廖成成唐 琪吳圣明覃云英
1.廣西醫(yī)科大學(xué)附屬腫瘤醫(yī)院淋巴血液腫瘤科,廣西南寧530021;2.廣西醫(yī)科大學(xué)附屬腫瘤醫(yī)院影像科,廣西南寧530021;3.廣西醫(yī)科大學(xué)附屬腫瘤醫(yī)院病理科,廣西南寧530021
淋巴瘤磁共振表觀彌散系數(shù)與腫瘤細(xì)胞密度及淋巴瘤進(jìn)展的相關(guān)性
廖成成1唐 琪2吳圣明3覃云英2
1.廣西醫(yī)科大學(xué)附屬腫瘤醫(yī)院淋巴血液腫瘤科,廣西南寧530021;2.廣西醫(yī)科大學(xué)附屬腫瘤醫(yī)院影像科,廣西南寧530021;3.廣西醫(yī)科大學(xué)附屬腫瘤醫(yī)院病理科,廣西南寧530021
目的探討磁共振彌散加權(quán)成像(DWI)的淋巴瘤表觀彌散系數(shù)(ADC)值與腫瘤細(xì)胞密度及淋巴瘤進(jìn)展的相關(guān)性。方法制備20只Raji淋巴瘤Balb/c荷瘤裸鼠,對(duì)其不同生長(zhǎng)階段的淋巴瘤進(jìn)行MR掃描,運(yùn)用Image J軟件進(jìn)行病理學(xué)分析及腫瘤細(xì)胞密度測(cè)量。統(tǒng)計(jì)分析ADC值和腫瘤細(xì)胞密度的相關(guān)性及與腫瘤細(xì)胞不同生長(zhǎng)階段之間的關(guān)系。結(jié)果腫瘤接種后第5周淋巴瘤ADC值[(0.58±0.07)×10-3mm2/s]顯著低于接種后第3周[(0.74±0.08)×10-3mm2/s],差異有高度統(tǒng)計(jì)學(xué)意義(t=4.722,P<0.01);腫瘤接種后第3周的腫瘤細(xì)胞密度[(45.84± 3.57)%]顯著低于接種后第5周[(55.51±2.98)%],差異有高度統(tǒng)計(jì)學(xué)意義(t=6.561,P<0.01);淋巴瘤ADC值與淋巴瘤細(xì)胞密度及淋巴瘤進(jìn)展均呈顯著負(fù)相關(guān)(r=-0.97、-0.97,均P<0.01)。結(jié)論淋巴瘤ADC值可用于分析和評(píng)價(jià)淋巴瘤的進(jìn)展,進(jìn)而判斷預(yù)后,指導(dǎo)治療,監(jiān)測(cè)療效。
淋巴瘤;腫瘤細(xì)胞密度;淋巴瘤進(jìn)展;表觀彌散系數(shù)值
[Abstract]Objective To study the correlation of apparent diffusion coefficient(ADC)value with the tumor cellularity density and the development of lymphoma.Methods Twenty Raji cell stress nude mice were prepared.MR was used to scan their different grow stage.Pathological analysis and the cellularity density were detected by Image J software.The correlation of ADC value with tumor cell density and the different progress were statistically analyzed.Results The ADC value of the 5th week after inoculation[(0.58±0.07)×10-3mm2/s]was significantly lower than the value of the 3th week after inoculation[(0.74±0.08)×10-3mm2/s],the difference was statistically significant(t=4.722,P<0.01);the density of xenograft at the 3th week after inoculation[(45.84±3.57)%]was significantly lower than that of the 5th after inoculation[(55.51±2.98)%],the difference was statistically significant(t=-6.561,P<0.01);ADC value was negatively correlated with cellularity density and the stage of lymphoma progression(r=-0.97,-0.97,all P<0.01).Conclusion ADC value can be used to analyze and evaluate the density and development process of lymphoma,and judgment the prognosis,thus direct the treatment,monitoring efficacy.
