Simultaneous static and cine nonenhanced MR angiography using radial sampling and highly constrained back projection reconstruction.

Purpose: To describe a pulse sequence for simultaneous static and cine nonenhanced magnetic resonance angiography (NEMRA) of the peripheral arteries.

Methods: The peripheral arteries of 10 volunteers and 6 patients with peripheral arterial disease (PAD) were imaged with the proposed cine NEMRA sequence on a 1.5 Tesla (T) system.

Evaluation of peripheral arterial disease with nonenhanced quiescent-interval single-shot MR angiography.

Purpose: To assess the diagnostic performance of quiescent-interval single-shot (QISS) magnetic resonance (MR) angiography, a nonenhanced two-dimensional electrocardiographically gated single-shot balanced steady-state free precession examination for the evaluation of symptomatic chronic lower limb ischemia.

Materials And Methods: For this prospective institutional review board-approved, HIPAA-compliant study, the institutional review board waived the requirement for informed patient consent. The QISS nonenhanced MR angiography technique was evaluated in a two-center trial involving 53 patients referred for lower extremity MR angiography for suspected or known chronic peripheral arterial disease (PAD), with contrast material-enhanced MR angiography serving as the noninvasive reference standard.

Sub-millimeter isotropic MRI for segmentation of subcortical brain regions and brain visualization.

Purpose: To evaluate a rapid sub-millimeter isotropic spoiled gradient-echo (nonselective SPGR) to facilitate the brain subcortical segmentation and the visualization of brain volume compared with the commonly accepted inversion recovery-prepared SPGR (SPGR-IR) technique.

Materials And Methods: The feasibility of the nonselective SPGR was evaluated for two segmentation algorithms. FAST was used to segment the brain into constituent tissue classes (white matter, gray matter, cerebrospinal fluid) and FreeSurfer was used to segment specific subcortical structures (hippocampus, caudate, putamen, and thalamus).

Quiescent-interval single-shot unenhanced magnetic resonance angiography of peripheral vascular disease: Technical considerations and clinical feasibility.

We performed technical optimization followed by a pilot clinical study of quiescent-interval single-shot MR angiography for peripheral vascular disease. Quiescent-interval single-shot MR angiography acquires data using a modified electrocardiographic (ECG)-triggered, fat suppressed, two-dimensional, balanced steady-state, free precession pulse sequence incorporating slice-selective saturation and a quiescent interval for maximal enhancement of inflowing blood. Following optimization at 1.

Cerebral venography using fluid-suppressed STARFIRE.

Fluid-suppressed STARFIRE (Signal Targeting Alternative Radiofrequency and Flow-Independent Relaxation Enhancement) is a noncontrast method for flow-independent MR venography (MRV). It uses magnitude subtraction of two inversion recovery-prepared segmented three-dimensional (3D) balanced steady-state free precession acquisitions to obtain isotropic cerebral venograms in which both fat and cerebrospinal fluid signals are suppressed. Unlike two-dimensional time-of-flight (2D TOF) MRV, it is insensitive to the flow velocity of the cerebral veins.

Rapid whole-brain magnetic resonance imaging with isotropic resolution at 3 Tesla.

Isotropic imaging offers the potential of improving lesion detection and imaging efficiency by enabling orthogonal image reformations without loss of spatial resolution. However, lengthy scan times for T1-weighted isotropic data acquisitions have been an impediment to the routine clinical application of this approach. We tested the feasibility of using the improved signal-to-noise ratio at 3 Tesla to perform rapid, whole-brain T1-weighted imaging with isotropic 0.

Effect of nitric oxide synthase inhibition on intrarenal oxygenation as evaluated by blood oxygenation level-dependent magnetic resonance imaging.

Objective: To investigate the feasibility of studying renal effects of nitric oxide synthase inhibition (NOSi) in humans by blood oxygenation level-dependent (BOLD) MRI. Nitric oxide (NO) is known to play a key role in the pathophysiology of hypertension and previous reports suggest reduced bioavailability of NO in the kidneys of hypertensive rats and hence show reduced response to NOSi using BOLD MRI. Ability to perform similar studies in humans could potentially lead to detection of early changes before development of symptoms, and to monitor novel interventions targeted toward improved NO bioavailability.

Gadolinium-enhanced off-resonance contrast angiography.

We describe a novel physical basis and methodology for gadolinium (Gd)-enhanced MRA, which we call "off-resonance contrast angiography" (ORCA). Unlike standard contrast-enhanced (CE) MR angiography (MRA), ORCA contrast depends not on T(1) but on Gd-induced shifts in intravascular resonance frequency due to the bulk magnetic susceptibility (BMS) effects of Gd. The method was tested at 3 Tesla in phantoms with a range of dilutions of Gd-DTPA and ultrasmall iron oxide contrast agent (CA).

Lower extremity deep venous thrombosis: evaluation with ferumoxytol-enhanced MR imaging and dual-contrast mechanism--preliminary experience.

Institutional review board approval and informed consent were obtained for this HIPAA-compliant study, whose purpose was to prospectively evaluate the use of a dual-contrast mechanism in conjunction with an iron oxide blood pool contrast agent, ferumoxytol, to depict deep venous thrombosis (DVT). Nine patients with lower extremity DVT detected with duplex ultrasonography (US) were imaged with magnetic resonance (MR) imaging and ferumoxytol. Three techniques, including precontrast two-dimensional time-of-flight (TOF) imaging, ferumoxytol-enhanced bright-blood imaging, and ferumoxytol-enhanced dark-blood imaging, were applied.

Magnetic resonance imaging of the pancreas at 3.0 tesla: qualitative and quantitative comparison with 1.5 tesla.

Objectives: We sought to perform a preliminary comparison of signal-to-noise ratio (SNR) and image quality for magnetic resonance imaging (MRI) of the pancreas at 1.5 and 3 T.

Materials And Methods: Two imaging cohorts were studied using a T2-weighted, single-shot fast spin-echo pulse sequence and a T1-weighted, fat-suppressed 3D gradient-echo pulse sequence.