Magnetic Resonance in Medicine最新文献

{"title":"Prospective acceleration of whole-brain CEST imaging by golden-angle view ordering in Cartesian coordinates and joint k-space and image-space parallel imaging (KIPI).","authors":"Tao Zu, Xingwang Yong, Zhechuan Dai, Tongling Jiang, Yi-Cheng Hsu, Shanshan Lu, Yi Zhang","doi":"10.1002/mrm.30375","DOIUrl":"https://doi.org/10.1002/mrm.30375","url":null,"abstract":"<p><strong>Purpose: </strong>To prospectively accelerate whole-brain CEST acquisition by joint k-space and image-space parallel imaging (KIPI) with a proposed golden-angle view ordering technique (GAVOT) in Cartesian coordinates.</p><p><strong>Theory and methods: </strong>The T₂-decay effect will vary across frames with variable acceleration factors (AF) in the prospective acquisition using sequences with long echo trains. The GAVOT method uses a subset strategy to eliminate the T₂-decay inconsistency, where all frames use a subset of shots from the calibration frame to form their k-space view ordering. The golden-angle rule is adapted to ensure uniform k-space coverage for arbitrary AFs in Cartesian coordinates. Phantom and in vivo studies were conducted on a 3 T scanner.</p><p><strong>Results: </strong>The GAVOT view ordering yielded a higher g-factor than conventional uniformly centric ordering, whereas the noise propagation in amide proton transfer (APT) weighted images was similar between different view ordering. Compared to centric ordering, GAVOT successfully eliminated the T₂-decay inconsistency across all frames, resulting in fewer image artifacts for both KIPI and conventional parallel imaging methods. The synergy of GAVOT and KIPI mitigated strong aliasing artifacts and achieved high-quality reconstruction of prospective variable-AF datasets. GAVOT-KIPI reduced the scan time to 2.1 min for whole-brain APT weighted imaging and 4.7 min for quantitative APT signal (APT^#) mapping.</p><p><strong>Conclusion: </strong>GAVOT makes the prospective variable AF strategy flexible and practical, and, in conjunction with KIPI, ensures high-quality reconstruction from highly undersampled data, facilitating the clinical translation of whole-brain CEST imaging.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142751313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time-efficient, high-resolution 3T whole-brain relaxometry using Cartesian 3D MR Spin TomogrAphy in Time-Domain (MR-STAT) with cerebrospinal fluid suppression.","authors":"Hongyan Liu, Edwin Versteeg, Miha Fuderer, Oscar van der Heide, Martin B Schilder, Cornelis A T van den Berg, Alessandro Sbrizzi","doi":"10.1002/mrm.30384","DOIUrl":"https://doi.org/10.1002/mrm.30384","url":null,"abstract":"<p><strong>Purpose: </strong>Current three-dimensional (3D) MR Spin TomogrAphy in Time-Domain (MR-STAT) protocols use transient-state, gradient-spoiled gradient-echo sequences that are prone to cerebrospinal fluid (CSF) pulsation artifacts when applied to the brain. This study aims to develop a 3D MR-STAT protocol for whole-brain relaxometry that overcomes the challenges posed by CSF-induced ghosting artifacts.</p><p><strong>Method: </strong>We optimized the flip-angle train within the Cartesian 3D MR-STAT framework to achieve two objectives: (1) minimization of the noise level in the reconstructed quantitative maps, and (2) reduction of the CSF-to-white-matter signal ratio to suppress CSF-associated pulsation artifacts. The optimized new sequence was tested on a gel/water phantom for accuracy evaluation of the quantitative maps, and on healthy volunteers to explore the effectiveness of the CSF artifact suppression and robustness of the new protocol.</p><p><strong>Results: </strong>An optimized sequence with high parameter-encoding capability and low CSF signal response was proposed and validated in the gel/water phantom experiment. From in vivo experiments with 5 volunteers, the proposed CSF-suppressed sequence produced quantitative maps with no CSF artifacts and showed overall greatly improved image quality compared with the baseline sequence. Statistical analysis indicated low intersubject and interscan variability for quantitative parameters in gray matter and white matter (1.6%-2.4% for T₁ and 2.0%-4.6% for T₂), demonstrating the robustness of the new sequence.</p><p><strong>Conclusion: </strong>We present a new 3D MR-STAT sequence with CSF suppression that effectively eliminates CSF pulsation artifacts. The new sequence ensures consistently high-quality, 1-mm³ whole-brain relaxometry within a rapid 5.5-min scan time.