Cardiac Magnetic Resonance Fingerprinting (cMRF) has been demonstrated to enable robust and accurate T1 and T2 mapping for the detection of myocardial fibrosis and edema. However, the relatively long acquisition window (250 ms) used in previous cMRF studies might leave it vulnerable to motion artifacts in patients with high heart rates. The goal of this study was therefore to compare cMRF with a short acquisition window (154 ms) and low-rank reconstruction to routine cardiac T1 and T2 mapping at 1.5 T. Phantom studies showed that the proposed cMRF had a high T1 and T2 accuracy over a wider range than routine mapping techniques. In 9 healthy volunteers, the proposed cMRF showed small but significant myocardial T1 and T2 differences compared to routine mapping (ΔT1 = 1.5%, P = 0.031 and ΔT2 = − 7.1%, P < 0.001). In 61 consecutive patients referred for CMR, the native T1 values were slightly lower (ΔT1 = 1.6%; P = 0.02), while T2 values did not show statistical difference (ΔT2 = 4.3%; P = 0.11). However, the difference was higher in post-contrast myocardial T1 values (ΔT1 = 12.3%; P < 0.001), which was reflected in the extracellular volume (ΔECV = 2.4%; P < 0.001). Across all subjects, the proposed cMRF had a lower precision when compared to routine techniques, although its higher spatial resolution enabled the visualization of smaller details.

Functional magnetic resonance imaging (fMRI) is a methodological cornerstone of neuroscience. Most studies measure blood-oxygen-level-dependent (BOLD) signal using echo-planar imaging (EPI), Cartesian sampling, and image reconstruction with a one-to-one correspondence between the number of acquired volumes and reconstructed images. However, EPI schemes are subject to trade-offs between spatial and temporal resolutions. We overcome these limitations by measuring BOLD with a gradient recalled echo (GRE) with 3D radial-spiral phyllotaxis trajectory at a high sampling rate (28.24ms) on standard 3T field-strength. The framework enables the reconstruction of 3D signal time courses with whole-brain coverage at simultaneously higher spatial (1mm3) and temporal (up to 250ms) resolutions, as compared to optimized EPI schemes. Additionally, artifacts are corrected before image reconstruction; the desired temporal resolution is chosen after scanning and without assumptions on the shape of the hemodynamic response. By showing activation in the calcarine sulcus of 20 participants performing an ON-OFF visual paradigm, we demonstrate the reliability of our method for cognitive neuroscience research.

The most commonly employed T2 mapping techniques are 2D and make use of ECG-triggering. This may be a limitation in patients with variable heart rate and complex three-dimensional conditions. To address these limitations, we here propose an isotropic free-running 3D T2 mapping technique that avoids ECG triggering by using Pilot Tone navigation. In three healthy volunteers, our technique produced accurate isotropic T2 maps when compared to 2D T2 prepared bSSFP (T2=41.1&plusmn;4.8ms vs. 44.9&plusmn;3.3ms, respectively, p=0.1), and cardiac motion was successfully resolved.

We implemented and compared three different reconstructions for 3D T2 mapping of the knee: I) a standard image reconstruction followed by an analytical fit, II) a standard image reconstruction followed by a dictionary fit, and III) a denoised image reconstruction followed by a dictionary fit. We optimized and compared these techniques in phantoms, five healthy volunteers, and five patients with mild osteoarthritis. The third reconstruction resulted in the highest accuracy and precision while retaining the spatial resolution, and allowed the load-bearing cartilage in the mild-OA patients to be differentiated from that in the healthy volunteers.

We introduce a novel method for combining multiple free-running MRI acquisitions together, through the use of cardiac and respiratory signal extraction with Pilot Tone navigation called Synchronization of Neighboring Acquisitions by Physiological Signals (SyNAPS). We demonstrate the initial feasibility and utility of SyNAPS on a setup for joint reconstruction of back-to-back dynamic anatomical and flow MRI acquisitions, here named 4D flow SyNAPS. Overall, 4D flow SyNAPS enabled an improved structural visualization, when compared to the magnitude images from free-running 4D flow datasets alone, and the resulting flow measurements showed better agreement with reference 2D flow acquisitions.