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ultrashort echo time

Peter Latta, Zenon Starčuk, Marco L H Gruwel, Michael H Weber, Boguslaw Tomanek
MR images are affected by system delays and gradient field imperfections which induce discrepancies between prescribed and actual k-space trajectories. This could be even more critical for non-Cartesian data acquisitions where even a small deviation from the assumed k-space trajectory results in severe image degradation and artifacts. Knowledge of the actual k-space trajectories is therefore crucial and can be incorporated in the reconstruction of high quality non-Cartesian images. A novel MR method for the calibration of actual gradient waveforms was developed using a combination of phase encoding increments and subsequent detection of the exact time point at which the corresponding trajectory is crossing the k-space origin...
October 11, 2016: Magnetic Resonance Imaging
Khadija Sheikh, Fumin Guo, Dante P I Capaldi, Alexei Ouriadov, Rachel L Eddy, Sarah Svenningsen, Grace Parraga
PURPOSE: To develop and assess ultrashort echo-time (UTE) magnetic resonance imaging (MRI) biomarkers of lung function in asthma patients. MATERIALS AND METHODS: Thirty participants including 13 healthy volunteers and 17 asthmatics provided written informed consent to UTE and pulmonary function tests in addition to hyperpolarized-noble-gas 3T MRI and computed tomography (CT) for asthmatics only. The difference in MRI signal-intensity (SI) across four lung volumes (full-expiration, functional-residual-capacity [FRC], FRC+1L, and full-inspiration) was determined on a voxel-by-voxel basis to generate dynamic proton-density (DPD) maps...
October 12, 2016: Journal of Magnetic Resonance Imaging: JMRI
Neville D Gai, Ashkan A Malayeri, David A Bluemke
PURPOSE: To develop and assess a new technique for three-dimensional (3D) full lung T1 and T2* mapping using a single free breathing scan during a clinically feasible time. MATERIALS AND METHODS: A 3D stack of dual-echo ultrashort echo time (UTE) radial acquisition interleaved with and without a WET (water suppression enhanced through T1 effects) saturation pulse was used to map T1 and T2* simultaneously in a single scan. Correction for modulation due to multiple views per segment was derived...
October 11, 2016: Journal of Magnetic Resonance Imaging: JMRI
Hyungseok Jang, Alan B McMillan
PURPOSE: We propose a new gradient measurement technique based on dynamic single-point imaging (SPI), which allows simple, rapid, and robust measurement of k-space trajectory. METHODS: To enable gradient measurement, we utilize the variable field-of-view (FOV) property of dynamic SPI, which is dependent on gradient shape. First, one-dimensional (1D) dynamic SPI data are acquired from a targeted gradient axis, and then relative FOV scaling factors between 1D images or k-spaces at varying encoding times are found...
October 3, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Ericky C A Araujo, N Azzabou, A Vignaud, G Guillot, P G Carlier
PURPOSE: To introduce an ultrashort echo time (UTE) based method for quantitative mapping of short-T2 signals in skeletal muscle (SKM) in the presence of fat, with the aim of monitoring SKM fibrosis. METHODS: From a set of at least five UTE images of the same slice, a long- T2* map, a fat-fraction map, and a map of short-T2 -signal fraction are extracted. The method was validated by numerical simulations and in vitro studies on collagen solutions. Finaly, the method was applied to image the short-T2 signals in the leg of eight healthy volunteers...
October 3, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Marta Tibiletti, Andrea Bianchi, Åsmund Kjørstad, Stefan Wundrak, Detlef Stiller, Volker Rasche
PURPOSE: To investigate retrospective respiratory gating of three-dimensional ultrashort echo time (3D UTE) lung acquisition in free-breathing rats using k-space center self gating signal (DC-SG) and 3D image-based SG (3D-Img-SG). METHODS: Seven rats were investigated with a quasi-random 3D UTE protocol. Low-resolution time-resolved sliding-window images were reconstructed with a 3D golden-angle radial sparse parallel (GRASP) reconstruction to extract a 3D-Img-SG signal, whereas DC-SG was extracted from the center of k-space...
September 23, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Trisha Roy, Garry Liu, Noor Shaikh, Andrew D Dueck, Graham A Wright
PURPOSE: To test and validate magnetic resonance imaging (MRI) sequences for peripheral artery lesion characterization and relate the MRI characteristics to the amount of force required for a guidewire to puncture peripheral chronic total occlusions (CTOs) as a surrogate for immediate failure of endovascular therapy. METHODS: Diseased superficial femoral, popliteal, and tibial artery segments containing 55 atherosclerotic lesions were excised from the amputated limbs of 7 patients with critical limb ischemia...
