聽瘤3相關影像學技術進展和電生理監(jiān)測

1、DTT在聽神經(jīng)瘤診治中的應用進展,浙江大學醫(yī)學院附屬邵逸夫醫(yī)院神經(jīng)外科郭洪彬,,,DTT 成像的基本原理（diffusion tensor tractography，DTT）,以往有關大腦白質纖維束（white matter fiber ，WMF）的研究主要依賴于活體動物的大腦組織或尸體解剖研究。常規(guī)的磁共振成像如 T2WI、FLAIR、MT (magnetization transfer imaging )圖像雖然可以顯示大腦白質和

2、灰質之間的差別，但這些成像方法不能顯示大腦白質纖維的走行方向，因此也就不能提供完全的白質纖維的解剖信息。DTI反映了 WMF 中水分子彌散的方向依賴特性，其 FA 圖像可以顯示大腦白質纖維的結構和各向異性特征，如顯示內(nèi)囊、胼胝體、外囊等結構。但 DTI 不能提供相鄰體素之間白質纖維是如何連接的。,,隨著計算機軟件的不斷開發(fā)和利用，人們利用 DTI 所獲得的數(shù)據(jù)進行大腦白質纖維成像，此即為彌散張量纖維束成像（diffusion tenso

3、r tractography，DTT），DTT 是 DTI 技術的進一步發(fā)展，它可以辨認大腦內(nèi)的特殊纖維通道及其相互之間的連接。由于 DTT 是新近應用的磁共振彌散成像技術，其名稱尚欠統(tǒng)一，例如有稱為纖維跟蹤技術（fiber tracking）或白質纖維束成像（tractography）等。,Abstract,Methods We investigated 11 patients with VS who underwent tumor

4、resection. Visualized tracts were compared with loca- tions of the facial and cochlear nerves as identified by intra- operative electrophysiological monitoring.作者研究了11例的聽神經(jīng)瘤的病例，并進行了手術切除。所獲得的DTT成像與術中的神經(jīng)電生理所示的面神經(jīng)和耳蝸神經(jīng)的位置比

5、較。,,Conclusions We visualized facial or vestibulocochlear nerves in nine of 11 patients (81.8 %). For the first time, DTT proved able to visualize not only the facial nerve but also the vestibulocochlear nerve in VS pati

6、ents. 面神經(jīng)和前庭耳蝸神經(jīng)的可視率達81.8 %，DTT第一次被證明可用于可視化前庭耳蝸神經(jīng)。,Abbreviations,平均擴散率(mean diffusivity，MD)與各向異性分數(shù)(fractional anisotropy, FA)是最常用的DTI導出量,MD反映水分子擴散的劇烈程度，F(xiàn)A反映水分子擴散的各向異性程度。,Introduction,Most recently, preoperative predicti

7、on of the locations of the nerves using diffusion tensor tractography (DTT) has been adopted as an aid to improving preservation rates for facial nerve function。術前應用DTT預測神經(jīng)纖維束的所在，被采用以提高聽瘤手術的面神經(jīng)功能保留率。,Materials and metho

8、ds,MRI was performed using a 3.0-T system (Signa 3.0 T; GE, Milwaukee, WI, USA) equipped with an eight-channel phased-array head coil.MRI采用的是3.0T的。,,Fig. 1 Method for setting the seed region of interest (ROI). In the pr

9、oposed method, the porus of the internal auditory canal is viewed from a direction parallel to the courses of the nerves inside the internal auditory canal (a arrow), and the seed ROI is placed at the porus of the intern

10、al auditory canal in a plane perpendicular to the courses of the nerves (b red circle),,From among the visualized fiber tracts, we verified as true fiber tracts those that ran on the surface or inside of the tumor and re

11、ached the brainstem and were identified as nerves based on electrophysiological testing performed during the operation.在那些被顯示的纖維束中，作者認定那些走行在腫瘤表面或中間，且到達腦干的可視的纖維束為true纖維束。然后根據(jù)術中的神經(jīng)電生理檢測認定為神經(jīng)纖維束。,,Identifying the vestibula

12、r nerve electrophysiologi- cally during surgery is not currently possible. We therefore judged visualized fiber tracts that coincided with the cochlear nerve identified during surgery as the vestibulocochlear nerve.因為術中

