劉穎曹代榮方哲明顧晰邢振

1福建醫(yī)科大學(xué)附屬第一醫(yī)院影像科

2福建醫(yī)科大學(xué)附屬第一醫(yī)院耳鼻咽喉頭頸外科

·臨床研究·

LVAS患者3D-FLAIR影像表現(xiàn)及其臨床意義

劉穎1曹代榮1方哲明1顧晰2邢振1

1福建醫(yī)科大學(xué)附屬第一醫(yī)院影像科

2福建醫(yī)科大學(xué)附屬第一醫(yī)院耳鼻咽喉頭頸外科

目的利用磁共振三維快速液體衰減反轉(zhuǎn)恢復(fù)序列(3D-FLAIR)探討大前庭導(dǎo)水管綜合征（LVAS）內(nèi)耳的影像特征及其臨床意義。方法回顧性分析60只經(jīng)水成像3D-TSE序列證實(shí)的LVAS患耳和20只正常對照耳的3.0T磁共振3D-FLAIR影像，參照水成像顯示的迷路形態(tài)，觀察迷路各結(jié)構(gòu)的信號(hào)特征，測量患耳內(nèi)淋巴囊、前庭和耳蝸的信號(hào)強(qiáng)度，分析其信號(hào)與患者年齡及聽力損失分級(jí)的相關(guān)性。結(jié)果病變組中52只耳蝸和50只前庭3D-FLAIR序列顯示高信號(hào)，對照組中20只正常耳均未見高信號(hào)；內(nèi)耳高信號(hào)的存在與否和聽力損失無相關(guān)(P＝0.840)；內(nèi)淋巴囊分別與耳蝸(t＝-1.2，P=0.233)和前庭(t＝-1.807，P=0.074)之間的信號(hào)強(qiáng)度差異不具統(tǒng)計(jì)學(xué)意義；內(nèi)淋巴囊信號(hào)強(qiáng)度與患者年齡呈正相關(guān)（r＝0.510，P＝0.000），與聽力損失程度無相關(guān)（r＝0.027，P＝0.852）。結(jié)論3D-FLAIR序列可以觀察到LVAS內(nèi)耳信號(hào)的改變，與聽力損失程度無關(guān)，與患者年齡相關(guān)。

水抑制成像；大前庭導(dǎo)水管綜合征；磁共振成像

大前庭導(dǎo)水管綜合征（Large Vestibular Aque?duct Syndrome LVAS）的認(rèn)識(shí)最初得益于顳骨斷層掃描的觀察，并提出該病的最初診斷標(biāo)準(zhǔn)[1]。MRI內(nèi)耳水成像作為LVAS診斷的重要手段，對于患耳迷路形態(tài)改變的認(rèn)識(shí)已有許多報(bào)道[2-9]，我們前期觀察到LVAS患耳內(nèi)淋巴囊體積與聽力損失程度無相關(guān)[8]，另提出骨性前庭導(dǎo)水管內(nèi)存在疝出的外淋巴間隙的推測[9]，然而這些研究限于形態(tài)學(xué)觀察，無法闡述LVAS發(fā)病機(jī)制。對于能反應(yīng)迷路內(nèi)淋巴液成分的MR信號(hào)變化除Sugiura[6]個(gè)案報(bào)道外，尚無專題研究。我們利用對液體成份變化高度敏感的三維液體衰減反轉(zhuǎn)恢復(fù)(three-dimensional fluid attenuated in?version recovery 3D-FLAIR)序列觀察LVAS迷路信號(hào)變化，探討LVAS迷路信號(hào)與患者年齡及聽力損失的相關(guān)性。

1 資料與方法

1.1 病例資料

收集30例（60只耳）由CT確診的大前庭導(dǎo)水管綜合征，合并其他內(nèi)耳畸形者（如Mondini畸形）剔除。男性20例，女性10例，中位年齡4歲（1-41歲）。20%LVAS患者具家族性[7]，30例患者中12例分屬4個(gè)家庭，18例散發(fā)病例。對照組10例共20只正常耳，男性6例，女性4例，中位年齡8歲（3-15歲）；入選標(biāo)準(zhǔn)為無耳部自覺癥狀且聽力學(xué)檢查正常，內(nèi)耳及顱腦MR正常；對照組源于因頭痛來我院行顱腦MR檢查的患兒，告知其父母情況，同意加做內(nèi)耳MR及聽力學(xué)檢查者作為志愿者。受檢者（未成年人由父母代簽）均簽署知情同意書。

1.2 聽力檢測

30名患者及10名對照組志愿者均在MR檢查前后一周內(nèi)在我院完成聽力檢查，其中15名不配合小兒行ABR檢查，25名可配合者行純音電測聽檢查，患者及對照組聽力分級(jí)參照WHO[1]標(biāo)準(zhǔn)。