[Key words]Lymphoma;Tumor cell density;Lymphoma development process;Apparent diffusion coefficient
侵襲性淋巴瘤是化療可以治愈的惡性腫瘤之一,因而化療后療效評(píng)估的準(zhǔn)確性對(duì)于臨床醫(yī)生采用適宜的化療方案和及時(shí)準(zhǔn)確的改變治療策略顯得尤為重要。B超、增強(qiáng)CT為兩種運(yùn)用廣泛的影像學(xué)評(píng)估手段,但較難鑒別化療后淋巴瘤細(xì)胞殘留與化療后組織壞死、纖維化,已經(jīng)無(wú)法適應(yīng)現(xiàn)階段淋巴瘤的個(gè)體化及精準(zhǔn)治療。近年來(lái),PET/CT因能夠?qū)⒋x活躍的殘留病灶顯像,成為侵襲性淋巴瘤療效評(píng)價(jià)的推薦手段[1]。但PET/CT檢查費(fèi)用高、造影劑具有電離輻射、對(duì)于惰性的淋巴瘤診斷的敏感性及特異性低、組織分辨率較差等局限性,限制了其在臨床的推廣;特別是在年輕的人群中,電離輻射的暴露有著比年長(zhǎng)者更高的電離輻射誘導(dǎo)的第二腫瘤的發(fā)生率[2-3]。磁共振作為一種非電離輻射的手段廣泛應(yīng)用于各實(shí)體腫瘤的診斷及療效評(píng)估中。磁共振彌散加權(quán)成像可通過(guò)表觀彌散系數(shù)值(apparent diffusion coefficient,ADC)值反映水分子在活體組織內(nèi)的彌散運(yùn)動(dòng),可達(dá)到了類PET的功能成像效果,從而間接評(píng)估腫瘤細(xì)胞增殖速度及密度,本研究主要探討淋巴瘤磁共振彌散加權(quán)成像(diffusion weighted imaging,DWI)ADC與腫瘤細(xì)胞密度及淋巴瘤進(jìn)展的相關(guān)性。
1.1對(duì)象
選取20只SPF雄性Balb/c裸鼠[廣西醫(yī)科大學(xué)實(shí)驗(yàn)中心,許可證號(hào):SYXK-(桂)2014-0002,實(shí)驗(yàn)動(dòng)物合格證編號(hào):No.45000300000546]。周齡4~5周,平均(5.0±1.0)周;平均體重(16.5±0.5)g。在廣西醫(yī)科大學(xué)實(shí)驗(yàn)動(dòng)物房飼養(yǎng),將環(huán)境溫度調(diào)節(jié)在22~25℃,相對(duì)濕度調(diào)節(jié)在50%~60%。實(shí)驗(yàn)細(xì)胞為人Burkitt's淋巴瘤細(xì)胞株Raji細(xì)胞,由廣西醫(yī)科大學(xué)醫(yī)學(xué)科學(xué)實(shí)驗(yàn)中心提供。本實(shí)驗(yàn)經(jīng)廣西醫(yī)科大學(xué)動(dòng)物倫理委員會(huì)審批通過(guò),并按照動(dòng)物倫理委員會(huì)的要求實(shí)施實(shí)驗(yàn)。
1.2儀器與試劑
磁共振動(dòng)物專用線圈直徑5 cm(江陰萬(wàn)康醫(yī)療科技有限公司);GE discovery 750W 3.0T磁共振掃描儀(日本GE healthcare公司);RPMI-1640培養(yǎng)基(上海博升生物科技有限公司);胎牛血清(上海恪敏生物科技有限公司)。
1.3方法
1.3.1細(xì)胞培養(yǎng)和處理及淋巴瘤動(dòng)物模型制備采用含10%胎牛血清的RPMI-1640培養(yǎng)基在37℃、5% CO2培養(yǎng)箱中培養(yǎng)Raji淋巴瘤細(xì)胞。取對(duì)數(shù)期生長(zhǎng)的Raji細(xì)胞,調(diào)整細(xì)胞濃度為5×107/mL,將0.2 mL細(xì)胞懸液接種在每只Balb/c鼠右下肢皮下。每天對(duì)小鼠進(jìn)行檢查,觀察小鼠腫瘤的生長(zhǎng)情況。嚴(yán)格依據(jù)淋巴瘤細(xì)胞接種后時(shí)間將其分為接種后第3、5周兩個(gè)階段。
