Dual Time Point FDG-PET/CT for the Differentiation of Adrenal Lesions in Patients with Cancer

摘要

Background: The adrenal gland is a common site of metastatic disease in oncology patients. The accurate characterization of adrenal lesions in images is important in avoiding unnecessarily invasive biopsies or surgeries. The aim of this study is to assess the value of dual time point F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for differentiating malignant from benign adrenal lesions in patients with cancer. Methods: Patients with adrenal nodules (size > 1 cm) evidenced through dual time point (1 and 3 hours after injection) FDG-PET/CT were enrolled in this retrospective study. The 1 hour and 3 hour maximum standardized uptake values (SUV_max) of adrenal lesions were measured. The 1 hour and 3 hour adrenal SUV_max to liver SUV_mean ratios (A/L SUR) were calculated. The additional parameters of ΔSUV_max, retention index of SUV_max (RI-SUV_m ax), Δ A/L SUR, and RI-A/L SUR were also calculated. Results: A total of 36 patients were enrolled in this study. There were 41 adrenal lesions identified among 36 patients, including 15 malignant and 26 benign adrenal lesions. There were significant differences between malignant and benign lesions within the parameters of 1 hour SUV_max, 3 h SUV_max, ΔSUV_max, 1 h A/L SUR, 3 h A/L SUR, ΔA/L SUR, and RI-A/L SUR. In the receiver operating characteristic curve analysis, the parameters of 1 hour SUV_max, 3 h SUV_max, 1 h A/L SUR, 3 h A/L SUR, and ΔA/ L SUR yielded excellent or good diagnostic performance results. In applying cutoff values of 1 hour SUV_max > 2.7, 3 h SUV_max > 2.8, 1 hour A/L SUR > 1.0, 3 hour A/L SUR > 1.15, and ΔA/L SUR > 0.18, the diagnostic accuracies were 82.9%, 82.9%, 85.4%, 85.4%, and 80.5% respectively. To maximize diagnostic accuracy, we developed a diagnostic algorithm using 1 hour SUV_max and ΔA/L SUR. Eleven adrenal lesions with 1 hour SUV_max less than 2.3 were all benign and 10 adrenal lesions with 1 hour SUV greater than 3.3 were all malignant. In the subgroup of 1 hour SUV_max 2.3 to 3.3, 12 adrenal lesions with ΔA/L SUR less than 0.18 were all benign and 5 of 8 adrenal lesions with ΔA/L SUR greater than 0.18 were malignant. The diagnostic accuracy was improved to 92.7%. Conclusion: Parameters of 1 hour SUV_max, 3 h SUV_max, 1 h A/L SUR, 3 h A/L SUR, and ΔA/L SUR in dual time point FDG-PET yield excellent or good diagnostic performance results in differentiating malignant from benign adrenal lesions. A diagnostic algorithm using 1 hour SUV_max and ΔA/L SUR can be helpful in improving diagnostic accuracy.