FID-SPI pulse sequence for quantitative MRI of fluids in porous media

Marica, Florea; Goora, Frédéric G.; Balcom, Bruce J.

doi:10.1016/j.jmr.2014.01.003

Cited by 10 publications

(8 citation statements)

References 16 publications

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“…Therefore, this uncertainty will be propagated to the output of the gradient amplifier and will directly impact the magnetic field gradient waveform as experienced by the sample. The uncertainty of the pre‐equalized gradient waveform applied for an experiment (such as FID‐SPI ) will remain identical to that of the initial MFGM measurement employed to characterize the system. For example, the uncertainty of a pre‐equalized gradient waveform based on a MFGM measurement with 64 scans is identical to that of the MFGM measurement (which is 0.42% as shown in Table ).…”

Section: Resultsmentioning

confidence: 99%

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Accuracy of the Magnetic Field Gradient Waveform Monitor Technique and Consequent Accuracy of Pre‐Equalized Gradient Waveform

Goora

Balcom

2016

Concepts Magn Reson

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The magnetic field gradient waveform monitor (MFGM) technique permits characterization of the temporal evolution of magnetic field gradients in magnetic resonance (MR) instruments (MRIs). Knowledge of the gradient waveform performance permits the development of further techniques, such as gradient waveform pre‐equalization, that correct and optimize gradient waveform distortions due to eddy currents induced during the application of switched magnetic fields and other system limitations. The accuracy of the MFGM technique is important since the overall uncertainty of the gradient waveform measurement will propagate into an uncertainty in corrected gradient waveforms impacting the precision of the resulting MR/MRI measurements. The accuracy of MFGM is investigated through a treatment of the noise present in a MRI. A noisy receiver model provides the basis for characterization of the noise and permits examination of the overall impact of noise on the phase accumulated in a pure‐phase encoded MR signal. Ultimately, a relationship between the signal‐to‐noise ratio of a measurement and the corresponding MFGM uncertainty is developed. The theoretical development is supported through simulation in conjunction with experimental results. The propagation of uncertainties to gradient waveform pre‐equalization is also discussed.

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Section: Resultsmentioning

confidence: 99%

“…Nevertheless, large‐scale gradient distortions may be measured and corrected when MFGM and pre‐equalization techniques are employed . Alternative field correction approaches such as MFM or k‐space trajectory approaches are required when higher resolution magnetic field corrections are necessary.…”

Section: Resultsmentioning

confidence: 99%

Accuracy of the Magnetic Field Gradient Waveform Monitor Technique and Consequent Accuracy of Pre‐Equalized Gradient Waveform

Goora

Balcom

2016

Concepts Magn Reson

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“…Besides medical applications such as the imaging of bones, tendons, or certain parts of the brain [ 19 , 20 ], these methods are of high convenience in the geo- and material sciences. Examples are fluid content imaging using SPRITE in rock cores [ 21 , 22 , 23 ] or mortar [ 24 ]. SPRITE is also especially convenient for rapid moisture profiling combined with relaxation time analysis in soil cores [ 25 ].…”

Section: Introductionmentioning

confidence: 99%

Magnetic Resonance Imaging of Water Content and Flow Processes in Natural Soils by Pulse Sequences with Ultrashort Detection

et al. 2021

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Magnetic resonance imaging is a valuable tool for three-dimensional mapping of soil water processes due to its sensitivity to the substance of interest: water. Since conventional gradient- or spin-echo based pulse sequences do not detect rapidly relaxing fractions of water in natural porous media with transverse relaxation times in the millisecond range, pulse sequences with ultrafast detection open a way out. In this work, we compare a spin-echo multislice pulse sequence with ultrashort (UTE) and zero-TE (ZTE) sequences for their suitability to map water content and its changes in 3D in natural soil materials. Longitudinal and transverse relaxation times were found in the ranges around 80 ms and 1 to 50 ms, respectively, so that the spin echo sequence misses larger fractions of water. In contrast, ZTE and UTE could detect all water, if the excitation and detection bandwidths were set sufficiently broad. More precisely, with ZTE we could map water contents down to 0.1 cm3/cm3. Finally, we employed ZTE to monitor the development of film flow in a natural soil core with high temporal resolution. This opens the route for further quantitative imaging of soil water processes.

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“…To improve sensitivity, a number of other SPI methods have been proposed. In free induction decay (FID) SPI, the gradients are switched off during the receiver event, which enables significant improvements in SNR . Hybrid spin‐echo (SE) SPI offers similar SNR advantages .…”

Section: Introductionmentioning

confidence: 99%

“…In free induction decay (FID) SPI, the gradients are switched off during the receiver event, which enables significant improvements in SNR. 15 Hybrid spin-echo (SE) SPI offers similar SNR advantages. 16 So far, these techniques are mainly used for T * 2 or T 2 -weighted and diffusion-weighted imaging.…”

Section: Introductionmentioning

confidence: 99%

Phase‐contrast single‐point imaging with synchronized encoding: a more reliable technique for in vitro flow quantification

Bruschewski

Kolkmannn

John

et al. 2018

Magnetic Resonance in Med

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Purpose The purpose of this study is to provide a standard method for flow velocity measurements with phase‐contrast (PC) MRI. This method can be used for in vitro studies that place high demands on measurement accuracy. Clinically relevant PC MRI techniques can be validated using this method before being applied in vivo. Methods Many motion‐related errors in PC MRI, particularly flow misregistration, depend on the timing of the encoding gradients in the pulse sequence. By synchronizing all encoding gradients and shortening the overall encoding interval, these errors can be significantly reduced. Based on this concept, a single‐point PC MRI method is proposed. Results Flow experiments were conducted in vitro. No considerable errors were found in the velocity data of the proposed method. For comparison, a conventional PC MRI technique showed up to 100% local velocity deviation and up to 35% flow rate deviation in the same experiments. Conclusions With the proposed method, the overall measurement accuracy is significantly increased compared to conventional PC MRI techniques. Due to long acquisition times and high specific absorption rates, this method can only be applied in vitro.

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FID-SPI pulse sequence for quantitative MRI of fluids in porous media

Cited by 10 publications

References 16 publications

Accuracy of the Magnetic Field Gradient Waveform Monitor Technique and Consequent Accuracy of Pre‐Equalized Gradient Waveform

Accuracy of the Magnetic Field Gradient Waveform Monitor Technique and Consequent Accuracy of Pre‐Equalized Gradient Waveform

Magnetic Resonance Imaging of Water Content and Flow Processes in Natural Soils by Pulse Sequences with Ultrashort Detection

Phase‐contrast single‐point imaging with synchronized encoding: a more reliable technique for in vitro flow quantification

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