Perirenal fat Hounsfield units: not only for renal stones but also for renal cell carcinoma

Objective: We aimed to evaluate the role of attenuation values of perirenal fat calculated by computed tomography (CT) in differentiating aggressive renal masses.Methods: The data of 83 patients with histologically confirmed local stage renal cell carcinoma (RCC), who were treated with nephrectomy in our center, and 78 control group cases were analyzed.All measurements including renal mass volume, abdominal subcutaneous fat area and subcutaneous fat area pelvic subcutaneous fat area, and perirenal fat thickness and Hounsfield unit (perirenal fat tissue thickness [PFT]-Hounsfield unit of perirenal fat [PFHU]) were performed on CT by the same radiologist.Results: In the statistical analysis of PFT and PFHU measurements between the groups, fat thickness was found to be lower in the patient group compared with the control group.However, hounsfield unit measurements were statistically significantly higher in the patient group (p < 0.0001).A cutoff value of -98.1 for the PFHU can identify the patient group with a sensitivity of 89.2% and a specificity of 84.6% (area under the curve = 0.9; 95% confidence interval: 0.86-0.95p < 0.0001).In the multivariate logistic regression analysis, a PFHU ≥ -98.1 was independently associated with RCC after accounting for clinical and radiologic parameters.Conclusion: We believe that measurement of the HU values of perirenal adipose tissue with the CT may be useful in differentiating aggressive renal masses and therefore in determining the appropriate treatment selection.