The advent of radiofrequency ablation (RFA) has changed the treatment strategy of hepatocellular carcinoma (HCC) in Japan. Although RFA is usually applied for the treatment of small HCCs measuring 3cm or less, the indications of RFA have been expanded to larger tumors by combining hepatic arterial embolization. Some tips have been developed to prevent complications, leading to a better prognosis even in the long term. On the other hand, recently, therapeutic results of RFA in liver metastasis patients have been reported and the types of patients who can benefit from liver RFA have been beginning to be understood.

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Recently, the expectation for percutaneous ablation has been increasing in the treatment of renal cell carcinoma (RCC). Potential advantages of this technique are good local control ability with a minimally invasive approach. Moreover, preservation of renal function is also excellent even in patients with reduced renal function. Some recent studies suggest that percutaneous ablation provides comparable oncologic outcomes to nephrectomy with little loss of renal function. This article provides an over view of percutaneous ablation therapy by focusing on radiofrequency ablation (RFA), and discusses the role of this promising technology in the treatment of RCC.

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Cryoablation is one of the potential modalities for tumor destruction and has some special characteristics. It is pain free. The entire frozen area (iceball) is clearly visible on MR and CT images. Hospital stay is very short (two or 3 days). In this century, many papers on renal cryoablation have been published. They report that cryoablation is a safe and effective modality for small renal cell carcinoma (RCC). There are however few papers on the midterm results. The technical success rate has ranged from 94 to 100%. Tumor free survival rate around 2 years ranged from 83% to 96%. When tumors are smaller than 3 cm, one, 3, 5 year tumor free survival rates are 98, 96, and 96% respectively. Recent complication rate is around 12% and serious complication rate is 6-8%. Most common complications are hemorrhage and hematuria.
Recently, High-pressure argon based cryoablation system was approved by the Japanese Health Welfare and Labor ministry for small renal cell carcinoma. The cryoablation system is safe and effective not only for RCC but also hepatocellular carcinoma, uterine fibroid, symptomatic bone tumor, etc.

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Radiofrequency ablation (RFA) is rapidly gaining popularity as a treatment of primary and secondary lung cancer. Inclusion criteria for this treatment include nonsurgical candidates, absence of coagulopathy, severe dysfunction of vital organs, uncontrollable extrapulmonary cancer, and coagulopathy. Number and size of tumors may be ≤ 3 per lung and ≥ 3cm, respectively. Techniques for lung RFA are quite similar to those of percutaneous lung biopsy. Local efficacy of lung RFA depends mainly on tumor size, but not on tumor type. Acquisition of an adequate ablative margin may be a key for local control. Local failure may be salvaged by repeating RFA. Survival rates after RFA are quite promising for patients with clinical stage I non–small cell lung cancer and pulmonary metastasis from colorectal cancer, hepatocellular carcinoma, and renal cell carcinoma. Although lung RFA is generally safe with a mortality rate of <1%, it may cause various complications. The most common complication is pneumothorax. Although most complications can be minor, the physicians should acknowledge and pay attention to rare but serious complications, which include massive hemorrhage, intractable pneumothorax, pulmonary artery pseudoaneurysm, systemic air embolism, pneumonitis, injury of the nearby tissues (e.g., brachial nerve plexus, phrenic nerve, diaphragm, and chest wall), and needle-tract seeding.

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Since 2002, we have applied percutaneous cryoablation for lung tumors (PCLT) under intermittent CT fluoroscopic guidance. In this paper, we describe our experience of PCLT more than 100 cases with about 300 primary or secondary tumors. The procedure was well tolerated by all patients. One-, 2- and 3-year local progression-free rates were 80.4%, 69.0% and 67.7%, respectively. Existence of a thick vessel (diameter ≥3mm) ≤3 mm from the edge of the tumor (P=.003) was assessed as an independent factor associated with local progression by multivariate analysis. Of 193 sessions pneumothorax, pleural effusion, and hemoptysis occurred after 119(61.7%), 136(70.5%), and 71(36.8%) sessions, respectively.
Of all cases with pneumothorax, 17.6% required chest tube insertion and 1.7% required pleurodesis. Delayed and recurrent pneumothorax occurred in 7.8% each. A greater number of cryoprobes was a significant predictor of pneumothorax (P<.001). Male sex (P=.047) and no history of ipsilateral surgery (P=.012) were predictors for the need for chest tube insertion, and no history of ipsilateral surgery (P=.021) was a predictor for delayed/recurrent pneumothorax. The Common Terminology Criteria for Adverse Events (CTCAE) grade 4 and 5 complications were not observed.
The biggest advantage compared with RFA is painlessness in PCLT. In addition, multiple cryoprobe activation is possible in PCLT. One of the drawbacks of PCLT is the difficulty of the PCLT procedure compared with RFA. PCLT could be performed minimally invasively with acceptable rates of local control.

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Irreversible electroporation (IRE) is emerging as a new minimally invasive ablation technique for the treatment of a variety of malignant tumors, which has unique aspects that differ from those of conventional ablation therapies such as radiofrequency ablation or cryotherapy. Electroporation means the formation of nanoscale pores in the cell membrane when certain electric fields are applied across the cell. This phenomenon can be reversible or irreversible according to the strength of the electric field. This non-thermal ablation provides entire tumor cell death preserving the surrounding important structures, such as vessels, bile ducts, and nerves. Tissue regeneration speed after the treatment is considerably faster than that of other ablation techniques. IRE could have potential advantages compared with thermal ablative modalities. Various tumors including liver cancer, pancreatic cancer, lung cancer, prostatic cancer and so on may be included in the application. Short-term treatment outcome is satisfactory and continued exploration is needed in human tumors.

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　We have used a reservoir system with an angiographic catheter and a coaxial microcatheter via the transfemoral route for hepatic arterial infusion chemotherapy (coaxial method), when gastroduodenal artery coil method is not available.
　In this report, we present three cases of catheter fracture at the time of system removal. In all cases, the fracture occurred at the tip and insertion point into the femoral artery of an angiographic catheter.
　When long-term placement of an angiographic catheter is performed for hepatic arterial infusion chemotherapy, attention should be paid to its possible breakage at removal.

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A woman in her 50s was incidentally found to have three bronchial artery aneurysms (with diameters of 24 mm, 12 mm, and 10 mm) during preoperative CT examination for an ovarian tumor. Coil embolization was performed for all three bronchial artery aneurysms. The aneurysm with a diameter of 24 mm was successfully treated with proximal and distal coil embolization. The aneurysms with diameters 12 mm and 10 mm were treated only with proximal coil embolization because the vessels were so tortuous that distal coil embolization would have been difficult. Contrast study performed for confirmation after the operative procedure revealed no aneurysms. Contrast CT performed 4 months after the operation showed that the aneurysms with diameters of 24 mm and 12 mm had successfully been embolized by thrombus formation, whereas the 10 mm aneurysm showed recanalization, suggesting the development of collateral circulation from the pulmonary artery.

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