Gd-EOB-DTPA增強(qiáng)掃描前后T2WI對(duì)肝臟局灶性病變檢出情況的比較
蔡華崧伍玲周麗莎羅宴吉翟鳳儀馮仕庭李子平鄭可國(guó)
【摘要】目的比較肝臟局灶性病變患者行MRI檢查時(shí)于注射釓塞酸二鈉(Gd-EOB-DTPA)前、后進(jìn)行T2加權(quán)像(T2WI)掃描對(duì)病灶檢出情況的差異。方法比較84例肝臟局灶性病變(包括肝細(xì)胞癌、局灶性結(jié)節(jié)增生、肝轉(zhuǎn)移瘤及肝血管瘤)患者Gd-EOB-DTPA增強(qiáng)掃描前、后進(jìn)行T2WI掃描的病灶檢出情況、病灶信號(hào)噪聲比及病灶-肝臟噪聲比。結(jié)果Gd-EOB-DTPA增強(qiáng)掃描后T2WI的肝細(xì)胞癌、局灶性結(jié)節(jié)增生、肝轉(zhuǎn)移瘤及肝血管瘤的檢出評(píng)分均稍高于增強(qiáng)掃描前T2WI,但比較差異均無(wú)統(tǒng)計(jì)學(xué)意義(P均>0.05)。Gd-EOB-DTPA增強(qiáng)掃描前肝細(xì)胞癌、局灶性結(jié)節(jié)增生、肝轉(zhuǎn)移瘤及肝血管瘤的病灶信號(hào)噪聲比依次為7.65±0.35、6.13±0.74、7.83±0.49、16.69±0.52,增強(qiáng)掃描后依次為7.27±0.38、5.78±0.70、7.32±0.45、12.37±0.42,比較差異均有統(tǒng)計(jì)學(xué)意義(P均<0.001);Gd-EOB-DTPA增強(qiáng)掃描前肝細(xì)胞癌、局灶性結(jié)節(jié)增生、肝轉(zhuǎn)移瘤及肝血管瘤的病灶-肝臟噪聲比依次為2.14±0.37、1.02±0.65、2.33±0.51、13.07±0.49,增強(qiáng)掃描后依次為3.46±0.35、2.06±0.61、4.28±0.47、9.11±0.52,比較差異均有統(tǒng)計(jì)學(xué)意義(P均<0.001)。結(jié)論對(duì)于肝細(xì)胞癌、局灶性結(jié)節(jié)增生、肝轉(zhuǎn)移瘤及肝血管瘤患者,在接受MRI檢查時(shí),于Gd-EOB-DTPA增強(qiáng)掃描后行T2WI掃描對(duì)病灶的檢出無(wú)明顯影響,可在上述病變動(dòng)態(tài)增強(qiáng)掃描后進(jìn)行T2WI以節(jié)省掃描時(shí)間。
【關(guān)鍵詞】釓塞酸二鈉;T2加權(quán)像;磁共振
收稿日期:(2015-05-31)
DOI:10.3969/g.issn.0253-9802.2015.10.006
基金項(xiàng)目:廣東省科技計(jì)劃項(xiàng)目(2013B021800185);廣東省科技第一批企業(yè)研發(fā)與升級(jí)改造項(xiàng)目(2013B021800178)
通訊作者,曾錦,E-mail:13710678633@139.com
Comparison of T2-weighted MR image in detection of focal liver lesions before and after administration of Gd-EOB-DTPACaiHuasong,WuLing,ZhouLisha,LuoYanji,ZhaiFengyi,FengShiting,LiZiping,ZhengKeguo.DepartmentofRadiology,theFirstAffiliatedHospitalofSunYat-senUniverisity,Guangzhou510080,China
Correspondingauthor,ZhengKeguo,E-mail:zheng-keguo@163.com