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142751317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single breath-hold volumetric lung imaging at 0.55T using stack-of-spiral (SoS) out-in balanced SSFP.","authors":"Ye Tian, Nam G Lee, Ziwei Zhao, Alison G Wilcox, Jorge J Nieva, Krishna S Nayak","doi":"10.1002/mrm.30386","DOIUrl":"https://doi.org/10.1002/mrm.30386","url":null,"abstract":"<p><strong>Purpose: </strong>To develop a robust single breath-hold approach for volumetric lung imaging at 0.55T.</p><p><strong>Method: </strong>A balanced-SSFP (bSSFP) pulse sequence with 3D stack-of-spiral (SoS) out-in trajectory for volumetric lung imaging at 0.55T was implemented. With 2.7× undersampling, the pulse sequence enables imaging during a 17-s breath-hold. Image reconstruction is performed using 3D SPIRiT and 3D l1-Wavelet regularizations. In two healthy volunteers, single breath-hold SoS out-in bSSFP was compared against stack-of-spiral UTE (spiral UTE) and half-radial dual-echo bSSFP (bSTAR), based on signal intensity (SI), blood-lung parenchyma contrast, and image quality. In six patients with pathologies including lung nodules, fibrosis, emphysema, and air trapping, single breath-hold SoS out-in and bSTAR were compared against low-dose computed tomography (LDCT).</p><p><strong>Results: </strong>SoS out-in bSSFP achieved 2-mm isotropic resolution lung imaging with a single breath-hold duration of 17 s. SoS out-in (2-mm isotropic) provided higher lung parenchyma and blood SI and blood-lung parenchyma contrast compared to spiral UTE (2.4 × 2.4 × 2.5 mm³) and bSTAR (1.6-mm isotropic). When comparing SI normalized by voxel size, SoS out-in has lower lung parenchyma signal, higher blood signal, and a higher blood-lung parenchyma contrast compared to bSTAR. In patients, SoS out-in bSSFP was able to identify lung fibrosis and lung nodules of size 4 and 8 mm, and breath-hold bSTAR was able to identify lung fibrosis and 8 mm nodules.</p><p><strong>Conclusion: </strong>Single breath-hold volumetric lung imaging at 0.55T with 2-mm isotropic spatial resolution is feasible using SoS out-in bSSFP. This approach could be useful for rapid lung disease screening, and in cases where free-breathing respiratory navigated approaches fail.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142751315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effects of maternal flow on placental diffusion-weighted MRI and intravoxel incoherent motion parameters.","authors":"George Jack Hutchinson, Adam Blakey, Nia Jones, Lopa Leach, Neele Dellschaft, Paul Houston, Matthew Hubbard, Reuben O'Dea, Penny Anne Gowland","doi":"10.1002/mrm.30379","DOIUrl":"https://doi.org/10.1002/mrm.30379","url":null,"abstract":"<p><strong>Purpose: </strong>To investigate and explain observed features of the placental DWI signal in healthy and compromised pregnancies using a mathematical model of maternal blood flow.</p><p><strong>Methods: </strong>Thirteen healthy and nine compromised third trimester pregnancies underwent pulse gradient spin echo DWI MRI, with the results compared to MRI data simulated from a 2D mathematical model of maternal blood flow through the placenta. Both sets of data were fitted to an intravoxel incoherent motion (IVIM) model, and a rebound model (defined within text), which described voxels that did not decay monotonically. Both the in vivo and simulated placentas were split into regions of interest (ROIs) to analyze how the signal varies and how IVIM and rebounding parameters change across the placental width.</p><p><strong>Results: </strong>There was good agreement between the in vivo MRI data, and the data simulated from the mathematical model. Both sets of data included voxels showing a rebounding signal and voxels showing fast signal decay focused near the maternal side of the placenta. In vivo we found higher <math> <semantics> <mrow><msub><mi>f</mi> <mtext>IVIM</mtext></msub> </mrow> <annotation>$$ {f}_{IVIM} $$</annotation></semantics> </math> in the uterine wall and near the maternal side of the placenta, with the slow diffusion coefficient <math> <semantics><mrow><mi>D</mi></mrow> <annotation>$$ D $$</annotation></semantics> </math> reduced in all ROIs in compromised pregnancy.</p><p><strong>Conclusion: </strong>A simulation based entirely on maternal blood explains key features observed in placental DWI, indicating the importance of maternal blood flow in interpreting placental MRI data, and providing potential new metrics for understanding changes in compromised placentas.