張湛,許相豐,魏剛
MRI在宮頸癌分期及淋巴結(jié)轉(zhuǎn)移評(píng)估中的價(jià)值探討
張湛,許相豐,魏剛
目的 比較宮頸癌磁共振成像(MRI)分期與2009版國(guó)際婦產(chǎn)科聯(lián)盟(FIGO)分期的準(zhǔn)確度并評(píng)估MRI診斷淋巴結(jié)轉(zhuǎn)移的價(jià)值。方法 以手術(shù)病理為金標(biāo)準(zhǔn),比較86例宮頸癌病例(手術(shù)病理分期≥Ⅰb期)MRI分期與FIGO分期的準(zhǔn)確度;取橫斷面擴(kuò)散加權(quán)成像(DWI)呈稍高信號(hào),圖像上短徑≥1 cm的淋巴結(jié)為轉(zhuǎn)移淋巴結(jié),分析其特征并評(píng)估MRI診斷淋巴結(jié)轉(zhuǎn)移的準(zhǔn)確度、敏感度、特異度、陽(yáng)性預(yù)測(cè)值、陰性預(yù)測(cè)值及轉(zhuǎn)移基本特征。結(jié)果FIGO分期準(zhǔn)確度80.2%(69/86),MRI分期準(zhǔn)確度83.7%(72/86),差異無(wú)統(tǒng)計(jì)學(xué)意義(P>0.05);MRI診斷淋巴結(jié)轉(zhuǎn)移準(zhǔn)確度94.2%(81/86)、敏感度73.3%(11/15)、特異度98.6%(70/71)、陽(yáng)性預(yù)測(cè)值91.7%(11/12)及陰性預(yù)測(cè)值94.6%(70/74);11例真陽(yáng)性淋巴結(jié)轉(zhuǎn)移以左髂內(nèi)及左髂總淋巴結(jié)為主,平均短、長(zhǎng)直徑比0.76,包括3例類(lèi)圓形,3例邊界不規(guī)則形,4例巨大融合形,1例含中心壞死區(qū)。1例假陽(yáng)性位于右髂內(nèi)淋巴結(jié),T2WI/TRA呈巨大融合形,薄層掃描顯示外形較細(xì)碎,而T2WI/SAG則呈長(zhǎng)條形。結(jié)論 MRI分期與FIGO分期準(zhǔn)確度均較高,兩者結(jié)合有利于提高診斷準(zhǔn)確度;MRI能較準(zhǔn)確診斷淋巴結(jié)轉(zhuǎn)移。
宮頸腫瘤;磁共振成像;淋巴轉(zhuǎn)移;腫瘤分期;診斷,鑒別;敏感性與特異性
宮頸癌是較常見(jiàn)的婦科惡性腫瘤,其分期與治療及預(yù)后密切相關(guān)。目前,宮頸癌分期仍采用臨床分期,其標(biāo)準(zhǔn)為2009版國(guó)際婦產(chǎn)科聯(lián)盟(FIGO)分期,且不隨影像檢查及手術(shù)病理結(jié)果更改[1]。研究顯示,約80%的宮頸癌發(fā)生于發(fā)展中國(guó)家,因此,臨床分期于發(fā)展中國(guó)家更為實(shí)用[2]。臨床分期的標(biāo)準(zhǔn)主要基于婦科宮頸活檢、胸片、膀胱鏡及腸鏡等檢查,但并不包括對(duì)淋巴結(jié)轉(zhuǎn)移的判斷,以病理分期為金標(biāo)準(zhǔn),臨床分期判斷的錯(cuò)誤率為16%~65%[3]。研究認(rèn)為,術(shù)前磁共振成像(MRI)分期雖不包含在臨床分期中,但對(duì)宮頸癌預(yù)后判斷有較高的敏感度和特異度[4]。本研究旨在比較MRI分期與臨床分期的差異,并初步探討MRI在淋巴結(jié)轉(zhuǎn)移中的診斷價(jià)值。
1.1 研究對(duì)象 選擇2014年12月—2015年7月經(jīng)陰道鏡宮頸活檢病理診斷確診為宮頸癌的患者86例,年齡25~73歲,平均年齡(49.0±8.9)歲;手術(shù)病理分期均≥Ⅰb期,其中鱗癌62例、腺癌22例、鱗腺癌2例。臨床分期、MRI分期及手術(shù)病理分期均采用2009版FIGO推薦標(biāo)準(zhǔn)[5]。