Abstract【】ObjectiveTo compare the T2-weighted image (T2WI) in the detection of focal hepatic lesions before and after administration of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA). MethodsEighty four patients diagnosed with focal liver lesions (hepatocellular carcinoma, focal nodular hyperplasia, liver metastasis neoplasm and hepatic hemangioma) underwent T2WI. The detection capability, signal-to-noise ratio (SNR) and lesion-liver contrast to noise ratio (CNR) before and after administering Gd-EOB-DTPA were statistically compared. ResultsThe detection scores of hepatocellular carcinoma, focal nodular hyperplasia, liver metastasis neoplasm and hepatic hemangioma after Gd-EOB-DTPA-enhanced T2WI were only slightly higher than those before the administration of Gd-EOB-DTPA without statistical significance(all P>0.05). The SNR of hepatocellular carcinoma, focal nodular hyperplasia, liver metastasis neoplasm and hepatic hemangioma before Gd-EOB-DTPA-enhanced T2WI were 7.65±0.35,6.13±0.74,7.83±0.49 and 16.69±0.52, significantly higher compared with 7.27±0.38, 5.78±0.70, 7.32±0.45 and 12.37±0.42 after Gd-EOB-DTPA-enhanced T2WI (all P<0.001). The CNR of hepatocellular carcinoma, focal nodular hyperplasia, liver metastasis neoplasm and hepatic hemangioma before Gd-EOB-DTPA-enhanced T2WI were 2.14±0.37, 1.02±0.65, 2.33±0.51 and 13.07±0.49, significantly lower than 3.46±0.35, 2.06±0.61, 4.28±0.47 and 9.11±0.52 following Gd-EOB-DTPA-enhanced T2WI (all P<0.001). ConclusionGd-EOB-DTPA-enhanced T2WI exerted no apparent effect upon the detection of focal liver lesions in patients diagnosed with hepatocellular carcinoma, focal nodular hyperplasia, liver metastasis neoplasm and hepatic hemangioma, so T2WI can be performed following Gd-EOB-DTPA-enhanced scan to shorten the time of examine.
