Apparent diffusion coefficient histogram analysis: differentiation of clear cell renal cell carcinoma from non-clear cell renal cell carcinoma with r-field of view diffusion weighted imaging

Abstract

Objective To explore the utility of ADC histogram analysisin differentiation of clear cell renal cell carcinoma(ccRCC)and non-clear cell renal cell carcinoma(non-ccRCC)with r-Fov DWI. Methods Sixty-six renal tumors(46 patients with 47 ccRCCs and 18 patients with 19 non-ccRCCs)in 64 patients, who underwent preoperative routine renal MRI sequences and r-FOV DWI, were retrospectively evaluated. The whole-lesion ADC values derived from histogram anlysis(including ADC mean, ADC median, ADC_5th, ADC_25th, ADC_75th, ADC_95th, skew and kurtosis)were measured for each patient. All parameters between ccRCC and non-ccRCC were compared by using the Student's t test or Mann-Whitney U test. ROC analysis was used to assess the diagnostic performance of ADC histogram in distinguishing the two groups. Results The postive skewness of ADC histograms were mostly seen in the non-ccRCC group, while the negtative skewness were present in the majority of ccRCCs. The skewness was significantly higher in non-ccRCCs than those of ccRCCs(P 0.05). 75th percentile ADC achieved the highest AUC(0.987)in differentiating ccRCC and non-ccRCC, whena cutoff value was 1.81× 10-3 mm2/s. The sensitivity and specificity were 100.0% and 94.7%. Conclusion ADC histograms of r-FOV DWI may be helpful to differentiate ccRCC from non-ccRCC, and the diagnostic accuracy of 75th percentile ADC is highest. Key words: Kidney neoplasms; Magnetic resonance imaging; Histogram