Differentiation of an adrenal mass in patients with non-small cell lung cancer by means of a normal range of adrenal standardized uptake values on FDG PET/CT

Abstract

OBJECT: The aim of this study was to assess the range of normal adrenal FDG uptake, and to determine the diagnostic criteria of FDG PET-CT to differentiate adrenal nodule.

METHODS: A total of 117 healthy subjects who underwent FDG PET/CT for cancer screening, and 106 lung cancer patients who underwent FDG PET/CT for cancer staging without adrenal abnormality were enrolled to determine the normal range of adrenal standardized uptake value (SUV). In addition, another 24 lung cancer patients with suspicious adrenal masses were enrolled to evaluate the diagnostic performance of the different diagnostic criteria from FDG PET/CT.

RESULTS: The adrenal maximal SUV (SUVmax) of the healthy group was 1.66 ± 0.21 in the right and 1.86 ± 0.30 in the left. The adrenal SUVmax of lung cancer group was 1.79 ± 0.30 in the right and 1.90 ± 0.37 in the left. Lung cancer group had a higher ratio of adrenal gland to liver (AL ratio) when compared with healthy subjects (0.77 ± 0.13 vs. 0.61 ± 0.10 on the right, 0.82 ± 0.12 vs. 0.68 ± 0.12 on the left: p < 0.001). The upper normal limits of adrenal SUVmax were calculated as the mean plus 2 standard deviations (right: 2.08 vs. 2.39, left: 2.46 vs. 2.64, in the normal group and lung cancer group, respectively). Using the upper limit from the lung cancer group, we achieved a sensitivity of 87 % and specificity of 100 %.

CONCLUSION: We demonstrated that left adrenal gland had higher SUV than right adrenal gland both in healthy group and lung cancer group. Using the different normal range of bilateral adrenal SUVmax, we could successfully differentiate adrenal masses.