Current role of image-guided ablative therapies in lung cancer

Salvage treatment of NSCLC recurrence after first-line chemotherapy failure: Iodine-125 seed brachytherapy or microwave ablation?

Background

Salvage treatments for recurrent NSCLC after first‐line chemotherapy remain challenging. This study was conducted to evaluate the clinical value of microwave ablation (MWA) and iodine‐125 brachytherapy, including overall survival (OS), disease free survival (DFS), local control, hospital stay, and health economics.

Methods

The data of 51 and 32 patients who were treated with MWA and brachytherapy was retrospectively analyzed. The number of lesions was limited up to two, with a diameter <4 cm and patients diagnosed with unilateral lung disease. Peripheral tumors were treated with MWA, while lesions close to the hilum were treated with brachytherapy. Contrast‐enhanced CT, blood cell count, coagulation function, liver & kidney function and tumor markers were performed for two years, with complications calculated. OS, DFS, local control rate, toxicity, hospital stay and expense were recorded.

Results

The one and two‐year OS rates were 96.08% and 92.16% versus 96.88% and 90.62% in the MWA and brachytherapy groups, respectively. The one and two‐year DFS rates were 92.16% and 76.47% versus 93.75% and 78.13%, respectively. No significant differences were observed in log‐rank analysis between the groups. Local control rates at six and 12 months were 100% and 96.08% versus 100% and 96.88%, while incidences of pleural effusion were 3.92% and 3.13%, respectively (P < 0.05). Medical cost was 3356.73 ± 206.87 and 6714.28 ± 35.43 U.S. dollars (P = 0.014).

Conclusion

MWA and brachytherapy are effective and safe options for the treatment of NSCLC recurrence after first‐line chemotherapy. Which modality should be considered is dependent upon tumor location, tumor size and experience of specialists.

Comparison between computed tomography-guided percutaneous microwave ablation and thoracoscopic lobectomy for stage I non-small cell lung cancer

Background

The study was conducted to investigate the effectiveness and cost of computed tomography (CT)‐guided percutaneous microwave ablation (MWA) and thoracoscopic lobectomy for stage I non‐small cell lung cancer (NSCLC).

Methods

We retrospectively analyzed the data of 46 and 85 patients with stage I NSCLC treated with CT‐guided percutaneous MWA or thoracoscopic lobectomy, respectively, at our center from July 2013 to June 2015. Overall survival (OS), disease‐free survival (DFS), local control rate, hospital stay, and cost were evaluated. Survival curves were constructed using the Kaplan–Meier method and compared using the log‐rank test.

Results

The one and two‐year OS rates were 97.82% and 91.30% and 97.65% and 90.59% in the MWA and lobectomy groups, respectively. The one and two‐year DFS rates were 95.65% and 76.09% and 95.29% and 75.29%, respectively. No significant differences were observed in log‐rank analysis between the groups (P = 0.169). The hospital stays in the MWA and lobectomy groups were 6.62 ± 2.31 and 9.57 ± 3.19 days, respectively. The costs of MWA and lobectomy were US$3274.50 ± US$233.91 and US$4678.87 ± US$155.96, respectively. The differences were all significant (P = 0.003).

Conclusion

MWA and thoracoscopic lobectomy for stage I NSCLC demonstrate similar one and two‐year OS and DFS, with no significant differences between the two groups. MWA involved a shorter hospital stay and lower cost, thus should be considered a better option for patients with severe cardiopulmonary comorbidity and patients unwilling to undergo surgery.

Radiofrequency ablation for hepatic oligometastatic pancreatic cancer: An analysis of safety and efficacy

OBJECTIVES

This study was to evaluate the value of radiofrequency ablation (RFA) in the treatment of pancreatic cancer with synchronous liver oligometastasis.

