Adrenal nuclear medicine

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Adrenal nuclear medicine comprises functional imaging techniques that assess the metabolic and hormonal activity of the adrenal cortex and medulla using specific radiopharmaceuticals.

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It helps localize hormonally active adrenal lesions, differentiate benign from malignant masses, and identify metastatic or ectopic functional tissue when anatomic imaging (CT/MRI) is inconclusive.

It is broadly divided into:

Adrenocortical imaging – evaluates cortisol- and aldosterone-producing tissues.
Adrenomedullary imaging – evaluates catecholamine-producing tissues (pheochromocytoma, paraganglioma, neuroblastoma).

Adrenal Anatomy and Physiology

Cortex: Produces steroid hormones — glucocorticoids (cortisol), mineralocorticoids (aldosterone), and androgens.
Medulla: Produces catecholamines (epinephrine, norepinephrine).

Hence, nuclear imaging targets distinct biochemical pathways:

Cortex: Cholesterol uptake and steroid synthesis.
Medulla: Catecholamine synthesis, uptake, and storage.

![Schematic display of radiopharmaceuticals for adrenal cortex and medulla tumors imaging. DXM (used for premedication before NP-59 or 11C-metomidate imaging in primary hyperaldosteronism) = dexamethasone; EPI = epinephrine; NE: norepinephrine; SSR = somatostatin receptors.

Sundin A, Hindié E, Avram AM, Tabarin A, Pacak K, Taïeb D. A Clinical Challenge: Endocrine and Imaging Investigations of Adrenal Masses. Journal of Nuclear Medicine. 2021;62(Supplement 2):26S-33S. doi:10.2967/jnumed.120.246066](attachment:1de12009-5258-4d51-894a-910e931e4f45:F1.large.jpg)

Schematic display of radiopharmaceuticals for adrenal cortex and medulla tumors imaging. DXM (used for premedication before NP-59 or 11C-metomidate imaging in primary hyperaldosteronism) = dexamethasone; EPI = epinephrine; NE: norepinephrine; SSR = somatostatin receptors.

![Stepwise algorithm of nuclear imaging in the evaluation of adrenal masses.

Stepwise algorithm of nuclear imaging in the evaluation of adrenal masses.

Adrenal Nuclear Imaging Overview

Category	Target	Radiopharmaceuticals	Common Indications
Adrenocortical Imaging	Steroid hormone synthesis	I-131 or I-123 iodomethyl norcholesterol (NP-59)	Cushing’s syndrome, primary aldosteronism, adrenal hyperplasia, adenoma vs carcinoma
Adrenomedullary Imaging	Catecholamine uptake (sympathoadrenal system)	I-123 or I-131 metaiodobenzylguanidine (MIBG)	Pheochromocytoma, paraganglioma, neuroblastoma
PET-based Imaging (Adrenomedullary)	Amino acid or receptor uptake	F-18 FDG, F-18 DOPA, Ga-68 DOTATATE, F-18 FDA (fluorodopamine)	Malignant, extra-adrenal, or metastatic disease

Differential Diagnosis Using Nuclear Imaging

Clinical Condition	Imaging Finding	Nuclear Modality
Cushing’s syndrome	Unilateral NP-59 uptake	Adrenocortical adenoma
ACTH-dependent Cushing’s	Bilateral NP-59 uptake	Adrenal hyperplasia
Conn’s (Primary hyperaldosteronism)	Unilateral NP-59 uptake	Aldosterone-producing adenoma
Pheochromocytoma	Focal MIBG uptake	I-123/I-131 MIBG
Paraganglioma	Extra-adrenal uptake	I-123 MIBG or Ga-68 DOTATATE
Neuroblastoma	Intense diffuse uptake (child)	I-123 MIBG
Adrenal metastasis	FDG-avid, MIBG-negative	F-18 FDG PET/CT
Adrenocortical carcinoma	FDG-avid, NP-59 negative	FDG PET/CT or C-11 metomidate PET

![Posterior to anterior view of 131I-adosterol scintigraphy and related imaging findings under various conditions. (A) and (B): Subclinical Cushing syndrome in a 50-year-old female: Adrenocortical scintigraphy showing moderate radiotracer uptake in the right-adrenal mass (A: black arrow) with mild contralateral adrenal suppression (A: white arrow), suggesting subclinical Cushing’s syndrome. NCCT showing a hypo-attenuating mass on right-adrenal gland consistent with adenoma (B: black arrow). (C) and (D): Cushing syndrome in a 60-year-old female. Adrenocortical scintigraphy showing marked radiotracer uptake in the adenoma with obvious contralateral suppression, indicative of Cushing syndrome (C). Chemical-shift imaging subtraction image highlights the fat content in the adenoma (D: black arrow). (E) and (F): ACTH-dependent Cushing’s disease in a 42-year-old female: Bilateral adrenal uptake is detected by adrenocortical scintigraphy (E), and pituitary MRI reveals a hypovascular adenoma on delayed contrast-enhanced imaging (F: black arrow). G and H: Bilateral micronodular adrenocortical disease in a 67-year-old female: Although initially suspected as a unilateral functional adrenal adenoma by CT (H), adrenocortical scintigraphy showed symmetrical high uptake bilaterally, leading to the diagnosis of bilateral micronodular adrenocortical disease, preventing surgery (G). I and J: Bilateral macronodular adrenocortical disease in a 71-year-old male: Adrenocortical scintigraphy showing high uptake bilaterally (I) with multiple nodules on contrast-enhanced CT (J), leading to the diagnosis of bilateral macronodular adrenocortical disease.

Yokoyama, K., Matsuki, M., Isozaki, T. et al. Advances in multimodal imaging for adrenal gland disorders: integrating CT, MRI, and nuclear medicine. Jpn J Radiol 43, 903–926 (2025). https://doi.org/10.1007/s11604-025-01732-6](attachment:bafb22a7-1e8b-43fe-8742-a8f4c396e4ff:11604_2025_1732_Fig5_HTML.webp)

Posterior to anterior view of 131I-adosterol scintigraphy and related imaging findings under various conditions. (A) and (B): Subclinical Cushing syndrome in a 50-year-old female: Adrenocortical scintigraphy showing moderate radiotracer uptake in the right-adrenal mass (A: black arrow) with mild contralateral adrenal suppression (A: white arrow), suggesting subclinical Cushing’s syndrome. NCCT showing a hypo-attenuating mass on right-adrenal gland consistent with adenoma (B: black arrow). (C) and (D): Cushing syndrome in a 60-year-old female. Adrenocortical scintigraphy showing marked radiotracer uptake in the adenoma with obvious contralateral suppression, indicative of Cushing syndrome (C). Chemical-shift imaging subtraction image highlights the fat content in the adenoma (D: black arrow). (E) and (F): ACTH-dependent Cushing’s disease in a 42-year-old female: Bilateral adrenal uptake is detected by adrenocortical scintigraphy (E), and pituitary MRI reveals a hypovascular adenoma on delayed contrast-enhanced imaging (F: black arrow). G and H: Bilateral micronodular adrenocortical disease in a 67-year-old female: Although initially suspected as a unilateral functional adrenal adenoma by CT (H), adrenocortical scintigraphy showed symmetrical high uptake bilaterally, leading to the diagnosis of bilateral micronodular adrenocortical disease, preventing surgery (G). I and J: Bilateral macronodular adrenocortical disease in a 71-year-old male: Adrenocortical scintigraphy showing high uptake bilaterally (I) with multiple nodules on contrast-enhanced CT (J), leading to the diagnosis of bilateral macronodular adrenocortical disease.