Volume-Controlled 19 F MR Ventilation Imaging of Fluorinated Gas.

Abstract

19 F MRI of inhaled gas tracers has developed into a promising tool for pulmonary diagnostics. Prior to clinical use, the intersession repeatability of acquired ventilation parameters must be quantified and maximized. To evaluate repeatability of static and dynamic 19 F ventilation parameters and correlation with predicted forced expiratory volume in 1 second (FEV1 %pred) with and without inspiratory volume control. Prospective. A total of 30 healthy subjects and 26 patients with chronic obstructive pulmonary disease (COPD). Three-dimensional (3D) gradient echo pulse sequence with golden-angle stack-of-stars k-space encoding at 1.5T. All study participants underwent 19 F ventilation MRI over eight breaths with inspiratory volume control (w VC) and without inspiratory volume control (w/o VC), which was repeated within 1 week. Ventilated volume percentage (VVP), fractional ventilation (FV), and wash-in time (WI) were computed. Lung function testing was conducted on the first visit. Correlation between imaging and FEV1 %pred was measured using Pearson correlation coefficient (r). Differences in imaging parameters between first and second visit were analyzed using paired t-test. Repeatability was quantified using intraclass correlation coefficient (ICC) and coefficient of variation (CoV). Minimum detectable effect size (MDES) was calculated with a power analysis for study size n=30 and a power of 0.8. All hypotheses were tested with a significance level of 5% two sided. Strong and moderate linear correlations with FEV1 %pred for COPD patients were found in almost all imaging parameters. The ICC w VC exceeds the ICC w/o VC for all imaging parameters. CoV was significantly lower w VC for initial VVP in COPD patients, FV, CoV FV, WI and standard deviation (SD) of WI. MDES of all imaging parameters were smaller w VC. 19 F gas wash-in MRI with inspiratory volume control increases the correlation and repeatability of imaging parameters with lung function testing. 2 TECHNICAL EFFICACY: Stage 2.