T1 Mapping-Derived Parameters in Breast Lesions: Diagnostic Accuracy and Correlation with Pathologic Features

Rationale and objectives: To evaluate the diagnostic potential of T1 mapping-derived parameters for distinguishing between benign and malignant breast tumors and their associations with pathologic prognostic indicators in invasive breast cancer. Materials and methods: Patients who underwent breast surgery and quantitative magnetic resonance imaging (MRI), including apparent diffusion coefficient (ADC) and T1 mapping, between August 2023 and March 2024 were prospectively included. T1 parameters, including lesion T1 values before and after contrast agent injection (T10, T1c), reduction in T1 value (Delta T1), ratio of reduction (Delta T1%), extracellular volume fractions (ECVs), and ADC values were compared between benign and malignant breast lesions. The classification effect was evaluated via receiver operating characteristic (ROC) curves, and the correlation between MRI parameters and each prognostic indicator in invasive ductal carcinoma (IDC) was analyzed via Spearman correlation. Results: The ROC curves revealed that the area under the curve (AUC) of the ECV was slightly larger than that of the ADC (0.90 [95% CI: 0.84-0.95] vs 0.89 [95% CI: 0.83-0.94]). The combined diagnostic model of all parameters had the highest AUC (0.95 [95% CI: 0.90-0.98]). In IDC, ECV was positively correlated with the expression of estrogen receptor (r = 0.449, P < .001) and progesterone receptor (r = 0.433, P < .001) and negatively correlated with Ki-67 protein expression (r = -0.407, P < .001). No correlation was found between the ADC values and prognostic indicators. Conclusion: T1 parameters can effectively differentiate benign and malignant breast lesions and have potential utility in predicting tumor invasiveness.