Murine pulmonary imaging at 7T: T2* and T1 with anisotropic UTE

PurposeTo measure the T-2* and T-1 of mouse lung at 7T via anisotropic-resolution radial ultrashort echo-time imaging with ellipsoidal k-space coverage. MethodsEllipsoidal field-of-view was created by expanding uniform spherical k-space coverage. The effects of T-2* and ellipsoidal sampling on image resolution were investigated by using point-spread-function analysis and resolution phantoms. Finally, this ellipsoidal sampling approach was used to measure the lung T-2* and T-1 of healthy C57BL/6 mice at the increasingly common preclinical field strength of 7T. ResultsLung parenchyma T-2* of 17- to 23-week-old mice at 7T was 0.3950.033 ms. T-1 of lung and left- and right-heart ventricles was 1452.5 +/- 87.0 ms, 1810.5 +/- 54.6 ms, and 1602.6 +/- 120.9 ms, respectively. Ellipsoidal k-space sampling provides enhanced resolution for a fixed scanning time or provides equivalent (although anisotropic) spatial resolution with reduced scanning times, while simultaneously avoiding fold-in artifacts. ConclusionUsing these techniques, the first T-2* and T-1 measures of mouse lung at 7T are reported. Ultrashort echo-time imaging with ellipsoidal k-space coverage significantly increases in-plane resolution without increasing scanning time, or equivalently, decreases scanning time while maintaining equivalent in-plane resolution. Magn Reson Med 79:2254-2264, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.