众所周知，近30年来医学科学的最主要进展之一，是曾经很多需要外科手术完成的诊断和/或治疗，如今可以在X光的导向下，经外周血管插入带有特殊装置的微细导管（catheter）完成或实施，如经皮冠状动脉成形术和/或支架置入术就可以让许多冠心病患者避免开胸接受冠状动脉搭桥手术。在心导管技术之基础上发展而来的介入诊断与治疗极大地推进了临床医学，特别是心脑血管病与外周血管病的诊治水平，但亦有其不足，即在进行介入治疗的过程中，医生和患者都不可避免地受到来自X光的辐射。因此，为了避免在介入诊断和/或治疗过程中，医生和患者接受不必要的辐射损伤。有研究人员就磁共振成像指导心导管检查进行了临床研究，结果发现“如同X光一样，磁共振成像技术亦可成功地指导临床医生实施介入诊断和/或治疗。”显然，这是一项非常了不起的研究，因为借助磁共振成像技术完成介入诊断和/或治疗，就可让医生和患者不必受到来自X光的电离辐射之损伤，值得期待啊！

NIH pilot study shows feasibility of MRI to guide heart catheter procedures

Heart catheter procedures guided by magnetic resonance imaging (MRI) are as safe as X-ray-guided procedures and take no more time, according to a pilot study conducted at the National Institutes of Health. The results of the study indicate that real-time MRI-guided catheterization could be a radiation-free alternative to certain X-ray-guided procedures.

A report of the study, which was conducted by researchers within the intramural program of the NIH’s National Heart, Lung, and Blood Institute (NHLBI), is available online in the European Heart Journal.

"This could be the first chapter of a big story," said Robert S. Balaban, Ph.D., scientific director of the NHLBI's Division of Intramural Research. "It provides evidence that clinical heart catheter procedures are possible without using radiation, which could be especially valuable in areas such as pediatrics."

MRI creates pictures of internal tissues using magnetic fields, unlike X-ray which uses ionizing radiation. In general X-ray fluoroscopy pictures have higher resolution but less detail than MRI pictures.

The research team performed transfemoral catheterization (guiding a catheter from the large vein in the leg to the heart) in 16 patients to examine the right side of the heart, including the attached veins and the pulmonary arteries. The study volunteers all needed catheterization for heart and valve disease. The researchers performed the procedure in the 16 patients using X-ray guidance, and then repeated it twice using real-time MRI guidance of a balloon-tipped catheter filled with air or with a contrast agent.

The MRI and X-ray catheterizations were successful in 15 of the 16 participants. One patient had required the use of a wire to help guide the catheter under X-ray, and currently no guidewires are available that work under an MRI.

The average procedure time for the two approaches was comparable — about 20 minutes. The team expected the MRI-guided procedure to take much longer because an MRI-compatible catheter can be harder to see in an MRI-generated image than a conventional steel catheter can be in an X-ray-generated image.

"Developing safe and conspicuous catheter devices for MRI is the chief obstacle to overcome before this approach can be widely applied at hospitals," said study lead Robert J. Lederman, M.D., a senior investigator in the NHLBI's Cardiovascular and Pulmonary Branch. "But with improved tools and further improvement of the procedure, real-time MRI catheterization may become a realistic option for many people."

Lederman's research group is still performing MRI catheterization on additional patients, and is currently designing improved catheters and other tools that will be more visible under MRI to help move this technology forward. In addition to guiding catheter procedures, the NHLBI team also hopes to use MRI to guide non-surgical catheter treatments in the future.

This study was funded by NHLBI Division of Intramural Research grants Z01-HL005062-08, Z01-HL006039-01, Z01-HL006041-01, and Z01-HL006061-01. More information about this clinical study can be found at http://clinicaltrials.gov/ct2/show/NCT01287026

For more information, or to schedule an interview, please contact the NHLBI Communications Office at 301-496-4236 or nhlbi_news@nhlbi.nih.gov. Film and visuals related to this study are also available upon request.