TY - JOUR T1 - Assessment of Simplified Methods to Measure <sup>18</sup>F-FLT Uptake Changes in EGFR-Mutated Non–Small Cell Lung Cancer Patients Undergoing EGFR Tyrosine Kinase Inhibitor Treatment JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1417 LP - 1423 DO - 10.2967/jnumed.114.140913 VL - 55 IS - 9 AU - Virginie Frings AU - Maqsood Yaqub AU - Lieke L. Hoyng AU - Sandeep S.V. Golla AU - Albert D. Windhorst AU - Robert C. Schuit AU - Adriaan A. Lammertsma AU - Otto S. Hoekstra AU - Egbert F. Smit AU - Ronald Boellaard AU - for the QuIC-ConCePT Consortium Y1 - 2014/09/01 UR - http://jnm.snmjournals.org/content/55/9/1417.abstract N2 - 3′-deoxy-3′-18F-fluorothymidine (18F-FLT) PET/CT provides a noninvasive assessment of proliferation and, as such, could be a valuable imaging biomarker in oncology. The aim of the present study was to assess the validity of simplified quantitative parameters of 18F-FLT uptake in non–small cell lung cancer (NSCLC) patients before and after the start of treatment with a tyrosine kinase inhibitor (TKI). Methods: Ten patients with metastatic NSCLC harboring an activating epidermal growth factor receptor mutation were included in this prospective observational study. Patients underwent 15O-H2O and 18F-FLT PET/CT scanning on 3 separate occasions: within 7 d before treatment, and 7 and 28 d after the first therapeutic dose of a TKI (gefitinib or erlotinib). Dynamic scans were acquired and venous blood samples were collected during the 18F-FLT scan to measure parent fraction and plasma and whole-blood radioactivity concentrations. Simplified measures (standardized uptake value [SUV] and tumor-to-blood ratio [TBR]) were correlated with fully quantitative measures derived from kinetic modeling. Results: Twenty-nine of thirty 18F-FLT PET/CT scans were evaluable. According to the Akaike criterion, a reversible 2-tissue model with 4 rate constants and blood volume parameter was preferred in 84% of cases. Relative therapy-induced changes in SUV and TBR correlated with those derived from kinetic analyses (r2 = 0.83–0.97, P &lt; 0.001, slope = 0.72–1.12). 18F-FLT uptake significantly decreased at 7 and 28 d after the start of treatment compared with baseline (P &lt; 0.01). Changes in 18F-FLT uptake were not correlated with changes in perfusion, as measured using 15O-H2O. Conclusion: SUV and TBR could both be used as surrogate simplified measures to assess changes in 18F-FLT uptake in NSCLC patients treated with a TKI, at the cost of a small underestimation in uptake changes or the need for a blood sample and metabolite measurement, respectively. ER -