Abstract:
PURPOSE:To facilitate assessment of RF power deposition and temperature rise within the breast, we present a method to seamlessly join heterogeneous breast models with standard whole-body models and demonstrate simulations at 7 T. METHODS:Finite-difference time-domain electromagnetic and bioheat simulations are performed to analyze the specific absorption rate (SAR) and temperature rise distributions in 36 Breast Imaging Reporting and Data System (BI-RADS) categorized breast models fused to 2 female whole-body models while transmitting from a 7T breast volume coil. The breast models are uncompressed in the prone position and feature heterogeneous tissue contents; fusion with human models uses affine transformation and the level-set method. RESULTS:The fusion method produces a continuous transient from the chest region to the posterior portion of breast models while preserving the original volume and shape of breast models. Simulation results of both Ella and Hanako models indicate that the maximum local SAR, partial body SAR, and local tissue temperature rise are positively correlated with both breast density and the highest BI-RADS density classification. Additionally, maximum local tissue temperature rise is positively correlated with maximum 10-g SAR values. CONCLUSION:Fibroglandular tissue content plays an important role in the distribution of SAR and temperature rise within breast tissue. The combined body-breast models preserve the integrity of breast models while concurrently exhibiting the loading of whole-body human models. The procedures presented in this simulation study facilitate safety assessments for breast MRI across the population at both clinical and ultrahigh field strengths.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Li X,Rispoli JVdoi
10.1002/mrm.27395subject
Has Abstractpub_date
2019-02-01 00:00:00pages
1307-1321issue
2eissn
0740-3194issn
1522-2594journal_volume
81pub_type
杂志文章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
pub_type: 杂志文章
doi:10.1002/mrm.28078
更新日期:2020-06-01 00:00:00
abstract::The rotationally invariant trace/3 apparent diffusion coefficients (ADC) of N-acetyl aspartate (NAA), creatine and phosphocreatine (tCr), and choline (Cho) were determined using a diffusion-weighted stimulated echo acquisition mode sequence at 3 T in three separate human brain regions, namely the subcortical white mat...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20427
更新日期:2005-05-01 00:00:00
abstract:PURPOSE:To develop the simultaneous acquisition of multiple voxels in localized MR spectroscopy (MRS) using sensitivity encoding, allowing reduced total scan time compared to conventional sequential single voxel (SV) acquisition methods. METHODS:Dual volume localization was used to simultaneously excite voxels in both...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25718
更新日期:2015-09-01 00:00:00
abstract::The incorporation of RF coils into the tips of intravascular devices has been shown to enable the localization of catheters and guidewires under MR guidance. Furthermore, such coils can be used for endoluminal imaging. The long cable required to connect the coil with the scanner input inadvertently acts as a dipole an...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(200004)43:4<615::aid-mrm19
更新日期:2000-04-01 00:00:00
abstract:PURPOSE:Previous work has evaluated the quality of different analytic methods for extracting relaxation times from magnitude imaging data exhibiting Rician noise. However, biexponential analysis of relaxation in tissue, including cartilage, and materials is of increasing interest. We, therefore, analyzed biexponential ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.25111
更新日期:2015-01-01 00:00:00
abstract::The guidance of minimally invasive procedures may become a very important future application of MRI. The guidance of interventions requires images of the anatomy as well as the information of the position of invasive devices used. This paper introduces continuous radial MRI for the simultaneous acquisition of the anat...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910370623
更新日期:1997-06-01 00:00:00
abstract::MnCl(2) was injected intrathecally through the cisterna magna in rats, allowing infusion of divalent manganese ions (Mn(++)) into the CSF space and thence into the brain, without breaking the blood-brain barrier (BBB). Mn(++) uptake and washout dynamics in the brain were measured by serial T(1)-weighted MRI and EPI T(...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.20047
更新日期:2004-05-01 00:00:00
