PROSPECTIVE COMPARISON OF F-18 FDG PET WITH CONVENTIONAL IMAGING MODALITIES (CT, MRI, US) IN LYMPH-NODE STAGING OF HEAD AND NECK-CANCER

The aims of this study were to investigate the detection of cervical l ymph node metastases of head and neck cancer by positron emission tomo graphic (PET) imaging with fluorine-18 fluorodeoxyglucose (FDG) and to perform a prospective comparison with computed tomography (CT), magne tic resonance imaging (MRI), sonographic and histopathological finding s. Sixty patients with histologically proven squamous cell carcinoma w ere studied by PET imaging before surgery. Preoperative endoscopy (inc luding biopsy), CT, MRI and sonography of the cervical region were per formed in all patients within 2 weeks preceding F-18-FDG whole-body PE T, FDG PET images were analysed visually and quantitatively for object ive assessment of regional tracer uptake. Histopathology of the resect ed neck specimens revealed a total of 1284 lymph nodes, 117 of which s howed metastatic involvement. Based on histopathological findings, FDG PET correctly identified lymph node metastases with a sensitivity of 90% and a specificity of 94% (P<10(-6)). CT and MRI visualized histolo gically proven lymph node metastases with a sensitivity of 82% (specif icity 85%) and 80% (specificity 79%), respectively (P<10(-6)). Sonogra phy revealed a sensitivity of 72% (P<10(-6)). The comparison of F-18-F DG PET with conventional imaging modalities demonstrated statistically significant correlations (PET vs CT, P = 0.017; PET vs MRI, P = 0.012 ; PET vs sonography, P = 0.0001). Quantitative analysis of FDG uptake in lymph node metastases using body weight-based standardized uptake v alues (SUVBW) showed no significant correlation between FDG uptake (3. 7+/-2.0) and histological grading of tumour-involved lymph nodes (P = 0.9), Interestingly, benign lymph nodes had increased FDG uptake as a result of inflammatory reactions (SUVBW-range: 2-15.8). This prospecti ve, histopathologically controlled study confirms FDG PET as the proce dure with the highest sensitivity and specificity for detecting lymph node metastases of head and neck cancer and has become a routine metho d in our University Medical Center. Furthermore, the optimal diagnosti c modality may be a fusion image showing the increased metabolism of t he tumour and the anatomical localization.