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https://www.readbyqxmd.com/read/28096269/differentiation-between-radiation-necrosis-and-tumor-progression-using-chemical-exchange-saturation-transfer
#1
Hatef Mehrabian, Kimberly L Desmond, Hany Soliman, Arjun Sahgal, Gregory J Stanisz
PURPOSE: Stereotactic radiosurgery (SRS) is a common treatment used in patients with brain metastases and is associated with high rates of local control, however, at the risk of radiation necrosis. It is difficult to differentiate radiation necrosis from tumor progression using conventional MRI making it a major diagnostic dilemma for practitioners. This prospective study investigated whether chemical exchange saturation transfer (CEST) was able to differentiate these two conditions. MATERIALS & METHODS: Fifteen patients with brain metastases who had been previously treated with SRS were included...
January 17, 2017: Clinical Cancer Research: An Official Journal of the American Association for Cancer Research
https://www.readbyqxmd.com/read/28090588/quantitative-magnetization-transfer-imaging-of-the-breast-at-3-0-t-reproducibility-in-healthy-volunteers
#2
Lori R Arlinghaus, Richard D Dortch, Jennifer G Whisenant, Hakmook Kang, Richard G Abramson, Thomas E Yankeelov
Quantitative magnetization transfer magnetic resonance imaging provides a means for indirectly detecting changes in the macromolecular content of tissue noninvasively. A potential application is the diagnosis and assessment of treatment response in breast cancer; however, before quantitative magnetization transfer imaging can be reliably used in such settings, the technique's reproducibility in healthy breast tissue must be established. Thus, this study aims to establish the reproducibility of the measurement of the macromolecular-to-free water proton pool size ratio (PSR) in healthy fibroglandular (FG) breast tissue...
December 2016: Tomography: a Journal for Imaging Research
https://www.readbyqxmd.com/read/28060254/quantitative-magnetic-resonance-imaging-of-skeletal-muscle-disease
#3
Bruce M Damon, Ke Li, Richard D Dortch, E Brian Welch, Jane H Park, Amanda K W Buck, Theodore F Towse, Mark D Does, Daniel F Gochberg, Nathan D Bryant
Quantitative magnetic resonance imaging (qMRI) describes the development and use of MRI to quantify physical, chemical, and/or biological properties of living systems. Neuromuscular diseases often exhibit a temporally varying, spatially heterogeneous, and multi-faceted pathology. The goal of this protocol is to characterize this pathology using qMRI methods. The MRI acquisition protocol begins with localizer images (used to locate the position of the body and tissue of interest within the MRI system), quality control measurements of relevant magnetic field distributions, and structural imaging for general anatomical characterization...
December 18, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28043954/an-abnormal-periventricular-magnetization-transfer-ratio-gradient-occurs-early-in-multiple-sclerosis
#4
J William L Brown, Matteo Pardini, Wallace J Brownlee, Kryshani Fernando, Rebecca S Samson, Ferran Prados Carrasco, Sebastien Ourselin, Claudia A M Gandini Wheeler-Kingshott, David H Miller, Declan T Chard
In established multiple sclerosis, tissue abnormality-as assessed using magnetization transfer ratio-increases close to the lateral ventricles. We aimed to determine whether or not (i) these changes are present from the earliest clinical stages of multiple sclerosis; (ii) they occur independent of white matter lesions; and (iii) they are associated with subsequent conversion to clinically definite multiple sclerosis and disability. Seventy-one subjects had MRI scanning a median of 4.6 months after a clinically isolated optic neuritis (49 females, mean age 33...
January 2, 2017: Brain: a Journal of Neurology
https://www.readbyqxmd.com/read/28035783/separating-dipolar-and-chemical-exchange-magnetization-transfer-processes-in-1-h-cest
#5
Tairan Yuwen, Ashok Sekhar, Lewis E Kay
An amide (1) H-Chemical Exchange Saturation Transfer (CEST) experiment is presented for studies of conformational exchange in proteins. The approach, exploiting spin-state-selective magnetization transfer, completely suppresses undesired NOE-based dips in CEST profiles so that chemical exchange processes can be studied. The methodology is demonstrated with applications involving proteins that interconvert on the millisecond timescale between major and invisible minor states, and accurate amide (1) H chemical shifts of the minor conformer are obtained in each case...
