Value of diffusion weighted imaging signal intensity in exploring histopathological differentiation of clear cell renal cell carcinoma

Objective To evaluate the relationship between diffusion weighted imaging visual signal intensity and quantitative signal intensity of cell renal cell carcinoma (CCRCC) and histopathological differentiation of CCRCC. Methods This retrospective analysis included 91 patients with CCRCC confirmed by pathology. All patients were grouped according to the Fuhrman pathological grading system, from Ⅰto Ⅵ. Four grades were merged into three classifications consisting of 37 well-differentiated CCRCCs (Ⅰ and Ⅱ), 32 moderately-differentiated CCRCCs (Ⅲ) and 22 poorly-differentiated CCRCCs (Ⅳ). Magnetic resonance examinations of MR plain scan, LALA dynamic enhanced scan and DWI (1.5T, b value: 800 sec/mm2) were performed. The each visually signal intensity of CCRCC was evaluated and quantitative signal intensity of CCRCC was measured. The Kruskal-Wallis test was used to compare DWI visual signal intensity between the three different histopathological groups. ANOVA was used to compare SI values between the three different histopathological groups. Spearman correlation analysis was used to analyze the correlation between histopathological differentiation of CCRCC and DWI visual signal intensity and SI values. ROC analysis was performed to evaluate the diagnostic efficiency of SI values. Results 43.9% of CCRCC appeared as obviously hyperintense, 30.8% of CCRCC appeared as moderate hyperintense, and 25.3% of CCRCC appeared as isointense/slight hyperintense to the surrounding renal parenchyma. There was a significant difference between obviously hyperintense and isointense/slight hyperintense in histopathological differentiation (P 0.05).There was a moderate negative correlation between visually signal intensity and histopathological differentiation of CCRCC (rs=-0.552; P<0.01). There was a significant difference in DWI signal intensity value among well- differentiated、moderately-differentiated and poorly-differentiated CCRCC (P<0.05). The SI value of moderately differentiated CCRCC was lower than that of poorly-differentiated CCRCC and there was significant difference between the SI value of moderately-differentiated and poorly-differentiated CCRCC. There was a significant negative correlation between SI value and histopathological differentiation of CCRCC (r=-0.711; P<0.01). The ROC curve showed the optimal cutoff point of SI value was 273.7 in diagnosing well-differentiated CCRCC. Taking 273.7 as the threshold value, sensitivity and specificity of differential diagnosis was 67.6% and 98.2%, respectively. The ROC curve showed the optimal cutoff point of SI value was 378.9 in diagnosing poorly-differentiated CCRCC. Taking 378.9 as the threshold value, sensitivity and specificity of differential diagnosis was 91.3% and 59.1%, respectively. Conclusion CCRCC tended to show a higher visual signal intensity and quantitative signal intensity on DWI with decreasing histopathologicaldifferentiation (P<0.05). DWI had some practical value in predicting histopathogical differentiation of CCRCC using signal intensity and quantitative signal intensity. Key words: Magnetic resonance imaging; Diffusion magnetic resonance imaging; Clear cell renal cell carcinoma; Signal intensity; Histopathological