張偉，王娟，李婷

?

雙干型大腦中動(dòng)脈分叉部幾何形態(tài)與動(dòng)脈瘤形成的CT血管成像研究

張偉1*，王娟1，李婷2

1.湖南省腦科醫(yī)院放射科，湖南長(zhǎng)沙 410011； 2.湖南省湘雅三醫(yī)院放射科，湖南長(zhǎng)沙 410013；

探討雙干型大腦中動(dòng)脈（MCA）分叉部動(dòng)脈瘤形成與分叉部幾何形態(tài)參數(shù)之間的關(guān)系，為篩選動(dòng)脈瘤高危人群、降低動(dòng)脈瘤破裂的病死率及致殘率提供參考?；仡櫺苑治?014年1月－2017年3月湖南省腦科醫(yī)院收治的30例MCA分叉部動(dòng)脈瘤患者（動(dòng)脈瘤組）與50例行頭部CT血管成像（CTA）檢查無(wú)動(dòng)脈瘤患者（對(duì)照組），分別測(cè)量?jī)山M患者M(jìn)CA兩分支夾角，即分支分別與主干形成的夾角（較粗分支與主干夾角記為γ1、較細(xì)分支與主干夾角記為γ2），分叉角（γ3），分叉部血管管徑和分支管徑；計(jì)算兩分支夾角比（較大分支夾角/較小分支夾角）及分支管徑比（較粗分支/較細(xì)分支）。比較對(duì)照組和動(dòng)脈瘤組各項(xiàng)參數(shù)間的差異。動(dòng)脈瘤組γ1、γ2、分叉部血管管徑均小于對(duì)照組，γ3大于對(duì)照組，差異均有統(tǒng)計(jì)學(xué)意義（<0.05）；管徑比、兩分支夾角比差異無(wú)統(tǒng)計(jì)學(xué)意義（>0.05）。雙干型MCA分叉部動(dòng)脈瘤形成與MCA分叉部幾何形態(tài)參數(shù)具有一定關(guān)聯(lián)。通過(guò)CTA獲得MCA分叉部幾何形態(tài)參數(shù)的方法對(duì)動(dòng)脈瘤高危人群篩選具有一定的價(jià)值。

顱內(nèi)動(dòng)脈瘤；大腦中動(dòng)脈；體層攝影術(shù)，X線計(jì)算機(jī)；腦血管造影術(shù)；圖像處理，計(jì)算機(jī)輔助

顱內(nèi)動(dòng)脈瘤指動(dòng)脈血管壁局部異常膨出。動(dòng)脈瘤破裂常表現(xiàn)為蛛網(wǎng)膜下腔出血或腦血腫，可導(dǎo)致約50%的患者死亡，0.5%~7.9%的動(dòng)脈瘤破裂患者并發(fā)硬膜下血腫[1]。大腦中動(dòng)脈（middle cerebral artery，MCA）瘤占顱內(nèi)動(dòng)脈瘤的20%，破裂率約為50%，而80%~85%為分叉部動(dòng)脈瘤[2-3]。因此，降低分叉部動(dòng)脈瘤的破裂率至關(guān)重要，其關(guān)鍵在于有效篩選高危人群，做到定期復(fù)查、及時(shí)診斷和治療。國(guó)內(nèi)對(duì)于MCA瘤的研究大多集中于大腦中動(dòng)脈分叉角大小與動(dòng)脈瘤形成的關(guān)系，且缺乏分叉角具體數(shù)據(jù)；同時(shí)對(duì)MCA分支與主干夾角及分叉部血管管徑與動(dòng)脈瘤形成的相關(guān)性研究鮮有報(bào)道。本研究擬進(jìn)一步分析雙干型MCA分叉部幾何形態(tài)與動(dòng)脈瘤發(fā)生的相關(guān)性，為高?；颊邉?dòng)脈瘤篩查提供參考。

