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Diffusion MRI

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https://www.readbyqxmd.com/read/28330041/retinal-tractography-influence-of-diffusion-acquisition-ocular-laterality-and-ocular-dominance-in-healthy-subjects
#1
Clément Jean, Arnaud Attyé, Sylvie Grand, Augustin Lecler, Christophe Chiquet, Florent Aptel, Laurent Lamalle, Alexandre Krainik
PURPOSE: Exploration of the human retina has never been described with MRI tractography, supposedly because of ocular movement-related artifacts and imaging distortions with EPI diffusion acquisition. In this work, we used track-weighting imaging to assess retinal fascicles. Diffusion acquisition parameters influence was studied and the relationship between variability and ocular laterality and ocular dominance was explored. MATERIALS AND METHODS: Twenty healthy subjects underwent MRI, with retinal tractography calculated with the constrained spherical deconvolution model...
March 2017: Journal of Neuroradiology. Journal de Neuroradiologie
https://www.readbyqxmd.com/read/28330019/facial-nerve-tractography-a-new-tool-to-detect-perineural-invasion-in-parotid-cancers
#2
René-Charles Rouchy, Arnaud Attyé, Irène Troprès, Maud Medici, Adrian Kastler, Christian Righini, Alexandre Krainik
PURPOSE: To determine whether magnetic resonance (MR) tractography of facial nerve (VIIn) is useful to detect perineural invasion in case of parotid cancers. MATERIALS AND METHODS: Thirty patients, aged 18 or over, were enrolled in this prospective study between December 2013 and March 2016 (IRB 5891), with a diagnosis of parotid tumors (15 malignant, 15 benign). They have undergone preoperative MR scans (3.0-T) before surgical management. The parameters of the diffusion-weighted (DW) sequence were b-value of 1000s/mm(2); 32 directions; voxel size: 2mm isotropic; scan time: 9' The post-processing generates whole-neck constrained spherical deconvolution (CSD)-based tractography data and super-resolution track-weighted imaging (TWI) technique...
March 2017: Journal of Neuroradiology. Journal de Neuroradiologie
https://www.readbyqxmd.com/read/28329953/imaging-feature-in-pres-syndrome-report-of-6-cases
#3
H El Mhabrech, S Karma, F Jbeli, M Dakkem, A Kraiem, C Hafsa
OBJECTIVES: Posterior reversible encephalopathy syndrome (PRES) is a rare syndrome. The pathophysiology is poorly understood. Computed tomography (CT) and magnetic resonance imaging (MRI) findings are characteristic of the diagnosis and diffusion weighted image has been also suggested having a prognostic value. We report this unusual neurologic complication of peripartumin except any pre-existent pathology of the pregnancy. MATERIEL AND METHODS: CT, MR findings and relevant clinical data of the patients were retrospectively reviewed on 5 cases between 2011 and 2012 in our radiologic department...
March 2017: Journal of Neuroradiology. Journal de Neuroradiologie
https://www.readbyqxmd.com/read/28329842/magnetic-resonance-imaging-reveals-progressive-brain-injury-in-rats-acutely-intoxicated-with-diisopropylfluorophosphate
#4
Brad A Hobson, Sílvia Sisó, Douglas J Rowland, Danielle J Harvey, Donald A Bruun, Joel R Garbow, Pamela J Lein
Acute intoxication with organophosphates (OPs) can trigger seizures that progress to status epilepticus, and survivors often exhibit chronic neuropathology, cognitive impairment, affective disorders and/or electroencephalographic abnormalities. Understanding how acute injury transitions to persistent neurological sequelae is critical to developing medical countermeasures for mitigating damage following OP-induced seizures. Here, we used in vivo magnetic resonance imaging (MRI) to monitor the spatiotemporal patterns of neuropathology for one month after acute intoxication with diisopropylfluorophosphate (DFP)...
March 7, 2017: Toxicological Sciences: An Official Journal of the Society of Toxicology
https://www.readbyqxmd.com/read/28329104/vascular-cerebral-damage-in-frail-older-adults-the-amimage-study
#5
José Alberto Avila-Funes, Amandine Pelletier, Céline Meillon, Gwénaëlle Catheline, Olivier Periot, Irene Trevin O-Frenk, Magali Gonzalez-Colaço, Jean-François Dartigues, Karine Pérès, Michèle Allard, Bixente Dilharreguy, Hélène Amieva
Background: Frailty has been associated with increased risk of adverse-health related outcomes including cognitive impairment. However, little is know about the pathogenesis relating frailty to cognitive decline. Therefore, the main objective of this study was to investigate the association between vascular cerebral damage and frailty. Methods: Cross-sectional study involving 176 community-dwelling participants aged 67-86 years, participating in the AMImage Study, an ancillary neuro-imaging project of the AMI cohort, a French prospective cohort including older farmers living in rural areas...
