Application of SWI in quantitative analysis of brain iron

Objective To analyze the distribution and change of brain iron with age and to evaluate the advantage and disadvantage of this quantitative analysis method.Methods SWI on 3.0T MR scanner was performed on 62 healthy subjects,which were divided into 5 groups according to the age for analysis of the change of signal with age.Results In phase image of SWI,detectable signal loss was observed in substantia nigra(SN),globus pallidus(GP),putamen(Pu),caudate nucleus(CA) and motor cortex(MC) at earlier age(6～7 years),while comparable later detection was revealed in red nucleus(RN) and dentate nucleus(9～10 years).Meanwhile,no signal loss was observed in posterior branch of internal capsule and optic radiation.An aggressive iron deposition was observed in RN,SN,GP,Pu,CA and MC before the age of 20,and a platform deposition reached afterward in RN,SN,CA,and MC.Prominent iron deposition was found in GP,RN,CA and SN.Conclusion SWI effectively presents the cerebral iron distribution and deposition.The foundation of SWI in brain iron quantitative analysis is that the paramagnetic ferritin causes the local magnetic field change,which produces corresponding phase change in phase image of SWI.