The Application Of3.0T MR DTI And T2mapping In The Diagnosis Of Acute Ischemic Rhabdomyolysis Of Rabbits

Objective: To observe the dynamic changes and investigate the correspondingpathological basis of muscle injury of acute ischemic rhabdomyolysis of rabbits on3.0TMR DTI and T2mapping; to investigate the value of3.0T MR DTI and T2mapping in thediagnosis of acute ischemic rhabdomyolysis; to provide evidences for clinical applicationof MR DTI and T2mapping in disease evaluation of rhabdomyolysis.Materials and Methods: From30New Zealand white rabbits,2rabbits wererandomly chosen to be checked by DSA immediately and8hours later after modeling,proving the modeling method succesful. The rest were randomly assigned into5groups(n=6): group A(normal control group); group B(ischemia group for2hours); groupC(ischemia group for4hours); group D(ischemia group for6hours); group E(ischemiagroup for8hours). Group A,B,C and D underwent MRI, histopathological examinationand detection of apoptosis at each time point. But group E continually underwent MRIbefore ischemia and1~8hours after modeling,9times altogether, then, underwenthistopathological examination and detection of apoptosis after MRI. We carried out MRIby using GE Signa HDxt3.0T superconducting magnectic resonance scanner and singlechannel flex surface coil. We conducted axial T2WI-FS, T1WI, DTI and T2mapping. Weprocessed all the data of DTI and T2mapping in GE ADW4.4Image ProcessingWorkstation, measuring ADC, FA and T2value in the rectus femoris inside part of eachrabbit’s left hind limbs, and fiber tracking. Muscle tissues of the rectus femoris inside partof each rabbit’s left hind limbs were examined by means of routine HE staining anddetection of apoptosis (including TUNEL staining and measuring the expressing ofcaspase-3by Western blot). We analyzed the relation among imaging results, histologicalresults and results of apoptosis, studying the dynamic changes of muscle injury of acuteischemic rhabdomyolysis on MRI.Results: The signal intensity on T2WI-FS continually increased one hour after ischemia; the signal intensity on T1WI didn’t change significantly after ischemia; fromfiber tracking, we saw muscle fibers stiffer, quantitatively reduce and spread apart afterischemia; ADC value declined slowly one hour after ischemia, minimized four hours afterischemia, rised slowly seven hours after ischemia(P<0.05). FA value rised slowly one hourafter ischemia, peaked four hours after ischemia, declined slowly seven hours afterischemia(P<0.05). T2value rised slowly one hour after ischemia, peaked four hours afterischemia, declined slowly six hours after ischemia(P<0.05); from HE staining results, wesaw granular degeneration six hours after ischemia and myocytolysis eight hours afterischemia; ADC and T2value had middle relativity with apoptotic index(AI), and FA valuehad low relativity with AI; ADC, FA and T2value had middle relativity with Caspase-3level.Conclusion:1) ADC, FA and T2value can identify the course of the pathologicalchanges of acute ischemic rhabdomyolysis, timely, objectively and accurately, fibertracking can directly show the changes of fiber architecture of the damaged muscle. DTIand T2mapping can objectively and accurately show the position, extent, range of acuteischemic rhabdomyolysis.2) In acute stage (<8h) after rhabdomyolysis, ADC value ofdamaged muscle first decreases and then increases, FA and T2value first increase and thendecrease.3) T2WI-FS can show morphology changes of muscle injury in rhabdomyolysis,eliminating disturbances of fat.