| Objective: To evaluate the correlation of ADC values with Fuhrman grading ofT1b clear cell renal cell carcinoma（CCRCC） for predicting the pathological grading andhelping clinicians to choose the appropriate operation program preoperatively.Methods: During December2010to February2012in our hospital,30patients（age range:27～78years old; median age:60years old） of T1b CCRCC examined byMR and confirmed by pathology were included in this study.Scanning sequences including coronal T2WI, transverse T2WI, T1WI, fat suppressionT2WI, diffusion-weighted imaging（DWI） and enhancement T1WI were performed inSiemens Verio3.0T MR. Gd-DTPA was used as contrast agent. ZOOM（zonal obliquemultislice）-EPI sequence was performed in DWI, and with b values of0and1200s/mm2respectively.Two senior pathologists assigned a nuclear grade for each CCRCC according to theFuhrman classification system. Four grades were merged into two classification systemconsisting of low-grade group（grades Ⅰ and Ⅱ） and high-grade group（grades Ⅲ andⅣ）. Two senior radiologists analysed all image of T1b CCRCC and measured ADC valuesof tumors on Siemens Syngo workstation.The SPSS17.0software was performed for statistical analysis. For the difference ofMRI features between low and high grade groups, chi-square test was used. The differenceof ADC values among four different pathologic grades was compared with a one-wayanalysis of variance（ANOVA）. The comparison of ADC values of two different gradinggroups was performed with Student’s t-test, and the ROC curve was performed to evaluatethe diagnostic efficiency of ADC values. Correlation between ADC values and pathological grading was assessed with Spearman rank correlation analysis. P<0.05wasconsidered to indicate a significant difference in all test.Results: There was no significant difference of the cases between low-grade groupand high-grade group in each sign, including pseudocapsule, necrosis, hemorrhage, mixedsignal of T1WI, mixed signal of T2WI and intense but inhomogeneous enhancement（χ2=0.031,0.062,0.625,0.139,1.875,1.701, respectively; P＞0.05）.The mean ADC value of grading Ⅰ, Ⅱ, Ⅲ and Ⅳwas（0.940±0.111）×10-3mm2/s,（0.816±0.129）×10-3mm2/s,（0.677±0.085）×10-3mm2/s,（0.590±0.028）×10-3mm2/s,respectively. Significant difference of ADC values among the four grades was present（F=16.422, P=0.000）.The mean ADC value of the low-grade group[（0.885±0.132）×10-3mm2/s] wassignificantly higher than that of the high-grade group[（0.641±0.079）×10-3mm2/s; t=5.738,P=0.000]. The area under the ROC curve was0.940. Taking0.724×10-3mm2/s as thethreshold value, sensitivity and specificity of differential diagnosis was88.9%and83.3%respectively.There was a high negative correlation between ADC value and pathologicalgrading（r=－0.807）．Conclusion:⑴Conventional MRI cannot differentiate low-grade group from high-grade group ofT1b CCRCC.⑵There was a high negative correlation between ADC value and pathological gradingof T1b CCRCC. The higher the ADC value, the lower the fuhrman grading and malignantdegree will be; Conversely, the lower the ADC value, the higher the fuhrman grading andmalignant degree will be.⑶ADC values can predict the pathological grading of T1b CCRCC. Taking0.724×10-3mm2/s as the threshold value, the sensitivity and specificity for differentiatinglow-grade group from high-grade group was high. The threshold value of ADC can help to make plan for operation program of T1b CCRCC.⑷ADC value can reflect the microscopic structure and pathophysiological changingof renal tumors. Comparing with conventional MRI, ADC values can better evaluate thepathological grading of T1b CCRCC preoperatively. |
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