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      磁共振小視野彌散加權(quán)成像技術(shù)在影像診斷中的研究進(jìn)展

      2017-03-22 04:54:42徐俏宇孫宏亮徐妍妍王武
      磁共振成像 2017年7期
      關(guān)鍵詞:偽影視野分辨率

      徐俏宇,孫宏亮,徐妍妍,王武

      磁共振小視野彌散加權(quán)成像技術(shù)在影像診斷中的研究進(jìn)展

      徐俏宇,孫宏亮,徐妍妍,王武*

      磁共振彌散加權(quán)成像作為一種功能成像已經(jīng)成為常規(guī)磁共振成像診斷中的重要組成部分。然而在目前的臨床應(yīng)用中較為廣泛使用的全視野彌散加權(quán)成像技術(shù),其圖像質(zhì)量較差,解剖結(jié)構(gòu)分辨率較低,容易產(chǎn)生比較嚴(yán)重的偽影,圖像的變形和失真等問題。隨著技術(shù)的進(jìn)展,小視野彌散加權(quán)成像技術(shù)通過(guò)在相位編碼方向上縮減視野大小等方法顯著提高了圖像質(zhì)量及組織結(jié)構(gòu)分辨能力,減輕圖像偽影、變形、失真等情況,這對(duì)于體積較小、結(jié)構(gòu)精細(xì)、解剖部位附近磁化率變化較大或易受不自主生理性運(yùn)動(dòng)影響的器官及部位尤為重要。作者對(duì)小視野彌散加權(quán)成像的成像原理及其在各器官中的研究進(jìn)展進(jìn)行綜述。

      彌散磁共振成像;視野;診斷,鑒別

      在影像診斷中,MRI常規(guī)T2序列具有良好的空間分辨率,但在檢出小的低級(jí)別腫瘤時(shí)易出現(xiàn)假陰性,在對(duì)腫瘤與出血或炎癥進(jìn)行鑒別,以及評(píng)價(jià)其治療反應(yīng)等方面時(shí)準(zhǔn)確率欠佳[1]。彌散加權(quán)成像(diffusion-weighted imaging,DWI)可以在無(wú)需對(duì)比劑的情況下檢測(cè)活體組織內(nèi)水分子的彌散變化以及彌散受限的程度,量化腫瘤的病理學(xué)特征及生物學(xué)行為[2-3]。所以將T2加權(quán)與DWI的功能信息相結(jié)合,能更準(zhǔn)確地定位病變,評(píng)估病變性質(zhì)、治療效果以及預(yù)后[4]。然而在臨床中最常用的DWI序列仍是以單次激發(fā)平面回波成像(singleshot echo-planar imaging,ssEPI)為基礎(chǔ),該成像方式存在易出現(xiàn)偽影、失真、空間分辨率有限等缺陷,影響病變檢出的準(zhǔn)確率。隨著技術(shù)的進(jìn)步,小視野彌散加權(quán)成像(reduced field of view diffusion weighted imaging,rFOV-DWI)可以獲得更優(yōu)越的圖像質(zhì)量、提高組織結(jié)構(gòu)分辨能力、顯著減少偽影和圖像失真[5]。筆者對(duì)rFOV-DWI的成像原理及其在各器官中的研究進(jìn)展進(jìn)行綜述。

      1 rFOV DWI的原理及總體優(yōu)勢(shì)

      在全視野彌散加權(quán)成像(full field of view diffusion weighted imaging,fFOV-DWI)中,因其視野較大常同時(shí)覆蓋液體、氣體、軟組織、骨骼等磁敏感程度不同的物質(zhì),臨床中越來(lái)越多地使用更高的3.0 T場(chǎng)強(qiáng)來(lái)獲得較高的信噪比等,使得B0場(chǎng)的不均一性帶來(lái)的問題更為突出[6-7]。再加上ssEPI本身回波鏈很長(zhǎng),容易累積相位誤差,而且相位方向上帶寬較小,易導(dǎo)致圖像的變形。長(zhǎng)回波鏈本身也會(huì)導(dǎo)致T2*衰減,進(jìn)而導(dǎo)致圖像的模糊和信號(hào)的損失。一般為了控制圖像變形程度,ssEPI的圖像空間分辨率比較低,而且如果增大矩陣則增加回波鏈長(zhǎng)度加劇圖像變形和模糊,故常規(guī)序列中通過(guò)增大矩陣來(lái)提升分辨率的方法不適用于ssEPI[8]。

