| Background: Brainage is the age of the brain according to the anatomical characteristics of the main structures in the brain.In the actual age-related neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease,brain age is an important biomarker for early diagnosis,and the occurrence of neurodegenerative diseases may be related to the deviation of brain anatomical structure and brain atrophy.At present,although many different magnetic resonance imaging(magneticresonanceimaging,MRI)techniques have been used to evaluate the changes of human brain with age,the progress of MRI research on specific brain regions in different brain age groups is slow,and there is no clear reference value range.Objective(s): The latest integrated magnetic resonance imaging(syntheticmagneticresonanceimaging,Sy MRI)technique is used to obtain the brain image data of normal adults of different ages,to delineate the reference ranges of T1 relaxation time,T2 relaxation time and proton density(protondensity,PD)in key brain regions,to evaluate the changes of relaxation values in different brain regions during brain aging,and to construct a brain aging prediction model.We will expand the application range of Sy MRI technology and obtain accurate data of many important brain regions in a very short scanning time(3min)for the first time,which has important clinical significance for understanding brain development in different age groups and early diagnosis of neurodegenerative diseases.Methods: We recruited 1000 volunteers(≥ 18 years old)from communities and universities,and finally included 943 subjects after exclusion criteria.All subjects were examined by Sy MRI at our research center from September 2020 to October2021.This study was approved by the Ethics Committee of Yunnan Cancer Hospital(Ethical approval No.: KYCS2021262).All participants were informed of the content and method of the trial and signed an informed consent form.1.After delineating the age according to the study design,the selected brain regions of interest were quantitatively measured in different subjects: the tissue values(T1,T2 and PD values)of the region of interest(regionofinterest,ROI)were selected and measured by the same observer.The details are as follows: ROI was manually placed in the following 17 positions,including cerebellar hemispheric cortex,pons,amygdala,hippocampal head,hippocampal caudate,temporal lobe,occipital lobe,frontal lobe,caudate nucleus,lentiform nucleus,dorsal thalamus,semicircular center,parietal lobe,precentral gyrus and postcentral gyrus on T1-weighted inversion recovery sequence.The symmetry measurements of bilateral cerebral hemispheres and cerebellar hemispheres were taken each time,and the average value was taken as the final measurement value of each brain region of interest.2.To analyze the relationship between brain tissue relaxation value and age,brain tissue relaxation value and sex.According to the characteristics of data distribution,the data set of brain tissue relaxation values of the subjects was divided into two groups: < 60 years old and ≥ 60 years old.The two groups of data were analyzed by Logistic regression,and the variables were selected according to the weight of related factors,and the brain age prediction model was established.Results: 943 subjects aged from 20 to 85 years old,357 males and 586 females.According to their age,they were divided into 6 groups: 350 in 20-30 years old group,70 in 30-40 years old group,110 in 40-60 years old group,170 in 50-60 years old group,132 in 60-70 years old group and 111 in ≥ 70 years old group.The tissue relaxation values of the same brain region were measured twice by the observers,keeping a good consistency(ICC > 0.75).We obtained the specific reference value ranges of different age groups and different brain regions,and found that there were differences in brain tissue relaxation values of the same age group and different sex.In the analysis of age and brain relaxation value,the high correlation between brain relaxation value and age was the T1 value and PD value of the center of semi-oval,and the T2 value of caudate nucleus and lentiform nucleus,respectively.At the same time,the T1 and PD values of semioval center increased with age,while the T2 values of caudate nucleus and lenticular nucleus decreased with age.Finally,we constructed seven brain age prediction models with high sensitivity and specificity,among which the combined model of T1,T2 and PD values was the best.The area,specificity and sensitivity under the training set curve were 0.959(95%confidence interval: 0.945-0.974),91.51% and 89.36%,respectively.In the verification set,the above indicators are 0.916(95%CI:0.882-0.951),89.24% and80.33%,respectively.Conclusion(s): This study provides the reference range of T1,T2 and PD values of different brain regions in different ages and healthy adults,and the relaxation values of some brain regions are different between sexes,which is helpful to provide new ideas for the diagnosis of brain diseases.The brain age model based on integrated magnetic resonance technique is helpful to determine brain age. |
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