Topographic metabolic map of head and neck squamous cell carcinoma using 18 F-FDG PET and CT image fusion Denise Takehana Dos Santos, DDS, a Eduardo No ´brega Pereira Lima, MD, b Rubens Chojniak, MD, PhD, c and Marcelo Gusma ˜o Paraiso Cavalcanti, DDS, PhD, d Sa ˜o Paulo, Brazil UNIVERSITY OF SA ˜ O PAULO COLLEGE OF DENTISTRY AND CANCER HOSPITAL Objective. To propose a methodologic approach to evaluate head and neck tumors in order to identify and distinguish areas of higher metabolic activity inside the lesion. Study design. The sample consisted of 17 patients with squamous cell carcinoma of the head and neck. Images were simultaneously acquired using a nondedicated PET-CT device and an independent workstation with ENTEGRA 2 NT software to generate the image fusion between PET and CT. Sites of higher metabolic activity inside the tumor were classified as centric or eccentric according to their relative location to the lesion center. Results. Seventy-seven percent (n = 13) of the patients presented the site of higher metabolic activity at the center of lesion, and in 23% (n = 4) the uptake of the tracer was increased at the periphery of the lesion. Conclusions. This technique gave a realistic view of the functional metabolism, locating the anatomical tumor area and helping in future treatment planning. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100:619-25) Prediction and detection of cancer response to radio- therapy is a challenge in oncology. Most commonly, the treatment planning is based on anatomical aspects such as size and volume of the lesions. Tumor size and volume have a major impact on both treatment deci- sion process and patient outcome. 1-2 The detection of a cancer with a small size or volume, that can be effectively treated, generally results in a more favorable outcome. 3 The precision radiation therapy techniques require accurate tumor identification and delineation. Inaccurate assessment of the target can lead to failure to meet the treatment goals, with a higher probability of tumor recurrence and an additional, unnecessary, radiation burden. 4 Technologic advances have already led to funda- mental improvements used to visualize tumors and to assess their metabolic and physical effects on the body. 5 A number of new developments in diagnostic imaging have potential impact for the detection, diagnosis, staging, and follow-up of cancer patients. Some of the diagnostic imaging developments include computerized tomography (CT), magnetic resonance imaging (MRI), Doppler and endoluminal ultrasound techniques, new contrast and radiopharmaceutical agents, positron emission tomography (PET), single-photon-emission tomography (SPECT), and MR spectroscopy or spec- troscopic imaging. 3,5-8 PET with [ 18 F]2-fluoro-2-deoxy-D-glucose ( 18 F-FDG) provides images that quantitatively portray glucose consumption and therefore lesion metabolic activity, though it presents low anatomical resolution. 3-5,9 Recently, a new diagnostic approach that combines simultaneously acquired x-ray CT and 18 F-FDG PET has been proposed. It can bring an anatomic localiza- tion to metabolic lesion activity, improving diagnostic capabilities. 6-9 The aim of this work therefore was to propose a methodologic approach to evaluate head and neck squa- mous cell carcinoma (SCCA) in order to identify and distinguish areas of higher metabolic activity inside the tumor by combining the functional metabolic and morphologic data simultaneously acquired in a non- dedicated PET-CT device. MATERIAL AND METHODS The study population consisted of 17 patients with SCCA of the head and neck (confirmed by histopath- ologic examination), staged clinically according to the 1988 American Joint Committee on Cancer 10 criteria in Supported by grants from CNPq (Dr Marcelo Cavalcanti, #309331/ 2003-0), Brasilia, Brazil, and funds from CAPES (Dr Denise Santos, PhD fellowship), Brasilia, Brazil. a PhD student, Oral and Maxillofacial Radiology, University of Sa ˜o Paulo College of Dentistry. b Director, Nuclear Medicine Division, Department of Imaging, Cancer Hospital. c Director, Department of Imaging, Cancer Hospital. d Professor, Oral and Maxillofacial Radiology, University of Sa ˜o Paulo College of Dentistry. Adjunct Assistant Professor, Department of Radiology, University of Iowa College of Medicine, Iowa City. Received for publication Dec 16, 2004; returned for revision Feb 22, 2005; accepted for publication Feb 25, 2005. 1079-2104/$ - see front matter Ó 2005 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2005.02.076 619