      rFOV-DWI使用了2D空間選擇性射頻脈沖(two-dimensional spatially selective radiofrequency pulses,2D RF)和180°回聚脈沖技術(shù)。這與常規(guī)序列的激發(fā)脈沖僅在目標(biāo)層面方向上選擇性激發(fā)一個(gè)指定厚度平面內(nèi)的組織不同,2DRF是由兩個(gè)在正交方向上獨(dú)立控制厚度的射頻脈沖組成,分別為層面選擇方向和相位編碼方向。在這兩個(gè)方向上同時(shí)選擇性激發(fā)特定厚度的組織,從而縮小相位方向上的FOV,減少相位編碼步數(shù),縮短EPI回波鏈長(zhǎng)度及回波時(shí)間,而且2D RF擁有整合B1場(chǎng)強(qiáng)信息后單獨(dú)調(diào)整每個(gè)RF脈沖的相位和振幅使其達(dá)到更加均一的反轉(zhuǎn)角度的優(yōu)勢(shì),這樣就可以達(dá)到個(gè)體或容積特異性的修正B1場(chǎng)的目的,因此其圖像幾何變形程度減少、磁敏感偽影減低、空間分辨率提高又不增加掃描時(shí)間[5,9-11]。此外,在2DRF的層面選擇方向上使用180°重聚脈沖縮減帶寬,進(jìn)而達(dá)到抑制除周期性2D激發(fā)脈沖之外的所有信號(hào)的作用。其中EPI序列的脂肪抑制尤為重要,否則將會(huì)導(dǎo)致嚴(yán)重的偽影,而2DRF與180°重聚脈沖的的結(jié)合可以在充分抑制脂肪的同時(shí)激發(fā)水信號(hào),消除了化學(xué)位移的影響,從而有助于微小病灶的檢出[12]。2D平面回波射頻脈沖還具有不激發(fā)鄰近層面的優(yōu)勢(shì),這使得連續(xù)多層面掃描得以實(shí)現(xiàn)[11]。與其他可以提升DWI清晰程度及減少圖像形變程度的多激發(fā)技術(shù)相比,rFOV-DWI不需要明顯增加掃描時(shí)間,且不需要復(fù)雜耗時(shí)的重建技術(shù)[13]。

      2 rFOV-DWI在各器官中的應(yīng)用及研究進(jìn)展

      2.1 脊髓

      脊髓的橫斷面較小,骨組織及腦脊液邊緣磁化率變化較大[14-15],尤其對(duì)于低位脊髓來(lái)說(shuō),其體積更小,更易受生理性不自主運(yùn)動(dòng)和部分容積效應(yīng)的影響[16-17],這即使在目前較為先進(jìn)的方法彌散張量成像中,檢出軸突和髓鞘的疾病時(shí)都不十分穩(wěn)定[18-19]。rFOV-DWI可以有效減少圖像失真及偽影,并進(jìn)一步觀察神經(jīng)系統(tǒng)的微觀結(jié)構(gòu)變化,這對(duì)于具有膀胱及性功能障礙等癥狀的神經(jīng)系統(tǒng)疾病的診斷是有幫助的,例如多發(fā)性硬化,脊髓損傷,多系統(tǒng)萎縮等[20]。此外,超高b值小視野彌散加權(quán)成像(ultrahigh-b radial DWI,UHB-rDWI)可以增加白質(zhì)和灰質(zhì)的對(duì)比度,提高分辨率和信噪比,非線性靜態(tài)磁場(chǎng)不均勻性導(dǎo)致的圖像失真顯著減少[15]。尤其當(dāng)b>5000 s/mm2時(shí),UHB-rDWI可以在總信號(hào)強(qiáng)度保持不變的同時(shí)使軸突之外的信號(hào)幾乎完全消失,從而更好地評(píng)估白質(zhì)病變。在急性脊髓缺血損傷的病人中,初發(fā)數(shù)小時(shí)內(nèi)可以進(jìn)行溶栓治療,因此早期診斷尤為重要,DWI (數(shù)小時(shí))可早于T2序列(1~2 d)識(shí)別梗死[20],rFOV-DWI能在縮短掃描時(shí)間的同時(shí)得到高分辨圖像,這對(duì)更精確地呈現(xiàn)圖像細(xì)節(jié)和判斷具體血供損傷區(qū)域有所幫助[14]。

