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Guy's Hospital pioneers MR-guided cardiac catheterizations in children

Best Practice
Prof. Razavi, Reza London, Guy's Hospital United Kingdom

 

Clinicians at Guy's Hospital London are revolutionizing clinical practice by performing MR-guided cardiac catheterizations in patients.To date, Guy's physicians have performed MR-guided procedures on over 30 patients with congenital heart disease (CHD), dramatically reducing - and in some cases completely eliminating - exposure to ionizing radiation.

 

The pioneering work of Reza Razavi, M.D., Director of Cardiac MRI at Guy's and St. Thomas' NHS Trust, appeared in a recent issue of the prestigious The Lancet journal. "This study showed for the first time that by using passive device visualization it is possible to perform MR-guided cardiac catheterization in humans," Dr. Razavi says.
 Catheter manipulation under MR guidance. The anesthesized patient is in the Intera MR scanner during catheter manipulation under MR guidance. Draping and vascular access procedures. At the x-ray side of the suite, the patient undergoes routine draping and vascular access procedures.
Catheter manipulation under MR guidance. The anesthesized patient is in the Intera MR scanner during catheter manipulation under MR guidance.
Draping and vascular access procedures. At the x-ray side of the suite, the patient undergoes routine draping and vascular access procedures.

MR excels in critical areas

Compared with x-ray, MRI offers superb soft-tissue visualization and the capacity to deliver functional information, such as quantitative blood flow - resulting in a high degree of flexibility and more clinical data for the clinician. Furthermore, use of MR dispels concerns about excessive x-ray dose to patients, especially children with CHD.

 

"Exposing very young children to x-rays has always been a source of anxiety among physicians, since the effect is cumulative and it is important to avoid adding to their lifetime dose," says Dr. Razavi. "This is particularly important for CHD patients, who often need successive interventions to correct their disorder and will require lifetime monitoring, which can involve many imaging studies. Clearly, alternative imaging techniques are needed to eliminate or limit x-ray exposure."

Philips XMR suite is a key tool in pioneering work

Currently, Guy's Hospital's strategy is to use the complementary benefits of x-ray and MR in its Philips XMR suite, which combines a 1.5T Intera I/T system, a BV Pulsera cardiac x-ray unit and an AngioDiagnost 5 Syncratilt table in the same RF and x-ray screened suite.

 

In the study, investigators acquired baseline MRI images of anesthetized patients using a high-resolution multi breath-hold 3D B-FFE scan of the entire thorax with up to 10 phases of the cardiac cycle for detailed delineation of the anatomy. A B-FFE interactive scan enables mapping and recording of the likely imaging planes along the route of catheter manipulation. Patients were then transferred to the x-ray side of the suite for routine draping and vascular access procedures.

 

"We used either MR guidance alone or both MR and x-ray to advance the catheter

based on ease of catheter manipulation," Dr. Razavi observes. "In some cases, when manipulation required the use of a non-MR compatible guidewire, we used x-ray guidance to place catheters in the appropriate structure."

 

Guy's researchers also found that performing cardiac catheterization under MR guidance yields greater physiological and anatomical information. "For the first time, we have shown it is possible to estimate pulmonary vascular resistance using simultaneous invasive pressure measurements and MR flow data," he says. "Our results show an important increase in accuracy when using MR flow quantification compared with the use of the traditional Fick's principle. Accurate PVR quantification is critical in managing our patients, especially when deciding on suitability for surgery."

 

Because the use of XMR in pediatric cardiology is an entirely new concept - with Guy's spearheading this global effort - a close working relationship between the center and Philips has been vital.

 

"We're exploring totally new clinical procedures, so Philips' support has been crucial to achieving our objectives," says Dr. Razavi.

 

XMR and image registration combines cardiac anatomy with electrophysiology (EP) devices. If x-rays alone are used to guide catheters into and around the heart, the cardiologist acquires a reasonable idea of the catheter's position, but obtains little data on inner cardiac surfaces where he might want to place a catheter or another device. (WIP research, Guy's Hospital).

 

 

MR allows combination of cardiac soft

tissue anatomy, EP device, electrical

maps and CSPAMM motion maps in

a single graphical view. (WIP research,

Guy's Hospital).

 

 

Images made during catheter manipulation ... through the cardiac chambers into the pulmonary artery under real-time MR guidance. The tip of the balloon catheter is seen as a black spot in these real-time images.
Images made during catheter manipulation
... through the cardiac chambers into the pulmonary artery under real-time MR guidance. The tip of the balloon catheter is seen as a black spot in these real-time images.
Images made during catheter manipulation through the cardiac chambers into the pulmonary artery under real-time MR guidance. The tip of the balloon catheter is seen as a black spot in these real-time images.

Reference

R Razavi, DLG Hill, SF Keevil, ME Miquel, V Muthurangu, S Hegde, K Rhode, M Barnett,

J van Vaals, DJ Hawkes, E Baker

Cardiac catheterisation guided by MRI in children and adults with congenital heart disease

The Lancet, 2003, Vol 362, 1877-1882



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Achieva 1.5T, Intera 1.5T
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Explorer / Nova Dual, Master / Nova, Nova, Nova Dual, Omni / Stellar, Power / Pulsar, Pulsar
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