January 21, 2017: Journals of Gerontology. Series A, Biological Sciences and Medical Sciences
https://www.readbyqxmd.com/read/28328939/multimodal-mr-imaging-reveals-large-scale-structural-and-functional-connectivity-changes-in-profound-early-blindness
#6
Corinna M Bauer, Gabriella V Hirsch, Lauren Zajac, Bang-Bon Koo, Olivier Collignon, Lotfi B Merabet
In the setting of profound ocular blindness, numerous lines of evidence demonstrate the existence of dramatic anatomical and functional changes within the brain. However, previous studies based on a variety of distinct measures have often provided inconsistent findings. To help reconcile this issue, we used a multimodal magnetic resonance (MR)-based imaging approach to provide complementary structural and functional information regarding this neuroplastic reorganization. This included gray matter structural morphometry, high angular resolution diffusion imaging (HARDI) of white matter connectivity and integrity, and resting state functional connectivity MRI (rsfcMRI) analysis...
2017: PloS One
https://www.readbyqxmd.com/read/28328501/monte-carlo-simulations-of-diffusion-weighted-mri-in-myocardium-validation-and-sensitivity-analysis
#7
Joanne Bates, Darryl McClymont, Irvin Teh, Peter Kohl, Jurgen Schneider, Vicente Grau
A model of cardiac microstructure and diffusion MRI is presented, and compared with experimental data from ex vivo rat hearts. The model includes a simplified representation of individual cells, with physiologically correct cell size and orientation, as well as intra- to extracellular volume ratio. Diffusion MRI is simulated using a Monte Carlo model and realistic MRI sequences. The results show good correspondence between the simulated and experimental MRI signals. Similar patterns are observed in the eigenvalues of the diffusion tensor, the mean diffusivity (MD) and the fractional anisotropy (FA)...
March 10, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28328072/tensor-estimation-for-double-pulsed-diffusional-kurtosis-imaging
#8
Calvin B Shaw, Edward S Hui, Joseph A Helpern, Jens H Jensen
Double-pulsed diffusional kurtosis imaging (DP-DKI) represents the double diffusion encoding (DDE) MRI signal in terms of six-dimensional (6D) diffusion and kurtosis tensors. Here a method for estimating these tensors from experimental data is described. A standard numerical algorithm for tensor estimation from conventional (i.e. single diffusion encoding) diffusional kurtosis imaging (DKI) data is generalized to DP-DKI. This algorithm is based on a weighted least squares (WLS) fit of the signal model to the data combined with constraints designed to minimize unphysical parameter estimates...
March 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28328013/validation-of-surface-to-volume-ratio-measurements-derived-from-oscillating-gradient-spin-echo-on-a-clinical-scanner-using-anisotropic-fiber-phantoms
#9
Gregory Lemberskiy, Steven H Baete, Martijn A Cloos, Dmitry S Novikov, Els Fieremans
A diffusion measurement in the short-time surface-to-volume ratio (S/V) limit (Mitra et al., Phys Rev Lett. 1992;68:3555) can disentangle the free diffusion coefficient from geometric restrictions to diffusion. Biophysical parameters, such as the S/V of tissue membranes, can be used to estimate microscopic length scales non-invasively. However, due to gradient strength limitations on clinical MRI scanners, pulsed gradient spin echo (PGSE) measurements are impractical for probing the S/V limit. To achieve this limit on clinical systems, an oscillating gradient spin echo (OGSE) sequence was developed...
March 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28327949/resection-of-navigated-transcranial-magnetic-stimulation-positive-prerolandic-motor-areas-causes-permanent-impairment-of-motor-function
#10
Tobias Moser, Lucia Bulubas, Jamil Sabih, Neal Conway, Noémie Wildschutz, Nico Sollmann, Bernhard Meyer, Florian Ringel, Sandro M Krieg
BACKGROUND: Navigated transcranial magnetic stimulation (nTMS) helps to determine the distribution of motor eloquent areas prior to brain surgery. Yet, the eloquence of primary motor areas frontal to the precentral gyrus identified via nTMS is unclear. OBJECTIVE: To investigate the resection of nTMS-positive prerolandic motor areas and its correlation with postsurgical impairment of motor function. METHODS: Forty-three patients with rolandic or prerolandic gliomas (WHO grade I-IV) underwent nTMS prior to surgery...