1.3 MR檢查

3.0 T SIEMENS MAGNETOM VERIO MR掃描，16通道頭線圈采集，重T2水成像及3D-FLAIR序列均采用 SPACE(Sampling Perfection with Applica?tion-optimized Contrast different flip angle Evolutions)，重T2水成像用于解剖定位，參數(shù)：TR=1000ms，TE= 132ms,空間分辨率0.50 mm×0.50 mm×0.50 mm,采集時(shí)間4分50秒；3D-FLAIR序列用于信號(hào)分析，參數(shù)：TR=6000 ms，TE=388 ms,TI=2100 ms，采集時(shí)間5分 32秒,空間分辨率0.70 mm×0.70 mm×0.70 mm。

1.3 圖像分析

由2名熟悉內(nèi)耳MR的醫(yī)師（分別具備6年、21年影像診斷經(jīng)歷）以腦脊液為參照，分別評(píng)估前庭及耳蝸3D-FLAIR信號(hào)，高于腦脊液信號(hào)者記錄為高信號(hào)；2名醫(yī)師評(píng)估結(jié)果的一致性行組內(nèi)相關(guān)系數(shù)分析，信度良好則Pearson’s chi-squared檢驗(yàn)分析前庭及耳蝸高信號(hào)的存在與否與聽力損失程度的相關(guān)性。2名醫(yī)師進(jìn)一步分別測量前庭、耳蝸及同一層面的內(nèi)淋巴囊信號(hào)強(qiáng)度后取平均值（圖1A/C），獨(dú)立樣本t檢驗(yàn)比較前庭與內(nèi)淋巴囊、耳蝸與內(nèi)淋巴囊的信號(hào)強(qiáng)度差異。3D-FLAIR感興趣區(qū)（ROI）的放置參照水成像定位（圖1）。水成像顯示:部分LVAS患者內(nèi)淋巴囊可見高低信號(hào)分界(圖1B/D)（研究[9]顯示水成像高信號(hào)部分為外淋巴液疝入骨性前庭導(dǎo)水管及巖骨后緣，并非真正的內(nèi)淋巴囊），因此測量3D-FLAIR高信號(hào)部分代表真正的內(nèi)淋巴囊，信號(hào)分析參照文獻(xiàn)[10]的半定量法，選取同層面小腦半球?yàn)閰⒄眨▓D1 A/C），計(jì)算內(nèi)淋巴囊/小腦信號(hào)強(qiáng)度比，Spearman’s rank-correlation coefficient分析內(nèi)淋巴囊/小腦信號(hào)強(qiáng)度比與患者年齡、聽力損失程度的相關(guān)性。所有統(tǒng)計(jì)應(yīng)用SPSS19.0統(tǒng)計(jì)學(xué)軟件（ver19.0;Chicago,IL,USA）分析數(shù)據(jù)，P＜0.05設(shè)為差異有統(tǒng)計(jì)學(xué)意義。

圖1 LVAS內(nèi)耳信號(hào)強(qiáng)度的測量方法：ROI以水成像圖像(圖1B/D)為參照，3D-FLAIR序列上選取中心層面手動(dòng)圈出耳蝸(1A)、前庭(1C)及內(nèi)淋巴囊(1A,1C)高信號(hào)區(qū)域，并圈出同層面同側(cè)3cm2大小的小腦半球，測量其信號(hào)強(qiáng)度(圖1A/C)。Fig.1 The measurement of the signal intensity of LVAS inner ear.Placed the ROI on 3D-fluid-attenuated inversion recovery (3D-FLAIR)images(Fig1A,1C)with referenced to the heavily T2-weighted images at the same level(Fig 1B,1D).We focused on the cochlea(Fig 1A),vestibule(Fig 1C)and endolymphatic sac(Fig 1A,1C),we placed ROI in the high signal area on 3D-FLAIR(Fig 1A,1C).The signal of the cerebellum at the same level as the endolymphatic sac was used as an internal reference(Fig 1A,1C).

2 結(jié)果

3D-FLAIR序列顯示：20只正常耳均無高信號(hào)(圖2A)，60只LVAS患耳52只耳蝸(圖2B)、50只前庭(圖2C)存在高信號(hào)，60只患耳中有43只耳蝸及前庭同時(shí)存在高信號(hào)。LVAS患者內(nèi)淋巴囊與前庭(t＝-1.807，P=0.074)、內(nèi)淋巴囊與耳蝸(t＝-1.200，P= 0.233)之間信號(hào)強(qiáng)度差異均無統(tǒng)計(jì)學(xué)意義。

60只患耳年齡介于1-41歲，中位年齡4歲；患耳內(nèi)淋巴囊與小腦信號(hào)強(qiáng)度比平均值為0.92±0.30，該信號(hào)強(qiáng)度比與患者年齡線性正相關(guān)（r＝0.510，P＝0.000）。

