CARDIAC IMAGINGC ardiovascular diseases are often associated with a disruption of the oxygen demand and supply equilibrium, which can lead to functional impairments and heart failure (1). There are numerous methods to diagnose myocardial ischemia by using surrogate markers (2), but these techniques often need contrast agents, vasodilators, or radiation, and do not directly reflect the ischemic response (3).Cardiac MRI can be used to assess myocardial oxygenation by using the blood oxygen level-dependent (BOLD) effect (4). Both T2-and T2*-weighted imaging and mapping approaches (5-7) have been used as cardiac BOLD MRI techniques to help identify coronary artery disease without the use of exogenous contrast agent (8-11). Breath-hold interventions are recognized to trigger a cardiac BOLD response (8,(11)(12)(13), causing an increase in vascular CO 2 levels and myocardial vasodilation within 15 seconds ( 14), which results in an increase of myocardial T2 and T2*. In addition to depicting coronary artery disease, it has been hypothesized that cardiac BOLD MRI may be able to depict microvascular dysfunction in conditions such as hypertension (1,15) because of expected differences in vascular response ( 16). Depiction of these relatively subtle differences by using current BOLD MRI techniques is challenging, but several approaches have been developed to

Purpose: Brain imaging exams typically take 10-20 min and involve multiple sequential acquisitions. A low-distortion whole-brain echo planar imaging (EPI)-based approach was developed to efficiently encode multiple contrasts in one acquisition, allowing for calculation of quantitative parameter maps and synthetic contrastweighted images. Methods: Inversion prepared spin-and gradient-echo EPI was developed with sliceorder shuffling across measurements for efficient acquisition with T 1 , T 2 , and T * 2 weighting. A dictionary-matching approach was used to fit the images to quantitative parameter maps, which in turn were used to create synthetic weighted images with typical clinical contrasts. Dynamic slice-optimized multi-coil shimming with a B 0 shim array was used to reduce B 0 inhomogeneity and, therefore, image distortion by >50%. Multi-shot EPI was also implemented to minimize distortion and blurring while enabling high in-plane resolution. A low-rank reconstruction approach was used to mitigate errors from shot-to-shot phase variation. Results: The slice-optimized shimming approach was combined with in-plane parallel-imaging acceleration of 4× to enable single-shot EPI with more than eightfold distortion reduction. The proposed sequence efficiently obtained 40 contrasts across the whole-brain in just over 1 min at 1.2 × 1.2 × 3 mm resolution. The multishot variant of the sequence achieved higher in-plane resolution of 1 × 1 × 4 mm with good image quality in 4 min. Derived quantitative maps showed comparable values to conventional mapping methods. Conclusion:The approach allows fast whole-brain imaging with quantitative parameter maps and synthetic weighted contrasts. The slice-optimized multi-coil shimming | 867 MANHARD et Al.

The PR-based DCE-MRI analysis was successfully automated to spatially map intratumoral vascular heterogeneity. Magn Reson Med 79:1736-1744, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

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