February 24, 2017: Neurosurgery
https://www.readbyqxmd.com/read/28327941/degree-of-vascular-encasement-in-sphenoid-wing-meningiomas-predicts-postoperative-ischemic-complications
#11
D Jay McCracken, Raymond A Higginbotham, Jason H Boulter, Yuan Liu, John A Wells, Sameer H Halani, Amit M Saindane, Nelson M Oyesiku, Daniel L Barrow, Jeffrey J Olson
BACKGROUND: Sphenoid wing meningiomas (SWMs) can encase arteries of the circle of Willis, increasing their susceptibility to intraoperative vascular injury and severe ischemic complications. OBJECTIVE: To demonstrate the effect of circumferential vascular encasement in SWM on postoperative ischemia. METHODS: A retrospective review of 75 patients surgically treated for SWM from 2009 to 2015 was undertaken to determine the degree of circumferential vascular encasement (0°-360°) as assessed by preoperative magnetic resonance imaging (MRI)...
January 28, 2017: Neurosurgery
https://www.readbyqxmd.com/read/28327920/of-bubbles-and-layers-which-cerebral-cavernous-malformations-are-most-difficult-to-dissect-from-surrounding-eloquent-brain-tissue
#12
Philipp Dammann, Karsten Wrede, Ramazan Jabbarli, Oliver Müller, Christoph Mönninghoff, Michael Forsting, Ulrich Sure
BACKGROUND: Cerebral cavernous malformations (CCM) may lead to repetitive intracerebral hemorrhage. In selected cases, a surgical resection is indicated. OBJECTIVE: To identify magnetic resonance imaging (MRI) features of CCM that correlate with the difficulty of dissection and postoperative outcome. METHODS: This study prospectively analyzed pre- and postoperative MRI features, intraoperative findings (surgical questionnaire), and postoperative outcome of 41 patients with eloquent CCM...
March 10, 2017: Neurosurgery
https://www.readbyqxmd.com/read/28325514/multiparametric-approach-with-diffusion-weighted-imaging-and-dynamic-contrast-enhanced-mri-a-comparison-study-for-differentiating-between-benign-and-malignant-bone-lesions-in-adults
#13
E Oh, Y C Yoon, J H Kim, K Kim
AIM: To evaluate and compare the diagnostic performance of quantitative parameters derived from diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in differentiating benign and malignant bone tumours. MATERIALS AND METHODS: Fifty-five patients (age range, 21-82 years; mean age, 55 years) underwent pretreatment MRI. Apparent diffusion coefficient (ADC) values were calculated by DWI. The DCE-MRI data were analysed for the volume transfer constant (K(trans)), extravascular extracellular volume fraction (Ve), and volume rate constant (Kep), and K(trans)/ADC ratio...
March 18, 2017: Clinical Radiology
https://www.readbyqxmd.com/read/28324188/autobiographical-memory-loss-following-a-right-prefrontal-lobe-tumour-resection-a-case-report-and-review-of-the-literature
#14
A A B Jamjoom, P Gallo, J Kandasamy, J Phillips, D Sokol
INTRODUCTION: The right prefrontal lobe has not traditionally been considered eloquent brain. Resection of tumours within this region does not typically lead to permanent functional impairment. In this report, we highlight the case of a patient who developed autobiographical memory loss following an uncomplicated resection of a right prefrontal tumour. CASE MATERIAL: A previously fit and well 15-year old presented with a persistent right-sided headache. An MRI demonstrated an expanded right mid-frontal gyrus with changes consistent with a low-grade tumour...
March 21, 2017: Child's Nervous System: ChNS: Official Journal of the International Society for Pediatric Neurosurgery
https://www.readbyqxmd.com/read/28323841/detection-of-crossed-cerebellar-diaschisis-in-hyperacute-ischemic-stroke-using-arterial-spin-labeled-mr-imaging
#15
Koung Mi Kang, Chul-Ho Sohn, Seung Hong Choi, Keun-Hwa Jung, Roh-Eul Yoo, Tae Jin Yun, Ji-Hoon Kim, Sun-Won Park
BACKGROUND AND PURPOSE: Arterial spin-labeling (ASL) was recently introduced as a noninvasive method to evaluate cerebral hemodynamics. The purposes of this study were to assess the ability of ASL imaging to detect crossed cerebellar diaschisis (CCD) in patients with their first unilateral supratentorial hyperacute stroke and to identify imaging or clinical factors significantly associated with CCD. MATERIALS AND METHODS: We reviewed 204 consecutive patients who underwent MRI less than 8 hours after the onset of stroke symptoms...