1 資料與方法

1.1 研究對(duì)象 回顧性分析2014年1月－2017年3月湖南省腦科醫(yī)院分叉部動(dòng)脈瘤患者30例，納入標(biāo)準(zhǔn)：①經(jīng)數(shù)字減影血管造影診斷為雙干型MCA分叉部動(dòng)脈瘤；②CTA圖像清晰，便于測(cè)量。30例患者中，男9例，女21例，平均年齡（58.6±9.6）歲。27例患者因突發(fā)頭痛、言語(yǔ)障礙或活動(dòng)障礙就診，其中10例CT表現(xiàn)為急性蛛網(wǎng)膜下腔出血，14例腦內(nèi)血腫及急性蛛網(wǎng)膜下腔出血，3例腦內(nèi)血腫；3例患者因高度懷疑腦梗死、面肌痙攣等就診，頭部CT檢查未發(fā)現(xiàn)異常。動(dòng)脈瘤組中4例為多發(fā)動(dòng)脈瘤，其中1例為雙側(cè)M1段動(dòng)脈瘤，2例合并M2段動(dòng)脈瘤，1例合并M3段動(dòng)脈瘤。同時(shí)收集2014年1月－2017年3月于湖南省腦科醫(yī)院行頭部CT血管成像（CTA）檢查的無(wú)動(dòng)脈瘤患者50例，其中男33例，女17例，平均年齡（56.4±13.5）歲。納入標(biāo)準(zhǔn)：①由2位副主任醫(yī)師審閱頭部CTA圖像，診斷為雙干型大腦中動(dòng)脈，無(wú)動(dòng)脈瘤，無(wú)瘤樣擴(kuò)張；②CTA圖像清晰，無(wú)偽影。

1.2 儀器與方法 采用Philips Ingenuity Core 128層CT或GE BrightSpeed 16排CT檢查。Philips Ingenuity Core 128層CTA掃描參數(shù)：管電壓120 kVp，管電流240 mAs，視野226×240；GE BrightSpeed 16排CTA掃描參數(shù)：管電壓120 kVp，管電流300 mAs，視野486×250。預(yù)掃后連接高壓注射器，注入15 ml生理鹽水后注入造影劑。造影劑采用碘普羅胺（370 mg/ml），流速為5.0~5.5 ml/s，總劑量65 ml。

1.3 三維圖像采集及參數(shù)測(cè)量 將掃描后的數(shù)據(jù)傳至Philips三維工作站行血管重建得到血管容積再現(xiàn)（VR）及最大密度投影（MIP）圖像，變換角度以選取最佳測(cè)量平面。分別測(cè)量較粗分支與主干夾角（γ1）、較細(xì)分支與主干夾角（γ2）、分叉角（γ3）、分叉部血管管徑、分支管徑（圖1、2）。為獲得相對(duì)準(zhǔn)確的數(shù)據(jù)，由2名醫(yī)師測(cè)量，每項(xiàng)數(shù)據(jù)均測(cè)量2次，取其平均值。根據(jù)最后測(cè)量數(shù)據(jù)計(jì)算出兩分支夾角比及分支管徑比。

圖1 男，59歲，對(duì)照組受試者頭部CTA未見(jiàn)異常。A~C分別為分叉角、分叉部血管管徑、分支分別與主干形成的夾角VR及MIP圖像

圖2 男，53歲，動(dòng)脈瘤組患者大腦中動(dòng)脈分叉部動(dòng)脈瘤。A~C分別為分叉角、分叉部血管管徑、分支分別與主干形成的夾角VR及MIP圖像，箭示動(dòng)脈瘤

2 結(jié)果

動(dòng)脈瘤組γ1、γ2、分叉部血管管徑均小于對(duì)照組，γ3大于對(duì)照組，差異均有統(tǒng)計(jì)學(xué)意義（<0.05）。兩組分支管徑比與兩分支夾角比比較，差異無(wú)統(tǒng)計(jì)學(xué)意義（>0.05），見(jiàn)表1。ROC曲線分析結(jié)果顯示，γ2、γ3、分叉部管徑曲線下面積均>0.7，具有較高的診斷價(jià)值；γ1曲線下面積為0.633，診斷價(jià)值相對(duì)較低。見(jiàn)表2、圖3。

