Observer Agreement and Accuracy of ¹⁸F-Sodium Fluoride PET/CT in the Diagnosis of Bone Metastases in Prostate Cancer

Abstract

Our aim was to evaluate the interobserver agreement in 18 F-sodium fluoride (NaF) PET/CT for the detection of bone metastases in patients with prostate cancer (PCa). Methods: 18 F-NaF PET/CT scans were retrieved from all patients who participated in 4 recent prospective trials. Two experienced observers independently evaluated the 18 F-NaF PET/CT scans on a patient level using a 3-category scale (no bone metastases [M0], equivocal for bone metastases, and bone metastases present [M1]) and on a dichotomous scale (M0/M1). In patients with no more than 10 lesions, the location and number of lesions were recorded. On a patient level, the diagnostic performance was calculated using a sensitivity analysis, in which equivocal lesions were handled as M0 as well as M1. Results: 18 F-NaF PET/CT scans from 219 patients with PCa were included, of whom 129 patients were scanned for primary staging, 67 for biochemical recurrence, and 23 for metastatic castration-resistant PCa. Agreement between the observers was almost perfect on a patient level (3-category unweighted κ 5 0.83 ± 0.05, linear weighted κ 5 0.90 ± 0.06, and dichotomous κ 5 0.91 ± 0.07). On a lesion level (dichotomous scale), the observers agreed on the number and location of bone metastases in 205 (93.6%) patients. In the remaining 14 patients, the readers disagreed on the number of lesions in 13 patients and the location of bone metastases in 1 patient. A final diagnosis of bone metastases was made for 211 of 219 patients. The sensitivity ranged from 0.86 to 0.92, specificity from 0.83 to 0.97, positive predictive value from 0.70 to 0.93, and negative predictive value from 0.94 to 0.96. Conclusion: The interobserver agreement on 18 F-NaF PET/CT for the detection of bone metastases in patients with PCa was very high among trained observers, both on a patient level and on a lesion level. Moreover, the diagnostic performance of 18 F-NaF PET/CT was satisfactory, rendering 18 F-NaF PET/CT a robust tool in the diagnostic armamentarium.

The Role of Magnetic Resonance Imaging and Positron Emission Tomography/Computed Tomography in the Primary Staging of Newly Diagnosed Prostate Cancer: A Systematic Review of the Literature

“…Consistent in all studies, NaF-PET/CT performed better than conventional imaging and had less equivocal findings requiring additional imaging for further clarification [135,137,139]. Zacho et al [138] reported high interobserver agreement in the detection of bone metastases by two well-trained radiologists (Cohen's kappa 0.89). Poulsen et al [139] compared NaF-and FCH-PET/CT with bone scintigraphy for the detection of spine metastases, and reported similar performance of NaF-and FCH-PET/ CT while superior performance of NAF-PET/CT compared with bone scintigraphy.…”

“…NaF binds mainly to osteoblastic bone lesions and, in combination with CT, may offer whole-body examination [134]. Six studies, including 37-211 patients, assessed the use of NaF-PET/ CT and reported overall favorable sensitivity ranging from 88% to 100% [133,[135][136][137][138][139]. Consistent in all studies, NaF-PET/CT performed better than conventional imaging and had less equivocal findings requiring additional imaging for further clarification [135,137,139].…”

Application of PET Tracers in Molecular Imaging for Breast Cancer

“…[19]. Moreover, a high inter-observer agreement at the patient level was found by using three scales to define [ 18 F]-NaF-PET/CT findings [21]. How to correctly perform and interpret [ 18 F]-NaF-PET/CT scans is published in EANM and Society of Nuclear Medicine and Molecular Imaging (SNMMI) guidelines, supporting technical standardization and harmonization [73,74].…”

18F-Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) is accurate for high-grade prostate cancer bone staging when compared to bone scintigraphy

“…Thus, false positive and false negative findings for both imaging modalities cannot be ruled out, and therefore may affect sensitivity and specificity, which need to be interpreted carefully. However, clinical and imaging follow-up remain valid approaches for evaluation of diagnostic accuracy, as it has been extensively used in other comparative imaging studies in PCa [27][28][29].…”