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

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

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].

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.

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

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.

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

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?

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

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

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

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

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

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

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.

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

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

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

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

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.

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

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

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)

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

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

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.

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

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

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

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

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

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

References Uppot, R. N. and D. A. Gervais (2013). "Imaging-guided adrenal tumor ablation." AJR Am J Roentgenol 200(6): 1226-1233 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): 149-156 Welch, B. T., et al. (2011). "Percutaneous image-guided adrenal cryoablation: procedural considerations and technical success." Radiology 258(1): 301-307