      2.2 前列腺

      前列腺在體內(nèi)位置較深,作為腫瘤好發(fā)部位的前列腺外周區(qū)毗鄰含有氣體的直腸,F(xiàn)OV內(nèi)嚴(yán)重的磁敏感不均一及運(yùn)動(dòng)偽影導(dǎo)致較為嚴(yán)重的圖像失真和偽影[21]。因此能在小范圍內(nèi)集中激發(fā)的rFOV-DWI優(yōu)勢(shì)明顯,包括圖像質(zhì)量顯著提高,偽影、模糊、變形的程度下降,解剖結(jié)構(gòu)分辨更為清晰(前列腺包膜、外周區(qū)、移行區(qū)、尿道周圍區(qū)),有利于小病灶的檢出和更為精準(zhǔn)的T分期[5,10,21-22]。另一方面前列腺本身及病變的體積均較小,DWI序列與T2序列對(duì)齊比較時(shí)(對(duì)齊精度)存在失真和角誤差,單個(gè)平面中病變的平均直徑僅1.3~1.4 cm[22],因此其精度對(duì)于前列腺影像圖像解讀尤為重要[10,22-23]。rFOV-DWI可以提高前列腺腺體本身(DWI圖像超出T2圖像中前列腺輪廓外的程度)以及前列腺病變(包括偏離病變中心的程度和超出病變外緣的程度)的對(duì)齊精度[10,22]。有研究表明其在矢狀面上超出病變外緣的程度從0.5 cm下降到0.3 cm,在冠狀面上從0.4 cm下降到0.2 cm[22],因而在MRI引導(dǎo)下前列腺腫瘤活檢和放射治療計(jì)劃制訂時(shí),病灶的定位和勾畫更加精確;rFOV-DWI擁有更高的真陽(yáng)性率,病變檢出的敏感性從0.59提升到0.66;ROC曲線下的面積(area under the curve,AUC)增加,因而擁有更優(yōu)的診斷價(jià)值。雖然目前研究表明兩個(gè)序列表觀彌散系數(shù)(apparent diffusion coefficient,ADC)數(shù)值結(jié)果沒有顯著的統(tǒng)計(jì)學(xué)差異[10,22],但rFOV-DWI ADC圖失真變形程度下降,特別在前列腺包膜、尿道周圍區(qū)圖像質(zhì)量明顯提高[5]。

      2.3 膀胱腫瘤

      膀胱腫瘤因治療方式不同,區(qū)分非浸潤(rùn)性(T1期及以下)和浸潤(rùn)性膀胱癌(T2期及以上)尤為重要。rFOV-DWI顯著提高膀胱圖像質(zhì)量,減輕偽影和幾何變形,因而T分期更為精準(zhǔn),尤其對(duì)于T2分期以上的腫瘤,T2序列與rFOV-DWI聯(lián)合使用的診斷準(zhǔn)確率、特異性、AUC都顯著高于單獨(dú)使用T2序列或聯(lián)合使用fFOV-DWI序列[24]。有研究報(bào)道單獨(dú)使用T2序列,T2聯(lián)合fFOV-DWI、T2聯(lián)合rFOV-DWI的診斷正確率分別為57%、70%、78%;AUC分別為0.781,0.771,0.826[24]。對(duì)于ADC值而言,膀胱腫瘤顯著低于正常組織[25],惡性腫瘤顯著低于良性腫瘤[26]及正常組織[27],肌層浸潤(rùn)性膀胱癌顯著低于非肌層浸潤(rùn)性膀胱癌[24],G3分級(jí)以上的膀胱腫瘤顯著低于G1分級(jí)的膀胱腫瘤[24,26,28]。特別是在肌層浸潤(rùn)性膀胱癌當(dāng)中rFOV-DWI表現(xiàn)為更低的ADC值,更為接近真實(shí)彌散狀態(tài)[24,26]。雖然rFOV-DWI診斷肌層浸潤(rùn)特異性提高,但敏感性低于T2序列,(從92%下降到75%),因此更為推薦聯(lián)合使用提高診斷效能[24]。

