| Nowadays,people's living habits and diet structure have undergone tremendous changes.Convenient transportation and people's own sedentary work styles lead to reduced exercise consumption.In addition,excessive food intake makes people's weight increase,and the proportion of obese people has surged,which has become a global health problem.Clinically,bariatric surgery is currently the most effective treatment for severe obesity,which can cause long-term significant and sustained weight loss.Neuroimaging studies have found that obesity causes abnormalities in brain function and structure,and bariatric surgery can significantly change brain function abnormalities caused by obesity while improving metabolism,eating behavior,and weight loss.Studies have shown that changes in brain structure are the material basis for changes in brain function,and there is a certain correlation between changes in brain function and changes in brain anatomy.Therefore,bariatric surgery can significantly reduce the weight of obese patients,and whether it can reverse the abnormal changes of brain structure caused by obesity,is a scientific problem worth exploring.Previous structural imaging studies only reported changes in brain gray/white matter density,and white matter skeleton caused by bariatric surgery at the whole brain level.The changes in cortical morphology and the changes of white matter fiber connections between cortical and subcortical brain areas caused by bariatric surgery have not been studied.The clarification of this scientific problem will provide imaging evidence for revealing changes in brain structure caused by bariatric surgery from the perspective of changes in cortical morphology and white matter fiber connection,thus helping to reveal the central regulation mechanism of bariatric surgery.It also provides clinical practice and theoretical basis for clinical intervention therapy and new drug research and development.In this paper,a 2 × 2 experimental design of group(obesity surgery group,control group)×time(preoperative,1 month after surgery)was used to recruit obese patients undergoing laparoscopic sleeve gastrectomy(LSG)and non-surgical control groups.T1 structural and diffusion magnetic resonance imaging scans were performed 1 month before and 1 month after surgery(corresponding time point of the control group).Based on surface-based morphometry and probabilistic tractography,repeated measures analysis of variance wasused to analyze the changes of brain gray matter structure and white matter fiber connection in obese patients caused by LSG surgery,and to explore the central regulation mechanism of bariatric surgery.In addition,based on the short structural changes of obese patients 1 month post-LSG surgery as a characteristic index,the siamese networks and K-nearest neighbor(KNN)algorithm were used to construct a classification prediction model for predicting the long-term weight loss effect of obese patients and to explore the effectiveness of cortical changes as imaging markers in predicting weight loss.(1)Firstly,22 obese patients who underwent LSG surgery were recruited as the operation group and 21 matched obese patients as the control group.For T1 structural imaging data,surface-based morphometry and subcortical volume measurement methods were used to analyze the changes in gray matter structure via LSG surgery.The study found that LSG surgery reduced cortical thickness in brain regions associated with the precuneus and increased cortical thickness in regions associated with executive-control(MOFC,VACC),emotion(VMPFC),interoception(insula),and visual processing(STG);and increased cortical volume in regions associated with somatosensory processing(left PostCen)and VACC;and the subcortical volume associated with reward(CAU).Furthermore,the correlation analysis between clinical measurement data and structural image data found that decreases in BMI were significantly correlated with changes in cortical thickness in the VMPFC/precuneus.These results indicate that LSG surgery caused changes in brain structural morphology(cortical thickness and volume)while reducing weight.These brain regions are closely related to executive control and self-referencing processing.(2)Secondly,obese patients had a significant reduction in high-calorie food cravings after surgery,suggesting that structural changes in brain regions associated with food reward processing may affect the processing of reward functions and thus change dietary behavior.Therefore,in this study,the morphological changes in gray matter and the reward-related areas of the MOFC,CAU and INS were selected as seed points to analyze the changes in white matter fiber connections induced by LSG.It was found that LSG surgery increased the FA value of white matter fiber connections between MOFC-CAU related to reward-driven regulation and MOFC-INS related to sensory-driven regulation.The decrease in BMI was negatively correlated with the increase in FA value of white matter fiber connections between MOFC-CAU.The correlation between the change in these fiber connections and the change in weight indicated that LSG reversed the abnormal whitematter fiber connections with weight loss.(3)Finally,using short-term structural cortical changes in obese patients as a characteristic index,the siamese networks and KNN algorithm were used to construct a classification prediction model to predict the weight loss effect after 6 months.The results showed that the classification accuracy rate reached 80.65%.This result indicated that structural cortical changes in obese patients could be used as an effective imaging marker to predict postoperative long-term weight loss.In this study,we found that LSG surgery reversed the abnormal changes in gray matter structure and white matter fiber connection caused by obesity with weight loss,and provided imaging evidence for revealing the central regulation mechanism of bariatric surgery.In addition,the preliminary attempt to predict the medium/long-term effect of weight loss through the imaging features of short-term structural cortical changes after surgery is helpful to screen patients with poor weight loss effect and provide effective information for timely intervention and treatment in the clinic. |
PDF Full Text Request