Radiofrequency ablation of adrenal tumors and adrenocortical carcinoma metastases

Abstract

Background: The current study was performed to analyze the feasibility, safety, imaging appearance, and short-term efficacy of image-guided percutaneous radiofrequency ablation (RFA) of primary and metastatic adrenal neoplasms including adrenocortical carcinoma.

Methods: The procedure was performed using 36 treatment spheres on 15 adrenocortical carcinoma primary or metastatic tumors in eight patients over 27 months. Tumors ranged from 15 to 90 mm in greatest dimension with a mean of 43 mm. All patients had unresectable tumors or were poor candidates for surgery. Mean follow-up was 10.3 months.

Results: All patients were discharged or were free of procedure-related medical care 6-48 hours after the procedures without major complications. All treatments resulted in presumptive coagulation necrosis by imaging criteria, which manifested as loss of previous contrast enhancement in ablated tissue. Eight of 15 (53%) posttreatment thermal lesions lost enhancement and stopped growing on latest follow-up computed tomographic scan. Three of 15 (20%) demonstrated interval growth and four did not change in size. Of these four lesions, two showed contrast enhancement. For smaller tumors with a mean greatest dimension less than or equal to 5 cm, 8 of 12 (67%) tumors were completely ablated, as defined by decreasing size and complete loss of contrast enhancement. Three of 15 (20 %) tumors and related thermal lesions were found to have disappeared nearly completely on imaging.

Conclusions: Percutaneous, image-guided RFA is a safe and well tolerated procedure for the treatment of unresectable primary or metastatic adrenocortical carcinoma. The procedure is effective for the short-term local control of small adrenal tumors, and is most effective for tumors less than 5 cm. The survival rate for patients with adrenocortical carcinoma improves when radical excision is performed in selected patients. Aggressive local disease control may potentially influence survival as well. However, further study is required to evaluate survival impact, document long-term efficacy, and to determine if RFA can obviate repeated surgical intervention in specific clinical scenarios.

FIGURE 1

(A) T2-weighted magnetic resonance image shows bilobed tumor (arrow) in the adrenal bed adjacent to the spleen before radiofrequency ablation (RFA) was performed. (B) Enhanced computed tomograpy scan 20 months after RFA demonstrates near-complete involution of treated tumor with shrinking, unenhancing residual thermal lesion (arrow), presumably scar tissue.

FIGURE 2

(A) Enhanced T1-weighted magnetic resonance image before radiofrequency ablation (RFA) shows the enhancing rim of a recurrent adrenocortical carcinoma (ACC) postsurgery (arrow). The ACC tumor is located in the suprarenal bed, between the aorta and kidney. (B) Enhanced computed tomography (CT) scan immediately after RFA shows devascularized tumor with loss of enhancement (arrow). (C) Enhanced CT scan 14 months after RFA shows interval shrinkage of thermal lesion or tumor with a small residual (arrow). (D) Three-dimensional shaded surface display from contrast-enhanced CT immediately after RFA. The planes are cut away in the treated region to display the renal artery, renal vein, and the intervening treated thermal lesion between these two vessels. This demonstrates the predictability of RFA near vessels.

FIGURE 3

(A) Contrast-enhanced computed tomography (CT) scan shows radiofrequency ablation (RFA) probe tip (arrow) within enhancing renal hilum adrenocortical carcinoma drop metastasis. (B) Enhanced CT scan immediately after RFA shows a patent renal artery and subtle residual enhancing tissue at the lateral margin of the tumor (arrow). (C) Contrast-enhanced CT 6 weeks after RFA shows regrowth of incompletely treated tumor in a region with previous suspicious enhancement (arrow).

FIGURE 4

Lesion volumes over time.