A novel CT-based normalization strategy using lesion-to-spleen density ratios for renal mass characterization.

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Accurate preoperative characterization of renal masses is challenging, with many benign lesions undergoing unnecessary surgery.
• Absolute Hounsfield unit (HU) measurements in contrast-enhanced computed tomography (CT) are variable and unreliable for differentiating renal masses.

Purpose of the Study:

• To introduce and evaluate a novel CT-based normalization strategy using lesion-to-organ HU ratios.
• To improve the differentiation between benign and malignant renal masses.
• To explore the performance of this strategy across different renal cell carcinoma (RCC) subtypes.

Main Methods:

• Retrospective analysis of 248 patients with histopathologically confirmed renal tumors who underwent multiphasic CT.
• Calculation of lesion-to-kidney (LK) and lesion-to-spleen (LS) HU ratios from contrast-enhanced images.
• Evaluation of diagnostic performance using receiver operating characteristic (ROC) analysis and logistic regression, with subgroup analysis for RCC subtypes.

Main Results:

• Both contrast-enhanced lesion-to-kidney (CE-LK) and lesion-to-spleen (CE-LS) HU ratios significantly differentiated benign from malignant lesions (p < 0.01).
• CE-LK ratio showed high diagnostic performance (AUC = 0.914), while CE-LS ratio demonstrated excellent accuracy (AUC = 0.883) with 87.4% sensitivity and 87.5% specificity.
• The CE-LS HU ratio was an independent predictor of malignancy (OR = 36.9, p = 0.004) and papillary RCC showed lower CE-LS HU ratios than clear cell RCC (p = 0.020).

Conclusions:

• Lesion-to-spleen HU normalization is a simple, reproducible, and broadly applicable CT-based approach.
• This method enhances renal mass characterization.
• It may aid in reducing unnecessary surgical interventions for renal masses.