Adrenal neoplasms: Effectiveness and safety of CT-guided ablation of 23 tumors in 22 patients

Partial biochemical response of adrenal artery embolization for pheochromocytoma: A case report and review of the literature

We present the case of a 22-year-old male with a left adrenal pheochromocytoma, initially diagnosed during a workup for thoracic pain. The patient's tumor was refractory to medical management, and surgical resection was ruled out due to high cardiovascular risk, stemming from cyanotic congenital heart disease, aortic aneurysm, and factor VII deficiency. The patient underwent adrenal artery embolization (AAE) as a salvage treatment. Following the procedure, there was an initial reduction in hypertensive crises and biochemical markers, with plasma normetanephrine levels decreasing from 1490 pg/mL to 313 pg/mL. However, over subsequent months, the patient experienced symptom recurrence, and biochemical relapse occurred, with normetanephrine levels rising to 742 pg/mL by 3 months postprocedure. This case highlights the potential for AAE to provide short-term symptom relief and biochemical response; nevertheless, it may not be an effective long-term curative option. More collaborative and prospective studies are needed to assess its success and efficacy.

Safety and efficacy of thermal ablation of adrenal metastases secondary to lung cancer

OBJECTIVES

Assess safety and efficacy of thermal ablation for adrenal metastases (AM) secondary to non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

This retrospective study included patients with NSCLC AM treated with thermal ablation between 2/2010-11/2021. Local tumor progression free survival (LTPFS) and overall survival (OS) were calculated using Kaplan-Meier method. Adverse events were graded using Common Terminology Criteria for Adverse Events v5.

RESULTS

Seven patients (mean age ± SD, 63.9 ± 12.5 years; 6 males) with seven AM were treated in eight sessions. Retreatment was performed in one patient with residual disease. Five sessions were with microwave ablation and 3 with radiofrequency ablation. Mean tumor size was 20.1 ± 7.0 mm. Median number of ablation probes used was 1 (range, 1-5), with a median of 3 activations (range, 1-3), and average ablation time of 14.4 ± 15.0 minutes. Response based on RECIST v 1.1 or PERCIST criteria revealed stable disease in 1 tumor, progression of disease in 3 tumors (one was re-ablated), and partial response in 3 tumors. Median LTPFS was not reached (NR) [95 % CI: 1- NR]. Median OS was 47.97 months (95 % CI: 18.63- NR). Intraprocedural hypertension (blood pressure ≥180 mmHg) occurred during 5/8 (62.5 %) sessions and intraoperative tachycardia occurred during 2/8 (25 %) sessions. Complications within one month of ablation occurred in 3/8 (37.5 %) sessions: grade 2 pneumothorax, grade 1 hematuria, and grade 2 adrenal insufficiency.

CONCLUSIONS

In this small series, thermal ablation for NSCLC AM resulted in prolonged local control and OS with no major complications.

The Role of Laser and Microwave in Treatment of Endocrine Disorders: A Systematic Review

Introduction: The treatment of endocrine problems like thyroid disease, diabetes mellitus (DM), and polycystic ovary syndrome (PCOS) faces significant challenges so that medical professionals worldwide try to find a new therapeutic approach. However, along with common treatments which include medications, hormone replacement therapy, and surgery; there is a growing interest in alternative therapies like laser therapy, which offers a non-invasive and unique technique for treating endocrine disorders alone or in combination with traditional methods. The main goal of this review was to do a systematic review on the role of the laser and Microwave in the treatment endocrine disorders. Methods: In the present systematic review, the most important databases, including PubMed, Scopus and Google Scholar, were searched for the studies examining the effect of lasers on the treatment of endocrine problems by using appropriate keywords and specific strategies from 1995 to 2023. All the studies that were not about lasers and endocrine were excluded. Results: Based on 51 reviewed studies, lasers and radiofrequency ablation such as RFA are effective in the treatment of thyroid diseases, hyperparathyroidism, pancreatic disorders, and sexual dysfunctions. Laser-induced interstitial thermal therapy (LITT) and microwave ablation (MWA) are genuine minimally invasive methods for the treatment of benign nodules, adenomas, and tumor ablation including pancreatic carcinomas and adrenal tumors. Intravenous laser blood irradiation (ILBI) which uses red, UV, and blue light could be effective in treating various metabolic disorders, such as DM. Conclusion: Laser as a cutting-edge and minimally invasive approach could treat various endocrine disorders. It has a great potential to treat and regulate hormonal imbalances, decrease inflammation, and relieve symptoms of various ailments, such as endocrine disorders.

Intraoperative radiofrequency ablation for unresectable abdominal paraganglioma: a case report

For pheochromocytoma and paraganglioma (PPGL), the efficacy of percutaneous ablative therapies in achieving control of metastatic tumors measuring <3 cm had been demonstrated in only few reports, and intraoperative radiofrequency ablation (RFA) of locally invasive primary PPGLs has not been reported. We presented the case of a 31-year-old man who had a 9-cm functioning unresectable PPGL. He was treated with 13 cycles of cytotoxic chemotherapy without objective tumor response, according to the Response Evaluation Criteria in Solid Tumors (RECIST). Subsequently, magnetic resonance imaging revealed a 9.0 × 8.6 × 6.0-cm retroperitoneal mass that extended to the inferior portion of the inferior vena cava, the inferior mesenteric artery, and the infrarenal aorta. Biochemical evaluation demonstrated high level of plasma normetanephrine (20.2 nmol/L, normal range <0.9 nmol/L). Genetic investigation showed the germline pathogenic variant c.1591delC (p. Ser198Alafs*22) in the SDHB gene. I131-metaiodobenzylguanidine scintigraphy was negative and Ga68-dotatate PET-CT scan showed high tumor uptake without distant metastases. On open laparotomy, tumor debulking was not possible. Therefore, intraoperative RFA was performed by a highly experienced team of interventional radiologists. At 12 months after the RFA, the tumor volume decreased from 208 to 45 mL (78%), plasma normetanephrine decreased from 20.2 to 2.6 nmol/L (87%), and the doxazosin dose was reduced from 16 to 8 mg/day. To our best knowledge, this was the first report on intraoperative RFA that markedly reduced the size of a large primary unresectable PPGL, along with clinical and biochemical responses.

Robot-Assisted Needle Insertion for CT-Guided Puncture: Experimental Study with a Phantom and Animals

PURPOSE

This study aimed to evaluate the accuracy and safety of robotic CT-guided needle insertion in phantom and animal experiments.

MATERIALS AND METHODS

A robotic system was developed for CT-guided needle insertion. For the phantom experiment, a specially made phantom containing multiple spherical was used. 15 robotic and manual insertions were conducted, and the accuracy, time, number of needle insertions, and radiation dose were compared between the robotic and manual insertion using Student's t-test. For the animal experiment, 20 robotic needle insertions were attempted toward simulated pulmonary nodules in the swine lung. The accuracy and safety of robotic CT-guided needle insertions were evaluated.

RESULTS

In the phantom experiment, the mean accuracies of manual and robotic insertion were 1.8 ± 0.3 mm and 1.9 ± 0.2 mm. The accuracy of robotic needle insertion had no significant difference with manual needle insertion, but the number of needle insertions and radiation dose of the robotic needle placement significantly decreased compared to manual needle placement. In the animal experiment, the mean accuracy of the robotic needle insertion was 3.8 ± 1.3 mm. The time for the whole needle insertion was 14.4 ± 4.8 min. The whole robotic needle insertions were safe and only one mild pneumothorax occurred.