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142751316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D MR elastography at 0.55 T: Concomitant field effects and feasibility.","authors":"Omar Isam Darwish, Pierluigi Di Cio, Ralph Sinkus, Radhouene Neji","doi":"10.1002/mrm.30377","DOIUrl":"https://doi.org/10.1002/mrm.30377","url":null,"abstract":"<p><strong>Purpose: </strong>To demonstrate the feasibility of hepatic 3D MR elastography (MRE) at 0.55 T in healthy volunteers using Hadamard encoding and to study the effects of concomitant fields in the domain of MRE in general.</p><p><strong>Methods: </strong>Concomitant field effects in MRE are assessed using a Taylor series expansion and an encoding scheme is proposed to study the corresponding effects on 3D MRE at 0.55 T in numerical simulations and in phantom experiments. In addition, five healthy volunteers were enrolled and scanned at 60 Hz mechanical excitation with a Hadamard-encoded 3D MRE sequence at 0.55 T and were also scanned with a reference 3D MRE sequence at 3 T for comparison. The retrieved biomechanical parameters were the magnitude of the complex shear modulus (|G*|), the shear wave speed (Cs), and the loss modulus (G″). Comparison of apparent SNR between 3 T and 0.55 T was performed.</p><p><strong>Results: </strong>Theoretical analysis, numerical simulations and phantom experiments demonstrated that the effects of concomitant fields in 3D MRE at 0.55 T are negligible. In the healthy volunteer experiments, the mean values of |G*|, Cs, and G″ in the liver were 2.1 ± 0.3 kPa, 1.5 ± 0.1 m/s, and 0.8 ± 0.1 kPa at 0.55 T, respectively, and 2.0 ± 0.2 kPa, 1.5 ± 0.1 m/s, and 0.9 ± 0.1 kPa at 3 T, respectively. Bland-Altman analysis demonstrated good agreement between the biomechanical parameters retrieved at 0.55 T and 3 T. A 2.1-fold relative apparent SNR decrease was observed in 3D MRE at 0.55 T in comparison with 3 T.</p><p><strong>Conclusion: </strong>Hepatic 3D MRE is feasible at 0.55 T, showing promising initial results in healthy volunteers.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142716482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Proton-free induction decay MRSI at 7 T in the human brain using an egg-shaped modified rosette K-space trajectory.","authors":"Simon Blömer, Lukas Hingerl, Małgorzata Marjańska, Wolfgang Bogner, Stanislav Motyka, Gilbert Hangel, Antoine Klauser, Ovidiu C Andronesi, Bernhard Strasser","doi":"10.1002/mrm.30368","DOIUrl":"10.1002/mrm.30368","url":null,"abstract":"<p><strong>Purpose: </strong>Proton (¹H)-MRSI via spatial-spectral encoding poses high demands on gradient hardware at ultra-high fields and high-resolutions. Rosette trajectories help alleviate these problems, but at reduced SNR-efficiency because of their k-space densities not matching any desired k-space filter. We propose modified rosette trajectories, which more closely match a Hamming filter, and thereby improve SNR performance while still staying within gradient hardware limitations and without prolonging scan time.</p><p><strong>Methods: </strong>Analytical and synthetic simulations were validated with phantom and in vivo measurements at 7 T. The rosette and modified rosette trajectories were measured in five healthy volunteers in 6 min in a 2D slice in the brain. An elliptical phase-encoding sequence was measured in one volunteer in 22 min, and a 3D sequence was measured in one volunteer within 19 min. The SNR per-unit-time, linewidth, Cramer-Rao lower bounds (CRLBs), lipid contamination, and data quality of the proposed modified rosette trajectory were compared to the rosette trajectory.</p><p><strong>Results: </strong>Using the modified rosette trajectories, an improved k-space weighting function was achieved resulting in an SNR per-unit-time increase of up to 12% compared to rosette's and 23% compared to elliptical phase-encoding, dependent on the two additional trajectory parameters. Similar results were achieved for the theoretical SNR calculation based on k-space densities, as well as when using the pseudo-replica method for simulated, in vivo, and phantom data. The CRLBs of γ-aminobutyric acid and N-acetylaspartylglutamate improved non-significantly for the modified rosette trajectory, whereas the linewidths and lipid contamination remained similar.</p><p><strong>Conclusion: </strong>By optimizing the shape of the rosette trajectory, the modified rosette trajectories achieved higher SNR per-unit-time and enhanced data quality at the same scan time.