Tumour characteristics and therapeutic results after percutaneous radiofrequency ablation of secondary lung neoplasms

Radiofrequency ablation of lung tumors: imaging features of the postablation zone

Radiofrequency ablation (RFA) is used to treat pulmonary malignancies. Although preliminary results are suggestive of a survival benefit, local progression rates are appreciable. Because a patient can undergo repeat treatment if recurrence is detected early, reliable post-RFA imaging follow-up is critical. The purpose of this article is to describe (a) an algorithm for post-RFA imaging surveillance; (b) the computed tomographic (CT) appearance, size, enhancement, and positron emission tomographic (PET) metabolic activity of the ablation zone; and (c) CT, PET, and dual-modality imaging with PET and CT (PET/CT) features suggestive of partial ablation or tumor recurrence and progression. CT is routinely used for post-RFA follow-up. PET and PET/CT have emerged as auxiliary follow-up techniques. CT with nodule densitometry may be used to supplement standard CT. Post-RFA follow-up was divided into three phases: early (immediately after to 1 week after RFA), intermediate (>1 week to 2 months), and late (>2 months). CT and PET imaging features suggestive of residual or recurrent disease include (a) increasing contrast material uptake in the ablation zone (>180 seconds on dynamic images), nodular enhancement measuring more than 10 mm, any central enhancement greater than 15 HU, and enhancement greater than baseline anytime after ablation; (b) growth of the RFA zone after 3 months (compared with baseline) and definitely after 6 months, peripheral nodular growth and change from ground-glass opacity to solid opacity, regional or distant lymph node enlargement, and new intrathoracic or extrathoracic disease; and (c) increased metabolic activity beyond 2 months, residual activity centrally or at the ablated tumor, and development of nodular activity.

Complications of microwave and radiofrequency lung ablation: personal experience and review of the literature

PURPOSE

Complications correlated with percutaneous radiofrequency ablation (RFA) and microwave ablation (MWA) of lung tumours were retrospectively reviewed to compare them with data from the literature and to assess risk factors related with the procedures.

MATERIALS AND METHODS

From January 2003 to January 2009, 29 patients (36 lung lesions) were treated with RFA; from January 2007 to January 2009, 16 patients (17 lung lesions) were treated with MWA. Complications recorded at our institution are reported following the Society of Interventional Radiology guidelines. A systematic review of the literature was performed.

RESULTS

Any major complication of RFA or MWA was recorded. In agreement with the literature, pneumothorax was the most frequent complication, even though the incidence in our series was lower than reported in the literature (3.5% vs. 4.3-18%). Other complications of RFA were pleural effusion and subcutaneous emphysema. No massive haemorrhages, haemoptysis, abscesses, pneumonia, infections or tumour seeding were recorded in our series. The most common complication of MWA was pneumothorax (25% vs. 39% reported in the literature). Pleural effusion was a common reaction, but therapeutic drainage was never required.

CONCLUSIONS

Pneumothorax is the most common complication of both techniques. RFA and MWA are both excellent choices in terms of safety and tolerance.