CONCLUSION

CT-guided robotic needle insertion showed accuracy comparable to manual needle insertion, but the number of needle insertions, confirmatory scans, and radiation exposure had been reduced significantly. In future, we will further apply the robotic system to clinical experiments.

MWA Performed at 5.8 GHz through 'Side Firing' Approach: An Exploratory Study

Recent studies have shown that ablation techniques have the potential to eradicate adrenal adenomas while preserving the functionalities of the adrenal gland and the surrounding anatomical structures. This study explores a new microwave ablation (MWA) approach operating at 5.8 GHz and using anatomical and dielectric characteristics of the target tissue to create directional heating patterns. Numerical simulations are executed in planar and 3D adrenal models, considering two energy doses. The numerical study is refined accounting for the vaporization of the tissue water content. Ex vivo experimental evaluations on porcine adrenal models complete the study. The numerical and experimental results show that spherical ablation zones are able to cover the target for both energy doses considered. Nonetheless, most of the non-targeted tissues can be preserved from excessive heating when low energy level is used. Numerical models accounting for water vaporization are capable to foresee the experimental temperature values. This study shows that the proposed MWA directional approach operating at 5.8 GHz can be considered for creating effective and selective ablation zones.

Management of adreno-cortical adenomas using microwave ablation: study of the effects of the fat tissue

BACKGROUND AND OBJECTIVES

Adrenocortical neoplasms are the main causes of secondary hypertension and related comorbidities including hypokalemia and cardiovascular diseases. Conventional techniques for the management of this condition are often invasive and not resolutive. Recent studies proposed microwave thermal ablation (MWA) to eradicate adrenocortical adenomas arising in proximity to sensitive structures. This study explores a new MWA approach to selectively direct the electromagnetic energy into the target and shield the surrounding tissues. The new solution relies on the anatomical and dielectric characteristics of the adrenal gland and the surrounding fat capsule.

METHODS

A 3 D model of the adrenal gland is developed, and a cooled microwave applicator is placed parallel to the interface between the fat and adrenal tissue. Numerical simulations are conducted at 2.45 GHz accounting for two energy delivery settings, two orientations of the applicator and blood perfusion of the tissues. Ex vivo and in vivo ablation procedures are conducted on ovine adrenal glands. Histology analysis completes the experimental studies.

RESULTS

Numerical results show asymmetric ablation profiles in ex vivo and in vivo conditions. The asymmetry ratio is influenced by the procedure settings and orientation of the applicator. Ablation zones obtained experimentally agree with those predicted by the numerical simulations. Histology analysis confirms irreversible cellular changes only in the adrenal tissue close to the applicator.

CONCLUSIONS

The outcomes show that the dielectric contrast between the fat layer and tissue target can be a tool in MWA to shape ablation zones to protect the surrounding structures from excessive temperature increases.

Comparison between surgery and thermal ablation for adrenal metastases: a retrospective study

PURPOSE

To retrospectively compare the efficacy and safety of surgical resection (SR) and thermal ablation for the treatment of adrenal metastases.

METHODS

From January 2008 to December 2018, 133 patients with adrenal metastases who underwent SR (n = 76) or thermal ablation (n = 57) were enrolled. The mean tumor size was 58.00 ± 10.65 mm (22-80 mm) in the SR group and 58.03 ± 12.76 mm (34-89 mm) in the thermal ablation group. Local progression-free survival (LPFS) and safety were compared between the two groups using the Kaplan-Meier method and log-rank tests. Cox proportional hazard regression models were used to evaluate the prognostic factors of LPFS. Complications, hospitalization days, and blood loss were also assessed.

RESULTS

The median follow-up was 29.0 months (range, 20.4-37.6 months). No treatment-related mortality was observed. The 1-, 3- and 5-year LPFS rates were 74.0%, 62.8%, and 31.4% in the SR group and 72.8%, 68.7%, and 51.5% in the ablation group, with the median LPFS of 41.5 months (95% CI: 9.3-23.4 months) vs. 47.9 months (95% CI 20.6-75.8 months), respectively (p = 0.784). Tumor size ≥3 cm was the only significant risk factor for LPFS (p = 0.031). The ablation group was superior to the SR group with a lower major complication rate (4.1% vs. 14.5%, p = 0.03), less blood loss (1 ml vs. 100 ml, p < 0.001), and a shorter hospital stay (2 d vs. 6 d, p < 0.001).

CONCLUSION

Thermal ablation provided a similar LPFS and less comorbidities than SR, indicating that it is an effective and safe treatment for adrenal metastases.

Percutaneous image-guided radiofrequency ablation for adrenal tumours: a systematic review

AIM

To undertaken a systematic review of the technical success and technique efficacy rates of percutaneous image-guided radiofrequency ablation (RFA) for adrenal tumours.

MATERIALS AND METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, the electronic databases MEDLINE, EMBASE, and PubMed were searched for relevant studies from inception to the third week of January 2020. Only studies reporting effectiveness rates of percutaneous RFA for adrenal tumours were included. Data regarding sample size, tumours, effectiveness rates, outcomes, and complications were extracted in duplicate and recorded.

RESULTS

A total of 15 studies evaluating 292 individuals with 305 tumours were included. Patient selection criteria included age ≥18 years, contraindication to surgical intervention, and no uncorrected coagulopathy. Cumulative technical success, primary technique efficacy, and secondary technique efficacy rates were 99%, 95.1% and 100%, respectively, indicating optimal immediate control of adrenal tumours. Technical success and technique efficacy rates of primary adrenal tumours were higher than adrenal metastases; however, formal statistical analyses were precluded due to lack of comparative studies. Local tumour progression rates for adrenal metastases were 20.3% at 3 months, 26.3% at 6 months, and 29.3% at 12 months. Overall survival rates for adrenal metastases were 81.8% at 6 months, 59.6% at 12 months, and 62.9% at 18 months. The intraprocedural complication rate was 30.2%, with the most frequency reported complication being procedural hypertensive crisis.

CONCLUSION

The findings of this study suggest percutaneous image-guided RFA is a safe and efficacious procedure. Further studies are warranted to define patient selection criteria and long-term outcomes.

Comparison of the radiofrequency ablation versus laparoscopic adrenalectomy for aldosterone-producing adenoma: a meta-analysis of perioperative outcomes and safety

Radiofrequency ablation (RFA) has emerged as a new treatment for primary aldosteronism owing to aldosterone-producing adenoma (APA). We aimed to compare the perioperative outcomes and safety of RFA and laparoscopic adrenalectomy (LA) for patients with APA. We searched PubMed, EMBASE, and the Cochrane Library for all literatures published from January 2001 to September 2020 to compare RFA with LA for APA. After data extraction and quality assessments, we used Review Manager 5.4.1 and STATA 14.0 to pool the data. Four retrospective studies consisting of 170 patients were obtained. Patients who underwent RFA were associated with shorter operative time (standard mean difference (SMD): -1.98, 95% confidence interval (CI): -3.86 to 0.11, P = 0.04), less intraoperative blood loss (SMD: -0.61, 95% CI: -0.96 to -0.26, P = 0.0007), and shorter hospital stay (weight mean difference (WMD): -1.40, 95% CI: -1.71 to -1.10, P < 0.00001) than those who underwent LA. No significant differences were found in the complication rate (odds ratio (OR): 0.67, 95% CI: 0.27-1.68, P = 0.39), the incidence of hypertensive crisis (OR: 3.16, 95% CI: 0.36-27.94, P = 0.30), the conversion rate (OR: 0.44, 95% CI: 0.04-4.32, P = 0.48) or the treatment success rate (OR: 0.72, 95% CI: 0.22-2.39, P = 0.59) between the two groups. RFA could achieve clinical outcomes that approach LA for patients with APA but result in shorter operative time, less intraoperative blood loss, and shorter hospital stay. However, RFA does not appear to be able to replace the LA. Future prospective randomized trials are needed to validate these results.

