Assessment Of Early Skeletal Muscle Myopathy With Contrast-enhanced Ultrasound In A Rabbit Model Of Diabetes Mellitus

Objective: To evaluate early skeletal muscl myopathy with contrast-enhanced ultrasound(CEUS)for quantitative assessment of muscular perfusion in diabetic rabbits.Methods: Sixteen male New Zealand white rabbits were randomly divided into two groups.The first group consisted of 11 rabbits treated with alloxan monohydrate(100 mg/kg);the second group consisted of 5 age-matched control animals.Baseline CEUS-parameters of calf muscle were previously obtained before conducting the diabetic model.Then,CEUS of the calf muscle was performed at 1month,2month and 3month after the establishment of type 1 diabetes model,respectively.Time-intensity curves were established in small artery,skeletal muscle tissue and small vein.CEUS parameters including arterial arrival time(AAT),arterial time to peak(ATTP),arterial peak intensity(API),venous arrival time(VAT),venous time to peak(VTTP),venous peak intensity(VPI),contrast transit time(CTT),muscular time to peak(MTTP),muscular peak intensity(MPI)and mean transit time(MTT).The CTT was calculated as the difference between contrast arrival time of artery and vein in the muscle.The MTT was estimated by the time difference between the respective 50% peak intensity of the time intensity curve of muscle tissue.Then,skeletal muscle samples were obtained using a 16-gauge automatic needle device for the morphologic observation under transmission electron microscope.At the end,the diabetic rabbits were divided into three groups according to their pathologic findings: mild myopathy group,moderately myopathy group and severe myopathy group.The changes of CEUS-parameters in diabetic and nondiabetic rabbits were evaluated.Results:1.General conditions: Type 1 diabetes mellitus were established in 9 rabbits of first group,and 2 died at 6 and 7 weeks.Most diabetic rabbits gained some body weight,but the gain was much less than the age-matched nondiabetic rabbits(P<0.05).Plasma levels of triglyceride,cholesterol,creatinine,urea nitrogen and lactate dehydrogenase were significantly higher in diabetic rabbits than in nondiabetic rabbits(P<0.05).2.CEUS analysis of diabetic and nondiabetic rabbits: The CTT,MTT and MPI values of the diabetic rabbits significantly changed over time compare with nondiabetic animals(P<0.05).There were no significant differences in the changes of ATTP?VTTP?MTTP?API and VPI over time between two groups(P>0.05).The CTT and MTT values were significantly higher in diabetic rabbits at 2 and 3 months compared with baseline and age-matched nondiabetic rabbits(P<0.05).The MPI values were significantly lower in diabetic rabbits than baseline and age-matched nondiabetic rabbits at 3 months(P<0.05).3.CEUS analysis of diabetic myopathy: There were significant differences of CTT and MTT among diabetic myopathy groups(P<0.05).No differences in the ATTP?VTTP?MTTP?API?VPI and MPI values were found among three groups(P>0.05).The CTT value was significantly higher in severe myopathy group than in mild group(P<0.05).The MTT values of both moderate and severe groups were significantly higher as compared to mild group(P<0.05).The CTT and MTT values is correlated with the severity of diabetic myopathy(P<0.05).Conclusion:1.Diabetic myopathy occurs in the early stage of diabetes,and aggravates gradually over time.2.The CTT and MTT values significantly increased over time,indicating the dysfunction of muscle microcirculation.3.The dysfunction of muscular microcirculation appears to correlate with the severity of myopathy.4.CEUS can quantify impaired muscle microcirculation,and is a valuable tool for assessment of skeletal muscle myopathy.