Endocare型氩氦冷刀冻结与复温性能的实验研究

目的：对Endocare型氩氦冷刀的实际工作性能进行测试，考察其优缺点，为肿瘤冷冻治疗提供参考。方法：将氩氦刀置于空气、水及哆子组织中进行冷冻并复温，监测刀杆外壁和内部测温点的温度变化；基于实验结果评价氩氦刀的工作性能以及工质气体的消耗情况；结果：氩氦刀冷冻时，刀头在很短的时间内降至极低温度，并保持稳定。冰球在冷冻初期增长很快，此后其增长速率明显下降。当工质由氩切换为氦后，刀头温度迅速上升，冰球随即熔化；工质气体的消耗速率随着实验进行不断降低。结论：证实氩氦刀确有良好的快速冷冻和复温性能，但同时也存在问题和不足。     

氩氦刀冷冻消融时间与冰球大小关系的实验研究

目的研究氩氦刀冷冻时间与冰球大小的关系,为临床确定最佳冷冻时间及冷冻靶区设计提供理论依据.方法离体猪肝在37℃恒温液中接受氩氦刀冷冻,分别即时测量2、3 mm氩氦刀冷冻以及两把3 mm氩氦刀间距30 mm冷冻不同时间点时形成冰球长径与横径,进行统计分析.结果直径2 mm刀最大冰球体积分别可达(71×50×50)mm3,直径3 mm刀最大冰球体积(75×56×56)mm3;2把直径3 mm以及3把直径3 mm的氩氦刀组合冷冻时,最大冰球范围分别可达(90×80×56)mm3和(105×100×80)mm3大小.无论哪种方式冷冻,在30 min以内冰球纵径和横径增加明显(P＜0.05),30 min以后冰球体积无明显增长(P＞0.05).结论 氩氦冷冻肿瘤时,靶区消融疗效确切,一般冷冻时间选择在25～30 min较为适宜.     

CT引导配合氩氦刀治疗肺癌的应用

目的 探讨CT引导在氩氦刀治疗肺癌中的正确应用.方法 对无手术适应证的晚期肺癌患者,在CT引导下准确定位,经皮穿刺行氩氦刀冷冻治疗.结果 本组22例肺癌患者均在CT引导下完成氩氦刀冷冻治疗,共26处病灶;其中17处完全被冰球覆盖,9处病灶冰球覆盖80%以上.近期总有效率达100%.术后测量冷冻区的CT值较术前平均下降35～55 Hu.结论 应用CT影像引导氩氦刀治疗可准确确定肿瘤部位及与周围组织的关系,方便选定进针角度和深度,使手术过程简化、安全.术后可实时观察冰球的大小,判断治疗效果.     

氩氦刀冷冻治疗肺癌的CT影像学分析

目的:分析氩氦刀靶向治疗肺癌的CT影像学征象及临床意义。方法:选择16例肺部肿瘤患者,在CT引导下,应用氩氦刀微创、靶向冷冻治疗,并分析其影像学表现特点。结果:氩氦刀冷冻形成的冰球能达到覆盖病灶体积的90%~100%,术前、术中和术后有不同的CT影像学表现。治疗后1~3月复查CT,肿块均有较大程度的缩小或消失。结论:CT影像学表现能够直接客观地评价氩氦刀治疗肺部肿瘤的临床意义及预后。     

氩氦靶向治疗对肺癌细胞的灭活作用

目的 研究体内、外氩氦靶向治疗对肺癌细胞的灭活作用。方法 观察氩氦刀对体外培养的肺癌细胞、实验动物及肺癌患者，治疗前后温度响应曲线、病理等方面的变化。结果 体外实验发现氩氦刀在空气及水中均有快速降温及升温作用，在水中能快速形成冰球及融化冰球。氩氦刀对体外培养的肺癌细胞有明显的破坏作用，在人体中也证实能灭活肺癌细胞，在1个月内，肿瘤细胞呈凝固性坏死，在3个月后则被纤维组织代替。动物实验可见，氩氦刀在肌肉组织中快速形成冰球。结论 氩氦刀有快速升、降温作用，体内、外均能灭活肺癌细胞。     

