Non-contrast-enhanced magnetic resonance imaging for visualization and quantification of endovascular aortic prosthesis, their endoleaks and aneurysm sacs at 1.5 T

Purpose: After an endovascular aortic aneurysm repair (EVAR), a follow-up at 1, 6 and every 12 months is recommended for remainder of the patient's life. The diagnostic standard methods for diagnosing endoleaks and visualization of aneurysms in EVAR-patients are: invasive digital subtraction angiography (DSA), contrast enhanced (CE) computed tomographic angiography (CE-CTA), and magnetic resonance angiography (CE-MRA). These techniques, however, require the use of iodine- or gadolinium-based contrast agents with rare, but possibly life threatening side effects such as renal impairment, thyrotoxicosis and allergic reactions, nephrogenic systemic fibrosis, and cerebral gadolinium deposition. The aim of this prospective study was to compare a non-contrast-enhanced MRI protocol (consist of four MRI methods) with DSA and CE-CTA for visualization and quantification of endovascular aortic prosthesis, their endoleaks and aneurysms.

Material and methods: Eight patients (mean age 76.8 ± 4.9 years, 63% male), whose thoracic, abdominal, or iliac aneurysms were treated with different endovascular prosthesis and suffered from type I-V endoleaks, were examined on a 1.5 Tesla MR system. Quiescent-interval slice selective MR angiography (QISS-MRA), 4-dimensional (4D)-flow MRI, T₁- and T₂-mapping, as well as DSA and CE-CTA were used for the visualization and quantification of endoprosthesis, endoleaks, and aneurysms in these patients.

Results: QISS-MRA provided good visualization of endoleaks and comparable quantification of aneurysm size with respect to CE-CTA and DSA. The 4D-flow MRI provided additional information about the wall shear stress, which could not be determined using DSA. In contrast to CE-CTA, T₁- and T₂-mapping provided detailed information about heterogeneous areas within an aneurysm sac.

Conclusions: Compared to DSA and CE-CTA, the proposed MRI methods provide improved anatomical and functional information for various types of endoprostheses and endoleaks. In addition, hemodynamic parameters of the aorta and information on the content of aneurysm sac are provided as well. Within the frame of personalized medicine, the personalized diagnosis enabled by this non-CE MRI protocol is the foundation for a personalized and successful treatment.