September 22, 2016: Journal of Endovascular Therapy
Sven Nebelung, Markus Tingart, Thomas Pufe, Christiane Kuhl, Holger Jahr, Daniel Truhn
OBJECTIVES: To evaluate the diagnostic performance of T1, T1ρ, T2, T2*, and UTE-T2* (ultrashort-echo time-enhanced T2*) mapping in the refined graduation of human meniscus degeneration with histology serving as standard-of-reference. MATERIALS AND METHODS: This IRB-approved intra-individual comparative ex vivo study was performed on 24 lateral meniscus body samples obtained from 24 patients undergoing total knee replacement. Samples were assessed on a 3.0-T MRI scanner using inversion-recovery (T1), spin-lock multi-gradient-echo (T1ρ), multi-spin-echo (T2) and multi-gradient-echo (T2* and UTE-T2*) sequences to determine relaxation times of quantitative MRI (qMRI) parameters...
September 17, 2016: Skeletal Radiology
Yasuhiro Fujiwara, Yoshiyuki Muranaka
Three-dimensional time-of-flight magnetic resonance angiography (TOF MRA) has been widely used in clinics. TOF MRA can cause dephasing artifacts, which lead to an intraluminal signal decrease. Silent MRA is a novel imaging technique that uses arterial spin labeling to achieve an ultrashort echo time (uTE), which is expected to decrease these effects and allow for accurate assessment of the flow in blood vessels. This study quantified the accuracy of Silent MRA images for visualizing the turbulent flow in flow-phantom and in vivo studies...
September 8, 2016: Radiological Physics and Technology
Ya-Jun Ma, Hongda Shao, Jiang Du, Eric Y Chang
MRI biomarkers such as T2 , T2 * and T1rho have been widely used, but are confounded by the magic angle effect. The purpose of this study is to investigate the use of the two-dimensional ultrashort echo time magnetization transfer (UTE-MT) sequence for potential magic angle independent MR biomarkers. Magnetization transfer was investigated in cadaveric Achilles tendon samples using the UTE-MT sequence at five MT powers and five frequency offsets ranging from 2 to 50 kHz. The protocol was applied at five sample orientations ranging from 0 to 90° relative to the B0 field...
November 2016: NMR in Biomedicine
David J Roach, Yannick Crémillieux, Robert J Fleck, Alan S Brody, Suraj D Serai, Rhonda D Szczesniak, Stephanie Kerlakian, John P Clancy, Jason C Woods
RATIONALE: Recent advancements in magnetic resonance imaging (MRI) have been made that improve our ability to assess pulmonary structure and function in cystic fibrosis (CF) patients. A non-ionizing imaging modality that can be used as a serial monitoring tool throughout life can positively impact patient care and outcomes. OBJECTIVES: The purpose of this study was to compare a new ultrashort echo-time (UTE) MRI method with computed tomography (CT) as a biomarker of lung structure abnormalities in young children with early CF lung disease...
August 23, 2016: Annals of the American Thoracic Society
Wen Hong, Qun He, Shujuan Fan, Michael Carl, Hongda Shao, Jun Chen, Eric Y Chang, Jiang Du
PURPOSE: To investigate two-dimensional (2D) and three-dimensional (3D) ultrashort echo time (UTE) and 3D magnetization-prepared rapid gradient-echo (MP-RAGE) sequences for the imaging of iron-oxide nanoparticles (IONP). METHODS: The phantoms were composed of tubes filled with different IONP concentrations ranging from 2 to 45 mM. The tubes were fixed in an agarose gel phantom (0.9% by weight). Morphological imaging was performed with 3D MP-RAGE, 2D UTE, 2D adiabatic inversion recovery-prepared UTE (2D IR-UTE), 3D UTE with Cones trajectory (3D Cones), and 3D IR-Cones sequences...
August 6, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Kirill V Kovtunov, Alexey S Romanov, Oleg G Salnikov, Danila A Barskiy, Eduard Y Chekmenev, Igor V Koptyug
(1)H MRI of gases can potentially enable functional lung imaging to probe gas ventilation and other functions. In this work, (1)H MR images of hyperpolarized and thermally polarized propane gas were obtained using UTE (ultrashort echo time) pulse sequence. A 2D image of thermally polarized propane gas with ~0.9×0.9 mm(2) spatial resolution was obtained in less than 2 seconds, demonstrating that even non-hyperpolarized hydrocarbon gases can be successfully utilized for conventional proton MRI. The experiments were also performed with hyperpolarized propane gas and demonstrated acquisition of high-resolution multi-slice FLASH 2D images in ca...
