Background: Ultrasound is known to be useful in imaging radiofrequency ablation (RFA) lesions intra- and postoperatively. The presented study intends to prove the value of ultrasound examination as a means of screening RFA-treated patients for local tumor recurrence.
Patients and methods: During a period of 47 months, 91 RFA treatments were performed in 61 patients in a single institution. Indications for RFA were hepatocellular carcinoma (74%), colorectal metastases (18%), recurrent cholangiocellular carcinoma (5%) and one neuroendocrine tumor metastasis as well as one metastasis of pancreatic cancer (1.5% each). RFA was only considered in non-resectable liver cancer. All applications were conducted under sonographic guidance following preoperative evaluation. Postoperative screening included sonographic examinations at intervals of 3, 6 and 12 months postoperatively, and further annual follow-up examinations. Mean follow-up period was 11.8 months.
Results: Within the first 12 months after treatment, the lesions become more and more inhomogenous with mixed echogeneity. Occasionally, this evolves as a misleading finding, mimicking early tumor recurrence. To clarify suspicious cases (31%), magnetic resonance imaging (20%) or computed tomography (10%) was engaged. Ultrasound led to the detection of local tumor recurrence in 78% of recurrent HCC (13 patients), but only in 67% of metastatic diseases (3 patients). Overall local recurrence rate was 18%.
Conclusion: Ultrasound screening as a follow-up of primary hepatic malignancies is, due to its sensitivity, capable of detecting early local recurrence despite its low specifity. Appropriate application of particular criteria of local recurrence allows B-mode ultrasound to play a major role in screening RFA-treated patients.