The word of "next generation" connotes somewhat a new start departing from the past and the present. The MicrotazeTM with various electrodes using a magnetron oscillator has been well accepted as a microwave dielectric apparatus as a medical surgical device, and proven by many clinical experiments and experiences. The magnetron is within a sphere of "analog" world and economically produced. In the decades, the semiconductor technology of the "digital" world has been rising. And entering into the next generation concept in the "digital" world, we attempt to introduce a microwave dielectric heating device with an automatic regulation system using compound semiconductors. An initial fundamental electric study has been conducted, utilizing semiconductor technologies and compared with the current MicrotazeTM performance. The preliminary experiments confirmed the superiority of the semiconductor controlled apparatus and meet with our ideas of the next generation microwave dielectric heating apparatus. That is, we will develop a system that automatically and successively control radiating frequencies, energy levels, VSWR levels, temperatures, permittivity, and dielectric loss in the process of time.
Microwaves do not interfere with magnetic resonance imaging (MRI), since these wave frequencies differ from each other. We have found that the microwaves have a special mechanism to fix living tissues around the temperature of 60 °C, and that the microwave device can be used as a surgical instrument under MRI. These characteristics have offered us a new horizon of the surgery under the MR monitor imaging. Thus, it is an evolution not only for the microwave devices but also for the microwave surgery (a surgery using microwave). Several new devices were developed, such as a bipolar tissue coagulator (fixer), scissors, a microwave knife, and a regional hyperthermia device. These new devices are introduced in this paper.
In consideration of women's quality of life, the surgery in gynecologic fields is replaced from laparotomy to endoscopic surgery. An operation of uterine leiomyoma is also changing from an abdominal hysterectomy into minimally invasive conservative surgery. The methods include a laparoscopic myomectomy and hysteroscopic myomectomy. Additionally we device and investigate laparoscopic microwave coagulation therapy and MR-guided transcervical microwave coagulation therapy for uterine leiomyoma. Clinically, a therapy should be selected after explaining an indication, a merit, a demerit and a possible complication of the therapy to a patient intelligibly, and having got enough understanding.
Recently, with an increasing uses of the high-resolution CT scan, the effectiveness of detecting tiny tumors in the peripheral lung, such as early stage lung carcinoma, small metastases, or atypical adenomatous hyperplasia, has increased. Video-assisted thoracic surgery is usually employed for many of these cases. However, we considered that a more minimal invasive therapy was necessary for patients who were inoperable due to low cardio-pulmonary function, other complications, severe adhesion and advanced age. Several investigators have applied various types of CT guided percutaneous modalities including percutaneous microwave coagulation therapy (PMCT), radiofrequency ablation (RFA), cryotherapy and photodynamic therapy (PDT) for small peripheral lung tumors experimentally and clinically and examined the possibility of these modalities for small lung tumors in inoperable patients. We reviewed their efficacy and safety. These percutaneous therapies demonstrate that good local control rate of 70-80%. However, recurrence from the tumor margin was of a problem. Pneumothrax occurred in 33.3-53.8% which is a main complication. CT guided percutaneous therapies are considered to be a useful modality as a minimally invasive therapy for peripheral lung tumors with the intent of palliative or curative treatments. The results demonstrated the possibility of percutaneous modalities for the patients with small peripheral lung tumors in near future.
Microwave energy is one of the heating sources used for thermal therapy of cancer. The thermal therapy means the hyperthermia and the coagulation therapy. In the hyperthermic treatment, the target tumor is heated up to 42-45 °C and in the coagulation therapy, it must be heated 60 °C or more to generate the tissue coagulation. In this manner, although therapeutic temperatures of both schemes are different, there are several similarities between them especially from the engineering aspects. Therefore, this paper describes the fundamental characteristics of microwave inside the biological tissue and two types of heating schemes for the hyperthermic treatments. In addition, the actual treatment by use of newly developed microwave antennas is introduced.
We analyzed the prognosis of the patients who received radiofrequency ablation (RFA) therapy at our hospital, and tried to establish our treatment-strategy for hepatocellular carcinoma (HCC). The subjects were 180 HCC patients. The 5 years survival rate was 70% for the 90 naive cases who matched the Milan criteria. The prognosis was clearly different in 3 groups classified according to the category combining tumor number and tumor size. As a result, the Milan criteria were useful for RFA indication and among them the best candidate was HCCs solitary and less than 3 cm in diameter. Furthermore, HCCs less than 3 cm in diameter and more than 4 in number were also indicative if they were defined as multi-centric development. In conclusion, there is a possibility that the indication of RFA for HCC is wider than the Milan criteria.