【Key words】Gdolinium ethoxybenzyl diethylenetriamine pentaacetic acid; T2-weighted image;
Magnetic resonance imaging
釓塞酸二鈉(Gd-EOB-DTPA) 是一種新型的肝膽特異性MRI對(duì)比劑,是釓與乙氧基苯甲基螯合物的二鈉鹽[1-3]。臨床研究表明,經(jīng)靜脈注射后,Gd-EOB-DTPA可提供與其他釓螯合物相媲美的鑒別診斷信息,約50%的Gd-EOB-DTPA被肝細(xì)胞特異性攝取后經(jīng)膽道排泄,利用此特性,可提高局灶性肝臟病變的檢出率[4-6]。Gd-EOB-DTPA不僅和傳統(tǒng)的釓噴酸葡胺(Gd-DTPA)一樣,能通過(guò)動(dòng)態(tài)增強(qiáng)掃描評(píng)價(jià)腫瘤的血流灌注,而且其肝細(xì)胞吸收特性及高T1弛豫率,使肝臟在注射Gd-EOB-DTPA后30 min甚至更長(zhǎng)時(shí)間仍能表現(xiàn)為高信號(hào)[7-8]。
目前,國(guó)內(nèi)外公認(rèn)的Gd-EOB-DTPA增強(qiáng)掃描肝細(xì)胞期為注藥后20 min[9-10]。在實(shí)際臨床應(yīng)用中操作者希望用盡可能短的時(shí)間完成整個(gè)MRI檢查,為了縮短Gd-EOB-DTPA增強(qiáng)掃描MRI的檢查時(shí)間,在動(dòng)態(tài)增強(qiáng)掃描后與肝細(xì)胞期掃描前這段時(shí)間內(nèi)行T2加權(quán)像(T2WI)是一種合理的提議。本研究旨在從病灶檢出率及病灶性質(zhì)(實(shí)性或非實(shí)性)兩方面,比較增強(qiáng)掃描前后半傅立葉采集單次激發(fā)快速自旋回波(HASTE)T2WI差異,以探討能否在注射Gd-EOB-DTPA后行T2WI。
對(duì)象與方法
一、研究對(duì)象
以2011 年11月至2014 年11月于我院就診的84例(共127個(gè)病灶)最終經(jīng)病理學(xué)檢查證實(shí)的肝臟局灶性病變患者為研究對(duì)象,84例均符合以下標(biāo)準(zhǔn):①年齡≥18歲;②Child-Pugh肝功能分級(jí)均為A級(jí)[11];③行MRI檢查前3 d測(cè)量血清總膽紅素均正常;④在檢查前1周停止服用主要經(jīng)膽汁排泄的陰離子類藥物(如利福平);⑤自愿參加本研究且簽署知情同意書。84例均排除以下情況:①體內(nèi)有心臟起搏器、胰島素泵等電子植入儀器,腹部有磁鐵性金屬異物等MRI相關(guān)禁忌證;②需要接受生命監(jiān)護(hù)和生命維持系統(tǒng)治療的危重患者或急診患者;③對(duì)已知MRI對(duì)比劑有過(guò)敏反應(yīng);④孕期或哺乳期婦女;⑤因生理或心理異常而無(wú)法簽署知情同意書。84例中男58例、女26例, 年齡(49.52±8.27)歲,病程2周~1年、中位病程6個(gè)月。其中肝細(xì)胞癌47例(共61個(gè)病灶),肝血管瘤17例(共28個(gè)病灶),肝局灶性結(jié)節(jié)增生11例(共15個(gè)病灶),肝轉(zhuǎn)移瘤9例(共23個(gè)病灶)。本研究方案經(jīng)我院醫(yī)學(xué)倫理委員會(huì)審查批準(zhǔn),每位患者入組前均了解整個(gè)研究過(guò)程并簽署了知情同意書。
二、MRI對(duì)比劑注射方案
本組病例采用Gd-EOB-DTPA(Primovist, Bayer Schering Pharma, Berlin, Germany)為MRI對(duì)比劑。使用劑量為0.1 ml/kg(即25 μmol/kg),經(jīng)肘靜脈手動(dòng)推注,注射速率約為1 ml/s。注射后立即用30 ml生理鹽水沖洗導(dǎo)管,沖洗速率約為1 ml/s[12-13]。
