Whole-body FDG positron emission tomographic imaging for staging esophageal cancer - Comparison with computed tomography

Purpose: The aim of the authors in this study was to critically evaluate th e role of whole-body positron emission tomographic (PET) imaging with fluor ine-18 fluorodeoxyglucose (FDG) in staging esophageal cancer, and further t o compare this method with conventional imaging with computed tomography (C T). Materials and Methods: The authors performed independent, blinded retrospec tive evaluations of FDG PET images obtained in 47 patients referred for the initial staging of esophageal cancer before minimally invasive surgical st aging. Twenty PET studies from patients with nonesophageal thoracic cancers were randomly selected for inclusion in the PET readings. In a subset of 3 7 of 47 cases, the PET findings were compared with independent readings of CT studies acquired within the same 6-week interval, The utility of the ima ging findings was evaluated using a high-sensitivity interpretation (i.e., assigning equivocal findings as positive) and a low-sensitivity interpretat ion (i.e., assigning equivocal findings as negative). Results: PET was less sensitive (41% in high-sensitivity mode, 35% in low-s ensitivity mode) than CT (63% to 87%) for diagnosing tumor involvement in l ocoregional lymph nodes, which was identified by surgical assessment in 72% of patients. Notable, however, was the greater specificity of PET-determin ed nodal sites (10 approximately 90%) compared with CT (14% to 43%). In det ecting histologically proved distant metastases (n = 10), PET performed con siderably better when applied in the high-sensitivity mode, with a sensitiv ity rate of approximately 70% and a specificity rate of more than 90% in th e total group and in the subset of patients with correlative CT data, In th e low-sensitivity mode, CT identified only two of seven metastatic sites, w hereas the high-sensitivity mode resulted in an unacceptably high rate of f alse-positive readings (positive predictive value, 29%). PET correctly iden tified one additional site of metastasis that was not detected by CT. Conclusions: The relatively low sensitivity of PET for identifying locoregi onal lesions precludes its replacement of conventional CT staging. However, the primary advantage of PET imaging is its superior specificity for tumor detection and improved diagnostic value for distant metastatic sites, feat ures that may substantially affect patient management decisions. In conclus ion, PET imaging is useful in the initial staging of esophageal cancer and provides additional and complementary information to that obtained by CT im aging.