侧卧式X线立体定位术在乳腺微钙化病灶中的临床研究

目的：探讨侧卧位术前X线导丝定位技术对乳腺微钙化病灶的应用价值。方法：选取120例乳腺微钙化病灶,随机分为侧卧式研究组及坐式对比组进行术前导丝立体定位,留置导丝引导外科手术进行切取活检。结果：两种不同定位方式中,针尖与病灶的距离、定位中不良反应及定位成功率方面有显著差异性（P＜0．01）;在切检成功率方面两者无显著差异性（P＞0．05）。结论：侧卧式X线立体定位导丝引导下切取活检是提高乳腺微钙化病灶诊断率的有效方法。     

数字化断层融合(DBT)与全视野数字X线摄影(FFDM)引导乳腺病灶定位对比

【摘要】目的:比较数字化断层融合（DBT）及全视野数字X线摄影（FFDM）引导乳腺病灶定位的异同。方法:回顾性搜集DBT引导乳腺病灶定位患者55例,FFDM引导定位患者65例。两种成像方式引导分别计算病灶中心三维坐标,通过乳腺定位针对病灶定位。当定位针针尖与病灶中心距离≤2cm时认为定位满意。应用独立样本t检验对两种方式定位满意率、定位时间、病灶穿刺时间及患者所接受辐射剂量进行比较。结果：DBT引导病灶定位满意率55/58,高于FFDM满意率67/73;定位时间对比上DBT要低于FFDM（609.14s vs 760.25s,P<0.05）;DBT病灶穿刺时间294.09s,低于FFDM 482.58s（P<0.05）;患者DBT引导比FFDM接受更少辐射剂量（9.13 vs 13.67mGy,P<0.05）。两种成像方式对恶性病灶定位满意率均高于良性病灶（DBT：26/27 vs 29/31;FFDM：26/27 vs 41/46）。而恶性病灶定位时间、穿刺时间则低于良性病灶。结论：相比于FFDM引导乳腺病灶定位,DBT能提供准确病灶深度信息,病灶定位满意率更高、定位时间及辐射剂量更少。     

立体定位导丝导向活检不能触及的乳腺病灶

目的 探讨立体定位导丝导向活检不能触及的乳腺病灶的价值。方法 对25例不能触及的乳腺病灶行立体定位导丝导向活检26处,对每处病灶计算出穿刺针针尖至病灶中心的距离（D）,并直接测量出留置的导丝头端至病灶中心的距离作对照,判断标准：优：D小于等于2．5mm;良：D＝2．6－4．9mm;差：D大于等于5．0mm。结果 定位优20例次,良5例次,差1例次。穿刺针针尖至病灶中心距离的计算值与直接测量值相符,1次性病灶切除26例次,标本体积的中位数为10．5cm3,检出乳腺癌6（6／26）处;结论 立体定位导丝导向活检不能触及的乳腺病灶能以最小的手术范围完整切除病灶,定位定性效果确切,可避免假阴性,提高了乳腺癌的早期检出率及诊断准确性。     

数字化乳腺X线立体穿刺定位摄影技术在病灶切除术中的应用

目的:探讨全数字化乳腺X线引导术前病灶立体定位穿刺摄影技术的操作方法及临床应用价值。方法:对20例临床触诊阴性或疑似触及小肿块,而乳腺摄影有异常的患者,行数字化乳腺X线引导下术前病灶立体穿刺定位,病灶内留置导丝指导临床手术切除病灶。结果:20例患者,穿刺成功18例,2例失败。成功率达90%。病理诊断结果:4例纤维瘤伴乳腺增生;8例为乳腺腺体增生和钙化灶,部分增生活跃;2例为导管内癌,3例为浸润性乳腺癌Ⅰ期;1例原位癌。结论:全数字化乳腺X线引导下术前病灶立体定位穿刺摄影技术方便、快捷、定位准确率高,为临床上不可扪及乳腺病灶手术提供了有效的影像信息,达到了手术病灶切除范围更精确、组织损伤更小;病理诊断更准确。     

