Clinical applications of dual‐channel transmit MRI: A review

Brink, Wyger M.; Gulani, Vikas; Webb, Andrew

doi:10.1002/jmri.24791

Cited by 33 publications

(26 citation statements)

References 70 publications

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“…All property maps are coregistered, which aids in creating a multiproperty quantitative space for lesion characterization. B 1 inhomogeneity is a well-known problem in 3.0 T imaging and is thus expected to affect the accuracy of relaxation property mapping (15,16,19). While it is less of an issue for MR fingerprinting studies with brain imaging at 1.5 T or 3.0 T, it is well known that large variation in B 1 is expected with abdominal imaging at 3.0 T because of the successfully used to obtain dynamic susceptibility contrast-enhanced perfusion images in the brain (26).…”

Section: Discussionmentioning

confidence: 99%

MR Fingerprinting for Rapid Quantitative Abdominal Imaging

Chen¹,

Jiang²,

Pahwa³

et al. 2016

Radiology

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).q RSNA, 2016 Purpose:To develop a magnetic resonance (MR) "fingerprinting" technique for quantitative abdominal imaging. Materials and Methods:This HIPAA-compliant study had institutional review board approval, and informed consent was obtained from all subjects. To achieve accurate quantification in the presence of marked B 0 and B 1 field inhomogeneities, the MR fingerprinting framework was extended by using a twodimensional fast imaging with steady-state free precession, or FISP, acquisition and a Bloch-Siegert B 1 mapping method. The accuracy of the proposed technique was validated by using agarose phantoms. Quantitative measurements were performed in eight asymptomatic subjects and in six patients with 20 focal liver lesions. A two-tailed Student t test was used to compare the T1 and T2 results in metastatic adenocarcinoma with those in surrounding liver parenchyma and healthy subjects. Results:Phantom experiments showed good agreement with standard methods in T1 and T2 after B 1 correction. In vivo studies demonstrated that quantitative T1, T2, and B 1 maps can be acquired within a breath hold of approximately 19 seconds. T1 and T2 measurements were compatible with those in the literature. Representative values included the following: liver, 745 msec 6 65 (standard deviation) and 31 msec 6 6; renal medulla, 1702 msec 6 205 and 60 msec 6 21; renal cortex, 1314 msec 6 77 and 47 msec 6 10; spleen, 1232 msec 6 92 and 60 msec 6 19; skeletal muscle, 1100 msec 6 59 and 44 msec 6 9; and fat, 253 msec 6 42 and 77 msec 6 16, respectively. T1 and T2 in metastatic adenocarcinoma were 1673 msec 6 331 and 43 msec 6 13, respectively, significantly different from surrounding liver parenchyma relaxation times of 840 msec 6 113 and 28 msec 6 3 (P , .0001 and P , .01) and those in hepatic parenchyma in healthy volunteers (745 msec 6 65 and 31 msec 6 6, P , .0001 and P = .021, respectively). Conclusion:A rapid technique for quantitative abdominal imaging was developed that allows simultaneous quantification of multiple tissue properties within one 19-second breath hold, with measurements comparable to those in published literature.q RSNA, 2016

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Section: Discussionmentioning

confidence: 99%

MR Fingerprinting for Rapid Quantitative Abdominal Imaging

Chen¹,

Jiang²,

Pahwa³

et al. 2016

Radiology

Self Cite

192

228

View full text Add to dashboard Cite

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“…As multi-transmit is becoming more common at very high-field in MRI, 17 each LimeSDR could also act as a transmitter for two coils. The pulse programmer, switches, and LimeSDR boards all fit easily into one compact 19" rack-mount aluminum enclosure.…”

Section: Spectrometer Architecturementioning

confidence: 99%

A low‐cost multi‐channel software‐defined radio‐based NMR spectrometer and ultra‐affordable digital pulse programmer

Michal

2018

Concepts Magn Reson

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In recent years, a new generation of software-defined radio (SDR) products has emerged that are well suited for adaptation for NMR instrumentation. The software and hardware of a new NMR spectrometer console based upon an inexpensive SDR product are described. This device is provided with open-source firmware and drivers which have allowed the customization of its behavior and optimization for use in NMR. In particular, these low-level modifications have allowed for straightforward synchronization of multiple SDR boards with each other and with other devices. Control of other devices is facilitated by a new digital pulse programmer constructed using an inexpensive open-source, widely available microcontroller platform. The strategy used for precise, reproducible synchronization of the different components is described in detail. Representative spectra are presented demonstrating both high-resolution and wide-line spectroscopy with spectral widths up to 50 MHz. K E Y W O R D Sarduino, double-resonance, LimeSDR, quadrature receiver, vector modulator

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“…In addition, the use of multi-channel coils (such as an 8-channel system arranged in two rows positioned in the z-orientation) can help to reduce the required RF power and SAR values [64,[72][73][74][75]. Multi-transmit coils offer reduced power requirement to produce RF field and thus, a decreased SAR value [63][64][65][66][73][74][75][76][77][78].…”

Section: Type Of Rf Transmit Coilmentioning

confidence: 99%

Safety of Simultaneous Scalp or Intracranial EEG during MRI: A Review

Hawsawi

Carmichael²,

Lemieux

2017

Front. Phys.

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Understanding the brain and its activity is one of the great challenges of modern science. Normal brain activity (cognitive processes, etc.) has been extensively studied using electroencephalography (EEG) since the 1930's, in the form of spontaneous fluctuations in rhythms, and patterns, and in a more experimentally-driven approach in the form of event-related potentials (ERPs) allowing us to relate scalp voltage waveforms to brain states and behavior. The use of EEG recorded during functional magnetic resonance imaging (EEG-fMRI) is a more recent development that has become an important tool in clinical neuroscience, for example for the study of epileptic activity. The purpose of this review is to explore the magnetic resonance imaging safety aspects specifically associated with the use of scalp EEG and other brain-implanted electrodes such as intracranial EEG electrodes when they are subjected to the MRI environment. We provide a theoretical overview of the mechanisms at play specifically associated with the presence of EEG equipment connected to the subject in the MR environment, and of the resulting health hazards. This is followed by a survey of the literature on the safety of scalp or invasive EEG-fMRI data acquisitions across field strengths, with emphasis on the practical implications for the safe application of the techniques; in particular, we attempt to summarize the findings in terms of acquisition protocols when possible.

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Clinical applications of dual‐channel transmit MRI: A review

Cited by 33 publications

References 70 publications

MR Fingerprinting for Rapid Quantitative Abdominal Imaging

MR Fingerprinting for Rapid Quantitative Abdominal Imaging

A low‐cost multi‐channel software‐defined radio‐based NMR spectrometer and ultra‐affordable digital pulse programmer

Safety of Simultaneous Scalp or Intracranial EEG during MRI: A Review

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