2017: PloS One
https://www.readbyqxmd.com/read/28323572/bilateral-changes-in-deep-tissue-environment-after-manual-lymphatic-drainage-in-patients-with-breast-cancer-treatment-related-lymphedema
#16
Paula M C Donahue, Rachelle Crescenzi, Allison O Scott, Vaughn Braxton, Aditi Desai, Seth A Smith, John Jordi, Ingrid M Meszoely, Ana M Grau, Rondi M Kauffmann, Raeshell S Sweeting, Kandace Spotanski, Sheila H Ridner, Manus J Donahue
BACKGROUND: Breast cancer treatment-related lymphedema (BCRL) arises from a mechanical insufficiency following cancer therapies. Early BCRL detection and personalized intervention require an improved understanding of the physiological processes that initiate lymphatic impairment. Here, internal magnetic resonance imaging (MRI) measures of the tissue microenvironment were paired with clinical measures of tissue structure to test fundamental hypotheses regarding structural tissue and muscle changes after the commonly used therapeutic intervention of manual lymphatic drainage (MLD)...
March 2017: Lymphatic Research and Biology
https://www.readbyqxmd.com/read/28323379/effects-of-short-term-levothyroxine-therapy-on-myocardial-injuries-in-patients-with-severe-overt-hypothyroidism-evidence-from-a-cardiac-mri-study
#17
Xia Gao, Zhe Chen, Min Liu, Yu-Mei Jia, Ning Yang, Zhi Yao, Xiao-Meng Feng, Yuan Xu, Guang Wang
PURPOSE: To investigate using magnetic resonance imaging (MRI) myocardial injuries and cardiac function in patients with newly diagnosed severe primary overt hypothyroidism (HT) before and after achieving euthyroidism by short-term levothyroxine treatment. Levothyroxine treatment improves cardiovascular performance and ventricular remodeling in patients with HT, but diffuse myocardial injuries induced by HT are difficult to detect clinically. MATERIALS AND METHODS: Myocardial longitudinal relaxation time (T1 ) mapping using the modified Look-Locker inversion-recovery (MOLLI) sequences at 3...
March 21, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28323371/diffusional-kurtosis-imaging-of-parotid-glands-in-sj%C3%A3-gren-s-syndrome-initial-findings
#18
Chen Chu, Huayong Zhang, Nan Zhou, Xin Dou, Ming Li, Song Liu, Yun Zhu, Chun Wang, Weibo Chen, Queenie Chan, Lingyun Sun, Jian He, Zhengyang Zhou
PURPOSE: To explore the role of diffusion kurtosis imaging (DKI) of parotid glands in diagnosing Sjögren's syndrome (SS). MATERIALS AND METHODS: A total of 40 patients with SS and 40 healthy volunteers underwent 3.0T magnetic resonance imaging (MRI) including DKI, which generated the apparent diffusion coefficient (ADC), corrected diffusion (D), and diffusional kurtosis (K) values. The MR nodular grade was determined on the basis of MR morphological findings. RESULTS: The parotid ADC, D, and K values in patients with SS were significantly higher than those of healthy volunteers (P = 0...
March 21, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28323202/enhanced-structural-connectivity-within-a-brain-sub-network-supporting-working-memory-and-engagement-processes-after-cognitive-training
#19
Francisco J Román, Yasser Iturria-Medina, Kenia Martínez, Sherif Karama, Miguel Burgaleta, Alan C Evans, Susanne M Jaeggi, Roberto Colom
The structural connectome provides relevant information about experience and training-related changes in the brain. Here, we used network-based statistics (NBS) and graph theoretical analyses to study structural changes in the brain as a function of cognitive training. Fifty-six young women were divided in two groups (experimental and control). We assessed their cognitive function before and after completing a working memory intervention using a comprehensive battery that included fluid and crystallized abilities, working memory and attention control, and we also obtained structural MRI images...
March 16, 2017: Neurobiology of Learning and Memory
https://www.readbyqxmd.com/read/28322902/negative-multi-parametric-mri-of-the-prostate-predicts-absence-of-clinically-significant-prostate-cancer-on-12-core-template-prostate-biopsy
#20
Amanda J Lu, Jamil S Syed, Kevin A Nguyen, Cayce B Nawaf, James Rosoff, Michael Spektor, Angelique Levi, Peter A Humphrey, Jeffrey C Weinreb, Peter G Schulam, Preston C Sprenkle
OBJECTIVE: To determine the negative predictive value of multiparametric-MRI (mpMRI), we evaluated the frequency of prostate cancer detection by 12-core template mapping biopsy in men whose mpMRI showed no suspicious regions. METHODS: 670 patients underwent mpMRI followed by transrectal ultrasound-(TRUS) guided systematic prostate biopsy from December 2012 to June 2016. Of this cohort, 100 patients had a negative mpMRI. mpMRI imaging sequences included T2-weighted, diffusion-weighted imaging, and dynamic contrast enhancement sequences...
March 16, 2017: Urology
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