Vertical open-bore MRI scanners generate significantly less radiofrequency heating around implanted leads: A study of deep brain stimulation implants in 1.2T OASIS scanners versus 1.5T horizontal systems
Ehsan Kazemivalipour
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey
Search for more papers by this authorBhumi Bhusal
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Search for more papers by this authorJasmine Vu
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois, USA
Search for more papers by this authorStella Lin
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Search for more papers by this authorBach Thanh Nguyen
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Search for more papers by this authorJohn Kirsch
A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA
Search for more papers by this authorElizabeth Nowac
Department of Neurosurgery, Albany Medical Center, Albany, New York, USA
Search for more papers by this authorJulie Pilitsis
Illinois Bone and Joint Institute (IBJI), Wilmette, Illinois, USA
Search for more papers by this authorJoshua Rosenow
Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Search for more papers by this authorErgin Atalar
Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey
Search for more papers by this authorCorresponding Author
Laleh Golestanirad
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois, USA
Correspondence
Laleh Golestanirad, Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N Michigan Ave, Suite 1600, Chicago, IL 60611, USA.
Email: [email protected]
Search for more papers by this authorEhsan Kazemivalipour
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey
Search for more papers by this authorBhumi Bhusal
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Search for more papers by this authorJasmine Vu
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois, USA
Search for more papers by this authorStella Lin
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Search for more papers by this authorBach Thanh Nguyen
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Search for more papers by this authorJohn Kirsch
A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA
Search for more papers by this authorElizabeth Nowac
Department of Neurosurgery, Albany Medical Center, Albany, New York, USA
Search for more papers by this authorJulie Pilitsis
Illinois Bone and Joint Institute (IBJI), Wilmette, Illinois, USA
Search for more papers by this authorJoshua Rosenow
Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Search for more papers by this authorErgin Atalar
Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey
Search for more papers by this authorCorresponding Author
Laleh Golestanirad
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, Illinois, USA
Correspondence
Laleh Golestanirad, Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N Michigan Ave, Suite 1600, Chicago, IL 60611, USA.
Email: [email protected]
Search for more papers by this authorBhumi Bhusal and Ehsan Kazemivalipour contributed equally to this work.
Abstract
Purpose
Patients with active implants such as deep brain stimulation (DBS) devices are often denied access to MRI due to safety concerns associated with the radiofrequency (RF) heating of their electrodes. The majority of studies on RF heating of conductive implants have been performed in horizontal close-bore MRI scanners. Vertical MRI scanners which have a 90° rotated transmit coil generate fundamentally different electric and magnetic field distributions, yet very little is known about RF heating of implants in this class of scanners. We performed numerical simulations as well as phantom experiments to compare RF heating of DBS implants in a 1.2T vertical scanner (OASIS, Hitachi) compared to a 1.5T horizontal scanner (Aera, Siemens).
Methods
Simulations were performed on 90 lead models created from post-operative CT images of patients with DBS implants. Experiments were performed with wires and commercial DBS devices implanted in an anthropomorphic phantom.
Results
We found significant reduction of 0.1 g-averaged specific absorption rate (30-fold, P < 1 × 10−5) and RF heating (9-fold, P < .026) in the 1.2T vertical scanner compared to the 1.5T conventional scanner.
Conclusion
Vertical MRI scanners appear to generate lower RF heating around DBS leads, providing potentially heightened safety or the flexibility to use sequences with higher power levels than on conventional systems.
Supporting Information
| Filename | Description |
|---|---|
| mrm28818-sup-0001-TableS1-3.docxWord document, 30.3 KB |
TABLE S1 Maximum of 0.1g SAR values for patient 47 (ID47) with different convergence thresholds TABLE S2 Maximum of 0.1g SAR TABLE S3 Measured temperature increase at the lead tip for each implant model |
| mrm28818-sup-0002-VideoS1.mp4MPEG-4 video, 8.2 MB | VIDEO S1 Incident E field (arrows) and Etan (color field overlaid on leads) for varying intrinsic phases along lead trajectories in patient #47 for the 1.2 T vertical OASIS coil and 1.2 T and 1.5 T horizontal birdcage coils. Simulations were done for the head imaging landmark and the coil's input power was adjusted to generate a mean  = 4 μT over a circular plane placed on an axial plane passing through the coil's iso-center |
Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
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