1.3.2磁共振檢查和圖像處理分別于開始移植瘤接種后第3周及第5周對(duì)小鼠進(jìn)行磁共振掃描,掃描前用10%水合氯醛(3.5 mL/kg)腹腔注射麻醉小鼠。麻醉滿意后在磁共振動(dòng)物專用線圈內(nèi)放置荷瘤小鼠,取仰臥位并固定于線圈中央。首先行TSE T2WI軸位、矢狀位掃描定位腫瘤,后行DWI軸位掃描,掃描參數(shù):TSE T2WI:TR/TE 4000 ms/85 ms,翻轉(zhuǎn)角150°,F(xiàn)OV 56 mm×90 mm,矩陣200×320,層厚/層距7 mm/1 mm,回波鏈長(zhǎng)度(echo train length):10;DWI采用單次激發(fā)SE-EPI序列TR/TE 3000 ms/58.5 ms、翻轉(zhuǎn)角150°,F(xiàn)OV 76 mm×80 mm,矩陣128×125,層厚/層距7 mm/1 mm, b值分別為0、800 s/mm2,在X、Y、Z軸方向施加彌散敏感梯度。磁共振掃描儀所獲取的DWI數(shù)據(jù)采用GE Medical Systems Functool 9.4.05軟件重建ADC圖。在病灶最大層面避開囊變、壞死、出血區(qū)及鄰近區(qū)域,選擇信號(hào)較均勻區(qū)域?yàn)楦信d趣區(qū)(ROI),獲取病灶的ADC值。每1個(gè)病灶層面進(jìn)行3次測(cè)量后取平均值。
1.3.3細(xì)胞密度分析測(cè)量ADC后取得BALB/c裸鼠移植瘤病理組織標(biāo)本,將標(biāo)本用福爾馬林固定后送病理科,包埋、切片、常規(guī)HE染色。每張組織切片(HE染色,200倍)隨機(jī)選取5個(gè)視野,選取視野盡量避開,壞死、炎癥及血管等區(qū)域,圖片經(jīng)電子顯微照相機(jī)(奧林巴斯DP22)拍攝保存后導(dǎo)入計(jì)算機(jī)。所有照片用ImageJ 2.1.4軟件分析處理,將彩色病理照片轉(zhuǎn)換為8位灰階黑白圖片,再選擇合適閾值,計(jì)算機(jī)自動(dòng)統(tǒng)計(jì)出每個(gè)視野中細(xì)胞核面積占照片面積百分比即為腫瘤細(xì)胞密度,用百分率表示,每個(gè)淋巴瘤標(biāo)本的細(xì)胞密度為5個(gè)視野的平均值。
1.4統(tǒng)計(jì)學(xué)方法
采用語(yǔ)言軟件包(R version 3.3.1,www.r-project.org)統(tǒng)計(jì)學(xué)軟件進(jìn)行數(shù)據(jù)分析,計(jì)量資料數(shù)據(jù)用均數(shù)±標(biāo)準(zhǔn)差(x±s)表示,兩組間比較采用t檢驗(yàn);分別采用Pearson相關(guān)分析、Spearman等級(jí)相關(guān)分析淋巴瘤ADC值與細(xì)胞密度、淋巴瘤進(jìn)展計(jì)數(shù)的相關(guān)性;以P< 0.05為差異有統(tǒng)計(jì)學(xué)意義。
2.1荷瘤小鼠病理切片及磁共振圖像的表現(xiàn)
腫瘤接種后第3周的荷瘤小鼠病理切片可見(jiàn),瘤細(xì)胞較稀疏,間質(zhì)成分較多;腫瘤接種后第5周的荷瘤小鼠病理切片可見(jiàn),細(xì)胞較致密,間質(zhì)成分較少。腫瘤接種后第5周的小鼠瘤細(xì)胞排列較接種后第3周的致密,間質(zhì)成分也較少,見(jiàn)圖1。小鼠磁共振瘤體DWI圖像呈高信號(hào),而ADC圖像信號(hào)減低。腫瘤接種后第5周的小鼠瘤體DWI信號(hào)較接種后第3周的增強(qiáng),而ADC信號(hào)較接種后第3周的減弱,見(jiàn)圖2。