低温冷冻介入疗法治肝癌获成功

最近,第四军医大学西京医院肝胆外科采用超低温冷冻介入方法治疗肝癌获得成功。其方法是:用直径２毫米的超导刀插入肿瘤部位,输出高压常温氩气或高压常温氦气,通过计算机系统监控刀尖部位温度。氩气在刀尖急速膨胀,在６０秒内冷冻病变组织至-１４０℃,使肿瘤变成一个冰球,彻底杀死癌细胞。此法治疗肝癌的优点是:基本不出血,无痛苦,手术时间仅３０分钟,术后３天患者即可出院。另外,由于氩氦刀杆有很好的热绝缘,不会对穿刺路径上的组织产生损伤,而且形成冰球的大小可以精确设定,因此不会损伤正常肝组织。此法不仅能治疗早期肝癌、中晚期肝癌,…     

CT导向氩氦刀冷冻治疗26例肝癌疗效探讨

目的:探讨氩氦刀冷冻治疗肝癌的疗效价值.方法:对26例肝癌在CT引导下使用氩氦超导手术系统反复冷冻升温,使其肿瘤组织坏死.结果:26例肝癌患者中,冷冻率达50%以上,1个月后CT复查,肿瘤坏死率达到42%～64%.结论:氩氦刀冷冻治疗是目前治疗肝癌的有效方法之一.     

TACE联合氩氦刀冷冻消融术治疗原发性肝癌后血小板变化观察

目的 :探讨TACE序贯氩氦刀冷冻消融术治疗中晚期原发性肝细胞癌后血小板的变化规律。方法:47例原发性肝癌患者均先行经典TACE术,术后2~4周内行氩氦冷冻消融术(冷冻时间30 min)。总结术前、术后血小板变化规律。结果:TACE术后1周血小板呈一过性轻度下降。氩氦刀术前与术后1周内血小板呈先迅速下降后快速恢复的过程。结论:肝癌行氩氦刀冷冻肿瘤消融术后导致血小板减少与冷冻时间、冷冻针数量及肝功能损害密切相关。     

氩氦刀治疗肺癌出现冷休克1例

氩氦刀(Ar-He cryotherapy)是肿瘤治疗方面近年来一种相当有效的新的微创性物理疗法.其原理就是通过介入人体微控针的冷冻来促使病灶组织快速降温、冷冻及融化,产生不可逆损伤,从而达到清除病灶的目的.我院行氩氦刀治疗肺部肿瘤数已累计600余例,且近期疗效满意.氩氦刀手术术中或术后可出现伤口疼痛、咯血、气胸、发热等并发症,但冷休克极少发生,我院自行此项手术来尚属首例,现报道应用氩氦刀冷冻治疗肺癌出现冷休克1例.     

氩氦刀治疗中晚期肝肿瘤

目的探讨氩氦刀靶向冷冻综合治疗中晚期肝肿瘤的疗效。方法72例中晚期肝肿瘤,采用B超或计算机体层摄影术引导经皮穿刺肝肿瘤氩氦靶向冷冻消融术。共计对117个病灶使用203把氩氦刀2次循环冷冻。结果氩氦超导低温靶向定位对肝肿瘤穿刺准确。冷冻术后有90．3％（65／72）的患者精神状态得到改善,腹部疼痛症状减轻,恢复快。应用18F-氟脱氧葡萄糖扫描显示肿瘤局部放射性浓聚影明显降低。计算机体层摄影术影像上可见肿瘤区域内有空泡样破坏,边界清楚,计算机体层摄影术值较冷冻前低。结论氩氦刀加综合治疗肝癌疗效明确,对正常肝组织损伤少,安全、有效、微创,为已丧失手术机会的晚期肝肿瘤患者开辟了一条新的治疗途径。但应强调的是氩氦刀仅仅是一种局部物理冷冻技术,应该结合化疗、放疗、生物治疗等综合措施。     

MR-guided interstitial cryotherapy of the liver with a novel,nitrogen-cooled cryoprobe

The purpose of the study was to test a newly developed, MR-compatible, liquid nitrogen-cooled cryoprobe. The probe has an outer diameter of 3.5 mm and was specifically developed for percutaneous, MR-guided, interstitial cryotherapy. The probe was inserted percutaneously into the livers of 10 rabbits. The cryotherapy procedure was monitored with a surface coil in a 1.5 Tesla magnet using a gradient echo sequence. Follow-up examinations were performed 3 and 7 days after the freezing procedure using T₁- and T₂-weighted spin echo sequences. At 7 days the animals were sacrificed and the cryolesions were examined histologically. The cryoprobe enabled artifact-free MR imaging of the “ice-ball” formation during freezing of the rabbit liver. After 1 min of freezing, the iceball at the tip of the probe showed an average maximum diameter of 10.8 mm. No bleeding complications were observed during or after the freezing procedure. Histologic examination 7 days after cryotherapy confirmed that the liver lesions were the same size as had been predicted by the images of the acute iceball. This new, percutaneously inserted, MR-compatible, liquid-nitrogen cooled cryoprobe allows accurate, artifact-free MR imaging of interstitial cryotherapy.     

