The Difference in Maximum Standardized Uptake Value among Lung Adenocarcinomas Located at the Upper and Lower Zone on PET/CT

Background: Findings on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) are surrogate markers of malignancy in lung adenocarcinoma. Breathing during PET/CT can substantially reduce the maximum standardized uptake value (maxSUV) of lung tumors when they are located at the lower zone (LZ).

Objectives: We assessed whether lung cancer location influences the malignancy predicted by maxSUV.

Methods: 608 patients with clinical stage IA lung adenocarcinoma had been preoperatively examined by PET/CT and high-resolution computed tomography (HRCT). We evaluated the clinicopathological characteristics of these patients and the accuracy of precognition obtained by maxSUV between the upper zone (UZ, n = 395) and the LZ (n = 213). maxSUV was also analyzed for matched pairs between the two groups.

Results: The mean maxSUV in the LZ group was significantly lower than that in the UZ group (1.98 ± 1.73 vs. 2.44 ± 2.43, respectively; p = 0.0145). The receiver operating characteristics curve of maxSUV for predicting high-grade malignancy (lymphatic, vascular, pleural invasion, or lymph node metastasis) was larger for the UZ group than for the LZ group [0.89, 95% confidence interval (CI) 0.86-0.93, vs. 0.82, 95% CI 0.76-0.88]. Analysis for maxSUV of 213 pairs matched for the solid component size on HRCT, pathological characteristics, and gender revealed that maxSUV in the LZ group was significantly lower than that in the UZ group (1.98 ± 1.73 vs. 2.47 ± 2.39, respectively; p < 0.001).

Conclusions: maxSUV of a tumor in the LZ group is apparently lower than the value which reflects the potential malignancy of a tumor. We have to carefully consider these facts when selecting the appropriate surgical procedure for lung cancer with PET/CT and HRCT.