Percutaneous cryoablation of adrenal metastases: technical feasibility and safety

PURPOSE

To assess the technical feasibility and outcomes of adrenal metastases cryoablation.

MATERIALS AND METHODS

This is an IRB approved retrospective review of adrenal metastases cryoablation between April 2003 and October 2018. Forty percutaneous cryoablation procedures were performed on 40 adrenal metastases in 34 patients. Histology, tumor size, ablation zone size, major vessel proximity, local recurrences, complications, and anesthesia-managed hypertension monitoring was collected. Complications were graded according to the Common Terminology of Complications and Adverse Events (CTCAE).

RESULTS

Mean tumor and ablation size was 3.2 cm and 5.2 cm, respectively. Local recurrence rate was 10.0% (N = 4/40) for a mean follow-up time of 1.8 years. Recurrences for tumors > 3 cm (21.0%, N = 4/19) was greater than for tumors ≤ 3 cm (0.0%, N = 0/21) (p = 0.027). Proximity of major vasculature (i.e., IVC & aorta) did not statistically effect recurrence rates (p = 0.52), however, those that recurred near vasculature were > 4 cm. Major complication (≥ grade 3) rate was 5.0% (N = 2/40), with one major complication attributable to the procedure. Immediate escalation of blood pressure during the passive stick phase (between freeze cycles) or post procedure thaw phase was greater in patients with residual adrenal tissue (N = 21/38) versus masses replacing the entire adrenal gland (N = 17/38), (p = 0.0020). Lower blood pressure elevation was noted in patients with residual adrenal tissue who were pre-treated with alpha blockade (p = 0.015).

CONCLUSIONS

CT-guided percutaneous cryoablation is a safe, effective and low morbidity alternative for patients with adrenal metastases. Transient hypertension is related only to residual viable adrenal tissue but can be safely managed and prophylactically treated.

Thermal ablation in adrenal disorders: a discussion of the technology, the clinical evidence and the future

PURPOSE OF REVIEW

To summarise the emerging role of thermal ablation as a therapeutic modality in the management of functioning adrenal tumours and metastases to the adrenal gland.

RECENT FINDINGS

Observational evidence has demonstrated the benefit of thermal ablation in (i) resolving adrenal endocrinopathy arising from benign adenomas, (ii) treating solitary metastases to the adrenal and (iii) controlling metastatic adrenocortical carcinoma and phaeochromocytoma/paraganglioma.

SUMMARY

Microwave thermal ablation offers a promising, minimally invasive therapeutic modality for the management of functioning adrenocortical adenomas and adrenal metastases. Appropriate technological design, treatment planning and choice of imaging modality are necessary to overcome technical challenges associated with this emerging therapeutic approach.

Asian Conference on Tumor Ablation Guidelines for Adrenal Tumor Ablation

Thermal ablation is a good alternative treatment in patients who are unable to undergo adrenalectomy. Even though the Asian Conference on Tumor Ablation (ACTA) has been held for many years, adrenal ablation guidelines have not been established. No guidelines for adrenal ablation are established in American and European countries, either. The aim of this review was to introduce the first version of ACTA guidelines for adrenal tumor ablation.

Mechanism of hypertensive crisis during energy device ablation of the adrenal gland: An experimental animal study

OBJECTIVE

To elucidate the mechanism of hypertensive crisis during energy device ablation of the adrenal gland.

METHODS

Electrocoagulation on the adrenal glands of six pigs was carried out with the same energy device (VIO300D) using four methods: (i) monopolar coagulation; (ii) monopolar soft coagulation using IO-advanced ball-type electrodes; (iii) bipolar soft coagulation by pinching; and (iv) bipolar soft coagulation by non-pinching (surface contact) using Bipolar forceps Premium. After electrocoagulation for 5 s, blood pressure and pulse changes were monitored, and adrenal hormones were measured from a central vein. The adrenal glands were removed, and the degree of tissue damage was scored histologically.

RESULTS

Hypertensive crisis occurred with electrocoagulation of the adrenal gland by the monopolar coagulation, monopolar soft coagulation and bipolar soft coagulation pinching methods. Blood pressure did not change with the bipolar soft coagulation non-pinching method. Pathologically, tissue damage to the adrenal medulla was associated with elevated blood pressure and adrenaline and noradrenaline release.

CONCLUSIONS

Hypertensive crisis caused by energy device ablation to the adrenal gland is caused by the release of catecholamines due to heat damage to the adrenal medulla rather than the type of energy device. Proper use of an energy device that does not cause thermal degeneration of the medulla is required to prevent hypertensive crisis.

Image-Guided Percutaneous Ablation of Adrenal Metastases: A Meta-Analysis of Efficacy and Safety

PURPOSE

To evaluate the efficacy and safety of percutaneous ablation of adrenal metastases through a meta-analysis of various image-guided percutaneous ablation techniques.

MATERIALS AND METHODS

A comprehensive literature search of PubMed and Embase databases was performed for studies evaluating the efficacy and/or safety of image-guided percutaneous ablation of adrenal metastases. A total of 37 studies published between 2009 and 2020 were analyzed, comprising a sample size of 959 patients. Proportion estimates of overall survival, local control, and toxicity were analyzed in a pooled meta-analysis. The pooled prevalence of adverse events after ablation was calculated based on common terminology criteria for adverse events (CTCAE) grading.

RESULTS

Of the 959 included patients, 320 (33.3%) underwent radiofrequency ablation, 72 (7.5%) microwave ablation, 95 (9.9%) cryoablation, and 46 (4.8%) ethanol injections for treatment of adrenal metastases. The remaining 426 (44.4%) patients were from studies involving a mixture of the 4 listed percutaneous ablation techniques. The pooled 1-year local control rate was 80% (95% confidence interval [CI], 76%-83%). The pooled 1-year overall survival rate was 77% (95% CI, 70%-83%). The overall rate of severe adverse events after ablation (CTCAE grade 3 or higher) was 16.1%. The overall rate of low-grade adverse events after ablation (CTCAE grade 2 or lower) was 32.6%. Approximately 21.9% (n = 203) of patients experienced intraprocedural hypertensive crises, the majority of which were reversed with antihypertensive medications.

CONCLUSIONS

This study demonstrates that image-guided percutaneous ablation can be effective in achieving acceptable short- to mid-term local tumor control and overall survival with a moderate safety profile.

Percutaneous Bilateral Adrenal Radiofrequency Ablation in Severe Adrenocorticotropic Hormone-dependent Cushing Syndrome

Objectives:

The objectives of the study were to evaluate adrenal radiofrequency ablation (RFA) as a method of treatment in patients with severe adrenocorticotropic hormone (ACTH)-dependent Cushing syndrome, among whom bilateral adrenalectomy is not a suitable option.

Material and Methods:

Five patients with ACTH-dependent Cushing syndrome underwent RFA of both adrenal glands. Four of them presented with Cushing disease unsuccessfully treated with pituitary surgery and medical therapy, while one patient had ACTH-dependent Cushing syndrome due to pancreatic endocrine tumor with liver metastases. All patients were disqualified from adrenalectomy due to morbid obesity or lack of consent.