METHODS

102 patients diagnosed with pancreatic cancer with synchronous liver oligometastasis undergoing RFA were recruited in this retrospective study between January 2012 and December 2015. Clinical efficacy was evaluated by computed tomography or magnetic resonance imaging 1 month later. All patients were treated with RFA and systemic chemotherapy based on NCCN guideline.

RESULTS

The median follow-up was 21 months (range, 4.0-43.8 months). Of all patients, the 1-year survival rate was 47.1% and the median overall survival time was 11.40 months. Complete tumor ablation was achieved in 137 of 145 RFA sessions (94.5%), and in 244 of 254 tumors (96.1%). The incidence of common complications was 9.8%, and no severe complications were reported in any patient. Multivariate Cox regression analysis revealed that primary tumor in the head of the pancreas (HR = 1.868, 95% CI: 1.023-3.409; P = 0.042), maximum diameter of liver metastasis 3-5 cm (HR = 1.801, 95% CI: 1.081-3.001, P = 0.024) and neutrophil/lymphocyte ratio (NLR) ≥2.5 (HR = 1.716, 95% CI: 1.047-2.811; P = 0.032) were independent predictors of poorer survival.

CONCLUSION

RFA provides a minimally invasive and safe treatment for patients with pancreatic cancer with liver oligometastases. The clinical efficiency of RFA for hepatic oligometastatic pancreatic cancer was easily affected by the following factors: primary tumor location, maximum diameter of liver metastasis and NLR. These factors could be helpful for treatment decision and clinical trial design.

Endoscopic ultrasound-guided radiofrequency ablation in gastroenterology: New horizons in search

Radiofrequency ablation (RFA) has been widely used for the treatment of various solid organ malignancies. Over the last decade, endosonographers have gradually shifted the application of RFA from porcine models to humans to treat a spectrum of diseases. RFA is performed in patients with pancreatic carcinoma who are not candidates for surgery. In this paper, we will discuss various indications for RFA, its procedural details and complications. At present, endoscopic ultrasound-guided RFA is gradually incorporated into the management of various diseases and opens a new avenue for disease treatment.

Endoscopic palliation of malignant biliary strictures

Malignant biliary strictures often present late after the window for curative resection has elapsed. In such patients, the goal of therapy is typically focused on palliation. While historically, palliative measures were performed surgically, the advent of endoscopic intervention offers minimally invasive options to provide relief of symptoms, improve quality of life, and in some cases, increase survival of these patients. Some of these therapies, such as endoscopic biliary decompression, have become mainstays of treatment for decades, whereas newer modalities, including radiofrequency ablation, and photodynamic therapy offer additional options for patients with incurable biliary malignancies.

Primary Treatment Options for High-Risk/Medically Inoperable Early Stage NSCLC Patients

Lung cancer is among the most common cancers worldwide and is the leading cause of cancer death in both men and women. For patients with early stage (American Joint Committee on Cancer T1-2, N0) non-small-cell lung cancer, the current standard of care is lobectomy with systematic lymph node evaluation. Unfortunately, patients with lung cancer often have medical comorbities, which may preclude the option of surgical resection. In such cases, a number of minimally invasive to noninvasive treatment options have gained popularity in the treatment of these high-risk patients. These modalities provide significant advantages, including patient convenience, treatment in an outpatient setting, and acceptable toxicities, including reduced impact on lung function and a modest risk of postprocedure chest wall pain. We provide a comprehensive review of the literature, including reported outcomes, complications, and limitations of sublobar resection with or without intraoperative brachytherapy, radiofrequency ablation, microwave ablation, percutaneous cryoablation, photodynamic therapy, and stereotactic body radiotherapy.

