MRI技術(shù)應(yīng)用：胸部和全腹部

1、胸部和全腹部門控(Gating) 人體許多部位的器官和組織都會或多或少地受呼吸.液體流動.脈搏和心跳的影響，所以在做相應(yīng)部位檢查的時候為了采集相對靜止的圖像，人們采取了一些措施，一般的方法為增加預(yù)飽和脈沖序列，其中目前主要的方法是利用“門控”。 類型主要為：呼吸觸發(fā).周圍脈搏和心電門控。什么是門控？ In Magnetic Resonance Imaging It is a device to synchronize MR data collection with the physiological motions of the patient It significantly reduces

2、 motion-related artifacts due to Respiration Flow Cardiac MotionOverview Types of Gating Respiratory Triggering PPG Gating Cardiac GatingRespiratory Triggering Types of Gating What is it used for? To reduce artifacts caused by respiratory motion or when a patient is unable to perform a breath-hold W

3、here is it used? Most used in the abdomen to help produce clear, artifact-free images of the anatomical structures in the abdomen What is needed? Respiratory bellow and respiratory gating hardware How does it do it? By synchronizing data collection of the sequence to the patients respiratory motion.

4、Respiratory Triggering Types of Gating How does it do it? By synchronizing data collection of the sequence to the patients respiratory motion. Changes in the patients chest circumference are converted to electronic signal and related to the MR Imaging system Proper placement of the bellows is requir

5、ed across the trunk of the patient where the breathing is most evident. They should be place taut across the patient. Avoid stretching of the bellows Instruct patient to breath normalthis insures a most accurate waveform Respiratory interval typically ranges from 400 ms - 15000 ms for one respirator

6、y cycle.Respiratory TriggeringRespiratory TriggeringNext Types of Gating Respiratory Triggering PPG Gating Cardiac Gating PPG What is is used for? To reduce artifacts caused by CSF motion or when CINE imaging with better coverage of diastole is desired Where is it used? Cervical & Thoracic Spine

7、 What is needed? Photoplethysmography (PPG) peripheral pulse monitory and hardware How does it work? The patients pulse will trigger data acquisition and synchronize image collection to the patients pulsePeripheral Pulse GatingPeripheral Pulse Gating Dichrotic Notch Occurs at the end of systole, and

8、 the beginning of diastole when the aortic valve closes. The aorta contracts, causing flow into the coronaries and a slight increase in peripheral flowNext Types of Gating Respiratory Triggering PPG Gating Cardiac GatingCardiac Gating ECG What is is used for? To reduce artifacts from cardiac motion,

9、 imaging of the heart or any other areas affected by the cardiac cycle Where is it used? In the thorax What is needed? ECG Electrodes, Lead Wires & hardware How does it work? By synchronizing MR Data collection of the sequence with the cardiac cycle of the patientCardiac Gating波形Cardiac Gating D

10、iastole The period of ventricular filling beginning near the end of the T wave and ends near the peak of the R wave Systole The period of ventricular contraction starting after the R wave and ends near the end of the T waveProblem Solving What to do if gating doesnt work? Check connections of the th

11、e gating hardware Check proper placement on the patient Respiratory Are the bellows stretched to far or not far enough PPG Does the patient have finger nail polish or long finger nails ECG Are the lead wires braided Did you select the proper gating softwareConclusion Types of Gating Respiratory Trig

12、gering PPG Gating Cardiac Gating胸部 縱隔結(jié)構(gòu)及病變顯示：平掃橫斷位T1W+T2W（加上門控），強化后再掃T1W（壓脂）。 另外可視病變部位加掃矢狀或冠狀位甚至斜位。 層厚38mm不等，注意選擇相位編碼的方向以及調(diào)整FOV的大小，以防折疊偽影的產(chǎn)生。 心臟的掃描主要是觀察結(jié)構(gòu)與其功能，所以掃描序列主要為T1W和Cine,強化后進(jìn)行心肌灌注掃描（包括延遲掃描）和AngioCe成像。位置包括：橫斷位 長短軸 四腔室和幾個進(jìn)出口及其瓣膜。T1w圖像T1W&Cine四腔室入 出口流出道T2w 圖像短軸的掃法 長軸怎么掃？MRC的臨床應(yīng)用心臟的常規(guī)定位方法瓣膜及大

13、血管的顯示 主動脈瓣MRA&MRA-DSA 未減影圖像 減影后圖像胸主動脈圖像定位像腹部（上中下） 平掃：T1W+T2W，強化：T1W（壓脂）。另外根據(jù)臨床要求，增加水成像，動態(tài)掃描和延遲掃描序列。 胰腺和腎臟(腎上腺）的檢查需要作平掃壓脂。 水成像要根據(jù)患者情況來決定用2D還是3D掃描。 層厚18mm或自定義。 方位：在橫斷位的基礎(chǔ)上增加冠 矢以及斜位。肝 膽 胰 脾 腎（T2W）T1W膽腸道的顯示盆腔直腸癌女性生殖系統(tǒng)MRI在胎兒檢查中的應(yīng)用尸檢后再做MRI. CT和X-ray檢查乳腺 一般用專用的乳腺線圈，也可以用別的信噪比相似的表面線圈代替（個人觀點）。冠狀，橫斷再加上失狀位。平掃 ：T1w（SE）+T2W（FSE 壓脂）+STIR。強化后掃T1w(壓脂）。患者主要采用俯臥位，讓乳房自然懸垂，偶爾也采用