On the steady-state properties of actual flip angle imaging (AFI).

abstract：PURPOSE:To investigate a computationally efficient method for optimizing the Cramér-Rao Lower Bound (CRLB) of quantitative sequences without using approximations or an analytical expression of the signal. METHODS:Automatic differentiation was applied to Bloch simulations and used to optimize several quantitative seque...

journal_title：Magnetic resonance in medicine

authors： Lee PK,Watkins LE,Anderson TI,Buonincontri G,Hargreaves BA

更新日期：2019-10-01 00:00:00

abstract：:A novel method based on selective detection of rapidly changing DeltaB(0) magnetic fields and suppression of slowly changing DeltaB(0) fields is presented. The ultimate goal of this work is to present a method that may allow detection of transient and subtle changes in B(0) in cortical tissue associated with electrica...

journal_title：Magnetic resonance in medicine

authors： Bodurka J,Bandettini PA

更新日期：2002-06-01 00:00:00

abstract：:A comparison between contrast and signal-to-noise ratio (SNR), as obtained by both maximum entropy (ME) and 2DFT reconstruction, is reported for NMR images. Our results show that in the ME elaboration the contrast and SNR are generally increased with respect to the 2DFT elaboration. The magnitude of such an increase d...

journal_title：Magnetic resonance in medicine

authors： De Simone BC,De Luca F,Maraviglia B

更新日期：1988-11-01 00:00:00

abstract：:Cortical bone in the mature skeleton has a short T(2)* and produces no detectable signal with conventional MR sequences. A two-dimensional ultrashort echo time (UTE) sequence employing half radio frequency (RF) pulse excitations and radial ramp sampling reduces the effective TE to 8 micros and is capable of detecting ...

journal_title：Magnetic resonance in medicine

authors： Du J,Hamilton G,Takahashi A,Bydder M,Chung CB

更新日期：2007-11-01 00:00:00

abstract：:This note considers the anomolous contrast in inversion recovery images produced by NMR scanners if a map of [My] is reconstructed, rather than a map of My'. ...

journal_title：Magnetic resonance in medicine

authors： Young IR,Bailes DR,Bydder GM

更新日期：1985-02-01 00:00:00

abstract：:Rapid MR imaging using the stimulated echo acquisition mode (STEAM) technique yields single-shot images without any sensitivity to resonance offset effects. However, the absence of susceptibility-induced signal voids or geometric distortions is at the expense of a somewhat lower signal-to-noise ratio than EPI. As a co...

journal_title：Magnetic resonance in medicine

authors： Block KT,Frahm J

更新日期：2008-04-01 00:00:00

abstract：:A technique using hyperpolarized (HP) 3He to image the small airways of the lung by using moderate flip angles and a short scanning period during early inspiration is demonstrated. Flip angles (alpha) ranging from 10-90 degrees were used in guinea pig experiments with scanning during the entire inspiration period. A s...

journal_title：Magnetic resonance in medicine

authors： Chen XJ,Chawla MS,Hedlund LW,Möller HE,MacFall JR,Johnson GA

更新日期：1998-01-01 00:00:00

abstract：PURPOSE:Proof-of-concept study of mapping renal blood flow vector field according to the inverse solution to a mass transport model of time resolved tracer-labeled MRI data. THEORY AND METHODS:To determine tissue perfusion according to the underlying physics of spatiotemporal tracer concentration variation, the mass t...

journal_title：Magnetic resonance in medicine

authors： Zhou L,Zhang Q,Spincemaille P,Nguyen TD,Morgan J,Dai W,Li Y,Gupta A,Prince MR,Wang Y

更新日期：2021-04-01 00:00:00

abstract：:In active catheter tracking, small RF coils are attached to the catheter for localization. For interactive catheter steering at vessel branchings, it is necessary to visualize not only a single point near the catheter tip but also the entire shape and orientation of the catheter's distal end. Therefore, a 35-mm-long t...

journal_title：Magnetic resonance in medicine

authors： Zuehlsdorff S,Umathum R,Volz S,Hallscheidt P,Fink C,Semmler W,Bock M

更新日期：2004-07-01 00:00:00

abstract：PURPOSE:Multi-slice radiofrequency (RF) pulses have higher specific absorption rates, more peak RF power, and longer pulse durations than single-slice RF pulses. Gradient field design techniques using a z-gradient array are investigated for exciting multiple slices with a single-band RF pulse. THEORY AND METHODS:Two d...

journal_title：Magnetic resonance in medicine

authors： Ertan K,Taraghinia S,Sadeghi A,Atalar E

更新日期：2018-07-01 00:00:00

abstract：PURPOSE:A multi-turn transmit surface coil design was presented to improve B1 efficiency when used with current source amplification. METHODS:Three different coil designs driven by an on-coil current-mode class-D amplifier with current envelope feedback were tested on the benchtop and through imaging in a 1.5 T scanne...