      2.4 乳腺

      rFOV-DWI應(yīng)用于乳腺掃描時(shí),圖像質(zhì)量顯著提高,分辨率和信噪比增加,偽影和失真顯著下降,脂肪抑制效果更佳,乳腺腫瘤的形態(tài)和病變細(xì)節(jié)顯示更清晰。在乳腺惡性腫瘤中,rFOVDWI和標(biāo)準(zhǔn)雙側(cè)DWI的ADC值都顯著低于其他的病變,特別是在ADC值本身較低的區(qū)域中[29]。甚至有部分研究者認(rèn)為rFOV-DWI得到了更低的ADC值,在基于BI-RADS評(píng)分預(yù)測(cè)乳腺腫瘤的AUC中, rFOV-DWI高于標(biāo)準(zhǔn)雙側(cè)DWI,依次分別為0.71~0.93、0.61~0.76;通過(guò)病變形態(tài)評(píng)估其良惡性時(shí),rFOV-DWI可達(dá)到與動(dòng)態(tài)增強(qiáng)核磁(dynamic contrast enhanced MRI,DCE-MRI)相似的效果(rFOV-DWI AUC:0.74-0.91;標(biāo)準(zhǔn)雙側(cè)DWI AUC:0.67~0.70,DCE AUC:0.76~0.83)[30],且因其無(wú)需注射造影劑并縮短掃描時(shí)間,更利于臨床中用于隨訪那些未進(jìn)行活檢或手術(shù)的乳腺病變(例如DCE-MRI評(píng)估為BI-RADS 3級(jí)的病例[31]),也可以用于評(píng)估新輔助化療后病變的病理組織學(xué)改變[30]和體積改變[32]。此外,Kang等[33]報(bào)道“病變邊緣高信號(hào)”可以作為一種很有價(jià)值的形態(tài)特征評(píng)估良惡性,其提高了DWI序列診斷的特異性,rFOV-DWI則提高了對(duì)這一特征的識(shí)別(特異性80.6%)[30]。

      2.5 頭頸部腫瘤

      頭頸部解剖結(jié)構(gòu)精細(xì)且復(fù)雜,fFOV內(nèi)常同時(shí)存在水,骨骼,空氣等磁化率不同的組織。DWI在腫瘤診斷中扮演著重要的角色,例如在原發(fā)腮腺腫瘤中,DWI比形態(tài)學(xué)MRI和動(dòng)態(tài)增強(qiáng)能更好地診斷其病理類型[34]。rFOV-DWI可以顯著提高圖像質(zhì)量,尤其對(duì)于體積小的病變或位于易受磁化效應(yīng)影像區(qū)域的腫瘤,如好發(fā)鱗狀細(xì)胞癌的舌和上顎[35],rFOV-DWI能夠顯示更多的解剖細(xì)節(jié),更準(zhǔn)確地界定腫瘤病變范圍,診斷的準(zhǔn)確性更高[34-36]。有研究報(bào)道rFOV-DWI測(cè)得的ADC值小于fFOV-DWI,可重復(fù)性更好,其數(shù)值更趨于可靠,這在區(qū)別唾液腺腫瘤和涎腺瘤(ADC值>1.4×10-3mm2/s)[34]、惡性和良性腫瘤(乳頭狀囊腺瘤)[37]、鱗狀細(xì)胞癌(平均ADC值=0.93×10-3mm2/s)和淋巴瘤(平均ADC值=0.64×10-3mm2/s)[38]以及甲狀腺病變[39]中尤為重要,幫助臨床選擇更合適治療手段;此外rFOV-ADC值的標(biāo)準(zhǔn)差減小提供了更可靠的一致性[34]。

