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1

MRI nerve root enhancement in Krabbe disease.  

PubMed

Krabbe disease is characterized by abnormal breakdown and turnover of myelin, leading to extensive demyelination in both the peripheral and central nervous systems. A 7-month-old infant with early-onset Krabbe disease had deceptively normal head images, but spinal MRI demonstrated abnormal gadolinium enhancement of the lumbosacral sacral nerve roots and cauda equina such as that seen in Guillain-Barré syndrome. Abnormal enhancement in spinal MRI has not been previously described in patients with leukodystrophies. PMID:9744639

Vasconcellos, E; Smith, M

1998-08-01

2

Texture Descriptors to distinguish Radiation Necrosis from Recurrent Brain Tumors on multi-parametric MRI.  

PubMed

Differentiating radiation necrosis (a radiation induced treatment effect) from recurrent brain tumors (rBT) is currently one of the most clinically challenging problems in care and management of brain tumor (BT) patients. Both radiation necrosis (RN), and rBT exhibit similar morphological appearance on standard MRI making non-invasive diagnosis extremely challenging for clinicians, with surgical intervention being the only course for obtaining definitive "ground truth". Recent studies have reported that the underlying biological pathways defining RN and rBT are fundamentally different. This strongly suggests that there might be phenotypic differences and hence cues on multi-parametric MRI, that can distinguish between the two pathologies. One challenge is that these differences, if they exist, might be too subtle to distinguish by the human observer. In this work, we explore the utility of computer extracted texture descriptors on multi-parametric MRI (MP-MRI) to provide alternate representations of MRI that may be capable of accentuating subtle micro-architectural differences between RN and rBT for primary and metastatic (MET) BT patients. We further explore the utility of texture descriptors in identifying the MRI protocol (from amongst T1-w, T2-w and FLAIR) that best distinguishes RN and rBT across two independent cohorts of primary and MET patients. A set of 119 texture descriptors (co-occurrence matrix homogeneity, neighboring gray-level dependence matrix, multi-scale Gaussian derivatives, Law features, and histogram of gradient orientations (HoG)) for modeling different macro and micro-scale morphologic changes within the treated lesion area for each MRI protocol were extracted. Principal component analysis based variable importance projection (PCA-VIP), a feature selection method previously developed in our group, was employed to identify the importance of every texture descriptor in distinguishing RN and rBT on MP-MRI. PCA-VIP employs regression analysis to provide an importance score to each feature based on their ability to distinguish the two classes (RN/rBT). The top performing features identified via PCA-VIP were employed within a random-forest classifier to differentiate RN from rBT across two cohorts of 20 primary and 22 MET patients. Our results revealed that, (a) HoG features at different orientations were the most important image features for both cohorts, suggesting inherent orientation differences between RN, and rBT, (b) inverse difference moment (capturing local intensity homogeneity), and Laws features (capturing local edges and gradients) were identified as important for both cohorts, and (c) Gd-C T1-w MRI was identified, across the two cohorts, as the best MRI protocol in distinguishing RN/rBT. PMID:24910722

Pallavi, Tiwari; Prateek, Prasanna; Lisa, Rogers; Leo, Wolansky; Chaitra, Badve; Andrew, Sloan; Mark, Cohen; Anant, Madabhushi

2014-01-01

3

Texture Descriptors to distinguish Radiation Necrosis from Recurrent Brain Tumors on multi-parametric MRI  

PubMed Central

Differentiating radiation necrosis (a radiation induced treatment effect) from recurrent brain tumors (rBT) is currently one of the most clinically challenging problems in care and management of brain tumor (BT) patients. Both radiation necrosis (RN), and rBT exhibit similar morphological appearance on standard MRI making non-invasive diagnosis extremely challenging for clinicians, with surgical intervention being the only course for obtaining definitive “ground truth”. Recent studies have reported that the underlying biological pathways defining RN and rBT are fundamentally different. This strongly suggests that there might be phenotypic differences and hence cues on multi-parametric MRI, that can distinguish between the two pathologies. One challenge is that these differences, if they exist, might be too subtle to distinguish by the human observer. In this work, we explore the utility of computer extracted texture descriptors on multi-parametric MRI (MP-MRI) to provide alternate representations of MRI that may be capable of accentuating subtle micro-architectural differences between RN and rBT for primary and metastatic (MET) BT patients. We further explore the utility of texture descriptors in identifying the MRI protocol (from amongst T1-w, T2-w and FLAIR) that best distinguishes RN and rBT across two independent cohorts of primary and MET patients. A set of 119 texture descriptors (co-occurrence matrix homogeneity, neighboring gray-level dependence matrix, multi-scale Gaussian derivatives, Law features, and histogram of gradient orientations (HoG)) for modeling different macro and micro-scale morphologic changes within the treated lesion area for each MRI protocol were extracted. Principal component analysis based variable importance projection (PCA-VIP), a feature selection method previously developed in our group, was employed to identify the importance of every texture descriptor in distinguishing RN and rBT on MP-MRI. PCA-VIP employs regression analysis to provide an importance score to each feature based on their ability to distinguish the two classes (RN/rBT). The top performing features identified via PCA-VIP were employed within a random-forest classifier to differentiate RN from rBT across two cohorts of 20 primary and 22 MET patients. Our results revealed that, (a) HoG features at different orientations were the most important image features for both cohorts, suggesting inherent orientation differences between RN, and rBT, (b) inverse difference moment (capturing local intensity homogeneity), and Laws features (capturing local edges and gradients) were identified as important for both cohorts, and (c) Gd-C T1-w MRI was identified, across the two cohorts, as the best MRI protocol in distinguishing RN/rBT. PMID:24910722

Pallavi, Tiwari; Prateek, Prasanna; Lisa, Rogers; Leo, Wolansky; Chaitra, Badve; Andrew, Sloan; Mark, Cohen; Anant, Madabhushi

2014-01-01

4

78 FR 12329 - Distinguishing Medical Device Recalls From Product Enhancements; Reporting Requirements; Draft...  

Federal Register 2010, 2011, 2012, 2013, 2014

...FDA-2013-D-0114] Distinguishing Medical Device Recalls From Product Enhancements...guidance entitled ``Distinguishing Medical Device Recalls From Product Enhancements...potential change to a device is a medical device recall, distinguish those...

2013-02-22

5

Distinguishing Conjoint and Independent Neural Tuning for Stimulus Features With fMRI Adaptation  

PubMed Central

A central focus of cognitive neuroscience is identification of the neural codes that represent stimulus dimensions. One common theme is the study of whether dimensions, such as color and shape, are encoded independently by separate pools of neurons or are represented by neurons conjointly tuned for both properties. We describe an application of functional magnetic resonance imaging (fMRI) adaptation to distinguish between independent and conjoint neural representations of dimensions by examining the neural signal evoked by changes in one versus two stimulus dimensions and considering the metric of two-dimension additivity. We describe how a continuous carry-over paradigm may be used to efficiently estimate this metric. The assumptions of the method are examined as are optimizations. Finally, we demonstrate that the method produces the expected result for fMRI data collected from ventral occipitotemporal cortex while subjects viewed sets of shapes predicted to be represented by conjoint or independent neural tuning. PMID:19357342

Drucker, Daniel M.; Kerr, Wesley Thomas; Aguirre, Geoffrey Karl

2009-01-01

6

Manganese enhanced MRI (MEMRI): neurophysiological applications  

PubMed Central

Manganese ion (Mn2+) is a calcium (Ca2+) analog that can enter neurons and other excitable cells through voltage gated Ca2+ channels. Mn2+ is also a paramagnetic that shortens the spin-lattice relaxation time constant (T1) of tissues where it has accumulated, resulting in positive contrast enhancement. Mn2+ was first investigated as a magnetic resonance imaging (MRI) contrast agent approximately 20 years ago to assess the toxicity of the metal in rats. In the late 1990s, Alan Koretsky and colleagues pioneered the use of manganese enhanced MRI (MEMRI) towards studying brain activity, tract tracing and enhancing anatomical detail. This review will describe the methodologies and applications of MEMRI in the following areas: monitoring brain activity in animal models, in vivo neuronal tract tracing and using MEMRI to assess in vivo axonal transport rates. PMID:22098448

Inoue, Taeko; Majid, Tabassum; Pautler, Robia G.

2012-01-01

7

Distinguishing Cancerous Liver Cells Using Surface-Enhanced Raman Spectroscopy.  

PubMed

Raman spectroscopy has been widely used in biomedical research and clinical diagnostics. It possesses great potentials for the analysis of biochemical processes in cell studies. In this article, the surface-enhanced Raman spectroscopy (SERS) of normal and cancerous liver cells incubated with SERS active substrates (gold nanoparticle) was measured using confocal Raman microspectroscopy technology. The chemical components of the cells were analyzed through statistical methods for the SERS spectrum. Both the relative intensity ratio and principal component analysis (PCA) were used for distinguishing the normal liver cells (QSG-7701) from the hepatoma cells (SMMC-7721). The relative intensity ratio of the Raman spectra peaks such as I937/I1209, I1276/I1308, I1342/I1375, and I1402/I1435 was set as the judge boundary, and the sensitivity and the specificity using PCA method were calculated. The results indicated that the surface-enhanced Raman spectrum could provide the chemical information for distinguishing the normal cells from the cancerous liver cells and demonstrated that SERS technology possessed the possible applied potential for the diagnosis of liver cancer. PMID:25432931

Huang, Jing; Liu, Shupeng; Chen, Zhenyi; Chen, Na; Pang, Fufei; Wang, Tingyun

2014-11-28

8

POCS-Enhanced Correction of Motion Artifacts in Parallel MRI  

E-print Network

POCS-Enhanced Correction of Motion Artifacts in Parallel MRI Alexey A. Samsonov,1 * Julia Velikina for correction of MRI motion artifacts induced by corrupted k-space data, acquired by multiple receiver coils for recon- struction of sensitivity encoded MRI data (POCSENSE) is employed to identify corrupted k

Utah, University of

9

TMJ disorders and pain: Assessment by contrast-enhanced MRI  

Microsoft Academic Search

Though magnetic resonance (MRI) is a widely accepted standard for the assessment of patients with temporomandibular joint (TMJ) disorders, efforts to correlate symptoms to MRI findings have often given controversial results. Aim of this study was to investigate the correlation between TMJ pain and findings of contrast-enhanced MRI. Thirty-eight consecutive patients with TMJ dysfunction syndrome (study group) were examined with

Davide Farina; Christiane Bodin; Silvia Gandolfi; Werner De Gasperi; Andrea Borghesi; Roberto Maroldi

2009-01-01

10

A Robust Classifier to Distinguish Noise from fMRI Independent Components  

PubMed Central

Analyzing Functional Magnetic Resonance Imaging (fMRI) of resting brains to determine the spatial location and activity of intrinsic brain networks–a novel and burgeoning research field–is limited by the lack of ground truth and the tendency of analyses to overfit the data. Independent Component Analysis (ICA) is commonly used to separate the data into signal and Gaussian noise components, and then map these components on to spatial networks. Identifying noise from this data, however, is a tedious process that has proven hard to automate, particularly when data from different institutions, subjects, and scanners is used. Here we present an automated method to delineate noisy independent components in ICA using a data-driven infrastructure that queries a database of 246 spatial and temporal features to discover a computational signature of different types of noise. We evaluated the performance of our method to detect noisy components from healthy control fMRI (sensitivity?=?0.91, specificity?=?0.82, cross validation accuracy (CVA)?=?0.87, area under the curve (AUC)?=?0.93), and demonstrate its generalizability by showing equivalent performance on (1) an age- and scanner-matched cohort of schizophrenia patients from the same institution (sensitivity?=?0.89, specificity?=?0.83, CVA?=?0.86), (2) an age-matched cohort on an equivalent scanner from a different institution (sensitivity?=?0.88, specificity?=?0.88, CVA?=?0.88), and (3) an age-matched cohort on a different scanner from a different institution (sensitivity?=?0.72, specificity?=?0.92, CVA?=?0.79). We additionally compare our approach with a recently published method [1]. Our results suggest that our method is robust to noise variations due to population as well as scanner differences, thereby making it well suited to the goal of automatically distinguishing noise from functional networks to enable investigation of human brain function. PMID:24748378

Sochat, Vanessa; Supekar, Kaustubh; Bustillo, Juan; Calhoun, Vince; Turner, Jessica A.; Rubin, Daniel L.

2014-01-01

11

In Vivo MRI Atherosclerotic Plaque Characterization Using Magnetic Susceptibility Distinguishes Symptom-Producing Plaques  

PubMed Central

Objectives We investigated iron's role in atherosclerosis and plaque instability with a novel approach to in vivo atherosclerotic plaque characterization using noninvasive, noncontrast magnetic resonance-based T2* measurement. We validated this approach using ex vivo plaque analyses to establish that T2* reflects intraplaque iron composition. Background Iron catalyzes free radical production, a key step for lipid peroxidation and atherosclerosis development. The parameter T2* measures tissue magnetic susceptibility, historically has been used to quantify hepatic and myocardial iron. To date, T2* measurement has not been previously developed for in vivo plaque characterization in patients with atherosclerosis. Methods Thirty-nine patients referred for carotid endarterectomy were prospectively enrolled to undergo preoperative carotid MRI and postoperative analysis of the explanted plaque. Clinical history of any symptoms attributable to each carotid lesion was recorded. Results MRI could not be completed in 4 subjects due to claustrophobia, and three patients scanned prior to the use of a neck stabilizer had motion artifact precluding quantification. In the remaining subjects, symptomatic compared to asymptomatic patients had significantly lower plaque T2* values (20.0±1.8 vs. 34.4±2.7 ms, respectively, p<0.001). Analytical methods demonstrated similar total iron (138.6±36.5 vs. 165.8±48.3 mg/kg, p=NS) but less low-molecular weight Fe(III) (7.3±3.8 vs. 17.7±4.0 nmol/mg, p<0.05) in the explanted plaques of symptomatic versus asymptomatic patients, respectively, consistent with a shift in iron from Fe(III) to higher amounts of T2*-shortening forms of iron. Mass spectroscopy also showed significantly lower calcium (37.5±10.8 vs. 123.6±19.3 g/kg, p<0.01) and higher copper (3.2±0.5 vs. 1.7±0.1 mg/kg, p<0.01) in plaques from symptomatic patients. Conclusions In vivo measurement of intraplaque T2* using MRI is feasible and reproducible, and distinguishes symptom-producing from non-symptom producing plaques in patients with carotid artery atherosclerosis. Symptom-producing plaques demonstrated characteristic changes in iron forms by ex vivo analysis, supporting the dynamic presence of iron in the microenvironment of atherosclerotic plaque. PMID:19356405

Raman, Subha V.; Winner, Marshall W.; Tran, Tam; Velayutham, Murugesan; Simonetti, Orlando P.; Baker, Peter B.; Olesik, John; McCarthy, Beth; Ferketich, Amy K.; Zweier, Jay L.

2009-01-01

12

Distinguishing the processing of gestures from signs in deaf individuals: an fMRI study.  

PubMed

Manual gestures occur on a continuum from co-speech gesticulations to conventionalized emblems to language signs. Our goal in the present study was to understand the neural bases of the processing of gestures along such a continuum. We studied four types of gestures, varying along linguistic and semantic dimensions: linguistic and meaningful American Sign Language (ASL), non-meaningful pseudo-ASL, meaningful emblematic, and nonlinguistic, non-meaningful made-up gestures. Pre-lingually deaf, native signers of ASL participated in the fMRI study and performed two tasks while viewing videos of the gestures: a visuo-spatial (identity) discrimination task and a category discrimination task. We found that the categorization task activated left ventral middle and inferior frontal gyrus, among other regions, to a greater extent compared to the visual discrimination task, supporting the idea of semantic-level processing of the gestures. The reverse contrast resulted in enhanced activity of bilateral intraparietal sulcus, supporting the idea of featural-level processing (analogous to phonological-level processing of speech sounds) of the gestures. Regardless of the task, we found that brain activation patterns for the nonlinguistic, non-meaningful gestures were the most different compared to the ASL gestures. The activation patterns for the emblems were most similar to those of the ASL gestures and those of the pseudo-ASL were most similar to the nonlinguistic, non-meaningful gestures. The fMRI results provide partial support for the conceptualization of different gestures as belonging to a continuum and the variance in the fMRI results was best explained by differences in the processing of gestures along the semantic dimension. PMID:19397900

Husain, Fatima T; Patkin, Debra J; Thai-Van, Hung; Braun, Allen R; Horwitz, Barry

2009-06-18

13

Resting-state BOLD networks versus task-associated functional MRI for distinguishing Alzheimer's disease risk groups  

PubMed Central

To assess the ability of resting state functional magnetic resonance imaging to distinguish known risk factors for AD, we evaluated 17 cognitively normal individuals with a family history of AD and at least one copy of the apolipoprotein e4 allele compared to 12 individuals who were not carriers of the APOE4 gene and did not have a family history of AD. Blood oxygen level dependent fMRI was performed evaluating encoding-associated signal and resting state default mode network signal differences between the two risk groups. Neurocognitive testing revealed that the high risk group performed worse on category fluency testing, but the groups were equivalent on all other cognitive measures. During encoding of novel face-name pairs, there were no regions of encoding-associated BOLD activations that were different in the high risk group. Encoding-associated deactivations were greater in magnitude in the low risk group in the medial and right lateral parietal cortex, similar to findings in AD studies. The resting state DMN analysis demonstrated nine regions in the prefrontal, orbital frontal, temporal and parietal lobes that distinguished the two risk groups. Resting state DMN analysis could distinguish risk groups with an effect size of 3.35, compared to an effect size of 1.39 using encoding-associated fMRI techniques. Imaging of the resting state avoids performance related variability seen in activation fMRI, is less complicated to acquire and standardize, does not require radio-isotopes, and may be more effective at identifying functional pathology associated with AD risk compared to non-resting fMRI techniques. PMID:19539034

Fleisher, Adam S.; Sherzai, Ayesha; Taylor, Curtis; Langbaum, Jessica B.S.; Chen, Kewei; Buxton, Richard B.

2009-01-01

14

Resting-state BOLD networks versus task-associated functional MRI for distinguishing Alzheimer's disease risk groups.  

PubMed

To assess the ability of resting-state functional magnetic resonance imaging to distinguish known risk factors for AD, we evaluated 17 cognitively normal individuals with a family history of AD and at least one copy of the apolipoprotein e4 allele compared to 12 individuals who were not carriers of the APOE4 gene and did not have a family history of AD. Blood oxygen level dependent fMRI was performed evaluating encoding-associated signal and resting-state default mode network signal differences between the two risk groups. Neurocognitive testing revealed that the high risk group performed worse on category fluency testing, but the groups were equivalent on all other cognitive measures. During encoding of novel face-name pairs, there were no regions of encoding-associated BOLD activations that were different in the high risk group. Encoding-associated deactivations were greater in magnitude in the low risk group in the medial and right lateral parietal cortex, similar to findings in AD studies. The resting-state DMN analysis demonstrated nine regions in the prefrontal, orbital frontal, temporal and parietal lobes that distinguished the two risk groups. Resting-state DMN analysis could distinguish risk groups with an effect size of 3.35, compared to an effect size of 1.39 using encoding-associated fMRI techniques. Imaging of the resting state avoids performance related variability seen in activation fMRI, is less complicated to acquire and standardize, does not require radio-isotopes, and may be more effective at identifying functional pathology associated with AD risk compared to non-resting fMRI techniques. PMID:19539034

Fleisher, Adam S; Sherzai, Ayesha; Taylor, Curtis; Langbaum, Jessica B S; Chen, Kewei; Buxton, Richard B

2009-10-01

15

Differentiation of Reactive and Tumor Metastatic Lymph Nodes with Diffusion-weighted and SPIO Enhanced MRI  

PubMed Central

Objectives Determination of lymphatic metastasis is of great importance for both treatment planning and patient prognosis. We aim to distinguish tumor metastatic lymph nodes (TLNs) and reactive lymph nodes (RLNs) with diffusion-weighted and superparamagnetic iron oxide (SPIO) enhanced magnetic resonance imaging (MRI). Materials and methods Ipsilateral popliteal lymph node metastasis or lymphadenitis model was established by hock injection of either luciferase-expressing 4T1 murine breast cancer cells or Complete Freund Adjuvant (CFA) in male Balb/C mice. At different time points after inoculation, bioluminescence imaging, T2-weighted, diffusion-weighted and SPIO enhanced MRI were performed. Imaging findings were confirmed by histopathological staining. Results Size enlargement was observed in both TLNs and RLNs. At day 28, TLNs showed strong bioluminescence signal and bigger size than RLNs (p < 0.01). At early stages up to day 21, both TLNs and RLNs appeared homogeneous on diffusion-weighted imaging (DWI). At day 28, TLNs showed heterogeneous apparent diffusion coefficient (ADC) map with significantly higher average ADC value of 0.41 ± 0.03 × 10?3 mm2/s than that of RLNs (0.34 ± 0.02 10?3 mm2/s, p < 0.05). On SPIO enhanced MRI, both TLNs and RLNs showed distinct T2 signal reduction at day 21 after inoculation. At day 28, TLNs demonstrated partial uptake of the iron oxide particles, which was confirmed by Prussian blue staining. Conclusions Both diffusion-weighted and SPIO enhanced MRI can distinguish tumor metastatic lymph nodes from reactive lymph nodes. However, neither method is able to detect tumor metastasis to the draining lymph nodes at early stages. PMID:22588595

Zhang, Fan; Zhu, Lei; Huang, Xinglu; Niu, Gang; Chen, Siouan

2012-01-01

16

Ultrashort Echo Time for Improved Positive-Contrast Manganese-Enhanced MRI of Cancer  

PubMed Central

Objective Manganese (Mn) is a positive magnetic resonance imaging (MRI) contrast agent that has been used to obtain physiological, biochemical, and molecular biological information. There is great interest to broaden its applications, but a major challenge is to increase detection sensitivity. Another challenge is distinguishing regions of Mn-related signal enhancement from background tissue with inherently similar contrast. To overcome these limitations, this study investigates the use of ultrashort echo time (UTE) and subtraction UTE (SubUTE) imaging for more sensitive and specific determination of Mn accumulation. Materials and Methods Simulations were performed to investigate the feasibility of UTE and SubUTE for Mn-enhanced MRI and to optimize imaging parameters. Phantoms containing aqueous Mn solutions were imaged on a MRI scanner to validate simulations predictions. Breast cancer cells that are very aggressive (MDA-MB-231 and a more aggressive variant LM2) and a less aggressive cell line (MCF7) were labeled with Mn and imaged on MRI. All imaging was performed on a 3 Tesla scanner and compared UTE and SubUTE against conventional T1-weighted spoiled gradient echo (SPGR) imaging. Results Simulations and phantom imaging demonstrated that UTE and SubUTE provided sustained and linearly increasing positive contrast over a wide range of Mn concentrations, whereas conventional SPGR displayed signal plateau and eventual decrease. Higher flip angles are optimal for imaging higher Mn concentrations. Breast cancer cell imaging demonstrated that UTE and SubUTE provided high sensitivity, with SubUTE providing background suppression for improved specificity and eliminating the need for a pre-contrast baseline image. The SubUTE sequence allowed the best distinction of aggressive breast cancer cells. Conclusions UTE and SubUTE allow more sensitive and specific positive-contrast detection of Mn enhancement. This imaging capability can potentially open many new doors for Mn-enhanced MRI in vascular, cellular, and molecular imaging. PMID:23484042

Nofiele, Joris Tchouala; Cheng, Hai-Ling Margaret

2013-01-01

17

Engineering Gd-loaded nanoparticles to enhance MRI sensitivity via T1 shortening  

PubMed Central

Magnetic resonance imaging (MRI) is a noninvasive imaging technique capable of obtaining high-resolution anatomical images of the body. Major drawbacks of MRI are the low contrast agent sensitivity and inability to distinguish healthy tissue from diseased tissue, making early detection challenging. To address this technological hurdle, paramagnetic contrast agents have been developed to increase the longitudinal relaxivity (R1), leading to an increased signal-to-noise ratio. This review focuses on methods and principles that enabled the design and engineering of nanoparticles to deliver contrast agents with enhanced ionic relaxivities. Different engineering strategies and nanoparticle platforms will be compared in terms of their manufacturability, biocompatibility properties, and their overall potential to make an impact in clinical MR imaging. PMID:24158750

Bruckman, Michael A.; Yu, Xin; Steinmetz, Nicole F.

2013-01-01

18

Dynamic contrast-enhanced imaging techniques: CT and MRI  

PubMed Central

Over the last few decades there has been considerable research into quantifying the cerebral microvasculature with imaging, for use in studies of the human brain and various pathologies including cerebral tumours. This review highlights key issues in dynamic contrast-enhanced CT, dynamic contrast-enhanced MRI and arterial spin labelling, the various applications of which are considered elsewhere in this special issue of the British Journal of Radiology. PMID:22433822

O'Connor, J P B; Tofts, P S; Miles, K A; Parkes, L M; Thompson, G; Jackson, A

2011-01-01

19

Gadolinium-enhanced MRI in central nervous system Behçet's disease.  

PubMed

Two cases of central nervous system Behçet's disease, studied by gadolinium-enhanced MRI, are presented. In one patient, whose clinical picture was dominated by a brain syndrome, the gadolinium enhancement resolved with clinical improvement, although the hyperintense areas in the mesencephalon on T2-weighted images persisted. In the second, who had a pseudobulbar palsy and a mild right hemiparesis, there were many abnormal areas, but an enhancing focus in the posterior limb of the left internal capsule was probably the lesion responsible for the hemiparesis. PMID:8433790

Erdem, E; Carlier, R; Idir, A B; Masnou, P O; Moulonguet, A; Adams, D; Doyon, D

1993-01-01

20

Classic models for dynamic contrast-enhanced MRI.  

PubMed

Dynamic contrast-enhanced MRI (DCE-MRI) is a functional MRI method where T1 -weighted MR images are acquired dynamically after bolus injection of a contrast agent. The data can be interpreted in terms of physiological tissue characteristics by applying the principles of tracer-kinetic modelling. In the brain, DCE-MRI enables measurement of cerebral blood flow (CBF), cerebral blood volume (CBV), blood-brain barrier (BBB) permeability-surface area product (PS) and the volume of the interstitium (ve ). These parameters can be combined to form others such as the volume-transfer constant K(trans) , the extraction fraction E and the contrast-agent mean transit times through the intra- and extravascular spaces. A first generation of tracer-kinetic models for DCE-MRI was developed in the early 1990s and has become a standard in many applications. Subsequent improvements in DCE-MRI data quality have driven the development of a second generation of more complex models. They are increasingly used, but it is not always clear how they relate to the models of the first generation or to the model-free deconvolution methods for tissues with intact BBB. This lack of understanding is leading to increasing confusion on when to use which model and how to interpret the parameters. The purpose of this review is to clarify the relation between models of the first and second generations and between model-based and model-free methods. All quantities are defined using a generic terminology to ensure the widest possible scope and to reveal the link between applications in the brain and in other organs. PMID:23674304

Sourbron, Steven P; Buckley, David L

2013-08-01

21

Consensus Recommendation for Acquisition of Dynamic Contrasted-Enhanced MRI Data in Oncology  

Cancer.gov

Establish minimum requirements for standardized data acquisition for oncologic applications of dynamic contrast enhanced MRI (DCE-MRI) to allow integration of data from different institutions and comparison of various approaches for data analysis.

22

Manganese-enhanced MRI: an exceptional tool in translational neuroimaging.  

PubMed

The metal manganese is a potent magnetic resonance imaging (MRI) contrast agent that is essential in cell biology. Manganese-enhanced magnetic resonance imaging (MEMRI) is providing unique information in an ever-growing number of applications aimed at understanding the anatomy, the integration, and the function of neural circuits both in normal brain physiology as well as in translational models of brain disease. A major drawback to the use of manganese as a contrast agent, however, is its cellular toxicity. Therefore, paramount to the successful application of MEMRI is the ability to deliver Mn2+ to the site of interest using as low a dose as possible while preserving detectability by MRI. In the present work, the different approaches to MEMRI in translational neuroimaging are reviewed and challenges for future identified from a practical standpoint. PMID:18550591

Silva, Afonso C; Bock, Nicholas A

2008-07-01

23

IMPATIENT MRI: ILLINOIS MASSIVELY PARALLEL ACCELERATION TOOLKIT FOR IMAGE RECONSTRUCTION WITH ENHANCED  

E-print Network

IMPATIENT MRI: ILLINOIS MASSIVELY PARALLEL ACCELERATION TOOLKIT FOR IMAGE RECONSTRUCTION WITH ENHANCED THROUGHPUT IN MRI Xiao-Long Wu1 , Jiading Gai2 , Fan Lam1,2 , Maojing Fu1,2 , Justin P. Haldar1 and temporal resolution in magnetic resonance imaging (MRI). Additionally, significant developments in image

Hwu, Wen-mei W.

24

Dynamic contrast-enhanced MRI evaluation of cerebral cavernous malformations.  

PubMed

The aim of this study is to quantitatively evaluate the behavior of CNS cavernous malformations (CCMs) using a dynamic contrast-enhanced MRI (DCEMRI) technique sensitive for slow transfer rates of gadolinium. The prospective study was approved by the institutional review board and was HIPPA compliant. Written informed consent was obtained from 14 subjects with familial CCMs (4 men and 10 women, ages 22-76 years, mean 48.1 years). Following routine anatomic MRI of the brain, DCEMRI was performed for six slices, using T1 mapping with partial inversion recovery (TAPIR) to calculate T1 values, following administration of 0.025 mmol/kg gadolinium DTPA. The transfer rate (Ki) was calculated using the Patlak model, and Ki within CCMs was compared to normal-appearing white matter as well as to 17 normal control subjects previously studied. All subjects had typical MRI appearance of CCMs. Thirty-nine CCMs were studied using DCEMRI. Ki was low or normal in 12 lesions and elevated from 1.4 to 12 times higher than background in the remaining 27 lesions. Ki ranged from 2.1E-6 to 9.63E-4 min(-1), mean 3.55E-4. Normal-appearing white matter in the CCM patients had a mean Ki of 1.57E-4, not statistically different from mean WM Ki of 1.47E-4 in controls. TAPIR-based DCEMRI technique permits quantifiable assessment of CCMs in vivo and reveals considerable differences not seen with conventional MRI. Potential applications include correlation with biologic behavior such as lesion growth or hemorrage, and measurement of drug effects. PMID:24323376

Hart, Blaine L; Taheri, Saeid; Rosenberg, Gary A; Morrison, Leslie A

2013-10-01

25

Dynamic Contrast-Enhanced MRI Evaluation of Cerebral Cavernous Malformations  

PubMed Central

The aim of this study is to quantitatively evaluate the behavior of CNS cavernous malformations (CCMs) using a dynamic contrast-enhanced MRI (DCEMRI) technique sensitive for slow transfer rates of gadolinium. The prospective study was approved by the institutional review board and was HIPPA compliant. Written informed consent was obtained from 14 subjects with familial CCMs (4 men and 10 women, ages 22–76 years, mean 48.1 years). Following routine anatomic MRI of the brain, DCEMRI was performed for six slices, using T1 mapping with partial inversion recovery (TAPIR) to calculate T1 values, following administration of 0.025 mmol/kg gadolinium DTPA. The transfer rate (Ki) was calculated using the Patlak model, and Ki within CCMs was compared to normal-appearing white matter as well as to 17 normal control subjects previously studied. All subjects had typical MRI appearance of CCMs. Thirty-nine CCMs were studied using DCEMRI. Ki was low or normal in 12 lesions and elevated from 1.4 to 12 times higher than background in the remaining 27 lesions. Ki ranged from 2.1E–6 to 9.63E–4 min?1, mean 3.55E–4. Normal-appearing white matter in the CCM patients had a mean Ki of 1.57E–4, not statistically different from mean WM Ki of 1.47E–4 in controls. TAPIR-based DCEMRI technique permits quantifiable assessment of CCMs in vivo and reveals considerable differences not seen with conventional MRI. Potential applications include correlation with biologic behavior such as lesion growth or hemorrage, and measurement of drug effects. PMID:24323376

Hart, B. L.; Taheri, S.; Rosenberg, G. A.; Morrison, L. A.

2013-01-01

26

A Simulation Tool for Dynamic Contrast Enhanced MRI  

PubMed Central

The quantification of bolus-tracking MRI techniques remains challenging. The acquisition usually relies on one contrast and the analysis on a simplified model of the various phenomena that arise within a voxel, leading to inaccurate perfusion estimates. To evaluate how simplifications in the interstitial model impact perfusion estimates, we propose a numerical tool to simulate the MR signal provided by a dynamic contrast enhanced (DCE) MRI experiment. Our model encompasses the intrinsic and relaxations, the magnetic field perturbations induced by susceptibility interfaces (vessels and cells), the diffusion of the water protons, the blood flow, the permeability of the vessel wall to the the contrast agent (CA) and the constrained diffusion of the CA within the voxel. The blood compartment is modeled as a uniform compartment. The different blocks of the simulation are validated and compared to classical models. The impact of the CA diffusivity on the permeability and blood volume estimates is evaluated. Simulations demonstrate that the CA diffusivity slightly impacts the permeability estimates ( for classical blood flow and CA diffusion). The effect of long echo times is investigated. Simulations show that DCE-MRI performed with an echo time may already lead to significant underestimation of the blood volume (up to 30% lower for brain tumor permeability values). The potential and the versatility of the proposed implementation are evaluated by running the simulation with realistic vascular geometry obtained from two photons microscopy and with impermeable cells in the extravascular environment. In conclusion, the proposed simulation tool describes DCE-MRI experiments and may be used to evaluate and optimize acquisition and processing strategies. PMID:23516414

Mauconduit, Franck; Christen, Thomas; Barbier, Emmanuel Luc

2013-01-01

27

Differentiation of solid pancreatic tumors by using dynamic contrast-enhanced MRI  

NASA Astrophysics Data System (ADS)

Distinguishing among different solid pancreatic tumor types, pancreatic ductal adenocarcinomas, neuroendocrine tumors (NETs), and solid pseudopapillary tumors (SPTs) is important, as the treatment options are vastly different. This study compared characteristics of solid pancreatic tumors by using dynamic contrast enhanced magnetic resonance imaging (MRI). Fifty patients underwent MR imaging of pancreatic masses with a histopathology that was later confirmed as an adenocarcinoma (n = 27), a NET (n = 16), and a SPT (n = 7). For qualitative analysis, two reviewers evaluated the morphologic features of the tumors: locations, margins, shapes, contained products, pancreatic ductal dilatation, and grade of signal intensity (SI). For the quantitative analysis, all phases of the MR images were co-registered using proprietary image registration software; thus, a region of interest (ROI) defined on one phase could be re-applied in other phases. The following four ratios were considered: tumor-to-uninvolved pancreas SI ratio, percent SI change, tumor-touninvolved pancreas enhancement index, and arterial-to-delayed washout rate. The areas under the receiver operating characteristic (ROC) curves were assessed for the four ratios. Adenocarcinomas had ill-defined margins, irregular shapes, and ductal dilatation compared with NETs and SPTs (P < 0.001). The tumor-to-uninvolved pancreas ratio on all dynamic phases was significantly higher for NETs than for both adenocarcinomas and SPTs (P < 0.05). Percentage SI changes of pancreatic tumors on the pancreatic and the portal venous phases were significantly higher for NETs than for both adenocarcinomas and SPTs (P < 0.05). A significant difference between NETs and adenocarcinomas was also found with respect to the tumor-to-uninvolved pancreas enhancement index and arterial-to-delayed washout rate. The percentage SI changes in the pancreatic phase and the arterial-to-delayed washout rate best distinguished between adenocarcinomas and NETs with the area under the ROC curve being 0.87. The percentage SI changes in the pancreatic and the portal venous phases best distinguished between NETs and SPTs with area under the ROC curve 0.87. In summary, contrast-enhanced MRI can be useful in differentiating solid pancreatic tumors in qualitative and quantitative analyses.

Choi, Seung Joon; Kim, Hyung Sik; Park, Hyunjin

2014-01-01

28

2013 Fall : Distinguished Honors Distinguished  

E-print Network

Distinguished Arscott Mary Kennon Distinguished Ashe Katherine Lee Distinguished Atkins Danielle S Distinguished Distinguished Campbell Miles Arthur Distinguished Campbell Taylor David Distinguished Campli Christy Sophia

Kasman, Alex

29

2009 Spring : Distinguished Honors Distinguished  

E-print Network

Distinguished Applewhite Madelyn Ellen Distinguished Aragone Rachel Distinguished Ard Sheri M Distinguished Louise Distinguished Campbell Christopher Warren Distinguished Campbell Samantha Lyn Distinguished Carson Nicole N Distinguished Cartee Tiffany Faith Distinguished Casamassa David James Distinguished

Kasman, Alex

30

High Speed 3D Overhauser-Enhanced MRI Using Combined b-SSFP and Compressed Sensing  

E-print Network

- clear magnetization via dynamic nuclear polarization (DNP) and subsequently images the enhanced nuclear spin polarization with MRI. OMRI provides an excellent way to image free radical species as narrow NMR: Overhauser-enhanced MRI is a promising technique for imaging the distribution and dynamics of free radicals

Rosen, Matthew S

31

In vivo auditory brain mapping in mice with Mn-enhanced MRI  

E-print Network

In vivo auditory brain mapping in mice with Mn-enhanced MRI Xin Yu1,2, Youssef Zaim Wadghiri1 brain development and hearing loss. We developed a manganese- enhanced MRI (MEMRI) method to map regions and molecular basis for the development of brain function. At present, knowledge of the genetic factors

32

Mammographic density, MRI background parenchymal enhancement and breast cancer risk  

PubMed Central

Mammographic density (MD), representing connective and epithelial tissue (fibroglandular tissue, FGT) is a major risk factor for breast cancer. In an analysis of an autopsy series (Bartow SA, Pathak DR, Mettler FA. Radiographic microcalcification and parenchymal patterns as indicators of histologic “high-risk” benign breast disease. Cancer 1990; 66: 1721–1725, Bartow SA, Pathak DR, Mettler FA et al. Breast mammographic pattern: a concatenation of confounding and breast cancer risk factors. Am J Epidemiol 1995; 142: 813–819), MD was found to be strongly correlated with the collagen and epithelial content of the breast (Li T, Sun L, Miller N et al. The association of measured breast tissue characteristics with MD and other risk factors for breast cancer. Cancer Epidemiol Biomarkers Prev 2005; 14: 343–349), and another report showed that breast epithelium was highly concentrated in the areas of collagen concentration (Hawes D, Downey S, Pearce CL et al. Dense breast stromal tissue shows greatly increased concentration of breast epithelium but no increase in its proliferative activity. Breast Cancer Res 2006; 8: R24). Collagen comprises the overwhelming majority of the FGT, occupying an area on the slides obtained from the autopsy series some 15 times the area of glandular tissue. The relationship of MD with breast cancer risk appears likely to be due to a major extent to increasing epithelial cell numbers with increasing MD. FGT is also seen in breast magnetic resonance imaging (breast MRI) and, as expected, it has been shown that this measure of FGT (MRI-FGT) is highly correlated with MD. A contrast-enhanced breast MRI shows that normal FGT ‘enhances’ (background parenchymal enhancement, BPE) after contrast agent is administered(Morris EA. Diagnostic breast MR imaging: current status and future directions. Radiol Clin North Am 2007; 45: 863–880, vii., Kuhl C. The current status of breast MR imaging. Part I. Choice of technique, image interpretation, diagnostic accuracy, and transfer to clinical practice. Radiology 2007; 244: 356–378), and a recent study suggests that BPE is also a major breast cancer risk factor, possibly as important as, and independent of MD (King V, Brooks JD, Bernstein JL et al. BPE at breast MR imaging and breast cancer risk. Radiology 2011; 260: 50–60). BPE is much more sensitive to the effects of menopause and tamoxifen than is FGT (King V, Gu Y, Kaplan JB et al. Impact of menopausal status on BPE and fibroglandular tissue on breast MRI. Eur Radiol 2012; 22: 2641–2647, King V, Kaplan J, Pike MC et al. Impact of tamoxifen on amount of fibroglandular tissue, BPE, and cysts on breast MRI. Breast J 2012; 18: 527–534). Changes in MD and BPE may be most useful in predicting response to chemopreventive agents aimed at blocking breast cell proliferation. More study of the biological basis of the effects of MD and BPE is needed if we are to fully exploit these factors in developing chemopreventive approaches to breast cancer. PMID:24131968

Pike, M. C.; Pearce, C. L.

2013-01-01

33

Mammographic density, MRI background parenchymal enhancement and breast cancer risk.  

PubMed

Mammographic density (MD), representing connective and epithelial tissue (fibroglandular tissue, FGT) is a major risk factor for breast cancer. In an analysis of an autopsy series (Bartow SA, Pathak DR, Mettler FA. Radiographic microcalcification and parenchymal patterns as indicators of histologic "high-risk" benign breast disease. Cancer 1990; 66: 1721-1725, Bartow SA, Pathak DR, Mettler FA et al. Breast mammographic pattern: a concatenation of confounding and breast cancer risk factors. Am J Epidemiol 1995; 142: 813-819), MD was found to be strongly correlated with the collagen and epithelial content of the breast (Li T, Sun L, Miller N et al. The association of measured breast tissue characteristics with MD and other risk factors for breast cancer. Cancer Epidemiol Biomarkers Prev 2005; 14: 343-349), and another report showed that breast epithelium was highly concentrated in the areas of collagen concentration (Hawes D, Downey S, Pearce CL et al. Dense breast stromal tissue shows greatly increased concentration of breast epithelium but no increase in its proliferative activity. Breast Cancer Res 2006; 8: R24). Collagen comprises the overwhelming majority of the FGT, occupying an area on the slides obtained from the autopsy series some 15 times the area of glandular tissue. The relationship of MD with breast cancer risk appears likely to be due to a major extent to increasing epithelial cell numbers with increasing MD. FGT is also seen in breast magnetic resonance imaging (breast MRI) and, as expected, it has been shown that this measure of FGT (MRI-FGT) is highly correlated with MD. A contrast-enhanced breast MRI shows that normal FGT 'enhances' (background parenchymal enhancement, BPE) after contrast agent is administered(Morris EA. Diagnostic breast MR imaging: current status and future directions. Radiol Clin North Am 2007; 45: 863-880, vii., Kuhl C. The current status of breast MR imaging. Part I. Choice of technique, image interpretation, diagnostic accuracy, and transfer to clinical practice. Radiology 2007; 244: 356-378), and a recent study suggests that BPE is also a major breast cancer risk factor, possibly as important as, and independent of MD (King V, Brooks JD, Bernstein JL et al. BPE at breast MR imaging and breast cancer risk. Radiology 2011; 260: 50-60). BPE is much more sensitive to the effects of menopause and tamoxifen than is FGT (King V, Gu Y, Kaplan JB et al. Impact of menopausal status on BPE and fibroglandular tissue on breast MRI. Eur Radiol 2012; 22: 2641-2647, King V, Kaplan J, Pike MC et al. Impact of tamoxifen on amount of fibroglandular tissue, BPE, and cysts on breast MRI. Breast J 2012; 18: 527-534). Changes in MD and BPE may be most useful in predicting response to chemopreventive agents aimed at blocking breast cell proliferation. More study of the biological basis of the effects of MD and BPE is needed if we are to fully exploit these factors in developing chemopreventive approaches to breast cancer. PMID:24131968

Pike, M C; Pearce, C L

2013-11-01

34

2011 Spring : Distinguished Honors Distinguished  

E-print Network

Babcock Brent Scott Distinguished Bagwell Emily Amanda Distinguished Bailey Alexandra Marie Distinguished Kimberly Marie Distinguished Beneroff Rachel Brina Distinguished Benjamin Abigail Distinguished Benson Distinguished Bernotski Vikki Lynn Distinguished Bettke Andrew Taylor Distinguished Binda Rachel Anne

Kasman, Alex

35

2009 Fall : Distinguished Honors Distinguished  

E-print Network

Merve Distinguished Albia Nathaniel J Distinguished Allen Daniel Patterson Distinguished Allen Emily M Antonnette Distinguished Barnett Naomi Stewart Distinguished Barrick Joshua David Distinguished Bartley Bell Lorin Legene Distinguished Bellamy Kara Nicole Distinguished Benjamin Abigail Distinguished

Kasman, Alex

36

ERK'2007, Portoroz, B:191-194 191 Motion correction of contrast-enhanced MRI time series of kidney  

E-print Network

ERK'2007, Portoroz, B:191-194 191 Motion correction of contrast-enhanced MRI time series of kidney In this paper we focus on motion correction of contrast enhanced kidney MRI time series, which is an important: motion correction, image registration, contrast-enhanced MRI. 1 Introduction The kidneys maintain normal

Kovacic, Stanislav

37

Contrast-enhanced MRI-guided photodynamic cancer therapy with a pegylated bifunctional polymer conjugate  

PubMed Central

Purpose To study contrast-enhanced MRI guided photodynamic therapy with a pegylated bifunctional polymer conjugate containing an MRI contrast agent and a photosensitizer for minimally invasive image-guided cancer treatment. Methods Pegylated and non-pegylated poly-(L-glutamic acid) conjugates containing mesochlorin e6, a photosensitizer, and Gd(III)-DO3A, an MRI contrast agent, were synthesized. The effect of pegylation on the biodistribution and tumor targeting was non-invasively visualized in mice bearing MDA-MB-231 tumor xenografts with MRI. MRI-guided photodynamic therapy was carried out in the tumor bearing mice. Tumor response to photodynamic therapy was evaluated by dynamic contrast enhanced MRI and histological analysis. Results The pegylated conjugate had longer blood circulation, lower liver uptake and higher tumor accumulation than the non-pegylated conjugate as shown by MRI. Site-directed laser irradiation of tumors resulted in higher therapeutic efficacy for the pegylated conjugate than the non-pegylated conjugate. Moreover, animals treated with photodynamic therapy showed reduced vascular permeability on DCE-MRI and decreased microvessel density in histological analysis. Conclusions Pegylation of the polymer bifunctional conjugates reduced non-specific liver uptake and increased tumor uptake, resulting in significant tumor contrast enhancement and high therapeutic efficacy. The pegylated poly(L-glutamic acid) bifunctional conjugate is promising for contrast enhanced MRI guided photodynamic therapy in cancer treatment. PMID:18584312

Vaidya, Anagha; Sun, Yongen; Feng, Yi; Emerson, Lyska; Jeong, Eun-Kee; Lu, Zheng-Rong

2008-01-01

38

2012 Spring : Distinguished Honors Distinguished  

E-print Network

Distinguished Baker-Whitcomb Annalise Frances Distinguished Bannister Shayna Rachel Distinguished Barber Zachary Richard Xavier Distinguished Burnham Robert Colin Distinguished Burnham-Fay Gwen Kristina Distinguished 2

Kasman, Alex

39

2011 Fall : Distinguished Honors Distinguished  

E-print Network

Distinguished Boehner Philip Scott Distinguished Bollenbacher Lynn Nicole Distinguished Bongard Rachel Suzanne Lauren Distinguished Binda Rachel Anne Distinguished Blaine Jennifer Leigh Distinguished Blake

Kasman, Alex

40

Enhancement of resting-state fcMRI networks by prior sensory stimulation.  

PubMed

It is important to consider the effect of a previous experimental condition when analyzing resting-state functional connectivity magnetic resonance imaging (fcMRI) data. In this work, a simple sensory stimulation functional MRI (fMRI) experiment was conducted between two resting-state fcMRI acquisitions in anesthetized rats using a high-field small-animal MR scanner. Previous human studies have reported fcMRI network alteration by prior task/stimulus utilizing similar experimental paradigms. An anesthetized rat preparation was used to test whether brain regions with higher level functions are involved in post-task/stimulus fcMRI network alteration. We demonstrate significant fcMRI enhancement poststimulation in the sensory cortical, limbic, and insular brain regions in rats. These brain regions have been previously implicated in vigilance and anesthetic arousal networks. We tested their experimental paradigm in several inbred strains of rats with known phenotypic differences in anesthetic susceptibility and cerebral vascular function. Brown Norway (BN), Dahl Salt-Sensitive (SS), and consomic SSBN13 strains were tested. We have previously shown significant differences in blood oxygen level-dependent fMRI activity and fcMRI networks across these strains. Here we report statistically significant interstrain differences in regional fcMRI poststimulation enhancement. In the SS strain, poststimulation enhancement occurred in posterior sensory and limbic cortical brain regions. In the BN strain, poststimulation enhancement appeared in anterior cingulate and subcortical limbic brain regions. These results imply that a prior condition has a significant impact on fcMRI networks that depend on intersubject difference in genetics and physiology. PMID:25387238

Li, Chenxuan; Li, Zhixin; Ward, B Douglas; Dwinell, Melinda R; Lombard, Julian H; Hudetz, Anthony G; Pawela, Christopher P

2014-11-01

41

Temporomandibular joint (TMJ) pain revisited with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)  

Microsoft Academic Search

PurposeWe aimed to assess the contrast enhancement patterns of the retrodiscal tissue with dynamic contrast-enhanced MR imaging (DCE-MRI) with respect to different temporomandibular joint disc pathologies. Additionally, we questioned the relationship between the temporomandibular joint (TMJ) pain and the contrast enhancement pattern of the retrodiscal tissue regardless of the TMJ disc position.

N. Tasali; R. Cubuk; M. Aricak; M. Ozarar; B. Saydam; H. Nur; N. Tuncbilek

42

Improving Bladder Cancer Imaging Using 3T Functional Dynamic Contrast-Enhanced MRI  

PubMed Central

Objectives To assess the capability of T2-weighted MRI (T2W-MRI) and the additional diagnostic value of Dynamic Contrast-Enhanced MRI (DCE-MRI) using multi-transmit 3T in the localization of bladder cancer. Materials and Methods This prospective study was approved by the local Institutional Review Board. Thirty–six patients were included in the study and provided informed consent. MRI scans were performed with T2W-MRI and DCE-MRI on a 3T multi-transmit system. Two observers (with 12 and 25 years of experience) independently interpreted T2W-MRI prior to DCE-MRI data (maps of pharmacokinetic parameters) to localize bladder tumors. The pathological examination of cystectomy bladder specimens was used as a reference gold standard. The McNemar test was performed to evaluate the differences in sensitivity, specificity, and accuracy. Kappa scores were calculated to assess interobserver agreement. Results The sensitivity, specificity, and accuracy of the localization with T2W-MRI alone were 81% (29/36), 63% (5/8) and 77% (34/44) for observer 1, and 72% (26/36), 63% (5/8), and 70% (31/44) for observer 2. With additional DCE-MRI available, these values were 92% (33/36), 75% (6/8), and 89% (39/44) for observer 1, and 92% (33/36), 63% (5/8), and 86% (38/44) for observer 2. DCE-MRI significantly (P < 0.01) improved the sensitivity and accuracy for observer 2. For the twenty-three patients treated with chemotherapy, DCE-MRI also significantly (P < 0.02) improved the sensitivity and accuracy of bladder cancer localization with T2W-MRI alone for observer 2. Kappa scores were 0.63 for T2W-MRI alone, and 0.78 for additional DCE-MRI. Out of seven sub-centimeter malignant tumors, four (57%) were identified on T2W images and six (86%) on DCE maps. Out of eleven malignant tumors within the bladder wall thickening, six (55%) were found on T2W images and ten (91%) on DCE maps. Conclusions Compared to conventional T2W-MRI alone, the addition of DCE-MRI improved interobserver agreement as well as the localization of small malignant tumors and those within bladder wall thickening. PMID:24637583

Nguyen, Huyen T.; Pohar, Kamal S.; Jia, Guang; Shah, Zarine K.; Mortazavi, Amir; Zynger, Debra L.; Wei, Lai; Clark, Daniel; Yang, Xiangyu; Knopp, Michael V.

2015-01-01

43

Human Tumor Cell Proliferation Evaluated Using Manganese-Enhanced MRI  

PubMed Central

Background Tumor cell proliferation can depend on calcium entry across the cell membrane. As a first step toward the development of a non-invasive test of the extent of tumor cell proliferation in vivo, we tested the hypothesis that tumor cell uptake of a calcium surrogate, Mn2+ [measured with manganese-enhanced MRI (MEMRI)], is linked to proliferation rate in vitro. Methodology/Principal Findings Proliferation rates were determined in vitro in three different human tumor cell lines: C918 and OCM-1 human uveal melanomas and PC-3 prostate carcinoma. Cells growing at different average proliferation rates were exposed to 1 mM MnCl2 for one hour and then thoroughly washed. MEMRI R1 values (longitudinal relaxation rates), which have a positive linear relationship with Mn2+ concentration, were then determined from cell pellets. Cell cycle distributions were determined using propidium iodide staining and flow cytometry. All three lines showed Mn2+-induced increases in R1 compared to cells not exposed to Mn2+. C918 and PC-3 cells each showed a significant, positive correlation between MEMRI R1 values and proliferation rate (p?0.005), while OCM-1 cells showed no significant correlation. Preliminary, general modeling of these positive relationships suggested that pellet R1 for the PC-3 cells, but not for the C918 cells, could be adequately described by simply accounting for changes in the distribution of the cell cycle-dependent subpopulations in the pellet. Conclusions/Significance These data clearly demonstrate the tumor-cell dependent nature of the relationship between proliferation and calcium influx, and underscore the usefulness of MEMRI as a non-invasive method for investigating this link. MEMRI is applicable to study tumors in vivo, and the present results raise the possibility of evaluating proliferation parameters of some tumor types in vivo using MEMRI. PMID:22363447

Braun, Rod D.; Bissig, David; North, Robert; Vistisen, Kerry S.; Berkowitz, Bruce A.

2012-01-01

44

Major mouse placental compartments revealed by diffusion-weighted MRI, contrast-enhanced MRI, and fluorescence imaging  

PubMed Central

Mammalian models, and mouse studies in particular, play a central role in our understanding of placental development. Magnetic resonance imaging (MRI) could be a valuable tool to further these studies, providing both structural and functional information. As fluid dynamics throughout the placenta are driven by a variety of flow and diffusion processes, diffusion-weighted MRI could enhance our understanding of the exchange properties of maternal and fetal blood pools—and thereby of placental function. These studies, however, have so far been hindered by the small sizes, the unavoidable motions, and the challenging air/water/fat heterogeneities, associated with mouse placental environments. The present study demonstrates that emerging methods based on the spatiotemporal encoding (SPEN) of the MRI information can robustly overcome these obstacles. Using SPEN MRI in combination with albumin-based contrast agents, we analyzed the diffusion behavior of developing placentas in a cohort of mice. These studies successfully discriminated the maternal from the fetal blood flows; the two orders of magnitude differences measured in these fluids’ apparent diffusion coefficients suggest a nearly free diffusion behavior for the former and a strong flow-based component for the latter. An intermediate behavior was observed by these methods for a third compartment that, based on maternal albumin endocytosis, was associated with trophoblastic cells in the interphase labyrinth. Structural features associated with these dynamic measurements were consistent with independent intravital and ex vivo fluorescence microscopy studies and are discussed within the context of the anatomy of developing mouse placentas. PMID:24969421

Solomon, Eddy; Avni, Reut; Hadas, Ron; Raz, Tal; Garbow, Joel Richard; Bendel, Peter; Frydman, Lucio; Neeman, Michal

2014-01-01

45

MRI, Enhanced CT, and FDG PET/CT in Primary Retroperitoneal Mucinous Cystadenocarcinoma.  

PubMed

Primary retroperitoneal mucinous cystadenocarcinoma (PRMC) is an extremely rare neoplasm. We present a case of PRMC with MRI, enhanced CT, and FDG PET/CT findings. Abdominal MRI showed a cystic lesion in the retroperitoneum with a mural nodule. The mural nodule showed progressive enhancement on enhanced CT and intense FDG uptake on early PET/CT with increased SUVmax on delayed PET/CT. Laparoscopy was performed. Retroperitoneal mucinous cystadenocarcinoma was confirmed histopathologically. Metastasis from gastrointestinal tract or ovary was excluded. This case indicates, although rare, PRMC should be considered when a hypermetabolic retroperitoneal cystic lesion with bilateral normal ovaries is found on FDG PET/CT. PMID:24445275

Dong, Aisheng; Zhai, Zhijun; Wang, Yang; Zuo, Changjing

2015-01-01

46

MRI-guided gas bubble enhanced ultrasound heating in in vivo rabbit thigh  

Microsoft Academic Search

In this study, we propose a focused ultrasound surgery protocol that induces and then uses gas bubbles at the focus to enhance the ultrasound absorption and ultimately create larger lesions in vivo. MRI and ultrasound visualization and monitoring methods for this heating method are also investigated. Larger lesions created with a carefully monitored single ultrasound exposure could greatly improve the

S. D. Sokka; R. King; K. Hynynen

2003-01-01

47

Interactive detection and visualization of breast lesions from dynamic contrast enhanced MRI volumes  

Microsoft Academic Search

Mammography is currently regarded as the most effective and widely used method for early detection of breast cancer, but recently its sensitivity in certain high risk cases has been less than desired. The use of Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI) has gained considerable attention in the past 10 years, especially for high risk cases, for smaller multi-focal lesions,

Kalpathi R. Subramanian; John P. Brockway; William B. Carruthers

48

USPIO-Enhanced Dynamic MRI: Evaluation of Normal and Transplanted Rat Kidneys  

E-print Network

.0­18.1 mg Fe/kg/body weight). All animals underwent 128 consecutive snapshot fast low-angle shot (FLASHUSPIO-Enhanced Dynamic MRI: Evaluation of Normal and Transplanted Rat Kidneys Dewen Yang,1 Qing Ye, 40 normal rats (20 Dark Agouti (DA) rats and 20 Brown Norway (BN) rats) and 16 transplanted rats (12

Moura, José

49

Assessment of liver function in primary biliary cirrhosis using Gd-EOB-DTPA-enhanced liver MRI  

PubMed Central

Objectives Gd-EOB-DTPA (gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid) is a gadolinium-based hepatocyte-specific contrast agent for magnetic resonance imaging (MRI). The aim of this study was to determine whether the hepatic uptake and excretion of Gd-EOB-DTPA differ between patients with primary biliary cirrhosis (PBC) and healthy controls, and whether differences could be quantified. Methods Gd-EOB-DTPA-enhanced liver MRI was performed in 20 healthy volunteers and 12 patients with PBC. The uptake of Gd-EOB-DTPA was assessed using traditional semi-quantitative parameters (Cmax, Tmax and T1/2), as well as model-free parameters derived after deconvolutional analysis (hepatic extraction fraction [HEF], input-relative blood flow [irBF] and mean transit time [MTT]). In each individual, all parameters were calculated for each liver segment and the median of the segmental values was used to define a global liver median (GLM). Results Although the PBC patients had relatively mild disease according to their Model for End-stage Liver Disease (MELD), Child–Pugh and Mayo risk scores, they had significantly lower HEF and shorter MTT values compared with the healthy controls. These differences significantly increased with increasing MELD and Child–Pugh scores. Conclusions Dynamic hepatocyte-specific contrast-enhanced MRI (DHCE-MRI) has a potential role as an imaging-based liver function test. The high spatial resolution of MRI enables hepatic function to be assessed on segmental and sub-segmental levels. PMID:20887325

Nilsson, Henrik; Blomqvist, Lennart; Douglas, Lena; Nordell, Anders; Jonas, Eduard

2010-01-01

50

Relationship of MRI Delayed Contrast Enhancement to Irreversible Injury, Infarct Age, and Contractile Function  

Microsoft Academic Search

Background—Contrast MRI enhancement patterns in several pathophysiologies resulting from ischemic myocardial injury are controversial or have not been investigated. We compared contrast enhancement in acute infarction (AI), after severe but reversible ischemic injury (RII), and in chronic infarction. Methods and Results—In dogs, a large coronary artery was occluded to study AI and\\/or chronic infarction (n 518), and a second coronary

Raymond J. Kim; David S. Fieno; Todd B. Parrish; Kathleen Harris; Enn-Ling Chen; Orlando Simonetti; Jeffrey Bundy; J. Paul Finn; Francis J. Klocke; Robert M. Judd

51

Randomized multicentre trial of gadoxetic acid-enhanced MRI versus conventional MRI or CT in the staging of colorectal cancer liver metastases  

PubMed Central

Background This multicentre international randomized trial compared the impact of gadoxetic acid-enhanced magnetic resonance imaging (MRI), MRI with extracellular contrast medium (ECCM-MRI) and contrast-enhanced computed tomography (CE-CT) as a first-line imaging method in patients with suspected colorectal cancer liver metastases (CRCLM). Methods Between October 2008 and September 2010, patients with suspected CRCLM were randomized to one of the three imaging modalities. The primary endpoint was the proportion of patients for whom further imaging after initial imaging was required for a confident diagnosis. Secondary variables included confidence in the therapeutic decision, intraoperative deviations from the initial imaging-based surgical plan as a result of additional operative findings, and diagnostic efficacy of the imaging modalities versus intraoperative and pathological extent of the disease. Results A total of 360 patients were enrolled. Efficacy was analysed in 342 patients (118, 112 and 112 with gadoxetic acid-enhanced MRI, ECCM-MRI and CE-CT respectively as the initial imaging procedure). Further imaging was required in 0 of 118, 19 (17·0 per cent) of 112 and 44 (39·3 per cent) of 112 patients respectively (P < 0·001). Diagnostic confidence was high or very high in 98·3 per cent of patients for gadoxetic acid-enhanced MRI, 85·7 per cent for ECCM-MRI and 65·2 per cent for CE-CT. Surgical plans were changed during surgery in 28, 32 and 47 per cent of patients in the respective groups. Conclusion The diagnostic performance of gadoxetic acid-enhanced MRI was better than that of CE-CT and ECCM-MRI as the initial imaging modality. No further imaging was needed in the gadoxetic acid-enhanced MRI group and comparison of diagnostic efficacy parameters demonstrated the diagnostic superiority of gadoxetic acid-enhanced MRI. Registration number: NCT00764621( http://clinicaltrials.gov ); EudraCT number: 2008-000583-16 ( https://eudract.ema.europa.eu/ ). PMID:24652690

Zech, C J; Korpraphong, P; Huppertz, A; Denecke, T; Kim, M-J; Tanomkiat, W; Jonas, E; Ba-Ssalamah, A

2014-01-01

52

Dynamic contrast-enhanced MRI in clinical trials of antivascular therapies  

Microsoft Academic Search

About 100 early-phase clinical trials and investigator-led studies of targeted antivascular therapies—both anti-angiogenic and vascular-targeting agents—have reported data derived from T1-weighted dynamic contrast-enhanced (DCE)-MRI. However, the role of DCE-MRI for decision making during the drug-development process remains controversial. Despite well-documented guidelines on image acquisition and analysis, several key questions concerning the role of this technique in early-phase trial design remain

Alan Jackson; Geoff J. M. Parker; Caleb Roberts; Gordon C. Jayson; James P. B. O'Connor

2012-01-01

53

MRI  

NSDL National Science Digital Library

This patient education program explains Magnetic Resonance Imaging (MRI), the role of this imaging in diagnosis, the procedure itself, and associated benefits and risks. This is a MedlinePlus Interactive Health Tutorial from the National Library of Medicine, designed and developed by the Patient Education Institute. NOTE: The tutorial requires a special Flash plug-in, version 4 or above. If you do not have Flash, you will be prompted to obtain a free download of the software before you start the tutorial. You will also need an Acrobat Reader, available as a free download, in order to view the Reference Summary.

