MRI-compatible Voltage-based Electro-anatomic Mapping

System for 3T MR-guided Cardiac ElectrophysiologyShelley Zhang et al. (SCMR poster) Developing MRI-Compatible

voltage device tracking (SJM NavX, BSW Carto3) Tested on GE & Siemens, 1.5T* and 3T

• Simultaneous Tracking & Imaging. • Track inside & outside MRI• No heating, lower accuracy than MR-Tracking • Also supporting (Mylar) Invasive Blood Pressure

• Defibrillation detected and resolved inside MRI

• Working on dual MR-tracking and NavX catheters

• Working on intracardiac MRI imaging& tracking catheters

* Schmidt et. al. , MRM 2013

Computation of the Gradient-Induced Electric Field Noise in

12-lead ECG Traces During Rapid MRI SequencesShelley Zhang et al. (SCMR poster) Developing MRI-Compatible 12-

lead ECG. Tested on GE & Siemens, 1.5 and 3T

Resolving residual issues with SSFP and FSE (short TR, high Duty Cycle scans)*

• Gradient-noise (<80mV) depends on spatial magnetic-field gradients. Varies with gradient pulses and electrodes.• Perform short (3s) scan and read data.• Fit to theoretical equation• Clean ECGs at all 12 electrodes

• Integrating with hardware switching system for largest noise (limb leads)• Real-Time software processing for precordial leads.

V(t)i = αi•dGx/dt+βi•dGy/dt+γi•dGz/dt+δiGx+εiGy+ζiGz+Ci

* Tse et. al. , MRM 2013

V1

V2V3V4

V5

V6

Real-time Active-tracking of Metallic Needles during MR-guided Radiation Therapy: from concept to human trials

Wei Wang et al. (ISMRM 2014) Developing MR-Tracking for metallic devices. Integrated with Siemens 3T.*

Resolved issues with metal effects on B0 and B1

• Built 1.6mm (5 Fr) metal needles by adding printed-circuit coils into groves in tungsten needles.• Requires phase dithering MR-Tracking• Heating <0.170C• Using for guidance of brachytherapy needle insertion in cervical cancer patients • Building metallic braided deflectable catheters and sheathes for EP use

* Wang et. al. , AAPM 2013, RSNA 2013

Simulation of RF (B1) Field

2 mm

Metal needle