IMAGING

Adrenal neoplasms: CT-guided radiofrequency ablation - preliminary results
Mayo-Smith WW, Dupuy DE
Department of Radiology, Rhode Island Hospital, Brown Medical School, 593 Eddy St, Providence, RI 02903, USA
Radiology 2004; 231: 225-30.

• Purpose: To evaluate initial experience with radiofrequency (RF) ablation of adrenal neoplasms.
• Materials and Methods: Thirteen adrenal masses in 12 patients (bilateral metastases in one patient) were treated with computed tomography (CT)-guided percutaneous RF ablation. Eleven adrenal lesions were metastases (five from lung cancer, four from renal cell carcinoma, and two from melanoma); one lesion was a pheochromocytoma and one was an aldosteronoma. There were 10 men and two women (average age, 58 years; range, 40-77 years) in the study; average adrenal mass diameter was 3.9 cm (range, 1-8 cm). Average number of RF applications per adrenal mass was 2.7 (range, 1-5 applications); average time per application was 7.8 minutes (range, 4-13 minutes). An internally cooled single electrode was used in five sessions; an internally cooled cluster electrode was used in eight sessions.
• Results: Average follow-up was 11.2 months (range, 1-46 months). Eleven of 13 lesions were treated successfully with RF ablation after one session. Successful treatment was defined as lack of enhancement of the treated region on follow-up CT images and resolution of the biochemical abnormality in two patients. In two patients with large adrenal lesions (4 and 8 cm in diameter), enhancement of residual tissue was observed after one treatment session; this finding was indicative of residual tumor. One patient with thrombocytopenia that resulted from chemotherapy had a small hematoma, but no transfusion was required. No patient developed hypertension during the RF application. No patient with metastases had recurrent tumor at the treated site, and this lack of recurrence indicated effective local control; 11 patients had progression of metastatic disease at extraadrenal sites.
• Conclusion: Preliminary data suggest that CT-guided RF ablation is an effective technique for local control of adrenal neoplasms.
  
  
• Editorial Comment
  Radiofrequency (RF) thermal ablation is a minimally invasive technique for treating inoperable solid tumors. This technique has been mainly used to treat solid hepatic and renal tumors and bone lesions (particularly osteoid osteoma). More recently, lesions involving lung, breast and the adrenal gland have also been treated by this modality. Percutaneous, image-guided RF ablation is a safe and well-tolerated procedure but may eventually present variable degree of complication (bleeding, infection, tumor seeding, pneumothorax and non-targeted thermal damage).
  In this paper the authors present a successful treatment of 11 of thirteen adrenal tumors (average diameter of 3.9 cm) treated with a CT-guided RF ablation. Eleven out 13 adrenal masses were metastases, with 6 isolated to the adrenal gland and 5 associated with localized disease elsewhere that had been successfully controlled with chemotherapy, radiation therapy, and/or surgical resection. Criteria for successful treatment were based on the absence of residual CT-contrast enhancement of soft tissues component, no evidence of subsequent adrenal enlargement or recurrent biochemical activity. Six of the ten patients with an extraadrenal primary tumor subsequently died of metastatic disease to other sites. The average time of death was 8 months after the adrenal tumor treatment (range 3 - 16 months). The four remaining patients of the 10 with extraadrenal primary tumor had new metastatic disease in extraadrenal sites. This manuscript offers a promising technique with important results since no patient with metastases (11 patients) had recurrent tumor at the treated site, and this lack of recurrence indicated effective local control.
  Although consensus indication of percutaneous RF ablation in oncology is not strictly defined, one should keep in mind that the use of these techniques for local cancer treatment should consider that a local disease control may or may not improve patients’ survival. Long term follow-up and randomized prospective trials are required to evaluate survival impact, document long-term efficacy and to determine if percutaneous RF ablation can reduce the number or eliminate repeated surgical intervention in specific clinic scenarios.

Dr. Adilson Prando
Department of Radiology
Vera Cruz Hospital
Campinas, São Paulo, Brazil