Visual and quantitative evaluation of [18F]FES and [18F]FDHT PET in patients with metastatic breast cancer: an interobserver variability study

Abstract

Purpose: Correct identification of tumour receptor status is important for treatment decisions in breast cancer. [ 18 F]FES PET and [ 18 F]FDHT PET allow non-invasive assessment of the oestrogen (ER) and androgen receptor (AR) status of individual lesions within a patient. Despite standardised analysis techniques, interobserver variability can significantly affect the interpretation of PET results and thus clinical applicability. The purpose of this study was to determine visual and quantitative interobserver variability of [ 18 F]FES PET and [ 18 F]FDHT PET interpretation in patients with metastatic breast cancer. Methods: In this prospective, two-centre study, patients with ER-positive metastatic breast cancer underwent both [ 18 F]FES and [ 18 F]FDHT PET/CT. In total, 120 lesions were identified in 10 patients with either conventional imaging (bone scan or lesions > 1 cm on high-resolution CT, n = 69) or only with [ 18 F]FES and [ 18 F]FDHT PET (n = 51). All lesions were scored visually and quantitatively by two independent observers. A visually PET-positive lesion was defined as uptake above background. For quantification, we used standardised uptake values (SUV): SUV max , SUV peak and SUV mean. Results: Visual analysis showed an absolute positive and negative interobserver agreement for [ 18 F]FES PET of 84% and 83%, respectively (kappa = 0.67, 95% CI 0.48-0.87), and 49% and 74% for [ 18 F]FDHT PET, respectively (kappa = 0.23, 95% CI − 0.04-0.49). Intraclass correlation coefficients (ICC) for quantification of SUV max , SUV peak and SUV mean were 0.98 (95% CI 0.96-0.98), 0.97 (95% CI 0.96-0.98) and 0.89 (95% CI 0.83-0.92) for [ 18 F]FES, and 0.78 (95% CI 0.66-0.85), 0.76 (95% CI 0.63-0.84) and 0.75 (95% CI 0.62-0.84) for [ 18 F]FDHT, respectively.

[18F]FDG and [18F]FES positron emission tomography for disease monitoring and assessment of anti-hormonal treatment eligibility in granulosa cell tumors of the ovary

“…Concerning the quantitative analysis of FES, no validated cutoff for FES PET in gynaecological tumors in known in literature. However, an optimal cutoff is suggested in breast cancer (SUV max of 1.54 for FES PET), which is in line with the results of our visual and quantitative assessment [18,26,27].…”

Application of PET Tracers in Molecular Imaging for Breast Cancer

“…[ 18 F]-FES-PET/CT enables the visualization of ER expression, with [ 18 F]-FES behaving very similar to estradiol [ 77 ]. A large prospective cohort study of 90 BC patients with first recurrence/metastatic disease and preliminary results from a prospective study in 10 ER+ MBC patients showed an excellent inter-observer agreement for [ 18 F]-FES uptake (0.90 and 0.98, respectively) [ 22 ••, 78 ]. Although limited data about repeatability and reproducibility are available, a recent guideline paper does provide recommendations regarding standardization of scanning time, control of pre-analytical factors that influence [ 18 F]-FES uptake (such as discontinuation of estrogen receptor degraders > 5 weeks prior to scanning), visual analysis, and quantification of [ 18 F]-FES uptake [ 77 ].…”

Bone Metastases Are Measurable: The Role of Whole-Body MRI and Positron Emission Tomography

“…The PET response assessment approach for bone metastases in prostate cancer using PSMA PET may be extended to other targeted PET tracers, such as 18 F-NaF and 18 F-FDHT in prostate cancer, 18 F-FES in breast cancer and 18 F-FDG and 68 Gafibroblast activation protein inhibitors ( 68 Ga-FAPI) in a multitude of cancer types (94,(99)(100)(101)(102).…”