三、MRI掃描方案
使用MAGNETOM Trio a Tim 3.0 T 超導(dǎo)MRI設(shè)備(Siemens Healthcare Sector, Erlangen, Germany)對(duì)患者行上腹部平掃及增強(qiáng)掃描。掃描前患者需禁食禁水至少4 h,受檢體位為仰臥位,采用8通道相控陣體線圈,掃描范圍覆蓋膈頂至肝臟下緣。
MRI平掃序列:①HASTE序列定位;②HASTE T2WI序列冠狀位成像;③HASTE T2WI序列軸位成像;④快速小角度激發(fā)(FLASH)T1WI同相位/反相位序列軸位成像;⑤FLASH T1WI脂肪抑制序列軸位成像。
Gd-EOB-DTPA動(dòng)態(tài)增強(qiáng)掃描序列:注藥后13~25 s連續(xù)行三維容積式內(nèi)插法屏氣檢查序列(3D-VIBE)T1WI(脂肪抑制)序列軸位及冠狀位成像,共掃描8次。
Gd-EOB-DTPA肝細(xì)胞期掃描序列:注藥后20 min行3D VIBE T1WI(脂肪抑制)序列軸位及冠狀位成像。
掃描結(jié)束后將所采集的數(shù)據(jù)傳輸至Siemens Leonardo Syngo 2009B工作站行最大信號(hào)強(qiáng)度投影(MIP)重組。各掃描序列的具體參數(shù)見(jiàn)表1。
表1 MRI掃描序列及參數(shù)
注:TRA、COR、SAG 分別為橫軸位、冠狀位、矢狀位
四、圖像分析
1.定性分析
參照Kim等[14]的研究方法,將掃描圖像分為2組:一組為增強(qiáng)掃描前T2WI圖像組(pre-T2WI組),包括T1WI平掃、增強(qiáng)掃描動(dòng)脈期、門靜脈期、平衡期、肝細(xì)胞期和pre-T2WI;另一組為增強(qiáng)掃描后5 min T2WI圖像組(post-T2WI組),包括T1WI平掃、增強(qiáng)掃描動(dòng)脈期、門靜脈期、平衡期、肝細(xì)胞期和post-T2WI。2組圖像由2位腹部影像閱片醫(yī)師在工作站隨機(jī)共同判讀,對(duì)病灶的檢出情況用5分法進(jìn)行評(píng)價(jià):0分代表未發(fā)現(xiàn)病灶;1分代表很可能無(wú)病灶;2分代表可能有病灶;3分代表很可能有病灶;4分代表肯定有病灶。2位閱片醫(yī)師均不知曉患者的病史、最終診斷、MRI其他序列圖像或其他影像學(xué)檢查結(jié)果。
2.定量分析
參照Kim等[14]的測(cè)量方法,公式如下。
病灶-肝臟噪聲比(CNR)=
肝臟(或病灶)信號(hào)強(qiáng)度由一位腹部影像閱片醫(yī)師在工作站的增強(qiáng)掃描前和增強(qiáng)掃描后T2WI軸位圖像上用一盡可能大的橢圓形感興趣區(qū)(ROI)測(cè)得,該醫(yī)師不參與圖像定性分析。測(cè)量時(shí)同一患者的增強(qiáng)掃描前和增強(qiáng)掃描后T2WI的ROI盡量選自同一層面,且盡量選擇偽影小的層面。背景噪聲標(biāo)準(zhǔn)差在與測(cè)量肝臟(或病灶)信號(hào)強(qiáng)度同一層面的空氣中用近似大小的ROI測(cè)得(圖1)。
圖1肝臟局灶性病變患者M(jìn)RI的
T2WI軸位圖像上ROI的測(cè)量
白箭頭:病灶信號(hào)強(qiáng)度;紅箭頭:肝臟信號(hào)強(qiáng)度;綠箭頭:背景噪聲標(biāo)準(zhǔn)差
五、統(tǒng)計(jì)學(xué)處理
結(jié)果
一、Gd-EOB-DTPA增強(qiáng)掃描前后T2WI病灶檢出評(píng)分及顯示情況
