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A method is proposed to estimate signal-to-noise ratio (SNR) values in phased array magnitude images, based on a region-of-interest (ROI) analysis. It is shown that the SNR can be found by correcting the measured signal intensity for the noise bias effects and by evaluating the noise variance as the mean square value of all the pixel intensities in a chosen(More)
A technique for transperineal high-dose-rate (HDR) prostate brachytherapy and needle biopsy in a standard 1.5 T MRI scanner is demonstrated. In each of eight procedures (in four patients with intermediate to high risk localized prostate cancer), four MRI-guided transperineal prostate biopsies were obtained followed by placement of 14-15 hollow transperineal(More)
OBJECTIVES We sought to determine the feasibility and potential of transesophageal magnetic resonance imaging (TEMRI) for quantifying atherosclerotic plaque burden in the aortic arch and descending thoracic aorta in comparison with transesophageal echocardiography (TEE). BACKGROUND Improved morphologic assessment of atherosclerotic plaque features in vivo(More)
Introduction: MRI provides excellent soft-tissue contrast and promises to improve image-guided prostate interventions, presently performed with ultrasound [1,2]. MRI-guided transperineal prostate biopsy has been demonstrated inside an open MRI scanner [3]. Transrectal prostate biopsy has been demonstrated inside a high-field MR scanner utilizing passive(More)
The purpose of this study was to develop a non-invasive method of imaging the thoracic aorta that would provide both morphological detail within the aortic wall and information about regional aortic wall motion. An esophageal probe is described that allows transesophageal MR imaging (TEMRI) of the thoracic aorta and has several potential advantages over the(More)
We have developed a method that can measure high-energy phosphate metabolite concentrations in humans with 1D resolved surface-coil NMR spectroscopy. The metabolites are measured by phosphorus (31P) NMR spectroscopy, and the tissue water proton (1H) resonance from the same volume serves as an internal concentration reference. The method requires only the(More)
Recently, intravascular catheter probes have been developed to increase signal-to-noise ratio (SNR) for MR imaging of blood vessels. Miniaturization of these catheter probes without degrading their performances is very critical in imaging small vessels such as coronary arteries. Catheter coils have a loop incorporated in their structure and have limitations(More)
With the rapid growth of interventional MRI, radiofrequency (RF) heating at the tips of guidewires, catheters, and other wire-shaped devices has become an important safety issue. Previous studies have identified some of the variables that affect the relative magnitude of this heating but none could predict the absolute amount of heating to formulate safety(More)