الفهرس | Only 14 pages are availabe for public view |
Abstract Postprocedural cross-sectional imaging is a must to assess the response to treatment. Computed tomography (CT), positron emission tomography (PET), and dual-modality imaging with combined PET and CT (PET/CT) are primarily used for this purpose. It also allows detection of procedure-related complications, metachronous tumors, and metastatic disease. An understanding of the anticipated and unexpected imaging features of the RFA zone is essential for accurate assessment of the response to treatment. Because a patient with recurrence may potentially undergo repeated treatment if the recurrence is detected early, the recognition of early signs of incomplete therapy or recurrence is also critical. 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 more than the preablation tumor (>180 seconds on dynamic images), nodular enhancement measuring more than 10 mm, any central enhancement greater than 15 HU, and enhancement greater than baseline any time after ablation; (b) growth of the RFA zone after 3 months (compared with baseline) and definitely after 6 months, peripheral 95 nodular growth and change from ground-glass opacity to solid opacity, regional or distant lymph node enlarge¬ment, and new intrathoracic or extrathoracic disease; and (c) increased met¬abolic activity beyond 2 months, residual activity centrally or at the ablated tumor, and development of nodular activity. Reliable imaging surveillance after thermal ablation is essential and remains a mainstay for its continued success. A firm understanding of the expected and unexpected imaging features of the ablation zone is critical for accurate assessment of treatment response and early identification of incomplete ablation, and locoregional and/or distant progression of disease. Non enhanced and contrast-enhanced CT, PET, and PET/CT should be used in conjunction as routine follow-up or as problem-solving modalities, and biopsy should be entertained whenever imaging findings are equivocal. Even with 100% local control, an already predetermined number of treated individuals will have microscopic disease beyond their ablated tumor that is below the detection of currently available imaging techniques. This, further exacerbated by high-risk patient populations in which pathologic staging is unavailable, should drive diligent and rigorous patient follow-up. |