journal_title：Magnetic resonance in medicine

authors： Gudino N,Griswold MA

更新日期：2013-04-01 00:00:00

abstract：:The purpose of this study was to determine the value of a blood-pool contrast media (NC100150, Nycomed Imaging (now Amersham Health) Oslo, Norway) for evaluation of venous thrombosis of the deep veins of the pelvis and lower extremities. Twelve patients were prospectively evaluated with conventional X-ray venography (...

journal_title：Magnetic resonance in medicine

authors： Aschauer M,Deutschmann HA,Stollberger R,Hausegger KA,Obernosterer A,Schöllnast H,Ebner F

更新日期：2003-11-01 00:00:00

abstract：:Ferumoxytol is an ultrasmall superparamagnetic iron oxide agent marketed for the treatment of anemia. There has been increasing interest in its properties as an MRI contrast agent as well as greater awareness of its adverse event profile. This mini-review summarizes the current state of knowledge of the risks of ferum...

journal_title：Magnetic resonance in medicine

authors： Vasanawala SS,Nguyen KL,Hope MD,Bridges MD,Hope TA,Reeder SB,Bashir MR

更新日期：2016-05-01 00:00:00

abstract：PURPOSE:In diffusion MRI, the actual b-value played out on the scanner may deviate from the nominal value due to magnetic field imperfections. A simple image-based correction method for this problem is presented. METHODS:The apparent diffusion constant (ADC) of a water phantom was measured voxel-wise along 64 diffusio...

journal_title：Magnetic resonance in medicine

authors： Lee Y,Kettinger AO,Wilm BJ,Deichmann R,Weiskopf N,Lambert C,Pruessmann KP,Nagy Z

更新日期：2020-06-01 00:00:00

abstract：PURPOSE:Cross-relaxation of protons with (14) N nuclei in proteins enhances relaxivity in the quadrupolar dip range of typically 2-3 MHz Larmor frequency. The magnitude of these dips was suggested as a means of assessing the degeneracy of articular cartilage during osteoarthritis (OA). However, so far only proteoglycan...

journal_title：Magnetic resonance in medicine

authors： Rössler E,Mattea C,Stapf S

更新日期：2015-05-01 00:00:00

abstract：:Detre et al. (Magn. Reson. Med. 23, 37-45 (1992)) and Zhang et al., (Magn. Reson. Med. 25, 362 (1992)) have recently demonstrated a technique for the measurement of regional cerebral blood flow (rCBF) based on the continuous saturation (or inversion) of the arterial blood supply to the brain in rats at 4.7 T. In the w...

journal_title：Magnetic resonance in medicine

authors： Walsh EG,Minematsu K,Leppo J,Moore SC

更新日期：1994-02-01 00:00:00

abstract：:For in vivo magnetic resonance imaging at high field (> or =3 T) it is essential to consider the homogeneity of the active B(1) field (B(1)+), particularly if surface coils are used for RF transmission. A new method is presented for highly rapid B(1)+ magnitude mapping. It combines the double angle method with a B(1)-...

journal_title：Magnetic resonance in medicine

authors： Cunningham CH,Pauly JM,Nayak KS

更新日期：2006-06-01 00:00:00

abstract：:The potential of quantitative parameter images of the relaxation times T1 and T2, the proton density rho and the apparent diffusion coefficient (ADC) to characterize three different experimental rat brain tumors (F98 glioma, RN6 Schwannoma, and E376 neuroblastoma) was studied. All parameter values, as determined in hi...

journal_title：Magnetic resonance in medicine

authors： Eis M,Els T,Hoehn-Berlage M

更新日期：1995-12-01 00:00:00

abstract：:Human intervertebral discs were investigated by 1H NMR in vitro. The measured parameters of samples differently located in discs give the "maps" of discs. The spin-lattice relaxation-time maps show similar structure to dry matter and bound water maps, which might mean the future possibility to detect certain disc proc...

journal_title：Magnetic resonance in medicine

authors： Furó I,Bobest M,Pócsik I,Tompa K

更新日期：1986-02-01 00:00:00

abstract：PURPOSE:Because of short signal lifetimes and respiratory motion, 3D lung MRI is still challenging today. Zero-TE (ZTE) pulse sequences offer promising solutions as they overcome the issue of short T 2 ∗ ...

journal_title：Magnetic resonance in medicine

authors： Boucneau T,Fernandez B,Besson FL,Menini A,Wiesinger F,Durand E,Caramella C,Darrasse L,Maître X

更新日期：2021-02-01 00:00:00

abstract：:The radial trajectory has found applications in cardiac imaging because of its resilience to undersampling and motion artifacts. Recent work has shown that interleaved and weighted radial imaging can produce images with multiple contrasts from a single data set. This feature was investigated for inversion recovery ima...