Results:

A technical success was obtained in all cases, with only one re-intervention necessitated by a cooling effect of the inferior vena cava. Despite pre-procedural adrenergic blockade, severe hypertension was noted during the procedure in three cases, this being treated immediately using direct-acting vasodilators. No complications occurred otherwise. In all cases, significant improvement of clinical symptoms was observed, as well as marked decreases in levels of serum cortisol, free urine cortisol, and dehydroepiandrosterone sulfate.

Conclusion:

Bilateral RFA under CT-guidance is technically feasible and clinical improvement can be achieved using the method. In patients disqualified from adrenal surgery, RFA might be considered as an alternative method of ACTH-dependent Cushing syndrome treatment.

Treatment outcomes of percutaneous radiofrequency ablation versus adrenalectomy for adrenal metastases: a retrospective comparative study

PURPOSE

To retrospectively evaluate the clinical outcomes of percutaneous ultrasound (US)-guided radiofrequency ablation (RFA) in treatment of adrenal metastasis (AM), and to compare with adrenalectomy (Adx).

METHODS

From June 2008 to August 2018, a total of 60 patients with AM treated at our hospital were retrospectively reviewed, of whom 29 treated by RFA (RFA group) and 31 by Adx (Adx group). The technical success, local tumor progression (LTP) and overall survival (OS) after the treatment were evaluated and compared.

RESULTS

In RFA group, the first technical success was 72.4% and the second technical success was 86.2%. In Adx group, all the AMs were successfully resected. After 24.5 ± 19.1 months follow-up period, a total of 8 patients (6 in RFA group and 2 in Adx group) were detected LTP. The 1-, 2- and 3- LTP rates after treatment were 17.1%, 30.9% and 44.7% in RFA group, and 6.5%, 6.5% and 6.5% in Adx group, respectively (P = 0.028). However, for AM ≤ 5 cm, the LTP between the two groups were comparable (P = 0.068). The 1-, 2- and 3- OS rates after treatment for AM were 85.0%, 42.4% and 27.8% in RFA group, and 93.0%, 66.1% and 52.3% in Adx group, respectively (P = 0.057). RFA offered shorter treatment time (23.6 ± 16.9 vs. 155.6 ± 58.8 min, P < 0.001), shorter hospital stay (7.8 ± 3.9 vs. 15.0 ± 4.9 days, P < 0.001), and lower hospital cost ($3405.7 ± 1067.8 vs. $5248.0 ± 2261.3, P = 0.003) than Adx.

CONCLUSION

In comparison with Adx, percutaneous US-guided RFA, as an alternative treatment, is feasible and effective in controlling AM, especially in AM ≤ 5 cm in diameter.

Outcomes following minimally invasive imagine-guided percutaneous ablation of adrenal glands

Whilst surgery represents the gold standard for the treatment of adrenal primary malignant tumors, metastatic involvement of the adrenal glands is generally approached conservatively; however, surgery for local control has been controversial, and several reports have described the utility of surgical removal in terms of prolonged survival in selected patients. Different techniques, including radiofrequency ablation (RFA), microwave ablation (MWA), laser induced thermal therapy (LITT), cryoablation (CRA), and chemical ablation, are employed in percutaneous image-guided ablation for primary and metastatic malignancies of the adrenal glands, in case of patients with multiple comorbidities or who refuse surgery. Technical success, clinical success and safety were analysed and discussed in this systematic review. Tumor size was found a significant determinant for local disease control; histology of the primary malignancy and coexistence of tumor elsewhere were correlated with prognosis. These procedures resulted to be feasible and safe, with hypertensive crisis representing the most common complication. Although there is lack of evidence in the literature concerning outcomes compared with surgery, percutaneous ablation may represent a useful therapeutic option for controlling unresectable adrenal metastases, offering patients opportunities for improved survival.

"How We Do It" - A Practical Approach to Percutaneous Adrenal Ablation Techniques

Incidental adrenal masses are common and are found in 4% of the CT scans.¹ While clinical history, laboratory results, and imaging characteristics are typically sufficient for diagnosis of an adrenal lesion, a biopsy is sometimes warranted. In some cases, adrenal mass ablation is subsequently indicated. This article serves as a brief but comprehensive review of preprocedural work-up and planning before an adrenal mass ablation, as well as a discussion on ablation techniques, associated challenges and solutions, and management of expected and unexpected outcomes.

Novel Dose Escalation Approaches for Stereotactic Body Radiotherapy to Adrenal Oligometastases: A Single-Institution Experience

OBJECTIVES

The role of local disease control in the oligometastatic setting is evolving. Stereotactic body radiation therapy (SBRT) is a noninvasive treatment option for oligometastases; however, using ablative radiation doses for adrenal metastases raises concern given the proximity to radiosensitive organs. Novel treatment techniques may allow for selective dose escalation to improve local control (LC) while minimizing dose to nearby critical structures.

MATERIALS AND METHODS

We retrospectively reviewed patients with adrenal oligometastases treated with SBRT from 2013 to 2018. LC, disease-free survival, and overall survival were estimated using Kaplan-Meier methods. Predictors of outcomes were evaluated by log-rank and Cox proportional hazard analyses.

RESULTS

We identified 45 adrenal oligometastases in 41 patients treated with SBRT. The median age at treatment was 67 years (range, 40 to 80). The most common primary histologies were non-small cell lung cancer (51%), renal cell carcinoma (24%), and small cell lung cancer (10%). The median prescription dose was 50 Gy (range, 25 to 60 Gy), with 30 (67%) lesions receiving ≥50 Gy and 14 (31%) receiving 60 Gy. In total, 26 (58%) lesions received a simultaneous-integrated boost. Of the 42 treatment simulations, 26 (62%) were supine, 5 (12%) prone, and 11 (26%) in the left lateral decubitus position. At a median follow-up of 10.5 months, there were 3 local failures with a 12-month LC rate of 96%.

CONCLUSIONS

Adrenal SBRT for oligometastatic disease is a feasible, noninvasive option with excellent LC and minimal toxicity. Lesions in close proximity to radiosensitive organs may benefit from dynamic patient positioning and selective simultaneous-integrated boost techniques to allow for dose escalation, while also limiting toxicity risks.

Anesthesia for Percutaneous Radiofrequency Tumor Ablation (PRFA): A Review of Current Practice and Techniques

Percutaneous radiofrequency ablation (PRFA) of solid tumors is a minimally invasive procedure used to treat primary or metastatic cancer lesions via needle targeted thermal energy transfer. Some of the most common tumor lesions treated using PRFA include those within the liver, lungs and kidneys. Additionally, bone, thyroid, and breast lesions can also be treated. In most cases, this procedure is performed outside of the operating room in a specialized radiology suite. As a result, the clinician must adapt in many cases to the specific environmental issues attendant to providing anesthesia outside the operating room, including the lack of availability of an anesthesia machine in some cases, and frequently a lack of adequate scavenging and other specialized monitoring and equipment. At this time, routine practice and anesthetic prescriptions for PRFA can vary widely, ranging from patients receiving local anesthesia alone, to monitored anesthesia care, to regional anesthesia, to combined regional and general anesthesia. The choice of anesthetic technique will depend on tumor location and practitioner experience. This review aims to summarize the current state of the art in terms of anesthetic techniques for patients undergoing PRFA of solid tumors.

CT Texture Analysis and Machine Learning Improve Post-ablation Prognostication in Patients with Adrenal Metastases: A Proof of Concept

INTRODUCTION

To assess the performance of pre-ablation computed tomography texture features of adrenal metastases to predict post-treatment local progression and survival in patients who underwent ablation using machine learning as a prediction tool.