      2.6 胰腺

      胰腺屬于位置較深的腹膜后位器官,早期胰腺腫瘤沒有明顯的臨床癥狀,DWI序列可以為常規(guī)MRI序列檢出病灶提供有效的補(bǔ)充。然而常規(guī)DWI序列會(huì)在胰腺鄰近胃腸道(含氣體),腹部器官和主動(dòng)脈運(yùn)動(dòng)的影響下產(chǎn)生磁敏感性偽影、重影、且空間分辨率較低。胰腺rFOV-DWI集中激發(fā)單個(gè)器官,提供了更清晰的解剖結(jié)構(gòu),病灶更為明顯,圖像質(zhì)量更佳,有文獻(xiàn)報(bào)道其空間分辨率大約為fFOV的2倍[40-41],更容易發(fā)現(xiàn)微小病變。雖然兩者的ADC值相似[40-42],但rFOV-DWI所獲得的ADC值可重復(fù)性更好,對(duì)于早期胰腺癌或信號(hào)強(qiáng)度與正常胰腺組織類似的病變來(lái)說(shuō),DWI是一種非常有意義的檢查方法,即使病變清晰度有輕微的提高和ADC值有輕度的變化,rFOV-DWI亦可檢測(cè)出來(lái)。有研究報(bào)道胰腺癌(rFOV ADC 1.061×10-3mm2/s±0.133,fFOV ADC1.079×10-3mm2/s±0.135)和胰腺神經(jīng)內(nèi)分泌腫瘤(rFOV ADC 0.983×10-3mm2/s±0.152,fFOV ADC 1.191×10-3mm2/s±0.153)的ADC值顯著地低于胰腺實(shí)質(zhì)(rFOV ADC 1.191×10-3mm2/s± 0.152,fFOV ADC 1.218×10-3mm2/s±0.103),所以rFOVDWI ADC值擁有更好的區(qū)分病變組織和正常組織的潛力[41]。

      2.7 腎臟

      對(duì)于腎臟疾病來(lái)說(shuō),rFOV-DWI整體圖像質(zhì)量顯著提高,減少圖像的模糊和變形,更清晰地顯示腎臟邊界、皮髓質(zhì)以及小病變,提高診斷的可信度[43]。有研究認(rèn)為ADC值可以用于區(qū)分腎臟嗜酸細(xì)胞瘤和腎細(xì)胞癌,從而避免不必要的腎臟切除術(shù)[44]。雖然對(duì)于腎實(shí)質(zhì)或腎臟病變來(lái)說(shuō),小視野與大視野DWI的ADC值相似,但rFOV- DWI可以在更短的掃描時(shí)間內(nèi)達(dá)到同樣的效果,而且測(cè)量可重復(fù)性更好[44]。

      3 rFOV-DWI技術(shù)存在的問題及展望

      目前,該技術(shù)在其他器官及組織中的相關(guān)研究鮮有報(bào)道,這可能由于其應(yīng)用重點(diǎn)為體積較小、結(jié)構(gòu)較為精細(xì)、解剖部位鄰近磁化率變化較大或易產(chǎn)生不自主生理性運(yùn)動(dòng)的器官及部位周圍,以及需要較高分辨率來(lái)判定病變性質(zhì)和范圍的器官或組織。rFOV-DWI仍然存在一定的問題有待解決,例如因其視野較小,視野外的病變或轉(zhuǎn)移易被忽略;在制訂掃描計(jì)劃時(shí),常無(wú)法直接通過(guò)定位像確定病變的具體位置,需要在常規(guī)相應(yīng)的大視野序列的基礎(chǔ)上進(jìn)行定位,因此臨床中仍需聯(lián)合應(yīng)用其他掃描序列進(jìn)行補(bǔ)充,即大視野用來(lái)覆蓋全部組織,小視野用于集中掃描病變的部位,提高病變局部細(xì)節(jié)和侵襲情況判斷的準(zhǔn)確性;即使在3.0 T場(chǎng)強(qiáng)中,rFOV-DWI的平面空間分辨率及信噪比仍相對(duì)較低,需進(jìn)一步改善。此外,目前各部位有關(guān)于rFOV-DWI的研究病例數(shù)普遍較少,需要更大規(guī)模的臨床實(shí)驗(yàn)證明其應(yīng)用前景;目前的研究主要著重于良惡性腫瘤的對(duì)比,缺乏不同病理類型之間、良性腫瘤之間、非腫瘤性疾病之間及轉(zhuǎn)移淋巴結(jié)相關(guān)的研究,進(jìn)一步明確其應(yīng)用價(jià)值。在ADC值方面,目前由于不同序列之間技術(shù)本身的差別,缺乏統(tǒng)一的評(píng)價(jià)標(biāo)準(zhǔn),只能從理論上預(yù)估其優(yōu)越性,而不能很好地從統(tǒng)計(jì)數(shù)據(jù)中體現(xiàn),因此有待于找到合理的比對(duì)方式,并設(shè)置統(tǒng)一的標(biāo)準(zhǔn)提高其臨床應(yīng)用價(jià)值。

