PT  - JOURNAL ARTICLE
AU  - Weber, Wolfgang A.
AU  - Gatsonis, Constantine A.
AU  - Mozley, P. David
AU  - Hanna, Lucy G.
AU  - Shields, Anthony F.
AU  - Aberle, Denise R.
AU  - Govindan, Ramaswamy
AU  - Torigian, Drew A.
AU  - Karp, Joel S.
AU  - (Michael) Yu, Jian Q.
AU  - Subramaniam, Rathan M.
AU  - Halvorsen, Robert A.
AU  - Siegel, Barry A.
TI  - Repeatability of <sup>18</sup>F-FDG PET/CT in Advanced Non–Small Cell Lung Cancer: Prospective Assessment in 2 Multicenter Trials
AID  - 10.2967/jnumed.114.147728
DP  - 2015 Aug 01
TA  - Journal of Nuclear Medicine
PG  - 1137--1143
VI  - 56
IP  - 8
4099  - http://jnm.snmjournals.org/content/56/8/1137.short
4100  - http://jnm.snmjournals.org/content/56/8/1137.full
SO  - J Nucl Med2015 Aug 01; 56
AB  - PET/CT with the glucose analog 18F-FDG has several potential applications for monitoring tumor response to therapy in patients with non–small cell lung cancer (NSCLC). A prerequisite for many of these applications is detailed knowledge of the repeatability of quantitative parameters derived from 18F-FDG PET/CT studies. Methods: The repeatability of the 18F-FDG signal was evaluated in 2 prospective multicenter trials. Patients with advanced NSCLC (tumor stage III–IV) underwent two 18F-FDG PET/CT studies while not receiving therapy. Tumor 18F-FDG uptake was quantified by measurement of the maximum standardized uptake value within a lesion (SUVmax) and the average SUV within a small volume of interest around the site of maximum uptake (SUVpeak). Analysis was performed for the lesion in the chest with the highest 18F-FDG uptake and a size of at least 2 cm (target lesion) as well as for up to 6 additional lesions per patient. Repeatability was assessed by Bland–Altman plots and calculation of 95% repeatability coefficients (RCs) of the log-transformed SUV differences. Results: Test–retest repeatability was assessed in 74 patients (34 from the ACRIN 6678 trial and 40 from the Merck MK-0646-008 trial). SUVpeak was 11.57 ± 7.89 g/mL for the ACRIN trial and 6.89 ± 3.02 for the Merck trial. The lower and upper RCs were −28% (95% confidence interval [CI], −35% to −23%) and +39% (95% CI, 31% to 54%) in the ACRIN trial, indicating that a decrease of SUVpeak by more than 28% or an increase by more than 39% has a probability of less than 2.5%. The corresponding RCs from the Merck trial were −35% (95% CI, −42% to −29%) and +53% (95% CI, 41% to 72%). Repeatability was similar for SUVmax of the target lesion, averaged SUVmax, and averaged SUVpeak of up to 6 lesions per patient. Conclusion: The variability of repeated measurements of tumor 18F-FDG uptake in patients with NSCLC is somewhat larger than previously reported in smaller single-center studies but comparable to that of gastrointestinal malignancies in a previous multicenter trial. The variability of measurements supports the definitions of tumor response according to PET Response Criteria in Solid Tumors.