乳腺X线立体定位与超声“萤火虫”技术检查乳腺微钙化灶临床分析

目的探讨乳腺X线三维立体定位技术与超声"萤火虫"技术在乳腺微钙化病灶定位中的价值。方法选择我院120例伴乳腺微钙化灶的乳腺疾病患者为观察对象,均为乳腺X线诊断4A类以上,需要手术的患者。将这些患者随机分成两组,每组60例,A组进行乳腺X线三维立体穿刺定位,B组应用超声"萤火虫"技术进行体表定位,分析记录影像科医生对标本的影像学评分,再请病理科医生观察标本切缘干净程度,评分并记录。再将两组评分结果进行比对分析,分析上述两种定位方法的符合率。结果影像学分析乳腺X线三维立体定位技术对钙化灶定位的准确性81.6%。超声"萤火虫"技术对微钙化灶体表定位的准确性78.3%。病理学分析乳腺X线三维立体定位技术对钙化灶定位的准确性80.0%。超声"萤火虫"技术对微钙化灶体表定位的准确性75.0%。将影像学对标本分析结果与病理科医生对标本分析结果对比,符合率分别为96.6%,93.3%。结论经过影像学和病理学双重对比,乳腺X线三维立体定位技术对钙化灶定位的准确性略高于超声"萤火虫"体表定位技术,但两者之间符合率无明显统计学差异。     

X线立体穿刺钩针定位在乳腺微小病变中的应用

目的:探讨X线立体穿刺钩针定位对不可触及乳腺微小病变的诊断价值.方法:回顾分析87例乳腺钼靶X线立体穿刺钩针定位病例,均为临床触诊阴性而乳腺钼靶X线片显示有微小病变,采用钩针定位后,留置导丝于定位区,引导手术将病灶切除活检.结果:83位患者,乳腺X线检查发现病灶87例,导丝引导下手术活检均一次性成功定位与切除,定性诊断正确率为100%.病理检查结果:恶性病变8例,良性病变79例.结论:X线立体穿刺钩针定位简单易行,在乳腺微小病变的诊断中起着重要的作用.     

乳腺X线立体定位细针活检的操作体会

目的：探讨乳腺X线立体定位细针活检（SNLB）的操作技术和注意事项。方法：回顾性总结分析对46例患者行SNLB检查的步骤、方法。结果：46例患者中，恶性病变24例。良性病变22例。数字立体定位细针活检钢丝放置精确率达83.3％,外科手术后标本摄片示病灶和钢丝已切除。半年后复查片中显示术前片病灶消失。46例定位患者术后未发生感染。结论：乳腺X线立体定位细针活检中正确和精细的操作是不可触及乳腺病灶准确定位、定性诊断的先决条件。     

耳-床线定位在射频治疗三叉神经痛中的临床应用研究

目的:验证以耳—床线为基线定位在射频治疗三叉神经痛卵圆孔穿刺的临床实用价值。方法:验证性资料16例。在穿刺侧向上、X线球管向头侧倾斜20°角度摄取的头颅侧位片上勾画出耳—床线,通过观察耳—床线与射频针之间的关系及测量耳—床线与射频针尖的距离进行穿刺定位。结果:16例穿刺均成功,定位准确,疗效满意;穿刺针与耳—床线基本成垂直关系(肉眼所见),穿刺针与耳—床线之间距离最小6mm,最大10mm,平均8.06mm。结论:我们在X线解剖研究的基础上确立了耳—床线这一基线,并提出采用观察穿刺针与耳—床线的关系以及测量穿刺针针尖与耳—床线之间的距离来进行射频治疗时的定位方法,是一种简便、客观、实用可行的定位方法。     

低剂量乳腺X线摄影在触诊阴性乳腺钙化病灶导丝定位中的应用

【摘要】目的：探讨低剂量乳腺X线摄影在触诊阴性乳腺钙化病灶导丝定位中的初步应用。方法：20例临床触诊阴性但乳腺X线摄影检查发现钙化病灶并进行导丝定位的病例纳入研究并等分为低剂量组和STD组。低剂量组在导丝定位过程中首次曝光采用AOP模式下的STD模式,记录kV,mAs,然后将曝光模式改为手动模式,将mAs值下降50%左右。STD组采用全程STD模式自动曝光。将低剂量组与STD组进行定位满意度对照（针尖到病灶中心距离≤2cm为定位满意）,比较其定位满意度。比较两组患者的平均AGD和ESD值的差异。结果： 10例低剂量组均成功定位,与STD组的定位满意度无统计学差异（P=0.686>0.05）。低剂量组与STD组的平均AGD和ESD值有统计学差异(P=0.005<0.05)。结论：采用降低曝光量的方式对导丝定位中的钙化病灶进行低剂量摄影不影响定位结果,有效降低辐射剂量。     