      [References]

      [1] Wu LM, Xu JR, Ye YQ, et al. The clinical value of diffusionweighted imaging in combination with T2-weighted imaging in diagnosing prostate carcinoma: a systematic review and metaanalysis. AJR Am J Roentgenol, 2012, 199(1): 103-110.

      [2] Reeder SB, Mukherjee P. Clinical applications of MR diffusion and perfusion imaging: Preface. Magn Reson Imaging Clin N Am, 2009,17(2): 11-12.

      [3] Chilla GS, Tan CH, Xu C, et al. Diffusion weighted magnetic resonance imaging and its recent trend-a survey. Quant Imaging Med Surg, 2015, 5(3): 407-422.

      [4] Haider MA, van der Kwast TH, Tanguay J, et al. Combined T2-weighted and diffusion-weighted MRI for localization of prostate cancer. AJR Am J Roentgenol, 2007, 189(2): 323-328.

      [5] Rosenkrantz AB, Chandarana H, Pfeuffer J, et al. Zoomed echoplanar imaging using parallel transmission: impact on image quality of diffusion-weighted imaging of the prostate at 3 T. Abdominal Imaging, 2015, 40(1): 120-126.

      [6] Lee VS, Hecht EM, Taouli B, et al. Body and cardiovascular MR imaging at 3.0 T. Radiology, 2007, 244(3): 692-705.

      [7] Akisik FM, Sandrasegaran K, Aisen AM, et al. Abdominal MR imaging at 3.0 T. Radiographics, 2007, 27(5): 1433-1444.

      [8] Morelli J, Porter D, Ai F, et al. Clinical evaluation of single-shot and readout-segmented diffusion-weighted imaging in stroke patients at 3 T. Acta Radiologica, 2013, 54(3): 299-306.

      [9] Mürtz P, Kaschner M, Tr?ber F, et al. Evaluation of dual-source parallel RF excitation for diffusion-weighted whole-body MR imaging with background body signal suppression at 3.0 T. Eur J Radiol, 2012, 81(11): 3614-3623.

      [10] Thierfelder KM, Scherr MK, Notohamiprodjo M, et al. Diffusion-weighted MRI of the prostate: advantages of zoomed EPI with parallel-transmit-accelerated 2D-selective excitation imaging. Eur Radiol, 2014, 24(12): 3233-3241.

      [11] Saritas EU, Cunningham CH, Lee JH, et al. DWI of the spinal cord with reduced FOV single-shot EPI. Magn Reson Med, 2008, 60(2):468-473.

      [12] Dong H, Li Y, Li H, et al. Study of the reduced field-of-view diffusion-weighted imaging of the breast. Clin Breast Cancer, 2014,14(4): 265-271.

      [13] Banerjee S, Nishimura DG, Shankaranarayanan A, et al. Reduced field-of-view DWI with robust fat suppression and unrestricted slice coverage using tilted 2DRF excitation. Magn Reson Med, 2016,76(6): 1668-1676.

      [14] Seeger A, Klose U, Bischof F, et al. Zoomed EPI DWI of acute spinal ischemia using a parallel transmission system. Clin Neuroradiol,2016, 26(2): 177-182.

      [15] Sapkota N, Shi X, Shah LM, et al. Two-dimensional single-shot diffusion-weighted stimulated EPI with reduced FOV for ultrahigh-b radial diffusion-weighted imaging of spinal cord. Magn Reson Med,2016. [Epub ahead of print]

      [16] Wheeler-Kingshott CA, Stroman PW, Schwab JM, et al. The current state-of-the-art of spinal cord imaging: applications. Neuroimage,2014, 84: 1082-1093.

      [17] Stroman PW, Wheeler-Kingshott C, Bacon M, et al. The current state-of-the-art of spinal cord imaging: methods. Neuroimage, 2014,84:1070-1081.

