1. Microwave Ablation of Bilateral Adrenal Metastases
Vincenzo Wong, MD
Louis Hinshaw, MD
University of Wisconsin Madison

2. History
65 year old male with history of right nephrectomy for renal cell cancer of unknown stage presents 2 years later with new bilateral adrenal lesions

3. Axial (A) and coronal (B) non-contrast abdominal CT
demonstrate bilateral adrenal nodules (arrows). The right kidney is surgically absent.
Axial PET/CT images (C & D) show associated mildly increased FDG avidity (arrows) [max SUV of 4.7].

4. Add coronal or sag CT image
Percutaneous CT guided core biopsy of the left adrenal lesion confirmed metastatic disease. Patient was given the option of bilateral metastatectomy or thermal ablation. Patient opted for ablation.
Ablation planning ultrasound demonstrates a hypoechoic circumscribed left adrenal mass felt to be better accessible utilizing CT guidance.

5. Question
What unique risks would you need to discuss with the patient that could occur during the procedure and long-term after the procedure?

6. Question
What unique risks would you need to discuss with the patient that could occur during the procedure and long-term after the procedure?
Answer
Hypertensive crisis can occur during the procedure, and potentially lead to hemodynamic collapse, organ failure, and death.
After the procedure, adrenal insufficiency may occur depending on how much adrenal tissue is ablated.

7. Probe 1 Placement
Probe 2 Placement
During Ablation
Post Ablation
A trace pneumothorax (arrow) was noted during the procedure not requiring a chest tube.
Patient was placed in a prone position. Two 20-cm Certus 140 microwave ablation probes were placed within the left adrenal mass under fluoroscopic CT guidance via a transpleural approach.
A 5 minute total ablation was performed. Both probes were run at 95 watts for 1 minute and subsequently at 70 watts for 4 minutes.
Pre Ablation
Post Ablation
Post ablation images show decreased size of the lesion secondary to tissue contraction

8. Questions
For microwave ablation, at what point during the procedure would you most likely expect hypertensive crisis to occur?
During probe placement?
During probe heating?
During probe cooling?
After probe removal?

9. Questions
For microwave ablation, at what point during the procedure would you most likely expect hypertensive crisis to occur?
During probe placement?
During probe heating?
During probe cooling?
After probe removal?
Hypertensive crisis is most likely to occur during cell rupture (causing release of catecholamines).
Most likely to occur during:
Heating for microwave and RF ablation
Thawing for cryoablation

10. A single Certus 140 probe was placed into the right adrenal lesion.
Pre Ablation
Probe Placement
During Ablation
Patient returned two weeks after treatment of the left-sided lesion for ablation of the right adrenal mass (arrow).
Scout CT image shows the patient in an ipsilateral decubitus position. The treated left adrenal mass (arrow) is redemonstrated.
A single Certus 140 probe was placed into the right adrenal lesion.
A 5 minute microwave ablation cycle was performed.
Post ablation images did not show any immediate complication.
Post Ablation

11. Question
What is the likelihood of long-term adrenal insufficiency in this patient?

12. Question
What is the likelihood of long-term adrenal insufficiency in this patient?
Answer
Likely… as both adrenal glands will have been ablated

13. Question
How much adrenal tissue would have to be destroyed before expecting adrenal insufficiency?
a) 30% b) 50% c) 70% d) 90%

14. Question
How much adrenal tissue would have to be destroyed before expecting adrenal insufficiency?
a) 30% b) 50% c) 70% d) 90%

15. A B C D E F
Patient presented approximately 1 year later (A, C, E) with three new lesions in the right adrenal gland (arrows). The treated lesion (arrow) is redemonstrated.
Three PR probes (B, D, F) were placed into the three nodules and a 5 minute ablation cycle at 65 watts was performed for each lesion.

16. Question
What is the likelihood of hypertensive crisis during this ablation session?

17. Question
What is the likelihood of hypertensive crisis during this ablation session?
Answer
Unlikely, as the adrenal gland has been previously ablated.

18. Question
The right adrenal gland may have been initially undertreated after the first ablation. If the original metastatic lesion was 3 cm, what diameter ablation zone would you aim to achieve?
a) 3 cm b) 4 cm c) 5 cm d) 6 cm

19. Question
The right adrenal gland appeared to be initially undertreated after the first ablation. If the original metastatic lesion was 3 cm, what diameter ablation zone would you aim to achieve?
a) 3 cm b) 4 cm c) 5 cm d) 6 cm
For metastatic disease, 1 cm ablation margins surrounding the lesion would be ideal.
1 cm
3 cm
5 cm
ablation
zone
1 cm

20. Restaging non-contrast CT images show stable appearance of the ablated adrenal lesions (arrows) without evidence of local or metastatic disease progression for 3 years.
Patient currently follows regularly with endocrinology for hormone replacement therapy for cortisol deficiency.

