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Optimized Imaging of the Postoperative Spine 2014

Category General Spine Idoia Corcuera-Solano, MD Anne McLellan Simon Daniel Vivek Joshi, MD Varsha Subramaniam, BA Lawrence Tanenbaum Purpose There are few imaging tasks more challenging than optimizing evaluations of the instrumented spine secondary to artifacts induced by implanted metal devices on MRI and CT examinations. MRI artifacts are primarily due to volume magnetic susceptibility mismatch between metal devices and tissue. In CT the issues are beam hardening and streak artifacts. 1. To review the essential techniques for optimization of MR and CT imaging of the postoperative spine 2. To explain the nature and cause of artifacts that hinder evaluations of the instrumented spine 3. To demonstrate the value of advanced CT techniques such as dual energy in imaging the postoperative spine. 4. To demonstrate the value of novel MR sequences such as chemical shift, and multispectral imaging in imaging the postoperative spine. Materials & Methods Content Organization 1. Brief review of the principles underlying optimized imaging for postoperative spine focusing on key technical factor adjustments, the value of innovations such as dual energy CT, and new MR techniques such as metal artifact reduction and chemical shift imaging. 2. Illustration cases with stepwise implementation of optimizations will be presented. 3. Highlight the advantages and pearls of the new imaging methods. 4. Discuss the potential pitfalls and limitations of basic and advanced techniques. Results Images demonstrating acquisitions utilizing thin slice, minimal pitch, higher definition/oversampling and iterative reconstruction are compared to images without these features. Results with dual energy CT including multiple types of dual or single sources (sequential and layered) images are compared to standard non dual energy. Optimum MR sequences including higher bandwidth, long echo train, small voxels, fast spin echo and adjusting the frequency coding directions, are showcased. Advanced fast supression tecniques with chemical shift fat supression rather than STIR sequences are compared. Advanced multispectral Imaging methodsincluding hybrid tecniques with examples of MAVRIC (GE), SEMAC (Siemens), Ultra-Short time to echo are presented with examples. Conclusion Conclusion (And Teaching points) Applying fundamental principles in postoperative spine CT and MR studies can significantly improve image quality. Newer and soon to be available enhancements further reduce the negative effects associated with metal implants, thus optimizing image quality. References 1. Stradiotti P, Curti A, Castellazzi G, Zerbi A. Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art. European Spine Journal, June 2009, Volume 18, Issue 1 Supplement, pp 102-108 2. Srinivasan A, Hoeffner E, Ibrahim M, Shah G, LaMarca F, Suresh K. 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