1.2 MRI檢查方法 采用飛利浦1.5T超導(dǎo)型磁共振(Achieva,Philips),16通道體部表面線(xiàn)圈。平掃序列為橫斷面及矢狀面T1weighted imaging(T1WI),T2weighted imaging(T2WI),短TI反轉(zhuǎn)恢復(fù)序列(Short-tau Inversion Recovery,SPIR),橫斷面擴(kuò)散加權(quán)成像(diffusion-weighted magnetic resonance imaging,DWI);平均層厚5 mm,層間距1 mm。增強(qiáng)掃描對(duì)比劑采用釓噴酸葡胺,劑量15 mL,流速為2.0 mL/s;注射后延遲15 s、25 s及60 s行3期掃描,層厚2.5 mm,層間距0 mm;第3期加掃矢狀面,層厚2.5 mm,層間距0 mm。
1.3 分期方法及判斷標(biāo)準(zhǔn) (1)臨床分期。根據(jù)病史,陰道鏡宮頸活檢及婦科三合診等檢查,由2名副主任以上婦科醫(yī)師根據(jù)2009版FIGO分期方法確定[1]。(2)MRI分期。由2名經(jīng)驗(yàn)豐富的MRI診斷醫(yī)師經(jīng)討論一致做出,結(jié)果判斷參照文獻(xiàn)[6]:Ⅰa期,無(wú)異常信號(hào);Ⅰb期,低信號(hào)的宮頸內(nèi)部間質(zhì)中斷;Ⅱa期,低信號(hào)的近端陰道壁連續(xù)性中斷;Ⅱb期,腫瘤穿過(guò)低信號(hào)的內(nèi)部間質(zhì)及中等信號(hào)的外部間質(zhì)蔓延至宮旁組織;Ⅲ期,腫瘤信號(hào)使低信號(hào)的遠(yuǎn)端陰道中斷或侵犯正常盆壁肌肉;Ⅳ期,低信號(hào)的膀胱逼尿肌或低信號(hào)的直腸肌中斷,盆外器官發(fā)現(xiàn)腫瘤。手術(shù)病理分期:由病理醫(yī)師根據(jù)手術(shù)病理結(jié)果按臨床分期標(biāo)準(zhǔn)判斷分期。以手術(shù)病理分期為金標(biāo)準(zhǔn)判斷臨床分期和MRI分期的差異。
1.4 淋巴結(jié)轉(zhuǎn)移 MRI診斷淋巴結(jié)轉(zhuǎn)移陽(yáng)性標(biāo)準(zhǔn):DWI呈稍高信號(hào),淋巴結(jié)T2WI-TRA短徑≥1 cm。以手術(shù)病理為金標(biāo)準(zhǔn),計(jì)算MRI診斷的敏感度、特異度、準(zhǔn)確度、陽(yáng)性預(yù)測(cè)值及陰性預(yù)測(cè)值,并分析MRI診斷淋巴結(jié)轉(zhuǎn)移的基本特征。
Tab.3 The basic status of metastatic lymph nodes by MRI表3MRI診斷轉(zhuǎn)移淋巴結(jié)的基本特征
1.5 統(tǒng)計(jì)學(xué)方法 采用SPSS 16.0統(tǒng)計(jì)軟件。符合正態(tài)分布的計(jì)量資料以±s表示。計(jì)數(shù)資料以例(%)表示,組間比較用卡方檢驗(yàn),以P<0.05為差異有統(tǒng)計(jì)學(xué)意義。
2.1 分期對(duì)比 與病理分期對(duì)比,臨床分期相符69例,準(zhǔn)確度80.2%(69/86);MRI分期相符72例,準(zhǔn)確度83.7%(72/86),準(zhǔn)確度差異無(wú)統(tǒng)計(jì)學(xué)意義(χ2= 0.354,P>0.05),見(jiàn)表1。
Tab.1 Clinical-staging and MRI-staging contrasted with pathological-staging in 86 cervical cancer samples表1 86例宮頸癌的臨床分期、MRI分期與病理分期對(duì)照(例)
2.2 淋巴結(jié)轉(zhuǎn)移診斷結(jié)果 MRI診斷淋巴結(jié)轉(zhuǎn)移準(zhǔn)確度94.2%(81/86),敏感度73.3%(11/15),特異度98.6%(70/71),陽(yáng)性預(yù)測(cè)值91.7%(11/12),陰性預(yù)測(cè)值94.6%(70/74),見(jiàn)表2。
Tab.2 Contrast study of metastatic lymph nodes by MRI and pathological results表2 淋巴結(jié)轉(zhuǎn)移MRI與病理診斷結(jié)果對(duì)比分析(例)