Comprehensive surgical management of pancreatic cancer

Pancreatic cancer is a malignancy with a very poor prognosis. Currently, surgery-based comprehensive management may be the only treatment able to significantly improve long-term survival. Radical resection is the first choice for pancreatic cancer patients. Unfortunately, less than 20% of patients are found to have resectable tumors at the time of diagnosis. In addition, only few people can acquire long-term survival even after radical resection because of recurrence and metastasis after surgery. Therefore, surgery-based comprehensive management, including iodine-125 seed implantation, sustained release 5-fluorouracil, argon-helium cryosurgery, radiofrequency ablation, immunotherapy, and regional intra-arterial infusion chemotherapy, may improve the survival and life quality of pancreatic cancer patients.

Cryosurgery for lung cancer

Cryosurgery is suited for patients with lung cancer who are not considered for lung resection because of the advanced stage of the disease or the patient's poor general condition or poor respiratory function and with tumor recurrence following radiotherapy, chemotherapy or lung resection, and those patients who have localized lung cancer but refuse to receive operative therapy. Procedures of cryosurgery for lung cancer can be performed through endobronchial, direct intrathoracic (at exploratory thoracotomy) or percutaneous routes depending upon location and size of tumor. Six hundred and twenty-five patients with Non-small cell lung cancer (NSCLC) received percutaneous cryoablation in Fuda Cancer Hospital Guangzhou, China. One hundred and fifty patients were followed-up for 12 to 38 months. Results showed that 1-, 2-, and 3-year survival rates were 64%, 45% and 32%, respectively. The adverse effects after cryosurgery of lung cancer include haemoptysis, pneumothorax, bloody thorax, pleural effusion and pulmonary infection which are generally mild, transient, and recovery with symptomatic management. In vitro studies have shown cryotherapy of lung cancer cells can improve the immune system to trigger the specific anti-tumor response. In the future, comparative studies between this modality and other therapies should be conducted for the treatment of lung cancer. In addition, more attention needs to be put on the immunomodulators that enhance the cryoimmunology.

Pancreatic metastases from renal cell carcinoma: the state of the art

Pancreatic metastases are rare, with a reported incidence varying from 1.6% to 11% in autopsy studies of patients with advanced malignancy. In clinical series, the frequency of pancreatic metastases ranges from 2% to 5% of all pancreatic malignant tumors. However, the pancreas is an elective site for metastases from carcinoma of the kidney and this peculiarity has been reported by several studies. The epidemiology, clinical presentation, and treatment of pancreatic metastases from renal cell carcinoma are known from single-institution case reports and literature reviews. There is currently very limited experience with the surgical resection of isolated pancreatic metastasis, and the role of surgery in the management of these patients has not been clearly defined. In fact, for many years pancreatic resections were associated with high rates of morbidity and mortality, and metastatic disease to the pancreas was considered to be a terminal-stage condition. More recently, a significant reduction in the operative risk following major pancreatic surgery has been demonstrated, thus extending the indication for these operations to patients with metastatic disease.

[Imaging and pathological features of percutaneous cryosurgery on normal lung evaluated in a porcine mode]

背景与目的

肺癌已成为最常见死因的恶性肿瘤之一，对不能手术切除的肺癌，冷冻是一种安全可选择的消融治疗手段，但肺为含气组织，与冷冻肝脏、胰腺等实体器官不同，在理论上冷冻范围很难超过肿瘤边缘。本研究旨在通过正常猪肺模型实验了解不同冷冻-复温循环对肺部组织坏死范围的影响并探讨经皮冷冻肺治疗的技术方案。

方法

采用6只平均体重为23 kg的正常西藏小型猪作为模型，在CT引导下选择猪肺上叶1点和下叶2点作为靶点，使用直径为1.7 mm的冷冻探针分别插入肺叶各靶点做经皮穿刺冷冻。左肺行冷冻10 min、复温5 min共2个周期的冷冻-复温循环；右肺先行冷冻5 min、复温5 min的2个冷冻-复温循环，然后行冷冻10 min、复温5 min的第3个冷冻-复温循环。左右肺的实验条件和实验方法均相同。实验中，观察CT影像下冰球的形态学变化。分别取冷冻后4 h、3 d和7 d的猪肺标本，观察其大体形态及其在光镜下的组织学变化。

