Magnetic resonance elastography of the pancreas: Measurement reproducibility and relationship with age

Kolipaka, Arunark; Schroeder, Samuel; Mo, Xiaokui; Shah, Zarine K.; Hart, Phil A.; Conwell, Darwin L.

doi:10.1016/j.mri.2017.04.015

Cited by 45 publications

(37 citation statements)

References 33 publications

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“…Directional filtering, along with a Butterworth band pass filter cutoff values of 10‐40 waves/FOV, was performed on the data to remove reflected and longitudinal waves . The filtered data were then processed using a 3D local frequency estimation (LFE) algorithm using MRElab software (Mayo Clinic, Rochester, MN, USA) to generate stiffness maps. 3D LFE was obtained by performing a weighted sum of stiffness map in each encoding direction using first harmonic amplitude.…”

Section: Methodsmentioning

confidence: 99%

“…Magnetic resonance elastography (MRE) is a noninvasive imaging technique that has been used to estimate the stiffness of soft tissues. [11][12][13][14][15][16][17][18][19] MRE is a clinically proven tool to stage liver fibrosis and is currently being investigated as a potential clinical tool to estimate stiffness in other organs such as aorta, 11 heart, 12 brain, 15 pancreas, 16 lungs, 17 intervertebral discs, 18 liver and spleen. 19 Preliminary studies have been conducted using MRE in kidneys to determine stiffness in healthy subjects 3,20,21 and the effect of water intake on renal stiffness.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic resonance elastography‐derived stiffness of the kidneys and its correlation with water perfusion

et al. 2019

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Stiffness plays an important role in diagnosing renal fibrosis. However, kidney stiffness is altered by perfusion changes in many kidney diseases. Therefore, the aim of the current study is to determine the correlation of kidney stiffness with water intake. We hypothesize that kidney stiffness will increase with 1 L of water intake due to increased water perfusion to the kidneys. Additionally, stiffness of the kidneys will correlate with apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values before and after water intake. A 3 T MRI scanner was used to perform magnetic resonance elastography and diffusion tensor imaging of the kidneys on 24 healthy subjects (age range: 22‐66 years) before and after water intake of 1 L. A 3D T1‐weighted bladder scan was also performed to measure bladder volume before and after water intake. A paired t‐test was performed to evaluate the effect of water intake on the stiffness of kidneys, in addition to bladder volume. A Spearman correlation test was performed to determine the association between stiffness, bladder volume, ADC and FA values of both kidneys before and after water intake. The results show a significant increase in stiffness in different regions of the kidney (ie, percentage increase ranged from 3.6% to 7.5%) and bladder volume after water intake (all P < 0.05). A moderate significant negative correlation was observed between change in kidney stiffness and bladder volume (concordance correlation coefficient = ‐0.468, P < 0.05). No significant correlation was observed between stiffness and ADC or FA values before and after water intake in both kidneys (P > 0.05). Water intake caused a significant increase in the stiffness of the kidneys. The negative correlation between the change in kidney stiffness and bladder volume, before and after water intake, indicates higher perfusion pressure in the kidneys, leading to increased stiffness.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetic resonance elastography‐derived stiffness of the kidneys and its correlation with water perfusion

et al. 2019

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“…5 MRE is a phase-contrast (PC) MRI technique that measures stiffness noninvasively in many organs, such as the liver, heart, pancreas, aorta, brain, breast, etc. [11][12][13][14][15][16][17][18][19][20] In MRE, the external motion is synchronized to motion-encoding gradients (MEG) to encode the displacement fields (ie wave images) in the phase of an MR image. These wave images are then processed to obtain the stiffness maps.…”

Section: Introductionmentioning

confidence: 99%

Magnetic resonance elastography of the lungs: A repeatability and reproducibility study

