動脈粥樣硬化斑塊的穩定度和其組成、結構及血管內脈動的壓力等皆息息相關。若能在硬化斑塊破裂前判定斑塊的穩定度進而辨別出不穩定者，不僅可預防血管栓塞的發生，以經濟考量而言更可節省可觀的醫療資源。目前醫學界及科學界正積極研究試圖進一步了解動脈粥樣硬化過程以助後續治療的設計。動脈粥樣硬化斑塊的穩定性和其組成有緊密的關連，因此一個適當的成像方法的研發將有助於硬化斑塊微結構的分析，當前非侵入性的顯影方法尚未能精確地提供此項資訊。本研究計畫將採用一新穎的X光位相差成像法(phase-contrast imaging)，即多重成像之X光成像術(multiple-image radiography (MIR)，來探討此一重要問題。
Abstract: Characterization of human atherosclerotic plaques by use of X-ray imaging
Atherosclerotic plaque is a form of atheromatous deposition accumulated on the walls of arteries. Its composition, often calcified, generally includes cholesterol lipid, fibrous connective tissues, and cellular debris. Atherosclerosis is potentially a life-threatening disease. Carotid plaque rupture can lead to many acute coronary events such as stokes and heart attacks. The stability of a plaque depends on its composition, structure, and pulsating pressure. There are great economic and health advantages to characterize the stability of plaques and identify the vulnerable plaques before rupture. There is an active effort underway to enhance the understanding of the progression of this disease and to aid the selection of the appropriate treatment. Plaque microstructure is known to strongly influence plaque stability. Accordingly, the development of imaging technologies capable of characterizing plaque microstructure would have tremendous value for clinical and basic science investigations. Currently available non-invasive imaging techniques are not capable of providing detailed information regarding plaque microstructure. The proposed project aims to address this important problem by use the development of a novel phase-sensitive of X-ray imaging method called multiple-image radiography (MIR).
Multiple-image radiography (MIR) is a novel phase-contrast imaging method that produces three concurrent images depicting the X-ray attenuation, refractive index, and ultra-small angle X-ray scattering (USAXS) properties of the imaged object. These three images provide complementary information and detailed descriptions regarding the tissue features that are not provided by conventional X-ray imaging methods. Currently, we are actively working on quantitatively evaluating and characterizing carotid plaque microstructure using the MIR method. The reconstructed X-ray images will be cross-correlated with the histology microscopy images, which serve as the gold standard images to identify the composition and vulnerability of plaques.
Our preliminary studies have suggested that calcified, fibrous, and lipid-rich tissues will produce MIR images that reveal their geometric configurations and permit their differentiation. Accordingly, the MIR method will produce a detailed characterization of plaque microstructure that conventional methods cannot. Because of the strong and multiple contrast mechanisms it exploits, MIR will not require the use of iodinated contrast agents to visualize tissue interfaces. Additionally, MIR presents the opportunity for very low dose imaging, which would render it a viable screening method.