Quantitative Parametric Perfusion Images Using 15O-Labeled Water and a Clinical PET/CT Scanner: Test–Retest Variability in Lung Cancer

Quantification of tumor perfusion using radioactive water (H215O) and PET is a promising method for monitoring treatment with antiangiogenic agents. However, use of dynamic H215O scans together with a fully 3-dimensional clinical PET/CT scan-ner needs to be validated. The purpose of the present study was to assess validity and reproducibility of dynamic H215O PET/CT scans for measuring tumor perfusion and validate the quantitative accuracy of parametric perfusion images. Methods: Eleven patients with non–small cell lung cancer were included in this study. Patients underwent 2 dynamic H215O (370 MBq) PET scans on the same day. During the first scan, arterial blood was withdrawn continuously. Input functions were derived from blood sampler data and the ascending aorta as seen in the images themselves (image-derived input function [IDIF]). Parametric perfusion images were computed using