13、電生理目前還不能辨識前庭神經(jīng)。所以術中根據(jù)走形判定，與耳蝸神經(jīng)匯合的為前庭耳蝸神經(jīng)。,,With regard to the cochlear nerve, since we invented electric stimuli-elicited dorsal cochlear nucleus ac- tion potential (ESE-DNAP) monitoring [5, 9], we could iden- tify the

14、specific direct connection of the specific nerve fascicle with the dorsal cochlear nucleus by intraoperative electrical stimulation around 0.2–0.4 mA.辨識耳蝸神經(jīng)也很困難。辨識耳蝸神經(jīng)。依據(jù)作者的一個發(fā)明。electric stimuli-elicited dorsal cochlear

15、 nucleus ac- tion potential (ESE-DNAP) monitoring,Results,facial nerve function according to House & Brackmann Classification(House-Brackmann 面神經(jīng)癱瘓分級,1級正常，6級全癱)hearing function was graded using the Gardner-Robertson

16、 Classification,House-Brackmann 面神經(jīng)癱瘓分級（中文-隱藏）,顧建文教授，解放軍306醫(yī)院級別類別臨床特征Ⅰ級正常所有面部功能正常Ⅱ級輕度功能障礙大體觀察：眼瞼閉合檢查時輕度無力；可有非常輕微的連帶運動靜止狀態(tài)：面部對稱，張力正常運動狀態(tài)：額部－功能中度至良好眼部－輕度用力可完全閉合嘴部－輕度不對稱,Ⅳ級中－重度功能障礙大體觀察：明顯的無力和/或影響外觀的不對稱運動狀態(tài)：額

17、部－無運動眼部－閉合不完全嘴部－用最大力仍有不對稱Ⅴ級重度功能障礙大體觀察：只有非常輕微的可察覺的運動靜止狀態(tài)：不對稱嘴部－僅有輕度運動Ⅵ級完全無功能無運動,Ⅲ級中度功能障礙大體觀察：面部兩側有明顯差異但不影響外觀，明顯可見但不嚴重的連帶運動，痙攣，和/或半側面肌痙攣運動狀態(tài)：額部－輕度至中度運動眼部－用力可完全閉合眼瞼嘴部－用最大力仍有輕度無力,Gardner-Robertson 聽力分級（中文版）,Re

18、sults,,,,,,平均擴散率(mean diffusivity，MD)與各向異性分數(shù)(fractional anisotropy, FA)是最常用的DTI導出量,MD反映水分子擴散的劇烈程度，F(xiàn)A反映水分子擴散的各向異性程度。,,Fig. 2 Case 2. Contrast-enhanced fast imaging employing steady-state acquisition imaging shows left cer

19、ebellopontine angle vestibular schwannoma in the (a) axial view. b Axial view of diffusion tensor tractography (DTT). c Sagittal view of DTT. d Oblique view of DTT. DTT when using the upper limit of the FA threshold visu

20、alizes the fiber tract running in the posterior middle one-third to the tumor. e, fIntraoperative view. Electrophysiological diagnosis performed during the surgery confirms that the cochlear nerve passes in the p

21、osterior middle one-third to the tumor (f asterisk). Positive wave of elicited dorsal cochlear nucleus action potential (ESE-DNAP) represents the presence of the cochlear nerve (e arrowhead),Case 2,術前把FA值設定在上限時可顯示一個模糊的DT

22、T影在腫瘤的中后部。術中電生理證實耳蝸神經(jīng)穿行在腫瘤的中后三分之一。ESEDNAP顯示陽性波，顯示為耳蝸神經(jīng)。,,In this patient, we intended to preserve hearing function, and there- fore only performed a biopsy at that time, since resection of the tumor without injury to the

23、 cochlear nerve using a lateral suboccipital approach seemed very difficult. We subsequently performed complete resection of the tumor using an extended middle cranial fossa approach.此病例，作者試圖保留聽力，所以只做了活檢，因為手術采用的是枕下外側入路，

24、作者認為這個入路極有可能損傷到聽神經(jīng)。所以下次采用中顱窩入路全切腫瘤，術后聽力為1級。,,Fig. 3 Case 8. DTT when using the upper limit of the fractional anisotropy threshold visualizes the fiber tract running in the anterior superior one-third to the tumor. d Int

