Imaging lung function using rapid dynamic acquisition of T1-maps during oxygen enhancement

This paper describes imaging of lung function with oxygen-enhanced MRI using dynamically acquired T-1 parameter maps, which allows an accurate, quantitative assessment of time constants of T-1-enhancement and therefore lung function. Eight healthy volunteers were examined on a 1.5-T whole-body scanner. Lung T-1-maps based on an IR Snapshot FLASH technique (TE = 1.4 ms, TR = 3.5 ins, FA - 7degrees) were dynamically acquired from each subject. Without waiting for full relaxation between subsequent acquisition of T-1-maps, one T-1-map was acquired every 6.7 s. For comparison, all subjects underwent a standard pulmonary function test (PET). Oxygen wash-in and wash-out time course curves of T-1 relaxation rate (R-1)-enhancement were obtained and time constants of oxygen wash-in (w(in)) and wash-out (w(out)) were calculated. Averaged over the whole right lung, the mean w(out) was 43.90 +/- 10.47 s and the mean (w(in)) was 51.20 +/- 15.53 s, thus about 17% higher in magnitude. Wash-in time constants correlated strongly with forced expired volume in one second in percentage of the vital capacity (FEV1 % VC) and with maximum expiratory flow at 25% vital capacity (MEF25), whereas wash-out time constants showed only weak correlation. Using oxygen-enhanced rapid dynamic acquisition of T-1-maps, time course curves of R-1-enhancement can be obtained. With w(in) and w(out) two new parameters for assessing lung function are available. Therefore, the proposed method has the potential to provide regional information of pulmonary function in various lung diseases.