2.2不同發(fā)展階段淋巴瘤ADC值和淋巴瘤細(xì)胞密度的差異
腫瘤接種后第3周淋巴瘤ADC值顯著高于接種后5周的淋巴瘤(t=4.722,P<0.01),腫瘤接種后3周的淋巴瘤細(xì)胞密度顯著低于接種后第5周的淋巴瘤(t=6.561,P<0.01)。見(jiàn)表1。
2.3淋巴瘤細(xì)胞密度、淋巴瘤進(jìn)展與ADC值的相關(guān)性分析
淋巴瘤ADC值與淋巴瘤細(xì)胞密度及淋巴瘤進(jìn)展均呈顯著負(fù)相關(guān)(r=-0.97、-0.97,均P<0.01)。見(jiàn)圖3。
表1 不同發(fā)展階段淋巴瘤ADC值和腫瘤細(xì)胞密度()
表1 不同發(fā)展階段淋巴瘤ADC值和腫瘤細(xì)胞密度()
注:ADC:表觀彌散系數(shù)
腫瘤接種時(shí)間只數(shù)ADC值(×10-3mm2/s)腫瘤細(xì)胞密度(%)接種第3周接種第5周10 10 t值P值0.74±0.08 0.58±0.07*4.722 <0.01 45.84±3.57 55.51±2.98*6.561 <0.01
圖1 荷瘤小鼠的病理圖像(HE,200×)
圖2 荷瘤小鼠的磁共振圖像
圖3 淋巴瘤細(xì)胞密度與磁共振ADC值相關(guān)性
磁共振成像技術(shù)因可直接顯示任意角度的切面像、無(wú)電離輻射、擁有高于CT數(shù)倍的軟組織分辨能力及不用造影劑就可得到很好的軟組織對(duì)比度等優(yōu)勢(shì),在惡性腫瘤的診斷及療效評(píng)估方面日益得到廣泛的應(yīng)用,但傳統(tǒng)的磁共振成像及其掃描序列難以提供腫瘤病理學(xué)及增殖程度的信息,而DWI為磁共振的一種功能成像技術(shù),不僅能夠反映腫瘤形態(tài)學(xué)的變化,還能夠直接反映活體內(nèi)水分子的微觀運(yùn)動(dòng)。與傳統(tǒng)的結(jié)構(gòu)性磁共振成像技術(shù)比較,它能提供如細(xì)胞膜完整性、組織結(jié)構(gòu)等更多的分子生物學(xué)信息,從而間接反映腫瘤細(xì)胞的增殖活性[4-5]。
DWI技術(shù)通過(guò)對(duì)組織施加彌散敏感的梯度脈沖后測(cè)定組織中水?dāng)U散受限的方向及程度來(lái)間接反映組織的微觀結(jié)構(gòu)變化。DWI信號(hào)衰減參數(shù)稱為ADC,ADC值可以反映腫瘤細(xì)胞密度并能夠?qū)λ肿釉诨铙w組織內(nèi)的彌散運(yùn)動(dòng)狀況進(jìn)行定量評(píng)價(jià)[6],理論上能更早地預(yù)測(cè)腫瘤進(jìn)展及判斷治療效果。相關(guān)醫(yī)學(xué)研究表明[7],DWI一方面對(duì)水分子在細(xì)胞內(nèi)外間隙的彌散運(yùn)動(dòng)變化敏感,另一方面還對(duì)細(xì)胞水腫敏感,鈉鉀泵功能障礙可能是誘發(fā)因素之一,ADC值可有效地在組織微觀水平上反映出這些變化,ADC值將可能成為一種分析細(xì)胞功能的有效參數(shù)。
一般來(lái)說(shuō),惡性增殖的腫瘤細(xì)胞密度要遠(yuǎn)高于良性腫瘤,大量的細(xì)胞實(shí)驗(yàn)[8-10]及動(dòng)物實(shí)驗(yàn)[11-13]證實(shí),惡性腫瘤分化程度越差、細(xì)胞增殖越活躍,其腫瘤組織內(nèi)水分子擴(kuò)散受限效應(yīng)越顯著。Lyng等[8]研究發(fā)現(xiàn),細(xì)胞密度高的同一種類的腫瘤細(xì)胞,有更低通透性的半透明細(xì)胞膜、相對(duì)更高的細(xì)胞內(nèi)水含量、相對(duì)更小的細(xì)胞外間隙與細(xì)胞密度可使其內(nèi)自由水分子的彌散受限,與其磁共振的ADC值呈正相關(guān)。此外,腫瘤細(xì)胞的異形性、病理類型、細(xì)胞核漿比例、腫瘤間質(zhì)成分、血流灌注情況等亦是導(dǎo)致ADC值改變的因素[14-15]。
