differentiation of MSA-P from IPD. A, Average phase shift. B, High iron percentage.