Interventional CMR Course
SCMR 22nd Annual Scientific Sessions
We describe our early institutional experience performing real-time interventional CMR (iCMR) procedures for congenital heart disease (CHD) using the MRI compatible wire (angle-tip Emeryglide MRWire, Nano4Imaging, Aachen, Germany) to guide catheters for RHC a left heart catheterization (LHC).
Patients with CHD underwent iCMR at 1.5 T with the MRWire. The MRI area is co-located adjacent to a standard catheterization laboratory. A dilute gadolinium-filled balloon-tip catheter was used in combination with the MRWire for RHC, LHC, and Fontan fenestration test occlusion (FFTO), under real-time MRI visualization. LHC included trans-septal navigation to obtain pressures in the left atrium with pulmonary vein access for saturations, and access across stenotic areas such as a severe coarctation of the aorta (CoA). A recently developed catheter tracking technique (Real-time spoilt gradient echo (TFE), FA 35-45O, TE 1.3ms; TR 2.7ms; 40O partial saturation (pSAT) pre-pulse) was used to visualize the gadolinium-filled balloon, MRWire, and cardiac structures simultaneously. MRWire visualization is enabled due to distal markers creating susceptibility artifact. Pre-clinical phantom testing was performed to determine the optimum imaging FA-pSAT combination.
MRWire was used on 16 out of 25 patients [10 single ventricle (SV) and 6 bi-ventricular (BiV)] undergoing iCMR. Median age and weight were 6.7yrs and 19.6kg (range:2-16yrs and 9.2-61.6kg). 10 patients had SV anatomy: 6 for pre-Fontan evaluation, and 4 post-Fontan patients for PLE/cyanosis evaluation. 6 patients with BiV anatomy: 3 underwent vaso-reactivity testing with inhaled Nitric Oxide, 1 underwent RV volume and branch PA stenosis evaluation and remaining 2 BiV patients had CoA.
Real-time MRI-guided RHC (n = 16), LHC/aortic pull back (n = 16), CoA crossing (n = 2) and FFTO (n = 2) was successfully performed in all patients when the MRWire was used. No complications were encountered. Time taken for first pass RHC and LHC/aortic pull back was 4.9 and 2.9 minutes, respectively. Patients were transferred to the fluoroscopy lab if further intervention was required (including fenestration device closure, covered stent placement to relieve CoA, balloon angioplasty for stenotic vessels, and coiling of collaterals in SV patients).
Feasibility for diagnostic RHC and LHC iCMR procedures in SV and BiV pediatric patients with CHD is demonstrated. MRWire was used to successfully complete detailed RHC and LHC iCMR procedures in complex CHD. Novel real-time TFE with optimized FA-pSAT has facilitated simultaneous visualization of the catheter balloon tip, MRWire, and cardiac/vessel anatomy during iCMR procedures.