Advantages of time-dependent diffusion MRI for quantitative microstructural mapping in breast tumors.

Objectives: Time-dependent diffusion MRI (TD-MRI) can measure tumor tissue microstructure, but its effectiveness in differentiating benign from malignant breast tumors is unclear. This study aims to investigate the diagnostic value of TD-MRI microstructural features for distinguishing between benign and malignant breast tumors.

Methods: This prospective study included 44 patients with malignant breast tumors and 28 with benign tumors. All subjects underwent the IMPULSED protocol on a 3.0-T MRI scanner. Imaging data were analyzed using least squares fitting in MATLAB, yielding Dex (extracellular diffusivity), Vin (intracellular volume fraction), Dmean (cell diameter), Vin/Dmean, and ADC values. The molecular subtypes of breast cancer are classified based on immunohistochemistry (IHC) results.

Results: Malignant tumors exhibited significantly lower Dmean (17.37 ± 2.74 µm 22.47 ± 3.85µm, p<0.0001), higher Vin (0.41 ± 0.13% 0.19 ± 0.10%, p<0.0001), and higher Vin/Dmean (2.13 ± 0.66 0.93 ± 0.61, p<0.0001) compared to benign tumors. No significant difference was found in Dex (2.15 ± 0.28 um/ms 2.25 ± 0.31 um/ms, p>0.05). Strong correlations were observed: positive between ADC and Dmean, and negative between ADC and both Vin and Vin/Dmean. AUC values for Vin (0.92; 95% CI: 0.86-0.99), and Vin/Dmean (0.91; 95% CI: 0.83-0.98) surpassed those for ADC.

Conclusion: TD-MRI microstructure mapping effectively differentiates benign from malignant breast tumors, highlighting its potential to improve diagnostic accuracy for lesions.