The purpose of this study was to determine whether intravoxel incoherent motion (IVIM) -derived parameters and apparent diffusion coefficient (ADC) could act as imaging biomarkers for predicting antifungal treatment response. Forty-six consecutive patients (mean age, 33.9 +/- 13.0 y) with newly diagnosed invasive fungal infection (IFI) in the lung according to EORTC/MSG criteria were prospectively enrolled. All patients underwent diffusion-weighted magnetic resonance (MR) imaging at 3.0 T using 11 b values (0-1000 sec/mm(2)). ADC, pseudodiffusion coffiecient D*, perfusion fraction f, and the diffusion coefficient D were compared between patients with favourable (n=32) and unfavourable response (n=14). f values were significantly lower in the unfavourable response group (12.6%+/- 4.4%) than in the favourable response group (30.2%+/- 8.6%) (Z=4.989, P0.05). Receiver operating characteristic curve analyses showed f to be a significant predictor for differentiation, with a sensitivity of 93.8% and a specificity of 92.9%. IVIM-MRI is potentially useful in the prediction of antifungal treatment response to patients with IFI in the lung. Our results indicate that a low perfusion fraction f may be a noninvasive imaging biomarker for unfavourable response. aEuro cent Recognition of IFI indicating clinical outcome is important for treatment decision-making. aEuro cent IVIM can reflect diffusion and perfusion information of IFI lesions separately. aEuro cent Perfusion characteristics of IFI lesions could help differentiate treatment response. aEuro cent An initial low f may predict unfavourable response in IFI.