Imaging CXCR4 expression in patients with suspected primary hyperaldosteronism

Evaluation of adrenal vein anatomy by adrenal venous sampling in patients with primary aldosteronism in Chinese

Accurate cannulation of the adrenal vein is challenging during adrenal venous sampling (AVS) because of the variations in adrenal vein anatomy. This study aimed to investigate the adrenal venous morphology in Chinese and improve the success rate of AVS. A total of 221 participants with primary aldosteronism (PA) who underwent AVS were enrolled. Compare the morphology among subgroups divided according to sex, body mass index (BMI), and with or without adenoma. The success rate of right, left, and bilateral AVS was 98.60%, 97.20%, and 96.85%, respectively. The triangular pattern was the most common (39.37%) on the right side, while the glandlike pattern (70.14%) on the left. The proportion of adrenal venous morphology varies among patients with different sexecs (χ2 = 21.335, P < .001), BMI (χ2 = 10.642 P = .031), and with or without adenoma (χ2 = 10.637, P = .031) on the right side, and the male, obese and adenoma group showed a higher proportion of glandlike pattern than triangular pattern. If only dependent on computed tomography, 9.05% of patients incorrectly diagnose the dominant side, 14.48% of patients would have inappropriate surgery meanwhile 25.34% of patients would miss the surgical opportunity. In conclusion, the most common types of right and left adrenal venous morphology were triangular pattern and glandlike pattern, respectively. Sex, BMI, and the presence of adenoma affected right adrenal venous morphology. Adequate knowledge of the adrenal venous morphology is critical for improving the success rate of AVS and making an appropriate treatment for PA.

68Ga-pentixafor PET/CT in the localization diagnosis of primary aldosteronism concurrent subclinical cushing's syndrsome: two case reports

PURPOSE

Adrenal venous sampling (AVS) is recommended for subtyping primary aldosteronism (PA). However, in cases of PA, concurrent subclinical Cushing's syndrome (SCS) has the potential to confound AVS results. Pentixafor, a CXC chemokine receptor type 4-specific ligand, has been reported as a promising marker to evaluate functional nature of adrenal adenomas. This study aims to investigate the clinical value of Gallium-68 Pentixafor Positron Emission Tomography-Computed Tomography (68Ga-Pentixafor PET/CT) in the localization diagnosis of patients with PA plus SCS.

METHODS

Two patients with a confirmed diagnosis of PA plus SCS underwent AVS and 68Ga-Pentixafor PET/CT.

RESULTS

AVS results revealed no lateralization for both patients while 68Ga-Pentixafor PET/CT showed a unilateral adrenal nodule with increased uptake of 68Ga-Pentixafor. Unilateral adrenalectomy was performed based on the results of 68Ga-Pentixafor PET/CT. Subsequently, complete biochemical remission of autonomous aldosterone and cortisol secretion were achieved in both cases.

CONCLUSIONS

68Ga-Pentixafor PET/CT shows promising potential for the localization of aldosterone and cortisol co-secreting adrenal adenoma in patients with PA plus SCS.

A comparison of the performance of 68Ga-Pentixafor PET/CT versus adrenal vein sampling for subtype diagnosis in primary aldosteronism

Objective

To investigate the diagnostic efficiency and prognostic value of 68Ga-Pentixafor PET/CT in comparison with adrenal vein sampling (AVS) for functional lateralization in primary aldosteronism (PA). Histology and long-term clinical follow-up normally serve as the gold standard for such diagnosis.

Methods

We prospectively recruited 26 patients diagnosed with PA. All patients underwent 68Ga-Pentixafor PET/CT and AVS. Postsurgical biochemical and clinical outcomes of patients with unilateral primary aldosteronism (UPA), as diagnosed by PET/CT or AVS, were assessed by applying standardized Primary Aldosteronism Surgical Outcome (PASO) criteria. Immunohistochemistry (IHC) was performed to detect the expression of aldosterone synthase (CYP11B2) and CXCR4.

Results

On total, 19 patients were diagnosed with UPA; of these, 13 patients were lateralized by both PET/CT and AVS, four patients were lateralized by PET-only, and two by AVS-only. Seven subjects with no lateralization on AVS and PET received medical therapy. All patients achieved complete biochemical success except one with nodular hyperplasia lateralized by AVS alone. The consistency between PET/CT and AVS outcomes was 77% (20/26). Moreover, CYP11B2-positive nodules were all CXCR4-positive and showed positive findings on PET. Patients who achieved complete biochemical and clinical success had a higher uptake on PET as well as stronger expression levels of CXCR4 and CYP11B2.

Conclusion

Our analysis showed that 68Ga-Pentixafor PET/CT could enable non-invasive diagnosis in most patients with PA and identify additional cases of unilateral and surgically curable PA which could not be classified by AVS. 68Ga-Pentixafor PET/CT should be considered as a first-line test for the future classification of PA.

Treating Primary Aldosteronism-Induced Hypertension: Novel Approaches and Future Outlooks

Primary aldosteronism (PA) is the most common cause of secondary hypertension and is associated with increased morbidity and mortality when compared with blood pressure-matched cases of primary hypertension. Current limitations in patient care stem from delayed recognition of the condition, limited access to key diagnostic procedures, and lack of a definitive therapy option for nonsurgical candidates. However, several recent advances have the potential to address these barriers to optimal care. From a diagnostic perspective, machine-learning algorithms have shown promise in the prediction of PA subtypes, while the development of noninvasive alternatives to adrenal vein sampling (including molecular positron emission tomography imaging) has made accurate localization of functioning adrenal nodules possible. In parallel, more selective approaches to targeting the causative aldosterone-producing adrenal adenoma/nodule (APA/APN) have emerged with the advent of partial adrenalectomy or precision ablation. Additionally, the development of novel pharmacological agents may help to mitigate off-target effects of aldosterone and improve clinical efficacy and outcomes. Here, we consider how each of these innovations might change our approach to the patient with PA, to allow more tailored investigation and treatment plans, with corresponding improvement in clinical outcomes and resource utilization, for this highly prevalent disorder.