Patient Education Institute

54

PSMA-targeting iron oxide magnetic nanoparticles enhance MRI of preclinical prostate cancer.  

PubMed

Aim: To evaluate the potential of newly-developed, biocompatible iron oxide magnetic nanoparticles (MNPs) conjugated with J591, an antibody to an extracellular epitope of PSMA, to enhance MRI of prostate cancer. Materials & methods: Specific binding to PSMA by J591-MNP was investigated in vitro. MRI studies were performed on orthotopic tumor-bearing NOD.SCID mice 2 h and 24 h after intravenous injection of J591-MNPs, or non-targeting MNPs. Results & conclusion: In vitro, MNPs did not affect prostate cancer cell viability, and conjugation to J591 did not compromise antibody specificity and enhanced cellular iron uptake. Magnetic resonance contrast of tumors was increased in vivo using PSMA-targeting MNPs, but not by non-targeting MNPs. This provides proof-of-concept that PSMA-targeting MNPs have potential to enhance magnetic resonance detection/localization of prostate cancer. PMID:25407827

Tse, Brian Wan-Chi; Cowin, Gary J; Soekmadji, Carolina; Jovanovic, Lidija; Vasireddy, Raja S; Ling, Ming-Tat; Khatri, Aparajita; Liu, Tianqing; Thierry, Benjamin; Russell, Pamela J

2014-11-19

55

Novel kinetic texture features for breast lesion classification on dynamic contrast enhanced (DCE) MRI  

NASA Astrophysics Data System (ADS)

Dynamic contrast enhanced (DCE) MRI has emerged as a promising new imaging modality for breast cancer screening. Currently, radiologists evaluate breast lesions based on qualitative description of lesion morphology and contrast uptake profiles. However, the subjectivity associated with qualitative description of breast lesions on DCE-MRI introduces a high degree of inter-observer variability. In addition, the high sensitivity of MRI results in poor specificity and thus a high rate of biopsies on benign lesions. Computer aided diagnosis (CAD) methods have been previously proposed for breast MRI, but research in the field is far from comprehensive. Most previous work has focused on either quantifying morphological attributes used by radiologists, characterizing lesion intensity profiles which reflect uptake of contrast dye, or characterizing lesion texture. While there has been much debate on the relative importance of the different classes of features (e.g., morphological, textural, and kinetic), comprehensive quantitative comparisons between the different lesion attributes have been rare. In addition, although kinetic signal enhancement curves may give insight into the underlying physiology of the lesion, signal intensity is susceptible to MRI acquisition artifacts such as bias field and intensity non-standardness. In this paper, we introduce a novel lesion feature that we call the kinetic texture feature, which we demonstrate to be superior compared to the lesion intensity profile dynamics. Our hypothesis is that since lesion intensity is susceptible to artifacts, lesion texture changes better reflect lesion class (benign or malignant). In this paper, we quantitatively demonstrate the superiority of kinetic texture features for lesion classification on 18 breast DCE-MRI studies compared to over 500 different morphological, kinetic intensity, and lesion texture features. In conjunction with linear and non-linear dimensionality reduction methods, a support vector machine (SVM) classifier yielded classification accuracy and positive predictive values of 78% and 86% with kinetic texture features compared to 78% and 73% with morphological features and 72% and 83% with textural features, respectively.

Agner, Shannon C.; Soman, Salil; Libfeld, Edward; McDonald, Margie; Rosen, Mark A.; Schnall, Mitchell D.; Chin, Deanna; Nosher, John; Madabhushi, Anant

2008-03-01

56

Cardiac Amyloidosis: Typical Imaging Findings and Diffuse Myocardial Damage Demonstrated by Delayed Contrast-Enhanced MRI  

SciTech Connect

Amyloidosis is a rare systemic disease. However, involvement of the heart is a common finding and is the most frequent cause of death in amyloidosis. We report the sonographic, scintigraphic, and MRI features of a pathologically proven case of cardiac amyloidosis. Delayed contrast-enhanced MR images, using an inversion recovery prepped gradient-echo sequence, revealed diffuse enhancement in the wall of both left and right ventricles. This enhancement suggested expansion of the extracellular space of the myocardium caused by diffuse myocardial necrosis secondary to deposition of amyloid.

Sueyoshi, Eijun, E-mail: EijunSueyoshi@aol.com; Sakamoto, Ichiro; Okimoto, Tomoaki; Hayashi, Kuniaki [Nagasaki University School of Medicine, Department of Radiology (Japan); Tanaka, Kyouei; Toda, Genji [Nagasaki University School of Medicine, Department of Cardiology (Japan)

2006-08-15

57

Dynamic Contrast-Enhanced MRI of Cervical Cancers: Temporal Percentile Screening of Contrast Enhancement Identifies Parameters for Prediction of Chemoradioresistance  

SciTech Connect

Purpose: To systematically screen the tumor contrast enhancement of locally advanced cervical cancers to assess the prognostic value of two descriptive parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Methods and Materials: This study included a prospectively collected cohort of 81 patients who underwent DCE-MRI with gadopentetate dimeglumine before chemoradiotherapy. The following descriptive DCE-MRI parameters were extracted voxel by voxel and presented as histograms for each time point in the dynamic series: normalized relative signal increase (nRSI) and normalized area under the curve (nAUC). The first to 100th percentiles of the histograms were included in a log-rank survival test, resulting in p value and relative risk maps of all percentile-time intervals for each DCE-MRI parameter. The maps were used to evaluate the robustness of the individual percentile-time pairs and to construct prognostic parameters. Clinical endpoints were locoregional control and progression-free survival. The study was approved by the institutional ethics committee. Results: The p value maps of nRSI and nAUC showed a large continuous region of percentile-time pairs that were significantly associated with locoregional control (p < 0.05). These parameters had prognostic impact independent of tumor stage, volume, and lymph node status on multivariate analysis. Only a small percentile-time interval of nRSI was associated with progression-free survival. Conclusions: The percentile-time screening identified DCE-MRI parameters that predict long-term locoregional control after chemoradiotherapy of cervical cancer.

Andersen, Erlend K.F. [Department of Medical Physics, Oslo University Hospital, Oslo (Norway); Hole, Knut Hakon; Lund, Kjersti V. [Department of Radiology, Oslo University Hospital, Oslo (Norway); Sundfor, Kolbein [Department of Gynaecological Oncology, Oslo University Hospital, Oslo (Norway); Kristensen, Gunnar B. [Department of Gynaecological Oncology, Oslo University Hospital, Oslo (Norway); Institute for Medical Informatics, Oslo University Hospital, Oslo (Norway); Lyng, Heidi [Department of Radiation Biology, Oslo University Hospital, Oslo (Norway); Malinen, Eirik, E-mail: eirik.malinen@fys.uio.no [Department of Medical Physics, Oslo University Hospital, Oslo (Norway); Department of Physics, University of Oslo, Oslo (Norway)

2012-03-01

58

Standardization of radiological evaluation of dynamic contrast enhanced MRI: application in breast cancer diagnosis.  

PubMed

Dynamic contrast enhanced MRI is applied as an adjuvant tool for breast cancer detection, diagnosis, and follow-up of therapy. Despite improvements through the years in achieving higher spatial and temporal resolution, it still suffers from lack of scanning and processing standardization, and consequently, high variability in the radiological evaluation, particularly differentiating malignant from benign lesions. We describe here a hybrid method for achieving standardization of the radiological evaluation of breast dynamic contrast enhanced (DCE)-magnetic resonance imaging (MRI) protocols, based on integrating the model based three time point (3TP) method with principal component analysis (PCA). The scanning and image processing procedures consisted of three main steps: 1. 3TP standardization of the MRI acquisition parameters according to a kinetic model, 2. Applying PCA to test cases and constructing an eigenvectors' base related to the contrast-enhancement kinetics and 3. Projecting all new cases on the eigenvectors' base and evaluating the clinical outcome. Datasets of overall 96 malignant and 26 benign breast lesions were recorded on 1.5T and 3T scanners, using three different MRI acquisition parameters optimized by the 3TP method. The final radiological evaluation showed similar detection and diagnostic ability for the three different MRI acquisition parameters. The area under the curve of receiver operating characteristic analysis yielded a value of 0.88 ± 0.034 for differentiating malignant from benign lesions. This 3TP+PCA hybrid method is fast and can be readily applied as a computer aided diagnostic tool of breast cancer. The underlying principles of this method can be extended to standardize the evaluation of malignancies in other organs. PMID:24000989

Furman-Haran, E; Feinberg, M Shapiro; Badikhi, D; Eyal, E; Zehavi, T; Degani, H

2014-10-01

59

Voluntary Enhancement of Neural Signatures of Affiliative Emotion Using fMRI Neurofeedback  

PubMed Central

In Ridley Scott’s film “Blade Runner”, empathy-detection devices are employed to measure affiliative emotions. Despite recent neurocomputational advances, it is unknown whether brain signatures of affiliative emotions, such as tenderness/affection, can be decoded and voluntarily modulated. Here, we employed multivariate voxel pattern analysis and real-time fMRI to address this question. We found that participants were able to use visual feedback based on decoded fMRI patterns as a neurofeedback signal to increase brain activation characteristic of tenderness/affection relative to pride, an equally complex control emotion. Such improvement was not observed in a control group performing the same fMRI task without neurofeedback. Furthermore, the neurofeedback-driven enhancement of tenderness/affection-related distributed patterns was associated with local fMRI responses in the septohypothalamic area and frontopolar cortex, regions previously implicated in affiliative emotion. This demonstrates that humans can voluntarily enhance brain signatures of tenderness/affection, unlocking new possibilities for promoting prosocial emotions and countering antisocial behavior. PMID:24847819

Moll, Jorge; Weingartner, Julie H.; Bado, Patricia; Basilio, Rodrigo; Sato, João R.; Melo, Bruno R.; Bramati, Ivanei E.; de Oliveira-Souza, Ricardo; Zahn, Roland

2014-01-01

60

Quantitative Evaluation of Enhancement Patterns in Focal Solid Liver Lesions with Gd-EOB-DTPA-Enhanced MRI  

PubMed Central

Purpose The objective was to investigate the dynamic enhancement patterns in focal solid liver lesions after the administration of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) by means of dynamic magnetic resonance imaging (MRI) including hepatobiliary phase (HP) images 20 min after Gd-EOB-DTPA administration. Materials and Methods Non-enhanced T1/T2-weighted as well as dynamic magnetic resonance (MR) images during the arterial phase (AP), the portal venous phase (PVP), the late phase (LP), and the HP (20 min) were obtained from 83 patients (54 male, 29 female, mean age 62.01 years) with focal solid liver lesions. MRI was conducted by means of a 1.5-T system for 63 patients with malignant liver lesions (HCCs: n?=?34, metastases: n?=?29) and for 20 patients with benign liver lesions (FNH lesions: n?=?14, hemangiomas: n?=?3, adenomas: n?=?3). For quantitative analysis, signal-to-noise ratios (SNR), contrast enhancement ratios (CER), lesion-to-liver contrast ratios (LLC), and signal intensity (SI) ratios were measured. Results The SNR of liver parenchyma significantly increased in each dynamic phase after Gd-EOB-DTPA administration compared to the SNR of non-enhanced images (p<0.001). The CER of HCCs and metastases significantly decreased between LP and HP images (p?=?0.0011, p<0.0001). However, FNH lesions did not show any significant difference, whereas an increased CER was found in hemangiomas. The mean LLCs of FNH lesions were significantly higher than those of HCCs and metastases. The LLC values of hemangiomas remained negative during the entire time course, whereas the LLC of adenomas indicated hyperintensity from the AP to the LP. Furthermore, adenomas showed hypointensity in HP images. Conclusion Gd-EOB-DTPA-enhanced MRI may help diagnose focal solid liver lesions by evaluating their enhancement patterns. PMID:24950259

Haimerl, Michael; Wächtler, Max; Zeman, Florian; Verloh, Niklas; Platzek, Ivan; Schreyer, Andreas Georg; Stroszczynski, Christian; Wiggermann, Philipp

2014-01-01

61

Gadolinium-enhanced dynamic MRI of the fractured carpal scaphoid: preliminary results.  

PubMed

The aim of the present report was to evaluate the vascularity of fracture fragments of the fractured carpal scaphoid in the acute (< 4 weeks) and chronic (> 3 months) phases using a gadolinium-enhanced dynamic MRI sequence. Eight patients with acute scaphoid fractures, six patients with chronic scaphoid fractures, and three control patients without fractures were evaluated using a T1-weighted fast spoiled gradient recalled acquisition (fSPGR) sequence with gadolinium-DTPA enhancement (0.1 mmol/kg bodyweight). Signal intensity over time plots were obtained using region of interest measurements from both fracture fragments. Enhancement factors (EF) were then calculated from the plots. No enhancement of the scaphoid was seen in control subjects (EF: distal scaphoid pole 1.04 +/- 0.01, proximal pole 1.07 +/- 0.08). In acute fracture patients, enhancement of the distal pole was greater than that of the proximal in all cases but one in which the two poles enhanced in a similar fashion (EF: distal 1.99 +/- 0.77, proximal 1.43 +/- 0.99). In chronic fracture patients the enhancement pattern was reversed, as the proximal pole enhanced to a greater degree than the distal with the exception of one case where both poles enhanced equally (EF: distal 1.74 +/- 0.52, proximal 2.64 +/- 0.50). Using a two-tailed non-parametric Mann-Whitney U-test, the difference in enhancement of the proximal poles between the acute and chronic groups was found to be highly significant (P < 0.003). Dynamic contrast-enhanced (fSPGR) MRI demonstrates significant differences in the enhancement patterns of the scaphoid when chronic and acute fractures are compared. PMID:9509596

Munk, P L; Lee, M J; Janzen, D L; Vellet, A D; Connell, D G; Poon, P Y; Logan, P M; Favero, K J; Struk, D

1998-02-01

62

Casein-coated Iron Oxide Nanoparticles for High MRI Contrast Enhancement and Efficient Cell Targeting  

PubMed Central

Surface properties, as well as inherent physicochemical properties, of the engineered nanomaterials play important roles in their interactions with the biological systems, which eventually affect their efficiency in diagnostic and therapeutic applications. Here we report a new class MRI contrast agent based on milk casein protein coated iron oxide nanoparticles (CNIOs) with a core size of 15 nm and hydrodynamic diameter ~30 nm. These CNIOs exhibited excellent water-solubility, colloidal stability, and biocompatibility. Importantly, CNIOs exhibited prominent T2 enhancing capability with a transverse relaxivity r2 of 273 mM?1s?1 at 3 Tesla. The transverse relaxivity is ~2.5-fold higher than that of iron oxide nanoparticles with the same core but an amphiphilic polymer coating. CNIOs showed pH-responsive properties, formed loose and soluble aggregates near the pI (pH~4.0). The aggregates could be dissociated reversibly when the solution pH was adjusted away from the pI. The transverse relaxation property and MRI contrast enhancing effect of CNIOs remained unchanged in the pH range of 2.0 to 8.0. Further functionalization of CNIOs can be achieved via surface modification of the protein coating. Bio-affinitive ligands, such as a single chain fragment from the antibody of epidermal growth factor receptor (ScFvEGFR), could be readily conjugated onto the protein coating, enabling specific targeting to MDA-MB-231 breast cancer cells over-expressing EGFR. T2-weighted MRI of mice intravenously administered with CNIOs demonstrated strong contrast enhancement in the liver and spleen. These favorable properties suggest CNIOs as a class of biomarker targeted magnetic nanoparticles for MRI contrast enhancement and related biomedical applications. PMID:23633522

Huang, Jing; Wang, Liya; Lin, Run; Wang, Andrew Y.; Yang, Lily; Kuang, Min; Qian, Weiping; Mao, Hui

2013-01-01

63

Tracer kinetic modelling of tumour angiogenesis based on dynamic contrast-enhanced CT and MRI measurements  

Microsoft Academic Search

Purpose  Technical developments in both magnetic resonance imaging (MRI) and computed tomography (CT) have helped to reduce scan times\\u000a and expedited the development of dynamic contrast-enhanced (DCE) imaging techniques. Since the temporal change of the image\\u000a signal following the administration of a diffusible, extracellular contrast agent (CA) is related to the local blood supply\\u000a and the extravasation of the CA into

Gunnar Brix; Jürgen Griebel; Fabian Kiessling; Frederik Wenz

2010-01-01

64

Precision analysis of kinetic modelling estimates in dynamic contrast enhanced MRI  

Microsoft Academic Search

Object  Dynamic contrast enhanced MRI and pharmacokinetic modelling provide a powerful tool for tumour diagnosis and treatment evaluation.\\u000a However, several studies show low reproducibility of the technique and poor precision of the transendothelial transfer constant\\u000a K\\u000a trans. This work proposes a theoretical framework describing how finite signal-noise-ratio (SNR) in the MR images is propagated\\u000a throughout the measurement protocol to uncertainty on

Dieter De Naeyer; Yves De Deene; Wim P. Ceelen; Patrick Segers; Pascal Verdonck

2011-01-01

65

Casein-coated iron oxide nanoparticles for high MRI contrast enhancement and efficient cell targeting.  

PubMed

Surface properties, as well as inherent physicochemical properties, of the engineered nanomaterials play important roles in their interactions with the biological systems, which eventually affect their efficiency in diagnostic and therapeutic applications. Here we report a new class of MRI contrast agent based on milk casein protein-coated iron oxide nanoparticles (CNIOs) with a core size of 15 nm and hydrodynamic diameter ~30 nm. These CNIOs exhibited excellent water-solubility, colloidal stability, and biocompatibility. Importantly, CNIOs exhibited prominent T2 enhancing capability with a transverse relaxivity r2 of 273 mM(-1) s(-1) at 3 tesla. The transverse relaxivity is ~2.5-fold higher than that of iron oxide nanoparticles with the same core but an amphiphilic polymer coating. CNIOs showed pH-responsive properties, formed loose and soluble aggregates near the pI (pH ~4.0). The aggregates could be dissociated reversibly when the solution pH was adjusted away from the pI. The transverse relaxation property and MRI contrast enhancing effect of CNIOs remained unchanged in the pH range of 2.0-8.0. Further functionalization of CNIOs can be achieved via surface modification of the protein coating. Bioaffinitive ligands, such as a single chain fragment from the antibody of epidermal growth factor receptor (ScFvEGFR), could be readily conjugated onto the protein coating, enabling specific targeting to MDA-MB-231 breast cancer cells overexpressing EGFR. T2-weighted MRI of mice intravenously administered with CNIOs demonstrated strong contrast enhancement in the liver and spleen. These favorable properties suggest CNIOs as a class of biomarker targeted magnetic nanoparticles for MRI contrast enhancement and related biomedical applications. PMID:23633522

Huang, Jing; Wang, Liya; Lin, Run; Wang, Andrew Y; Yang, Lily; Kuang, Min; Qian, Weiping; Mao, Hui

2013-06-12

66

Focal nodular hyperplasia of the liver: detection and characterization with plain and dynamic-enhanced MRI  

Microsoft Academic Search

Background: We compared nonenhanced and dynamic gadolinium (Gd)–enhanced magnetic resonance imaging (MRI) appearances of hepatic focal\\u000a nodular hyperplasia (FNH) as depicted with breath-hold MR sequences and assessed the detectability of the individual MR sequences\\u000a used. Methods: We retrospectively reviewed 48 consecutive patients with FNH. All patients underwent nonenhanced (T1 fast low-angle shot\\u000a [FLASH] and T2 half-Fourier acquisition [HASTE]) and dynamic

K. J. Mortelé; M. Praet; H. Van Vlierberghe; B. de Hemptinne; K. Zou; P. R. Ros

2002-01-01

67

Assessment of blood–brain barrier disruption using dynamic contrast-enhanced MRI. A systematic review  

PubMed Central

There is increasing recognition of the importance of blood–brain barrier (BBB) disruption in aging, dementia, stroke and multiple sclerosis in addition to more commonly-studied pathologies such as tumors. Dynamic contrast-enhanced MRI (DCE-MRI) is a method for studying BBB disruption in vivo. We review pathologies studied, scanning protocols and data analysis procedures to determine the range of available methods and their suitability to different pathologies. We systematically review the existing literature up to February 2014, seeking studies that assessed BBB integrity using T1-weighted DCE-MRI techniques in animals and humans in normal or abnormal brain tissues. The literature search provided 70 studies that were eligible for inclusion, involving 417 animals and 1564 human subjects in total. The pathologies most studied are intracranial neoplasms and acute ischemic strokes. There are large variations in the type of DCE-MRI sequence, the imaging protocols and the contrast agents used. Moreover, studies use a variety of different methods for data analysis, mainly based on model-free measurements and on the Patlak and Tofts models. Consequently, estimated KTrans values varied widely. In conclusion, DCE-MRI is shown to provide valuable information in a large variety of applications, ranging from common applications, such as grading of primary brain tumors, to more recent applications, such as assessment of subtle BBB dysfunction in Alzheimer's disease. Further research is required in order to establish consensus-based recommendations for data acquisition and analysis and, hence, improve inter-study comparability and promote wider use of DCE-MRI. PMID:25379439

Heye, Anna K.; Culling, Ross D.; Valdés Hernández, Maria del C.; Thrippleton, Michael J.; Wardlaw, Joanna M.

2014-01-01

68

Lack of nephrotoxicity of gadopentetate dimeglumine-enhanced non-vascular MRI and MRI without contrast agent in patients at high-risk for acute kidney injury  

PubMed Central

Background Gadolinium chelates (GCs) have been traditionally considered as non-nephrotoxic magnetic resonance imaging (MRI) contrast materials. However, it has been suggested in some recent articles that GCs may have a nephrotoxic potential, but most of these reports are retrospective. However, the evaluated contrast agents, their doses, and the tests used to determine the kidney function were not consistent across studies. We aimed to investigate the effect of magnetic field and an MRI contrast agent, gadopentetate dimeglumine (GD), on renal functions in patients at high risk for acute kidney injury (AKI). Material/Methods We designed a prospective case-control study with 2 age- and sex-matched groups of patients at high-risk for AKI (n=72 for each group). Patients in Group 1 received a fixed dose of (0.2 mmol/kg) GD-enhanced non-vascular MRI and patients in Group 2 received MRI without GD. Before the MRI and at 6, 24, 72, and 168 hours after the MRI, biochemical tests, estimated glomerular filtration rate (eGFR), albumin/creatinine ratio in spot urine, and early AKI biomarkers (cystatin C, N-Acetyl-Glucosaminidase [NAG], Neutrophil gelatinase-associated lipocalin [NGAL]) were measured. Results Serum creatinine, albumin/creatinine ratio, and eGFR were not different between Group 1 and 2 (p>0.05). There were no significant changes in renal function tests and AKI biomarkers (?serum creatinine, ?albumin/creatinine ratio, ?GFR, ?cystatin C, ?NAG, and ?NGAL) for either groups 6, 24, 72, and 168 hours after the procedures (p>0.05). Conclusions MRI without contrast agent and non-vascular contrast-enhanced (GD, 0.2 mmol/kg) MRI are not nephrotoxic procedures for patients at high risk for AKI. PMID:24193150

Oguz, Ebru Gok; Kiykim, Ahmet; Turgutalp, Kenan; Olmaz, Refik; Ozhan, Onur; Muslu, Necati; Horoz, Mehmet; Bardak, Simge; Sungur, Mehmet Ali

2013-01-01

69

Neural Correlates of Feigned Memory Impairment are Distinguishable from Answering Randomly and Answering Incorrectly: An fMRI and Behavioral Study  

ERIC Educational Resources Information Center

Previous functional magnetic resonance imaging (fMRI) studies have identified activation in the prefrontal-parietal-sub-cortical circuit during feigned memory impairment when comparing with truthful telling. Here, we used fMRI to determine whether neural activity can differentiate between answering correctly, answering randomly, answering…

Liang, Chun-Yu; Xu, Zhi-Yuan; Mei, Wei; Wang, Li-Li; Xue, Li; Lu, De Jian; Zhao, Hu

2012-01-01

70

SPIO-Enhanced MRI Findings of Well-Differentiated Hepatocellular Carcinomas: Correlation with MDCT Findings  

PubMed Central

Objective This study was designed to assess superparamagnetic iron oxide (SPIO)-enhanced MRI findings of well-differentiated hepatocellular carcinomas (HCCs) correlated with their multidetector-row CT (MDCT) findings. Materials and Methods Seventy-two patients with 84 pathologically proven well-differentiated HCCs underwent triple-phase MDCT and SPIO-enhanced MRI at a magnetic field strength of 1.5 Tesla (n = 49) and 3.0 Tesla (n = 23). Two radiologists in consensus retrospectively reviewed the CT and MR images for attenuation value and the signal intensity of each tumor. The proportion of hyperintense HCCs as depicted on SPIO-enhanced T2- or T2*-weighted images were compared in terms of tumor size (< 1 cm and > 1 cm), five CT attenuation patterns based on arterial and equilibrium phases and magnetic field strength, by the use of univariate and multivariate analyses. Results Seventy-eight (93%) and 71 (85%) HCCs were identified by CT and on SPIO-enhanced T2- and T2*-weighted images, respectively. For the CT attenuation pattern, one (14%) of seven isodense-isodense, four (67%) of six hypodense-hypodense, four (80%) of five isodense-hypodense, 14 (88%) of 16 hyperdense-isodense and 48 (96%) of 50 hyperdense-hypodense HCCs were hyperintense (Cochran-Armitage test for trend, p < 0.001). Based on the use of multivariate analysis, the CT attenuation pattern was the only factor that affected the proportion of hyperintense HCCs as depicted on SPIO-enhanced T2- or T2*-weighted images (p < 0.001). Tumor size or magnetic field strength was not a factor that affected the proportion of hyperintense HCCs based on the use of univariate and multivariate analysis (p > 0.05). Conclusion Most well-differentiated HCCs show hyperintensity on SPIO-enhanced MRI, although the lesions show various CT attenuation patterns. The CT attenuation pattern is the main factor that affects the proportion of hyperintense well-differentiated HCCs as depicted on SPIO-enhanced MRI. PMID:19270856

Lee, Won Jae; Lim, Hyo K.; Park, Cheol Keun

2009-01-01

71

Contrast-enhanced MRI of the subdeltoid, subacromial bursa in painful and painless rotator cuff tears  

PubMed Central

Objective Although shoulder pain is often associated with rotator cuff tears, many tears are asymptomatic and are not the cause of the patient's pain. This may explain the persistence of symptoms in some patients despite technically successful rotator cuff repair. It has been proposed that rotator cuff tears cause pain through subdeltoid/subacromial bursal inflammation. The aim of this study was to determine whether bursal inflammation seen on MRI is associated with pain in patients with rotator cuff tears of the shoulder. Methods The shoulders of 255 patients were screened with ultrasound. 33 full-thickness rotator cuff tears (18 with shoulder pain and 15 without pain) were identified and subsequently studied using contrast-enhanced MRI of the shoulder. Enhancement of the subacromial bursa was scored independently by two musculoskeletal radiologists. Logistic regression was used to determine whether bursal enhancement was independently associated with pain. Results There was a significant association between pain and age, with greater likelihood of pain in younger patients. Bursal enhancement was common in both painful and painless tears. No statistically significant link between pain and bursal enhancement was seen, even after accounting for age. Conclusion Although enhancement of the subdeltoid/subacromial bursa was common, no evidence was found to support the hypothesis that bursal enhancement is associated with pain in rotator cuff tears. It is therefore unlikely to determine reliably which patients would benefit from rotator cuff repair. Advances in knowledge Bursal enhancement and thickening does not reliably correlate with symptoms or presence of rotator cuff tear. PMID:23091289

Hodgson, R J; O'Connor, P J; Hensor, E M A; Barron, D; Robinson, P

2012-01-01

72

fMRI feedback enhances emotion regulation as evidenced by a reduced amygdala response.  

PubMed

Deficits in emotion regulation are a prominent feature of psychiatric conditions and a promising target for treatment. For instance, cognitive reappraisal is regarded as an effective strategy for emotion regulation. Neurophysiological models have established the lateral prefrontal cortex (LPFC) as a key structure in the regulation of emotion processing through modulations of emotion-eliciting structures such as the amygdala. Feedback of the LPFC activity by real-time functional magnetic resonance (fMRI) may thus enhance the efficacy of cognitive reappraisal. During cognitive reappraisal of aversive visual stimuli, LPFC activity was fed back to the experimental group, whereas control participants received no such information. As a result, during reappraisal, amygdala activity was lower in the experimental group than in the controls. Furthermore, an increase of inter-hemispheric functional connectivity emerged in the feedback group. The current study extends the neurofeedback literature by suggesting that fMRI feedback can modify brain activity during a given task. PMID:25461265

Sarkheil, Pegah; Zilverstand, Anna; Kilian-Hütten, Niclas; Schneider, Frank; Goebel, Rainer; Mathiak, Klaus

2015-03-15

73

2014 Spring : Highly Distinguished Honors Highly Distinguished  

E-print Network

Cristovam Anton Highly Distinguished Arruda Olivia Blair Highly Distinguished Arthur Mary Catherine Highly Distinguished Ashe Katherine Lee Highly Distinguished Ashy Cody Charles Highly Distinguished Atkins Danielle

Kasman, Alex

74

Semi-quantitative assessment of pulmonary perfusion in children using dynamic contrast-enhanced MRI  

NASA Astrophysics Data System (ADS)

This paper addresses the study of semi-quantitative assessment of pulmonary perfusion acquired from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in a study population mainly composed of children with pulmonary malformations. The automatic analysis approach proposed is based on the indicator-dilution theory introduced in 1954. First, a robust method is developed to segment the pulmonary artery and the lungs from anatomical MRI data, exploiting 2D and 3D mathematical morphology operators. Second, the time-dependent contrast signal of the lung regions is deconvolved by the arterial input function for the assessment of the local hemodynamic system parameters, ie. mean transit time, pulmonary blood volume and pulmonary blood flow. The discrete deconvolution method implements here a truncated singular value decomposition (tSVD) method. Parametric images for the entire lungs are generated as additional elements for diagnosis and quantitative follow-up. The preliminary results attest the feasibility of perfusion quantification in pulmonary DCE-MRI and open an interesting alternative to scintigraphy for this type of evaluation, to be considered at least as a preliminary decision in the diagnostic due to the large availability of the technique and to the non-invasive aspects.

Fetita, Catalin; Thong, William E.; Ou, Phalla

2013-03-01

75

Dynamic-contrast-enhanced-MRI with extravasating contrast reagent: Rat cerebral glioma blood volume determination  

NASA Astrophysics Data System (ADS)

The accurate mapping of the tumor blood volume (TBV) fraction ( vb) is a highly desired imaging biometric goal. It is commonly thought that achieving this is difficult, if not impossible, when small molecule contrast reagents (CRs) are used for the T1-weighted (Dynamic-Contrast-Enhanced) DCE-MRI technique. This is because angiogenic malignant tumor vessels allow facile CR extravasation. Here, a three-site equilibrium water exchange model is applied to DCE-MRI data from the cerebrally-implanted rat brain U87 glioma, a tumor exhibiting rapid CR extravasation. Analyses of segments of the (and the entire) DCE data time-course with this "shutter-speed" pharmacokinetic model, which admits finite water exchange kinetics, allow TBV estimation from the first-pass segment. Pairwise parameter determinances were tested with grid searches of 2D parametric error surfaces. Tumor blood volume ( vb), as well as ve (the extracellular, extravascular space volume fraction), and Ktrans (a CR extravasation rate measure) parametric maps are presented. The role of the Patlak Plot in DCE-MRI is also considered.

Li, Xin; Rooney, William D.; Várallyay, Csanád G.; Gahramanov, Seymur; Muldoon, Leslie L.; Goodman, James A.; Tagge, Ian J.; Selzer, Audrey H.; Pike, Martin M.; Neuwelt, Edward A.; Springer, Charles S.

2010-10-01

76

DCE@urLAB: a dynamic contrast-enhanced MRI pharmacokinetic analysis tool for preclinical data  

PubMed Central

Background DCE@urLAB is a software application for analysis of dynamic contrast-enhanced magnetic resonance imaging data (DCE-MRI). The tool incorporates a friendly graphical user interface (GUI) to interactively select and analyze a region of interest (ROI) within the image set, taking into account the tissue concentration of the contrast agent (CA) and its effect on pixel intensity. Results Pixel-wise model-based quantitative parameters are estimated by fitting DCE-MRI data to several pharmacokinetic models using the Levenberg-Marquardt algorithm (LMA). DCE@urLAB also includes the semi-quantitative parametric and heuristic analysis approaches commonly used in practice. This software application has been programmed in the Interactive Data Language (IDL) and tested both with publicly available simulated data and preclinical studies from tumor-bearing mouse brains. Conclusions A user-friendly solution for applying pharmacokinetic and non-quantitative analysis DCE-MRI in preclinical studies has been implemented and tested. The proposed tool has been specially designed for easy selection of multi-pixel ROIs. A public release of DCE@urLAB, together with the open source code and sample datasets, is available at http://www.die.upm.es/im/archives/DCEurLAB/. PMID:24180558

2013-01-01

77

Brain-wide pathway for waste clearance captured by contrast-enhanced MRI.  

PubMed

The glymphatic system is a recently defined brain-wide paravascular pathway for cerebrospinal fluid (CSF) and interstitial fluid (ISF) exchange that facilitates efficient clearance of solutes and waste from the brain. CSF enters the brain along para-arterial channels to exchange with ISF, which is in turn cleared from the brain along para-venous pathways. Because soluble amyloid ? clearance depends on glymphatic pathway function, we proposed that failure of this clearance system contributes to amyloid plaque deposition and Alzheimer's disease progression. Here we provide proof of concept that glymphatic pathway function can be measured using a clinically relevant imaging technique. Dynamic contrast-enhanced MRI was used to visualize CSF-ISF exchange across the rat brain following intrathecal paramagnetic contrast agent administration. Key features of glymphatic pathway function were confirmed, including visualization of para-arterial CSF influx and molecular size-dependent CSF-ISF exchange. Whole-brain imaging allowed the identification of two key influx nodes at the pituitary and pineal gland recesses, while dynamic MRI permitted the definition of simple kinetic parameters to characterize glymphatic CSF-ISF exchange and solute clearance from the brain. We propose that this MRI approach may provide the basis for a wholly new strategy to evaluate Alzheimer's disease susceptibility and progression in the live human brain. PMID:23434588

Iliff, Jeffrey J; Lee, Hedok; Yu, Mei; Feng, Tian; Logan, Jean; Nedergaard, Maiken; Benveniste, Helene

2013-03-01

78

Vascular changes caused by deep brain stimulation using double-dose gadolinium-enhanced brain MRI  

PubMed Central

We retrospectively analyzed the clinical data of 32 patients with medically intractable idiopathic Parkinson's disease who had undergone staged bilateral deep brain stimulation of the subthalamic nuclei from January 2007 to May 2011. The vascularture of the patients who received two deep brain stimulations was detected using double-dose gadolinium-enhanced brain MRI. The dimensions of straight sinus, superior sagittal sinus, ipsilateral internal cerebral vein in the thalamic branch and ipsilateral anterior caudate vein were reduced. These findings demonstrate that bilateral deep brain stimulation of the subthalamic nuclei affects cerebral venous blood flow. PMID:25206812

Choi, Byeong Sam; Kim, Yong Hwan; Jeon, Sang Ryong

2014-01-01

79

Acute effects of pelvic irradiation on the adult uterus revealed by dynamic contrast-enhanced MRI  

PubMed Central

Objective: Pelvic radiation therapy (RT) can influence fertility in female rectal cancer survivors. Data regarding its effects on the adult uterus are scant. This study aims to evaluate the uterus before and after RT, using dynamic contrast-enhanced MRI. Methods: Eligible patients (n=10) received RT for rectal cancer, had an intact uterus and underwent dynamic contrast-enhanced MRI before and after RT. Seven patients were pre-menopausal. Results: Patients received pelvic RT (median, 50.2?Gy) with concurrent 5-fluorouracil. Five patients were treated with intensity modulated RT (IMRT) and five with a three-field technique. The median D95 of the uterus was 30?Gy; D05 was 48?Gy; and V95 was 97%. The median cervical D95 was 45?Gy; D05, 50?Gy; and V95, 100%. Cervical dose was higher with IMRT than with three-field plans (p?0.038). On T2 MRI, the junctional zone was visible in nine patients before and in one after RT (p=0.001). Median cervical length (2.3 vs 3.0?cm) and endometrial thickness (2.6 vs 5.9?mm) were reduced after RT (p?0.008). In pre-menopausal patients, the volume transfer constant, Ktrans, (0.069 vs 0.195, p=0.006) and the extracellular extravascular volume fraction, Ve, (0.217 vs 0.520, p=0.053) decreased. Conclusion: Pelvic RT significantly affected uterine anatomy and perfusion. Cervical dose was higher with IMRT than three-field plans, but no attempt was made to constrain the dose. Advances in knowledge: Pelvic RT significantly affects the adult uterus. These findings are crucial to understand the potential consequences of RT on fertility, and they lay the groundwork for further prospective studies. PMID:24052311

Milgrom, S A; Alberto Vargas, H; Sala, E; Frankel Kelvin, J; Hricak, H

2013-01-01

80

Targeted Multifunctional Nanoparticles cure and image Brain Tumors: Selective MRI Contrast Enhancement and Photodynamic Therapy  

NASA Astrophysics Data System (ADS)

Aimed at targeted therapy and imaging of brain tumors, our approach uses targeted, multi-functional nano-particles (NP). A typical nano-particle contains a biologically inert, non-toxic matrix, biodegradable and bio-eliminable over a long time period. It also contains active components, such as fluorescent chemical indicators, photo-sensitizers, MRI contrast enhancement agents and optical imaging dyes. In addition, its surface contains molecular targeting units, e.g. peptides or antibodies, as well as a cloaking agent, to prevent uptake by the immune system, i.e. enabling control of the plasma residence time. These dynamic nano-platforms (DNP) contain contrast enhancement agents for the imaging (MRI, optical, photo-acoustic) of targeted locations, i.e. tumors. Added to this are targeted therapy agents, such as photosensitizers for photodynamic therapy (PDT). A simple protocol, for rats implanted with human brain cancer, consists of tail injection with DNPs, followed by 5 min red light illumination of the tumor region. It resulted in excellent cure statistics for 9L glioblastoma.

Kopelman, Raoul

2008-03-01

81

2013 Fall : Highly Distinguished Honors Highly Distinguished  

E-print Network

Shayna Rachel Highly Distinguished Barbaro Jillian Patrice Highly Distinguished Barrett John Patrick Christopher Scott Highly Distinguished Beanland Alexandra Sara Highly Distinguished Beasley Daniel Learin Distinguished Boyd Lindsay Elizabeth Louis Highly Distinguished Bradd Rachel Jo

Kasman, Alex

82

The Quality of Tumor Size Assessment by Contrast-Enhanced Spectral Mammography and the Benefit of Additional Breast MRI  

PubMed Central

Background - Contrast-enhanced spectral mammography (CESM) is a promising new breast imaging modality that is superior to conventional mammography for breast cancer detection. We aimed to evaluate correlation and agreement of tumor size measurements using CESM. As additional analysis, we evaluated whether measurements using an additional breast MRI exam would yield more accurate results. Methods - Between January 1st 2013 and April 1st 2014, 87 consecutive breast cancer cases that underwent CESM were collected and data on maximum tumor size measurements were gathered. In 57 cases, tumor size measurements were also available for breast MRI. Histopathological results of the surgical specimen served as gold standard in all cases. Results - The Pearson's correlation coefficients (PCC) of CESM versus histopathology and breast MRI versus histopathology were all >0.9, p<0.0001. For the agreement between measurements, the mean difference between CESM and histopathology was 0.03 mm. The mean difference between breast MRI and histopathology was 2.12 mm. Using a 2x2 contingency table to assess the frequency distribution of a relevant size discrepancy of >1 cm between the two imaging modalities and histopathological results, we did not observe any advantage of performing an additional breast MRI after CESM in any of the cases. Conclusion - Quality of tumor size measurement using CESM is good and matches the quality of these measurement assessed by breast MRI. Additional measurements using breast MRI did not improve the quality of tumor size measurements. PMID:25561979

Lobbes, Marc B.I.; Lalji, Ulrich C.; Nelemans, Patty J.; Houben, Ivo; Smidt, Marjolein L.; Heuts, Esther; de Vries, Bart; Wildberger, Joachim E.; Beets-Tan, Regina G.

2015-01-01

83

The correlation of contrast-enhanced ultrasound and MRI perfusion quantitative analysis in rabbit VX2 liver cancer.  

PubMed

Our objective is to explore the value of liver cancer contrast-enhanced ultrasound (CEUS) and MRI perfusion quantitative analysis in liver cancer and the correlation between these two analysis methods. Rabbit VX2 liver cancer model was established in this study. CEUS was applied. Sono Vue was applied in rabbits by ear vein to dynamically observe and record the blood perfusion and changes in the process of VX2 liver cancer and surrounding tissue. MRI perfusion quantitative analysis was used to analyze the mean enhancement time and change law of maximal slope increasing, which were further compared with the pathological examination results. Quantitative indicators of liver cancer CEUS and MRI perfusion quantitative analysis were compared, and the correlation between them was analyzed by correlation analysis. Rabbit VX2 liver cancer model was successfully established. CEUS showed that time-intensity curve of rabbit VX2 liver cancer showed "fast in, fast out" model while MRI perfusion quantitative analysis showed that quantitative parameter MTE of tumor tissue increased and MSI decreased: the difference was statistically significant (P < 0.01). The diagnostic results of CEUS and MRI perfusion quantitative analysis were not significantly different (P > 0.05). However, the quantitative parameter of them were significantly positively correlated (P < 0.05). CEUS and MRI perfusion quantitative analysis can both dynamically monitor the liver cancer lesion and surrounding liver parenchyma, and the quantitative parameters of them are correlated. The combined application of both is of importance in early diagnosis of liver cancer. PMID:25123838

Xiang, Zhiming; Liang, Qianwen; Liang, Changhong; Zhong, Guimian

2014-12-01

84

Toward Clinical Application of Manganese-enhanced MRI of Retinal Function  

PubMed Central

Purpose The application of Manganese-Enhanced MRI (MEMRI) to measure retinal function in humans is unclear. To begin to address this gap, we tested the hypothesis that an FDA-approved manganese-based MRI contrast agent, Teslascan, is useful for measuring functional intraretinal ionic regulation. Methods Anesthetized dark- or light-adapted male healthy Sprague Dawley rats were infused for 30 min with 10 ?mol/kg of Teslascan (clinically relevant dose; n=5), 100 ?mol/kg Teslascan (n=5), or saline (n=5). Four hours post administration, high resolution MEMRI data were collected. Intraretinal signal intensities and enhancements were measured. Modelling was performed to estimate apparent retinal transfer constant Ki and to determine optimal data acquisition parameters. Results In light-adapted rats, intraretinal enhancements responded in a dose-response manner. In addition, in the outer retina the effect of light-adaptation was to reduce significantly Mn2+ uptake and Ki compared to dark-adaptation. A non-significant change was also observed in the inner retina. Modelling shows Mn2+ plasma concentration reaching a plateau after about 2 hours. Apparent Ki values for the clinically-relevant dose are 3-6 10-3 min-1, decreasing to 0.5-0.6 10-3 min-1 at the higher dose. Intraretinal signal is almost linear with Ki. Optimal TR for a spin echo sequence is 0.4-1.4s. Conclusion First time evidence is presented that a clinically-relevant dose and route of Teslascan can be used to measure intraretinal function. The potential for future clinical application of MEMRI in a broad range of retinopathies is high. PMID:19524028

Tofts, Paul S; Porchia, Andre; Jin, Ying; Roberts, Robin; Berkowitz, Bruce A

2009-01-01

85

Layer-Specific Manganese-Enhanced MRI of the Retina in Light and Dark Adaptation  

PubMed Central

Purpose. To employ functional manganese-enhanced MRI (MEMRI) to image layer-specific changes in calcium-dependent activities in the rat retina during light versus dark adaptation. Methods. Functional MEMRI at 20 × 20 × 700 ?m was used to study light and dark adaptation in the same animals (N = 10) in which one eye was covered and the fellow eye was not. The activity encoding of the light and dark adaptation was achieved in awake conditions and imaged under anesthesia. T1-weighted MRI at 11.7 tesla (T) was performed using two identical radiofrequency transceiver coils to allow interleaved MRI acquisitions of the two eyes. An intravascular contrast agent was also used to verify layer assignments. Results. MEMRI detected contrasts among the inner retina, outer retina, and choroid. Independent confirmation of the vascular layers and boundaries between layers was documented with an intravascular contrast agent. The retinal layer thicknesses agreed with published data. The outer retina had lower MEMRI activity in light compared with dark adaption (P < 0.001), consistent with the increased metabolic demand associated with the “dark current.” The inner retina had higher MEMRI activity in light compared with dark adaption (P < 0.05). The choroid MEMRI activity was not statistically different between light and dark adaptation (P > 0.05). Conclusions. This study demonstrated a high-resolution MEMRI protocol to image functional activities among different layers of the retinas in awake animals during light and dark adaptation. This approach could have potential applications in animal models of retinal dysfunction. PMID:22669725

De?La?Garza, Bryan H.; Li, Guang; Shih, Yen-Yu I.; Duong, Timothy Q.

2012-01-01

86

Simultaneous molecular imaging of redox reactions monitored by Overhauser-enhanced MRI with 14N- and 15N-labeled nitroxyl radicals  

Microsoft Academic Search

MRI has provided significant clinical utility in the diagnosis of diseases and will become a powerful tool to assess phenotypic changes in genetically engineered animals. Overhauser enhanced MRI (OMRI), which is a double resonance technique, creates images of free radical distributions in small animals by enhancing the water proton signal intensity by means of the Overhauser effect. Several studies have

Hideo Utsumi; Ken-Ichi Yamada; Kazuhiro Ichikawa; Kiyoshi Sakai; Yuichi Kinoshita; Shingo Matsumoto; Mika Nagai

2006-01-01

87

Raloxifene Treatment Enhances Brain Activation during Recognition of Familiar Items: a Pharmacological fMRI Study in Healthy Elderly Males  

Microsoft Academic Search

Raloxifene is a selective estrogen receptor modulator that may delay the onset of mild cognitive impairment in elderly women. Effects of raloxifene treatment on mental performance in males remain to be investigated. In a previous functional magnetic resonance imaging (fMRI) study, we showed that raloxifene treatment enhanced brain activation in elderly males during encoding of new information (faces) into memory.

Rutger Goekoop; Frederik Barkhof; Erik J J Duschek; Coen Netelenbos; Dirk L Knol; Philip Scheltens; Serge ARB Rombouts

2006-01-01

88

Nanoparticle-Enhanced MRI to Evaluate Radiation Delivery to the Regional Lymphatics for Patients With Breast Cancer  

SciTech Connect

Purpose: At present, radiation (RT) fields are based largely, and often solely, on bony anatomy. Recent efforts have been taken to better define lymphatic regions for RT planning. Lymphotrophic nanoparticle-enhanced MRI (LN-MRI) allows for accurate identification of malignant and benign lymph nodes. We sought to evaluate RT delivery to lymphatics for breast cancer using LN-MRI. Methods and Materials: Twenty-three patients with breast cancer underwent LN-MRI. MRIs were anatomically registered to a reference CT; benign and malignant lymph nodes were contoured. Standard RT fields were planned and dose calculated to prescribe 45-50 Gy. Lymphatic regions were contoured on CT. Coverage of LN-MRI lymph nodes by RT fields and contoured lymphatics were assessed. Results: Eighty-one percent of all lymph nodes defined by LN-MRI were covered by the 45-Gy isodose line; 82% of malignant and 79% of benign. The 50-Gy isodose line only encompassed 60% of LN-MRI defined lymph nodes-64% of malignant and 59% of benign. For nodal volumes contoured in the absence of a margin, 86% of actual lymph nodes were within contoured volumes. When a 5-mm expansion was added, 99% were included. Conclusions: LN-MRI is a useful tool to delineate the location of breast regional lymphatics. These results suggest less than desired coverage of lymph nodes using standard RT fields and that a margin may be advisable when defining nodal volumes by CT. The use of IMRT and RT in lieu of surgery makes accurate definition of the location of breast regional lymphatics of paramount importance.

MacDonald, Shannon M., E-mail: smacdonald@partners.or [Departments of Radiation Oncology and Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States); Harisinghani, Mukesh G.; Katkar, Amol; Napolitano, Brian; Wolfgang, John; Taghian, Alphonse G. [Departments of Radiation Oncology and Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA (United States)

2010-07-15

89

Enhancement and suppression in a lexical interference fMRI-paradigm  

PubMed Central

Previous picture-word interference (PWI) fMRI-paradigms revealed ambiguous mechanisms underlying facilitation and inhibition in healthy subjects. Lexical distractors revealed increased (enhancement) or decreased (suppression) activation in language and monitoring/control areas. Performing a secondary examination and data analysis, we aimed to illuminate the relation between behavioral and neural interference effects comparing target-related distractors (REL) with unrelated distractors (UNREL). We hypothesized that interference involves both (A) suppression due to priming and (B) enhancement due to simultaneous distractor and target processing. Comparisons to UNREL should remain distractor unspecific even at a low threshold. (C) Distractor types with common characteristics should reveal overlapping brain areas. In a 3T MRI scanner, participants were asked to name pictures while auditory words were presented (stimulus onset asynchrony [SOA] = –200 msec). Associatively and phonologically related distractors speeded responses (facilitation), while categorically related distractors slowed them down (inhibition) compared to UNREL. As a result, (A) reduced brain activations indeed resembled previously reported patterns of neural priming. Each target-related distractor yielded suppressions at least in areas associated with vision and conflict/competition monitoring (anterior cingulate cortex [ACC]), revealing least priming for inhibitors. (B) Enhancements concerned language-related but distractor-unspecific regions. (C) Some wider brain regions were commonly suppressed for combinations of distractor types. Overlapping areas associated with conceptual priming were found for facilitatory distractors (inferior frontal gyri), and areas related to phonetic/articulatory processing (precentral gyri and left parietal operculum/insula) for distractors sharing feature overlap. Each distractor with semantic relatedness revealed nonoverlapping suppressions in lexical-phonological areas (superior temporal regions). To conclude, interference combines suppression of areas well known from neural priming and enhancement of language-related areas caused by dual activation from target and distractor. Differences between interference and priming need to be taken into account. The present interference paradigm has the potential to reveal the functioning of word-processing stages, cognitive control, and responsiveness to priming at the same time. PMID:22574280

Abel, Stefanie; Dressel, Katharina; Weiller, Cornelius; Huber, Walter

2012-01-01

90

Investigating the Influence of Flip Angle and k-Space Sampling on Dynamic Contrast-Enhanced MRI Breast Examinations  

PubMed Central

Rationale and Objectives To retrospectively investigate the effect of flip angle (FA) and k-space sampling on the performance of dynamic contrast-enhanced (DCE-) magnetic resonance imaging (MRI) breast sequences. Materials and Methods Five DCE-MRI breast sequences were evaluated (10°, 14°, and 18° FAs; radial or linear k-space sampling), with 7–10 patients in each group (n = 45). All sequences were compliant with current technical breast screening guidelines. Contrast agent (CA) uptake curves were constructed from the right mammary artery for each examination. Maximum relative enhancement, Emax, and time-to-peak enhancement, Tmax, were measured and compared between protocols (analysis of variance and Mann–Whitney). For each sequence, calculated values of maximum relative enhancement, Ecalc, were derived from the Bloch equations and compared to Emax. Fat suppression performance (residual bright fat and chemical shift artifact) was rated for each examination and compared between sequences (Fisher exact tests). Results Significant differences were identified between DCE-MRI sequences. Emax increased significantly at higher FAs and with linear k-space sampling (P < .0001; P = .001). Radial protocols exhibited greater Tmax than linear protocols at FAs of both 14° (P = .025) and 18° (P < .0001), suggesting artificially flattened uptake curves. Good correlation was observed between Ecalc and Emax (r = 0.86). Fat suppression failure was more pronounced at an FA of 18° (P = .008). Conclusions This retrospective approach is validated as a tool to compare and optimize breast DCE-MRI sequences. Alterations in FA and k-space sampling result in significant differences in CA uptake curve shape which could potentially affect diagnostic interpretation. These results emphasize the need for careful parameter selection and greater standardization of breast DCE-MRI sequences. PMID:25179563

Ledger, Araminta E.W.; Borri, Marco; Pope, Romney J.E.; Scurr, Erica D.; Wallace, Toni; Richardson, Cheryl; Usher, Marianne; Allen, Steven; Wilson, Robin M.; Thomas, Karen; deSouza, Nandita M.; Leach, Martin O.; Schmidt, Maria A.

2014-01-01

91

Adaptive k-space sampling design for edge-enhanced DCE-MRI using compressed sensing.  

PubMed

The critical challenge in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is the trade-off between spatial and temporal resolution due to the limited availability of acquisition time. To address this, it is imperative to under-sample k-space and to develop specific reconstruction techniques. Our proposed method reconstructs high-quality images from under-sampled dynamic k-space data by proposing two main improvements; i) design of an adaptive k-space sampling lattice and ii) edge-enhanced reconstruction technique. A high-resolution data set obtained before the start of the dynamic phase is utilized. The sampling pattern is designed to adapt to the nature of k-space energy distribution obtained from the static high-resolution data. For image reconstruction, the well-known compressed sensing-based total variation (TV) minimization constrained reconstruction scheme is utilized by incorporating the gradient information obtained from the static high-resolution data. The proposed method is tested on seven real dynamic time series consisting of 2 breast data sets and 5 abdomen data sets spanning 1196 images in all. For data availability of only 10%, performance improvement is seen across various quality metrics. Average improvements in Universal Image Quality Index and Structural Similarity Index Metric of up to 28% and 24% on breast data and about 17% and 9% on abdomen data, respectively, are obtained for the proposed method as against the baseline TV reconstruction with variable density random sampling pattern. PMID:24848294

Raja, Rajikha; Sinha, Neelam

2014-09-01

92

Same-session functional assessment of rat retina and brain with manganese-enhanced MRI  

PubMed Central

Manganese-enhanced MRI (MEMRI) is a powerful non-invasive approach for objectively measuring either retina or binocular visual brain activity in vivo. In this study, we investigated the sensitivity of MEMRI to monocular stimulation using a new protocol for providing within-subject functional comparisons in the retina and brain in the same scanning session. Adult Sprague Dawley or Long–Evans rats had one eye covered with an opaque patch. After intraperitoneal Mn2+ administration on the following day, rats underwent visual stimulation for 8 h. Animals were then anesthetized, and the brain and each eye examined by MEMRI. Function was assessed through pairwise comparisons of the patched (dark-adapted) versus unpatched (light-exposed) eyes, and of differentially-stimulated brain structures – the dorsal lateral geniculate nucleus, superior colliculus, and visual cortical regions – contralateral to the patched versus unpatched eye. As expected, Mn2+ uptake was greater in the outer retina of dark-adapted, relative to light-exposed, eyes (P<0.05). Contralateral to the unpatched eye, significantly more Mn2+ uptake was found throughout the visual brain regions than in the corresponding structures contralateral to the patched eye (P<0.05). Notably, this regional pattern of activity corresponded well to previous work with monocular stimulation. No stimulation-dependent differences in Mn2+ uptake were observed in negative control brain regions (P>0.05). Post-hoc assessment of functional data by animal age and strain revealed no significant effects. These results demonstrate, for the first time, the acquisition of functional MRI data from the eye and visual brain regions in a single scanning session. PMID:21749922

Bissig, David; Berkowitz, Bruce A.

2013-01-01

93

Manganese-enhanced MRI reveals early-phase radiation-induced cell alterations in vivo.  

PubMed

For tumor radiotherapy, the in vivo detection of early cellular responses is important for predicting therapeutic efficacy. Mn(2+) is used as a positive contrast agent in manganese-enhanced MRI (MEMRI) and is expected to behave as a mimic of Ca(2+) in many biologic systems. We conducted in vitro and in vivo MRI experiments with Mn(2+) to investigate whether MEMRI can be used to detect cell alterations as an early-phase tumor response after radiotherapy. Colon-26 cells or a subcutaneously grafted colon-26 tumor model were irradiated with 20 Gy of X-rays. One day after irradiation, a significant augmentation of G2-M-phase cells, indicating a cell-cycle arrest, was observed in the irradiated cells in comparison with the control cells, although both early and late apoptotic alterations were rarely observed. The MEMRI signal in radiation-exposed tumor cells (R1: 0.77 ± 0.01 s(-1)) was significantly lower than that in control cells (R1: 0.82 ± 0.01 s(-1)) in vitro. MEMRI signal reduction was also observed in the in vivo tumor model 24 hours after irradiation (R1 of radiation: 0.97 ± 0.02 s(-1), control: 1.10 ± 0.02 s(-1)), along with cell-cycle and proliferation alterations identified with immunostaining (cyclin D1 and Ki-67). Therefore, MEMRI after tumor radiotherapy was successfully used to detect cell alterations as an early-phase cellular response in vitro and in vivo. PMID:23695553

Saito, Shigeyoshi; Hasegawa, Sumitaka; Sekita, Aiko; Bakalova, Rumiana; Furukawa, Takako; Murase, Kenya; Saga, Tsuneo; Aoki, Ichio

2013-06-01

94

Practical Dynamic Contrast Enhanced MRI in Small Animal Models of Cancer: Data Acquisition, Data Analysis, and Interpretation  

PubMed Central

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) consists of the continuous acquisition of images before, during, and after the injection of a contrast agent. DCE-MRI allows for noninvasive evaluation of tumor parameters related to vascular perfusion and permeability and tissue volume fractions, and is frequently employed in both preclinical and clinical investigations. However, the experimental and analytical subtleties of the technique are not frequently discussed in the literature, nor are its relationships to other commonly used quantitative imaging techniques. This review aims to provide practical information on the development, implementation, and validation of a DCE-MRI study in the context of a preclinical study (though we do frequently refer to clinical studies that are related to these topics). PMID:23105959

Barnes, Stephanie L.; Whisenant, Jennifer G.; Loveless, Mary E.; Yankeelov, Thomas E.

2012-01-01

95

Is 3-Tesla Gd-EOB-DTPA-Enhanced MRI with Diffusion-Weighted Imaging Superior to 64-Slice Contrast-Enhanced CT for the Diagnosis of Hepatocellular Carcinoma?  