      [18] Zollinger LV, Kim TH, Hill K, et al. Using diffusion tensor imaging and immunofluorescent assay to evaluate the pathology of multiple sclerosis. J Magn Reson Imaging, 2011, 33(3): 557-564.

      [19] Facon D, Ozanne A, Fillard P, et al. MR diffusion tensor imaging and fiber tracking in spinal cord compression. AJNR Am J Neuroradiol,2005, 26(6): 1587-1594.

      [20] Yiannakas MC, Grussu F, Louka P, et al. Reduced field-of-view diffusion-weighted imaging of the lumbosacral enlargement: a pilot in vivo study of the healthy spinal cord at 3 T. PLoS One, 2016,11(10): e164890.

      [21] Attenberger UI, Rathmann N, Sertdemir M, et al. Small field-of-view single-shot EPI-DWI of the prostate: evaluation of spatially-tailored two-dimensional radiofrequency excitation pulses. Z Med Phys,2016, 26(2): 168-176.

      [22] Brendle C, Martirosian P, Schwenzer NF, et al. Diffusion-weighted imaging in the assessment of prostate cancer: comparison of zoomed imaging and conventional technique. Eur J Radiol, 2016, 85(5): 893-900.

      [23] Turkbey B, Merino MJ, Gallardo EC, et al. Comparison of endorectal coil and nonendorectal coil T2W and diffusion-weighted MRI at 3 tesla for localizing prostate cancer: correlation with whole-mount histopathology. J Magn Reson Imag, 2014, 39(6): 1443-1448.

      [24] Wang Y, Li Z, Meng X, et al. Nonmuscle-invasive and muscle-invasive urinary bladder cancer. Medicine (Baltimore), 2016, 95(10): e2951.[25] Matsuki M, Inada Y, Tatsugami F, et al. Diffusion-weighted MR imaging for urinary bladder carcinoma: initial results. Eur Radiol,2007, 17(1): 201-204.

      [26] Avcu S, Koseoglu MN, Ceylan K, et al. The value of diffusionweighted MRI in the diagnosis of malignant and benign urinary bladder lesions. Br J Radiol, 2011, 84(1006): 875-882.

      [27] El-Assmy A, Abou-El-Ghar ME, Refaie HF, et al. Diffusion-weighted MR imaging in diagnosis of superficial and invasive urinary bladder carcinoma: a preliminary prospective study. Scientific World Journal,2008, 8: 364-370.

      [28] Takeuchi M, Sasaki S, Ito M, et al. Urinary bladder cancer: diffusionweighted MR imaging--accuracy for diagnosing T stage and estimating histologic grade. Radiology, 2009, 251(1): 112-121.

      [29] Singer L, Wilmes LJ, Saritas, EU et al. High-resolution diffusionweighted magnetic resonance imaging in patients with locally advanced breast cancer. Acad Radiol, 2012, 19(5): 526-534.

      [30] Barentsz MW, Taviani V, Chang JM, et al. Assessment of tumor morphology on diffusion-weighted (DWI) breast MRI: diagnostic value of reduced field of view DWI. J Magn Reson Imaging, 2015,42(6): 1656-1665.

      [31] Eby PR, DeMartini WB, Gutierrez RL, et al. Characteristics of probably benign breast MRI lesions. AJR Am J Roentgenol, 2009,193(3): 861-867.

      [32] Wilmes LJ, McLaughlin RL, Newitt DC, et al. High-resolution diffusion-weighted imaging for monitoring breast cancer treatment response. Acad Radiol, 2013, 20(5): 581-589.

      [33] Kang BJ, Lipson JA, Planey KR, et al. Rim sign in breast lesions on diffusion-weighted magnetic resonance imaging: diagnostic accuracy and clinical usefulness. J Magn Reson Imaging, 2015, 41(3): 616-623.

      [34] Vidiri A, Minosse S, Piludu F, et al. Feasibility study of reduced field of view diffusion-weighted magnetic resonance imaging in head and neck tumors. Acta Radiologica, Acta Radiol, 2017, 58(3): 292-300.