Clinical Value of 68Ga-Pentixafor PET/CT in Subtype Diagnosis of Primary Aldosteronism Patients with Adrenal Micronodules

Our objective was to investigate the clinical value of 68Ga-pentixafor PET/CT in subtype diagnosis of primary aldosteronism (PA) patients with adrenal micronodules less than 1 cm in diameter and compare it with the routine clinical methods. Methods: We used prospective enrollment of PA patients with adrenal micronodules identified by adrenal CT scans to undergo 68Ga-pentixafor PET/CT. Patients were divided into surgically eligible and ineligible groups based on surgical pathology and postoperative follow-up or adrenal venous sampling (AVS) results. Patient management was discussed by a multidisciplinary team. The semiquantitative parameters of PET/CT included SUVmax for adrenal lesion and SUV ratios for lesion to liver and lesion to normal adrenal gland. Results: In total, 123 PA patients with adrenal micronodules were examined using 68Ga-pentixafor PET/CT, and 104 patients who underwent surgery or successful AVS were included in the analysis (48 ± 10 y old). The sensitivity, specificity, and accuracy of visual analysis using 68Ga-pentixafor PET/CT to identify surgically eligible patients were 90.2%, 72.7%, and 86.5%, respectively, which were significantly higher than those of adrenal CT (73.1%, 53.8%, and 68.3%, respectively) and yielded consistent results in different CT morphologic or age subgroups. In 36 patients who had both AVS and 68Ga-pentixafor PET/CT, the tests showed a 66.7% concordance rate. However, PET/CT was significantly more concordant with surgical outcomes than was AVS in 17 patients who underwent adrenalectomy (82.4% vs. 68.86%). Among the 183 adrenal micronodules included in the study, the semiquantitative diagnostic thresholds for 92 lesions eligible for surgical treatment were an SUVmax of at least 4.55, an SUV ratio of at least 2.17 for lesion to liver, and an SUV ratio of at least 1.90 for lesion to normal adrenal gland. All patients benefited from surgical removal of 68Ga-pentixafor-avid microlesions. Conclusion: In PA patients with adrenal micronodules, 68Ga-pentixafor PET/CT demonstrated promising diagnostic accuracy in classification and appeared to perform better than adrenal CT. Furthermore, there was also a suggestion of some potential in predicting postoperative efficacy compared with AVS, although these observations require further investigation and verification in larger cohorts.

Advances in PET Imaging of the CXCR4 Receptor: [68Ga]Ga-PentixaFor

[68Ga]Ga-PentixaFor, a PET agent targeting CXCR4 is emerging as a versatile radiotracer with promising applications in oncology, cardiology and inflammatory disease. Preclinical work in various cancer cell lines have demonstrated high specificity and selectivity. In human investigations of several tumors, the most promising applications may be in multiple myeloma, certain lymphomas and myeloproliferative neoplasms. In the nononcologic setting, [68Ga]Ga-PentixaFor could greatly improve detection for primary aldosteronism and other endocrine abnormalities. Similarly, atherosclerotic disease and other inflammatory conditions could also benefit from enhanced identification by CXCR4 targeting. Rapidly cleared from the body with a favorable imaging and radiation dosimetry profile that has been already studied in over 1000 patients, [68Ga]Ga-PentixaFor is a worthy agent for further clinical exploration with potential for theranostic applications in hematologic malignancies.

Feasibility of spectral CT-derived extracellular volume fraction for differentiating aldosterone-producing from nonfunctioning adrenal nodules

OBJECTIVE

To assess the feasibility of spectral CT-derived extracellular volume (ECV) for differentiating aldosterone-producing nodules (APN) from nonfunctioning adrenal nodules (NFN).

METHODS

Sixty-nine patients with biochemically and histologically confirmed unilateral APN (34) and NFN (35) as well as 23 patients with bilateral APN (19) and NFN (27) confirmed biochemically and by adrenal vein sampling (AVS) were enrolled in this retrospective study from October 2020 to April 2022. All patients underwent contrast-enhanced spectral CT of the adrenal glands with a 10-min delayed phase. The haematocrit level was measured within 2 days of CT. An iodine density map was derived from the delayed CT. The ECV fractions of the APN and NFN were calculated and compared in the test cohort of 69 patients with unilateral adrenal nodules. The optimal cut-off value was determined to evaluate the diagnostic efficacy of the ECV fraction for differentiating APN from NFN in the validation cohort of 23 patients with bilateral adrenal nodules.

RESULTS

The ECV fractions of the APN (11.17 ± 4.57%) were significantly lower (p < 0.001) than that of the NFN (24.79 ± 6.01%) in the test cohort. At cut-off ECV value of 17.16%, the optimal area under the receiver operating characteristic curve was 0.974 (95% confidence interval: 0.942-1) with 91.4% sensitivity, 93.9% specificity, and 92.8% accuracy in the test cohort and 89.5% sensitivity, 96.3% specificity, and 93.5% accuracy in the validation cohort for differentiating APN from NFN.

CONCLUSION

The spectral CT-derived ECV fraction can differentiate APN from NFN with high diagnostic performance.

CLINICAL RELEVANCE STATEMENT

Spectral CT-derived extracellular volume fraction could accurately differentiate between adrenal aldosterone-producing nodules and nonfunctioning nodules. It might serve as a noninvasive alternative to adrenal vein sampling in primary aldosteronism patients with bilateral adrenal nodules.

KEY POINTS

• Conventional CT cannot differentiate aldosterone-producing adrenal nodules from nonfunctioning nodules. • Extracellular volume of adrenal aldosterone-producing nodules was significantly lower than that of nonfunctioning nodules and normal adrenal glands. It can accurately differentiate between aldosterone-producing and nonfunctioning adrenal nodules. • Extracellular volume may be a novel, noninvasive biomarker alternative to adrenal vein sampling for determining the functional status of bilateral adrenal nodules in patients with primary aldosteronism.

The Value of Targeting CXCR4 With 68Ga-Pentixafor PET/CT for Subtyping Primary Aldosteronism

CONTEXT

Primary aldosteronism (PA) is one of the leading causes of secondary hypertension, and its diagnostic subtyping consistently presents a clinical challenge.

