Intravoxel incoherent motion diffusion-weighted MR imaging in differentiation of lung cancer from obstructive lung consolidation: comparison and correlation with pharmacokinetic analysis from dynamic contrast-enhanced MR imaging.

OBJECTIVES: To test whether parameters derived from intravoxel incoherent motion (IVIM) can be used to distinguish lung cancer from obstructive pulmonary consolidation by comparing them with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)-derived parameters and to evaluate the correlation between these quantitative parameters.
METHODS: A total of 31 lung cancer patients, confirmed by pathology and obstructive consolidations confirmed by positron emission tomography/computed tomography (PET-CT), were recruited. All of them were assessed with structural MRI and IVIM and 17 of them underwent additional DCE-MRI examinations. Parameters derived from IVIM and DCE-MRI in the tumour and consolidation were analysed, and the optimal cut-off values in differential diagnosis were obtained.
RESULTS: ADC(total), D and f values were lower (P < 0.05), while IAUC60 was higher in lung cancers (P = 0.013) compared with obstructive pulmonary consolidations. According to the ROC curve, ADC(total) outperformed other perfusion and diffusion parameters with the optimal cut-off value of 1.409 × 10(-3) mm(2)/s (AUC = 0.95). Poor correlations were found between parameters derived from IVIM and DCE-MRI.
CONCLUSIONS: IVIM-MRI is potentially useful in the differentiation of lung cancer and obstructive pulmonary consolidation. ADC(total), D and f may be reliable independent discriminating markers, but D* is variable with low diagnostic accuracy. KEY POINTS: • Lung cancer and consolidation differentiation is essential for treatment decision-making. • Perfusion and diffusion characteristics of lesions could help differential diagnosis. • IVIM can separate reflection of tissue diffusivity and microcapillary perfusion. • The relationship between perfusion quantified by IVIM and DCE-MRI is controversial.