Extracellular Matrix–Specific Molecular MR Imaging Probes for the Assessment of Aortic Aneurysms

All tissues in the human body are composed of cells that are embedded in the extracellular matrix. The extracellular matrix has, besides its structural role, several important functions. These functions include important regulatory mechanisms for signal transduction and matrix cell interactions. If pathological processes, e.g., in atherosclerosis or aortic aneurysms occur, the extracellular matrix changes in response. This includes alterations in the structural and functional components of the extracellular matrix. While traditional imaging technologies, such as X-ray or computed tomography (CT), are mainly aimed at imaging morphological changes, molecular magnetic resonance (MR) imaging is a technique that enables the visualization and quantification of pathological changes on a molecular scale. Different techniques can be used for molecular MR imaging. The most commonly employed techniques include the use of specific molecular magnetic resonance probes. These probes are, in most cases, either based on iron oxide particles or gadolinium chelates for signal generation. Aortic abdominal aneurysms represent an irreversible dilation of the aortic wall which could cause severe consequences, including wall rupture with a mortality rate >90%. Due to the absence of symptoms during the development of aortic aneurysms, early diagnosis remains challenging. In the following chapter, we will outline major developments regarding extracellular matrix–specific molecular magnetic resonance imaging for the assessment of aortic aneurysms.