Abstract
Purpose: To evaluate the local specific absorption rate (SAR) and heating around retained cardiac leads during MRI at 64 MHz (1.5T) and 127 MHz (3T) as a function of RF coil type and imaging landmark. Methods: Numerical models of retained cardiac leads were built from CT and X-ray images of 6 patients with retained cardiac leads. Electromagnetic simulations and bio-heat modeling were performed with MRI RF body and head coils tuned to 64 MHz and 127 MHz and positioned at 9 different imaging landmarks covering an area from the head to the lower limbs. Results: For all patients and at both 1.5T and 3T, local transmit head coils produced negligible temperature rise (DT<0:1C) for ||B1+|| ≤ 3µT. For body imaging with quadrature-driven coils at 1.5T, ΔT during a 10-min scan remained < 3°C at all imaging landmarks for ||B1+|| ≤ 3µT and <6°C for ||B1+|| ≤ 4µT. For body imaging at 3T, ΔT during a 10-min scan remained < 6°C at all imaging landmarks for (Formula presented.). For shorter pulse sequences up to 2 min, ΔT remained < 6°C for ||B1+|| ≤ 3µT. Conclusion: For the models based on 6 patients studied, simulations suggest that MRI could be performed safely using a local head coil at both 1.5T and 3T, and with a body coil at 1.5T with pulses that produced ||B1+|| ≤ 4µT. MRI at 3T could be performed safely in these patients using pulses with ||B1+|| ≤2µT.
Original language | English (US) |
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Pages (from-to) | 653-669 |
Number of pages | 17 |
Journal | Magnetic resonance in medicine |
Volume | 81 |
Issue number | 1 |
DOIs | |
State | Published - Jan 2019 |
Funding
The mention of commercial products, their sources, or their use in connection with material reported herein is not to be construed as either an actual or implied endorsement of such products by the Department of Health and Human Services. This work was supported by National Institutes of Health, Grant/Award Numbers: K99EB021320, R01EB00684, R01MH111875, and R03EB024705.
Keywords
- RF heating
- SAR
- abandoned lead
- anatomical models
- cardiac implanted electronic device
- computational modeling
- defibrillator
- finite element method
- pacemaker
- retained lead
- safety
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging