2015年 · 第95卷第27期

In recent years, imaging-guided local ablation technique has played an important role in the treatment of liver cancer. Among them, the local ablation treatment represented by radiofrequency ablation (RFA) has the advantages of less trauma, easy operation and remarkable curative effect, which can effectively locally coagulate and inactivate the tumor, and make a breakthrough in the treatment effect of liver cancer^[1]。 RFA is widely used in clinical practice, and its safety and efficacy have been recognized by clinicians. However, the annual incidence of liver cancer in China is high, and there are many large tumors in the middle and late stages at the time of consultation. Most of them are complicated with cirrhosis and poor liver function, and about 70% of them lose the opportunity of surgical resection^[2]Traditional surgical resection treatment also faces the problem of high recurrence rate. Percutaneous minimally invasive ablation for a large number of large liver cancer and recurrent cancer that are not suitable for surgical resection in clinic is difficult and requires high technique. At present, the operators mainly come from doctors in more than ten disciplines such as surgery, internal medicine, interventional department, imaging department or ultrasound department. Influenced by professional limitations, treatment concepts, and judgment on the degree of patients' disease, the treatment effect is uneven, and the recurrence rate and complication rate are high. On the one hand, the clinical demand is large, and on the other hand, it is refractory to treat, which is the bottleneck of RFA treatment in China.

The treatment of primary liver cancer in China has made remarkable progress, among which surgical treatment has played a decisive role. Resection of liver cancer is the most important way to achieve long-term survival by radical therapy. However, the role of surgical resection in the treatment of liver cancer also has certain limits. Non-surgical treatment with local treatment is still the treatment choice for most liver cancer patients, among which local ablation is the first choice for radical treatment for some liver cancer patients who are not suitable for surgery.

Clinical studies have proved that minimally invasive local ablation can achieve satisfactory efficacy and less complications in the treatment of many solid malignant tumors. At present, it is most widely used in the treatment of focal hepatocellular carcinoma (HCC) and secondary liver tumors. It has a wide application range, can treat patients with non-surgical indication and outpatient cases, has low complication and mortality rate immediately after treatment, and has low treatment cost^[1,2,3]。 At present, the most commonly used tumor ablation methods in clinical practice should be mainly divided into two categories: thermal ablation and chemical ablation. The former includes radio frequency, microwave, laser, high intensity focused ultrasound, cryotherapy^[4,5]； The latter consists of injection of ethanol or acetic acid ablation^[6,7]。 A variety of imaging means (e.g., ultrasound, CT, MR, etc.) can guide these treatments. The concept of image guidance is emphasized from the viewpoint of imaging, and it is determined that image guidance is the key to guarantee the success of local treatment. With the advancement of instruments and the adeptness of therapeutic methods, the indications continue to expand. Radiofrequency ablation is increasingly widely used in the treatment of liver tumors, and the understanding of its principle is helpful to select indications and improve treatment equipment. Establishing standards for ablation therapy can help improve communication in this field, promote more accurate comparisons between different techniques, results, and ultimately improve patient treatment results.

Before thermal ablation of liver cancer, detailed imaging examination should be performed. On the one hand, it is necessary to determine whether there is a real lesion in the liver and whether the lesion is a malignant tumor; On the other hand, it is necessary to clarify the location, number, size, blood supply characteristics, growth mode and adjacent relationship of liver tumors, as well as whether there is metastasis in other parts, so as to determine whether thermal ablation treatment can be performed, and then select the appropriate ablation treatment pole (radiofrequency ablation electrode, microwave antenna or cryoprobe), guidance mode and puncture path.

