Magnetic resonance imaging clinics of North America
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Body MR imaging at 3T is in its infancy, and should improve substantially over the next several years. Radiologists need to be aware of several limitations that are based on the laws of physics: Overall, the gain in SNR at 3T will be less than twofold (without protocol alteration) compared with a standard 1.5T MR system because of the increase in T'I'1 at ultra high field. Typically, the gain in SNR is greater in T2-weighted sequences than in TI-weighted sequences, because longer TRs allow for a more complete recovery of the longitudinal magnetization, and T2 is independent of Bo. ⋯ Therefore, fetal MR imaging generally should not be performed at 3T because of these artifacts and the increased safety concerns. The same holds true for patients with a large amount of ascites, who also are not well suited for an ultrahigh-field MR examination. Except as noted above, most patients can undergo an abdominal MR imaging study at 3T with a reasonable outcome in terms of image quality.
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Magn Reson Imaging Clin N Am · Feb 2006
Review3T MR imaging of the musculoskeletal system (Part II): clinical applications.
The gain in SNR that is afforded by 3T MR imaging systems has tremendous clinical applications in the musculoskeletal system. The potential for demonstrating and enhancing the visibility of normal osseous, tendinous, cartilaginous, and ligamentous structures is exciting. Furthermore, harnessing this added signal to increase spatial resolution may improve our diagnostic abilities in various joints dramatically. ⋯ Because of the enhanced SNR, the higher spatial resolution, and the greater CNR of intrinsic joint structures at higher field strengths, 3T MR imaging has the potential to improve diagnostic abilities in the musculoskeletal system vastly, which translates into better patient care and management. The author's 2 years of clinical experience with musculoskeletal MR imaging on 3T systems has met and exceeded his expectations, and has bolstered the confidence of his orthopedic surgeons in his diagnoses. As coil technology advances and as the use of parallel imaging becomes more available in the extremities, the author expects to see even more dramatic improvements in image quality.
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Magn Reson Imaging Clin N Am · Feb 2006
Review3T MR imaging of the musculoskeletal system (Part I): considerations, coils, and challenges.
As 3T MR imaging systems become more wide-spread in the clinical realm, a full understanding of the opportunities for image improvement and the limitations in the applications of the signal gain is needed. It is clear that even with current coil technology, much of the gain in signal can be harnessed effectively; however, continued coil development is necessary to realize the full potential of 3T, especially with the wonderful synergy that can be achieved with the use of parallel imaging and multiple-channel phased-array extremity coils. ⋯ This creates excellent opportunities to improve image quality, spatial resolution, and diagnostic accuracy in the musculo-skeletal system. From the author's experience, the superb image quality has impressed referring orthopedic surgeons, and the reduction in scan time has resulted in greater patient satisfaction and reduced anxiety.
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This article reviews the complex normal anatomy of the hip joint and its surrounding structures on MR imaging, including MR arthrography. Thorough knowledge of the normal appearance of the marrow and osseous and articular anatomy as well as the ligaments, tendons, and surrounding muscles of the hip is essential for imaging diagnosis.
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Magn Reson Imaging Clin N Am · Aug 2005
ReviewMR imaging-controlled focused ultrasound ablation: a noninvasive image-guided surgery.
The history of MR-guided FUS demonstrates the need for merging advanced therapy technology with advanced imaging. Without the ability of MR imaging to localize the tumor margins and without the temperature-sensitive imaging that provides the closed-loop control of energy deposition, this method is inadequate for most clinical applications. Given these limitations,high-intensity focused ultrasound initially appeared to have a narrow application area and was not able to compete with other surgical or ablation methods. ⋯ It is uniquely applicable for image-guided therapy using targeted drug delivery methods and gene therapy. Further advances in this technology will no doubt improve energy deposition and reduce treatment times. In the near future, FUS will offer a viable alternative to conventional surgery and radiation therapy; in the longer-term, it may also enable a host of targeted treatment methods aimed at eradicating or arresting heretofore intractable diseases such as certain brain malignancies and forms of epilepsy.