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Numerous techniques have been developed for tissue ablation. Techniques to kill tumor cells include heating, freezing, radiation, chemotherapy, occluding the tumor blood supply, injection of caustic agents directly into the tumor, as well as various combinations of these. While most of these were introduced in the late 20th century, at least one dates back to the 19th century. This chapter reviews the general historical perspectives of these different methods, with particular emphasis on radiofrequency ablation.

PURPOSE: To evaluate the effectiveness of ablation for hepatic tumors. ablation for hepatic tumors. METHODS: The medical records of patients with either primary or secondary hepatic tumors who underwent ablative procedures from February 1991 to May 2001 at a single institution were retrospectively reviewed. reviewed. One hundred nine patients with tumors ranging in size from 0. tumors ranging in size from 0.5 to 12cm in diameter were treated. in diameter were treated. The diagnoses were colorectal cancer (n = 69), hepatoma (n = 15), ovarian cancer (n = 8), cholangiocarcinoma (n = 4), carcinoid (n = 7), one each of leiomyosarcoma, testicular cancer, and endometrial cancer, and other tumors (n = 3). and other tumors (n = 3). Ablation was used to treat 90 tumors: 47 percutaneously, 23 laparoscopically, and 20 intraoperatively. and 20 intraoperatively. Additional tumors were identified by intraoperative ultrasound in 37% of the patients taken to surgery despite extensive preoperative imaging. despite extensive preoperative imaging. In 45%, radiofrequency ablation (RFA) was combined with resection or cryoablation or both. with resection or cryoablation or both. Alcohol ablation was performed on those patients who were found to have residual tumor after the initial ablative procedure. initial ablative procedure. Ten patients underwent a second procedure and three had a third for progressive or recurrent disease. for progressive or recurrent disease. Neoadjuvant chemotherapy was used in 19 cases, intrahepatic treatment in 10, and postoperative chemotherapy was given to 33 patients. chemotherapy was given to 33 patients. Followup ranged between 12 and 28 months.ranged between 12 and 28 months. RESULTS: If we exclude the six cases in which it was clearly impossible to destroy the liver tumors and the one death due to postprocedure myocardial infarction, median progression-free survival was 13 months. survival was 13 months. Tumor response was seen in 87% of cases. seen in 87% of cases. Median time to death or last follow-up was 18 months: 16 months for nonsurvivors, and 20 months for survivors. nonsurvivors, and 20 months for survivors. Complications occurred in 27% of patients and included one skin burn, one postoperative hemorrhage from hepatic parenchyma cracking, and two hepatic abscesses. Only 4. 7% locally recurred, although 37% have died of their cancer, and another 28% developed metastatic disease at other sites. at other sites. CONCLUSION: Ablation may be effective in allowing patients to undergo liver surgery and achieve better survival. surgery and achieve better survival.

Minimally invasive strategies in image-guided tumor ablation are gaining increasing attention as viable therapeutic options for focal primary and secondary hepatic malignancies (1–3). Although liver transplantation continues to be the standard for cure of hepatocellular carcinoma (HCC), there remains a clear need for treatment alternatives in the large population of HCC patients unable to qualify for liver transplantation surgery (4). For hepatic metastases, while conventional surgical resection has demonstrated acceptable rates of success (5) in carefully selected patient populations, several classes of minimally invasive, image-guided therapeutic strategies are being vigorously explored as practical alternatives (2,3). Possible advantages of minimally invasive therapies compared to surgical resection include the anticipated reduction in morbidity and mortality, lower cost, the ability to perform procedures on outpatients, and the potential application in a wider spectrum of patients, including nonsurgical candidates.

Tumor growth is dependent on angiogenesis, the process by which new capillary blood vessels are recruited and sustained. In recent years, key steps in the angiogenic process have been identified, and various angiogenesis inhibitors have been developed. These agents are now in clinical testing for cancer and a number of other diseases. In the majority of cases, angiogenesis inhibitors are being tested alone and in combination with chemotherapy for advanced or metastatic cancers. Recent evidence suggests, however, that they potentially may be beneficial in earlier stage disease (i.e., chemoprevention) or in combination with other modalities such as radiation therapy. Furthermore, tumor ablation techniques such as hyperthermia and chemoembolization work, at least in part, through effects on the tumor vasculature. Understanding mechanisms of tumor angiogenesis, therefore, may shed light on ways to inhibit tumor growth and increase the effectiveness of existing treatment modalities.

