The Study Of Using Multimodal Radiologic Images To Evaluate The Musculoskeletal And Nerve Abnormalities In Metabolic Syndrome

Objective: After the super-pixel segmentation of lower extremities in Computer Tomography(CT),the aim is to evaluate the muscle fat infiltration and muscle fat distribution of lower extremities in Metabolic Syndrome(MS).Histogram analysis of the muscle and the muscle fat ratio parameters in CT images of lower extremities to assess the adipose tissue distribution.To explore the utilization of zero echo imaging(ZTE)sequence in the diagnosis of cortical bone by using CT images as diagnostic criteria.To evaluate the nerve structure of lumbosacral plexus,sciatic nerve,femoral nerve,muscle structure and fatty infiltration in abdominal muscle in MS patients with diabetes.Methods: The subjects who completed CT examination of both lower extremities with complete medical history and laboratory examinations were included in this study.The subjects in the MS group were the patients from out hospital with the MS diagnosis,the subjects in the control group were the patients with the physical examination and the negative results of the radiologic and laboratory examinations.The muscle and fat of different parts of the lower extremities were segmented by in-house developed software to obtain the volume of different components.The subjects finished the examination with the same machine and the same protocol,the region of interest(ROI)was delineated in the muscle of different locations,and histogram parameters were extracted and ratio parameters of muscle and fat in different parts.Patients diagnosed with MS and low back pain were examined by ZTE sequence after 3.0T conventional Magnetic Resonance Imaging(MRI)sequences.After the image was anonymized and randomized,the image quality and the quantitative and qualitative parameters of lumbar cortical morphology on CT,ZTE and conventional MRI images were evaluated by three radiologists independently,respectively.The agreement between readers and modalities were calculated.DTI,Q-Dixon and conventional sequences were performed in patients with MS and diabetes mellitus.The structural parameters of muscle fibers at the abdominal level and different fat components were evaluated.The structural and functional changes of lumbosacral plexus,sciatic nerve and femoral nerve were evaluated with DTI parameters.Results: Men had more muscle volume in lower extremities and less adipose tissue than women.The female subjects in MS group had more ectopic fat accumulation,less muscle content,and more Extramyocellular lipid(EMCL)in lower extremities(P < 0.001).The total fat content of the male in MS group is more than control group(P < 0.001),and the muscle mass did not decrease significantly.The decreased muscle fat ratio was observed in the MS group.The distribution of muscle CT value in MS group was mainly manifested in lower peak value(P = 0.041)and skewness value(P = 0.049),and the distribution frequency of low pixel value was higher.Univariate and multivariate logistic regression of MS showed that EMCL was one of the risk factors for MS.The performance of the radiologic model including the histogram parameters of thigh and abdomen was similar,and higher than that of the calf.The performance of ZTE in the diagnosis of cortical bone structure was similar to CT,and the agreement between CT and ZTE readers was higher than that between CT and conventional MRI sequence readers.FA value of S3 nerve root and bilateral femoral nerve was significantly lower than that of the control group(P < 0.05),and MD of bilateral L5 nerve root was higher than that of the control group(P = 0.002,P = 0.003).EMCL in psoas major muscle and bilateral multifidus muscle in the MS group was significantly higher in the control group,and the content of Intramyocellular lipid(IMCL)in left multifidus muscle was significantly increased.Conclusions: MS is often accompanied by ectopic fat deposition,and the changes of muscle and fat content are different in different genders.In female patients,the increase of Subcutaneous Adipose Tissue(SAT)and EMCL and the decreased muscle are mainly manifested,while in male patients,the increase of SAT is mainly manifested.The histogram parameters combined with fat and muscle content parameters have a high AUC value in the diagnosis of MS,and the middle thigh and abdomen can be used as the reference position for the analysis of muscle and fat content in the body.ZTE sequence allow the visualization of bone cortex and is better in qualitative and quantitative assessment of the cortical bone.It can be an alternative tool for CT assessment of lumbar spine bone morphology.The abnormal DTI parameters of sciatic nerve,femoral nerve,nerve roots and bilateral multifidus muscle indicated that the fiber structure was