结果

猪肺冷冻过程中随着时间的延长和循环次数的增加，冰球逐渐增大；无论2个或3个冷冻-复温循环，所产生的冷冻范围（“假定坏死区”）在大体标本上均超过CT上冷冻过程中显示的冰球大小；冷冻后随着时间延长，组织学坏死区逐步增大，3天及以后，假定坏死区即为组织学坏死区。

结论

经皮冷冻肺可以达到有效破坏靶组织的目的；在技术上，肺冷冻以3个冷冻-复温循环为佳；冷冻范围不强求冷冻“1 cm安全边缘”。上述研究结果对于简化冷冻治疗过程及减少并发症具有临床价值。

Comparison between surgery and radiofrequency ablation for stage I non-small cell lung cancer

Surgical resection remains as the treatment of choice for non-small cell lung cancer (NSCLC) and provides the best opportunity for cure and long-term survival. Minimally invasive percutaneous ablative therapies, such as radiofrequency ablation (RFA) for treating lung cancers, are currently being studied as treatment alternatives. But, to date, there is little information on comparison of therapeutic effects between surgery and RFA in patients with early stage lung malignancy. We aimed to investigate the clinical significance of RFA as an alternative curative modality for the early stage lung cancer through analyzing the long-term mortality of both treatment groups; surgery vs. RFA. Twenty-two patients of stage I NSCLC were included for this comparative analysis. To minimize confounding effects, we conducted a matching process. In which patients of RFA group (n = 8) were matched with patients of surgery group (n = 14) on the following variables; gender, age (± 3 years), tumor node metastasis stage, and calendar year of surgery or RFA (± 2 years). The mean survival duration of RFA group and surgery group were 33.18 ± 7.90 and 45.49 ± 7.21, respectively (months, p = 0.297). Log-rank analysis showed that there was no significant difference in overall survival (p = 0.054) between two groups. These results have shown that RFA can offer the survival comparable to that by surgery to stage I NSCLC patients, especially to the patients impossible for the surgery. This study provides an evidence for the use of RFA as a treatment alternative with low procedural morbidity for inoperable early-stage NSCLC patients.

Intraoperative radiofrequency ablation combined with 125iodine seed implantation for unresectable pancreatic cancer

AIM: To evaluate the feasibility, efficacy and safety of intraoperative radiofrequency ablation (RFA) combined with ¹²⁵iodine seed implantation for unresectable pancreatic cancer.

METHODS: Thirty-two patients (21 males and 11 females) at the age of 68 years (range 48-90 years) with unresectable locally advanced pancreatic cancer admitted to our hospital from January 2006 to May 2008 were enrolled in this study. The tumor, 4-12 cm in diameter, located in pancreatic head of 23 patients and in pancreatic body and tail of 9 patients, was found to be unresectable during operation. Diagnosis of pancreatic cancer was made through intraoperative biopsy. Patients were treated with FRA combined with ¹²⁵iodine seed implantation. In brief, a RFA needle was placed, which was confirmed by intraoperative ultrasound to decrease the potential injury of surrounding vital structures, a ¹²⁵iodine seed was implanted near the blood vessels and around the tumor border followed by bypass palliative procedure (cholangio-jejunostomy and/or gastrojejunostomy) in 29 patients.