自适应图像接收线圈应用于仰卧位乳腺磁共振成像研究

【摘要】目的：本文探讨了自适应图像接收（AIR）线圈在仰卧位乳腺磁共振成像的可行性。方法：纳入53例乳腺磁共振检查的患者作为研究对象,仰卧位检查时采用AIR线圈,与常规俯卧位乳腺线圈成像进行图像质量对比,包括图像信噪比（SNR）、对比噪声比（CNR）、对比度、图像伪影、清晰度和整体评分。同时,对不同体位图像病灶显示能力进行评估,对比不同体位图像病灶SNR、CNR、病灶边缘清晰度;并比较病灶的最大长径、病灶距乳头和胸骨中点的距离。结果：仰卧位T2WI图像的对比度高于俯卧位（0.59±0.02 vs. 0.54±0.01）,DWI图像脂肪SNR高于俯卧位（12.08±2.95 vs. 9.31±0.91,T2WI图像病灶的SNR大于俯卧位（120.41±31.86 vs. 34.25±4.60）,且仰卧位病灶距离胸骨中点的距离大于俯卧位（113.99±2.03 vs. 86.64±2.14）,差异有统计学意义（P<0.05）。仰卧位图像在伪影、清晰度和整体评分与俯卧位无统计学差别。病灶边缘的显示两种体位无差别。结论：采用AIR线圈的仰卧位乳腺磁共振成像与常规俯卧位图像质量、病灶的评估效能大致相仿,值得推广。     

MRI‐guided vacuum‐assisted breast biopsy: A phantom and patient evaluation of targeting accuracy

Purpose

To determine the spatial localization errors of magnetic resonance imaging (MRI)‐guided core biopsy for breast lesions using the handheld vacuum‐assisted core biopsy device in phantoms and patients.

Materials and Methods

Biopsies were done using a 10‐gauge handheld vacuum‐assisted core biopsy system (Vacora, Bard, AZ, USA) on a 1.5T MRI scanner (Philips Achieva, Best, The Netherlands). A standardized biopsy localization protocol was followed by trained operators for multiplanar planning of the biopsy on a separate workstation. Biopsy localization errors were determined as the distance from needle tip to center of the target in three dimensions.

Results

Twenty MRI‐guided biopsies of phantoms were performed by three different operators. The biopsy target mean size was 6.8 ± 0.6 mm. The overall mean three‐dimensional (3D) biopsy targeting error was 4.4 ± 2.9 mm. Thirty‐two MRI breast biopsies performed in 22 patients were reviewed. The lesion mean size was 10.5 ± 9.4 mm. The overall mean 3D localization error was 5.7 ± 3.0 mm. No significant differences between phantom and patients biopsy errors were found (P > 0.5).

Conclusion

MRI‐guided handheld vacuum‐assisted core biopsy device shows good targeting accuracy and should allow localization of lesions to within ～5 to 6 mm. J. Magn. Reson. Imaging 2009;30:424–429. © 2009 Wiley‐Liss, Inc.     

核磁图像上后交叉韧带止点位置的测量及临床应用

目的:在核磁共振图像(MRI)上观察和测量后交叉韧带(PCL)止点位置,为PCL重建骨道定位和术后骨道评估提供帮助。方法:选择102例PCL完整的患者,在MRI的SE T1WI序列矢状位图像上,分别测量PCL股骨和胫骨的止点位置和大小,以及胫骨止点中点到胫骨平台的垂直距离。利用术前MRI测量结果指导12例PCL断裂患者重建术中的骨道定位,术后利用CT评估骨道位置。结果:PCL股骨止点位于Blumensaat线的前下二分之一,止点长度为(11.08±1.51)mm,占Blumensaat线的37.55%;胫骨止点位于胫骨斜坡的后下二分之一,止点长度为(12.37±1.98)mm,占斜坡长度的44.48%。从胫骨止点中心点到胫骨平台最高点的垂直距离为(15.21±2.203)mm。利用术前测量结果指导术中骨道定位和术后骨道位置评估,骨道位置正确。结论:术前MRI测量结果,可以指导术中骨道定位,帮助术后骨道位置的评估。     

