Biodistribution of ¹⁸F-AlF-NOTA-octreotide in Different Organs and Characterization of Uptake in Neuroendocrine Neoplasms

Purpose: The aims of this study were threefold: [1] to describe the biodistribution of ¹⁸F-AlF-NOTA-octreotide (¹⁸F-OC) in normal organs; [2] to evaluate the range of uptake of NEN and benign lesions using the maximum standardized uptake value (SUV_max); and [3] to compare the difference in ¹⁸F-OC uptake among tumors of different grades.

Methods: This study included 162 patients (67 females and 95 males) who received ¹⁸F-OC positron emission tomography (PET)/computed tomography (CT), 128 of whom were diagnosed with neuroendocrine neoplasms (NENs). The SUV_max and SUV_mean of ¹⁸F-OC were measured in 21 normal anatomical structures. We compared the differences among G1, G2, and G3 NENs, as well as between NENs and benign lesions.

Results: High physiological uptake of ¹⁸F-OC (SUV_max > 6.77) was detected in the spleen, adrenal gland, renal parenchyma, pituitary gland, and liver. Moderate uptake (SUV_max 3.00-6.77) was found in the uncinate process of the pancreas (PU), prostate, thyroid, and uterus. Mild uptake (SUV_max 1.34-3.00) was observed in the small intestine, pancreas (pancreas uptake except for the head of the pancreas), gallbladder, and transverse colon. The SUV_max of NENs was higher than that of benign lesions, including fractures, inflamed tissue, reactive hyperplasia, and degenerative disease. However, overlap was noted between the two groups. The SUV_max of ¹⁸F-OC uptake by tumors was significantly correlated with tumor grade in primary lesions and those of the lymph node, bone, and other sites (all P < 0.01).

Conclusions: The results obtained from the majority of the samples in this study show the biodistribution of ¹⁸F-OC in normal organs and have significance as a reference. Although some benign lesions show variable uptake, the uptake by these lesions is still different from that of NENs. NENs of different grades have differences in ¹⁸F-OC uptake levels.