Objective:To explore the feasibility of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in assessing the microcirculatory perfusion of skeletal muscle in rabbit limbs in the early stage after high-voltage electric burns.Methods:This study was an experimental study. Thirty-two male big ear white rabbits aged 6-8 months were assigned into electric burn group of 20 rabbits with high-voltage electric burns in the right lower limb and control group of 12 rabbits with sham injury in the right lower limb using the random number table method. At 0.5, 24.0, 48.0, and 72.0 h post injury, the lower limbs of rabbits in the two groups underwent axial fast spin echo T1-weighted imaging, fast spin echo T2-weighted imaging, and DCE-MRI examination. A reference region-based hemodynamic model was applied to obtain the blood perfusion parameters of skeletal muscle in the injured limbs, including the volume transfer constant K trans value and rate constant K ep value. The skeletal muscle tissue from the electric burn group of rabbits at 0.5, 24.0, 48.0, and 72.0 h post injury and the control group of rabbits at 0.5 h post injury was harvested for immunohistochemical staining to observe the microvascular changes and calculate the microvascular density (MVD). The correlation between the K trans and K ep values and the MVD of skeletal muscle tissue in electric burn group of rabbits at 0.5-72.0 h post injury was analyzed. The number of samples was 5 in the electric burn group, and the number of samples was 3 in the control burn group. Results:From 0.5-72.0 h post injury, the K trans and K ep values in skeletal muscle tissue of electric burn group of rabbits exhibited the trends of increase first and decrease then, both of which reached peak values at 24.0 h post injury. The K trans values at 0.5, 24.0, 48.0, and 72.0 h post injury (with t values of -15.77, -14.91, -40.35, and -40.25, respectively, P<0.05) and the K ep values at 0.5, 24.0, and 48.0 h post injury (with t values of -5.39, -6.82, and -6.83, respectively, P<0.05) in skeletal muscle tissue in electric burn group of rabbits were significantly higher than those in control group. The MVD in skeletal muscle tissue in control group of rabbits at 0.5 h post injury and in electric burn group of rabbits at 0.5, 24.0, 48.0, and 72.0 h post injury was (24.7±3.5), (21.8±2.2), (40.8±9.1), (16.4±2.4), and (9.8±0.8) per mm2, respectively. The MVD in skeletal muscle tissue in electric burn group of rabbits at 24.0 h post injury was significantly higher than that in control group at 0.5 h post injury ( t=2.89, P<0.05), and the MVD in skeletal muscle tissue at 48.0 and 72.0 h post injury was significantly lower than that in control group at 0.5 h post injury (with t values of 4.01 and 9.52, respectively, P<0.05). The K trans and K ep values of skeletal muscle tissue in rabbits in electric burn group were significantly positively correlated with microvascular density at 0.5 to 72.0 h post injury (with both r values of 0.95, P<0.05). Conclusions:The quantitative perfusion parameters K trans and K ep values of DCE-MRI can effectively reflect the microcirculatory perfusion changes of skeletal muscle in rabbit limbs in the early stage after high-voltage electric burns.

Objective:To explore the feasibility of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in assessing the microcirculatory perfusion of skeletal muscle in rabbit limbs in the early stage after high-voltage electric burns.Methods:This study was an experimental study. Thirty-two male big ear white rabbits aged 6-8 months were assigned into electric burn group of 20 rabbits with high-voltage electric burns in the right lower limb and control group of 12 rabbits with sham injury in the right lower limb using the random number table method. At 0.5, 24.0, 48.0, and 72.0 h post injury, the lower limbs of rabbits in the two groups underwent axial fast spin echo T1-weighted imaging, fast spin echo T2-weighted imaging, and DCE-MRI examination. A reference region-based hemodynamic model was applied to obtain the blood perfusion parameters of skeletal muscle in the injured limbs, including the volume transfer constant K trans value and rate constant K ep value. The skeletal muscle tissue from the electric burn group of rabbits at 0.5, 24.0, 48.0, and 72.0 h post injury and the control group of rabbits at 0.5 h post injury was harvested for immunohistochemical staining to observe the microvascular changes and calculate the microvascular density (MVD). The correlation between the K trans and K ep values and the MVD of skeletal muscle tissue in electric burn group of rabbits at 0.5-72.0 h post injury was analyzed. The number of samples was 5 in the electric burn group, and the number of samples was 3 in the control burn group. Results:From 0.5-72.0 h post injury, the K trans and K ep values in skeletal muscle tissue of electric burn group of rabbits exhibited the trends of increase first and decrease then, both of which reached peak values at 24.0 h post injury. The K trans values at 0.5, 24.0, 48.0, and 72.0 h post injury (with t values of -15.77, -14.91, -40.35, and -40.25, respectively, P<0.05) and the K ep values at 0.5, 24.0, and 48.0 h post injury (with t values of -5.39, -6.82, and -6.83, respectively, P<0.05) in skeletal muscle tissue in electric burn group of rabbits were significantly higher than those in control group. The MVD in skeletal muscle tissue in control group of rabbits at 0.5 h post injury and in electric burn group of rabbits at 0.5, 24.0, 48.0, and 72.0 h post injury was (24.7±3.5), (21.8±2.2), (40.8±9.1), (16.4±2.4), and (9.8±0.8) per mm2, respectively. The MVD in skeletal muscle tissue in electric burn group of rabbits at 24.0 h post injury was significantly higher than that in control group at 0.5 h post injury ( t=2.89, P<0.05), and the MVD in skeletal muscle tissue at 48.0 and 72.0 h post injury was significantly lower than that in control group at 0.5 h post injury (with t values of 4.01 and 9.52, respectively, P<0.05). The K trans and K ep values of skeletal muscle tissue in rabbits in electric burn group were significantly positively correlated with microvascular density at 0.5 to 72.0 h post injury (with both r values of 0.95, P<0.05). Conclusions:The quantitative perfusion parameters K trans and K ep values of DCE-MRI can effectively reflect the microcirculatory perfusion changes of skeletal muscle in rabbit limbs in the early stage after high-voltage electric burns.