The global incidence of primary liver cancer is increasing year by year, of which hepatocellular carcinoma accounts for 70% to 85%. According to the latest statistics of the World Health Organization, there are 748,300 new cases and 695,900 deaths of primary liver cancer every year, while the number of new cases and deaths of liver cancer in China due to the hepatitis B epidemic is as high as half of the world^[1,2]。 Metastatic cancer is another common malignant tumor of the liver. Gastrointestinal, lung, breast and ovarian cancers are all primary tumors that are prone to liver metastasis. It is reported that 14.5% ~23.0% of colorectal cancer patients have liver metastasis at the same time when the primary tumor is found, and 76.8% of patients will eventually develop liver metastatic cancer^[3]。 For the treatment of liver malignant tumors, partial resection is still the first choice, but surgery is only suitable for 9% to 27% of patients^[4,5]。 Severe secondary cirrhosis and multiple lesions often make many patients with liver cancer lose the opportunity of surgery. In addition, recurrence of tumors occurs frequently after radical resection, and few patients are suitable for reoperation. Therefore, minimally invasive but effective treatment is necessary to improve the prognosis of liver cancer patients. With the development of engineering technology, microwave ablation technology has made rapid progress in the treatment of liver cancer in recent years, and has become an important technology for the treatment of liver cancer, especially for small liver cancer. This technology has become one of the curative methods for early liver cancer except surgical resection and liver transplantation.

With the development and progress of medicine, the treatment methods of liver cancer are constantly updated. Imaging-guided local thermal ablation has become one of the main radical treatment methods for liver cancer, among which radiofrequency ablation (RFA) and microwave ablation (MWA) have been recognized as the first-line treatment methods for early liver cancer. The goal of local thermal ablation therapy for liver cancer is to pursue complete tumor inactivation and avoid complications to the greatest extent. Fully understand and master the causes of thermal ablation complications, prevention and treatment methods, and standardized operation can significantly reduce the occurrence of complications.

Imaging examination is the main method to evaluate the efficacy after liver ablation, which can provide important clinical efficacy-related information. The imaging tests that can be used to evaluate the efficacy after ablation include CT, MR, US, PET, DSA, etc. Among them, CT has become the first choice for evaluating curative effect because of its advantages such as high penetration rate, simple operation, good patient compliance, large examination coverage, complete information such as evaluation form and blood supply. Because of its advantages of multi-parameter imaging and functional imaging, MR has been gradually affirmed in the early detection of residual lesions and the differentiation between postoperative changes and residual and recurrent lesions^[1]。

Iodine-enhanced CT and gadolinium-enhanced MR imaging methods are usually used to judge the efficacy of liver tumor ablation, and their value has been affirmed by many experts. They are the main imaging basis for evaluating the efficacy of ablation, the presence or absence of residual activity and recurrence. Contrast-enhanced ultrasound has some limitations in evaluating the efficacy of routine ultrasound. Contrast-enhanced ultrasound has similar diagnostic value to enhanced CT. It has become one of the effective methods to evaluate the efficacy of ablation in the treatment of liver tumors.

Radiofrequency ablation (RFA) techniques have been widely used in the minimally invasive treatment of hepatocellular carcinoma (HCC), especially in cases where poor liver reserve function cannot tolerate surgical resection or tumor diameter<HCC patients of 3 cm, this technique as a radical treatment means, offers hope for the survival of more patients. Although surgical resection is still considered as the preferred method for the treatment of HCC, after nearly 20 years of clinical application, RFA has achieved good results in the treatment of HCC^[1], diameter<3 cm HCC can achieve results comparable to surgical resection^[2]。 Therefore, this technology has been paid more and more attention and application by surgeons, especially the assistance of laparoscopy, which improves the safety and thoroughness of RFA in the treatment of HCC, and can achieve the purpose of one-time radiofrequency complete ablation for some HCC^[3]。 The understanding of RFA treatment of HCC assisted by laparoscopy under surgical conditions is discussed.

90% of primary liver cancer is hepatocellular carcinoma (HCC), which mostly occurs on the basis of chronic liver disease and its resulting cirrhosis. Therefore, the prognosis of HCC depends not only on oncological factors such as the degree, size, number, location of lesion differentiation, portal vein tumor thrombus and distant metastasis, but also on primary liver diseases (such as hepatitis B, virus replication virus level, alcohol abstinence), liver function reserve status and general condition, and the latter is also an important factor affecting the choice of treatment plan. Therefore, before performing ablation surgery, in addition to comprehensive oncological evaluation of patients, they should also comprehensively evaluate their primary liver disease, liver function reserve status and general condition, and give targeted necessary treatment to achieve the best clinical effect.

