胆道系统结石腹腔镜及开腹手术虚拟可视化研究
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摘要
背景
胆道系统结石病通常依结石所在的部位,分别称为胆囊结石、胆总管结石和肝胆管结石等。随着人民生活方式的改变和老龄化社会的到来,胆道结石病病谱构成正发生着改变,其中胆囊结石发病率呈逐年上升趋势。自20世纪80年代后期,腹腔镜胆囊切除术作为微创外科技术的代表,成为新世纪发展的潮流,使胆囊切除术从开放法手术时代进入到腹腔镜外科时代。然而腹腔镜胆囊切除术至今仍然并非平安无事,据统计其胆管损伤率仍在0.2-0.3%左右,由于接受此项手术治疗的患者数目众多,故做好腹腔镜胆囊切除术仍然是对外科医师培训上至关重要的事。虽然国内外已经出现了各种商业化的腹腔镜技术训练工具及虚拟手术机械,但大多仍停留在基础训练层面,难以实现个体化,因而也无法显著减少腹腔镜胆囊切除术的并发症发生。与此同时,对肝内外胆管结石的手术治疗则出现了两种不同的趋势,一方面是大部分胆总管结石及部分肝胆管结石已经可以在腹腔镜下实现微创化处理；而另一方面随着人们对肝胆管结石病病理改变认识的提高,肝胆管结石的开腹手术治疗趋向于联合多种手术方式,以达到“去除病灶,取尽结石,矫正狭窄,通畅引流,防止复发”的目的。因而如何进一步提高腹腔镜手术的安全性及如何合理有效地选择胆道系统结石病的手术方式问题成为摆在人们面前的两大现实问题,而这两大问题的实质仍然是如何对特定患者的手术治疗实现个体化选择。2003年本课题组采用数字化虚拟中国女性一号肝脏数据集和肝脏管道灌注标本CT薄层扫描数据进行三维重建和虚拟手术研究,随后开始利用64排螺旋CT腹部薄层扫描数据进行肝胆脾胰等脏器以及血管的计算机辅助三维重建及虚拟可视化手术研究。由于上述虚拟手术是基于患者特征性三维重建模型,因而实现了个体化的要求。课题组目前已对多种肝胆系统疾病包括肝癌、肝血管瘤、胰腺癌等实现了个体化的手术虚拟仿真,显示了其重要的临床应用价值。本研究即是将该技术及“个体化”的思想向胆道系统结石手术治疗的两大领域即腹腔镜和开腹手术的进一步延伸。
目的
1、研究可视化虚拟仿真技术在腹腔镜胆囊切除术、腹腔镜胆总管切开引流及左肝外叶切除术中的应用价值。
2、研究可视化虚拟仿真技术在复杂肝胆管结石手术方式合理选择及再次胆道手术中的临床应用价值。
方法
采用优化的64排螺旋CT扫描技术,收集胆囊结石、胆总管结石及肝胆管结石亚毫米图像数据,应用自主研发的,具有自主知识产权的腹部医学图像三维可视化系统(MI-3DVS)进行三维重建和辅助诊断；然后应用虚拟器械及仿真手术系统进行胆道系统结石病例的可视化仿真手术。
1、胆囊结石个体化腹腔镜虚拟可视化手术研究
1.1研究对象：患者,女,43岁,上腹痛反复发作10余年,诊断为“胆囊结石并慢性胆囊炎”。
1.2设备
64排螺旋CT—PHILIPS Brilliance64(荷兰PHILIPS公司)；图像后处理工作站为PHILIPS Brilliance64层螺旋CT自带的Mxview工作站；FreeForm Modeling System(美国SensAble Technologies公司)；力反馈设备PHANToM (PHANToM Desktop); ACDSee9 Message Center (ACD System Ltd.); MI-3DVS(自主研发。主机：内存2G、处理器2.0G*2Xeon 5130)。
1.3腹腔镜器械的设计开发
本研究在课题组前期简单开腹手术器械的基础上,进一步研究虚拟腹腔镜手术器械。具体方法包括3个步骤,即几何建模、运动建模及物理建模。在FreeForm Modeling System中应用带力反馈装置的PHANToM可操纵这些器械进行虚拟手术。我们设计开发的腹腔镜虚拟手术器械包括TORCAR、电凝钩、组织钳、钛夹钳、剪刀、胆道镜、超声刀等,电刀及剪刀赋予一定的组织切割功能。
1.4胆囊结石病例CT扫描参数的设定及数据存储
常规平扫时患者取仰卧位,头足方向,由膈顶至肝脏下缘,扫描条件120KV、250mAs；采用0.625x64排探测器组合,以层厚5mm、间隔5mm、螺距0.984、球管旋转一周时间0.5s。动脉期扫描延时时间为20-25s,门脉期为延时50-55s。扫描结束后将图像数据传至Mxview工作站,在Mxview工作站进行三期数据(平扫期、动脉期和门脉期)的刻盘存贮。格式为DICOM(Digital Imaging and Communications in Medicine)3.0,然后通过DICOM查看器将数据转换为BMP格式。
1.5图像分割及三维重建
本研究的分割方法采用阈值分割法与区域生长法,三维分割与二维分割相结合方式进行。利用MxliteView DICOM Viewer阅读64排CT扫描数据,调整适当的窗宽和窗位,并将以DICOM数据导出并转化成JPEG格式存盘,将JPEG文件导入ACDSee 9 Message Center转化成BMP文件,并调整图像大小后导入自主开发的MI-3DVS进行分割,分割后的图像文件进行三维重建,并以STL格式的文件输出,重建后的模型导入FreeForm Modeling System进行平滑和修饰。
1.5.1肝脏、胆道系统及腹腔血管图像分割
采用自行设计的分割软件MI-3DVS,以自适应的区域生长算法对肝脏、胆道系统及其周围血管系统进行序列分割,得到分割后的肝脏、胆道系统、腹主动脉、腹腔动脉及其分支、门静脉、肝静脉系统等的STL(STereo Lithography)格式数据。其中胆道系统及结石的分割要求尽量精准。胆囊结石患者胆囊内大多存在胆汁,由于胆汁密度与水接近,因而在CT扫描图像上胆囊底部、体部与周围组织存在较明显的密度差,采用同一域值下的自适应区域生长法进行图像分割较为理想；但胆囊颈及胆囊管由于解剖结构细小,且往往存在结石嵌顿,利用胆管与结石阈值的不一致性,采用胆管与结石在不同域值下分别分割的方式较为可行；对胆囊内充填性结石及萎缩性胆囊、因胆囊壁与结石间距离过小,采用同一域值下的自适应区域生长法单张或序列二维图像分割,胆囊结石患者肝外胆管及肝门部胆管多无扩张,图像分割存在较大困难,但上述结构对腹腔镜手术而言却又十分重要,我们采用对不同扫描期别图像进行多次胆道(肝门部胆管、胆囊管、胆总管)及结石的自动切割后,再利用系统自动整合功能,得到完整的胆道系统及结石分割STL数据。对于CT“阴性结石”,由于CT图像分辨率太低,则需参考B超结果定位,利用软件模拟出类似结石整合入胆囊,以求三维重建图像完整。
1.5.2胸腹壁组织及腹腔的分割
以自适应区域生长算法对胸腹壁组织包括皮肤、肋骨、胸骨、脊柱等进行序列分割,分别得到各组织的分割后的STL数据。
1.5.3胸腹壁、肝脏及其血管、胆道系统等的三维重建
将分割图像的STL格式数据导入FreeForm Modeling System进行平滑和去除一些燥声,然后系统根据各组织脏器的真实空间位置关系自动配置成一整套的脏器三维重建模型,对模型及各组成部分可以进行放大、缩小、旋转、透明等操作,全方位观察各结构或细节。
1.6腹腔镜手术环境建立及腹腔镜胆囊切除术仿真可视化
腹腔镜手术体位与开腹手术有所不同,利用FreeForm Modeling System图像旋转-移动工具可将腹壁及腹腔脏器三维重建模型设置左侧卧30°,头高脚低仰卧位,使与实际腹腔镜胆囊切除术体位一致。腹腔镜手术术者视角与开腹手术相比也较为固定,通常更接近水平前后位,有时为了显示特定组织结构,还可将30。镜进行旋转,利用FreeForm Modeling System水平及纵向旋转工具,以肚脐为参考点,将视角调整至水平30°角左右即可满足要求。此外以FreeForm Modeling System软件工作窗模拟腹腔镜手术显示器屏幕,通过对工作窗放大／缩小、左右平移等操作模拟摄像头进退、扫视及旋转等功能也较为方便。然后利用力反馈设备PHANTOM和自行开发设计的腹腔镜手术器械进行腹腔镜下胆囊切除术的重要手术步骤的虚拟仿真,与开腹手术相比,腹腔镜手术器械的活动范围受到TORCAR位置、腹膜腔范围、组织结构等的限制,虚拟仿真手术时也要求适应上述要求,但有时为了显示重要组织结构或重要手术步骤,可将胸腹壁或其他结构透明化,甚至暂时隐藏。
2、肝内外胆管结石个体化腹腔镜虚拟可视化手术研究
2.1、研究对象：患者,男,45岁,发现胆总管结石3年,上腹痛反复发作1年余,CT提示“左肝外叶胆管结石,胆总管结石,肝内外胆管扩张”。
2.2、患者64排CT原始扫描数据的采集、图像分割及三维重建同“1.4”及“1.5”。
2.3、腹腔镜器械的设计开发同“1.3”
2.4、腹腔镜手术环境建立同“1.6”,腹腔镜下虚拟胆总管切开取石引流及左肝外叶切除术手术步骤。
3、肝胆管结石三维重建及开腹手术仿真可视化研究
3.1研究对象：收集我院自2008年10月至2009年10月22例肝胆管结石患者64排螺旋CT数据,选其中代表性的4个病例进行分析说明：例1：叶XX,女性,ID：161510,53岁,腹痛反复发作10年入院,CT提示：左肝外叶内胆管结石。例2：谢XX,ID：115350,女性,45岁,因B超发现肝胆管结石3年余收入院,入院时CT提示：肝内胆管结石,肝胆管扩张积气。例3：李XX,ID：110230,女性,45岁,上腹痛反复发作1年余入院,CT提示：肝胆管显著扩张,左右肝内胆管及胆总管结石。例4：郑XX,ID：1316277,女性,52岁,上腹部反复疼痛发作十余年入院,CT提示：左、右肝内胆管结石及胆管扩张,胆总管结石。
3.2仪器与设备同“1.2”
3.3患者64排螺旋CT原始扫描数据的采集、图像分割、三维重建同“1.4”
3.4.肝胆管结石的可视化仿真手术
在FreeForm Modeling System中对三维重建模型及各组成部分进行放大、缩小、旋转、透明等操作,全方位观察各结构或细节,根据结石分布、胆道系统及肝脏病变情况选择合理手术预案,利用力反馈设备PHANTOM和自行开发设计的开腹手术器械进行肝胆管结石的仿真可视化手术,以确定手术预案可行性,并与实际手术情况对照,以探究该技术的临床应用价值。
4、再次手术肝胆管结石三维重建及仿真可视化研究
4.1研究对象：收集我院自2008年10月至2010年1月20例再次肝胆管结石患者64排螺旋CT数据,选其中代表性的3个病例进行分析说明：例1：吴XX,ID：1145376,女性,45岁,上腹部疼痛反复发作10余年入院,5年前于外院行“胆道探查术”(具体手术方式不详),CT提示：左肝内胆管结石,肝门部低密度灶性质待查。例2：黎XX,ID：1195132,女性,56岁,因上腹痛反复发作10余年,再发加重1天入院,既往有2次胆道手术史(手术方式均为胆总管切开探查取石引流术),CT提示：左、右肝内胆管及胆总管结石,肝内外胆管扩张。例3：伍XX,ID：1293786,女性,46岁,因上腹痛反复发作8余年,再发加重10天入院,既往有2次胆道手术史(手术方式均为胆总管切开探查取石引流术),CT提示：肝内外胆管扩张,肝内结石弥漫分布,胆总管巨大结石。
4.2仪器与设备同“1.2”
4.3患者64排螺旋CT原始扫描数据的采集、图像分割、三维重建同“1.4”
4.4再次手术肝胆管结石患者的可视化仿真手术
在FreeForm Modeling System中对三维重建模型及各组成部分进行放大、缩小、旋转、透明等操作,全方位观察各结构或细节,根据结石分布、胆道系统及肝脏病变情况力求找出结石复发的原因,并选择合理手术方案,利用力反馈设备PHANTOM和自行开发设计的开腹手术器械进行肝胆管结石的虚拟仿真手术,以确定手术预案可行性,并与实际手术情况对照,以探究该技术的临床应用价值。
结果
1、胆囊结石个体化腹腔镜虚拟可视化手术研究
1.1、腹腔镜手术器械的设计开发
在FreeForm Modeling System建立的手术虚拟环境中,在原有的开腹手术器械库的基础上,本研究进一步自主研制的腹腔镜仿真器械形态逼真且有力反馈感受,可以完成简单的腹腔镜腔内操作。这些器械包括：气腹针、电凝钩、锥鞘、超声刀、钛夹钳等,然后利用力反馈设备PHANTOM和自行开发设计的腹腔镜手术器械进行腹腔镜下仿真手术,整个仿真手术过程有力反馈的感受,与临床过程所见相符合。
1.2、腹部脏器及胸腹壁组织图像分割与三维重建
胆囊结石患者64排螺旋CT薄层扫描数据集,获得676层CT扫描图像。图像分为平扫期、动脉期、静脉期、门静脉期,各期均含有患者特定的解剖学信息,可分别用于进行图像的分割及三维重建,并相互参考补充。
1.2.1肝脏及其周围血管系统图像分割
肝脏模型能真实反映肝脏的实际体积和肝脏的解剖标志,并且通过调节肝脏的透明度可同时显示肝脏和肝内的动脉、静脉、门静脉各分支。腹主动脉、腹腔动脉及其分支胃十二指肠动脉、双肾动脉、胃右、左动脉、肝固有动脉、脾动脉、肠系膜部分动脉等结构,形态逼真,立体感强,尤其是胆囊周围动脉的迂曲走行,较解剖图谱的表示更加立体和真实。门静脉系统显示肝外的主干和脾静脉、肠系膜上静脉,肝内门静脉系统能清楚显示门静脉的左主干和右主干,以及各叶、段的分支。
1.2.2胆道系统及结石的图像分割及三维重建
数据导入MI-3DVS,以自适应区域生长图像分割法通常能一次性完整分割胆道系统,对一些细微结构如胆囊管与胆总管汇合部、不扩张的肝门部胆管等,可利用数据集的不同期别图像如平扫期、动脉期、静脉期、门静脉期等,分别对各期胆道系统进行图像切割,再利用系统自动整合功能将各期所含特定解剖学信息整合为完整的胆道三维图像,使重建的胆道系统模型能更真实反映胆囊与胆总管及左右肝管的空间位置关系,胆道系统三维模型与腹腔脏器及血管模型整合后,对腹腔镜手术有重要解剖学意义的胆囊三角、肝十二指肠韧带、右肝门等区域的结构特点便可一目了然。
1.2.3胸腹壁图像切割及三维重建
重建的胸腹壁模型立体感强,且具皮肤纹理,对腹腔镜手术具有定位意义的重要解剖结构如肚脐、双侧肋弓、剑突角等清晰可辨。当胸腹壁透明度设置为0时,可以完全显示腹腔内各脏器和腹腔血管结构。
1.3腹腔镜手术环境建立
以FreeForm Modeling System软件工作窗模拟腹腔镜手术显示器屏幕,利用FreeForm Modeling System图像旋转-移动工具改变腹壁及腹腔脏器三维重建模型位置以设置所需手术体位。利用FreeForm Modeling System水平及纵向旋转工具,以肚脐为参考点,将视角调整至水平30°角左右,通过对工作窗放大／缩小、左右平移等操作模拟摄像头进退、扫视及旋转等功能,效果与实际腹腔镜下操作相似。有时为了显示重要组织结构或重要手术步骤,可将胸腹壁或其他结构透明化,或暂时隐藏,以体现虚拟仿真手术的优点及灵活性。但腹腔镜手术的气腹建立过程由于三维模型目前还没有弹性变形能力,因而暂时还无法虚拟。
1.4腹腔镜胆囊切除术可视化仿真手术过程
1.4.1手术体位设置：利用FreeForm Modeling System图像旋转-移动工具将腹壁及腹腔脏器三维重建模型设置左侧卧30度,头高脚低仰卧位,使与实际腹腔镜胆囊切除术体位一致。
1.4.2设置各TORCAR位置：首先于脐周建立1.0cmTORCAR作观察孔,置入摄像杆,然后于剑突下建立1.0cmTORCAR作主操作孔,右侧锁骨中线与右侧肋弓交界处建立0.5cmTORCAR作辅操作孔。
1.4.3腹腔镜胆囊切除术手术步骤虚拟
腹腔镜虚拟环境下激活胆道系统模型,并定义其力反馈强度大小,使用PHANToM操纵电凝钩、组织钳、剪刀、抓钳等虚拟腹腔镜器械完成胆囊三角显露、胆囊管及胆囊动脉夹闭及切断、分离胆囊床、取出胆囊标本等手术步骤,整个仿真过程与实际手术过程相似。
2、肝内外胆管结石个体化腹腔镜虚拟可视化手术研究
2.1肝胆管结石患者64排螺旋CT采集、图像分割及三维重建同结果“1.2”
2.2腹腔镜手术器械的设计开发同结果“1.1”
2.3腹腔镜肝内外胆管结石手术可视化过程
2.3.1手术体位设置：利用FreeForm Modeling System图像旋转-移动工具将腹壁及腹腔脏器三维重建模型设置左侧卧30度,头高脚低仰卧位,使与实际腹腔镜胆道手术体位一致。
2.3.2设置各TORCAR位置：首先于脐周建立1.0cmTORCAR作观察孔,置入摄像杆,然后于剑突下及左肋缘下建立1.0cmTORCAR作主操作孔,右侧锁骨中线、右腋前线与右侧肋弓交界处分别建立0.5cmTORCAR作辅操作孔。
2.3.3腹腔镜下虚拟手术过程,包括：胆囊切除、胆总管前壁切开取石、胆道镜探查胆总管并取石、腹腔镜下左肝外叶切除、胆总管T管及腹腔引流管放置等,手术过程与临床实际相比有较高仿真度。
3、肝胆管结石三维重建及开腹手术仿真可视化研究
3.1肝胆管结石患者64排螺旋CT采集、图像分割及三维重建同结果“1.2”
患者三维重建模型形态逼真,解剖结构位置正确,肝内各管道系统的空间位置关系直观可辨。通过对模型的透明阈值设定及多方位旋转,可全面了解结石分布、胆管系统及肝实质病变情况以及病灶与周围组织的相互关系等,还可明确肝动脉、门静脉及肝静脉的变异类型等。
3.2.虚拟仿真手术过程及手术实际情况
在虚拟手术环境中,患者三维重建模型能通过放大、缩小、旋转及透明化等操作进行多方位、多角度地观察,明确肝内结石分布、胆道系统与肝脏大体形态改变及肝内血管树改变等情况,据此对肝胆管结石进行临床分型及选择最佳手术方式,然后仿真可视化上述手术过程,并指导实际手术过程。
