[Differentiation of malignant and benign superficial lymph nodes by dual time point 18F-FDG PET]

To evaluate the value of dual time point 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in differentiating malignant and benign superficial lymph nodes.

Sixty-eight patients with ninety superficial lymph nodes were examined. Whole body 18F-FDG PET imaging was performed one hour (early) after FDG injection and repeated one hour (delayed) later but only for the interesting areas. The maximum standardized uptake value (SUVmax) was determined for each of the node on both early and delayed images (SUV early and SUV delayed, respectively). Retention index (RI) was then calculated. The cutoff values of SUV early, SUV delayed and RI were determined by receiver operating characteristic (ROC) analyses. The efficacy of each parameter was also analyzed by ROC analyses.

The histopathology examinations confirmed 51 malignant nodes and 39 benign nodes. The SUV early (x +/- s) for benign nodes and malignant nodes were 3.26 +/- 1.62 and 8.04 +/- 5.56, respectively (P=0.000). The SUV delayed for benign nodes and malignant nodes were 3.93 +/- 2.11 and 9.82 +/- 6.29, respectively (P=0.000). The RI for benign nodes and malignant nodes were 19.1 +/- 22.5 and 24.8 +/- 18.8, respectively (P=0.191). The cutoff values of SUV early, SUV delayed and RI were 4.3, 4.8 and 18, respectively. The cutoff values of SUV early, SUV delayed and RI produced a sensitivity of 71%, 78% and 63%, a specificity of 87%, 85% and 46%, and an accuracy of 78%, 80% and 57%, respectively. The ROC analyses illustrated that the diagnostic efficacy of SUV early, SUV delayed was higher than RI (P<0.001). However, there was no difference in diagnostic efficacy between SUV early, and SUV delayed (P=0.409).

Dual-time point 18F-FDG PET does differentiate benign and malignant superficial lymph nodes effectively.