Pulmonary MR perfusion at 3.0 Tesla using a blood pool contrast agent: Initial results in a swine model

Purpose: To prospectively evaluate the technical feasibility of a highly accelerated pulmonary MR perfusion protocol at 3.0T using a blood pool contrast agent in a swine model. Materials and Methods: Twelve pigs underwent time-resolved pulmonary MR angiography (MRA) on a 3.0T MR system under anesthesia and controlled mechanical ventilation. After intravenous injection of 0.05 mmol/kg of Gadomer-17 at 4 mL/second, a fast time-resolved MRA sequence with temporal echo-sharing (three segmented k-space) and highly accelerated parallel acquisition was used to acquire 3D data sets with an in-plane resolution of 1 × 1 mm² (slice thickness = 6 mm) and temporal resolution of one second. Image quality was evaluated independently by two radiologists, and quantitative analysis of perfusion parameters was performed using pre-released perfusion software. Results: All studies were identified by both readers as having diagnostic image quality (range = 2-3, median = 3) and there was excellent interobserver agreement (κ = 0.89; 95% CI = 0.83, 0.95). A quantitative analysis of perfusion indices was performed, with excellent overall goodness-of-fit (χ² value = 1.4, degree of freedom (DF) = 1). Successfully derived perfusion parameters included the time to peak (TTP, 5.1 ± 0.7 second), mean transit time (MTT, 6.6 ± 0.9 second), maximal signal intensity (MSI, 1051.2 ± 718.9 arbitrary units [A.U.]), and maximal upslope of the curve (MUS, 375.9 ± 263.4 A.U./second). Conclusion: 3.0T pulmonary MR perfusion using a blood pool contrast agent in a swine model is feasible. The higher available signal-to-noise ratio (SNR) at 3.0T and the high T1 relaxivity of Gadomer-17 effectively support highly accelerated parallel acquisition, and improve the performance of time-resolved pulmonary MRA.