A Fast Parallel Imaging Rotary Phased Array Head Coil with Improved Sensitivity Profile Deep in the Center of the Brain

Objective: To compare and evaluate the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) values between a 15-channel phased array head coil and 6-channel dS Flex M surface coil in the MRI of temporomandibular joint. Methods: 300 patients were randomly assigned to two groups: 150 patients were examined by using a 15-channel phased array head coil and the other 150 patients were scanned by using a 6-channel dS Flex M surface coil. All of the data were set in the same 6 regions of interest including the temporal lobe, condyle neck, lateral pterygoid muscle, parotid gland, the adipose area and an area of the background noise）. SNR and CNR values were measured respectively. Results: The numerical variation law of SNR and CNR values measured in regionsof interest of each group was similar, although different coils were used. There were statistically significant differences of SNR values in all of the oblique sagittal (OSag) proton density-weighted imaging, the part of OSag T 2 weighted image (T 2WI) except for SNR4 and SNR5. and oblique coronal (OCor) T 2WI sequence except for SNR2. On the contrary, SNR4 and SNR5 values in the OCor T 2WI and SNR5 values in OSag T 2WI sequences by using the surface coil were higher than those by using the head coil. There were no statistically significant intergroup differences of CNR values in OSag proton density-weighted imaging sequence except CNR1 and in OSag T 2WI sequence except CNR5. But, statistically significant differences of all the values in the OCor T 2WI sequence except for CNR1 were observed. Conclusion: Both the phased array head coil and dS Flex M surface coil can be used for temporomandibular joint MRI.

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Evaluation of Image Quality of a 32-Channel versus a 12-Channel Head Coil at 1.5T for MR Imaging of the Brain

American Journal of Neuroradiology ◽

10.3174/ajnr.a2297 ◽

2010 ◽

Vol 32 (2) ◽

pp. 365-373 ◽

Cited By ~ 25

Author(s):

P.T. Parikh ◽

G.S. Sandhu ◽

K.A. Blackham ◽

M.D. Coffey ◽

D. Hsu ◽

...

Keyword(s):

Image Quality ◽

Mr Imaging ◽

The Brain ◽

Head Coil

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Single-shot fast spin-echo diffusion tensor imaging of the brain and spine with head and phased array coils at 1.5 T and 3.0 T

Magnetic Resonance Imaging ◽

10.1016/j.mri.2004.01.075 ◽

2004 ◽

Vol 22 (6) ◽

pp. 751-759 ◽

Cited By ~ 35

Author(s):

Duan Xu ◽

Roland G Henry ◽

Pratik Mukherjee ◽

Lucas Carvajal ◽

Steven P Miller ◽

...

Keyword(s):

Phased Array ◽

Diffusion Tensor ◽

Spin Echo ◽

Fast Spin Echo ◽

Single Shot ◽

3.0 T ◽

Phased Array Coils ◽

The Brain ◽

Fast Spin ◽

Array Coils

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Capacitive versus Overlap Decoupling of Adjacent Radio Frequency Phased Array Coil Elements: An Imaging Robustness Comparison When Sample Load Varies for 3 Tesla MRI

Concepts in Magnetic Resonance Part B Magnetic Resonance Engineering ◽

10.1155/2020/8828047 ◽

2020 ◽

Vol 2020 ◽

pp. 1-14

Author(s):

Michael J. Beck ◽

Dennis L. Parker ◽

J. Rock Hadley

Keyword(s):

