磁振灌注造影對心肌受損之可逆性評估

An Evaluation Study of Myocardium Viability Using MR Perfusion Imaging

吳玉書(Yu-Shu Wu)

指導教授 ： 徐良育

中原大學/工學院/醫學工程研究所/碩士(2007年)

https://doi.org/10.6840/cycu200700876

摘要

國人冠心病隨著生活水準提昇，其發病率也上升。雖然診療方法不斷改進，對間歇性心肌損害仍是不容易察覺。已受創的心肌在治療前因缺乏心肌受損的資訊，所以無法有效評估癒後效果；過去無法明確的呈現心肌受損區域與範圍，隨著影像科技的進步，心肌灌注磁振造影已可以彌補這方面不足，本研究的主要目的就是利用磁振心肌灌注造影結合心臟功能分析技術對心肌梗塞範圍、位置及心肌存活程度，提供精確資訊，以利於臨床對梗塞性心肌疾病的治癒評估，最重要的是，磁振心肌灌注造影是一種非侵入性，而且無輻射的檢查，可以重複進行追踪檢查也不會危害病人的健康。
研究對象以臨床診斷為疑似冠心病患者，於一週內進行兩項檢查，一是磁振心肌灌注造影，採用1.5T超導體磁振造影儀，以心電門控技術，並以0.07mmol/kg，3ml/s的速率靜脈注射顯影劑(Gadolinium diethylen-triamine pentaacetic Acid﹐Gd-DTPA)，同步進行心肌首過期(first-pass)灌注掃描並採集心臟短軸切面影像，再追加2倍劑量，10分鐘後進行延遲期增強(delayed enhancement)掃描，採集心臟的短軸及長軸切面影像，觀察心肌受損的可逆性；二是心導管攝影。磁振心肌灌注造影觀察心肌血流灌注異常的部位和範圍，心導管攝影記錄狹窄血管和狹窄程度。結果分析以心導管攝影做為標準值，計算磁振心肌灌注造影對病灶的靈敏度(sensitivity)，特異性(specificity)，準確度(accuracy)；並分析計算兩者的靈敏度之間有無顯著性差異。
檢測結果顯示，在33位疑似冠心病之受檢者，磁振心肌灌注造影敏感性為90%，特異性為94%，準確率為96%，陽性預測值為90%，陰性預測值為100%。同時，冠心病之受檢者心肌缺血區的訊號強度明顯低於正常心肌，在延遲期梗塞的心肌則被強化出來。其中14位受檢者經過三個月治療後再進行追踪檢查，並分析心肌的活性及心臟的功能，比較分析術前術後差異。術前術後磁振心肌灌注的首過期時間訊號強度曲線有顯著性的差異，在治療前及治療後心肌訊號上升斜率分別為0.93±0.16及1.67±0.35 (p < 0.03)，峰值訊號為30.84±5.93及53±11.35 (p < 0.02)，兩者間有顯著性的差異。左心室局部功能，治療前及治療後之心室壁厚度分別為1.54±0.83及2.51±0.54 (p < 0.2)，心室壁增厚率則為25.90±10.13及35.26±1.70 (p < 0.3) ，兩者間無顯著性的差異。
本研究證實，磁振Cine影像不但可以用來評估冠心病患者左心室整體收縮功能，及節段性心肌功能不全，而且結合Magnetic Resonance Image Perfusion 影像可提高對冠狀動脈狹窄的診斷及心肌活性的評估。

關鍵字

冠心病 ； 磁振心肌灌注造影 ； 心肌活性

並列摘要

In recent years, the incident rate of coronary artery disease (CAD) is significantly increasing in Taiwan. It has been greatly improved in diagnosis of CAD in past decade; however, it is not easy to identify with template-damaged of myocardium. The efficiency of treatment for damaged-myocardium may not easy to evaluate due to insufficient of information in this tissue. The damaged-region and damaged-volume of myocardium were not clearly to identify in the past; in recent years, however, the information can be obtained by examining with MRI myocardial perfusion. Since MRI myocardial perfusion is a noninvasive and radiation-free exam, the health of patient can not be affected after received the exams. The purpose of this study is to analyze the cardiac function of patients with CAD after treatment by using MRI myocardial perfusion.
All the subjects included in this study were suspected with CAD. The exams of MRI myocardial perfusion and digital subtraction angiography (DSA) were taken within one week for the same patient. The images of MRI myocardial perfusion were acquired with a Siemens 1.5T MRI scanner. The technique of ECG trigger was employed in this work. All the patients were injected with GD-DTPA contrast medium with 0.07 mmol per kilogram. The images along short axis of heart were acquired with perfusion scan of first-pass with contrast medium injection rate of 3 ml/s. The images along short axis and long (both horizontal and vertical) axis of heart were acquired with delayed enhancement scan after 10 minutes later by injecting of contrast medium with injection rate of 3 ml/s. All the patients were examined with DSA to quantify the level of stenosis of artery, abnormal perfusion region and volume of myocardium. The golden standard in this work is DSA. To investigate the detection efficiency for patient examined with MRI myocardial perfusion, the sensitivity, specificity and accuracy of MRI were calculated.
Total of 33 patients were included in this study. The sensitivity, specificity and accuracy of MRI were 90%, 94% and 96%, respectively. The positive predictive value and negative predictive value were respect to 90% and 100%. The signal intensity of ischemic region of myocardium is significantly lower than that of normal region for patient with CAD. However, the signals were enhanced for infracted myocardium in the delay phase. The difference of myocardium activity and heart function before and after treatment were evaluated in 14 patients within 3 months after treatment. A significant difference of signal intensity at first phase of MRI myocardial perfusion was observed before and after treatment. The increased slops of signal of myocardium before and after treatment were 0.93±0.16 and 1.67±0.35 (p<0.03), respectively. The peak signal of myocardium before and after treatment were 30.84±5.93 and 53±11.35 (p<0.02), respectively. The wall thickness of left ventricle was improved from 1.54±0.83 to 2.51±0.54 before and after treatment. The increasing percentages of wall thickness were 25.9±10.13 (p<0.2) and 35.26±1.70 (p<0.3), which no significantly difference was observed before and after treatment.
The image of MR Cine can evaluate the contraction function of whole left ventricle and the function of segmental myocardium for patients with CAD. Moreover, the diagnosis of stenosis level of coronary artery and the myocardium activity are significantly improved by using perfusion MRI.

並列關鍵字

coronary artery disease ； Myocardium Viability ； Magnetic Resonance Image Perfusion

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