Longitudinal Assessment of Patients With Cystic Fibrosis Lung Disease With Multivolume Noncontrast MRI and Spirometry.

BACKGROUND

MRI has been suggested as a radiation-free imaging modality to investigate early structural alterations and regional functional impairment in cystic fibrosis (CF) lung disease.

PURPOSE/HYPOTHESIS: To compare functional and morphological MRI changes over the course of the disease to changes in spirometry.

STUDY TYPE: Longitudinal retrospective study.

POPULATION: Twenty patients with CF lung disease (at baseline, age = 16.5 (13.3-20.6) years, forced expiratory volume in 1 second (as % of predicted [%pred]) FEV1 = 71 (59-87) %pred, forced expiratory flow at 25-75% of forced vital capacity FEF25-75 = 39 (25-63) %pred.

FIELD STRENGTH/SEQUENCE: 1.5T / T2 -weighted HASTE; T2 -weighted TSE-PROPELLER; T2 -weighted bSSFP; T1 -weighted 3D GRE.

ASSESSMENT: Nonenhanced chest MRI and spirometry were retrospectively collected over a 3-year period from the initial recruitment visit. Images acquired at end-inspiration and end-expiration were registered by software using the optical flow method to measure expiratory-inspiratory differences in MR signal-intensity (Δ1 H-MRI). Measures of CF functional impairment were defined from Δ1 H-MRI: Δ1 H-MRI median, Δ1 H-MRI quartile coefficient of variation (QCV), and percent low-signal-variation volume (LVV). MR images were also evaluated by three readers using a CF-specific scoring system.

STATISTICAL TESTS: Spearman correlation analysis, Spearman rank correlation analysis, linear mixed-effect model analysis, intraclass correlation coefficient.

RESULTS

Functional imaging parameters and total morphological score correlated with all spirometric measures, as did subscores of bronchial wall thickening/bronchiectasis, mucus plugging, and consolidation. Overall, the percent change of Δ1H-MRI median correlated with the percent change of FEV1 (ΔFEV1 , r = 0.41, P < 0.01) and the percent change of FEF25-75 (ΔFEF25-75%, r = 0.38, P < 0.01). The percent change of LVV correlated with ΔFEV1 (r = -0.47, P < 0.001) and ΔFEF25-75 (r = -0.50, P < 0.001).

DATA

CONCLUSION

These preliminary results suggest that nonenhanced multivolume MRI may provide a feasible tool to regionally map early pulmonary alterations for longitudinal evaluation of CF lung disease, without exposing the patients to ionizing radiation.

LEVEL OF EVIDENCE: 3T TECHNICAL EFFICACY STAGE: 5.