Preliminary Study Of The Brain In Patients With Amyotrophic Lateral Sclerosis By Using Susceptibility-weighted Imaging

PartⅠPreliminary Study of the Correlation between Phase Shift in Susceptibility-weighted Imaging and Regional Brain Iron ConcentrationPurpose:To investigate the relationship between the magnetic susceptibility of brain tissue and iron concentration in order to provide the basis for diagnosing brain disorders.Materials and Methods:Twenty-one normal volunteers(13 males and 8 females; age range 10～62 years;mean age 40.9±15.3 years)received conventional MRI and SWI examinations of the brain on a 3.0 T scanner.Phase shifts in correct phase images were measured,and compared with published values of regional brain iron concentration,including semioval center,precentral gyrus,frontal cortex,globus pallidus,caudate nucleus,and putamen.Results:the average phase shift value of the semioval center,precentral gyrus, frontal cortex,globus pallidus,caudate nucleus,and putamen,were-0.031±0.026, -0.114±0.023,-0.085±0.018,-0.343±0.227,-0.071±0.017,-0.216±0.089 respectively,and the corresponding regional iron concentration were 0.040±0.004(mg/g),0.044±0.008(mg/g),0.028±0.003(mg/g),0.204±0.023(mg/g), 0.043±0.008(mg/g),0.116±0.024(mg/g)respectively.Phase were correlated with brain iron concentration in precentral gyrus(R~2=0.609),frontal cortex(0.408), caudate nucleus(0.426),globus pallidus(0.243),putamen(0.488)(all P＜0.05),but not in white matter(R~2=0.103,P=0.157).The slope of the regression varied from -1.17 in the caudate nucleus and -4.94 in the globus pallidus.These results suggest that magnetic resonance phase reflects iron-induced differences in brain tissue susceptibility in gray matter.The lack of correlation in white matter may reflect important differences between gray and white matter in the cellular distribution and the metabolic functions of iron.Conclusions:These results suggest that magnetic resonance phase images reflect iron-induced differences in brain tissue susceptibility in gray matter.The lack of correlation in white matter may reflect important differences between gray and white matter in the cellular distribution and the metabolic functions of iron.PartⅡPreliminary Study of Susceptibility-weighted Imaging in Patients with ALSPurpose:To study the phase shift in gray matter in patients with amyotrophic lateral sclerosis(ALS)based on the quantitative measurement of healthy volunteers.Materials and Methods:20 patients(13 males and 7 females;age range 17～75 years,mean age 46.1±14.5 years;duration range 4～192 months,mean duration 41.2±57.1 months)with definite or probable ALS(defined by the diagnostic criteria of E1 Escorial World Federation of Neurology,and evaluated by Norris Scale and Amyotrophic Lateral Sclerosis Functional Rating Score)and 19 age and gender matched normal controls(11 males,8 females,age range 14～62 years, mean age 43.8±12.7 years)were enrolled.MRI was performed using a 3.0 T GE scanner.Phase shifts in gradient-echo images were measured,including bilateral precentral gyros,frontal cortex,caudate nucleus,globus pailidus,putamen,then compared with published values of regional age-induced iron concentration,Results:The average phase shift value of the precentral gyrus,frontal cortex, caudate nucleus,globus pallidus and putamen in ALS were-0.176±0.050,-0.089±0.023,-0.065±0.016,-0.336±0.191,-0.227±0.101 respectively,the corresponding regional age-induced iron concentration were 0.046±0.004(mg/g),0.029±0.002 (mg/g),0.045±0.004(mg/g),0.211±0.010(mg/g),0.124±0.015(mg/g)respectively. The average phase shift value of the precentral gyrus,frontal cortex,caudate nucleus,globus pallidus and putamen in controls were -0.119±0.016,-0.885±0.015,-0.079±0.018,-0.329±0.136 and -0.229±0.083,the corresponding regional age-induced iron concentration were 0.045±0.005(mg/g),0.028±0.002 (mg/g),0.045±0.005(mg/g),0.209±0.014(mg/g)and 0.017(mg/g).Phase shift values of precentral gyrus in ALS patients were lower than those of the control group(P＜0.05).Phase shift values of precentral gyrus,cadate nucleus,and putamen in ALS patients correlate with regional age-induced iron concentration with the published criteria.Conclusions:The differences between the two groups in the phase shift values in precentral gyrus indicate that the precentral gyrus in ALS patients have stronger susceptibility,and it possibly relates with the abnormal iron overload.The phase shifts in precentral gyrus in ALS patients correlate with the age-induced iron concentration.