Editorial Slides VP Watch, February 5, 2003, Volume 3, Issue 5

Towards The Future Cath Lab

Jarek WosikPaul Cherukuri

Texas Heart Institute

– In the past two decades, MRI has been slowly introduced into the world of cardiovascular medicine.

– In early 1980s Higgins and others envisioned MRI applications for detection of cardiac structural abnormalities (such as congenital anomalies) as well as acute and remote myocardial infarctions, atherosclerotic plaques, hypertrophic cardiomyopathy, pericardial diseases, aneurysms, and patency of bypass graft. 2

Manning et al. demonstrated the power of noninvasive MRI coronary angiography to identify substantial stenosis correctly within the proximal portion of major coronary arteries in a group of patients undergoing conventional contrast coronary angiography. Other investigators also introduced MRI application in non-invasive coronary imaging.3,4,5

• Intravascular MRI (iMRI) is a potential tool for the detailed characterization and localization of plaques as well as having the added benefit of implementing local therapy.

• iMRI is simply a wire resonator tuned to the external applied pulse generated by an extravascular MRI system. The resonator due to it’s close proximity to the target body increases the signal from that region thereby capable of providing microscopic images

This image is a selective angiogram of a kidney after a catheter is placed in the renal artery using real-time MRI guidance. The image shows good spatial detail of the renal artery, renal parenchyma, and

collecting system.

This panel of images shows a sequence of real-time MRI-guided cardiac injections. 

NHLBI - Robert Lederman

Atlar also showed a new development that uses high-resolution MR imaging as an in vivo imaging tool to monitor catheter-based vascular gene delivery. 9

In another study Atalar et al showed that coronary artery catheterization and intracoronary balloon angioplasty are feasible with MRI guidance indicating that iMRI maybe an alternative to X-ray guidance in coronary artery interventions in the future. 8

Intercept™ Vascular .030" Internal MR Coil

Pre-Clinical Animal Image www.Surgi-Vision.com

• Guenther RW et al have shown that active tip tracking simultaneous with MRI of the vascular anatomy-both in real time-is possible, enabling MR-guided percutaneous dilatation (PTA) of iliac arteries.10

• Buecker A et al presented a new sequence for real-time MR imaging sequence reliably allowed for high-quality coronary MR fluoroscopy without motion artifacts in all pigs for accurate stent placement. Ten of 11 coronary stents were correctly placed under MR guidance. 11

• Wilke NM et al recently demonstrated that catheter tracking and ASD device closure can be performed under real-time MRI guidance with the use of intravascular antenna guide wires. 12

• As highlighted in VP Watch of this week, Serfaty, Atalar and colleagues have shown the feasibility of using an MR imaging guide wire as a potential tool for use in endovascular interventional MR imaging-guided balloon angioplasty. 7

• A prototype 0.014-inch coronary MRI guidewire, a prototype 7 French MRI-guiding catheter, and two flexible surface coils were connected to a GE 1.5 T CV/i scanner for simultaneous visualization of the guidewire, guiding catheter, and chest anatomy.

• Images were displayed in real time on an in-room monitor. A nongated, single-slice fast gradient-echo sequence was used to obtain real-time images of the catheters and background anatomy during the intervention.

• Fifteen selective catheterizations were attempted in the coronary arteries, and all were successful.

• Selective injection of diluted gadolinium into the MRI-guiding catheter provided dynamic 2D projection coronary angiography in all cases, confirming successful catheterization.

• Percutaneouse transluminal coronary angioplasty (PTCA) was attempted after two catheterizations, and all attempts were successful. Inflation of the balloon angioplasty catheter was performed successfully in the left anterior and circumflex arteries.

Conclusion:• Coronary artery catheterization and

intracoronary balloon angioplasty are feasible with MRI guidance only.

• MRI guidance may be used as an alternative to X-ray guidance in coronary artery interventions in the future.

Questions:• 1- What are the technological and

non-technological barriers for the implementation of MRI guided PCI?

• 2- Can we make everything in cath labs MR compatible? Or should we try to make MRI cath lab compatible?

Questions:• 3- What are the accreditation

and reimbursement issues in cardiovascular MRI?

• 4- Can MRI replace X-ray systems in future cath labs?

Is XMR (combined X-Ray and MRI) a viable solution for cath labs?

MRI

X-Ray