PubMed Central

Objectives To compare 64-slice contrast-enhanced computed tomography (CT) with 3-Tesla magnetic resonance imaging (MRI) using Gd-EOB-DTPA for the diagnosis of hepatocellular carcinoma (HCC) and evaluate the utility of diffusion-weighted imaging (DWI) in this setting. Methods 3-phase-liver-CT was performed in fifty patients (42 male, 8 female) with suspected or proven HCC. The patients were subjected to a 3-Tesla-MRI-examination with Gd-EOB-DTPA and diffusion weighted imaging (DWI) at b-values of 0, 50 and 400 s/mm2. The apparent diffusion coefficient (ADC)-value was determined for each lesion detected in DWI. The histopathological report after resection or biopsy of a lesion served as the gold standard, and a surrogate of follow-up or complementary imaging techniques in combination with clinical and paraclinical parameters was used in unresected lesions. Diagnostic accuracy, sensitivity, specificity, and positive and negative predictive values were evaluated for each technique. Results MRI detected slightly more lesions that were considered suspicious for HCC per patient compared to CT (2.7 versus 2.3, respectively). ADC-measurements in HCC showed notably heterogeneous values with a median of 1.2±0.5×10?3 mm2/s (range from 0.07±0.1 to 3.0±0.1×10?3 mm2/s). MRI showed similar diagnostic accuracy, sensitivity, and positive and negative predictive values compared to CT (AUC 0.837, sensitivity 92%, PPV 80% and NPV 90% for MRI vs. AUC 0.798, sensitivity 85%, PPV 79% and NPV 82% for CT; not significant). Specificity was 75% for both techniques. Conclusions Our study did not show a statistically significant difference in detection in detection of HCC between MRI and CT. Gd-EOB-DTPA-enhanced MRI tended to detect more lesions per patient compared to contrast-enhanced CT; therefore, we would recommend this modality as the first-choice imaging method for the detection of HCC and therapeutic decisions. However, contrast-enhanced CT was not inferior in our study, so that it can be a useful image modality for follow-up examinations. PMID:25375778

Maiwald, Bettina; Lobsien, Donald; Kahn, Thomas; Stumpp, Patrick

2014-01-01

96

Direct CSF injection of MnCl(2) for dynamic manganese-enhanced MRI.  

PubMed

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(1) and T(2) mapping for up to 3 weeks after injection. Observations within the first 6 hr after injection demonstrated anterograde and bilateral distribution of the Mn(++) within the CSF space, from the olfactory bulb and frontal cortex to the brain stem. Enhancement increased in most brain areas up to 4 days after injection, and then slowly decreased. Relaxation maps at each time point demonstrated higher concentrations of Mn in basal ganglia. Residual concentrations were still observable after 3 weeks in all brain regions. With the use of MnCl(2) calibration phantoms, the maximum Mn concentration in the brain was estimated to be approximately 27 +/- 16 microM, corresponding to changes in relaxation rates of 0.49 +/- 0.30 s(-1) for R(1) and 3.9 +/- 2.4 s(-1) for R(2). For comparison, an intrathecal GdDTPA injection was performed. This injection showed different distribution dynamics: it remained chiefly within the CSF spaces, and was largely washed out after 1 day. This method shows promise as a means of supplying Mn(++) uniformly to the whole brain for a variety of chronic functional activation studies. PMID:15122680

Liu, Christina H; D'Arceuil, Helen E; de Crespigny, Alex J

2004-05-01

97

Ionic Dysregulatory Phenotyping of Pathologic Retinal Thinning with Manganese-Enhanced MRI  

PubMed Central

PURPOSE To test the hypothesis that manganese-enhanced MRI (MEMRI) provides a sensitive and robust measure of an important retinal ionic dysregulatory phenotype in pathologic retinal thinning. METHODS Four hours after intraperitoneal MnCl2 injection, high-resolution MEMRI data were collected from overnight dark-adapted male control Sprague–Dawley and albino Royal College of Surgeons rats before (at development stage postnatal day [P] 17) and during photoreceptor degeneration (P36 and P57). In separate experiments, control rats, with and without repetitive hypoxic preconditioning, were subjected to high IOP (100 mm Hg) for 60 minutes followed by 24 hours or 7 days of reperfusion (e.g., ischemia/reperfusion). Central retinal thickness and intraretinal ion activity were measured from the MEMRI data. Histology examination was also performed to confirm retinal damage. RESULTS In two different neurodegenerative models, MEMRI revealed first-time evidence for changes (P < 0.05) in intraretinal ion regulation before and during pathologic, but not (P > 0.05) developmental, retinal thinning. This phenotype was significantly altered by a neuroprotective repetitive hypoxic preconditioning protocol. CONCLUSIONS MEMRI and a nontoxic systemic dose of MnCl2 provided an objective, noninvasive measure of an ionic deregulatory phenotype that appears useful for improved early diagnosis and treatment prognosis in a range of neurodegenerative diseases and their treatment. PMID:18362105

Berkowitz, Bruce A.; Gradianu, Marius; Schafer, Stephen; Jin, Ying; Porchia, Andre; Iezzi, Raymond; Roberts, Robin

2008-01-01

98

Inflow-weighted pulmonary perfusion: comparison between dynamic contrast-enhanced MRI versus perfusion scintigraphy in complex pulmonary circulation  

PubMed Central

Background Due to the different properties of the contrast agents, the lung perfusion maps as measured by 99mTc-labeled macroaggregated albumin perfusion scintigraphy (PS) are not uncommonly discrepant from those measured by dynamic contrast-enhanced MRI (DCE-MRI) using indicator-dilution analysis in complex pulmonary circulation. Since PS offers the pre-capillary perfusion of the first-pass transit, we hypothesized that an inflow-weighted perfusion model of DCE-MRI could simulate the result by PS. Methods 22 patients underwent DCE-MRI at 1.5T and also PS. Relative perfusion contributed by the left lung was calculated by PS (PSL%), by DCE-MRI using conventional indicator dilution theory for pulmonary blood volume (PBVL%) and pulmonary blood flow (PBFL%) and using our proposed inflow-weighted pulmonary blood volume (PBViwL%). For PBViwL%, the optimal upper bound of the inflow-weighted integration range was determined by correlation coefficient analysis. Results The time-to-peak of the normal lung parenchyma was the optimal upper bound in the inflow-weighted perfusion model. Using PSL% as a reference, PBVL% showed error of 49.24% to ?40.37% (intraclass correlation coefficient RI?=?0.55) and PBFL% had error of 34.87% to ?27.76% (RI?=?0.80). With the inflow-weighted model, PBViwL% had much less error of 12.28% to ?11.20% (RI?=?0.98) from PSL%. Conclusions The inflow-weighted DCE-MRI provides relative perfusion maps similar to that by PS. The discrepancy between conventional indicator-dilution and inflow-weighted analysis represents a mixed-flow component in which pathological flow such as shunting or collaterals might have participated. PMID:23448679

2013-01-01

99

Investigation of PET/MRI Image Fusion Schemes for Enhanced Breast Cancer Diagnosis  

E-print Network

for reading registered MRI and PET breast images. Preliminary results indicate that the radiologists were generated by our new genetic algorithm, as compared to commonly used fire/gray or red/gray schemes. I radiologists were asked to perform a set of tasks reading fused PET/MRI breast images obtained using several

100

ACTIVE DELIVERY CABLE TUNED TO DEVICE DEPLOYMENT STATE: ENHANCED VISIBILITY OF NITINOL OCCLUDERS DURING PRE-CLINICAL INTERVENTIONAL MRI  

PubMed Central

Purpose To develop an active delivery system that enhances visualization of nitinol cardiac occluder devices during deployment under real-time MRI. Materials and Methods We constructed an active delivery cable incorporating a loopless antenna and a custom titanium microscrew to secure the occluder devices. The delivery cable was tuned and matched to 50? at 64 MHz with the occluder device attached. We used real-time balanced SSFP in a wide-bore 1.5T scanner. Device-related images were reconstructed separately and combined with surface-coil images. The delivery cable was tested in vitro in a phantom and in vivo in swine using a variety of nitinol cardiac occluder devices. Results In vitro, the active delivery cable provided little signal when the occluder device was detached and maximal signal with the device attached. In vivo, signal from the active delivery cable enabled clear visualization of occluder device during positioning and deployment. Device release resulted in decreased signal from the active cable. Post-mortem examination confirmed proper device placement. Conclusions The active delivery cable enhanced the MRI depiction of nitinol cardiac occluder devices during positioning and deployment, both in conventional and novel applications. We expect enhanced visibility to contribute to effectiveness and safety of new and emerging MRI-guided treatments. PMID:22707441

Bell, Jamie A.; Saikus, Christina E.; Ratnayaka, Kanishka; Barbash, Israel M.; Faranesh, Anthony Z.; Franson, Dominique N.; Sonmez, Merdim; Slack, Michael C.; Lederman, Robert J.; Kocaturk, Ozgur

2012-01-01

101

Can contrast-enhanced ultrasound distinguish malignant from reactive lymph nodes in patients with head and neck cancers?  

PubMed

The purpose of this study was to investigate the utility of contrast-enhanced ultrasound in differentiating benign from malignant cervical lymph nodes in patients with squamous cell carcinoma of the head and neck. A consecutive series of 17 patients with known head and neck malignancy scheduled for neck surgery and lymph node clearance were recruited for contrast-enhanced ultrasound evaluation. Sonographic signal intensity as a function of time, comparing features of time to peak, time to arrival and time to wash-out, was quantified. The selected node was removed surgically and submitted for histology. Contrast-enhanced ultrasound examination had 100% sensitivity and 85.7% specificity for lymph node involvement. Functional analysis revealed contrast peaks significantly earlier in the malignant nodes (mean ± standard deviation) of 24.14 ± 2.7 s compared with 29.33 ± 3.4 s (p = 0.0128). Contrast-enhanced ultrasound holds promise in the detection and characterization of metastatic nodes that would not be diagnosed as abnormal on the basis of conventional ultrasound criteria. PMID:24462154

Dudau, Cristina; Hameed, Shema; Gibson, Daren; Muthu, Senthil; Sandison, Ann; Eckersley, Rob J; Clarke, Peter; Cosgrove, David O; Lim, Adrian K

2014-04-01

102

Development and characterization of a dynamic lesion phantom for the quantitative evaluation of dynamic contrast-enhanced MRI  

PubMed Central

Purpose: To develop a dynamic lesion phantom that is capable of producing physiological kinetic curves representative of those seen in human dynamic contrast-enhanced MRI (DCE-MRI) data. The objective of this phantom is to provide a platform for the quantitative comparison of DCE-MRI protocols to aid in the standardization and optimization of breast DCE-MRI. Methods: The dynamic lesion consists of a hollow, plastic mold with inlet and outlet tubes to allow flow of a contrast agent solution through the lesion over time. Border shape of the lesion can be controlled using the lesion mold production method. The configuration of the inlet and outlet tubes was determined using fluid transfer simulations. The total fluid flow rate was determined using x-ray images of the lesion for four different flow rates (0.25, 0.5, 1.0, and 1.5 ml?s) to evaluate the resultant kinetic curve shape and homogeneity of the contrast agent distribution in the dynamic lesion. High spatial and temporal resolution x-ray measurements were used to estimate the true kinetic curve behavior in the dynamic lesion for benign and malignant example curves. DCE-MRI example data were acquired of the dynamic phantom using a clinical protocol. Results: The optimal inlet and outlet tube configuration for the lesion molds was two inlet molds separated by 30° and a single outlet tube directly between the two inlet tubes. X-ray measurements indicated that 1.0 ml?s was an appropriate total fluid flow rate and provided truth for comparison with MRI data of kinetic curves representative of benign and malignant lesions. DCE-MRI data demonstrated the ability of the phantom to produce realistic kinetic curves. Conclusions: The authors have constructed a dynamic lesion phantom, demonstrated its ability to produce physiological kinetic curves, and provided estimations of its true kinetic curve behavior. This lesion phantom provides a tool for the quantitative evaluation of DCE-MRI protocols, which may lead to improved discrimination of breast cancer lesions. PMID:21992378

Freed, Melanie; de Zwart, Jacco A.; Hariharan, Prasanna; R. Myers, Matthew; Badano, Aldo

2011-01-01

103

Prostate cancer transrectal HIFU ablation: detection of local recurrences using T2-weighted and dynamic contrast-enhanced MRI.  

PubMed

The objective was to evaluate T2-weighted (T2w) and dynamic contrast-enhanced (DCE) MRI in detecting local cancer recurrences after prostate high-intensity focused ultrasound (HIFU) ablation. Fifty-nine patients with biochemical recurrence after prostate HIFU ablation underwent T2-weighted and DCE MRI before transrectal biopsy. For each patient, biopsies were performed by two operators: operator 1 (blinded to MR results) performed random and colour Doppler-guided biopsies ("routine biopsies"); operator 2 obtained up to three cores per suspicious lesion on MRI ("targeted biopsies"). Seventy-seven suspicious lesions were detected on DCE images (n = 52), T2w images (n = 2) or both (n = 23). Forty patients and 41 MR lesions were positive at biopsy. Of the 36 remaining MR lesions, 20 contained viable benign glands. Targeted biopsy detected more cancers than routine biopsy (36 versus 27 patients, p = 0.0523). The mean percentages of positive cores per patient and of tumour invasion of the cores were significantly higher for targeted biopsies (p < 0.0001). The odds ratios of the probability of finding viable cancer and viable prostate tissue (benign or malignant) at targeted versus routine biopsy were respectively 3.35 (95% CI 3.05-3.64) and 1.38 (95% CI 1.13-1.63). MRI combining T2-weighted and DCE images is a promising method for guiding post-HIFU biopsy towards areas containing recurrent cancer and viable prostate tissue. PMID:19690866

Rouvière, Olivier; Girouin, Nicolas; Glas, Ludivine; Ben Cheikh, Alexandre; Gelet, Albert; Mège-Lechevallier, Florence; Rabilloud, Muriel; Chapelon, Jean-Yves; Lyonnet, Denis

2010-01-01

104

Automated segmentation of reference tissue for prostate cancer localization in dynamic contrast enhanced MRI  

NASA Astrophysics Data System (ADS)

For pharmacokinetic (PK) analysis of Dynamic Contrast Enhanced (DCE) MRI the arterial input function needs to be estimated. Previously, we demonstrated that PK parameters have a significant better discriminative performance when per patient reference tissue was used, but required manual annotation of reference tissue. In this study we propose a fully automated reference tissue segmentation method that tackles this limitation. The method was tested with our Computer Aided Diagnosis (CADx) system to study the effect on the discriminating performance for differentiating prostate cancer from benign areas in the peripheral zone (PZ). The proposed method automatically segments normal PZ tissue from DCE derived data. First, the bladder is segmented in the start-to-enhance map using the Otsu histogram threshold selection method. Second, the prostate is detected by applying a multi-scale Hessian filter to the relative enhancement map. Third, normal PZ tissue was segmented by threshold and morphological operators. The resulting segmentation was used as reference tissue to estimate the PK parameters. In 39 consecutive patients carcinoma, benign and normal tissue were annotated on MR images by a radiologist and a researcher using whole mount step-section histopathology as reference. PK parameters were computed for each ROI. Features were extracted from the set of ROIs using percentiles to train a support vector machine that was used as classifier. Prospective performance was estimated by means of leave-one-patient-out cross validation. A bootstrap resampling approach with 10,000 iterations was used for estimating the bootstrap mean AUCs and 95% confidence intervals. In total 42 malignant, 29 benign and 37 normal regions were annotated. For all patients, normal PZ was successfully segmented. The diagnostic accuracy obtained for differentiating malignant from benign lesions using a conventional general patient plasma profile showed an accuracy of 0.64 (0.53-0.74). Using the automated per-patient calibration method the diagnostic performance improved significantly to 0.76 (0.67-0.86, p=0.017) , whereas the manual per-patient calibration showed a diagnostic performance of 0.79 (0.70-0.89, p=0.01). In conclusion, the results show that an automated per-patient reference tissue PK model is feasible. A significantly better discriminating performance compared to the conventional general calibration was obtained and the diagnostic accuracy is similar to using manual per-patient calibration.

Vos, Pieter C.; Hambrock, Thomas; Barentsz, Jelle O.; Huisman, Henkjan J.

2010-03-01

105

Dynamic Contrast-Enhanced MRI Assessment of Hyperemic Fractional Microvascular Blood Plasma Volume in Peripheral Arterial Disease: Initial Findings  

PubMed Central

Objectives The aim of the current study was to describe a method that assesses the hyperemic microvascular blood plasma volume of the calf musculature. The reversibly albumin binding contrast agent gadofosveset was used in dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) to assess the microvascular status in patients with peripheral arterial disease (PAD) and healthy controls. In addition, the reproducibility of this method in healthy controls was determined. Materials and Methods Ten PAD patients with intermittent claudication and 10 healthy control subjects were included. Patients underwent contrast-enhanced MR angiography of the peripheral arteries, followed by one DCE MRI examination of the musculature of the calf. Healthy control subjects were examined twice on different days to determine normative values and the interreader and interscan reproducibility of the technique. The MRI protocol comprised dynamic imaging of contrast agent wash-in under reactive hyperemia conditions of the calf musculature. Using pharmacokinetic modeling the hyperemic fractional microvascular blood plasma volume (Vp, unit: %) of the anterior tibial, gastrocnemius and soleus muscles was calculated. Results Vp was significantly lower for all muscle groups in PAD patients (4.3±1.6%, 5.0±3.3% and 6.1±3.6% for anterior tibial, gastrocnemius and soleus muscles, respectively) compared to healthy control subjects (9.1±2.0%, 8.9±1.9% and 9.3±2.1%). Differences in Vp between muscle groups were not significant. The coefficient of variation of Vp varied from 10–14% and 11–16% at interscan and interreader level, respectively. Conclusions Using DCE MRI after contrast-enhanced MR angiography with gadofosveset enables reproducible assessment of hyperemic fractional microvascular blood plasma volume of the calf musculature. Vp was lower in PAD patients than in healthy controls, which reflects a promising functional (hemodynamic) biomarker for the microvascular impairment of macrovascular lesions. PMID:22662212

Versluis, Bas; Dremmen, Marjolein H. G.; Nelemans, Patty J.; Wildberger, Joachim E.; Schurink, Geert-Willem; Leiner, Tim; Backes, Walter H.

2012-01-01

106

Manganese-impregnated mesoporous silica nanoparticles for signal enhancement in MRI cell labelling studies  

NASA Astrophysics Data System (ADS)

Mesoporous silica nanoparticles (MSNs) are used in drug delivery and cell tracking applications. As Mn2+ is already implemented as a ``positive'' cell contrast agent in preclinical imaging procedures (in the form of MnCl2 for neurological studies), the introduction of Mn in the porous network of MSNs would allow labelling cells and tracking them using MRI. These particles are in general internalized in endosomes, an acidic environment with high saline concentration. In addition, the available MSN porosity could also serve as a carrier to deliver medical/therapeutic substances through the labelled cells. In the present study, manganese oxide was introduced in the porous network of MCM-48 silica nanoparticles (Mn-M48SNs). The particles exhibit a narrow size distribution (~140 nm diam.) and high porosity (~60% vol.), which was validated after insertion of Mn. The resulting Mn-M48SNs were characterized by TEM, N2 physisorption, and XRD. Evidence was found with H2-TPR, and XPS characterization, that Mn(ii) is the main oxidation state of the paramagnetic species after suspension in water, most probably in the form of Mn-OOH. The colloidal stability as a function of time was confirmed by DLS in water, acetate buffer and cell culture medium. In NMR data, no significant evidence of Mn2+ leaching was found in Mn-M48SNs in acidic water (pH 6), up to 96 hours after suspension. High longitudinal relaxivity values of r1 = 8.4 mM-1 s-1 were measured at 60 MHz and 37 °C, with the lowest relaxometric ratios (r2/r1 = 2) reported to date for a Mn-MSN system. Leukaemia cells (P388) were labelled with Mn-M48SNs and nanoparticle cell internalization was confirmed by TEM. Finally, MRI contrast enhancement provided by cell labelling with escalated incubation concentrations of Mn-M48SNs was quantified at 1 T. This study confirmed the possibility of efficiently confining Mn into M48SNs using incipient wetness, while maintaining an open porosity and relatively high pore volume. Because these Mn-labelled M48SNs express strong ``positive'' contrast media properties at low concentrations, they are potentially applicable for cell tracking and drug delivery methodologies.Mesoporous silica nanoparticles (MSNs) are used in drug delivery and cell tracking applications. As Mn2+ is already implemented as a ``positive'' cell contrast agent in preclinical imaging procedures (in the form of MnCl2 for neurological studies), the introduction of Mn in the porous network of MSNs would allow labelling cells and tracking them using MRI. These particles are in general internalized in endosomes, an acidic environment with high saline concentration. In addition, the available MSN porosity could also serve as a carrier to deliver medical/therapeutic substances through the labelled cells. In the present study, manganese oxide was introduced in the porous network of MCM-48 silica nanoparticles (Mn-M48SNs). The particles exhibit a narrow size distribution (~140 nm diam.) and high porosity (~60% vol.), which was validated after insertion of Mn. The resulting Mn-M48SNs were characterized by TEM, N2 physisorption, and XRD. Evidence was found with H2-TPR, and XPS characterization, that Mn(ii) is the main oxidation state of the paramagnetic species after suspension in water, most probably in the form of Mn-OOH. The colloidal stability as a function of time was confirmed by DLS in water, acetate buffer and cell culture medium. In NMR data, no significant evidence of Mn2+ leaching was found in Mn-M48SNs in acidic water (pH 6), up to 96 hours after suspension. High longitudinal relaxivity values of r1 = 8.4 mM-1 s-1 were measured at 60 MHz and 37 °C, with the lowest relaxometric ratios (r2/r1 = 2) reported to date for a Mn-MSN system. Leukaemia cells (P388) were labelled with Mn-M48SNs and nanoparticle cell internalization was confirmed by TEM. Finally, MRI contrast enhancement provided by cell labelling with escalated incubation concentrations of Mn-M48SNs was quantified at 1 T. This study confirmed the possibility of efficiently confining Mn into M48SNs using incipient wetness

Guillet-Nicolas, Rémy; Laprise-Pelletier, Myriam; Nair, Mahesh M.; Chevallier, Pascale; Lagueux, Jean; Gossuin, Yves; Laurent, Sophie; Kleitz, Freddy; Fortin, Marc-André

2013-11-01

107

Delayed gadolinium-enhanced MRI of the fibrocartilage disc of the temporomandibular joint – a feasibility study  

PubMed Central

Objective To 1) test the feasibility of delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC) at 3 T in the temporomandibular joint (TMJ) and 2) to determine the optimal delay for measurements of the TMJ disc after i.v. contrast agent (CA) administration. Design MRI of the right and left TMJ of six asymptomatic volunteers was performed at 3 T using a dedicated coil. 2D inversion recovery (2D-IR) sequences were performed at 4 time points covering 120 minutes and 3D gradient-echo (3D GRE) dual flip-angle sequences were performed at 14 time points covering 130 minutes after the administration of 0.2 mmol/kg of Gd-diethylenetriamine pentaacetic acid ion (Gd-DTPA)2-, i.e., 0.4 mL of Magnevist™ per kg body weight. Pair-wise tests were used to assess differences between pre-and post-contrast T1 values. Results 2D-IR sequences showed a statistically significant drop (p < 0.001) in T1 values after i.v. CA administration. The T1 drop of 50% was reached 60 minutes after bolus injection in the TMJ disc. The 3D GRE dual flip-angle sequences confirmed these results and show plateau of T1 after 60 minutes. Conclusions T1(Gd) maps calculated from dGEMRIC data allow in vivo assessment of the fibrocartilage disc of the TMJ. The recommended measurement time for dGEMRIC in the TMJ after i.v. CA administration is from 60 to 120 minutes. PMID:25131629

Pittschieler, Elisabeth; Szomolanyi, Pavol; Schmid-Schwap, Martina; Weber, Michael; Egerbacher, Monika; Traxler, Hannes; Trattnig, Siegfried

2014-01-01

108

Manganese-enhanced MRI detection of impaired calcium regulation in a mouse model of cardiac hypertrophy.  

PubMed

The aim of this study was to use manganese (Mn)-enhanced MRI (MEMRI) to detect changes in calcium handling associated with cardiac hypertrophy in a mouse model, and to determine whether the impact of creatine kinase ablation is detectable using this method. Male C57BL/6 (C57, n?=?11) and male creatine kinase double-knockout (CK-M/Mito(-/-) , DBKO, n?=?12) mice were imaged using the saturation recovery Look-Locker T1 mapping sequence before and after the development of cardiac hypertrophy. Hypertrophy was induced via subcutaneous continuous 3-day infusion of isoproterenol, and sham mice not subjected to cardiac hypertrophy were also imaged. During each scan, the contrast agent Mn was administered and the resulting change in R1 (=1/T1 ) was calculated. Two anatomical regions of interest (ROIs) were considered, the left-ventricular free wall (LVFW) and the septum, and one ROI in an Mn-containing standard placed next to the mouse. We found statistically significant (p?

Andrews, Martin; Giger, Maryellen L; Roman, Brian B

2015-02-01

109

Detection of renal ischemic lesions using Gd-DTPA enhanced turbo FLASH MRI: Experimental and clinical results  

SciTech Connect

Our goal was to investigate the role of Gd-DTPA-enhanced dynamic MRI in the evaluation of renal ischemic lesions. With a turbo FLASH sequence before and after injection of Gd-DTPA, nine foxhound dogs after 60-120 min of renal ischemia underwent MR examination. In addition, five patients with a tumor in a solitary kidney were examined before and after nephron-sparing renal surgery to evaluate renal perfusion and function. The experimental and clinical findings were correlated with conventional measurements of kidney function and with histological findings. Complete renal ischemia leads to a poor corticomedullary differentiation in Gd-DTPA-enhanced turbo FLASH MRI. The signal-intensity-versus-time plots of kidneys with significant postischemic changes show a less steep increase of signal intensity in the cortex and a steeper increase of signal intensity in the medulla than those of normal kidneys. Dynamic MRI demonstrate renal morphology and reflect the functional status of the renal vasculature. 21 refs., 8 figs., 1 tab.

Vosshenrich, R.; Fischer, U.; Funke, M.; Kopka, L.; Grabbe, E. [Univ. of Goettingen (Germany)] [and others] [Univ. of Goettingen (Germany); and others

1996-03-01

110

Non-rigid alignment of preoperative MRI, fMRI, and DT-MRI with intra-operative MRI for enhanced visualization and navigation in image-guided neurosurgery  

PubMed Central

Objective The usefulness of neurosurgical navigation with current visualizations is seriously compromised by brain shift, which inevitably occurs during the course of the operation, significantly degrading the precise alignment between the preoperative MR data and the intra-operative shape of the brain. Our objectives were (i) to evaluate the feasibility of non-rigid registration that compensates for the brain deformations within the time constraints imposed by neurosurgery, and (ii) create augmented reality visualizations of critical structural and functional brain regions during neurosurgery using pre-operatively acquired fMRI and DT-MRI. Materials and Methods Eleven consecutive patients with supratentorial gliomas were included in our study. All underwent surgery at our intra-operative MR imaging–guided therapy facility and have tumors in eloquent brain areas (e.g. precentral gyrus and cortico-spinal tract). Functional MRI and DT-MRI, together with MPRAGE and T2w structural MRI were acquired at 3T prior to surgery. SPGR and T2w images were acquired with a 0.5T magnet during each procedure. Quantitative assessment of the alignment accuracy was carried out and compared with current state-of the-art systems based only on rigid-registration. Results Alignment between preoperative and intra-operative datasets was successfully carried out during surgery for all patients. Overall, the mean residual displacement remaining after non-rigid registration was 1.82 mm. There is a statistically significant improvement in alignment accuracy utilizing our non-rigid registration in comparison to the currently used technology (p<0.001). Conclusions We were able to achieve intra-operative rigid and non-rigid registration of (1) pre-operative structural MRI with intra-operative T1w MRI; (2) pre-operative FMRI with intra-operative T1w MRI, and (3) pre-operative DT-MRI with intra-operative T1w MRI. The registration algorithms as implemented were sufficiently robust and rapid to meet the hard real-time constraints of intra-operative surgical decision making. The validation experiments demonstrate that we can accurately compensate for the deformation of the brain and thus can construct an augmented reality visualization to aid the surgeon. PMID:17289403

Archip, Neculai; Clatz, Olivier; Whalen, Stephen; Kacher, Dan; Fedorov, Andriy; Kot, Andriy; Chrisochoides, Nikos; Jolesz, Ferenc; Golby, Alexandra; Black, Peter M.; Warfield, Simon K.

2012-01-01

111

Can contrast-enhanced ultrasound with second-generation contrast agents replace computed tomography angiography for distinguishing between occlusion and pseudo-occlusion of the internal carotid artery?  

PubMed Central

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of contrast-enhanced ultrasound with a second-generation contrast agent in distinguishing between occlusion and pseudo-occlusion of the cervical internal carotid artery, comparing it with that of conventional Doppler ultrasound and the gold standard, computed tomography angiography. METHOD: Between June 2006 and June 2012, we screened 72 symptomatic vascular surgery outpatients at a public hospital. Among those patients, 78 cervical internal carotid arteries were previously classified as occluded by Doppler ultrasound (without contrast). The patients were examined again with Doppler ultrasound, as well as with contrast-enhanced ultrasound and computed tomography angiography. The diagnosis was based on the presence or absence of flow. RESULTS: Among the 78 cervical internal carotid arteries identified as occluded by Doppler ultrasound, occlusion was confirmed by computed tomography angiography in only 57 (73.1%), compared with 59 (77.5%) for which occlusion was confirmed by contrast-enhanced ultrasound (p>0.5 vs. computed tomography angiography). Comparing contrast-enhanced ultrasound with Doppler ultrasound, we found that the proportion of cervical internal carotid arteries classified as occluded was 24.4% higher when the latter was used (p<0.001). CONCLUSIONS: We conclude that, in making the differential diagnosis between occlusion and pseudo-occlusion of the cervical internal carotid artery, contrast-enhanced ultrasound with a second-generation contrast agent is significantly more effective than conventional Doppler ultrasound and is equally as effective as the gold standard (computed tomography angiography). Our findings suggest that contrast-enhanced ultrasound could replace computed tomography angiography in this regard.

Ventura, Carlos Augusto Pinto; da Silva, Erasmo Simão; Cerri, Giovanni Guido; Leão, Pedro Puech; Tachibana, Adriano; Chammas, Maria Cristina

2015-01-01

112

Parameters of Dynamic Contrast-Enhanced MRI as Imaging Markers for Angiogenesis and Proliferation in Human Breast Cancer  

PubMed Central

Background Breast cancer is the most common malignancy and the leading cause of cancer death in women worldwide; however, early diagnosis has been difficult due to its complex pathological structure. This study evaluated the value of morphological examination in conjunction with dynamic contrast-enhanced MRI (DCE-MRI) for more precise diagnosis of breast cancer, as well as their correlation with angiogenesis and proliferation biomarkers. Material/Methods DCE-MRI parameters (including Ktrans: volume transfer coefficient reflecting vascular permeability, Kep: flux rate constant, Ve: extracellular volume ratio reflecting vascular permeability, and ADC: apparent diffusion coefficient) were obtained from 124 patients with breast cancer (124 lesions). Microvessel density (MVD) was evaluated by the immunohistochemical analysis of tumor vessels for CD31 and CD105 expression. The proliferation was assessed by analyzing Ki67. Results Ktrans values were in the order of: malignant lesions > benign lesions > normal glands. Similar results were observed for Kep. The opposite changes were seen with Ve. Ktrans and Kep values were significantly higher in invasive ductal carcinoma (IDC) and ductal carcinoma in situ (DCIS) than in mammary ductal dysplasia (MDD; ANOVA followed by Dunnett’s test). In sharp contrast, ADC values were lower in IDC and DCIS than in MDD, and Ve was not significantly different among the three groups. The data from MIP (maximum intensity projection) showed that benign breast lesions had no or only one blood vessel, whereas malignant lesions had two or more blood vessels. In addition, expression of CD105 and Ki67, the commonly recognized markers for angiogenesis and proliferation, respectively, were closely correlated with MRI parameters as revealed by Pearson analysis. Conclusions Determination of Ktrans, Kep and ADC values permits estimation of tumor angiogenesis and proliferation in breast cancer and DCE-MRI parameters can be used as imaging biomarkers to predict patient prognosis and the biologic aggressiveness of the tumor. PMID:25640082

Li, Lin; Wang, Kai; Sun, Xilin; Wang, Kezheng; Sun, Yingying; Zhang, Guangfeng; Shen, Baozhong

2015-01-01

113

Suitability of Pharmacokinetic Models for Dynamic Contrast-Enhanced MRI of Abdominal Aortic Aneurysm Vessel Wall: A Comparison  

PubMed Central

Purpose Increased microvascularization of the abdominal aortic aneurysm (AAA) vessel wall has been related to AAA progression and rupture. The aim of this study was to compare the suitability of three pharmacokinetic models to describe AAA vessel wall enhancement using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Materials and Methods Patients with AAA underwent DCE-MRI at 1.5 Tesla. The volume transfer constant (Ktrans), which reflects microvascular flow, permeability and surface area, was calculated by fitting the blood and aneurysm vessel wall gadolinium concentration curves. The relative fit errors, parameter uncertainties and parameter reproducibilities for the Patlak, Tofts and Extended Tofts model were compared to find the most suitable model. Scan-rescan reproducibility was assessed using the interclass correlation coefficient and coefficient of variation (CV). Further, the relationship between Ktrans and AAA size was investigated. Results DCE-MRI examinations from thirty-nine patients (mean age±SD: 72±6 years; M/F: 35/4) with an mean AAA maximal diameter of 49±6 mm could be included for pharmacokinetic analysis. Relative fit uncertainties for Ktrans based on the Patlak model (17%) were significantly lower compared to the Tofts (37%) and Extended Tofts model (42%) (p<0.001). Ktrans scan-rescan reproducibility for the Patlak model (ICC?=?0.61 and CV?=?22%) was comparable with the Tofts (ICC?=?0.61, CV?=?23%) and Extended Tofts model (ICC?=?0.76, CV?=?22%). Ktrans was positively correlated with maximal AAA diameter (Spearman’s ??=?0.38, p?=?0.02) using the Patlak model. Conclusion Using the presented imaging protocol, the Patlak model is most suited to describe DCE-MRI data of the AAA vessel wall with good Ktrans scan-rescan reproducibility. PMID:24098370

Nguyen, V. Lai; Kooi, M. Eline; Backes, Walter H.; van Hoof, Raf H. M.; Saris, Anne E. C. M.; Wishaupt, Mirthe C. J.; Hellenthal, Femke A. M. V. I.; van der Geest, Rob J.; Kessels, Alfons G. H.; Schurink, Geert Willem H.; Leiner, Tim

2013-01-01

114

Role of Diffusion Weighted Imaging and Contrast-Enhanced MRI in the Evaluation of Intrapelvic Recurrence of Gynecological Malignant Tumor  

PubMed Central

Background and Purpose To investigate the diagnostic performance of diffusion-weighted imaging (DWI) and contrast-enhanced imaging in combination with T2-weighted imaging (T2WI) for magnetic resonance imaging (MRI) evaluation of intrapelvic recurrence of gynecological malignancies. Materials and Methods Sixty-two patients with suspected intrapelvic recurrence of gynecological malignancies underwent pelvic MRI including T2WI DWI, and contrast-enhanced imaging. Diagnostic performance for detection of local recurrence, pelvic lymph node and bone metastases, and peritoneal lesions was evaluated by consensus reading of two experienced radiologists using a 5-point scoring system, and compared among T2WI with unenhanced T1-weighted imaging (T1WI) (protocol A), a combination of protocol A and DWI (protocol B), and a combination of protocol B and contrast-enhanced imaging (protocol C). Final diagnoses were obtained by histopathological examinations, radiological imaging and clinical follow-up for at least 6 months. Receiver operating characteristic (ROC) analysis and McNemar test were employed for statistical analysis. Results Locally recurrent disease, lymph node recurrence, peritoneal dissemination and bone metastases were present in 48.4%, 29.0%, 16.1%, and 6.5% of the patients, respectively. The patient-based sensitivity, specificity, accuracy, and area under the ROC curve (AUC) for detection of intrapelvic recurrence were 55.0, 81.8, 64.5% and 0.753 for protocol A, 80.0, 77.3, 79.0% and 0.838 for protocol B, and 80.0, 90.9, 83.9% and 0.862 for protocol C, respectively. The sensitivity, accuracy, and AUC were significantly better for protocols B and C than for protocol A (p<0.001). There was no significant difference between protocols B and C. Conclusion MRI using a combination of DWI and T2WI gives comparatively acceptable results for assessment of intrapelvic recurrence of gynecological malignancies. PMID:25629156

Kitajima, Kazuhiro; Tanaka, Utaru; Ueno, Yoshiko; Maeda, Tetsuo; Suenaga, Yuko; Takahashi, Satoru; Deguchi, Masashi; Miyahara, Yoshiya; Ebina, Yasuhiko; Yamada, Hideto; Tsurusaki, Masakatsu; Tamaki, Yukihisa; Sugimura, Kazuro

2015-01-01

115

In Vivo Assessment of Aqueous Humor Dynamics Upon Chronic Ocular Hypertension and Hypotensive Drug Treatment Using Gadolinium-Enhanced MRI  

PubMed Central

Purpose. Although glaucoma treatments alter aqueous humor (AH) dynamics to lower intraocular pressure, the regulatory mechanisms of AH circulation and their contributions to the pathogenesis of ocular hypertension and glaucoma remain unclear. We hypothesized that gadolinium-enhanced magnetic resonance imaging (Gd-MRI) can visualize and assess AH dynamics upon sustained intraocular pressure elevation and pharmacologic interventions. Methods. Gadolinium contrast agent was systemically administered to adult rats to mimic soluble AH components entering the anterior chamber (AC) via blood–aqueous barrier. Dynamic Gd-MRI was applied to examine the signal enhancement in AC and vitreous body upon microbead-induced ocular hypertension and unilateral topical applications of latanoprost, timolol maleate, and brimonidine tartrate to healthy eyes. Results. Gadolinium signal time courses in microbead-induced hypertensive eyes possessed faster initial gadolinium uptake and higher peak signals in AC than control eyes, reflective of reduced gadolinium clearance upon microbead occlusion. Opposite trends were observed in latanoprost- and timolol-treated eyes, indicative of their respective drug actions on increased uveoscleral outflow and reduced AH production. The slowest initial gadolinium uptake but strongest peak signals were found in AC of both brimonidine-treated and untreated fellow eyes. These findings drew attention to the systemic effects of topical hypotensive drug treatment. Gadolinium leaked into the vitreous of microbead-induced hypertensive eyes and brimonidine-treated and untreated fellow eyes, suggestive of a compromise of aqueous–vitreous or blood–ocular barrier integrity. Conclusions. Gadolinium-enhanced MRI allows spatiotemporal and quantitative evaluation of altered AH dynamics and ocular tissue permeability for better understanding the physiological mechanisms of ocular hypertension and the efficacy of antiglaucoma drug treatments. PMID:24764067

Ho, Leon C.; Conner, Ian P.; Do, Chi-Wai; Kim, Seong-Gi; Wu, Ed X.; Wollstein, Gadi; Schuman, Joel S.; Chan, Kevin C.

2014-01-01

116

Preliminary Study of Oxygen-Enhanced Longitudinal Relaxation in MRI: A Potential Novel Biomarker of Oxygenation Changes in Solid Tumors  

SciTech Connect

Purpose: There is considerable interest in developing non-invasive methods of mapping tumor hypoxia. Changes in tissue oxygen concentration produce proportional changes in the magnetic resonance imaging (MRI) longitudinal relaxation rate (R{sub 1}). This technique has been used previously to evaluate oxygen delivery to healthy tissues and is distinct from blood oxygenation level-dependent (BOLD) imaging. Here we report application of this method to detect alteration in tumor oxygenation status. Methods and materials: Ten patients with advanced cancer of the abdomen and pelvis underwent serial measurement of tumor R{sub 1} while breathing medical air (21% oxygen) followed by 100% oxygen (oxygen-enhanced MRI). Gadolinium-based dynamic contrast-enhanced MRI was then performed to compare the spatial distribution of perfusion with that of oxygen-induced DELTAR{sub 1}. Results: DELTAR{sub 1} showed significant increases of 0.021 to 0.058 s{sup -1} in eight patients with either locally recurrent tumor from cervical and hepatocellular carcinomas or metastases from ovarian and colorectal carcinomas. In general, there was congruency between perfusion and oxygen concentration. However, regional mismatch was observed in some tumor cores. Here, moderate gadolinium uptake (consistent with moderate perfusion) was associated with low area under the DELTAR{sub 1} curve (consistent with minimal increase in oxygen concentration). Conclusions: These results provide evidence that oxygen-enhanced longitudinal relaxation can monitor changes in tumor oxygen concentration. The technique shows promise in identifying hypoxic regions within tumors and may enable spatial mapping of change in tumor oxygen concentration.

O'Connor, James P.B. [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom) and Cancer Research UK Department of Medical Oncology, Christie Hospital, Manchester (United Kingdom); Naish, Josephine H.; Parker, Geoff J.M. [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom); Waterton, John C. [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom); AstraZeneca, Cheshire (United Kingdom); Watson, Yvonne [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom); Jayson, Gordon C. [Cancer Research UK Department of Medical Oncology, Christie Hospital, Manchester (United Kingdom); Buonaccorsi, Giovanni A.; Cheung, Sue; Buckley, David L.; McGrath, Deirdre M. [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom); West, Catharine M.L. [Academic Department of Radiation Oncology, University of Manchester, Manchester (United Kingdom); Davidson, Susan E. [Department of Clinical Oncology, Christie Hospital, Manchester (United Kingdom); Roberts, Caleb; Mills, Samantha J. [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom); Mitchell, Claire L.; Hope, Lynn; Ton, N. Chan [Cancer Research UK Department of Medical Oncology, Christie Hospital, Manchester (United Kingdom); Jackson, Alan [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom)

2009-11-15

117

Retrieval of Brain Tumors with Region-Specific Bag-of-Visual-Words Representations in Contrast-Enhanced MRI Images  

PubMed Central

A content-based image retrieval (CBIR) system is proposed for the retrieval of T1-weighted contrast-enhanced MRI (CE-MRI) images of brain tumors. In this CBIR system, spatial information in the bag-of-visual-words model and domain knowledge on the brain tumor images are considered for the representation of brain tumor images. A similarity metric is learned through a distance metric learning algorithm to reduce the gap between the visual features and the semantic concepts in an image. The learned similarity metric is then used to measure the similarity between two images and then retrieve the most similar images in the dataset when a query image is submitted to the CBIR system. The retrieval performance of the proposed method is evaluated on a brain CE-MRI dataset with three types of brain tumors (i.e., meningioma, glioma, and pituitary tumor). The experimental results demonstrate that the mean average precision values of the proposed method range from 90.4% to 91.5% for different views (transverse, coronal, and sagittal) with an average value of 91.0%. PMID:23243462

Huang, Meiyan; Yang, Wei; Yu, Mei; Lu, Zhentai; Feng, Qianjin; Chen, Wufan

2012-01-01

118

Quantitative Estimation of Renal Function with Dynamic Contrast-Enhanced MRI Using a Modified Two-Compartment Model  

PubMed Central

Objective To establish a simple two-compartment model for glomerular filtration rate (GFR) and renal plasma flow (RPF) estimations by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Materials and Methods A total of eight New Zealand white rabbits were included in DCE-MRI. The two-compartment model was modified with the impulse residue function in this study. First, the reliability of GFR measurement of the proposed model was compared with other published models in Monte Carlo simulation at different noise levels. Then, functional parameters were estimated in six healthy rabbits to test the feasibility of the new model. Moreover, in order to investigate its validity of GFR estimation, two rabbits underwent acute ischemia surgical procedure in unilateral kidney before DCE-MRI, and pixel-wise measurements were implemented to detect the cortical GFR alterations between normal and abnormal kidneys. Results The lowest variability of GFR and RPF measurements were found in the proposed model in the comparison. Mean GFR was 3.03±1.1 ml/min and mean RPF was 2.64±0.5 ml/g/min in normal animals, which were in good agreement with the published values. Moreover, large GFR decline was found in dysfunction kidneys comparing to the contralateral control group. Conclusion Results in our study demonstrate that measurement of renal kinetic parameters based on the proposed model is feasible and it has the ability to discriminate GFR changes in healthy and diseased kidneys. PMID:25141138

Chen, Bin; Zhang, Yudong; Song, Xiaojian; Wang, Xiaoying; Zhang, Jue; Fang, Jing

2014-01-01

119

Phase-contrast MRI and 3D-CISS versus contrast-enhanced MR cisternography on the evaluation of the aqueductal stenosis  

Microsoft Academic Search

Introduction  In the current study, we aimed to compare the diagnostic efficacies of phase-contrast magnetic resonance imaging (PC-MRI)\\u000a and three-dimensional constructive interference in steady-state (3D-CISS) sequence over detection of aqueductal stenosis (AS)\\u000a on the basis of contrast-enhanced magnetic resonance cisternography (MRC).\\u000a \\u000a \\u000a \\u000a Methods  Twenty-five patients with clinically and radiologically suspected AS were examined by PC-MRI, 3D-CISS, and MRC. Axial–sagittal\\u000a PC-MRI and sagittal 3D-CISS

Oktay Algin; Bahattin Hakyemez; Mufit Parlak

2010-01-01

120

Examining the acute effects of cediranib (RECENTIN, AZD2171) treatment in tumor models: a dynamic contrast-enhanced MRI study using gadopentate  

Microsoft Academic Search

Cediranib (RECENTIN, AZD2171) is a highly potent inhibitor of the tyrosine kinase activity associated with all three vascular endothelial growth factor (VEGF) receptors and is currently in Phase II\\/III clinical trials. Preclinically, cediranib inhibits VEGF signaling and angiogenesis in vivo and impedes solid tumor growth significantly. Clinically, changes observed using dynamic contrast-enhanced MRI (DCE-MRI) with gadopentate suggest that acute cediranib

Daniel P. Bradley; Jean J. Tessier; Tony Lacey; Marietta Scott; Juliane M. Jürgensmeier; Rajesh Odedra; Jonathan Mills; Lyndsey Kilburn; Stephen R. Wedge

2009-01-01

121

pH-Responsive Theranostic Polymer-Caged Nanobins (PCNs): Enhanced Cytotoxicity and T1 MRI Contrast by Her2-Targeting  

PubMed Central

A PCN theranostic platform comprises a doxorubicin (DXR)-loaded liposomal core and an acid-sensitive polymer shell that is functionalized with Herceptin and GdIII-based MRI contrast agents. In vitro testing reveals a 14-fold increase in DXR-based cytotoxicity versus a non-targeted analogue and an 120-fold improvement in cellular GdIII–uptake in comparison with clinically approved DOTA-GdIII, leading to significant T1 MRI contrast enhancement. PMID:24516291

Hong, Bong Jin; Swindell, Elden P.; MacRenaris, Keith W.; Hankins, Patrick L.; Chipre, Anthony J.; Mastarone, Daniel J.; Ahn, Richard W.; Meade, Thomas J.; O’Halloran, Thomas V.

2014-01-01

122

An aqueous method for the controlled manganese (Mn(2+)) substitution in superparamagnetic iron oxide nanoparticles for contrast enhancement in MRI.  

PubMed

Despite the success in the use of superparamagnetic iron oxide nanoparticles (SPION) for various scientific applications, its potential in biomedical fields has not been exploited to its full potential. In this context, an in situ substitution of Mn(2+) was performed in SPION and a series of ferrite particles, MnxFe1-xFe2O4 with a varying molar ratio of Mn(2+)?:?Fe(2+) where 'x' varies from 0-0.75. The ferrite particles obtained were further studied in MRI contrast applications and showed appreciable enhancement in their MRI contrast properties. Manganese substituted ferrite nanocrystals (MnIOs) were synthesized using a novel, one-step aqueous co-precipitation method based on the use of a combination of sodium hydroxide and trisodium citrate (TSC). This approach yielded the formation of highly crystalline, superparamagnetic MnIOs with good control over their size and bivalent Mn ion crystal substitution. The presence of a TSC hydrophilic layer on the surface facilitated easy dispersion of the materials in an aqueous media. Primary characterizations such as structural, chemical and magnetic properties demonstrated the successful formation of manganese substituted ferrite. More significantly, the MRI relaxivity of the MnIOs improved fourfold when compared to SPION crystals imparting high potential for use as an MRI contrast agent. Further, the cytocompatibility and blood compatibility evaluations demonstrated excellent cell morphological integrity even at high concentrations of nanoparticles supporting the non-toxic nature of nanoparticles. These results open new horizons for the design of biocompatible water dispersible ferrite nanoparticles with good relaxivity properties via a versatile and easily scalable co-precipitation route. PMID:25586703

Ereath Beeran, Ansar; Nazeer, Shaiju S; Fernandez, Francis Boniface; Muvvala, Krishna Surendra; Wunderlich, Wilfried; Anil, Sukumaran; Vellappally, Sajith; Ramachandra Rao, M S; John, Annie; Jayasree, Ramapurath S; Harikrishna Varma, P R

2015-01-28

123

Assessment of tumor necrotic fraction by dynamic contrast-enhanced MRI: a preclinical study of human tumor xenografts with histopathologic correlation.  

PubMed

Contrary to the common notion that tumor necrotic regions are non-enhancing after contrast administration, recent evidence has shown that necrotic regions exhibit delayed and slow uptake of gadolinium tracer on dynamic contrast-enhanced MRI (DCE MRI). The purpose of this study is to explore whether the mapping of tumor voxels with delayed and slow enhancement on DCE MRI can be used to derive estimates of tumor necrotic fraction. Patient-derived tumor xenograft lines of seven human cancers were implanted in 26 mice which were subjected to DCE MRI performed using a spoiled gradient recalled sequence. Gadolinium tracer concentration was estimated using the variable flip angle technique. To identify tumor voxels exhibiting delayed and slow uptake of contrast medium, clustering analysis was performed using a k-means clustering algorithm that classified tumor voxels according to their contrast enhancement patterns. Comparison of the percentage of tumor voxels exhibiting delayed and slow enhancement with the tumor necrotic fraction estimated on histology showed a strong correlation (r?=?0.962, p?MRI correlated strongly with tumor necrotic fraction, and can potentially serve as a non-invasive imaging surrogate for the in vivo assessment of necrotic fraction. PMID:24535773

Koh, Tong San; Thng, Choon Hua; Hartono, Septian; Dominguez, Lourdes T M; Lim, Tony K H; Huynh, Hung; Martarello, Laurent; Ng, Quan Sing

2014-04-01

124

Added value of hepatobiliary phase gadoxetic acid-enhanced MRI for diagnosing hepatocellular carcinoma in high-risk patients  

PubMed Central

AIM: To determine the added value of hepatobiliary phase (HBP) gadoxetic acid-enhanced magnetic resonance imaging (MRI) in evaluating hepatic nodules in high-risk patients. METHODS: The institutional review board approved this retrospective study and waived the requirement for informed consent. This study included 100 patients at high risk for hepatocellular carcinoma (HCC) and 105 hepatic nodules that were larger than 1 cm. A blind review of two MR image sets was performed in a random order: set 1, unenhanced (T1- and T2-weighted) and dynamic images; and set 2, unenhanced, dynamic 20-min and HBP images. The diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were compared for the two image sets. Univariate and multivariate analyses were performed on the MR characteristics utilized to diagnose HCC. RESULTS: A total of 105 hepatic nodules were identified in 100 patients. Fifty-nine nodules were confirmed to be HCC. The diameter of the 59 HCCs ranged from 1 to 12 cm (mean: 1.9 cm). The remaining 46 nodules were benign (28 were of hepatocyte origin, nine were hepatic cysts, seven were hemangiomas, one was chronic inflammation, and one was focal fat infiltration). The diagnostic accuracy significantly increased with the addition of HBP images, from 88.7% in set 1 to 95.5% in set 2 (P = 0.002). In set 1 vs set 2, the sensitivity and NPV increased from 79.7% to 93.2% and from 78.9% to 91.8%, respectively, whereas the specificity and PPV were not significantly different. The hypointensity on the HBP images was the most sensitive (93.2%), and typical arterial enhancement followed by washout was the most specific (97.8%). The multivariate analysis revealed that typical arterial enhancement followed by washout, hyperintensity on T2-weighted images, and hypointensity on HBP images were statistically significant MRI findings that could diagnose HCC (P < 0.05). CONCLUSION: The addition of HBP gadoxetic acid-enhanced MRI statistically improved the diagnostic accuracy in HCCs larger than 1 cm. Typical arterial enhancement followed by washout and hypointensity on HBP images are useful for diagnosing HCC. PMID:24363528

Phongkitkarun, Sith; Limsamutpetch, Kuruwin; Tannaphai, Penampai; Jatchavala, Janjira

2013-01-01

125

Diagnostic efficacy of gadoxetic acid-enhanced MRI for the detection and characterisation of liver metastases: comparison with multidetector-row CT  

PubMed Central

Objectives We compared the diagnostic performance of gadoxetic acid-enhanced MRI and 16-slice multidetector CT (MDCT) with respect to their abilities to detect hepatic metastases and differentiate hepatic metastases from hepatic cysts and haemangiomas. Methods 67 patients with 110 liver metastases (size 0.3–2.5 cm), 33 haemangiomas (size 0.5–1.5 cm) and 17 cysts (size 0.3–1.0 cm) underwent 4-phase MDCT and gadoxetic acid-enhanced MRI, including early dynamic phases, post-contrast T2 weighted turbo spin echo sequences and 20 min hepatocyte-selective phases. Two observers independently analysed each image in random order. Sensitivity and diagnostic accuracy for lesion detection and differentiation for MDCT and gadoxetic acid-enhanced MRI were calculated using receiver operating characteristic analysis. Results For both observers, the Az values of gadoxetic acid-enhanced MRI (mean, 0.982 and 0.981) were significantly higher than the Az values of MDCT (mean, 0.839 and 0.892) (p<0.05) for the detection of metastases and for the differentiation of metastases from haemangiomas and cysts. Sensitivities of gadoxetic acid-enhanced MRI with regard to the detection and characterisation of liver metastases (mean, 96.9% and 96.0%) were significantly higher than those of MDCT (mean, 78.7% and 75.0%) (p<0.05). Conclusion Gadoxetic acid-enhanced MRI showed higher diagnostic accuracy and sensitivity than did MDCT for the detection of hepatic metastases and for the differentiation between hepatic metastases and hepatic haemangiomas or cysts. PMID:22556405

Kim, Y K; Park, G; Kim, C S; Yu, H C; Han, Y M

2012-01-01

126

Blood-ocular barrier damage: use of contrast-enhanced MRI.  

PubMed

The blood-ocular barrier (BOB) shares similar neuroepithelial origin, microanatomy and functions with the blood-brain barrier. There are many natural (e. g. diabetes, hypertension) or iatrogenic (chemotherapy, retinal photocoagulation) conditions which can cause a BOB breakdown, resulting in visual acuity impairment or loss. The authors examined 42 patients affected by BOB damage in different pathological conditions. All patients previously underwent a conventional fluoroangiographic (FA) study. Nine patients with normal FA exam were evaluated also. Despite normal MRI findings immediately after Gd-DTPA injection, contrast leakage into the vitreous body or into the aqueous fluid was demonstrated in delayed scans (40-50 min after contrast administration), proving the existence of a BOB damage (sensitively 94 %). Although FA exam remains the choice modality in BOB breakdown demonstration, we propose MRI as a useful diagnostic tool when optic media opacity (cataract, haemovitreous, intraocular silicon oil) occurs, preventing direct retinal fundus imaging and/or an early screening tool. PMID:9000410

Manfré, L; Midiri, M; Giuffré, G; Mangiameli, A; Cardella, G; Ponte, F; De Maria, M; Lagalla, R

1997-01-01

127

Hemophilic arthropathy of the knee joint: static and dynamic Gd-DTPA — enhanced MRI  

Microsoft Academic Search

A total of 17 patients with hemophilic arthropathy of the knee joint were studied with static and dynamic MRI before and after an IV bolus injection of Gadolinium-DTPA (Gd-DTPA; 0.1 mmol\\/kg body weight). The T1-weighted spin-echo (SE) and gradient-echo (fast-field echo [FFE]) sequences were applied. The FFE sequences of eight consecutive scans carried out over a time interval of 160

M. Nägele; R. Brüning; V. Kunze; H. Eickhoff; W. Koch; M. Reiser

1995-01-01

128

Sol and Gel States in Peptide Hydrogels Visualized by Gd(III)-enhanced MRI  

PubMed Central

The hydrogels assembled from a pair of self-repulsive but mutually-attractive decapeptides are visualized by magnetic resonance imaging. It is found that in the absence of Gd(III)-chelate, gelation has little effect on MRI signal intensity. In the presence of Gd(III)-chelate, gelation leads to significant changes in water relaxation and MR signal intensity. The sol to gel transition is best visualized by T2-weighted imaging using large echo time with the sol producing a bright spot and the gel producing a dark spot. MRI studies indicate high local Gd(III)-chelate concentration. Small-angle X-ray scattering study indicates that this local enrichment of Gd(III)-chelate has two contributing processes: first, the aggregation of peptides into fibers; second, within peptide fibers, Gd(III)-chelate further aggregate into clusters. This work demonstrates that the status of peptide-based hydrogels can be visualized by MRI with the aid of covalently linked Gd(III)-chelates. This result has implications for monitoring peptide scaffolds in vivo. PMID:22252424

Weerasekare, Mahika; Taraban, Marc B.; Shi, Xianfeng; Jeong, Eun-Kee; Trewhella, Jill; Yu, Yihua Bruce

2013-01-01

129

MRI-based estimation of liver function: Gd-EOB-DTPA-enhanced T1 relaxometry of 3T vs. the MELD score  

PubMed Central

Gd-EOB-DTPA is a hepatocyte-specific MRI contrast agent. Due to its hepatocyte-specific uptake and paramagnetic properties, functioning areas of the liver exhibit shortening of the T1 relaxation time. We report the potential use of T1 relaxometry of the liver with Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) for estimating the liver function as expressed by the MELD score. 3 T MRI relaxometry was performed before and 20?min after Gd-EOB-DTPA administration. A strong correlation between changes in the T1 relaxometry and the extent of liver disease, expressed by the MELD score, was documented. Reduced liver function correlates with decreased Gd-EOB-DTPA accumulation in the hepatocytes during the hepatobiliary phase. MRI-based T1 relaxometry with Gd-EOB-DTPA may be a useful method for assessing overall and segmental liver function. PMID:25001391

Haimerl, Michael; Verloh, Niklas; Fellner, Claudia; Zeman, Florian; Teufel, Andreas; Feigl, Stefan Fichtner-; Schreyer, Andreas G.; Stroszczynski, Christian; Wiggermann, Philipp

2014-01-01

130

Gd2O3 nanoparticles in hematopoietic cells for MRI contrast enhancement  

PubMed Central

As the utility of magnetic resonance imaging (MRI) broadens, the importance of having specific and efficient contrast agents increases and in recent time there has been a huge development in the fields of molecular imaging and intracellular markers. Previous studies have shown that gadolinium oxide (Gd2O3) nanoparticles generate higher relaxivity than currently available Gd chelates: In addition, the Gd2O3 nanoparticles have promising properties for MRI cell tracking. The aim of the present work was to study cell labeling with Gd2O3 nanoparticles in hematopoietic cells and to improve techniques for monitoring hematopoietic stem cell migration by MRI. Particle uptake was studied in two cell lines: the hematopoietic progenitor cell line Ba/F3 and the monocytic cell line THP-1. Cells were incubated with Gd2O3 nanoparticles and it was investigated whether the transfection agent protamine sulfate increased the particle uptake. Treated cells were examined by electron microscopy and MRI, and analyzed for particle content by inductively coupled plasma sector field mass spectrometry. Results showed that particles were intracellular, however, sparsely in Ba/F3. The relaxation times were shortened with increasing particle concentration. Relaxivities, r1 and r2 at 1.5 T and 21°C, for Gd2O3 nanoparticles in different cell samples were 3.6–5.3 s?1 mM?1 and 9.6–17.2 s?1 mM?1, respectively. Protamine sulfate treatment increased the uptake in both Ba/F3 cells and THP-1 cells. However, the increased uptake did not increase the relaxation rate for THP-1 as for Ba/F3, probably due to aggregation and/or saturation effects. Viability of treated cells was not significantly decreased and thus, it was concluded that the use of Gd2O3 nanoparticles is suitable for this type of cell labeling by means of detecting and monitoring hematopoietic cells. In conclusion, Gd2O3 nanoparticles are a promising material to achieve positive intracellular MRI contrast; however, further particle development needs to be performed. PMID:22228991

Hedlund, Anna; Ahrén, Maria; Gustafsson, Håkan; Abrikossova, Natalia; Warntjes, Marcel; Jönsson, Jan-Ingvar; Uvdal, Kajsa; Engström, Maria

2011-01-01

131

The use of error-category mapping in pharmacokinetic model analysis of dynamic contrast-enhanced MRI data.  