damaged.EMCL was significantly increased in the MS group,and the increase of EMCL and IMCL had more clinical significance than fat fraction and total fat in the diagnosis of MS.Part Ⅰ: Assessment of the distribution of the muscle and adipose in the lower extremities at the super-voxel level in CT imagesObjective: To evaluate the effect of MS on the distribution of muscle and fat components by super-pixel segmentation of CT images of lower extremities.Methods: All subjects included in this study completed CT imaging of lower extremities,and with complete medical history and laboratory examinations.The subjects in the MS group were the patients from out hospital with the MS diagnosis,the subjects in the control group were the patients with the physical examination and the negative results of the radiologic and laboratory examinations.The muscle and fat in different parts of the lower extremities were segmented by super-pixel using in-house developed software.The volume of different components of the lower extremities was obtained,mainly including SAT,EMCL and muscle volume.The patients were divided into two groups by gender and MS.Independent t test or Mann-Whitney U test,chi-square test and Fisher exact test were used to compare the quantitative and qualitative clinical indicators and imaging parameters between the groups.P < 0.05 was considered statistically significant.Results: 236 subjects were included,including 139 males(mean age 60.97±11.3)and 97 females(mean age 62.32±12.27).There was no difference in age,and 118 subjects met the diagnosis of MS.After analyzing the muscle fat content of different genders,it is concluded that men have more muscle content of lower extremities than women(P < 0.001),and women have more total fat content of lower extremities and fat content of different parts of lower extremities(P < 0.001).The female in MS group had more fat accumulation and less muscle content than the control group,and the EMCL in different parts of the case group was significantly increased compared(P < 0.05).The total fat content of the male MS group increased,but the muscle mass did not decrease significantly,and the EMCL content of the calf increased significantly.Conclusions: MS is usually accompanied by accumulation of SAT and EMCL and decreased muscle volume.The changes of skeletal muscle and fat content in different genders are also different.The increase of SAT and EMCL is more common in female patients,and the increase of SAT is more common in male patients,and the decrease of muscle in female is more obvious than that in male patients.Part Ⅱ: Histogram analysis of the muscle of lower extremities in Metabolic syndrome in CT imagesObjective: To evaluate the degree of muscle fat infiltration in lower extremities by using histogram analysis of CT images in patients with MS,and to measure muscle fat ratio parameters in different parts in patients with MS.Methods: The examination of the lower extremities with same machine and scanning protocol were included,subjects in the MS group were the patients from out hospital with the MS diagnosis,the subjects in the control group were the patients with the physical examination and the negative results of the radiologic and laboratory examinations.the muscle of the middle thigh,the middle calf and the middle L3 vertebra,SAT,EMCL and the area of Visceral Adipose Tissue(VAT)were measured.The histogram parameters of muscle regions in different locations were extracted.The clinical and imaging parameters of the subjects were calculated,and chronic history was recorded with binary variables;Demographic parameters;The content of SAT,muscle and EMCL in different parts of lower extremities and the ratio between them were measured.Independent t test or Mann-Whitney U test,chi-square test and Fisher exact test were used to compare the radiologic parameters and clinical indicators in different groups.With the status of MS as the dependent variable,the Receiver Operating characteristic Curve(ROC)was obtained after correction by using binary logistics regression analysis,the Area Under the receiver operating characteristic Curve(AUC)was calculated.P < 0.05 was considered statistically significant.Results: 47 subjects in MS and 48 controls met the diagnostic criteria.According to the statistics of histogram parameters,muscle and fat parameters in the lower extremities,the proportion of muscle and fat in the MS group was imbalanced,which was mainly manifested as an increase in the proportion of fat and a decrease in muscle.The EMCL content of the thigh in the MS group also increased.In terms of the statistics of histogram parameters,the distribution of muscle CT values in the case group was mainly manifested in reduced kurtosis values(P = 0.041),smaller skewness(P = 0.049),and higher frequency of distribution of