2019

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Lung diseases are one of the leading causes of death worldwide, from which four million people die annually. Lung diseases are associated with changes in the mechanical properties of the lungs. Several studies have shown the feasibility of using magnetic resonance elastography (MRE) to quantify the lungs' shear stiffness. The aim of this study is to investigate the reproducibility and repeatability of lung MRE, and its shear stiffness measurements, obtained using a modified spin echo‐echo planar imaging (SE‐EPI) MRE sequence. In this study, 21 healthy volunteers were scanned twice by repositioning the volunteers to image right lung both at residual volume (RV) and total lung capacity (TLC) to assess the reproducibility of lung shear stiffness measurements. Additionally, 19 out of the 21 volunteers were scanned immediately without moving the volunteers to test the repeatability of the modified SE‐EPI MRE sequence. A paired t‐test was performed to determine the significant difference between stiffness measurements obtained at RV and TLC. Concordance correlation and Bland–Altman's analysis were performed to determine the reproducibility and repeatability of the SE‐EPI MRE‐derived shear stiffness measurements. The SE‐EPI MRE sequence is highly repeatable with a concordance correlation coefficient (CCC) of 0.95 at RV and 0.96 at TLC. Similarly, the stiffness measurements obtained across all volunteers were highly reproducible with a CCC of 0.95 at RV and 0.92 at TLC. The mean shear stiffness of the lung at RV was 0.93 ± 0.22 kPa and at TLC was 1.41 ± 0.41 kPa. TLC showed a significantly higher mean shear stiffness (P = 0.0004) compared with RV. Lung MRE stiffness measurements obtained using the SE‐EPI sequence were reproducible and repeatable, both at RV and TLC. Lung shear stiffness changes across respiratory cycle with significantly higher stiffness at TLC than RV.

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“…[13][14][15][16][17][18][19] Currently, MRE is a diagnostic tool used clinically for staging liver fibrosis. [20][21][22][23][24] MRE is also being evaluated for determining in-vivo stiffness in brain, 25 heart, 14 aorta, 13 pancreas, 26 lungs, 27 intervertebral discs 28 and spleen. 29 Few studies have evaluated renal MRE in healthy humans [30][31][32][33][34] and animals [35][36][37] but these studies have been limited to feasibility.…”

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confidence: 99%

Magnetic Resonance Elastography of kidneys: SE‐EPI MRE reproducibility and its comparison to GRE MRE

et al. 2019

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The purpose of this study is 1) to demonstrate reproducibility of spin echo‐echo planar imaging (SE‐EPI) magnetic resonance elastography (MRE) to estimate kidney stiffness; and 2) to compare SE‐EPI MRE and gradient recalled echo (GRE) MRE‐derived stiffness estimations in various anatomical regions of the kidney. Kidney MRE was performed on 33 healthy subjects (8 for SE‐EPI MRE reproducibility and 25 for comparison with GRE MRE; age range: 22–66 years) in a 3 T MRI scanner. To demonstrate SE‐EPI MRE reproducibility, subjects were scanned for the first scan and then asked to leave the scan room and repositioned again for the second (repeat) scan. Similar set‐up was used for GRE MRE as well. The displacement data was then processed to obtain overall stiffness estimates of the kidney. Concordance correlation analyses were performed to determine SE‐EPI MRE reproducibility and agreement between GRE MRE and SE‐EPI MRE derived stiffness. A high concordance correlation (ρc = 0.95; p‐value<0.0001) was obtained for SE‐EPI MRE reproducibility. Good concordance correlation was observed (ρc = 0.84; p < 0.0001 for both kidneys, ρc = 0.91; p < 0.0001 for right kidney and ρc = 0.78; p < 0.0001 for left kidney) between GRE MRE and SE‐EPI MRE derived stiffness measurements. Paired t‐test results showed that stiffness value of medulla was significantly (p < 0.0001) greater than cortex using SE‐EPI MRE as well as GRE MRE. SE‐EPI MRE was reproducible and good agreement was observed in MRE‐derived stiffness measurements obtained using SE‐EPI and GRE sequences. Therefore, SE‐EPI can be used for kidney MRE applications.

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Magnetic resonance elastography of the pancreas: Measurement reproducibility and relationship with age

Cited by 45 publications

References 33 publications

Magnetic resonance elastography‐derived stiffness of the kidneys and its correlation with water perfusion

Magnetic resonance elastography‐derived stiffness of the kidneys and its correlation with water perfusion

Magnetic resonance elastography of the lungs: A repeatability and reproducibility study

Magnetic Resonance Elastography of kidneys: SE‐EPI MRE reproducibility and its comparison to GRE MRE

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