Seminars in musculoskeletal radiology
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Semin Musculoskelet Radiol · Apr 2015
ReviewThree-dimensional MR neurography of the lumbosacral plexus.
The lumbosacral (LS) plexus is a complicated network of nerves, and the complex anatomy is resolvable using high-resolution three-dimensional (3D) magnetic resonance neurography. This article focuses on 3D imaging evaluation of the anatomy and the pathology of various LS plexus branch nerves.
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MR neurography (MRN) has evolved to become a clinically useful imaging modality for evaluating nerve pathologies. Anatomically, nerves are often surrounded by fat and blood vessels, which appear bright on MR images impeding the conspicuity of nerve visualization. ⋯ These advancements enabled optimized imaging protocols for better visualization of the nerves. This review article discusses some of these technical advancements that enabled current MRN protocols in routine clinical imaging and certain research techniques that may facilitate nerve disorder characterization following interventions.
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Pathologic conditions of the brachial plexus often result in serious and disabling complications. With the increasing availability and use of new and powerful MRI sequences and coils, understanding and assessment of the complex anatomy and pathology of the brachial plexus have been greatly facilitated. ⋯ The main characteristics of pathologic conditions affecting the brachial plexus are discussed and illustrated, as well as their differential diagnoses, with an emphasis on key imaging findings and relevance for patient management. Pitfalls related to suboptimal technique and image interpretation are also addressed.
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Molecular and cellular imaging of neuropathic pain, utilizing the myriad of receptors and inflammatory mediators involved in nociceptive activity, is a promising approach toward objectively identifying peripheral pain generators. Neuropathic conditions arise from injured and inflamed nerves, which have been shown to elaborate several molecular and cellular elements that give rise to the neuropathic phenotype and can be exploited for imaging purposes. ⋯ By combining the sensitivity and specificity of molecular imaging with the high anatomical, spatial and contrast resolution afforded by computed tomography and MRI, radiologists can potentially identify sites of nerve injury or neuroinflammation that are implicated as peripheral pain drivers with greater accuracy and confidence. In addition to guiding therapy, these approaches will aid in new drug designs for analgesia and more individualized treatment options.
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Diffusion tensor imaging (DTI) is a powerful MR imaging technique that can be used to probe the microstructural environment of highly anisotropic tissues such as peripheral nerves. DTI has been used predominantly in the central nervous system, and its application in the peripheral nervous system does pose some challenges related to imaging artifacts, the small caliber of peripheral nerves, and low water proton density. However advances in MRI hardware and software have made it possible to use the technique in the peripheral nervous system and to obtain functional data relating to the effect of pathologic processes on peripheral nerves. This article reviews the imaging principles behind DTI and examines the literature regarding its application in assessing peripheral nerves.