One Versus Up‑to‑5 Lesion Measurements for Response Assessment by PERCIST in Patients with Lung Cancer / 대한핵의학회잡지

ABSTRACT

Purpose@#The optimal number of lesions to measure for response assessment from fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) is not validated for lung cancer. We compared 1 lesion and up-to-5 lesion measurements for response assessment in lung cancer per PET Response Criteria in Solid Tumors (PERCIST). @*Methods@#Patients with lung cancer with pre- and post-treatment PET/CT images were included. The standard uptake value corrected for lean body mass (SULpeak) of up-to-5 hottest target lesions was measured at each time point. The percent changes of ­SULpeak of the single hottest lesion and the sum of up-to-5 hottest lesions were computed. Pearson correlation coefficient evaluated the strength of association between the percent changes of ­SUL peak values from the 1 lesion and up-to-5 lesion analyses. Response categories were complete metabolic response (CMR) with no perceptible lesion; partial metabolic response (PMR), stable metabolic disease (SMD), or progressive metabolic disease (PMD) using the threshold of 30% and 0.8 unit change in ­SULpeak ; and unequivocal new lesion meant PMD. The concordance for response categorization was assessed by kappa statistics. @*Results@#A total of 40 patients (25 non-small cell lung cancer; 15 small cell lung cancer) were analyzed, all with 18F-FDGavid lung cancer. Average of 3 target lesions were measured for up-to-5 lesion analysis. Pearson’s r was 0.74 (P < 0.001) and increased to 0.96 (P < 0.001) when two outliers were excluded. Response categorization with 1 lesion and up-to-5 lesion analyses was concordant in 37 patients (92.5%, weighted kappa = 0.89). @*Conclusion@#Analyzing 1 lesion and up-to-5 lesions for response assessment by PERCIST showed high concordance in patients with lung cancer.