Correlation Study Of SWI Signal Values Of Deep Brain Gray Nucleus And Age In Volunteers

Purposes: To study the correlation of Susceptibility Weighted Imaging (SWI) signal values of deep brain gray nucleus (including substan- tia nigra, red nucleus, globus pallidus, putamen, caudate nucleus) and age in normal human brains and to evaluate the brain iron changes with advancing age on SWI signal values.Materials and methods: 171 cases of healthy adults(86 males and 85 females) were selected to perform MR examination, in which, none of the subjects had the history of neurological and psychotic diseases according to MRI and clinical results. Each subject gave a written consent for participation before the experiment. All of volunteers ranged from 20 to 69 years (mean 44.26 years), which were divided into five age groups in term of ten years: 20~29(31 cases),30~39(33 cases),40~49(35 cases),50~59(40 cases),60~69(32 cases).MRI Experiment scanning: GE Signa 1.5T echospeed MR/i scanner and 8-channel head coil were used. Firstly,transecting T2 WI was perfomed and its scan parameter included TR 4000ms,TE 102ms, slice thickness 2.0mm, no interval, matrix 256×160, fields of view 24 cm, NEX 1. During the experiment period, the SWI were performed using a both magnitude and phase images from a high-resolution, three-dimensional, fully velocity compensated gradient echo sequence, and its scan parameter: TR 50ms, TE 45ms, slice thickness 3.0mm, intervals 0mm, fields of view 24 cm, matrix 320×320, NEX 0.75, Bandwidth 31.25, Flip Angle:30°,Scan time: 338s. And then, raw data of SWI for every volunteer was sent to GE Advantage workstation 4.3 workshop and"Corrected phase"and"SWI-Negative Mask"images were reconstructed. The signal values of substantia nigra, red nucleus, globus pallidus, putamen, caudate nucleus on SWI were measured by manual measuring tools. The measurement was taken three times with variable oval areas. All the statistical data were displayed as Mean±SD. Different age groups SWI signal values were compared by using the one-way ANOVA. The relationship between SWI signal values of deep brain gray nucleus and age use linear correlation model. P value less than 0.05 indicated a statistically significant difference.Results:1. In 171 cases, the signal values of deep brain gray nucleus of SWI was lower than them in the deep gray matter in the same age group .2. SWI signal values of deep brain gray nucleus were no statistical difference beween male and female (P>0.05).3. In the 20~39 group, SWI signal values the low - to - high order were as follows: substantia nigra, globus pallidus, red nucleus, caudate nucleus, putamen. In the 40~69 group, SWI signal values the low - to - high order were as follows: substantia nigra, red nucleus, globus pallidus, putamen, caudate nucleus.The speed of brain iron deposit become slower during the period of 20~39 years, and increase rapidly after 40 years (especially red nucleus and putamen), while iron depoisit in substantia nigra and red nucleus became slower again after 60 years. 4. Obviously negative correlations between age and SWI signal values were shown in substantia nigra(r=-0.759), red nucleus(r=-0.875), putamen (r=-0.880) and caudate nucleus(r=-0.524), while weakly negative linear correlation was displayed in globus pallidus (r =-0.211).Conclusion:1. SWI intensity decreased with age in all deep gray matter areas. And the speed of brain iron deposit seemed to divided by 40 years old.2. There is no statistical difference beween male and female in the SWI signal values of all deep gray nucleus. Negative correlations were measured between SWI signal values and age in these gray nuleus.3. SWI have provided a new method to detect brain iron, and can quantitatively measure the anatomical localization and age-related iron concentration changes.