84例患者均耐受本項(xiàng)檢查,且均未出現(xiàn)不良反應(yīng)。Gd-EOB-DTPA增強(qiáng)掃描前后T2WI病灶檢出評(píng)分見(jiàn)表2。post-T2WI組中肝細(xì)胞癌、局灶性結(jié)節(jié)增生、肝轉(zhuǎn)移瘤及肝血管瘤的檢出評(píng)分均稍高于pre-T2WI組的評(píng)分,但2組比較差異均無(wú)統(tǒng)計(jì)學(xué)意義(P>0.05)。127個(gè)病灶中,有4個(gè)肝細(xì)胞癌病灶(4/61,6.56%)和2個(gè)肝轉(zhuǎn)移瘤病灶(2/23,8.70%)在增強(qiáng)掃描前T2WI顯示不清楚,在增強(qiáng)掃描后T2WI卻能清晰顯示;另有1個(gè)肝細(xì)胞癌病灶(1/61,1.64%)在增強(qiáng)掃描后T2WI顯示不清楚,在增強(qiáng)掃描前T2WI卻能清晰顯示。圖例見(jiàn)圖2。
表2 Gd-EOB-DTPA 增強(qiáng)掃描前后T 2WI病灶檢出評(píng)分 分
二、Gd-EOB-DTPA增強(qiáng)掃描前后病灶的信號(hào)噪聲比、病灶-肝臟噪聲比比較
肝細(xì)胞癌、局灶性結(jié)節(jié)增生、肝轉(zhuǎn)移瘤及肝血管瘤的病灶的信號(hào)噪聲比與病灶-肝臟噪聲比于Gd-EOB-DTPA增強(qiáng)掃描前、后比較差異均有統(tǒng)計(jì)學(xué)意義(P均<0.001),見(jiàn)表3。
表3 Gd-EOB-DTPA 增強(qiáng)掃描前后T 2WI SNR及
注:SNR為病灶的信號(hào)噪聲比,CNR為病灶-肝臟噪聲比
討論
傳統(tǒng)的非細(xì)胞特異性MRI對(duì)比劑(如Gd-DTPA)的掃描流程主要包括平掃和增強(qiáng)掃描兩大部分,其中T2WI掃描一般在增強(qiáng)掃描前進(jìn)行。因?yàn)榇祟悓?duì)比劑無(wú)需在注藥后延長(zhǎng)掃描時(shí)間行其他特殊時(shí)期的掃描,所以T2WI無(wú)論是在增強(qiáng)掃描前進(jìn)行還是在增強(qiáng)掃描后進(jìn)行,均不會(huì)影響整體的掃描時(shí)間。對(duì)于肝膽特異性MRI對(duì)比劑(如Gd-EOB-DTPA)而言,其掃描程序與普通釓類對(duì)比劑相似,不同點(diǎn)主要在于前者延長(zhǎng)了注射對(duì)比劑后20 min的肝細(xì)胞期,因此動(dòng)態(tài)增強(qiáng)掃描與肝細(xì)胞期掃描間會(huì)留下約十幾分鐘的“空閑”時(shí)間。此期間如果能進(jìn)行HASTE序列等T2WI掃描,就能縮短整個(gè)肝臟MRI的檢查時(shí)間。
誠(chéng)然,縮短檢查時(shí)間應(yīng)以保證病灶檢出率與診斷正確性為前提。然而,幾乎大部分的MRI對(duì)比劑都具有一定程度的T1弛豫時(shí)間和T2弛豫時(shí)間縮短效應(yīng),可能會(huì)導(dǎo)致增強(qiáng)掃描后T2WI圖像上的肝臟和病灶信號(hào)強(qiáng)度與增強(qiáng)掃描前不一致[13]。病灶的檢出和診斷可能因此受到影響。
為了比較Gd-EOB-DTPA增強(qiáng)掃描前后T2WI對(duì)病灶顯示的差異,筆者對(duì)行Gd-EOB-DTPA增強(qiáng)掃描的多種肝結(jié)節(jié)進(jìn)行了增強(qiáng)掃描前后T2WI掃描,對(duì)比病變?cè)谠鰪?qiáng)掃描前后T2WI上的檢出率及信號(hào)強(qiáng)度的定量數(shù)據(jù),擬確定是否能在注射Gd-EOB-DTPA增強(qiáng)后進(jìn)行T2WI掃描。在本組研究中,post-T2WI組肝細(xì)胞癌、局灶性結(jié)節(jié)增生、肝轉(zhuǎn)移瘤及肝血管瘤的檢出評(píng)分雖然稍高于pre-T2WI組的評(píng)分,但比較差異均無(wú)統(tǒng)計(jì)學(xué)意義。故我們初步認(rèn)為,Gd-EOB-DTPA增強(qiáng)掃描后行T2WI檢查,對(duì)肝臟局灶性病變的檢出率可能無(wú)明顯影響。