21. Background
Adrenal tumors comprise 1% of all neoplasms and are detected in 4-6% of patients undergoing imaging
Select patients with isolated metastatic disease to an adrenal gland reported to have a survival benefit from adrenalectomy
Ablation is an effective alternative to adrenalectomy for non-surgical candidates

22. Indications Potential indicated adrenal lesions include:
Non functioning and functioning adrenal tumors (cortisol producing adenomas, aldosteronoma)
Pheochromocytoma
Adrenocortical carcinoma
Metastases (most commonly lung, gastrointestinal tract, renal cell carcinoma, and melanoma)
Better results reported for lesions ≤ 5 cm

23. Pre-ablation Preparation
CT or MRI for ablation planning
For suspected functioning tumors
Serum or urine assays for cortisol, aldosterone, and catecholamines obtained prior to ablation (to evaluate for change after treatment)

24. Pre-ablation Preparation
Endocrinology consultation
Necessary in management of functioning adrenal tumors
Can assist with pre-treatment blockade with ⍺-blocker and β-blocker
Can monitor hormone levels and manage hormone replacement therapy after ablation

25. Question
What is a potentially harmful regimen for adrenergic blockade? a) β-blocker alone b) β-blocker + ⍺-blocker c) ⍺-blocker alone

26. Question
What is a potentially harmful regimen for adrenergic blockade? a) β-blocker alone b) β-blocker + ⍺-blocker c) ⍺-blocker alone
β-blockers are not administered until adequate ⍺ blockade has been established.
Unopposed ⍺-adrenergic receptor stimulation can precipitate a hypertensive crisis.

27. Pre-ablation Preparation
Anesthesiology Consultation and Sedation
Adrenal ablations generally performed under general anesthesia (to preempt hypertensive crisis and prepare for treatment should one occur)
Brief anesthesiology team about risk of hypertensive crisis to facilitate rapid administration of anti-hypertensive medications during procedure

28. Outcomes Functioning adenomas Malignant Tumors
Similar outcomes between ablation modalities
75-100% success rate after single ablation
100% success after second ablation
Malignant Tumors
Thermal ablation rates of residual or recurrent disease as low as 0 to 25%.
Chemical ablation appears less efficacious for controlling adrenal metastases

29. Complications Hypertensive Crisis (HC)
Due to release of catecholamines from manipulation of the normal non-tumorous adrenal gland
No difference in risk between ablation modalities
Generally occurs during heating for microwave and RF ablation, and thawing for cryoablation
Adrenergic blockade reported to decrease peak SBP in HC, although may not actually decrease risk for developing HC
Greater risk of HC
Lower risk of HC
tumor diameter < 4.5 cm
visualization of normal adrenal tissue
tumor diameter > 4.5 cm
gland replaced by tumor
previously ablated or irradiated gland

30. Complications Tips in mitigating hypertensive crisis
Pre-ablation adrenergic blockade
General anesthesia favored over moderate sedation
Invasive arterial blood pressure monitoring favored
During ablation, short acting anti-hypertensive agents favored over long-acting agents (risk of hypotension with long acting agents when catecholamine surge ends)
Warn anesthesiology team prior to tissue heating (microwave & RFA) and prior to thawing (cryoablation)
Brief anesthesiology team about need for rapid administration of anti-hypertensive medications

31. Complications Adrenal Insufficiency Pneumothorax Infection Bleeding
Exceedingly rare
Reported that >90% of adrenal tissue must be destroyed to compromise biochemical adrenal function
Managed by hormone replacement therapy
Pneumothorax
Infection
Bleeding
Pain

32. Conclusions
Ablation offers effective short-term local control of primary and metastatic adrenal neoplasms
Unique risks include hypertensive crisis (common) and adrenal insufficiency (rare)
Multidisciplinary approach with endocrinology and anesthesiology important to safe and successful ablation
Aim for 1 cm ablation margins for metastatic lesions

33. References
Uppot, R. N. and D. A. Gervais (2013). "Imaging-guided adrenal tumor ablation." AJR Am J Roentgenol 200(6):
Fintelmann, F. J., et al. (2015). "Catecholamine Surge during Image-Guided Ablation of Adrenal Gland Metastases: Predictors, Consequences, and Recommendations for Management." J Vasc Interv Radiol.
Yamakado, K. (2014). "Image-guided ablation of adrenal lesions." Semin Intervent Radiol 31(2):
Welch, B. T., et al. (2011). "Percutaneous image-guided adrenal cryoablation: procedural considerations and technical success." Radiology 258(1):