December 30, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/28025129/myelin-volume-fraction-imaging-with-mri
#6
Kathryn L West, Nathaniel D Kelm, Robert P Carson, Daniel F Gochberg, Kevin C Ess, Mark D Does
MRI is a valuable tool to assess myelin during development and demyelinating disease processes. While multiexponential T2 and quantitative magnetization transfer measures correlate with myelin content, neither provides the total myelin volume fraction. In many cases correlative measures are adequate; but to assess microstructure of myelin, (e.g. calculate the g-ratio using MRI), an accurate measure of myelin volume fraction is imperative. Using a volumetric model of white matter, we relate MRI measures of myelin to absolute measures of myelin volume fraction and compare them to quantitative histology...
December 23, 2016: NeuroImage
https://www.readbyqxmd.com/read/28019018/contrast-mechanisms-associated-with-neuromelanin-mri
#7
Paula Trujillo, Paul E Summers, Emanuele Ferrari, Fabio A Zucca, Michela Sturini, Luca T Mainardi, Sergio Cerutti, Alex K Smith, Seth A Smith, Luigi Zecca, Antonella Costa
PURPOSE: To investigate the physical mechanisms associated with the contrast observed in neuromelanin MRI. METHODS: Phantoms having different concentrations of synthetic melanins with different degrees of iron loading were examined on a 3 Tesla scanner using relaxometry and quantitative magnetization transfer (MT). RESULTS: Concentration-dependent T1 and T2 shortening was most pronounced for the melanin pigment when combined with iron. Metal-free melanin had a negligible effect on the magnetization transfer spectra...
December 26, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28018953/high-resolution-three-dimensional-quantitative-map-of-the-macromolecular-proton-fraction-distribution-in-the-normal-rat-brain
#8
Anna V Naumova, Andrey E Akulov, Marina Yu Khodanovich, Vasily L Yarnykh
The presented dataset provides a normative high-resolution three-dimensional (3D) macromolecular proton fraction (MPF) map of the healthy rat brain in vivo and source images used for its reconstruction. The images were acquired using the protocol described elsewhere (Naumova, et al. High-resolution three-dimensional macromolecular proton fraction mapping for quantitative neuroanatomical imaging of the rodent brain in ultra-high magnetic fields. Neuroimage (2016) doi: 10.1016/j.neuroimage.2016.09.036). The map was reconstructed from three source images with different contrast weightings (proton density, T1, and magnetization transfer) using the single-point algorithm with a synthetic reference image...
February 2017: Data in Brief
https://www.readbyqxmd.com/read/27988876/edaravone-reduces-astrogliosis-and-apoptosis-in-young-rats-with-kaolin-induced-hydrocephalus
#9
Camila Araújo Bernardino Garcia, Carlos Henrique Rocha Catalão, Hélio Rubens Machado, Ivair Matias Júnior, Thais Helena Romeiro, José Eduardo Peixoto-Santos, Marcelo Volpon Santos, Luiza da Silva Lopes
PURPOSE: We investigated the possible neuroprotective effects of the free radical scavenger edaravone in experimental hydrocephalus. METHODS: Seven-day-old Wistar rats were divided into three groups: control group (C), untreated hydrocephalic (H), and hydrocephalic treated with edaravone (EH). The H and EH groups were subjected to hydrocephalus induction by 20% kaolin intracisternal injection. The edaravone (20 mg/kg) was administered daily for 14 days from the induction of hydrocephalus...
December 17, 2016: Child's Nervous System: ChNS: Official Journal of the International Society for Pediatric Neurosurgery
https://www.readbyqxmd.com/read/27982487/magnetization-transfer-swift-mri-consistently-detects-histologically-verified-myelin-loss-in-the-thalamocortical-pathway-after-a-traumatic-brain-injury-in-rat
#10
Lauri Juhani Lehto, Alejandra Sierra, Olli Gröhn
Traumatic brain injury (TBI) is associated with various neurocognitive deficits, and rapid assessment of the damage is potentially important for the prevention and treatment of these deficits. Imaging assessment of mild or moderate damage outside the primary lesion area after TBI, however, remains challenging. Magnetization transfer (MT) has clearly been underutilized in imaging the damage caused by TBI. Here, we applied the MT ratio (MTR) using sweep imaging with Fourier transformation (SWIFT) to study microstructural tissue damage in the thalamocortical pathway outside the primary lesion in a lateral fluid percussion injury rat model of TBI, 5 months after injury...
