Interventional MRI - Methods

1350531 - Rapid Electrophysiological Electro-Anatomic Mapping (EAM) in the MRI scanner using Co-registered MR-Tracking and Impedance Tracking

Friday, January 27, 2023

8:20 AM – 8:30 AM

Location: Silver Pearl 2

Presenting Author(s)

Ehud J. Schmidt, PhD

Associate Professor
Johns Hopkins University
Baltimore, Maryland, United States

Co-Author(s)

Ehud J. Schmidt, PhD

Associate Professor
Johns Hopkins University
Baltimore, Maryland, United States

Primary Author(s)

MS

Masahito Suzuki, MD

Post-doctoral Fellow
Johns Hopkins Medicine
Baltimore, Maryland, United States

Co-Author(s)

JT

Junichi Tokuda, PhD

Associate Professor
Brigham and Women's Hospital
Boston, Massachusetts, United States
GO

Gregory Olson, MSc

Director
Abbott Labs, Inc.
Minnetonka, Minnesota, United States
JS

Jeffrey Schweitzer, MSc

Director
Abbott Labs, Inc.
Minnetonka, Minnesota, United States
LN

Luca Neri, MSc

Electrical Engineer
Johns Hopkins School of Medicine
Baltimore, Maryland, United States
RB

Ryan M. Baumgaertner, BSc

Mechanical Engineer
Johns Hopkins Medicine
Baltimore, Maryland, United States
Aravindan Kolandaivelu, MD

Assistant Professor
Johns Hopkins Medicine
Baltimore, Maryland, United States
Henry R. Halperin, MD

Professor
Johns Hopkins Medicine
Baltimore, Maryland, United States

Background: We aim to increase the effficiency of Electrophyiology (EP) interventions that utilize MR imaging (LGE, TWILITE[1]) information in order to improve ablative-therapy outcomes by (a) permitting some procedure portions to be performed outside the MRI bore (e.g. on the MRI stretcher) and (b) increasing navigation and mapping accuracy by integrating (fast, but non-linear) impedance-tracking. We develop and evaluate a system that allows seamless transition between in-bore and out-of-bore tasks. We previously [2,3]rendered metallic-braided catheters and sheathes MRI-conditional at 1.5 and 3T, preserving the torquability and pushability advantages that conventional EP devices have. These devices are mounted with MR-Tracking (MRT) microcoils and electrical-electrodes, with shaft locations positionally-tracked using MRT and electrical-Impedance-Tracking (IMP)[4] within the MR-bore, and with IMP outside the bore. We developed a 3D-Slicer application which co-registers non-spatially-linear IMP and spatially-linear MRT coordinates by matching corresponding landmarks. Application then facilitates IMP/MRT catheter&sheath navigation in MRI coordinates to collect cardiac-chamber-wall intracardiac-ECGs (EGMs), constructing EAM maps, which can benefit from acquired MRI images. Examples; to detect arrhythmia circuits pre-ablation (LGE) or residual circuits post-ablation (TWILITE).

Methods: EP tool-set (Fig.1): 15-French deflectable sheath with 2 MRT and 3 IMP sensors, with internal 8.5-Fr deflectable EP catheter with 4 MRT and 5 IMP sensors[2,3]. Testing Platforms: Human-torso emulating phantom (LxWxH=55x40x35cm³) instrumented with IMP transmission pads (Fig.2), artificial EGM sources and 9x5x5cm³ simulated “cardiac-chamber”,placed within a 1.5T Siemens Aera MRI. The 3D-Slicer application receives MRT locations (12 frames/sec) from a dedicated MRT sequence, and IMP as well as EGM traces (99 frames/sec) from Abbott’s Ensite-Velocity workstation in a temporally-interleaved fashion (1.5sec MRT, 2sec IMP, 1.5sec MRT..), preventing MRT< - >IMP mutual interference.

Results:

IMP-MRT co-registration was performed by navigation to 32 points on the “cardiac-chamber”-wall and then using an thin-spline transformation (fit-error: < 3mm, registration-time: < 20 sec). Rapid IMP/MRT navigation in MRI coordinates collected ~4000 EGMs using all 5 catheter electrodes, which were then mapped onto the vessel-wall.

Conclusion:

MRI-conditional dual-tracked navigation can be used, following IMP/MRT co-registration, to perform MRI-guided EP procedures within or outside the scanner.