Application Of The Muscles Around The Knee Magnetic Resonance Diffusion Tensor Imaging

ObjectiveDiffusion tensor imaging (DTI) with fibre tracking (FT) has been extensively used tocentral nervous system（white matter tract）and peripheral nervous system, because of itsunique superiority. However,3.0T MRI tractography used in muscle around the knee isless common and the scanning parameter is immature. The optimal b-value of DTI formuscles around the knee has not been reported.The purpose of our study was to assess theoptimal b-value and reconstruction parameters for DTI and fiber tractography of themuscles around the knee.Materials and MethodsFifteen healthy volunteers（7male，8females; mean age,25.5years） were performedconventional MRI and DTI of knee at3T MRI scanner. The conventional MRI includingcoronal T1WI, FS-T2WI, sagittal T2WI、PDWI and axial T1WI and DTI. DTI wasacquired at four different b-values （400,500,600,700s/mm2）. semimembranous muscle,medial vastus muscle and caput mediale musculi gastrocnemii were investigated in thisstudy. Apparent diffusion coefficient (ADC) map，exponent ADC (EADC) map，fractionalanisotropy (FA) map，fractional anisotropy (FA) color-coded map were reconstructed andADC, FA values were measured. Two radiology experts gave a level to every imaging withdouble blind methods, then compared the image quality. The mean values of image qualitywere statistically analyzed by SPSS.ResultsThe quality of fiber tract images of knee muscles were very different for differentb-values. The image quality with b-value500s/mm2was better than that of other b-values.Semimembranous muscle, medial vastus muscle and caput mediale musculi gastrocnemii was explicitly showed in dwi-map. The signal of medial vastus muscle was highest, andthat of semimembranous muscle, aput mediale musculi gastrocnemii was relatively low.The muscles around the knee could be explicitly tract with DTI. The mean ADC value ofsemimembranous muscle, medial vastus muscle and caput mediale musculi gastrocnemiiwas （1.569±0.122）×10-3s/mm2,（1.572±0.188）×10-3s/mm2,（1.600±0.139）×10-3s/mm2，FA vaule was0.245±0.038s/mm2,0.223±0.024s/mm2,0.258±0.030s/mm2,respectively.ConclusionIn conclusion, DTI of the muscles around the knee on3Tesla MR scanner could befeasible and500s/mm2was the optimal b value. DTI and fiber tracking could reflectdiffusion characteristics of muscles and provide more serviceable information for clinicaldiagnosis. ObjectiveTo assess the difference of DTI for muscles around knee between athlete andnon-athlete healthy men. The parameters of apparent diffusion coefficient (ADC) vaule,fractional anisotropy (FA) vaule of three muscles were calculated and compared. To studythe affect of athletics for water molecules diffusivity within human skeletal muscle.Materials and MethodsTwenty-six healthy male volunteers,12non-athlete men （mean age,26.8years）、14athletes (mean age,23.6years) were performed conventional MRI and DTI of knee at3TMRI scanner. The conventional MRI including coronal T1WI, FS-T2WI, sagittal T2WI、PDWI and axial T1WI, DTI. DTI was acquired at b-values500s/mm2.Apparent diffusioncoefficient (ADC) map，exponent ADC (EADC) map，fractional anisotropy (FA) map，fractional anisotropy (FA) color-coded map were reconstructed and ADC values, FA valueswere measured. All examinations were performed on Achieve3.0T MRI scanner (PhilipsMedical Systems). The following parameters were used for fibre tracking: Minimum FA=0.15; Minimum fibre length=10mm; Angle Change (deg)=15. We used the anatomicalfusion with the axial T1sequences to estimate the relevance of our reconstructions. Threemuscles were investigated in this study: semimembranous muscle, medial vastus muscleand caput mediale musculi gastrocnemii. The parameters were statistically analyzed bySPSS16.0.ResultsThere were differences both ADC values and FA values among semimembranousmuscle, medial vastus muscle and caput mediale musculi gastrocnemii between athlete andnon-athlete men. For non-athlete men, The mean ADC value of semimembranous muscle,medial vastus muscle and caput mediale musculi gastrocnemii was （1.567±0.071）×10-3，（1.608±0.147）×10-3,（1.615±0.148）×10-3, FA vaule was0.248±0.020,0.221±0.016,1.615±0.148, respectively. For the athlete, the mean ADC value was （1.703±0.088）×10-3,（1.489±0.123）×10-3,（1.652±0.100）×10-3, FA value was0.213±0.012,0.210±0.012,0.246±0.020, respectively. For the non-athlete men, there was no statistically difference of ADC vaule among the three muscles. Significant difference was found in FA valuebetween medial vastus muscle and semimembranous muscle, caput mediale musculigastrocnemii. For the athlete, there was statistically different of ADC vaule betweenmedial vastus muscle and semimembranous muscle, caput mediale musculi gastrocnemii.There was also statistically difference of FA vaule between caput mediale musculigastrocnemii and semimembranous muscle, medial vastus muscle. For two groups, theADC value and FA value was significant difference for semimembranous muscle andmedial vastus muscle, while there was no statistical difference for caput mediale musculigastrocnemii.ConclusionAthletics can affect the structure of muscles around knee. DTI can sensitively reflectwater diffusivity within muscles, which indirectly demonstrated that there was differencebetween the structure of muscles. DTI and fiber tracking has promising prospect fordiagnosis of muscles disease.