December 16, 2016: NMR in Biomedicine
https://www.readbyqxmd.com/read/27979793/lower-magnetization-transfer-ratio-in-the-forceps-minor-is-associated-with-poorer-gait-velocity-in-older-adults
#11
S Seiler, L Pirpamer, B Gesierich, E Hofer, M Duering, D Pinter, E Jouvent, F Fazekas, J-F Mangin, H Chabriat, S Ropele, R Schmidt
BACKGROUND AND PURPOSE: Gait disturbances in the elderly are disabling and a major public health issue but are poorly understood. In this multimodal MR imaging study, we used 2 voxel-based analysis methods to assess the voxelwise relationship of magnetization transfer ratio and white matter hyperintensity location with gait velocity in older adults. MATERIALS AND METHODS: We assessed 230 community-dwelling participants of the Austrian Stroke Prevention Family Study...
December 15, 2016: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/27918896/the-physical-mechanism-of-inhomogeneous-magnetization-transfer-mri
#12
Alan P Manning, Kimberley L Chang, Alex L MacKay, Carl A Michal
Inhomogeneous MT (ihMT) is a new magnetic resonance imaging technique that shows promise for myelin selectivity. Materials with a high proportion of lipids, such as white matter tissue, show a reduced intensity in magnetic resonance images acquired with selective prepulses at positive and negative offsets simultaneously compared to images with a single positive or negative offset prepulse of the same power. This effect was initially explained on the basis of hole-burning in inhomogeneously broadened lines of the lipid proton spin system...
January 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/27898701/assessing-white-matter-microstructure-in-brain-regions-with-different-myelin-architecture-using-mri
#13
Samuel Groeschel, Gisela E Hagberg, Thomas Schultz, Dávid Z Balla, Uwe Klose, Till-Karsten Hauser, Thomas Nägele, Oliver Bieri, Thomas Prasloski, Alex L MacKay, Ingeborg Krägeloh-Mann, Klaus Scheffler
OBJECTIVE: We investigate how known differences in myelin architecture between regions along the cortico-spinal tract and frontal white matter (WM) in 19 healthy adolescents are reflected in several quantitative MRI parameters that have been proposed to non-invasively probe WM microstructure. In a clinically feasible scan time, both conventional imaging sequences as well as microstructural MRI parameters were assessed in order to quantitatively characterise WM regions that are known to differ in the thickness of their myelin sheaths, and in the presence of crossing or parallel fibre organisation...
2016: PloS One
https://www.readbyqxmd.com/read/27888839/detection-of-intermolecular-noe-interactions-in-large-protein-complexes
#14
REVIEW
Jacob Anglister, Gautam Srivastava, Fred Naider
Intermolecular NOE interactions are invaluable for structure determination of biomolecular complexes by NMR and they represent the "gold-standard" amongst NMR measurements for characterizing interfaces. These NOEs constitute only a small fraction of the observed NOEs in a complex and are usually weaker than many of the intramolecular NOEs. A number of methods have been developed to remove the intramolecular NOEs that interfere with the identification of intermolecular NOEs. NMR experiments used to observe intermolecular NOE interactions in large protein complexes must cope with the short T2 relaxation time of the protons and heteronuclei in these complexes because they result in severe losses in sensitivity...
November 2016: Progress in Nuclear Magnetic Resonance Spectroscopy
https://www.readbyqxmd.com/read/27886558/optimization-of-sparse-phase-encodings-for-variable-repetition-delay-turbo-spin-echo-tse-t1-measurements-for-preclinical-applications
#15
DongKyu Lee, Sohyun Han, HyungJoon Cho
A variable repetition-delay (TR) spin echo sequence with repeated refocusing pulses, i.e., a variable TR turbo-spin echo (TSE), provides an attractive means of acquiring an accurate T1 map information that is free from gradient echo based artifacts such as magnetic field inhomogeneities particularly for ultra-high field (at 7T and above) preclinical applications. However, the applicability of multi-slice TSE sequences is often limited by signal distortion from T2 relaxation due to echo-train acquisitions for short T2 tissues, inter-slice cross talks and magnetization transfer (MT) from repetitive slice-selective 180° pulse, and extended scan times with multiple TR excitations...
