14. FDG CDET (2D Dual-Head Coincidence Gamma Camera) in the Primary Staging of Oesophageal Cancer

Purpose: The aim of this study was to evaluate the role of FDG-CDET for the detection of primary oesophageal tumour, lymph node involvement and distant extension before surgery.

Methods and patients: In patients fasting for 6h or more, 150-250 MBq of ¹⁸F-FDG were injected i.v. and 2D imaging (whole-body scan and at least a tomoscintigram) was started 45 min. later, using a PICKER gamma camera. We studied 14 patients (pts). All of them were operated on (mean time between FDG and surgery: 5.4 ± 3.8 days) and staging results were correlated with post surgical histology.

Results: The primary lesion took up FDG in all cases but one (FN in a 5 mm lesion). The primary NM staging of these 14 pts was negative with FDG-CDET in 7 cases (4 TN and 3 FN corresponding to an invasion of satellite lymph nodes in 2 cases and to a metastatic infracentimetric subdiaphragmatic lymph node in one case) and positive in 7 cases (7 TP corresponding to 10 foci), revealing in 4 cases a sub-diaphragmatic lymph node extension unknown prior to FDG-CDET. One pt referred for characterisation of an oesophageal lesion (failure of multiple biopsies) had an intense focus of FDG uptake in this area (TP confirmed by surgery). The overall sensitivity was 13/14 = 93% on a per patient basis and 21/25 = 84% on a per lesion basis. Specificity on a per lesion basis was 5/5 = 100%.

Conclusion: These first results, obtained in an indication of FDG not frequently evaluated even with dedicated PET systems, seem very promising, the oesophageal neoplastic lesions appearing to take up FDG with a high intensity.