60只患耳中，輕度聽力下降（26-40 dB HL）3只，中度聽力下降（41-60 dB HL）3只，重度聽力下降（61-80 dB HL）2只，極重度聽力下降（＞80dB HL）52只。內(nèi)淋巴囊信號(hào)強(qiáng)度比與患者聽力損失程度無相關(guān)性（r＝0.027，P＝0.852）；前庭或耳蝸中高信號(hào)存在與否與患者的聽力損失程度無相關(guān)(P＝0.840)。

60只LVAS患耳中16只耳3D-FLAIR序列上內(nèi)淋巴囊僅見高信號(hào)影(圖3A)，44只耳低信號(hào)區(qū)以前庭導(dǎo)水管開口為中心向遠(yuǎn)端延伸，后緣始終有高信號(hào)區(qū)，分界清楚，弧形膨隆(圖3B)。無1例僅見低信號(hào)。無1只耳3D-FLAIR序列上內(nèi)淋巴囊僅見低信號(hào)。

圖2 LVAS及志愿者正常耳3D-FLAIR迷路信號(hào)特點(diǎn)：10歲志愿者，內(nèi)耳無高信號(hào)影（圖2A）；5歲LVAS女孩，右側(cè)耳蝸及內(nèi)淋巴囊見高信號(hào)影（圖2B）；6歲LVAS男孩，左側(cè)前庭見高信號(hào)影。（圖2C）。Fig.2 The signal intensity feature of inner ear in the healthy control and LVAS on 3D-FLAIR images.No high signal was present in the inner ear of a 10-year-old healthy control(Fig 2A).High signal intensity was identified in the cochlea of a 5-year-old girl with LVAS(Fig 2B).High signal intensity was identified in the vestibule of a 6-year-old boy with LVAS(Fig 2C).

圖3 LVAS患者擴(kuò)大內(nèi)淋巴囊的信號(hào)特點(diǎn)：4歲LVAS男孩，內(nèi)淋巴囊內(nèi)僅見高信號(hào)影（圖3A）；6歲LVAS男孩，內(nèi)淋巴囊除有高信號(hào)區(qū)外,還有和腦脊液相似的低信號(hào)區(qū),低信號(hào)區(qū)后緣有高信號(hào)區(qū)，分界清楚，呈弧形膨隆。（圖3B）。Fig.3 The signal characteristics of the endolymphatic sac in LVAS.Only hyperintense signal was observed in the endolymphatic sac of a 4-year-old boy with LVAS(Fig 3A).High-signal area co-occurred with a low-signal area was observed in the endolymphatic sac with clear boundary and in curved bulge of a 3-year-old girl with LVAS(Fig 3B).

3 討論

三維液體衰減反轉(zhuǎn)恢復(fù)(three-dimensional fluid attenuated inversion recovery 3D-FLAIR)序列可抑制自由水信號(hào)，對液體成份變化的敏感性明顯優(yōu)于水成像[11-13]。水成像序列內(nèi)、外淋巴液均為高信號(hào)，無法區(qū)別；由于3D-FLAIR序列對液體成分變化的高敏感性，同時(shí)內(nèi)淋巴液蛋白含量遠(yuǎn)高于外淋巴液，濃度約1000～3000mg/100ml[14]，因此內(nèi)淋巴液呈高信號(hào)，外淋巴液呈低信號(hào)。正常人耳蝸、前庭及半規(guī)管以外淋巴液為主，外淋巴液總量是內(nèi)淋巴液總量的28.4倍[15]，因此正常人耳蝸、前庭3D-FLAIR呈低信號(hào)；內(nèi)淋巴囊僅含內(nèi)淋巴液，LVAS患者內(nèi)淋巴囊3D-FLAIR呈高信號(hào)。

本組病例3D-FLAIR顯示：LVAS組耳蝸及前庭見高信號(hào)，且信號(hào)強(qiáng)度與內(nèi)淋巴囊信號(hào)呈正相關(guān)，而無癥狀對照組無高信號(hào)。LVAS患者前庭和耳蝸3D-FLAIR顯示高信號(hào)提示其蛋白含量增高，考慮這些區(qū)域有較多內(nèi)淋巴液，從影像學(xué)上支持多數(shù)學(xué)者提出的內(nèi)淋巴倒流理論，即LVAS患者外傷等引起腦脊液壓力的突然波動(dòng)，壓迫淋巴囊周圍的硬腦膜，有可能使淋巴循環(huán)從高滲的內(nèi)淋巴囊倒流，迫使內(nèi)淋巴囊的高滲液通過寬大的內(nèi)淋巴管逆流，并經(jīng)擴(kuò)大了的水管進(jìn)入淋巴循環(huán)，經(jīng)連合管流入耳蝸，引起毛細(xì)胞退變導(dǎo)致患者感音神經(jīng)性聾[16-20]。