journal_title：Magnetic resonance in medicine

authors： Peters DC,Botnar RM,Kissinger KV,Yeon SB,Appelbaum EA,Manning WJ

更新日期：2006-05-01 00:00:00

abstract：PURPOSE:To demonstrate the feasibility of imaging a bolus of co-polarized [1-13 C]pyruvate and 13 C-urea to simultaneously assess both metabolism and perfusion in the rodent heart. METHODS:Copolarized [1-13 C]pyruvate and 13 C-urea was imaged using a multi-echo, flow-sensitized spiral pulse sequence. Healthy rats were...

journal_title：Magnetic resonance in medicine

authors： Lau AZ,Miller JJ,Robson MD,Tyler DJ

更新日期：2017-01-01 00:00:00

abstract：:Rapid flow imaging was achieved with a partial field of view (pFOV) spiral motion-encoded technique. The FOV and the acquisition time were reduced by a factor of 2 by undersampling k-space. The pFOV spiral k-space trajectory aliased signals from outside a circular ring whose radius was inversely proportional to the di...

journal_title：Magnetic resonance in medicine

authors： Nezafat R,Thompson RB,Derbyshire JA,McVeigh ER

更新日期：2006-09-01 00:00:00

abstract：PURPOSE:To develop a fast and accurate method for 3D T2 mapping of prostate cancer using undersampled acquisition and dictionary-based fitting. METHODS:3D high-resolution T2 -weighted images (0.9 × 0.9 × 3 mm3 ) were obtained with a multishot T2 -prepared balanced steady-state free precession (T2 -prep-bSSFP) acquisit...

journal_title：Magnetic resonance in medicine

authors： Roccia E,Vidya Shankar R,Neji R,Cruz G,Munoz C,Botnar R,Goh V,Prieto C,Dregely I

更新日期：2019-03-01 00:00:00

abstract：PURPOSE:To develop a rapid and motion-robust technique for volumetric MRI, which is based on cross-sectional real-time MRI acquisitions with automatic advancement of the slice position. METHODS:Real-time MRI with a frame-by-frame moving cross-section is performed with use of highly undersampled radial gradient-echo se...

journal_title：Magnetic resonance in medicine

authors： Voit D,Kalentev O,van Zalk M,Joseph AA,Frahm J

更新日期：2020-05-01 00:00:00

abstract：PURPOSE:To investigate four-dimensional flow denoising using the divergence-free wavelet (DFW) transform and compare its performance with existing techniques. THEORY AND METHODS:DFW is a vector-wavelet that provides a sparse representation of flow in a generally divergence-free field and can be used to enforce "soft" ...

journal_title：Magnetic resonance in medicine

authors： Ong F,Uecker M,Tariq U,Hsiao A,Alley MT,Vasanawala SS,Lustig M

更新日期：2015-02-01 00:00:00

abstract：:Images of hyperpolarized 3He were acquired during breath-hold in four healthy volunteers with the use of an optimized 3D gradient-echo sequence. The images were compared with existing 2D gradient-echo methods. The average SNR from a 13-mm-thick slice in the peripheral lung was 1.4 times greater with 3D. In the airways...

journal_title：Magnetic resonance in medicine

authors： Wild JM,Woodhouse N,Paley MN,Fichele S,Said Z,Kasuboski L,van Beek EJ

更新日期：2004-09-01 00:00:00

abstract：:A 3.0 Tesla, 0.80-m bore magnet replaced our previous 1.9 Tesla, 0.76-m magnet. The 3.0 Tesla replacement magnet had a dipole moment of 1.7 with respect to that of the 1.9 Tesla magnet. The pre-existing cylindrically symmetric passive steel shielding was modified to confine the fringe fields of the replacement magnet ...

journal_title：Magnetic resonance in medicine

authors： Ewing JR,Warner R,Helpern JA

更新日期：1993-03-01 00:00:00

abstract：PURPOSE:This study aimed to evaluate the reproducibility and specificity of quantitative magnetization transfer (qMT) imaging for monitoring spinal cord injuries (SCIs). METHODS:MRI scans were performed in anesthetized monkeys at 9.4T, before and serially after a unilateral lesion of the cervical spinal cord. A two-po...

journal_title：Magnetic resonance in medicine

authors： Wang F,Li K,Mishra A,Gochberg D,Min Chen L,Gore JC

更新日期：2016-04-01 00:00:00

abstract：PURPOSE:We investigated global specific absorption rate (SAR) and radiofrequency (RF) power requirements in parallel transmission as the distance between the transmit coils and the sample was increased. METHODS:We calculated ultimate intrinsic SAR (UISAR), which depends on object geometry and electrical properties but...

journal_title：Magnetic resonance in medicine

authors： Deniz CM,Vaidya MV,Sodickson DK,Lattanzi R

更新日期：2016-01-01 00:00:00