OBJECTIVE

This study aimed to investigate the potential of 68Ga-Pentixafor positron emission tomography/computed tomography (PET/CT) in PA classification and its applicability in guiding the development of clinical treatment plans by increasing the sample size.

METHODS

We prospectively enrolled 120 patients with either PA or nonfunctional adenoma (NFA) for analysis. All patients underwent 68Ga-Pentixafor PET/CT. Of these, 11 patients underwent adrenal venous sampling (AVS), 77 underwent adrenalectomy, 76 received pathological diagnoses, and 71 underwent immunohistochemical detection of aldosterone synthase (CYP11B2). Immunohistochemistry for C-X-C chemokine receptor 4 (CXCR4) was performed in 62 cases. Follow-up was conducted for all patients.

RESULTS

Among the 120 patients, 66 were diagnosed with aldosterone-producing adenoma (APA), 33 with idiopathic hyperaldosteronism (IHA), and 21 with NFA. For APA patients, the sensitivity, specificity, and accuracy of visual analysis using 68Ga-Pentixafor PET/CT were 92.40%, 94.40%, and 93.33%, respectively. Furthermore, for APA patients with a nodule greater than 1 cm in diameter, when the maximum standard uptake value was 7.3 or greater, the specificity was 100%; and for APA patients with a nodule less than 1 cm in diameter, 68Ga-Pentixafor PET/CT also exhibited high sensitivity. AVS was successfully performed in 5 patients. Among the 5 patients, the concordance rate between the AVS and 68Ga-Pentixafor PET/CT for PA subtyping was 60%. In the 77 patients who underwent adrenalectomy, 61 PET/CT scans displayed positive lesions, all of which benefited from the surgery. Additionally, the concordance rate between 68Ga-Pentixafor PET/CT imaging and CYP11B2 was 81.69%.

CONCLUSION

68Ga-Pentixafor PET/CT is a reliable and noninvasive functional imaging technique that demonstrates high accuracy in classifying PA and provides valuable guidance for clinical treatment decision-making.

A clinical assessment of portable point-of-care testing for quick cortisol assay during adrenal vein sampling

This study assessed the clinical performance of point-of-care testing (POCT) for quick cortisol assay (QCA) during adrenal vein sampling (AVS) using a newly invented portable quantitative assay instrument. An observational study was conducted prospectively at two centres in Japan. Forty-eight patients with primary aldosteronism considered for adrenalectomy were enrolled in this study and underwent AVS. Three basal adrenal vein samples from each adrenal vein and two from the inferior vena cava were collected sequentially. The cortisol concentration of adrenal vein samples was measured by routine method and QCA. A total of 338 adrenal vein samples were analysed from 250 sites to determine AVS success or failure. The distribution of turnaround time of the QCA for AVS success or failure followed a normal distribution with an average of 20.5 min. A positive correlation between the routine method and QCA was observed regarding cortisol concentration or selectivity index. No significant difference between the two methods was observed regarding the success rate of AVS. Using the routine method as a reference, the sensitivity and specificity of AVS success or failure were 99.1% (210/212) and 81.6% (31/38), respectively. Easy, quick, portable, and precise POCT-QCA demonstrated its compatibility with routine methods regarding clinical performance.

2023 Korean Endocrine Society Consensus Guidelines for the Diagnosis and Management of Primary Aldosteronism

Primary aldosteronism (PA) is a common, yet underdiagnosed cause of secondary hypertension. It is characterized by an overproduction of aldosterone, leading to hypertension and/or hypokalemia. Despite affecting between 5.9% and 34% of patients with hypertension, PA is frequently missed due to a lack of clinical awareness and systematic screening, which can result in significant cardiovascular complications. To address this, medical societies have developed clinical practice guidelines to improve the management of hypertension and PA. The Korean Endocrine Society, drawing on a wealth of research, has formulated new guidelines for PA. A task force has been established to prepare PA guidelines, which encompass epidemiology, pathophysiology, clinical presentation, diagnosis, treatment, and follow-up care. The Korean clinical guidelines for PA aim to deliver an evidence-based protocol for PA diagnosis, treatment, and patient monitoring. These guidelines are anticipated to ease the burden of this potentially curable condition.

Key to the Treatment of Primary Aldosteronism in Secondary Hypertension: Subtype Diagnosis

PURPOSE OF REVIEW

Primary aldosteronism (PA) is a leading global cause of secondary hypertension. Subtyping diagnosis of PA is the key to surgery, but accurate classification of PA is crucial but challenging in clinical diagnosis and treatment. The purpose of this review is to provide a summary of current literature and propose subtyping diagnosis flow chart to help us classify PA quickly and accurately.

RECENT FINDINGS

Early diagnosis and accurate typing are essential for the timely treatment and appropriate management of PA. For most patients, adrenal venous sampling (AVS) is the central choice for typing diagnosis, but AVS is invasive and difficult to promote effectively. CT can help identify unilateral typical adenomas in select patients to avoid AVS. New radionuclide imaging has shown value in the diagnosis and classification of PA, which distinguishes adrenocortical hyperplasia from adenoma and can replace AVS in some patients. Accurately diagnosing unilateral PA is crucial for determining the appropriate treatment strategy for PA. The simple flow chart of PA subtyping diagnosis based on the current literature needs to be verified and evaluated by follow-up researches.

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.

Case series: Primary aldosteronism diagnosed despite normal screening investigations: A report of three cases

RATIONALE

Since the introduction of the aldosterone-to-renin ratio (ARR) as a screening tool for primary aldosteronism (PA), there has been a marked increase in the reported prevalence of this condition among hypertensive, even normotensive, subjects.

PATIENT CONCERNS

But ARR as a spot blood draw for estimating a patient's aldosterone secretory status is influenced by many factors.

DIAGNOSES

Here, we describe a series of patients with biochemically confirmed PA, whose diagnosis was delayed by the initial ARR assessment with non-suppressed renin.

