Objective To investigate the gender differences of glucose metabolic network in brains of healthy adults at resting state by 18F-FDG PET.Methods A total of 204 dextromanual,healthy individuals (104 males,average age:(53.45±11.51) years;100 females,average age:(54.11±12.09) years) were enrolled from June 2011 to June 2016 to construct brain metabolic networks.The nodal and global parameters,including clustering coefficient (Cp),characteristic path length (Lp) and betweenness centrality (Cb),were analyzed by graph theory.Permutation test with 1 000 repetitions was used.Results The brain metabolic networks derived from 18F-FDG PET data were with small-world properties in both male group and female group.Compared with Cb in females,Cb in males was significantly reduced in left postcentral gyrus,right angular gyrus and left temporal pole/middle temporal gyrus (permutation test,all P<0.05);and it was increased in left amygdala,left precuneus,right temporal pole/middle temporal gyrus and left inferior temporal gyrus (permutation test,all P<0.05).Comparing with the females,the male group had higher Cp and longer absolute Lp but without significant difference (permutation test,all P>0.05).Conclusions There are gender-related differences of topological structure in whole-brain metabolic networks.Gender should be considered as a covariate while designing experiments,accounting for cerebral metabolic data from normal control and experimental patients as well as making clinical decisions.

Objective To explore the feasibility and application in quantifying the rabbit central nervous system by using magnetic resonance diffusion tensor imaging(DTI)sequences.Methods 12 normal New Zealand rabbits were used to scan the brain and spinal cord of rabbits by DTI sequence of 1.5T MR machine,and the normal apparent diffusion coefficient(ADC)and fractional anisotropy (FA)values were obtained in the different regions of the brain and every spinal segment of rabbits,to analyse the characteristics and regularity of numerical changes.Results The average ADC value in the brain of rabbits was (0.87±0.08)×10-3mm2/s,the average FA value was 0.23±0.09;the average ADC value in cervical spinal cord was (1.05±0.14)×10-3mm2/s,the average FA value was 0.55±0.08.The average ADC value in thoracic spinal cord was (1.14±0.12)×10-3mm2/s,and the average FA value was 0.57±0.06;the average ADC value in lumber spinal cord was (1.20±0.12)×10-3mm2/s,and the average FA value was 0.61±0.06.Conclusion FA average value in the brain is lower than that in spinal cord (P<0.001),the difference is related to the distribution of nerve fibers and physiological curvature of spine.ADC average value in the brain is lower than that in spinal cord(P<0.001),this is related to the volume of spinal canal and the peripheral structure of spinal cord.The difference of FA value in the brain and spinal cord is higher than ADC value.