The Method and Efficacy of 18F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography for Diagnosing the Lymphatic Metastasis of Colorectal Carcinoma

Abstract

The aim of this study was to analyze the morphologic and functional features of metastatic lymph nodes of colorectal carcinoma on (18)F-fluorodeoxyglucose positron emission tomographic (PET)/computed tomographic (CT) images and correlate these with pathologic results to explore the best diagnostic performance. Sixty-eight patients without any previous treatment underwent (18)F-fluorodeoxyglucose PET/CT examinations and subsequent operations. All lymph nodes were evaluated by recording short diameter and maximum standardized uptake value (SUVmax) on axial images and were carefully verified on the surgically resected specimens. The radiologic diagnostic efficacies on the basis of different diagnostic criteria were compared and evaluated with pathologic results. There was a significant difference for SUVmax between metastatic and benign juxtaintestinal lymph nodes (F = 96.836, P = .000) and a correlation between size and SUVmax in metastatic juxtaintestinal lymph nodes (r = 0.352, P = .038). Diagnosing according to short diameter ≥ 10 mm and SUVmax ≥ 2.5, the sensitivity, specificity, positivity prediction value (PPV), and negative prediction value (NPV) were 10.00%, 98.26%, 66.67%, and 75.84% and 82.50%, 90.43%, 75.00%, and 93.69%, respectively. Considered together, the sensitivity, specificity, PPV, and NPV were 10.00%, 99.13%, 80.00%, and 76.00%, respectively. Receiver-operating characteristic curves showed that the best cutoff values for SUVmax and short diameter were 2.0 and 4.85 mm, respectively; the corresponding sensitivity, specificity, PPV, and NPV, were 91.43%, 87.83%, 69.57%, and 97.12% and 85.71%, 60.87%, 40.00%, and 98.2%, respectively. Considered together, the sensitivity, specificity, PPV, and NPV were 95.00%, 86.96%, 71.70%, and 98.04%, respectively. Fluorine-18-fluorodeoxyglucose uptake was a more reliable indicator in diagnosing malignant juxtaintestinal lymph node of colorectal carcinoma. The optimal diagnostic efficacy could be reached by considering morphologic and functional features together.