Integrating the occasional tumor ablation procedure into a thriving radiology practice is not a particularly difficult job. Patient preoperative workup, billing, and patient follow-up need not change from the usual handling of other interventional radiology or cross-sectional imaging patients. If the intent, however, is to build a large, thriving tumor ablation service, many issues need to be addressed if the venture is to be successful, without placing undue time and financial burden on a radiology practice. My practice is image-guided tumor ablation exclusively, and therefore this chapter focuses on problems and pitfalls associated with building a successful tumor ablation practice.

This chapter provides a short primer on anesthesiology for clinicians who are involved in the care of tumor ablation patients, but who have not been trained in one of the surgical subspecialties. Anesthesiologists, in the role of pain treatment specialists, have long been asked to care for patients with metastatic tumors; the role of anesthesiologists in tumor ablation therapy represents a continuation of a recent trend that has seen anesthesiologists perform their conventional services (i.e., to make the patient insensible to pain) in areas outside of the operating room. Anesthesiologists have expanded their roles in the past several years in angiography, endoscopy, and magnetic resonance imaging (MRI)-guided surgical suites, in which they interact with physician and nonphysician personnel who are as unfamiliar with what the anesthesiologist needs to deliver patient care as the anesthesiologist is with the needs of the team members in these non—operating-room settings.

This chapter reviews the operation of each of several medical systems that is used to deliver local thermal therapy. Each system provides its own mechanism for the transfer of energy within tissue that results in cytotoxic effects. This targeted destruction of cells is referred to as . This chapter concentrates on the medical system itself, and not the principles behind the various mechanisms of tissue ablation. It is concerned with the physician as a user, or , of the ablation system during a procedure. Accordingly, emphasis is placed on the following: the thermal , the , user-defined , and feedback to the operator.

While the continuous development and improvements in tumor ablation techniques and equipment have made the percutaneous non-surgical approach ever more successful, even for larger lesions, there is still a need for ablative treatments in the operating room. In some practices, based on local referral patterns, the surgical approach to tumor ablation may be predominant, either via laparoscopy or open laparotomy. In other settings, additional tumor sites may be encountered during a planned surgical excision that can be efficiently treated intraoperatively with a variety of ablative approaches. Finally, some techniques, such as cryoablation, may be best performed intraoperatively, particularly when treating large tumors with 5- to 10-mm diameter cryoprobes. Therefore, a review of intraoperative ultrasound (IOUS) scanning and guidance techniques for ablation is appropriate. This chapter discusses the optimal approach to intraoperative and laparoscopic ultrasound (LUS) scanning techniques, equipment, technical preparations, and methods for guidance of interventional techniques.

Computed tomography (CT) affords the best visualization of all organs in the body, simultaneously depicting air, soft tissue, and bones on the same scan. This ability makes CT an ideal imaging modality for tissue ablation, as it enables the physician to target any type of organ accurately and to avoid inadvertently puncturing others along the needle path. However, in the past, as the duration of image acquisition and reconstruction was long with CT, this time-consuming aspect appeared inconvenient for tissue ablation. Recent improvements in computerized data management have transformed CT into almost a real-time imaging technique, and even more recently, the advent of multislice CT has made imaging of a volume in a single acquisition feasible, thereby improving the scope of CT guidance for tissue ablation. CT can now be used throughout tissue ablation for guidance, monitoring, and follow-up.

Nuclear medicine imaging involves the injection or ingestion of radioactive Pharmaceuticals known as radiotracers, each designed to track a particular physiologic or pathophysiologic process. In contrast to conventional radiologic imaging such as x-ray computed tomography (CT) and magnetic resonance imaging (MRI), which map out anatomic structure and depend on changes in morphology or size for determination of pathology, nuclear medicine imaging provides information on the metabolic of the investigated organ or tissue.