磁共振氨基質(zhì)子轉(zhuǎn)移成像的臨床應(yīng)用

白巖，馬瀟越，史大鵬，劉太元，王梅云

磁共振氨基質(zhì)子轉(zhuǎn)移成像的臨床應(yīng)用

白巖，馬瀟越，史大鵬，劉太元，王梅云*

磁共振氨基質(zhì)子轉(zhuǎn)移(amide proton transfer, APT)成像是一種基于化學(xué)交換飽和轉(zhuǎn)移技術(shù)且可反映生物組織中內(nèi)源性游離蛋白和肽類(lèi)含量以及氨基質(zhì)子交換速率的無(wú)創(chuàng)性分子磁共振成像方法。APT加權(quán)圖像是通過(guò)對(duì)Z譜中水頻率兩側(cè)±3.5 ppm處的非對(duì)稱(chēng)性磁化轉(zhuǎn)移率進(jìn)行計(jì)算得到的。近年來(lái)，APT磁共振成像(magnetic resonance imaging, MRI)已被越來(lái)越多地應(yīng)用于疾病診斷中。本文針對(duì)目前APT MRI在臨床應(yīng)用和科學(xué)研究方面的進(jìn)展予以綜述。

氨基質(zhì)子轉(zhuǎn)移；磁共振成像；化學(xué)交換飽和轉(zhuǎn)移

Received 20 Feb 2016, Accepted 29 Mar 2016

ACKNOWLEDGMENTSThis work was part of National Natural Science Foundation of China (No. 81271565, 31470047).

磁共振氨基質(zhì)子轉(zhuǎn)移(am ide proton transfer, APT)成像是一種基于化學(xué)交換飽和轉(zhuǎn)移技術(shù)的無(wú)創(chuàng)性磁共振成像方法[1]。由APT磁共振成像(magnetic resonance imaging, MRI)生成的參數(shù)APT加權(quán)(APT weighted, APTw)信號(hào)強(qiáng)度能夠反映生物組織中內(nèi)源性游離蛋白和肽類(lèi)的含量以及氨基質(zhì)子的交換速率[2]。目前，APT MRI已被成功應(yīng)用于人體多個(gè)系統(tǒng)的疾病診斷和科學(xué)研究中，在臨床上具有廣闊的應(yīng)用前景。

1 APT MRI原理概述

APT MRI是由Zhou等[1]提出的一種無(wú)需使用外源性磁共振對(duì)比劑即可在活體組織內(nèi)檢測(cè)游離蛋白和肽類(lèi)含量的磁共振成像技術(shù)。人體組織內(nèi)游離蛋白和多肽主鏈上的酰胺鍵與水的氫質(zhì)子之間存在化學(xué)交換，通過(guò)施加特定頻率的射頻脈沖可對(duì)氨基質(zhì)子進(jìn)行飽和標(biāo)記，被飽和的氨基質(zhì)子通過(guò)與未被飽和的水的氫質(zhì)子進(jìn)行交換，使部分水的氫質(zhì)子被飽和，經(jīng)過(guò)多次反復(fù)的化學(xué)交換后可導(dǎo)致水的信號(hào)降低，從而通過(guò)水的信號(hào)降低程度間接得到氨基質(zhì)子的濃度或交換速率(圖1)。APT MRI一般利用水信號(hào)隨飽和脈沖頻率的變化而得出Z譜，然后使用不同的方法對(duì)APTw信號(hào)進(jìn)行測(cè)量。最常用的測(cè)量方法為對(duì)Z譜 ±3.5 ppm處的磁化轉(zhuǎn)移進(jìn)行非對(duì)稱(chēng)性分析獲得氨基質(zhì)子的化學(xué)交換信息，即通過(guò)水共振頻率兩側(cè)+3.5 ppm和-3.5 ppm處的磁化轉(zhuǎn)移率之差得到APTw信號(hào)強(qiáng)度，從而生成APTw圖，具體計(jì)算公式如下：M TRasym(3.5 ppm)=MTR(+3.5 ppm)-MTR(-3.5 ppm)=Ssat(-3.5 ppm)/S0-Ssat(+3.5 ppm)/S0，MTRasym為非對(duì)稱(chēng)性磁化轉(zhuǎn)移率，MTR為磁化轉(zhuǎn)移率，Ssat為施加飽和脈沖后的信號(hào)強(qiáng)度，S0為未施加飽和脈沖的信號(hào)強(qiáng)度[2]。APTw信號(hào)強(qiáng)度與內(nèi)源性游離蛋白和肽類(lèi)的含量以及氨基質(zhì)子的交換速率有關(guān)。APTw信號(hào)強(qiáng)度隨著內(nèi)源性游離蛋白和肽類(lèi)含量的增加而升高。pH值的下降可使氨基質(zhì)子的交換速率減低，從而導(dǎo)致APTw信號(hào)強(qiáng)度降低[1]。此外，實(shí)際測(cè)量到的APTw信號(hào)強(qiáng)度還受到來(lái)自非直接化學(xué)交換的核奧氏效應(yīng)(nuclear overhauser effect, NOE)的影響[3]。NOE通常存在于Z譜的-2.0 ppm與-4.0 ppm之間從而影響MTRasym(3.5 ppm)的定量測(cè)量[4]。在活體APT MRI中，NOE可能來(lái)自組織中水的氫質(zhì)子與游離蛋白及多肽、代謝分子和脂質(zhì)之間的相互作用，包括分子間的空間偶極耦合等[3]。