abstract::Phase contrast flow velocity measurements were performed in six healthy volunteers and 30 patients with arteriosclerotic disease. The iliac arteries were investigated in 8 cases and the femoral arteries in 28 cases. In the first 24 patients, 16 evenly distributed data sets were acquired during one cardiac cycle. In th...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910340508
更新日期:1995-11-01 00:00:00
abstract::An optimized multislice data acquisition scheme for phase acquisition of composite echoes (PACE) imaging is presented. This new scheme uses a repetition time equal to the mixing time and an appropriate phase cycling scheme, which allows for more efficient exploitation of all composite echoes. These modifications provi...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(199912)42:6<1089::aid-mrm1
更新日期:1999-12-01 00:00:00
abstract:PURPOSE:Chemical exchange saturation transfer (CEST) MRI has shown promise in tissue characterization in diseases like stroke and tumor. However, in vivo CEST imaging such as amide proton transfer (APT) MRI is challenging because of concomitant factors such as direct water saturation, macromolecular magnetization trans...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26959
更新日期:2017-12-01 00:00:00
abstract::Mumps virus-infected and normal newborn hamster brains were imaged with magnetic resonance (MR) within 24 h after birth and serially scanned. Hydrocephalus developed explosively on Day 6 postinfection and progressed until death occurred soon after Day 10. This study demonstrates the utility of MR in the investigation ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910040611
更新日期:1987-06-01 00:00:00
abstract::It is shown that in vivo measurement of bile water apparent diffusion coefficient (ADC) by diffusion-weighted echo-planar imaging (EPI) in hamster gallbladder is possible providing motion artifact-free ADC values. These ADC values are used to estimate bile viscosity variation induced by normal diets, cholesterol galls...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/1522-2594(200006)43:6<854::aid-mrm11>3.0.c
更新日期:2000-06-01 00:00:00
abstract:PURPOSE:Conventional fat/water separation techniques require that patients hold breath during abdominal acquisitions, which often fails and limits the achievable spatial resolution and anatomic coverage. This work presents a novel approach for free-breathing volumetric fat/water separation. METHODS:Multiecho data are ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26392
更新日期:2017-08-01 00:00:00
abstract::Comparative NMR studies of normal and pathologically altered human stomach tissues were performed on the basis of proton T1 relaxation time measurements in the presence of high external concentrations of relaxation (contrast) agents manganese ethylenediaminetetraacetic acid (Mn-EDTA) and gadolinium diethylenetriaminep...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910150313
更新日期:1990-09-01 00:00:00
abstract::Minimally invasive cardiac surgery requires arresting and emptying of the heart, which compromises visualization of the surgical field. In this feasibility study a novel surgical procedure is demonstrated in which real-time MRI is used to guide the placement of a prosthetic aortic valve in the beating heart via direct...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21044
更新日期:2006-11-01 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
pub_type: 杂志文章
doi:10.1002/mrm.1910390113
更新日期:1998-01-01 00:00:00
abstract::This article introduces a novel method named "Parallel Imaging and Noquist in Tandem" (PINOT) for accelerated image acquisition of cine cardiac magnetic resonance imaging. This method combines two prior information formalisms, the SPACE-RIP implementation of parallel imaging and the Noquist method for reduced-data ima...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22696
更新日期:2011-04-01 00:00:00
abstract:PURPOSE:At high field, T2 -weighted (T2 w) imaging is limited by transmit field inhomogeneity and increased radiofrequency power deposition. In this work, we introduce SAMPA (Slice-selective Adiabatic Magnetization T2 PrepAration) and demonstrate its use for efficient brain T2 w imaging at 7 Tesla (T). METHODS:SAMPA w...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.26067
更新日期:2016-12-01 00:00:00
abstract::Metallic particles have shaped the use of magnetic resonance imaging (MRI) for molecular and cellular imaging. Although these particles have generally been developed for extracellular residence, either as blood pool contrast agents or targeted contrast agents, the coopted use of these particles for intracellular label...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章,评审