low CT values in the histogram.EMCL is one of the important risk factors of MS.The results show that the radiologic model with the histogram parameters and content parameters of thigh and abdomen has similar performance and higher than that of calf model.Conclusions::The histogram parameters can be used to evaluate the muscle fat infiltration,the muscle fat ratio imbalance is related to MS,and the combination of fat and muscle content and histogram parameters of diagnostic model for MS is better.In the assessment of body composition for metabolic syndrome,both mid-thigh and abdomen can be used as reference locations.Part Ⅲ: The Feasibility of ZTE-MRI in the Evaluation of Lumbar Cortical Degeneration in Metabolic SyndromeObjective: To evaluate the lumbar cortical degeneration in MS patients by comparing the new sequence of Zero Echo Time(ZTE)with the conventional MRI sequence,and to explore the utilization of ZTE sequence in the diagnosis of cortical bone abnormality.Methods: Subjects with MS diagnosis and low back pain were recruited,who completed 3.0T conventional Magnetic Resonance Imaging(MRI)and ZTE scan,and underwent lumbar CT examination.Image quality and cortical morphology of lumbar vertebrae were evaluated quantitatively(axial orientation of facet joint,lateral recess)and qualitatively(osteophyte grade,vertebral facet joint osteoarthritis)on CT,ZTE and conventional MRI images.After image anonymization and randomization,three radiologists completed the evaluation independently.The agreement between readers and between different imaging modalities was calculated separately.P < 0.05 was considered statistically significant.Results: There were no significant differences between the imaging modalities in the morphological assessment of bone structures,including axial orientation(P = 0.444),Interarticular Distance(P = 0.444),and interarticular distance(P = 0.444).IAD(P = 0.381),lateral recess(P = 0.370),osteophyte grade(P = 0.052).In the measurement of foramendiameters,there was a statistical difference between conventional MRI and CT(P < 0.05),but there was no statistical difference between CT and ZTE.Cortical bone is more ambiguous than CT in the ZTE sequence,especially in cases of severe lumbar degeneration.The agreement between readers of CT and ZTE was higher than the agreement between readers of CT and conventional MRI.Conclusions: ZTE-MRI could offer more cortical bone details than conventional MRI images and might be a valid alternative to CT for lumbar osseous morphology assessment to some extent.Part Ⅳ: Q-Dixon and DTI in the Evaluation of Nerve and Muscle Fiber Structure and Fat Content of Muscle in Metabolic SyndromeObjective: To evaluate the early structural changes of lumbosacral plexus,sciatic nerve,femoral nerve and abdominal muscles in MS patients with diabetes by functional magnetic resonance imaging,so as to further understand the neuromuscular abnormalities in metabolic syndrome.Methods: MS patients with diabetes mellitus and matched controls were recruited for clinical evaluation,laboratory examinations,and MRI examinations including DTI,QDixon,and conventional sequences.DTI parameters of L3 level muscles and muscle fat fraction and content of different fat components in Q-Dixon were measured.The DTI parameters of lumbosacral plexus,sciatic nerve and femoral nerve were used to evaluate the structural and functional changes of nerve fibers.The clinical and radiologic parameters of were statistically analyzed respectively.Independent t test or Mann-Whitney U test were used for continuous variables,and chi-square test and Fisher exact test were used for categorical variables to compare radiologic parameters and clinical parameters of different groups.P < 0.05 was considered statistically significant.Results: The quantitative parameters of DTI of lumbosacral plexus nerve roots,bilateral sciatic nerve and femoral nerve were analyzed.FA of S3 nerve roots and bilateral femoral nerve were significantly lower than those of the control group(P < 0.05),and MD of bilateral L5 nerve roots were higher than the control group(P = 0.002,0.003).Statistically significant differences were found in bilateral L5 nerve roots in TRACE parameters(P < 0.05).According to the fat fraction of different muscle groups and different fat components,the EMCL content of psoas major and bilateral multifidus muscle in the MS group was lower,and the IMCL content of left multifidus muscle was also more than control groupConclusions: The DTI parameters of sciatic nerve,femoral nerve,part of nerve roots and bilateral multifidus muscle in MS patients suggest that the fiber structure were damaged.EMCL and IMCL were significantly increased in the MS group.EMCL and IMCL contents were more meaningful than fat fraction and total fat in the diagnosis of metabolic syndrome.