The following is a summary of “3-[¹⁸F]Fluoro-para-hydroxyphenethylguanidine (3-[¹⁸F]pHPG) PET—A Novel Imaging Modality for Paraganglioma,” published in the June 2024 issue of Endocrinology by Else, et al.

Functional positron emission tomography (PET) imaging serves as a valuable tool for characterizing pheochromocytoma and paraganglioma (PCC/PGL) and detecting metastases in malignant disease, aiding in treatment decisions for patients. For a study, researchers sought to assess the effectiveness of a novel PET radiotracer, 3-[¹⁸F]fluoro-para-hydroxyphenethylguanidine (3-[¹⁸F]pHPG), an analog of norepinephrine, in localizing PCC/PGL.

Sixteen patients (8 male: 8 female; mean age 47.6 ± 17.6 years; range, 19-74 years) with pathologically confirmed or clinically diagnosed PCC/PGL underwent 3-[¹⁸F]pHPG PET/CT whole-body scans. Following intravenous administration of 304 to 475 MBq (8.2-12.8 mCi) of 3-[¹⁸F]pHPG, whole-body PET scans were conducted at 90 minutes. Abnormal findings consistent with primary tumors or metastases were identified, and physiological biodistribution in normal organs was recorded. Standardized uptake value (SUV) measurements were obtained for target lesions and physiological organ distributions.

3-[¹⁸F]pHPG PET demonstrated high radiotracer uptake and retention in primary tumors, as well as metastatic lesions in bones, lymph nodes, and other solid organs. Physiological biodistribution was observed in salivary glands (parotid, submandibular, sublingual), thyroid, heart, liver, adrenals, kidneys, and bladder. Comparison with [⁶⁸Ga]DOTATATE PET/CT in 10 patients showed concordant distribution. Additionally, in 4 patients with available [¹²³I]meta-iodobenzylguanidine [¹²³I]mIBG planar scintigraphy and SPECT/CT scans, 3-[¹⁸F]pHPG PET revealed a greater number of metastatic lesions.

3-[¹⁸F]pHPG PET imaging demonstrated high activity retention within both benign and metastatic PCC/PGL, suggesting its utility as a novel modality for functional imaging and staging of malignant paraganglioma. Its advantages include high lesion affinity, whole-body coregistered computed tomography and same-day imaging capability.

Reference: academic.oup.com/jes/article/8/6/bvae049/7644596