圖1 APT MRI原理示意圖。內(nèi)源性游離蛋白的氨基質(zhì)子和水的氫質(zhì)子和之間存在著化學(xué)交換，通過(guò)施加射頻脈沖對(duì)內(nèi)源性游離蛋白的氨基質(zhì)子進(jìn)行飽和，氨基質(zhì)子的飽和可以轉(zhuǎn)移到水的氫質(zhì)子中，從而使水的信號(hào)下降。(Bai Y, et al. MAGNETOM Flash, 2014)Fig. 1 A schematic diagram of APT MRI. There are chem ical exchanges between am ide protons of endogenous mobile proteins and water p rotons. Am ide protons of endogenous mobile proteins are saturated via radio frequency irradiation. This saturation is transferred to water protons and decreases the water signals. (Bai Y, et al. MAGNETOM Flash, 2014)

2 APT MRI在中樞神經(jīng)系統(tǒng)中的應(yīng)用

2.1 APT MRI在腦腫瘤中的應(yīng)用

膠質(zhì)瘤是成人最常見(jiàn)的原發(fā)性腦腫瘤，它的準(zhǔn)確分級(jí)對(duì)于臨床治療決策的選擇和預(yù)后的判斷至關(guān)重要[5]。包括筆者前期研究在內(nèi)的多項(xiàng)研究結(jié)果表明APT MRI能夠?qū)δz質(zhì)瘤進(jìn)行準(zhǔn)確分級(jí)[2, 6-8]。與低級(jí)別膠質(zhì)瘤相比，高級(jí)別膠質(zhì)瘤的惡性程度增高且腫瘤的細(xì)胞密度和細(xì)胞內(nèi)游離蛋白和肽類(lèi)的含量增高，導(dǎo)致APTw信號(hào)強(qiáng)度顯著升高[6](圖2、3)。需要注射外源性磁共振對(duì)比劑的常規(guī)磁共振成像有時(shí)不能對(duì)膠質(zhì)瘤進(jìn)行準(zhǔn)確分級(jí)，這是由于一些高、低級(jí)別膠質(zhì)瘤有著相似的影像表現(xiàn)，例如高級(jí)別膠質(zhì)瘤通常有強(qiáng)化表現(xiàn)，但一些低級(jí)別膠質(zhì)瘤也會(huì)出現(xiàn)強(qiáng)化現(xiàn)象。Park等[9]發(fā)現(xiàn)APT MRI可有效鑒別有強(qiáng)化表現(xiàn)的低級(jí)別膠質(zhì)瘤與高級(jí)別膠質(zhì)瘤，強(qiáng)化的低級(jí)別膠質(zhì)瘤的APTw信號(hào)強(qiáng)度顯著低于高級(jí)別膠質(zhì)瘤的。此外，APT MRI有助于膠質(zhì)瘤的療效評(píng)估[7]以及高級(jí)別膠質(zhì)瘤經(jīng)過(guò)放療后的放射性壞死與假性進(jìn)展之間的鑒別診斷[10-11]。

