ORIGINAL ARTICLE FDG PET in Detecting Primary and Recurrent Malignant Salivary Gland Tumors Tevfik Fikret Cermik, MD, Ayse Mavi, MD, Gunsel Acikgoz, MD, Mohamed Houseni, MD, Simin Dadparvar, MD, and Abass Alavi, MD Purpose: The aim of this study was to assess the role of PET in the management of patients with primary malignant salivary gland (SG) tumor. Material and Methods: Sixty-one FDG PET studies in 48 patients (median age 58, range 28 – 89 years, 20 female, 28 male) who were diagnosed with malignant SG tumors were retrospectively analyzed. Thirteen were referred for initial diagnosis and staging while there was a suspicion of recurrence and/or metastatic disease in 48 patients during the follow-up period. Results: On PET examinations of 13 patients on initial presentation, 12 showed increased uptake in the primary lesion, while conven- tional methods (CT, MRI) were positive in 11 and were equivocal for 2 patients. Six patients with multiple nodal and 2 patients with distant metastases were detected by PET. Conventional methods demonstrated lymph node metastases in 5 of these patients. In the follow-up patient group, PET was inaccurate (false-negative or positive) in 4 (8%) patients with local recurrence, and in 4 (8%) with metastatic disease. However, 15 (31%) studies for recurrence and 7 (15%) for metastasis were false-negative with conventional radio- logic methods. The sensitivity, specificity, and positive and negative predictive values for the detection of recurrent disease were 83%, 93%, 63%, and 98% for PET; 67%, 69%, 24%, and 94% for conventional methods, respectively. Overall sensitivity, specificity, positive and negative predictive values of PET for detecting meta- static disease were 93%, 96%, 82%, and 99%, while those of conventional methods were 80%, 95%, 75%, and 96%, respectively. Conclusion: These results demonstrate that FDG PET is not only superior to CT and/or MRI for staging at the initial presentation but also superior to conventional imaging methodologies for detecting local recurrence and regional lymph node and distant metastases in patients with malignant SG tumor. Key Words: salivary gland, parotid, malignant tumor, FDG PET, recurrence, metastasis (Clin Nucl Med 2007;32: 286 –291) M alignant salivary gland (SG) tumors are uncommon and constitute about 3%–5% of all head and neck malig- nancies. Approximately 85% of salivary gland tumors arise in the parotid gland and about 25% of these tumors are malig- nant. 1 Surgery and radiation therapy are the main treatment modalities for patients with primary malignant tumors and local lymph node metastases in SG tumors. Traditional diag- nostic and staging procedures of salivary gland tumors in- clude physical examination, radiologic modalities such as computed tomography (CT), magnetic resonance imaging (MRI), neck sonography (US), and fine-needle aspiration biopsy (FNAB). Fine-needle aspiration biopsy is used for the initial diagnosis of SG lesions, but this technique has a limited role in the later stages of the disease. 2 F-18 fluoro- deoxyglucose (FDG) positron emission tomography (PET) imaging has proven to be useful in the initial diagnosis, staging, monitoring response to therapy and the detection of tumor recurrence of a variety of malignancies. 3,4 Based on reports in the literature, PET has been used for the assessment of primary SG tumors. 5–7 However, the role of PET in the initial diagnosis of these malignancies appears to be limited because of a high false-positive rate. 5,6 Also, there is only a single publication in the literature about the role of FDG PET for detecting recurrence or metastases during the follow-up period and includes only patients with a primary malignant SG tumor. 8 The aim of this study was to assess the role of PET in the management of patients with malignant SG tumors at the initial staging and in the follow-up period. MATERIALS AND METHODS Patient Population In our institution, 48 consecutive patients (median age 58, range 28 – 89 years, 20 F, 28 M) with malignant primary SG tumors (45 parotid and 3 submandibular) underwent FDG PET imaging between May 2000 and April 2006. We retro- spectively analyzed 61 FDG PET scans and radiologic studies of these patients. Patients were divided into 2 groups. FDG PET was performed for the assessment of the primary tumor for initial staging in the first group, which included 13 patients. In the second group, comprising 37 patients, 48 FDG PET studies were performed for the detection of recur- rence as well as loco-regional and distant metastases in the follow-up period. Two patients had both an initial and a follow-up PET examination, 3 patients had 3 follow-up, and 5 patients had 2 follow-up PET studies. All patients under- Received for publication July 15, 2006; accepted December 27, 2006. From the Department of Radiology, Division of Nuclear Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA. Reprints: Abass Alavi, MD, Division of Nuclear Medicine, Hospital of the University of Pennsylvania, 3400 Spruce St., 110 Donner Bldg., Phila- delphia, PA 19104. E-mail alavi@rad.upenn.edu. Copyright © 2007 by Lippincott Williams & Wilkins ISSN: 0363-9762/07/3204-0286 Clinical Nuclear Medicine • Volume 32, Number 4, April 2007 286