2.3 MRI診斷轉(zhuǎn)移淋巴結(jié)的基本特征 MRI診斷的12例淋巴結(jié)轉(zhuǎn)移患者的基本特征情況,見(jiàn)表3。11例真陽(yáng)性淋巴結(jié)轉(zhuǎn)移以左髂內(nèi)淋巴結(jié)及左髂總淋巴結(jié)為主;1例假陽(yáng)性的淋巴結(jié)位于右髂內(nèi),T2WI橫斷面上形態(tài)似巨大融合,薄層掃描顯示外形較細(xì)碎,矢狀面上呈長(zhǎng)條形,見(jiàn)圖1。
Fig.1 One example of false positive lymph node showed by MRI圖1MRI診斷假陽(yáng)性淋巴結(jié)轉(zhuǎn)移1例
3.1 MRI分期與臨床分期比較 宮頸多層組織與周?chē)Y(jié)構(gòu)信號(hào)對(duì)比顯著,是宮頸癌MRI分期的良好基礎(chǔ)。宮頸在T2WI序列上可清晰區(qū)分出4層結(jié)構(gòu):稍高信號(hào)宮腔黏液、高信號(hào)宮頸黏膜、低信號(hào)的基質(zhì)環(huán)及稍高信號(hào)的外層疏松肌層[3,7]。宮頸周?chē)咝盘?hào)的脂肪組織中可見(jiàn)低信號(hào)的子宮韌帶及蔓狀流空血管影;宮頸與前后方的膀胱及直腸信號(hào)差異顯著并有脂肪組織間隔;陰道壁低信號(hào)與宮頸癌稍高信號(hào)具有良好對(duì)比[8]。本研究前期曾以手術(shù)病理分期為金標(biāo)準(zhǔn),106例宮頸癌的 MRI分期準(zhǔn)確度(84.0%)、陰道浸潤(rùn)準(zhǔn)確度(85.8%)及宮旁浸潤(rùn)準(zhǔn)確度(96.2%);MRI在宮頸癌分期及分期的關(guān)鍵因素陰道浸潤(rùn)及宮旁浸潤(rùn)判斷上均較敏感[9]。
目前,MRI分期與臨床分期的比較研究較多,但結(jié)果多有爭(zhēng)議。多篇研究認(rèn)為,MRI分期準(zhǔn)確度明顯高于臨床分期準(zhǔn)確度[10-11];而部分研究認(rèn)為臨床分期較MRI分期優(yōu)勢(shì)明顯[12-13]。筆者考慮造成差異的原因可能與診斷者的水平、研究對(duì)象的選擇差異有關(guān)。研究顯示,針對(duì)部分晚期(Ⅱb期以上)患者臨床分期診斷的準(zhǔn)確度明顯低于MRI分期[14-15]。本研究以早期患者為主(Ⅰb期占88.4%),臨床分期與MRI分期的準(zhǔn)確度分別為80.2%和83.7%,差異無(wú)統(tǒng)計(jì)學(xué)意義。然而兩種分期的準(zhǔn)確度符合早期宮頸癌臨床分期準(zhǔn)確度較高的情況[1,3];MRI分期準(zhǔn)確度較高進(jìn)一步證實(shí)了MRI在早期宮頸癌分期中的作用。另外,中晚期患者M(jìn)RI更易于顯示腫瘤與周?chē)K器的關(guān)系及淋巴結(jié)轉(zhuǎn)移等情況,而臨床分期往往不能提示這些情況。故本研究認(rèn)為雖然二者準(zhǔn)確度無(wú)明顯差異,但MRI分期在總體上還是優(yōu)于臨床分期的,提示二者更多表現(xiàn)為一種互相補(bǔ)充的關(guān)系,應(yīng)把兩者結(jié)合起來(lái)能進(jìn)一步提高診斷準(zhǔn)確度。喬志偉等[12]將臨床分期與MRI分期結(jié)合后顯示,整體準(zhǔn)確度(92%)明顯高于單獨(dú)臨床分期(81%)及MRI分期(67%)。
3.2 淋巴結(jié)轉(zhuǎn)移 淋巴結(jié)轉(zhuǎn)移是影響宮頸癌預(yù)后的重要因素,也是婦科醫(yī)師關(guān)注的重點(diǎn)內(nèi)容。DWI是能觀察活體組織內(nèi)水分子擴(kuò)散運(yùn)動(dòng)的無(wú)創(chuàng)性方法,無(wú)需引入對(duì)比劑即能提高病變的組織對(duì)比度。轉(zhuǎn)移淋巴結(jié)中水分子擴(kuò)散受限,在DWI上顯示為較高信號(hào)影[16]。轉(zhuǎn)移淋巴結(jié)往往表現(xiàn)為特定的形態(tài)如圓形、不規(guī)則形,預(yù)示較大融合淋巴結(jié)轉(zhuǎn)移的可能性大[17];淋巴結(jié)壞死并伴環(huán)形強(qiáng)化是轉(zhuǎn)移的特異性征象,陽(yáng)性預(yù)測(cè)值約100%[18]。淋巴結(jié)的大小是影像檢查診斷淋巴結(jié)轉(zhuǎn)移的主要診斷依據(jù)。Manfredi等[19]選擇淋巴短徑≥1 cm與≥5 mm兩組對(duì)比判斷淋巴結(jié)轉(zhuǎn)移,發(fā)現(xiàn)≥1 cm組有較高的陽(yáng)性預(yù)測(cè)值(≥1 cm組:100%;≥5 mm組:43%)。