RESULTS: The serum CA 19-9 level was decreased from 512 ± 86 U/mL before operation to 176 ± 64 U/mL, 108 ± 42 U/mL and 114 ± 48 U/mL, respectively, 1, 3 and 6 mo after operation (P < 0.05). The pain score on day 7 after operation, 1 and 3 mo after combined therapy was decreased from 5.86 ± 1.92 before operation to 2.65 ± 1.04, 1.65 ± 0.88 and 2.03 ± 1.16, respectively, after operation (P < 0.05). The rate of complete response (CR), partial response (PR), stable disease (SD), progressive disease (PD) in 32 patients was 21.8% (7/32), 56.3% (18/32), 15.6% (5/32) and 6.3% (2/32), respectively, 6 mo after operation, with a median overall survival time of 17. 5 mo. The median survival time of patients at stage III was longer than that of those at stage IV (19 mo vs 10 mo, P = 0.0026). The median survival time of patients who received and did not receive chemotherapy after operation was 20 mo and 16 mo, respectively (P = 0.0176). Of the 32 patients, 3 (10.6%) experienced postoperative complications including transient biliary leaks in 2 patients and acute pancreatitis in 1 patient. All the patients recovered well after conservative support treatment.

CONCLUSION: Intraoperative RFA combined with ¹²⁵iodine seed implantation is a feasible and safe procedure for unresectable pancreatic cancer with acceptable minor complications, and can prolong the survival time of patients, especially those at stage III.

Stereotactic body radiation therapy versus surgical resection for stage I non-small cell lung cancer

OBJECTIVES

Stereotactic body radiation therapy has been proposed as an alternative local treatment option for high-risk patients with early-stage lung cancer. A direct comparison of outcomes between stereotactic body radiation therapy and surgical resection has not been reported. This study compares short-term outcomes between stereotactic body radiation therapy and surgical treatment of non-small cell lung cancer.

METHODS

We compared all patients treated with surgery (January 2000-December 2006) or stereotactic body radiation therapy (February 2004-May 2007) with clinical stage IA/B non-small cell lung cancer staged by computed tomography and positron emission tomography. Comorbidity scores were recorded prospectively using the Adult Co-Morbidity Evaluation scoring system. Charts were reviewed to determine local tumor recurrence, disease-specific survival, and overall survival. A propensity score matching analysis was used to adjust estimated treatment hazard ratios for confounding effects of patient age, comorbidity index, and clinical stage.

RESULTS

A total of 462 patients underwent surgery and 76 received stereotactic body radiation therapy. Overall, surgical patients were younger (P < .001), had lower comorbidity scores (P < .001), and better pulmonary function (forced expiratory volume in 1 second and carbon monoxide diffusion in the lung) (P < .001). Among the surgical and stereotactic body radiation therapy groups, 62.6% (291/462) and 78.9% (60/76) were in clinical stage IA, respectively. Final pathology upstaged 35% (161/462) of the surgery patients. In an unmatched comparison, overall 5-year survival was 55% with surgery, and the 3-year survival was 32% with radiation therapy. Among patients with clinical stage IA disease, 3-year local tumor control was 89% with radiation therapy and 96% with surgery (P = .04). There was no difference in local tumor control in stage IB disease (P = .89). No disease-specific survival differences were found in patients with 1A (P = .33) or IB disease (P = .69). Propensity analysis matched 57 high-risk surgical patients to 57 patients undergoing stereotactic body radiation therapy. In the matched comparison of this subgroup, there was no difference in freedom from local recurrence (88% vs 90%), disease-free survival (77% vs 86%), and overall survival (54% vs 38%) at 3 years.

CONCLUSIONS

In an unmatched comparison of clinical stage IA disease, surgical patients were healthier and had better local tumor control compared with those receiving stereotactic body radiation therapy. Propensity analysis in clinical stage IA/B non-small cell lung cancer revealed similar rates of local recurrence and disease-specific survival in patients treated with surgery compared with stereotactic body radiation therapy.

Algorithm optimization for multitined radiofrequency ablation: comparative study in ex vivo and in vivo bovine liver

PURPOSE

To prospectively optimize multistep algorithms for largest available multitined radiofrequency (RF) electrode system in ex vivo and in vivo tissues, to determine best energy parameters to achieve large predictable target sizes of coagulation, and to compare these algorithms with manufacturer's recommended algorithms.

