Prone position [F-18]FDG PET/CT to reduce respiratory motion artefacts in the evaluation of lung nodules

Abstract

Objectives 2-Deoxy-2-[F-18]fluoro-D-glucose ([F-18]FDG) positron-emission tomography/computed tomography (PET/CT) is widely used to evaluate lung nodules, although respiratory motion artefacts may occur. We investigated the value of prone position PET/CT (pPET/CT) in lung nodule evaluation compared with standard supine position PET/CT (sPET/CT). Methods We retrospectively reviewed 28 consecutive patients (20 men; age, 65.6 +/- 12.1 years) with a lung nodule (size, 16.8 +/- 5.5 mm) located below the sub-carinal level who underwent [F-18]FDG PET/CT in a standard supine position and additional prone position. The maximum standardised uptake value (SUVmax), metabolic tumour volume (MTV), difference of diaphragm position between PET and CT (DDP), Dice's similarity coefficient (DSC) and occurrence of mis-registration were analysed. The [F-18]FDG uptake of 20 biopsy-confirmed (15 malignant) nodules was evaluated visually. Results pPET/CT yielded a significantly higher SUVmax, lower MTV and shorter DDP than with sPET/CT (p = 0.043, 0.007 and 0.021, respectively). Mis-registration occurred in 53.6% of cases in sPET/CT and in 28.6% of cases in pPET/CT (p = 0.092). Among the 15 patients with mis-registration in sPET/CT, 10 patients (66.7%) did not show mis-registration in pPET/CT. DSC was higher in pPET/CT than in sPET/CT in 18 out of 28 patients (64.3%). In visual analysis, malignant nodules exhibited a higher [F-18]FDG uptake positivity than benign nodules in pPET/CT (93.3% vs. 40.0%, p = 0.032) but not in sPET/CT (80.0% vs. 40.0%, p = 0.131). Conclusions pPET/CT reduces respiratory motion artefact and enables more-precise measurements of PET parameters.