The 2011 "Guidelines for Staging and Treatment of Liver Cancer in China" clearly recommended that patients with middle and advanced primary liver cancer need radiotherapy. This is based on a series of reports on the treatment of hepatocellular carcinoma, including the comparison of the effects of radiotherapy and non-radiotherapy. Radiotherapy is one of the comprehensive treatment methods of primary liver cancer. Doctors engaged in the treatment of liver cancer should know its indications, curative effects and corresponding concepts.

Imaging-guided methods for percutaneous radiofrequency ablation of liver cancer include ultrasound, CT, MRI, DSA, etc^[1]。 Ultrasound guidance is the most commonly used method. The DSA fluoroscopic guidance method is used for tumors that have undergone transarterial lipiodol embolization, especially those DSA machines with rotary scan re-imaging capabilities. MRI guidance is rarely used in our country due to its special equipment requirements. CT has strong density resolution and spatial resolution. Combined with enhanced scan and three-dimensional reconstruction, it can clearly show the size, morphology and anatomical relationship with nearby structures, which provides reliable information for conformal ablation treatment. Especially for some small lesions that are deep, hidden and close to the top of the diaphragm, as well as lesions that are difficult to observe by B-ultrasound, CT guidance has more advantages. At the same time, modern CT often has real-time fluoroscopy function, which overcomes the influence of lesion displacement caused by respiratory movement in conventional CT, greatly improves puncture accuracy and saves operation time. The biggest disadvantage of CT is that it has a certain amount of radiation, but by designing a suitable scanning method, the radiation dose will be greatly reduced. Therefore, CT is suitable for various ablation techniques, and is widely used in clinical practice.

The pathogenesis of epilepsy has not been fully elucidated, and the curative effect is poor. Recent studies have found that the epigenetic mechanism is closely related to epilepsy, which has become a hot spot in epilepsy research. There are abnormal epigenetic modifications in the pathogenesis of epilepsy, including DNA methylation, chromatin recombination, histone modification and non-coding RNA regulation. In addition, the application of DNA methyltransferase inhibitors and histone acetylation inhibitors has therapeutic effects on epilepsy. This article will review the research progress of the epigenetic mechanism of epilepsy and its epigenetic therapy.

The incidence of ectopic pregnancy is about 2%^[1,2,3]Deaths due to fallopian tube rupture account for 6% of all first-trimester deaths, and recent data in the United States show that 6% of maternal deaths are related to ectopic pregnancy^[4,5,6]。 Because it has a variety of atypical symptoms and signs in the early stage, it is difficult to diagnose quickly. It is often confused with threatened abortion, inevitable abortion or rupture of the corpus luteum when visiting the gynecological emergency department, and it may also be delayed because the patient neglects the pregnancy and goes to the medical and surgical department. Unknown site pregnancy (PUL) was defined as: human chorionic gonadotropin (HCG) positive but no gestational sac was found intrauterine or extrauterine by transvaginal ultrasound and laparoscopy. There are four possibilities of PUL outcome: disappearance of gestational sac, normal intrauterine pregnancy (IUP), EP and persistent PUL. Atypical EP and PUL are potentially dangerous, requiring repeated transvaginal ultrasound (TVS), dynamic monitoring of hormone levels and even dozens of biomarkers, which is time-consuming and laborious, and bears huge risks, so it is necessary to find new stable and accurate diagnostic markers. Senapati and Barnhart^[7]It is considered that the development of biomarkers from basic research to clinical application is divided into four stages: subclinical stage of basic research, clinical test stage, predictive ability analysis stage in retrospective cohort or (and) case-control study and prospective study stage. The same is true for biomarkers associated with normal pregnancy or with EP.

Although the growth rod technology has unparalleled advantages in conservative treatment and fusion surgery, problems are constantly found and improved during its application. There are still many deficiencies and controversies in the application of growth rods, especially the complications and the selection of the timing of distraction, which have not been well solved.