例1三维重建结果显示：结石分布于左肝外叶及胆总管,左肝外叶肝实质萎缩,左肝静脉闭塞,右副肝管变异等。患者临床分型为Ⅱb型+E型,三维重建拟定手术方式为：胆囊切除+胆总管切开取石T管引流术+左肝外叶切除术。仿真可视化上述手术过程顺利,上述手术方案安全可行,但要注意保护右副肝管及肝中静脉,手术存在一定风险。患者接受手术,术后恢复顺利。
例2三维重建结果显示：结石分布于右肝后叶及右肝管,右肝后叶胆管扩张及开口部狭窄,肝门部胆管汇合处狭窄,尾状叶胆管汇合变异及右肝动脉压迫肝总管等。患者临床分型为Ⅱb型+Eb型,拟定手术方式为：胆囊切除+肝方叶切除+肝门部胆管切开整形+胆总管横断式胆肠吻合术。经仿真可视化上述手术方案,右肝后叶胆管开口部在肝方叶切除后可顺利切开整形,而且不会损伤肝中静脉,手术目的可以达到。此患者目前尚未接受手术。
例3三维重建结果显示：肝内外胆管高度扩张,结石分布于左右肝内胆管及胆总管,无肝内胆管狭窄及肝实质萎缩。患者临床分型为Ⅲa型+E。型,拟定手术方式为：胆囊切除+胆总管切开取石+侧-侧胆肠吻合术。仿真可视化上述手术方案,认为手术方案安全可行。因患者结石易于复发,亦可考虑行皮下盲襻式胆肠吻合术作为预备手术方案。患者接受手术,术中情况与虚拟手术所见相似,患者术后恢复顺利。
例4三维重建结果显示：肝内外胆管高度扩张,胆囊结石,胆管结石分布于左肝外叶、右肝管及胆总管。患者临床分型为Ⅱa型+Ea型,拟定手术方式为：胆囊切除+胆总管切开取石引流+肝左外叶切除+侧-侧胆肠吻合术。虚拟手术过程显示手术安全可行。患者接受手术,术后恢复顺利。
4、再次手术肝胆管结石三维重建及仿真可视化研究
4.1肝胆管结石患者64排螺旋CT采集、图像分割及三维重建同结果“3.1”
4.2.虚拟仿真手术过程及手术实际情况
在虚拟手术环境中,通过对3D模型及其附件的放大、缩小、旋转及透明化等操作进行多方位、多层次观察,可明确肝内结石分布、胆道系统与肝脏大体形态改变等情况,然后针对上述病理改变及结石复发原因确定手术方案；通过仿真可视化上述手术过程,明确手术方案的可行性,并指导临床实际手术过程。
例1三维重建结果显示：结石分布于左肝外叶,左肝内胆管囊状扩张及左肝管开口部环状狭窄,胆总管内无结石,肝门部低密度灶为与胆道吻合之肠管。患者临床分型为Ⅱa型,结石复发原因为遗留肝内胆管狭窄及不适当的胆肠吻合术。拟定手术方式为：左肝外叶切除+胆-肠吻合拆除重建+左肝管切开整形。仿真可视化手术过程中发现从左肝外叶切除后裸露之左肝外叶胆管断端内即可将左肝管狭窄部切开整形,如此则既可经此途径探查胆总管及原胆-肠吻合口,又可保留左肝外叶肝组织。实际手术证实了仿真手术过程发现的正确性,术中探查原胆肠吻合口十分通畅,胆总管下端无结石,因而免于拆除胆-肠吻合拆除重建。患者术后恢复顺利。
例2三维重建结果显示：结石分布于左肝外叶及胆总管,肝内外胆管扩张,左肝管汇合变异,左肝外叶肝实质萎缩,门静脉左支及左肝静脉闭塞等。患者临床分型为：Ⅱa型+E型,结石复发原因为首次手术遗留肝内胆管、血管畸形未予纠正。拟定手术方式为：左肝外叶切除+胆管整形+胆-肠吻合术。实际术中证实三维重建诊断结果正确,手术计划顺利实现。患者接受手术,术后恢复顺利。
例3三维重建结果显示：结石分布于左、右肝内胆管及胆总管,肝内外胆管扩张,肝内胆管无狭窄。患者临床分型为Ⅲa型+E型,结石复发原因为既往手术未解决肝内及胆总管胆汁郁滞问题。拟定手术方式为：左肝外叶切除+右肝后叶切除+肝胆管切开取石+侧-侧胆肠吻合。实际手术顺利完成预定手术计划,患者术后恢复顺利。
结论
1、个体化腹腔镜虚拟可视化手术系统能成功完成腹腔镜胆囊切除术、腹腔镜胆总管切开取石引流及左肝外叶切除术手术过程,其“个体化”的特点有利于克服普通腹腔镜训练系统训练与实际手术操作间脱节的缺点,从而提高腹腔镜技术培训效果,减少实际腹腔镜手术术中并发症的发生。
3、个体化腹腔镜仿真可视化手术系统尚处于研究的初级阶段,需要继续吸收计算机虚拟现实技术的最新成果以逐步完善其功能。
3、三维重建及仿真可视化手术技术对肝胆管结石开腹手术及再次手术在准确显示结石分布范围、胆管狭窄部位、胆管和／或血管变异,分析结石复发原因,正确临床分型及合理选择手术方案等方面均具有重要价值；而且仿真手术过程还可评估所选手术方案的可行性及安全性,为临床实际手术操作提供指导,从而进一步提高肝胆管结石病的临床疗效。
Background
Biliary lithiasis,including gallbladder stones, common bile duct stones, intrahepatic bile duct stones and so on. With the people's lifestyle changes and the arrival of aging society, constitute spectrum of biliary calculus disease are changing, in which the incidence of cholelithiasis showed an upward trend year by year. For cholelithiasis,since the late 80's of 20th century, laparoscopic cholecystectomy,as the representative of minimally invasive surgical techniques, have become the development trend of new century, and bring the treatment of cholelithiasis from the open cholecystectomy era of surgery into the era of laparoscopic surgery. However, Laparoscopic cholecystectomy is still not without incident today, according to statistics,its bile duct injury rate is still about 0.2%-0.3%. As the acceptance of laparoscopic cholecystectomy is on an increasing number, strengthening the training of laparoscopic cholecystectomy is still very important to the training of surgeons.Although there have been a variety of domestic and foreign commercial virtual laparoscopic surgical training machines, but most of them is still at the basic training level, and difficult to achieve individual and thus could not significantly reduce the complications of laparoscopic cholecystectomy occurred. At the same time, for the surgical treatment of bile duct stones, there have been two different trends recently. On the one hand, most of the common bile duct stones and some of the intrahepatic bile duct stones have been able to achieve minimally invasive laparoscopic treatment,On the other hand, due to people's understanding of pathological changes of intrahepatic bile duct stones were more and more detailed, open surgery of intrahepatic bile duct stones tended to be a joint model of a variety of surgical method in order to achieve the purpose of "remove the lesion, taking every stones, corrected narrow, unobstructed drainage and prevent recurrence". Thus,how to further enhance the safety of laparoscopic surgery and how to choose a reasonable and effective surgical method for biliary lithiasis have become the two major practical problems for surgeons.However, The essence of these two major issues remained how to achieve a individualized surgical treatment for specific patients with biliary lithiasis.In 2003, our research group performed 3-dimensional reconstruction and simulation surgery based on data collected from CT scanning of a digitalized virtual female Chinese No.1 liver perfusion specimen. Later, our study was extended to 3-dimensional reconstruction and visible simulation surgery of the liver, pancreas, gallbladder, spleen, and vascular system based on 64-slice helical CT scanning data. At present, we were able to perform individualized Visible Simulation Surgery of hepatobiliary diseases, including liver cancer and pancreatic cancer etc. This current study addressed the utilization of visible simulation surgery and the "individual-oriented" thinking on the two areas of minimally invasive and laparotomy surgery for biliary lithiasis.
Objectives
This study aims:1) to establish individual-based virtual simulation laparoscopic surgery system based on the virtual simulation technology, and explore the application value of the system by using of force feedback devices and virtual laparoscopic surgical instruments to complete the virtual laparoscopic cholecystectomy,laparoscopic bile duct incision and liver resection, etc.2) bring the virtual simulation technology into the laparotomy treatment for complex hepatolithiasis, and to explore its clinical application value at the options of reasonable surgical method choice and re-biliary-tract surgery.
Methods
1 Study of individual laparoscopic surgery virtual visualization System for gallbladder stone disease
1.1 The object of study:the patient, female,43 years old, recurrent upper abdominal pain for more than 10 years, diagnosed as "gallstones and chronic cholecystitis."
1.2 Equipment:the software included ACDSee9 Message-Center (ACD System Ltd), MI-3DVS (self-developed), Free-Form Modeling System (Sens-Able Technologies, Inc.USA). The hardware included PHANTOM (PHANTOM Desktop), Main computer:memory 2G; Xeon 5130 processor 2.0G*2.
1.3 Development of laparoscopic simulation surgical instruments
On the basis of previous studies, simulation surgical instruments were developed through three steps, such as geometry modeling, movement modeling and physical modeling. The laparoscopic simulation surgical instruments included laparoscopic surgery TORCAR, electro-coagulation hook, organization pliers, titanium clamp, scissors, cholangioscopy, ultrasonic knife,etc. Virtual laparoscopic basic surgical operation was carried out using force feed-back devices of Phantom with particle-spring-damper force feedback model in Free-Form Modeling System.
1.4 CT scanning and data collection of biliary lithiasis
The patients were scanned from the top of diaphragm to the lower edge of liver in supine position. The CT scanner settings involved 250mAs,120KV, and thickness of 5mm, interval of 5mm,0.984 pitch, and rotation speed of 0.5S/cycle. Scanning was delayed 20 to 25S after arterial phase,50 to 55S after venous phase. Then data were transferred to Mxview working station. Data of plain scan, arterial venous phase, portal vein phase were stored in Mxview working station. Its format was transferred from DICOM to BMP.
1.5 CT image segmentation and 3-dimension reconstruction
