Magnetic Resonance Imaging (MRI)

PURPOSE: To design parallel transmit (pTx) simultaneous multislice (SMS) spokes pulses with explicit control for peak power and local and global specific absorption rate (SAR).
METHODS: We design SMS pTx least-squares and magnitude least squares spokes pulses while constraining local SAR using the virtual observation points (VOPs) compression of SAR matrices. We evaluate our approach in simulations of a head (7T) and a body (3T) coil with eight channels arranged in two z-rows.

PURPOSE: To develop an active MR-tracking system to guide placement of metallic devices for radiation therapy.

PURPOSE: Specific absorption rate (SAR) amplification around active implantable medical devices during diagnostic MRI procedures poses a potential risk for patient safety. In this study, we present a parallel transmit (pTx) strategy that can be used to safely scan patients with deep brain stimulation (DBS) implants.

BACKGROUND: Despite improvements in treatments, metastatic breast cancer remains difficult to cure. Bones constitute the most common site of first-time recurrence, occurring in 40-75% of cases. Therefore, evaluation for possible osseous metastases is crucial. Technetium 99 ((99)Tc) bone scintigraphy and fluorodexossyglucose (FDG) positron emission tomography (PET)-computed tomography (PET-CT) are the most commonly used techniques to assess osseous metastasis. PET magnetic resonance (PET-MR) imaging is an innovative technique still under investigation.

Altered brain morphometry has been widely acknowledged in chronic pain, and recent studies have implicated altered network dynamics, as opposed to properties of individual brain regions, in supporting persistent pain. Structural covariance analysis determines the inter-regional association in morphological metrics, such as gray matter volume, and such structural associations may be altered in chronic pain. In this study, voxel-based morphometry structural covariance networks were compared between fibromyalgia patients (N = 42) and age- and sex-matched pain-free adults (N = 63).

Naturalistic stimuli such as movies are increasingly used to engage cognitive and emotional processes during fMRI of brain hemodynamic activity. However, movies have been little utilized during magnetoencephalography (MEG) and EEG that directly measure population-level neuronal activity at a millisecond resolution. Here, subjects watched a 17-min segment from the movie Crash (Lionsgate Films, 2004) twice during simultaneous MEG/EEG recordings. Physiological noise components, including ocular and cardiac artifacts, were removed using the DRIFTER algorithm.

Subject motion is unavoidable in clinical and research imaging studies. Breathing is the most important source of motion in whole-body PET and MRI studies, affecting not only thoracic organs but also those in the upper and even lower abdomen. The motion related to the pumping action of the heart is obviously relevant in high-resolution cardiac studies. These two sources of motion are periodic and predictable, at least to a first approximation, which means certain techniques can be used to control the motion (eg, by acquiring the data when the organ of interest is relatively at rest).

BACKGROUND: Extensive evidence indicates that cortical connectivity patterns are abnormal in autism spectrum disorders (ASD), showing both overconnectivity and underconnectivity. Since, however, studies to date have focused on either spatial or spectral dimensions, but not both simultaneously, much remains unknown about the nature of these abnormalities. In particular, it remains unknown whether abnormal connectivity patterns in ASD are driven by specific frequency bands, by spatial network properties, or by some combination of these factors.

PURPOSE: To determine the detection rate, clinical relevance, Gleason grade, and location of prostate cancer ( PCa prostate cancer ) diagnosed with and the safety of an in-bore transperineal 3-T magnetic resonance (MR) imaging-guided prostate biopsy in a clinically heterogeneous patient population.

Visual information is largely processed through two pathways in the primate brain: an object pathway from the primary visual cortex to the temporal cortex (ventral stream) and a spatial pathway to the parietal cortex (dorsal stream). Whether and to what extent dissociation exists in the human prefrontal cortex (PFC) has long been debated. We examined anatomical connections from functionally defined areas in the temporal and parietal cortices to the PFC, using noninvasive functional and diffusion-weighted magnetic resonance imaging.