Interventional MRI is an established clinical tool for the biopsy of lesions that are difficult or impossible to delineate or that cannot be reached easily by any other modality. Liver and breast lesions often fall into the first category. Subdiaphragmatic liver lesions benefit particularly from the free choice of imaging planes offered by MRI.
MR-guided endovascular interventions are seldom performed in humans, despite encouraging results from animal studies. Potential advantages include high soft tissue contrast, the ability to perform unenhanced and contrast-enhanced angiography, the ability to acquire physiological data such as flow and ventricular function, and promises of “molecular imaging.”
The biggest obstacle to broader clinical acceptance of MR-guided endovascular intervention is the lack of MR-compatible instruments. Researchers have commonly made their own devices for animal studies, or used dedicated prototypes that are not commercially available for clinical studies.
Endovascular MR-guided interventions have been promoted as a way of sparing patients and practitioners from ionizing radiation. Procedures that would typically be followed on fluoroscopy were carried out under realtime MRI guidance in animals, allowing interventional radiologists to gain practical experience. The dosereduction argument was not sufficiently compelling, though, and the majority of endovascular x-ray–guided interventions have not been moved to the MRI suite. One notable exception is the diagnosis and treatment of patients with congenital heart disease. In general, however, the method has not made the critical step from the research laboratory into the clinical arena.
