Diagnostic value of diffusion-weighted imaging combined with DCE-MRI time-signal intensity curve for differentiating benign from malignant BI-RADS 4 breast lesions.

OBJECTIVE: To determine whether intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) parameters combined with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) time-signal intensity curve (TIC) can help distinguish benign from malignant BI-RADS 4 breast lesions. MATERIALS AND METHODS: This retrospective study included 81 women with pathologically confirmed BI-RADS 4 breast lesions (22 benign, 59 malignant). For each lesion, TIC type, apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) were recorded. Pathological results served as the reference standard. Each parameter was compared between benign and malignant groups using independent t‑test or Mann‑Whitney U test. Diagnostic models were built using binary logistic regression, and their performance was assessed with ROC curves and leave‑one‑out cross‑validation. RESULTS: Malignant lesions had significantly lower ADC and D values than benign ones (both P < 0.05). D* and f did not differ between groups. Type III TIC was much more common in malignant than in benign lesions (P < 0.05). Among individual parameters, ADC performed best (AUC = 0.83, 95 % CI: 0.72-0.94). Adding TIC to ADC raised the AUC to 0.88, with sensitivity 0.93, specificity 0.73 and accuracy 0.88. CONCLUSION: Both DWI parameters (especially ADC and D) and TIC type help differentiate benign from malignant BI-RADS 4 lesions. The ADC combined with TIC model offers better diagnostic accuracy and is practical for clinical use.