1.5.1 Segmentation of liver,biliary system and abdominal vascular system image
Data of hepatic tissue, bile duct system and abdominal vascular system were processed by a self-developed Medical Image Processing System. This Medical Image Processing System uses a self-adaptive region growing algorithm to segment previous tissues' images consecutively and obtained data in Stereo Lithography format. In which segmentation of biliary system and the stone image required accurate as far as possible. In common conditions, the segmentation of gallbladder and the stone image were more satisfied, because the density of gallbladder bile quite different with the surrounding tissue. But when the gallbladder filled by stones, atrophic gallbladder,stone incarcerated within gallbladder neck and cystic duct,especially gallbladder neck and cystic duct structure was small, or hepatic portal bile duct was non-expanded, image segmentation became more difficult, In such cases,image segmentations to different stage of CT data were carried out, and by complement each other, get a complete system and biliary stones STL data.
1.5.2 Abdomen and abdominal wall tissue segmentation Standard Template Library data of the abdominal wall tissue including skin, ribs, sternum, spine aorta were obtained by a 3-dimensional dynamic region growing method.
1.5.3 3-dimensional reconstruction of liver, bile duct systems,vascular
system,abdominal wall,etc.
Data of liver, bile duct systems,vascular system,abdominal wall in Standard Template Library format were introduced to the Freeform Modelling system to be smoothed and noise was eliminated. Then images of the liver and bile duct systems were reconstructed,Then the system configured them into a set of three-dimensional reconstruction organs model according to their real space location of the organization automatically,and we can zoom, rotate, transparency the different components of the model to observe the structure or details.
1.6 Laparoscopic surgery scenario building and laparoscopic surgery virtual simulation
Laparoscopic surgery position is different from laparotomy, set the position of abdominal wall and abdominal viscera three-dimensional reconstruction model is similar to the actual position of laparoscopic cholecystectomy.Set the viewing angle of laparoscopic surgery to 30-degree using Freeform Modeling System Image Rotation-Move tool. Furthermore, laparoscopic surgery display screen is simulated by Freeform Modeling System software work window. Through the window zoom in/out, pan around analog cameras advance and retreat, glance, and rotation functions.Then use the PHANTOM force feedback devices and self-developmented laparoscopic surgical instruments for the virtual simulation of laparoscopic cholecystectomy.Compared with laparotomy, the scope of activities of laparoscopic surgical instruments was limited by TORCAR location, range of peritoneal cavity, organizational structure and other constraints, the virtual simulation of surgery was also required to adapt to these requirements, But sometimes in order to show an important organizational structures or major surgical procedures, abdominal wall or other structure can be transparent, or even temporatedly hidden.
2 study of individual laparoscopic surgery virtual visualization system for patient with intrahepatic and extrahepatic stones
2.1 The object of study:the patient, male,45 years old, found stones in common bile duct three years ago, and recurrent abdominal pain for more than a year, CT NOTE:left lateral lobe of liver bile duct stones, common bile duct stones, bile ducts expansion"
2.2 Original 64-slice CT scan data collection, image segmentation and three-dimensional reconstruction This step was in agreement with "1.4."。
2.3 Laparoscopic instrument design and development This step was in agreement with "1.3"
2.4 Laparoscopic surgery scenario building and laparoscopic surgery virtual simulation This step was in agreement with "1.6", by using virtual laparoscopic instruments simulate, the major surgical procedures of laparoscopic common bile duct incision and hepatic left lateral lobectomy were simulated.
3 Applications of three-dimensionnal reconstruction and virtual simulation technique to intrahepatic caculi
3.1 The object of study:to collect 64-slice spiral CT data of four cases from 22 cases of bile duct stones patients in our hospital from October 2008 to October 2009: Example 1:XX patient, ID:161510,female,53 years old, recurrent abdominal pain for 10 years. CT NOTE:left hepatic bile duct stone. Example 2:XX patient, ID:115350,female,45 years old, bile duct stones found three years ago, CT NOTE: intrahepatic bile duct stones, bile duct expansion, gas in intrahepatic bile duct. Example 3:XX patients, ID:110230,female,45 years old, recurrent abdominal pain for more than one year. CT NOTE:a significant expansion of bile duct, left/right intrahepatic bile duct and common bile duct stones. Example 4:XX patients, 1316271,female,52 years old, for upper abdominal pain recurring more than 10 years admitted to hospital, CT Tip:left and right hepatic bile duct contained stones, expanded common bile duct exists stones.
3.2 Apparatus and equipments were similar to the "1.2"
3.3 64-slice spiral CT original scan data acquisition, image segmentation,3D reconstruction were similar to the "1.4"
3.4 Visible simulation surgery for intrahepatic calculi
The Free-Form Modelling System was used to reconstruct 3-dimensional models of viscera according to their real spatial position. The stereo model and its components could be amplified, deleted, rotated, and hyalinized to clarify the anatomical character of tissue structures, calculi distribution, bile duct stricture and deformity, vascular arrangement, and parenchymal lesions from omni-direction, multi-angle, and different levels. Then, according to the Chinese Guideline of Hepatobiliary Calculi Diagnosis and Treatment, we classified the disease and determined the optimal operation planning. Finally, simulated operations were performed in the Free-Form Modelling System by a force feed-back instrument (PHANTOM). The simulated operation helped us to predict the difficulties that may be encountered in the real operation process and what precautions to take.
4 Applications of three-dimensionnal reconstruction and virtual simulation technique to reoperational patients of intrahepatic caculi
4.1 The object of study:to analysis 3 cases underwent biliary reoperatons: Example 1:XX patients, ID1145376,female,45 years old, upper abdominal pain recurrence for more than 10 years, accepted"bile duct exploration" (the specific surgical method unknown) five years ago, CT Tip:left intrahepatic bile duct stones, a hilar low-density lesion unknown nature existed. Example 2:XX patients, ID:1195132,female,56 years old, recurrent upper abdominal pain for more than 10 years, and underwent biliary tract surgery two times (both common bile duct exploration and T-tube drainage), CT Tip:stones filld in left, right hepatic bile duct and common bile duct. Example 3:XX patients, ID:1293786,female,46 years old, recurrent upper abdominal pain for more than eight years, there were two times history of biliary tract surgery (common bile duct exploration and T-tube drainage), CT Tip:expansion of intra-and extrahepatic bile duct, intrahepatic stones were scattered, large common bile duct stones.