理論上講,當(dāng)對(duì)比劑濃度較低時(shí),因其T1弛豫時(shí)間縮短效應(yīng),增強(qiáng)掃描后T2WI圖像的病灶信號(hào)噪聲比會(huì)輕度升高;當(dāng)對(duì)比劑濃度較高時(shí),因其T2弛豫時(shí)間縮短效應(yīng)超過(guò)T1弛豫時(shí)間縮短效應(yīng),增強(qiáng)掃描后T2WI圖像的病灶信號(hào)噪聲比會(huì)明顯下降[15]。過(guò)去的研究表明,Gd-DTPA增強(qiáng)掃描后快速自旋回波序列(TSE)或快速自旋回波序列-快速翻轉(zhuǎn)恢復(fù)序列(TSE-STIR)的T2WI圖像上,實(shí)性肝臟病灶或非實(shí)性肝臟病灶的病灶信號(hào)噪聲比輕度上升。這可能是由于細(xì)胞外間隙殘存對(duì)比劑的T1弛豫時(shí)間縮短效應(yīng)減少了磁化轉(zhuǎn)化所致[16]。
圖2 肝臟局灶性病變患者M(jìn)RI圖
A:肝細(xì)胞癌,箭頭所示為病灶,左上圖見(jiàn)Gd-EOB-DTPA增強(qiáng)掃描前T2WI病灶呈中等偏高信號(hào);右上圖見(jiàn)增強(qiáng)掃描后T2WI病灶呈中等偏高信號(hào);左下圖見(jiàn)增強(qiáng)掃描動(dòng)脈期T1WI病灶不均勻強(qiáng)化;右下圖見(jiàn)增強(qiáng)掃描肝細(xì)胞期T1WI病灶呈低信號(hào)。B:肝局灶性結(jié)節(jié)增生,箭頭所示為病灶,左上圖見(jiàn)增強(qiáng)掃描前T2WI病灶呈中等信號(hào);右上圖見(jiàn)增強(qiáng)掃描后T2WI病灶呈中等偏低信號(hào);左下圖見(jiàn)增強(qiáng)掃描動(dòng)脈期T1WI病灶呈高信號(hào);右下圖見(jiàn)增強(qiáng)掃描肝細(xì)胞期T1WI病灶呈低信號(hào)。C:肝轉(zhuǎn)移瘤,箭頭所示為病灶,左上圖和右上圖分別見(jiàn)增強(qiáng)掃描前T2WI和增強(qiáng)掃描后T2WI病灶呈中等信號(hào);左下圖見(jiàn)增強(qiáng)掃描動(dòng)脈期T1WI病灶呈高信號(hào);右下圖見(jiàn)增強(qiáng)掃描肝細(xì)胞期T1WI病灶呈低信號(hào)。D:肝血管瘤,箭頭所示為病灶,左上圖和右上圖分別見(jiàn)增強(qiáng)掃描前T2WI和增強(qiáng)掃描后T2WI呈高信號(hào);左下圖見(jiàn)增強(qiáng)掃描動(dòng)脈期T1WI病灶呈高信號(hào);右下圖見(jiàn)增強(qiáng)掃描肝細(xì)胞期T1WI病灶呈低信號(hào)。E: 肝細(xì)胞癌,箭頭所示為病灶,左上圖示增強(qiáng)掃描前T2WI病灶顯示不清楚;右上圖示增強(qiáng)掃描后T2WI S4病灶呈類圓形稍高信號(hào);左下圖示增強(qiáng)掃描動(dòng)脈期S4病灶呈明顯強(qiáng)化;右下圖示肝細(xì)胞期病灶呈低信號(hào)。F:肝細(xì)胞癌,箭頭所示為病灶,左上圖示增強(qiáng)掃描前T2WI S5病灶呈類圓形稍高信號(hào);右上圖示增強(qiáng)掃描后T2WI病灶顯示不清楚;左下圖示增強(qiáng)掃描動(dòng)脈期S5病灶呈明顯強(qiáng)化;右下圖示肝細(xì)胞期病灶呈低信號(hào)