doi:10.1002/mrm.25263
更新日期:2015-01-01 00:00:00
abstract::NMRD profiles, the magnetic field dependence of the water proton longitudinal relaxation rates, have been acquired for two new diphosphonate-modified GdDTPA complexes currently under evaluation as relaxation agents for the MRI detection of soft-tissue calcifications. Fresh dilute solutions show profiles identical to t...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910170118
更新日期:1991-01-01 00:00:00
abstract::Reduction of image-to-image signal fluctuations and imaging artifacts is important for fMRI studies. The imaging artifacts caused by respiration, cardiac pulsation, and gross head motion and the suppression of these artifacts have been studied for many years. However, the artifacts caused by eye movement and their eff...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910380407
更新日期:1997-10-01 00:00:00
abstract::Introduction of a Gaussian weighting function into the phase encoding of the spin-echo imaging method via variable tip angle excitation, with concomitant optimization of the recycle delay, is shown to increase the sensitivity of T2-weighted imaging by up to 40%. In addition, the Gibbs artifact associated with sharp bo...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910210216
更新日期:1991-10-01 00:00:00
abstract::In vivo MR spectroscopy (MRS) studies have shown reductions in NAA/Cr levels in patients with severe neurocognitive deficits due to AIDS dementia complex (ADC), also known as neuroAIDS. The relationship between the cellular changes within the brain during neuroAIDS and the role of NAA/Cr as a metabolic marker remains ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21556
更新日期:2008-03-01 00:00:00
abstract::Multislice MR images obtained using a fast spin-echo (FSE) readout are strongly affected by magnetization transfer (MT) effects, which will cause a decrease in the observed longitudinal relaxation times for tissues with a large bound water component. This is pertinent for FSE-based inversion-recovery (IR) sequences, a...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21338
更新日期:2007-10-01 00:00:00
abstract::The myelin sheath, which is wrapped around the axons in the brain, can be affected by many diseases, resulting in cognitive and physical disability. Other work showed water in the myelin sheath has a T2 approximately 15 ms. The current standard technique to estimate the fraction of myelin water in vivo is to collect m...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.10713
更新日期:2004-03-01 00:00:00
abstract:PURPOSE:High-resolution three-dimensional (3D) structural MRI is useful for delineating complex or small structures of the body. However, it requires long acquisition times and high SAR, limiting its clinical use. The purpose of this work is to accelerate the acquisition of high-resolution images by combining compresse...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.27789
更新日期:2019-09-01 00:00:00
abstract::Recovery of the cerebral cortex after 10 min of cardiac arrest was studied in rat using noninvasive MRI techniques. The apparent diffusion coefficient (ADC) of brain water was imaged to document reversal of the metabolic impairment. Perfusion-weighted imaging and blood oxygen level dependent (BOLD) imaging were perfor...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910390516
更新日期:1998-05-01 00:00:00
abstract:PURPOSE:Amide-proton transfer (APT) and amine-water proton exchange (APEX) MRI can be viable to map pH-decreasing ischemic regions. However, their exact contributions are unclear. METHODS:We measured APEX- and APT-weighted magnetization transfer ratio asymmetry (denoted as APEXw and APTw), apparent diffusion coefficie...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24639
更新日期:2014-01-01 00:00:00
abstract::A three-axis uniplanar gradient coil was designed and built to provide order-of-magnitude increases in gradient strength of up to 500 mT/m on the x- and y-axes, and 1000 mT/m for the z-axis at 640 A input over a limited FOV ( approximately 16 cm) for superficial regions, compared to conventional gradient coils, with s...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.21263
更新日期:2007-07-01 00:00:00
abstract::Quantitative 1H MRS to determine cerebral metabolite patterns and MRI to determine CSF flow were applied to 12 patients with ventricular dilation-Group A, cortical atrophy (N = 5); or Group B, hydrocephalus (N = 7)- and in 9 normal controls. While mean brain water (Group A = 80% +/- 6; Group B = 86% +/- 5; normal = 85...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910370317
更新日期:1997-03-01 00:00:00