圖2 女性，51歲，左側(cè)額葉星形細(xì)胞瘤(WHO II級(jí))。腫瘤在T1加權(quán)圖像(A)上呈等信號(hào)，在T2加權(quán)圖像(B)上呈高信號(hào)，在磁共振對(duì)比劑增強(qiáng)后的T1加權(quán)圖像(C)上未見(jiàn)強(qiáng)化。APT加權(quán)圖像(D)顯示腫瘤的信號(hào)強(qiáng)度未見(jiàn)增高(Wang MY, et al. ISMRM 2014) 圖3 男性，59歲，左側(cè)額葉膠質(zhì)母細(xì)胞瘤(WHO IV級(jí))。腫瘤實(shí)性部分在T1加權(quán)圖像(A)上呈等或稍低信號(hào)，在T2加權(quán)圖像(B)上呈稍高信號(hào)，在磁共振對(duì)比劑增強(qiáng)后的T1加權(quán)圖像(C)上呈不規(guī)則強(qiáng)化。APT加權(quán)圖像(D)顯示腫瘤的信號(hào)強(qiáng)度明顯增高(Wang MY, et al. ISMRM 2014)Fig. 2 A 51-year-old female patient w ith astrocytoma (WHO grade II) in the left frontal lobe. The tumor shows isointensity on T1-weighted image (A) and hyperintensity on T2-weighted image (B). No enhancement is revealed on post-gadolinium T1-weighted image (C). APT-weighted map (D) demonstrates not increased signal intensity in the tumor. (Wang MY, et al. ISMRM 2014). Fig. 3 A 59-year-old man w ith glioblastoma (WHO IV grade) in the left frontal lobe. The solid component of the tumor shows isointensity or m ild hypointensity on T1-w eightw ed image (A) and m ild hyperintensity on T2-weightwed image (B). Irregular enhancement is revealed on post-gadolinium image (C). APT-weighted map (D) show s increased signal intensity in the tumor. (W ang MY, et al. ISMRM 2014).

APT MRI不僅在膠質(zhì)瘤的分級(jí)和診斷中具有重要的臨床應(yīng)用價(jià)值，它還能夠有效鑒別高級(jí)別膠質(zhì)瘤與原發(fā)性中樞神經(jīng)系統(tǒng)淋巴瘤或腦轉(zhuǎn)移瘤[12-13]。原發(fā)性中樞神經(jīng)系統(tǒng)淋巴瘤的最大與最小APTw信號(hào)強(qiáng)度的差值顯著低于高級(jí)別膠質(zhì)瘤的，這可能是由于原發(fā)性中樞神經(jīng)系統(tǒng)淋巴瘤的組織均一性明顯高于高級(jí)別膠質(zhì)瘤[12]。APTw信號(hào)強(qiáng)度在腦轉(zhuǎn)移瘤和高級(jí)別膠質(zhì)瘤之間沒(méi)有顯著的統(tǒng)計(jì)學(xué)差異，這可能是由于兩者均為含有較多游離蛋白的惡性腫瘤所導(dǎo)致的。但是，腦轉(zhuǎn)移瘤的瘤周區(qū)APTw信號(hào)強(qiáng)度顯著低于高級(jí)別膠質(zhì)瘤的瘤周區(qū)信號(hào)強(qiáng)度，這可能是由高級(jí)別膠質(zhì)瘤的腫瘤細(xì)胞對(duì)瘤周區(qū)的浸潤(rùn)造成的[13]。