另外觀察到LVAS患者內(nèi)淋巴囊信號(hào)與年齡呈正相關(guān)，提示擴(kuò)大的內(nèi)淋巴囊中蛋白成分隨年齡增長而升高，這支持Pyle[20-21]報(bào)道的前庭水管隨年齡增長可出現(xiàn)動(dòng)態(tài)變化；內(nèi)淋巴囊組織學(xué)研究[22]表明：內(nèi)淋巴囊結(jié)構(gòu)呈囊樣，存在吞噬細(xì)菌、細(xì)胞碎屑和其他小顆粒的功能異常，可引起內(nèi)淋巴囊內(nèi)容液的濃縮，因此內(nèi)淋巴囊3D-FLAIR序列信號(hào)隨年齡增長而升高。

進(jìn)一步分析LVAS患者迷路信號(hào)與聽力損失程度的相關(guān)性，發(fā)現(xiàn)前庭、耳蝸高信號(hào)的存在與否和聽力損失程度無相關(guān)，而且內(nèi)淋巴囊信號(hào)強(qiáng)度與聽力損失程度亦無相關(guān)，可能是本組患者以重度聾為主而影響了結(jié)果。

由于本組患者以重度聾為主，無一例在聽力下降過程中行MR觀察，無法及時(shí)了解MR信號(hào)改變與患者聽力動(dòng)態(tài)變化的相關(guān)性。聽障兒童的語言功能發(fā)展呈現(xiàn)出年齡差異,干預(yù)年齡越早，聽障兒童的語言功能發(fā)展越快[23]，因此及早得通過MR信號(hào)及聽力情況了解并干預(yù)LVAS患兒的治療，對于未來語言發(fā)展及聽力保護(hù)具重要作用，這方面有待影像及耳科醫(yī)師進(jìn)一步研究探討。

4 結(jié)論

LVAS患者的前庭和耳蝸與內(nèi)淋巴囊的3D-FLAIR序列信號(hào)強(qiáng)度相關(guān)，且內(nèi)淋巴囊信號(hào)強(qiáng)度隨LVAS患者年齡的增長而升高，預(yù)示著內(nèi)淋巴囊高滲液倒流及內(nèi)淋巴囊內(nèi)液體蛋白含量隨病程進(jìn)展而升高。

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3D-FLAIR MRI Findings and Its Clinical significance in Patients with Large VestibularAqueduct Syndrome

LIU Ying1,CAO Dairong1,FANG Zheming1,GU Xi2,XING Zhen1
1 Departments of Radiology,
2 Departments of Otolaryngology-Head and Neck Surgery,The First Affiliated Hospital of Fujian Medical University

Subject To study characteristics of inner ears imaging with 3D-fluid-attenuated inversion recovery (3D-FLAIR)and its clinical significance in patients with large vestibular aqueduct syndrome(LVAS).MethodsStudy subjects included 30 patients(60 ears)with bilateral LVAS confirmed by water imaging with 3D-TSE sequence and 10 normal volunteers(20 ears).3D-FLAIR sequence was performed using a 3-Tesla MR scanner.With comparison to labyrinth morphology on routine inner ear water imaging,characteristics of labyrinth signals were examined.Signal intensities(SI)in the endolymphatic sac,vestibule and cochlea was measured,and their correlation to the degree of hearing loss and patient age analyzed.Correlation between the SI ratio(SIRs)of the endolymphatic sac and patient age(degree of hearing loss)was investigated.ResultsOn 3D-FLAIR,high signal was present in 52 cochleae and 50 vestibules among the 60 ears with LVAS, and in none of the 20 normal ears.There was no significant difference between endolymphatic sac SI and that of the vestibule(t＝-1.807，P=0.074)or cochlea(t＝-1.2，P=0.233).There was no correlation between high SI in inner ear and hearing loss(P＝0.840).A positive linear correlation,however,was found between SIR and patient age(r＝0.510，P＝0.000),but not between SIR and hearing loss(r＝0.027，P＝0.852).Conclusion Signal variation in inner ear seen on 3D-FLAIR sequences does not correlate with the degree of hearing loss,but with patient age in LVAS.

Fluid Attenuated Inversion Recovery;Enlarged Vestibular Aqueduct Syndrome;Magnetic Resonance Imaging

R764

A

1672-2922（2016）06-783-5

2016-05-17審核人：婁昕）

10.3969/j.issn.1672-2922.2016.06.016

劉穎，碩士，主治醫(yī)師，研究方向:頭頸部影像診斷

方哲明，Email:409016093@qq.com