介入磁共振

簡介

介入磁共振(Interventional Magnetic Resonance),是近年發展起來的新技術,套用磁共振引導器械可達到診斷或治療疾病的目的。作為介入導向工具,磁共振具有其它影像學方法無法比擬的優勢,其組織對比優良,空間解析度達亞毫米級,對病變定位及其介入引導均有益,更重要的是磁共振具有多平面和三維容積重建的能力,可全面評價介入靶灶與鄰近組織的重要解剖關係。

在介入手術過程中醫師要能夠隨時接近患者,開放式磁體技術的出現和快速成像技術的進步,使磁共振引導下的介人性治療得以發展。開放式磁共振系統成像空間大,手術可以在掃描區域內、外進行,術中可隨時掃描與監控,既便於實時觀察術中情況,又大大地提高了工作效率。

介入磁共振系統磁體設計

開展介入性磁共振最重要的條件是磁體系統能夠允許醫生接觸病人並進行介入操作。越容易接觸到患者的系統,其介入性能越好。目前的開放式系統,可以滿足介入磁共振的需要。Picker和Siemens公司的開放系統為“馬蹄”形垂直式磁體,GE公司的磁體呈雙“麵包圈 樣,即在兩個線圈之間留有一較大間隙,可以允許270度垂直式接觸患者,由於患者可在坐位下成像,特別適於腦和會陰部的介入磁共振操作。超短或較短的磁體,甚至是標準磁體,也有用做介入磁共振的,其缺點是與患者接觸差,優勢是磁體強度較高,利於實時成像技術的實施。

介入磁共振 介入磁共振

圖1 開放性介入磁共振系統

介入磁共振手術場所及器械設備

磁共振介入手術在磁共振禁止室內進行的,磁共振介入導航具有室內操作控制台和磁體間內顯示屏。室內操作控制台體積小巧、移動方便,可以在掃描室內進行各種磁共振操作,便於醫師與技師隨時溝通。磁兼容室內顯示屏能清晰顯示術中磁共振圖像,既方便手術操作,又能實時監控手術全過程。下圖為醫生在進行磁共振介入手術。

介入磁共振 介入磁共振

圖2 醫生在磁共振禁止室內進行介入手術

使用設備及器械要求是磁兼容的,即不含鐵質材料。含鐵質的非磁兼容性物品受磁場的吸引會發生飛射,容易造成人身傷害。同時強磁場、梯度場及射頻信號也會干擾非磁場兼容性設備的正常使用,當梯度場開啟時心電導聯會接收到強噪聲信號,干擾正常的心電圖波形。而磁流體動力因素也會影響通過心臟的血流,使正常的心電圖波形發生變形。非磁兼容性設備工作時還會干擾MR 成像,使圖像變形、出現偽影,是手術器械的磁敏感偽影或設備產生電子信號的電磁干擾造成的。由於低場開放式磁共振系統的磁場強度較低, 因而對設備與器械磁兼容性的要求會比超導高場磁共振相對降低。磁共振介入手術禁止室內需要消毒處理,例如紫外線燈空氣消毒,掃描磁體、射頻線圈覆蓋無菌罩等。標準的磁共振介入手術室還應參照手術室的設計,配有醫護人員更衣、洗手的潔淨區,醫護人員與患者通過不同的通道進入磁共振介入手術室。

磁共振介入手術中要有磁共振兼容性生命監護設備, 實時監控患者的心率、呼吸、血氧、血壓等生理信息的變化,緊急情況下宜及時採取救治措施,保證手術過程的安全性。磁兼容麻醉設備通常用於全麻手術中, 目前一些微創介入治療如氬氦刀冷凍、放化療粒子植入或椎間盤旋切與臭氧消融等,由於治療過程患者痛苦小,一般在局麻方式下即可完成。其他輔助設備如超聲吸引器、外科顯微鏡、神經外科骨鑽、神經刺激器、身體固定架、患者取暖加熱器等會根據不同的手術而有所需要,這些設備如果放在禁止室內則要求是磁兼容的。

介入磁共振成像序列

介入磁共振導航為了配合術中的實時導引與監控, 需要有專門設計的快速成像序列,應滿足以下要求:(1)成像速度快;(2)穿刺針偽影大小適中,既要足夠大以易於觀察,又不能太大以免影響穿刺病灶的顯示;(3) 要保證病灶與鄰近組織間、病灶與穿刺偽影間有足夠的對比度;(4) 必須選擇理想的序列,以能顯示沿穿刺針道上的易損結構。單一序列是不可能完全滿足以上4 項要求,因此,在手術過程中,通常使用一個以上的序列。為了加快成像速度,常採取K 空間取樣步驟、平行成像技術及微波編碼數據接收技術。