2.2 APT MRI在腦血管疾病中的應(yīng)用

前期的一些研究表明，APTw信號(hào)強(qiáng)度在超急性期缺血性腦卒中的病灶中顯著低于在對(duì)側(cè)正常腦組織中，這可能是由于病灶中的酸中毒導(dǎo)致pH值減低，使氨基質(zhì)子交換速率減慢，從而造成APTw信號(hào)強(qiáng)度減低[14-15]。此外，Tietze等[15]通過(guò)隨訪(fǎng)發(fā)現(xiàn)在一些超急性期缺血性腦卒中病例中，APTw信號(hào)強(qiáng)度減低區(qū)與最終的梗死區(qū)具有關(guān)聯(lián)性。Harston等[16]在對(duì)超急性和急性期缺血性腦卒中病人的研究中進(jìn)一步發(fā)現(xiàn)APTw信號(hào)強(qiáng)度的減低程度在水腫區(qū)、梗死進(jìn)展區(qū)和缺血核心區(qū)依次加重。此外，通過(guò)將APT MRI與磁共振擴(kuò)散加權(quán)成像和動(dòng)脈自旋標(biāo)記灌注成像進(jìn)行對(duì)比發(fā)現(xiàn)APT MRI可能對(duì)缺血半暗帶的識(shí)別更有價(jià)值。該研究結(jié)果支持APTw圖像可將擴(kuò)散-灌注不匹配區(qū)域分為酸中毒性缺血半暗帶和良性水腫區(qū)這一觀點(diǎn)[17]。因此，在反映缺血性腦卒中病灶的代謝變化方面，APT MRI可以提供磁共振擴(kuò)散加權(quán)成像和灌注成像所不能夠顯示的信息[15]。

APT MRI不僅限于對(duì)缺血性腦卒中的研究，筆者首次將APT MRI用于鑒別超急性期的出血性與缺血性腦卒中[18]。該研究利用大鼠模型發(fā)現(xiàn)APT MRI可早期檢測(cè)和區(qū)分超急性的出血性與缺血性腦卒中。腦血腫內(nèi)豐富的蛋白成分導(dǎo)致APTw信號(hào)強(qiáng)度增高且易于同APTw信號(hào)強(qiáng)度下降的缺血性腦卒中病灶相鑒別(圖4)，有望為早期檢測(cè)和區(qū)分腦出血和腦缺血提供新的無(wú)創(chuàng)性MRI技術(shù)。

此外，APT MRI還被應(yīng)用于腦血管畸形類(lèi)疾病中。Gerigk等[19]對(duì)一例經(jīng)立體定向放射治療后的腦動(dòng)靜脈畸形病例進(jìn)行了報(bào)道，對(duì)該病例在7 T磁共振成像儀上行APT MRI后發(fā)現(xiàn)放射性壞死區(qū)的APTw信號(hào)強(qiáng)度明顯減低且與周?chē)X組織分界清楚。

圖4 在超急性期腦出血的大鼠模型中，血腫在T2權(quán)圖像(A)上呈等或低信號(hào)，在T2*加權(quán)圖像(B)上呈低或等信號(hào)。APT加權(quán)圖像(C)顯示血腫的信號(hào)強(qiáng)度增高（箭頭）。在超急性期腦缺血的大鼠模型中，缺血病灶在T2加權(quán)圖像(D)上呈等或稍高信號(hào)，在T2*加權(quán)圖像(E)上呈等信號(hào)。APT加權(quán)圖像(F)顯示缺血病灶的信號(hào)強(qiáng)度減低(箭頭) (Wang MY. et al. Magnetic Resonance in Medicine, 2015)Fig. 4 In the rat model of intracerebral hemorrhage at hyperacute stage,the hematoma show s isointensity or hypointesity on T2-weighted image (A) and hypointesity or isointensity on T2*-weighted image (B). APT-weighted map (C) demonstrates hyperintesity in the hematoma (arrow). In the rat model of cerebral ischem ia at hyperacute stage,the ischem ic lesion show s isointensity or m ild hyperintensity on T2weighted image (D) and isointensity on T2*-weighted image (E). APT-weighted map (F) demonstrates hypointesity in the ischem ic lesion (arrow). (W ang MY. et al. M agnetic Resonance in Medicine, 2015)

