Magnetic Resonance Imaging of the Knee: Optimizing 3 Tesla Imaging

Abstract

IntroductionMagnetic resonance imaging (MRI), with its multiplanar capabilities and excellent soft-tissue contrast, has established itself as the leading modality for noninvasive evaluation of the musculoskeletal system (1-5). It is regarded as the top imaging and diagnostic tool for the knee joint as a result of its ability to evaluate a wide range of anatomy and pathology varying from ligamentous injuries to articular cartilage lesions. Imaging of the knee requires excellent contrast, high resolution and the ability to visualize very small structures, all of which can be provided by MR imaging. The development of advanced diagnostic MR imaging tools for the joints is of increased clinical importance as it has been recently shown that musculoskeletal imaging is the most rapidly growing field in MR imaging, second only to neuroradiology applications (6).Currently, most clinical evaluation of the musculoskeletal system is performed at intermediate field strengths of 1.5 T or lower. High field systems, like 3.0 T, are now becoming increasingly available for clinical use. Although at first used primarily for neurological imaging, an increasing number of studies have demonstrated the abilities and advantages of 3.0 T systems in musculoskeletal imaging (7-10). The most notable advantage includes an increased signalto-noise ratio (SNR) which can lead to a shorter imaging time or improved image resolution. However, with the increase to a 3.0 T field strength comes a various number of considerations that must be dealt with in order to optimize its intrinsically superior imaging capabilities.Advantages of using 3.0 T 3.0 T imaging is of special interest to the musculoskeletal system due to the increased MR signal and higher SNR. SNR is a function of the main magnetic field strength, the volume of tissue being imaged and the radiofrequency coil used. Therefore if the tissue volume imaged and coil used remain the same, the transition from 1.5 T to 3.0 T should result in twice the intrinsic SNR. This increase in SNR then allows for up to four times faster image acquisition on multiple-average scans or double the resolution in one direction. Positive clinical applications abound. The increase in scan speed has the ability to provide for increased patient © 2010 Elsevier Inc. All rights reserved.Corresponding author: Garry Gold, MD, Department of Radiology, Grant Building Room SO68B, Stanford, CA 94305, gold@stanford.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Shortly after the introduction of 3.0 T imaging capabilities several researchers began studies in an attempt to invest...

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