本研究用DWI與T2WI圖像結(jié)合診斷淋巴結(jié)轉(zhuǎn)移,準(zhǔn)確度(94.2%)及陽(yáng)性預(yù)測(cè)值(91.7%)均較高。11例真陽(yáng)性淋巴結(jié)外形特征與以上研究相似;1例假陽(yáng)性淋巴結(jié)雖表現(xiàn)為巨大融合形,但外形較細(xì)碎。然而,尚有4例假陰性MRI未提示淋巴結(jié)轉(zhuǎn)移,表明僅根據(jù)淋巴短徑≥1 cm的標(biāo)準(zhǔn)判斷淋巴結(jié)轉(zhuǎn)移敏感度不夠高(73.3%)。Jiménez等[20]研究顯示,僅根據(jù)形態(tài)及信號(hào)較難判斷小于1 cm的淋巴結(jié)轉(zhuǎn)移。因此,結(jié)合相關(guān)研究,筆者認(rèn)為要提高轉(zhuǎn)移淋巴結(jié)的檢出率,有必要對(duì)小于1 cm的淋巴結(jié)進(jìn)行觀察研究。有研究顯示,依據(jù)傳統(tǒng)影像方法診斷淋巴微轉(zhuǎn)移難度較大,而一些新的方法比如納米級(jí)超微超順磁性鐵氧化體顆粒(ultrasmall superparamagnetic iron oxide,USPIO)對(duì)比劑或PET成像(positron emission tomography)等可以提高敏感度[19]。
綜上所述,在早期宮頸癌的診斷中,MRI分期與臨床分期準(zhǔn)確度均較高,兩者結(jié)合有利于診斷;MRI能較準(zhǔn)確診斷淋巴結(jié)轉(zhuǎn)移。然而,本研究存在的局限之處為:納入的患者多為早期手術(shù)患者(Ⅰb期為主),因晚期患者不采用手術(shù)治療,無(wú)病理對(duì)照而未進(jìn)行分析;對(duì)盆部淋巴結(jié)分析著重于外形及大小,對(duì)DWI的分析有待采用更精確的量化指標(biāo)(如ADC值等)。
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(2015-11-19收稿 2016-03-08修回)
(本文編輯 陸榮展)
Evaluation of MRI-staging and assessment of lymphatic metastasis in cervical cancer
ZHANG Zhan,XU Xiangfeng,WEI Gang
Department of Radiology,Tianjin Central Hospital of Gynecology and Obstetrics,Tianjin 300100,China
Objective To contrast the accuracy rate of nuclear magnetic resonance imaging(MRI)-staging and the International Federation of Gynecology and Obstetrics(FIGO,2009)clinical-staging,and evaluate the value of MRI in diagnosis of lymph node metastasis in cervical cancer.Methods The surgical pathology was used as golden standard,the accuracy rates of MRI-staging and FIGO-staging were compared in 86 patients of cervical