Chronic hepatitis C is a leading cause of hepatocellular carcinoma worldwide. Interferon therapy decreases the incidence of hepatocellular carcinoma in patients with chronic hepatitis C. Prevention of chronic hepatitis C-related HCC is one of the most important issues in current hepatology. We previously reported that male gender and high-titer of HCV-RNA were predictive factors for the development of hepatocellular carcinoma in the anti-HCV positive group. Clinical efforts of eradicating or reducing the viral load may reduce the risk for hepatocellular carcinoma. Furthermore, because hepatocellular carcinoma often recurs after ablation therapy, we performed a trial of interferon in patients with chronic liver disease caused by hepatitis C virus (HCV) to investigate whether the interferon therapy decrease the recurrence after ablation therapy of hepatitis C virus-related hepatocellular carcinoma. By the interferon therapy as secondary prevention, we found that the patients with hepatocellular carcinoma who had received complete tumor ablation might be associated with better survival, primarily as a result of the preservation of liver function and also probably the prevention of recurrence. Postoperative interferon therapy appears to decrease recurrence after ablation therapy such as radiofrequency ablation therapy of hepatitis C virus-related hepatocellular carcinoma.
We evaluated the efficacy of radiofrequency ablation (RFA) therapy for 60 patients with 94 hepatocellular carcinoma (HCC) nodules of equal to or less than 3 cm in diameter and 42 patients with 45 HCC nodules of larger than 3 cm in diameter. HCC nodules of equal to or less than 3 cm were treated with RFA alone. In these patients, the 5-year local recurrence rates were 8.6%, and the 5-year survival rates were 62%. Of 45 patients with HCC nodules of larger than 3 cm, 21 were treated with RFA alone, 16 were treated with a combination of RFA and chemoembolization (TAE), and 7 were treated with a combination of RFA and occlusion of both hepatic artery and portal vein. In the RFA alone, the 5-year local recurrence rates were 29%, and the 5-year survival rates were 61%. In the combination of RFA and TAE, the 5-year local recurrence rates were 27%, and the 5-year survival rates were 42%. In the combination of RFA and occlusion of both hepatic artery and portal vein, the 5-year local recurrence rates were 14%, and the 5-year survival rates were 71%. These treatment results were the same class or more in comparison with treatment results of a No. 17 follow-up survey report by Liver Cancer Study Group of Japan. Our experience suggests that RFA alone is effective in the treatment of HCC nodules equal to or less than 3 cm, and RFA with occlusion of blood flow is effective for HCC nodules of larger than 3 cm.
Purpose : To evaluate the usefulness of contrast-enhanced ultrasonography (CEUS) guidance in RFA for HCC that could not be depicted by US. Methods and materials : Thirty-seven HCCs that could be depicted by US underwent RFA. Five HCCs that could not be depicted by US underwent RFA guided by real-time CEUS. Results : (Conventional RFA Group) In 9 (38%) of 24 HCCs evaluated with CEUS after initial RFA, residual lesions were found. These lesions could be treated with PEIT guided by CEUS. There was only one local tumor recurrence (4.2%). On the other hand, in 5 (39%) of 13 HCCs evaluated with only contrast-enhanced helical CT after initial RFA, residual lesions were found. These lesions were treated with conventional PEIT. There were 3 local tumor recurrences (23%). (CEUS RFA Group) There was no residual lesion and local recurrence. Conclusion : CEUS may be useful in real-time guiding PEIT and RFA in HCC that could not be depicted by US.
Between July 1994 and December 2005, 1,324 patients underwent hepatic surgery in our institute. Of these patients, 508 patients who received their initial therapy for HCC were analyzed this time. MCN (microwave coagulo-necrotic therapy) was performed in 369 patients, hepatic resection (Hr) was in 98, and Hr + MCN was in 38. The remaining 3 patients were treated with laparotomic ethanol injection. The 1-, 3-, 5-, and 10-year cumulative survival rates for patients treated with MCN (mean tumor size, 28.8mm ; mean number of lesion, 2.63 ; Liver Damage, A in 39.1%, B in 56.8%, and C in 4.1%) were 97.3%, 80.2%, 62.3%, and 35.1%, respectively. Five-year survival rate was 62.3% in MCN and 60.8% in Hr group (p = 0.6047). The 1-, 3-, and 5-year local recurrence rates with MCN were 1.8%, 4.3%, and 5.4%. and those with Hr were 1.1%, 4,1%, and 4.1% (p = 0.8990). The 1-, 3-, and 5-year cumulative survival rates for 109 patients, who had 4 or more tumors, were 95.0%, 69.0%, and 43.3%. The 3-, 5-, and 10-year cumulative survival rates for the liver damage-A-patients treated with MCN were 87.6%, 68.9%, and 31.6%. Those for the liver damage-B-patients with MCN were 77.2%, 59.5%, and 37.6%. Based on the above, it was suggested that MCN has the good ability of loco-regional control of HCC and it is less invasive to the patients, especially with multiple tumors and/or with severe liver function. Therefore, we recommend MCN as a first choice for the treatment of HCC.