磁共振介入導航的主要方式

目前磁共振導航的主要方式為光學導航, 該系統主要包括紅外線導航相機、定位示蹤器、配有導航光球的持針器以及導航功能軟體、手術規劃軟體等。三維動態主動跟蹤介入手術器械的位置並投射到實時顯示的磁共振圖像上是磁共振導航技術一個至關重要的優勢。手術器械固定在帶有定位標記物或微型射頻探測器的持針器上, 一般用光學或梯度方法跟蹤手術器械,通過捕獲電荷耦合的相機裝置,光學追蹤導航器械上的定位標記物(至少3 個),標定物與追蹤器械的位置、方向等信息與圖像序列信息通過計算機準確計算與處理, 使手術醫生就

能夠隨時了解手術器械與病變、重要組織結構的位置關係,從而使複雜的操作更加簡捷、直觀。

磁共振介入的臨床套用

磁共振引導的介入手術,主要是病理活檢、穿刺引流、腫瘤消融與近距離放化療綜合治療、詩經阻滯與損毀、頸腰間盤旋切與臭氧治療等諸多方面,手術部位涉及神經系統、呼吸系統、泌尿生殖系統、骨骼肌肉軟組織、眼球以及肺、肝、腎、前列腺等諸多器官,成功率高。具體為:

•MR引導下經皮穿刺活檢及囊腫、血腫和膿腫的抽吸引流;

•腫瘤間質消融治療:腫瘤雷射熱消融術、氬氦刀冷凍消融治療;

•腫瘤內局部放射性粒子及化學藥物植入術;

•疼痛治療:神經根阻滯與腹腔神經叢的阻滯與損毀術;

•椎間盤突出微創性旋切結合臭氧治療術;

•中晚期帕金森病的微創治療;

•乳腺早期病變及前列腺腫瘤的病理診斷與冷凍消融治療。

擴展閱讀

趙磊,王洋. MRI 導引與監控微創介入治療技術[J]. 醫學影像學

林征宇,武樂斌,李成利,等.光學導航介入性MR的臨床套用[J].中華放射學雜誌,2005,39(7):740—742.

F.A. Jolesz, S.M. Blumenfeld. Interventional use of magnetic resonance imaging.

Magn Reson Q, 10 (1994), pp. 85–96

J. Kettenbach, D.F. Kacher, S.K. Koskinen, etal. Interventional and intraoperative magnetic resonance imaging. Annu Rev Biomed Eng, 2 (2000), pp. 661–690

J.S. Lewin, C.A. Petersilge, S.F. Hatem, etal. Interactive MR imaging-guided biopsy and aspiration with a modified clinical C-arm system. AJR Am J Roentgenol, 170 (1998), pp. 1593–1601

R. Lufkin, L. Teresi, L. Chiu, W. Hanafee. A technique for MR-guided needle placement.AJR Am J Roentgenol, 151 (1988), pp. 193–196

R. Lufkin, L. Teresi, W. Hanafee. New needle for MR-guided aspiration cytology of the head and neck. AJR Am J Roentgenol, 149 (1987), pp. 380–382

P.R. Mueller, D.D. Stark, J.F. Simeone, etal. MR-guided aspiration biopsy: needle design and clinical trials. Radiology, 161 (1986), pp. 605–609

G. Duckwiler, R.B. Lufkin, W.N. Hanafee. MR-directed needle biopsies. Radiol Clin North Am, 27 (1989), pp. 255–263

E. vanSonnenberg, P. Hajek, V. Gylys-Morin, etal. A wire-sheath system for MR-guided biopsy and drainage: laboratory studies and experience in 10 patients. AJR Am J Roentgenol, 151 (1988), pp. 815–817

H.E. Cline, J.F. Schenck, K. Hynynen, R.D. Watkins, S.P. Souza, F.A. Jolesz. MR-guided focused ultrasound surgery. J Comput Assist Tomogr, 16 (1992), pp. 956–965

B. Quesson, J.A. de Zwart, C.T. Moonen. Magnetic resonance temperature imaging for guidance of thermotherapy. J Magn Reson Imaging, 12 (2000), pp. 525–533

E. Salomonowitz. MR imaging-guided biopsy and therapeutic intervention in a closed-configuration magnet: single-center series of 361 punctures. AJR Am J Roentgenol, 177 (2001), pp. 159–163

Y. Popowski, E. Hiltbrand, D. Joliat, M. Rouzaud. Open magnetic resonance imaging using titanium–zirconium needles: improved accuracy for interstitial brachytherapy implants? Int J Radiat Oncol Biol Phys, 47 (2000), pp. 759–765

J.F. Schenck, F.A. Jolesz, P.B. Roemer, etal. Superconducting open-configuration MR imaging system for image-guided therapy. Radiology, 195 (1995), pp. 805–814

D.H. Gronemeyer, R.M. Seibel, L. Kaufman. Low-field design eases MRI-guided biopsies. Diagn Imaging (San Franc), 13 (1991), pp. 139–143

R. Ojala, E. Vahala, J. Karppinen, et al. Nerve root infiltration of the first sacral root with MRI guidance. J Magn Reson Imaging, 12 (2000), pp. 556–561

Buecker, G. Adam, J.M. Neuerburg, A. Glowinski, J.J. van Vaals, R.W. Guenther. MR-guided biopsy using a T2-weighted single-shot zoom imaging sequence (Local Look technique). J Magn Reson Imaging, 8 (1998), pp. 955–959

J.L. Duerk, J.S. Lewin, D.H. Wu. Application of keyhole imaging to interventional MRI: a simulation study to predict sequence requirements.J Magn Reson Imaging, 6 (1996), pp. 918–924

G. Adam, A. Bucker, C. Nolte-Ernsting, J. Tacke, R.W. Gunther. Interventional MR imaging: percutaneous abdominal and skeletal biopsies and drainages of the abdomen.Eur Radiol, 9 (1999), pp. 1471–1478

1.

