张 磊,俞万钧
(1.宁波大学医学院,浙江 宁波 315211;2.宁波大学医学院附属鄞州医院呼吸科,浙江 宁波 315040)
气道超声在肺部疾病中的临床应用及进展
张 磊1,2,俞万钧2*
(1.宁波大学医学院,浙江 宁波 315211;2.宁波大学医学院附属鄞州医院呼吸科,浙江 宁波 315040)
气道内超声(EBUS)已成为各种肺部疾病重要的诊断工具。EBUS可指导肺外周病变经支气管肺活检(TBB),同时也可指导肺门纵隔淋巴结或肿块进行经支气管针吸活检术(TBNA),因此EBUS-TBB和EBUS-TBNA对于肺部疾病良恶性诊断至关重要。EBUS属微创侵入性检查,肺癌纵隔淋巴结分期中被推荐为首选的诊断方法。此外,EBUS可以评估恶性肿瘤对支气管壁的浸润程度。本文对EBUS在肺部疾病中的临床应用及进展进行综述。
气道内超声;支气管镜;超声引导支气管针吸活检术;支气管肺活检;淋巴结
气道超声(endobronchial ultrasonography, EBUS)源于消化内镜,EBUS因搭载探头形式不同,可分为环扫探头气道内超声(radial probe EBUS, R-EBUS)和凸面探头气道内超声(convex probe EBUS, CP-EBUS)。环扫探头频率为12~30 MHz,纵向分辨力0.1 mm,可进行连续360°扫描,探及周围2~3 cm组织深度,可清晰显示支气管壁5~7层结构,协助诊断肺外周肿块和观察支气管壁浸润程度、范围;凸面探头搭载于纤维支气管镜前端,频率5~12 MHz,近场分辨力较差,对目标区域可进行60°~75°扫描,单个扫描平面可观察到35°扇形区域,探及组织深度约5 cm,最大优点为可对目标区域进行实时观测活检,还可通过多普勒模式观察血流情况,主要用于协助诊断中央型肺部肿块性质及纵隔淋巴结早期转移、肺血管病变。EBUS微创、检查过程安全、并发症少,对可疑肺癌的诊断准确率高,美国胸科医师学会(American college of chest physicians, ACCP)推荐EBUS可作为肺癌分期首选诊断方法之一,并将其写入指南,推荐可用于纵隔淋巴结分期[1-2]。EBUS对肺部恶性病灶的诊断准确率高,对诊断肺门纵隔良性病变也有很高的应用价值,其在胸部疾病诊断应用中具有重要作用[3]。本文对EBUS在肺部疾病的临床应用及进展进行综述。
1.1 EBUS在肺部恶性肿瘤中的应用
1.1.1 肺癌 R-EBUS可观察到病变对支气管壁侵犯的程度和范围,但不可进行穿刺取样。对于段支气管以上占位性病变及肺门部肿大淋巴结,超声支气管镜引导下经支气管针吸活检术(endobronchial ultrasound-guided transbronchial needle aspiration, EBUS-TBNA)可对病灶进行定位并实时活检,可较大程度避免传统支气管针吸活检(transbronchial needle aspiration, TBNA)盲穿的风险。Lee等[4]对126例高度可疑恶性肺内占位和淋巴结肿大患者行EBUS-TBNA检查,其诊断肺癌的敏感度、准确率分别为97%(105/108)、98%(123/126);徐叶红等[5]对53例可疑肺癌患者行EBUS-TBNA检查,其诊断肺癌的敏感度、特异度、准确率分别为95%、100%、96%。对于中央型肺部肿瘤,EBUS-TBNA检查需采用CP-EBUS[6]。Kang等[7]对161例诊断为小细胞肺癌(small cell lung cancer, SCLC)患者行EBUS-TBNA检查,中位病灶直径17 mm,发现EBUS-TBNA诊断的敏感度、特异度、阴性预测值、阳性预测值、准确率分别为97.4%、100%、60%、100%、97.5%,认为EBUS-TBNA用于诊断SCLC安全、高效。因EBUS-TBNA敏感度和准确率高、可重复性强、微创、操作简单等,在肺内占位病变中作为一种安全、有效的初始诊断手段,越来越得到认可[8-9]。
肺癌的发生、发展与基因突变有关,EBUS-TBNA穿刺标本可用于分子检测,可对非小细胞肺癌进行分型,使化疗方案个体化,有效指导肺癌化疗[10-12]。
