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Balanced steady-state free precession (SSFP) imaging is limited by off-resonance banding artifacts, which occur with periodicity 1/TR in the frequency spectrum. A novel balanced SSFP technique for widening the band spacing in the frequency response is described. This method, called wideband SSFP, utilizes two alternating repetition times with alternating RF phase, and maintains high SNR and T 2 /T 1 contrast. For a fixed band spacing, this method can enable improvements in spatial resolution compared to conventional SSFP. Alternatively, for a fixed readout duration this method can widen the band spacing, and potentially avoid the banding artifacts in conventional SSFP. The method is analyzed using simulations and phantom experiments, and is applied to the reduction of banding artifacts in cine cardiac imaging and high-resolution knee imaging at 3T. Magn Reson Med 58:931-938, 2007.

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MR-encephalography is a technique that allows real-time observation of functional changes in the brain with a time-resolution of 100 ms. The high sampling rate is enabled by the use of undersampled image acquisition with regularized reconstruction. The article describes a novel imaging method for fast three-dimensional-MR-encephalography whole brain coverage based on undersampled, single-shot concentric shells trajectories and the use of multiple small receiver coils. The technique allows the observation of changes in blood oxygenation level dependent signal as a measure of brain physiology at very high temporal resolution. Magn Reson Med 68:484-494,

Connectome genetics seeks to uncover how genetic factors shape brain functional connectivity; however, the causal impact of a single gene's activity on whole-brain networks remains unknown. We tested whether the sole targeted deletion of the mu opioid receptor gene (Oprm1) alters the brain connectome in living mice. Hypothesis-free analysis of combined resting-state fMRI diffusion tractography showed pronounced modifications of functional connectivity with only minor changes in structural pathways. Fine-grained resting-state fMRI mapping, graph theory, and intergroup comparison revealed Oprm1-specific hubs and captured a unique Oprm1 gene-to-network signature. Strongest perturbations occurred in connectional patterns of pain/aversion-related nodes, including the mu receptor-enriched habenula node. Our data demonstrate that the main receptor for morphine predominantly shapes the so-called reward/aversion circuitry, with major influence on negative affect centers. mouse brain connectivity | resting-state functional MRI | diffusion tensor imaging | mu opioid receptor | reward/aversion network N euronal connectivity is at the foundation of brain function (1) and the concept that brain connectivity patterns are dynamically shaped by experience, pathology, and genetics has gained increasing importance. In humans, MRI has opened the era of connectome/imaging genetics to elucidate how genetic factors affect brain organization and connectivity in healthy individuals and disease, and to correlate genotype to phenotype (2). However, the causal impact of a single gene on overall functional connectivity (FC) remains largely unknown, and animal research is best suited to this goal. Here we tested whether combined functional/structural MRI in live animals (3-8) coupled to open-ended postprocessing analysis would reveal connectivity alterations upon targeted inactivation of a single gene. The mu opioid receptor (MOR) mediates the remarkably potent analgesic and addictive properties of opiates, like morphine (9), and belongs to the endogenous opioid system that controls sensory, emotional, and cognitive processes. This receptor is broadly distributed throughout the nervous system (10). It is a key component to facilitate reward (11) and relieves the negative experience of pain (12)(13)(14). In this report we show that targeted deletion of the MOR gene (Oprm1) significantly alters the brain connectome in living mice and predominantly reshapes the so-called reward/aversion network involved in pain, depression, and suicide (15). Results and DiscussionFine-Grained Mapping of the Mouse Brain Functional Connectome. In a first step, we established fine-grained mapping of the mouse brain functional connectome (MBFC) in control and Oprm1 −/− living mice. Using data-driven spatial independent component analysis (100-ICASSO) (4) of combined blood oxygenation level-dependent (BOLD) resting-state functional MRI (rsfMRI) datasets (Materials and Methods, Data Analysis), we identified 87 functional components, the patterns of which covered neur...

In this article we aim at improving the performance of whole brain functional imaging at very high temporal resolution (100 ms or less). This is achieved by utilizing a nonlinear regularized parallel image reconstruction scheme, where the penalty term of the cost function is set to the L1-norm measured in some transform domain. This type of image reconstruction has gained much attention recently due to its application in compressed sensing and has proven to yield superior spatial resolution and image quality over e.g. Tikhonov regularized image reconstruction. We demonstrate that by using nonlinear regularization it is possible to more accurately localize brain activation from highly undersampled k-space data at the expense of an increase in computation time.