Xinxin Zhao1, Hedi An2, Tian Liu3, Nan Shen2, Binshi Bo4, Zhuwei Zhang4, Pengfei Weng4, Meining Chen4, Mengchao Pei4, Yi Wang3,4, Dongya Huang2, and Jianqi Li4
1Shanghai Key Laboratory of Magnetic Resonance and Department of Physics, East China Normal University, Shanghai, China, People's Republic of, 2Dongfang Hospital Neural Medical Affiliated Tongji University, Shanghai, China, People's Republic of, 3Department of Radiology, Weill Medical College of Cornell University, New York, NY, United States, 4Department of physics, Shanghai Key Laboratory of Magnetic Resonance and Department of Physics, East China Normal University, Shanghai, China, People's Republic of
Synopsis
Quantitative
susceptibility mapping (QSM) provides excellent contrast of
iron-rich deep nuclei to quantify iron in the brains. Clinicians are interested
in using QSM to diagnose PD patients. QSM and R2* values were measured in the
whole substantia nigra in patients with PD and healthy controls. The
significant difference between PD patients and healthy controls in the
substantia nigra was found on QSM but not on R2* mapping.Purpose
The purpose of
this study was to quantify brain iron deposition in patients with Parkinson’s
disease using quantitative susceptibility mapping (QSM) and R2* mapping, and to
evaluate the sensitivity of both mapping methods in clinical diagnosis of
Parkinson's disease.
Materials and Methods
Twenty-nine
patients with idiopathic PD (67.9 ± 6.7 years old, 12 males and 17 females) and
twenty-five healthy controls (HC) (64.7 ± 8.3 years old, 11 males and 14 females) were studied on
a clinical 3T MRI system (Magnetom Trio Tim; Siemens Medical Solutions,
Erlangen, Germany) with a 12 channel matrix coil. The QSM images and R2* maps were
generated from processing the same three dimensional (3D) multi-echo
gradient-echo sequence with the following parameters: TR = 60ms, TE1 = 6.8ms,
ΔTE = 6.8ms, echoes number = 8, flip angle = 15˚, FOV = 240*180mm2,
in-plane resolution = 0.625*0.625mm2, slice thickness = 2mm, number
of slices = 96.
QSM images were reconstructed from the phase data using the
Morphology Enabled Dipole Inversion (MEDI) algorithm 1. Regions of
interest (ROIs) of the whole SN were drawn manually on the QSM images by two
researchers.
Two-tailed Pearson correlation analysis was used to analyze the
correlations of QSM and R2* values with the UPDRS-III score respectively, and
the correlation between whole mean values of two maps in both groups
respectively. Two-tailed t-test and an analysis of sensitivity and specificity
were applied to the mean values of QSM and R2* of two groups.
Results
The
substantia nigra in all R2* and QSM maps showed a high contrast to the
surrounding tissue. Fig.1 shows representative QSM maps and R2* maps of two
individuals, a 67 years old female healthy control subject and a 68 years old
female PD patient. A significant Pearson’s coefficient was found between
susceptibility and R2* values of the SN of both groups, with the regression of 0.71
(p<0.001, Fig.2) in HC group and 0.67 (p<0.001, Fig.3) in PD group,
respectively. The susceptibility values for the SN was significantly higher in
the patients with PD than in the HC (154.80±43.36ppb vs. 127.50±21.05ppb,
P=0.006, Fig.4). However, no significant difference was found for the R2* value
in the SN between two groups.
The receiver operating characteristic curves
(ROC) showed that the QSM had higher sensitivity to classify PD patients than
the R2* mapping, with the area under the curve was 0.68 and 0.51, respectively
(Fig. 5). The
UPDRS-III motor scores did not correlate with mean susceptibility or R2* values
in PD group.
Discussion and conclusion
The mean values of
QSM within the whole SN in patients with PD was significant higher than in
healthy controls. Furthermore, our ROC result showed QSM, compared to R2*, had
higher sensitivity to distinguish PD from controls. These results in the
current study are in good agreement with previous studies 2-5. No
significant correlation was found between QSM value and the UPDRS-III motor
scores, which is consistent with one recent study 2 but inconsistent
with another recent study 3.
Further investigation with detailed characterization of patients including
UPDRS-II, in addition to UPDRS-III, is needed to sort this out.
In summary, the significant difference between PD
patients and healthy controls in the substantia nigra was found on QSM but not
on R2* mapping. QSM provides a more accurate and sensitive MRI technology to
detect the pathologic changes in the substantia nigra of patients with PD.
Acknowledgements
This
study was supported in part by grants from The National Natural Science
Foundation of China (81271533).References
1.Liu T, Wisnieff C, Lou M, et al. Nonlinear formulation of the magnetic field to source relationship
for robust quantitative susceptibility mapping. Magnetic resonance in medicine. 2013; 69(2):467-476.
2.Guangwei Du M, PhD,Tian Liu, et al. Quantitative Susceptibility Mapping of the
Midbrain in Parkinson's Disease. Movement Disorders. 2015; 00.
3.He
N, Ling H, Ding B, et al. Region-specific disturbed iron distribution in early idiopathic Parkinson's
disease measured by quantitative susceptibility mapping. Human brain mapping. 2015.
4.Murakami Y, Kakeda S, Watanabe
K, et al. Usefulness of quantitative susceptibility mapping for the diagnosis of
Parkinson disease. AJNR American journal of neuroradiology. 2015; 36(6):1102-1108.
5.Barbosa JH, Santos AC, Tumas V, et al. Quantifying brain iron deposition in patients with
Parkinson's disease using quantitative susceptibility mapping, R2 and R2. Magn
Reson Imaging. 2015; 33(5):559-565.