2.3 APT MRI在功能性腦疾病中的應(yīng)用

APT MRI還被應(yīng)用于一些功能性腦疾病中，如阿爾茨海默病和帕金森病等。Wang等[20]發(fā)現(xiàn)雙側(cè)海馬的APTw信號(hào)強(qiáng)度在阿爾茨海默病患者中顯著高于其在正常人中，而且阿爾茨海默病患者雙側(cè)海馬的APTw信號(hào)強(qiáng)度與簡(jiǎn)易精神狀態(tài)量表評(píng)分呈顯著負(fù)相關(guān)。阿爾茨海默病患者腦內(nèi)存在一些異常沉積的蛋白，如α-突觸核蛋白、Tau蛋白、Ab寡聚體和TDP-43蛋白等。異常沉積的蛋白可能導(dǎo)致阿爾茨海默病患者雙側(cè)海馬的APTw信號(hào)強(qiáng)度增加以及認(rèn)知功能受損。因此，APT MRI不僅能夠作為一種無(wú)創(chuàng)性磁共振成像技術(shù)顯示阿爾茨海默病患者腦內(nèi)的游離蛋白含量，還可通過(guò)APTw信號(hào)強(qiáng)度增加的程度來(lái)反映認(rèn)知功能的受損情況。

帕金森病是一種以黑質(zhì)和紋狀體細(xì)胞減少為特征的神經(jīng)退行性疾病。Li等[21]發(fā)現(xiàn)在對(duì)帕金森病的診斷和嚴(yán)重程度的評(píng)估中，APT MRI優(yōu)于磁共振擴(kuò)散張量成像。該研究結(jié)果顯示帕金森病患者的APTw信號(hào)強(qiáng)度在殼核和尾狀核中均顯著高于正常人，這可能是由患者腦內(nèi)游離蛋白如α-突觸核蛋白含量的異常增加所致。另外，早期帕金森病患者的APTw信號(hào)強(qiáng)度在殼核和尾狀核中均顯著高于進(jìn)展期帕金森病患者的，這可能是由于該病在進(jìn)展過(guò)程中造成的神經(jīng)元減少或者病人所經(jīng)受的治療造成的。在帕金森病患者和正常人之間，包括平均擴(kuò)散系數(shù)和部分各向異性值在內(nèi)的磁共振擴(kuò)散張量成像參數(shù)在殼核中均無(wú)顯著統(tǒng)計(jì)學(xué)差異。此外，黑質(zhì)的平均擴(kuò)散系數(shù)在帕金森病患者和正常人之間也無(wú)顯著統(tǒng)計(jì)學(xué)差異。在早期和進(jìn)展期帕金森病患者之間，殼核和尾狀核的平均擴(kuò)散系數(shù)和部分各向異性值均無(wú)顯著統(tǒng)計(jì)學(xué)差異。因此，APT MRI不僅可以有效地檢測(cè)出帕金森病患者和正常人之間存在游離蛋白含量差異的腦區(qū)，還能夠?qū)ε两鹕〉膰?yán)重程度進(jìn)行評(píng)估。

2.4 APT MRI在正常兒童腦發(fā)育過(guò)程中的應(yīng)用

Zhang等[22]利用APT MRI對(duì)正常兒童的腦發(fā)育過(guò)程進(jìn)行觀察。該研究發(fā)現(xiàn)兒童腦白質(zhì)的APTw信號(hào)強(qiáng)度在腦發(fā)育過(guò)程中逐漸減低且在發(fā)育過(guò)程中的第一年減低程度最為明顯。游離蛋白含量在髓鞘形成過(guò)程中的減少可能造成了APTw信號(hào)強(qiáng)度的減低。APT MRI可被用來(lái)監(jiān)測(cè)兒童的髓鞘形成過(guò)程，可能會(huì)對(duì)兒童的髓鞘形成異常及療效評(píng)估有幫助。