PubMed

This study introduces the use of 'error-category mapping' in the interpretation of pharmacokinetic (PK) model parameter results derived from dynamic contrast-enhanced (DCE-) MRI data. Eleven patients with metastatic renal cell carcinoma were enrolled in a multiparametric study of the treatment effects of bevacizumab. For the purposes of the present analysis, DCE-MRI data from two identical pre-treatment examinations were analysed by application of the extended Tofts model (eTM), using in turn a model arterial input function (AIF), an individually-measured AIF and a sample-average AIF. PK model parameter maps were calculated. Errors in the signal-to-gadolinium concentration ([Gd]) conversion process and the model-fitting process itself were assigned to category codes on a voxel-by-voxel basis, thereby forming a colour-coded 'error-category map' for each imaged slice. These maps were found to be repeatable between patient visits and showed that the eTM converged adequately in the majority of voxels in all the tumours studied. However, the maps also clearly indicated sub-regions of low Gd uptake and of non-convergence of the model in nearly all tumours. The non-physical condition ve ?1 was the most frequently indicated error category and appeared sensitive to the form of AIF used. This simple method for visualisation of errors in DCE-MRI could be used as a routine quality-control technique and also has the potential to reveal otherwise hidden patterns of failure in PK model applications. PMID:25460333

Gill, Andrew B; Anandappa, Gayathri; Patterson, Andrew J; Priest, Andrew N; Graves, Martin J; Janowitz, Tobias; Jodrell, Duncan I; Eisen, Tim; Lomas, David J

2015-02-01

132

Brain Processing of Biologically Relevant Odors in the Awake Rat, as Revealed by Manganese-Enhanced MRI  

PubMed Central

Background So far, an overall view of olfactory structures activated by natural biologically relevant odors in the awake rat is not available. Manganese-enhanced MRI (MEMRI) is appropriate for this purpose. While MEMRI has been used for anatomical labeling of olfactory pathways, functional imaging analyses have not yet been performed beyond the olfactory bulb. Here, we have used MEMRI for functional imaging of rat central olfactory structures and for comparing activation maps obtained with odors conveying different biological messages. Methodology/Principal Findings Odors of male fox feces and of chocolate flavored cereals were used to stimulate conscious rats previously treated by intranasal instillation of manganese (Mn). MEMRI activation maps showed Mn enhancement all along the primary olfactory cortex. Mn enhancement elicited by male fox feces odor and to a lesser extent that elicited by chocolate odor, differed from that elicited by deodorized air. This result was partly confirmed by c-Fos immunohistochemistry in the piriform cortex. Conclusion/Significance By providing an overall image of brain structures activated in awake rats by odorous stimulation, and by showing that Mn enhancement is differently sensitive to different stimulating odors, the present results demonstrate the interest of MEMRI for functional studies of olfaction in the primary olfactory cortex of laboratory small animals, under conditions close to natural perception. Finally, the factors that may cause the variability of the MEMRI signal in response to different odor are discussed. PMID:23119035

Lehallier, Benoist; Rampin, Olivier; Saint-Albin, Audrey; Jérôme, Nathalie; Ouali, Christian; Maurin, Yves; Bonny, Jean-Marie

2012-01-01

133

Comparison of model-based arterial input functions for dynamic contrast-enhanced MRI in tumor bearing rats.  

PubMed

When using tracer kinetic modeling to analyze dynamic contrast-enhanced MRI (DCE-MRI) it is necessary to identify an appropriate arterial input function (AIF). The measured AIF is often poorly sampled in both clinical and preclinical MR systems due to the initial rapid increase in contrast agent concentration and the subsequent large-scale signal change that occurs in the arteries. However, little work has been carried out to quantify the sensitivity of tracer kinetic modeling parameters to the form of AIF. Using a preclinical experimental data set, we sought to measure the effect of varying model forms of AIF on the extended Kety compartmental model parameters (K(trans), v(e), and v(p)) through comparison with the results of experimentally acquired high temporal resolution AIFs. The AIF models examined have the potential to be parameterized on lower temporal resolution data to predict the form of the true, higher temporal resolution AIF. The models were also evaluated through application to the population average AIF. It was concluded that, in the instance of low temporal resolution or noisy data, it may be preferable to use a bi-exponential model applied to the raw data AIF, or when individual measurements are not available a bi-exponential model of the average AIF. PMID:19253360

McGrath, Deirdre M; Bradley, Daniel P; Tessier, Jean L; Lacey, Tony; Taylor, Chris J; Parker, Geoffrey J M

2009-05-01

134

Gd-EOB-DTPA-enhanced 3.0-Tesla MRI findings for the preoperative detection of focal liver lesions: Comparison with iodine-enhanced multi-detector computed tomography  

NASA Astrophysics Data System (ADS)

The safety of gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid (Gd-EOB-DTPA) has been confirmed, but more study is needed to assess the diagnostic accuracy of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) in patients with a hepatocellular carcinoma (HCC) for whom surgical treatment is considered or with a metastatic hepatoma. Research is also needed to examine the rate of detection of hepatic lesions compared to multi-detector computed tomography (MDCT), which is used most frequently to localize and characterize a HCC. Gd-EOB-DTPA-enhanced MRI and iodine-enhanced MDCT imaging were compared for the preoperative detection of focal liver lesions. The clinical usefulness of each method was examined. The current study enrolled 79 patients with focal liver lesions who preoperatively underwent MRI and MDCT. In these patients, there was less than one month between the two diagnostic modalities. Imaging data were taken before and after contrast enhancement in both methods. To evaluate the images, we analyzed the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) in the lesions and the liver parenchyma. To compare the sensitivity of the two methods, we performed a quantitative analysis of the percentage signal intensity of the liver (PSIL) on a high resolution picture archiving and communication system (PACS) monitor (paired-samples t-test, p < 0.05). The enhancement was evaluated based on a consensus of four observers. The enhancement pattern and the morphological features during the arterial and the delayed phases were correlated between the Gd-EOB-DTPA-enhanced MRI findings and the iodine-enhanced MDCT by using an adjusted x2 test. The SNRs, CNRs, and PSIL all had a greater detection rate in Gd-EOB-DTPA enhanced MRI than in iodine-enhanced MDCT. Hepatocyte-selective uptake was observed 20 minutes after the injection in the focal nodular hyperplasia (FNH, 9/9), adenoma (9/10), and highly-differentiated HCC (grade G1, 27/30). Rim enhancement was detected in all metastases (30/30). During the arterial and the delayed phases, good overall agreement between the gadoxetic-acid-enhanced MR and CT was observed (x2 test, p < 0.05). For the preoperative detection of focal liver lesions, Gd-EOB-DTPA-enhanced MRI had a higher diagnostic value and higher detection rate than iodine-enhanced MDCT. The arterial and the delayed dynamic enhancement patterns, and the gadoxetic-acid-enhanced MR imaging can provide information on the possible degree of cellular differentiation of a HCC, adenoma or metastatic tumor.

Park, Hyong-Hu; Goo, Eun-Hoe; Im, In-Chul; Lee, Jae-Seung; Kim, Moon-Jib; Kwak, Byung-Joon; Chung, Woon-Kwan; Dong, Kyung-Rae

2012-12-01

135

Vertical distribution of specific ventilation in normal supine humans measured by oxygen-enhanced proton MRI  

PubMed Central

Specific ventilation (SV) is the ratio of fresh gas entering a lung region divided by its end-expiratory volume. To quantify the vertical (gravitationally dependent) gradient of SV in eight healthy supine subjects, we implemented a novel proton magnetic resonance imaging (MRI) method. Oxygen is used as a contrast agent, which in solution changes the longitudinal relaxation time (T1) in lung tissue. Thus alterations in the MR signal resulting from the regional rise in O2 concentration following a sudden change in inspired O2 reflect SV—lung units with higher SV reach a new equilibrium faster than those with lower SV. We acquired T1-weighted inversion recovery images of a sagittal slice of the supine right lung with a 1.5-T MRI system. Images were voluntarily respiratory gated at functional residual capacity; 20 images were acquired with the subject breathing air and 20 breathing 100% O2, and this cycle was repeated five times. Expired tidal volume was measured simultaneously. The SV maps presented an average spatial fractal dimension of 1.13 ± 0.03. There was a vertical gradient in SV of 0.029 ± 0.012 cm?1, with SV being highest in the dependent lung. Dividing the lung vertically into thirds showed a statistically significant difference in SV, with SV of 0.42 ± 0.14 (mean ± SD), 0.29 ± 0.10, and 0.24 ± 0.08 in the dependent, intermediate, and nondependent regions, respectively (all differences, P < 0.05). This vertical gradient in SV is consistent with the known gravitationally induced deformation of the lung resulting in greater lung expansion in the dependent lung with inspiration. This SV imaging technique can be used to quantify regional SV in the lung with proton MRI. PMID:20930129

Cronin, Matthew V.; Cortney Henderson, A.; Holverda, Sebastiaan; Theilmann, Rebecca J.; Arai, Tatsuya J.; Dubowitz, David J.; Hopkins, Susan R.; Buxton, Richard B.; Kim Prisk, G.

2010-01-01

136

Dual Manganese-Enhanced and Delayed Gadolinium-Enhanced MRI Detects Myocardial Border Zone Injury in a Pig Ischemia-Reperfusion Model  

PubMed Central

Background Delayed gadolinium (Gd) enhancement MRI (DEMRI) identifies non-viable myocardium, but is non-specific and may overestimate nonviable territory. Manganese (Mn2+)-enhanced MRI (MEMRI) denotes specific Mn2+ uptake into viable cardiomyocytes. We performed a dual-contrast myocardial assessment in a porcine ischemia-reperfusion (IR) model to test the hypothesis that combined DEMRI and MEMRI will identify viable infarct border zone (BZ) myocardium in vivo. Methods and Results Sixty-minute LAD ischemia-reperfusion injury (IR) was induced in 13 adult swine. Twenty-one days post-IR, 3T cardiac MRI was performed. MEMRI was obtained after injection (0.7 cc/kg) of Mn2+ contrast agent (EVP1001-1, Eagle Vision Pharmaceutical Corp.). DEMRI was then acquired after 0.2mmol/kg Gd injection. Left ventricular (LV) mass, infarct, and function were analyzed. Subtraction of MEMRI defect from DEMRI signal identified injured border zone myocardium. Explanted hearts were analyzed by 2,3,5-triphenyltetrazolium chloride (TTC) stain and tissue electron microscopy (TEM) to compare infarct, BZ, and remote myocardium. Average LV ejection fraction was reduced (30±7%). MEMRI and DEMRI infarct volumes correlated with TTC (MEMRI: r=0.78; DEMRI: r=0.75; p<0.004). MEMRI infarct volume percentage was significantly lower than DEMRI (14±4%* vs. 23±4%; *p<0.05). BZ MEMRI SNR was intermediate to remote and core infarct SNR (7.5±2.8* vs. 13.2±3.4 and 2.9±1.6; *p<0.0001), and DEMRI BZ SNR tended to be intermediate to remote and core infarct (8.4±5.4 vs. 3.3±0.6 and 14.3±6.6; p>0.05). TEM analysis exhibited preserved cell structure in BZ cardiomyocytes despite transmural DEMRI enhancement. Conclusions Dual-contrast MEMRI-DEMRI detects BZ viability within DEMRI infarct zones. This approach may identify injured, at-risk myocardium in ischemic cardiomyopathy. PMID:21719779

Dash, Rajesh; Chung, Jaehoon; Ikeno, Fumiaki; Hahn-Windgassen, Annett; Matsuura, Yuka; Bennett, Mihoko V.; Lyons, Jennifer K.; Teramoto, Tomohiko; Robbins, Robert C.; McConnell, Michael V.; Yeung, Alan C.; Brinton, Todd J.; Harnish, Phillip P.; Yang, Phillip C.

2011-01-01

137

Automated scoring of regional lung perfusion in children from contrast enhanced 3D MRI  

NASA Astrophysics Data System (ADS)

MRI perfusion images give information about regional lung function and can be used to detect pulmonary pathologies in cystic fibrosis (CF) children. However, manual assessment of the percentage of pathologic tissue in defined lung subvolumes features large inter- and intra-observer variation, making it difficult to determine disease progression consistently. We present an automated method to calculate a regional score for this purpose. First, lungs are located based on thresholding and morphological operations. Second, statistical shape models of left and right children's lungs are initialized at the determined locations and used to precisely segment morphological images. Segmentation results are transferred to perfusion maps and employed as masks to calculate perfusion statistics. An automated threshold to determine pathologic tissue is calculated and used to determine accurate regional scores. We evaluated the method on 10 MRI images and achieved an average surface distance of less than 1.5 mm compared to manual reference segmentations. Pathologic tissue was detected correctly in 9 cases. The approach seems suitable for detecting early signs of CF and monitoring response to therapy.

Heimann, Tobias; Eichinger, Monika; Bauman, Grzegorz; Bischoff, Arved; Puderbach, Michael; Meinzer, Hans-Peter

2012-03-01

138

Automated in vivo segmentation of carotid plaque MRI with Morphology-Enhanced probability maps.  

PubMed

MRI is a promising noninvasive technique for characterizing atherosclerotic plaque composition in vivo, with an end-goal of assessing plaque vulnerability. Because of limitations arising from acquisition time, achievable resolution, contrast-to-noise ratio, patient motion, and the effects of blood flow, automatically identifying plaque composition remains a challenging task in vivo. In this article, a segmentation method using maximum a posteriori probability Bayesian theory is presented that divides axial, multi-contrast-weighted images into regions of necrotic core, calcification, loose matrix, and fibrous tissue. Key advantages of the method are that it utilizes morphologic information, such as local wall thickness, and coupled active contours to limit the impact from noise and artifacts associated with in vivo imaging. In experiments involving 142 sets of multi-contrast images from 26 subjects undergoing carotid endarterectomy, segmented areas of each of these tissues per slice agreed with histologically confirmed areas with correlations (R(2)) of 0.78, 0.83, 0.41, and 0.82, respectively. In comparison, manually identifying areas blinded to histology yielded correlations of 0.71, 0.76, 0.33, and 0.78, respectively. These results show that in vivo automatic segmentation of carotid MRI is feasible and comparable to or possibly more accurate than manual review for quantifying plaque composition. PMID:16470594

Liu, Fei; Xu, Dongxiang; Ferguson, Marina S; Chu, Baocheng; Saam, Tobias; Takaya, Norihide; Hatsukami, Thomas S; Yuan, Chun; Kerwin, William S

2006-03-01

139

In vivo evaluation of retinal and callosal projections in early postnatal development and plasticity using manganese-enhanced MRI and diffusion tensor imaging  

Microsoft Academic Search

The rodents are an excellent model for understanding the development and plasticity of the visual system. In this study, we explored the feasibility of Mn-enhanced MRI (MEMRI) and diffusion tensor imaging (DTI) at 7T for in vivo and longitudinal assessments of the retinal and callosal pathways in normal neonatal rodent brains and after early postnatal visual impairments. Along the retinal

Kevin C. Chan; Joe S. Cheng; Shujuan Fan; Iris Y. Zhou; Jian Yang; Ed X. Wu

140

Joint estimation of shape and deformation for the detection of lesions in dynamic contrast-enhanced breast MRI  

NASA Astrophysics Data System (ADS)

We propose a mathematical framework for simultaneously delineating the boundary of object and estimating its temporal motion in the application of lesion detection in a dynamic contrast-enhanced (DCE) breast MRI sequence where both the appearance and the shape of region of interest is assumed to change in time. A unified energy functional for a joint segmentation and registration is proposed based on the assumption that the statistical properties of dynamic intensity curves within a region of interest are homogeneous. Our algorithm is designed to provide the morphological properties of the enhanced region and its dynamic intensity profiles, called kinetic signatures, in the analysis of DCE imagery since these features are considered as significant cues in understanding images. The proposed energy comprises a combination of a segmentation energy and a registration energy. The segmentation energy is developed based on a convex formulation being insensitive to the initialization. The registration energy is designed to compensate motion artifacts that are usually involved in the temporal imaging procedure. The major objective of this work is to provide a mathematical framework for a joint segmentation and registration on a dynamic sequence of images, and we demonstrate the mutual benefit of the estimation of temporal deformations for the registration step and the localization of regions of interest for the segmentation step. The effectiveness of the developed algorithm has been demonstrated on a number of clinical DCE breast MRI data in the application of breast lesion detection and the results show its potential to improve the accuracy and the efficiency in the diagnosis of breast cancer.

Hong, Byung-Woo

2013-11-01

141

Hepatocellular Adenoma: Evaluation with Contrast-Enhanced Ultrasound and MRI and Correlation with Pathologic and Phenotypic Classification in 26 Lesions  

PubMed Central

Purpose. To review the contrast-enhanced ultrasonographic (CEUS) and magnetic resonance (MR) imaging findings in 25 patients with 26 hepatocellular adenomas (HCAs) and to compare imaging features with histopathologic results from resected specimen considering the new immunophenotypical classification. Material and Methods. Two abdominal radiologists reviewed retrospectively CEUS cineloops and MR images in 26 HCA. All pathological specimens were reviewed and classified into four subgroups (steatotic or HNF 1? mutated, inflammatory, atypical or ?-catenin mutated, and unspecified). Inflammatory infiltrates were scored, steatosis, and telangiectasia semiquantitatively evaluated. Results. CEUS and MRI features are well correlated: among the 16 inflammatory HCA, 7/16 presented typical imaging features: hypersignal T2, strong arterial enhancement with a centripetal filling, persistent on delayed phase. 6 HCA were classified as steatotic with typical imaging features: a drop out signal, slight arterial enhancement, vanishing on late phase. Four HCA were classified as atypical with an HCC developed in one. Five lesions displayed important steatosis (>50%) without belonging to the HNF1? group. Conclusion. In half cases, inflammatory HCA have specific imaging features well correlated with the amount of telangiectasia and inflammatory infiltrates. An HCA with important amount of steatosis noticed on chemical shift images does not always belong to the HNF1? group. PMID:22811588

Manichon, Anne-Frédérique; Bancel, Brigitte; Durieux-Millon, Marion; Ducerf, Christian; Mabrut, Jean-Yves; Lepogam, Marie-Annick; Rode, Agnès

2012-01-01

142

Optimal k-space sampling for dynamic contrast-enhanced MRI with an application to MR renography.  

PubMed

For time-resolved acquisitions with k-space undersampling, a simulation method was developed for selecting imaging parameters based on minimization of errors in signal intensity versus time and physiologic parameters derived from tracer kinetic analysis. Optimization was performed for time-resolved angiography with stochastic trajectories (TWIST) algorithm applied to contrast-enhanced MR renography. A realistic 4D phantom comprised of aorta and two kidneys, one healthy and one diseased, was created with ideal tissue time-enhancement pattern generated using a three-compartment model with fixed parameters, including glomerular filtration rate (GFR) and renal plasma flow (RPF). TWIST acquisitions with different combinations of sampled central and peripheral k-space portions were applied to this phantom. Acquisition performance was assessed by the difference between simulated signal intensity (SI) and calculated GFR and RPF and their ideal values. Sampling of the 20% of the center and 1/5 of the periphery of k-space in phase-encoding plane and data-sharing of the remaining 4/5 minimized the errors in SI (<5%), RPF, and GFR (both <10% for both healthy and diseased kidneys). High-quality dynamic human images were acquired with optimal TWIST parameters and 2.4 sec temporal resolution. The proposed method can be generalized to other dynamic contrast-enhanced MRI applications, e.g., MR angiography or cancer imaging. PMID:19230014

Song, Ting; Laine, Andrew F; Chen, Qun; Rusinek, Henry; Bokacheva, Louisa; Lim, Ruth P; Laub, Gerhard; Kroeker, Randall; Lee, Vivian S

2009-05-01

143

Hydrothermally synthesized PEGylated calcium phosphate nanoparticles incorporating Gd-DTPA for contrast enhanced MRI diagnosis of solid tumors.  

PubMed

Organic-inorganic hybrid nanoparticles with calcium phosphate (CaP) core and PEGylated shell were developed to incorporate magnetic resonance imaging (MRI) contrast agent diethylenetriaminepentaacetic acid gadolinium (III) (Gd-DTPA) for noninvasive diagnosis of solid tumors. A two-step preparation method was applied to elaborate hybrid nanoparticles with a z-average hydrodynamic diameter about 80nm, neutral surface ?-potential and high colloidal stability in physiological environments by self-assembly of poly(ethylene glycol)-b-poly(aspartic acid) block copolymer, Gd-DTPA, and CaP in aqueous solution, followed with hydrothermal treatment. Incorporation into the hybrid nanoparticles allowed Gd-DTPA to show significant enhanced retention ratio in blood circulation, leading to high accumulation in tumor positions due to enhanced permeability and retention (EPR) effect. Moreover, Gd-DTPA revealed above 6 times increase of relaxivity in the nanoparticle system compared to free form, and eventually, selective and elevated contrast enhancements in the tumor positions were observed. These results indicate the high potential of Gd-DTPA-loaded PEGylated CaP nanoparticles as a novel contrast agent for noninvasive cancer diagnosis. PMID:24211705

Mi, Peng; Kokuryo, Daisuke; Cabral, Horacio; Kumagai, Michiaki; Nomoto, Takahiro; Aoki, Ichio; Terada, Yasuko; Kishimura, Akihiro; Nishiyama, Nobuhiro; Kataoka, Kazunori

2014-01-28

144

Response of the Primary Auditory and Non-Auditory Cortices to Acoustic Stimulation: A Manganese-Enhanced MRI Study  

PubMed Central

Structural and functional features of various cerebral cortices have been extensively explored in neuroscience research. We used manganese-enhanced MRI, a non-invasive method for examining stimulus-dependent activity in the whole brain, to investigate the activity in the layers of primary cortices and sensory, such as auditory and olfactory, pathways under acoustic stimulation. Male Sprague-Dawley rats, either with or without exposure to auditory stimulation, were scanned before and 24–29 hour after systemic MnCl2 injection. Cortex linearization and layer-dependent signal extraction were subsequently performed for detecting layer-specific cortical activity. We found stimulus-dependent activity in the deep layers of the primary auditory cortex and the auditory pathways. The primary sensory and visual cortices also showed the enhanced activity, whereas the olfactory pathways did not. Further, we performed correlation analysis of the signal intensity ratios among different layers of each cortex, and compared the strength of correlations between with and without the auditory stimulation. In the primary auditory cortex, the correlation strength between left and right hemisphere showed a slight but not significant increase with the acoustic simulation, whereas, in the primary sensory and visual cortex, the correlation coefficients were significantly smaller. These results suggest the possibility that even though the primary auditory, sensory, and visual cortices showed enhanced activity to the auditory stimulation, these cortices had different associations for auditory processing in the brain network. PMID:24618696

Kim, Young R.; Song, Youngkyu; Chun, Song-I; Suh, Ji-Yeon; Kim, Jeong Kon; Ryu, Yeon-Hee; Choi, Sun-Mi; Cho, Hyungjoon; Cho, Gyunggoo

2014-01-01

145

Enhanced brain connectivity in math-gifted adolescents: An fMRI study using mental rotation  

Microsoft Academic Search

Mathematical giftedness is a form of intelligence related to enhanced mathematical reasoning that can be tested using a variety of numerical and spatial tasks. A number of neurobiological mechanisms related to exceptional mathematical reasoning ability have been postulated, including enhanced brain connectivity. We aimed to further investigate this possibility by comparing a group of mathematically gifted adolescents with an average

James Prescott; Maria Gavrilescu; Ross Cunnington; Michael W. OBoyle; Gary F. Egan

2010-01-01

146

Variable Delay Multi-Pulse Train for Fast Chemical Exchange Saturation Transfer and Relayed-Nuclear Overhauser Enhancement MRI  

PubMed Central

Purpose Chemical exchange saturation transfer (CEST) imaging is a new MRI technology allowing the detection of low concentration endogenous cellular proteins and metabolites indirectly through their exchangeable protons. A new technique, variable delay multi-pulse CEST (VDMP-CEST), is proposed to eliminate the need for recording full Z-spectra and performing asymmetry analysis to obtain CEST contrast. Methods The VDMP-CEST scheme involves acquiring images with two (or more) delays between radiofrequency saturation pulses in pulsed CEST, producing a series of CEST images sensitive to the speed of saturation transfer. Subtracting two images or fitting a time series produces CEST and relayed-nuclear Overhauser enhancement CEST maps without effects of direct water saturation and, when using low radiofrequency power, minimal magnetization transfer contrast interference. Results When applied to several model systems (bovine serum albumin, crosslinked bovine serum albumin, l-glutamic acid) and in vivo on healthy rat brain, VDMP-CEST showed sensitivity to slow to intermediate range magnetization transfer processes (rate < 100–150 Hz), such as amide proton transfer and relayed nuclear Overhauser enhancement-CEST. Images for these contrasts could be acquired in short scan times by using a single radiofrequency frequency. Conclusions VDMP-CEST provides an approach to detect CEST effect by sensitizing saturation experiments to slower exchange processes without interference of direct water saturation and without need to acquire Z-spectra and perform asymmetry analysis. PMID:23813483

Xu, Jiadi; Yadav, Nirbhay N.; Bar-Shir, Amnon; Jones, Craig K.; Chan, Kannie W. Y.; Zhang, Jiangyang; Walczak, P.; McMahon, Michael T.; van Zijl, Peter C. M.

2013-01-01

147

In vivo mn-enhanced MRI for early tumor detection and growth rate analysis in a mouse medulloblastoma model.  

PubMed

Mouse models have increased our understanding of the pathogenesis of medulloblastoma (MB), the most common malignant pediatric brain tumor that often forms in the cerebellum. A major goal of ongoing research is to better understand the early stages of tumorigenesis and to establish the genetic and environmental changes that underlie MB initiation and growth. However, studies of MB progression in mouse models are difficult due to the heterogeneity of tumor onset times and growth patterns and the lack of clinical symptoms at early stages. Magnetic resonance imaging (MRI) is critical for noninvasive, longitudinal, three-dimensional (3D) brain tumor imaging in the clinic but is limited in resolution and sensitivity for imaging early MBs in mice. In this study, high-resolution (100 ?m in 2 hours) and high-throughput (150 ?m in 15 minutes) manganese-enhanced MRI (MEMRI) protocols were optimized for early detection and monitoring of MBs in a Patched-1 (Ptch1) conditional knockout (CKO) model. The high tissue contrast obtained with MEMRI revealed detailed cerebellar morphology and enabled detection of MBs over a wide range of stages including pretumoral lesions as early as 2 to 3 weeks postnatal with volumes close to 0.1 mm(3). Furthermore, longitudinal MEMRI allowed noninvasive monitoring of tumors and demonstrated that lesions within and between individuals have different tumorigenic potentials. 3D volumetric studies allowed quantitative analysis of MB tumor morphology and growth rates in individual Ptch1-CKO mice. These results show that MEMRI provides a powerful method for early in vivo detection and longitudinal imaging of MB progression in the mouse brain. PMID:25499213

Suero-Abreu, Giselle A; Praveen Raju, G; Aristizábal, Orlando; Volkova, Eugenia; Wojcinski, Alexandre; Houston, Edward J; Pham, Diane; Szulc, Kamila U; Colon, Daniel; Joyner, Alexandra L; Turnbull, Daniel H

2014-12-01

148

In Vivo Mn-Enhanced MRI for Early Tumor Detection and Growth Rate Analysis in a Mouse Medulloblastoma Model12  

PubMed Central

Mouse models have increased our understanding of the pathogenesis of medulloblastoma (MB), the most common malignant pediatric brain tumor that often forms in the cerebellum. A major goal of ongoing research is to better understand the early stages of tumorigenesis and to establish the genetic and environmental changes that underlie MB initiation and growth. However, studies of MB progression in mouse models are difficult due to the heterogeneity of tumor onset times and growth patterns and the lack of clinical symptoms at early stages. Magnetic resonance imaging (MRI) is critical for noninvasive, longitudinal, three-dimensional (3D) brain tumor imaging in the clinic but is limited in resolution and sensitivity for imaging early MBs in mice. In this study, high-resolution (100 ?m in 2 hours) and high-throughput (150 ?m in 15 minutes) manganese-enhanced MRI (MEMRI) protocols were optimized for early detection and monitoring of MBs in a Patched-1 (Ptch1) conditional knockout (CKO) model. The high tissue contrast obtained with MEMRI revealed detailed cerebellar morphology and enabled detection of MBs over a wide range of stages including pretumoral lesions as early as 2 to 3 weeks postnatal with volumes close to 0.1 mm3. Furthermore, longitudinal MEMRI allowed noninvasive monitoring of tumors and demonstrated that lesions within and between individuals have different tumorigenic potentials. 3D volumetric studies allowed quantitative analysis of MB tumor morphology and growth rates in individual Ptch1-CKO mice. These results show that MEMRI provides a powerful method for early in vivo detection and longitudinal imaging of MB progression in the mouse brain. PMID:25499213

Suero-Abreu, Giselle A.; Praveen Raju, G.; Aristizábal, Orlando; Volkova, Eugenia; Wojcinski, Alexandre; Houston, Edward J.; Pham, Diane; Szulc, Kamila U.; Colon, Daniel; Joyner, Alexandra L.; Turnbull, Daniel H.

2014-01-01

149

Molecular imaging of tumors and metastases using chemical exchange saturation transfer (CEST) MRI  

NASA Astrophysics Data System (ADS)

The two glucose analogs 2-deoxy-D-glucose (2-DG) and 2-fluoro-2-deoxy-D-glucose (FDG) are preferentially taken up by cancer cells, undergo phosphorylation and accumulate in the cells. Owing to their exchangeable protons on their hydroxyl residues they exhibit significant chemical exchange saturation transfer (CEST) effect in MRI. Here we report CEST-MRI on mice bearing orthotopic mammary tumors injected with 2-DG or FDG. The tumor exhibited an enhanced CEST effect of up to 30% that persisted for over one hour. Thus 2-DG/FDG CEST MRI can replace PET/CT or PET/MRI for cancer research in laboratory animals, but also has the potential to be used in the clinic for the detection of tumors and metastases, distinguishing between malignant and benign tumors and monitoring tumor response to therapy as well as tumors metabolism noninvasively by using MRI, without the need for radio-labeled isotopes.

Rivlin, Michal; Horev, Judith; Tsarfaty, Ilan; Navon, Gil

2013-10-01

150

Focal lesions in the cirrhotic liver: their pivotal role in gadoxetic acid-enhanced MRI and recognition by the Western guidelines.  

PubMed

Hepatocellular carcinoma (HCC) is a major health concern, and early HCC diagnosis is a primary radiological concern. The goal of imaging liver cirrhosis is the early identification of high-grade dysplastic nodules/early HCC since their treatment is associated with a higher chance of radical cure and lower recurrence rates. The newly introduced MRI contrast agent gadoxetic acid (gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid, Gd-EOB-DTPA) has enabled the concurrent assessment of tumor vascularity and hepatocyte-specific contrast enhancement during the hepatobiliary phase (HBP), which can help to detect and characterize smaller HCCs and their precursors. HBP-EOB-MRI identifies hypovascular HCC nodules that are difficult to detect using ultrasonography or computed tomography, which do not show the diagnostic HCC hallmarks of arterial washin and portal/delayed washout. During the HBP, typical HCC and early HCC appear hypointense on EOB-MRI, whereas low-grade dysplastic or regenerative nodules appear as iso- or hyperintense lesions. The diagnostic accuracy of EOB-MRI for the diagnosis of early HCC is approximately 95-100%. One third of hypovascular hypointense nodules in HBP become hypervascular 'progressed' HCC, with a 1- and 3-year cumulative incidence of 25 and 41%, respectively. Therefore, these hypovascular nodules should be strictly followed up or definitely treated as typical HCC. Due to this capability of identifying the precursors and biological behavior of HCC, EOB-MRI has rapidly become a key imaging tool for the diagnosis of HCC and its precursors, despite the scarce MRI availability throughout Europe. With increasing experience, EOB-MRI may eventually be established as the diagnostic imaging modality of choice in this setting. Full recognition by the Western EASL-AASLD guidelines is expected. PMID:25376286

Golfieri, Rita; Garzillo, Giorgio; Ascanio, Salvatore; Renzulli, Matteo

2014-01-01

151

Noninvasive Topical Loading for Manganese-Enhanced MRI of the Mouse Visual System  

PubMed Central

Purpose. To evaluate topical loading as an alternative to intravitreal injection for Mn2+-enhanced magnetic resonance imaging (MEMRI) of the visual system. Methods. Topical administration of 0.5 to 1.5 M MnCl2 and intravitreal injections with 0.5 ?L 100 mM and 2 ?L 1 M MnCl2 for mouse MEMRI were conducted, followed by immunohistochemistry. In another mouse group, two topical administrations of 1 M Mn2+ were applied to the same animals 7 days apart, to evaluate the use of MEMRI in a time course study. Dynamic imaging was also conducted to reveal how Mn2+ travels to the retina. MEMRI with topically loaded MnCl2 was also conducted in eyes with retinal ischemia, to evaluate whether the enhancements required healthy neurons. Results. After 1 day, topical administration of 1 M and 1.5 M MnCl2 rendered significant signal enhancement (up to 20%) in the superior colliculus (P < 0.05) that was equivalent to that of the 2-?L 1 M injection. Repeated exposure to Mn2+ showed reproduced enhancement. Dynamic imaging showed significant enhancement in the iris, retina, and lens boundary, but not in the vitreous space. In retinal ischemic eyes, no enhancement of MEMRI was detected in the optic nerves. The immunohistochemistry of the optic nerve (1.5 mm anterior to the chiasm) and retina showed no injury 1 week after Mn2+ topical administrations to each mouse. Conclusions. The results demonstrated the feasibility of using topical administration of Mn2+ for MEMRI. Topically loaded Mn2+ did not diffuse into the vitreous space, but was it may have been absorbed into the iris to diffuse or travel via the capillary circulation to reach the retina. PMID:21421878

Campbell, Bruce; Lunderville, Chantal; Won, Eric; Liang, Hsiao-Fang

2011-01-01

152

Quantitative measurement of changes in calcium channel activity in vivo utilizing dynamic manganese-enhanced MRI (dMEMRI).  

PubMed

The ability of manganese ions (Mn(2+)) to enter cells through calcium ion (Ca(2+)) channels has been used for depolarization dependent brain functional imaging with manganese-enhanced MRI (MEMRI). The purpose of this study was to quantify changes to Mn(2+) uptake in rat brain using a dynamic manganese-enhanced MRI (dMEMRI) scanning protocol with the Patlak and Logan graphical analysis methods. The graphical analysis was based on a three-compartment model describing the tissue and plasma concentration of Mn. Mn(2+) uptake was characterized by the total distribution volume of manganese (Mn) inside tissue (V(T)) and the unidirectional influx constant of Mn(2+) from plasma to tissue (K(i)). The measurements were performed on the anterior (APit) and posterior (PPit) parts of the pituitary gland, a region with an incomplete blood brain barrier. Modulation of Ca(2+) channel activity was performed by administration of the stimulant glutamate and the inhibitor verapamil. It was found that the APit and PPit showed different Mn(2+) uptake characteristics. While the influx of Mn(2+) into the PPit was reversible, Mn(2+) was found to be irreversibly trapped in the APit during the course of the experiment. In the PPit, an increase of Mn(2+) uptake led to an increase in V(T) (from 2.8±0.3 ml/cm(3) to 4.6±1.2 ml/cm(3)) while a decrease of Mn(2+) uptake corresponded to a decrease in V(T) (from 2.8±0.3 ml/cm(3) to 1.4±0.3 ml/cm(3)). In the APit, an increase of Mn(2+) uptake led to an increase in K(i) (from 0.034±0.009 min(-1) to 0.049±0.012 min(-1)) while a decrease of Mn(2+) uptake corresponded to a decrease in K(i) (from 0.034±0.009 min(-1) to 0.019±0.003 min(-1)). This work demonstrates that graphical analysis applied to dMEMRI data can quantitatively measure changes to Mn(2+) uptake following modulation of neural activity. PMID:22227885

Leuze, Christoph; Kimura, Yuichi; Kershaw, Jeff; Shibata, Sayaka; Saga, Tsuneo; Chuang, Kai-Hsiang; Shimoyama, Ichiro; Aoki, Ichio

2012-03-01

153

Combined Respiratory and Cardiac Triggering Improves Blood Pool Contrast Agent Enhanced Pediatric Cardiovascular MRI  

PubMed Central

Background Contrast-enhanced cardiac MRA suffers from cardiac motion artifacts and often requires a breath-hold. Objective This work develops and evaluates a blood pool contrast agent enhanced combined respiratory and ECG triggered MRA method. Materials and methods An SPGR sequence was modified to enable combined cardiac and respiratory triggering on a 1.5T scanner. 23 consecutive patients referred for pediatric heart disease receiving gadofosveset were recruited in HIPAA-compliant fashion with IRB approval and informed consent/assent. Patients underwent standard, non-triggered contrast-enhanced MRA with or without suspended respiration. Additionally, a free-breathing triggered MRA was acquired. Triggered and non-triggered studies were presented in blinded random order independently to two radiologists twice. Anatomic structure delineation was graded for each triggered and non-triggered acquisition and the visual quality on triggered MRA was compared directly to non-triggered MRA. Results Triggered images received higher scores from each radiologist for all anatomic structures on each of the two reading sessions (Wilcoxon rank-sum test, p< 0.05). In direct comparison, triggered images were preferred over non-triggered images for delineating cardiac structures, with most comparisons reaching statistical significance (binomial test, p<0.05). Conclusion Combined cardiac and respiratory triggering, enabled by a blood-pool contrast agent, improves delineation of most anatomic structures in pediatric cardiovascular MRA. PMID:21786125

Vasanawala, Shreyas S.; Chan, Frandics P.; Newman, Beverley; Alley, Marcus T.

2013-01-01

154

Dynamic Contrast-Enhanced and Diffusion MRI Show Rapid and Dramatic Changes in Tumor Microenvironment in Response to Inhibition of HIF-1? Using PX478  

Microsoft Academic Search

PX-478 is a new agent known to inhibit the hypoxia- responsivetranscriptionfactor,HIF-1A,inexperimental tumors. The current study was undertaken in prepa- ration for clinical trials to determine which noninvasive imaging endpoint(s) is sensitive to this drug's actions. Dynamic contrast-enhanced (DCE) and diffusion- weighted (DW) magnetic resonance imaging (MRI) were used to monitor acute effects on tumor hemo- dynamics and cellularity, respectively. Mice

Bénédicte F. Jordan; Matthew Runquist; Natarajan Raghunand; Amanda Baker; Ryan Williams; Lynn Kirkpatrickb; Garth Powis; Robert J. Gillies

2005-01-01

155

Functional MRI in Prostate Cancer Detection  

PubMed Central

Multiparametric magnetic resonance imaging (MP-MRI) has emerged as a promising method for the detection of prostate cancer. The functional MRI components of the MP-MRI consist of the diffusion weighted MRI, dynamic contrast enhanced MRI, and magnetic resonance spectroscopic imaging. The purpose of this paper is to review the existing literature about the use of functional MRI in prostate cancer detection. PMID:25215284

Choyke, Peter L.

2014-01-01

156

Evaluation of Image Registration in Subtracted 3D Dynamic Contrast-Enhanced MRI of Treated Hepatocellular Carcinoma.  

PubMed

OBJECTIVE. The objective of our study was to quantify hepatic displacement between breath-holds in multiphasic contrast-enhanced MRI and assess the value of a 3D registration algorithm for displacement correction on subtracted images. MATERIALS AND METHODS. For this retrospective analysis, we evaluated MR images of 25 cirrhotic patients with treated hepatocellular carcinoma (HCC) and at least one coexisting small hepatic cyst that was hypointense on T1-weighted imaging. With the use of an automated 3D deformable registration algorithm, registered base and subtraction images were created using portal venous phase images as the baseline images. The relative displacement of the cysts over the dynamic phases was used to estimate hepatic displacement before and after registration. The width of the subtraction band artifact, HCC lesion conspicuity, and overall subtraction artifact level (i.e., image quality of the entire volume) of the subtraction images were evaluated before and after registration on a 5-point scale (1 = nondiagnostic, 5 = excellent image quality) by two blinded radiologists. Hepatic displacement and subtraction band artifact results were analyzed using the paired Student t test, and the results for HCC lesion conspicuity and image quality of the volume results were analyzed using the Wilcoxon signed rank test. Interobserver agreement was assessed using kappa statistics. RESULTS. The average total cyst displacement on unenhanced, arterial, and delayed phase images was significantly reduced by registration from 4.0, 3.2, and 4.6 mm, respectively, on pre-registered images to 2.4, 1.6, and 1.3 mm on postregistered images (p < 0.01). The mean HCC lesion conspicuity grade improved from 3.4 before registration to 4.4 after registration (p < 0.01), and the mean grade for image quality of the volume improved from 3.3 before registration to 4.6 after registration (p < 0.01). The average width of the subtraction band artifact decreased from 5.3 mm before registration to 2.4 mm after registration, from 6.1 mm before registration to 2.6 mm after registration, and from 5.2 mm before registration to 2.8 mm after registration for the arterial, portal venous, and delayed phase subtractions, respectively (p < 0.01). CONCLUSION. Automated registration of the liver in multiphasic MRI examinations reduced interphasic hepatic displacement, improved the conspicuity of the treated HCC lesion, and improved the overall subtraction image quality. PMID:25615750

Sundarakumar, Dinesh K; Wilson, Gregory J; Osman, Sherif F; Zaidi, Sadaf F; Maki, Jeffrey H

2015-02-01

157

Ferucarbotran (Resovist): a new clinically approved RES-specific contrast agent for contrast-enhanced MRI of the liver: properties, clinical development, and applications.  

PubMed

Ferucarbotran (Resovist) is the second clinically approved superparamagnetic iron oxide developed for contrast-enhanced MRI of the liver. The purpose of this review is to provide an overview on the properties, clinical development, and application of ferucarbotran. Safety data obtained during clinical phases I-III revealed a total of 162 adverse events within 1053 patients, of which 75 were classified as possibly, probably, or definitely drug related. The majority of events occurred within the first 3 h (73 of 75) and was of mild intensity. The agent significantly improves the detection of hypovascular focal liver lesions with a comparable sensitivity in lesion detection to CTAP but without a relevant loss in specificity. Furthermore, ferucarbotran leads to a significant improvement of the sensitivity for lesion classification and characterization of the most frequent liver lesions. Contrast-enhanced MRA is not feasible and the angiographic effect is not sufficient to allow for postprocessing of data into maximum intensity projections. Intraindividual studies at low-field (0.2 T) and high-field (1.5 T) showed similar rates for lesion detection. The time window for contrast-enhanced MRI of the liver is at least 1 day up to 4 days. The compound can be regarded as safe and well tolerated. Even bolus injections caused no cardiovascular side effects, lumbar back pain, or clinically relevant laboratory changes. The examination time can be kept short with T1- and T2-weighted pre-contrast sequences, dynamic MRI over 10 min, and finally accumulation phase T2-weighted MRI. Patients who may benefit in particular are surgical candidates for resection, transplantation, or interventional therapies, and patients with liver cirrhosis and/or suspected hepatocellular carcinoma to either exclude malignancy or to define the extent of disease, the location of lesions, and the type of newly detected lesions. PMID:12764641

Reimer, Peter; Balzer, Thomas

2003-06-01

158

Self-Gated CINE MRI for Combined Contrast-Enhanced Imaging and Wall-Stiffness Measurements of Murine Aortic Atherosclerotic Lesions  

PubMed Central

Background High-resolution contrast-enhanced imaging of the murine atherosclerotic vessel wall is difficult due to unpredictable flow artifacts, motion of the thin artery wall and problems with flow suppression in the presence of a circulating contrast agent. Methods and Results We applied a 2D-FLASH retrospective-gated CINE MRI method at 9.4T to characterize atherosclerotic plaques and vessel wall distensibility in the aortic arch of aged ApoE?/? mice after injection of a contrast agent. The method enabled detection of contrast enhancement in atherosclerotic plaques in the aortic arch after I.V. injection of micelles and iron oxides resulting in reproducible plaque enhancement. Both contrast agents were taken up in the plaque, which was confirmed by histology. Additionally, the retrospective-gated CINE method provided images of the aortic wall throughout the cardiac cycle, from which the vessel wall distensibility could be calculated. Reduction in plaque size by statin treatment resulted in lower contrast enhancement and reduced wall stiffness. Conclusions The retrospective-gated CINE MRI provides a robust and simple way to detect and quantify contrast enhancement in atherosclerotic plaques in the aortic wall of ApoE?/? mice. From the same scan, plaque-related changes in stiffness of the aortic wall can be determined. In this mouse model, a correlation between vessel wall stiffness and atherosclerotic lesions was found. PMID:23472079

den Adel, Brigit; van der Graaf, Linda M.; Strijkers, Gustav J.; Lamb, Hildo J.; Poelmann, Robert E.; van der Weerd, Louise

2013-01-01

159

DW-MRI of the urogenital tract: applications in oncology  

PubMed Central

Abstract Diffusion-weighted magnetic resonance imaging (DW-MRI) appears to hold promise as a non-invasive imaging modality in the detection of early microstructural and functional changes of different organs. DW-MRI is an imaging technique with a high sensitivity for the detection of a large variety of diseases in the urogenital tract. In kidneys, DW-MRI has shown promise for the characterization of solid lesions. Also in focal T1 hyperintense lesions DW-MRI was able to differentiate hemorrhagic cysts from tumours according to the lower apparent diffusion coefficient (ADC) values reported for renal cell carcinomas. Promising results were also published for the detection of prostate cancer. DW-MRI applied in addition to conventional T2-weighted imaging has been found to improve tumour detection. On a 3 T magnetic resonance unit ADC values were reported to be lower for tumours compared with the normal-appearing peripheral zone. The combined approach of T2-weighted imaging and DW-MRI also showed promising results for the detection of recurrent tumour in patients after radiation therapy. DW-MRI may improve the performance of conventional T2-weighted and contrast-enhanced MRI in the preoperative work-up of bladder cancer, as it may help in distinguishing superficial from muscle invasive bladder cancer, which is critical for patient management. Another challenging application of DW-MRI in the urogenital tract is the detection of pelvic lymph node metastases. As the ADC is generally reduced in malignant tumours and increased under inflammatory conditions, reduced ADC values were expected in patients with lymph node metastases. PMID:20880781

Petralia, G.

2010-01-01

160

MRI-based Kidney Volume Measurements in ADPKD: Reliability and Effect of Gadolinium Enhancement  

PubMed Central

Background and objectives: To evaluate the inter- and intrareader reliability and the effect of gadolinium enhancement on kidney volume measurements obtained from pre- and postgadolinium T1 MR images in patients with autosomal dominant polycystic kidney disease (ADPKD). Design, setting, participants, & measurements: Twenty subjects were randomly selected with approximately equal frequency from three kidney-size groups. Pre- and postgadolinium 3D T1 (pre-T1, post-T1) MR images were obtained. The stereology method was applied to segment and measure kidney volumes. The measurement process was repeated at two-wk intervals by two radiologists. Reliability was assessed with correlation coefficients. Intra- and inter-reader bias and measure differences were assessed with paired T-tests. The size effect on the pre- and post-T1 measurements was evaluated with one-way ANOVA. Results: The intra- and inter-reader reliability was extremely high in all measurements. No systematic intrareader bias but a small inter-reader bias for the post-T1 measurements was observed. All kidney volumes measured on the pre- and post-T1 images were highly correlated with each other for both readers. The post-T1 volumes were significantly higher than pre-T1 volumes. While the post-pre volume differences were relatively constant across the three kidney-size groups, the post-pre percent volume differences were significantly smaller as the size of the kidney increased. Conclusions: Kidney volume measurements can be made with minimum intra- and inter-reader variability on both pre- and post-T1 MR images. Kidney volumes measured on the pre-T1 were smaller than those on post-T1, and percent differences between pre-T1 and post-T1 kidney volumes decreased with increasing kidney size. PMID:19339416

Bae, Kyongtae T.; Tao, Cheng; Zhu, Fang; Bost, James E.; Chapman, Arlene B.; Grantham, Jared J.; Torres, Vicente E.; Guay-Woodford, Lisa M.; Meyers, Catherine M.; Bennett, William M.

2009-01-01

161

Quantitative assessment of regional cerebral blood flow by dynamic susceptibility contrast-enhanced MRI, without the need for arterial blood signals  

NASA Astrophysics Data System (ADS)

In dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI), an arterial input function (AIF) is usually obtained from a time-concentration curve (TCC) of the cerebral artery. This study was aimed at developing an alternative technique for reconstructing AIF from TCCs of multiple brain regions. AIF was formulated by a multi-exponential function using four parameters, and the parameters were determined so that the AIF curves convolved with a model of tissue response reproduced the measured TCCs for 20 regions. Systematic simulations were performed to evaluate the effects of possible error sources. DSC-MRI and positron emission tomography (PET) studies were performed on 14 patients with major cerebral artery occlusion. Cerebral blood flow (CBF) images were calculated from DSC-MRI data, using our novel method alongside conventional AIF estimations, and compared with those from 15O-PET. Simulations showed that the calculated CBF values were sensitive to variations in the assumptions regarding cerebral blood volume. Nevertheless, AIFs were reasonably reconstructed for all patients. The difference in CBF values between DSC-MRI and PET was -2.2 ± 7.4 ml/100 g/min (r = 0.55, p < 0.01) for our method, versus -0.2 ± 8.2 ml/100 g/min (r = 0.47, p = 0.01) for the conventional method. The difference in the ratio of affected to unaffected hemispheres between DSC-MRI and PET was 0.07 ± 0.09 (r = 0.82, p < 0.01) for our method, versus 0.07 ± 0.09 (r = 0.83, p < 0.01) for the conventional method. The contrasts in CBF images from our method were the same as those from the conventional method. These findings suggest the feasibility of assessing CBF without arterial blood signals.

Enmi, Jun-ichiro; Kudomi, Nobuyuki; Hayashi, Takuya; Yamamoto, Akihide; Iguchi, Satoshi; Moriguchi, Tetsuaki; Hori, Yuki; Koshino, Kazuhiro; Zeniya, Tsutomu; Shah, Nadim Jon; Yamada, Naoaki; Iida, Hidehiro

2012-12-01

162

Gadoxetic Acid-Enhanced MRI and Sonoelastography: Non-Invasive Assessments of Chemoprevention of Liver Fibrosis in Thioacetamide-Induced Rats with Sho-Saiko-To  

PubMed Central

Background This study aimed to compare the performance of gadoxetic acid -enhanced magnetic resonance imaging (MRI) and sonoelastography in evaluating chemopreventive effects of Sho-Saiko-To (SST) in thioacetamide (TAA)-induced early liver fibrosis in rats. Materials and Methods Ten of Sprague-Dawley rats receiving TAA (200 mg/kg of body weight) intraperitoneal injection were divided into three groups: Group 1 (TAA only, n?=?3), Group 2 (TAA +0.25 g/kg SST, n?=?4) and Group 3 (TAA+1 g/kg SST, n?=?3). Core needle liver biopsy at week 2 and liver specimens after sacrifice at week 6 confirmed liver fibrosis using histological examinations, including Sirius red staining, Ishak and Metavir scoring systems. Gadoxetic acid-enhanced MRI and shear-wave sonoelastography were employed to evaluate liver fibrosis. The expression of hepatic transporter organic anion transporter 1 (Oatp1), multidrug-resistant protein 2 (Mrp2) and alpha-smooth muscle actin (?-Sma) were also analyzed in each group by immunohistochemistry (IHC) and Western blot. Results According to histological grading by Sirius red staining, Ishak scores of liver fibrosis in Groups 1, 2 and 3 were 3, 2 and 1, respectively. As shown in gadoxetic acid-enhanced MRI, the ratio of relative enhancement was significantly lower in Group 1 (1.87±0.21) than in Group 2 of low-dose (2.82±0.25) and Group 3 of high-dose (2.72±0.12) SST treatment at 10 minutes after gadoxetic acid intravenous injection (p<0.05). Sonoelastography showed that the mean difference before and after experiments in Groups 1, 2 and 3 were 4.66±0.1, 4.4±0.57 and 3±0.4 KPa (p<0.1), respectively. Chemopreventive effects of SST reduced the Mrp2 protein level (p<0.01) but not Oatp1 and ?-Sma levels. Conclusion Sonoelastography and gadoxetic acid-enhanced MRI could monitor the treatment effect of SST in an animal model of early hepatic fibrosis. PMID:25490034

Chen, Ya-Wen; Tsai, Meng-Yuan; Pan, Huay-Ben; Tseng, Hui-Hwa; Hung, Yu-Ting; Chou, Chen-Pin

2014-01-01

163

An investigation into the effects of temporal resolution on hepatic dynamic contrast-enhanced MRI in volunteers and in patients with hepatocellular carcinoma  

NASA Astrophysics Data System (ADS)

This study investigated the effect of temporal resolution on the dual-input pharmacokinetic (PK) modelling of dynamic contrast-enhanced MRI (DCE-MRI) data from normal volunteer livers and from patients with hepatocellular carcinoma. Eleven volunteers and five patients were examined at 3 T. Two sections, one optimized for the vascular input functions (VIF) and one for the tissue, were imaged within a single heart-beat (HB) using a saturation-recovery fast gradient echo sequence. The data was analysed using a dual-input single-compartment PK model. The VIFs and/or uptake curves were then temporally sub-sampled (at interval ?t = [2-20] s) before being subject to the same PK analysis. Statistical comparisons of tumour and normal tissue PK parameter values using a 5% significance level gave rise to the same study results when temporally sub-sampling the VIFs to HB < ?t <4 s. However, sub-sampling to ?t > 4 s did adversely affect the statistical comparisons. Temporal sub-sampling of just the liver/tumour tissue uptake curves at ?t ? 20 s, whilst using high temporal resolution VIFs, did not substantially affect PK parameter statistical comparisons. In conclusion, there is no practical advantage to be gained from acquiring very high temporal resolution hepatic DCE-MRI data. Instead the high temporal resolution could be usefully traded for increased spatial resolution or SNR.

Gill, Andrew B.; Black, Richard T.; Bowden, David J.; Priest, Andrew N.; Graves, Martin J.; Lomas, David J.

2014-06-01

164

Cerebral blood volume estimation by ferumoxytol-enhanced steady-state MRI at 9.4?T reveals microvascular impact of ?1 -adrenergic receptor antibodies.  

PubMed

Cerebrovascular abnormality is frequently accompanied by cognitive dysfunctions, such as dementia. Antibodies against the ?1 -adrenoceptor (?1 -AR) can be found in patients with Alzheimer's disease with cerebrovascular disease, and have been shown to affect the larger vessels of the brain in rodents. However, the impact of ?1 -AR antibodies on the cerebral vasculature remains unclear. In the present study, we established a neuroimaging method to measure the relative cerebral blood volume (rCBV) in small rodents with the ultimate goal to detect changes in blood vessel density and/or vessel size induced by ?1 -AR antibodies. For this purpose, mapping of R2 * and R2 was performed using MRI at 9.4?T, before and after the injection of intravascular iron oxide particles (ferumoxytol). The change in the transverse relaxation rates (?R2 *, ?R2 ) showed a significant rCBV decrease in the cerebrum, cortex and hippocampus of rats (except hippocampal ?R2 ), which was more pronounced for ?R2 * than for ?R2 . Immunohistological analyses confirmed that the ?1 -AR antibody induced blood vessel deficiencies. Our findings support the hypothesis that ?1 -AR antibodies lead to cerebral vessel damage throughout the brain, which can be monitored by MRI-derived rCBV, a non-invasive neuroimaging method. This demonstrates the value of rCBV estimation by ferumoxytol-enhanced MRI at 9.4?T, and further underlines the significance of this antibody in brain diseases involving vasculature impairments, such as dementia. PMID:25060359

Pohlmann, Andreas; Karczewski, Peter; Ku, Min-Chi; Dieringer, Babette; Waiczies, Helmar; Wisbrun, Natali; Kox, Stefanie; Palatnik, Irina; Reimann, Henning Matthias; Eichhorn, Christina; Waiczies, Sonia; Hempel, Petra; Lemke, Bernd; Niendorf, Thoralf; Bimmler, Marion

2014-09-01

165

Intratumor distribution and test-retest comparisons of physiological parameters quantified by dynamic contrast-enhanced MRI in rat U251 glioma.  

PubMed

The distribution of dynamic contrast-enhanced MRI (DCE-MRI) parametric estimates in a rat U251 glioma model was analyzed. Using Magnevist as contrast agent (CA), 17 nude rats implanted with U251 cerebral glioma were studied by DCE-MRI twice in a 24?h interval. A data-driven analysis selected one of three models to estimate either (1) plasma volume (vp), (2) vp and forward volume transfer constant (K(trans)) or (3) vp, K(trans) and interstitial volume fraction (ve), constituting Models 1, 2 and 3, respectively. CA distribution volume (VD) was estimated in Model 3 regions by Logan plots. Regions of interest (ROIs) were selected by model. In the Model 3 ROI, descriptors of parameter distributions--mean, median, variance and skewness--were calculated and compared between the two time points for repeatability. All distributions of parametric estimates in Model 3 ROIs were positively skewed. Test-retest differences between population summaries for any parameter were not significant (p???0.10; Wilcoxon signed-rank and paired t tests). These and similar measures of parametric distribution and test-retest variance from other tumor models can be used to inform the choice of biomarkers that best summarize tumor status and treatment effects. PMID:25125367

Aryal, Madhava P; Nagaraja, Tavarekere N; Brown, Stephen L; Lu, Mei; Bagher-Ebadian, Hassan; Ding, Guangliang; Panda, Swayamprava; Keenan, Kelly; Cabral, Glauber; Mikkelsen, Tom; Ewing, James R

2014-10-01

166

Optimized and combined T1 and B1 mapping technique for fast and accurate T1 quantification in contrast-enhanced abdominal MRI.  

PubMed

Fast T(1) mapping techniques are a valuable means of quantitatively assessing the distribution and dynamics of intravenously or orally applied paramagnetic contrast agents (CAs) by noninvasive imaging. In this study a fast T(1) mapping technique based on the variable flip angle (VFA) approach was optimized for accurate T(1) quantification in abdominal contrast-enhanced (CE) MRI. Optimization methods were developed to maximize the signal-to-noise ratio (SNR) and ensure effective RF and gradient spoiling, as well as a steady state, for a defined T(1) range of 100-800 ms and a limited acquisition time. We corrected B(1) field inhomogeneities by performing an additional measurement using an optimized fast B(1) mapping technique. High-precision in vitro and abdominal in vivo T(1) maps were successfully generated at a voxel size of 2.8 x 2.8 x 15 mm(3) and a temporal resolution of 2.3 s per T(1) map on 1.5T and 3T MRI systems. The application of the proposed fast T(1) mapping technique in abdominal CE-MRI enables noninvasive quantification of abdominal tissue perfusion and vascular permeability, and offers the possibility of quantitatively assessing dilution, distribution, and mixing processes of labeled solutions or drugs in the gastrointestinal tract. PMID:17326175

Treier, Reto; Steingoetter, Andreas; Fried, Michael; Schwizer, Werner; Boesiger, Peter

2007-03-01

167

Dynamic contrast enhanced MRI as a predictor of vascular-targeted photodynamic focal ablation therapy outcome in prostate cancer post-failed external beam radiation therapy  

PubMed Central

Introduction: Photodynamic therapy (PDT) can be employed as a focal therapy for prostate cancer. Dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) can potentially help identify tumour recurrence after failed external-beam radiotherapy (EBRT). The purpose of this study was to determine the ability of DCE-MRI to predict early response to PDT salvage treatment. Methods: Patients with post-EBRT prostate cancer recurrence were prospectively enrolled into a Phase I/II trial of PDT using WST09. A 15-patient subgroup of this cohort undergoing 1.5T DCE-MRI at baseline and 1-week post-PDT was retrospectively analyzed. The reference standard was prostate biopsy obtained 6 months post-PDT. Analysis was performed on a patient-by-patient basis, by prostate gland halves, and by prostate sextants. Results: Biopsy 6 months post-PDT identified cancer in 10/15 patients (66.7%), and in 24/90 sextants (26.7%). Residual cancer was identified in 22/37 sextants (59.5%) identified as being involved at baseline. DCE-MRI at 1 week correctly predicted recurrent disease with a sensitivity of 100% (10/10), specificity of 60% (3/5), positive predictive value of 83.3% (10/12), negative predictive value of 100% (3/3), and an overall accuracy of 86.7%, (13/15). When analysis was performed on prostate halves, the sensitivity and negative predictive value remained at 100%, with an improvement in specificity to 88.2% (15/17). The overall accuracy of DCE-MRI was similar regardless of analysis method: 86.7% on a patient-by-patient basis, 86.7% by prostate half and 83.3% by sextant. Changes in prostate-specific antigen (PSA) did not correlate to response. Conclusion: DCE-MRI shows promise as a tool to predict successful outcome when performed 1 week post-PDT and could potentially be used to inform the need for re-treatment at an early time-point. PMID:25408811

Barrett, Tristan; Davidson, Sean R.H.; Wilson, Brian C.; Weersink, Robert A.; Trachtenberg, John; Haider, Masoom A.