MATERIALS AND METHODS

Institutional animal care and use committee approval was obtained for the in vivo portion of this study. Ablation (n = 473) was performed in ex vivo bovine liver; final tine extension was 5-7 cm. Variables in stepped-deployment RF algorithm were interrogated and included initial current ramping to 105 degrees C (1 degrees C/0.5-5.0 sec), the number of sequential tine extensions (2-7 cm), and duration of application (4-12 minutes) for final two to three tine extensions. Optimal parameters to achieve 5-7 cm of coagulation were compared with recommended algorithms. Optimal settings for 5- and 6-cm final tine extensions were confirmed in in vivo perfused bovine liver (n = 14). Multivariate analysis of variance and/or paired t tests were used.

RESULTS

Mean RF ablation zones of 5.1 cm +/- 0.2 (standard deviation), 6.3 cm +/- 0.4, and 7 cm +/- 0.3 were achieved with 5-, 6-, and 7-cm final tine extensions in a mean of 19.5 min +/- 0.5, 27.9 min +/- 6, and 37.1 min +/- 2.3, respectively, at optimal settings. With these algorithms, size of ablation at 6- and 7-cm tine extension significantly increased from mean of 5.4 cm +/- 0.4 and 6.1 cm +/- 0.6 (manufacturer's algorithms) (P <.05, both comparisons); two recommended tine extensions were eliminated. In vivo confirmation produced mean diameter in specified time: 5.5 cm +/- 0.4 in 18.5 min +/- 0.5 (5-cm extensions) and 5.7 cm +/- 0.2 in 21.2 min +/- 0.6 (6-cm extensions).

CONCLUSION

Large zones of coagulation of 5-7 cm can be created with optimized RF algorithms that help reduce number of tine extensions compared with manufacturer's recommendations. Such algorithms are likely to facilitate the utility of these devices for RF ablation of focal tumors in clinical practice.

Feasibility and safety of radiofrequency ablation for locally advanced pancreatic cancer

BACKGROUND

: Radiofrequency ablation (RFA) may be a valuable treatment option for locally advanced pancreatic cancer. The present study examined its feasibility and safety.

METHODS

: Fifty patients with locally advanced pancreatic cancer were studied prospectively. Ultrasound-guided RFA was performed during laparotomy. The main outcome measures were short-term morbidity and mortality.

RESULTS

: The tumour was located in the pancreatic head or uncinate process in 34 patients and in the body or tail in 16; median diameter was 40 (interquartile range 30-50) mm. RFA was the only treatment in 19 patients. RFA was combined with biliary and gastric bypass in 19 patients, gastric bypass alone in eight, biliary bypass alone in three and pancreaticojejunostomy in one. The 30-day mortality rate was 2 per cent. Abdominal complications occurred in 24 per cent of patients; in half they were directly associated with RFA and treated conservatively. Three patients with surgery-related complications needed reoperation. Reduction of RFA temperature from 105 degrees C to 90 degrees C resulted in a significant reduction in complications (ten versus two of 25 patients; P = 0.028). Median postoperative hospital stay was 10 (range 7-31) days.

CONCLUSION

: RFA of locally advanced pancreatic cancer is feasible and relatively well tolerated, with a 24 per cent complication rate.

Complications of ablative therapies in lung cancer

Two cases of complications secondary to the use of microwave ablation (MWA) in non-small-cell lung cancer (NSCLC) are discussed herein. The first case involves a 62-year-old man with stage IB NSCLC who declined surgery and pursued MWA. Within 7 months, he had residual disease at the MWA treatment site, and surgery was performed. The patient was found to have pleural and chest wall involvement, making complete resection impossible. The second case involves an 86-year-old woman with a second local recurrence of NSCLC and previous treatment including surgery and chemoradiation therapy. She was initially a surgical candidate but declined surgery and pursued MWA. Within 6 months, she had residual disease at the MWA treatment site. A second MWA was performed, and she developed a large cavitary abscess at the MWA site and had subsequent clinical decline. Less invasive ablation therapies and stereotactic radiosurgery are being developed for patients with inoperable lung cancer. Because these modalities have recently been developed, trials that clearly show efficacy and survival benefit are yet to be completed. Ablation procedures can result in complications, including residual disease and cavitary lesions susceptible to infection. These cases highlight the caution that should still be observed when recommending lung ablation strategies and the importance of selecting appropriate patients.

