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Objective To investigate the value of intravoxel incoherent motion MR imaging (IVIM-MRI)on monitoring impairment of renal function in hydronephrosis.Methods Left hydronephrosis model of Healthy New-Zealand rabbits made by ureteral incomplete obstruction were scanned by IVIM-MRI at 4, 8, 12, and 16 weeks.The change of IVIM-MRI quantitative parameters (ADC values, D values, D* values, and f values) in left hydronephrosis kidney were observed.The correlation between these parameters and glomerular filtration rate (GFR) were evaluated.Results ADC values, D values, D* values and f values at cortex and medulla in left hydronephrosis model of rabbits decreased gradually in the progression of renal damage after 4, 8, 12, and 16 weeks.For D value, f value and ADC values, there was statistical significant difference among the group of 12 weeks, the group of 16 weeks, the control group, and the group of 4 weeks;statistical significant difference was also observed between the group of 8 weeks and the group of 16 weeks by LSD contrast.ADC values, D values, D* values, and f values were positively correlated to GFR at 4, 8, 12, and 16 weeks for left hydronephrosis model of rabbits.Conclusion IVIM-MRI could monitor impairment of renal function in hydronephrosis dynamically.
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Objective To analyze CT features and related factors of mediastinal lymphoma with necrosis in order to identify other mediastinal tumor with necrosis.Methods CT features were retrospectively reviewed and related factors of necrosis were analyzed in 37 cases of mediastinal lymphoma confirmed by pathology.Results 37 cases appeared as mediastinal masses,in which 25 cases were cross-regional growth of the mediastinum,1 1 cases in anterior mediastinum and 1 case in posterior mediastinum.The largest cross-sectional area of tumors was 1.6-129.6 cm2 ,in which there were 1 case (0-10)cm2 ,8 cases (10-25)cm2 ,10 cases (25-50)cm2 ,1 5 cases(50-100)cm2 and 3 cases >100 cm2 .24 cases had necrosis ,among which 23 cases were slight enhanced and 1 case was seriously enhanced.Necrosis of mediastinal lymphoma was related to the size and CT enhancement of tumor by the logistic regression analysis(P <0.05).Conclusion Mediastinal lymphoma with necrosis is common .The necrosis of mediastinal lymphoma is related to the size and CT enhancement.Slight CT enhancement is one of differential points between mediastinal lymphoma with necrosis and other mediastinal tumor.
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BACKGROUND:Magnetic resonance diffusion tensor imaging can display the dispersion changes of peripheral nerve injury and be used to conduct quantitative research, so it has good application prospects in displaying the nerve injury and regeneration. OBJECTIVE:To investigate the possibility of magnetic resonance diffusion tensor imaging of rabbit acute sciatic nerve traction injury, and to figure out the value of diffusion tensor parameters in the diagnosis of peripheral nerve injuries and to reveal the pathologic basis. METHODS:The right hind limb sciatic nerves of 32 New Zealand white rabbits were selected to make the regeneration and repair models, the left hind limb nerves as the sham-operation side. Diffusion tensor imaging examination of sciatic nerves were performed at 1 and 3 days, 1, 2, 3, 4, 6 and 8 weeks after operation with 1.5 T MRI. Fractional anisotropy and apparent diffusion coefficient were measured through diffusion tensor tracing reconstruction, and then the pathological examination was performed. RESULTS AND CONCLUSION:Diffusion tensor imaging revealed only the proximal nerve, injured nerve as wel as the middle of the distal nerve at 1 day after traction injury. At 1 week, the nerve of distal portion appeared thinner and shorter fiber bundle. At 2-6 weeks after operation, the fiber bundle was increased and thickened. At 8 weeks after operation, the distal nerve fibers had nearly restored to the level before injury. There was significant difference in the fractional anisotropy value of traction portion and distal portions between traction injury and sham-operation group at 1 day-8 weeks after operation (P<0.05). While there was significant difference in the fractional anisotropy value of proximal traction portion between traction injury and sham-operation group 1 day-1 week after operation (P<0.05). There were no significant differences in the apparent diffusion coefficient values between traction injury and sham-operation group at 1 day-8 weeks after operation. Fal of fractional anisotropy value in the early stage of nerve traction injury was the result of myelin sheath broke down and axonal disintegrated;recovery of fractional anisotropy value resulted from myelin sheath proliferated and myelin sheath grew slowly to mature. Diffusion tensor tracing can show the abnormal change of the sciatic nerve with traction injury in rabbit clearly and early, and the measurement of fractional anisotropy value can be used as the sensitive method to monitor the degeneration and regeneration after nerve traction injury.
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Objective To explore MRI features and diagnostic value of primary hepatocellular carcinoma(PHCC).Methods Onehundred and seventy-four patients which were diagnosed as PHCC by MRI were analyzed retrospectively,including signal intensity ofPHCC,pseudocapsules,the sign out of PHCC(such as the tumor thrombi in portal or hepatic vein,lymph nodule in abdomen),and therelationship between them and tumor patterns.The accurate and misdiagnostic rate of MRI in the cases of PHCC proved by pathology were analysed.Results The signal intensity of PHCC was mainly hypointense or slightly hypointense on T_1WI and slightly hyperintense on T_2WI.The accurate rate of MRI in diagnosis of PHCC was 91.42%.The appeared rate of unhomogeneous signal intense of PHCC on T_2WI,thetumor thrombi in portal or hepatic veins and the peudocapsules was of significance in statistics between different type of PHCC.Pseudocapsules were shown better on T_1WI than on T_2WI and fat suppression.Conclusion MRI signal intensity of PHCC is socharacteristic that it has improtant value in diagnosing PHCC.