Diffusion weighted imaging in cystic fibrosis disease: beyond morphological imaging.

OBJECTIVES: To explore the feasibility of diffusion-weighted imaging (DWI) to assess inflammatory lung changes in patients with Cystic Fibrosis (CF) METHODS: CF patients referred for their annual check-up had spirometry, chest-CT and MRI on the same day. MRI was performed in a 1.5 T scanner with BLADE and EPI-DWI sequences (b = 0-600 s/mm2). End-inspiratory and end-expiratory scans were acquired in multi-row scanners. DWI was scored with an established semi-quantitative scoring system. DWI score was correlated to CT sub-scores for bronchiectasis (CF-CTBE), mucus (CF-CTmucus), total score (CF-CTtotal-score), FEV1, and BMI. T-test was used to assess differences between patients with and without DWI-hotspots. RESULTS: Thirty-three CF patients were enrolled (mean 21 years, range 6-51, 19 female). 4 % (SD 2.6, range 1.5-12.9) of total CF-CT alterations presented DWI-hotspots. DWI-hotspots coincided with mucus plugging (60 %), consolidation (30 %) and bronchiectasis (10 %). DWItotal-score correlated (all p < 0.0001) positively to CF-CTBE (r = 0.757), CF-CTmucus (r = 0.759) and CF-CTtotal-score (r = 0.79); and negatively to FEV1 (r = 0.688). FEV1 was significantly higher (p < 0.0001) in patients without DWI-hotspots. CONCLUSIONS: DWI-hotspots strongly correlated with radiological and clinical parameters of lung disease severity. Future validation studies are needed to establish the exact nature of DWI-hotspots in CF patients. KEY POINTS: • DWI hotspots only partly overlapped structural abnormalities on morphological imaging • DWI strongly correlated with radiological and clinical indicators of CF-disease severity • Patients with more DWI hotspots had lower lung function values • Mucus score best predicted the presence of DWI-hotspots with restricted diffusion.