Effects of RF profile on precision of quantitative T2 mapping using dual-echo steady-state acquisition

Wu, Pei Hsin; Cheng, Cheng Chieh; Wu, Ming Long; Chao, Teng‐Chih; Chung, Hsiao Wen; Huang, Teng Yi

doi:10.1016/j.mri.2013.10.002

Cited by 6 publications

(6 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A special attention should be given to slab-selective refocusing profile. 17 Generation of multi-slice dictionaries combined to the fitting of multi-slice experimental data allowed obtainment of a substantial reduction of the inter-slice T 2 variation in phantoms. For the phantoms scanned with a short TR (2 s), such a fitting provided a comparably small CV (0.54%).…”

Section: Discussionmentioning

confidence: 99%

“…In other words, slice interactions may lead to T 2 inter‐slice variability. As a matter of example, it has been recently reported that using a double echo steady‐state sequence, T 2 can vary within a 10% range between the middle and the border slices 17 . For MESE, the concern regarding a potential biasing effect in multi‐slice acquisitions was raised by Watanabe et al, 18 who identified a uniform bias for all slices as a consequence of a MT effect occurring from MPP.…”

Section: Introductionmentioning

confidence: 99%

“…As a matter of example, it has been recently reported that using a double echo steady-state sequence, T 2 can vary within a 10% range between the middle and the border slices. 17 For MESE, the concern regarding a potential biasing effect in multi-slice acquisitions was raised by Watanabe et al, 18 who identified a uniform bias for all slices as a consequence of a MT effect occurring from MPP. However, the effect of a direct MT (or slice cross-talk effect, a direct saturation of the borders of the neighboring slices) on T 2 inter-slice homogeneity has not been studied.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mitigating slice cross‐talk in multi‐slice multi‐echo spin echo T₂ mapping

Brui,

Badrieva,

de Mayenne

et al. 2023

Magnetic Resonance in Med

View full text Add to dashboard Cite

PurposeTo investigate whether a T2 inter‐slice variation could occur when a multi‐slice multi‐echo spin echo (MESE) sequence is used for image acquisition and to propose an enhanced method for reconstructing T2 maps that can effectively address and correct these variations.MethodsBloch simulations were performed accounting for the direct saturation effect to evaluate magnetization changes in multi‐slice 2D MESE sequence. Experimental phantom scans were performed to validate these simulations. An improved version of the dictionary‐based reconstruction approach was proposed, enabling the creation of a multi‐slice dictionary of echo modulation curves (EMC). The corresponding method has been assayed considering inter‐slice T2 variation with phantoms and in lower leg.ResultsExperimental and numerical study illustrate that direct saturation leads to a bias of EMCs. This bias during the T2 maps reconstructions using original single‐slice EMC‐dictionary method led to inter‐slice T2 variation of 2.03% in average coefficient of variation (CV) in agarose phantoms, and up to 2.8% in vivo (for TR = 2 s, slice gap = 0%). A reduction of CV was observed when increasing the gap up to 100% (0.36% in phantoms, and up to 1.5% in vivo) or increasing TR up to 4 s (0.76% in phantoms, and up to 1.9% in vivo). Matching the multi‐slice experimental data with multi‐slice dictionaries provided a reduced CV of 0.54% in phantoms and up to 2.3% in vivo.ConclusionT2 values quantified from multi‐slice MESE images using single‐slice dictionaries are biased. A dedicated multi‐slice EMC method providing the appropriate dictionaries can reduce the inter‐slice T2 variation.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mitigating slice cross‐talk in multi‐slice multi‐echo spin echo T₂ mapping

Brui,

Badrieva,

de Mayenne

et al. 2023

Magnetic Resonance in Med

View full text Add to dashboard Cite

show abstract

“…Applications for knee imaging demonstrated accurate and precise T 2 estimates 4,12 . Recent studies have shown its potential in breast, 13 prostate, 14 and brain 15–17 imaging. This latter application is therefore an interesting prospect as T 2 mapping sequences can be used to monitor multiple cerebral pathologies including dementia, 18 focal epilepsy, 19 ischemia, 20 and multiple or hippocampal sclerosis 21–23 …”

Section: Introductionmentioning

confidence: 99%

Rapid whole brain 3D T₂ mapping respiratory‐resolved Double‐Echo Steady State (DESS) sequence with improved repeatability

