Imaging Technology News - October 2008 - (Page 9)

1.5T and LowField MRI Systems COMPARISON CHART GE Healthcare his comparison chart covers stationary magnetic resonance imaging (MRI) units, including models that have static magnetic fields ranging from lowfield strength, starting at 0.064, to a high-field strength limited to 1.5T. MRI units use strong electromagnetic fields and radiofrequency (RF) radiation to translate hydrogen nuclei distribution in body tissue into computer-generated images of anatomic structures. Magnetic resonance (MR) images have excellent contrast that allows clinicians to clearly see the details of tissue structure, including soft tissue, and to distinguish normal from diseased tissue and thereby diagnose and track the progress and treatment of disease. MRI can acquire images in slices from 0.1 to 400 millimeters thick in the transaxial (transverse), sagittal and coronal planes of the body. Oblique, multiangle oblique and radial slice orientation are also possible. A principal advantage of MRI over radiographic imaging methods is that it does not use ionizing radiation. T An MRI unit consists of a magnet, shimming magnets, an RF transmitter/receiver system with an antenna coil, a gradient system, a patient table, a computer, display monitors and an operator console. Low-field-strength MR imaging as low as 0.064T are useful in imaging extremities. While longer imaging times increase the likelihood of patient movement, resulting in decreased image quality, researchers are working on techniques for improving signal-to-noise ratios (SNR’s) at lower field strengths by manipulating the size of volume elements (voxels). High field-strength MR at 1.5T usually allow for shorter imaging times and higher SNR’s. MR images are obtained by selectively modifying the static magnetic field. Gradient coils produce magnetic fields both in the direction of the static magnetic field and perpendicular to the field. The gradient magnetic fields are used to select a specific anatomic area for imaging and to encode the location of signals received from the slice being imaged. The type of image produced depends on the timing of the RF pulses: altering pulse timing alters the tissue contrast in the resultant image. A standard MRI suite comprises of three main rooms: the procedure room; the equipment room, where the computer and signal generation equipment plus all the electronics needed to run the scanner are kept; and the control room. The suite should be equipped with MR-compatible or MR-safe equipment (see definitions below), defined in the U.S. by the FDA Center for Devices and Radiological Health (CDRH). The two most important planning considerations when selecting the MRI site are the fringe field and the need for a site free from ambient RF electrical noise. A permanent magnet has a minimal fringe field, but its tremendous weight requires careful preconstruction planning. Shielding can be used to contain the magnetic fringe field of resistive and superconducting electromagnetic systems. Without shielding, the fringe field could cause problems at some sites. Both active and passive shielding are used to contain the fringe field. Active shielding is a design feature of the magnet and passive shielding uses steel around the magnet. PARTICIPANTS Aurora Imaging Technology www.auroramri.com GE Healthcare www.gehealthcare.com MRI is primarily used to identify diseases of the central nervous system, brain and spine and to detect musculoskeletal disorders. It is also used to view cartilage, tendons and ligaments, making it useful in diagnosing joint abnormalities. MRI can also be used to image the eyes and the sinuses; to diagnose infectious diseases, such as those associated with AIDS; to detect metastatic liver disease; to display heart wall structure; to stage prostate, bladder and uterine cancer; to evaluate kidney transplant viability and to study marrow diseases. MRI is also used in conjunction with other modalities to localize treatment areas for stereotactic radiosurgical and image-guided surgical procedures. MRA is used for imaging vascular and arterial malformations, thromboses, stenoses and other vascular abnormalities and for evaluating the carotid artery and cerebral vasculature. Breast MRI is most commonly used to determine the nature of lesions discovered by conventional mammography. Contrast-agent-enhanced breast MRI can reduce the number of biopsies in women with abnormal mammograms. MRI can also be used for staging breast cancer, as well as for ruling out residual or recurrent cancer and for treatment planning. Hitachi Medical Systems America www.hitachimed.com Hologic Inc. www.hologic.com Philips Healthcare www.medical.philips.com Siemens Medical Solutions www.usa.siemens.com/medical Toshiba America Medical Systems www.medical.toshiba.com Definitions: MR safe — the device, when used in the MR environment, has been demonstrated to present no additional risk to the patient, but may affect the quality of the diagnostic information. MR compatible — the device, when used in the MR environment, is MR safe and has been demonstrated to neither significantly affect the quality of the diagnostic information nor have its operations affected by the MR device. CDRH Magnetic Resonance Working Group draft document. Reilly Communications Group obtained the model specifications from the manufacturers. The chart outline and introduction are from the Healthcare Product Comparison System (HPCS) published by ECRI Institute, a non-profit health services research agency. HPCS is a comprehensive database of brand-name model specifications for more than 450 types of devices available in three ways: online, CD-ROM, or print editions. For more information, contact ECRI Institute at (610) 825-6000, Ext. 5265; eMail: hpcs@ecri.org; or visit www.ecri.org. Editor’s Note: Due to space constraints, Imaging Technology News was not able to include all submitted product information in the printed version of this chart. However, all submitted information appears on our Web site at ITNonline.net. The “+” at the end of entries signifies more information is available online. Comparison Chart Conducted by Reilly Communications Group Reilly Communications Group assumes no responsibility or liability for any errors or omissions in this chart. Please direct all chart inquiries to: charts@rcgpubs.com Open and fold out or remove for wall display ITNonline.net | October 2008 | ITN | 9 http://www.ITNonline.net http://www.auroramri.com http://www.gehealthcare.com http://www.hitachimed.com http://www.hologic.com http://www.medical.philips.com http://www.usa.siemens.com/medical http://www.medical.toshiba.com http://www.ITNonline.net http://www.ecri.org http://www.ITNonline.net

Table of Contents Feed for the Digital Edition of Imaging Technology News - October 2008

Imaging Technology News - October 2008 Contents RSNA Low-Field MRI Systems Contrast Media Injectors AM-LCDs Special Report - Agents Target Neurological Diseases and Disorders IT Laser Imagers Monitors Meet Radiology Suite Needs MR Guides Ultrasound in Outpatient Treatments Replacing a Legacy PACS PACS SAs: Titles and Salaries

Imaging Technology News - October 2008

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