Microwave ablation with triaxial antennas tuned for lung: results in an in vivo porcine model

PURPOSE

To prospectively determine in swine the size and shape of coagulation zones created in normal lung tissue by using small-diameter triaxial microwave antennas and to prospectively quantify the effects of bronchial occlusion and multiple antennas on the coagulation zone.

MATERIALS AND METHODS

The study was approved by the research animal care and use committee, and all husbandry and experimental studies were compliant with the National Research Council's Guide for the Care and Use of Laboratory Animals. Twenty-four coagulation zones (three per animal) were created at thoracotomy in eight female domestic swine (mean weight, 55 kg) by using a microwave ablation system with 17-gauge lung-tuned triaxial antennas. Ablations were performed for 10 minutes each by using (a) a single antenna, (b) a single antenna with bronchial occlusion, and (c) an array of three antennas powered simultaneously. The animals were sacrificed immediately after ablation. The coagulation zones were excised en bloc and sectioned into approximately 4-mm slices for measurement of size, shape, and circularity. Analysis of variance and two-sample t tests were used to identify differences between the three ablation groups.

RESULTS

The overall mean diameters of coagulation achieved with a single antenna and bronchial occlusion (4.11 cm +/- 1.09 [standard deviation]) and with multiple-antenna arrays (4.05 cm +/- 0.69) were significantly greater than the overall mean diameter achieved with a single antenna alone (3.09 cm +/- 0.83) (P = .016 for comparison with multiple antennas, P = .032 for comparison with bronchial occlusion). No significant differences in size were seen between the coagulation zones created with bronchial occlusion and those created with multiple antennas (P = .68). The coagulation zones in all groups were very circular (isoperimetric ratio > 0.80) at cross-sectional analysis.

CONCLUSION

A 17-gauge triaxial microwave ablation system tuned for lung tissue yielded large circular zones of coagulation in vivo in porcine lungs. The coagulation zones created with bronchial occlusion and multiple antennas were significantly larger than those created with one antenna.

Feasibility study on using an infrared thermometer for evaluation and administration of cryosurgery

Successful performance of cryosurgery relies heavily on a quick, efficient, safe and economic imaging way to monitor the surgical advancement and then to evaluate the curative effect. However, there is currently a lack of such an imaging modality. As for the commonly adopted imaging devices such as X-CT, MRI and PET, in addition their high cost and complexity in operation, they often induce additional scathe to the patients due to their potential radiation effects. Besides, in cryosurgery, the most important parameter - temperature - can not be directly detected by these methods. Considering the above factors, infrared thermography (IRT), a rather useful yet often neglected functional imaging technique in clinics, is proposed in this paper as an efficient tool for the quick evaluation and administration of a cryosurgical treatment of tumors. Based on skin surface temperature mapping, the degree of damage to the target tissue site caused by different freezing/heating protocols, as well as the states of blood circulation and metabolic heat generation within the treated region can possibly be identified. Further, through recording the temperature variation feature at the skin surface before and after cryosurgery, IRT would help to quickly evaluate the curative effect, which is very beneficial for later treatment planning. By detecting the surface infrared image and analyzing its digital values, the patient's invisible focus and abnormal physiological states, e.g. inflammations or pneumothorax, often accompanied by cryosurgical output yet difficult to determine via conventional imaging, could also possibly be diagnosed. To test the above concepts, both typical animal and clinical experiments were performed to demonstrate the feasibility and advantages of IRT-guided cryosurgery. This study may help push forward a novel, low-cost and non-contact way for an efficient performance of cryosurgery.