4.2. Apparatus and equipment were in agreement with the "1.2"
4.3 original 64-slice spiral CT scan data acquisition, image segmentation,3D reconstruction were in agreement with the "1.4"
4.4. virtual surgery for reoperations of Intrahepatic bile duct stones this part was similar to "3.4"
Results
1 Study of individual laparoscopic surgery virtual visualization System for gallbladder stone disease
1.1 Design and development of laparoscopic surgical instruments
The virtual laparoscopic instruments in this study could complete some simple laparoscopic operation procedure by a force feed-back instrument (PHANTOM), the feedback powerful feelings and findings of the simulation of surgical procedures were consistent with the clinical process.
1.2 Abdominal organs and abdominal wall tissue image segmentation and three-dimensional reconstruction
1.2.1 Liver and peripheral vascular system image segmentation
The hepatobiliary tract model was segmented with the Medical Image Process System, after smoothing with the Free-Form Modelling System, and its structure become clearer and all of the structures including the bile duct, hepatic artery, hepatic vein, portal vein, and calculi were reconstructed in 3-dimensions successfully.
1.2.2 Biliary system and the stone image segmentation and three-dimensional reconstruction
The biliary system model can more truly reflect the relationship between gallbladder,common bile duct and the left/right hepatic bile duct Three-dimensional model of biliary system, abdominal organs and vascular models with integrated, the structures of triangle gallbladder, liver duodenum ligament and right hepatic door could be seen clearly, their structural characteristics were very important for laparoscopic surgery. 1.2.3 Abdominal wall image segmentation and three-dimensional reconstruction
The thoraco-abdominal wall model were clear, strong stereo and had skin texture appearance, and the structures which had significant value for laparoscopic surgery such as the navel, bilateral costal arch, xiphoid angle could be seen clearly. When the transparency of abdominal wall model was set to 0, the abdominal organs and abdominal vascular structure could be fully displayed. In order to observe the details from different ranges, such as zooming in, zooming, and rotation operations could be taken.
1.3 The establishment of laparoscopic surgery scenario
Set the position of abdominal wall and abdominal viscera three-dimensional reconstruction model similar to the actual position of laparoscopic cholecystectomy, and set the viewing angle of laparoscopic surgery to 30-degree using FreeForm Modeling System Image Rotation-Move tool. Then use the PHANTOM force feedback devices and self-developmented laparoscopic surgical instruments to simulate laparoscopic basic procedures. Sometimes, in order to show an important organizational structures or major surgical procedures, abdominal wall or other structure could be transparent, or even temporarily hidden.
1.4 Laparoscopic visualization of basic laparoscopic surgical operation
In the laparoscopic virtual environment,using PHANToM manipulate the "electrocoagulation hook", "titanium clamp", "scissors", "grasping forceps" and other virtual laparoscopic insruments to complete the main process of laparoscopic cholecystectomy.including:gallbladder triangle revealed, cystic duct and cystic artery occlusion and cut off, separation of the gallbladder bed, remove the gallbladder specimens,ect. The whole simulation process was similar to the actual surgical procedure.
2 study of individual laparoscopic surgery virtual visualization system for patient with intrahepatic and extrahepatic stones
2.1 64-slice spiral CT acquisition, image segmentation and three-dimensional reconstruction
The result was Similar to the result "1.2"
2.2 Design and development of laparoscopic surgical instruments
The result was similar to the result "1.3"
2.3 Laparoscopic surgery visualization process for hepatolithiasis
2.3.1 Surgery position settings:In the laparoscopic virtual environment, the position of abdominal wall and abdominal viscera three-dimensional reconstruction model was similar to the actual position of laparoscopic cholecystectomy.
2.3.2 Set the location of the TORCARS:First, the establishment of 1.0cm TORCAR for observation at the Cullen hole, placed in camera shot. Then set the location of disposes hole (1.0cmTORCAR) and two auxiliary holes (0.5cmTORCAR) under xiphoid and left/right ribs.
2.3.3 Main process of laparoscopic surgery for hepatolithiasis in the laparoscopic virtual environment
Including:Cholecystectomy steps, Common bile duct incision and take Stones, Choledochoscopic exploration and take stones from common bile duct, Laparoscopic hepatic left lateral lobectomy steps, Common bile duct T tube and peritoneal drainage tube placement ect. The whole simulation process was similar to the actual surgical procedure.
3 Applications of three-dimensionnal reconstruction and virtual simulation technique to intrahepatic caculi
3.1 64-slice spiral CT acquisition, image segmentation and three-dimensional reconstruction
The result was Similar to the result "1.2",and the 3-dimensional model could be amplified, rotated, and hyalinized to clarify the anatomical character of tissue structure with omni-directional, multi-angle, and multi-level views. After we localized the intrahepatic calculi and determined the calculi shape, deformity or stricture of the bile tract system, the distribution of the intrahepatic vessel system, and parenchyma lesions, an optimal surgical option was chosen.
3.2. Virtual reality of surgical procedures and actual surgical conditions.
Case1:3-dimensional reconstruction revealed that the stones were localized in the bile duct of left lateral lobe, and no stones were present in the caudate lobe. This case was defined as typeⅡb+E of hepatobiliolithiasis and a left lateral lobectomy, cholecystetomy, choledochotomy, and T-tube drainage was recommended. the program was proofed feasible and safe by virtual simulation technology, but to protect the deputy right hepatic duct and liver vein were very important, there are certain risks in these surgical steps. The patient recovered uneventfully after operation.
Case 2:This case was defined as typeⅡb+Eb hepatobiliary lithiasis according 3-D reconstruction and CT film, we could see that the junction of the bilateral hepatic duct was narrowed, the opening of the right posterior bile duct was narrowed, and the bile duct of the right and left caudate lobe entered the right hepatic bile duct ect. We choose to perform 1st and 2nd grade choledochoplasty and choledochojejunostomy. Because first hepatic hilum was high, quadrate lobectomy was essential to expose hepatic hilum. Because air in the intrahepatic bile duct suggested sphincter of Oddi dysfunction, cholecystectomy, choledochotomy, and common bile duct exploration were necessary. the program was proofed feasible and safe by virtual simulation technology. At present the patient has not yet accepted operation.
Case 3:3-dimensional reconstruction revealed that stones were found in left/right intrahepatic bile duct and extrahepatic bile duct. The intrahepatic bile duct was markedly dilated and the hilar bile duct did not appear to be narrowed, This case was defined as typeⅢa+Ea hepatobiliary lithiasis. The best surgical option was cholecystectomy, choledocholithotomy of the common bile duct, and hepatic hilum and choledochojejunostomy. And the Patient underwent surgery, intraoperative situation is similar to the virtual surgical findings, the patient recovered uneventfully after operation.
Case 4:3-dimensional reconstruction revealed that stones were found in left/right intrahepatic bile duct and extrahepatic bile duct. and the stones of right intrahepatic bile duct in this case were secondary stones.This case was defined as typeⅡa+Ea hepatobiliary lithiasis, The best surgical option was cholecystectomy, choledocholithotomy of the common bile duct, and left lateral lobectomy, intraoperative situation is similar to the virtual surgical findings, the patient recovered uneventfully after operation.
4、Applications of three-dimensionnal reconstruction and virtual simulation technique to reoperational patients of intrahepatic caculi
4.1 64-slice spiral CT acquisition, image segmentation and three-dimensional reconstruction
The result were Similar to the result "3.1".
4.2 Virtual reality of surgical procedures and actual surgical conditions.
The 3-D models could be amplified, rotated, and hyalinized to clarify the anatomical character of tissue structure with omni-directional, multi-angle, and multi-level views. After we localized the intrahepatic calculi and determined the calculi shape, deformity or stricture of the bile tract system, the distribution of the intrahepatic vessel system, and parenchyma lesions, the reasons of bile duct stones recurrence was analysised, and then a reasonable surgical method was determinded according to the reasons. Finally,virtual above-mentioned surgical procedures were taken and to guide the actual surgical procedure.
case 1:Three-dimensional reconstruction results:stones were found in the left hepatic lobe, and the left intrahepatic bile duct was in cystic dilatation state, the opening of left hepatic duct was narrow, no stones within common bile duct low-density lesion nearby hilar bile duct maybe the bowel anastomosised with the bile duct, etc.This case was defined as typeⅡb of hepatobiliolithiasis according to results of 3-D,the reasons of stone recurrence were left intrahepatic duct stricture and inappropriate choledochojejunostomy.The rational surgical method as follows:left lateral lobectomy, bile-intestinal anastomosis demolition and reconstruction. In Virtual surgery, we found that we could cut and shaped the bile duct stricture from the bile duct stump,and then took exploration from this way, found the opening of biliary-enteric anastomosis is very smooth,and none stones in the common bile duct,thus the step of bile-intestinal anastomosis demolition and reconstruction was canselled, the patient recovered uneventfully after operation.
case 2:Three-dimensional reconstruction showed that:The stones were found in the left lobe and extrahepatic bile duct, intrahepatic bile duct system was dilatation, and bile duct variation existed in the left hepatic lobe.3-D model also showed that left hepatic lobe of liver was atrophied, and left portal vein and left hepatic vein were occlusioned and so on.According to the 3-D results,this case was defined as typeⅡa+E of hepatobiliolithiasis, the reasons of stones recurrence were malformations of intrahepatic bile ducts and vascular which were not corrected in the first operation. A reasonable surgical method as follows:left lateral lobectomy of the liver,bile duct plastic,bile-intestinal anastomosis. Actual surgery confirmed the malformations of intrahepatic bile ducts and vascular and achieve surgical planning, the patient recovered uneventfully after operation.
case 3:Three-dimensional reconstruction results:stones existed in the left, right hepatic duct and common bile duct, intrahepatic and extrahepatic bile ducts were expanded, intrahepatic bile duct system had no stenosises. According to the 3-D results,this case was defined as typeⅡa+E of hepatobiliolithiasis, the reasons of Stones recurrence were cholestasis in intrahepatic and common bile duct. A reasonable surgical method as follows:left lateral lobectomy of the liver, right posterior hepatic lobectomy, common bile duct incision,side-side biliary-enteric anastomosis, the actual surgery completed the scheduled surgical planning successfully, and the patient recovered uneventfully after operation.
Conclusions
1. The individual laparoscopic virtual visualization system was able to establish a realistic scenario of laparoscopic surgery, complete successfully the major surgical procedures of laparoscopic cholecystectomy, laparoscopic bile duct exploration and left hepatic lobectomy. The self-developed virtual laparoscopic surgical instruments have vivid image, can increase the visual effect of surgical simulation. The "individual" features of this system can help practitioners to avoid the mind-set from the common laparoscopic surgery training system,to overcome the gap between training and actual operation, and thus to reduce the complications in actual laparoscopic surgery. Meanwhile, individual virtual simulation of laparoscopic surgery system is also an open system.
2. Individual laparoscopic virtual visualization system is also at an early stage, it needs to continue to absorb the latest computer virtual reality technology in order to gradually improve its functions.
3. Three-dimensional reconstruction and virtual simulation technology have very important application value for hepatolithiasis laparotomy surgery and those patients underwent re-operation of this disseas also benefit from these technologies. Compared to general imaging technologies, three-dimensional reconstruction and virtual simulation technology have more advantages in the following areas such as showing stones' distribution accurately, displaying bile duct stenosises overall, discovering bile duct and/or vascular variations, analysis the reasons of stone recurrence specificly, providing accurate clinical classification and reasonable operation program,etc. Meanwhile simulation surgical procedures can also assess the feasibility and safety of the selected operation programs, provide guidance to actual surgical operations and thus improve the clinical efficacy of hepatolithiasis furthermore.