1.1.2 肺癌纵隔淋巴结转移分期 肺癌淋巴结转移准确分期对治疗方案的选择及判断预后十分重要,尤其对于单一肿大淋巴结组织的活检和指导外科手术方案。在肺癌纵隔淋巴结转移分期过程中,穿刺取样一般按照N3区、N2区、N1区的顺序,EBUS可获取2区、4区、7区、10区、11区淋巴结,如联合超声内镜引导下细针针吸活检(endobronchial ultrasound-guided fine needle aspiration, EUS-FNA)可对5区、8区、9区淋巴结取样。纵隔镜检查结果被认为是肺癌纵隔淋巴转移分期的“金标准”,但存在创伤大、风险高、并发症多、不能重复检查等不足。张良等[13]研究表明纵隔镜和EBUS-TBNA对诊断肺癌及其分期的敏感度、准确率及特异度差异无统计学意义。Ge等[14]通过对10个研究中心999例患者进行EBUS-TBNA检查和对7个研究中心915例患者进行电视纵隔镜(video-assisted mediastinoscopy, VAM)检查的Meta分析,发现两种检查均有很高的诊断敏感度,但VAM有较多的并发症和相对较低的阴性预测值,推荐EBUS-TBNA作为肺癌纵隔淋巴结转移分期的首选手段。Osinka等[15]对712例患者进行EBUS-TBNA纵隔淋巴结检查,发现淋巴结直径15~30 mm(中位淋巴结直径 20 mm)时呈阳性。Fielding等[16-17]证实EBUS-TBNA在肺癌纵隔淋巴结转移分期中具有很高的敏感度和特异度,尤其对于淋巴结直径≤1 cm纵隔淋巴结微转移,CT、PET对肺癌纵隔转移淋巴结直径≤1 cm时存在很高的假阴性[18]。
1.2 EBUS在常见肺部良性病变中的应用
1.2.1 结节病 EBUS-TBNA可快速安全地对肺门区肿大淋巴结进行实时穿刺活检,进而获得组织病理学结果。Ribeiro等[19]对39例疑似Ⅰ、Ⅱ期结节病患者进行EBUS-TBNA检查,获得38例患者的有效样本量,33例最终诊断为结节病,其中31例由EBUS-TBNA确诊,EBUS-TBNA对Ⅰ、Ⅱ期结节病诊断的敏感度、特异度、阴性预测值、阳性预测值、诊断准确率分别为94%、100%、100%、75%、95%,表明EBUS-TBNA在Ⅰ、Ⅱ期结节病诊断方面具有较高的应用价值。
1.2.2 肺结核 临床诊断肺结核的“金标准”是痰涂片和痰培养检出抗酸杆菌,对反复痰涂片和培养均阴性的肺结核诊断困难,采用EBUS-TBNA可对病灶或侵犯的淋巴结进行穿刺活检。Navani等[20]对确诊胸内结核的156例患者进行EBUS-TBNA,共诊断146例结核,诊断准确率为94%。Campos等[21]报道1例气管内结核患者,X线胸片和高分辨CT(high resolution CT, HRCT)均未发现异常病灶,采用EBUS-TBNAT通过对淋巴结活检获得明确诊断。提示EBUS-TBNA可有效诊断胸内结核,有望成为诊断胸内结核一种新的方式。
1.3 肺外周病变 既往对肺外周病变的诊断通常采用荧光支气管镜肺活检,因诊断准确率较低,逐渐被EBUS取代成为诊断肺外周病变新的手段。ACCP推荐将EBUS应用于肺外周病变的诊断[22],通过R-EBUS可清晰地发现肺外周低回声团块和强回声边界,通过经超声支气管镜引导下支气管肺活检(endobronchial ultrasound-guided transbronchial biopsy, EBUS-TBB)可有效获取组织标本,进行组织病理诊断。但相对于EBUS-TBNA,EBUS-TBB不能进行实时活检,其主要应用于段支气管以下的肺周围型病变,借助EBUS可以观察支气管壁结构以及肿瘤对支气管壁浸润的程度和范围,且可在EBUS引导下进行经支气管肺活检(transbronchial biopsy, TBB)。Herth等[23]对50例肺外周病变患者进行EBUS-TBB,发现诊断准确率为80%(较对照组荧光支气管镜肺活检高4%),且对直径<3 cm的肺外周病变的诊断价值更高。Tay等[24]对1 420例肺外周病变患者行EBUS-TBB,发现肺外周病变直径与诊断准确率有相关性,肺外周病变直径≤2 cm时诊断准确率为56.3%,直径>2 cm时诊断准确率为77.7%。EBUS结合虚拟电磁导航技术可更好地定位肺外周病变,进一步提高诊断准确率[25]。
