Magnetic Resonance Imaging (MRI)

PURPOSE: To quantify dynamic enhancement of breast lesions with echo-planar and conventional magnetic resonance (MR) imaging, to correlate these data with histologic findings and vessel density, and to evaluate
MATERIALS AND METHODS: Twenty female patients with 22 breast lesions underwent conventional and MR echo-planar imaging T1 values, change in gadopentetate dimeglumine concentration, and extraction-flow products were calculated with echo-planar imaging data and were correlated with histologic findings and microvessel density.

BACKGROUND: Development of techniques for percutaneous closure of atrial septal defects (ASDs) makes accurate noninvasive sizing of ASDs important for appropriate patient selection.

Previously, we have developed a colloidal dextran-stabilized monocrystalline iron oxide nanocompound (MION-46) as a magnetic label for magnetic resonance imaging (MRI). In an effort to use this magnetic label to visualize pancreatic receptor function by MRI in vivo, we investigated the potential of secretin as a vector molecule. Secretin receptors, abundant on exocrine pancreas cells, recognize secretin through its amidated carboxyl terminal.

Functional magnetic resonance imaging exploits deoxygenated blood as an endogenous source for contrast in assessing local changes in tissue perfusion. Intrinsic changes in myocardial signal intensity were measured during dipyridamole induced coronary vasodilatation with T2*-weighted echo planar MRI in healthy volunteers. Concurrently, changes in flow velocity in the left anterior descending coronary artery were measured using a time-of-flight method. Dipyridamole infusion produced 14 +/- 6% increase in myocardial signal intensity (n = 7).

The purpose of this study was to investigate the dependence of contrast-to-noise ratio (CNR) on the dose and rate of sprodiamide injection in magnetic resonance relative cerebral blood volume (rCBV) imaging. rCBV maps for 35 normal volunteers were constructed from dynamic MR image sets acquired with echo-planar spin-echo imaging after intravenous injection of sprodiamide. Doses of .1, .2, and .3 mmol/kg, at rates of 2 ml/second and 5 ml/second, were tested. CNRs and blood/volume ratios of gray to white matter were computed. CNR depended on dose (P

AIM: This feasibility study explores relative myocardial perfusion characterization with an investigational T2/T2 contrast agent.
METHODS: Dysprosium-DTPA bis (methylamide) was administered peripherally in six patients with thallium defects. Rest and stress multi-section, gated, T2-weighted images were acquired with a 1.5 T echo-planar imager. Change in transverse relaxation rate was calculated in four segments for each subject.

BACKGROUND: New tests, such as magnetic resonance imaging (MRI) and electron-beam computed tomography (CT), are being developed for the diagnosis of coronary artery disease.
OBJECTIVE: To determine the conditions that a new test must meet to be a cost-effective alternative to established imaging tests.
DESIGN: Decision model and cost-effectiveness analysis.
DATA SOURCES: Literature review and meta-analysis.
TARGET POPULATION: 55-year-old men and 65-year-old women presenting with chest pain.
TIME HORIZON: Lifetime of the patient.

PURPOSE: To use diffusion-sensitive magnetic resonance (MR) imaging to obtain images of fiber orientation in vivo and to map fiber shortening in humans by means of integrating such data with strain images.

Cardiac MRI studies often show susceptibility artifacts along the inferoapical myocardial margin in both human and in vivo animal experiments at field strengths of 1.5T and greater. This study was designed to determine the cause of these artifacts in porcine myocardium at 3T. Gradient echo images were obtained under various anatomic and physiologic conditions to systematically study potential sources of local susceptibility gradients. Lung resection in the open-chested, euthanized swine was the only intervention that eliminated the artifact.