Hindawi Publishing Corporation Case Reports in Medicine Volume 2013, Article ID 791078, 4 pages http://dx.doi.org/10.1155/2013/791078 Case Report PET/MRI for Preoperative Planning in Patients with Soft Tissue Sarcoma: A Technical Report of Two Patients Annika Loft, 1 Karl Erik Jensen, 2 Johan Löfgren, 1 Søren Daugaard, 3 and Michael M. Petersen 4 1 Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark 2 Department of Radiology, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark 3 Department of Pathology, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark 4 Department of Orthopedic Surgery, Rigshospitalet, University Hospital of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark Correspondence should be addressed to Michael M. Petersen; m.m.petersen@dadlnet.dk Received 8 August 2013; Revised 2 October 2013; Accepted 17 October 2013 Academic Editor: Grigorios Korosoglou Copyright © 2013 Annika Lotet al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Clinical positron emission tomography (PET)/magnetic resonance imaging (MRI) acquisition protocols may improve the evaluation of sot tissue sarcomas (STS) prior to surgical planning. We examined two patients with lower extremity STS using a Siemens Biograph mMR PET/MRI scanner and the glucose analogue 18F-luoro-deoxyglucose (FDG). We investigated clinically relevant tumor volumes and evaluated the relations to skeletal periosteum and nerve bundles. he patient scans suggest that FDG PET/MRI improved the edge detection, and invasion of tumor tissue into important adjacent anatomical structures can be evaluated. FDG PET/MRI also provided additional information compared to conventional Gadolinium enhanced MR imaging. he indings were proven by subsequent pathological examination of the resected tumor tissue. In the future, clinical FDG PET/MRI may be an important modality for preoperative planning, including radiation therapy planning in patients with STS. 1. Introduction Sot tissue sarcomas (STS) comprise a heterogeneous group of mesenchymal derived tumors. Historically, the primary treatment for most STS is surgical excision with a wide mar- gin, and amputation if a wide margin cannot be obtained [1]. However, over the past decades, it has been accepted by many surgeons to use also less mutilating limb-sparing operative procedures because when combined with external radiation therapy, marginal or even intralesional margins in STS surgery oten provide an acceptable local tumor control [2, 3]. In the preoperative planning and workup of STS patients, Gadolinium enhanced magnetic resonance imaging (MRI) is the current gold standard. Although conventional MRI ofers an excellent sot-tissue contrast and is the most versatile modality in musculoskeletal imaging, there are limitations concerning the exact deinition of tumor iniltration into the peritumoral edema and the adjacent structures, which is essential for therapy planning. Moreover, oncologic therapy monitoring and follow-up ater treatment remain challeng- ing. In Gadolinium enhanced MRI, edge detection is still afected by peritumoral inlammation and edema which leads to overestimation of tumor volume and extension. If major blood vessels, major nerve bundles, or bones are close to the tumor, it could lead to overestimation of invasive growth and hereby result in major surgical intervention or amputation. Hence, a more precise and speciic imaging method may reduce the morbidity following sarcoma surgery. he new hybrid positron emission tomograph combined with a 3 Tesla (T) MRI scanner (PET/MRI) provides the possibility for simultaneous PET/MRI and combines the highly sensitive molecular imaging capability of PET with the superior sot-tissue contrast of MR imaging [4, 5]. he purpose of our study was to evaluate the tumor delineation by use of clinical PET/MRI performed in two