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BACKGROUND Imaging of the lung by MRI is challenging due to the intrinsic low proton density and rapid T2 * relaxation. MRI methods providing lung parenchyma and function are in demand. PURPOSE To investigate the feasibility of two-dimensional ultrashort echo-time (2D UTE) imaging for lung function assessment. STUDY TYPE Prospective. POPULATION Eleven healthy volunteers. FIELD STRENGTH/SEQUENCE 3T, 2D tiny golden angle UTE (2D-tyUTE). ASSESSMENT The applicability of breath-hold (BH) and self-gated (SG) 2D-tyUTE for quantification of the lung parenchyma signal-to-noise ratio (SNR), proton fraction (fP ), fractional ventilation (FV), and perfusion (f) was investigated. Dependencies on repetition time (BHS/I1/I2 ) and respiratory phase (expiration [EX], inspiration [IN]) were investigated and compared between smokers and nonsmokers. STATISTICAL TESTS Analysis of variance (ANOVA), Kendell's W. RESULTS Significant differences of SNR (EX: 10.98 ± 3.19(BHS ), 14.58 ± 3.89(BHI1 ), 17.59 ± 4.92(BHI2 ), 11.00 ± 5.42(SG); IN: 7.17 ± 2.07(BHS ), 9.51 ± 2.37(BHI1 ), 10.49 ± 2.33(BHI2 ), 10.00 ± 4.14(SG)) (P

Background Current functional cardiovascular imaging protocols mostly rely on electrocardiogram (ECG) gating and breathholding. The resulting image quality can substantially suffer from insufficient patient cooperation or severe arrhythmia. Real-time imaging can mitigate these effects but requires highly accelerated techniques, usually relying on non-cartesian trajectories and Compressed Sensing (CS). Methods We investigate a sliding window reduced field of view (FOV) Echo Planar Imaging (EPI) technique for real-time cardiac MRI. Segmented EPI has been combined with a subtraction technique for reducing the FOV in cardiac applications to the region of the beating heart. Residual respiratory motion, potentially impairing the image quality, has been addressed by continuous update of the static image fraction, which is derived from a low-temporal resolution sliding window reconstruction. For further acceleration, the proposed technique was combined with parallel imaging. Results The sliding window reduced FOV technique was proven feasible to reconstruct images of diagnostic image quality at a temporal resolution of 36.5 ms per image. Semi-quantitative evaluation of image quality showed significant improvement over the existing rFOV method (p = 0.039). Derived functional parameters show comparable results as with the BH-CINE reference. However, a trend to a slight underestimation of the largest and smallest in-plane volumes is observed. Conclusion The proposed technique is feasible of providing real-time cardiac MRI with a temporal resolution better than 40 ms without the need of computably complex reconstruction techniques.

The overall duration of acquiring a Nyquist sampled 3D dataset can be significantly shortened by enhancing the efficiency of ${k}$ -space sampling. This can be achieved by increasing the coverage of ${k}$ -space for every trajectory interleave. Furthermore, acceleration is possible by making use of advantageous undersampling properties. In this paper, a versatile 3D center-out ${k}$ -space trajectory based on Jacobian elliptic functions (Seiffert’s spiral) is presented. The trajectory leads to a low-discrepancy coverage of ${k}$ -space using a considerably reduced number of readouts compared with other approaches. Such a coverage is achieved for any number of interleaves, and, therefore, even single-shot trajectories can be constructed to be combined with, for example, hyperpolarized media. Furthermore, acceleration is achievable due to non-coherent undersampling properties of the trajectory in combination with non-linear reconstruction techniques like compressed sensing (CS). Simulations of point-spread functions and discrepancy evaluations compare Seiffert’s spiral to the established 3D cones approach. Imaging capabilities are evaluated by comparison of in vivo knee images using Nyquist and undersampled datasets in combination with CS reconstructions.