Intense 68Ga-Pentixafor Activity in Aldosterone-Producing Adrenal Adenomas

Advances in the molecular imaging of primary aldosteronism

Primary aldosteronism (PA) is the most common cause of secondary hypertension. It predisposes to adverse outcomes such as nephrotoxicity and cardiovascular damage, which are mediated by direct harm from hypertension to the target organs. Accurate subtype diagnosis and localization are crucial elements in choosing the type of treatment for PA in clinical practice since the dominant side of aldosterone secretion in PA affects subsequent treatment options. The gold standard for diagnosing PA subtypes, adrenal venous sampling (AVS), requires specialized expertise, the invasive nature of the procedure and high costs, all of which delay the effective treatment of PA. Nuclide molecular imaging is non-invasive and has wider applications in the diagnosis and treatment of PA. This review aims to provide a summary of the application of radionuclide imaging in the diagnosis, treatment management and prognostic assessment of PA.

Accuracy of Gallium-68 Pentixafor Positron Emission Tomography-Computed Tomography for Subtyping Diagnosis of Primary Aldosteronism

IMPORTANCE

Adrenal vein sampling (AVS) is the recommended procedure for subtyping primary aldosteronism (PA) as unilateral PA (UPA) or bilateral PA (BPA), with different treatment needed for each: adrenalectomy for UPA and medication for BPA. However, AVS is invasive and technically difficult, and how to subtype PA noninvasively is currently a great challenge.

OBJECTIVE

To evaluate the accuracy of gallium-68 pentixafor positron emission tomography-computed tomography (PET-CT) in subtyping PA using AVS as a reference standard.

DESIGN, SETTING, AND PARTICIPANTS

This diagnostic study was conducted at a tertiary hospital in China among patients diagnosed with PA. Enrollment was started in November 2021, with follow-up ending in May 2022.

EXPOSURES

: Patients were recruited to undergo gallium-68 pentixafor PET-CT and AVS.

MAIN OUTCOMES AND MEASURES

Maximum standardized uptake value (SUVmax) of each adrenal gland during PET-CT was measured to calculate the lateralization index of SUVmax. Area under the receiver operating characteristic curve (AUROC), specificity, and sensitivity were used to analyze the accuracy of the lateralization index based on SUVmax for subtyping PA.

RESULTS

Among 100 patients with PA who completed the study (47 female [47.0%] and 53 male [53.0%]; median [IQR] age, 49 [38-56] years), 43 individuals had UPA and 57 individuals had BPA. Aldosterone-cortisol ratio (Spearman ρ = 0.26; P < .001) in adrenal veins was positively correlated with SUVmax of adrenal glands at 10 minutes during PET-CT. Using lateralization index based on SUVmax at 10 minutes to identify UPA, the AUROC was 0.90 (95% CI, 0.83-0.97). A cutoff value for lateralization index based on SUVmax at 10 minutes set at 1.65 conferred a specificity of 1.00 (95% CI, 0.94-1.00) and sensitivity of 0.77 (95% CI, 0.61-0.88). The diagnostic concordance rate of PET-CT and AVS was 90 patients (90.0%) compared with 54 patients (54.0%) between traditional CT and AVS.

CONCLUSIONS AND RELEVANCE

This study found good diagnostic accuracy of gallium-68 pentixafor PET-CT in differentiating UPA from BPA. These findings suggest that gallium-68 pentixafor PET-CT may be used to avoid invasive AVS in some patients with PA.

Imaging Aldosterone-Producing Adrenocortical Carcinoma With 68 Ga-Pentixafor PET/CT

ABSTRACT

Chemokine receptor 4 (CXCR4) is a 7-transmembrane G protein-coupled receptor, and pentixafor is considered to be a potent ligand for the CXCR4 receptor. Recently, 68 Ga-pentixafor has been reported as a potential PET imaging agent for CXCR4-positive tumors and inflammatory lesions, including adrenocortical lesions. We report a case of primary aldosteronism due to adrenocortical carcinoma with intense 68 Ga-pentixafor activity on PET/CT.

Usefulness of 68 Ga-Pentixafor PET/CT on Diagnosis and Management of Cushing Syndrome

PURPOSE

This pilot study investigated the performance of C-X-C motif chemokine receptor 4 (CXCR4) molecular imaging ( 68 Ga-pentixafor PET/CT) in Cushing syndrome (CS) and the correlation between CXCR4 signaling interactions and glucose metabolism in adrenocorticotropin-cortisol pathway.

METHODS

We retrospectively evaluated 31 patients (16 patients with CS and 15 patients with nonfunctioning pituitary or adrenal adenomas). All patients underwent 68 Ga-pentixafor PET/CT, and 11 with pituitary adenoma also underwent 18 F-FDG PET/CT. The diagnosis accuracy of 68 Ga-pentixafor PET/CT was calculated. The correlation between radiouptake along the pituitary-adrenal axis and hormone levels was calculated.

RESULTS

Patients with Cushing disease characterized a focal uptake in adrenocorticotropic hormone-producing pituitary adenoma (ACTH-PA). In ACTH-independent CS, there was increased uptake of 68 Ga-pentixafor in adrenal lesions but not in the pituitary fossa. The nonfunctioning pituitary or adrenal adenomas showed negative 68 Ga-pentixafor signal. The one patient with metastatic ectopic ACTH syndrome had multiple 68 Ga-pentixafor-avid lesions. Using the threshold of SUV max >8.5 in the adrenal lesions, the sensitivity and specificity of 68 Ga-pentixafor PET/CT to diagnose cortisol-producing adenoma were 100% and 84.9%. A cutoff SUV max value of 3.0 on 68 Ga-pentixafor PET/CT had 100% sensitivity and specificity for differentiating ACTH-PA. The corresponding hormone level was significantly correlated with uptake of 68 Ga-pentixafor in pituitary adenoma and adrenal tissue but not with glucose metabolism.

CONCLUSION

We have characterized the performance of 68 Ga-pentixafor in different subtypes of CS. 68 Ga-pentixafor PET/CT is promising in the differential diagnosis of both ACTH-independent and ACTH-dependent CS. Activated CXCR4 molecular signaling along the pituitary-adrenal axis was found in patients with Cushing disease.

Cortisol-Producing Adrenal Adenomas With Intense Activity on 68Ga-Pentixafor PET/CT

ABSTRACT

CXC chemokine receptor type 4 as a G-protein-coupled receptor has been confirmed to be highly expressed in functional adrenocortical adenomas. 68Ga-pentixafor, a CXC chemokine receptor type 4-specific ligand, has been reported as a promising tracer to evaluate functional nature of adrenal adenomas. We report intense 68Ga-pentixafor activity of cortisol-producing adrenal adenomas in 2 patients with adrenocorticotropic hormone-independent Cushing syndrome.