Purpose To analyze the impact of clinicopatho-logical factors on residual tumor burden(RCB)grading system and Miller-Payne(MP)grading system in non-specific invasive breast cancer patients after neoadjuvant chemotherapy,and to explore the predictive value of the two grading systems for patient survival.Methods The clinical data of 177 patients with non-specific invasive breast cancer diagnosed by preoperative punc-ture and treated with neoadjuvant chemotherapy were retrospec-tively analyzed.The relationship of RCB grading system or MP grading system with disease free survival(DFS)and overall sur-vival(OS)was studied,and the value of the two systems in predicting prognosis was analyzed and compared.Results RCB grading was related to menstrual status,histological grading be-fore treatment,and lymph node metastasis after treatment;MP grading was related to pre-treatment histological grading,post-treatment lymph node metastasis,and pre-treatment molecular typing.By evaluating the ROC curve of recurrence and survival and comparing the area under curve(AUC),it was shown that RCB grading system was superior to MP grading system in pre-dicting recurrence and evaluating survival.Univariate and multi-variate survival analysis showed that pre-treatment clinical stag-ing,post-treatment lymph node metastasis,and RCB grading were independent factors for DFS.Pre-treatment clinical stag-ing,pre-treatment molecular typing,and RCB grading were in-dependent factors for OS,while MP grading was not an inde-pendent factor for DFS and OS.Conclusion RCB grading sys-tem has a higher predictive value for patient survival than MP grading system.RCB grading evaluation system is recommended as evaluation system for non-specific invasive breast cancer after neoadjuvant chemotherapy.

Objective To observe the value of apparent diffusion coefficient(ADC)for quantitatively evaluating progressive muscle injury of rabbit limbs in early stage of high-voltage electrical burn.Methods Twenty healthy adult rabbits were selected to establish limb high-voltage electrical burn models,which were randomly divided into 0.5,24,48 and 72 h groups(each n=5).MR diffusion weighted imaging(DWI)was collected for each group at 0.5,24,48 and 72 h after modeling,and the injured core muscles of the right hind limb and the normal muscles of the contralateral limb were taken for HE staining.The muscle's ADC,muscle fiber density(MFD)and muscle fiber diameter(D)values at the injured core of current entry and exit were compared,and those of normal muscle were also analyzed.The correlations of ADC values in injured core muscle and MFD or D values were investigated.Results There were significant differences of ADC values of injured core muscle at both the entry and exit and normal muscle,also of ADC values of injured core muscle at the entry and exit within each group(all P＜0.05).ADC values of injured core muscle at the entry and exit decreased with time going(all P＜0.05),but ADC values of normal muscle were not significantly different among different time points(P＞0.05).MFD values of injured core muscle at the entry and exit decreased with time going(all P＜0.05),while MFD values of the normal muscle,D values of the injured core muscle at the entry and exit and normal muscle were not significantly different among time points(all P＞0.05).ADC value of the injured core muscle was positively correlated with MFD value and negatively correlated with D value(rs=0.846,r=-0.507,both P＜0.05).Conclusion ADC could quantitatively evaluate the progressive muscle injury of rabbit limbs in early stage of high-voltage electrical burn.