Stimulated echo diffusion weighted imaging of the liver at 3 Tesla

Zhang, Hui; Sun, Aiqi; Li, Hongjun; Saiviroonporn, Pairash; Wu, Ed X.; Guo, Hua

doi:10.1002/mrm.26128

Cited by 17 publications

(26 citation statements)

References 48 publications

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“…Correct position and absence of frank artifacts (i.e. chemical shift artifacts due to SPAIR fat suppression) on all images was verified visually. Prior to texture analysis, ROI contents were normalized between μ ± 3 σ ( μ , grey‐level mean; σ , grey‐level standard deviation).…”

Section: Methodsmentioning

confidence: 94%

Diffusion‐weighted imaging of the abdomen: Impact of b‐values on texture analysis features

et al. 2016

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The purpose of this work was to systematically assess the impact of the b-value on texture analysis in MR diffusion-weighted imaging (DWI) of the abdomen. In eight healthy male volunteers, echo-planar DWI sequences at 16 b-values ranging between 0 and 1000 s/mm were acquired at 3 T. Three different apparent diffusion coefficient (ADC) maps were computed (0, 750/100, 390, 750 s/mm /all b-values). Texture analysis of rectangular regions of interest in the liver, kidney, spleen, pancreas, paraspinal muscle and subcutaneous fat was performed on DW images and the ADC maps, applying 19 features computed from the histogram, grey-level co-occurrence matrix (GLCM) and grey-level run-length matrix (GLRLM). Correlations between b-values and texture features were tested with a linear and an exponential model; the best fit was determined by the smallest sum of squared residuals. Differences between the ADC maps were assessed with an analysis of variance. A Bonferroni-corrected p-value less than 0.008 (=0.05/6) was considered statistically significant. Most GLCM and GLRLM-derived texture features (12-18 per organ) showed significant correlations with the b-value. Four texture features correlated significantly with changing b-values in all organs (p < 0.008). Correlation coefficients varied between 0.7 and 1.0. The best fit varied across different structures, with fat exhibiting mostly exponential (17 features), muscle mostly linear (12 features) and the parenchymatous organs mixed feature alterations. Two GLCM features showed significant variability in the different ADC maps. Several texture features vary systematically in healthy tissues at different b-values, which needs to be taken into account if DWI data with different b-values are analyzed. Histogram and GLRLM-derived texture features are stable on ADC maps computed from different b-values.

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Section: Methodsmentioning

confidence: 94%

Diffusion‐weighted imaging of the abdomen: Impact of b‐values on texture analysis features

et al. 2016

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“…These procedures are time consuming. For many clinical cases and studies, the scan time is limited because the patients are pediatric or elderly, have severe anxiety or other psychiatric conditions, or have difficulty holding their breath . Hence, longer SE or STE scans are not suitable, whereas ISTE is a viable way to increase the SNR in diffusion MRI in these conditions.…”

Section: Discussionmentioning

confidence: 96%

“…To compare the signals of SE, standard STE, and ISTE for sequences with the same time parameters, we replaced the parameters of TE and mixing time ( t m ) with τ 1 and τ 2 . The parameter t m is the time interval between the 2nd and 3rd pulses in an STE sequence . According to the 2 sequences, the TE of SE equals twice the sum of τ 1 and τ 2 , the TE of standard STE equals twice the value of τ 1 , and the t m of standard STE equals twice the value of τ 2 .…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, negligible δ relative to Δ meets the requirements of the DKI model and decreases the blurring in DSI . Therefore, in the case of limited G and δ, increasing Δ is a viable way to retain a high b ‐value but causes severe MR signal loss because of T 2 relaxation decay and is detrimental to the SNR in diffusion measurement . However, not only the calculation of anomalous diffusion parameters of DSI and DKI but also the measurement of diffusive transport across the plasma membrane of living cells requires high SNR in life events .…”

Section: Introductionmentioning

confidence: 99%

“…7,14 Therefore, in the case of limited G and δ, increasing Δ is a viable way to retain a high b-value but causes severe MR signal loss because of T 2 relaxation decay and is detrimental to the SNR in diffusion measurement. [15][16][17] However, not only the calculation of anomalous diffusion parameters of DSI and DKI but also the measurement of diffusive transport across the plasma membrane of living cells requires high SNR in life events. 18 Moreover, radiomics, a novel and powerful method for MRI data analysis, calls for high SNR values in imaging.…”

Section: Introductionmentioning

confidence: 99%

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Improved stimulated echo in diffusion magnetic resonance imaging: introducing a π pulse for SNR enhancement

