Intravoxel incoherent motion diffusion-weighted MR imaging of breast cancer: association with histopathological features and subtypes

Objective: To evaluate the associations between intravoxel incoherent motion (IVIM)-derived parameters and histopathological features and subtypes of breast cancer. Methods: Pre-operative MRI from 275 patients with unilateral breast cancer was analyzed. The apparent diffusion coefficient (ADC) and IVIM parameters [tissue diffusion coefficient (D-t), perfusion fraction (f(p)) and pseudodiffusion coefficient] were obtained from cancer and normal tissue using diffusion-weighted imaging with b-values of 0, 30, 70, 100, 150, 200, 300, 400, 500 and 800 s mm(-2). We then compared the IVIM parameters of tumours with different histopathological features and subtypes. Results: The ADC and Dt were lower and fp was higher in cancers than in normal tissues (p < 0.001), The Dt was lower in high Ki-67 cancer than in low Ki-67 cancer (p = 0.019), whereas ADC showed no significant difference (p = 0.309). Luminal B [human epidermal growth factor receptor 2 (HER2)-negative] cancer showed lower ADC (p = 0,003) and Dt (p = 0.001) than other types. Conclusion: We found low tissue diffusivity in high Ki-67 cancer and lumina! B (HER2-negative) cancer using IVIM imaging. Advances in knowledge: Low tissue diffusivity is more clearly shown in high Ki-67 tumours and lumina! B (HER2-negative) tumours with the IVIM model.