胆道系统结石病通常依结石所在的部位,分别称为胆囊结石、胆总管结石和肝胆管结石等。随着人民生活方式的改变和老龄化社会的到来,胆道结石病病谱构成正发生着改变,其中胆囊结石发病率呈逐年上升趋势。自20世纪80年代后期,腹腔镜胆囊切除术作为微创外科技术的代表,成为新世纪发展的潮流,使胆囊切除术从开放法手术时代进入到腹腔镜外科时代。然而腹腔镜胆囊切除术至今仍然并非平安无事,据统计其胆管损伤率仍在0.2-0.3%左右,由于接受此项手术治疗的患者数目众多,故做好腹腔镜胆囊切除术仍然是对外科医师培训上至关重要的事。虽然国内外已经出现了各种商业化的腹腔镜技术训练工具及虚拟手术机械,但大多仍停留在基础训练层面,难以实现个体化,因而也无法显著减少腹腔镜胆囊切除术的并发症发生。与此同时,对肝内外胆管结石的手术治疗则出现了两种不同的趋势,一方面是大部分胆总管结石及部分肝胆管结石已经可以在腹腔镜下实现微创化处理；而另一方面随着人们对肝胆管结石病病理改变认识的提高,肝胆管结石的开腹手术治疗趋向于联合多种手术方式,以达到“去除病灶,取尽结石,矫正狭窄,通畅引流,防止复发”的目的。因而如何进一步提高腹腔镜手术的安全性及如何合理有效地选择胆道系统结石病的手术方式问题成为摆在人们面前的两大现实问题,而这两大问题的实质仍然是如何对特定患者的手术治疗实现个体化选择。2003年本课题组采用数字化虚拟中国女性一号肝脏数据集和肝脏管道灌注标本CT薄层扫描数据进行三维重建和虚拟手术研究,随后开始利用64排螺旋CT腹部薄层扫描数据进行肝胆脾胰等脏器以及血管的计算机辅助三维重建及虚拟可视化手术研究。由于上述虚拟手术是基于患者特征性三维重建模型,因而实现了个体化的要求。课题组目前已对多种肝胆系统疾病包括肝癌、肝血管瘤、胰腺癌等实现了个体化的手术虚拟仿真,显示了其重要的临床应用价值。本研究即是将该技术及“个体化”的思想向胆道系统结石手术治疗的两大领域即腹腔镜和开腹手术的进一步延伸。
目的
1、研究可视化虚拟仿真技术在腹腔镜胆囊切除术、腹腔镜胆总管切开引流及左肝外叶切除术中的应用价值。
2、研究可视化虚拟仿真技术在复杂肝胆管结石手术方式合理选择及再次胆道手术中的临床应用价值。
方法
采用优化的64排螺旋CT扫描技术,收集胆囊结石、胆总管结石及肝胆管结石亚毫米图像数据,应用自主研发的,具有自主知识产权的腹部医学图像三维可视化系统(MI-3DVS)进行三维重建和辅助诊断；然后应用虚拟器械及仿真手术系统进行胆道系统结石病例的可视化仿真手术。
1、胆囊结石个体化腹腔镜虚拟可视化手术研究
1.1研究对象：患者,女,43岁,上腹痛反复发作10余年,诊断为“胆囊结石并慢性胆囊炎”。
1.2设备
64排螺旋CT—PHILIPS Brilliance64(荷兰PHILIPS公司)；图像后处理工作站为PHILIPS Brilliance64层螺旋CT自带的Mxview工作站；FreeForm Modeling System(美国SensAble Technologies公司)；力反馈设备PHANToM (PHANToM Desktop); ACDSee9 Message Center (ACD System Ltd.); MI-3DVS(自主研发。主机：内存2G、处理器2.0G*2Xeon 5130)。
1.3腹腔镜器械的设计开发
本研究在课题组前期简单开腹手术器械的基础上,进一步研究虚拟腹腔镜手术器械。具体方法包括3个步骤,即几何建模、运动建模及物理建模。在FreeForm Modeling System中应用带力反馈装置的PHANToM可操纵这些器械进行虚拟手术。我们设计开发的腹腔镜虚拟手术器械包括TORCAR、电凝钩、组织钳、钛夹钳、剪刀、胆道镜、超声刀等,电刀及剪刀赋予一定的组织切割功能。
1.4胆囊结石病例CT扫描参数的设定及数据存储
常规平扫时患者取仰卧位,头足方向,由膈顶至肝脏下缘,扫描条件120KV、250mAs；采用0.625x64排探测器组合,以层厚5mm、间隔5mm、螺距0.984、球管旋转一周时间0.5s。动脉期扫描延时时间为20-25s,门脉期为延时50-55s。扫描结束后将图像数据传至Mxview工作站,在Mxview工作站进行三期数据(平扫期、动脉期和门脉期)的刻盘存贮。格式为DICOM(Digital Imaging and Communications in Medicine)3.0,然后通过DICOM查看器将数据转换为BMP格式。
1.5图像分割及三维重建
本研究的分割方法采用阈值分割法与区域生长法,三维分割与二维分割相结合方式进行。利用MxliteView DICOM Viewer阅读64排CT扫描数据,调整适当的窗宽和窗位,并将以DICOM数据导出并转化成JPEG格式存盘,将JPEG文件导入ACDSee 9 Message Center转化成BMP文件,并调整图像大小后导入自主开发的MI-3DVS进行分割,分割后的图像文件进行三维重建,并以STL格式的文件输出,重建后的模型导入FreeForm Modeling System进行平滑和修饰。
1.5.1肝脏、胆道系统及腹腔血管图像分割
采用自行设计的分割软件MI-3DVS,以自适应的区域生长算法对肝脏、胆道系统及其周围血管系统进行序列分割,得到分割后的肝脏、胆道系统、腹主动脉、腹腔动脉及其分支、门静脉、肝静脉系统等的STL(STereo Lithography)格式数据。其中胆道系统及结石的分割要求尽量精准。胆囊结石患者胆囊内大多存在胆汁,由于胆汁密度与水接近,因而在CT扫描图像上胆囊底部、体部与周围组织存在较明显的密度差,采用同一域值下的自适应区域生长法进行图像分割较为理想；但胆囊颈及胆囊管由于解剖结构细小,且往往存在结石嵌顿,利用胆管与结石阈值的不一致性,采用胆管与结石在不同域值下分别分割的方式较为可行；对胆囊内充填性结石及萎缩性胆囊、因胆囊壁与结石间距离过小,采用同一域值下的自适应区域生长法单张或序列二维图像分割,胆囊结石患者肝外胆管及肝门部胆管多无扩张,图像分割存在较大困难,但上述结构对腹腔镜手术而言却又十分重要,我们采用对不同扫描期别图像进行多次胆道(肝门部胆管、胆囊管、胆总管)及结石的自动切割后,再利用系统自动整合功能,得到完整的胆道系统及结石分割STL数据。对于CT“阴性结石”,由于CT图像分辨率太低,则需参考B超结果定位,利用软件模拟出类似结石整合入胆囊,以求三维重建图像完整。
1.5.2胸腹壁组织及腹腔的分割
以自适应区域生长算法对胸腹壁组织包括皮肤、肋骨、胸骨、脊柱等进行序列分割,分别得到各组织的分割后的STL数据。
1.5.3胸腹壁、肝脏及其血管、胆道系统等的三维重建
将分割图像的STL格式数据导入FreeForm Modeling System进行平滑和去除一些燥声,然后系统根据各组织脏器的真实空间位置关系自动配置成一整套的脏器三维重建模型,对模型及各组成部分可以进行放大、缩小、旋转、透明等操作,全方位观察各结构或细节。
1.6腹腔镜手术环境建立及腹腔镜胆囊切除术仿真可视化
腹腔镜手术体位与开腹手术有所不同,利用FreeForm Modeling System图像旋转-移动工具可将腹壁及腹腔脏器三维重建模型设置左侧卧30°,头高脚低仰卧位,使与实际腹腔镜胆囊切除术体位一致。腹腔镜手术术者视角与开腹手术相比也较为固定,通常更接近水平前后位,有时为了显示特定组织结构,还可将30。镜进行旋转,利用FreeForm Modeling System水平及纵向旋转工具,以肚脐为参考点,将视角调整至水平30°角左右即可满足要求。此外以FreeForm Modeling System软件工作窗模拟腹腔镜手术显示器屏幕,通过对工作窗放大／缩小、左右平移等操作模拟摄像头进退、扫视及旋转等功能也较为方便。然后利用力反馈设备PHANTOM和自行开发设计的腹腔镜手术器械进行腹腔镜下胆囊切除术的重要手术步骤的虚拟仿真,与开腹手术相比,腹腔镜手术器械的活动范围受到TORCAR位置、腹膜腔范围、组织结构等的限制,虚拟仿真手术时也要求适应上述要求,但有时为了显示重要组织结构或重要手术步骤,可将胸腹壁或其他结构透明化,甚至暂时隐藏。
2、肝内外胆管结石个体化腹腔镜虚拟可视化手术研究
2.1、研究对象：患者,男,45岁,发现胆总管结石3年,上腹痛反复发作1年余,CT提示“左肝外叶胆管结石,胆总管结石,肝内外胆管扩张”。
2.2、患者64排CT原始扫描数据的采集、图像分割及三维重建同“1.4”及“1.5”。
2.3、腹腔镜器械的设计开发同“1.3”
2.4、腹腔镜手术环境建立同“1.6”,腹腔镜下虚拟胆总管切开取石引流及左肝外叶切除术手术步骤。
3、肝胆管结石三维重建及开腹手术仿真可视化研究
3.1研究对象：收集我院自2008年10月至2009年10月22例肝胆管结石患者64排螺旋CT数据,选其中代表性的4个病例进行分析说明：例1：叶XX,女性,ID：161510,53岁,腹痛反复发作10年入院,CT提示：左肝外叶内胆管结石。例2：谢XX,ID：115350,女性,45岁,因B超发现肝胆管结石3年余收入院,入院时CT提示：肝内胆管结石,肝胆管扩张积气。例3：李XX,ID：110230,女性,45岁,上腹痛反复发作1年余入院,CT提示：肝胆管显著扩张,左右肝内胆管及胆总管结石。例4：郑XX,ID：1316277,女性,52岁,上腹部反复疼痛发作十余年入院,CT提示：左、右肝内胆管结石及胆管扩张,胆总管结石。
3.2仪器与设备同“1.2”
3.3患者64排螺旋CT原始扫描数据的采集、图像分割、三维重建同“1.4”
3.4.肝胆管结石的可视化仿真手术
在FreeForm Modeling System中对三维重建模型及各组成部分进行放大、缩小、旋转、透明等操作,全方位观察各结构或细节,根据结石分布、胆道系统及肝脏病变情况选择合理手术预案,利用力反馈设备PHANTOM和自行开发设计的开腹手术器械进行肝胆管结石的仿真可视化手术,以确定手术预案可行性,并与实际手术情况对照,以探究该技术的临床应用价值。
4、再次手术肝胆管结石三维重建及仿真可视化研究
4.1研究对象：收集我院自2008年10月至2010年1月20例再次肝胆管结石患者64排螺旋CT数据,选其中代表性的3个病例进行分析说明：例1：吴XX,ID：1145376,女性,45岁,上腹部疼痛反复发作10余年入院,5年前于外院行“胆道探查术”(具体手术方式不详),CT提示：左肝内胆管结石,肝门部低密度灶性质待查。例2：黎XX,ID：1195132,女性,56岁,因上腹痛反复发作10余年,再发加重1天入院,既往有2次胆道手术史(手术方式均为胆总管切开探查取石引流术),CT提示：左、右肝内胆管及胆总管结石,肝内外胆管扩张。例3：伍XX,ID：1293786,女性,46岁,因上腹痛反复发作8余年,再发加重10天入院,既往有2次胆道手术史(手术方式均为胆总管切开探查取石引流术),CT提示：肝内外胆管扩张,肝内结石弥漫分布,胆总管巨大结石。
4.2仪器与设备同“1.2”
4.3患者64排螺旋CT原始扫描数据的采集、图像分割、三维重建同“1.4”
4.4再次手术肝胆管结石患者的可视化仿真手术
在FreeForm Modeling System中对三维重建模型及各组成部分进行放大、缩小、旋转、透明等操作,全方位观察各结构或细节,根据结石分布、胆道系统及肝脏病变情况力求找出结石复发的原因,并选择合理手术方案,利用力反馈设备PHANTOM和自行开发设计的开腹手术器械进行肝胆管结石的虚拟仿真手术,以确定手术预案可行性,并与实际手术情况对照,以探究该技术的临床应用价值。
结果
1、胆囊结石个体化腹腔镜虚拟可视化手术研究
1.1、腹腔镜手术器械的设计开发
在FreeForm Modeling System建立的手术虚拟环境中,在原有的开腹手术器械库的基础上,本研究进一步自主研制的腹腔镜仿真器械形态逼真且有力反馈感受,可以完成简单的腹腔镜腔内操作。这些器械包括：气腹针、电凝钩、锥鞘、超声刀、钛夹钳等,然后利用力反馈设备PHANTOM和自行开发设计的腹腔镜手术器械进行腹腔镜下仿真手术,整个仿真手术过程有力反馈的感受,与临床过程所见相符合。
1.2、腹部脏器及胸腹壁组织图像分割与三维重建
胆囊结石患者64排螺旋CT薄层扫描数据集,获得676层CT扫描图像。图像分为平扫期、动脉期、静脉期、门静脉期,各期均含有患者特定的解剖学信息,可分别用于进行图像的分割及三维重建,并相互参考补充。
1.2.1肝脏及其周围血管系统图像分割
肝脏模型能真实反映肝脏的实际体积和肝脏的解剖标志,并且通过调节肝脏的透明度可同时显示肝脏和肝内的动脉、静脉、门静脉各分支。腹主动脉、腹腔动脉及其分支胃十二指肠动脉、双肾动脉、胃右、左动脉、肝固有动脉、脾动脉、肠系膜部分动脉等结构,形态逼真,立体感强,尤其是胆囊周围动脉的迂曲走行,较解剖图谱的表示更加立体和真实。门静脉系统显示肝外的主干和脾静脉、肠系膜上静脉,肝内门静脉系统能清楚显示门静脉的左主干和右主干,以及各叶、段的分支。
1.2.2胆道系统及结石的图像分割及三维重建
数据导入MI-3DVS,以自适应区域生长图像分割法通常能一次性完整分割胆道系统,对一些细微结构如胆囊管与胆总管汇合部、不扩张的肝门部胆管等,可利用数据集的不同期别图像如平扫期、动脉期、静脉期、门静脉期等,分别对各期胆道系统进行图像切割,再利用系统自动整合功能将各期所含特定解剖学信息整合为完整的胆道三维图像,使重建的胆道系统模型能更真实反映胆囊与胆总管及左右肝管的空间位置关系,胆道系统三维模型与腹腔脏器及血管模型整合后,对腹腔镜手术有重要解剖学意义的胆囊三角、肝十二指肠韧带、右肝门等区域的结构特点便可一目了然。
1.2.3胸腹壁图像切割及三维重建
重建的胸腹壁模型立体感强,且具皮肤纹理,对腹腔镜手术具有定位意义的重要解剖结构如肚脐、双侧肋弓、剑突角等清晰可辨。当胸腹壁透明度设置为0时,可以完全显示腹腔内各脏器和腹腔血管结构。
1.3腹腔镜手术环境建立
以FreeForm Modeling System软件工作窗模拟腹腔镜手术显示器屏幕,利用FreeForm Modeling System图像旋转-移动工具改变腹壁及腹腔脏器三维重建模型位置以设置所需手术体位。利用FreeForm Modeling System水平及纵向旋转工具,以肚脐为参考点,将视角调整至水平30°角左右,通过对工作窗放大／缩小、左右平移等操作模拟摄像头进退、扫视及旋转等功能,效果与实际腹腔镜下操作相似。有时为了显示重要组织结构或重要手术步骤,可将胸腹壁或其他结构透明化,或暂时隐藏,以体现虚拟仿真手术的优点及灵活性。但腹腔镜手术的气腹建立过程由于三维模型目前还没有弹性变形能力,因而暂时还无法虚拟。
1.4腹腔镜胆囊切除术可视化仿真手术过程
1.4.1手术体位设置：利用FreeForm Modeling System图像旋转-移动工具将腹壁及腹腔脏器三维重建模型设置左侧卧30度,头高脚低仰卧位,使与实际腹腔镜胆囊切除术体位一致。
1.4.2设置各TORCAR位置：首先于脐周建立1.0cmTORCAR作观察孔,置入摄像杆,然后于剑突下建立1.0cmTORCAR作主操作孔,右侧锁骨中线与右侧肋弓交界处建立0.5cmTORCAR作辅操作孔。
1.4.3腹腔镜胆囊切除术手术步骤虚拟
腹腔镜虚拟环境下激活胆道系统模型,并定义其力反馈强度大小,使用PHANToM操纵电凝钩、组织钳、剪刀、抓钳等虚拟腹腔镜器械完成胆囊三角显露、胆囊管及胆囊动脉夹闭及切断、分离胆囊床、取出胆囊标本等手术步骤,整个仿真过程与实际手术过程相似。
2、肝内外胆管结石个体化腹腔镜虚拟可视化手术研究
2.1肝胆管结石患者64排螺旋CT采集、图像分割及三维重建同结果“1.2”
2.2腹腔镜手术器械的设计开发同结果“1.1”
2.3腹腔镜肝内外胆管结石手术可视化过程
2.3.1手术体位设置：利用FreeForm Modeling System图像旋转-移动工具将腹壁及腹腔脏器三维重建模型设置左侧卧30度,头高脚低仰卧位,使与实际腹腔镜胆道手术体位一致。
2.3.2设置各TORCAR位置：首先于脐周建立1.0cmTORCAR作观察孔,置入摄像杆,然后于剑突下及左肋缘下建立1.0cmTORCAR作主操作孔,右侧锁骨中线、右腋前线与右侧肋弓交界处分别建立0.5cmTORCAR作辅操作孔。
2.3.3腹腔镜下虚拟手术过程,包括：胆囊切除、胆总管前壁切开取石、胆道镜探查胆总管并取石、腹腔镜下左肝外叶切除、胆总管T管及腹腔引流管放置等,手术过程与临床实际相比有较高仿真度。
3、肝胆管结石三维重建及开腹手术仿真可视化研究
3.1肝胆管结石患者64排螺旋CT采集、图像分割及三维重建同结果“1.2”
患者三维重建模型形态逼真,解剖结构位置正确,肝内各管道系统的空间位置关系直观可辨。通过对模型的透明阈值设定及多方位旋转,可全面了解结石分布、胆管系统及肝实质病变情况以及病灶与周围组织的相互关系等,还可明确肝动脉、门静脉及肝静脉的变异类型等。
3.2.虚拟仿真手术过程及手术实际情况
在虚拟手术环境中,患者三维重建模型能通过放大、缩小、旋转及透明化等操作进行多方位、多角度地观察,明确肝内结石分布、胆道系统与肝脏大体形态改变及肝内血管树改变等情况,据此对肝胆管结石进行临床分型及选择最佳手术方式,然后仿真可视化上述手术过程,并指导实际手术过程。
