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Synthetic mri

Goran Abdula, Jannike Nickander, Peder Sörensson, Magnus Lundin, Peter Kellman, Andreas Sigfridsson, Martin Ugander
OBJECTIVES: Late gadolinium enhancement (LGE) is the in vivo reference standard for assessing focal myocardial fibrosis. Post-contrast T1-mapping by Modified Look-Locker Inversion recovery (MOLLI) can be used to generate synthetic late gadolinium enhancement (SynLGE) images with an image contrast similar to conventional LGE images. We hypothesized that SynLGE has an accuracy that approaches conventional LGE for diagnosing focal myocardial fibrosis. METHODS: Consecutive patients (n = 109, mean ± SD age 50 ± 16 years, 63% male) referred for clinical cardiac magnetic resonance imaging underwent LGE and post-contrast MOLLI starting 10-15 and 20-25 minutes post contrast, respectively...
March 16, 2018: Scandinavian Cardiovascular Journal: SCJ
Pádraig Egan, Susan Murphy, Jelena Jovanovik, Russell Tucker, Noel Fitzpatrick
OBJECTIVE:  This article aimed to describe the use and evolution of a synthetic osteochondral resurfacing (SOR) implant in the treatment of osteochondrosis dissecans (OCD) of the femoral condyle and to report the clinical, radiographic, computed tomography and magnetic resonance imaging outcomes of this technique. METHODS:  Medical records of dogs that were treated with first-generation (G1) and second-generation (G2) SOR at a single institute were reviewed...
February 2018: Veterinary and Comparative Orthopaedics and Traumatology: V.C.O.T
Thais Roque, Laurent Risser, Veerle Kersemans, Sean Smart, Danny Allen, Paul Kinchesh, Stuart Gilchrist, Ana L Gomes, Julia A Schnabel, Michael A Chappell
Predicting tumor growth and its response to therapy remains a major challenge in cancer research and strongly relies on tumor growth models. In this paper, we introduce, calibrate, and verify a novel image-driven reaction-diffusion model of avascular tumor growth. The model allows for proliferation, death and spread of tumor cells, and accounts for nutrient distribution and hypoxia. It is constrained by longitudinal time series of dynamic contrast-enhancement-MRI images. Tumor specific parameters are estimated from two early time points and used to predict the spatio-temporal evolution of the tumor volume and cell densities at later time points...
March 2018: IEEE Transactions on Medical Imaging
Heye Zhang, Zhifan Gao, Lin Xu, Xingjian Yu, Ken C L Wong, Huafeng Liu, Ling Zhuang, Pengcheng Shi
The prominent advantage of meshfree method, is the way to build the representation of computational domain, based on the nodal points without any explicit meshing connectivity. Therefore, meshfree method can conveniently process the numerical computation inside interested domains with large deformation or inhomogeneity. In this paper, we adopt the idea of meshfree representation into cardiac medical image analysis in order to overcome the difficulties caused by large deformation and inhomogeneous materials of the heart...
2018: IEEE Journal of Translational Engineering in Health and Medicine
Jisook Yi, Young Han Lee, Ho-Taek Song, Jin-Suck Suh
Objective: To evaluate the feasibility of synthetic magnetic resonance imaging (MRI) compared to conventional MRI for the diagnosis of internal derangements of the knee at 3T. Materials and Methods: Following Institutional Review Board approval, image sets of conventional and synthetic MRI in 39 patients were included. Two musculoskeletal radiologists compared the image sets and qualitatively analyzed the images. Subjective image quality was assessed using a four-grade scale...
March 2018: Korean Journal of Radiology: Official Journal of the Korean Radiological Society
So Mi Lee, Young Hun Choi, Sun-Kyoung You, Won Kee Lee, Won Hwa Kim, Hye Jung Kim, Sang Yub Lee, Hyejin Cheon
OBJECTIVES: The properties of brain tissue undergo dynamic changes during maturation. T1 relaxation time (T1), T2 relaxation time (T2), and proton density (PD) are now simultaneously quantifiable within a clinically acceptable time, using a synthetic magnetic resonance imaging (MRI) sequence. This study aimed to provide age-specific reference values for T1, T2, and PD in children, using synthetic MRI. MATERIALS AND METHODS: We included 89 children (median age, 18 months; range, 34 weeks of gestational age to 17 years) who underwent quantitative MRI, using a multidynamic, multiecho sequence on 3 T MRI, between December 2015 and November 2016, and had no abnormal MRI/neurologic assessment findings...