Parallel Imaging ◽

Phased Array ◽

Signal To Noise Ratio ◽

Decoupling Method ◽

3 Tesla Mri ◽

Imaging Performance ◽

Factor Maps ◽

Decoupled Method ◽

Array Coil ◽

Selection Of

Phased array (PA) receive coils are built such that coil elements approximate independent antenna behavior. One method of achieving this goal is to use an available decoupling method to decouple adjacent coil elements. The purpose of this work was to compare the relative performance of two decoupling methods as a function of variation in sample load. Two PA receive coils with 5 channels (5-ch) each, equal outer dimensions, and formed on 12 cm diameter cylindrical phantoms of conductivities 0.3, 0.6, and 0.9 S/m were evaluated for relative signal-to-noise ratio (SNR) and parallel imaging performance. They were only tuned and matched to the 0.6 S/m phantom. Simulated and measured axial, sagittal, and coronal 5-ch PA coil SNR ratios were compared by dividing the overlap by the capacitive decoupled coil SNR results. Issues related to the selection of capacitor values for the two decoupling methods were evaluated by taking the ratio of the match and tune capacitors for large and small 2 channel (2-ch) PA coils. The SNR ratios showed that the SNR of the two decoupling methods were very similar. The inverse geometry-factor maps showed similar but better overall parallel imaging performance for the capacitive decoupled method. The quotients for the 2-ch PA coils’ maximum and minimum capacitor value ratios are 3.28 and 1.38 for the large and 3.28 and 2.22 for the small PA. The results of this paper demonstrate that as the sample load varies, the capacitive and overlap decoupling methods are very similar in relative SNR and this similarity continues for parallel imaging performance. Although, for the 5-ch coils studied, the capacitive decoupling method has a slight SNR and parallel imaging advantage and it was noted that the capacitive decoupled coil is more likely to encounter unbuildable PA coil configurations.

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A 16-element phased-array head coil

Magnetic Resonance in Medicine ◽

10.1002/mrm.1910400213 ◽

1998 ◽

Vol 40 (2) ◽

pp. 272-279 ◽

Cited By ~ 57

Author(s):

Jay R. Porter ◽

Steven M. Wright ◽

Arne Reykowski

Keyword(s):

Phased Array ◽

Head Coil

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Safety and Feasibility of Magnetic Resonance Imaging of the Brain at 1.5 Tesla in Patients with Temporary Transmyocardial Pacing Leads

The Thoracic and Cardiovascular Surgeon ◽

10.1055/s-0037-1607331 ◽

2017 ◽

Vol 67 (02) ◽

pp. 086-091 ◽

Cited By ~ 2

Author(s):

Rami Homsi ◽

Fritz Mellert ◽

Roger Luechinger ◽

Daniel Thomas ◽

Jonas Doerner ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Troponin I ◽

Brain Mri ◽

Maximum Temperature ◽

Safe Procedure ◽

Resonance Imaging ◽

The Brain ◽

Head Coil ◽

Pacing Leads

Background Temporary transmyocardial pacing leads (TTPLs) represent an absolute contraindication to magnetic resonance imaging (MRI). The purpose of this study was to evaluate the safety and feasibility of MRI at 1.5 Tesla (T) using a transmit/receive (T/R) head coil in patients with TTPL. Methods TTPLs (220 cm, Osypka TME, Dr. Osypka GmbH, Rheinfelden, Germany) were implanted in a phantom and exposed to conditions of a 1.5 T brain examination using a T/R head coil. Temperature changes at the lead tip were continuously recorded. A total of 28 patients with TTPL and an urgent indication for a brain MRI underwent MRI at 1.5 T with vital sign monitoring. A T/R head coil was used to minimize radiofrequency exposure of the TTPL. Before and immediately after the MRI scan, TTPL lead impedance, pacing capture threshold (PCT), signal slope, and sensing were measured. Serum troponin I was determined before and after MRI to detect thermal myocardial injury. Results In vitro, the maximum temperature increase from radiofrequency-induced heating of the TTPL tip was < 1°C. In vivo, no complications, such as heating sensations, dizziness, unexpected changes in heart rate or rhythm, or other unusual signs or symptoms were observed. No significant changes in the lead impedance, PCT, signal slope, or sensing were recorded. There were no increases of serum troponin I after the MRI examination. Conclusions MRI of the brain may be performed safely at 1.5 T using a T/R head coil in case of an urgent clinical need in patients with TTPL and may be considered a feasible and safe procedure when appropriate precautionary measures are taken.

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