[Application value of diffusion-weighted imaging signal pattern in the qualitative diagnosis of renal lesions with T(2)WI hypointensity]

Objective: To analyze the diagnostic value of diffusion-weighted imaging (DWI) signal pattern in renal lesions with T(2)WI hypointensity. Methods: Retrospective analysis was performed on DWI imaging datasets of 135 renal lesions with hypointentsity on T(2)WI confirmed by surgery, biopsy, or follow-up in the First Medical Center of Chinese PLA General Hospital from February 2016 to February 2017.One hundred and thirty-five renal lesions,43 benign lesions(age from 28 to 70 years,mean age was 43.5 years, male 18 lesions and female 25 lesions) and 92 malignant lesions (age from 17 to 86 years, mean age was 54.1 years, male 62 lesions and female 30 lesions). DWI signal pattern was classified into six categories: homogeneously high signal, homogeneously low signal, heterogeneously high signal, high halo signal, high halo and nodular signal, and high nodular signal. The agreement between two observers were tested using kappa statistic. The statistical difference between DWI signal characteristics in benign and malignant lesions was analyzed with Chi-Square test. Diagnostic efficacy in differentiation of benign and malignant renal lesions using DWI signal pattern were calculated. Results: One hundred and thirty-five lesions were detected in 135 cases with T(2)WI hypointensity. There were 43 benign lesions and 92 malignant lesions. The agreement between two observers was very good (kappa value=0.878 6). In renal T(2)WI hypointensity lesions, the proportion of DWI homogeneous high signal, homogeneous low signal, heterogeneous high signal, high halo signal, high halo and nodular signal, high nodular signal was 4.7% (2/43), 25.6% (11/43), 30.2% (13/43), 18.6% (8/43), 11.6% (5/43), 9.3% (4/43), respectively. The proportion of malignant lesions was 10.9% (10/92), 0 (0/92), 17.4% (16/92), 13.0% (12/92), 56.5% (52/92) and 2.2% (2/92), respectively. The difference of high halo and nodules signal and homogeneous low signal was statistically significant (all P<0.01). The sensitivity, specificity, positive prediction value (PPV) and negative prediction value (NPV) of high halo and nodular signal for malignancy were 56.5% (52/92), 88.4%(38/43), 91.2% (52/57) and 48.7%(38/78), respectively and homogeneous low signal for benign lesions were 25.6% (11/43), 100.0% (92/92), 100.0% (11/11) and 74.2% (92/124), respectively. Conclusions: DWI signal features may facilitated the accurate diagnosis of renal lesions with T(2)WI hypointensity. Malignant lesions exhibit a higher propensity with high halo and nodular signal on DWI while benign lesions with homogeneous low signal.