cancer(surgical pathological staging≥Ⅰb).The lymph nodes with slightly hyperintense signal in diffusion-weighted magnetic resonance imaging(DWI)and with minor axis≥1 cm in T2WI-TRA(T2 weighted imaging-transverse section)were considered as metastatic lymph nodes,the characteristics of lymphatic metastasis diagnosed by MRI were analyzed,and the accuracy rate,the sensitivity,the specificity,the positive predictive value and the negative predictive value of MRI were evaluated.Results The accuracy rate of FIGO-staging was 80.2%(69/86),and the accuracy rate of MRI-staging was 83.7%(72/86),there was no significant difference between them(P>0.05).The accuracy rate of lymphatic metastasis diagnosed by MRI was 94.2%(81/86),the sensitivity was 73.3%(11/15),the specificity was 98.6%(70/71),the positive predictive value was 91.7%(11/12),and the negative predictive value was 94.6%(70/74).The true positive metastatic lymph nodes in 11 cases were located in the external iliac nodes or common iliac lymph nodes,the average short/long diameter was 0.76.The forms of lymph nodes were as follows:quasi-circular(n=3),border irregularity(n=3),huge fusion form(n=4),and 1 with central necrosis area.One case of false positive metastatic lymph node was located in the right external iliac node,with the sharp of huge fusion form in T2WI/TRA,comminution in T2WI-axial thin slices,and long strip in T2WI/SAG.Conclusion The accuracy rates of MRI-staging and FIGO-staging were both higher,which can diagnose lymphatic metastasis relatively accurately when they are combined together.
uterine cervical neoplasms;magnetic resonance imaging;lymphatic metastasis;neoplasm staging;diagnosis,differential;sensitivity and specificity
R445.2,R711.74
A
10.11958/20150338
天津市中心婦產(chǎn)科醫(yī)院放射科(郵編300100)
張湛(1978),女,主治醫(yī)師,碩士,主要從事婦科腫瘤的影像診斷研究