Accuracy of a new diagnostic tool in deep infiltrating endometriosis: Positron emission tomography-computed tomography with 16α-[18F]fluoro-17β-estradiol

Aim: Preoperative workup of deep infiltrating endometriosis is limited in the evaluation of extragenital and extrapelvic disease and in distinguishing between the previous surgical scar and active lesion. Histological verification remains the gold standard for diagnosis. The aimof this study was therefore to evaluate positron emission tomography-computed tomography (PET/CT) with an experimental estrogen receptor tracer (16 alpha-[18F] fluoro-17 beta-estradiol; [18F] FES) for accurate staging and non-invasive diagnosis of the disease. The primary endpoint was the feasibility of this tool on comparison with histology. The secondary endpoint was the accuracy of PET/CT in comparison with magnetic resonance imaging (MRI). Methods: Four eligible subjects with extragenital endometriosis underwent MRI, PET/CT with [18F] FES, and laparoscopic excision of endometriosis in the same month. Region-by-region analysis was used to compare the findings of the two diagnostic tools with surgical histological specimens obtained during laparoscopy. Results: A total of 40 anatomical regions were examined: seven were [18F] FES positive, four were positive on MRI and eight positive on histology. A total of nine regions were discordant. PET/CT agreed with histology in 9/9 of the discrepant findings. Conclusion: PET/CT with [18F] FES was feasible and had greater accuracy than MRI, particularly in patients with previous surgery. Further studies are needed, however, to investigate its role in bowel endometriosis in sites other than recto-sigmoid junction, nerve localization, and subcentimetric disease.