利用漏溢聲波及電磁追蹤技術實現導絲定位

Abstract

冠狀動脈疾病 (coronary artery disease, CAD) 是主要的心血管疾病之一，而在CAD的診斷中，血管攝影 (angiography) 與血管內超音波 (intravascular ultrasound, IVUS) 是臨床常見的診斷技術。然而，血管攝影過程中，具有輻射曝曬與顯影劑的副作用，以及二維投影影像的受限，而IVUS也只能觀察出內部血管的橫切面影像，無法完整的定位出導絲 (guidewire) 及所代表的血管確切位置。為了解決上述問題，本研究目的是開發基於漏溢聲波 (leaky acoustic waves, LAW) 之定位技術，預期藉由LAW成像方式獲取導絲的位置資訊。電磁追蹤系統 (electromagnetic tracking system, EMTS) 也將提供六個自由度 (six-degrees-of-freedom, 6-DOF) 之位置資訊，給予每張二維LAW影像對應的三維座標資訊，將搭配三維座標資訊的多張二維LAW影像進行疊合並建構出三維LAW影像，從而描繪出三維導絲行走路徑。LAW成像將於另一篇論文中進行介紹。此外，為了有效地模擬導絲在冠狀動脈行走之情形，本研究亦藉由來自掃描過程中EMTS提供的三維座標資訊，進行冠狀動脈的三維血管輪廓影像的建構。最終，由於三維LAW成像方式及三維血管輪廓影像兩者是基於不同之三維座標空間，為了明確地建構出完整的三維血管輪廓影像及導絲移動路徑相疊合的重建影像，本研究藉由座標轉換 (coordinates transformation) 運算之方式，將不同座標系進行三維座標空間的疊合，模擬出導絲在冠狀動脈中可能之三維行走路徑。最終利用本研究提出之影像建構方式，除了確保三維導絲行走路徑能完整地顯示在三維血管輪廓影像的空間內，三維血管輪廓影像在空間中的重建誤差最大達到1.90 mm左右。在未來，預期利用上述方式，在臨床上引導IVUS探頭，達到更有效率的心導管插入術診斷。

Coronary artery disease (CAD) is one of the major cardiovascular diseases. In the diagnosis of CAD, angiography and intravascular ultrasound (IVUS) are both commonly used. However, angiography poses the risk of exposure to ionizing radiation and the associated side effects of the contrast agents. Besides, it is limited to 2D projection imaging. On the other hand, IVUS can only visualize the cross-sections of interior vessel structures without the spatial information of the guidewire and the exact location relative to the vessels. To address these issues, the goal of this research is to develop alternative positioning techniques for interventional cardiology using leaky acoustic waves (LAW). An electromagnetic tracking system (EMTS) providing six-degrees-of-freedom (6-DOF) information is used to provide the 3D coordinates of each 2D LAW image. Multiple 2D LAW images are then combined to construct the 3D LAW image and depict the 3D traveling path of the guidewire. Note that the LAW images were obtained from a separate study. Besides, to simulate the 3D traveling path of the guidewire in the coronary artery, the proposed method also obtains the 3D position information from EMTS to construct 3D coronary artery morphology. Finally, since 3D LAW images and 3D coronary artery morphology are based on different 3D coordinate spaces, the coordinate transformation is conducted to overlay two separate areas into the same space. Finally, by the methods mentioned above, both the 3D traveling path of the guidewire and vessel parameters can be obtained. The maximum reconstruction error of 3D coronary artery morphology is about 1.90 mm. In the future, it is expected to guide the IVUS probe in clinical applications by the proposed methods, and more effective diagnoses in the cardiac catheterization can be obtained.