Simplified intravoxel incoherent motion DWI for differentiating malignant from benign breast lesions

BACKGROUND: To evaluate simplified intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) for differentiating malignant versus benign breast lesions as (i) stand-alone tool and (ii) add-on to dynamic contrast-enhanced magnetic resonance imaging. METHODS: 1.5-T DWI data (b = 0, 50, 250, 800 s/mm(2)) were retrospectively analysed for 126 patients with malignant or benign breast lesions. Apparent diffusion coefficient (ADC) ADC (0, 800) and IVIM-based parameters D(1)′ = ADC (50, 800), D(2)′ = ADC (250, 800), f(1)′ = f (0, 50, 800), f(2)′ = f (0, 250, 800) and D*′ = D* (0, 50, 250, 800) were voxel-wise calculated without fitting procedures. Regions of interest were analysed in vital tumour and perfusion hot spots. Beside the single parameters, the combined use of D(1)′ with f(1)′ and D(2)′ with f(2)′ was evaluated. Lesion differentiation was investigated for lesions (i) with hyperintensity on DWI with b = 800 s/mm(2) (n = 191) and (ii) with suspicious contrast-enhancement (n = 135). RESULTS: All lesions with suspicious contrast-enhancement appeared also hyperintense on DWI with b = 800 s/mm(2). For task (i), best discrimination was reached for the combination of D(1)′ and f(1)′ using perfusion hot spot regions-of-interest (accuracy 93.7%), which was higher than that of ADC (86.9%, p = 0.003) and single IVIM parameters D(1)′ (88.0%) and f(1)′ (87.4%). For task (ii), best discrimination was reached for single parameter D(1)′ using perfusion hot spot regions-of-interest (92.6%), which were slightly but not significantly better than that of ADC (91.1%) and D(2)′ (88.1%). Adding f(1)′ to D(1)′ did not improve discrimination. CONCLUSIONS: IVIM analysis yielded a higher accuracy than ADC. If stand-alone DWI is used, perfusion analysis is of special relevance.