INTERESTING IMAGE 18 F-FDG PET/CT in Tumefactive Multiple Sclerosis Anna Margherita Maffione, MD,* Lucia Rampin, MD,* Gaia Grassetto, MD,* Roberto L’Erario, MD,Þ Patrick M Colletti, MD,þ and Domenico Rubello, MD* Abstract: A 35-year-old man underwent contrast-enhanced MRI and 18FFDG PET/CT for acute peripheral paresthesia, vision loss, muscle weakness, and difficulty walking. T2-weighted MRI demonstrated multiple bright periventricular supratentorial and infratentorial white matter lesions, including 2 with nodularity. Both nodular lesions showed moderate focal FDG uptake (SUVmax, 6.9 in both cases). Cerebrospinal fluid analysis showed increased levels of immunocytes and oligoclonal antibody bands. A diagnosis of acute onset tumefactive multiple sclerosis was made. Key Words: PET, multiple sclerosis, MRI, FDG, active plaque (Clin Nucl Med 2014;39: 750Y751) Received for publication January 15, 2014; revision accepted February 12, 2014. From the Departments of *Nuclear Medicine, PET Unit, and †Neurology, Santa Maria della Misericordia Hospital, Rovigo, Italy; and ‡Department of Radiology, University of Southern California, Los Angeles, CA. Conflicts of interest and sources of funding: none declared. Reprints: Domenico Rubello, MD, Department of Nuclear Medicine, Santa Maria della Misericordia Hospital, Rovigo, Italy, Viale Tre Martiri, 140, 45100 Rovigo, Italy. E-mail: domenico.rubello@libero.it. Copyright * 2014 by Lippincott Williams & Wilkins ISSN: 0363-9762/14/3908Y0750 750 www.nuclearmed.com REFERENCES 1. Lakhanpal SK, Maravilla JR. Multiple sclerosis. In: Stark DD, Bradley WG, eds. Magnetic Resonance Imaging. 3rd ed. St Louis, MO: Mosby; 1999. 2. Altintas A, Petek B, Isik N, et al. Clinical and radiological characteristics of tumefactive demyelinating lesions: follow-up study. Mult Scler. 2012;18: 1448Y1453. 3. Chen W, Silverman DH, Delaloye S, et al. 18F-FDOPA PET imaging of brain tumors: comparison study with 18F-FDG PET and evaluation of diagnostic accuracy. J Nucl Med. 2006;47:904Y911. 4. Gay FW, Drye TJ, Dick GW, et al. The application of multifactorial cluster analysis in the staging of plaques in early multiple sclerosis. Identification and characterization of the primary demyelinating lesion. Brain. 1997;120(Pt 8): 1461Y1483. 5. Adams CW, Poston RN, Buk SJ. Pathology, histochemistry and immunocytochemistry of lesions in acute multiple sclerosis. J Neurol Sci. 1989;92:291Y306. 6. Niccolini F, Su P, Politis M. Positron emission tomography in multiple sclerosis. Clin Nucl Med. 2014. [Epub ahead of print]. 7. Kiferle L, Politis M, Muraro PA, et al. Positron emission tomography imaging in multiple sclerosis-current status and future applications. Eur J Neurol. 2011;18: 226Y231. 8. Bakshi R, Miletich RS, Kinkel PR, et al. High-resolution fluorodeoxyglucose positron emission tomography shows both global and regional cerebral hypometabolism in multiple sclerosis. J Neuro Imag. 1998;8:228Y234. Clinical Nuclear Medicine & Volume 39, Number 8, August 2014 Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Clinical Nuclear Medicine & Volume 39, Number 8, August 2014 18 F-FDG PET/CT in Tumefactive Multiple Sclerosis FIGURE 1. A 35-year-old man presented with acute peripheral paresthesia, vision loss, muscle weakness, and difficulty walking. Left, T2-weighted MRI demonstrates bilateral multifocal deep white matter lesions with a nodular lesion in the white matter of the right parietal lobe (arrow) surrounded by edema characterized by an open ring sign that is relatively specific for demyelination. Findings are typical for multiple sclerosis (MS).1,2 Right, Transaxial 18F-FDG PET/CT at the same level demonstrates a corresponding moderate (SUVmax, 6.9) focal FDG uptake (arrow). FIGURE 2. Left, T2-weighted MRI also demonstrates bilateral multifocal deep white matter lesions with a nodular lesion in the white matter of the left parietal lobe (arrow) surrounded by edema with a dark ring sign that is again relatively specific for demyelination. Right, 18F-FDG PET/CT demonstrates a corresponding moderate (SUVmax, 6.9) focal FDG uptake (arrow). Because it is composed chiefly of long-range myelinated axon tracts with relatively few cell bodies, white matter accumulates minimal FDG.3 Multiple sclerosis is an inflammatory demyelinating disease typically characterized by multiple lesions of different age. Lymphocytic infiltration has been proposed as the primary event in the genesis of the MS plaque.4 In the natural history of MS, active plaques are characterized by hypercellularity, lymphocytic perivascular infiltration, and macrophage infiltration, whereas inactive plaques are hypocellular with reactive gliosis.5 In the acute phase of MS, focal FDG uptake in correspondence with nodular lesions may be associated with hypercellular plaques.6Y8 * 2014 Lippincott Williams & Wilkins www.nuclearmed.com Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 751