Scoutless stepping-table peripheral contrast-enhanced MR angiography.

Purpose: To evaluate the feasibility of a scoutless method, termed EZ-STEP, for stepping-table peripheral contrast-enhanced magnetic resonance angiography (CE-MRA).

Materials And Methods: This scoutless method involves the use of a stepping-table, fast 3D MRA acquisition that incorporates spatially nonselective radiofrequency (RF) pulses for excitation to reduce the repetition time (TR). The sequence was tested in a phantom.

Effect of free radical scavenger (tempol) on intrarenal oxygenation in hypertensive rats as evaluated by BOLD MRI.

Purpose: To demonstrate a differential response following administration of a free radical scavenger, tempol, in kidneys of hypertensive compared to normotensive rats.

Material And Methods: Data were obtained in spontaneously hypertensive rats (SHR, N = 5). Wistar-Kyoto rats (WKY, N = 6) were used as normotensive controls.

First-pass contrast-enhanced magnetic resonance angiography in humans using ferumoxytol, a novel ultrasmall superparamagnetic iron oxide (USPIO)-based blood pool agent.

Purpose: To evaluate the feasibility of first-pass contrast-enhanced magnetic resonance angiography (MRA) using ferumoxytol in humans.

Materials And Methods: First-pass and equilibrium phase MRA were performed using ferumoxytol in one healthy volunteer and 11 patients with a fast three-dimensional spoiled gradient recalled (SPGR) pulse sequence. The examined vessels included carotid arteries, thoracic aorta, abdominal aorta, and peripheral arteries.

Relapsing-remitting multiple sclerosis: metabolic abnormality in nonenhancing lesions and normal-appearing white matter at MR imaging: initial experience.

Purpose: To quantify, with three-dimensional proton magnetic resonance (MR) spectroscopy, metabolic characteristics of normal-appearing white matter and nonenhancing lesions in patients with relapsing-remitting multiple sclerosis (MS).

Materials And Methods: Institutional review board approval and informed patient consent were obtained. Nine patients with relapsing-remitting MS (six women, three men) and nine age-matched control subjects (seven women, two men) were studied with T1- and T2-weighted MR imaging and three-dimensional proton MR spectroscopy at spatial resolution less than a cubic centimeter.

Myocardial delayed enhancement imaging using inversion recovery single-shot steady-state free precession: initial experience.

Purpose: To evaluate the feasibility of using an inversion recovery single-shot steady-state free precession (SS_SSFP) sequence for myocardial delayed enhancement (MDE) imaging, and to compare SS_SSFP with the conventional inversion recovery segmented fast gradient echo (IR_FGRE) technique.

Materials And Methods: Ten subjects (four volunteers and six patients with suspected or known coronary disease) were included in this study. All subjects were scanned with both IR_FGRE and SS_SSFP sequences 15-25 minutes after gadopentetate dimeglumine injection.

Dark flow artifacts with steady-state free precession cine MR technique: causes and implications for cardiac MR imaging.

Steady-state free precession cine images from cardiac magnetic resonance imaging studies of 24 patients were reviewed retrospectively to identify dark flow artifacts. The cause and features of the artifacts were studied in flow phantom experiments. Dark flow artifacts were recognized in eight of the 24 cases and were characterized by low or inhomogeneous signal intensity in blood pools with little change in adjacent tissues.

Metabolite ratios to assumed stable creatine level may confound the quantification of proton brain MR spectroscopy.

In localized brain proton MR spectroscopy ((1)H-MRS), metabolites' levels are often expressed as ratios, rather than as absolute concentrations. Frequently, their denominator is the creatine [Cr], which level is explicitly assumed to be stable in normal as well as in many pathologic states. The rationale is that ratios self-correct for imager and localization method differences, gain instabilities, regional susceptibility variations and partial volume effects.

Diffusely elevated cerebral choline and creatine in relapsing-remitting multiple sclerosis.

It is well known that multiple sclerosis (MS) pathogenesis continues even during periods of clinical silence. To quantify the metabolic characteristics of this activity we compared the absolute levels of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the normal-appearing white matter (NAWM) between relapsing-remitting (RR) MS patients and controls. Metabolite concentrations were obtained with 3D proton MR spectroscopy at 1.

Brain metabolite profiles of T1-hypointense lesions in relapsing-remitting multiple sclerosis.

Background And Purpose: Persistent T1-hypointense lesions ("black holes") are thought to represent permanent damage of brain parenchyma. We attempted to ascertain whether the metabolic profiles of these hypointense areas support this hypothesis and whether these profiles correlate with these hypointense findings.

Methods: Four patients with relapsing-remitting multiple sclerosis and four matched control volunteers underwent MR imaging and 3D proton MR spectroscopy.

Relapsing-remitting multiple sclerosis and whole-brain N-acetylaspartate measurement: evidence for different clinical cohorts initial observations.

Purpose: To quantify the rate of concentration decline of neuronal marker N-acetylaspartate (NAA) in the entire brain of patients with relapsing-remitting multiple sclerosis (MS) in relation to healthy age-matched control subjects.

Materials And Methods: Whole-brain NAA (WBNAA) concentration was quantified in 49 patients with relapsing-remitting MS by using magnetic resonance (MR) imaging and proton MR spectroscopy. It was statistically analyzed by using Spearman rank correlation coefficients to test the intragroup relationship between WBNAA and Expanded Disability Status Scale (EDSS) score and Mann-Whitney analyses to test for differences between subgroups' EDSS scores versus previously published WBNAA values for healthy subjects, disease duration, and age.

Whole-brain N-acetylaspartate concentration: correlation with T2-weighted lesion volume and expanded disability status scale score in cases of relapsing-remitting multiple sclerosis.

Background And Purpose: The T2-weighted MR imaging total lesion volume and Expanded Disability Status Scale (EDSS) score are two common measures of relapsing-remitting multiple sclerosis disability and pathologic abnormality. Because the whole-brain N-acetylaspartate concentration is considered to be a new marker of the disease burden, the purpose of this study was to evaluate the relationship among these three measures.

Methods: The whole-brain N-acetylaspartate concentration and T2-weighted lesion volume were quantified by using MR imaging and proton MR spectroscopy in 49 patients with relapsing-remitting multiple sclerosis (36 female and 13 male patients; average age, 39 years; age range, 24-55 years; average EDSS score, 2; range of EDSS scores, 0-6).

Reproducibility of 3D proton spectroscopy in the human brain.

The inter- and intrasubject reproducibility of the metabolite levels of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho), obtained with three-dimensional (3D) multivoxel proton spectroscopy (1H-MRS), was analyzed in eight healthy volunteers. Serial, back-to-back measurements on a phantom showed the methodology and instrumentation to be highly reproducible, with a median coefficient of variation (CV) of 3.8%.