1.4 过度动态气道闭陷症(excessive dynamic airway collapse, EDAC)和气管支气管软化症(tracheobronchomalacia, TBM) EDAC和TBM临床表现缺乏特异性,易与慢性阻塞性肺疾病(chronic obstructive pulmonary disease, COPD)和哮喘相混淆[26],引起呼吸衰竭。借助支气管镜和EBUS可确诊EDAC和TBM,支气管镜可直视气道病变,发现气道塌陷和狭窄,EBUS可发现气管支气管壁结构的改变。EDAC气道内超声主要表现为气道后壁回声结构不清、变薄,前壁和侧壁正常;TBM气道内超声表现为气管软骨不完整、连续性中断,主要发生在前壁和侧壁气管和支气管[27]。
1.5 肺动脉栓塞 CP-EBUS因具有彩色多普勒技术,可分辨肺门大血管,将探头置于气管隆突部位,可探测到肺动脉主干、左右肺动脉;将探头置于右主支气管内时,可探测到肺动脉主干、主动脉弓起始部、上腔静脉和右肺动脉。借助血管腔内的血液作为良好的透声窗,可探测到血栓栓子。Aumiller等[28]对32例肺动脉栓塞患者进行EBUS检查,并在24 h内进行增强CT检查检测EBUS的准确性,结果发现增强CT共检出101个栓子,EBUS检出97个,检出率为97%,且平均检查用时为 4 min/例次,且无不良反应。Segraves等[29]采用EBUS探测到56岁男性患者右肺动脉内的栓子,并经增强CT扫描证实。由于EBUS为高频探头、穿透力有限、远场分辨力差等,不推荐常规进行胸腔心血管超声检查,但对肺门部动脉栓塞症的检查安全、可行。
1.6 EBUS在介入治疗中的应用 在支气管镜引导和气道内超声定位下,近年来气道内介入治疗迅速发展,诊疗技术多样化,如对气道良恶性狭窄进行气道支架植入术;肺癌及纵隔肿瘤精确植入放射性粒子和后装放疗技术;利用精细超声支气管镜消融探头,可对纵隔和肺门黏膜下肿瘤进行热消融治疗。采用CP-EBUS的彩色多普勒功能,EBUS-TBNA实时可控、安全精准、阳性率高等优势,在超声引导下对纵隔疾病的治疗将是今后微创介入治疗发展的方向。
具有常规支气管镜技术操作实践并有一定超声影像学基础的医师,经数十次操作练习后便可掌握EBUS。
EBUS-TBNA主要并发症包括穿刺点少量出血、气胸、穿刺后引发肺炎、纵隔炎、心包炎及败血症等,严重的并发症为大血管出血,但罕见[30],穿刺并发症的发生率为1.23%,死亡率为0.01%[31]。一项Meta分析[32]表明1 299例患者中,仅2例发生并发症(0.15%),分别为气胸和低氧,术后可自行缓解。将EBUS-TBB应用于段支气管以下病变,患者耐受性良好,并发症较EBUS-TBNA少且轻微,以少许出血最为多见,气胸、咯血相对少见,以上技术操作并发症经休息或简单对症处理均可减轻。
EBUS-TBNA在胸部疾病中诊断价值已得到公认,但应用于临床肺癌TNM分期时间较短[33]。其不足之处有:①医师的操作水平,需要加强专业医师培训,提高操作诊疗水平,使医师操作水平对穿刺诊断的影响降到最低。②EBUS-TBNA需要专用穿刺针,兼容性差。③EBUS-TBNA检查设备昂贵,检查中可导致设备损毁,且相关耗材未纳入医保范围。④EBUS-TBNA受操作孔道结构限制,活检取材标本偏少,且对穿刺组织标本处理要求高,难以在基层医院推广。⑤活检取材标本偏少导致其假阴性率偏高。
EBUS-TBNA在肺癌诊断及分期、纵隔肺门良恶性疾病的诊断方面有很高的敏感度、特异度和准确率,且其微创、安全、检查时间短、并发症少而且可控,有利于临床推广应用。在气道超声引导和定位下,EBUS结合激光技术,展现出广阔的发展前景。
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Ultrasound diagnosis foreign body in vivo after 20 years: Case report
R563; R445.1
A
1672-8475(2016)11-0705-05
刘丹(1992—),女,江西赣州人,在读硕士。
E-mail: superliudanliudan@163.com
2016-08-11
2016-09-13