Motion-compensated FDG PET/CT for oesophageal cancer

Purpose Respiratory-induced motion of oesophageal tumours and lymph nodes can influence positron-emission tomography/computed tomography (PET/CT). The aim was to compare standard three-dimensional (3D) and motion-compensated PET/CT regarding standardized uptake value (SUV), metabolic tumour volume (MTV) and detection of lymph node metastases. Methods This prospective observational study (NCT02424864) included 37 newly diagnosed oesophageal cancer patients. Diagnostic PET/CT was reconstructed in 3D and motion-compensated PET/CT. MTVs of the primary tumour were calculated using an automated region-growing algorithm with SUV thresholds of 2.5 (MTV2.5) and ≥ 50% of SUVmax (MTV50%). Blinded for reconstruction method, a nuclear medicine physician assessed all lymph nodes showing 18 F‑fluorodeoxyglucose uptake for their degree of suspicion. Results The mean (95% CI) SUVmax of the primary tumour was 13.1 (10.6–15.5) versus 13.0 (10.4–15.6) for 3D and motion-compensated PET/CT, respectively. MTVs were also similar between the two techniques. Bland–Altman analysis showed mean differences between both measurements (95% limits of agreement) of 0.08 (−3.60–3.75), −0.26 (−2.34–1.82), 4.66 (−29.61–38.92) cm 3 and −0.95 (−19.9–18.0) cm 3 for tumour SUVmax, lymph node SUVmax, MTV2.5 and MTV50%, respectively. Lymph nodes were classified as highly suspicious (30/34 nodes), suspicious (20/22) and dubious (66/59) for metastases on 3D/motion-compensated PET/CT. No additional lymph node metastases were found on motion-compensated PET/CT. SUVmax of the most intense lymph nodes was similar for both scans: mean (95% CI) 6.6 (4.3–8.8) and 6.8 (4.5–9.1) for 3D and motion-compensated, respectively. Conclusion SUVmax of the primary oesophageal tumour and lymph nodes was comparable on 3D and motion-compensated PET/CT. The use of motion-compensated PET/CT did not improve lymph node detection.