March 2016: Tomography: a Journal for Imaging Research
Andrew D Hahn, Nara S Higano, Laura L Walkup, Robert P Thomen, Xuefeng Cao, Stephanie L Merhar, Jean A Tkach, Jason C Woods, Sean B Fain
PURPOSE: To determine the feasibility of pulmonary magnetic resonance imaging (MRI) of neonatal lung structures enabled by combining two novel technologies: first, a 3D radial ultrashort echo time (UTE) pulse sequence capable of high spatial resolution full-chest imaging in nonsedated quiet-breathing neonates; and second, a unique, small-footprint 1.5T MRI scanner design adapted for neonatal imaging and installed within the neonatal intensive care unit (NICU). MATERIALS AND METHODS: Ten patients underwent MRI within the NICU, in accordance with an approved Institutional Review Board protocol...
July 26, 2016: Journal of Magnetic Resonance Imaging: JMRI
Curtis N Wiens, Nathan S Artz, Hyungseok Jang, Alan B McMillan, Scott B Reeder
PURPOSE: To develop an externally calibrated parallel imaging technique for three-dimensional multispectral imaging (3D-MSI) in the presence of metallic implants. THEORY AND METHODS: A fast, ultrashort echo time (UTE) calibration acquisition is proposed to enable externally calibrated parallel imaging techniques near metallic implants. The proposed calibration acquisition uses a broadband radiofrequency (RF) pulse to excite the off-resonance induced by the metallic implant, fully phase-encoded imaging to prevent in-plane distortions, and UTE to capture rapidly decaying signal...
July 12, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Tim Klasen, Cornelius Faber
OBJECTIVE: Multi-component T2 relaxation allows for assessing the myelin water fraction in nervous tissue, providing a surrogate marker for demyelination. The assessment of the number and distribution of different T2 components for devising exact models of tissue relaxation has been limited by T2 sampling with conventional MR methods. MATERIALS AND METHODS: A T2-prepared UTE sequence was used to assess multicomponent T2 relaxation at 9.4 T of fixed mouse and rat spinal cord samples and of mouse spinal cord in vivo...
July 9, 2016: Magma
Jannick De Tobel, Elke Hillewig, Stephanie Bogaert, Karel Deblaere, Koenraad Verstraete
BACKGROUND: Established dental age estimation methods in subadults study the development of third molar root apices on radiographs. In living individuals however, avoiding ionizing radiation is expedient. Studying dental development with magnetic resonance imaging complies with this requirement, adding the advantage of imaging in three dimensions. AIM: To elaborate the development of an MRI protocol to visualise all third molars for forensic age estimation, with particular attention to the development of the root apex...
June 22, 2016: Annals of Human Biology
Jun Chen, Eric Y Chang, Michael Carl, Yajun Ma, Hongda Shao, Bimin Chen, Zhihong Wu, Jiang Du
PURPOSE: We present three-dimensional ultrashort echo time Cones (3D UTE Cones) techniques for quantification of total water T1 ( T1TW), bound water T1 ( T1BW), and pore water T1 ( T1PW) in vitro and in vivo using a 3 Tesla (T) scanner. METHODS: T1TW, T1BW, and T1PW were measured with three-dimensional (3D) Cones and adiabatic inversion recovery Cone (IR-Cone) sequences. Two-dimensional (2D) nonselective ultrashort echo time (UTE) techniques, including saturation recovery, variable repetition times (TRs), and inversion recovery (IR) preparation approaches were compared with 3D-Cones techniques on bovine cortical bone samples (n = 8)...
June 6, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Karen C Chen, Betty Tran, Reni Biswas, Sheronda Statum, Koichi Masuda, Christine B Chung, Won C Bae
OBJECTIVE: To evaluate ultrashort time to echo (UTE) magnetic resonance (MR) morphology of the cartilaginous endplates (CEP) in cadaveric lumbar spines with bony vertebral endplate (VEP) lesions, to determine inter-reader agreement as well as associations between the CEP morphology and VEP lesions as well as other abnormalities. MATERIALS AND METHODS: MR imaging of cadaveric lumbar spines from 10 donors was performed at 3T using a UTE MR sequence. Two musculoskeletal radiologists identified the location of vertebral endplate lesions in consensus...
September 2016: Skeletal Radiology
Ryan G Price, Joshua P Kim, Weili Zheng, Indrin J Chetty, Carri Glide-Hurst
PURPOSE: The development of synthetic computed tomography (CT) (synCT) derived from magnetic resonance (MR) images supports MR-only treatment planning. We evaluated the accuracy of synCT and synCT-generated digitally reconstructed radiographs (DRRs) relative to CT and determined their performance for image guided radiation therapy (IGRT). METHODS AND MATERIALS: Magnetic resonance simulation (MR-SIM) and CT simulation (CT-SIM) images were acquired of an anthropomorphic skull phantom and 12 patient brain cancer cases...
July 15, 2016: International Journal of Radiation Oncology, Biology, Physics
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