We analyzed the rates of survival, non-local recurrence, and non-another recurrence of 89 patients with solitary hepatocellular carcinoma who underwent thermal ablation therapies as primary treatment (naive patients). Thirty five cases were ablated by percutaneous radiofrequency ablation (PRFA), 32 and 22 were treated by laparoscopic microwave coagulation (LMCT) and by percutaneous microwave coagulation (PMCT), respectively. Five-year survival rates were 87%, 60%, and 82% in PRFA, LMCT, and PMCT, respectively, with no statistical significance. Rates of 5-year non-local recurrence were 60%, 74%, and 51% in PRFA, LMCT, and PMCT, respectively, with no statistical significance. Those of 5-year non-another recurrence were 0%, 19%, and 20%, with no statistical significance.Thus, PRFA, LMCT, and PMCT had same effectiveness for the local treatment of HCC.
Purpose : The purposes of this study were to classify electricity process during percutaneous radiofrequecy ablation (P-RFA) for liver tumors, and to propose the usefulness of our ablation protocol. Objects and methods : 149 patients were diagnosed liver tumors from June 2004 to January 2006. Of these patients, total 282 nodules were treated with P-RFA Cool-tip® type RFA system. During ablation, two electricity methods (standard protocol and our modified protocol) were compared to identify a suitable RF voltage for impedance of every nodule. Results : The voltage of the first break was 100 V in type 1 (151 nodules), over 100 V in type 2 (47 nodules), under 100 V in type 3 (84 nodules). Regardless of the electricity method, incomplete ablation rate was 0% in the type 1. In the type 2 and type 3, the rates were 9.4% and 14.3% in the standard protocol, v.s. 0%, 7.1% in our modified protocol, respectively. Conclusion : Our individualized electricity protocol, suitable voltage controlled ablation is more effective than standard protocol.
The aim of this study is to evaluate the merits of various solutions when we perform artificial acites as an aid to percutaneous RFA therapy. We made an experimental model of RFA using a special plastic container. A piece of swine liver as ablation sample was placed in this container full of 1,500 mL saline or 5% glucose solution as artificial ascites. RFA was performed using 17 G cooled electrode with 2 cm exposed tip. The duration of ablation was 5 minutes and generated power was 20 W. We assessed necrotic area, tissue temperature and impedance. Ablation area was 28 mm and 22 mm using saline and 5% glucose solution respectively. Temperature of ablation tissue was 84°C and 79°C for each. Our data suggest that we had more effective RFA by using saline than 5% glucose solution in artificial ascites. We found saline to be recommended for artificial ascites technique.
A 70-year-old man was admitted for suspected hepatocellular carcinoma (HCC). Abdominal CT detected a tumor mass 2.5 cm in diameter protruding from the surface of the right lobe of his liver. We decided to perform radiofrequency ablation (RFA) with laparoscopic guidance. Laparoscopy revealed the HCC being adjacent to the costae on the outermost side of the right lobe; it was difficult to safely puncture an electrode needle into the tumor. Hence, we infused normal saline (artificial ascites) into the space between the liver and abdominal wall, and then performed percutaneous RFA with ultrasonography guidance. Using this laparoscopic artificial ascites technique, we could safely and easily perform ultrasonography-guided percutaneous RFA for HCC on the outermost side of the right lobe of the liver, which is otherwise difficult to treat by laparoscopic or percutaneous approach.
CT-assisted radiofrequency ablation (RFA) using real-time virtual sonography (RVS) was performed for 3 patients with hepatocellular carcinoma (HCC) undetectable with conventional sonography. Combined CTHA and CTAP DICOM image or dynamic CT/MRI image were used as RVS reference images. RFA was performed in the CT room. The tumor site was punctured under sonography together with RVS, and immediately, CT was performed. Ablation was conducted after confirming on CT and 3D images that the needle had been inserted into the tumor. The RFA needle was inserted into the tumor in all cases. This method allowed safe ablation with enough margin without complications. CT-assisted RFA using RVS is a safe and effective treatment for HCC undetectable with conventional sonography.