例1三维重建结果显示：结石分布于左肝外叶及胆总管,左肝外叶肝实质萎缩,左肝静脉闭塞,右副肝管变异等。患者临床分型为Ⅱb型+E型,三维重建拟定手术方式为：胆囊切除+胆总管切开取石T管引流术+左肝外叶切除术。仿真可视化上述手术过程顺利,上述手术方案安全可行,但要注意保护右副肝管及肝中静脉,手术存在一定风险。患者接受手术,术后恢复顺利。
例2三维重建结果显示：结石分布于右肝后叶及右肝管,右肝后叶胆管扩张及开口部狭窄,肝门部胆管汇合处狭窄,尾状叶胆管汇合变异及右肝动脉压迫肝总管等。患者临床分型为Ⅱb型+Eb型,拟定手术方式为：胆囊切除+肝方叶切除+肝门部胆管切开整形+胆总管横断式胆肠吻合术。经仿真可视化上述手术方案,右肝后叶胆管开口部在肝方叶切除后可顺利切开整形,而且不会损伤肝中静脉,手术目的可以达到。此患者目前尚未接受手术。
例3三维重建结果显示：肝内外胆管高度扩张,结石分布于左右肝内胆管及胆总管,无肝内胆管狭窄及肝实质萎缩。患者临床分型为Ⅲa型+E。型,拟定手术方式为：胆囊切除+胆总管切开取石+侧-侧胆肠吻合术。仿真可视化上述手术方案,认为手术方案安全可行。因患者结石易于复发,亦可考虑行皮下盲襻式胆肠吻合术作为预备手术方案。患者接受手术,术中情况与虚拟手术所见相似,患者术后恢复顺利。
例4三维重建结果显示：肝内外胆管高度扩张,胆囊结石,胆管结石分布于左肝外叶、右肝管及胆总管。患者临床分型为Ⅱa型+Ea型,拟定手术方式为：胆囊切除+胆总管切开取石引流+肝左外叶切除+侧-侧胆肠吻合术。虚拟手术过程显示手术安全可行。患者接受手术,术后恢复顺利。
4、再次手术肝胆管结石三维重建及仿真可视化研究
4.1肝胆管结石患者64排螺旋CT采集、图像分割及三维重建同结果“3.1”
4.2.虚拟仿真手术过程及手术实际情况
在虚拟手术环境中,通过对3D模型及其附件的放大、缩小、旋转及透明化等操作进行多方位、多层次观察,可明确肝内结石分布、胆道系统与肝脏大体形态改变等情况,然后针对上述病理改变及结石复发原因确定手术方案；通过仿真可视化上述手术过程,明确手术方案的可行性,并指导临床实际手术过程。
例1三维重建结果显示：结石分布于左肝外叶,左肝内胆管囊状扩张及左肝管开口部环状狭窄,胆总管内无结石,肝门部低密度灶为与胆道吻合之肠管。患者临床分型为Ⅱa型,结石复发原因为遗留肝内胆管狭窄及不适当的胆肠吻合术。拟定手术方式为：左肝外叶切除+胆-肠吻合拆除重建+左肝管切开整形。仿真可视化手术过程中发现从左肝外叶切除后裸露之左肝外叶胆管断端内即可将左肝管狭窄部切开整形,如此则既可经此途径探查胆总管及原胆-肠吻合口,又可保留左肝外叶肝组织。实际手术证实了仿真手术过程发现的正确性,术中探查原胆肠吻合口十分通畅,胆总管下端无结石,因而免于拆除胆-肠吻合拆除重建。患者术后恢复顺利。
例2三维重建结果显示：结石分布于左肝外叶及胆总管,肝内外胆管扩张,左肝管汇合变异,左肝外叶肝实质萎缩,门静脉左支及左肝静脉闭塞等。患者临床分型为：Ⅱa型+E型,结石复发原因为首次手术遗留肝内胆管、血管畸形未予纠正。拟定手术方式为：左肝外叶切除+胆管整形+胆-肠吻合术。实际术中证实三维重建诊断结果正确,手术计划顺利实现。患者接受手术,术后恢复顺利。
例3三维重建结果显示：结石分布于左、右肝内胆管及胆总管,肝内外胆管扩张,肝内胆管无狭窄。患者临床分型为Ⅲa型+E型,结石复发原因为既往手术未解决肝内及胆总管胆汁郁滞问题。拟定手术方式为：左肝外叶切除+右肝后叶切除+肝胆管切开取石+侧-侧胆肠吻合。实际手术顺利完成预定手术计划,患者术后恢复顺利。
结论
1、个体化腹腔镜虚拟可视化手术系统能成功完成腹腔镜胆囊切除术、腹腔镜胆总管切开取石引流及左肝外叶切除术手术过程,其“个体化”的特点有利于克服普通腹腔镜训练系统训练与实际手术操作间脱节的缺点,从而提高腹腔镜技术培训效果,减少实际腹腔镜手术术中并发症的发生。
3、个体化腹腔镜仿真可视化手术系统尚处于研究的初级阶段,需要继续吸收计算机虚拟现实技术的最新成果以逐步完善其功能。
3、三维重建及仿真可视化手术技术对肝胆管结石开腹手术及再次手术在准确显示结石分布范围、胆管狭窄部位、胆管和／或血管变异,分析结石复发原因,正确临床分型及合理选择手术方案等方面均具有重要价值；而且仿真手术过程还可评估所选手术方案的可行性及安全性,为临床实际手术操作提供指导,从而进一步提高肝胆管结石病的临床疗效。
Background
Biliary lithiasis,including gallbladder stones, common bile duct stones, intrahepatic bile duct stones and so on. With the people's lifestyle changes and the arrival of aging society, constitute spectrum of biliary calculus disease are changing, in which the incidence of cholelithiasis showed an upward trend year by year. For cholelithiasis,since the late 80's of 20th century, laparoscopic cholecystectomy,as the representative of minimally invasive surgical techniques, have become the development trend of new century, and bring the treatment of cholelithiasis from the open cholecystectomy era of surgery into the era of laparoscopic surgery. However, Laparoscopic cholecystectomy is still not without incident today, according to statistics,its bile duct injury rate is still about 0.2%-0.3%. As the acceptance of laparoscopic cholecystectomy is on an increasing number, strengthening the training of laparoscopic cholecystectomy is still very important to the training of surgeons.Although there have been a variety of domestic and foreign commercial virtual laparoscopic surgical training machines, but most of them is still at the basic training level, and difficult to achieve individual and thus could not significantly reduce the complications of laparoscopic cholecystectomy occurred. At the same time, for the surgical treatment of bile duct stones, there have been two different trends recently. On the one hand, most of the common bile duct stones and some of the intrahepatic bile duct stones have been able to achieve minimally invasive laparoscopic treatment,On the other hand, due to people's understanding of pathological changes of intrahepatic bile duct stones were more and more detailed, open surgery of intrahepatic bile duct stones tended to be a joint model of a variety of surgical method in order to achieve the purpose of "remove the lesion, taking every stones, corrected narrow, unobstructed drainage and prevent recurrence". Thus,how to further enhance the safety of laparoscopic surgery and how to choose a reasonable and effective surgical method for biliary lithiasis have become the two major practical problems for surgeons.However, The essence of these two major issues remained how to achieve a individualized surgical treatment for specific patients with biliary lithiasis.In 2003, our research group performed 3-dimensional reconstruction and simulation surgery based on data collected from CT scanning of a digitalized virtual female Chinese No.1 liver perfusion specimen. Later, our study was extended to 3-dimensional reconstruction and visible simulation surgery of the liver, pancreas, gallbladder, spleen, and vascular system based on 64-slice helical CT scanning data. At present, we were able to perform individualized Visible Simulation Surgery of hepatobiliary diseases, including liver cancer and pancreatic cancer etc. This current study addressed the utilization of visible simulation surgery and the "individual-oriented" thinking on the two areas of minimally invasive and laparotomy surgery for biliary lithiasis.
Objectives
This study aims:1) to establish individual-based virtual simulation laparoscopic surgery system based on the virtual simulation technology, and explore the application value of the system by using of force feedback devices and virtual laparoscopic surgical instruments to complete the virtual laparoscopic cholecystectomy,laparoscopic bile duct incision and liver resection, etc.2) bring the virtual simulation technology into the laparotomy treatment for complex hepatolithiasis, and to explore its clinical application value at the options of reasonable surgical method choice and re-biliary-tract surgery.
Methods
1 Study of individual laparoscopic surgery virtual visualization System for gallbladder stone disease
1.1 The object of study:the patient, female,43 years old, recurrent upper abdominal pain for more than 10 years, diagnosed as "gallstones and chronic cholecystitis."
1.2 Equipment:the software included ACDSee9 Message-Center (ACD System Ltd), MI-3DVS (self-developed), Free-Form Modeling System (Sens-Able Technologies, Inc.USA). The hardware included PHANTOM (PHANTOM Desktop), Main computer:memory 2G; Xeon 5130 processor 2.0G*2.
1.3 Development of laparoscopic simulation surgical instruments
On the basis of previous studies, simulation surgical instruments were developed through three steps, such as geometry modeling, movement modeling and physical modeling. The laparoscopic simulation surgical instruments included laparoscopic surgery TORCAR, electro-coagulation hook, organization pliers, titanium clamp, scissors, cholangioscopy, ultrasonic knife,etc. Virtual laparoscopic basic surgical operation was carried out using force feed-back devices of Phantom with particle-spring-damper force feedback model in Free-Form Modeling System.
1.4 CT scanning and data collection of biliary lithiasis
The patients were scanned from the top of diaphragm to the lower edge of liver in supine position. The CT scanner settings involved 250mAs,120KV, and thickness of 5mm, interval of 5mm,0.984 pitch, and rotation speed of 0.5S/cycle. Scanning was delayed 20 to 25S after arterial phase,50 to 55S after venous phase. Then data were transferred to Mxview working station. Data of plain scan, arterial venous phase, portal vein phase were stored in Mxview working station. Its format was transferred from DICOM to BMP.
1.5 CT image segmentation and 3-dimension reconstruction
1.5.1 Segmentation of liver,biliary system and abdominal vascular system image
