Positron emission tomography (PET) in the management of oro-pharyngeal cancer

Basic principles and applications of (18)F-FDG-PET/CT in oral and maxillofacial imaging: A pictorial essay

A combination of positron emission tomography (PET) with ¹⁸F-labeled fluoro-2-deoxyglucose (¹⁸F-FDG) and computed tomography (¹⁸F-FDG-PET/CT) has increasingly become a widely used imaging modality for the diagnosis and management of head and neck cancer. On the basis of both recent literature and our professional experience, we present a set of principles with pictorial illustrations and clinical applications of FDG-PET/CT in the evaluation and management planning of squamous cell carcinoma of the oral cavity and oropharynx. We feel that this paper will be of interest and will aid the learning of oral and maxillofacial radiology trainees and practitioners.

18F-fluorodeoxyglucose positron emission tomography to evaluate cervical node metastases in patients with head and neck squamous cell carcinoma: a meta-analysis

BACKGROUND

Positron emission tomography using 18F-fluorodeoxyglucose (18F-FDG PET) has been proposed to enhance preoperative assessment of cervical lymph node status in patients with head and neck squamous cell carcinoma (HNSCC). Management is most controversial for patients with a clinically negative (cN0) neck. We aimed to assess the diagnostic accuracy of 18F-FDG PET in detecting lymph node metastases in patients with HNSCC.

METHODS

We performed a meta-analysis of all available studies of the diagnostic performance of 18F-FDG PET in patients with HNSCC. We determined sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR-), and constructed summary receiver operating characteristic curves using hierarchical regression models. We also compared the performance of 18F-FDG PET with that of conventional diagnostic methods (ie, computed tomography, magnetic resonance imaging, and ultrasound with fine-needle aspiration) by analyzing studies that had also used these diagnostic methods on the same patients.

RESULTS

Across 32 studies (1236 patients), 18F-FDG PET sensitivity was 79% (95% confidence interval [CI] = 72% to 85%) and specificity was 86% (95% CI = 83% to 89%). For cN0 patients, sensitivity of 18F-FDG PET was only 50% (95% CI = 37% to 63%), whereas specificity was 87% (95% CI = 76% to 93%). Overall, LR+ was 5.84 (95% CI = 4.59 to 7.42) and LR- was 0.24 (95% CI = 0.17 to 0.33). In studies in which both 18F-FDG PET and conventional diagnostic tests were performed, sensitivity and specificity of 18F-FDG PET were 80% and 86%, respectively, and of conventional diagnostic tests were 75% and 79%, respectively.

CONCLUSION

18F-FDG PET has good diagnostic performance in the overall pretreatment evaluation of patients with HNSCC but still does not detect disease in half of the patients with metastasis and cN0.

[Role of PET-CT with 18-FDG in the management of UADT squamous-cell carcinomas: a retrospective study of 43 cases]

INTRODUCTION

The aim of our retrospective study was to evaluate the role of PET-CT in the management of upper-aerodigestive tract (UADT) squamous-cell carcinomas.

MATERIAL AND METHODS

Our study included 43 patients with UADT squamous-cell carcinomas having undergone PET-CT for: initial staging (n=20), diagnosis of recurrent disease (n=16), and response to treatment (n=7).

RESULTS

PET-CT diagnosed distant metastases missed by conventional imaging in four patients (20%) in initial staging, four patients (25%) in diagnosis of recurrent disease, and two patients (29%) in response to treatment. Overall, PET-CT induced a shift in the management of 10 patients (28%).

DISCUSSION

Our study and other publications suggest that PET-CT should be used in: initial staging in Stage III and IV; detection of recurrent disease; and evaluation of treatment response.

Head and Neck Cancer: Dedicated FDG PET/CT Protocol for Detection—Phantom and Initial Clinical Studies

PURPOSE

To retrospectively compare the sensitivity of a dedicated fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) protocol versus a standard whole-body PET/CT protocol for detection of head and neck cancer, with biopsy and follow-up as reference standards.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained for this HIPAA-compliant study. Dedicated and standard PET/CT protocols were performed in a phantom and in 55 patients suspected of having head and neck cancer (28 men, 27 women; age range, 21-79 years). The neck phantom contained four 4.4-9.8-mm-diameter spheres. Standard protocol consisted of a midcranium to proximal thigh emission scan of 2-4 minutes per bed position. Dedicated protocol was an 8-minute head and neck scan. Reconstructed field of view and pixel size, respectively, were 30 cm and 2.34 mm for the dedicated and 50 cm and 3.91 mm for the standard protocol. FDG uptake was evaluated visually and semiquantitatively by using standardized uptake values (SUVs). Mean SUV was compared between dedicated and standard protocols with a t test modified for clustered sampling. Receiver operating characteristic (ROC) curves were calculated. A two-tailed P value was used.

RESULTS

In the phantom study, a larger percentage difference (20%-27%) in sphere-to-background ratios with the dedicated than with the standard protocol was observed for 6.0-9.8-mm spheres. In the clinical study, a total of 149 lymph nodes were identified. Five malignant and six benign lymph nodes (mean diameter, 7.1 mm) were visually identified with the dedicated protocol only. SUVs with the dedicated protocol were significantly higher than those with the standard protocol (P<.001). Area under the ROC curve was 0.94 for the dedicated and 0.92 for the standard protocol (P=.56).

CONCLUSION

FDG PET with either the standard or dedicated protocol was more sensitive than CT for evaluating head and neck lymph nodes. The dedicated protocol improved the detectability of smaller nodes.