MATERIALS AND METHODS

This is a pilot retrospective study of patients with adrenal metastases undergoing ablation. Clinical variables were collected. Thirty-two texture features were extracted from manually segmented adrenal tumors. A univariate cox proportional hazard model was used for prediction of local progression and survival. A linear support vector machine (SVM) learning technique was applied to the texture features and clinical variables, with leave-one-out cross-validation. Receiver operating characteristic analysis and the area under the curve (AUC) were used to assess performance between using clinical variables only versus clinical variables and texture features.

RESULTS

Twenty-one patients (61% male, age 64.1 ± 10.3 years) were included. Mean time to local progression was 29.8 months. Five texture features exhibited association with progression (p < 0.05). The SVM model based on clinical variables alone resulted in an AUC of 0.52, whereas the SVM model that included texture features resulted in an AUC 0.93 (p = 0.01). Mean overall survival was 35 months. Fourteen texture features were associated with survival in the univariate model (p < 0.05). While the trained SVM model based on clinical variables resulted in an AUC of 0.68, the SVM model that included texture features resulted in an AUC of 0.93 (p = 0.024).

DISCUSSION

Pre-ablation texture analysis and machine learning improve local tumor progression and survival prediction in patients with adrenal metastases who undergo ablation.

Stereotactic body radiation therapy for adrenal gland metastases: Outcomes and toxicity

Purpose

This study aimed to report on our institutional experience in the use of stereotactic body radiation therapy (SBRT) for the treatment of adrenal gland metastases. Specifically, we examined the outcomes and toxicity from this treatment modality on adjacent organs at risk.

Methods and Materials

Data were retrieved from patients with adrenal metastases who were treated with SBRT between 2008 and 2017. Patients with primary adrenal malignancies were excluded. Toxicities were graded in accordance with the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.03. Time-to-event rates were calculated from the date of SBRT delivery.

Results

In total, 35 patients with adrenal metastases were identified. Four patients were treated for bilateral disease. The median dose was 40 Gy (range, 20-54 Gy) in 5 fractions (range, 1-6 fractions). The median follow-up time was 37 months (range, 14-451 months) from disease diagnosis and 7 months (range, 1-54 months) from the SBRT start date. With death treated as a competing risk event, the cumulative incidence of local failure was 7.6% at 1 year after SBRT and 19.2% at 3 years. The median overall survival (OS) time was 19 months (95% confidence interval, 8-54 months) and tumor size correlated with survival (P = .0006). Patients with metastases <2.9 cm had a median OS of 54 months compared with 11 months for those with adrenal metastases ≥2.9 cm (P = .01). Incidence of grade 2 toxicity was 17% with no case of grade ≥3 toxicity. SBRT did not impact renal function with a mean estimated decline in glomerular filtration rate of only 2.6 ± 8 mL/min/1.73 m² compared with baseline. Combined kidneys V5 and combined renal cortex V17.5 did not correlate with a change in estimated glomerular filtration rate (P = .7 and P = .9, respectively).

Conclusions

SBRT offers excellent local control for the treatment of adrenal gland metastases with very low toxicity rates and no significant short-term impact on renal function.

Thermal Ablation in the Management of Adrenal Metastasis Originating from Non-small Cell Lung Cancer: A 5-year Single-center Experience

Background:

Treatment of adrenal metastasis from lung carcinoma may prolong survival in the selected patients. However, not all patients can undergo surgery; thus, minimally invasive ablation procedures such as radiofrequency ablation (RFA) and microwave ablation (MWA) have gained acceptance as alternative treatment methods. This study summarized a 5-year single-center experience regarding the evaluation of safety and efficacy of computed tomography (CT)-guided thermal ablation in the management of adrenal metastasis originating from non-small cell lung cancer (NSCLC).

Methods:

The data of NSCLC patients ablated for adrenal metastasis at the Department of Diagnostic Imaging and Interventional Radiology, General Hospital Sotiria, were retrospectively analyzed. Patients were divided into two groups: RFA group and MWA group according to the therapeutic approaches. Preprocedural blood tests included measurement of international normalized ratio, partial thromboplastin time, and platelet enumeration. A dual-phase contrast-enhanced spiral CT was performed immediately after the procedure to assess the immediate response after ablation and to screen for related complications. Follow-up was performed with CT or magnetic resonance imaging at 1, 3, 6 months and 1 year after ablation and every 6 months thereafter.

Results:

A total of 99 ablation sessions in 71 patients with adrenal metastasis originating from NSCLC were included in the final analysis. Self-limited, postablation syndrome occurred in 16/99 (16.1%) of ablation sessions. All procedures were technically successful. Immediate postablation imaging showed no contrast enhancement of the ablated tumor in all patients. Follow-up imaging at 3 months revealed local tumor progression in 8 (22.8%) patients of the RFA group and 7 (19.4%) patients of MWA group, all of them underwent a second session successfully. The 1-year assessment revealed local recurrence of the ablated tumor in six patients (17.1%) of RFA group and seven patients (19.4%) of MWA group. Among these 71 patients, those with tumor size >3.5 cm had a higher local recurrence rate (65.2%, 15/23) than those with tumors ≤3.5 cm (16.7%, 8/48; P = 0.012). There was no significant difference in the median survival time between RFA (14.0 months) and MWA (14.6 months) groups (P > 0.05).

Conclusions:

RFA and MWA showed comparable efficacy and safety in adrenal metastasis treatment.

Interventional radiology of the adrenal glands: current status

As more and more adrenal neoplasms are found incidentally or symptomatically, the need for interventional procedures has being increasing. In recent years these procedures registered continued steady expansion. Interventional radiology of the adrenal glands comprises angiographic and percutaneous procedures. They may be applied both in benign and in malignant pathologies. The present review reports the current status of indications, techniques results and complications of the image-guided procedures.

Effectiveness and safety of CT-guided percutaneous radiofrequency ablation of adrenal metastases

OBJECTIVE

The imaging-guided percutaneous radiofrequency (RF) ablation of adrenal metastases is a relatively new treatment procedure, compared to the more widespread application of the technique for the treatment of liver and renal cancers. The present study aims to evaluate the safety and efficacy of the CT-guided percutaneous RF ablation of adrenal metastases in a cohort of patients.

METHODS

33 patients with 38 adrenal metastases who received percutaneous CT-guided RF ablation between 2012 to 2015 were retrospectively reviewed. The average diameter of the treated adrenal metastases was 3.0 ± 1.6 cm. The treatment outcomes, including presence of residual tumours, technical success rate, recurrence rate, and complications, were evaluated. Patients were followed up for every 3 months to monitor the progression of the disease.

RESULTS

Postoperative CT images showed the lack of tumour enhancement in 30 tumours (30/38 tumours, technical success rate = 78.9%), and residual disease was found in 7 tumours (7/37 tumours, 18.9%). The rate of residual disease was significantly lower in the group with tumour size <3 cm than the group with tumour size ≥3 cm (p = 0.025). The severe complication rate was 4.3%, and the mild complication rate was 48%, with intraoperative hypertensive crisis as the most frequently observed complication (27.3%). The follow-up data showed that 76.3% of patients had recurrence-free survival in 27.4 months.

CONCLUSION

The current study demonstrated that radiofrequency ablation is a relatively safe and effective treatment for controlling adrenal metastases, especially for patients with tumour size <3 cm. Advances in knowledge: Surgical resection of the adrenal metastases was advocated as one of the treatment options for patients. The present study showed that radiofrequency ablation is a relatively safe and effective treatment for controlling adrenal metastases.