Data of hepatic tissue, bile duct system and abdominal vascular system were processed by a self-developed Medical Image Processing System. This Medical Image Processing System uses a self-adaptive region growing algorithm to segment previous tissues' images consecutively and obtained data in Stereo Lithography format. In which segmentation of biliary system and the stone image required accurate as far as possible. In common conditions, the segmentation of gallbladder and the stone image were more satisfied, because the density of gallbladder bile quite different with the surrounding tissue. But when the gallbladder filled by stones, atrophic gallbladder,stone incarcerated within gallbladder neck and cystic duct,especially gallbladder neck and cystic duct structure was small, or hepatic portal bile duct was non-expanded, image segmentation became more difficult, In such cases,image segmentations to different stage of CT data were carried out, and by complement each other, get a complete system and biliary stones STL data.
1.5.2 Abdomen and abdominal wall tissue segmentation Standard Template Library data of the abdominal wall tissue including skin, ribs, sternum, spine aorta were obtained by a 3-dimensional dynamic region growing method.
1.5.3 3-dimensional reconstruction of liver, bile duct systems,vascular
system,abdominal wall,etc.
Data of liver, bile duct systems,vascular system,abdominal wall in Standard Template Library format were introduced to the Freeform Modelling system to be smoothed and noise was eliminated. Then images of the liver and bile duct systems were reconstructed,Then the system configured them into a set of three-dimensional reconstruction organs model according to their real space location of the organization automatically,and we can zoom, rotate, transparency the different components of the model to observe the structure or details.
1.6 Laparoscopic surgery scenario building and laparoscopic surgery virtual simulation
Laparoscopic surgery position is different from laparotomy, set the position of abdominal wall and abdominal viscera three-dimensional reconstruction model is similar to the actual position of laparoscopic cholecystectomy.Set the viewing angle of laparoscopic surgery to 30-degree using Freeform Modeling System Image Rotation-Move tool. Furthermore, laparoscopic surgery display screen is simulated by Freeform Modeling System software work window. Through the window zoom in/out, pan around analog cameras advance and retreat, glance, and rotation functions.Then use the PHANTOM force feedback devices and self-developmented laparoscopic surgical instruments for the virtual simulation of laparoscopic cholecystectomy.Compared with laparotomy, the scope of activities of laparoscopic surgical instruments was limited by TORCAR location, range of peritoneal cavity, organizational structure and other constraints, the virtual simulation of surgery was also required to adapt to these requirements, But sometimes in order to show an important organizational structures or major surgical procedures, abdominal wall or other structure can be transparent, or even temporatedly hidden.
2 study of individual laparoscopic surgery virtual visualization system for patient with intrahepatic and extrahepatic stones
2.1 The object of study:the patient, male,45 years old, found stones in common bile duct three years ago, and recurrent abdominal pain for more than a year, CT NOTE:left lateral lobe of liver bile duct stones, common bile duct stones, bile ducts expansion"
2.2 Original 64-slice CT scan data collection, image segmentation and three-dimensional reconstruction This step was in agreement with "1.4."。
2.3 Laparoscopic instrument design and development This step was in agreement with "1.3"
2.4 Laparoscopic surgery scenario building and laparoscopic surgery virtual simulation This step was in agreement with "1.6", by using virtual laparoscopic instruments simulate, the major surgical procedures of laparoscopic common bile duct incision and hepatic left lateral lobectomy were simulated.
3 Applications of three-dimensionnal reconstruction and virtual simulation technique to intrahepatic caculi
3.1 The object of study:to collect 64-slice spiral CT data of four cases from 22 cases of bile duct stones patients in our hospital from October 2008 to October 2009: Example 1:XX patient, ID:161510,female,53 years old, recurrent abdominal pain for 10 years. CT NOTE:left hepatic bile duct stone. Example 2:XX patient, ID:115350,female,45 years old, bile duct stones found three years ago, CT NOTE: intrahepatic bile duct stones, bile duct expansion, gas in intrahepatic bile duct. Example 3:XX patients, ID:110230,female,45 years old, recurrent abdominal pain for more than one year. CT NOTE:a significant expansion of bile duct, left/right intrahepatic bile duct and common bile duct stones. Example 4:XX patients, 1316271,female,52 years old, for upper abdominal pain recurring more than 10 years admitted to hospital, CT Tip:left and right hepatic bile duct contained stones, expanded common bile duct exists stones.
3.2 Apparatus and equipments were similar to the "1.2"
3.3 64-slice spiral CT original scan data acquisition, image segmentation,3D reconstruction were similar to the "1.4"
3.4 Visible simulation surgery for intrahepatic calculi
The Free-Form Modelling System was used to reconstruct 3-dimensional models of viscera according to their real spatial position. The stereo model and its components could be amplified, deleted, rotated, and hyalinized to clarify the anatomical character of tissue structures, calculi distribution, bile duct stricture and deformity, vascular arrangement, and parenchymal lesions from omni-direction, multi-angle, and different levels. Then, according to the Chinese Guideline of Hepatobiliary Calculi Diagnosis and Treatment, we classified the disease and determined the optimal operation planning. Finally, simulated operations were performed in the Free-Form Modelling System by a force feed-back instrument (PHANTOM). The simulated operation helped us to predict the difficulties that may be encountered in the real operation process and what precautions to take.
4 Applications of three-dimensionnal reconstruction and virtual simulation technique to reoperational patients of intrahepatic caculi
4.1 The object of study:to analysis 3 cases underwent biliary reoperatons: Example 1:XX patients, ID1145376,female,45 years old, upper abdominal pain recurrence for more than 10 years, accepted"bile duct exploration" (the specific surgical method unknown) five years ago, CT Tip:left intrahepatic bile duct stones, a hilar low-density lesion unknown nature existed. Example 2:XX patients, ID:1195132,female,56 years old, recurrent upper abdominal pain for more than 10 years, and underwent biliary tract surgery two times (both common bile duct exploration and T-tube drainage), CT Tip:stones filld in left, right hepatic bile duct and common bile duct. Example 3:XX patients, ID:1293786,female,46 years old, recurrent upper abdominal pain for more than eight years, there were two times history of biliary tract surgery (common bile duct exploration and T-tube drainage), CT Tip:expansion of intra-and extrahepatic bile duct, intrahepatic stones were scattered, large common bile duct stones.