Cao

Zhang

Wang

et al. 2019

Magnetic Resonance in Med

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Purpose Anomalous diffusion in biological tissues can be examined by diffusion MRI for various applications, including tumor diagnosis and measurement of brain fiber pathways. However, the measurement of anomalous diffusion requires high b‐values for the diffusion gradient in MRI, and current MRI methods cannot provide a high SNR. This study aimed to improve on the standard stimulated echo (STE) to enhance the SNR in diffusion MRI with high b‐values. Methods Because of hardware limitations and human safety considerations, prolonging the diffusion time (Δ) is 1 of the few methods available to realize high b‐values. Here, we propose a new echo mechanism for diffusion MRI to enhance SNRs under long Δ. By introducing a π pulse at the midpoint between 2nd and 3rd π/2 pulses of STE, we refocus the magnetic moment vectors in the longitudinal plane before the third π/2 pulse is applied, which preserves the full echo signals. This sequence was compared with STE and spin echo (SE). Nine Δs were tested in a phantom. Multi b‐values with 2 Δs were tested in a mouse liver, brain, and tumor. Results Compared with STE and SE, the proposed improved STE (ISTE) exhibited an improved SNR in the phantom experiment and improved performance in the in vivo experiments. Conclusion By using the proposed echo mechanism in diffusion MRI, we enhanced the SNR of the images, which enables us to investigate diffusion behavior at higher b‐values and further facilitates the development of quantitative diffusion MRI and radiomics.

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Diffusion‐weighted MRI of the lung at 3T evaluated using echo‐planar‐based and single‐shot turbo spin‐echo‐based acquisition techniques for radiotherapy applications

Tyagi

Cloutier

Zakian

et al. 2018

J Applied Clin Med Phys

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PurposeTo compare single‐shot echo‐planar (SS‐EPI)‐based and turbo spin‐echo (SS‐TSE)‐based diffusion‐weighted imaging (DWI) in Non‐Small Cell Lung Cancer (NSCLC) patients and to characterize the distributions of apparent diffusion coefficient (ADC) values generated by the two techniques.MethodsTen NSCLC patients were enrolled in a prospective IRB‐approved study to compare and optimize DWI using EPI and TSE‐based techniques for radiotherapy planning. The imaging protocol included axial T2w, EPI‐based DWI and TSE‐based DWI on a 3 T Philips scanner. Both EPI‐based and TSE‐based DWI sequences used three b values (0, 400, and 800 s/mm2). The acquisition times for EPI‐based and TSE‐based DWI were 5 and 8 min, respectively. DW‐MR images were manually coregistered with axial T2w images, and tumor volume contoured on T2w images were mapped onto the DWI scans. A pixel‐by‐pixel fit of tumor ADC was calculated based on monoexponential signal behavior. Tumor ADC mean, standard deviation, kurtosis, and skewness were calculated and compared between EPI and TSE‐based DWI. Image distortion and ADC values between the two techniques were also quantified using fieldmap analysis and a NIST traceable ice‐water diffusion phantom, respectively.ResultsThe mean ADC for EPI and TSE‐based DWI were 1.282 ± 0.42 × 10−3 and 1.211 ± 0.31 × 10−3 mm2/s. The average skewness and kurtosis were 0.14 ± 0.4 and 2.43 ± 0.40 for DWI‐EPI and −0.06 ± 0.69 and 2.89 ± 0.62 for DWI‐TSE. Fieldmap analysis showed a mean distortion of 13.72 ± 8.12 mm for GTV for DWI‐EPI and 0.61 ± 0.4 mm for DWI‐TSE. ADC values obtained using the diffusion phantom for the two techniques were within 0.03 × 10−3 mm2/s with respect to each other as well as the established values.ConclusionsDiffusion‐weighted turbo spin‐echo shows better geometrical accuracy compared to DWI‐EPI. Mean ADC values were similar with both acquisitions but the shape of the histograms was different based on the skewness and kurtosis values. The impact of differences in respiratory technique on ADC values requires further investigation.

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Stimulated echo diffusion weighted imaging of the liver at 3 Tesla

Cited by 17 publications

References 48 publications

Diffusion‐weighted imaging of the abdomen: Impact of b‐values on texture analysis features

Diffusion‐weighted imaging of the abdomen: Impact of b‐values on texture analysis features

Improved stimulated echo in diffusion magnetic resonance imaging: introducing a π pulse for SNR enhancement

Diffusion‐weighted MRI of the lung at 3T evaluated using echo‐planar‐based and single‐shot turbo spin‐echo‐based acquisition techniques for radiotherapy applications

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