Kadalie,

Trotier,

Corbin

et al. 2023

Magnetic Resonance in Med

View full text Add to dashboard Cite

PurposeTo propose a quantitative 3D double‐echo steady‐state (DESS) sequence that offers rapid and repeatable T2 mapping of the human brain using different encoding schemes that account for respiratory B0 variation.MethodsA retrospective self‐gating module was firstly implemented into the standard DESS sequence in order to suppress the respiratory artifact via data binning. A compressed‐sensing trajectory (CS‐DESS) was then optimized to accelerate the acquisition. Finally, a spiral Cartesian encoding (SPICCS‐DESS) was incorporated to further disrupt the coherent respiratory artifact. These different versions were compared to a standard DESS sequence (fully DESS) by assessing the T2 distribution and repeatability in different brain regions of eight volunteers at 3 T.ResultsThe respiratory artifact correction was determined to be optimal when the data was binned into seven respiratory phases. Compared to the fully DESS, T2 distribution was improved for the CS‐DESS and SPICCS‐DESS with interquartile ranges reduced significantly by a factor ranging from 2 to 12 in the caudate, putamen, and thalamus regions. In the gray and white matter areas, average absolute test–retest T2 differences across all volunteers were respectively 3.5 ± 2% and 3.1 ± 2.1% for the SPICCS‐DESS, 4.6 ± 4.6% and 4.9 ± 5.1% for the CS‐DESS, and 15% ± 13% and 7.3 ± 5.6% for the fully DESS. The SPICCS‐DESS sequence's acquisition time could be reduced by half (<4 min) while maintaining its efficient T2 mapping.ConclusionThe respiratory‐resolved SPICCS‐DESS sequence offers rapid, robust, and repeatable 3D T2 mapping of the human brain, which can be especially effective for longitudinal monitoring of cerebral pathologies.

show abstract

“…However, as analyzed in the next section, the NMR signal does not satisfy equation (1) when the slice profile is not uniform. Recent papers have indeed pointed out that the measurement accuracy can be improved significantly with strategies that account for the slice profile inhomogeneity (Iwaoka et al 1987, Deene et al 2000, Parker et al 2001, Deichmann 2005, Wang et al 2006, Siversson et al 2009, Coolen et al 2009, Lebel and Wilman 2010, Cooper et al 2012, Shen 2012, Gras et al 2013, Wu et al 2014. These strategies either formulate improved equations to compute T 1 for pulse sequences that use specific FAs (e.g.…”

Section: Introductionmentioning

confidence: 99%

Flip-angle profile of slice-selective excitation and the measurement of the MR longitudinal relaxation time with steady-state magnetization

Hsu

2015

Phys. Med. Biol.

View full text Add to dashboard Cite

In MRI, the flip angle (FA) of slice-selective excitation is not uniform across the slice-thickness dimension. This work investigates the effect of the non-uniform FA profile on the accuracy of a commonly-used method for the measurement, in which the T1 value, i.e., the longitudinal relaxation time, is determined from the steady-state signals of an equally-spaced RF pulse train. By using the numerical solutions of the Bloch equation, it is shown that, because of the non-uniform FA profile, the outcome of the T1 measurement depends significantly on T1 of the specimen and on the FA and the inter-pulse spacing τ of the pulse train. A new method to restore the accuracy of the T1 measurement is described. Different from the existing approaches, the new method also removes the FA profile effect for the measurement of the FA, which is normally a part of the T1 measurement. In addition, the new method does not involve theoretical modeling, approximation, or modification to the underlying principle of the T1 measurement. An imaging experiment is performed, which shows that the new method can remove the FA-, the τ-, and the T1-dependence and produce T1 measurements in excellent agreement with the ones obtained from a gold standard method (the inversion-recovery method).

show abstract

Effects of RF profile on precision of quantitative T2 mapping using dual-echo steady-state acquisition

Cited by 6 publications

References 15 publications

Mitigating slice cross‐talk in multi‐slice multi‐echo spin echo T₂ mapping

Mitigating slice cross‐talk in multi‐slice multi‐echo spin echo T₂ mapping

Rapid whole brain 3D T₂ mapping respiratory‐resolved Double‐Echo Steady State (DESS) sequence with improved repeatability

Flip-angle profile of slice-selective excitation and the measurement of the MR longitudinal relaxation time with steady-state magnetization

Contact Info

Product

Resources

About

Effects of RF profile on precision of quantitative T2 mapping using dual-echo steady-state acquisition

Cited by 6 publications

References 15 publications

Mitigating slice cross‐talk in multi‐slice multi‐echo spin echo T2 mapping

Mitigating slice cross‐talk in multi‐slice multi‐echo spin echo T2 mapping

Rapid whole brain 3D T2 mapping respiratory‐resolved Double‐Echo Steady State (DESS) sequence with improved repeatability

Flip-angle profile of slice-selective excitation and the measurement of the MR longitudinal relaxation time with steady-state magnetization

Contact Info

Product

Resources

About

Mitigating slice cross‐talk in multi‐slice multi‐echo spin echo T₂ mapping

Mitigating slice cross‐talk in multi‐slice multi‐echo spin echo T₂ mapping

Rapid whole brain 3D T₂ mapping respiratory‐resolved Double‐Echo Steady State (DESS) sequence with improved repeatability