The case is a 74-year-old-female who was treated with percutaneous transhepatic low output microwave tissue coagulation therapy (PLMCT) using a new needle electrode 1 mm in diameter for liver tumor. This needle electrode is more useful than an old type 16 G needle electrode in strength and for the point that coagulated tissue is hard to adherent to the electrode. PLMCT was performed at the output of 30 watt for 90 seconds at a time. Tumor 1.5 cm in diameter was completely coagulated by irradiation 6 times and blood flow of vessel in touch with tumor was preserved judged by enhanced CT. The results suggested that PLMCT using a new electrode 1 mm in diameter is a useful therapy for small solitary liver tumor.
We investigated efficacy of microwave ablation plus hepatectomy for multiple colorectal liver metastases. Clinicopathologic data were analyzed retrospectively for 71 consecutive patients with four or more bilobar liver metastases from colorectal cancer who underwent hepatectomy with or without microwave ablation. Overall, no significant differences were found and as well as disease-free survival between 19 patients with resection/ablation and 52 patients with resection (p = 0.18 and 0.93). Multivariate analysis selected prehepatectomy carcinoembryonic antigen concentration in serum as an independent prognosticator for survival (p = 0.04), but not resection/ablation vs. resection. In the patients with combined resection/ablation, recurrences occurred near the resection or ablation line in only 3 patient (30%, although multiple tumors (≥ 4) were the most common liver recurrence pattern (60%). Microwave ablation plus hepatic resection expanded indications for surgery to treat multiple bilobar liver metastases.
Surgical resection is the most effective therapy for colorectal liver metastases, subsequently there are chemotherapy and thermal destruction technique using microwave coagulation therapy (MCT) and radiofrequency ablation therapy (RFA). As the surgical approach is generally guided by these criteria (cancer factors : Tumor staging, differentiation of tumor, recurrence free interval, node status and transition of CEA. patient factors : age, liver function and performance status) and these criteria are intricated, the majority of patients present practically with unresectable. The thermal destructive therapy is well acceptable for hepatocellular cancer but not for colorectal liver metastases. We review the patients of colorectal liver metastases that we performed the thermal destructive therapy.
Radiofrequency ablation (RFA) was used to treat colorectal liver metastases, and the prognosis of hepatic resection with RFA (Hr + RFA, n = 15) was compared with that of hepatic artery infusion chemotherapy (HAI, n = 43) in patients with unresectable liver metastases. Hr + RFA group 4-year survival rate was 37.5%, and better than the HAI group 2-year survival rate of 13.4%. When local recurrence rate after RFA was determined for those with colorectal liver metastases (LM, n = 30) or hepatocellular carcinoma (HCC, n = 174), tumor diameter affected recurrence rate in neither group, though recurrence rate increased with tumor size. Our findings suggest that RFA is indicated for patients whose tumor diameter is 2 cm or less, since their recurrence rate should be lower. RFA thus appears useful for treating colorectal liver metastases.
The aim of this study is to verify whether transperineal needle microwave needle ablation under transrectal prostate sonography is safe and effective for the patients with symptomatic benign prostatic hyperplasia. Three patients having International Prostate Symptom Score (IPSS) above 8 and quality of life (QOL) index above 2 were enrolled in this study. After full explanation of the objective and method of this study, which our Institutional Reviewer Board approved, informed consent was obtained from all patients. The operations were performed under general anesthesia in all cases. The mean operation time was 52 min. Postoperatively, the IPSS and QOL index improved from 14.7 to 10.3 and 6.0 to 4.7, respectively. Furthermore, the maximum urine flow rate increased from 6.3 to 14.3 mL/s, and the volume of prostate decreased from 70.3 to 35.1 cm3 after 3 months. There were no surgical complications. We concluded that transperineal needle microwave needle ablation under transrectal prostate sonography was safe and effective for the patients with symptomatic benign prostatic hyperplasia.
Retroperitoneoscopic nephron-sparing surgery using a microwave tissue coagulator (MTC) without renal ischemia is feasible as minimally invasive procedure for small renal tumor. However, the indication of this procedure is limited for exophytic small renal tumors because of uncontrollable urine leakage as a typical complication of MTC. We performed retroperitoneoscope-assisted partial nephrectomy using MCT even for non-exophytic small renal cell carcinoma under 5-6 cm small skin incision. We report the points and pitfalls of the operative procedure.
To accomplish MR-guided microwave endometrial ablation, a sounding applicator type MR-compatible microwave electrode has been constructed. The visibility of the electrode in MR images was appropriate and temperature changes during microwave ablation were clearly shown with MR temperature maps. Optical and electromagnetic tracking systems for this electrode have also been developed. Both of them were able to control MR image planes with its curved electrode tip, successfully. With the optical tracking system, however, the configuration needs to be changed depending on the direction of the electrode because of the visibility of diodes. Meanwhile, electromagnetic tracking system could be used in any directions of the electrode without taking care of the line of sights and was found to be quite useful for such curved surgical instruments.