      [35] Riffel P, Michaely HJ, Morelli JN, et al. Zoomed EPI-DWI of the head and neck with two-dimensional, spatially-selective radiofrequency excitation pulses. Eur Radiol, 2014, 24(10): 2507-2512.[36] von Morze C, Kelley DA, Shepherd TM, et al. Reduced field-ofview diffusion-weighted imaging of the brain at 7 T. Magn Reson Imaging, 2010, 28(10): 1541-1545.

      [37] Yabuuchi H, Matsuo Y, Kamitani T, et al. Parotid Gland Tumors:Can Addition of diffusion-weighted MR imaging to dynamic contrast-enhanced mr imaging improve diagnostic accuracy in characterization? Radiology, 2008, 249(3): 909.

      [38] Zhang Y, Chen J, Shen J, et al. Apparent diffusion coefficient values of necrotic and solid portion of lymph nodes: differential diagnostic value in cervical lymphadenopathy. Clin Radiol, 2013, 68(3): 224-231.

      [39] Lu Y, Hatzoglou V, Banerjee S, et al. Repeatability investigation of reduced field-of-view diffusion-weighted magnetic resonance imaging on thyroid glands. J Comput Assist Tomogr, 2015, 39(3):334-339.

      [40] Ma C, Li Y, Pan C, et al. High resolution diffusion weighted magnetic resonance imaging of the pancreas using reduced field of view single-shot echo-planar imaging at 3 T. Magn Reson Imaging,2014, 32(2): 125-131.

      [41] Kim H, Lee JM, Yoon JH, et al. Reduced field-of-view diffusionweighted magnetic resonance imaging of the pancreas: comparison with conventional single-shot echo-planar imaging. Korean J Radiol,2015, 16(6): 1216-1225.

      [42] Riffel P, Michaely HJ, Morelli JN, et al. Zoomed EPI-DWI of the pancreas using two-dimensional spatially-selective radiofrequency excitation pulses. PLoS One, 2014, 9(3): e89468.

      [43] He Y, Hausmann D, Morelli JN, et al. Renal zoomed EPI-DWI with spatially-selective radiofrequency excitation pulses in two dimensions. Eur J Radiol, 2016, 85(10): 1773-1777.

      [44] Lassel EA, Rao R, Schwenke C, et al. Diffusion-weighted imaging of focal renal lesions: a meta-analysis. Eur Radiol, 2014, 24(1): 241-249.

      Research advances in reduced field of view diffusion weighted imaging

      XU Qiao-yu, SUN Hong-liang, XU Yan-yan, WANG Wu*
      Department of Radiology, China-Japan Friendship Hospital, Beijing 100029, China

      Diffusion-weighted imaging (DWI), as a kind of functional imaging technique, is an important complement to the conventional MRI in imaging diagnosis.However, the most common technique is full field of view diffusion weighted imaging(fFOV-DWI), which has some defects that cannot be ignored, such as poor image quality, low resolution of anatomical structure and serious artifact. With development of technology, reduced field of view diffusion weighted imaging (rFOV DWI) avoids the need to encode a large extent in the phase-encode direction, shortens the echo train and reduces off-resonance-induced artifacts in single-shot echo-planar imaging(ssEPI), resulting in significantly improved image quality. This review focuses on the theory and clinical research advances of rFOV DWI in the various organs for imaging diagnosis.

      Diffusion magnetic resonance imaging; Visual fields; Diagnosis,differential

      國(guó)家自然科學(xué)基金項(xiàng)目(編號(hào):81501469);國(guó)家衛(wèi)生和計(jì)劃生育委員會(huì)公益性行業(yè)科研專項(xiàng)(編號(hào):201402019)

      中日友好醫(yī)院放射科,北京 100029

      王武,E-mail:cjr.wangwu@vip.163.com

      2017-02-14

      接受日期:2017-04-08

      R445.2

      A

      10.12015/issn.1674-8034.2017.07.016

      徐俏宇, 孫宏亮, 徐妍妍, 等. 磁共振小視野彌散加權(quán)成像技術(shù)在影像診斷中的研究進(jìn)展. 磁共振成像, 2017, 8(7):556-560.*Correspondence to: Wang W, E-mail: cjr.wangwu@vip.163.com

      Received 14 Feb 2017, Accepted 8 Apr 2017

      ACKNOWLEDGMENTSThe National Natural Science Fund (No. 81501469).Health and family planning commission public welfare industry research (No.201402019).

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