Differentiating Fat-Poor Angiomyolipoma from Chromophobe Renal Cell Carcinoma Using Preoperative Non-Contrast CT Histogram Analysis
Author Block: J. Wei, X. Zhang, J. Liu, J. Zhou; Lanzhou/CN
Purpose: To investigate the value of clinical-radiologic features and whole-tumor histogram analysis derived from non-contrast CT in differentiating fat-poor angiomyolipoma (fp-AML) from chromophobe renal cell carcinoma (ChRCC).
Methods or Background: This retrospective study enrolled 89 patients with pathologically confirmed fp-AML (n=36) or ChRCC (n=53). Clinical, imaging, and pathological data were collected. Demographic data and conventional CT features (sex, age, symptoms, location, shape, margin, attenuation on non-contrast CT, tumor volume) were recorded. Using FireVoxel software, volumetric regions of interest were drawn on axial non-contrast CT images to extract histogram parameters (minimum, maximum, mean, standard deviation, variance, coefficient of variation, skewness, kurtosis, entropy, and percentiles). Statistical analyses included the Chi-square test, Mann-Whitney U test, and independent samples t-test. Multivariable logistic regression was used to identify independent predictors for differentiation and to construct clinical-radiologic and histogram models. Receiver operating characteristic (ROC) curve analysis was performed to evaluate diagnostic performance.
Results or Findings: Multivariable analysis identified non-contrast CT attenuation (OR=1.178, 95% CI: 1.087-1.277, P<0.001), tumor volume (OR=0.952, 95% CI: 0.928-0.976, P<0.001), mean attenuation (OR=0.764, 95% CI: 0.589-0.946, P=0.015), skewness (OR=0.135, 95% CI: 0.046-0.396, P<0.001), and the Perc.75 (OR=1.522, 95% CI: 1.169-1.983, P=0.002) as independent predictors for differentiating fp-AML from ChRCC. Both models demonstrated good performance. The clinical-radiologic model achieved an AUC of 0.905 (95% CI: 0.843-0.967), with a sensitivity of 77.8% and specificity of 90.6%. The histogram model achieved an AUC of 0.964 (95% CI: 0.932-0.996), with a sensitivity of 88.9% and specificity of 75.5%.
Conclusion: Clinical-radiologic features and whole-tumor histogram analysis based on non-contrast CT can help noninvasively differentiate fp-AML from ChRCC preoperatively, providing valuable guidance for clinical management.
Limitations: This study is limited by its retrospective, single-center design, and the findings have not been validated in an independent cohort.
Funding for this study: Natural Science Foundation of Gansu Province (22JR11RA060)
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by the Medical Ethics Committee of the Second Hospital of Lanzhou University (approval number: 2025A-585) and informed consent was waived.