Objective This study was performed to evaluate the effects of intravenous (i.v.) contrast agent on semi-quantitative values and lymph
node (LN) staging of
18F-fluorodeoxyglucose positron emission tomography/computed tomography (
18F-FDG PET/CT) in patients with lung cancer.
Methods Thirty-five patients with lung cancer were prospectively included. Whole-body PET and nonenhanced CT images were acquired
60 min following the i.v. injection of 370 MBq
18F-FDG and subsequently, enhanced-CT images were acquired with the i.v. administration of 400 mg iodinated contrast agent without
positional change. PET images were reconstructed with both nonenhanced and enhanced CTs, and the maximum and average standardized
uptake values (SUV
max and SUV
ave) calculated from lung masses, LNs, metastatic lesions, and normal structures were compared. To evaluate the effects of the
i.v. contrast agent on LN staging, we compared the LN status on the basis of SUVs (cut-offs; SUV
max = 3.5, SUV
ave = 3.0).
Results The mean differences of SUV
max in normal structures between enhanced and nonenhanced PET/CT were 15.23% ± 13.19% for contralateral lung, 8.53% ± 6.11% for
aorta, 5.85% ± 4.99% for liver, 5.47% ± 6.81% for muscle, and 2.81% ± 3.05% for bone marrow, and those of SUV
ave were 10.17% ± 9.00%, 10.51% ± 7.89%, 4.95% ± 3.89%, 5.66% ± 9.12%, and 2.49% ± 2.50%, respectively. The mean differences
of SUV
max between enhanced and nonenhanced PET/CT were 5.89% ± 3.92% for lung lesions (
n = 41), 6.27% ± 3.79% for LNs (
n = 76), and 3.55% ± 3.38% for metastatic lesions (
n = 35), and those of SUV
ave were 3.22% ± 3.01%, 2.86% ± 1.71%, and 2.33% ± 3.95%, respectively. Although one LN status changed from benign to malignant
because of contrast-related artifact, there was no up- or down-staging in any of the patients after contrast enhancement.
Conclusions An i.v. contrast agent may be used in PET/CT without producing any clinically significant artifact.
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