Accurate IVIM model-based liver lesion characterisation can be achieved with only three b-value DWI

ObjectiveThe objective of this study was to evaluate a simplified intravoxel incoherent motion (IVIM) approach of diffusion-weighted imaging (DWI) with four b-values for liver lesion characterisation at 1.5 T.MethodsDWI data from a respiratory-gated MRI sequence with b = 0, 50, 250, 800 s/mm(2) were retrospectively analysed in 173 lesions and 40 healthy livers. The apparent diffusion coefficient ADC = ADC(0,800) and IVIM-based parameters D-1 = ADC(50,800), D-2 =ADC(250,800), f(1), f(2), D*, ADC(low) = ADC(0,50), and ADC(diff)=ADC(low)-D-2 were calculated voxel-wise without fitting procedures. Differences between lesion groups were investigated.ResultsFocal nodular hyperplasias were best discriminated from all other lesions by f(1) with an area under the curve (AUC) of 0.989. Haemangiomas were best discriminated by D-1 (AUC of 0.994). For discrimination between malignant and benign lesions, ADC(0,800) and D-1 were best suited (AUC of 0.915 and 0.858, respectively). Discriminatory power was further increased by using a combination of D-1 and f(1).ConclusionIVIM parameters D and f approximated from three b-values provided more discriminatory power between liver lesions than ADC determined from two b-values. The use of b = 0, 50, 800 s/mm(2) was superior to that of b = 0, 250, 800 s/mm(2). The acquisition of four instead of three b-values has no further benefit for lesion characterisation.Key Points center dot Diffusion and perfusion characteristics are assessable with only three b-values.center dot Association of b = 0, 50, 800 s/mm(2)is superior to b = 0, 250, 800 s/mm(2).center dot A fourth acquired b-value has no benefit for differential diagnosis.center dot For liver lesion characterisation, simplified IVIM analysis is superior to ADC determination.center dot Simplified IVIM approach guarantees numerically stable, voxel-wise results and short acquisition times.