Conventional MR Image And ³¹P-MRS Study In Myopathy

Objective:To analyze MRI, rest and dynamic 31P-MRS imaging characters of Facioscapulohumeral muscular dystrophy(FSHD),Limb girdle muscle dystroph(LGMD),Lipid storage myopathy(LSM),Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes(MELAS), and to identify 31P-MRS characteristics capable of enabling discrimination between different kinds of myopathy.Material and methods:37 myopathy patients and 17 volunteers (who were healthy, having no espacilly physical training) were all examined by MR examinations.After excluded 3 inflammatory myopathy,3 congenital myotonia,1 myasthenia gravis,1 intramuscularylipoma,4 children myopathy,25 patients included in our study, there were 6 Facioscapulohumeral muscular dystrophy (FSHD),6 Limb girdle muscle dystroph(LGMD),8 Lipid storage myopathy(L.SM)and 5 MELAS patient. MR examinations included spin echo sequence (axial T1-Weight image) and FRFSE (axial T2-Weight image), axial and coronal T2WI Fat saturation Sequence,rest and dynamic 31P-MRS on right musculus quadriceps fexoris.The value of PCr, PCr/ATP, Pi, Pi/ATP, PP, Pi/PCr, ADP, PH, Q/Qmax were calcuated by 31P-MRS.Dynamic 31P-MRS was also performed in all patients during 20 mins recovery after submaximal exercise. Using PCr and ADP to caculated the initial rate of PCr recovery (ViPCr),the rate constant of PCr resynthesis(KPCr) and the maximum aerobic capacity(Qmax).31P-MRS data were compared with the multiple sample variance analysis and the LSD-t test.Results:There were abnormal apparents in 19(76%) patients,included 7 muscular atrophy,12 muscular fat infiltration,7 muscular inflammation infiltration,3 muscular pseudohypertrophy.The characteristic appearants of LGMD included muscular pseudohypertrophy in anteriomedial region of thigh, muclular fat infiltration and atrophy in medial and retrahens region of thigh,gracilis,sartorius muscle, semimembranosus were free. The other muscular dieases groups shared the same abnormal image:muscular atrophy in medial region of thigh showed in B, C groups of patients; muscular fat infiltration in medial and retrahens region of thigh showed in A,B,C groups of patients;inflammation infiltration in retrahens region of thigh showed in B,C groups of patients. It was hard that only using MRI to differencial diagnose beween kinds of myopaty.The myopathy groups all showed decreased PCr,PCr/ATP,PP,Qmax,increased Pi/PCr,ADP,normal Pi,Pi/ATP.The characteristics of A groups were normal Q/Qmax,ViPCr,KPCr,PH value; the characteristics of B groups were increased PH value (t=3.13, P=0.032); the characteristics of C groups were increased KPCr (t=2.729, P=0.029); the characteristics of D groups were decreased Q/Qmax,ViPCr,KPCr (t=3.012,5.84,3.15, P=0.041,0.04,0.035, respectively)A,B groups of patients had same PCr,Qmax,ViPCr,KPCr,Q/Qmax. The rate constant of PCr resynthesis(KPCr) in C group was larger than A,B,D group (P=0.001,0.000,0.000, respectively),but Qmax less than A, B group.(P=0.007,0.366, respectively).Q/Qmax,ViPCrwere same in A,B,C groups,showed no statistic difference between each other. PCr,Qmax,KPCr,Q/Qmax,ViPCr were all obviously decreased in D group.Conclusions:Muscular morphology changes in MRI provided useful evidence in diagnosis myopathy,but less useful in differential diagnosis between each other.Rest and dynamic 31P-MRS can non-invasively detect the metabolic changes of myopathy Because of its capability of providing quantitative markers of mitochondrial,it can provide important information in diagnose various kinds of myopathy.