三种固定方式治疗胫骨平台后外侧1/2骨折的生物力学分析

目的通过尸体标本及有限元模型对前侧拉力螺钉固定、外侧L型钢板固定和后侧T型钢板固定治疗胫骨平台后外侧1/2骨折行生物力学分析,为临床工作提供基础数据。方法选取上海交通大学医学院解剖教研室提供的新鲜成人尸体胫骨标本24个,用电动摆锯制备胫骨平台后外侧1/2骨折模型,将模型随机等分为前侧拉力螺钉固定组、外侧L型钢板固定组及后侧T型钢板固定组各8具。另选取1名健康男性志愿者,对其膝关节行螺旋CT后将数据导入Mimics14.0等软件后得到三维胫骨平台实体,经分割等操作后获得胫骨平台后外侧1/2骨折模型,而后结合三维解剖数据,通过Solidworks2013软件制作相应的拉力螺钉及钢板,模拟前侧拉力螺钉固定、外侧L型钢板固定及后侧T型钢板固定三种胫骨平台后外侧1/2骨折内固定有限元模型。对各骨折内固定实体标本和有限元模型分别施加250、500、1000、1500N的轴向载荷,比较各组骨折块移位及受力情况。结果实验生物力学结果表明,250N、500N和1000N载荷下前侧拉力螺钉固定组、外侧L型钢板固定组及后侧T型钢板固定组内固定实体标本骨折块移位值[250N:(0.14±0.02)mm vs.(0.13±0.02)mm vs.(0.14±0.13)mm;500N:(0.27±0.05)mm vs.(0.29±0.06)mm vs.(0.28±0.07)mm;1000N:(0.49±0.12)mm vs.(0.53±0.10)mm vs(0.50±0.09)mm],差异均无统计学意义(P0.05),1500N载荷下前侧拉力螺钉固定组骨折块位移值(0.57±0.14mm)小于外侧L型钢板固定组(0.72±0.10mm)和后侧T型钢板固定组(0.76±0.13mm),差异均有统计学意义(P0.05),外侧L型钢板固定组和后侧T型钢板固定组骨折块位移值差异无统计学意义(P0.05)。有限元分析结果表明,在各载荷下前侧拉力螺钉固定模型的骨折块位移值及内固定最大应力均小于外侧L型钢板固定模型和后侧T型钢板固定模型。两种实验方法所得最大位移值分布区域均为近侧胫腓关节交界区。结论对于胫骨平台后外侧1/2骨折,前侧拉力螺钉固定、外侧L型钢板固定和后侧T型钢板固定均可提供早期稳定性,其中前侧拉力螺钉固定在稳定性方面最具优势,应作为临床首选方案。     

乳腺X线立体定位穿刺活检术在NPBL中的应用

目的：探究乳腺X线立体定位穿刺活检技术及其在诊断临床不可触及的乳腺病变(nonpalpable breast lesion，NPBL)上的应用。方法：对29个NPBL进行SCNB检查，并与手术病理对照，分析SCNB技术的操作方法。结果：对29个乳腺病变的检查，诊断符合率为86．2％，无假阳性。结论：本技术对应用取材部位的深度由电子计算机指导完成，定位准确，操作简单，安全可靠。熟练掌握SCNB技术，可望提高早期癌的诊断水平。     

Arthroscopically assisted retrograde drilling for osteochondritis dissecans (OCD) lesions of the knee

Purpose

Accurate retrograde drilling for osteochondritis dissecans lesions remains technically challenging. A novel, radiation-free method using an electromagnetic guidance system was developed, and its feasibility and accuracy for retrograde drilling procedures evaluated in an experimental setting.

Methods

Sixteen arthroscopically assisted, electromagnetically guided retrograde drilling procedures were performed in 4 human cadaveric knee joints. Therefore, two artificial cartilage lesions were set consecutively on each condyle. Final drill bit position was documented in two planes using fluoroscopy. Subsequently, drilling accuracy was measured in terms of distance from the final position of the drill bit to the articular cartilage surface (D1), and distance between the tip of the drill bit to the centre of the cartilage lesion on the articular cartilage surface (D2). All procedures were timed using a stopwatch.