2014-01-01

168

In vivo monitoring of sorafenib therapy effects on experimental prostate carcinomas using dynamic contrast-enhanced MRI and macromolecular contrast media  

PubMed Central

Abstract Purpose: To investigate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with macromolecular contrast media (MMCM) to monitor the effects of the multikinase inhibitor sorafenib on subcutaneous prostate carcinomas in rats with immunohistochemical validation. Materials and methods: Copenhagen rats, implanted with prostate carcinoma allografts, were randomized to the treatment group (n?=?8) or the control group (n?=?8). DCE-MRI with albumin-(Gd-DTPA)35 was performed at baseline and after 1 week using a clinical 3-Tesla system. The treatment group received sorafenib, 10?mg/kg body weight daily. Kinetic analysis yielded quantitative parameters of tumor endothelial permeability–surface area product (PS; ml/100?ml/min) and fractional blood volume (Vb, %). Tumors were harvested on day 7 for immunohistochemical analysis. Results: In sorafenib-treated tumors, PS (0.62?±?0.20 vs 0.08?±?0.09?ml/100?ml/min; P?MRI-assayed fractional blood volume Vb showed a highly significant correlation with tumor vascularity (RECA-1; r?=?0.87, P?MRI with MMCM demonstrated good, significant correlations with the immunohistochemically assessed antiangiogenic, antiproliferative, and proapoptotic effects of a 1-week, daily treatment course of sorafenib on experimental prostate carcinoma allografts. PMID:24380871

Schwarz, Bettina; Paprottka, Philipp M.; Sourbron, Steven; von Einem, Jobst C.; Dietrich, Olaf; Hinkel, Rabea; Clevert, Dirk A.; Bruns, Christiane J.; Reiser, Maximilian F.; Nikolaou, Konstantin; Wintersperger, Bernd J.

2013-01-01

169

Alertness in Young Healthy Subjects: An fMRI Study of Brain Region Interactivity Enhanced by a Warning Signal  

ERIC Educational Resources Information Center

An effective connectivity study was carried out on 16 young, healthy subjects performing an alertness task. The objective of this study was to develop and to evaluate a putative network model of alertness by adapting structural equation modeling to fMRI data. This study was designed to evaluate the directed interactivity of an attentional network…

Perin, B.; Godefroy, O.; Fall, S.; de Marco, G.

2010-01-01

170

Dynamic contrast-enhanced MRI-based biomarkers of therapeutic response in triple-negative breast cancer  

E-print Network

. Materials and methods 60 patients with triple- negative early-stage breast cancer receiving NAC were­MRI features can be used to predict whether triple-negative breast cancer patients will respond to NAC. Models receptors, and lacking overexpression of the HER2/neu onco- gene.1­3 Triple-negative breast cancer (TNBC

Rubin, Daniel L.

171

Statistical mapping of sound-evoked activity in the mouse auditory midbrain using Mn-enhanced MRI  

E-print Network

and unbiased analysis of brain function in the deep brain nuclei of mice. © 2007 Published by Elsevier Inc of neurobiology research on the genetic and molecular mechanisms underlying brain function, the mouse has become. These challenges led us to investigate alternative MRI methods for assessing brain function and neural activity

172

Protein composition alters in vivo resorption of PEG-based hydrogels as monitored by contrast-enhanced MRI.  

PubMed

We report on the use of magnetic resonance imaging (MRI)-based non-invasive monitoring to document the role of protein adjuvants in hydrogel implant integration in vivo. Polyethylene glycol (PEG) hydrogels were formed with different protein constituents, including albumin, fibrinogen and gelatin. The hydrogels were designed to exhibit similar material properties, including modulus, swelling and hydrolytic degradation kinetics. The in vivo resorption properties of these PEG-based hydrogels, which contained a tethered gadolinium contrast agent, were characterized by MRI and histology, and compared to their in vitro characteristics. MRI data revealed that PEG-Albumin implants remained completely intact throughout the experiments, PEG-Fibrinogen implants lost about 10% of their volume and PEG-Gelatin implants underwent prominent swelling and returned to their initial volume by day 25. Fully synthetic PEG-diacrylate (PEG-DA) control hydrogels lost about half of their volume after 25 days in vivo. Transverse MRI cross-sections of the implants revealed distinct mechanisms of the hydrogel's biodegradation: PEG-Fibrinogen and PEG-Albumin underwent surface erosion, whereas PEG-Gelatin and PEG-DA hydrogels mainly underwent bulk degradation. Histological findings substantiated the MRI data and demonstrated significant cellular response towards PEG-DA and PEG-Gelatin scaffolds with relatively low reaction towards PEG-Fibrinogen and PEG-Albumin hydrogels. These findings demonstrate that PEG-protein hydrogels can degrade via a different mechanism than PEG hydrogels, and that this difference can be linked to a reduced foreign body response. PMID:25542788

Berdichevski, Alexandra; Shachaf, Yonatan; Wechsler, Roni; Seliktar, Dror

2015-02-01

173

Breast MRI in Patients with Unilateral Bloody and Serous-Bloody Nipple Discharge: A Comparison with Galactography  

PubMed Central

Purpose. Assessing the role of breast MRI compared to galactography in patients with unilateral bloody or serous-bloody nipple discharge. Materials and Methods. Retrospective study including 53 unilateral discharge patients who performed galactography and MRI. We evaluated the capability of both techniques in identifying pathology and distinguishing between nonmalignant and malignant lesions. Lesions BIRADS 1/2 underwent follow-up, while the histological examination after surgery has been the gold standard to assess pathology in lesions BIRADS 3/4/5. The ROC analysis was used to test diagnostic MRI and galactography ability. Results. After surgery and follow-up, 8 patients had no disease (15%), 23 papilloma (43%), 11 papillomatosis (21%), 5 ductal cancer in situ (10%), and 6 papillary carcinoma (11%) diagnoses. Both techniques presented 100% specificity; MRI sensitivity was 98% versus 49% of galactography. Considering MRI, we found a statistical association between mass enhancement and papilloma (P < 0.001; AUC 0.957; CI 0.888–1.025), ductal enhancement and papillomatosis (P < 0.001; AUC 0.790; CI 0.623–0.958), segmental enhancement and ductal cancer in situ (P = 0.007; AUC 0.750; CI 0.429–1.071), and linear enhancement and papillary cancer (P = 0.011). Conclusions. MRI is a valid tool to detect ductal pathologies in patients with suspicious bloody or serous-bloody discharge showing higher sensitivity and specificity compared to galactography.

Manganaro, Lucia; D'Ambrosio, Ilaria; Gigli, Silvia; Di Pastena, Francesca; Tardioli, Stefano; Framarino, Marialuisa; Ballesio, Laura

2015-01-01

174

Facile non-hydrothermal synthesis of oligosaccharides coated sub-5 nm magnetic iron oxide nanoparticles with dual MRI contrast enhancement effect  

PubMed Central

Ultrafine sub-5 nm magnetic iron oxide nanoparticles coated with oligosaccharides (SIO) with dual T1-T2 weighted contrast enhancing effect and fast clearance has been developed as magnetic resonance imaging (MRI) contrast agent. Excellent water solubility, biocompatibility and high stability of such sub-5 nm SIO nanoparticles were achieved by using the “in-situ polymerization” coating method, which enables glucose forming oligosaccharides directly on the surface of hydrophobic iron oxide nanocrystals. Reported ultrafine SIO nanoparticles exhibit a longitudinal relaxivity (r1) of 4.1 mM?1s?1 and a r1/r2 ratio of 0.25 at 3 T (clinical field strength), rendering improved T1 or “brighter” contrast enhancement in T1-weighted MRI in addition to typical T2 or “darkening” contrast of conventional iron oxide nanoparticles. Such dual contrast effect can be demonstrated in liver imaging with T2 “darkening” contrast in the liver parenchyma but T1 “bright” contrast in the hepatic vasculature. More importantly, this new class of ultrafine sub-5 nm iron oxide nanoparticles showed much faster body clearance than those with larger sizes, promising better safety for clinical applications. PMID:25181490

Huang, Jing; Wang, Liya; Zhong, Xiaodong; Li, Yuancheng; Yang, Lily

2014-01-01

175

Posttraumatic pseudolipoma: MRI appearances.  

PubMed

The goal of this study was to describe the MRI characteristics of posttraumatic pseudolipomas. Ten patients with previous history of blunt trauma or local surgery were investigated with MRI at the level of their deformity. The etiology was blunt trauma in eight patients and postoperative trauma in two. For all patients medical documentation, in the form of clinical history and physical examination, confirmed that a visible hematoma was present acutely at the same location following the injury and that the contour deformity subsequently appeared. All patients underwent liposuction. Preoperative bilateral MRI examinations were performed on all patients. The mean clinical follow-up was 17.8 months. MRI examinations were interpreted in consensus by two experienced musculoskeletal radiologists with attention to fatty extension (subcutaneous fatty thickness and anatomical extension), asymmetry compared with the asymptomatic side, the presence or absence of fibrous septae or nonfatty components, and patterns of contrast enhancement. Ten posttraumatic pseudolipomas were identified. Clinically, they showed as subcutaneous masses with the consistency of normal adipose tissue. Their locations were the abdomen (n=1), hip (n=1), the upper thigh (n=6), the knee (n=1), and the ankle (n=1). On MRI examinations, using the contralateral side as a control, pseudolipomas appeared as focal fatty masses without a capsule or contrast enhancement. Posttraumatic pseudolipomas may develop at a site of blunt trauma or surgical procedures often antedated by a soft tissue hematoma. Characteristic MRI findings are unencapsulated subcutaneous fatty masses without contrast enhancement. PMID:15841381

Theumann, N; Abdelmoumene, A; Wintermark, M; Schnyder, P; Gailloud, M-C; Resnick, D

2005-09-01

176

Iterative approach of dual regression with a sparse prior enhances the performance of independent component analysis for group functional magnetic resonance imaging (fMRI) data.  

PubMed

This study proposes an iterative dual-regression (DR) approach with sparse prior regularization to better estimate an individual's neuronal activation using the results of an independent component analysis (ICA) method applied to a temporally concatenated group of functional magnetic resonance imaging (fMRI) data (i.e., Tc-GICA method). An ordinary DR approach estimates the spatial patterns (SPs) of neuronal activation and corresponding time courses (TCs) specific to each individual's fMRI data with two steps involving least-squares (LS) solutions. Our proposed approach employs iterative LS solutions to refine both the individual SPs and TCs with an additional a priori assumption of sparseness in the SPs (i.e., minimally overlapping SPs) based on L(1)-norm minimization. To quantitatively evaluate the performance of this approach, semi-artificial fMRI data were created from resting-state fMRI data with the following considerations: (1) an artificially designed spatial layout of neuronal activation patterns with varying overlap sizes across subjects and (2) a BOLD time series (TS) with variable parameters such as onset time, duration, and maximum BOLD levels. To systematically control the spatial layout variability of neuronal activation patterns across the "subjects" (n=12), the degree of spatial overlap across all subjects was varied from a minimum of 1 voxel (i.e., 0.5-voxel cubic radius) to a maximum of 81 voxels (i.e., 2.5-voxel radius) across the task-related SPs with a size of 100 voxels for both the block-based and event-related task paradigms. In addition, several levels of maximum percentage BOLD intensity (i.e., 0.5, 1.0, 2.0, and 3.0%) were used for each degree of spatial overlap size. From the results, the estimated individual SPs of neuronal activation obtained from the proposed iterative DR approach with a sparse prior showed an enhanced true positive rate and reduced false positive rate compared to the ordinary DR approach. The estimated TCs of the task-related SPs from our proposed approach showed greater temporal correlation coefficients with a reference hemodynamic response function than those of the ordinary DR approach. Moreover, the efficacy of the proposed DR approach was also successfully demonstrated by the results of real fMRI data acquired from left-/right-hand clenching tasks in both block-based and event-related task paradigms. PMID:22939873

Kim, Yong-Hwan; Kim, Junghoe; Lee, Jong-Hwan

2012-12-01

177

Accurate High-Resolution Measurements of 3-D Tissue Dynamics With Registration-Enhanced Displacement Encoded MRI  

PubMed Central

Displacement fields are important to analyze deformation, which is associated with functional and material tissue properties often used as indicators of health. Magnetic resonance imaging (MRI) techniques like DENSE and image registration methods like Hyperelastic Warping have been used to produce pixel-level deformation fields that are desirable in high-resolution analysis. However, DENSE can be complicated by challenges associated with image phase unwrapping, in particular offset determination. On the other hand, Hyperelastic Warping can be hampered by low local image contrast. The current work proposes a novel approach for measuring tissue displacement with both DENSE and Hyperelastic Warping, incorporating physically accurate displacements obtained by the latter to improve phase characterization in DENSE. The validity of the proposed technique is demonstrated using numerical and physical phantoms, and in vivo small animal cardiac MRI. PMID:24771572

Merchant, Samer S.; Hsu, Edward W.

2014-01-01

178

48th Annual Distinguished  

E-print Network

Ballroom, Overton Hotel and Conference Center Lubbock, Texas #12;3 2 2014 Distinguished Engineer Awards.m. Sunset Ballroom » Overton Hotel and Conference Center Lubbock, Texas Lunch Victoria Richards Harkins, Ph.D. Biochemistry » 1992 Civil Engineering » 1995, 1998 Louis Gritzo, Ph.D. Mechanical Engineering » 1988, 1990

Gelfond, Michael

179

Enhanced multi-protocol analysis via intelligent supervised embedding (EMPrAvISE): detecting prostate cancer on multi-parametric MRI  

NASA Astrophysics Data System (ADS)

Currently, there is significant interest in developing methods for quantitative integration of multi-parametric (structural, functional) imaging data with the objective of building automated meta-classifiers to improve disease detection, diagnosis, and prognosis. Such techniques are required to address the differences in dimensionalities and scales of individual protocols, while deriving an integrated multi-parametric data representation which best captures all disease-pertinent information available. In this paper, we present a scheme called Enhanced Multi-Protocol Analysis via Intelligent Supervised Embedding (EMPrAvISE); a powerful, generalizable framework applicable to a variety of domains for multi-parametric data representation and fusion. Our scheme utilizes an ensemble of embeddings (via dimensionality reduction, DR); thereby exploiting the variance amongst multiple uncorrelated embeddings in a manner similar to ensemble classifier schemes (e.g. Bagging, Boosting). We apply this framework to the problem of prostate cancer (CaP) detection on 12 3 Tesla pre-operative in vivo multi-parametric (T2-weighted, Dynamic Contrast Enhanced, and Diffusion-weighted) magnetic resonance imaging (MRI) studies, in turn comprising a total of 39 2D planar MR images. We first align the different imaging protocols via automated image registration, followed by quantification of image attributes from individual protocols. Multiple embeddings are generated from the resultant high-dimensional feature space which are then combined intelligently to yield a single stable solution. Our scheme is employed in conjunction with graph embedding (for DR) and probabilistic boosting trees (PBTs) to detect CaP on multi-parametric MRI. Finally, a probabilistic pairwise Markov Random Field algorithm is used to apply spatial constraints to the result of the PBT classifier, yielding a per-voxel classification of CaP presence. Per-voxel evaluation of detection results against ground truth for CaP extent on MRI (obtained by spatially registering pre-operative MRI with available whole-mount histological specimens) reveals that EMPrAvISE yields a statistically significant improvement (AUC=0.77) over classifiers constructed from individual protocols (AUC=0.62, 0.62, 0.65, for T2w, DCE, DWI respectively) as well as one trained using multi-parametric feature concatenation (AUC=0.67).

Viswanath, Satish; Bloch, B. Nicholas; Chappelow, Jonathan; Patel, Pratik; Rofsky, Neil; Lenkinski, Robert; Genega, Elizabeth; Madabhushi, Anant

2011-03-01

180

Measurement of Blood-Brain Barrier Permeability with T1-Weighted Dynamic Contrast-Enhanced MRI in Brain Tumors: A Comparative Study with Two Different Algorithms  

PubMed Central

The purpose of this study was to assess the feasibility of measuring different permeability parameters with T1-weighted dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in order to investigate the blood brain-barrier permeability associated with different brain tumors. The Patlak algorithm and the extended Tofts-Kety model were used to this aim. Twenty-five adult patients with tumors of different histological grades were enrolled in this study. MRI examinations were performed at 1.5?T. Multiflip angle, fast low-angle shot, and axial 3D T1-weighted images were acquired to calculate T1 maps, followed by a DCE acquisition. A region of interest was placed within the tumor of each patient to calculate the mean value of different permeability parameters. Differences in permeability measurements were found between different tumor grades, with higher histological grades characterized by higher permeability values. A significant difference in transfer constant (Ktrans) values was found between the two methods on high-grade tumors; however, both techniques revealed a significant correlation between the histological grade of tumors and their Ktrans values. Our results suggest that DCE acquisition is feasible in patients with brain tumors and that Ktrans maps can be easily obtained by these two algorithms, even if the theoretical model adopted could affect the final results. PMID:24959569

Saitta, Laura; Barletta, Laura; Bonzano, Laura; Mancardi, Giovanni Luigi; Castellan, Lucio; Ravetti, Jean Louis; Roccatagliata, Luca

2013-01-01

181

Dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) of photodynamic therapy (PDT) outcome and associated changes in the blood-brain barrier following Pc 4-PDT of glioma in an athymic nude rat model  

NASA Astrophysics Data System (ADS)

Introduction: Dynamic Contrast-Enhanced-Magnetic Resonance Imaging (DCE-MRI) appears to provide an unambiguous means of tracking the outcome of photodynamic therapy (PDT) of brain tumors with the photosensitizer Pc 4. The increase in Gd enhancement observed after Pc 4-PDT may be due to a temporary opening of the blood-brain-barrier which, as noted by others, may offer a therapeutic window. Methods: We injected 2.5 x 105 U87 cells into the brains of 9 athymic nude rats. After 8-9 days peri-tumor DCE-MRI images were acquired on a 7.0 T microMRI scanner before and after the administration of 150 ?L Gd. DCE-MRI scans were repeated three times following Pc 4-PDT. Results: The average, normalized peak enhancement in the tumor region, approximately 30-90 seconds after Gd administration, was 1.31 times greater than baseline (0.03 Standard Error [SE]) prior to PDT and was 1.44 (0.02 SE) times baseline in the first Post-PDT scans (Day 11), a statistically significant (p ~ 0.014, N=8) increase over the Pre- PDT scans, and was 1.38 (0.02 SE) times baseline in the second scans (Day 12), also a statistically significant (p ~ 0.008, N=7) increase. Observations were mixed in the third Post-PDT scans (Day 13), averaging 1.29 (0.03 SE) times baseline (p ~ 0.66, N=7). Overall a downward trend in enhancement was observed from the first to the third Post-PDT scans. Discussion: DCE-MRI may provide an unambiguous indication of brain tumor PDT outcome. The initial increase in DCE-MRI signal may correlate with a temporary, PDT-induced opening of the blood-brain-barrier, creating a potential therapeutic window.

Belle, Vaijayantee; Anka, Ali; Cross, Nathan; Thompson, Paul; Mott, Eric; Sharma, Rahul; Gray, Kayla; Zhang, Ruozhen; Xu, Yueshuo; Sun, Jiayang; Flask, Chris A.; Oleinick, Nancy L.; Dean, David

2012-02-01

182

Evidence of Key Tinnitus-Related Brain Regions Documented by a Unique Combination of Manganese-Enhanced MRI and Acoustic Startle Reflex Testing  

PubMed Central

Animal models continue to improve our understanding of tinnitus pathogenesis and aid in development of new treatments. However, there are no diagnostic biomarkers for tinnitus-related pathophysiology for use in awake, freely moving animals. To address this disparity, two complementary methods were combined to examine reliable tinnitus models (rats repeatedly administered salicylate or exposed to a single noise event): inhibition of acoustic startle and manganese-enhanced MRI. Salicylate-induced tinnitus resulted in wide spread supernormal manganese uptake compared to noise-induced tinnitus. Neither model demonstrated significant differences in the auditory cortex. Only in the dorsal cortex of the inferior colliculus (DCIC) did both models exhibit supernormal uptake. Therefore, abnormal membrane depolarization in the DCIC appears to be important in tinnitus-mediated activity. Our results provide the foundation for future studies correlating the severity and longevity of tinnitus with hearing loss and neuronal activity in specific brain regions and tools for evaluating treatment efficacy across paradigms. PMID:21179508

Holt, Avril Genene; Bissig, David; Mirza, Najab; Rajah, Gary; Berkowitz, Bruce

2010-01-01

183

Parallel MRI Reconstruction Using Variance Partitioning Regularization  

E-print Network

Parallel MRI Reconstruction Using Variance Partitioning Regularization Fa-Hsuan Lin,1,2* Fu be utilized to enhance the spatiotempo- ral resolution of MRI by employing the parallel imaging tech- nique set in parallel MRI data. The proposed Variance Partition- ing Regularization (VPR) method can improve

184

Quasi-Cubic Magnetite/Silica Core-Shell Nanoparticles as Enhanced MRI Contrast Agents for Cancer Imaging  

PubMed Central

Development of magnetic resonance imaging (MRI) contrast agents that can be readily applied for imaging of biological tissues under clinical settings is a challenging task. This is predominantly due to the expectation of an ideal MR agent being able to be synthesized in large quantities, possessing longer shelf life, reasonable biocompatibility, tolerance against its aggregation in biological fluids, and high relaxivity, resulting in better contrast during biological imaging. Although a repertoire of reports address various aforementioned issues, the previously reported results are far from optimal, which necessitates further efforts in this area. In this study, we demonstrate facile large-scale synthesis of sub-100 nm quasi-cubic magnetite and magnetite/silica core-shell (Mag@SiO2) nanoparticles and their applicability as a biocompatible T2 contrast agent for MRI of biological tissues. Our study suggests that silica-coated magnetite nanoparticles reported in this study can potentially act as improved MR contrast agents by addressing a number of aforementioned issues, including longer shelf life and stability in biological fluids. Additionally, our in vitro and in vivo studies clearly demonstrate the importance of silica coating towards improved applicability of T2 contrast agents for cancer imaging. PMID:21747962

Cowell, Simon F.; Garg, Ashish; Eu, Peter; Bhargava, Suresh K.; Bansal, Vipul

2011-01-01

185

First-ever optic neuritis: distinguishing subsequent neuromyelitis optica from multiple sclerosis.  

PubMed

To identify factors distinguishing subsequent neuromyelitis optica (NMO) from multiple sclerosis (MS) after first-ever optic neuritis (ON), we compared ophthalmic findings and MRI features of 24 NMO and 55 MS patients who initially presented with ON. The female-to-male ratio was higher, and bilateral ON was more common in NMO patients than in MS patients (p = 0.044 and p = 0.020, respectively). The visual acuity (VA) score was higher in NMO patients (p = 0.034), and a greater proportion of NMO patients had a VA score ? 5 (p = 0.003). The frequency of patients without pattern-reversal and flash visual evoked potentials was higher in the NMO group (p = 0.015). Brain MRI abnormalities were more common in the MS group (p = 0.001). The optic chiasm was affected in 25 % of NMO patients and was unaffected in MS patients, although it did not reach statistical significance (p = 0.096). There were no differences with respect to the severity of swelling and enhancement of the optic nerve. In conclusion, severe optic nerve damage at the first ON attack was associated with subsequent development of NMO, whereas presence of brain MRI abnormalities was associated with developing MS. PMID:24487628

Lim, Young-Min; Pyun, So Young; Lim, Hyun Taek; Jeong, In Hye; Kim, Kwang-Kuk

2014-05-01

186

Safety and efficacy of contrast-enhanced MRI in the brain, head and neck: gadodiamide injection versus gadopentate dimeglumine.  

PubMed

The objective of the present study was to evaluate the safety and efficacy of gadodiamide injection, a non ionic MRI contrast medium in comparison with the ionic agent gadopentate dimeglumine. Two groups of 50 patients with known or suspected lesions of the brain or head and neck were enrolled in a double -blind, randomised trial. In the gadopentate dimeglumine group three patients reported four adverse events, and in the gadodiamide injection group, four patients reported four side effects. All events were minor. Two radiologists analyzed pre and post-contrast MR images. The parameters evaluated were the number of lesions, delineation of the lesion, gain of diagnostic information, and final diagnosis. Both contrast media gave identical diagnostic information. PMID:9400053

Sadni, M; Collignon, J; Dondelinger, R F; De Greef, D

1997-10-01

187

Role of New Functional MRI Techniques in the Diagnosis, Staging, and Followup of Gynecological Cancer: Comparison with PET-CT  

PubMed Central

Recent developments in diagnostic imaging techniques have magnified the role and potential of both MRI and PET-CT in female pelvic imaging. This article reviews the techniques and clinical applications of new functional MRI (fMRI) including diffusion-weighted MRI (DWI), dynamic contrast-enhanced (DCE)-MRI, comparing with PET-CT. These new emerging provide not only anatomic but also functional imaging, allowing detection of small volumes of active tumor at diagnosis and early disease relapse, which may not result in detectable morphological changes at conventional imaging. This information is useful in distinguishing between recurrent/residual tumor and post-treatment changes and assessing treatment response, with a clear impact on patient management. Both PET-CT and now fMRI have proved to be very valuable tools for evaluation of gynecologic tumors. Most papers try to compare these techniques, but in our experience both are complementary in management of these patients. Meanwhile PET-CT is superior in diagnosis of ganglionar disease; fMRI presents higher accuracy in local preoperative staging. Both techniques can be used as biomarkers of tumor response and present high accuracy in diagnosis of local recurrence and peritoneal dissemination, with complementary roles depending on histological type, anatomic location and tumoral volume. PMID:22315683

Alvarez Moreno, Elena; Jimenez de la Peña, Mar; Cano Alonso, Raquel

2012-01-01

188

DCE-MRI Data Analysis for Cancer Area Classification  

E-print Network

DCE-MRI Data Analysis for Cancer Area Classification U. Castellani, M. Cristani, A. Daducci, P and functional parameters ob- tained by Dynamic Contrast-Enhanced MRI (DCE-MRI) techniques are analyzed, which in proposing a machine learning methodology to segment auto- matically these MRI data, by isolating tumor areas

Castellani, Umberto

189

Intracystic gadolinium-enhanced MRI in the evaluation of residual giant-cystic craniopharyngiomas in children: report of four cases.  

PubMed

Residual giant-cystic craniopharyngiomas are amenable to intracavitary bleomycin treatment. Radiologic identification of potential cyst leaks is of paramount for treatment decisions. This report describes our experience in the use of intracystic Gadolinium (Gd)-enhanced MR imaging to determine potential communications between the tumoral cysts and other intra-axial spaces in 4 pediatric patients with residual giant-cystic craniopharyngiomas in whom intracavitary bleomycin treatment was planned after the injection of .1-.2 mL of gadopentetate dimeglumine (Gd-DTPA). In three cases no leaks were found. In one case, whose previous water-soluble iodinated contrast-enhanced CT cystography was negative for leaks, intracystic Gd-enhanced MR showed intraventricular Gd enhancement. We conclude that MR imaging after intracystic administration of Gd-based contrast paramagnetic agents is useful in the detection of potential leaks in cases of giant residual craniopharyngiomas. PMID:23157657

Muñoz, Alberto; Martínez-León, María; Vázquez, Élida; Pérez da Rosa, Sandra; Crespo, José

2014-01-01

190

Hepatic Cavernous Hemangiomas: Relationship between Speed of Intratumoral Enhancement during Dynamic MRI and Apparent Diffusion Coefficient on Diffusion-Weighted Imaging  

PubMed Central

Objective To investigate the relationships between the apparent diffusion coefficients (ADCs) on diffusion-weighted imaging (DWI) and the speed of contrast-enhancement in hepatic hemangiomas. Materials and Methods Sixty-nine hepatic hemangiomas (? 1 cm) were evaluated with DWI, by using multiple b values (b = 50, 400, 800 s/mm2), followed by a gadolinium-enhanced dynamic MRI. The lesions were classified into three groups, according to the speed of contrast-enhancement on the portal phase. ADCs were measured on the ADC map automatically, and were calculated by using the two different b values (mADC50-400 with b values = 50 and 400; mADC400-800 with b values = 400 and 800 s/mm2). Results The mean ADCs (× 10-3 mm2/s) were significantly higher in the rapid group (1.9 ± 0.44) than in the intermediate (1.7 ± 0.35, p = 0.046) or the slow groups (1.4 ± 0.34, p = 0.002). There were significant differences between the rapid and the slow groups in mADC50-400 (2.12 vs. 1.48; p = 0.008) and mADC400-800 (1.68 vs. 1.22, p = 0.010), and between the rapid and the intermediate groups in mADC50-400 (2.12 vs. 1.79, p = 0.049). Comparing mADC50-400 with mADC400-800, there was a significant difference only in the rapid group (p = 0.001). Conclusion Higher ADCs of rapidly-enhancing hemangiomas may be related to richer intralesional vascular perfusion. Also, the restricted diffusion may be attributed to the difference of structural characteristics of hemangioma. PMID:23118571

Nam, Se Jin; Park, Kae Young; Chung, Jae-Joon; Kim, Joo Hee; Kim, Ki Whang

2012-01-01

191

Response of HT29 colorectal xenograft model to cediranib assessed with 18 F-fluoromisonidazole positron emission tomography, dynamic contrast-enhanced and diffusion-weighted MRI.  

PubMed

Cediranib is a small-molecule pan-vascular endothelial growth factor receptor inhibitor. The tumor response to short-term cediranib treatment was studied using dynamic contrast-enhanced and diffusion-weighted MRI at 7 T, as well as (18) F-fluoromisonidazole positron emission tomography and histological markers. Rats bearing subcutaneous HT29 human colorectal tumors were imaged at baseline; they then received three doses of cediranib (3 mg/kg per dose daily) or vehicle (dosed daily), with follow-up imaging performed 2 h after the final cediranib or vehicle dose. Tumors were excised and evaluated for the perfusion marker Hoechst 33342, the endothelial cell marker CD31, smooth muscle actin, intercapillary distance and tumor necrosis. Dynamic contrast-enhanced MRI-derived parameters decreased significantly in cediranib-treated tumors relative to pretreatment values [the muscle-normalized initial area under the gadolinium concentration curve decreased by 48% (p=0.002), the enhancing fraction by 43% (p=0.003) and K(trans) by 57% (p=0.003)], but remained unchanged in controls. No change between the pre- and post-treatment tumor apparent diffusion coefficients in either the cediranib- or vehicle-treated group was observed over the course of this study. The (18) F-fluoromisonidazole mean standardized uptake value decreased by 33% (p=0.008) in the cediranib group, but showed no significant change in the control group. Histological analysis showed that the number of CD31-positive vessels (59 per mm(2) ), the fraction of smooth muscle actin-positive vessels (80-87%) and the intercapillary distance (0.17 mm) were similar in cediranib- and vehicle-treated groups. The fraction of perfused blood vessels in cediranib-treated tumors (81 ± 7%) was lower than that in vehicle controls (91 ± 3%, p=0.02). The necrotic fraction was slightly higher in cediranib-treated rats (34 ± 12%) than in controls (26 ± 10%, p=0.23). These findings suggest that short-term treatment with cediranib causes a decrease in tumor perfusion/permeability across the tumor cross-section, but changes in vascular morphology, vessel density or tumor cellularity are not manifested at this early time point. PMID:22777834

Bokacheva, Louisa; Kotedia, Khushali; Reese, Megan; Ricketts, Sally-Ann; Halliday, Jane; Le, Carl H; Koutcher, Jason A; Carlin, Sean

2013-02-01

192

A model-constrained Monte Carlo method for blind arterial input function estimation in dynamic contrast-enhanced MRI: I. Simulations  

NASA Astrophysics Data System (ADS)

Widespread adoption of quantitative pharmacokinetic modeling methods in conjunction with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has led to increased recognition of the importance of obtaining accurate patient-specific arterial input function (AIF) measurements. Ideally, DCE-MRI studies use an AIF directly measured in an artery local to the tissue of interest, along with measured tissue concentration curves, to quantitatively determine pharmacokinetic parameters. However, the numerous technical and practical difficulties associated with AIF measurement have made the use of population-averaged AIF data a popular, if sub-optimal, alternative to AIF measurement. In this work, we present and characterize a new algorithm for determining the AIF solely from the measured tissue concentration curves. This Monte Carlo blind estimation (MCBE) algorithm estimates the AIF from the subsets of D concentration-time curves drawn from a larger pool of M candidate curves via nonlinear optimization, doing so for multiple (Q) subsets and statistically averaging these repeated estimates. The MCBE algorithm can be viewed as a generalization of previously published methods that employ clustering of concentration-time curves and only estimate the AIF once. Extensive computer simulations were performed over physiologically and experimentally realistic ranges of imaging and tissue parameters, and the impact of choosing different values of D and Q was investigated. We found the algorithm to be robust, computationally efficient and capable of accurately estimating the AIF even for relatively high noise levels, long sampling intervals and low diversity of tissue curves. With the incorporation of bootstrapping initialization, we further demonstrated the ability to blindly estimate AIFs that deviate substantially in shape from the population-averaged initial guess. Pharmacokinetic parameter estimates for Ktrans, kep, vp and ve all showed relative biases and uncertainties of less than 10% for measurements having a temporal sampling rate of 4 s and a concentration measurement noise level of ? = 0.04 mM. A companion paper discusses the application of the MCBE algorithm to DCE-MRI data acquired in eight patients with malignant brain tumors.

Schabel, Matthias C.; Fluckiger, Jacob U.; DiBella, Edward V. R.

2010-08-01

193

Functional MRI Research Facility The Functional MRI Laboratory is dedicated to supporting research on the structures and functions of  

E-print Network

Functional MRI Research Facility The Functional MRI Laboratory is dedicated to supporting research on functional MRI and associated research tools. The Laboratory's mission is to maintain an environment that will enhance the excellence of research using fMRI and associated technologies by providing a well

Kamat, Vineet R.

194

Deficits in axonal transport in hippocampal-based circuitry and the visual pathway in APP knock-out animals witnessed by manganese enhanced MRI  

PubMed Central

Mounting evidence implicates axonal transport defects, typified by the presence of axonal varicosities with aberrant accumulations of cargo, as an early event in Alzheimer’s disease (AD) pathogenesis. Work identifying amyloid precursor protein (APP) as a vesicular motor receptor for anterograde axonal transport further implicates axonal transport in AD. Manganese-enhanced MRI (MEMRI) detects axonal transport dynamics in preclinical studies. Here we pursue an understanding of the role of APP in axonal transport in the central nervous system by applying MEMRI to hippocampal circuitry and to the visual pathway in living mice homozygous for either wild type or a deletion in the APP gene (n = 12 for each genotype). Following intra-ocular or stereotaxic hippocampal injection, we performed time-lapse MRI to detect Mn2+ transport. Three dimensional whole brain datasets were compared on a voxel-wise basis using within-group pair-wise analysis. Quantification of transport to structures connected to injection sites via axonal fiber tracts was also performed. Histology confirmed consistent placement of hippocampal injections and no observable difference in glial-response to the injections. APP ?/? mice had significantly reduced transport from the hippocampus to the septal nuclei and amygdala after 7 hours and reduced transport to the contralateral hippocampus after 25 hours; axonal transport deficits in the APP ?/? animals were also identified in the visual pathway. These data support a system-wide role for APP in axonal transport within the central nervous system and demonstrate the power of MEMRI for assessing neuronal circuitry involved in memory and learning. PMID:22500926

Gallagher, Joseph J.; Zhang, Xiaowei; Ziomek, Greg; Jacobs, Russell E.; Bearer, Elaine L.

2012-01-01

195

Organic Nitrate Maintains Bone Marrow Blood Perfusion in Ovariectomized Female Rats: A Dynamic, Contrast-Enhanced Magnetic Resonance Imaging (MRI) Study  

PubMed Central

This study investigated the effects of nitrate on bone mineral density (BMD) and bone marrow perfusion in ovariectomized (OVX) female rats, and also the effects of nitrate on in vitro osteoblastic activity and osteoclastic differentiation of murine monocyte/macrophage RAW 264.7 cells. Female Sprague–Dawley rats were divided into OVX + nitrate group (isosorbide-5-mononitrate, ISM, 150 mg/kg/ day b.i.d), OVX + vehicle group, and control group. Lumbar spine CT bone densitometry and perfusion MRI were performed on the rats at baseline and week 8 post-OVX. The OVX rats’ BMD decreased by 22.5% ± 5.7% at week 8 (p < 0.001); while the OVX + ISM rats’ BMD decreased by 13.1% ± 2.7% (p < 0.001). The BMD loss difference between the two groups of rats was significant (p = 0.018). The OVX rats’ lumbar vertebral perfusion MRI maximum enhancement (Emax) decreased by 10.3% ± 5.0% at week 8 (p < 0.005), while in OVX + ISM rats, the Emax increased by 5.5% ± 6.9% (p > 0.05). The proliferation of osteoblast-like UMR-106 cells increased significantly with ISM treatment at 0.78 µM to 50 ?M. Treatment of UMR-106 cells with ISM also stimulated the BrdU uptake. After the RAW 264.7 cells were co-treated with osteoclastogenesis inducer RANKL and 6.25 ?M ~ 100 ?M of ISM for 3 days, a trend of dose-dependent increase of osteoclast number was noted. PMID:24300395

Wang, Yi-Xiang J.; Ko, Chun Hay; Griffith, James F.; Deng, Min; Wong, Hing Lok; Gu, Tao; Huang, Yu

2012-01-01

196

The association between meniscal damage of the posterior horns and localized posterior synovitis detected on T1-weighted contrast-enhanced MRI—the MOST study  

PubMed Central

Objective Synovitis is thought to be a secondary phenomenon in the osteoarthritis (OA) process and the menisci might be triggers of localized synovitis. The aim was to assess the cross-sectional associations of posterior horn meniscal damage with perimeniscal synovitis, and with synovitis posterior to the posterior cruciate ligament (PCL) using contrast enhanced (CE) MRI. Design The Multicenter Osteoarthritis (MOST) Study is a longitudinal observational study of subjects with or at risk for knee OA. Subjects are a subset of MOST who were examined with 1.5 T CE MRI and had semiquantitative synovitis (scored from 0–2 at 11 locations) and meniscal readings (scored with WORMS from 0–4 ) available. Logistic regression was used to assess the association of posterior meniscal damage and perimeniscal synovitis in the same compartment, and between posterior meniscal damage and synovitis posterior to the PCL. Results Three hundred and seventy seven knees were included (mean age 61.1 years ± 6.9, mean BMI 29.6 ± 4.9, 44.3% women). The odds for ipsi-compartmental perimeniscal synovitis were increased for knees with medial posterior horn meniscal damage (adjusted odds ratio [aOR] 2.5, 95% confidence intervals [95% CI] 1.3,4.8), but not for lateral damage (aOR 1.7, 95% CI 0.4,6.6). No positive associations were found for meniscal damage and presence of synovitis posterior to the PCL (aOR 0.9, 95% CI 0.6,1.5). Conclusions Meniscal damage of the posterior horns is associated with ipsi-compartmental perimensical synovitis. No associations were found for posterior horn meniscal damage with synovitis posterior to the PCL, which suggests that synovitis posterior to the PCL is likely to be triggered by different pathomechanisms. PMID:23270763

Roemer, Frank W.; Felson, David T.; Yang, Tianzhong; Niu, Jingbo; Crema, Michel D.; Englund, Martin; Nevitt, Michael C.; Zhang, Yuqing; Lynch, John A.; El Khoury, George Y.; Torner, James; Lewis, Cora E.; Guermazi, Ali

2013-01-01

197

Tumor Metabolism and Perfusion in Head and Neck Squamous Cell Carcinoma: Pretreatment Multimodality Imaging with 1H-Magnetic Resonance Spectroscopy, Dynamic Contrast-Enhanced MRI and 18F-FDG PET  

PubMed Central

Purpose To correlate proton magnetic resonance spectroscopy (1H-MRS), dynamic contrast-enhanced MRI (DCE-MRI) and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) in nodal metastases of patients with head and neck squamous cell carcinoma (HNSCC) for assessment of tumor biology. Additionally, pretreatment multimodality imaging (MMI) was evaluated for its efficacy in predicting short-term response to treatment. Methods and Materials Metastatic neck nodes were imaged with 1H-MRS, DCE-MRI and 18F-FDG PET in 16 patients with newly diagnosed HNSCC before treatment. Short-term radiological response was evaluated at 3–4 months. The correlations between 1H-MRS (choline concentration, Cho/W), DCE-MRI (volume transfer constant, Ktrans; volume fraction of the extravascular extracellular space, ve; and redistribution rate constant, kep) and 18F-FDG PET (standard uptake value, SUV; and total lesion glycolysis, TLG) were calculated using non-parametric Spearman rank correlation. To predict the short-term response, logistic regression analysis was performed. Results A significant positive correlation was found between Cho/W and TLG (? = 0.599, p = 0.031). Cho/W correlated negatively with heterogeneity measures std(ve) (? = ?0.691, p = 0.004) and std(kep) (? = ?0.704, p = 0.003). SUVmax values correlated strongly with MRI tumor volume (? = 0.643, p = 0.007). Logistic regression indicated that std(Ktrans) and SUVmean were significant predictors of short-term response (p < 0.07). Conclusion Pretreatment multi-modality imaging using 1H-MRS, DCE-MRI and 18F-FDG PET is feasible in HNSCC patients with nodal metastases. Additionally, combined DCE-MRI and 18F-FDG PET parameters were predictive of short-term response to treatment. PMID:21236594

Jansen, Jacobus F.A.; Schöder, Heiko; Lee, Nancy Y.; Stambuk, Hilda. E.; Wang, Ya; Fury, Matthew G.; Patel, Snehal G.; Pfister, David G.; Shah, Jatin P.; Koutcher, Jason A.; Shukla-Dave, Amita

2010-01-01

198

Characterization of hyperintense nodules on T1-weighted liver magnetic resonance imaging: Comparison of Ferucarbotran-enhanced MRI with accumulation-phase FST1WI and gadolinium-enhanced MRI  

Microsoft Academic Search

BackgroundT1-weighted (T1W) hyperintense nodules against a background of cirrhosis are diagnostically challenging in daily practice. All regenerative nodules, dysplastic nodules and hepatocellular carcinoma (HCC) might present hyperintense on T1W imaging (T1WI), so T1W hyperintense nodules cannot be definitively characterized as dysplastic nodules or HCC before biopsy, resection or transplantation. The purpose of our study was to evaluate Ferucarbotran-enhanced Magnetic Resonance

Chen-Te Chou; Ran-Chou Chen; Wei-Tsung Chen; Jiunn-Ming Lii

2011-01-01

199

Quantitative assessment of macromolecular concentration during direct infusion into an agarose hydrogel phantom using contrast-enhanced MRI  

Microsoft Academic Search

Convection-enhanced delivery (CED), that is, direct tissue infusion, has emerged as a promising local drug delivery method for treating diseases of the nervous system. Determination of the spatial distribution of therapeutic agents after infusion is important in evaluating the efficacy of treatment, optimizing infusion protocols and improving the understanding of drug pharmacokinetics. In this study, we provide a methodology to

Xiaoming Chen; Garrett W. Astaryb; Hector Sepulveda; Thomas H. Marecic; Malisa Sarntinoranont

200

Characterizing tumor changes during neoadjuvant treatment of locally advanced breast cancer patients (LABC) using dynamic-enhanced magnetic resonance imaging (DE-MRI)  

NASA Astrophysics Data System (ADS)

At Duke University Medical Center, selective LABC patients were treated on a protocol using neoadjuvant Myocet/Paclitaxel (ChT) and HT. With the purpose of generating perfusion/permeability parametric maps and to use gadolinium (Gd) enhancement curves to score and predict response to neoadjuvant treatment, a study was designed to acquire 3 sets of DE-MRI images along the 4 cycles of combined ChT and HT. A T1-weighted three-dimensional fast gradient echo technique was used over 30 minutes following bolus injection of Gd-based contrast agent. Perfusion/permeability maps were generated by fitting the signal intensity to a double exponential curve that generates washin (WiP) and washout (WoP), parameters that are associated with the tumors vascularity/permeability and cellularity. Based on the values of the WiP, the tumors were divided in lowWI (WiP < 100), mediumWI (100 200). During the HT treatments temperatures in the breast were measured invasively via a catheter inserted under CT guidance. Although minimum sampled temperatures give a crude indication of the temperature distribution, several thermal dose metrics were calculated for each of the HT fractions (e.g. T90, T50, T10). As expected, tumors that were more vascularized (i.e. higher WiP) heated less than tumors with low WiP, a degree on average. The adjuvant treatment also changed the shape and inhomogeneity of the perfusion/permeability maps, with dramatic changes after the first fraction in responders. The correlation between the thermal metrics and pathological response will be discussed, as well as possible correlation with other tumor physiology parameters. In conclusion, the Gd-enhancement analysis of DE-MRI images is able to generate information related to the tumor vascularity, permeability and cellularity that can correlate with the tumor's response to the neoadjuvant treatment in general, and to HT in particular. Work supported by a grant from the NCI CA42745.

Craciunescu, Oana I.; Jones, Ellen L.; Blackwell, Kimberly L.; Wong, Terence Z.; Rosen, Eric L.; Vujaskovic, Zeljko; MacFall, James R.; Liotcheva, Vlayka; Lora-Michiels, Michael; Prosnitz, Leonard R.; Samulski, Thaddeus V.; Dewhirst, Mark W.

2005-04-01

201

CAD-system based on kinetic analysis for non-mass-enhancing lesions in DCE-MRI  

NASA Astrophysics Data System (ADS)

Non-mass enhancing lesions represent one of the most challenging types of lesions for both the clinician as well as current computer-aided diagnosis (CAD) systems. Differently from the well-studied mass-enhancing tumors these lesions do not exhibit a typical kinetic behavior that can be further easily categorized into benign or malignant based on feature descriptors. Furthermore, the poorly defined tumor borders pose a difficulty to even the most sophisticated segmentation algorithms. To address these challenges in terms of segmentation and atypical contrast enhancement dynamics, we apply an ICA-based segmentation on these lesions and extract from the average signal intensity curve of the most representative independent component (IC). Subsequently the dynamics of this IC is modeled based on mathematical models such as the empirical mathematical model and the phenomenological universalities. An automated computer-aided diagnosis system evaluates the atypical behavior of these lesions, and additionally compares the benefit of ICA-segmentation versus active contour segmentation.

Goebl, Sebastian; Plant, Claudia; Lobbes, Marc; Meyer-Bäse, Anke

2013-05-01

202

A novel estimation method for physiological parameters in dynamic contrast-enhanced MRI: application of a distributed parameter model using Fourier-domain calculations.  

PubMed

Dynamic contrast-enhanced magnetic resonance imaging (MRI) is a promising tool in the evaluation of tumor physiology. From rapidly acquired images and a model for contrast agent pharmacokinetics, physiological parameters are derived. One pharmacokinetic model, the tissue homogeneity model, enables estimation of both blood flow and vessel permeability together with parameters that describe blood volume and extracellular extravascular volume fraction. However, studies have shown that parameter estimation with this model is unstable. Therefore, several initial guesses are needed for accurate estimates, which makes the estimation slow. In this study a new estimation algorithm for the tissue homogeneity model, based on Fourier domain calculations, was derived and implemented as a Matlab program. The algorithm was tested with Monte-Carlo simulations and the results were compared to an existing method that uses the adiabatic approximation. The algorithm was also tested on data from a metastasis in the brain. The comparison showed that the new algorithm gave more accurate results on the 2.5th and 97.5th percentile levels, for instance the error in blood volume was reduced by 21%. In addition, the time needed for the computations was reduced with a factor 25. It was concluded that the new algorithm can be used to speed up parameter estimation while accuracy can be gained at the same time. PMID:19278930

Garpebring, Anders; Ostlund, Nils; Karlsson, Mikael

2009-09-01

203

Evaluation of Enhanced Attention to Local Detail in Anorexia Nervosa Using the Embedded Figures Test; an fMRI Study  

PubMed Central

The behavioural literature in anorexia nervosa and autism spectrum disorders has indicated an overlap in cognitive profiles. One such domain is the enhancement of local processing over global processing. While functional imaging studies of autism spectrum disorder have revealed differential neural patterns compared to controls in response to tests of local versus global processing, no studies have explored such effects in anorexia nervosa. This study uses functional magnetic resonance imaging in conjunction with the embedded figures test, to explore the neural correlates of this enhanced attention to detail in the largest anorexia nervosa cohort to date. On the embedded figures tests participants are required to indicate which of two complex figures contains a simple geometrical shape. The findings indicate that whilst healthy controls showed greater accuracy on the task than people with anorexia nervosa, different brain regions were recruited. Healthy controls showed greater activation in the precuneus whilst people with anorexia nervosa showed greater activation in the fusiform gyrus. This suggests that different cognitive strategies were used to perform the task, i.e. healthy controls demonstrated greater emphasis on visuospatial searching and people with anorexia nervosa employed a more object recognition-based approach. This is in accordance with previous findings in autism spectrum disorder using a similar methodology and has implications for therapies addressing the appropriate adjustment of cognitive strategies in anorexia nervosa. PMID:23691129

Giampietro, Vincent; Van den Eynde, Frederique; Davies, Helen; Lounes, Naima; Andrew, Christopher; Dalton, Jeffrey; Simmons, Andrew; Williams, Steven C.R.; Baron-Cohen, Simon; Tchanturia, Kate

2013-01-01

204

Dynamic Contrast Enhanced MRI Detects Early Response to Adoptive NK Cellular Immunotherapy Targeting the NG2 Proteoglycan in a Rat Model of Glioblastoma  

PubMed Central

There are currently no established radiological parameters that predict response to immunotherapy. We hypothesised that multiparametric, longitudinal magnetic resonance imaging (MRI) of physiological parameters and pharmacokinetic models might detect early biological responses to immunotherapy for glioblastoma targeting NG2/CSPG4 with mAb9.2.27 combined with natural killer (NK) cells. Contrast enhanced conventional T1-weighted MRI at 7±1 and 17±2 days post-treatment failed to detect differences in tumour size between the treatment groups, whereas, follow-up scans at 3 months demonstrated diminished signal intensity and tumour volume in the surviving NK+mAb9.2.27 treated animals. Notably, interstitial volume fraction (ve), was significantly increased in the NK+mAb9.2.27 combination therapy group compared mAb9.2.27 and NK cell monotherapy groups (p?=?0.002 and p?=?0.017 respectively) in cohort 1 animals treated with 1 million NK cells. ve was reproducibly increased in the combination NK+mAb9.2.27 compared to NK cell monotherapy in cohort 2 treated with increased dose of 2 million NK cells (p<0.0001), indicating greater cell death induced by NK+mAb9.2.27 treatment. The interstitial volume fraction in the NK monotherapy group was significantly reduced compared to mAb9.2.27 monotherapy (p<0.0001) and untreated controls (p?=?0.014) in the cohort 2 animals. NK cells in monotherapy were unable to kill the U87MG cells that highly expressed class I human leucocyte antigens, and diminished stress ligands for activating receptors. A significant association between apparent diffusion coefficient (ADC) of water and ve in combination NK+mAb9.2.27 and NK monotherapy treated tumours was evident, where increased ADC corresponded to reduced ve in both cases. Collectively, these data support histological measures at end-stage demonstrating diminished tumour cell proliferation and pronounced apoptosis in the NK+mAb9.2.27 treated tumours compared to the other groups. In conclusion, ve was the most reliable radiological parameter for detecting response to intralesional NK cellular therapy. PMID:25268630

Thuen, Marte; Gras Navarro, Andrea; Huuse, Else Marie; Thorsen, Frits; Poli, Aurelie; Zimmer, Jacques; Haraldseth, Olav; Lie, Stein Atle; Enger, Per Øyvind; Chekenya, Martha

2014-01-01

205

A model-constrained Monte Carlo method for blind arterial input function estimation in dynamic contrast-enhanced MRI: II. In vivo results  

NASA Astrophysics Data System (ADS)

Accurate quantification of pharmacokinetic model parameters in tracer kinetic imaging experiments requires correspondingly accurate determination of the arterial input function (AIF). Despite significant effort expended on methods of directly measuring patient-specific AIFs in modalities as diverse as dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), dynamic positron emission tomography (PET), and perfusion computed tomography (CT), fundamental and technical difficulties have made consistent and reliable achievement of that goal elusive. Here, we validate a new algorithm for AIF determination, the Monte Carlo blind estimation (MCBE) method (which is described in detail and characterized by extensive simulations in a companion paper), by comparing AIFs measured in DCE-MRI studies of eight brain tumor patients with results of blind estimation. Blind AIFs calculated with the MCBE method using a pool of concentration-time curves from a region of normal brain tissue were found to be quite similar to the measured AIFs, with statistically significant decreases in fit residuals observed in six of eight patients. Biases between the blind and measured pharmacokinetic parameters were the dominant source of error. Averaged over all eight patients, the mean biases were +7% in K trans, 0% in kep, -11% in vp and +10% in ve. Corresponding uncertainties (median absolute deviation from the best fit line) were 0.0043?min-1 in K trans, 0.0491 min-1 in kep, 0.29% in vp and 0.45% in ve. The use of a published population-averaged AIF resulted in larger mean biases in three of the four parameters (-23% in K trans, -22% in kep, -63% in vp), with the bias in ve unchanged, and led to larger uncertainties in all four parameters (0.0083 min-1 in K trans, 0.1038 min-1 in kep, 0.31% in vp and 0.95% in ve). When blind AIFs were calculated from a region of tumor tissue, statistically significant decreases in fit residuals were observed in all eight patients despite larger deviations of these blind AIFs from the measured AIFs. The observed decrease in root-mean-square fit residuals between the normal brain and tumor tissue blind AIFs suggests that the local blood supply in tumors is measurably different from that in normal brain tissue and that the proposed method is able to discriminate between the two. We have shown the feasibility of applying the MCBE algorithm to DCE-MRI data acquired in brain, finding generally good agreement with measured AIFs and decreased biases and uncertainties relative to the use of a population-averaged AIF. These results demonstrate that the MCBE algorithm is a useful alternative to direct AIF measurement in cases where acquisition of high-quality arterial input function data is difficult or impossible.

Schabel, Matthias C.; DiBella, Edward V. R.; Jensen, Randy L.; Salzman, Karen L.

2010-08-01

206

AUR memorial award--1988. MRI enhancement of perfused tissues using chromium labeled red blood cells as an intravascular contrast agent  

SciTech Connect

It has been demonstrated that chromium (Cr) labeling significantly decreases the relaxation times of packed red blood cells (RBCs). In this study, the spin-lattice relaxation time (T1) of human red cells was shortened from 836 ms to 29 ms and the spin-spin relaxation time (T2) shortened from 134 ms to 18 ms, when the cells were labeled at a Cr incubation concentration of 50 mM. Labeling of canine cells at 50 mM resulted in a T1 of 36 ms and a T2 of 26 ms. A labeling concentration of 10 mM produced similar relaxation enhancement, with uptake of 47% of the available Cr, and was determined to be optimal. The enhancement of longitudinal and transverse relaxation rates (1/T1,-1/T2) per amount of hemoglobin-bound Cr are 6.9 s-1 mM-1 and 9.8 s-1 mM-1 respectively, different from those of a pure Cr+3 solution. Labeling cells at 10 mM decreased the survival half-time in vivo from 16.6 days to 4.7 days in dogs. No difference in red cell survival was found with the use of hetero-transfusion versus auto-transfusion of labeled RBCs. Significant shortening of the T1 (912 ms to 266 ms, P = .03) and T2 (90 ms to 70 ms, P = .006) of spleen and the T1 (764 ms to 282 ms, P = .005) and the T2 (128 ms to 86 ms, P = .005) of liver occurred when 10% of the RBC mass of dogs was exchanged with Cr labeled cells. Liver and spleen spin density changes (P greater than 0.23) and muscle spin density and relaxation changes (P greater than 0.4) were insignificant. The in vivo T1 of a canine spleen which had been infarcted did not change following transfusion with labeled cells, where the T1 of liver did shorten. We believe this preliminary study suggests that Cr labeled red cells may have the potential to become an intravascular magnetic resonance imaging contrast agent.

Eisenberg, A.D.; Conturo, T.E.; Price, R.R.; Holburn, G.E.; Partain, C.L.; James, A.E. Jr. (Vanderbilt Univ. Medical Center, Nashville, TN (USA))

1989-10-01

207

Application of Direct Virtual Coil to Dynamic Contrast-Enhanced MRI and MR Angiography with Data-Driven Parallel Imaging  

PubMed Central

Purpose To demonstrate the feasibility of Direct Virtual Coil (DVC) in the setting of 4D dynamic imaging used in multiple clinical applications. Theory and Methods Three dynamic imaging applications were chosen: pulmonary perfusion, liver perfusion and peripheral MRA, with 18, 11 and 10 subjects respectively. After view-sharing, the k-space data were reconstructed twice: once with channel-by-channel (CBC) followed by sum-of-squares coil combination and once with DVC. Images reconstructed using CBC and DVC were compared and scored based on overall image quality by two experienced radiologists using a 5-point scale. Results The CBC and DVC showed similar image quality in image domain. Time course measurements also showed good agreement in the temporal domain. CBC and DVC images were scored as equivalent for all pulmonary perfusion cases, all liver perfusion cases, and 4 out of the 10 peripheral MRA cases. For the remaining 6 peripheral MRA cases, DVC were scored as slightly better (not clinically significant) than the CBC images by Radiologist A and as equivalent by Radiologist B. Conclusion For dynamic contrast-enhanced MR applications, it is clinically feasible to reduce image reconstruction time while maintaining image quality and time course measurement using the DVC technique. PMID:23441013

Wang, Kang; Beatty, Philip J.; Nagle, Scott K.; Reeder, Scott B.; Holmes, James H.; Rahimi, Mahdi S.; Bell, Laura C.; Korosec, Frank R.; Brittain, Jean H.

2013-01-01

208

Breast MRI-Detected Cystic Apocrine Metaplasia: Imaging Features With Microvessel Analysis and Histologic Correlation.  

PubMed

OBJECTIVE. The purpose of this article is to characterize the histologic vascular features and distinguishing MRI features of cystic apocrine metaplasia to better understand imaging-pathology concordance. MATERIALS AND METHODS. Retrospective review of 261 consecutive MRI-guided biopsy cases was performed. Pathology results were reviewed for all biopsies; cystic apocrine metaplasia was identified as the predominant finding in 19 cases (7%). CD31 immunohistochemistry was subsequently performed on the most representative block of cystic apocrine metaplasia, and microvasculature was evaluated using computer-assisted image analysis. The contrast-enhanced MRI examinations correlating with the cystic apocrine metaplasia cases were independently reviewed by two radiologists specializing in breast imaging; lesions were analyzed for morphologic, kinetic, and T2 characteristics. RESULTS. On MRI review, 17 of 19 (89%) lesions were 10 mm or smaller. Washout kinetics were present in 11 of 19 (58%) lesions, and 14 of 19 (74%) lesions were at least partially hyperintense on T2-weighted sequences relative to adjacent glandular tissue. Cystic apocrine metaplasia had a higher percentage area (mean, 4.1%) of CD31-immunostained microvessels compared with background fibroglandular tissue (mean, 1.2%). CONCLUSION. Cystic apocrine metaplasia should be considered in the differential diagnosis of a T2-hyperintense enhancing focus or subcentimeter smoothly marginated mass, even if associated with washout kinetics. Cystic apocrine metaplasia contains a statistically significant increase in microvessel area compared with background fibroglandular tissue and fat and, therefore, may be considered a concordant result for this set of imaging findings. PMID:25539259

diFlorio-Alexander, Roberta M; Marotti, Jonathan D; Bond, Jesse S; Schwab, Mary C; Memoli, Vincent A; Wells, Wendy A; Poplack, Steven P

2015-01-01

209

Falx Cerebri Ossification: CT and MRI Evaluation.  