INTERVENTIONS

Patient 1 had a history of resistant hypertension for many years and had a negative initial screening for secondary hypertension (including ARR). At the reevaluation, ARR was close to cutoff still with normal renin after strict and extended drug washout, and the further workup for PA demonstrated a unilateral aldosterone producing adenoma that was surgically removed, with subsequent complete biochemical remission and partial clinical success. Patient 2 was diagnosed with idiopathic hyperaldosteronism combined with obstructive sleep apnea syndrome, which could increase renin resulting in a negative ARR, and finally got a better treatment effect with PA-specific spironolactone, as well as continuous positive airway pressure. Patient 3 with hypokalemia as the main presentation was finally diagnosed with PA after excluding other diseases, and proceeded to laparoscopic adrenalectomy and histologically confirmed an aldosterone producing adenoma. Postoperatively, patient 3 achieved complete biochemical success without any medicine.

OUTCOMES

The clinical status of all three patients was effectively managed, resulting in either complete resolution or notable improvement of their respective conditions.

LESSONS

After rigorous standardized diagnostic evaluation, there are still many reasons for ARR negative in PA, but they all basically occur in the background of normal or normal-high renin without suppression. A negative screening test result should be repeated and analyzed carefully if this is not consistent with the clinical picture. If, despite a repeatedly negative ARR, clinical suspicion remains high, we recommend consideration of further evaluation, including confirmatory tests and adrenal venous blood sampling (AVS) or even 68Ga-pentixafor PET/CT to better confirm the diagnosis and improve patient outcomes.

Functional nodules in primary aldosteronism: identification of CXCR4 expression with 68Ga-pentixafor PET/CT

OBJECTIVES

We analyzed the diagnostic efficiency of ⁶⁸Ga-pentixafor PET/CT for functional nodules in primary aldosteronism (PA). Furthermore, we compared the correlation of CXCR4 expression with aldosterone synthase (CYP11B2) expression and PET/CT uptake in these patients.

METHODS

We prospectively assessed 50 patients diagnosed with PA and 10 patients with non-functional adrenal adenoma (NFA). All patients underwent ⁶⁸Ga-pentixafor PET/CT before adrenalectomy. Immunohistochemistry (IHC) was performed to detect the protein expression of CYP11B2 and the G-protein-coupled receptor CXCR4.

RESULTS

CYP11B2 IHC revealed the presence of 43 functional nodules. Subsequently, 40/43 functional nodules could be detected on ⁶⁸Ga-pentixafor PET/CT, while negative imaging findings were noted for 11/13 non-functional nodules (sensitivity, 93.0%; specificity, 84.6%). The optimum SUV_max cut-off for the identification of functional nodules was 8.95 (AUC 0.914 [0.828-1.000], p < 0.001). Regarding the size of functional nodules, diagnostic efficiency appeared to be much higher for nodules greater than 1 cm in size (sensitivity, up to 97.3%). Moreover, we examined the relationship between CXCR4 and CYP11B2 expression in 56 lesions. All 43 CYP11B2-positive nodules were CXCR4-positive, but one of the 13 CYP11B2-negative nodules (7.7%) showed false-positive staining for CXCR4. Moreover, the consistency between PET/CT uptake and CXCR4 staining results was 92.9% (52/56).

CONCLUSIONS

At least 90% of functional nodules show positive uptake on ⁶⁸Ga-pentixafor PET/CT, and the detection ability is much better for nodules with a diameter ≥ 1 cm. With its high sensitivity and specificity, ⁶⁸Ga-pentixafor PET/CT can be considered a promising surgical decision-making tool for patients with PA.

KEY POINTS

• ⁶⁸Ga-pentixafor PET/CT could be a useful tool for the identification of functional adrenal nodules in APAs and even IHAs. • The diagnostic efficiency appears to be much higher for nodules ≥ 1 cm in size. • There is high consistency between the results of 68Ga-pentixafor PET/CT imaging and CXCR4 immunohistochemistry.

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.

Development of Fluorinated NP-59: A Revival of Cholesterol Use Imaging with PET

Imaging of cholesterol use is possible with the ¹³¹I scintiscanning/SPECT agent NP-59. This agent provided a noninvasive measure of adrenal function and steroid synthesis. However, iodine isotopes resulted in poor resolution, manufacturing challenges, and high radiation dosimetry to patients that have limited their use and clinical impact. A ¹⁸F analog would address these shortcomings while retaining the ability to image cholesterol use. The goal of this study was to prepare and evaluate a ¹⁸F analog of NP-59 to serve as a PET imaging agent for functional imaging of the adrenal glands based on cholesterol use. Previous attempts to prepare such an analog of NP-59 have proven elusive. Preclinical and clinical evaluation could be performed once the new fluorine analog of NP-59 production was established. Methods: The recent development of a new reagent for fluorination along with an improved route to the NP-59 precursor allowed for the preparation of a fluorine analog of NP-59, FNP-59. The radiochemistry for the ¹⁸F-radiolabeled ¹⁸F-FNP-59 is described, and rodent radiation dosimetry studies and in vivo imaging in New Zealand rabbits was performed. After in vivo toxicity studies, an investigational new drug approval was obtained, and the first-in-humans images with dosimetry using the agent were acquired. Results: In vivo toxicity studies demonstrated that FNP-59 is safe for use at the intended dose. Biodistribution studies with ¹⁸F-FNP-59 demonstrated a pharmacokinetic profile similar to that of NP-59 but with decreased radiation exposure. In vivo animal images demonstrated expected uptake in tissues that use cholesterol: gallbladder, liver, and adrenal glands. In this first-in-humans study, subjects had no adverse events and images demonstrated accumulation in target tissues (liver and adrenal glands). Manipulation of uptake was also demonstrated with patients who received cosyntropin, resulting in improved uptake. Conclusion: ¹⁸F-FNP-59 provided higher resolution images, with lower radiation dose to the subjects. It has the potential to provide a noninvasive test for patients with adrenocortical diseases.

Influence of cortisol cosecretion on non-ACTH-stimulated adrenal venous sampling in primary aldosteronism: a retrospective cohort study

OBJECTIVE

Cortisol measurements are essential for the interpretation of adrenal venous samplings (AVS) in primary aldosteronism (PA). Cortisol cosecretion may influence AVS indices. We aimed to investigate whether cortisol cosecretion affects non-adrenocorticotrophic hormone (ACTH)-stimulated AVS results.

