Lung imaging is an essential part of the diagnostic work-up in CF patients with Magnetic Resonance Imaging (MRI) representing a novel approach to characterize lung disease. MRI enables beside morphological assessment also a functional evaluation and is preferred in young patients because of absence of radiation. Nevertheless the predictive value of MRI in cystic fibrosis (CF) has not been established.To evaluate usefulness of a novel MRI-Score as a prognostic biomarker for the clinical course of CF. Sixty-one CF-patients (mean age 12.9 ± 4.7 y) were examined using an optimized, advanced MRI-protocol for lung imaging including morphological sequences and very short TE PDw Flash 2D for functional evaluation without the use of contrast medium (Fig 1). Further all patients had a pulmonary function testing (PFT) performed within 14 days of the MRI-examination, as well as PFT follow-up over a period of at least 2 years. All MRI-examinations were analyzed by three blinded raters by the means of a self-developed MRI-Score and compared to the Helbich-Bhalla score (HB-S) (Ref 1). To evaluate loss of FEV1, a linear regression analysis over a period of two years was performed. HB-S and MRI-Score showed a moderate inverse correlation with FEV1 (-0.58 and -0.62, respectively). The best correlation for single categories of HB-S was severity and extent of bronchiectasis (-0.56) and for MRI-Score centrilobular opacity and air trapping (-0.69 and -0.62). Our optimized MRI-Score was able to predict loss of FEV1 within 2 years. Particularly, after excluding patients with high normal (> 99%) or very low values (<45%) of FEV1 at baseline the extent of centrilobular opacity was highly significant associated with a more severe loss of FEV1 in children with CF.Our new CF-specific MRI-Score predicts loss of pulmonary function in children with CF. Further prospective evaluations of the new score are necessary to confirm its clinical usefulness.