PubMed

During the last three years, CT and MRI brain scans of 40 patients revealed falx cerebri partial ossification as an incidental finding. The patients had been admitted for brain CT and MRI for several reasons. In most cases, there was no problem in the differential diagnosis of falx cerebri ossification during interpretation of the cases. In a few cases, the lesion should be distinguished from calcified meningioma, small hematoma in the interhemispheric fissure and in one case there was also meningeal infiltration of breast cancer. In these cases both CT and MRI scans of the brain were evaluated and a definite diagnosis was made. PMID:24351265

Tsitouridis, I; Natsis, K; Goutsaridou, F; Tsitouridis, K; Tarazi, L; Chondromatidou, S; Papapostolou, P; Papastergiou, C; Emmanouilidou, M

2006-11-30

210

Bipolar radiofrequency ablation for liver tumors: comparison of contrast-enhanced ultrasound with contrast-enhanced MRI/CT in the posttreatment imaging evaluation  

PubMed Central

Objective: The aim of the study was to assess the role of contrast-enhanced ultrasound (CEUS) in treatment response evaluation after percutaneous bipolar radiofrequency ablation (BRFA) for liver tumors. Methods: From May 2012 to May 2014, 39 patients with 73 tumors were treated by BRFA. One month after the treatment, CEUS and CEMRI/CECT were conducted to evaluate the treatment response. The results of CEUS were compared with CEMRI/CECT. Results: Of the 73 tumors ablated, eight (11.0%) were found to have residual viable tumor tissue and 65 (89.0%) were successfully ablated based on CEMRI/CECT within 1-month after ablation. CEUS detected seven of the eight residual tumors and 63 of 65 completely ablated tumors. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of CEUS were 87.5% (7/8), 96.9% (63/65), 77.8% (7/9), 98.4% (63/64) and 95.9% (70/73), respectively. The complete ablation (CR) rates for the tumors ?3.0 cm, 3.1-5.0 cm, and >5.0 cm were 96.6% (58/60), 63.6% (7/11), and 0% (0/2), respectively (P<0.001). CR rates were 94.7% (36/38) for primary liver tumors and 82.9% (29/35) for metastatic liver tumors (P=0.212), and were 97.4% (38/39) for the tumors with curative treatment intention and 79.4% (27/34) for those with palliative treatment intention (P=0.037). Major complication was not encountered in this series. Conclusions: BRFA is an effective technique of percutaneous ablation for liver tumors and CEUS can be used to assess its therapeutic effect accurately. PMID:25337258

Bo, Xiao-Wan; Xu, Hui-Xiong; Sun, Li-Ping; Zheng, Shu-Guang; Guo, Le-Hang; Lu, Feng; Wu, Jian; Xu, Xiao-Hong

2014-01-01

211

Portable MRI  

SciTech Connect

This project proposes to: (1) provide the power of MRI to situations where it presently isn't available; (2) perform the engineering required to move from lab to a functional prototype; and (3) leverage significant existing infrastructure and capability in ultra-low field MRI. The reasons for doing this: (1) MRI is the most powerful tool for imaging soft-tissue (e.g. brain); (2) Billions don't have access due to cost or safety issues; (3) metal will heat/move in high magnetic fields; (4) Millions of cases of traumatic brain injury in US alone; (5) even more of non-traumatic brain injury; (6) (e.g. stroke, infection, chemical exposure); (7) Need for early diagnostic; (8) 'Signature' wound of recent conflicts; (9) 22% of injuries; (10) Implications for post-traumatic stress disorder; and (11) chronic traumatic encephalopathy.

Espy, Michelle A. [Los Alamos National Laboratory

2012-06-29

212

MRI temporal acceleration techniques.  

PubMed

In recent years, there has been an explosive growth of magnetic resonance imaging (MRI) techniques that allow faster scan speed by exploiting temporal or spatiotemporal redundancy of the images. These techniques improve the performance of dynamic imaging significantly across multiple clinical applications, including cardiac functional examinations, perfusion imaging, blood flow assessment, contrast-enhanced angiography, functional MRI, and interventional imaging, among others. The scan acceleration permits higher spatial resolution, increased temporal resolution, shorter scan duration, or a combination of these benefits. Along with the exciting developments is a dizzying proliferation of acronyms and variations of the techniques. The present review attempts to summarize this rapidly growing topic and presents conceptual frameworks to understand these techniques in terms of their underlying mechanics and connections. Techniques from view sharing, keyhole, k-t, to compressed sensing are covered. PMID:22903655

Tsao, Jeffrey; Kozerke, Sebastian

2012-09-01

213

In vivo transport of Gd-DTPA2- into human meniscus and cartilage assessed with delayed gadolinium-enhanced MRI of cartilage (dGEMRIC)  

PubMed Central

Background Impaired stability is a risk factor in knee osteoarthritis (OA), where the whole joint and not only the joint cartilage is affected. The meniscus provides joint stability and is involved in the early pathological progress of OA. Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) has been used to identify pre-radiographic changes in the cartilage in OA, but has been used less commonly to examine the meniscus, and then using only a double dose of the contrast agent. The purpose of this study was to enable improved early OA diagnosis by investigate the temporal contrast agent distribution in the meniscus and femoral cartilage simultaneously, in healthy volunteers, using 3D dGEMRIC at two different doses of the contrast agent Gd-DTPA2-. Methods The right knee in 12 asymptomatic volunteers was examined using a 3D Look-Locker sequence on two occasions after an intravenous injection of a double or triple dose of Gd-DTPA2- (0.2 or 0.3 mmol/kg body weight). The relaxation time (T1) and relaxation rate (R1?=?1/T1) were measured in the meniscus and femoral cartilage before, and 60, 90, 120 and 180 minutes after injection, and the change in relaxation rate (?R1) was calculated. Paired t-test and Analysis of Variance (ANOVA) were used for statistical evaluation. Results The triple dose yielded higher concentrations of Gd-DTPA2- in the meniscus and cartilage than the double dose, but provided no additional information. The observed patterns of ?R1 were similar for double and triple doses of the contrast agent. ?R1 was higher in the meniscus than in femoral cartilage in the corresponding compartments at all time points after injection. ?R1 increased until 90-180 minutes in both the cartilage and the meniscus (p?

2014-01-01

214

Delayed Gadolinium-Enhanced MRI of Cartilage (dGEMRIC) Shows No Change in Cartilage Structural Composition after Viscosupplementation in Patients with Early-Stage Knee Osteoarthritis  

PubMed Central

Introduction Viscosupplementation with hyaluronic acid (HA) of osteoarthritic (OA) knee joints has a well-established positive effect on clinical symptoms. This effect, however, is only temporary and the working mechanism of HA injections is not clear. It was suggested that HA might have disease modifying properties because of its beneficial effect on cartilage sulphated glycosaminoglycan (sGAG) content. Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is a highly reproducible, non-invasive surrogate measure for sGAG content and hence composition of cartilage. The aim of this study was to assess whether improvement in cartilage structural composition is detected using dGEMRIC 14 weeks after 3 weekly injections with HA in patients with early-stage knee OA. Methods In 20 early-stage knee OA patients (KLG I-II), 3D dGEMRIC at 3T was acquired before and 14 weeks after 3 weekly injections with HA. To evaluate patient symptoms, the knee injury and osteoarthritis outcome score (KOOS) and a numeric rating scale (NRS) for pain were recorded. To evaluate cartilage composition, six cartilage regions in the knee were analyzed on dGEMRIC. Outcomes of dGEMRIC, KOOS and NRS before and after HA were compared using paired t-testing. Since we performed multiple t-tests, we applied a Bonferroni-Holm correction to determine statistical significance for these analyses. Results All KOOS subscales (‘pain’, ‘symptoms’, ‘daily activities’, ‘sports’ and ’quality of life’) and the NRS pain improved significantly 14 weeks after Viscosupplementation with HA. Outcomes of dGEMRIC did not change significantly after HA compared to baseline in any of the cartilage regions analyzed in the knee. Conclusions Our results confirm previous findings reported in the literature, showing persisting improvement in symptomatic outcome measures in early-stage knee OA patients 14 weeks after Viscosupplementation. Outcomes of dGEMRIC, however, did not change after Viscosupplementation, indicating no change in cartilage structural composition as an explanation for the improvement of clinical symptoms. PMID:24223194

van Tiel, Jasper; Reijman, Max; Bos, Pieter K.; Hermans, Job; van Buul, Gerben M.; Bron, Esther E.; Klein, Stefan; Verhaar, Jan A. N.; Krestin, Gabriel P.; Bierma-Zeinstra, Sita M. A.; Weinans, Harrie; Kotek, Gyula; Oei, Edwin H. G.

2013-01-01

215

Tumor Metabolism and Perfusion in Head and Neck Squamous Cell Carcinoma: Pretreatment Multimodality Imaging With {sup 1}H Magnetic Resonance Spectroscopy, Dynamic Contrast-Enhanced MRI, and [{sup 18}F]FDG-PET  

SciTech Connect

Purpose: To correlate proton magnetic resonance spectroscopy ({sup 1}H-MRS), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), and {sup 18}F-labeled fluorodeoxyglucose positron emission tomography ([{sup 18}F]FDG PET) of nodal metastases in patients with head and neck squamous cell carcinoma (HNSCC) for assessment of tumor biology. Additionally, pretreatment multimodality imaging was evaluated for its efficacy in predicting short-term response to treatment. Methods and Materials: Metastatic neck nodes were imaged with {sup 1}H-MRS, DCE-MRI, and [{sup 18}F]FDG PET in 16 patients with newly diagnosed HNSCC, before treatment. Short-term patient radiological response was evaluated at 3 to 4 months. Correlations among {sup 1}H-MRS (choline concentration relative to water [Cho/W]), DCE-MRI (volume transfer constant [K{sup trans}]; volume fraction of the extravascular extracellular space [v{sub e}]; and redistribution rate constant [k{sub ep}]), and [{sup 18}F]FDG PET (standard uptake value [SUV] and total lesion glycolysis [TLG]) were calculated using nonparametric Spearman rank correlation. To predict short-term responses, logistic regression analysis was performed. Results: A significant positive correlation was found between Cho/W and TLG ({rho} = 0.599; p = 0.031). Cho/W correlated negatively with heterogeneity measures of standard deviation std(v{sub e}) ({rho} = -0.691; p = 0.004) and std(k{sub ep}) ({rho} = -0.704; p = 0.003). Maximum SUV (SUVmax) values correlated strongly with MRI tumor volume ({rho} = 0.643; p = 0.007). Logistic regression indicated that std(K{sup trans}) and SUVmean were significant predictors of short-term response (p < 0.07). Conclusion: Pretreatment multimodality imaging using {sup 1}H-MRS, DCE-MRI, and [{sup 18}F]FDG PET is feasible in HNSCC patients with nodal metastases. Additionally, combined DCE-MRI and [{sup 18}F]FDG PET parameters were predictive of short-term response to treatment.

Jansen, Jacobus F.A. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Department of Radiology, Maastricht University Medical Center, Maastricht (Netherlands); Schoeder, Heiko [Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Lee, Nancy Y. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Stambuk, Hilda E. [Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Wang Ya [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Fury, Matthew G. [Department of Medical Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Patel, Senehal G. [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Pfister, David G. [Department of Medical Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Shah, Jatin P. [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Koutcher, Jason A. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Department of Medical Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Shukla-Dave, Amita, E-mail: davea@mskcc.org [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)

2012-01-01

216

Early post-bevacizumab progression on contrast-enhanced MRI as a prognostic marker for overall survival in recurrent glioblastoma: results from the ACRIN 6677/RTOG 0625 Central Reader Study  

PubMed Central

Background RTOG 0625/ACRIN 6677 is a multicenter, randomized, phase II trial of bevacizumab with irinotecan or temozolomide in recurrent glioblastoma (GBM). This study investigated whether early posttreatment progression on FLAIR or postcontrast MRI assessed by central reading predicts overall survival (OS). Methods Of 123 enrolled patients, 107 had baseline and at least 1 posttreatment MRI. Two central neuroradiologists serially measured bidimensional (2D) and volumetric (3D) enhancement on postcontrast T1-weighted images and volume of FLAIR hyperintensity. Progression status on all posttreatment MRIs was determined using Macdonald and RANO imaging threshold criteria, with a third neuroradiologist adjudicating discrepancies of both progression occurrence and timing. For each MRI pulse sequence, Kaplan-Meier survival estimates and log-rank test were used to compare OS between cases with or without radiologic progression. Results Radiologic progression occurred after 2 chemotherapy cycles (8 weeks) in 9 of 97 (9%), 9 of 73 (12%), and 11 of 98 (11%) 2D-T1, 3D-T1, and FLAIR cases, respectively, and 34 of 80 (43%), 21 of 58 (36%), and 37 of 79 (47%) corresponding cases after 4 cycles (16 weeks). Median OS among patients progressing at 8 or 16 weeks was significantly less than that among nonprogressors, as determined on 2D-T1 (114 vs 278 days and 214 vs 426 days, respectively; P < .0001 for both) and 3D-T1 (117 vs 306 days [P < .0001] and 223 vs 448 days [P = .0003], respectively) but not on FLAIR (201 vs 276 days [P = .38] and 303 vs 321 days [P = .13], respectively). Conclusion Early progression on 2D-T1 and 3D-T1, but not FLAIR MRI, after 8 and 16 weeks of anti–vascular endothelial growth factor therapy has highly significant prognostic value for OS in recurrent GBM. PMID:23788270

Boxerman, Jerrold L.; Zhang, Zheng; Safriel, Yair; Larvie, Mykol; Snyder, Bradley S.; Jain, Rajan; Chi, T. Linda; Sorensen, A. Gregory; Gilbert, Mark R.; Barboriak, Daniel P.

2013-01-01

217

2.3.' , MRI .  

E-print Network

1 34.2.2014 2009. ".. )MRI(. - - -ELSC "- -, "- , ,' ,- - ,ELSC.8.,. ­"" ) , , "( . , , , . . , . , . . . . - - ),(. 0F 1 MRI . . MRI . 100. . . ·. ·-. · . · , . 1. #12;3 I.IV)(/ . . / . / /­ , . 1. ,., MRI,,. )-(. ):,'4.( 2. ·18,18. ·. ·. ·. · . 3. :,. :: ·-MRI

218

Distinguished Lecture November 6, 2014  

E-print Network

Abstract: ML/Google Distinguished Lecture November 6, 2014 11:00 am NSH 3305 Joint seminar by the Machine Learning Department at Carnegie Mellon University & Google Pittsburgh Peter Stone University implemented and tested on a full-size fully autonomous robot car, and layered learning was the key deciding

219

Registration of different phases of contrast-enhanced CT\\/MRI data for computer-assisted liver surgery planning: Evaluation of state-of-the-art methods  

Microsoft Academic Search

The exact localization of intrahepatic vessels in relation to a tumour is an important issue in oncological liver surgery. For computer-assisted preoperative planning of surgical procedures high quality vessel models are required. In this work we show how to generate such models on the basis of registered CT or MRI data at different phases of contrast agent propagation. We combine

T Lange; T H Wenckebach; H Lamecker; M Seebass; M Huenerbein; S Eulenstein; B Gebauer; P M Schlag

2005-01-01

220

Play the MRI Game  

MedlinePLUS

... Teachers' Questionnaire MRI Play MRI the Magnetic Miracle Game About the game In the MRI imaging technique, strong magnets and ... last will in Paris. Play the Blood Typing Game Try to save some patients and learn about ...

221

Computer-aided detection of brain tumor invasion using multiparametric MRI  

PubMed Central

Purpose To determine the potential of using a computer-aided detection method to intelligently distinguish peritumoral edema alone from peritumor edema consisting of tumor using a combination of high-resolution morphological and physiological magnetic resonance imaging (MRI) techniques available on most clinical MRI scanners. Materials and Methods This retrospective study consisted of patients with two types of primary brain tumors: meningiomas (n=7) and glioblastomas (n=11). Meningiomas are typically benign and have a clear delineation of tumor and edema. Glioblastomas are known to invade outside the contrast-enhancing area. Four classifiers of differing designs were trained using morphological, diffusion-weighted, and perfusion-weighted features derived from MRI to discriminate tumor and edema, tested on edematous regions surrounding tumors, and assessed for their ability to detect nonenhancing tumor invasion. Results The four classifiers provided similar measures of accuracy when applied to the training and testing data. Each classifier was able to identify areas of non-enhancing tumor invasion supported with adjunct images or follow-up studies. Conclusion The combination of features derived from morphological and physiological imaging techniques contains the information necessary for computer-aided detection of tumor invasion and allows for the identification of tumor invasion not previously visualized on morphological, diffusion-weighted, and perfusion-weighted images and maps. Further validation of this approach requires obtaining spatially co-registered tissue samples in a study with a larger sample size. PMID:19711398

Jensen, Todd R.; Schmainda, Kathleen M.

2010-01-01

222

Feasibility of simultaneous whole-brain imaging on an integrated PET-MRI system using an enhanced 2-point Dixon attenuation correction method  

PubMed Central

Purpose: To evaluate a potential approach for improved attenuation correction (AC) of PET in simultaneous PET and MRI brain imaging, a straightforward approach that adds bone information missing on Dixon AC was explored. Methods: Bone information derived from individual T1-weighted MRI data using segmentation tools in SPM8, were added to the standard Dixon AC map. Percent relative difference between PET reconstructed with Dixon+bone and with Dixon AC maps were compared across brain regions of 13 oncology patients. The clinical potential of the improved Dixon AC was investigated by comparing relative perfusion (rCBF) measured with arterial spin labeling to relative glucose uptake (rPETdxbone) measured simultaneously with 18F-flurodexoyglucose in several regions across the brain. Results: A gradual increase in PET signal from center to the edge of the brain was observed in PET reconstructed with Dixon+bone. A 5–20% reduction in regional PET signals were observed in data corrected with standard Dixon AC maps. These regional underestimations of PET were either reduced or removed when Dixon+bone AC was applied. The mean relative correlation coefficient between rCBF and rPETdxbone was r = 0.53 (p < 0.001). Marked regional variations in rCBF-to-rPET correlation were observed, with the highest associations in the caudate and cingulate and the lowest in limbic structures. All findings were well matched to observations from previous studies conducted with PET data reconstructed with computed tomography derived AC maps. Conclusion: Adding bone information derived from T1-weighted MRI to Dixon AC maps can improve underestimation of PET activity in hybrid PET-MRI neuroimaging. PMID:25601825

Anazodo, Udunna C.; Thiessen, Jonathan D.; Ssali, Tracy; Mandel, Jonathan; Günther, Matthias; Butler, John; Pavlosky, William; Prato, Frank S.; Thompson, R. Terry; St. Lawrence, Keith S.

2015-01-01

223

Tailgut cysts: MRI findings.  

PubMed

Magnetic resonance imaging (MRI) features of 11 surgically resected pelvic tailgut cysts were analyzed with reference to histopathologic and clinical data. Homogeneity, size, location, signal intensity, appearance and presence of septa and/or nodules and/or peripheral rim and involvement of surrounding structures were studied. Histological examination demonstrated 11 tailgut cysts (TGC), including one infected TGC and one TGC with a component of adenocarcinoma. Lesions (3-8 cm in diameter) were exclusively or partly retrorectal in all cases but one, with an extension down the anal canal in five cases. Lesions were multicystic in all patients but one. On T1-weighted MR images, all cystic lesions contained at least one hyperintense cyst. The peripheral rim of the cystic lesion was regular and non or moderately enhancing in all cases but the two complicated TGC. Nodular peripheral rim and irregular septa were seen in the degenerated TGC. Marked enhancement of the peripheral structures was noted in the two complicated TGC. Pelvic MRI is a valuable tool in the preoperative evaluation of TGC. PMID:18566821

Aflalo-Hazan, V; Rousset, P; Mourra, N; Lewin, M; Azizi, L; Hoeffel, C

2008-11-01

224

[Intramedullary glioma. Postoperative MRI aspects].  

PubMed

MRI is the standard exploration of intramedullary tumours. Following up the patients is of prime importance to detect and treat possible recurrences at an early stage. The purpose of this paper is to specify the postoperative MRI semiology of intraspinal gliomas. During the 1986-1992 period, 47 patients operated upon in the Bicêtre hospital for primary intraspinal tumours were followed up with high-field MR (1.5 Tesla, Signa, G.E.). The retrospective visual study was carried out by two neuro-radiologists. The patients' group consisted of 24 women and 23 men aged from 15 to 67 years (mean 38 years). The tumours treated were 29 ependymomas and 18 astrocytomas. Eighty-five MRI examinations were analysed. Most of them comprised at least two planes in T1 and T2-weighted spin echo sequences with gadolinium injection, then only T1-weighted spin echo sequences after gadolinium injection (0.1 mmol/kg). The mean postoperative follow up period in the 47 patients was 32 months (range 7 to 84 months). Contrast enhancement of the spinal cord was observed in 20 cases. In the 6 patients with recurrence (5 astrocytomas, 1 malignant ependymoma) there was a segmental increase of spinal cord volume with contrast enhancement after gadolinium injection. In 3 out of these 6 patients clinical deterioration appeared later than MRI semiology. In clinically stable patients neither enhancement nor increase in spinal cord size was found in 27 cases, and enhancement alone was noted in 12 cases. There was no reliable criterion in the analysis of post gadolinium signal enhancement that could be used to differentiate recurrence from cicatricial contrast enhancement.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7629570

Borocco, A; Idir, A; Joubert, E; Lacroix, C; Hurth, M; Doyon, D

1995-06-01

225

Perfect distinguishability of quantum operations.  

PubMed

We provide a feasible necessary and sufficient condition for when an unknown quantum operation (quantum device) secretly selected from a set of known quantum operations can be identified perfectly within a finite number of queries, and thus complete the characterization of the perfect distinguishability of quantum operations. We further design an optimal protocol which can achieve the perfect discrimination between two quantum operations by a minimal number of queries. Interestingly, we find that an optimal perfect discrimination between two isometries is always achievable without auxiliary systems or entanglement. PMID:20366023

Duan, Runyao; Feng, Yuan; Ying, Mingsheng

2009-11-20

226

On the distinguishability of histograms  

NASA Astrophysics Data System (ADS)

We consider an approach for testing the hypothesis that two realizations of the random variables in the form of histograms are taken from the same statistical population ( i.e. two histograms are drawn from the same distribution). The approach is based on the notion of "significance of deviation". This approach allows to estimate the statistical difference between two histograms using multi-dimensional test statistics. The distinguishability of the histograms is estimated by constructing a number of clones (rehistograms) of the observed histograms.

Bityukov, S.; Krasnikov, N.; Nikitenko, A.; Smirnova, V.

2013-11-01

227

MRI Findings of Pericardial Fat Necrosis: Case Report  

PubMed Central

Pericardial fat necrosis is an infrequent cause of acute chest pain and this can mimic acute myocardial infarction and acute pericarditis. We describe here a patient with the magnetic resonance imaging (MRI) findings of pericardial fat necrosis and this was correlated with the computed tomography (CT) findings. The MRI findings may be helpful for distinguishing pericardial fat necrosis from other causes of acute chest pain and from the fat-containing tumors in the cardiophrenic space of the anterior mediastinum. PMID:21603300

Lee, Hyo Hyeok; Jung, Sang Sig; Jung, Seung Mun; Choi, Soo Jung; Shin, Dae Hee

2011-01-01

228

Engineering Novel Detectors and Sensors for MRI  

PubMed Central

Increasing detection sensitivity and image contrast have always been major topics of research in MRI. In this perspective, we summarize two engineering approaches to make detectors and sensors that have potential to extend the capability of MRI. The first approach is to integrate miniaturized detectors with a wireless powered parametric amplifier to enhance the detection sensitivity of remotely coupled detectors. The second approach is to microfabricate contrast agents with encoded multispectral frequency shifts, whose properties can be specified and fine-tuned by geometry. These two complementary approaches will benefit from the rapid development in nanotechnology and microfabrication which should enable new opportunities for MRI. PMID:23245489

Qian, Chunqi; Zabow, Gary; Koretsky, Alan

2013-01-01

229

Distinguishing Ichthyoses by Protein Profiling  

PubMed Central

To explore the usefulness of protein profiling for characterization of ichthyoses, we here determined the profile of human epidermal stratum corneum by shotgun proteomics. Samples were analyzed after collection on tape circles from six anatomic sites (forearm, palm, lower leg, forehead, abdomen, upper back), demonstrating site-specific differences in profiles. Additional samples were collected from the forearms of subjects with ichthyosis vulgaris (filaggrin (FLG) deficiency), recessive X-linked ichthyosis (steroid sulfatase (STS) deficiency) and autosomal recessive congenital ichthyosis type lamellar ichthyosis (transglutaminase 1 (TGM1) deficiency). The ichthyosis protein expression patterns were readily distinguishable from each other and from phenotypically normal epidermis. In general, the degree of departure from normal was lower from ichthyosis vulgaris than from lamellar ichthyosis, parallel to the severity of the phenotype. Analysis of samples from families with ichthyosis vulgaris and concomitant modifying gene mutations (STS deficiency, GJB2 deficiency) permitted correlation of alterations in protein profile with more complex genetic constellations. PMID:24130705

Rice, Robert H.; Bradshaw, Katie M.; Durbin-Johnson, Blythe P.; Rocke, David M.; Eigenheer, Richard A.; Phinney, Brett S.; Schmuth, Matthias; Gruber, Robert

2013-01-01

230

High-Speed Real-Time Resting-State fMRI Using Multi-Slab Echo-Volumar Imaging  

PubMed Central

We recently demonstrated that ultra-high-speed real-time fMRI using multi-slab echo-volumar imaging (MEVI) significantly increases sensitivity for mapping task-related activation and resting-state networks (RSNs) compared to echo-planar imaging (Posse et al., 2012). In the present study we characterize the sensitivity of MEVI for mapping RSN connectivity dynamics, comparing independent component analysis (ICA) and a novel seed-based connectivity analysis (SBCA) that combines sliding-window correlation analysis with meta-statistics. This SBCA approach is shown to minimize the effects of confounds, such as movement, and CSF and white matter signal changes, and enables real-time monitoring of RSN dynamics at time scales of tens of seconds. We demonstrate highly sensitive mapping of eloquent cortex in the vicinity of brain tumors and arterio-venous malformations, and detection of abnormal resting-state connectivity in epilepsy. In patients with motor impairment, resting-state fMRI provided focal localization of sensorimotor cortex compared with more diffuse activation in task-based fMRI. The fast acquisition speed of MEVI enabled segregation of cardiac-related signal pulsation using ICA, which revealed distinct regional differences in pulsation amplitude and waveform, elevated signal pulsation in patients with arterio-venous malformations and a trend toward reduced pulsatility in gray matter of patients compared with healthy controls. Mapping cardiac pulsation in cortical gray matter may carry important functional information that distinguishes healthy from diseased tissue vasculature. This novel fMRI methodology is particularly promising for mapping eloquent cortex in patients with neurological disease, having variable degree of cooperation in task-based fMRI. In conclusion, ultra-high-real-time speed fMRI enhances the sensitivity of mapping the dynamics of resting-state connectivity and cerebro-vascular pulsatility for clinical and neuroscience research applications. PMID:23986677

Posse, Stefan; Ackley, Elena; Mutihac, Radu; Zhang, Tongsheng; Hummatov, Ruslan; Akhtari, Massoud; Chohan, Muhammad; Fisch, Bruce; Yonas, Howard

2013-01-01

231

Enhance  

NSDL National Science Digital Library

It doesn't take a Photoshop expert to create attractive graphics for the Web. To prove this, the folks at MicroFrontier have released three graphic creation/editing packages for the Macintosh, each aimed at a different user level. All three applications support Photoshop 3.0 compatible plug-ins and basic features such as scanner support, image and resolution scaling, and basic image enhancement. Enhance, aimed at the graphics professionals, adds even more features, including multiple layers, opacity control, sixteen levels of undo, convolution filter effects, and CYMK support. A save-disabled demo version of each application is available at the MicroFrontier Website. The price for Enhance is $100 .

1998-01-01

232

MRI in craniofacial fibrous dysplasia  

Microsoft Academic Search

Five patients with biopsy-proven craniofacial fibrous dysplasia underwent MRI with T1- and T2-weighted sequences and a gadolinium-enhanced T1-weighted spin-echo sequence. Low to intermediate signal intensity was usually seen in the largest part of the lesion on both spin-echo sequences, but smaller regions of hyperintensity on T1- and T2-weighted images and intermediate signal intensity throughout a lesion on T1-weighted images were

J. W. Casselman; I. De Jonge; L. Neyt; C. De Clercq; G. D'Hont

1993-01-01

233

Intra voxel analysis in MRI  

NASA Astrophysics Data System (ADS)

A new application of Compressive Sensing (CS) in Magnetic Resonance Imaging (MRI) field is presented. In particular, first results of the Intra Voxel Analysis (IVA) technique are reported. The idea is to exploit CS peculiarities in order to distinguish different contributions inside the same resolution cell, instead of reconstructing images from not fully sampled k-space acquisition. Applied to MRI field, this means the possibility of estimating the presence of different tissues inside the same voxel, i.e. in one pixel of the obtained image. In other words, the method is the first attempt, as far as we know, of achieving Spectroscopy-like results starting from each pixel of MR images. In particular, tissues are distinguished each others by evaluating their spin-spin relaxation times. Within this manuscript, first results on clinical dataset, in particular a phantom made by aqueous solution and oil and an occipital brain lesion corresponding to a metastatic breast cancer nodule, are reported. Considering the phantom dataset, in particular focusing on the slice where the separation between water and oil occurs, the methodology is able to distinguish the two components with different spin-spin relaxation times. With respect to clinical dataset,focusing on a voxel of the lesion area, the approach is able to detect the presence of two tissues, namely the healthy and the cancer related ones, while in other location outside the lesion only the healthy tissue is detected. Of course, these are the first results of the proposed methodology, further studies on different types of clinical datasets are required in order to widely validate the approach. Although few datasets have been considered, results seem both interesting and promising.

Ambrosanio, Michele; Baselice, Fabio; Ferraioli, Giampaolo; Pascazio, Vito

2014-03-01

234

Outcome Classification of Preschool Children with Autism Spectrum Disorders Using Mri Brain Measures.  

ERIC Educational Resources Information Center

Objective: To test the hypothesis that a combination of magnetic resonance imaging (MRI) brain measures obtained during early childhood distinguish children with autism spectrum disorders (ASD) from typically developing children and is associated with functional outcome. Method: Quantitative MRI technology was used to measure gray and white matter…

Akshoomoff, Natacha; Lord, Catherine; Lincoln, Alan J.; Courchesne, Rachel Y.; Carper, Ruth A.; Townsend, Jeanne; Courchesne, Eric

2004-01-01

235

Spinal cystic schwannoma: an MRI evaluation.  

PubMed

Spinal cystic schwannomas are a very rare entity and have been reported in only a few case reports in literature; its diagnosis and management has remained a challenge. This study reviewed the results of magnetic resonance imaging (MRI) of 12 patients (7 men and 5 women; aged 37 - 67 years; mean age: 52.75 years) with pathologically proven cystic schwannoma of the spine and discussed their differential diagnosis. All patients underwent surgery at our institutions between June 2000 and April 2012. MRI showed well-delineated intradural and extramedullary lesion of iso- to low signal intensity on T1 weighted images, high signal intensity on T2 weighted images, and rim enhancement on contrast-enhanced images. A precise understanding of the MRI features of spinal schwannomas, especially the typical characteristic of enhancement, may help clinicians in their pre-operative diagnoses and surgical planning. PMID:24491015

Netra, Rana; Hui, Ma Shao; Gang, Min Zhi; Ming, Zhang

2014-02-01

236

Computerized breast parenchymal analysis on DCE-MRI  

Microsoft Academic Search

Breast density has been shown to be associated with the risk of developing breast cancer, and MRI has been recommended for high-risk women screening, however, it is still unknown how the breast parenchymal enhancement on DCE-MRI is associated with breast density and breast cancer risk. Ninety-two DCE-MRI exams of asymptomatic women with normal MR findings were included in this study.

Hui Li; Maryellen L. Giger; Yading Yuan; Sanaz A. Jansen; Li Lan; Neha Bhooshan; Gillian M. Newstead

2009-01-01

237

Numerical Study of the Magnetorotational Instability in Princeton MRI Experiment  

E-print Network

In preparation for an experimental study of magnetorotational instability (MRI) in liquid metal, we present non-ideal axisymmetric magnetohydrodynamic simulations of the nonlinear evolution of MRI in the experimental geometry. The simulations adopt fully insulating boundary conditions. No-slip conditions are imposed at the cylinders. A clear linear phase is observed with reduced linear growth rate. MRI results in an inflowing "jet" near the midplane and enhances the angular momentum transport at saturation.

Wei Liu

2008-08-22

238

Distinguishing ordinal and disordinal interactions.  

PubMed

Re-parameterized regression models may enable tests of crucial theoretical predictions involving interactive effects of predictors that cannot be tested directly using standard approaches. First, we present a re-parameterized regression model for the Linear × Linear interaction of 2 quantitative predictors that yields point and interval estimates of 1 key parameter-the crossover point of predicted values-and leaves certain other parameters unchanged. We explain how resulting parameter estimates provide direct evidence for distinguishing ordinal from disordinal interactions. We generalize the re-parameterized model to Linear × Qualitative interactions, where the qualitative variable may have 2 or 3 categories, and then describe how to modify the re-parameterized model to test moderating effects. To illustrate our new approach, we fit alternate models to social skills data on 438 participants in the National Institute of Child Health and Human Development Study of Early Child Care. The re-parameterized regression model had point and interval estimates of the crossover point that fell near the mean on the continuous environment measure. The disordinal form of the interaction supported 1 theoretical model-differential-susceptibility-over a competing model that predicted an ordinal interaction. PMID:22984788

Widaman, Keith F; Helm, Jonathan L; Castro-Schilo, Laura; Pluess, Michael; Stallings, Michael C; Belsky, Jay

2012-12-01

239

MRI-Guided Vascular Access with an Active Visualization Needle  

PubMed Central

Purpose To develop an approach to vascular access under MRI, as a component of comprehensive MRI-guided cardiovascular catheterization and intervention. Materials and Methods We attempted jugular vein access in healthy pigs as a model of “difficult” vascular access. Procedures were performed under real-time MRI guidance using reduced field of view imaging. We developed an “active” MRI antenna-needle having an open-lumen, distinct tip appearance and indicators of depth and trajectory, in order to enhance MRI visibility during the procedure. We compared performance of the active needle against an unmodified commercial passively-visualized needle, measured by procedure success among operators with different levels of experience. Results MRI-guided central vein access was feasible using both the active needle and the unmodified passive needle. The active needle required less time (88 vs. 244 sec, p=0.022) and fewer needle passes (4.5 vs. 9.1, p=0.028), irrespective of operator experience. Conclusion MRI-guided access to central veins is feasible in our animal model. When image guidance is necessary for vascular access, performing this component under MRI will allow wholly MRI-guided catheterization procedures that do not require adjunctive imaging facilities such as X-ray or ultrasound. The active needle design showed enhanced visibility, as expected. These capabilities may permit more complex catheter-based cardiovascular interventional procedures enabled by enhanced image guidance. PMID:22006552

Saikus, Christina E.; Ratnayaka, Kanishka; Barbash, Israel M.; Colyer, Jessica H.; Kocaturk, Ozgur; Faranesh, Anthony Z.; Lederman, Robert J.

2011-01-01

240

Structural MRI scan Functional MRI scan  

E-print Network

FUNCTIONAL IMAGING LABORATORY www.fil.ion.ucl.ac.uk MRI INFORMATION #12;MRI is short for Magnetic Resonance scans take place in a strong magnetic field. Therefore no metallic items can be taken into the scanner and credit cards in the lockers provided. Clothing should be loose and comfortable (not sports or `technical

Zeki, Semir

241

PRECISIONPNEUMATICROBOTFOR MRI-GUIDEDNEUROSURGERY  

E-print Network

PRECISIONPNEUMATICROBOTFOR MRI-GUIDEDNEUROSURGERY DavidB.Comber,DianaCardona,Robert of Energetic Systems Objective To provide a minimally invasive treatment for epilepsy in a closedbore MRI design objectives: ·Fully MRI compatible ­nonmagnetic and mostly plastic ·Safe operation ­Rod locks

Webster III, Robert James

242

Predictive Value of Imaging Markers at Multiple Sclerosis Disease Onset Based on Gadolinium- and USPIO-Enhanced MRI and Machine Learning  

PubMed Central

Objectives A novel characterization of Clinically Isolated Syndrome (CIS) patients according to lesion patterns is proposed. More specifically, patients are classified according to the nature of inflammatory lesions patterns. It is expected that this characterization can infer new prospective figures from the earliest imaging signs of Multiple Sclerosis (MS), since it can provide a classification of different types of lesions across patients. Methods The method is based on a two-tiered classification. Initially, the spatio-temporal lesion patterns are classified. The discovered lesion patterns are then used to characterize groups of patients. The patient groups are validated using statistical measures and by correlations at 24-month follow-up with hypointense lesion loads. Results The methodology identified 3 statistically significantly different clusters of lesion patterns showing p-values smaller than 0.01. Moreover, these patterns defined at baseline correlated with chronic hypointense lesion volumes by follow-up with an score of . Conclusions The proposed methodology is capable of identifying three major different lesion patterns that are heterogeneously present in patients, allowing a patient classification using only two MRI scans. This finding may lead to more accurate prognosis and thus to more suitable treatments at early stage of MS. PMID:24691080

Crimi, Alessandro; Commowick, Olivier; Maarouf, Adil; Ferré, Jean-Christophe; Bannier, Elise; Tourbah, Ayman; Berry, Isabelle; Ranjeva, Jean-Philippe; Edan, Gilles; Barillot, Christian

2014-01-01

243

Clinical Utility of Multimodality Imaging with Dynamic Contrast-Enhanced MRI, Diffusion-Weighted MRI, and 18F-FDG PET/CT for the Prediction of Neck Control in Oropharyngeal or Hypopharyngeal Squamous Cell Carcinoma Treated with Chemoradiation  

PubMed Central

The clinical usefulness of pretreatment imaging techniques for predicting neck control in patients with oropharyngeal or hypopharyngeal squamous cell carcinoma (OHSCC) treated with chemoradiation remains unclear. In this prospective study, we investigated the role of pretreatment dynamic contrast-enhanced perfusion MR imaging (DCE-PWI), diffusion-weighted MR imaging (DWI), and [18F]fluorodeoxyglucose-positron emission tomography (18F-FDG PET)/CT derived imaging markers for the prediction of neck control in OHSCC patients treated with chemoradiation. Patients with untreated OHSCC scheduled for chemoradiation between August, 2010 and July, 2012 were eligible for the study. Clinical variables and the following imaging parameters of metastatic neck lymph nodes were examined in relation to neck control: transfer constant, volume of blood plasma, and volume of extracellular extravascular space (Ve) on DCE-PWI; apparent diffusion coefficient (ADC) on DWI; maximum standardized uptake value, metabolic tumor volume, and total lesion glycolysis on 18F-FDG PET/CT. There were 69 patients (37 with oropharynx SCC and 32 with hypopharynx SCC) with successful pretreatment DCE-PWI and DWI available for analysis. After a median follow-up of 31 months, 25 (36.2%) participants had neck failure. Multivariate analysis identified hemoglobin level <14.3 g/dL (P?=?0.019), Ve <0.23 (P?=?0.040), and ADC >1.14×10?3 mm2/s (P?=?0.003) as independent prognostic factors for 3-year neck control. A prognostic scoring system was formulated by summing up the three significant predictors of neck control. Patients with scores of 2–3 had significantly poorer neck control and overall survival rates than patients with scores of 0–1. We conclude that hemoglobin levels, Ve, and ADC are independent pretreatment prognostic factors for neck control in OHSCC treated with chemoradiation. Their combination may identify a subgroup of patients at high risk of developing neck failure. PMID:25531391

Chan, Sheng-Chieh; Lin, Yu-Chun; Yen, Tzu-Chen; Liao, Chun-Ta; Chang, Joseph Tung-Chieh; Ko, Sheung-Fat; Wang, Hung- Ming; Chang, Chee-Jen; Wang, Jiun-Jie

2014-01-01

244

Denoising MRI Using Spectral Subtraction  

PubMed Central

Improving the signal-to-noise-ratio (SNR) of magnetic resonance imaging (MRI) using denoising techniques could enhance their value, provided that signal statistics and image resolution are not compromised. Here, a new denoising method based on spectral subtraction of the measured noise power from each signal acquisition is presented. Spectral subtraction denoising (SSD) assumes no prior knowledge of the acquired signal and does not increase acquisition time. Whereas conventional denoising/filtering methods are compromised in parallel imaging by spatially dependent noise statistics, SSD is performed on signals acquired from each coil separately, prior to reconstruction. Using numerical simulations, we show that SSD can improve SNR by up to ~45% in MRI reconstructed from both single and array coils, without compromising image resolution. Application of SSD to phantom, human heart, and brain MRI achieved SNR improvements of ~40% compared to conventional reconstruction. Comparison of SSD with anisotropic diffusion filtering showed comparable SNR enhancement at low-SNR levels (SNR = 5–15) but improved accuracy and retention of structural detail at a reduced computational load. PMID:23322757

Ertürk, M. Arcan; Bottomley, Paul A.

2014-01-01

245

The Basics of MRI  

NSDL National Science Digital Library

The Basics of MRI is a hypertextbook by Dr. Joseph Hornak of the Rochester Institute of Technology that focuses on the mathematics and physics of magnetic resonance imaging. "Exponential Functions," "Differentials and Integrals," and "Coordinate Transformation" are just a few of the mathematical topics discussed. The physics behind MRI is broken down into the following chapters: "Spin Physics," "NMR Spectroscopy," "Fourier Transforms," "Imaging Principles," and "Fourier Transform Imaging Principles." Hornak has also included a multitude of information on imaging techniques, presentation, and hardware. Those concerned with what occurs during a MRI exam, rather than the math and physics of MRI, will want to consult the chapter entitled "Your MRI Exam."

Hornak, Joseph P.

246

[Cardiac magnetic resonance imaging (MRI)].  

PubMed

TECHNOLOGICAL PROGRESS: Although cardiac magnetic resonance imaging (MRI) is now recognised as the imaging method of choice for the morphological study of the heart, recent technological progress have widened its indications to functional analysis of the heart rate, perfusion and contractility. FUNCTIONAL ASSESSMENT: The possibility of conducting pharmacological stress tests enhances the functional exploration of cardiac perfusion and contractility. The rapid sequences in apnea, tissue marking and injection of contrast products are all elements that help to refine the study of the locoregional consequences of an ischemia: does the myocardial tissue contract normally? Is it sufficiently perfused? Is it still viable? THE BENEFITS OF A NON-INVASIVE TECHNIQUE: The MRI offers clinicians a non-invasive and non-radiating imaging technique that is the perfect supplement to echocardiography. A reliable angio-coronary LRI technique would, for the first time, permit exploration of the coronary vascularisation, tissue perfusion and resulting contractility. PMID:15387389

Vignaux, Olivier

2004-07-31

247

Development of MRI Microscope  

NASA Astrophysics Data System (ADS)

We have been developing an ultra high spatial resolution MRI, “MRI Microscope”, especially for 3He physics at ultra low temperature. The ultimate goal of our MRI Microscope is to achieve 1 ?m×1 ?m two dimensional spatial resolution comparable to optical microscopes. We constructed the MRI Microscope using a magnetic field of 7.2 T, with tri-axial magnetic field gradients of 2.0 T/m. We visualized the pure liquid 3He in a 230 ?m diameter tube to study the effect of nonlinearity on the MRI Microscope at low temperature and in high magnetic fields. An MRI image was obtained at 0.22 MPa, 1 K with 1.8 ?m×1.8 ?m pixel size. At 65 mK, the MRI image became more blurred. We speculate that it was caused by large spin diffusion and nonlinearity.

Hachiya, Mahiro; Arimura, Kyohei; Ueno, Tomohiro; Matsubara, Akira

2010-02-01

248

TEXTURE-BASED CHARACTERIZATION OF ARTERIALIZATION IN SIMULATED MRI OF HYPERVASCULARIZED LIVER TUMORS  

E-print Network

TEXTURE-BASED CHARACTERIZATION OF ARTERIALIZATION IN SIMULATED MRI OF HYPERVASCULARIZED LIVER this influence, we propose a multiscale model of liver dynamic contrast-enhanced MRI, consisting of a model Terms-- Physiological modeling, multiscale model, MRI simulation, liver cancer, image analysis 1

249

Comparison of Contrast Enhanced Ultrasound and Contrast Enhanced CT or MRI in Monitoring Percutaneous Thermal Ablation Procedure in Patients with Hepatocellular Carcinoma: A MultiCenter Study in China  

Microsoft Academic Search

To evaluate the ability of contrast enhanced ultrasound (CEUS) in monitoring percutaneous thermal ablation procedure in patients with hepatocellular carcinoma (HCC) in comparison with contrast enhanced computed tomography (CECT) and\\/or magnetic resonance imaging (CEMRI). A total of 151 patients were enrolled in the study. Before the radio-frequency (RF) or microwave ablation treatment, tumor vascularity was assessed in 139 patients with

Ming-de Lu; Xiao-ling Yu; An-hua Li; Tian-an Jiang; Min-hua Chen; Bao-zhen Zhao; Xiao-dong Zhou; Jin-rui Wang

2007-01-01

250

Divalent Metal Transporter, DMT1: A Novel MRI Reporter Protein  

PubMed Central

Manganese (Mn)-enhanced MRI (MEMRI) has found a growing number of applications in anatomical and functional imaging in small animals, based on the cellular uptake of Mn ions in the brain, heart and other organs. Previous studies have relied on endogenous mechanisms of paramagnetic Mn ion uptake and enhancement. To genetically control MEMRI signals, we reverse engineered a major component of the molecular machinery involved in Mn uptake, the divalent metal transporter, DMT1. DMT1 provides positive cellular enhancement in a manner that is highly sensitive and dynamic, allowing greater spatial and temporal resolution for MRI compared to previously proposed MRI reporters such as ferritin. We characterized the MEMRI signal enhancement properties of DMT1-expressing cells, both in vitro and in vivo in mouse models of cancer and brain development. Our results show that DMT1 provides an effective genetic MRI reporter for a wide range of biological and pre-clinical imaging applications. PMID:23065715

Bartelle, Benjamin B.; Szulc, Kamila U.; Suero-Abreu, Giselle A.; Rodriguez, Joe J.; Turnbull, Daniel H.

2012-01-01

251

MICHIGAN STATE UNIVERSITY DISTINGUISHED ALUMNI AWARD  

E-print Network

MICHIGAN STATE UNIVERSITY DISTINGUISHED ALUMNI AWARD The MSU Alumni Association annually seeks and accepts nominations of alumni for the Michigan State University DISTINGUISHED ALUMNI AWARD. The selection the prestige of Michigan State University. RECIPIENT SELECTION CRITERIA · Must have a degree from Michigan

252

The wealth of distinguished doctors: retrospective survey  

PubMed Central

Objective To assess changes in the wealth of distinguished doctors in the United Kingdom between 1860 and 2001. Design Retrospective survey. Setting The UK. Participants 980 doctors of sufficient distinction to be included in the Oxford Dictionary of National Biography and who died between 1860 and 2001. Main outcome measures Wealth at death, based on probate records and adjusted relative to average earnings in 2002. Results The wealth of distinguished doctors declined substantially between 1860 and 2001, and paralleled a decline in the relative income of doctors in general. The wealth of distinguished doctors also declined relative to other groups of distinguished individuals. Conclusions In the 19th century, distinction in doctors was accompanied by substantial wealth, whereas by the end of the 20th century, the most distinguished doctors were less wealthy than their contemporaries who had achieved national distinction in other areas. PMID:16373738

McManus, I C

2005-01-01

253

Functional MRI today Peter Bandettini  

E-print Network

Functional MRI today Peter Bandettini Section on Functional Imaging Methods, National Institute Abstract Most brain imaging researchers would agree with the assertion that functional MRI (fMRI) is progressing. Since fMRI began in 1991, the number of people, papers, and abstracts related to fMRI has been

Baker, Chris I.

254

New concepts in characterization of ischemically injured myocardium by MRI.  

PubMed

New concepts regarding the assessment of ischemic myocardial injuries have been addressed in this Minireview using magnetic resonance imaging (MRI). MRI, with its different techniques, brings not only anatomic, but also physiologic, information on ischemic heart disease. It has the ability to measure identical parameters in preclinical and clinical studies. MRI techniques provide the ideal package for repeated and noninvasive assessment of myocardial anatomy, viability, perfusion, and function. MR contrast agents can be applied in a variety of ways to improve MRI sensitivity for detecting and assessing ischemically injured myocardium. With MR contrast agents protocol, it becomes possible to identify ischemic, acutely infarcted, and peri-infarcted myocardium in occlusive and reperfused infarctions. Necrosis specific and nonspecific extracellular contrast-enhanced MRI has been used to assess myocardial viability. Contrast-enhanced perfusion MRI can explore the disturbances in large (angiography) and small coronary arteries (myocardial perfusion) as the underlying cause of myocardial dysfunction. Perfusion MRI has been used to measure myocardial perfusion (ml/min/g) and to demonstrate the difference in transmural myocardial blood flow. Information on no-reflow phenomenon is derived from dynamic changes in regional signal intensity after bolus injection of MR contrast agents. Another development is the near future availability of blood pool MR contrast agents. These agents are able to assess microvascular permeability and integrity and are advantageous in MR angiography (MRA) due to their persistence in the blood. Noncontrast-enhanced MRI such as cine MRI at rest/stress, sodium MRI, and MR spectroscopy also have the potential to noninvasively assess myocardial viability in patients. Futuristic applications for MRI in the heart will focus on identifying coronary artery disease at an early stage and the beneficial effects of new therapeutic agents such as intra-arterial gene therapy. MR techniques will have great future in the drug discovery process and in testing the effects of drugs on myocardial biochemistry, physiology, and morphology. Molecular imaging is going to bloom in this decade. PMID:11393166

Saeed, M

2001-05-01

255

SENSE: Sensitivity encoding for fast MRI  

Microsoft Academic Search

New theoretical and practical concepts are presented for consid- erably enhancing the performance of magnetic resonance imag- ing (MRI) by means of arrays of multiple receiver coils. Sensitiv- ity encoding (SENSE) is based on the fact that receiver sensitivity generally has an encoding effect complementary to Fourier preparation by linear field gradients. Thus, by using multiple receiver coils in parallel

Klaas P. Pruessmann; Markus Weiger; Markus B. Scheidegger; Peter Boesiger

1999-01-01

256

Superficial Siderosis of the Central Nervous System Induced by a Single-Episode of Traumatic Subarachnoid Hemorrhage: A Study Using MRI-Enhanced Gradient Echo T2 Star-Weighted Angiography  

PubMed Central

The purpose of this study was to examine whether a single episode of traumatic subarachnoid hemorrhage (tSAH) could cause superficial siderosis of the central nervous system (SS-CNS).This study was approved by the local ethics committee. Thirty-two patients with a history of a single episode of tSAH were enrolled in the study. An episode of tSAH was confirmed in patients based on a CT scan or a lumbar puncture, and a follow-up examination was conducted at least six weeks after the brain trauma. A follow-up MRI examination was performed, using enhanced gradient echo T2 star-weighted angiography (ESWAN) to detect hemosiderin deposition on the cortical surface. The extent to which hemosiderin deposition was associated with several clinical factors was investigated. Various degrees of hemosiderin deposition were detected in 31 of 32 (96.9%) single-episode tSAH patients. Analysis of contingency tables revealed an association between the regions of subarachnoid bleeding based on CT images and the regions of hemosiderin deposition based on ESWAN images (?2 = 17.73, P<0.05). SS-CNS was determined to be a common consequence after a single episode of tSAH. The extent of hemosiderin deposition is closely correlated with the initial bleeding sites and bleeding volume. PMID:25647424

Zhao, Hongwei; Wang, Jin; Lu, Zhonglie; Wu, Qingjie; Lv, Haijuan; Liu, Hu; Gong, Xiangyang

2015-01-01

257

Superficial Siderosis of the Central Nervous System Induced by a Single-Episode of Traumatic Subarachnoid Hemorrhage: A Study Using MRI-Enhanced Gradient Echo T2 Star-Weighted Angiography.  

PubMed

The purpose of this study was to examine whether a single episode of traumatic subarachnoid hemorrhage (tSAH) could cause superficial siderosis of the central nervous system (SS-CNS).This study was approved by the local ethics committee. Thirty-two patients with a history of a single episode of tSAH were enrolled in the study. An episode of tSAH was confirmed in patients based on a CT scan or a lumbar puncture, and a follow-up examination was conducted at least six weeks after the brain trauma. A follow-up MRI examination was performed, using enhanced gradient echo T2 star-weighted angiography (ESWAN) to detect hemosiderin deposition on the cortical surface. The extent to which hemosiderin deposition was associated with several clinical factors was investigated. Various degrees of hemosiderin deposition were detected in 31 of 32 (96.9%) single-episode tSAH patients. Analysis of contingency tables revealed an association between the regions of subarachnoid bleeding based on CT images and the regions of hemosiderin deposition based on ESWAN images (?2 = 17.73, P<0.05). SS-CNS was determined to be a common consequence after a single episode of tSAH. The extent of hemosiderin deposition is closely correlated with the initial bleeding sites and bleeding volume. PMID:25647424

Zhao, Hongwei; Wang, Jin; Lu, Zhonglie; Wu, Qingjie; Lv, Haijuan; Liu, Hu; Gong, Xiangyang

2015-01-01

258

Future perspectives for intraoperative MRI.  

PubMed

MRI-guided neurosurgery not only represents a technical challenge but a transformation from conventional hand-eye coordination to interactive navigational operations. In the future, multimodality-based images will be merged into a single model, in which anatomy and pathologic changes are at once distinguished and integrated into the same intuitive framework. The long-term goals of improving surgical procedures and attendant outcomes, reducing costs, and achieving broad use can be achieved with a three-pronged approach: 1. Improving the presentation of preoperative and real-time intraoperative image information 2. Integrating imaging and treatment-related technology into therapy delivery systems 3. Testing the clinical utility of image guidance in surgery The recent focus in technology development is on improving our ability to understand and apply medical images and imaging systems. Areas of active research include image processing, model-based image analysis, model deformation, real-time registration, real-time 3D (so-called "four-dimensional") imaging, and the integration and presentation of image and sensing information in the operating room. Key elements of the technical matrix also include visualization and display platforms and related software for information and display, model-based image understanding, the use of computing clusters to speed computation (ie, algorithms with partitioned computation to optimize performance), and advanced devices and systems for 3D device tracking (navigation). Current clinical applications are successfully incorporating real-time and/or continuously up-dated image-based information for direct intra-operative visualization. In addition to using traditional imaging systems during surgery, we foresee optimized use of molecular marker technology, direct measures of tissue characterization (ie, optical measurements and/or imaging), and integration of the next generation of surgical and therapy devices (including image-guided robotic systems). Although we expect the primary clinical thrusts of MRI-guided therapy to remain in neurosurgery, with the possible addition of other areas like orthopedic, head, neck, and spine surgery, we also anticipate increased use of image-guided focal thermal ablative methods (eg, laser, RF, cryoablation, high-intensity focused ultrasound). By validating the effectiveness of MRI-guided therapy in specific clinical procedures while refining the technology that serves as its underpinning at the same time, we expect many neurosurgeons will eventually embrace MRI as their intraoperative imaging choice. Clearly, intraoperative MRI offers several palpable advantages. Most important among these are improved medical outcomes, shorter hospitalization, and better and faster procedures with fewer complications. Certain economic and practical barriers also impede the large-scale use of intraoperative MRI. Although there has been a concerted technical effort to increase the benefit/cost ratio by gathering more accurate information, designing more localized and less invasive treatment devices, and developing better methods to orient and position therapy end-effectors, further research is needed. Indeed, the drive to improve and upgrade technology is ongoing. Specifically, in the context of the real-time representation of the patient's anatomy, we have improved the quality and utility of the information presented to the surgeon, which, in turn, contributes to more successful surgical outcomes. We can also expect improvements in intraoperative imaging systems as well as increased use of nonimaging sensors and robotics to facilitate more widespread use of intraoperative MRI. PMID:15561539

Jolesz, Ferenc A

2005-01-01

259

Augmenting intraoperative MRI with preoperative fMRI and DTI by biomechanical simulation of brain deformation  

NASA Astrophysics Data System (ADS)

The key challenge facing the neurosurgeon during neurosurgery is to be able to remove from the brain as much tumor tissue as possible while preserving healthy tissue and minimizing the disruption of critical anatomical structures. The purpose of this work was to demonstrate the use of biomechanical simulation of brain deformation to project preoperative fMRI and DTI data into the coordinate system of the patient brain deformed during neurosurgery. This projection enhances the visualization of relevant critical structures available to the neurosurgeon. Our approach to tracking brain changes during neurosurgery has been previously described. We applied this procedure to warp preoperative fMRI and DTI to match intraoperative MRI. We constructed visualizations of preoperative fMRI and DTI, and intraoperative MRI showing a close correspondence between the matched data. We have previously demonstrated our biomechanical simulation of brain deformation can be executed entirely during neurosurgery. We previously used a generic atlas as a substitute for patient specific data. Here we report the successful alignment of patient-specific DTI and fMRI preoperative data into the intraoperative configuration of the patient's brain. This can significantly enhance the information available to the neurosurgeon.

Warfield, Simon K.; Talos, Florin; Kemper, Corey; Cosman, Eric; Tei, Alida; Ferrant, Matthieu; Macq, Benoit M. M.; Wells, William M., III; Black, Peter M.; Jolesz, Ferenc A.; Kikinis, Ron

2003-05-01

260

RESTRICTION FRAGMENT LENGTH POLYMORPHISMS DISTINGUISH ECTOMYCORRHIZAL FUNGI  

EPA Science Inventory

Basidiomycetous fungi, two saprophytes and three mycorrhizal, were used to assess the specificity of DNA hybridization for distinguishing genera from one another. nterspecific comparisons were done with several isolates of mycorrhizal fungi, Laccaria bicolor and L. laccata, colle...

261

Novel approaches to imaging epilepsy by MRI  

PubMed Central

As the concept of a network of injury has emerged in the treatment of epilepsy, the importance of evaluating that network noninvasively has also grown. Recently, studies utilizing magnetic resonance spectroscopic imaging, manganese-enhanced MRI and functional (f)MRI measures of resting state connectivity have demonstrated their ability to detect injury and dysfunction in cerebral networks involved in the propagation of seizures. The ability to noninvasively detect neuronal injury and dysfunction throughout cerebral networks should improve surgical planning, provide guidance for placement of devices that target network propagation and provide insights into the mechanisms of recurrence following resective surgery. PMID:20161076

Hetherington, Hoby

2009-01-01

262

Preparation and in vitro evaluation of folate-receptor-targeted SPION-polymer micelle hybrids for MRI contrast enhancement in cancer imaging.  

PubMed

Polymer-SPION hybrids were investigated for receptor-mediated localization in tumour tissue. Superparamagnetic iron oxide nanoparticles (SPIONs) prepared by high-temperature decomposition of iron acetylacetonate were monodisperse (9.27 ± 3.37 nm), with high saturation magnetization of 76.8 emu g(-1). Amphiphilic copolymers prepared from methyl methacrylate and PEG methacrylate by atom transfer radical polymerization were conjugated with folic acid (for folate-receptor specificity). The folate-conjugated polymer had a low critical micellar concentration (0.4 mg l(-1)), indicating stability of the micellar formulation. SPION-polymeric micelle clusters were prepared by desolvation of the SPION dispersion/polymer solution in water. Magnetic resonance imaging of the formulation revealed very good contrast enhancement, with transverse (T(2)) relaxivity of 260.4 mM(-1) s(-1). The biological evaluation of the SPION micelles included cellular viability assay (MTT) and uptake in HeLa cells. These studies demonstrated the potential use of these nanoplatforms for imaging and targeting. PMID:23221062

Mahajan, Shveta; Koul, Veena; Choudhary, Veena; Shishodia, Gauri; Bharti, Alok C

2013-01-11

263

Volume transfer constant (K(trans)) maps from dynamic contrast enhanced MRI as potential guidance for MR-guided high intensity focused ultrasound treatment of hypervascular uterine fibroids.  

PubMed

Higher perfusion of uterine fibroids at baseline is recognized as cause for poor efficacy of MR-guided high intensity focused ultrasound (HIFU) ablation, and higher acoustic power has been suggested for the treatment of high-perfused areas inside uterine fibroids. However, considering the heterogeneously vascular distribution inside the uterine fibroids especially with hyper vascularity, it is not easy to choose the correct therapy acoustic power for every part inside fibroids. In our study, we presented two cases of fibroids with hyper vascularity, to show the differences between them with different outcomes. Selecting higher therapy acoustic powers to ablate high-perfused areas efficiently inside fibroids might help achieving good ablation results. Volume transfer constant (K(trans)) maps from dynamic contrast-enhanced (DCE) imaging at baseline helps visualizing perfusion state inside the fibroids and locating areas with higher-perfusion. In addition, with the help of K(trans) maps, appropriate therapy acoustic power could be selected by the result of initial test and therapy sonications at different areas with significantly different perfusion state inside fibroids. PMID:25091628

Liu, Jing; Keserci, Bilgin; Yang, Xuedong; Wei, Juan; Rong, Rong; Zhu, Ying; Wang, Xiaoying

2014-11-01

264

Preparation and in vitro evaluation of folate-receptor-targeted SPION-polymer micelle hybrids for MRI contrast enhancement in cancer imaging  

NASA Astrophysics Data System (ADS)

Polymer-SPION hybrids were investigated for receptor-mediated localization in tumour tissue. Superparamagnetic iron oxide nanoparticles (SPIONs) prepared by high-temperature decomposition of iron acetylacetonate were monodisperse (9.27 ± 3.37 nm), with high saturation magnetization of 76.8 emu g-1. Amphiphilic copolymers prepared from methyl methacrylate and PEG methacrylate by atom transfer radical polymerization were conjugated with folic acid (for folate-receptor specificity). The folate-conjugated polymer had a low critical micellar concentration (0.4 mg l-1), indicating stability of the micellar formulation. SPION-polymeric micelle clusters were prepared by desolvation of the SPION dispersion/polymer solution in water. Magnetic resonance imaging of the formulation revealed very good contrast enhancement, with transverse (T2) relaxivity of 260.4 mM-1 s-1. The biological evaluation of the SPION micelles included cellular viability assay (MTT) and uptake in HeLa cells. These studies demonstrated the potential use of these nanoplatforms for imaging and targeting.