表1 分叉部動(dòng)脈瘤組與對(duì)照組血管形態(tài)學(xué)參數(shù)比較（±s）

表2 各項(xiàng)血管形態(tài)學(xué)參數(shù)診斷效能比較

圖3 各項(xiàng)血管形態(tài)學(xué)參數(shù)診斷效能的ROC曲線

3 討論

MCA分叉部根據(jù)分支數(shù)目可分為單干型、雙干型及多干型，其中雙干型占88.75%，而MCA瘤80%~85%位于分叉部[4-5]。動(dòng)脈瘤形成與炎癥及組織變性密切相關(guān)，遺傳、血流動(dòng)力學(xué)、激素和環(huán)境也可發(fā)揮重要作用[6-7]。Low等[8]通過(guò)全基因組關(guān)聯(lián)研究識(shí)別與動(dòng)脈瘤相關(guān)的遺傳變異，發(fā)現(xiàn)染色體rs6842241與動(dòng)脈瘤顯著相關(guān)。動(dòng)脈瘤幾何形態(tài)和血流動(dòng)力學(xué)通過(guò)血液流動(dòng)（管壁切應(yīng)力和血壓）互為作用，動(dòng)脈瘤的幾何形態(tài)決定血流流動(dòng)情況，而血流流動(dòng)驅(qū)使動(dòng)脈瘤重塑，從而確定動(dòng)脈瘤未來(lái)的幾何形態(tài)（即擴(kuò)大和形態(tài)變化）[9]。Hademenos等[10]研究發(fā)現(xiàn)，血管分叉處的血流方向會(huì)發(fā)生偏移，局部血液流動(dòng)形成湍流，對(duì)動(dòng)脈分叉頂端的沖擊力及剪切力明顯加大，其壓力可達(dá)到鄰近部位載瘤動(dòng)脈壓力的2~3倍，故分叉部易形成動(dòng)脈瘤。Sadatomo等[11]對(duì)MCA分叉部載瘤動(dòng)脈與MCA主干外側(cè)夾角進(jìn)行研究，但缺乏對(duì)MCA分叉處角度的研究。既往研究發(fā)現(xiàn)，MCA分叉角及分支傾斜角的擴(kuò)大會(huì)造成血流對(duì)血管的壁面切應(yīng)力（wall shear stress，WSS）及壁面切應(yīng)力梯度增大，從而導(dǎo)致動(dòng)脈瘤形成[12]。王瑋等[13]研究認(rèn)為靠近血管分叉頂部的層流可能因明顯受阻而減小速度，外層血流與中心血流的速度差將增大WSS，導(dǎo)致動(dòng)脈瘤形成。相關(guān)研究表明，動(dòng)脈瘤患者大腦中動(dòng)脈分叉角明顯大于對(duì)照組[13-14]；但該研究樣本量相對(duì)較小（僅19例動(dòng)脈瘤），且缺乏具體數(shù)據(jù)可供篩選動(dòng)脈瘤高危人群。本研究增加了樣本量，同時(shí)也證實(shí)了分叉部動(dòng)脈瘤組與對(duì)照組間γ3差異有統(tǒng)計(jì)學(xué)意義，且進(jìn)一步發(fā)現(xiàn)兩分支夾角差異有統(tǒng)計(jì)學(xué)意義。根據(jù)ROC曲線確定當(dāng)γ3>105o時(shí)，發(fā)生動(dòng)脈瘤的危險(xiǎn)性相對(duì)較高；當(dāng)γ1<101o、γ2<91o時(shí)，發(fā)生動(dòng)脈瘤的風(fēng)險(xiǎn)較高；但γ1、γ2診斷敏感度及特異度低于γ3。Bor等[15]測(cè)量104例MCA分叉部血管的幾何參數(shù)并對(duì)患者進(jìn)行隨訪，發(fā)現(xiàn)分叉部分支發(fā)育不良（直徑<1 mm）發(fā)生動(dòng)脈瘤的幾率更大。而本研究發(fā)現(xiàn)兩分支管徑比差異無(wú)統(tǒng)計(jì)學(xué)意義，分叉部血管管徑差異有統(tǒng)計(jì)學(xué)意義，動(dòng)脈瘤組分叉部管徑小于對(duì)照組。當(dāng)分叉部管徑<1.95 mm時(shí)，發(fā)生動(dòng)脈瘤的危險(xiǎn)性相對(duì)較高，因此分叉部血管管徑也可以作為評(píng)估分叉部動(dòng)脈瘤的易感性參數(shù)之一。

總之，分叉部動(dòng)脈瘤組與對(duì)照組間γ1、γ2、γ3和分叉部管徑差異有統(tǒng)計(jì)學(xué)意義。通過(guò)CTA獲得MCA分叉部幾何形態(tài)相關(guān)參數(shù)，對(duì)篩選動(dòng)脈瘤高危人群具有一定的價(jià)值。但本研究的不足之處在于未排除對(duì)照組與動(dòng)脈瘤組患者年齡、性別、高血壓等可能危險(xiǎn)因素的影響，下一步將進(jìn)行更為深入的研究。

[1] Gong J, Sun H, Shi XY, et al. Pure subdural haematoma caused by rupture of middle cerebral artery aneurysm: case report and literature review. J Int Med Res, 2014, 42(3): 870-878.

[2] Millon D, Derelle AL, Omoumi P, et al. Nontraumatic subarachnoid hemorrhage management: evaluation with reduced iodine volume at CT angiography. Radiology, 2012, 264(1): 203.

[3] Heros RC, Fritsch MJ. Surgical management of middle cerebral artery aneurysms. Neurosurgery, 2001, 48(4): 780-785.

[4] Wong GK, Boet R, Ng SC, et al. Ultra-early (within 24 hours) aneurysm treatment after subarachnoid hemorrhage. World Neurosurg, 2012, 77(2): 311-315.