Adrenal obliteration by balloon-occluded retrograde venous ethanol injection in a swine model

PURPOSE

To evaluate the effects of adrenal obliteration by balloon-occluded retrograde venous ethanol injection.

MATERIAL AND METHODS

We inserted a micro-balloon catheter into the left adrenal vein of six pigs and retrogradely injected absolute ethanol (0.06 ml/kg) under balloon occlusion. Two pigs were sacrificed on day 3, 7, and 14 after the procedure, respectively. We evaluated adrenal cortical and medullary hormones of the left renal vein, venograms, magnetic resonance imaging scans obtained before and after the procedure, autopsy and microscopic findings, and the weight of the bilateral adrenal glands.

RESULTS

The hormone levels were extremely high on day 3 after the procedure. Post-procedure, partially-enhanced parenchyma and shaggy veins were observed. On the post-mortem examination, the left adrenal glands showed hemorrhage and adhesion on the third and seventh day and fatty proliferation 14 days after the procedure. Microscopic examination revealed hemorrhagic necrosis on day 3, inflammatory cell infiltration on day 7, and partial fibrosis 14 days after the procedure. The weight of the left adrenal gland on day 14 was lower than that of the right gland.

CONCLUSIONS

This procedure elicited partial adrenal infarction with a high catecholamine concentration in the left renal vein.

Management of Adrenal Masses

An adrenal mass can be either symptomatic or asymptomatic in the form of adrenal incidentalomas (AIs) in up to 8 % in autopsy and 4 % in imaging series. Once a diagnosis of adrenal mass is made, we need to differentiate whether it is functioning or nonfunctioning, benign, or malignant. In this article, we provide a literature review of the diagnostic workup including biochemical evaluation and imaging characteristics of the different pathologies. We also discuss the surgical strategies with laparoscopy as the mainstay with partial adrenalectomy in select cases and adrenalectomy in large masses. Follow-up protocol of AIs and adrenocortical carcinoma is also discussed.

Long-term Results after CT-Guided Percutaneous Ethanol Ablation for the Treatment of Hyperfunctioning Adrenal Disorders

OBJECTIVES:

To evaluate the safety and long-term efficacy of computed tomography-guided percutaneous ethanol ablation for benign primary and secondary hyperfunctioning adrenal disorders.

METHOD:

We retrospectively evaluated the long-term results of nine patients treated with computed tomography-guided percutaneous ethanol ablation: eight subjects who presented with primary adrenal disorders, such as pheochromocytoma, primary macronodular adrenal hyperplasia and aldosterone-producing adenoma, and one subject with Cushing disease refractory to conventional treatment. Eleven sessions were performed for the nine patients. The patient data were reviewed for the clinical outcome and procedure-related complications over ten years.

RESULTS:

Patients with aldosterone-producing adenoma had clinical improvement: symptoms recurred in one case 96 months after ethanol ablation, and the other patient was still in remission 110 months later. All patients with pheochromocytoma had clinical improvement but were eventually submitted to surgery for complete remission. No significant clinical improvement was seen in patients with hypercortisolism due to primary macronodular adrenal hyperplasia or Cushing disease. Major complications were seen in five of the eleven procedures and included cardiovascular instability and myocardial infarction. Minor complications attributed to sedation were seen in two patients.

CONCLUSION:

Computed tomography-guided ethanol ablation does not appear to be suitable for the long-term treatment of hyperfunctioning adrenal disorders and is not without risks.

Radiofrequency ablation compared with laparoscopic adrenalectomy for aldosterone-producing adenoma

BACKGROUND

Radiofrequency ablation (RFA) is an emerging treatment for primary aldosteronism owing to aldosterone-producing adenoma. Whether RFA could be an alternative treatment to laparoscopic adrenalectomy is unknown.

METHODS

This was a retrospective comparative study in patients with aldosterone-producing adenoma undergoing either laparoscopic adrenalectomy or CT-guided percutaneous RFA between 2004 and 2012. Short-term outcomes and long-term resolution rates of primary aldosteronism (normalized aldosterone to renin ratio), hypokalaemia and hypertension (BP lower than 140/90 mmHg without antihypertensive medical therapy) were evaluated.

RESULTS

Some 63 patients were included, 27 in the laparoscopic adrenalectomy group and 36 in the RFA group. RFA was associated with shorter duration of operation (median 12 versus 124 min; P < 0·001), shorter hospital stay (2 versus 4 days; P < 0·001), lower analgesic requirements (13 of 36 versus 23 of 27 patients; P < 0·001) and earlier resumption of work (median 4 versus 14 days; P = 0·006). Morbidity rates were similar in the two groups. With median follow-up of 5·7 (range 1·9-10·6) years, resolution of primary aldosteronism was seen in 33 of 36 patients treated with RFA and all 27 patients who had laparoscopic adrenalectomy (P = 0·180). Hypertension was resolved less frequently after treatment with RFA compared with laparoscopic adrenalectomy (13 of 36 versus 19 of 27 patients; P = 0·007). Hypokalaemia was resolved in all patients.

CONCLUSION

For patients with aldosterone-producing adenoma the efficacy of resolution of primary aldosteronism and hypertension was inferior after treatment with RFA compared with laparoscopic adrenalectomy.

Clinical Outcomes following Percutaneous Radiofrequency Ablation of Unilateral Aldosterone-Producing Adenoma: Comparison with Adrenalectomy

PURPOSE

To compare adrenal radiofrequency (RF) ablation with adrenalectomy in treating unilateral aldosterone-producing adenoma (APA).

MATERIALS AND METHODS

Between April 2008 and September 2013, 44 patients with adrenal venous sampling-confirmed (lateralization index ≥ 4) unilateral APA underwent adrenal RF ablation (12/44 [27%]) or adrenalectomy (32/44 [73%]). Outcomes of adrenal RF ablation (patient age, 51 y ± 11; 4/12 men) were compared with adrenalectomy (patient age, 50 y ± 11; 19/32 men). Blood pressure (145/94 mm Hg ± 19/13 vs 144/89 mm Hg ± 10/8, P = .92), number of antihypertensives (3.0 ± 1.3 vs 2.7 ± 0.89, P = .38), and serum potassium (3.2 mEq/L ± 0.6 vs 3.5 mEq/L ± 0.6, P = .65) of patients were similar before treatment.

RESULTS

RF ablation and adrenalectomy resulted in normokalemia (RF ablation, 4.2 mEq/L ± 0.1, P = .0004; adrenalectomy, 4.3 mEq/L ± 0.6, P < .0001) and normotension (RF ablation, 129/81 mm Hg ± 11/11, P = .02/P = .001; adrenalectomy, 128/85 mm Hg ± 13/12, P < .0001/P = .07) in all patients. Proportions of RF ablation and adrenalectomy patients cured of hypertension (2/12 [17%] vs 12/32 [38%], P = .28) or requiring fewer antihypertensives (7/12 [58%] vs 13/32 [40%], P = .29) were similar. RF ablation patients had a shorter length of stay (0.6 d ± 0.8 [range, 0-2 d] vs 1.7 d ± 1.4 [range, 0-7 d]; P = .01) and less intraoperative blood loss (1.2 mL ± 3 vs 40 mL ±85; P = .01). Procedural complications occurred in 5/32 (15%) adrenalectomy patients (2 major, 3 minor) and in 0/12 RF ablation patients.

