¹⁸F-fluorodeoxyglucose uptake on positron emission tomography in mucinous adenocarcinoma

Background: The prognostic value of maximum standardized uptake value (maxSUV) on ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) is known for localized pulmonary adenocarcinoma, which is most commonly non-mucinous adenocarcinoma. We examined the validity of thin-section computed tomography (TS-CT) and FDG-PET findings in mucinous adenocarcinoma. Materials and Methods: TS-CT and FDG-PET were performed on 25 patients with mucinous lung adenocarcinoma that was subsequently resected between January 2009 and March 2013. Based on the percentage reduction of maximum tumor diameter on the mediastinal window image compared with the diameter on the lung window image on TS-CT, tumors were classified as air-type (≥50%) or solid-type (<50%). All resected specimens were pathologically diagnosed according to the International Association for the Study of Lung Cancer (IASLC) classification, and the diameter of the pathological invasive area was assessed. Results: Most mucinous adenocarcinomas were located in the lower lobe. All except two were classified as solid-type tumor on TS-CT. Multiple regression analysis revealed the correlation of maxSUV with pathological tumor size and diameter of pathological invasive area; these two parameters showed no significant correlation with each other (r = 0.354, p = 0.083). maxSUV was significantly lower for tumors with invasive area ≤5 mm than for tumors with invasive area >5 mm (1.62 vs. 3.77, p = 0.01), but no statistically significant difference was found in terms of other pathological invasive findings such as the presence of lymphatic or vascular invasion, pleural involvement, or predominant histological subtype. Conclusions: Most mucinous adenocarcinomas had appearances of solid-type tumor on TS-CT. maxSUV on FDG-PET indicates the pathological invasive area in mucinous adenocarcinoma as well as non-mucinous adenocarcinoma