盡管已有較多的研究證實(shí)多數(shù)各類惡性腫瘤的細(xì)胞密度與其ADC值呈負(fù)相關(guān),但淋巴瘤的細(xì)胞密度、進(jìn)展與ADC值的關(guān)系研究較少[16],本研究結(jié)果顯示,在淋巴瘤小鼠模型中,淋巴瘤細(xì)胞的密度及腫瘤進(jìn)展均與淋巴瘤的ADC值呈顯著負(fù)相關(guān),與既往多數(shù)研究相符[17]。其機(jī)制可能為淋巴瘤細(xì)胞密度隨著腫瘤的生長(zhǎng)增殖而增加,細(xì)胞外的空間將受到壓縮,細(xì)胞外間質(zhì)水的流動(dòng)性減少,進(jìn)而引起細(xì)胞內(nèi)的水分子擴(kuò)散受限。細(xì)胞內(nèi)外兩種因素綜合作用使得水分子的擴(kuò)散運(yùn)動(dòng)受到極大程度的限制,其相應(yīng)區(qū)域的腫瘤的ADC值也隨之降低[18-20]。相反如果在腫瘤壞死區(qū)域,由于細(xì)胞間成分增多,水分子擴(kuò)散障礙減少,其ADC值升高[21]。
綜上所述,本研究發(fā)現(xiàn),淋巴瘤ADC與腫瘤細(xì)胞密度及淋巴瘤進(jìn)展呈顯著負(fù)相關(guān)。這可能可以幫助臨床醫(yī)生對(duì)淋巴瘤進(jìn)展進(jìn)行分析和評(píng)價(jià),進(jìn)而對(duì)預(yù)后進(jìn)行判斷,對(duì)治療進(jìn)行指導(dǎo),對(duì)療效進(jìn)行監(jiān)測(cè),亦可為DWI技術(shù)在淋巴瘤診斷相關(guān)的臨床試驗(yàn)提供參考依據(jù),值得臨床充分重視。但ADC值大小變化與近期療效的相關(guān)性以及是否能對(duì)淋巴瘤遠(yuǎn)期療效進(jìn)行預(yù)測(cè)等諸多問(wèn)題還需更多的研究進(jìn)一步探討。
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Correlation of MRI apparent diffusion coefficient with tumor cell density and development process of lymphoma
LIAO Chengcheng1TANG Qin2WU Shengming3QIN Yunying2
1.Department of Oncology,Affiliated Tumor Hospital of Guangxi Medical University,Guangxi Zhuang Autonomous Region,Nanning530021,China;2.Department of Imaging,Affiliated Tumor Hospital of Guangxi Medical University,Guangxi Zhuang Autonomous Region,Nanning530021,China;3.Department of Pathology,Affiliated Tumor Hospital of Guangxi Medical University,Guangxi Zhuang Autonomous Region,Nanning530021,China
R733
A
1673-7210(2016)09(c)-0031-04
2016-04-20本文編輯:任念)
廣西壯族自治區(qū)衛(wèi)生和計(jì)劃生育委員會(huì)自籌經(jīng)費(fèi)科研課題項(xiàng)目(Z2016504)。