CONCLUSIONS

RF ablation to treat APA can achieve similar clinical outcomes as adrenalectomy and results in shorter hospital stays. Larger, prospective trials are needed to validate these results.

Comparison of radiofrequency ablation versus laparoscopic adrenalectomy for benign aldosterone-producing adenoma

PURPOSE

To retrospectively compare the safety and efficacy of radiofrequency ablation (RFA) with laparoscopic adrenalectomy (LA) in treating aldosterone-producing adenoma (APA) of the adrenal gland.

MATERIALS AND METHODS

From September 2009 to September 2013, seven patients, diagnosed with unilateral adrenal APA and underwent computed tomography (CT)-guided percutaneous RFA, were recruited in this retrospective study. Eighteen unilateral adrenal APA with the same tumor size (<25 mm) who underwent LA during the same interval were enrolled as control group. Treatment success was defined as complete tumor ablation on follow-up CT scan and normalization of serum aldosterone-to-renin ratio. We also compared "normalization ability" between RFA group and LA group. Normalization ability was defined as reduction in blood pressure, decrease in number of antihypertensive medicine use, reduction in serum aldosterone, and increase in serum potassium level.

RESULTS

There was no statistically significant demographic difference in both groups. The mean tumor size was 18 (8-25) mm in RFA and 19 (11-25) mm in LA groups, respectively. There was only one intra-procedure hypertensive crisis in the RFA group. No other complications needed further management in both groups. During an interval of 3-6 months of follow-up, the treatment success rate reached 100 % in the RFA group versus 94.4 % in the LA group. Normalization ability was statistically equivalent in the RFA and the LA group. Comparing with LA group, RFA group demonstrated with less post-operative pain (visual analog scale, 2.0 ± 1.16 vs. 4.22 ± 1.44, p < 0.001) and shorter operative time (105 ± 34 vs. 194 ± 58 min, p < 0.001).

CONCLUSIONS

CT-guided percutaneous RFA is effective, safe and is a justifiable alternative for patients who are reluctant or unfit for laparoscopic surgery for the treatment of APA.

Percutaneous microwave ablation of adrenal tumours under ultrasound guidance in 33 patients with 35 tumours: A single-centre experience

PURPOSE

The aim of this study was to investigate the efficacy and safety of percutaneous microwave ablation (MWA) of adrenal tumours under ultrasound (US) guidance.

MATERIALS AND METHODS

A total of 33 consecutive patients with 35 tumours were enrolled. The term 'technical success' is used to indicate whether the tumour was treated according to protocol and was covered completely by the ablation zone. Technical success, local tumour progression (LTP) and complications were recorded. For seven patients with eight biochemically active tumours, biochemical markers were recorded prior to and after the ablation procedure.

RESULTS

In this study, technical success was achieved in all cases. Follow-up imaging was performed on 31 patients with 33 tumours (excluding two patients who were lost to follow-up). LTP occurred for five tumours (15.2%) at a mean of 24 months of follow-up (range 3-82 months). In the subgroup analysis of tumour size and LTP, a significant difference was noted between tumours with a diameter ≤5 cm compared with those >5 cm (p < 0.01). For seven cases of metabolically active adrenal tumours, technical success was confirmed in all patients, and LTP occurred in one case of recurrent pheochromocytoma. All patients demonstrated the normalisation of abnormal biochemical markers after ablation. No major complications were observed.

CONCLUSION

Percutaneous MWA under US guidance is effective in terms of good local control of adrenal tumours with a diameter of less than or equal to 5 cm and is capable of treating biochemically active tumours harbouring clinical syndromes.

Catecholamine Surge during Image-Guided Ablation of Adrenal Gland Metastases: Predictors, Consequences, and Recommendations for Management

PURPOSE

To identify retrospectively predictors of catecholamine surge during image-guided ablation of metastases to the adrenal gland.

MATERIALS AND METHODS

Between 2001 and 2014, 57 patients (39 men, 18 women; mean age, 65 y ± 10; age range, 41-81 y) at two academic medical centers underwent ablation of 64 metastatic adrenal tumors from renal cell carcinoma (n = 27), lung cancer (n = 23), melanoma (n = 4), colorectal cancer (n = 3), and other tumors (n = 7). Tumors measured 0.7-11.3 cm (mean, 4 cm ± 2.5). Modalities included cryoablation (n = 38), radiofrequency (RF) ablation (n = 20), RF ablation with injection of dehydrated ethanol (n = 10), and microwave ablation (n = 4). Fisher exact test, univariate, and multivariate logistical regression analysis was used to evaluate factors predicting hypertensive crisis (HC).

RESULTS

HC occurred in 31 sessions (43%). Ventricular tachycardia (n = 1), atrial fibrillation (n = 2), and troponin leak (n = 4) developed during HC episodes. HC was significantly associated with maximum tumor diameter ≤ 4.5 cm (odds ratio [OR], 26.36; 95% confidence interval [CI], 5.26-131.99; P < .0001) and visualization of normal adrenal tissue on CT or MR imaging before the procedure (OR, 8.38; 95% CI, 2.67-25.33; P < .0001). No HC occurred during ablation of metastases in previously irradiated or ablated adrenal glands.

CONCLUSIONS

Patients at high risk of catecholamine surge during ablation of non-hormonally active adrenal metastases can be identified by the presence of normal adrenal tissue and tumor diameter ≤ 4.5 cm on pre-procedure CT or MR imaging.

Adrenal Imaging and Intervention

The adrenal glands are a common site for primary benign and malignant tumors and metastatic disease. Computed tomography (CT), MR imaging, and fluorine-18 fluorodeoxyglucose PET combined with CT are the most common imaging modalities used to assess the adrenal glands. There are established morphologic criteria for both CT and MR imaging that can be used to assess whether an adrenal mass is benign or malignant, and whether follow-up, biopsy, or resection should be performed. In the setting of a known primary malignancy, CT, MR imaging, and PET can help differentiate most benign masses from metastasis.

Microwave ablation: state-of-the-art review

This paper reviews state-of-the-art microwave ablation (MWA) of tumors. MWA is a novel method for treating inoperable tumors, ie, tumors that cannot be treated surgically. However, patients generally choose removal of the tumor by conventional techniques. A literature review of MWA for breast, liver, lung, and kidney tumors is reported here, with tabulation of our findings according to the type of technique used, with a detailed description of the time, type of microwave generator used, and number of patients treated with MWA. In some cases, the subjects were not human patients, but pig or bovine liver specimens. MWA is a technique that has proved to be promising and likely to be used increasingly in the ablation of cancerous tumors. However, MWA needs to be used more widely to establish itself as a common tool in the treatment of inoperable tumors.

Unresectable Adrenal Metastases: Clinical Outcomes of Radiofrequency Ablation

PURPOSE

To retrospectively evaluate the clinical outcomes of radiofrequency (RF) ablation for the treatment of unresectable adrenal metastasis.

MATERIALS AND METHODS

The institutional review board approved this retrospective study, and informed consent to perform adrenal RF ablation was obtained from all patients. From February 2005 through May 2014, 35 patients (25 men and 10 women; mean age, 64.7 years ± 9.6; age range, 39-82 years) underwent RF ablation to treat 41 metastatic adrenal tumors from lung cancer (n = 15), renal cell carcinoma (n = 9), colorectal cancer (n = 5), hepatocellular carcinoma (n = 4), and other tumors (n = 2). Tumors ranged in size from 1.2 to 8.2 cm (mean, 3.3 cm ± 1.6). The diagnosis was established mainly on the basis of radiologic findings. Adrenal arterial embolization was combined with RF ablation in 12 of the 35 patients (34%). Technical success, safety, local tumor progression, and survival were evaluated. The Kaplan-Meier method and Cox proportional hazard model were used to evaluate prognostic factors.

