Adrenal functional imaging – which marker for which indication?

Abstract

In recent years, a broad spectrum of molecular image biomarkers for assessment of adrenal functional imaging have penetrated the clinical arena. Those include positron emission tomography and single photon emission computed tomography radiotracers, which either target glucose transporter, CYP11B enzymes, C-X-C motif chemokine receptor 4, norepinephrine transporter or somatostatin receptors. We will provide an overview of key radiopharmaceuticals and determine their most relevant clinical applications, thereby providing a roadmap for the right image biomarker at the right time for the right patient. Numerous radiotracers for assessment of adrenal incidentalomas ([ 18 F]FDG; [ 123 I]IMTO/IMAZA), ACC ([ 123 I]IMTO/IMAZA; [ 18 F]FDG; [ 68 Ga]PentixaFor), pheochromocytomas and paragangliomas ([ 123 I]mIBG; [ 18 F]flubrobenguane; [ 18 F]AF78; [ 68 Ga]DOTATOC/-TATE), or primary aldosteronism ([ 11 C]MTO, [ 68 Ga]PentixaFor) are currently available and have been extensively investigated in recent years. In addition, the field is currently evolving from adrenal functional imaging to a patient-centered adrenal theranostics approach, as some of those radiotracers can also be labeled with ß-emitters for therapeutic purposes. The herein reviewed functional image biomarkers may not only allow to increase diagnostic accuracy for adrenal gland diseases but may also enable for achieving substantial antitumor effects in patients with adrenocortical carcinoma, pheochromocytoma or paraganglioma.