No clinically relevant differences between positron emission tomography (PET) reconstructions based on low-dose or contrast-enhanced CT in combined integrated multiphase (18) F-Fluorethylcholine PET/CT for prostate cancer.

Objectives: To qualitatively and quantitatively compare the reconstructions of F-18-Fluorethylcholine (FCH) positron emission tomography (PET) based on the non-enhanced X-ray computed tomography (neCT) and contrast-enhanced CT (ceCT) acquired in integrated PET/CT in prostate cancer (PCA) patients. Methods: We retrospectively analysed FCH-PET/CTs of 63 PCA patients. PET images were reconstructed using either neCT or ceCT for attenuation correction. Contrast-enhancement (HU) and mean and maximum standardised FDG uptake (SUVmean and SUVmax) were measured at eight anatomical sites, and PET images were evaluated for image quality and patient staging by two independent observers. Results: At all anatomical sites the HU values were significantly higher in the ceCT than in the neCT. This in turn led to increases in SUVmean and SUVmax that, although small in both absolute and relative terms, were highly consistent and thus statistically highly significant. However, assessment of the FCH-PET images reconstructed using either neCT or ceCT revealed no differences between observers or reconstructions with regard to patient staging (all kappa = 1.0: excellent agreement; P = 1.0). Minor visual differences without clinical relevance were seen in 21 scans by observer 1 and in 22 scans by observer 2 (kappa = 0.68, P < 0.001). Conclusions: There is no clinically relevant difference between reconstruction of PET images based on ceCT or neCT in FCH-PET/CT in patients with prostate cancer. Small quantitative differences exist, but do not lead to clinically relevant differences in visual quality or clinical assessment of patients. Therefore, CT scan may be used for attenuation correction.