Correlation of 18F-fluorodeoxyglucose uptake on positron emission tomography with Ki-67 index and pathological invasive area in lung adenocarcinomas 30 mm or less in size

Abstract

Background 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is commonly used to distinguish benign from malignant lesion. Recently, maximum standardized uptake value (SUVmax) on FDG-PET has found to have prognostic value. We examined the relationship between SUVmax and proliferative activities as indicated by maximum diameter of tumor opacity on mediastinal-window images (TOM), Ki-67 index, and diameter of the pathological invasive area in lung adenocarcinomas ≤30 mm. Methods Thin-section computed tomography (TS-CT) and FDG-PET were performed on 140 patients with resectable lung adenocarcinomas ≤30 mm between March 2006 and May 2008. Tumors were classified as air-type or solid-type based on TS-CT findings. In all resected specimens, diameter of the pathological invasive area and Ki-67 index were assessed. Results SUVmax was significantly lower for air-type than for solid-type tumors (0.97 vs. 3.96, p < 0.0001). In solid-type tumors, SUVmax correlated with diameter of TOM ( r = 0.450, p < 0.0001), Ki-67 index ( r = 0.567, p < 0.0001), and diameter of the pathological invasive area ( r = 0.672, p < 0.0001). In multiple regression analysis, SUVmax correlated significantly with Ki-67 index and diameter of the pathological invasive area but not with diameter of TOM. The cut-off value of SUVmax for predicting invasive area >5 mm was determined as 2.15 by ROC analysis, with sensitivity of 88.3% and specificity of 84.6%. Conclusions SUVmax correlated significantly with Ki-67 index and diameter of the pathological invasive area. The present results suggest the potential role of FDG-PET in predicting adenocarcinomas with invasive characteristics.