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142682129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time-resolved MR fingerprinting for T₂* signal extraction: MR fingerprinting meets echo planar time-resolved imaging.","authors":"Di Cui, Xiaoxi Liu, Peder E Z Larson, Duan Xu","doi":"10.1002/mrm.30381","DOIUrl":"https://doi.org/10.1002/mrm.30381","url":null,"abstract":"<p><strong>Purpose: </strong>This study leverages the echo planar time-resolved imaging (EPTI) concept in MR fingerprinting (MRF) framework for a new time-resolved MRF (TRMRF) approach, and explores its capability for fast simultaneous quantification of multiple MR parameters including T₁, T₂, T₂*, proton density, off resonance, and B₁ ⁺.</p><p><strong>Methods: </strong>The proposed TRMRF method uses the concept of EPTI to track the signal change along the EPI echo train for T₂* weighting with a k-t Poisson-based sampling order designed for acquisition. A two-dimensional decomposition algorithm was designed for the image reconstruction, enabling fast and precise subspace modeling. The accuracy of proposed method was evaluated by a T₁/T₂ phantom. The feasibility was demonstrated through 5 healthy volunteer brain studies.</p><p><strong>Results: </strong>In the phantom studies, T₁, T₂, and T₂* maps of TRMRF correlated strongly with gold-standard methods. The concordance correlation coefficients are 0.9999, 0.9984 and 0.9978, and R²s are 0.9998, 0.9971, and 0.9983. In the in vivo studies, quantitative maps were acquired with 5 healthy volunteers. TRMRF was demonstrated to have comparable results with spiral MRF and gradient-echo EPTI. TRMRF scans using 16, 10, and 6 s per slice were also evaluated to demonstrate the capability of shorter scan times.</p><p><strong>Conclusion: </strong>A new approach is proposed to exploit the advantage of EPTI in the MRF framework. We demonstrate in phantom and in vivo experiments that T₁, T₂, T₂*, proton density, off resonance, and B₁ ⁺ can be simultaneously quantified within 6 s/slice by TRMRF.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142682131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variable-flip-angle 3D spiral-in-out turbo spin-echo imaging using concomitant gradient compensation and echo reordering at 0.55 T.","authors":"Zhixing Wang, Rajiv Ramasawmy, Ahsan Javed, John P Mugler, Craig H Meyer, Adrienne E Campbell-Washburn","doi":"10.1002/mrm.30380","DOIUrl":"https://doi.org/10.1002/mrm.30380","url":null,"abstract":"<p><strong>Purpose: </strong>To develop single-slab 3D spiral turbo spin echo (spiral SPACE) for 1-mm³ isotropic whole-brain T₂-weighted imaging on a high-performance 0.55T scanner, with high scan efficiency from interleaved spiral-in-out trajectories, variable-flip-angle refocusing radiofrequency (RF) pulses, echo reordering, and concomitant-field compensation.</p><p><strong>Methods: </strong>A stack-of-spirals (in-out waveforms) turbo-spin-echo acquisition was implemented with T₂-weighed contrast. Gradient infidelity was corrected using the gradient impulse response function (GIRF), and concomitant-field compensation was used to correct for phase errors among echoes and during the readout windows. To maintain a long echo train (˜600 ms) within each shot, variable-flip-angle refocusing RF pulses were generated using extended-phase-graph analysis. An echo-reordering scheme provided a smooth signal variation along the echo direction in k-space. Images from spiral SPACE with and without concomitant-field compensation were compared with those from Cartesian SPACE in phantoms and 6 healthy volunteers.</p><p><strong>Results: </strong>Phantom results demonstrated the improved performance of concomitant-field correction via sequence-based modifications and of GIRF-based trajectory estimation. Volunteer data showed that with concomitant-field correction and echo reordering, system imperfection associated image artifacts and blurring were substantially mitigated in spiral SPACE. Compared with Cartesian SPACE, spiral SPACE had an overall 15%-25% signal-to-noise ratio (SNR) improvement in both white matter and gray matter.</p><p><strong>Conclusion: </strong>A 3D spiral-in-out SPACE acquisition with variable-flip-angles, concomitant-field compensation, and echo-reordering was demonstrated at 0.55 T, showing promising gains in SNR, compared with Cartesian SPACE.