Results

Successful retrograde drilling was accomplished in all 16 cases. The overall mean time for the retrograde drilling procedures was 361.6?±?34.7?s. Mean D1 was 2.2?±?0.5?mm; mean D2 was 0.8?±?0.7?mm. No complications occurred.

Conclusions

The novel electromagnetic guidance system used in this study showed accurate targeting results, required no radiation, was associated with no complications and demonstrated user-friendliness.

Level of evidence

II.     

前交叉韧带股骨后外束足迹解剖变异与双束重建骨道定位的对策

目的:研究前交叉韧带(ACL)股骨侧后外侧束(PLB)在股骨足迹的解剖变异范围、参考标记和关节镜下定位方法。方法:采用30侧人膝关节标本,解剖ACL的PLB在股骨髁间窝外侧壁(Lateral Intercondylar Wall,LIW)的足迹。观察髁间窝外侧壁的形态、住院医师脊(Resident Ridge)与ACL足迹关系、测量ACL长轴与股骨干夹角(AA)、PLB中心距离髁间窝外侧壁下缘软骨的垂直高度(PD)。采用数字影像学方法对足迹进行图像分析。结果:(1)住院医师脊为ACL足迹的上界(屈膝90°),紧靠住院医师脊下方为ACL纤维最集中的部位。(2)AA=18.7±15.25°,范围在-18°与56°之间;PD=7.02±1.47mm,范围在11 mm与3.75 mm之间,二者组数据离散程度均较大。(3)髁间窝外侧壁有2种类型,梯形8侧,三角形22侧,两种髁ACL的AA、PD均有明显差异(P=0.00)。结论:(1)AA、PD因人而异,数值差异较大,必须在术中测量进行个体化PLB定位。(2)虽然由于个体化的解剖变异,关节镜下难以采用通用的指引,但新鲜损伤,可根据明确的残端足迹术中定位;陈旧损伤住院医师脊可见时,PLB中心位置可参考在住院医师脊下方、前内束骨道前方予以定位;另外,3D-CT显示的髁间窝外侧壁形态也可以作为参考,梯形者PLB中心点较高、AA角较平,三角形者PLB中心点较低、AA角较倾斜。(3)如陈旧损伤住院医师脊无法辨认,难以明确PLB高度和AA角,建议进行双束个体化原位解剖重建时需谨慎。     

Phantom and Animal Study of a Robot-Assisted,CT-Guided Targeting System using Image-Only Navigation for Stereotactic Needle Insertion without Positional Sensors

PurposeTo evaluate the feasibility and accuracy of a robotic system to integrate and map computed tomography (CT) and robotic coordinates, followed by automatic trajectory execution by a robotic arm. The system was hypothesized to achieve a targeting error of <5 mm without significant influence from variations in angulation or depth.Materials and MethodsAn experimental study was conducted using a robotic system (Automated Needle Targeting device for CT [ANT-C]) for needle insertions into a phantom model on both moving patient table and moving gantry CT scanners. Eight spherical markers were registered as targets for 90 insertions at different trajectories. After a single ANT-C registration, the closed-loop software targeted multiple markers via the insertion of robotically aligned 18-gauge needles. Accuracy (distance from the needle tip to the target) was assessed by postinsertion CT scans. Similar procedures were repeated to guide 10 needle insertions into a porcine lung. A regression analysis was performed to test the effect of needle angulation and insertion depth on the accuracy of insertion.ResultsIn the phantom model, all needle insertions (median trajectory depth, 64.8 mm; range, 46.1–153 mm) were successfully performed in single attempts. The overall accuracy was 1.36 mm ± 0.53, which did not differ between the 2 types of CT scanners (1.39 mm ± 0.54 [moving patient table CT] vs 1.33 mm ± 0.52 [moving gantry CT]; P = .54) and was not significantly affected by the needle angulation and insertion depth. The accuracy for the porcine model was 9.09 mm ± 4.21.ConclusionsRobot-assisted needle insertion using the ANT-C robotic device was feasible and accurate for targeting multiple markers in a phantom model.     