4.2. Apparatus and equipment were in agreement with the "1.2"
4.3 original 64-slice spiral CT scan data acquisition, image segmentation,3D reconstruction were in agreement with the "1.4"
4.4. virtual surgery for reoperations of Intrahepatic bile duct stones this part was similar to "3.4"
Results
1 Study of individual laparoscopic surgery virtual visualization System for gallbladder stone disease
1.1 Design and development of laparoscopic surgical instruments
The virtual laparoscopic instruments in this study could complete some simple laparoscopic operation procedure by a force feed-back instrument (PHANTOM), the feedback powerful feelings and findings of the simulation of surgical procedures were consistent with the clinical process.
1.2 Abdominal organs and abdominal wall tissue image segmentation and three-dimensional reconstruction
1.2.1 Liver and peripheral vascular system image segmentation
The hepatobiliary tract model was segmented with the Medical Image Process System, after smoothing with the Free-Form Modelling System, and its structure become clearer and all of the structures including the bile duct, hepatic artery, hepatic vein, portal vein, and calculi were reconstructed in 3-dimensions successfully.
1.2.2 Biliary system and the stone image segmentation and three-dimensional reconstruction
The biliary system model can more truly reflect the relationship between gallbladder,common bile duct and the left/right hepatic bile duct Three-dimensional model of biliary system, abdominal organs and vascular models with integrated, the structures of triangle gallbladder, liver duodenum ligament and right hepatic door could be seen clearly, their structural characteristics were very important for laparoscopic surgery. 1.2.3 Abdominal wall image segmentation and three-dimensional reconstruction
The thoraco-abdominal wall model were clear, strong stereo and had skin texture appearance, and the structures which had significant value for laparoscopic surgery such as the navel, bilateral costal arch, xiphoid angle could be seen clearly. When the transparency of abdominal wall model was set to 0, the abdominal organs and abdominal vascular structure could be fully displayed. In order to observe the details from different ranges, such as zooming in, zooming, and rotation operations could be taken.
1.3 The establishment of laparoscopic surgery scenario
Set the position of abdominal wall and abdominal viscera three-dimensional reconstruction model similar to the actual position of laparoscopic cholecystectomy, and set the viewing angle of laparoscopic surgery to 30-degree using FreeForm Modeling System Image Rotation-Move tool. Then use the PHANTOM force feedback devices and self-developmented laparoscopic surgical instruments to simulate laparoscopic basic procedures. Sometimes, in order to show an important organizational structures or major surgical procedures, abdominal wall or other structure could be transparent, or even temporarily hidden.
1.4 Laparoscopic visualization of basic laparoscopic surgical operation
In the laparoscopic virtual environment,using PHANToM manipulate the "electrocoagulation hook", "titanium clamp", "scissors", "grasping forceps" and other virtual laparoscopic insruments to complete the main process of laparoscopic cholecystectomy.including:gallbladder triangle revealed, cystic duct and cystic artery occlusion and cut off, separation of the gallbladder bed, remove the gallbladder specimens,ect. The whole simulation process was similar to the actual surgical procedure.
2 study of individual laparoscopic surgery virtual visualization system for patient with intrahepatic and extrahepatic stones
2.1 64-slice spiral CT acquisition, image segmentation and three-dimensional reconstruction
The result was Similar to the result "1.2"
2.2 Design and development of laparoscopic surgical instruments
The result was similar to the result "1.3"
2.3 Laparoscopic surgery visualization process for hepatolithiasis
2.3.1 Surgery position settings:In the laparoscopic virtual environment, the position of abdominal wall and abdominal viscera three-dimensional reconstruction model was similar to the actual position of laparoscopic cholecystectomy.
2.3.2 Set the location of the TORCARS:First, the establishment of 1.0cm TORCAR for observation at the Cullen hole, placed in camera shot. Then set the location of disposes hole (1.0cmTORCAR) and two auxiliary holes (0.5cmTORCAR) under xiphoid and left/right ribs.
2.3.3 Main process of laparoscopic surgery for hepatolithiasis in the laparoscopic virtual environment
Including:Cholecystectomy steps, Common bile duct incision and take Stones, Choledochoscopic exploration and take stones from common bile duct, Laparoscopic hepatic left lateral lobectomy steps, Common bile duct T tube and peritoneal drainage tube placement ect. The whole simulation process was similar to the actual surgical procedure.
3 Applications of three-dimensionnal reconstruction and virtual simulation technique to intrahepatic caculi
3.1 64-slice spiral CT acquisition, image segmentation and three-dimensional reconstruction
The result was Similar to the result "1.2",and the 3-dimensional model could be amplified, rotated, and hyalinized to clarify the anatomical character of tissue structure with omni-directional, multi-angle, and multi-level views. After we localized the intrahepatic calculi and determined the calculi shape, deformity or stricture of the bile tract system, the distribution of the intrahepatic vessel system, and parenchyma lesions, an optimal surgical option was chosen.
3.2. Virtual reality of surgical procedures and actual surgical conditions.
Case1:3-dimensional reconstruction revealed that the stones were localized in the bile duct of left lateral lobe, and no stones were present in the caudate lobe. This case was defined as typeⅡb+E of hepatobiliolithiasis and a left lateral lobectomy, cholecystetomy, choledochotomy, and T-tube drainage was recommended. the program was proofed feasible and safe by virtual simulation technology, but to protect the deputy right hepatic duct and liver vein were very important, there are certain risks in these surgical steps. The patient recovered uneventfully after operation.
Case 2:This case was defined as typeⅡb+Eb hepatobiliary lithiasis according 3-D reconstruction and CT film, we could see that the junction of the bilateral hepatic duct was narrowed, the opening of the right posterior bile duct was narrowed, and the bile duct of the right and left caudate lobe entered the right hepatic bile duct ect. We choose to perform 1st and 2nd grade choledochoplasty and choledochojejunostomy. Because first hepatic hilum was high, quadrate lobectomy was essential to expose hepatic hilum. Because air in the intrahepatic bile duct suggested sphincter of Oddi dysfunction, cholecystectomy, choledochotomy, and common bile duct exploration were necessary. the program was proofed feasible and safe by virtual simulation technology. At present the patient has not yet accepted operation.
Case 3:3-dimensional reconstruction revealed that stones were found in left/right intrahepatic bile duct and extrahepatic bile duct. The intrahepatic bile duct was markedly dilated and the hilar bile duct did not appear to be narrowed, This case was defined as typeⅢa+Ea hepatobiliary lithiasis. The best surgical option was cholecystectomy, choledocholithotomy of the common bile duct, and hepatic hilum and choledochojejunostomy. And the Patient underwent surgery, intraoperative situation is similar to the virtual surgical findings, the patient recovered uneventfully after operation.
Case 4:3-dimensional reconstruction revealed that stones were found in left/right intrahepatic bile duct and extrahepatic bile duct. and the stones of right intrahepatic bile duct in this case were secondary stones.This case was defined as typeⅡa+Ea hepatobiliary lithiasis, The best surgical option was cholecystectomy, choledocholithotomy of the common bile duct, and left lateral lobectomy, intraoperative situation is similar to the virtual surgical findings, the patient recovered uneventfully after operation.
4、Applications of three-dimensionnal reconstruction and virtual simulation technique to reoperational patients of intrahepatic caculi
4.1 64-slice spiral CT acquisition, image segmentation and three-dimensional reconstruction
The result were Similar to the result "3.1".
4.2 Virtual reality of surgical procedures and actual surgical conditions.
The 3-D models could be amplified, rotated, and hyalinized to clarify the anatomical character of tissue structure with omni-directional, multi-angle, and multi-level views. After we localized the intrahepatic calculi and determined the calculi shape, deformity or stricture of the bile tract system, the distribution of the intrahepatic vessel system, and parenchyma lesions, the reasons of bile duct stones recurrence was analysised, and then a reasonable surgical method was determinded according to the reasons. Finally,virtual above-mentioned surgical procedures were taken and to guide the actual surgical procedure.
case 1:Three-dimensional reconstruction results:stones were found in the left hepatic lobe, and the left intrahepatic bile duct was in cystic dilatation state, the opening of left hepatic duct was narrow, no stones within common bile duct low-density lesion nearby hilar bile duct maybe the bowel anastomosised with the bile duct, etc.This case was defined as typeⅡb of hepatobiliolithiasis according to results of 3-D,the reasons of stone recurrence were left intrahepatic duct stricture and inappropriate choledochojejunostomy.The rational surgical method as follows:left lateral lobectomy, bile-intestinal anastomosis demolition and reconstruction. In Virtual surgery, we found that we could cut and shaped the bile duct stricture from the bile duct stump,and then took exploration from this way, found the opening of biliary-enteric anastomosis is very smooth,and none stones in the common bile duct,thus the step of bile-intestinal anastomosis demolition and reconstruction was canselled, the patient recovered uneventfully after operation.
case 2:Three-dimensional reconstruction showed that:The stones were found in the left lobe and extrahepatic bile duct, intrahepatic bile duct system was dilatation, and bile duct variation existed in the left hepatic lobe.3-D model also showed that left hepatic lobe of liver was atrophied, and left portal vein and left hepatic vein were occlusioned and so on.According to the 3-D results,this case was defined as typeⅡa+E of hepatobiliolithiasis, the reasons of stones recurrence were malformations of intrahepatic bile ducts and vascular which were not corrected in the first operation. A reasonable surgical method as follows:left lateral lobectomy of the liver,bile duct plastic,bile-intestinal anastomosis. Actual surgery confirmed the malformations of intrahepatic bile ducts and vascular and achieve surgical planning, the patient recovered uneventfully after operation.
case 3:Three-dimensional reconstruction results:stones existed in the left, right hepatic duct and common bile duct, intrahepatic and extrahepatic bile ducts were expanded, intrahepatic bile duct system had no stenosises. According to the 3-D results,this case was defined as typeⅡa+E of hepatobiliolithiasis, the reasons of Stones recurrence were cholestasis in intrahepatic and common bile duct. A reasonable surgical method as follows:left lateral lobectomy of the liver, right posterior hepatic lobectomy, common bile duct incision,side-side biliary-enteric anastomosis, the actual surgery completed the scheduled surgical planning successfully, and the patient recovered uneventfully after operation.
Conclusions
1. The individual laparoscopic virtual visualization system was able to establish a realistic scenario of laparoscopic surgery, complete successfully the major surgical procedures of laparoscopic cholecystectomy, laparoscopic bile duct exploration and left hepatic lobectomy. The self-developed virtual laparoscopic surgical instruments have vivid image, can increase the visual effect of surgical simulation. The "individual" features of this system can help practitioners to avoid the mind-set from the common laparoscopic surgery training system,to overcome the gap between training and actual operation, and thus to reduce the complications in actual laparoscopic surgery. Meanwhile, individual virtual simulation of laparoscopic surgery system is also an open system.
2. Individual laparoscopic virtual visualization system is also at an early stage, it needs to continue to absorb the latest computer virtual reality technology in order to gradually improve its functions.
3. Three-dimensional reconstruction and virtual simulation technology have very important application value for hepatolithiasis laparotomy surgery and those patients underwent re-operation of this disseas also benefit from these technologies. Compared to general imaging technologies, three-dimensional reconstruction and virtual simulation technology have more advantages in the following areas such as showing stones' distribution accurately, displaying bile duct stenosises overall, discovering bile duct and/or vascular variations, analysis the reasons of stone recurrence specificly, providing accurate clinical classification and reasonable operation program,etc. Meanwhile simulation surgical procedures can also assess the feasibility and safety of the selected operation programs, provide guidance to actual surgical operations and thus improve the clinical efficacy of hepatolithiasis furthermore.
引文
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