Histological, CT, and intraoperative ultrasound appearance of hepatic tumors previously treated by laparoscopic radiofrequency ablation

Purpose The purpose of this paper is to compare intraoperative biopsy results of previously ablated liver tumors with their preoperative computed tomography (CT) and intraoperative laparoscopic ultrasound (LUS) appearances in patients undergoing repeat radiofrequency ablation (RFA). Methods Seventy repeat RFA procedures were performed in 59 (13%) patients. Laparoscopically, suspected recurrent and stable appearing foci were biopsied using an 18 G biopsy gun. Preoperative CT and LUS appearances of the previously ablated lesions were compared with core biopsy results. Results There were 33 patients with colorectal cancer, 11 with hepatocellular cancer, 8 with neuroendocrine tumors, and 7 with other tumor types. Two hundred lesions were treated by RFA in these 70 repeat ablations. Suspected recurrent tumor foci were enhanced on CT and produced a more finely stippled echo pattern on LUS. Biopsy confirmed recurrent tumor in 72 of 84 such lesions. Previously ablated foci had a CT appearance of a hypodense, nonenhancing lesion without evidence of adjacent enhancing foci. Laparoscopic ultrasound appearance was of a hypoechoic lesion with a coarse internal pattern with the tracks of the ablation catheter probes often still visible. Biopsy found necrotic tissue in 21 of 22 such lesions appearing radiologically to be without recurrence. Biopsy of an ablated focus adjacent to an area of suspected recurrence showed necrotic tissue in 17 of 22 lesions and viable cancer in 5. Conclusion CT and LUS appearance of previously ablated foci showed good correlation with core biopsies. CT scan is reliable in following RFA lesions, without the need for routine biopsy. LUS reliably distinguished recurrent from ablated lesions in patients undergoing repeat ablation.