3 APT MRI在頭頸部腫瘤中的應(yīng)用

Yuan等[23]采用APT MRI對(duì)4例具有不同病理類(lèi)型頭頸部腫瘤的病人進(jìn)行了研究。結(jié)果表明腮腺多形性腺瘤、神經(jīng)鞘瘤、鼻咽癌和轉(zhuǎn)移淋巴結(jié)這4種頭頸部腫瘤的APTw信號(hào)強(qiáng)度和分布各不相同，可能是由于這些腫瘤在生物學(xué)特性方面的差異造成的。因此，APT MRI有潛力成為一種可顯示不同類(lèi)型頭頸部腫瘤之間特征性差異的磁共振技術(shù)而應(yīng)用于臨床。

4 APT MRI在乳腺中的應(yīng)用

Dula等[24]在3 T磁共振成像儀上采用APT MRI對(duì)3例女性乳腺癌病人分別在經(jīng)過(guò)一個(gè)周期新輔助化療前后的腫瘤APTw信號(hào)強(qiáng)度變化進(jìn)行檢測(cè)。研究結(jié)果顯示治療后有進(jìn)展腫瘤的APTw信號(hào)強(qiáng)度較治療前增加，這可能是由于腫瘤的增殖能力進(jìn)一步增強(qiáng)導(dǎo)致腫瘤組織內(nèi)游離蛋白含量增多。而治療后部分緩解和完全緩解的腫瘤APTw信號(hào)強(qiáng)度均低于治療前的。因此，APT MRI可能有助于乳腺癌病人的療效評(píng)估。此外，有研究發(fā)現(xiàn)APT MRI在7 T磁共振成像儀上能夠很清楚地顯示正常人的纖維腺體乳腺組織[25]。

5 APT MRI在胸部惡性腫瘤和良性病變中的應(yīng)用

Ohno等[26]將APT MRI應(yīng)用于肺癌、縱膈淋巴瘤、胸腺癌、遷延性肺炎和縱膈囊性良性腫瘤等胸部病變的研究中。該研究結(jié)果表明，APTw信號(hào)強(qiáng)度在胸部惡性腫瘤中顯著高于其在胸部良性病變中。另外，肺癌的APTw信號(hào)強(qiáng)度顯著低于其他胸部惡性腫瘤的，肺腺癌的APTw信號(hào)強(qiáng)度顯著低于肺鱗癌的。因此，APT MRI在胸部良、惡性腫瘤的鑒別、肺癌與其他胸部惡性腫瘤的鑒別以及肺腺癌與肺鱗癌的鑒別中均具有潛在的臨床應(yīng)用價(jià)值[26]。

6 APT MRI在前列腺癌中的應(yīng)用

前列腺癌是一種常見(jiàn)的男性泌尿系統(tǒng)惡性腫瘤，可嚴(yán)重影響病人生活質(zhì)量甚至導(dǎo)致死亡。但常規(guī)磁共振成像對(duì)前列腺癌的敏感性和特異性均不高[27]。Jia等[28]發(fā)現(xiàn)前列腺癌組織的APTw信號(hào)強(qiáng)度顯著高于良性前列腺組織的，這可能是由于前列腺癌組織的細(xì)胞密度和細(xì)胞增殖能力增高導(dǎo)致內(nèi)源性游離蛋白含量增加。