MR导向冷冻消融猪肾脏的动态影像学研究

目的:评价冷冻消融对猪肾实质、肾脏微循环、集合系统的影响,为临床冷冻消融肾脏肿瘤的可行性及安全性提供实验理论依据。方法:五指山小型实验猪实验组6头,ipath200光学系统导引下1.47mm氩氦冷冻探针植入集合系统周围,冻融两个循环;对照组2头,仅行穿刺。术中动态监测冰球形成情况。术后1天、14天、30天分别行1.5T高场磁共振检查。结果:实验猪均穿刺并冷冻消融成功。冷冻10min,冰球最大并大部分位于靶组织内,显示为椭圆形极低信号影。术后1.5TMR显示靶区组织T1WI、T2WI均呈低信号伴周围不连续的斑片状高信号出血带。周围可见水肿信号。注入GD-DTPA后,冷冻中心无明显强化,周边见均匀强化环。结论:MR导向穿刺准确率高,未发现继发于冷冻的集合系统损伤,对于小肾癌、局限性的累及集合系统的肾肿瘤安全可行。     

Improved slice selection for R2* mapping during cryoablation with eddy current compensation

PURPOSE: To improve the slice profile and image quality of R2* mapping in the iceball during cryoablation with ultrashort echo time (UTE) imaging by compensating for eddy currents induced by the selective gradient when half-pulse radiofrequency (RF) excitation is employed to achieve UTEs. MATERIALS AND METHODS: A method to measure both B0 and linear eddy currents simultaneously is first presented. This is done with a least-square fitting process on calibration data collected on a phantom. Eddy currents during excitation are compensated by redesigning the RF pulse and the selective gradient accordingly, while that resultant from the readout gradient are compensated for during image reconstruction. In vivo data were obtained continuously during the cryoablation experiments to calculate the R2* values in the iceball and to correlate them with the freezing process. RESULTS: Image quality degradation due to eddy currents is significantly reduced with the proposed approaches. R2* maps of iceball throughout the cryoablation experiments were achieved with improved quality. CONCLUSION: The proposed approaches are effective for compensating eddy currents during half-pulse RF excitation as well as readout. TEs as short as 100 microsec were obtained, allowing R2* maps to be obtained from frozen tissues with improved quality.     

低温手术过程多维传热有限元分析

目的 通过有限元分析，给出低温手术过程组织三维瞬态温度场；考察人体血液灌注和代谢产热对其影响，为优化设计冷刀提供参考。方法 充分考虑组织物性和内热源的非线性，使用基于有限容积法的大型商业有限元软件Ansys求解描述低温手术过程组织传热问题的经典生物传热方程。结果 考虑血液灌注和代谢产热后，组织局部降／复温速率降低、所经历的最低温度绝对数值减少；对应时刻，组织内局部温度梯度增加；相同手术方案下，组织内冻结区域减小，且冰球生长过程减慢。结论 人体血液灌注和代谢产热对低温手术过程影响显著，体外实验由于无法模拟血液灌注和代谢产热效果而对冷刀的优化设计作用有限，必须进行在体实验以优化冷刀及其相应的低温手术方案。     

Initial experience of percutaneous renal cryosurgery under the guidance of a horizontal open MRI system

OBJECTIVE: The aim of this study was to obtain preliminary results of cryoablation of renal tumors by using a percutaneous approach guided by a horizontal open MRI system, and to assess the safety and efficacy of this procedure. MATERIALS AND METHODS: Four patients with renal tumors underwent percutaneous cryosurgery with local anesthesia using a horizontal open MRI system (AIRIS II, Hitachi Medical Corp., Tokyo, Japan). The size of the mass was radiographically documented as 4 cm or less in diameter. A 2- or 3-mm cryoprobe was advanced into the renal mass under real-time MR monitoring. Growth of the iceball during cryoablation was monitored by two-dimensional MR images. Follow-up dynamic CT and physical examination were done after two weeks and six weeks. RESULT: MR imaging demonstrated the iceballs as sharply marginated regions of signal loss that expanded and engulfed the renal mass with clear contrast between the iceball and surrounding tissue. Cryoablated tumors resolved, and there were no serious complications and no clinically significant changes during the procedures and follow-up study. CONCLUSION: In this limited clinical trial of percutaneous renal tumor surgery, cryoablation demonstrated its feasibility with minimal morbidity. Intraprocedual MR-guided cryosurgery can be used as a safe modality, although further studies are necessary to determine the long-term efficacy of this procedure.     

