Magnetic resonance imaging clinics of North America
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Magn Reson Imaging Clin N Am · Nov 2006
ReviewMR imaging evaluation of acute abdominal pain during pregnancy.
MR imaging enables diagnosis of a variety of maternal diseases presenting as acute abdominal pain in pregnant patients. MR imaging is a valuable complement to ultrasound in the determination of the exact etiology of acute abdominal pain, and it is important for the radiologist to recognize the MR imaging appearance of common causes of acute abdominal pain during pregnancy. This article reviews the MR imaging technique and findings of various abnormalities causing acute abdominal pain in pregnant patients.
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Magn Reson Imaging Clin N Am · Aug 2006
ReviewPreoperative MR imaging in patients with breast cancer: preoperative staging, effects on recurrence rates, and outcome analysis.
As well documented for other diseases (ie, lymphoma), an accurate pretherapeutic assessment of the extent of breast cancer is essential for planning the appropriate treatment to get the best long-term results, decrease recurrence rates, and increase patient survival. This article presents an overview of the effects of preoperative local staging with MR imaging in breast cancer patients.
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Some controversy exists over the accuracy and optimal parameters for carotid CE MR angiography at 1.5T. Spatial resolution remains more important than does temporal resolution to address the key question of vessel stenosis, based upon a review of the available literature that compares CE MR angiography with DSA. Specifically, CE MR angiograms with 0.9- to 1.2-mm resolution in all three planes before interpolation have a high reported sensitivity and specificity compared with DSA. ⋯ Future generations of 16- to 32-channel carotid coils should be able to combine the best features of current 4- to 8-channel surface carotid coils and neurovascular coils. These will enable a comprehensive evaluation of the entire course of the carotid artery and detailed carotid bifurcation plaque characterization at 3T within a clinically acceptable 1-hour time frame. This comprehensive carotid artery evaluation with 3T MR imaging would be far superior to that which is possible with US or CT.
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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.