7 APT MRI在一些動(dòng)物模型中的研究進(jìn)展

Sagiyama等[29]通過(guò)將腦內(nèi)被種植膠質(zhì)瘤的小鼠在經(jīng)過(guò)一個(gè)療程的替莫唑胺化療后行APT MRI復(fù)查，發(fā)現(xiàn)腫瘤的APTw信號(hào)減低，由此推測(cè)造成腫瘤在治療后APTw信號(hào)減低的原因一方面是由于經(jīng)過(guò)治療的腫瘤組織中游離蛋白和肽類(lèi)的含量減低，另一方面由于替莫唑胺化療損害了腫瘤細(xì)胞的pH調(diào)節(jié)功能，造成膠質(zhì)瘤細(xì)胞內(nèi)的酸性程度增加從而導(dǎo)致APTw信號(hào)減低。Togao等[30]通過(guò)對(duì)肺癌動(dòng)物模型進(jìn)行研究發(fā)現(xiàn)，APTw信號(hào)強(qiáng)度在A549和Lew is這兩種不同類(lèi)型的肺癌組織間存在差異。因此，APT MRI將來(lái)可能成為一種能夠?qū)Ψ伟┻M(jìn)行分型及分級(jí)的無(wú)創(chuàng)性磁共振成像方法。另外，F(xiàn)ranconi等[31]利用動(dòng)物模型研究APT MRI對(duì)腹壁疝修補(bǔ)術(shù)后體內(nèi)復(fù)合網(wǎng)狀補(bǔ)片的顯示能力。該研究結(jié)果表明在術(shù)后的前三周內(nèi)，復(fù)合網(wǎng)狀補(bǔ)片在APTw圖像上可被清楚顯示，這是由于復(fù)合網(wǎng)狀補(bǔ)片的膠原蛋白覆膜的APTw信號(hào)強(qiáng)度明顯高于周?chē)∪獾?。APT MRI有望作為一種能夠在腹壁疝修補(bǔ)術(shù)后早期對(duì)體內(nèi)復(fù)合網(wǎng)狀補(bǔ)片位置進(jìn)行檢測(cè)的無(wú)創(chuàng)性磁共振成像技術(shù)應(yīng)用于臨床。

如今，APT MRI技術(shù)已由最初的二維單層成像發(fā)展為三維全腦成像[2, 32]，信噪比在不斷提升而掃描時(shí)間在不斷減少。此外，近年來(lái)出現(xiàn)的同樣基于化學(xué)交換飽和轉(zhuǎn)移技術(shù)的飽和脈沖參數(shù)調(diào)制

(length and offset varied saturation, LOVARS) MRI可顯著提高圖像的對(duì)比噪聲比[33]，W ang[34-35]等在國(guó)際上率先將該技術(shù)應(yīng)用于臨床研究，發(fā)現(xiàn)其在腦膠質(zhì)瘤和腦卒中疾病的精準(zhǔn)診斷中很有潛力。相信隨著APT MRI技術(shù)的不斷改善和發(fā)展，未來(lái)將會(huì)在臨床診療中發(fā)揮重要的作用。

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Clinical app lications of am ide p roton transfer magnetic resonance imaging

BA I Yan, MA X iao-yue, SHI Da-peng, LIU Tai-yuan, W ang M ei-yun*
Department of Radiology, The Peop le’s Hospital of Zhengzhou University & Henan Provincial People’s Hospital, Zhengzhou 450003, China

Am ide proton transfer (APT) imaging is a noninvasive molecular magnetic resonance imaging (MRI) method based on chem ical exchange dependent saturation transfer technique that detects endogenous mobile proteins and peptides, and am ide proton exchange rates in biological tissues. APT weighted image is calculated by the magnetization transfer asymmetry between ±3.5 ppm which respect to the w ater frequency on z-spectrum. In recent years, APT MRI has been increasingly used for the diagnosis of diseases. In this article, w e review ed the developments of APT MRI in the clinical app lications and scientific researches.

Am ide pro ton transfer; M agnetic resonance imaging; Chem ical exchange dependent saturation transfer

國(guó)家自然科學(xué)基金項(xiàng)目(編號(hào)：81271 565，31470047)

鄭州大學(xué)人民醫(yī)院/河南省人民醫(yī)院影像科，鄭州 450003

ail: marian9999@163.com

2016-02-20

接受日期：2016-03-29

R445.2

A

10.12015/issn.1674-8034.2016.04.004

白巖, 馬瀟越, 史大鵬, 等. 磁共振氨基質(zhì)子轉(zhuǎn)移成像的臨床應(yīng)用. 磁共振成像, 2016, 7(4): 259–264.

*Correspondence to: Wang MY, E-mail: marian9999@163.com