Treatment of frostbite with i.v. streptokinase: an experimental study in rabbits

Experiments were conducted in 32 rabbits to determine whether treatment with IV streptokinase can effectively limit the extent of tissue damage associated with frostbite injury of the hind limbs. Other variables studied were the temperature of the tissue during freezing, the time taken to rewarm the exposed limbs, and the delay between the initiation of treatment with streptokinase and cessation of freezing. A control group of 16 rabbits was not given streptokinase. The extent of tissue damage was estimated by sequential radionuclide perfusion scans of the exposed limbs. This estimate was based on the proportional loss of tissue perfusion on subsequent twice-weekly nuclear scans in comparison with that shown by scans performed immediately after thawing. Pathologic changes in exposed tissues were studied by histology. Streptokinase treatment and rapid rewarming both resulted in less tissue damage at all freezing temperatures. Streptokinase was most beneficial when given 12 hr after freezing, but was effective even when treatment was delayed up to 48 hr.     

肝门区域低温冷冻的实验效应

为深入研究低温对肝门区域组织及Glisson管道的影响。将16只小猪随机分为2组，用冷冻头对实验组第一肝门部进行3min的深低温冷冻，对照组仅阻断肝门3min。术后通过血清学、核素扫描、彩色多谱勒和病理学等反映肝 组织及管道系统变化。结果显示，动物肝门部的胆管系统在冷冻后出现严重损伤，表现为 进行性、不可逆的胆管坏死、狭窄、胆瘘及化脓性胆管炎等并发症，肝门部较大坏死物质也会对门静脉造成 压迫。提示如对第一肝门部进行直接深低温冷冻，应注意保护胆管系统。     

Percutaneous local ablation of unifocal subclinical breast cancer: clinical experience and preliminary results of cryotherapy

Objectives

To assess the ablative effectiveness, the oncological and cosmetic efficacy of image-guided percutaneous cryoablation in the treatment of single breast nodules with subclinical dimensions after identification with ultrasonography (US), mammography, magnetic resonance (MRI) and characterization by vacuum assisted biopsy.

Materials

Fifteen women with a mean age of 73?±?5?years (range 64?C82?years) and lesion diameter of 8?±?4?mm were undergoing cryotherapy technology with a single probe under US-guidance associated with intra-procedural lymph-node mapping and excision of the sentinel node. All the patients underwent surgical resection (lumpectomy) from 30 to 45?days after the percutaneous ablation.

Results

The iceball size generated by the cryoprobe during the procedure at minus 40°C was 16?×?41?mm. In 14 of the 15 patients was observed a complete necrosis of the cryo-ablated lesion both in post-procedural MRI follow-up and anatomo-pathological evaluation after surgical resection. In one case there was a residual disease in post-procedural MRI and postoperative histological examination, probably justified by an incorrect positioning of the probe.

Conclusion

The percutaneous cryoablation as a ??minimally invasive?? technique can provide excellent oncological and cosmetic results on selected cases handled by experienced operators by using the tested devices.     

Mr image-guided control of cryosurgery

Cryoablation has recently become a useful procedure for the treatment of prostatic and hepatic tumors, primarily because of advances in the ability to monitor visually the freezing process with ultrasound. Success of the procedure depends in large part on how well the ice front can be positioned to destroy pathologic tissue, while sparing healthy tissue. This study describes a cryogen delivery system that can be used in conjunction with magnetic resonance (MR) image-guided cryoablation, and an automatic control system that uses MR image guidance in a feedback loop to control the ice front trajectory. Edge-detected MR images are used to determine the current ice front location at each time interval, providing feedback to an automatic control system that adjusts the flow of cryogen to the cryoprobe. Numerical simulations and experimental results demonstrate that an ice front with cylindrical symmetry can be accurately controlled using this MR image-guided feedback control scheme.