Current medical treatment of pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (NETs) consist of a wide group of neoplasms, with different biological behaviors in terms of aggressiveness and hormone production. In the last two decades, significant progress has been observed in our understanding of their biology, diagnosis and treatment. Surgery remains to be the only curative approach, but unfortunately the diagnosis is often delayed due to the slow growth of these tumors and the difficulty in identifying the symptoms related to the tumor-released hormones. In addition to surgery, other approaches to control the disease are biological therapy consisting of somatostatin analogs and interferon (IFN), systemic chemotherapy, radioligand therapy and local therapy with chemoembolization. Several newer cytotoxic agents, including irinotecan, gemcitabine, taxanes, oxaliplatin, capecitabine and PS-341 have been studied in metastatic patients. Considering the high vascularity of these tumors, antiangiogenic agents like endostatin and thalidomide have also been evaluated in advanced NETs. Although these agents seem to have potential activity in NETs and may increase progression free survival, none of these currently available medical therapeutic options are curative. While more efficient novel strategies are to be developed, the rationale use of the current therapeutic options may improve quality of life, control the symptoms related to the hypersecretion of hormones and/or peptides, control tumor proliferation and prolong survival in patients suffering from NETs.

High-power generator for radiofrequency ablation: larger electrodes and pulsing algorithms in bovine ex vivo and porcine in vivo settings

PURPOSE

To prospectively maximize the extent of tissue coagulation by using a high-power (1000-W, 4000-mA) radiofrequency (RF) generator to optimize pulsing algorithms.

MATERIALS AND METHODS

The institutional animal care and use committee approved the use of the animal model in the in vivo portion of this study. RF ablations (n = 258) were performed in ex vivo bovine livers by using a 500-kHz high-power generator. Through internally cooled 3.0-cm single and 2.5- and 4.0-cm cluster electrodes, RF energy was applied for 12 minutes. For each electrode, simplex optimization was used to determine the pulsing algorithms to be used (ie, 5-50-second "on" [energy application] and 10-50-second "off" [cooling without RF heating] periods). Three-dimensional contour maps expressing the relationship between pulsing parameters and resultant coagulation were constructed. Then, 31 RF ablations were performed with optimal settings in vivo in porcine livers, and the results were compared with those obtained in control ablations performed by using a 2000-mA commercial generator. Finally, in 108 experiments, RF energy was applied in ex vivo livers for 6, 12, and 20 minutes with maximum current settings (1000-4000 mA) by using the optimal on and off settings for all three electrodes, and the results were analyzed with multivariate analysis of variance (MANOVA).

RESULTS

For all three electrodes, a relationship between the on and off times during the pulsing cycle and the resultant coagulation was established (P < .01). With 3.0-cm single electrodes, maximum coagulation (mean, 5.2 cm +/- 0.1 [standard deviation] ex vivo and 3.6 cm +/- 0.2 in vivo) was achieved with pulse settings of 10-18 seconds on and 11-20 seconds off. With cluster electrodes, greater coagulation was achieved (mean, 6.5 cm +/- 0.6 ex vivo and 3.9 cm +/- 0.3 in vivo with 2.5-cm tip; 8.3 cm +/- 0.3 ex vivo and 5.2 cm +/- 0.8 in vivo with 4.0-cm tip) with optimal pulse settings. Thus, use of the high-power generator yielded substantially increased tissue coagulation in vivo compared with the coagulation achieved with the standard generator. MANOVA revealed that increased maximum current and RF ablation durations of up to 20 minutes were associated with greater coagulation, the size of which also varied according to electrode type (P < .01).

CONCLUSION

Markedly larger coagulation zones can be achieved with optimized high-power RF ablation. This may require longer pulsing intervals compared with those previously used.