Functional Characterization of Adrenocortical Masses in Nononcologic Patients Using <sup>68</sup>Ga-Pentixafor
Jie Ding, Anli Tong, Yushi Zhang, Jin Wen, Hui Zhang, Marcus Hacker, Li Huo, Xiang Li
Abstract
<b>Purpose:</b> We aimed to investigate the diagnostic and prognostic value of <sup>68</sup>Ga-pentixafor positron emission tomography (PET)/computed tomography (CT) imaging in non-cancer patients with suspected adrenal masses. <b>Methods:</b> Sixty-four patients who had benign adrenal masses on CT were retrospectively included in our study. All patients underwent <sup>68</sup>Ga-pentixafor PET/CT scans, and 56 of these patients subsequently underwent adrenalectomy. The subtypes of 81 adrenal tumors including 14 nonfunctioning adrenal nodules, 4 cortisol-producing adenomas, 41 aldosterone-producing adenomas, 5 suspected unilateral adrenal hyperplasia, 15 idiopathic aldosterone hyperplasia and 2 pheochromocytomas, were determined by histology or follow-up evaluations. The functional lateralization diagnosis efficiency was calculated by visual analysis. Semi-quantitative parameters of these lesions including maximum standardized uptake value (SUV<sub>max</sub>), the ratio of lesional SUV<sub>max</sub> to normal liver SUVmean (LLR), and the ratio of lesional SUV<sub>max</sub> to contralateral adrenal tissue SUVmean (LCR) have also been calculated. Dynamic analysis has also been performed on fifteen patients. Besides, clinical outcomes were assessed and compared in patients who underwent adrenalectomy. <b>Results:</b> The sensitivity and specificity of <sup>68</sup>Ga-pentixafor PET for functional lateralization of patients with adrenocortical lesions were 97.8% (45/46) and 87.5% (14/16) respectively. The two pheochromocytoma lesions had lower pentixafor uptake compared to the normal adrenal glands. Functioning (active) adrenocortical adenomas showed an elevated SUV<sub>max</sub> of 16.3±7.9 in comparison to 4.4±1.7 in nonfunctioning (inactive) adenomas and 5.5±2.7 in hyperplasia lesions (P<0.0001). To identify active adrenocortical adenomas, a cutoff value of 7.1 for SUV<sub>max</sub> showed a sensitivity of 90.9% and a specificity of 85.3% (AUC=0.96, P<0.0001); a cutoff value of 2.5 for LLR showed a sensitivity of 95.5% and a specificity of 88.2% (AUC=0.97, P<0.0001); and a cutoff value of 2.4 for LCR showed a sensitivity of 88.6% and a specificity of 91.8% (AUC=0.95, P<0.0001). The graphical Ki of active adrenocortical adenomas was significantly higher than in-active adenomas. Uptake values for <sup>68</sup>Ga-pentixafor were significantly higher in patients with preferable outcomes (cured/improved) (SUV<sub>max</sub>=15.5±8.0, LLR=6.5±4.3, LCR=6.2±5.0) than in patients with nonpreferable outcomes (no improvement) (SUV<sub>max</sub>=4.2±0.5, LLR=1.3±0.2, LCR =1.5±0.6, all P<0.0001). <b>Conclusion:</b><sup>68</sup>Ga-pentixafor PET/CT imaging exhibits great potential for noninvasive functional lateralization and characterization of patients with adrenocortical masses.