Microwave coagulation using a perfusion microwave electrode: Preliminary experimental study using ex vivo and in vivo liver.

To assess the coagulation capability of a perfusion microwave electrode (PME) as a key component of microwave coagulation therapy, a preliminary experimental study was performed using ex vivo and in vivo livers. For a microwave electrode, a PME was employed. Using a PME, saline was passed through the electrode and injected continuously into the target tissue. Using an ex vivo bovine liver, the range of tissue coagulation was measured for various volumes of infused saline and microwave outputs. Using an in vivo porcine liver, the efficiency of coagulation by a PME was compared with that of radiofrequency ablation (RFA) using a cool-tip needle. In an ex vivo bovine liver, the range of tissue coagulation increased as the flow rate of saline increased. In the in vivo porcine liver, the range of coagulation was similar to that found in the ex vivo bovine liver. With a PME under conditions of a microwave output of 80 W, a flow rate of 3 ml/min and irradiation time of 5 min, the range of coagulation was 44.8±2.8 mm [maximum vertical diameter: (a)] x 31.2±2.4 mm [maximum transverse diameter: (b)]. The range of RFA (cool-tip needle) at 12 min was 46.0±2.0 mm (a) x 30.2±2.0 mm (b). With only 5 min of microwave irradiation, the use of a PME enabled induction of the same range of coagulation that was obtainable by RFA for 12 min. In comparison with microwave coagulation without saline infusion, the use of a PME made it possible to extend the range of tissue coagulation to a range equal to that of RFA in a short time. Microwave coagulation using a PME may be one of the suitable tissue coagulation systems for local ablation treatment.

Combined treatment of large hepatocellular carcinoma with transcatheter arterial chemoembolization and percutaneous ethanol injection with a multipronged needle: experimental and clinical investigation.

PURPOSE: This study was designed to evaluate the usefulness of percutaneous ethanol injection (PEI) with a multipronged needle for the treatment of large hepatocellular carcinoma (HCC). An experimental animal study and a clinical investigation were performed. METHODS: In the experimental study, 20 ml of 99.5% ethanol was injected into porcine liver in vivo with a multipronged needle (n = 5) or a straight needle (n = 5), and the volumes of coagulation necrosis were compared. In the clinical investigation, PEI was performed in 17 patients (10 men, 7 women; mean age 73.4 ± 6.7 years) with single, large HCC (mean tumor diameter, 47.2 ± 11.5 mm; range, 32-70 mm) by using a multipronged needle. Fifteen of 17 patients received transarterial chemoembolization (TACE) before PEI. RESULTS: The volume of coagulation in porcine liver in vivo was significantly increased with the multipronged needle compared with the straight needle (longest perpendicular diameters, 34.2 ± 3.6 mm × 30.2 ± 3.6 mm vs. 22.6 ± 2.5 mm × 19 ± 2.2 mm, respectively; P < 0.05). In the clinical trial, initial complete response (CR) of the tumor was achieved in 17 of 17 patients, 7 of whom required two PEI sessions. During the follow-up, local recurrence was detected in 4 of 17 patients at 3-19 months after the procedure, for a rate of sustained local CR of 76%. No major complication occurred. CONCLUSIONS: Use of a multipronged needle substantially increases the volume of coagulation in vivo with respect to the conventional PEI technique. Combined TACE and PEI with multipronged needles is a safe and effective option for percutaneous treatment of single, large HCC.

Percutaneous microwave coagulation therapy for hepatocellular carcinoma: increased coagulation diameter using a new electrode and microwave generator.

We performed percutaneous microwave co-agulation therapy (PMCT) using a new microwave electrode and microwave generator to lessen the number of microwave electrode insertions for hepatocellular carcinoma (HCC) measuring 2 to 2.5 to or=5 mm on dynamic computed tomography. Necrosis of HCC and the non-cancerous area surrounding the tumor was obtained by a single needle insertion in 23 patients (tumor size: 2 to 2.5 to 2 to 2.5 to or=5 mm, we have not detected local recurrences. On the other hand, 4 of the 10 patients who could not obtain the treated margin of >or=5 mm, experienced a local recurrence. No fatal complications were observed. However, bile duct stricture was observed in 2 patients. The new microwave coagulation system can induce extensive necrosis with a small number of microwave electrode insertions. This system may enhance the efficacy of PMCT for HCC measuring <3.0 cm in diameter.

Clinicopathologic study of small hepatocellular carcinoma with microscopic satellite nodules to determine the extent of tumor ablation by local therapy.

To determine the optimal treatment margin of local ablation therapy for small hepatocellular carcinoma (HCC), we investigated characteristics of microscopic satellite HCC nodules (msn) using resected livers, and the incidence of local recurrences in patients who underwent percutaneous microwave coagulation therapy (PMCT) according to whether or not an adequate treatment margin was achieved. We reviewed 117 single small HCCs (tumor size < or =3 cm ) resected with a > or =1-cm surgical margin. Among the surgically resected tumors, none of the msn were detected by preoperative imaging. When an msn was observed in the resected specimen, the maximum distance from the edge of the tumor to the msn was measured. Among the tumors sized < or =2 cm (n=66), the number having msn and the distance (mm) from the main tumor according to the degree of tumor differentiation were as follows: well (n=16), 1 (6.2%) and 1.4 mm; moderate (n=46), 5 (19.2%) and 5.8+/-1.2 mm; and poor (n=4), 1 (25.0%) and 4.8 mm. Among the tumors sized 2 to 3 cm (n=51), the corresponding results were: well (n=11), 3 (27.2%) and 3.5+/-2.2 mm; moderate (n=36), 6 (16.7%) and 5.4+/-1.4 mm; and poor (n=4), 1 (25.0%) and 4.9 mm. Of the 112 vascular tumors, 17 (15%) had msn. The 5 avascular tumors had no msn. Among the patients who underwent PMCT with a treatment margin measuring <5 mm, local recurrence occurred in 2 of 25 patients whose original tumor was < or =2 cm, and 3 of 25 (12%) patients of those with tumors of 2 to 3 cm. No patient with a tumor < or =3 cm and a > or =5-mm treatment margin suffered a local recurrence. The results of this study suggest that the incidence of local recurrence may be reduced by achieving a treatment margin of any width for avascular tumors and a margin of 1 cm for vascular tumors during local ablation therapy for small HCCs of < or =3 cm.