April 2018: Investigative Radiology
M Drake-Pérez, B M A Delattre, J Boto, A Fitsiori, K-O Lovblad, S Boudabbous, M I Vargas
BACKGROUND AND PURPOSE: SyMRI is a technique developed to perform quantitative MR imaging. Our aim was to analyze its potential use for measuring relaxation times of normal components of the spine and to compare them with values found in the literature using relaxometry and other techniques. MATERIALS AND METHODS: Thirty-two spine MR imaging studies (10 cervical, 5 dorsal, 17 lumbosacral) were included. A modified multiple-dynamic multiple-echo sequence was added and processed to obtain quantitative T1 (millisecond), T2 (millisecond), and proton density (percentage units [pu]) maps for each patient...
March 1, 2018: AJNR. American Journal of Neuroradiology
Mami Iima, Masako Kataoka, Shotaro Kanao, Makiko Kawai, Natsuko Onishi, Sho Koyasu, Katsutoshi Murata, Akane Ohashi, Rena Sakaguchi, Kaori Togashi
We prospectively examined the variability of non-Gaussian diffusion magnetic resonance imaging (MRI) and intravoxel incoherent motion (IVIM) measurements with different numbers of b-values and excitations in normal breast tissue and breast lesions. Thirteen volunteers and fourteen patients with breast lesions (seven malignant, eight benign; one patient had bilateral lesions) were recruited in this prospective study (approved by the Internal Review Board). Diffusion-weighted MRI was performed with 16 b-values (0-2500 s/mm2 with one number of excitations [NEX]) and five b-values (0-2500 s/mm2, 3 NEX), using a 3T breast MRI...
2018: PloS One
Lipeng Ning, Markus Nilsson, Samo Lasič, Carl-Fredrik Westin, Yogesh Rathi
The rate of water exchange across cell membranes is a parameter of biological interest and can be measured by diffusion magnetic resonance imaging (dMRI). In this work, we investigate a stochastic model for the diffusion-and-exchange of water molecules. This model provides a general solution for the temporal evolution of dMRI signal using any type of gradient waveform, thereby generalizing the signal expressions for the Kärger model. Moreover, we also derive a general nth order cumulant expansion of the dMRI signal accounting for water exchange, which has not been explored in earlier studies...
February 21, 2018: Journal of Chemical Physics
Natsuo Konta, Syuhei Shibukawa, Tomoaki Hakucho, Tomohiko Horie, Makoto Obara
Synthetic MRI can provide proton density (PD), T1 value, T2 value for each pixel by only one data acquisition and can create various contrast-weighted images. The aim of this study is to evaluate the effect on the calculation of the T1 ·T2 value when changing the scan parameters for synthetic MRI. In the phantom study, when changing 1st TE/2nd TE/TR/TSE factor, the effect on the T1 ·T2 value calculated by synthetic MRI was examined. In the volunteer study, the brain was imaged and compared with known T1 ·T2 value...
2018: Nihon Hoshasen Gijutsu Gakkai Zasshi
Jeremy R Manning, Xia Zhu, Theodore L Willke, Rajesh Ranganath, Kimberly Stachenfeld, Uri Hasson, David M Blei, Kenneth A Norman
Recent research shows that the covariance structure of functional magnetic resonance imaging (fMRI) data - commonly described as functional connectivity - can change as a function of the participant's cognitive state (for review see (Turk-Browne, 2013)). Here we present a Bayesian hierarchical matrix factorization model, termed hierarchical topographic factor analysis (HTFA), for efficiently discovering full-brain networks in large multi-subject neuroimaging datasets. HTFA approximates each subject's network by first re-representing each brain image in terms of the activities of a set of localized nodes, and then computing the covariance of the activity time series of these nodes...
February 12, 2018: NeuroImage
Tom Hilbert, Tilman J Sumpf, Elisabeth Weiland, Jens Frahm, Jean-Philippe Thiran, Reto Meuli, Tobias Kober, Gunnar Krueger
BACKGROUND: Quantitative T2 measurements are sensitive to intra- and extracellular water accumulation and myelin loss. Therefore, quantitative T2 promises to be a good biomarker of disease. However, T2 measurements require long acquisition times. PURPOSE: To accelerate T2 quantification and subsequent generation of synthetic T2 -weighted (T2 -w) image contrast for clinical research and routine. To that end, a recently developed model-based approach for rapid T2 and M0 quantification (MARTINI) based on undersampling k-space, was extended by parallel imaging (GRAPPA) to enable high-resolution T2 mapping with access to T2 -w images in less than 2 minutes acquisition time for the entire brain...
February 15, 2018: Journal of Magnetic Resonance Imaging: JMRI
Jonathan Scharff Nielsen, Tim B Dyrby, Henrik Lundell
Molecular diffusion measured with diffusion weighted MRI (DWI) offers a probe for tissue microstructure. However, inferring microstructural properties from conventional DWI data is a complex inverse problem and has to account for heterogeneity in sizes, shapes and orientations of the tissue compartments contained within an imaging voxel. Alternative experimental means for disentangling the signal signatures of such features could provide a stronger link between the data and its interpretation. Double diffusion encoding (DDE) offers the possibility to factor out variation in compartment shapes from orientational dispersion of anisotropic domains by measuring the correlation between diffusivity in multiple directions...