DESIGN

Retrospective cohort study at a tertiary referral center.

METHODS

We analyzed 278 PA patients who underwent non-ACTH-stimulated AVS and had undergone at least a 1-mg dexamethasone suppression test (DST). Subsets underwent additional late-night salivary cortisol (LSC) and/or 24-h urinary free cortisol (UFC) measurements. Patients were studied from 2013 to 2020 with follow-up data of 6 months following adrenalectomy or mineralocorticoid antagonist therapy initiation. We analyzed AVS parameters including adrenal vein aldosterone/cortisol ratios, selectivity, lateralization (LI) and contralateral suppression indices and post-operative ACTH-stimulation. We classified outcomes according to the primary aldosteronism surgical outcome (PASO) criteria.

RESULTS

Among the patients, 18.9% had a pathological DST result (1.9-5 µg/dL: n = 44 (15.8%); >5 µg/dL: n = 8 (2.9%)). Comparison of AVS results stratified according to the 1-mg DST (≤1.8 vs >1.8 µg/dL: P = 0.499; ≤1.8 vs 1.8 ≤ 5 vs >5 µg/dL: P = 0.811) showed no difference. Lateralized cases with post DST serum cortisol values > 5 µg/dL had lower LI (≤1.8 µg/dL: 11.11 (5.36; 26.76) vs 1.9-5 µg/dL: 11.76 (4.9; 31.88) vs >5 µg/dL: 2.58 (1.67; 3.3); P = 0.008). PASO outcome was not different according to cortisol cosecretion.

CONCLUSIONS

Marked cortisol cosecretion has the potential to influence non-ACTH-stimulated AVS results. While this could result in falsely classified lateralized cases as bilateral, further analysis of substitutes for cortisol are required to unmask effects on clinical outcome.

Adrenal functional imaging - which marker for which indication?

PURPOSE OF REVIEW

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.

RECENT FINDINGS

Numerous radiotracers for assessment of adrenal incidentalomas ([18F]FDG; [123I]IMTO/IMAZA), ACC ([123I]IMTO/IMAZA; [18F]FDG; [68Ga]PentixaFor), pheochromocytomas and paragangliomas ([123I]mIBG; [18F]flubrobenguane; [18F]AF78; [68Ga]DOTATOC/-TATE), or primary aldosteronism ([11C]MTO, [68Ga]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.

SUMMARY

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.

CXCR4-directed [68Ga]Ga-PentixaFor PET/CT versus adrenal vein sampling performance: a study protocol for a randomised two-step controlled diagnoStic Trial Ultimately comparing hypertenSion outcome in primary aldosteronism (CASTUS)

INTRODUCTION

Primary aldosteronism (PA) is the most common form of secondary hypertension. It is caused by overproduction of aldosterone by either a unilateral aldosterone-producing adenoma (APA) or by bilateral adrenal hyperplasia (BAH). Distinction is crucial, because PA is cured by adrenalectomy in APA and is treated by mineralocorticoid receptor antagonists in BAH. The distinction is currently made by adrenal vein sampling (AVS). AVS is a costly, invasive and complex technical procedure with limited availability and is not superior in terms of outcomes to CT scan-based diagnosis. Thus, there is a need for a cheaper, non-invasive and readily available diagnostic tool in PA. We propose a new diagnostic imaging modality employing the positron emission tomography (PET) tracer [⁶⁸Ga]Ga-PentixaFor. This tracer has high focal uptake in APAs, whereas low uptake was shown in patients with normal adrenals. Thus, [⁶⁸Ga]Ga-PentixaFor PET/CT is an imaging modality with the potential to improve subtyping of PA. It is readily available, safe and, as an out-patient procedure, much cheaper diagnostic method than AVS.

METHODS AND ANALYSIS

We present a two-step randomised controlled trial (RCT) protocol in which we assess the accuracy of [⁶⁸Ga]Ga-PentixaFor PET/CT in the first step and compare [⁶⁸Ga]Ga-PentixaFor PET/CT to AVS in the second step. In the first step, the concordance will be determined between [⁶⁸Ga]Ga-PentixaFor PET/CT and AVS and a concordance probability is calculated with a Bayesian prediction model. In the second step, we will compare [⁶⁸Ga]Ga-PentixaFor PET/CT and AVS for clinical outcome and intensity of hypertensive drug use defined as daily defined doses in a RCT.

ETHICS AND DISSEMINATION

Ethics approval was acquired from the medical ethical committee East-Netherlands (METC Oost-Nederland). Results will be disseminated through peer-reviewed articles.

TRIAL REGISTRATION NUMBER

NL9625.

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.

Integration of molecular imaging in the personalized approach of patients with adrenal masses

Adrenal masses are a frequent finding in clinical practice. Many of them are incidentally discovered with a prevalence of 4% in patients undergoing abdominal anatomic imaging and require a differential diagnosis. Biochemical tests, evaluating hormonal production of both adrenal cortex and medulla (in particular, mineralocorticoids, glucocorticoids and catecholamines), have a primary importance in distinguishing functional or non-functional lesions. Conventional imaging techniques, in particular computerized tomography (CT) and magnetic resonance imaging (MRI), are required to differentiate between benign and malignant lesions according to their appearance (size stability, contrast enhanced CT and/or chemical shift on MRI). In selected patients, functional imaging is a non-invasive tool able to explore the metabolic pathways involved thus providing additional diagnostic information. Several single photon emission tomography (SPET) and positron emission tomography (PET) radiopharmaceuticals have been developed and are available, each of them suitable for studying specific pathological conditions. In functional masses causing hypersecreting diseases (mainly adrenal hypercortisolism, primary hyperaldosteronism and pheochromocytoma), functional imaging can lateralize the involvement and guide the therapeutic strategy in both unilateral and bilateral lesions. In non-functioning adrenal masses with inconclusive imaging findings at CT/MR, [¹⁸F]-FDG evaluation of tumor metabolism can be helpful to characterize them by distinguishing between benign nodules and primary malignant adrenal disease (mainly adrenocortical carcinoma), thus modulating the surgical approach. In oncologic patients, [¹⁸F]-FDG uptake can differentiate between benign nodule and adrenal metastasis from extra-adrenal primary malignancies.