January 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/27885356/magnetization-transfer-and-amide-proton-transfer-mri-of-neonatal-brain-development
#16
Yang Zheng, Xiaoming Wang, Xuna Zhao
Purpose. This study aims to evaluate the process of brain development in neonates using combined amide proton transfer (APT) imaging and conventional magnetization transfer (MT) imaging. Materials and Methods. Case data were reviewed for all patients hospitalized in our institution's neonatal ward. Patients underwent APT and MT imaging (a single protocol) immediately following the routine MR examination. Single-slice APT/MT axial imaging was performed at the level of the basal ganglia. APT and MT ratio (MTR) measurements were performed in multiple brain regions of interest (ROIs)...
2016: BioMed Research International
https://www.readbyqxmd.com/read/27872808/delineation-of-cortical-pathology-in-multiple-sclerosis-using-multi-surface-magnetization-transfer-ratio-imaging
#17
David A Rudko, Mishkin Derakhshan, Josefina Maranzano, Kunio Nakamura, Douglas L Arnold, Sridar Narayanan
The purpose of our study was to evaluate the utility of measurements of cortical surface magnetization transfer ratio (csMTR) on the inner, mid and outer cortical boundaries as clinically accessible biomarkers of cortical gray matter pathology in multiple sclerosis (MS). Twenty-five MS patients and 12 matched controls were recruited from the MS Clinic of the Montreal Neurological Institute. Anatomical and magnetization transfer ratio (MTR) images were acquired using 3 Tesla MRI at baseline and two-year time-points...
2016: NeuroImage: Clinical
https://www.readbyqxmd.com/read/27868234/efficient-31-p-band-inversion-transfer-approach-for-measuring-creatine-kinase-activity-atp-synthesis-and-molecular-dynamics-in-the-human-brain-at-7-t
#18
Jimin Ren, A Dean Sherry, Craig R Malloy
PURPOSE: To develop an efficient (31) P magnetic resonance spectroscopy (MRS) method for measuring creatine kinase (CK) activity, adenosine triphosphate (ATP) synthesis, and motion dynamics in the human brain at 7 Tesla (T). METHODS: Three band inversion modules differing in center frequency were used to induce magnetization transfer (MT) effect in three exchange pathways: (i) CK-mediated reaction PCr → γ-ATP; (ii) de novo ATP synthesis Pi → γ-ATP; and (iii) ATP intramolecular (31) P-(31) P cross-relaxation γ-(α-) ↔ β-ATP...
November 20, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27859618/in-vivo-measurement-of-a-new-source-of-contrast-the-dipolar-relaxation-time-t1d-using-a-modified-inhomogeneous-magnetization-transfer-ihmt-sequence
#19
Gopal Varma, Olivier M Girard, Valentin H Prevost, Aaron K Grant, Guillaume Duhamel, David C Alsop
PURPOSE: This paper describes a technique that can be used in vivo to measure the dipolar relaxation time, T1D , of macromolecular protons contributing to magnetization transfer (MT) in tissues and to produce quantitative T1D maps. THEORY AND METHODS: The technique builds upon the inhomogeneous MT (ihMT) technique that is particularly sensitive to tissue components with long T1D . A standard ihMT experiment was altered to introduce a variable time for switching between positive and negative offset frequencies for RF saturation...
November 17, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/27856800/normal-testes-asymmetry-evaluated-by-apparent-diffusion-coefficient-and-magnetization-transfer-ratio
#20
Athina C Tsili, Alexandra Ntorkou, Dimitrios Giannakis, Nikolaos Sofikitis, Maria I Argyropoulou
BACKGROUND: In humans, the left testis generally hangs lower than the right and the right is larger than the left. Magnetic resonance imaging (MRI) represents an important adjuvant modality in the investigation of testicular diseases. PURPOSE: To assess if normal testes asymmetry is related to apparent diffusion coefficient (ADC) and magnetization transfer ratio (MTR). MATERIAL AND METHODS: The normal testes from 106 men were included. Testicular volume (TV) was calculated by using the ellipsoid formula: length × width × height × 0...
November 17, 2016: Acta Radiologica
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