RESULTS

There were 48 completed sessions with planned procedures and treatment protocols with no mortality and a major complication rate of 8.3% (four of 48 sessions). Tumor enhancement disappeared after initial adrenal RF ablation in 33 of the 35 patients (94%). Local tumor progression developed in eight of the 35 patients (23%); two patients received repeated RF ablation, resulting in adrenal tumor control in 27 of the 35 patients (77%) at the last follow-up (mean, 30.1 months ± 27.5; range 1.2-96.8 months). The 1-, 3-, and 5-year overall survival rates were 75% (95% confidence interval [CI], 61%, 90%), 34% (95% CI: 17%, 52%), and 30% (95% CI: 13%, 48%), respectively, with a median survival time of 26.0 months. Existence of extra-adrenal tumors (P = .005) and age of 65 years or older (P = .04) were significant indicators of a poor prognosis.

CONCLUSION

Adrenal RF ablation is a feasible and useful method for controlling adrenal metastases and offers patients opportunities for improved survival.

Metabolic and anatomic characteristics of benign and malignant adrenal masses on positron emission tomography/computed tomography: a review of literature

PET/CT with (18)F-fluorodeoxyglucose (FDG) or using different radiocompounds has proven accuracy for detection of adrenal metastases in patients undergoing cancer staging. It can assist the diagnostic work-up in oncology patients by identifying distant metastases to the adrenal(s) and defining oligometastatic disease that may benefit from targeted intervention. In patients with incidentally discovered adrenal nodules, so-called adrenal "incidentaloma" FDG PET/CT is emerging as a useful test to distinguish benign from malignant etiology. Current published evidence suggests a role for FDG PET/CT in assessing the malignant potential of an adrenal lesion that has been 'indeterminately' categorized with unenhanced CT, adrenal protocol contrast-enhanced CT, or chemical-shift MRI. FDG PET/CT could be used to stratify patients with higher risk of malignancy for surgical intervention, while recommending surveillance for adrenal masses with low malignant potential. There are caveats for interpretation of the metabolic activity of an adrenal nodule on PET/CT that may lead to false-positive and false-negative interpretation. Adrenal lesions represent a wide spectrum of etiologies, and the typical appearances on PET/CT are still being described, therefore our goal was to summarize the current diagnostic strategies for evaluation of adrenal lesions and present metabolic and anatomic appearances of common and uncommon adrenal lesions. In spite of the emerging role of PET/CT to differentiate benign from malignant adrenal mass, especially in difficult cases, it should be emphasized that PET/CT is not needed for most patients and that many diagnostic problems can be resolved by CT and/or MR imaging.

Single-Session CT-Guided Percutaneous Microwave Ablation of Bilateral Adrenal Gland Hyperplasia Due to Ectopic ACTH Syndrome

Bilateral adrenalectomy is currently the only available treatment for adrenocorticotropic hormone (ACTH)-dependent Cushing's syndrome (ectopic ACTH syndrome) that is refractory to pharmacologic therapy. We describe two patients with refractory ectopic ACTH syndrome who were treated with CT-guided percutaneous microwave ablation of both hyperplastic adrenal glands in a single session: O ne was not a surgical candidate, and the other had undergone unsuccessful surgery. Following the procedure, both patients achieved substantial decreases in serum cortisol, symptomatic improvement, and decreased anti-hypertensive medication requirements.

Image-guided ablation of adrenal lesions

Although laparoscopic adrenalectomy has remained the standard of care for the treatment for adrenal tumors, percutaneous image-guided ablation therapy, such as chemical ablation, radiofrequency ablation, cryoablation, and microwave ablation, has been shown to be clinically useful in many nonsurgical candidates. Ablation therapy has been used to treat both functioning adenomas and malignant tumors, including primary adrenal carcinoma and metastasis. For patients with functioning adenomas, biochemical and symptomatic improvement is achieved in 96 to 100% after ablation; for patients with malignant adrenal neoplasms, however, the survival benefit from ablation therapy remains unclear, though good initial results have been reported. This article outlines the current role of ablation therapy for adrenal lesions, as well as identifying some of the technical considerations for this procedure.

A single-institution experience in image-guided thermal ablation of adrenal gland metastases

PURPOSE

To assess safety, technical success, local control, and survival associated with percutaneous image-guided adrenal ablation.

MATERIALS AND METHODS

Adult patients with adrenal metastases who underwent percutaneous image-guided adrenal ablation during the years 2003-2012 were identified. There were 32 patients with 37 adrenal tumors identified. Technical success, safety, local control, and survival were analyzed according to standard criteria.

RESULTS

In 32 patients (25 men and 7 women; mean age, 66 y; age range, 44-88 y) with 37 adrenal tumors, 35 ablation procedures were performed. One patient with an 8.2-cm tumor underwent planned cryoablation debulking fully anticipating untreated margins owing to close proximity of the pancreas (ie, the intent was to diminish tumor burden rather than a curative intervention). Of the 36 patients treated with curative intent, technical success was achieved in 35 (97%) tumors. Follow-up imaging was performed on 34 of 37 tumors (excluding patients with intentional debulking [n = 1], technical failure [n = 1], and absence of follow-up [n = 1]). Local recurrence developed in 3 (8.8%) of 34 tumors. Local tumor control was achieved in 31 lesions at a mean of 22.7 months of follow-up. Recurrence-free survival and overall survival at 36 months were 88% and 52%, respectively, with a median survival of 34.5 months. A Common Terminology Criteria for Adverse Events version 4 grade 3 or 4 complication was observed in three (8.6%) ablation procedures.

CONCLUSIONS

Image-guided ablation is safe and effective for local control of metastatic adrenal tumors and provides a minimally invasive alternative to surgical resection in appropriately selected patients.

[Microwave tumor ablation. New devices, new applications?]

CLINICAL ISSUE

The majority of patients with hepatic malignancies are not amenable to surgical resection. In some of these cases minimally invasive ablative therapies are a treatment option.

STANDARD TREATMENT

Besides radiofrequency ablation, the most common ablative therapies are cryoablation, laser ablation and microwave ablation.

TREATMENT INNOVATIONS

The classic fields of application of microwave ablation are the treatment of malignancies of the liver, kidneys and lungs. Furthermore, cases of treatment of bone tumors and tumors of the adrenal gland have been reported as well as treatment of secondary hypersplenism.

PERFORMANCE

The manufacturers of microwave systems pursue different strategies to reach an optimal ablation zone, such as water or gas cooling of the antenna, the simultaneous use of different antennas or an automatic modulation of the microwave energy and frequency.

ACHIEVEMENTS

In contrast to other tumor ablation methods microwave ablation causes a direct heating of a tissue volume, thus this method is less vulnerable to the cooling effect of vessels in the ablation zone. Moreover the electric conductivity of the treated tissue does not influence microwave radiation so that microwave ablation has advantages for the treatment of high-resistance organs, such as the lungs or bone. Some publications have shown that microwave ablation causes larger ablation zones in less time in comparison to radiofrequency ablation.

PRACTICAL RECOMMENDATIONS

Classic indications for microwave ablation are the treatment of malignancies of the liver, lungs and kidneys. Initial technical problems have been solved, so that an increasing significance of the microwave ablation among the ablative therapies is to be expected.