Adrenal functional imaging

Given the more widespread use of conventional imaging techniques such as magnetic resonance imaging or computed tomography, recent years have witnessed an increased rate of incidental findings in the adrenal gland and those adrenal masses can be either of benign or malignant origin. In this regard, routinely conducted morphological imaging cannot always reliably distinguish between cancerous and noncancerous lesions. As such, those incidental adrenal masses trigger further diagnostic work-up, including molecular functional imaging providing a non-invasive read-out on a sub-cellular level. For instance, [¹⁸F]FDG positron emission tomography (PET) as a marker of glucose consumption has been widely utilized to distinguish between malignant vs benign adrenal lesions. In addition, more adrenal cortex-targeted radiotracers for PET or single photon emission computed tomography have entered the clinical arena, e.g., Iodometomidate or IMAZA, which are targeting CYP11B enzymes, or Pentixafor identifying CXCR4 in adrenal tissue. All these tracers are used for diagnosing tumors deriving from the adrenal cortex. Furthermore, radiolabeled MIBG, DOPA, and DOTATOC/-TATE are radiotracers that are quite helpful in detecting pheochromocytomas originating from the adrenal medulla. Of note, after having quantified the retention capacities of the target in-vivo, such radiotracers have the potential to be used as anti-cancer therapeutics by using their therapeutic equivalents in a theranostic setting. The present review will summarize the current advent of established and recently introduced molecular image biomarkers for investigating adrenal masses and highlight its transformation beyond providing functional status towards image-guided therapeutic approaches, in particular in patients afflicted with adrenocortical carcinoma.

Validation of three novel clinical prediction tools for primary aldosteronism subtyping

The 20-point clinical prediction SPACE score, the aldosterone-to-lowest potassium ratio (APR), aldosterone concentration (AC) and the AC relative reduction rate after saline infusion test (SIT) have recently been proposed for primary aldosteronism (PA) subtyping prior to adrenal vein sampling (AVS). To validate those claims, we performed a retrospective cross-sectional study that included all patients at our center who had positive SIT to confirm PA and were diagnosed with either bilateral disease (BPA) according to AVS or with lateralized disease (LPA) if biochemically cured after adrenalectomy from November 2004 to the end of 2019. Final diagnoses were used to evaluate the diagnostic performance of proposed clinical prediction tools. Our cohort included 144 patients (40 females), aged 32-72 years (mean 54 years); 59 with LPA and 85 with BPA. The originally suggested SPACE score ≤8 and SPACE score >16 rules yielded about 80% positive predictive value (PPV) for BPA and LPA, respectively. Multivariate analyses with the predictors constituting the SPACE score highlighted post-SIT AC as the most important predictor of PA subtype for our cohort. APR-based tool of <5 for BPA and >15 for LPA yielded about 75% PPV for LPA and BPA. The proposed post-SIT AC <8.79 ng/dL criterion yielded 41% sensitivity and 90% specificity, while the relative post-SIT AC reduction rate of >33.8% criterion yielded 80% sensitivity and 51% specificity for BPA prediction. The application of any of the validated clinical prediction tools to our cohort did not predict the PA subtype with the high diagnostic performance originally reported.

Japan Endocrine Society clinical practice guideline for the diagnosis and management of primary aldosteronism 2021

Primary aldosteronism (PA) is associated with higher cardiovascular morbidity and mortality rates than essential hypertension. The Japan Endocrine Society (JES) has developed an updated guideline for PA, based on the evidence, especially from Japan. We should preferentially screen hypertensive patients with a high prevalence of PA with aldosterone to renin ratio ≥200 and plasma aldosterone concentrations (PAC) ≥60 pg/mL as a cut-off of positive results. While we should confirm excess aldosterone secretion by one positive confirmatory test, we could bypass patients with typical PA findings. Since PAC became lower due to a change in assay methods from radioimmunoassay to chemiluminescent enzyme immunoassay, borderline ranges were set for screening and confirmatory tests and provisionally designated as positive. We recommend individualized medicine for those in the borderline range for the next step. We recommend evaluating cortisol co-secretion in patients with adrenal macroadenomas. Although we recommend adrenal venous sampling for lateralization before adrenalectomy, we should carefully select patients rather than all patients, and we suggest bypassing in young patients with typical PA findings. A selectivity index ≥5 and a lateralization index >4 after adrenocorticotropic hormone stimulation defines successful catheterization and unilateral subtype diagnosis. We recommend adrenalectomy for unilateral PA and mineralocorticoid receptor antagonists for bilateral PA. Systematic as well as individualized clinical practice is always warranted. This JES guideline 2021 provides updated rational evidence and recommendations for the clinical practice of PA, leading to improved quality of the clinical practice of hypertension.

Intraoperative fluorescence molecular imaging accelerates the coming of precision surgery in China

Purpose

China has the largest cancer population globally. Surgery is the main choice for most solid cancer patients. Intraoperative fluorescence molecular imaging (FMI) has shown its great potential in assisting surgeons in achieving precise resection. We summarized the typical applications of intraoperative FMI and several new trends to promote the development of precision surgery.

Methods

The academic database and NIH clinical trial platform were systematically evaluated. We focused on the clinical application of intraoperative FMI in China. Special emphasis was placed on a series of typical studies with new technologies or high-level evidence. The emerging strategy of combining FMI with other modalities was also discussed.

Results

The clinical applications of clinically approved indocyanine green (ICG), methylene blue (MB), or fluorescein are on the rise in different surgical departments. Intraoperative FMI has achieved precise lesion detection, sentinel lymph node mapping, and lymphangiography for many cancers. Nerve imaging is also exploring to reduce iatrogenic injuries. Through different administration routes, these fluorescent imaging agents provided encouraging results in surgical navigation. Meanwhile, designing new cancer-specific fluorescent tracers is expected to be a promising trend to further improve the surgical outcome.