Mahajan, Shveta; Koul, Veena; Choudhary, Veena; Shishodia, Gauri; Bharti, Alok C.

2013-01-01

265

MRI at 132 ?T for the Detection of Tumors  

NASA Astrophysics Data System (ADS)

We are investigating the use of magnetic resonance imaging (MRI), typically at 132 ?T, with enhanced longitudinal-relaxation-time (T1)-weighted contrast to detect tumors. We have measured T1 of healthy and cancerous prostate tissue specimens--within a few hours of their surgical removal--from approximately 20 patients. The measurements involve a field-cycling imaging technique in which we prepolarize protons in fields up to 150 mT. After this field has been ramped down, the image of each pair of samples is encoded using magnetic field gradients, and the proton nuclear magnetic resonance signal is measured using a SQUID coupled to an untuned, second-derivative gradiometer. The observed T1 contrast is significantly greater than that at (say) 1.5 T, suggesting that one may be able to distinguish tumors from healthy tissue without a contrast agent: average T1 values at 132 ?T for healthy and cancerous prostate tissue are 60 and 46 ms. We describe a 150-mT prepolarizing coil that will allow the system to be reconfigured in a geometry suitable for in vivo imaging of human prostates.

Busch, Sarah; Mößle, Michael; Hatridge, Michael; Lee, In Hwan; Chew, Kevin; Simko, Jeff; Pines, Alex; Clarke, John

2010-03-01

266

The initial Trinidad experience with Cine MRI in clinical cardiology.  

PubMed

We describe the initial Trinidad experience with Magnetic Resonance Imaging (MRI) and Cine MRI as a diagnostic tool in clinical cardiology. Six patients from the following categories were referred for Cine MRI evaluation: congenital heart disease, valvular heart disease, aortic diseases, cardiomyopathy and intracardiac mass. All patients underwent echocardiography. MRI and Cine MRI were performed on all patients using a Siemens Magnetom 1.0 Tesla MR system at MRI Trinidad and Tobago Ltd. Selected patients underwent Angiography and/or computed tomography (CT) scanning. Clinical data and images of the six patients evaluated are described. MRI and Cine MRI provided excellent anatomical and functional details of the heart and aorta in five patients with dissection of the aorta, aneurysm of the ascending aorta, suspected left ventricular apical thrombus, infiltrative cardiomyopathy and arrhythmogenic right ventricular dysplasia. Technical difficulty was experienced with one patient who had a congenital defect (common atrium). In this study, Cine MRI provided excellent images in all but one patient. This new noninvasive technique enhanced diagnostic capabilities and facilitated management in patients with certain cardiovascular diseases. PMID:12089881

Thomas, C N; Maharaj, P; Bodapati, S; John, R; Rahaman, R; Henry, R; Brann, S

2002-03-01

267

MRI in small brains displaying extensive plasticity.  

PubMed

Manganese-enhanced magnetic resonance imaging (ME-MRI), blood oxygen-level-dependent functional MRI (BOLD fMRI) and diffusion tensor imaging (DTI) can now be applied to animal species as small as mice or songbirds. These techniques confirmed previous findings but are also beginning to reveal new phenomena that were difficult or impossible to study previously. These imaging techniques will lead to major technical and conceptual advances in systems neurosciences. We illustrate these new developments with studies of the song control and auditory systems in songbirds, a spatially organized neuronal circuitry that mediates the acquisition, production and perception of complex learned vocalizations. This neural system is an outstanding model for studying vocal learning, brain steroid hormone action, brain plasticity and lateralization of brain function. PMID:19307029

Van der Linden, Annemie; Van Meir, Vincent; Boumans, Tiny; Poirier, Colline; Balthazart, Jacques

2009-05-01

268

Benchmarking the ERG valve tip and MRI Interventions Smart Flow neurocatheter convection-enhanced delivery system's performance in a gel model of the brain: employing infusion protocols proposed for gene therapy for Parkinson's disease.  

PubMed

Convection-enhanced delivery (CED) is an advanced infusion technique used to deliver therapeutic agents into the brain. CED has shown promise in recent clinical trials. Independent verification of published parameters is warranted with benchmark testing of published parameters in applicable models such as gel phantoms, ex vivo tissue and in vivo non-human animal models to effectively inform planned and future clinical therapies. In the current study, specific performance characteristics of two CED infusion catheter systems, such as backflow, infusion cloud morphology, volume of distribution (mm(3)) versus the infused volume (mm(3)) (Vd/Vi) ratios, rate of infusion (µl min(-1)) and pressure (mmHg), were examined to ensure published performance standards for the ERG valve-tip (VT) catheter. We tested the hypothesis that the ERG VT catheter with an infusion protocol of a steady 1 µl min(-1) functionality is comparable to the newly FDA approved MRI Interventions Smart Flow (SF) catheter with the UCSF infusion protocol in an agarose gel model. In the gel phantom models, no significant difference was found in performance parameters between the VT and SF catheter. We report, for the first time, such benchmark characteristics in CED between these two otherwise similar single-end port VT with stylet and end-port non-stylet infusion systems. Results of the current study in agarose gel models suggest that the performance of the VT catheter is comparable to the SF catheter and warrants further investigation as a tool in the armamentarium of CED techniques for eventual clinical use and application. PMID:22331865

Sillay, Karl; Schomberg, Dominic; Hinchman, Angelica; Kumbier, Lauren; Ross, Chris; Kubota, Ken; Brodsky, Ethan; Miranpuri, Gurwattan

2012-04-01

269

Benchmarking the ERG valve tip and MRI Interventions Smart Flow neurocatheter convection-enhanced delivery system's performance in a gel model of the brain: employing infusion protocols proposed for gene therapy for Parkinson's disease  

NASA Astrophysics Data System (ADS)

Convection-enhanced delivery (CED) is an advanced infusion technique used to deliver therapeutic agents into the brain. CED has shown promise in recent clinical trials. Independent verification of published parameters is warranted with benchmark testing of published parameters in applicable models such as gel phantoms, ex vivo tissue and in vivo non-human animal models to effectively inform planned and future clinical therapies. In the current study, specific performance characteristics of two CED infusion catheter systems, such as backflow, infusion cloud morphology, volume of distribution (mm3) versus the infused volume (mm3) (Vd/Vi) ratios, rate of infusion (µl min-1) and pressure (mmHg), were examined to ensure published performance standards for the ERG valve-tip (VT) catheter. We tested the hypothesis that the ERG VT catheter with an infusion protocol of a steady 1 µl min-1 functionality is comparable to the newly FDA approved MRI Interventions Smart Flow (SF) catheter with the UCSF infusion protocol in an agarose gel model. In the gel phantom models, no significant difference was found in performance parameters between the VT and SF catheter. We report, for the first time, such benchmark characteristics in CED between these two otherwise similar single-end port VT with stylet and end-port non-stylet infusion systems. Results of the current study in agarose gel models suggest that the performance of the VT catheter is comparable to the SF catheter and warrants further investigation as a tool in the armamentarium of CED techniques for eventual clinical use and application.

Sillay, Karl; Schomberg, Dominic; Hinchman, Angelica; Kumbier, Lauren; Ross, Chris; Kubota, Ken; Brodsky, Ethan; Miranpuri, Gurwattan

2012-04-01

270

MRI in local staging of rectal cancer: an update.  

PubMed

Preoperative imaging for staging of rectal cancer has become an important aspect of current approach to rectal cancer management, because it helps to select suitable patients for neoadjuvant chemoradiotherapy and determine the appropriate surgical technique. Imaging modalities such as endoscopic ultrasonography, computed tomography, and magnetic resonance imaging (MRI) play an important role in assessing the depth of tumor penetration, lymph node involvement, mesorectal fascia and anal sphincter invasion, and presence of distant metastatic diseases. Currently, there is no consensus on a preferred imaging technique for preoperative staging of rectal cancer. However, high-resolution phased-array MRI is recommended as a standard imaging modality for preoperative local staging of rectal cancer, with excellent soft tissue contrast, multiplanar capability, and absence of ionizing radiation. This review will mainly focus on the role of MRI in preoperative local staging of rectal cancer and discuss recent advancements in MRI technique such as diffusion-weighted imaging and dynamic contrast-enhanced MRI. PMID:25010367

Tapan, Umit; Ozbayrak, Mustafa; Tatl?, Servet

2014-01-01

271

MRI Instrumentation and Pulse Sequences  

E-print Network

1 MRI Instrumentation and Pulse Sequences Yao Wang Polytechnic University, Brooklyn, NY 11201 Based. Figures are from the textbook except otherwise noted. Yao Wang, NYU-Poly EL5823/BE6203: MRI Instrumentation 2 Lecture Outline · Review of MRI physics and imaging principle · MRI instrumentation ­ Magnet

Suel, Torsten

272

Implantable medical devices MRI safe.  

PubMed

Pacemakers, ICDs, neurostimulators like deep brain stimulator electrodes, spiral cord stimulators, insulin pumps, cochlear implants, retinal implants, hearing aids, electro cardio gram (ECG) leads, or devices in interventional MRI such as vascular guide wires or catheters are affected by MRI magnetic and electromagnetic fields. Design of MRI Safe medical devices requires computer modeling, bench testing, phantom testing, and animal studies. Implanted medical devices can be MRI unsafe, MRI conditional or MRI safe (see glossary). In the following paragraphs we will investigate how to design implanted medical devices MRI safe. PMID:23739365

Dal Molin, Renzo; Hecker, Bertrand

2013-01-01

273

[MRI and pituitary adenoma].  

PubMed

Pituitary is the most important gland of the organism which can be affected by many diseases, especially by adenomatous processes. Classically macroadenoma, microadenoma and picoadenoma are described, according to the size of the pituitary adenoma. The diagnosis of microadenoma was long considered a highly difficult task and that of picoadenoma was impossible by computed tomography. Recently, the high resolution of multiplanar MRI has enabled the diagnosis of microadenomas measuring less than 3 mm (picoadenoma). For macroadenoma, MRI not only contributes to diagnosis but is particularly important to assess the extension and to detect possible complications. The aim of our study is to illustrate MRI features in pituitary adenoma. PMID:17072237

Harzallah, L; Boudabbous, S; Migaw, H; Harzallah, F; Ach, K; Hamdi, I; Bakir, D; Chaieb, L; Kraiem, C

2006-09-01

274

DISTINGUISHED INNOVATION AND IMPACT AWARD 2014 Basic Information  

E-print Network

DISTINGUISHED INNOVATION AND IMPACT AWARD 2014 Basic Information The Distinguished Innovation and Impact Award (DIIA) recognizes outstanding innovators whose accomplishments as faculty members distinguished themselves and the University through entrepreneurial activities that have resulted in innovations

Tipple, Brett

275

DISTINGUISHED INNOVATION AND IMPACT AWARD 2015 Basic Information  

E-print Network

DISTINGUISHED INNOVATION AND IMPACT AWARD 2015 Basic Information The Distinguished Innovation and Impact Award (DIIA) recognizes outstanding innovators whose accomplishments as faculty members distinguished themselves and the University through entrepreneurial activities that have resulted in innovations

Tipple, Brett

276

Reconstruction algorithms for MRI  

E-print Network

This dissertation presents image reconstruction algorithms for Magnetic Resonance Imaging (MRI) that aims to increase the imaging efficiency. Algorithms that reduce imaging time without sacrificing the image quality and ...

Bilgic?, Berkin

2013-01-01

277

Studies of MRI relaxivities of gadolinium-labeled dendrons  

NASA Astrophysics Data System (ADS)

In cancer detection, imaging techniques have a great importance in early diagnosis. The more sensitive the imaging technique and the earlier the tumor can be detected. Contrast agents have the capability to increase the sensitivity in imaging techniques such as magnetic resonance imaging (MRI). Until now, gadolinium-based contrast agents are mainly used for MRI, and show good enhancement. But improvement is needed for detection of smaller tumors at the earliest stage possible. The dendrons complexed with Gd(DOTA) were synthesized and evaluated as a new MRI contrast agent. The longitudinal and transverse relaxation effects were tested and compared with commercial drug Magnevist, Gd(DTPA).

Pan, Hongmu; Daniel, Marie-Christine

2011-05-01

278

Distinguished Lecturer Series Understanding Climate Change  

E-print Network

Distinguished Lecturer Series Understanding Climate Change: Opportunities and Challenges for Data A Climate change is the defining environmental challenge facing our planet, yet there is considerable.Anew and transformative approach is required to understand the potential impact of climate change. Data driven approaches

California at Davis, University of

279

Fall 2011 -Distinguished Lecture Program Semantic Web  

E-print Network

Fall 2011 - Distinguished Lecture Program Semantic Web: State of the Art Semantic Web: State record lists over 160 publications in such diverse areas as semantic web, neural-symbolic integration-in-chief of the IOS Press journal "Semantic Web" and the IOS Press book series "Studies on the Semantic Web". He

Mayfield, John

280

Autonomic Nervous System Activity Distinguishes among Emotions  

Microsoft Academic Search

Emotion-specific activity in the autonomic nervous system was generated by constructing facial prototypes of emotion muscle by muscle and by reliving past emotional experiences. The autonomic activity produced distinguished not only between positive and negative emotions, but also among negative emotions. This finding challenges emotion theories that have proposed autonomic activity to be undifferentiated or that have failed to address

Paul Ekman; Robert W. Levenson; Wallace V. Friesen

1983-01-01

281

Comparative Minicolumnar Morphometry of Three Distinguished Scientists  

ERIC Educational Resources Information Center

It has been suggested that the cell minicolumn is the smallest module capable of information processing within the brain. In this case series, photomicrographs of six regions of interests (Brodmann areas 4, 9, 17, 21, 22, and 40) were analyzed by computerized image analysis for minicolumnar morphometry in the brains of three distinguished

Casanova, Manuel F.; Switala, Andrew E.; Trippe, Juan; Fitzgerald, Michael

2007-01-01

282

Soil Properties That Distinguish Ecological Sites  

E-print Network

that determines soil water amounts. Soil properties are features of a soil: · e.g. soil texture, depth #12Soil Properties That Distinguish Ecological Sites Mike Duniway USGS-Southwest Biological Science Properties · Within a climatic zone (e.g. MLRA), differentiation of ecological sites based on soil

283

"Distinguished Alumni Award Dr. Sultana Nahar"  

E-print Network

- national Society of Muslim Women in Science". She has also founded STEM programs in several countries, especially women in developing countries. A role model for Muslim woman, she is the founder of "The Inter State of Women of Wayne. It is an honor to bestow upon her today the Distinguished Alumni Award. 1 #12;

Nahar, Sultana Nurun

284

Comparison between Side-Channel Analysis Distinguishers  

E-print Network

) metrics, Probability/Cumulative Density Function (PDF/CDF), Kolmogorov-Smirnov Analysis (KSA), InterComparison between Side-Channel Analysis Distinguishers Houssem Maghrebi, Olivier Rioul, Sylvain-class Kolmogorov-Smirnov Analysis (IKSA), Masking. 1 Introduction Smart cards play a crucial role in many security

Rioul, Olivier

285

Indicators for cognitive performance and subjective cognitive complaints in multiple sclerosis: a role for advanced MRI?  

PubMed

Previous studies showed that advanced neuroimaging measures (functional MRI, diffusion tensor imaging) could distinguish multiple sclerosis (MS) patients with and without cognitive impairment. Are these measures indeed better indicators for cognitive impairment or subjective cognitive complaints than conventional MRI? Fifty MS patients and 29 controls were investigated. Regression analysis, including socio-demographic data, disease characteristics, psychological measures, and (advanced) neuroimaging, showed that worse cognitive performance was associated with male sex, lower education, and lower gray matter volume. Subjective cognitive complaints were associated with fatigue and less hippocampal atrophy. Advanced MRI measures did not add to the predictive power of our model. PMID:24277326

Hulst, Hanneke E; Gehring, Karin; Uitdehaag, Bernard Mj; Visser, Leo H; Polman, Chris H; Barkhof, Frederik; Sitskoorn, Margriet M; Geurts, Jeroen Jg

2013-11-25

286

EEG-informed fMRI analysis during a hand grip task: estimating the relationship between EEG rhythms and the BOLD signal  

PubMed Central

In the last decade, an increasing interest has arisen in investigating the relationship between the electrophysiological and hemodynamic measurements of brain activity, such as EEG and (BOLD) fMRI. In particular, changes in BOLD have been shown to be associated with changes in the spectral profile of neural activity, rather than with absolute power. Concurrently, recent findings showed that different EEG rhythms are independently related to changes in the BOLD signal: therefore, it would be also important to distinguish between the contributions of the different EEG rhythms to BOLD fluctuations when modeling the relationship between the two signals. Here we propose a method to perform EEG-informed fMRI analysis where the changes in the spectral profile are modeled, and, at the same time, the distinction between rhythms is preserved. We compared our model with two other frequency-dependent regressors modeling using simultaneous EEG-fMRI data from healthy subjects performing a motor task. Our results showed that the proposed method better captures the correlations between BOLD signal and EEG rhythms modulations, identifying task-related, well localized activated volumes. Furthermore, we showed that including among the regressors also EEG rhythms not primarily involved in the task enhances the performance of the analysis, even when only correlations with BOLD signal and specific EEG rhythms are explored. PMID:24744720

Sclocco, Roberta; Tana, Maria G.; Visani, Elisa; Gilioli, Isabella; Panzica, Ferruccio; Franceschetti, Silvana; Cerutti, Sergio; Bianchi, Anna M.

2014-01-01

287

Microtesla MRI with dynamic nuclear polarization  

PubMed Central

Magnetic resonance imaging at microtesla fields is a promising imaging method that combines the pre-polarization technique and broadband signal reception by superconducting quantum interference device (SQUID) sensors to enable in vivo MRI at microtesla-range magnetic fields similar in strength to the Earth magnetic field. Despite significant advances in recent years, the potential of microtesla MRI for biomedical imaging is limited by its insufficient signal-to-noise ratio due to a relatively low sample polarization. Dynamic nuclear polarization (DNP) is a widely used approach that allows polarization enhancement by two-four orders of magnitude without an increase in the polarizing field strength. In this work, the first implementation of microtesla MRI with Overhauser DNP and SQUID signal detection is described. The first measurements of carbon-13 NMR spectra at microtesla fields are also reported. The experiments were performed at the measurement field of 96 microtesla, corresponding to Larmor frequency of 4 kHz for protons and 1 kHz for carbon-13. The Overhauser DNP was carried out at 3.5 –5.7 mT field using rf irradiation at 120 MHz. Objects for imaging included water phantoms and a cactus plant. Aqueous solutions of metabolically relevant sodium bicarbonate, pyruvate, alanine, and lactate, labeled with carbon-13, were used for NMR studies. All the samples were doped with TEMPO free radicals. The Overhauser DNP enabled nuclear polarization enhancement by factor as high as ?95 for protons and as high as ?200 for carbon-13, corresponding to thermal polarizations at 0.33 T and 1.1 T fields, respectively. These results demonstrate that SQUID-based microtesla MRI can be naturally combined with Overhauser DNP in one system, and that its signal-to-noise performance is greatly improved in this case. They also suggest that microtesla MRI can become an efficient tool for in vivo imaging of hyperpolarized carbon-13, produced by the low-temperature dissolution DNP. PMID:20843715

Zotev, Vadim S.; Owens, Tuba; Matlashov, Andrei N.; Savukov, Igor M.; Gomez, John J.; Espy, Michelle A.

2010-01-01

288

Microtesla MRI with dynamic nuclear polarization  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging at microtesla fields is a promising imaging method that combines the pre-polarization technique and broadband signal reception by superconducting quantum interference device (SQUID) sensors to enable in vivo MRI at microtesla-range magnetic fields similar in strength to the Earth magnetic field. Despite significant advances in recent years, the potential of microtesla MRI for biomedical imaging is limited by its insufficient signal-to-noise ratio due to a relatively low sample polarization. Dynamic nuclear polarization (DNP) is a widely used approach that allows polarization enhancement by 2-4 orders of magnitude without an increase in the polarizing field strength. In this work, the first implementation of microtesla MRI with Overhauser DNP and SQUID signal detection is described. The first measurements of carbon-13 NMR spectra at microtesla fields are also reported. The experiments were performed at the measurement field of 96 ?T, corresponding to Larmor frequency of 4 kHz for protons and 1 kHz for carbon-13. The Overhauser DNP was carried out at 3.5-5.7 mT fields using rf irradiation at 120 MHz. Objects for imaging included water phantoms and a cactus plant. Aqueous solutions of metabolically relevant sodium bicarbonate, pyruvate, alanine, and lactate, labeled with carbon-13, were used for NMR studies. All the samples were doped with TEMPO free radicals. The Overhauser DNP enabled nuclear polarization enhancement by factor as large as -95 for protons and as large as -200 for carbon-13, corresponding to thermal polarizations at 0.33 T and 1.1 T fields, respectively. These results demonstrate that SQUID-based microtesla MRI can be naturally combined with Overhauser DNP in one system, and that its signal-to-noise performance is greatly improved in this case. They also suggest that microtesla MRI can become an efficient tool for in vivo imaging of hyperpolarized carbon-13, produced by low-temperature dissolution DNP.

Zotev, Vadim S.; Owens, Tuba; Matlashov, Andrei N.; Savukov, Igor M.; Gomez, John J.; Espy, Michelle A.

2010-11-01

289

Longitudinal MRI contrast enhanced monitoring of early tumour development with manganese chloride (MnCl2) and superparamagnetic iron oxide nanoparticles (SPIOs) in a CT1258 based in vivo model of prostate cancer  

PubMed Central

Background Cell lines represent a key tool in cancer research allowing the generation of neoplasias which resemble initial tumours in in-vivo animal models. The characterisation of early tumour development is of major interest in order to evaluate the efficacy of therapeutic agents. Magnetic resonance imaging (MRI) based in-vivo characterisation allows visualisation and characterisation of tumour development in early stages prior to manual palpation. Contrast agents for MRI such as superparamagnetic iron oxide nanoparticles (SPIOs) and manganese chloride (MnCl2) represent powerful tools for the in-vivo characterisation of early stage tumours. In this experimental study, we labelled prostate cancer cells with MnCl2 or SPIOs in vitro and used 1?T MRI for tracing labelled cells in-vitro and 7?T MRI for tracking in an in-vivo animal model. Methods Labelling of prostate cancer cells CT1258 was established in-vitro with MnCl2 and SPIOs. In-vitro detection of labelled cells in an agar phantom was carried out through 1?T MRI while in-vivo detection was performed using 7?T MRI after subcutaneous (s.c.) injection of labelled cells into NOD-Scid mice (n?=?20). The animals were scanned in regular intervals until euthanization. The respective tumour volumes were analysed and corresponding tumour masses were subjected to histologic examination. Results MnCl2in-vitro labelling resulted in no significant metabolic effects on proliferation and cell vitality. In-vitro detection-limit accounted 105 cells for MnCl2 as well as for SPIOs labelling. In-vivo 7?T MRI scans allowed detection of 103 and 104 cells. In-vivo MnCl2 labelled cells were detectable from days 4–16 while SPIO labelling allowed detection until 4?days after s.c. injection. MnCl2 labelled cells were highly tumourigenic in NOD-Scid mice and the tumour volume development was characterised in a time dependent manner. The amount of injected cells correlated with tumour size development and disease progression. Histological analysis of the induced tumour masses demonstrated characteristic morphologies of prostate adenocarcinoma. Conclusions To the best of our knowledge, this is the first study reporting direct in-vitro MnCl2 labelling and 7?T based in-vivo MRI tracing of cancer cells in a model of prostate cancer. MnCl2 labelling was found to be suitable for in-vivo tracing allowing long detection periods. The labelled cells kept their highly tumourigenic potential in-vivo. Tumour volume development was visualised prior to manual palpation allowing tumour characterisation in early stages of the disease. PMID:22784304

2012-01-01

290

Distinguishing Provenance Equivalence of Earth Science Data  

NASA Technical Reports Server (NTRS)

Reproducibility of scientific research relies on accurate and precise citation of data and the provenance of that data. Earth science data are often the result of applying complex data transformation and analysis workflows to vast quantities of data. Provenance information of data processing is used for a variety of purposes, including understanding the process and auditing as well as reproducibility. Certain provenance information is essential for producing scientifically equivalent data. Capturing and representing that provenance information and assigning identifiers suitable for precisely distinguishing data granules and datasets is needed for accurate comparisons. This paper discusses scientific equivalence and essential provenance for scientific reproducibility. We use the example of an operational earth science data processing system to illustrate the application of the technique of cascading digital signatures or hash chains to precisely identify sets of granules and as provenance equivalence identifiers to distinguish data made in an an equivalent manner.

Tilmes, Curt; Yesha, Ye; Halem, M.

2010-01-01

291

Techniques for Fast Stereoscopic MRI  

PubMed Central

Stereoscopic MRI can impart 3D perception with only two image acquisitions. This economy over standard multiplanar 3D volume renderings allows faster frame rates, which are needed for real-time imaging applications. Real-time 3D perception may enhance the appreciation of complex anatomical structures, and may improve hand-eye coordination while manipulating a medical device during an image-guided interventional procedure. To this goal, a system is being developed to acquire and display stereoscopic MR images in real-time. A clinically used, fast gradient-recalled echo-train sequence has been modified to produce stereo image pairs. Features have been added for depth cueing, view sharing, and bulk signal suppression. A workstation was attached to a clinical MR scanner for fast data extraction, image reconstruction and stereoscopic image display. PMID:11477636

Guttman, Michael A.; McVeigh, Elliot R.

2007-01-01

292

Familial Identification: Population Structure and Relationship Distinguishability  

PubMed Central

With the expansion of offender/arrestee DNA profile databases, genetic forensic identification has become commonplace in the United States criminal justice system. Implementation of familial searching has been proposed to extend forensic identification to family members of individuals with profiles in offender/arrestee DNA databases. In familial searching, a partial genetic profile match between a database entrant and a crime scene sample is used to implicate genetic relatives of the database entrant as potential sources of the crime scene sample. In addition to concerns regarding civil liberties, familial searching poses unanswered statistical questions. In this study, we define confidence intervals on estimated likelihood ratios for familial identification. Using these confidence intervals, we consider familial searching in a structured population. We show that relatives and unrelated individuals from population samples with lower gene diversity over the loci considered are less distinguishable. We also consider cases where the most appropriate population sample for individuals considered is unknown. We find that as a less appropriate population sample, and thus allele frequency distribution, is assumed, relatives and unrelated individuals become more difficult to distinguish. In addition, we show that relationship distinguishability increases with the number of markers considered, but decreases for more distant genetic familial relationships. All of these results indicate that caution is warranted in the application of familial searching in structured populations, such as in the United States. PMID:22346758

Rohlfs, Rori V.; Fullerton, Stephanie Malia; Weir, Bruce S.

2012-01-01

293

Mobile instrumentation platform to distinguish airway disorders  

PubMed Central

Asthma and chronic obstructive pulmonary disease (COPD) are distinct but clinically overlapping airway disorders which often create diagnostic and therapeutic dilemmas. Current strategies to discriminate these diseases are limited by insensitivity and poor performance due to biologic variability. We tested the hypothesis that a gas chromatograph / differential mobility spectrometer (GC/DMS) sensor could distinguish between clinically well-defined groups with airway disorders based on the volatile organic compounds (VOCs) obtained from exhaled breath. After comparing VOC profiles obtained from 13 asthma, 5 COPD, and 13 healthy control subjects, we found that VOC profiles distinguished asthma from healthy controls and also a subgroup of asthmatics taking the drug omalizumab from healthy controls. The VOC profiles could not distinguish between COPD and any of the other groups. Our results show a potential application of the GC/DMS for non-invasive and bedside diagnostics of asthma and asthma therapy monitoring. Future studies will focus on larger sample sizes and patient cohorts. PMID:23446184

Schivo, Michael; Seichter, Felicia; Aksenov, Alexander A.; Pasamontes, Alberto; Peirano, Daniel J.; Mizaikoff, Boris; Kenyon, Nicholas J.; Davis, Cristina E.

2013-01-01

294

Challenges for Molecular Neuroimaging with MRI  

PubMed Central

Magnetic resonance (MRI)-based molecular imaging methods are beginning to have impact in neuroscience. A growing number of molecular imaging agents have been synthesized and tested in vitro, but so far relatively few have been validated in the brains of live animals. Here, we discuss key challenges associated with expanding the repertoire of successful molecular neuroimaging approaches. The difficulty of delivering agents past the blood-brain barrier (BBB) is a particular obstacle to molecular imaging in the central nervous system. We review established and emerging techniques for trans-BBB delivery, including intracranial infusion, BBB disruption, and transporter-related methods. Improving the sensitivity with which MRI-based molecular agents can be detected is a second major challenge. Better sensitivity would in turn reduce the requirements for delivery and alleviate potential side effects. We discuss recent efforts to enhance relaxivity of conventional longitudinal relaxation time (T1) and transverse relaxation time (T2) MRI contrast agents, as well as strategies that involve amplifying molecular signals or reducing endogenous background influences. With ongoing refinement of imaging approaches and brain delivery methods, MRI-based techniques for molecular-level neuroscientific investigation will fall increasingly within reach. PMID:20808721

Lelyveld, Victor S.; Atanasijevic, Tatjana; Jasanoff, Alan

2010-01-01

295

Polynomial transformation for MRI feature extraction  

NASA Astrophysics Data System (ADS)

We present a non-linear (polynomial) transformation to minimize scattering of data points around normal tissue clusters in a normalized MRI feature space, in which normal tissues are clustered around pre-specified target positions. This transformation is motivated by non-linear relationship between MRI pixel intensities and intrinsic tissue parameters (e.g., T1, T2, PD). To determine scattering amount, we use ratio of summation of within-class distances fro clusters to summation of their between-class distances. We find the transformation by minimizing the scattering amount. Next, we generate a 3D visualization of the MRI feature space and define regions of interest (ROI's) on clusters seen for normal and abnormal tissues. We use these ROI's to estimate signature vectors (cluster centers). Finally, we use the signature vectors for segmenting and characterizing tissues. We used simulation, phantom, and brain MRI to evaluate the polynomial transformation and compare it to the linear transformation. In all studies, we were able to identify clusters for normal and abnormal tissues and segment the images. Compared to the linear method, the non-linear approach yields enhanced clustering properties and better separation of normal and abnormal tissues. ON the other hand, the linear transformation is more appropriate than the non-linear method for capturing partial volume information.

Soltanian-Zadeh, Hamid; Kharrat, Mahmood; Peck, Donald J.

2001-07-01

296

Characterizing Rotation in a Plasma MRI Experiment  

NASA Astrophysics Data System (ADS)

The Plasma Couette Experiment (PCX) is underway to investigate a nearly unmagnetized, differentially rotating plasma. A host of astrophysically motivated processes can be studied, including the magnetorotational instability (MRI), a mechanism that could account for the efficient angular momentum transport in accretion disks. Observation of MRI in a laboratory plasma would enhance our understanding of how accretion occurs in a variety of astrophysical objects, including planet and star forming systems, galactic nuclei, and black holes. Depending on plasma parameters, it may be possible to experimentally identify effects beyond ideal MHD in MRI theory. For example, the addition of the Hall term can lead to growth rates that depend on whether the magnetic field is parallel or anti-parallel to the rotation axis. In PCX, the plasma is confined by a cylindrical, axisymmetric, highly localized ring cusp magnetic field at the boundary. Electrodes are positioned between the magnet rings and biased with alternating polarity so that the resulting electric field induces azimuthal ExB drift. Density and temperature profiles are measured using a swept, single tip Langmuir probe. As plasma begins to rotate, the plasma density and potential are expected to hollow out, with the electron pressure gradient balancing the outward centrifugal force. To study plasma rotation, ion flow velocity and plasma potential are measured with Mach and emissive probes. Measurements of plasma characteristics will be presented, and the feasibility of observing the MRI will be discussed.

Collins, Cami; Forest, C.; Clark, M.; Wallace, J.

2010-05-01

297

MRI - Nobel Prize Educational Game  

NSDL National Science Digital Library

The MRI educational game is based on the 2003 Nobel Prize in Physiology or Medicine, which was awarded for discoveries concerning MRI - magnetic resonance imaging. A technique making it possible to get images of soft tissue inside the body.

2009-01-01

298

Low-grade and anaplastic oligodendrogliomas: differences in tumour microvascular permeability evaluated with dynamic contrast-enhanced magnetic resonance imaging.  

PubMed

This study was designed to quantitatively assess the microvascular permeability of oligodendroglioma using the volume transfer constant (K(trans)) and the volume of the extravascular extracellular space per unit volume of tissue (V(e)) with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). We aimed to evaluate the effectiveness of K(trans) and V(e) in distinguishing between low-grade and anaplastic oligodendroglioma. The maximal values of K(trans) and V(e) for 65 patients with oligodendroglioma (27 grade II, 38 grade III) were obtained. Differences in K(trans) and V(e) between the two groups were analysed using the Mann-Whitney rank-sum test. Receiver operating characteristic (ROC) curve analyses were performed to determine the cut-off values for the K(trans) and Ve that could differentiate between low-grade and anaplastic oligodendrogliomas. Values for K(trans) and Ve in low-grade oligodendrogliomas were significantly lower than those in anaplastic oligodendrogliomas (p < 0.001 and p < 0.001, respectively). ROC curve analysis showed that cut-off values of the K(trans) (0.037 min(-1)) and Ve (0.079) could be used to distinguish between low-grade and anaplastic oligodendrogliomas in a statistically significant manner. Our results suggest that DCE-MRI can distinguish the differences in microvascular permeability between low-grade and anaplastic oligodendrogliomas. PMID:23673143

Jia, Zhongzheng; Geng, Daoying; Liu, Ying; Chen, Xingrong; Zhang, Jun

2013-08-01

299

MRI in differentiation of benign and malignant tongue tumors.  

PubMed

The differential diagnosis of benign and malignant tongue tumors is crucial to treatment and prognosis. Magnetic resonance imaging (MRI) is the preferred modality for the evaluation of tongue carcinomas. Dynamic contrast-enhanced (DCE)-MRI can reflect the density, integrity, and leakiness of tumor vasculature, and the time-intensity curve (TIC) patterns derived from DCE-MRI results can differentiate benign from malignant tumors based on differences in vascular structure. Diffusion-weighted (DW)-MRI is based on the random thermal motion of water molecules and can provide information on the cellular and tissue microstructure of the tumor. A low apparent diffusion coefficient (ADC) derived from DW-MRIs may indicate a malignant tumor. Thus, ADC values and TIC parameters yield complementary information on tumors that may improve diagnostic accuracy. Indeed, the combination of DCE-MRI and DW-MRI is a comprehensive reflection of the pathological status of the tongue tumor, so utilization of these MRI modalities may facilitate the diagnostic differentiation of benign from malignant tumors of the tongue. PMID:25553468

Liu, Xinli; Cheng, Dongfeng; Wang, Wen

2015-01-01

300

Polarized noble gas MRI  

SciTech Connect

The development of convenient methods to polarize liter quantities of the noble gases helium-3 and xenon-129 has provided the opportunity for a new MRI method to visualize the internal air spaces of the human lung. These spaces are usually poorly seen with hydrogen-based MRI, because of the limited water content of the lung and the low thermal polarization of the water protons achieved in conventional magnets. In addition, xenon, which has a relatively high solubility and a sufficiently persistent polarization level in blood and biological tissue, offers the prospect of providing perfusion images of the lung, brain and other organs.

Brookeman, James R.; Mugler, John P. III; Lange, Eduard E. de; Knight-Scott, Jack; Maier, Therese [Department of Radiology, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908 (United States); Bogorad, Paul; Driehuys, Bastiaan; Cates, Gordon; Happer, William [Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States); Daniel, Thomas M. [Department of Surgery, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908 (United States); Truwit, Jonathon D. [Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908 (United States)

1998-01-20

301

Introduction Magnetic Resonance Imaging (MRI)  

E-print Network

Introduction Statistics Magnetic Resonance Imaging (MRI) Statistics in the UK Statistics at UCL and Beyond #12;Introduction Statistics Magnetic Resonance Imaging (MRI) Statistics in the UK Statistics Magnetic Resonance Imaging (MRI) Statistics in the UK Statistics at UCL Outline Why do Statistics? Some

Wirosoetisno, Djoko

302

Distinguishing quantum and classical transport through nanostructures  

E-print Network

We consider the question of how to distinguish quantum from classical transport through nanostructures. To address this issue we have derived two inequalities for temporal correlations in nonequilibrium transport in nanostructures weakly coupled to leads. The first inequality concerns local charge measurements and is of general validity; the second concerns the current flow through the device and is relevant for double quantum dots. Violation of either of these inequalities indicates that physics beyond that of a classical Markovian model is occurring in the nanostructure.

Neill Lambert; Clive Emary; Yueh-Nan Chen; Franco Nori

2010-02-16

303

Classification of cardiac-related artifacts in dynamic contrast breast MRI  

Microsoft Academic Search

Dynamic contrast breast MRI is becoming an important adjunct in screening women at high risk for breast cancer, determining extent of disease (staging) and monitoring response to therapy. In dynamic contrast breast MRI, regions of rapid contrast uptake indicate increases in vascularity which can be associated with abnormal tissue, sometimes significant for malignant disease. To show these areas of enhancement,

Keith C. Stegbauer; Justin P. Smith; Tanya L. Niemeyer; Chris Wood

2004-01-01

304

MRI driven magnetic microswimmers.  

PubMed

Capsule endoscopy is a promising technique for diagnosing diseases in the digestive system. Here we design and characterize a miniature swimming mechanism that uses the magnetic fields of the MRI for both propulsion and wireless powering of the capsule. Our method uses both the static and the radio frequency (RF) magnetic fields inherently available in MRI to generate a propulsive force. Our study focuses on the evaluation of the propulsive force for different swimming tails and experimental estimation of the parameters that influence its magnitude. We have found that an approximately 20 mm long, 5 mm wide swimming tail is capable of producing 0.21 mN propulsive force in water when driven by a 20 Hz signal providing 0.85 mW power and the tail located within the homogeneous field of a 3 T MRI scanner. We also analyze the parallel operation of the swimming mechanism and the scanner imaging. We characterize the size of artifacts caused by the propulsion system. We show that while the magnetic micro swimmer is propelling the capsule endoscope, the operator can locate the capsule on the image of an interventional scene without being obscured by significant artifacts. Although this swimming method does not scale down favorably, the high magnetic field of the MRI allows self propulsion speed on the order of several millimeter per second and can propel an endoscopic capsule in the stomach. PMID:22037673

Kósa, Gábor; Jakab, Péter; Székely, Gábor; Hata, Nobuhiko

2012-02-01

305

Making MRI quieter.  

PubMed

We have mitigated acoustic noise in a 1.5 T cylindrical MRI scanner equipped with epoxy-potted, shielded gradients. It has been widely assumed that MRI acoustic noise comes overwhelmingly from vibrations of the gradient assembly. However, with vibration-isolated gradients contained in an airtight enclosure, we found the primary sources of acoustic noise to be eddy-current-induced vibrations of metal structures such as the cryostat inner bore and the rf body coil. We have elucidated the relative strengths of source-pathways of acoustic noise and assembled a reduced-acoustic-noise demonstration MRI system. This scanner employed a number of acoustic noise reduction measures including a vacuum enclosure of a vibrationally isolated gradient assembly, a low-eddy-current rf coil and a non-conducting inner bore cryostat. The demonstration scanner reduced, by about 20 dBA, the acoustic noise levels in the patient bore to 85 dBA and below for several typical noisy pulse sequences. The noise level standing near the patient bore is 71 dBA and below. We have applied Statistical Energy Analysis to develop a vibroacoustic model of the MR system. Our model includes vibrational sources and acoustic pathways to predict acoustic noise and provides a good spectral match above 400 Hz to experimentally measured sound levels. This tool enables us to factor acoustics into the design parameters of new MRI systems. PMID:12034336

Edelstein, William A; Hedeen, Robert A; Mallozzi, Richard P; El-Hamamsy, Sayed Amr; Ackermann, Robert A; Havens, Timothy J

2002-02-01

306

MRI-guided breast interventions.  

PubMed

The use of breast magnetic resonance imaging (MRI) in the diagnosis, staging, and management of breast cancer is rapidly increasing. MRI has the ability to detect malignancy that is occult to physical exam, ultrasound, and mammography. These qualities necessitate methods for MRI-guided tissue sampling. This article reviews all previously published and currently accepted methods for MRI-guided tissue sampling. The data to support these techniques are provided where appropriate. A detailed technique for vacuum-assisted breast biopsy is included. We will also review the data on other MRI-guided breast interventions such as transcutaneous tissue ablation. PMID:16916002

Eby, Peter R; Lehman, Constance

2006-08-01

307

Automated localization of breast cancer in DCE-MRI.  

PubMed

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is increasingly being used for the detection and diagnosis of breast cancer. Compared to mammography, DCE-MRI provides higher sensitivity, however its specificity is variable. Moreover, DCE-MRI data analysis is time consuming and depends on reader expertise. The aim of this work is to propose a novel automated breast cancer localization system for DCE-MRI. Such a system can be used to support radiologists in DCE-MRI analysis by marking suspicious areas. The proposed method initially corrects for motion artifacts and segments the breast. Subsequently, blob and relative enhancement voxel features are used to locate lesion candidates. Finally, a malignancy score for each lesion candidate is obtained using region-based morphological and kinetic features computed on the segmented lesion candidate. We performed experiments to compare the use of different classifiers in the region classification stage and to study the effect of motion correction in the presented system. The performance of the algorithm was assessed using free-response operating characteristic (FROC) analysis. For this purpose, a dataset of 209 DCE-MRI studies was collected. It is composed of 95 DCE-MRI studies with 105 breast cancers (55 mass-like and 50 non-mass-like malignant lesions) and 114 DCE-MRI studies from women participating in a screening program which were diagnosed to be normal. At 4 false positives per normal case, 89% of the breast cancers (91% and 86% for mass-like and non-mass-like malignant lesions, respectively) were correctly detected. PMID:25532510

Gubern-Mérida, Albert; Martí, Robert; Melendez, Jaime; Hauth, Jakob L; Mann, Ritse M; Karssemeijer, Nico; Platel, Bram

2015-02-01

308

Item Memory, Context Memory and the Hippocampus: fMRI Evidence  

ERIC Educational Resources Information Center

Dual-process models of recognition memory distinguish between the retrieval of qualitative information about a prior event (recollection), and judgments of prior occurrence based on an acontextual sense of familiarity. fMRI studies investigating the neural correlates of memory encoding and retrieval conducted within the dual-process framework have…

Rugg, Michael D.; Vilberg, Kaia L.; Mattson, Julia T.; Yu, Sarah S.; Johnson, Jeffrey D.; Suzuki, Maki

2012-01-01

309

MRI of the Sacroiliac Joints in Patients with Moderate to Severe Ankylosing Spondylitis  

Microsoft Academic Search

OBJECTIVE. The objectives of our study were to evaluate whether MRI findings of the sacroiliac joints are able to distinguish between active and inactive disease in patients with es- tablished ankylosing spondylitis and to determine whether these findings correlate with mark- ers of clinical activity, disease duration, severity, and degree of radiographic damage. MATERIALS AND METHODS. Eighteen patients with symptomatic

Miriam A. Bredella; Lynne S. Steinbach; Stephanie Morgan; Michael Ward; John C. Davis; Bredella MA; Steinbach LS; Davis JC

310

Myelin and iron concentration in the human brain: a quantitative study of MRI contrast.  

PubMed

During the last five years ultra-high-field magnetic resonance imaging (MRI) has enabled an unprecedented view of living human brain. Brain tissue contrast in most MRI sequences is known to reflect mainly the spatial distributions of myelin and iron. These distributions have been shown to overlap significantly in many brain regions, especially in the cortex. It is of increasing interest to distinguish and identify cortical areas by their appearance in MRI, which has been shown to be feasible in vivo. Parcellation can benefit greatly from quantification of the independent contributions of iron and myelin to MRI contrast. Recent studies using susceptibility mapping claim to allow such a separation of the effects of myelin and iron in MRI. We show, using post-mortem human brain tissue, that this goal can be achieved. After MRI scanning of the block with appropriate T1 mapping and T2* weighted sequences, we section the block and apply a novel technique, proton induced X-ray emission (PIXE), to spatially map iron, phosphorus and sulfur elemental concentrations, simultaneously with 1?m spatial resolution. Because most brain phosphorus is located in myelin phospholipids, a calibration step utilizing element maps of sulfur enables semi-quantitative ex vivo mapping of myelin concentration. Combining results for iron and myelin concentration in a linear model, we have accurately modeled MRI tissue contrasts. Conversely, iron and myelin concentrations can now be estimated from appropriate MRI measurements in post-mortem brain samples. PMID:24607447

Stüber, Carsten; Morawski, Markus; Schäfer, Andreas; Labadie, Christian; Wähnert, Miriam; Leuze, Christoph; Streicher, Markus; Barapatre, Nirav; Reimann, Katja; Geyer, Stefan; Spemann, Daniel; Turner, Robert

2014-06-01

311

MRI features of ovarian cystic lesions.  

PubMed

The purpose of this article is to present the clinical and imaging features for the spectrum of ovarian cystic lesions, from benign to malignant and from tumorous to nontumorous. We review the imaging modalities for evaluating ovarian cystic lesions, especially magnetic resonance imaging (MRI) techniques. We present clinical and imaging features that can be used to help with the differential diagnosis of the spectrum of ovarian cystic lesions. We discuss the relevance of imaging features for distinguishing between benign and malignant ovarian cystic lesions. The characteristic clinical and imaging features of ovarian cystic lesions can provide criteria for making a diagnosis or substantially narrowing the differential diagnosis. Therefore, a careful assessment of ovarian cystic lesions is warranted. PMID:24474469

Park, Sung Bin; Lee, Jong Beum

2014-09-01

312

Markers of Cochlear Inflammation Using MRI  

PubMed Central

Purpose: To quantify spatial and temporal inflammation-induced changes in vascular permeability and macrophage infiltration in guinea-pig (GP) cochlea using MRI. Materials and Methods: GPs were injected with lipopolysaccharide (LPS) to induce cochlear inflammation. One group was injected with a gadolinium based contrast agent (GBCA) and dynamic contrast enhanced (DCE)-MRI was performed at 4, 7, and 10 days after LPS treatment. A two-compartment pharmacokinetic model was used to determine the apparent rate constant of GBCA extravasation (Ktrans). A second group was injected with ultrasmall superparamagnetic iron oxide particles (USPIOs) and studied at 2, 3, and 7 days after LPS treatment to detect tissue USPIO uptake and correlate with histology. For both groups, control GPs were scanned similarly. Results: The signal enhancement increased substantially and more rapidly at day 4 in LPS-treated than in control cochlea shortly following GBCA injection. Ktrans of LPS-treated cochlea was maximum on day 4 at 0.0218±0.0032 min?1 and then decreased to control level at 0.0036±0.0004 min?1 by day 10. In the second group, the relative signal intensity and T2 in cochlear perilymphatic spaces on day 2 decreased, on average, by 54% and 45%, respectively, compared with baseline and then remained under control levels by day 7. This suggests the infiltration of inflammatory cells, although unconfirmed by histology. Conclusion: This provides the first measurement of cochlear vascular permeability using MRI and a quantitative evaluation of the development of cochlear inflammation. MRI holds considerable potential for the assessment of disease processes such as clinical diagnosis of conditions such as labyrinthitis. PMID:23589173

Floc’h, Johann Le; Tan, Winston; Telang, Ravindra S.; Vlajkovic, Srdjan M.; Nuttall, Alfred; Rooney, William D.; Pontré, Beau; Thorne, Peter R.

2014-01-01

313

MRI findings of a middle ear cholesteatoma in a dog.  

PubMed

This article describes the MRI features of a middle ear cholesteatoma in an 8 yr old flat-coated retriever. Physical examination revealed pain on opening the jaw, and otoscopic examination showed tympanic membrane rupture associated with hyperplastic tissue at the entrance of the middle ear. Standard MRI sequences allowed for the identification of a severely expanded bulla containing material that was isointense to brain tissue on T1-weighted images and of mixed intensity on T2-weighted and fluid-attenuated inversion recovery sequences. No postcontrast enhancement of the content was present, but the lining of the bulla was partially enhanced. The images allowed evaluation of the surgical margins and the secondary changes due to the expansion of the mass. Surgery was performed and histopathology confirmed the presumptive diagnosis of cholesteatoma. In the present case, MRI appeared to serve as a good alternative to computed tomography for the diagnosis of cholesteatoma. PMID:22843826

Harran, Nathaniel X; Bradley, Kate J; Hetzel, Natasha; Bowlt, Kelly L; Day, Michael J; Barr, Frances

2012-01-01

314

10 CFR 1002.22 - Use of distinguishing flag.  

Code of Federal Regulations, 2010 CFR

...Energy DEPARTMENT OF ENERGY (GENERAL PROVISIONS...distinguishing flag. (a) DOE distinguishing flags...Chairman of the Federal Energy Regulatory Commission... (2) At official DOE ceremonies. (3...front of DOE installation buildings. (5) Other...

2010-01-01

315

University of Massachusetts: Distinguished Visitors Program  

NSDL National Science Digital Library

The University of Massachusetts at Amherst Library has an elaborate mix of digital collections available through their UMarmot program, which is the online presence of their Special Collections & University Archives division. One of the more recent digitization projects they have completed is the Distinguished Visitors Program. The Program contains talks from a wide range of visitors who came to Amherst in the 1970s. The talks here include lively conversations with Isaac Asimov, Julian Bond, Angela Davis, David Halberstam, Tom Hayden, and Jane Fonda. Visitors will also find a short description of each individual's talk, along with information about what brought him or her to campus. The talks are engaging; one of the best is the talk by David Halberstam, which features a discussion of American politics and foreign policy in the wake of Watergate.

2012-04-06

316

California Policy Should Distinguish Biofuels by Differential Global Warming Effects  

E-print Network

California Policy Should Distinguish Biofuels by Differential Global Warming Effects by Richard J: _______________________________________ Date #12;California Policy Should Distinguish Biofuels by Differential Global Warming Effects Richard J, 2006 #12;#12;ABSTRACT California Policy Should Distinguish Biofuels by Differential Global Warming

Kammen, Daniel M.

317

PSI CHI -UBC CHAPTER DISTINGUISHED UNDERGRADUATE RESEARCH AWARD (DURA)  

E-print Network

PSI CHI - UBC CHAPTER DISTINGUISHED UNDERGRADUATE RESEARCH AWARD (DURA) What is the Distinguished Undergraduate Research Award? The DURA is a competitive undergraduate award given by our chapter of Psi Chi on the UBC campus or in a UBC-related facility/program. What does the Distinguished Undergraduate Research

Handy, Todd C.

318

MRI of the penis  

PubMed Central

MRI of the penis is an expensive test that is not always superior to clinical examination or ultrasound. However, it shows many of the important structures, and in particular the combination of tumescence from intracavernosal alprostadil, and high-resolution T2 sequences show the glans, corpora and the tunica albuginea well. In this paper we summarise the radiological anatomy and discuss the indications for MRI. For penile cancer, it may be useful in cases where the local stage is not apparent clinically. In priapism, it is an emerging technique for assessing corporal viability, and in fracture it can in most cases make the diagnosis and locate the injury. In some cases of penile fibrosis and Peyronie's disease, it may aid surgical planning, and in complex pelvic fracture may replace or augment conventional urethrography. It is an excellent investigation for the malfunctioning penile prosthesis. PMID:23118102

Kirkham, A

2012-01-01

319

MRI of the penis.  

PubMed

MRI of the penis is an expensive test that is not always superior to clinical examination or ultrasound. However, it shows many of the important structures, and in particular the combination of tumescence from intracavernosal alprostadil, and high-resolution T(2) sequences show the glans, corpora and the tunica albuginea well. In this paper we summarise the radiological anatomy and discuss the indications for MRI. For penile cancer, it may be useful in cases where the local stage is not apparent clinically. In priapism, it is an emerging technique for assessing corporal viability, and in fracture it can in most cases make the diagnosis and locate the injury. In some cases of penile fibrosis and Peyronie's disease, it may aid surgical planning, and in complex pelvic fracture may replace or augment conventional urethrography. It is an excellent investigation for the malfunctioning penile prosthesis. PMID:23118102

Kirkham, A

2012-11-01

320

Eosinophilic granuloma: MRI manifestations.  

PubMed

The appearance on magnetic resonance imaging (MRI) of 16 cases of pathologically proven eosinophilic granuloma were reviewed retrospectively and correlated with the radiographic appearance of the lesion. The most common MR appearance (ten cases) was a focal lesion, surrounded by an extensive, ill-defined bone marrow and soft tissue reaction with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, considered to represent bone marrow and soft tissue edema (the flare phenomenon). The MRI manifestations of eosinophilic granuloma, especially during the early stages, are nonspecific, and may stimulate an aggressive lesion such as osteomyelitis or Ewings sarcoma, or other benign bone tumors such as osteoid osteoma or chondroblastoma. PMID:8480200

Beltran, J; Aparisi, F; Bonmati, L M; Rosenberg, Z S; Present, D; Steiner, G C

1993-01-01

321

Multivalent, High-Relaxivity MRI Contrast Agents Using Rigid Cysteine-Reactive Gadolinium Complexes  

PubMed Central

MRI contrast agents providing very high relaxivity values can be obtained through the attachment of multiple gadolinium(III) complexes to the interior surfaces of genome-free viral capsids. In previous studies, the contrast enhancement was predicted to depend on the rigidity of the linker attaching the MRI agents to the protein surface. To test this hypothesis, a new set of Gd-hydroxypyridonate based MRI agents was prepared and attached to genetically introduced cysteine residues through flexible and rigid linkers. Greater contrast enhancements were seen for MRI agents that were attached via rigid linkers, validating the design concept and outlining a path for future improvements of nanoscale MRI contrast agents. PMID:21800868

Garimella, Praveena D.; Datta, Ankona; Romanini, Dante W.; Raymond, Kenneth N.; Francis, Matthew B.

2011-01-01

322

Wilson's disease: MRI features  

PubMed Central

A 15-year-old boy presented with coarse tremors of right hand and dysarthric speech. Neurologic examination demonstrated Kayser-Fleischer rings and dystonic tremor of the right hand. Serum ceruloplasmin and urine copper studies established the diagnosis of Wilson's disease. Brain MRI showed bilateral T2 hyperintensity involving putamen, thalami, and brainstem. Involvement of brainstem revealed the characteristic “double panda sign.” PMID:21977083

Singh, Paramdeep; Ahluwalia, Archana; Saggar, Kavita; Grewal, Charanpreet Singh

2011-01-01

323

Occupational exposure in MRI  

PubMed Central

This article reviews occupational exposure in clinical MRI; it specifically considers units of exposure, basic physical interactions, health effects, guideline limits, dosimetry, results of exposure surveys, calculation of induced fields and the status of the European Physical Agents Directive. Electromagnetic field exposure in MRI from the static field B0, imaging gradients and radiofrequency transmission fields induces electric fields and currents in tissue, which are responsible for various acute sensory effects. The underlying theory and its application to the formulation of incident and induced field limits are presented. The recent International Commission on Non-Ionizing Radiation Protection (ICNIRP) Bundesministerium für Arbeit und Soziales and Institute of Electrical and Electronics Engineers limits for incident field exposure are interpreted in a manner applicable to MRI. Field measurements show that exposure from movement within the B0 fringe field can exceed ICNIRP reference levels within 0.5 m of the bore entrance. Rate of change of field dB/dt from the imaging gradients is unlikely to exceed the new limits, although incident field limits can be exceeded for radiofrequency (RF) exposure within 0.2–0.5 m of the bore entrance. Dosimetric surveys of routine clinical practice show that staff are exposed to peak values of 42±24% of B0, with time-averaged exposures of 5.2±2.8 mT for magnets in the range 0.6–4 T. Exposure to time-varying fields arising from movement within the B0 fringe resulted in peak dB/dt of approximately 2 T s?1. Modelling of induced electric fields from the imaging gradients shows that ICNIRP-induced field limits are unlikely to be exceeded in most situations; however, movement through the static field may still present a problem. The likely application of the limits is discussed with respect to the reformulation of the European Union (EU) directive and its possible implications for MRI. PMID:22457400

Mcrobbie, D W

2012-01-01

324

MRI anatomy of schizophrenia  

Microsoft Academic Search

Structural magnetic resonance imaging (MRI) data have provided much evidence in support of our current view that schizophrenia is a brain disorder with altered brain structure, and consequently involving more than a simple disturbance in neurotransmission. This review surveys 118 peer–reviewed studies with control group from 1987 to May 1998.Most studies (81%) do not find abnormalities of whole brain\\/intracranial contents,

Robert W. McCarley; Cynthia G. Wible; Melissa Frumin; Yoshio Hirayasu; James J. Levitt; Iris A. Fischer; Martha E. Shenton

1999-01-01

325

MRI of intact plants  

Microsoft Academic Search

Nuclear magnetic resonance imaging (MRI) is a non-destructive and non-invasive technique that can be used to acquire two-\\u000a or even three-dimensional images of intact plants. The information within the images can be manipulated and used to study\\u000a the dynamics of plant water relations and water transport in the stem, e.g., as a function of environmental (stress) conditions.\\u000a Non-spatially resolved portable

Henk Van As; T. W. J. Scheenen; Frank J. Vergeldt

2009-01-01

326

Tailgut cysts: MRI findings  

Microsoft Academic Search

Magnetic resonance imaging (MRI) features of 11 surgically resected pelvic tailgut cysts were analyzed with reference to histopathologic\\u000a and clinical data. Homogeneity, size, location, signal intensity, appearance and presence of septa and\\/or nodules and\\/or peripheral\\u000a rim and involvement of surrounding structures were studied. Histological examination demonstrated 11 tailgut cysts (TGC),\\u000a including one infected TGC and one TGC with a component

V. Aflalo-Hazan; P. Rousset; N. Mourra; M. Lewin; L. Azizi; C. Hoeffel

2008-01-01

327

MRI (Magnetic Resonance Imaging) : tour an MRI machine  

NSDL National Science Digital Library

In this resource, appropriate for students in high school and beyond, the user navigates through a five-page illustrated explanation of MRI (magnetic resonance imaging). Each page profiles a different step in the MRI process. The resource addresses the science behind how MRI works, revealing how a strong magnet and radio wave pulses affect the targeted area of the body and allow that area to be imaged. As part of a set of materials about brain scanning technologies, this resource focuses on brain MRI. Copyright 2005 Eisenhower National Clearinghouse

David Grubin Productions

2001-01-01

328

Prostate cancer magnetic resonance imaging (MRI): multidisciplinary standpoint  

PubMed Central

Prostate cancer is the most common cancer diagnosed in men and a leading cause of death. Accurate assessment is a prerequisite for optimal clinical management and therapy selection of prostate cancer. There are several parameters and nomograms to differentiate between patients with clinically insignificant disease and patients in need of treatment. Magnetic resonance imaging (MRI) is a technique which provides more detailed anatomical images due to high spatial resolution, superior contrast resolution, and multiplanar capability. State-of-the-art MRI techniques, such as diffusion weighted imaging (DWI), MR spectroscopic imaging (MRSI), dynamic contrast enhanced MRI (DCE-MRI), improve interpretation of prostate cancer imaging. In this article, we review the major role of MRI in the advanced management of prostate cancer to noninvasively improve tumor staging, biologic potential, treatment planning, therapy response, local recurrence, and to guide target biopsy for clinical suspected cancer with previous negative biopsy. Finally, future challenges and opportunities in prostate cancer management in the area of functional MRI are discussed as well. PMID:23630657

Li, Liang; Feng, Zhaoyan; Hu, Zhiquan; Wang, Guoping; Yuan, Xianglin; Wang, He; Hu, Daoyu

2013-01-01

329

Head and neck MRI of Kimura disease  

PubMed Central

Objectives The purpose of our study was to describe the MR appearance of Kimura disease and to interpret the differences in appearance from malignant parotid gland tumours. Methods MR studies of seven patients with Kimura disease were reviewed. The MR studies included T1 weighted, T2 weighted, short tau inversion-recovery, diffusion-weighted (DW) and dynamic contrast-enhanced imaging. Results Typical Kimura disease featured subcutaneous lesions, continuously infiltrated parotid lesions from the subcutaneous lesions with or without intraparotid lymphadenopathies, and reactive cervical lymphadenopathies. The subcutaneous lesions showed gradual upward enhancement on dynamic contrast-enhanced MR images. Reactive lymph nodes showed early enhancement on contrast-enhanced MR images and marked high intensity and low apparent diffusion coefficient values on DW images. Conclusion An indication for making the diagnosis of Kimura disease should be the subcutaneous tissue of the head and neck showing gradual upward enhancement on dynamic contrast-enhanced MRI and a lack of high intensity on DW images, associated with reactive lymph nodes. PMID:21849365

Horikoshi, T; Motoori, K; Ueda, T; Shimofusa, R; Hanazawa, T; Okamoto, Y; Ito, H

2011-01-01

330

Functional MRI of the kidneys  

PubMed Central

Renal function is characterized by different physiologic aspects, including perfusion, glomerular filtration, interstitial diffusion and tissue oxygenation. MRI shows great promise in assessing these renal tissue characteristics noninvasively. The last decade has witnessed a dramatic progress in MRI techniques for renal function assessment. This article briefly describes relevant renal anatomy and physiology, reviews the applications of functional MRI techniques for the diagnosis of renal diseases, and lists unresolved issues that will require future work. PMID:23355431

Zhang, Jeff L.; Rusinek, Henry; Chandarana, Hersh; Lee, Vivian S.