February 13, 2018: Scientific Reports
Kai Zhu, Yanmin Ju, Junjie Xu, Ziyu Yang, Song Gao, Yanglong Hou
Magnetic nanomaterials (MNMs) have attracted significant interest in the past few decades because of their unique properties such as superparamagnetism, which results from the influence of thermal energy on a ferromagnetic nanoparticle. In the superparamagnetic size regime, the moments of nanoparticles fluctuate as a result of thermal energy. To understand the fundamental behavior of superparamagnetism and develop relevant potential applications, various preparation routes have been explored to produce MNMs with desired properties and structures...
February 7, 2018: Accounts of Chemical Research
Manisha Sharma, Kaushik Chandramouli, Louise Curley, Beau Pontre, Keryn Reilly, Jacob Munro, Andrew Hill, Simon Young, Darren Svirskis
Sustained lidocaine release via a thermoresponsive poloxamer-based in situ gelling system has the potential to alleviate pain following knee arthroplasty. A previously developed formulation showed a promising drug release profile in synthetic phosphate-buffered saline (PBS). To support the translation of this formulation, ex vivo characterisation was warranted. This study therefore aimed (1) to modify the previously developed formulation to reduce the burst release, (2) to compare the release behaviour into ex vivo human intra-articular fluid (IAF) and PBS and (3) to determine the formulation spread in an ex vivo human knee using magnetic resonance imaging (MRI)...
February 6, 2018: Drug Delivery and Translational Research
Juha O Ranne, Terho U Kainonen, Lasse L Lempainen, Jussi A Kosola, Sami A Kajander, Pekka T Niemi
BACKGROUND: Several techniques have been introduced to treat acromioclavicular (AC) separation using the semitendinosus tendon as a graft for coracoclavicular (CC) ligament reconstruction. However, the tendon may have been used previously or the patient may not want it harvested. Hence, synthetic tendon transfers have become increasingly popular. METHODS: Five patients with chronic AC separations were treated. A synthetic polyurethane urea tendon graft (Artelon Tissue Reinforcement [ATR]) was chosen for its ability to partially transform into connective tissue...
February 1, 2018: Surgical Innovation
Amir M Owrangi, Peter B Greer, Carri K Glide-Hurst
Over the past decade, the application of magnetic resonance imaging (MRI) has increased, and there is growing evidence to suggest that improvements in the accuracy of target delineation in MRI-guided radiation therapy may improve clinical outcomes in a variety of cancer types. However, some considerations should be recognized including patient motion during image acquisition and geometric accuracy of images. Moreover, MR-compatible immobilization devices need to be used when acquiring images in the treatment position while minimizing patient motion during the scan time...
February 2, 2018: Physics in Medicine and Biology
Zhipeng Yang, Peiyu He, Jiliu Zhou, Xi Wu
Due to the clinical durable scanning time and other physical constraints, the spatial resolution of diffusion-weighted magnetic resonance imaging (DWI) is highly limited. Using a post-processing method to improve the resolution of DWI holds the potential to improve the investigation of smaller white-matter structures and to reduce partial volume effects. In the present study, a novel non-local mean super-resolution method was proposed to increase the spatial resolution of DWI datasets. Based on a non-local strategy, joint information from the adjacent scanning directions was taken advantage of through the implementation of a novel weighting scheme...
January 2018: Experimental and Therapeutic Medicine
Seung Hyun Lee, Young Han Lee, Ho-Taek Song, Jin-Suck Suh
The purpose was to evaluate the feasibility of quantitative MRI T2 mapping based on the quantitative MRI (QRAPMASTER) sequence for the quantitative assessment of knee cartilage. The T2 values from the phantom study showed excellent correlation between the two techniques (r2 = 0.998). The cartilage T2 values exhibited strong correlations (r2 = 0.867-0.982). Quantitative MRI (qMRI) T2 mapping can be used as an alternative to multi-echo T2 mapping, with relatively short scan time.
February 1, 2018: Magnetic Resonance in Medical Sciences: MRMS
Hennadii Madan, Franjo Pernuš, Žiga Špiclin
We present a computational framework to select the most accurate and precise method of measurement of a certain quantity, when there is no access to the true value of the measurand. A typical use case is when several image analysis methods are applied to measure the value of a particular quantitative imaging biomarker from the same images. The accuracy of each measurement method is characterized by systematic error (bias), which is modeled as a polynomial in true values of measurand, and the precision as random error modeled with a Gaussian random variable...
January 1, 2018: Statistical Methods in Medical Research
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