Conclusions

Intraoperative FMI is in a rapid development in China. In-depth understanding of cancer-related molecular mechanisms is necessary to achieve precision surgery. Molecular-targeted fluorescent agents and multi-modal imaging techniques might play crucial roles in the era of precision surgery.

Reassessment of Postural Stimulation Testing as a Simple Tool to Identify a Subgroup of Patients With Unilateral Primary Aldosteronism

CONTEXT

Adrenal vein sampling (AVS) represents the current diagnostic gold standard for differentiation between unilateral and bilateral primary aldosteronism (PA). Postural stimulation testing (PST) has been used to provide additional diagnostic information.

OBJECTIVE

This work aimed to evaluate the diagnostic utility of PST in the differential diagnosis of PA.

METHODS

This cohort study was conducted at a single tertiary reference center. We analyzed 106 PST performed between 2008 and 2020. Diagnosis of PA and cause of PA were determined according to the Endocrine Society Clinical Practice Guideline, taking into account results of saline infusion testing, AVS, preoperative imaging, and outcome after medical or surgical treatment. The suggested cutoffs for the diagnosis of unilateral PA were revisited and optimized for high specificity using receiver operating characteristics (ROC) analysis.

RESULTS

A total of 106 patients had confirmed PA (unilateral PA: n = 55, bilateral PA: n = 29, AVS unsuccessful/declined by patients: n = 22). Based on decreased aldosterone plasma concentration of 28% or more after 4 hours in the upright position, the PST showed a sensitivity of 36.4% at a specificity of 100% to identify unilateral disease (area under the curve [AUC] = 0.72; 95% CI, 0.62-0.83; P = .001). In patients with valid testing (drop of cortisol of 10% or more after 4 hours, n = 53) the sensitivity of PST rose to 51.4% at a specificity of 100% (AUC = 0.77; 95% CI, 0.65-0.90; P = .001).

CONCLUSION

The high specificity of 100% for the detection of unilateral PA in patients with decreased aldosterone by at least 28% after 4 hours makes PST a simple, noninvasive contribution to subtype differentiation in PA.

Diagnosis and treatment of primary aldosteronism

Primary aldosteronism is a common cause of secondary hypertension associated with excess cardiovascular morbidities. Primary aldosteronism is underdiagnosed because it does not have a specific, easily identifiable feature and clinicians can be poorly aware of the disease. The diagnostic investigation is a multistep process of screening, confirmatory testing, and subtype differentiation of unilateral from bilateral forms for therapeutic management. Adrenal venous sampling is key for reliable subtype identification, but can be bypassed in patients with specific characteristics. For unilateral disease, surgery offers the possibility of cure, with total laparoscopic unilateral adrenalectomy being the treatment of choice. Bilateral forms are treated mainly with mineralocorticoid receptor antagonists. The goals of treatment are to normalise both blood pressure and excessive aldosterone production, and the primary aims are to reduce associated comorbidities, improve quality of life, and reduce mortality. Prompt diagnosis of primary aldosteronism and the use of targeted treatment strategies mitigate aldosterone-specific target organ damage and with appropriate patient management outcomes can be excellent. Advances in molecular histopathology challenge the traditional concept of primary aldosteronism as a binary disease, caused by either a unilateral aldosterone-producing adenoma or bilateral adrenal hyperplasia. Somatic mutations drive autonomous aldosterone production in most adenomas. Many of these same mutations have been identified in nodular lesions adjacent to an aldosterone-producing adenoma and in patients with bilateral disease. In addition, germline mutations cause rare familial forms of aldosteronism (familial hyperaldosteronism types 1-4). Genetic testing for inherited forms in suspected cases of familial hyperaldosteronism avoids the burdensome diagnostic investigation in positive patients. In this Review, we discuss advances and future management approaches in the diagnosis of primary aldosteronism.

Current status and future perspective of radiopharmaceuticals in China

Radiopharmaceuticals are essential components of nuclear medicine and serve as one of the cornerstones of molecular imaging and precision medicine. They provide new means and approaches for early diagnosis and treatment of diseases. After decades of development and hard efforts, a relatively matured radiopharmaceutical production and management system has been established in China with high-quality facilities. This review provides an overview of the current status of radiopharmaceuticals on production and distribution, clinical application, and regulatory supervision and also describes some important advances in research and development and clinical translation of radiopharmaceuticals in the past 10 years. Moreover, some prospects of research and development of radiopharmaceuticals in the near future are discussed.

Identification of Surgically Curable Primary Aldosteronism by Imaging in a Large, Multiethnic International Study

CONTEXT

Adrenal gland imaging is recommended by the current guidelines for the workup of primary aldosteronism (PA). However, its diagnostic performance has not been established in large, multiethnic cohorts of patients who undergo adrenal vein sampling (AVS) and adrenalectomy.

OBJECTIVE

This work aims to assess the diagnostic accuracy of cross-sectional adrenal imaging.

METHODS

This international multicenter study took place in tertiary referral centers. A total of 1625 PA patients seeking surgical cure were enrolled in an international study involving 19 centers in North America, Europe, Asia, and Australia. Of these, 1311 (81%) had imaging data available and 369 (23%), who received a final diagnosis of surgically cured unilateral PA, were examined. Patients underwent AVS and imaging by computed tomography and/or magnetic resonance imaging. The accuracy of detection of unilateral PA at imaging was estimated by the area under the receiver operator characteristics curve using cure (biochemical and/or full clinical success) as the reference at follow-up after unilateral adrenalectomy.

RESULTS

In the cohort of 1311 patients with imaging data available, 34% and 7% of cases showed no detectable or bilateral nodules, respectively. Imaging did not detect the culprit adrenal in 28% of the surgically cured unilateral PA patients. Moreover, the clinical outcome did not differ significantly between the imaging-positive and imaging-negative patients.

CONCLUSION

Cross-sectional imaging did not identify a lateralized cause of disease in around 40% of PA patients and failed to identify the culprit adrenal in more than one-fourth of patients with unilateral PA.