與前述研究不同的是,本研究結(jié)果顯示,幾種肝臟局灶性病變Gd-EOB-DTPA增強(qiáng)掃描后HASTE序列T2WI圖像上的病灶信號(hào)噪聲比均較增強(qiáng)掃描前有所減低。筆者分析,造成這種結(jié)果的可能原因是本研究中在增強(qiáng)掃描后T2WI于注藥后5 min進(jìn)行,此時(shí)大部分對(duì)比劑仍位于細(xì)胞外間隙,產(chǎn)生T2弛豫時(shí)間縮短效應(yīng),本研究中肝血管瘤增強(qiáng)掃描后T2WI圖像病灶信號(hào)噪聲比下降程度大于實(shí)性肝臟腫瘤的下降程度,也提示了這一點(diǎn)。
本研究結(jié)果還顯示,盡管肝臟局灶性病變?cè)鰪?qiáng)掃描后T2WI圖像的病灶信號(hào)噪聲比普遍下降,增強(qiáng)掃描后T2WI圖像的病灶-肝臟噪聲比卻上升。4個(gè)肝細(xì)胞癌病灶和2個(gè)肝轉(zhuǎn)移瘤病灶在增強(qiáng)掃描前T2WI顯示不清,在增強(qiáng)掃描后T2WI卻能顯示清晰。筆者認(rèn)為,這可能由于肝臟實(shí)質(zhì)受Gd-EOB-DTPA T1弛豫時(shí)間或T2弛豫時(shí)間縮短效應(yīng)的影響大于肝臟局灶性病變,因此肝臟實(shí)質(zhì)在增強(qiáng)掃描后T2WI圖像信號(hào)強(qiáng)度的下降程度亦大于肝臟局灶性病變,兩者的對(duì)比較增強(qiáng)掃描前加大,故更有利于病灶的檢出。
基于上述研究結(jié)果,筆者認(rèn)為增強(qiáng)掃描后行HASTE序列T2WI掃描可作為Gd-EOB-DTPA增強(qiáng)MRI檢查的常規(guī)流程??紤]到延遲期時(shí)肝細(xì)胞源性腫瘤會(huì)攝取Gd-EOB-DTPA,需特別留意肝硬化患者增強(qiáng)掃描后T2WI圖像,因?yàn)椴≡詈透闻K攝取對(duì)比劑的量的多少會(huì)影響病灶本身的信號(hào)強(qiáng)度。本研究中1個(gè)肝細(xì)胞癌病灶在增強(qiáng)掃描后T2WI顯示不清楚,在增強(qiáng)掃描前T2WI卻能清晰顯示,這可能是病灶攝取了對(duì)比劑,使原本的T2WI圖像信號(hào)強(qiáng)度降低,分化好的肝細(xì)胞癌可能更容易出現(xiàn)這種情況。同樣推斷,原本T2WI圖像低信號(hào)的病灶,如肝硬化再生結(jié)節(jié),可能因肝實(shí)質(zhì)信號(hào)減低而在增強(qiáng)掃描后T2WI圖像表現(xiàn)為等信號(hào),此類患者增強(qiáng)掃描后T2WI圖像上表現(xiàn)為高信號(hào)的病灶,并不一定提示惡性病變。
本研究存在的不足之處如下:首先,并非所有病灶在行MRI檢查時(shí)均經(jīng)臨床手術(shù)證實(shí),有可能高估了各期圖像診斷病灶的敏感性。其次,只有同時(shí)進(jìn)行了增強(qiáng)掃描前T2WI和增強(qiáng)掃描后T2WI檢查的患者才被納入此次研究,可能存在選擇偏倚。再次,筆者僅研究了增強(qiáng)掃描前、增強(qiáng)掃描后5 min時(shí)的T2WI圖像,無(wú)研究其他時(shí)期。另外,本研究局限于肝細(xì)胞癌、局灶性結(jié)節(jié)增生、肝轉(zhuǎn)移瘤和肝血管瘤,無(wú)覆蓋所有的肝臟局灶性病變。
綜上所述,Gd-EOB-DTPA增強(qiáng)掃描后HASTE序列T2WI對(duì)肝細(xì)胞癌、局灶性結(jié)節(jié)增生、肝轉(zhuǎn)移瘤和肝血管瘤這幾類肝臟局灶性病變的檢出和診斷能力與增強(qiáng)掃描前T2WI相仿。因此,對(duì)于大多數(shù)進(jìn)行Gd-EOB-DTPA增強(qiáng)掃描MRI檢查的肝臟局灶性病變患者,可在動(dòng)態(tài)增強(qiáng)掃描后進(jìn)行T2WI以節(jié)省掃描時(shí)間。
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(本文編輯:洪悅民)
臨床研究論著
作者單位:510080廣州,廣東省人民醫(yī)院