[5] 劉建民, 張榮偉, 袁紹紀(jì), 等. 破裂性大腦中動(dòng)脈瘤開(kāi)顱夾閉與血管內(nèi)栓塞的對(duì)比研究. 臨床神經(jīng)外科雜志, 2014, 11(3): 191-192, 196.

[6] Chalouhi N, Hoh BL, Hasan D. Review of cerebral aneurysm formation, growth, and rupture. Stroke, 2013, 44(12): 3613-3622.

[7] 涂雪松. 顱內(nèi)動(dòng)脈瘤的發(fā)生機(jī)制和影像學(xué)檢查. 中華腦血管病雜志(電子版), 2013, 7(6): 44-48.

[8] Low SK, Takahashi A, Cha PC, et al. Genome-wide association study for intracranial aneurysm in the Japanese population identifies three candidate susceptible loci and a functional genetic variant at EDNRA. Hum Mol Genet, 2012, 21(9): 2102-2110.

[9] Meng H, Tutino VM, Xiang J, et al. High WSS or low WSS? Complex interactions of hemodynamics with intracranial aneurysm initiation, growth, and rupture: toward a unifying hypothesis. Am J Neuroradiol, 2014, 35(7): 1254-1262.

[10] Hademenos GJ, Massoud TF. Biophysical mechanisms of stroke. Stroke, 1997, 28(10): 2067-2077.

[11] Sadatomo T, Yuki K, Migita K, et al. Morphological differences between ruptured and unruptured cases in middle cerebral artery aneurysms. Neurosurgery, 2008, 62(3): 602-608.

[12] Baharoglu MI, Lauric A, Safain MG, et al. Widening and high inclination of the middle cerebral artery bifurcation are associated with presence of aneurysms. Stroke, 2014, 45(9): 2649-2655.

[13] 王瑋, 何躍, 陳如東, 等. 大腦中動(dòng)脈分叉角度與分叉處動(dòng)脈瘤形成關(guān)系的研究. 中華神經(jīng)外科疾病研究雜志, 2012, 11(3): 197-200.

[14] 周存河, 崔彩霞, 劉懷軍, 等. 正常國(guó)人雙側(cè)大腦中動(dòng)脈分叉角度測(cè)量及腦動(dòng)脈瘤形成、發(fā)展因素的相關(guān)性研究. 腦與神經(jīng)疾病雜志, 2015, 23(3): 193-197.

[15] Bor A, Velthuis BK, Majoie CB. Configuration of intracranial arteries and development of aneurysms-a follow-up study. Neurology, 2008, 70(9): 700-705.

（本文編輯 聞浩）

Computed Tomography Angiography of Geometrical Morphology of Double Trunk Middle Cerebral Artery Bifurcation and Formation of Aneurysm

ZHANG Wei1*, WANG Juan1, LI Ting2

;

To investigate the correlation between the formation of double trunk middle cerebral artery (MCA) bifurcation aneurysm and the geometrical morphology parameters of MCA bifurcation to provide a reference for the screening of high-risk groups of aneurysms and reducing mortality and disability rate of ruptured aneurysms.Thirty patients with MCA bifurcation aneurysm (aneurysm group) and 50 patients without aneurysm confirmed by head CTA (control group) admitted to Brain Hospital of Hunan Province from January 2014 to March 2017 were retrospectively analyzed. Angles of bilateral MCA branches of the patients in the two groups were measured respectively, namely angles of branches with main trunk (angle of coarser branch with main trunk was recorded as γ1 and that of finer branch with main trunk as γ2), branch angles (γ3) and diameter of bifurcation vessel and daughter arteries. Branches angle ratio (larger branches angle/smaller branched angle) and branches diameter ratio (coarser branches/finer branches) were calculated. Difference of each parameter in the control group and aneurysm group was compared.Differences of γ1, γ2, γ3 and diameter of bifurcation vessel between aneurysm group and control group was of statistical significance (<0.05). Difference of diameter ratio and branches angle ratio was of no statistical significance (>0.05).The formation of double trunk MCA bifurcation aneurysm is to certain degree correlated with the geometrical morphology parameters of MCA bifurcation. The geometrical morphology parameters of MCA bifurcation obtained by CTA are valuable for screening high-risk groups of aneurysm.

Intracranial aneurysm; Middle cerebral artery; Tomography, X-ray computed; Cerebral angiography; Image processing, computer-assisted

R732.2；R445.3

10.3969/j.issn.1005-5185.2018.02.003

2017-10-25

2018-01-25

Chinese Journal of Medical Imaging, 2018, 26 (2): 90-93

湖南省衛(wèi)生計(jì)生委課題（B2016027）