Metallic clip deployment during stereotactic breast biopsy: retrospective analysis

PURPOSE: To determine the visibility of presumably excised lesions on screen-film mammograms obtained after biopsy and to determine the accuracy of clip deployment on the basis of measurements obtained on routine pre- and postbiopsy mammograms. MATERIALS AND METHODS: One hundred eleven cases of core-needle biopsy with clip deployment were reviewed. In each, the type of lesion, lesion location, and biopsy approach were recorded. Pre- and postbiopsy images were reviewed, and the distance between the clip and biopsy site was measured. Postbiopsy images were reviewed to determine whether the targeted lesion remained visible. RESULTS: In 62 (56%) cases, the clip was located within 5 mm of the target on postbiopsy images (craniocaudal and mediolateral), while in 18 (16%), the clip was within 6-10 mm on one projection. However, 31 (28%) clips were more than 1 cm from the target on at least one postbiopsy image. Of the 111 cases, 39 (35%) were malignant or atypical and required excision. Of these, 18 (46%) had clips at least 1 cm from the targeted lesion on at least one projection. CONCLUSION: Metallic clips placed during core-needle breast biopsy are intended to mark the biopsy site when the visible lesion is excised, in case additional biopsy is required. The data suggest that the position of metallic clips placed during stereotactic core-needle biopsy may differ substantially from the location of the biopsy site. Postbiopsy mammography should be performed in two orthogonal planes to document clip position relative to the biopsy site.     

Accuracy in tumor size measurements: Comparison of digital mammography,digital breast tomosynthesis and synthetic mammography

PurposeThe aim of this study was to assess the accuracy of digital mammography (DM), digital breast tomosynthesis (DBT) and synthetic mammography (SM) in tumor size measurements compared with histological tumor sizes.Materials and methods71 breast cancer patients who underwent DM and DBT acquisitions simultaneously were included in this study. One radiologist with 8 years of experience in breast imaging measured tumor sizes independently in three separate sessions which include DM, DBT and SM images, respectively. The correlations between the measured tumor sizes on each imaging technique and histological sizes were analyzed using Spearman correlation test. The patients were categorized into two subgroups according to assigned breast density categories (dense and non-dense), and histological tumor sizes (≤2 cm and > 2 cm). To assess the agreement levels between the measured tumor sizes and histological sizes Bland-Altman analyses were performed for each imaging technique.ResultsThe mean of histological size of tumors was 23.85 ± 16.57 mm (median: 20). The means of measured tumor sizes were 21.21 ± 13.59 mm (median: 19), 21.52 ± 13.42 mm (median: 19) and 18.97 ± 11.21 mm (median: 17) in DM, DBT and SM, respectively. The Spearman correlation values with histologic sizes were 0.814 (P < 0.001), 0.887 (P < 0.001), and 0.852 (P < 0.001) for DM, DBT and SM, respectively. In subgroup analyses, the correlation values showed decrement for tumors >2 cm in size compared to tumors ≤2 cm in size.ConclusionDBT provides the most accurate tumor size measurements among mammographic imaging techniques and if mammography will be used in tumor size measurements, DBT should be preferred.     

Radio-frequency thermal ablation with hypertonic saline solution injection of the lung: ex vivo and in vivo feasibility studies

The aim of this study was to assess the effects of simultaneous instillation of NaCl solutions during radio-frequency ablation (RFA) on the dimension of the ablated lesion in ex vivo bovine lung tissue and in vivo rabbit lung tissue. The RFA was induced in ex vivo bovine lung tissue which was inflated with room air and in vivo rabbit lung tissue by a 500-kHz RF generator and a 17-G cooled-tip electrode. In in vivo experiments, RFA was performed using CT guidance. The RF energy was applied for 5 min with or without instillation of 0.9 or 36% NaCl solutions. The changes in tissue impedance, current, power output, and temperature of the electrode tip were automatically measured. The maximum diameter of all thermal lesions was measured perpendicular to the electrode axis by two observers. In an ex vivo study, the mean lesion diameters using 36 and 0.9% NaCl solutions were larger than those of the control group: 51±8, 34±6, and 5±2 mm (p<0. 05). In in vivo rabbit lung tissue, the mean lesion diameter with NaCl solution (15.3±3.1 mm) was larger than that of the lesion without NaCl solution (8.5±1.4 mm; p<0.05). With instillation of NaCl solutions, a marked decrease of tissue impedance (>100 Ω) and corresponding increase of current flow occurred in both ex vivo and in vivo studies. This experimental study demonstrates that RF ablation with simultaneous NaCl solution infusion of the lung is more effective in achieving coagulation necrosis than conventional RFA procedure.