Adrenal Venous Sampling for Subtype Diagnosis of Primary Hyperaldosteronism

Adrenal venous sampling (AVS) is the key procedure for lateralization of primary hyperaldosteronism (PA) before surgery. Identification of the adrenal veins using computed tomography (CT) and intraoperative cortisol assay facilitates the success of catheterization. Although administration of adrenocorticotropic hormone (ACTH) has benefits such as improving the success rate, some unilateral cases could be falsely diagnosed as bilateral. Selectivity index of 5 with ACTH stimulation to assess the selectivity of catheterization and lateralization index (LI) >4 with ACTH stimulation for unilateral diagnosis is used in many centers. Co-secretion of cortisol from the tumor potentially affects the lateralization by the LI. Patients aged <35 years with hypokalemia, marked aldosterone excess, and unilateral adrenal nodule on CT have a higher probability of unilateral disease. Patients with normokalemia, mild aldosterone excess, and no adrenal tumor on CT have a higher probability of bilateral disease. Although no methods have 100% specificity for subtype diagnosis that would allow bypassing AVS, prediction of the subtype should be considered when recommending AVS to patients. Methodological standardization and strict indication improve diagnostic quality of AVS. Development of non-invasive imaging and biochemical markers will drive a paradigm shift in the clinical practice of PA.

Steroidogenic cell microenvironment and adrenal function in physiological and pathophysiological conditions

The human adrenal cortex is a complex organ which is composed of various cell types including not only steroidogenic cells but also mesenchymal cells, immunocompetent cells and neurons. Intermingling of these diverse cell populations favors cell-to-cell communication processes involving local release of numerous bioactive signals such as biogenic amines, cytokines and neuropeptides. The resulting paracrine interactions play an important role in the regulation of adrenocortical cell functions both in physiological and pathophysiological conditions. Especially, recent evidence indicates that adrenocortical cell microenvironment is involved in the pathogenesis of adrenal disorders associated with corticosteroid excess. The paracrine factors involved in these intraadrenal regulatory mechanisms may thus represent valuable targets for future pharmacological treatments of adrenal diseases.

Functional characterization of adrenocortical masses in nononcological patients using [68Ga]-pentixafor

Purpose: We aimed to investigate the diagnostic and prognostic value of ⁶⁸Ga-pentixafor positron emission tomography (PET)/computed tomography (CT) imaging in non-cancer patients with suspected adrenal masses. Methods: Sixty-four patients who had benign adrenal masses on CT were retrospectively included in our study. All patients underwent ⁶⁸Ga-pentixafor PET/CT scans, and 56 of these patients subsequently underwent adrenalectomy. The subtypes of 81 adrenal tumors including 14 nonfunctioning adrenal nodules, 4 cortisol-producing adenomas, 41 aldosterone-producing adenomas, 5 suspected unilateral adrenal hyperplasia, 15 idiopathic aldosterone hyperplasia and 2 pheochromocytomas, were determined by histology or follow-up evaluations. The functional lateralization diagnosis efficiency was calculated by visual analysis. Semi-quantitative parameters of these lesions including maximum standardized uptake value (SUV_max), the ratio of lesional SUV_max to normal liver SUVmean (LLR), and the ratio of lesional SUV_max to contralateral adrenal tissue SUVmean (LCR) have also been calculated. Dynamic analysis has also been performed on fifteen patients. Besides, clinical outcomes were assessed and compared in patients who underwent adrenalectomy. Results: The sensitivity and specificity of ⁶⁸Ga-pentixafor PET for functional lateralization of patients with adrenocortical lesions were 97.8% (45/46) and 87.5% (14/16) respectively. The two pheochromocytoma lesions had lower pentixafor uptake compared to the normal adrenal glands. Functioning (active) adrenocortical adenomas showed an elevated SUV_max of 16.3±7.9 in comparison to 4.4±1.7 in nonfunctioning (inactive) adenomas and 5.5±2.7 in hyperplasia lesions (P<0.0001). To identify active adrenocortical adenomas, a cutoff value of 7.1 for SUV_max showed a sensitivity of 90.9% and a specificity of 85.3% (AUC=0.96, P<0.0001); a cutoff value of 2.5 for LLR showed a sensitivity of 95.5% and a specificity of 88.2% (AUC=0.97, P<0.0001); and a cutoff value of 2.4 for LCR showed a sensitivity of 88.6% and a specificity of 91.8% (AUC=0.95, P<0.0001). The graphical Ki of active adrenocortical adenomas was significantly higher than in-active adenomas. Uptake values for ⁶⁸Ga-pentixafor were significantly higher in patients with preferable outcomes (cured/improved) (SUV_max=15.5±8.0, LLR=6.5±4.3, LCR=6.2±5.0) than in patients with nonpreferable outcomes (no improvement) (SUV_max=4.2±0.5, LLR=1.3±0.2, LCR =1.5±0.6, all P<0.0001). Conclusion: ⁶⁸Ga-pentixafor PET/CT imaging exhibits great potential for noninvasive functional lateralization and characterization of patients with adrenocortical masses.

A Clinical Challenge: Endocrine and Imaging Investigations of Adrenal Masses

Incidentalomas are reported in 3%-4% of patients who undergo abdominal anatomic imaging, making adrenal mass evaluation a common occurrence. An adrenal mass can be caused by a variety of pathologies, such as benign cortical and medullary tumors, malignant tumors (primary or secondary), cysts, hyperplasia, hemorrhage, or more rarely infection/inflammation processes. Functioning tumors usually have increased hormonal production but they are less common. Regardless of their functional status, some tumors have the potential to behave aggressively. Anatomic and functional imaging together with biologic evaluation play a vital role in adrenal pathology subtyping. Most patients are initially evaluated by CT or MRI, which allows for tumor characterization (to a certain extent) and can rule out malignant behavior based on the absence of tumor growth during longitudinal follow-up. In the remaining patients for whom CT or MRI fail to characterize the pathogenesis of adrenal tumors, the use of specialized molecular imaging techniques should be performed after hormonal screening. This review emphasizes well-established and emerging nuclear medicine imaging modalities and describes their use across various clinical scenarios.

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.