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142682150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regional changes in cerebral perfusion with age when accounting for changes in gray-matter volume.","authors":"Jian Hu, Martin S Craig, Silvin P Knight, Celine De Looze, James F Meaney, Rose Anne Kenny, Xin Chen, Michael A Chappell","doi":"10.1002/mrm.30376","DOIUrl":"https://doi.org/10.1002/mrm.30376","url":null,"abstract":"<p><strong>Purpose: </strong>One possible contributing factor for cerebral blood flow (CBF) decline in normal aging is the increase in partial volume effects due to brain atrophy, as cortical thinning can exacerbate the contamination of gray-matter (GM) voxels by other tissue types. This work investigates CBF changes in normal aging of a large elderly cohort aged 54 to 84 and how correction for partial volume effects that would accommodate potential changes in GM might affect this.</p><p><strong>Methods: </strong>The study cohort consisted of 474 participants aged 54 to 84 years using pseudo-continuous arterial spin labeling MRI. A volumetric pipeline and a surface-based pipeline were applied to measure global and regional perfusion. Volumetric regions of interest (ROIs) included GM, cerebral white matter, vascular territories, and the brain atlas from the UK Biobank. The cortical parcellation was using Desikan-Killiany atlas. Non-partial volume effect correction (PVEc) and PVEc GM-CBF changes with aging were modeled using linear regressions.</p><p><strong>Results: </strong>Global GM CBF decreased by 0.17 mL/100 g/min per year with aging before PVEc (p < 0.05) and was 0.18 mL/100 g/min after PVEc (p < 0.05). All cortical parcels exhibited CBF decreases with age before PVEc. After PVEc, seven parcels retained decreasing trends. However, GM CBF demonstrated increase with age after PVEc in three parcels.</p><p><strong>Conclusion: </strong>Although decreases in global perfusion are observed with aging before PVEc, perfusion variations appear to be more regionally selective after PVEc. This supports the understanding that variation in cerebral perfusion with age observed with imaging is influenced by regional changes in anatomy that can be accommodated with PVEc, but perfusion variation is still observable even after PVE is accounted for.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142682130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Romer-EPTI: Rotating-view motion-robust super-resolution EPTI for SNR-efficient distortion-free in-vivo mesoscale diffusion MRI and microstructure imaging.","authors":"Zijing Dong, Timothy G Reese, Hong-Hsi Lee, Susie Y Huang, Jonathan R Polimeni, Lawrence L Wald, Fuyixue Wang","doi":"10.1002/mrm.30365","DOIUrl":"10.1002/mrm.30365","url":null,"abstract":"<p><strong>Purpose: </strong>To overcome the major challenges in diffusion MRI (dMRI) acquisition, including limited SNR, distortion/blurring, and susceptibility to motion artifacts.</p><p><strong>Theory and methods: </strong>A novel Romer-EPTI technique is developed to achieve SNR-efficient acquisition while providing distortion-free imaging, minimal spatial blurring, high motion robustness, and simultaneous multi-TE imaging. It introduces a ROtating-view Motion-robust supEr-Resolution technique (Romer) combined with a distortion/blurring-free Echo Planar Time-resolved Imaging (EPTI) readout. Romer enhances SNR through simultaneous multi-thick-slice acquisition with rotating-view encoding, while providing high motion-robustness via a high-fidelity, motion-aware super-resolution reconstruction. Instead of EPI, the in-plane encoding is performed using EPTI readout to prevent geometric distortion, T₂/T₂*-blurring, and importantly, dynamic distortions that could introduce additional blurring/artifacts after super-resolution reconstruction due to combining volumes with inconsistent geometries. This further improves effective spatial resolution and motion robustness. Additional developments include strategies to address slab-boundary artifacts, achieve minimized TE and optimized readout for additional SNR gain, and increase robustness to strong phase variations at high b-values.</p><p><strong>Results: </strong>Using Romer-EPTI, we demonstrated distortion-free whole-brain mesoscale in-vivo dMRI at both 3T (500-μm isotropic [iso] resolution) and 7T (485-μm iso resolution) for the first time. Motion experiments demonstrated the technique's motion robustness and its ability to obtain high-resolution diffusion images in the presence of subject motion. Romer-EPTI also demonstrated high SNR gain and robustness in high b-value (b = 5000 s/mm²) and time-dependent dMRI.</p><p><strong>Conclusion: </strong>The high SNR efficiency, improved image quality, and motion robustness of Romer-EPTI make it a highly efficient acquisition for high-resolution dMRI and microstructure imaging.</p>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142648438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}