25、raoperative view. Electrophysiological diag- nosis performed during the sur- gery confirms that the facial nerve runs in the anterior superior one- third to the tumor (asterisk) a圖顯示曾強MR一個大型聽瘤。采用FA上限設定，DTT顯示一個纖維束穿行在腫瘤的前

26、上三分之一。術中神經(jīng)電生理監(jiān)測在為面神經(jīng)。,Discussion,,,,追根溯源（……）,,第一步，設定興趣點a。第二步，非選擇性重建。第三步，根據(jù)內(nèi)聽道內(nèi)發(fā)出的纖維走向，重建。,,病例4,70歲女性。磁共振腦池成像不能辨別面神經(jīng)，DTT發(fā)現(xiàn)面神經(jīng)被腫瘤擠壓向前移位。,,病例2,55歲女性。A增強MR，bMR腦池造影，c和d 立體顯像， e透明疊加顯像。DTT顯示面神經(jīng)束被擠向后上。F，術中證實。,,病例4,63歲女性，b圖中箭頭所

27、示的線樣影像好像是面神經(jīng)，但是應用DTT未能發(fā)現(xiàn)在此處的纖維束。,,病例5，34歲男性，MR提示一個囊性的聽神經(jīng)瘤。術中發(fā)現(xiàn)一個神經(jīng)束被壓向前下，而DTT顯示一個神經(jīng)纖維束穿過了腫瘤，腫瘤內(nèi)有橫隔樣結構。,Discussion,In this report, we indicated for the first time that DTT allows visualization of not only the facial nerve

28、 but also the vestibulocochlear nerve in VS patients.此報道第一次闡述了，DTT不僅能顯示面神經(jīng)，而且能顯示前庭耳蝸神經(jīng)。,,In fact, we were uncertain whether the fiber tract visualized on DTT represented facial nerve, vestibulocochlear nerve, or mere no

29、ise in case 2, because the visualized fiber tract followed a course that the facial and vestibulocochlear nerves were considered unlikely to take對于case2，作者術前不能確定DTT圖像顯示的是面神經(jīng)還是前庭耳蝸神經(jīng)，因為作者認為這樣的走形，面神經(jīng)和前庭耳蝸神經(jīng)都不大可能出現(xiàn)。,,FA va

30、lues of the nerve fiber tract visualized as the vestibulocochlear nerve were higher than those of the facial nerve, leading to a higher rate of vestibulocochlear nerve vi- sualization by DTT.能夠顯示前庭耳蝸神經(jīng)的神經(jīng)纖維束的FA值比面神經(jīng)的高，導

31、致前庭耳蝸神經(jīng)比面神經(jīng)在DTT圖像上更容易被分辨出來。,,Application of DTT to VS was first reported by Taoka et al. [14], and in a later study the preoperative visualization rate for the facial nerve was increased to 90.9 % [3]. On the other hand,

32、 visualization of the vestibulocochlear nerve was either not mentioned [1, 10] or was reported as impossible [3]. The present results are thus very different .DDT應用于聽神經(jīng)瘤的診治首先是2006年由Taoka et al使用。后來，DTT于術前顯示面神經(jīng)的比率增加到90.9

33、%。但DTT顯示前庭耳蝸神經(jīng)卻沒有被提及，或者被報道為不可能。,,With regard to interpretation, as shown in this study, completely eliminating false tracts is difficult, and even if only nerve fiber tracts can be visualized, distinguishing whether a de

34、picted fiber represents facial or vestibulocochlear nerve or noise is also problematic.此技術，就像在此研究中提到的，完全消除錯誤的神經(jīng)束的是很困難的。即使看到了神經(jīng)束，也不能確定它代表的是面神經(jīng)還是前庭耳蝸神經(jīng)或者是noise。,,even though fibers other than the facial nerve may have bee

35、n visualized, previous reports have judged the visualized fiber as representing the facial nerve, thus increasing the visualization rate for the facial nerve.正是因為不是面神經(jīng)纖維束的纖維束可能被顯影，以前的報道判斷實際上增加了面神經(jīng)的顯示率。,,Despite our find

36、ings, good methods for distinguishing whether a visualized nerve tract represents facial nerve, vestibulocochlear nerve, or only noise remain unavailable. Close attention should therefore be paid to the interpretation of