趙磊,王洋. MRI 導引與監控微創介入治療技術[J]. 醫學影像學

2.

林征宇,武樂斌,李成利,等.光學導航介入性MR的臨床套用[J].中華放射學雜誌,2005,39(7):740—742.

3.

F.A. Jolesz, S.M. Blumenfeld. Interventional use of magnetic resonance imaging.

4.

Magn Reson Q, 10 (1994), pp. 85–96

5.

J. Kettenbach, D.F. Kacher, S.K. Koskinen, etal. Interventional and intraoperative magnetic resonance imaging. Annu Rev Biomed Eng, 2 (2000), pp. 661–690

6.

J.S. Lewin, C.A. Petersilge, S.F. Hatem, etal. Interactive MR imaging-guided biopsy and aspiration with a modified clinical C-arm system. AJR Am J Roentgenol, 170 (1998), pp. 1593–1601

7.

R. Lufkin, L. Teresi, L. Chiu, W. Hanafee. A technique for MR-guided needle placement.AJR Am J Roentgenol, 151 (1988), pp. 193–196

8.

R. Lufkin, L. Teresi, W. Hanafee. New needle for MR-guided aspiration cytology of the head and neck. AJR Am J Roentgenol, 149 (1987), pp. 380–382

9.

P.R. Mueller, D.D. Stark, J.F. Simeone, etal. MR-guided aspiration biopsy: needle design and clinical trials. Radiology, 161 (1986), pp. 605–609

10.

G. Duckwiler, R.B. Lufkin, W.N. Hanafee. MR-directed needle biopsies. Radiol Clin North Am, 27 (1989), pp. 255–263

11.

E. vanSonnenberg, P. Hajek, V. Gylys-Morin, etal. A wire-sheath system for MR-guided biopsy and drainage: laboratory studies and experience in 10 patients. AJR Am J Roentgenol, 151 (1988), pp. 815–817

12.

H.E. Cline, J.F. Schenck, K. Hynynen, R.D. Watkins, S.P. Souza, F.A. Jolesz. MR-guided focused ultrasound surgery. J Comput Assist Tomogr, 16 (1992), pp. 956–965

13.

B. Quesson, J.A. de Zwart, C.T. Moonen. Magnetic resonance temperature imaging for guidance of thermotherapy. J Magn Reson Imaging, 12 (2000), pp. 525–533

14.

E. Salomonowitz. MR imaging-guided biopsy and therapeutic intervention in a closed-configuration magnet: single-center series of 361 punctures. AJR Am J Roentgenol, 177 (2001), pp. 159–163

15.

Y. Popowski, E. Hiltbrand, D. Joliat, M. Rouzaud. Open magnetic resonance imaging using titanium–zirconium needles: improved accuracy for interstitial brachytherapy implants? Int J Radiat Oncol Biol Phys, 47 (2000), pp. 759–765

16.

J.F. Schenck, F.A. Jolesz, P.B. Roemer, etal. Superconducting open-configuration MR imaging system for image-guided therapy. Radiology, 195 (1995), pp. 805–814

17.

D.H. Gronemeyer, R.M. Seibel, L. Kaufman. Low-field design eases MRI-guided biopsies. Diagn Imaging (San Franc), 13 (1991), pp. 139–143

18.

R. Ojala, E. Vahala, J. Karppinen, et al. Nerve root infiltration of the first sacral root with MRI guidance. J Magn Reson Imaging, 12 (2000), pp. 556–561

19.

Buecker, G. Adam, J.M. Neuerburg, A. Glowinski, J.J. van Vaals, R.W. Guenther. MR-guided biopsy using a T2-weighted single-shot zoom imaging sequence (Local Look technique). J Magn Reson Imaging, 8 (1998), pp. 955–959

20.

J.L. Duerk, J.S. Lewin, D.H. Wu. Application of keyhole imaging to interventional MRI: a simulation study to predict sequence requirements.J Magn Reson Imaging, 6 (1996), pp. 918–924

21.

G. Adam, A. Bucker, C. Nolte-Ernsting, J. Tacke, R.W. Gunther. Interventional MR imaging: percutaneous abdominal and skeletal biopsies and drainages of the abdomen.Eur Radiol, 9 (1999), pp. 1471–1478

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