2012-01-01

331

MRI in neuro-Behçet's disease  

Microsoft Academic Search

Our purpose was to characterise specific MRI findings and to determine their value in neuro-Behet's disease. We examined\\u000a 17 patients (14 men, 3 women) with neuro-Behet's disease using T1- and T2-weighted spin-echo images and contrast-enhanced\\u000a images at 0.5 T. There were 13 patients (76.5 %) who had single or multiple lesions. Most of these were in the basal ganglia,\\u000a brain

E. T. Tal?; S. Atilla; T. Keskin; T. Simonson; S. I?ik; W. T. C. Yuh

1997-01-01

332

Distinguishing Modified Gravity from Dark Energy  

E-print Network

The acceleration of the universe can be explained either through dark energy or through the modification of gravity on large scales. In this paper we investigate modified gravity models and compare their observable predictions with dark energy models. Modifications of general relativity are expected to be scale-independent on super-horizon scales and scale-dependent on sub-horizon scales. For scale-independent modifications, utilizing the conservation of the curvature scalar and a parameterized post-Newtonian formulation of cosmological perturbations, we derive results for large scale structure growth, weak gravitational lensing, and cosmic microwave background anisotropy. For scale-dependent modifications, inspired by recent $f(R)$ theories we introduce a parameterization for the gravitational coupling $G$ and the post-Newtonian parameter $\\gamma$. These parameterizations provide a convenient formalism for testing general relativity. However, we find that if dark energy is generalized to include both entropy and shear stress perturbations, and the dynamics of dark energy is unknown a priori, then modified gravity cannot in general be distinguished from dark energy using cosmological linear perturbations.

Edmund Bertschinger; Phillip Zukin

2008-01-16

333

Distinguishability and agreement with continuous data.  

PubMed

The analysis of concordance among repeated measures has received a huge amount of attention in the statistical literature leading to a range of different approaches. However, because all the approaches are able to assess the closeness among the readings taken on the same subject, the conclusions about the degree of concordance should be similar regardless the approach applied. Here, two indices to assess the concordance among continuous repeated measures, the intraclass correlation coefficient and the total deviation index, are applied and compared in two case examples. The first example concerns the repeatability of individual nutrient allocation strategy assessed by stable isotope analysis. The second example dealt with the assessment of the concordance of functional magnetic resonance imaging data that shows spatial correlation. The results differ depending upon the approach applied leading to contradictory conclusions about the degree of concordance. The reason behind these results is discussed reaching the conclusion that the total deviation index is just assessing agreement among repeated measurements, whereas the intraclass correlation coefficient assesses the concept of distinguishability among subjects that involves agreement among repeated measurements and spread of subjects at once. Therefore, the best way to select the right approach is to understand the right question behind the research hypothesis. PMID:23825013

Carrasco, Josep L; Caceres, Alejandro; Escaramis, Georgia; Jover, Lluis

2014-01-15

334

Cognitive Enhancement, Cheating, and Accomplishment  

Microsoft Academic Search

An ethics of enhancement should not rest on blanket judgments; it should ask us to distinguish between the kinds of activities we want to enhance. Both students and academics have turned to cognition-enhancing drugs in significant numbers—but is their enhancement a form of cheating? The answer should hinge on whether the activity subject to enhancement is zero-sum or non-zero-sum, and

Rob Goodman

2010-01-01

335

Reduction of boundary effects in spiral MRI experiment PROMISE  

E-print Network

Magnetorotational instability (MRI) is one of the most important and most common instabilities in astrophysics, it is widely accepted that it serves as a source of turbulent viscosity in accretion disks -- the most energy efficient objects in the Universe. However it is very difficult to bring this process down on earth and model it in a laboratory experiment. Several different approaches have been proposed, one of the most recent is PROMISE (Potsdam-ROssendorf Magnetorotational InStability Experiment). It consists of a flow of a liquid metal between two rotating cylinders under applied current-free spiral magnetic field. The cylinders must be covered with plates which introduce additional end-effects which alter the flow and make it more difficult to clearly distinguish between MRI stable and unstable state. In this paper we propose simple and inexpensive improvement to the PROMISE experiment which would reduce those undesirable effects.

J. Szklarski

2007-04-18

336

Hyperpolarized Xenon for NMR and MRI Applications  

PubMed Central

Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 T generate only a small detectable net-magnetization of the sample at room temperature 1. Hence, most NMR and MRI applications rely on the detection of molecules at relative high concentration (e.g., water for imaging of biological tissue) or require excessive acquisition times. This limits our ability to exploit the very useful molecular specificity of NMR signals for many biochemical and medical applications. However, novel approaches have emerged in the past few years: Manipulation of the detected spin species prior to detection inside the NMR/MRI magnet can dramatically increase the magnetization and therefore allows detection of molecules at much lower concentration 2. Here, we present a method for polarization of a xenon gas mixture (2-5% Xe, 10% N2, He balance) in a compact setup with a ca. 16000-fold signal enhancement. Modern line-narrowed diode lasers allow efficient polarization 7 and immediate use of gas mixture even if the noble gas is not separated from the other components. The SEOP apparatus is explained and determination of the achieved spin polarization is demonstrated for performance control of the method. The hyperpolarized gas can be used for void space imaging, including gas flow imaging or diffusion studies at the interfaces with other materials 8,9. Moreover, the Xe NMR signal is extremely sensitive to its molecular environment 6. This enables the option to use it as an NMR/MRI contrast agent when dissolved in aqueous solution with functionalized molecular hosts that temporarily trap the gas 10,11. Direct detection and high-sensitivity indirect detection of such constructs is demonstrated in both spectroscopic and imaging mode. PMID:22986346

Witte, Christopher; Kunth, Martin; Döpfert, Jörg; Rossella, Federica; Schröder, Leif

2012-01-01

337

CT and MRI Findings of Hepatic Involvement in Rendu-Osler-Weber Disease  

PubMed Central

Rendu-Osler-Weber disease is a rare autosomal dominant disorder. Hepatic involvement manifests itself as vascular, parenchymal, and biliary lesions with characteristic telangiectasias and vascular shunts. In a 37-year-old female patient, dynamic contrast-enhanced upper abdominal CT and MRI were performed. CT and MRI revealed dilated celiac trunk and hepatic artery. On early arterial phase, dilated hepatic veins showed significant enhancement. On arterial and portal venous phases, liver showed significantly heterogeneous contrast enhancement and showed homogenous enhancement in the hepatic parenchymal phase. On the magnetic resonance cholangiopancreatography, irregular biliary ducts with strictures and dilatation were seen. PMID:23198241

Bilgin, Mehmet; Yildiz, Seyma; Toprak, Huseyin; Ahmad, Issam Cheikh; Kocakoc, Ercan

2012-01-01

338

RF HEATING OF MRI-ASSISTED CATHETER STEERING COILS FOR INTERVENTIONAL MRI  

PubMed Central

RATIONALE AND OBJECTIVES To assess magnetic resonance imaging (MRI) radiofrequency (RF) related heating of conductive wire coils used in magnetically steerable endovascular catheters. MATERIALS AND METHODS A 3-axis microcoil was fabricated onto a 1.8 Fr catheter tip. In vitro testing was performed in a 1.5 T MRI system using an agarose gel filled vessel phantom, a transmit/receive body RF coil and a steady state free precession (SSFP) pulse sequence, and a fluoroptic thermometry system. Temperature was measured without simulated blood flow at varying distances from magnet isocenter and varying flip angles. Additional experiments were performed with laser-lithographed single-axis microcoil-tipped microcatheters in air and in a saline bath with varied grounding of the microcoil wires. Preliminary in vivo evaluation of RF heating was performed in pigs at 1.5 T with coil-tipped catheters in various positions in the common carotid arteries with SSFP pulse sequence on and off, and under physiologic flow and zero flow conditions. RESULTS In tissue-mimicking agarose gel, RF heating resulted in a maximal temperature increase of 0.35°C after 15 minutes of imaging, 15 cm from magnet isocenter. For a single axis microcoil, maximal temperature increases were 0.73-1.91°C in air and 0.45-0.55°C in saline. In vivo, delayed contrast enhanced MRI revealed no evidence of vascular injury and histopathological sections from the common carotid arteries confirmed the lack of vascular damage. CONCLUSIONS Microcatheter tip microcoils for endovascular catheter steering in MRI experience minimal RF heating under the conditions tested. These data provide the basis for further in vivo testing of this promising technology for endovascular interventional MRI. PMID:21075019

Settecase, Fabio; Hetts, Steven W.; Martin, Alastair J.; Roberts, Timothy P. L.; Bernhardt, Anthony F.; Evans, Lee; Malba, Vincent; Saeed, Maythem; Arenson, Ronald L.; Kucharzyk, Walter; Wilson, Mark W.

2010-01-01

339

LDRD 149045 final report distinguishing documents.  

SciTech Connect

This LDRD 149045 final report describes work that Sandians Scott A. Mitchell, Randall Laviolette, Shawn Martin, Warren Davis, Cindy Philips and Danny Dunlavy performed in 2010. Prof. Afra Zomorodian provided insight. This was a small late-start LDRD. Several other ongoing efforts were leveraged, including the Networks Grand Challenge LDRD, and the Computational Topology CSRF project, and the some of the leveraged work is described here. We proposed a sentence mining technique that exploited both the distribution and the order of parts-of-speech (POS) in sentences in English language documents. The ultimate goal was to be able to discover 'call-to-action' framing documents hidden within a corpus of mostly expository documents, even if the documents were all on the same topic and used the same vocabulary. Using POS was novel. We also took a novel approach to analyzing POS. We used the hypothesis that English follows a dynamical system and the POS are trajectories from one state to another. We analyzed the sequences of POS using support vector machines and the cycles of POS using computational homology. We discovered that the POS were a very weak signal and did not support our hypothesis well. Our original goal appeared to be unobtainable with our original approach. We turned our attention to study an aspect of a more traditional approach to distinguishing documents. Latent Dirichlet Allocation (LDA) turns documents into bags-of-words then into mixture-model points. A distance function is used to cluster groups of points to discover relatedness between documents. We performed a geometric and algebraic analysis of the most popular distance functions and made some significant and surprising discoveries, described in a separate technical report.

Mitchell, Scott A.

2010-09-01

340

Distinguishing dynamical dark matter at the LHC  

NASA Astrophysics Data System (ADS)

Dynamical dark matter (DDM) is a new framework for dark-matter physics in which the dark sector comprises an ensemble of individual component fields which collectively conspire to act in ways that transcend those normally associated with dark matter. Because of its nontrivial structure, this DDM ensemble—unlike most traditional dark-matter candidates—cannot be characterized in terms of a single mass, decay width, or set of scattering cross sections, but must instead be described by parameters which describe the collective behavior of its constituents. Likewise, the components of such an ensemble need not be stable so long as lifetimes are balanced against cosmological abundances across the ensemble as a whole. In this paper, we investigate the prospects for identifying a DDM ensemble at the LHC and for distinguishing such a dark-matter candidate from the candidates characteristic of traditional dark-matter models. In particular, we focus on DDM scenarios in which the component fields of the ensemble are produced at colliders alongside some number of standard-model particles via the decays of additional heavy fields. The invariant-mass distributions of these standard-model particles turn out to possess several unique features that cannot be replicated in most traditional dark-matter models. We demonstrate that in many situations it is possible to differentiate between a DDM ensemble and a traditional dark-matter candidate on the basis of such distributions. Moreover, many of our results also apply more generally to a variety of other extensions of the standard model which involve multiple stable or metastable neutral particles.

Dienes, Keith R.; Su, Shufang; Thomas, Brooks

2012-09-01

341

Multiple Nodular lesions In Spleen Associated With Visceral Leishmaniasis: A Case Report of MRI-Findings.  

PubMed

The spleen is one of the most commonly involved organs of visceral leishmaniasis (VL). However, there were few reports about imaging findings of splenic leishmaniasis, especially regarding MRI findings.This case report describes a 45 years old male patient from Zhejiang province of southeastern China, who was admitted for persistent fever of unknown origin, with splenomegaly and multiple hypodense/low echo nodules on CT/ultrasonography (USG) studies. MRI showed multiple nodules with concentric rings in the spleen on T2-weighted imaging (T2WI), with no obvious diffusion restriction on diffusion weighted imaging (DWI), and gradual ring-like enhancement after intravenous administration of contrast medium. So MRI suggested necrotic granulomatous lesion. By reviewing the clinical history and following positive serological leishmania antibody test, the patient was finally confirmed a recent infection with VL.The patient received antimony gluconate therapy intravenously.At 4 months follow-up, the contrast-enhanced abdominal MRI showed that the size of the spleen was returned to normal and the splenic lesions were completely resolved except for reduced infarction compared with the previous MRI.This is the first case which was performed MRI examination completely. Meanwhile, it is the second case which MRI findings were reported. As for the characteristics of MRI in this case, there are several features, which are helpful for giving the diagnosis and differential diagnosis of VL. PMID:25546669

Mao, Guoqun; Yang, Guangzhao; Cheng, Yougen; Zee, Chi S; Huang, Wenmin; Ni, Weiyang; Meng, Guanmin; Chen, Zhilu

2014-12-01

342

Nanoformulations for molecular MRI  

PubMed Central

Nanoscale contrast agents have shown the ability to increase the detection sensitivity of MRI by several orders of magnitude, endowing this traditionally macroscopic modality with the ability to observe unique molecular signatures. Herein, we describe three types of nanoparticulate contrast agents: iron oxide nanoparticles, gadolinium-based nanoparticles, and bio-essential manganese, cobalt, nickel, and copper ion-containing nanoformulations. Some of these agents have been approved for clinical use, but more are still under development for medical imaging. The advantages and disadvantages of each nanoformulation, in terms of intrinsic magnetism, ease of synthesis, and biodistribution, etc. are discussed. PMID:22488901

Tu, Chuqiao; Louie, Angelique Y.

2012-01-01

343

Self-regulation of human brain activity using simultaneous real-time fMRI and EEG neurofeedback.  

PubMed

Neurofeedback is a promising approach for non-invasive modulation of human brain activity with applications for treatment of mental disorders and enhancement of brain performance. Neurofeedback techniques are commonly based on either electroencephalography (EEG) or real-time functional magnetic resonance imaging (rtfMRI). Advances in simultaneous EEG-fMRI have made it possible to combine the two approaches. Here we report the first implementation of simultaneous multimodal rtfMRI and EEG neurofeedback (rtfMRI-EEG-nf). It is based on a novel system for real-time integration of simultaneous rtfMRI and EEG data streams. We applied the rtfMRI-EEG-nf to training of emotional self-regulation in healthy subjects performing a positive emotion induction task based on retrieval of happy autobiographical memories. The participants were able to simultaneously regulate their BOLD fMRI activation in the left amygdala and frontal EEG power asymmetry in the high-beta band using the rtfMRI-EEG-nf. Our proof-of-concept results demonstrate the feasibility of simultaneous self-regulation of both hemodynamic (rtfMRI) and electrophysiological (EEG) activities of the human brain. They suggest potential applications of rtfMRI-EEG-nf in the development of novel cognitive neuroscience research paradigms and enhanced cognitive therapeutic approaches for major neuropsychiatric disorders, particularly depression. PMID:23668969

Zotev, Vadim; Phillips, Raquel; Yuan, Han; Misaki, Masaya; Bodurka, Jerzy

2014-01-15

344

Primary epiploic appendagitis: MRI findings  

Microsoft Academic Search

Primary epiploic appendagitis (PEA) occurs secondary to inflammation of an epiploic appendage, and is considered to be a rare cause of acute abdomen. In this case report, we describe the magnetic resonance imaging (MRI) findings of PEA correlated with computed tomographic (CT) findings. MRI findings included an oval shaped fat intensity mass with a central dot on T1- and T2-weighted

Mustafa ?irvanci; N. Cem Balci; Kutlay Karaman; Cihan Duran; Ercan Karaka?

2002-01-01

345

MRI-based morphometric characterizations of sexual dimorphism of the cerebrum of ferrets (Mustela putorius).  

PubMed

The present study aimed to characterize cerebral morphology in young adult ferrets and its sexual dimorphism using high-field MRI and MRI-based morphometry. Ex vivo short TR/TE (typical T1-weighted parameter setting for conventional MRI) and T2W (long TR/TE) MRI with high spatial resolution at 7-tesla could visualize major subcortical and archicortical structures, i.e., the caudate nucleus, lentiform nucleus, amygdala and hippocampus. In particular, laminar organization of the olfactory bulb was identifiable by short TR/TE-MRI. The primary and secondary sulci observable in the adult ferret were distinguishable on either short TR/TE- or T2W-MRI, and the cortical surface morphology was reproduced well by 3D-rendered images obtained by short TR/TE-MRI. The cerebrum had a significantly lower volume in females than in males, which was attributed to region-specific volume reduction in the cerebral cortex and subcortical white matter in females. A sexual difference was also detected, manifested by an overall reduction in normalized signal ratios of short TR/TE-MRI in all cerebral structures examined in females than in males. On the other hand, an alternating array of higher and lower short TR/TE-MRI intensity transverse zones throughout the cortex, which was reminiscent of the functional cortical areas, was revealed by maximum intensity projection (MIP) in 3D. The normalized signal ratio of short TR/TE-MRI, but not T2W-MRI in the cortex, was negatively correlated with the density of myelin-basic protein immunoreactive fibers (males, r=-0.440; females, r=-0.481). The present results suggest that sexual differences in the adult ferret cerebrum are characterized by reduced volumes of the cerebral cortex and subcortical white matter in females, and by overall reductions in physiochemical characteristics, as obtained by short TR/TE-MRI, in females. It should be noted that short TR/TE-MRI-based MIP delineated functional cortical areas related to myeloarchitecture in 3D. Such an approach makes possible conventional investigation of the functional organization of the cerebral cortex and its abnormalities using high-field MRI. PMID:23770407

Sawada, Kazuhiko; Horiuchi-Hirose, Miwa; Saito, Shigeyoshi; Aoki, Ichio

2013-12-01

346

[MRI symptomatology of primary intraspinal cord gliomas].  

PubMed

MRI has now been recognized as the best technique for exploration of spinal tumours and, in particular, tumours within the spinal cord. Based on a retrospective study of 74 operated glial tumours, we are trying to define a specific semiology for intramedullary astrocytomas and ependymomas. Thirty-four cases were selected including 17 astrocytomas (7 low-grade, 10 high-grade) and 17 ependymomas (1 of which was grade III) for whom the pre-operative MRI examination was complete, with T1-weighted sequences without, then with gadolinium, and T2-weighted sequences. The examination was performed using a high-field and in most cases 1.5 Tesla machine. Analysis, correlated with operative data and pathology results, comprised on the one hand patients' distribution by age, sex and location of the tumour on the spinal cord, and on the other hand the MRI semiology concerning the sagittal and axial localization of the fleshy portion after gadolinium injection, the limits of the tumour, the homo- or heterogeneous character of its enhancement, the possible existence of stigmas of intra- or peritumoral chronic bleeding, and finally the presence or absence of associated cysts in the 34 exploitable cases. Some semiological differences were elicited between astrocytomas and ependymomas: the patient's age at the time of diagnosis was predominantly 0 to 20 for astrocytomas (astrocytomas 39%, ependymomas 4%), and the well-limited character of the fleshy portion of the tumour after gadolinium injection was found in 70% of ependymomas, 40% of high-grade astrocytomas and 14% of low-grade astrocytomas. The homogeneity of contrast enhancement in ependymomas has been classically defined, but it did not show in our series. Finally, it seems that high-grade astrocytomas are characterized by the rare presence of hemosiderin deposits (high-grade 20%, low-grade 57%, ependymomas 58%) and by the absence or reduced extension of overlying and underlying cysts. PMID:7707132

Joubert, E; Idir, A B; Carlier, R; Belal, N; Hurth, M; Lacroix-Ciaudo, C; Ducot, B; Doyon, D

1995-03-01

347

Natural D-Glucose as a biodegradable MRI contrast agent for detecting cancer  

PubMed Central

Purpose Modern imaging technologies such as CT, PET, SPECT, and MRI employ contrast agents to visualize the tumor microenvironment, providing information on malignancy and response to treatment. Currently, all clinical imaging agents require chemical labeling, i.e. with iodine (CT), radioisotopes (PET/SPECT), or paramagnetic metals (MRI). The goal was to explore the possibility of using simple D-glucose as an infusable biodegradable MRI agent for cancer detection. Methods D-glucose signals were detected using chemical exchange saturation transfer (glucoCEST) MRI of its hydroxyl groups. Feasibility was established in phantoms as well as in vivo using two human breast cancer cell lines, MDA-MB-231 and MCF-7, implanted orthotopically in nude mice. PET and contrast-enhanced MRI were also acquired. Results Both tumor types exhibited significant glucoCEST signal enhancement during systemic sugar infusion (mild hyperglycemia), allowing their noninvasive visualization. GlucoCEST showed differences between types, while PET and CE-MRI did not. Data are discussed in terms of signal contributions from the increased vascular volume in tumors and especially from the acidic extracellular extravascular space (EES), where glucoCEST signal is expected to be enhanced due to a slow-down of hydroxyl proton exchange. Conclusions This observation opens up the possibility for using simple non-toxic sugars as contrast agents for cancer detection with MRI by employing hydroxyl protons as a natural label. PMID:23074027

Chan, Kannie W. Y.; McMahon, Michael T.; Kato, Yoshinori; Liu, Guanshu; Bulte, Jeff W.M.; Bhujwalla, Zaver M.; Artemov, Dmitri; van Zijl, Peter C. M.

2012-01-01

348

MRI breast screening in high-risk women: cancer detection and survival analysis.  

PubMed

Women with a genetic predisposition to breast cancer tend to develop the disease at a younger age with denser breasts making mammography screening less effective. The introduction of magnetic resonance imaging (MRI) for familial breast cancer screening programs in recent years was intended to improve outcomes in these women. We aimed to assess whether introduction of MRI surveillance improves 5- and 10-year survival of high-risk women and determine the accuracy of MRI breast cancer detection compared with mammography-only or no enhanced surveillance and compare size and pathology of cancers detected in women screened with MRI + mammography and mammography only. We used data from two prospective studies where asymptomatic women with a very high breast cancer risk were screened by either mammography alone or with MRI also compared with BRCA1/2 carriers with no intensive surveillance. 63 cancers were detected in women receiving MRI + mammography and 76 in women receiving mammography only. Sensitivity of MRI + mammography was 93 % with 63 % specificity. Fewer cancers detected on MRI were lymph node positive compared to mammography/no additional screening. There were no differences in 10-year survival between the MRI + mammography and mammography-only groups, but survival was significantly higher in the MRI-screened group (95.3 %) compared to no intensive screening (73.7 %; p = 0.002). There were no deaths among the 21 BRCA2 carriers receiving MRI. There appears to be benefit from screening with MRI, particularly in BRCA2 carriers. Extended follow-up of larger numbers of high-risk women is required to assess long-term survival. PMID:24687378

Evans, D Gareth; Gareth, Evans D; Kesavan, Nisha; Nisha, Kesavan; Lim, Yit; Yit, Lim; Gadde, Soujanye; Soujanye, Gadde; Hurley, Emma; Emma, Hurley; Massat, Nathalie J; Maxwell, Anthony J; Ingham, Sarah; Sarah, Ingham; Eeles, Rosalind; Rosalind, Eeles; Leach, Martin O; Howell, Anthony; Anthony, Howell; Duffy, Stephen W; Stephen, Duffy

2014-06-01

349

Cyclic generalized projection MRI.  

PubMed

Progress in the development of portable MRI hinges on the ability to use lightweight magnets that have non-uniform magnetic fields. An image encoding method and mathematical procedure for recovering the image from the NMR signal from non-uniform magnets with closed isomagnetic contours is given. Individual frequencies in an NMR signal from an object in a non-uniform magnetic field give rise to integrals of the object along contours of constant magnetic field: generalized projections. With closed isomagnetic field contours a simple, cyclic, direct reconstruction of the image from the generalized projections is possible when the magnet and RF transmit coil are held fixed relative to the imaged object while the RF receive coil moves. Numerical simulations, using the Shepp and Logan mathematical phantom, were completed to show that the mathematical method works and to illustrate numerical limitations. The method is numerically verified and exact reconstruction demonstrated for discrete mathematical image phantoms. Correct knowledge of the RF receive field is necessary or severe image distortions will result. The cyclic mathematical reconstruction method presented here will be useful for portable MRI schemes that use non-uniform magnets with closed isomagnetic contours along with mechanically or electronically moving the RF receive coils. PMID:25532468

Sarty, Gordon E

2015-04-01

350

INGRID SPEAKER MEDAL FOR DISTINGUISHED RESEARCH, SCHOLARSHIP, OR PERFORMANCE ENDOWMENT  

E-print Network

INGRID SPEAKER MEDAL FOR DISTINGUISHED RESEARCH, SCHOLARSHIP, OR PERFORMANCE ENDOWMENT The Ingrid agreement with the University. Terms of Reference The Ingrid Speaker Medal Endowment is an endowment fund

Morris, Joy

351

MRI in necrotizing fasciitis of the extremities  

PubMed Central

Necrotizing fasciitis is a life-threatening soft-tissue infection of bacterial origin, which involves mainly the deep fascia. Early recognition of this condition may be hampered by the uncommon nature of the disease and non-specificity of initial clinical signs and symptoms in less fulminant cases, making the role of imaging important. MRI is the most useful imaging modality in the diagnosis of necrotizing fasciitis. The presence of thick (>3?mm) hyperintense signal in the deep fascia (particularly intermuscular fascia) on fat-suppressed T2 weighted or short tau inversion–recovery images is an important marker for necrotizing fasciitis. Contrast enhancement of the thickened necrotic fascia can be variable, with a mixed-pattern of enhancement being more commonly encountered. Involvement of multiple musculofascial compartments increases the likelihood of necrotizing fasciitis. It is important to remember that T2-hyperintense signal in the deep fascia is not specific to necrotizing fasciitis and can also be seen in cases such as non-infective inflammatory fasciitis or muscle tear. In this pictorial essay, we aim to review the MRI findings in necrotizing fasciitis, discuss its limitations and pitfalls and identify differentiating features from non-necrotizing soft-tissue infections, such as cellulitis and infective myositis/pyomyositis, conditions which may clinically mimic necrotizing fasciitis. PMID:24288403

Srinivasan, S; Peh, W C G

2014-01-01

352

[Cardiac MRI: technology, clinical applications, and future directions].  

PubMed

The field of cardiovascular MRI has evolved rapidly over the past decade, feeding new applications across a broad spectrum of clinical and research areas. Advances in magnet hardware technology, and key developments such as segmented k-space acquisitions, advanced motion encoding techniques, ultra-rapid perfusion imaging and delayed myocardial enhancement imaging have all contributed to a revolution in how patients with ischemic and non-ischemic heart disease are diagnosed and treated. Actually, cardiac MRI is a widely accepted method as the "gold standard" for detection and characterization of many forms of cardiac diseases. The aim of this review is to present an overview of cardiac MRI technology, advances in clinical applications, and future directions. PMID:24035258

Pesenti-Rossi, D; Peyrou, J; Baron, N; Allouch, P; Aubert, S; Boueri, Z; Livarek, B

2013-11-01

353

Displaying perfusion MRI images as color intensity projections  

E-print Network

Dynamic susceptibility-weighted contrast-enhanced (DSC) MRI or perfusion-MRI plays an important role in the non-invasive assessment of tumor vascularity. However, the large number of images provided by the method makes display and interpretation of the results challenging. Current practice is to display the perfusion information as relative cerebral blood volume maps (rCBV). Color intensity projections (CIPs) provides a simple, intuitive display of the perfusion-MRI data so that regional perfusion characteristics are intrinsically integrated into the anatomy structure the T2 images. The ease of use and quick calculation time of CIPs should allow it to be easily integrated into current analysis and interpretation pipelines.

Friso Hoefnagels; Keith S Cover; Ester Sanchez; Frank J. Lagerwaard

2007-11-19

354

Heterogeneity in DCE-MRI parametric maps: a biomarker for treatment response?  

NASA Astrophysics Data System (ADS)

This study aims to quantify the heterogeneity of tumour enhancement in dynamic contrast-enhanced MRI (DCE-MRI) using texture analysis methods. The suitability of the coherence and the fractal dimension to monitor tumour response was evaluated in 18 patients with limb sarcomas imaged by DCE-MRI pre- and post-treatment. According to the histopathology, tumours were classified into responders and non-responders. Pharmacokinetic (Ktrans) and heuristic model-based parametric maps (slope, max enhancement, AUC) were computed from the DCE-MRI data. A substantial correlation was found between the pharmacokinetic and heuristic model-based parametric maps: ? = 0.56 for the slope, ? = 0.44 for maximum enhancement, and ? = 0.61 for AUC. From all four parametric maps, the enhancing fraction, and the heterogeneity features (i.e. coherence and fractal dimension) were determined. In terms of monitoring tumour response, using both pre- and post-treatment DCE-MRI, the enhancing fraction and the coherence showed significant differences between the response group and the non-response group (i.e. the highest sensitivity (91%) for Ktrans, and the highest specificity (83%) for max enhancement). In terms of treatment prediction, using solely the pre-treatment DCE-MRI, the enhancing fraction and coherence discriminated between responders and non-responders. For prediction, the highest sensitivity (91%) was shared by Ktrans, slope and max enhancement, and the highest specificity (71%) was achieved by Ktrans. On average, tumours that responded showed a high enhancing fraction and high coherence on the pre-treatment scan. These results suggest that specific heterogeneity features, computed from both pharmacokinetic and heuristic model-based parametric maps, show potential as a biomarker for monitoring tumour response.

Alic, L.; van Vliet, M.; van Dijke, C. F.; Eggermont, A. M. M.; Veenland, J. F.; Niessen, W. J.

2011-03-01

355

Quantitative Serial MRI of the Treated Fibroid Uterus  

PubMed Central

Objective There are no long-term medical treatments for uterine fibroids, and non-invasive biomarkers are needed to evaluate novel therapeutic interventions. The aim of this study was to determine whether serial dynamic contrast-enhanced MRI (DCE-MRI) and magnetization transfer MRI (MT-MRI) are able to detect changes that accompany volume reduction in patients administered GnRH analogue drugs, a treatment which is known to reduce fibroid volume and perfusion. Our secondary aim was to determine whether rapid suppression of ovarian activity by combining GnRH agonist and antagonist therapies results in faster volume reduction. Methods Forty women were assessed for eligibility at gynaecology clinics in the region, of whom thirty premenopausal women scheduled for hysterectomy due to symptomatic fibroids were randomized to three groups, receiving (1) GnRH agonist (Goserelin), (2) GnRH agonist+GnRH antagonist (Goserelin and Cetrorelix) or (3) no treatment. Patients were monitored by serial structural, DCE-MRI and MT-MRI, as well as by ultrasound and serum oestradiol concentration measurements from enrolment to hysterectomy (approximately 3 months). Results A volumetric treatment effect assessed by structural MRI occurred by day 14 of treatment (9% median reduction versus 9% increase in untreated women; P?=?0.022) and persisted throughout. Reduced fibroid perfusion and permeability assessed by DCE-MRI occurred later and was demonstrable by 2–3 months (43% median reduction versus 20% increase respectively; P?=?0.0093). There was no apparent treatment effect by MT-MRI. Effective suppression of oestradiol was associated with early volume reduction at days 14 (P?=?0.041) and 28 (P?=?0.0061). Conclusion DCE-MRI is sensitive to the vascular changes thought to accompany successful GnRH analogue treatment of uterine fibroids and should be considered for use in future mechanism/efficacy studies of proposed fibroid drug therapies. GnRH antagonist administration does not appear to accelerate volume reduction, though our data do support the role of oestradiol suppression in GnRH analogue treatment of fibroids. Trial Registration ClinicalTrials.gov NCT00746031 PMID:24608161

Williams, Alistair R. W.; McKillop, Graham; Walker, Jane; Horne, Andrew W.; Newby, David E.; Anderson, Richard A.; Semple, Scott I.; Marshall, Ian; Lewis, Steff C.; Millar, Robert P.; Bastin, Mark E.; Critchley, Hilary O. D.

2014-01-01

356

Agreement of Mammographic Measures of Volumetric Breast Density to MRI  

PubMed Central

Background Clinical scores of mammographic breast density are highly subjective. Automated technologies for mammography exist to quantify breast density objectively, but the technique that most accurately measures the quantity of breast fibroglandular tissue is not known. Purpose To compare the agreement of three automated mammographic techniques for measuring volumetric breast density with a quantitative volumetric MRI-based technique in a screening population. Materials and Methods Women were selected from the UCSF Medical Center screening population that had received both a screening MRI and digital mammogram within one year of each other, had Breast Imaging Reporting and Data System (BI-RADS) assessments of normal or benign finding, and no history of breast cancer or surgery. Agreement was assessed of three mammographic techniques (Single-energy X-ray Absorptiometry [SXA], Quantra, and Volpara) with MRI for percent fibroglandular tissue volume, absolute fibroglandular tissue volume, and total breast volume. Results Among 99 women, the automated mammographic density techniques were correlated with MRI measures with R2 values ranging from 0.40 (log fibroglandular volume) to 0.91 (total breast volume). Substantial agreement measured by kappa statistic was found between all percent fibroglandular tissue measures (0.72 to 0.63), but only moderate agreement for log fibroglandular volumes. The kappa statistics for all percent density measures were highest in the comparisons of the SXA and MRI results. The largest error source between MRI and the mammography techniques was found to be differences in measures of total breast volume. Conclusion Automated volumetric fibroglandular tissue measures from screening digital mammograms were in substantial agreement with MRI and if associated with breast cancer could be used in clinical practice to enhance risk assessment and prevention. PMID:24324712

Wang, Jeff; Azziz, Ania; Fan, Bo; Malkov, Serghei; Klifa, Catherine; Newitt, David; Yitta, Silaja; Hylton, Nola; Kerlikowske, Karla; Shepherd, John A.

2013-01-01

357

Molecular MRI of Collagen to Diagnose and Stage Liver Fibrosis  

PubMed Central

Background & Aims The gold standard in assessing liver fibrosis is biopsy despite limitations like invasiveness and sampling error and complications including morbidity and mortality. Therefore, there is a major unmet medical need to quantify fibrosis noninvasively to facilitate early diagnosis of chronic liver disease and provide a means to monitor disease progression. The goal of this study was to evaluate the ability of several magnetic resonance imaging (MRI) techniques to stage liver fibrosis. Methods A gadolinium (Gd)-based MRI probe targeted to type I collagen (termed EP-3533) was utilized to noninvasively stage liver fibrosis in a carbon tetrachloride (CCl4) mouse model and the results were compared to other MRI techniques including relaxation times, diffusion and magnetization transfer measurements. Results The most sensitive MR biomarker was the change in liver:muscle contrast to noise ratio (?CNR) after EP-3533 injection. We observed a strong positive linear correlation between ?CNR and liver hydroxyproline (i.e. collagen) levels (r=0.89) as well as ?CNR and conventional Ishak fibrosis scoring. In addition, the area under the receiver operating curve (AUR0C) for distinguishing early (Ishak ?3) from late (Ishak ? 4) fibrosis was 0.942±0.052 (p<0.001). By comparison, other MRI techniques were not as sensitive to changes in fibrosis in this model. Conclusions We have developed a MRI technique using a collagen-specific probe for diagnosing and staging liver fibrosis, and validated it in the CCl4 mouse model. This approach should provide a better means to monitor disease progression in patients. PMID:23838178

Fuchs, Bryan C.; Wang, Huifang; Yang, Yan; Wei, Lan; Polasek, Miloslav; Schühle, Daniel T.; Lauwers, Gregory Y.; Parkar, Ashfaq; Sinskey, Anthony J.; Tanabe, Kenneth K.; Caravan, Peter

2013-01-01

358

Cluster validation indices for fMRI data: Fuzzy C-Means with feature partitions versus cluster merging strategies  

Microsoft Academic Search

Fuzzy C-Means (FCM) is a standard technique for exploratory analysis and is readily adaptable to integrate unique data characteristics and auxiliary feature relations. Distinguishing between the spatial and temporal features of functional magnetic resonance imaging (fMRI) time courses (TC) has proved effective in reducing the presence of false positives for stimulation studies. The fuzzy partitions generated by this FCM variant

M. D. Alexiuk; N. J. Pizzi

2004-01-01

359

CT and MRI of fibrous dysplasia of the spine  

PubMed Central

Objectives The purpose of this study was to present the CT and MRI findings of patients with fibrous dysplasia (FD) of the spine. Methods Among the patients with pathologically proven skeletal FD, 12 (8 males and 4 females; mean age, 43 years) who were evaluated with either spine CT or MRI were included. The number and location of the involved vertebral segments, the presence of lytic lesions, ground-glass opacity (GGO), an expansile nature, cortical disruption, a sclerotic rim, a decrease in body height and contour deformity were examined on CT scans (n = 12), while signal intensity, enhancement patterns and the presence of a dark signal rim on the lesion were examined using MRI (n = 9). Results Nine patients had polyostotic FD, including one with an isolated spinal localisation, while three had monostotic FD. An expansile nature (n = 3) and osteolytic lesions with GGO (n = 3) were seen. On CT images, GGO was noted in all patients. An expansile nature (n = 11) and presence of lytic lesions (n = 11) were noted. A decrease in body height (n = 9) and sclerotic rim formation (n = 9) were indicated. Contour deformities were visible in six patients. The MRI findings were non-specific. Dark signal rims were visible on MRI in seven patients. Conclusion Typical imaging findings of extraspinal FD were noted on spine CT scans. These characteristic CT imaging findings of spinal FD may be helpful in differentiating FD from other common spine diseases. PMID:22167510

Park, S K; Lee, I S; Choi, J-Y; Cho, K H; Suh, K J; Lee, J W; Song, J W

2012-01-01

360

Mouse MRI: Concepts and Applications in Physiology  

NSDL National Science Digital Library

Brief introduction to the rapidly expanding field of mouse magnetic resonance imaging (MRI), including the basics of MRI theory, insight into the basic experiments that can be performed in mice by using MRI, and some factors to consider when planning a mouse MRI experiment.

PhD Robia G. Pautler (Baylor College of Medicine Department of Molecular Physiology and Biophysics)

2004-08-01

361

Hepatic Sinusoidal Obstruction Syndrome Caused by Herbal Medicine: CT and MRI Features  

PubMed Central

Objective To describe the CT and MRI features of hepatic sinusoidal obstruction syndrome (HSOS) caused by herbal medicine Gynura segetum. Materials and Methods The CT and MRI features of 16 consecutive Gynura segetum induced HSOS cases (12 men, 4 women) were analyzed. Eight patients had CT; three patients had MRI, and the remaining five patients had both CT and MRI examinations. Based on their clinical presentations and outcomes, the patients were classified into three categories: mild, moderate, and severe. The severity of the disease was also evaluated radiologically based on the abnormal hepatic patchy enhancement in post-contrast CT or MRI images. Results Ascites, patchy liver enhancement, and main right hepatic vein narrowing or occlusion were present in all 16 cases. Hepatomegaly and gallbladder wall thickening were present in 14 cases (87.5%, 14/16). Periportal high intensity on T2-weighted images was present in 6 cases (75%, 6/8). Normal liver parenchymal enhancement surrounding the main hepatic vein forming a clover-like sign was observed in 4 cases (25%, 4/16). The extent of patchy liver enhancement was statistically associated with clinical severity classification (kappa = 0.565). Conclusion Ascites, patchy liver enhancement, and the main hepatic veins narrowing were the most frequent signs of herbal medicine induced HSOS. The grade of abnormal patchy liver enhancement was associated with the clinical severity. PMID:24643319

Zhou, Hua; Wang, Yi-Xiang J.; Lou, Hai-yan; Xu, Xiao-jun

2014-01-01

362

MRI of cholangiocarcinoma.  

PubMed

Cholangiocarcinomas are the second most common primary hepatobiliary tumors after hepatocellular carcinomas. They can be categorized either based on their location (intrahepatic/perihilar/extrahepatic distal) or their growth characteristics (mass-forming/periductal-infiltrating/intraductal) because they exhibit varied presentations and outcomes based on their location and or pattern of growth. The increased risk of cholangiocarcinoma in PSC necessitates close surveillance of these patients by means of imaging and laboratory measures; and because currently surgical resection is the only effective treatment for cholangiocarcinoma, the need for accurate pre-operative staging and assessment of resectability has emphasized the role of high quality imaging in management. Today magnetic resonance imaging (MRI) is the modality of choice for detection, pre-operative staging and surveillance of cholangiocarcinoma. J. Magn. Reson. Imaging 2014. PMID:25447417

Jhaveri, Kartik S; Hosseini-Nik, Hooman

2014-12-01

363

Liberating the Publications of a Distinguished Scholar: A Pilot Project  

ERIC Educational Resources Information Center

Many distinguished scholars published the primary corpus of their work before the advent of online journals, which makes it more challenging to access. Upon being approached by a distinguished Emeritus Professor seeking advice about getting his work posted online, librarians at the University of Minnesota worked to gain copyright permissions to…

Kelly, Julie

2014-01-01

364

Distinguishability of Biological Material Using Ultraviolet Multi-Spectral Fluorescence  

SciTech Connect

Recent interest in the detection and analysis of biological samples by spectroscopic methods has led to questions concerning the degree of distinguishability and biological variability of the ultraviolet (W) fluorescent spectra from such complex samples. We show that the degree of distinguishability of such spectra is readily determined numerically.

Gray, P.C.; Heinen, R.J.; Rigdon, L.D.; Rosenthal, S.E.; Shokair, I.R.; Siragusa, G.R.; Tisone, G.C.; Wagner, J.S.

1998-10-14

365

Distinguishability of Biological Material Using Ultraviolet MultiSpectral Fluorescence  

Microsoft Academic Search

Recent interest in the detection and analysis of biological samples by spectroscopic methods has led to questions concerning the degree of distinguishability and biological variability of the ultraviolet (W) fluorescent spectra from such complex samples. We show that the degree of distinguishability of such spectra is readily determined numerically.

P. C. Gray; R. J. Heinen; L. D. Rigdon; S. E. Rosenthal; I. R. Shokair; G. R. Siragusa; G. C. Tisone; J. S. Wagner

1998-01-01

366

NOMINATION FORM 2010 Distinguished Texan in Agriculture Award  

E-print Network

NOMINATION FORM 2010 Distinguished Texan in Agriculture Award Texas A&M AgriLife The Texas A/her contributions on behalf of the Texas agricultural industry and community (information may be submitted:__________________________________________________________ ________________________________________________________________________ RETURN NOMINATIONS TO 2010 Distinguished Texan in Agriculture Selection Advisory Committee c/o Office

367

Distinguishing Humans from Bots in Web Search Logs  

E-print Network

Distinguishing Humans from Bots in Web Search Logs Omer M. Duskin Dror G. Feitelson School characterize human web search behavior, and to study the effects of bot activity. However, available workload of these non-human behaviors as "bots". Bots are not unique to web search activity, and the need to distinguish

Feitelson, Dror

368

Distinguishability of Conductivities by Electric Current Computed Tomography  

Microsoft Academic Search

We give criteria for the distinguishability of two different conductivity distributions inside a body by electric current computed tomography (ECCT) systems with a specified precision. It is shown in a special case how these criteria can be used to determine the measurement precision needed to distinguish between two different conductivity distributions. It is also shown how to select the patterns

David Isaacson

1986-01-01

369

Exemplar Selection Methods to Distinguish Human from Animal Footsteps  

E-print Network

), but that the self-training method shows promise for the task of learning to distinguish between the discrete of learning a classifier from a mixture of unlabeled and labeled training data, under the constraint that labeled training data exist for only N-1 of the N target classes. The task of distinguishing human from

Hasegawa-Johnson, Mark

370

Documenting the location of systematic transrectal ultrasound-guided prostate biopsies: correlation with multi-parametric MRI  

PubMed Central

Abstract During transrectal ultrasound (TRUS)-guided prostate biopsies, the actual location of the biopsy site is rarely documented. Here, we demonstrate the capability of TRUS-magnetic resonance imaging (MRI) image fusion to document the biopsy site and correlate biopsy results with multi-parametric MRI findings. Fifty consecutive patients (median age 61 years) with a median prostate-specific antigen (PSA) level of 5.8?ng/ml underwent 12-core TRUS-guided biopsy of the prostate. Pre-procedural T2-weighted magnetic resonance images were fused to TRUS. A disposable needle guide with miniature tracking sensors was attached to the TRUS probe to enable fusion with MRI. Real-time TRUS images during biopsy and the corresponding tracking information were recorded. Each biopsy site was superimposed onto the MRI. Each biopsy site was classified as positive or negative for cancer based on the results of each MRI sequence. Sensitivity, specificity, and receiver operating curve (ROC) area under the curve (AUC) values were calculated for multi-parametric MRI. Gleason scores for each multi-parametric MRI pattern were also evaluated. Six hundred and 5 systemic biopsy cores were analyzed in 50 patients, of whom 20 patients had 56 positive cores. MRI identified 34 of 56 positive cores. Overall, sensitivity, specificity, and ROC area values for multi-parametric MRI were 0.607, 0.727, 0.667, respectively. TRUS-MRI fusion after biopsy can be used to document the location of each biopsy site, which can then be correlated with MRI findings. Based on correlation with tracked biopsies, T2-weighted MRI and apparent diffusion coefficient maps derived from diffusion-weighted MRI are the most sensitive sequences, whereas the addition of delayed contrast enhancement MRI and three-dimensional magnetic resonance spectroscopy demonstrated higher specificity consistent with results obtained using radical prostatectomy specimens. PMID:21450548

Xu, Sheng; Kruecker, Jochen; Locklin, Julia; Pang, Yuxi; Shah, Vijay; Bernardo, Marcelino; Baccala, Angelo; Rastinehad, Ardeshir; Benjamin, Compton; Merino, Maria J.; Wood, Bradford J.; Choyke, Peter L.; Pinto, Peter A.

2011-01-01

371

A unified formulation for entanglement of distinguishable and indistinguishable particles  

E-print Network

Entanglement is a well understood concept only for distinguishable particles. However fundamental particles being inherently indistinguishable, it is desirable to have a single formulation for entanglement of distinguishable and indistinguishable particles. We take such a unified notion to be defined in connection with a measurement whose outcome gives R\\`{e}nyi entropies when two subsystems are perfectly distinguishable, and which remains well defined even when two subsystems can not be distinguished perfectly. An explicit formula for outcome of such a measurement, which we call "exact R\\`{e}nyi entropy", is conjectured in terms of "normalized" R\\'{e}nyi entropies of spatial regions in field theory. Same idea is used to define "exact Von Neumann entropy" as well. Our formula works for both statistics and to leading order reproduces R\\'{e}nyi/Von Neumann entropies of distinguishable particles. Corrections due to indistinguishability are finite in number, they depend on spatial overlap of the wave functions an...

Mondal, Swapnamay

2015-01-01

372

Adenomatoid odontogenic tumor: correlation of MRI with histopathological findings.  

PubMed

Adenomatoid odontogenic tumor is a rare benign and odontogenic tumor that is frequently misdiagnosed as other odontogenic cysts and tumors on radiographic examination. To acquire additional information of adenomatoid odontogenic tumor, we performed magnetic resonance imagings (MRI) at a case of adenomatoid odontogenic tumor. The lesion was divided between the peripheral portion with a thick circular shape and the central portion with a round shape on the basis of the signal intensity (SI) of MRI. The peripheral portion showed intermediate SI contained multifocal no SI on T1WI, high SI contained multifocal no SI on T2WI, and heterogeneous enhancement on CE-T1WI. These multifocal areas corresponded to the numerous punctate radiopaque foci shown on computed tomography. The central portion showed homogeneous low SI on T1WI, homogeneous very high SI on T2WI, and no enhancement on CE-T1WI. Macroscopic examination revealed the round shaped lesion included one large cystic space correspondent to the central portion with a clear cystic wall correspondent to the peripheral portion on MRI. The MRI features corresponded to the macroscopic findings of the histopathological examination. PMID:12350405

Konouchi, Hironobu; Asaumi, Jun-ichi; Yanagi, Yoshinobu; Hisatomi, Miki; Kishi, Kanji

2002-10-01

373

Assessment of Diastolic Function by Cardiac MRI  

Microsoft Academic Search

Cardiac magnetic resonance imaging (MRI) techniques continue to change rapidly, and cardiac MRI is developing as an alternative\\u000a noninvasive technique having the unique potential of three-dimensional function analysis with great accuracy and reproducibility.\\u000a Advances in rapid cardiac MRI technology are making real-time imaging possible at approaching echocardiographic frame rates.\\u000a Together with the increasing availability of cardiac MRI machines, cardiac MRI

Bernard P. Paelinck; Hildo J. Lamb

374

Albert Einstein Distinguished Educators Fellowship Act of 1994. Report To Accompany S. 2104. 103D Congress, 2d Session, Senate.  

ERIC Educational Resources Information Center

This document contains the text of the "Albert Einstein Distinguished Educators Fellowship Act of 1994" (S. 2104) along with related analysis. The bill establishes a Department of Energy (DOE) fellowship program for math and science teachers that provides them opportunities to work at DOE labs in order to enhance coordination and communication…

Congress of the U.S., Washington, DC. Senate Committee on Energy and Natural Resources.

375

Contrast Agents for Cardiovascular MRI  

Microsoft Academic Search

In the last two decades, magnetic resonance imaging (MRI) has revolutionized clinical cardiovascular imaging. Its major advantages\\u000a over other noninvasive diagnostic modalities are its safety, operator-independent reproducibility, and multiplanar two-dimensional\\u000a (2D) and three-dimensional (3D) imaging capability with high spatial and temporal resolution. MRI does not deliver ionizing\\u000a radiation and does not utilize inherently nephrotoxic iodinated contrast media. The intrinsic tissue

Hale Ersoy; Frank Rybicki; Martin Prince

376

Quantitative pharmacologic MRI in mice  

PubMed Central

Pharmacologic MRI (phMRI) uses functional MRI techniques to provide a non-invasive in vivo measurement of the hemodynamic effects of drugs. The cerebral blood volume change (?CBV) serves as a surrogate for neuronal activity via neurovascular coupling mechanisms. By assessing the location and time course of brain activity in mouse mutant studies, phMRI can provide valuable insights into how different behavioral phenotypes are expressed in differing brain activity response to drug challenge. In this report, we evaluate the utility of three different intravascular ultrasmall superparamagnetic iron oxide (USPIO) contrast agents for phMRI using a gradient-echo technique with temporal resolution of one minute at high magnetic field. The tissue half life of the USPIOs was studied using a nonlinear detrending model. All three studied USPIOs are candidates for CBV weighted phMRI-experiments, with r2/r1 ratios ? 20 and apparent half-lives ? 1.5 h at the described doses. An echo time of about 10 ms or longer results in a fCNR > 75 after USPIO injection, with negligible decrease during 1.5 to 2 hours. phMRI experiments were conducted at 7T using cocaine as a psychotropic substance and acetazolamide, a global vasodilator, as a positive control. Cocaine acts as a dopamine-serotonin-norepinephrine reuptake inhibitor, increasing extracellular concentrations of these neurotransmitters and thus increasing dopaminergic, serotonergic and noradrenergic neurotransmission. phMRI indicated that CBV was reduced in the normal mouse brain after cocaine challenge, with largest effects in nucleus accumbens, while after acetazolamide the blood volume was increased in both cerebral and extra-cerebral tissue. PMID:21793079

Perles-Barbacaru, Teodora-Adriana; Procissi, Daniel; Demyanenko, Andrey V.; Jacobs, Russell E.

2011-01-01

377

Pediatric elbow fractures: MRI evaluation  

Microsoft Academic Search

Magnetic resonance imaging (MRI) was performed in eight patients under the age of 8 years who suffered elbow fractures, to\\u000a assess possible fracture extension into the distal nonossified epiphysis of the humerus in seven cases and to determine the\\u000a displacement and location of the radial head in one case. MRI allowed accurate depiction of the fracture line when it extended

Javier Beltran; Zehava S. Rosenberg; Moises Kawelblum; Lourdes Montes; A. Gabrielle Bergman; Alan Strongwater

1994-01-01

378

Quantitative pharmacologic MRI in mice.  

PubMed

Pharmacologic MRI (phMRI) uses functional MRI techniques to provide a noninvasive in vivo measurement of the hemodynamic effects of drugs. The cerebral blood volume change (?CBV) serves as a surrogate for neuronal activity via neurovascular coupling mechanisms. By assessing the location and time course of brain activity in mouse mutant studies, phMRI can provide valuable insights into how different behavioral phenotypes are expressed in deferring brain activity response to drug challenge. In this report, we evaluate the utility of three different intravascular ultrasmall superparamagnetic iron oxide (USPIO) contrast agents for phMRI using a gradient-echo technique, with temporal resolution of one min at high magnetic field. The tissue half-life of the USPIOs was studied using a nonlinear detrending model. The three USPIOs are candidates for CBV weighted phMRI experiments, with r(2)/r(1) ratios ? 20 and apparent half-lives ? 1.5 h at the described doses. An echo-time of about 10 ms or longer results in a functional contrast to noise ratio (fCNR) > 75 after USPIO injection, with negligible decrease between 1.5-2 h. phMRI experiments were conducted at 7 T using cocaine as a psychotropic substance and acetazolamide, a global vasodilator, as a positive control. Cocaine acts as a dopamine-serotonin-norepinephrine reuptake inhibitor, increasing extracellular concentrations of these neurotransmitters, and thus increasing dopaminergic, serotonergic and noradrenergic neurotransmission. phMRI results showed that CBV was reduced in the normal mouse brain after cocaine challenge, with the largest effects in the nucleus accumbens, whereas after acetazolamide, blood volume was increased in both cerebral and extracerebral tissue. PMID:21793079

Perles-Barbacaru, Teodora-Adriana; Procissi, Daniel; Demyanenko, Andrey V; Jacobs, Russell E

2012-04-01

379

[Placental MRI: physiology and pathology].  

PubMed

The placenta is essential for fetal development but its in vivo study, including the study of placental perfusion is still very limited to date. MRI is a safe examination that offers new perspectives for the study of placental function that is altered in many conditions (IUGR, preeclampsia…) and placental anatomy (placenta accreta…). The different MRI sequences (DCE, IVIM, BOLD, ASL…) are new tools that may soon allow us to assess precisely placental function and anatomy, in vivo and non-invasively. PMID:23731696

Deloison, B; Millischer, A-E; Salomon, L-J

2013-06-01

380

The Claude Bernard Distinguished Lecture. In pursuit of meaningful learning.  

PubMed

The Bernard Distinguished Lecturers are individuals who have a history of experience and expertise in teaching that impacts multiple levels of health science education. Dr. Joel Michael more than meets these criteria. Joel earned a BS in biology from CalTech and a PhD in physiology from MIT following which he vigorously pursued his fascination with the mammalian central nervous system under continuous National Institutes of Health funding for a 15-yr period. At the same time, he became increasingly involved in teaching physiology, with the computer being his bridge between laboratory science and classroom teaching. Soon after incorporating computers into his laboratory, he began developing computer-based learning resources for his students. Observing students using these resources to solve problems led to an interest in the learning process itself. This in turn led to a research and development program, funded by the Office of Naval Research (ONR), that applied artificial intelligence to develop smart computer tutors. The impact of problem solving on student learning became the defining theme of National Science Foundation (NSF)-supported research in health science education that gradually moved all of Dr. Michael's academic efforts from neurophysiology to physiology education by the early 1980's. More recently, Joel has been instrumental in developing and maintaining the Physiology Education Research Consortium, a group of physiology teachers from around the nation who collaborate on diverse projects designed to enhance learning of the life sciences. In addition to research in education and learning science, Dr. Michael has devoted much of his time to helping physiology teachers adopt modern approaches to helping students learn. He has organized and presented faculty development workshops at many national and international venues. The topics for these workshops have included computer-based education, active learning, problem-based learning, and the use of general models in teaching physiology. PMID:11824191

Michael, J

2001-12-01

381

MRI of the lung gas-space at very low-field using hyperpolarized noble gases  

Microsoft Academic Search

Abstract In hyperpolarized (HP) noble-gas magnetic resonance imaging, large nuclear spin polarizations, about 100,000 times that ordinarily obtainable at thermal equilibrium, are created in ,Xe. The enhanced signal that results can be employed in high-resolution MRI studies of void spaces such as in the lungs. In HP gas MRI the signal-to-noise ratio (SNR) depends only weakly,on the static magnetic,field (B0),

Arvind K. Venkatesh; Adelaide X. Zhang; Joey Mansour; Lyubov Kubatina; Oh Chang-hyun; Gregory Blasche; M. Selim U Nlu; Dilip Balamore; Ferenc A. Jolesz; Bennett B. Goldberg; Mitchell S. Albert

382

MRI of the lung gas-space at very low-field using hyperpolarized noble gases  

Microsoft Academic Search

In hyperpolarized (HP) noble-gas magnetic resonance imaging, large nuclear spin polarizations, about 100,000 times that ordinarily obtainable at thermal equilibrium, are created in 3He and 129Xe. The enhanced signal that results can be employed in high-resolution MRI studies of void spaces such as in the lungs. In HP gas MRI the signal-to-noise ratio (SNR) depends only weakly on the static

Arvind K. Venkatesh; Adelaide X. Zhang; Joey Mansour; Lyubov Kubatina; Chang-Hyun Oh; Gregory Blasche; M. Selim Ünlü; Dilip Balamore; Ferenc A. Jolesz; Bennett B. Goldberg; Mitchell S. Albert

2003-01-01

383

In vivo MRI study of the visual system in normal, developing and injured rodent brains  

Microsoft Academic Search

This paper demonstrated our recent use of contrast-enhanced MRI, diffusion tensor\\/kurtosis imaging, proton magnetic resonance spectroscopy, and functional MRI techniques, for in vivo and global assessments of the structure, metabolism and function of the visual system in rodent studies of ocular diseases, optic neuropathies, developmental plasticity and neonatal hypoxic-ischemic brain injury at 7T. Results suggested the significant values of high-field

Kevin C. Chan; Matthew M. Cheung; Kyle K. Xing; Iris Y. Zhou; April M. Chow; Condon Lau; Kwok-fai So; Ed X. Wu

2010-01-01

384

Evaluation of focal hepatic masses: a comparative study of MRI and CT  

Microsoft Academic Search

We evaluated suspected hepatic lesions in 30 patients using both nongated spin-echo magnetic resonance imaging (MRI) on a 0.35 T superconducting magnet and contrast-enhanced dynamic incremental computed tomography (CT). In the 27 patients with focal lesions, both modalities detected abnormalities in 26 patients. Liver lesions were equally well demonstrated using MRI and CT in 15 patients, better demonstrated by CT

Gary M. Glazer; Alex M. Aisen; Isaac R. Francis; Barry H. Gross; John W. Gyves; William D. Ensminger

1986-01-01

385

Copaxone's effect on MRI-monitored disease in relapsing MS is reproducible and sustained  

Microsoft Academic Search

All but 6% of the subjects with relapsing remitting MS who were randomly assigned to receive glatiramer acetate or placebo for the 9-month controlled phase of the European\\/Canadian MRI trial entered an open-label extension with quarterly clinical and MRI evaluations for another 9 months. There was a 54% reduction in the mean number of enhanced lesions for those converted from

J. S. Wolinsky; G. Comi; M. Filippi; D. Ladkani; S. Kadosh; G. Shifroni

386

Quintuple-modality (SERS-MRI-CT-TPL-PTT) plasmonic nanoprobe for theranostics.  

PubMed

A unique quintuple-modality theranostic nanoprobe (QMT) is developed with gold nanostars for surface-enhanced Raman scattering (SERS), magnetic resonance imaging (MRI), computed tomography (CT), two-photon luminescence (TPL) imaging and photothermal therapy (PTT). The synthesized gold nanostars were tagged with a SERS reporter and linked with an MRI contrast agent Gd(3+). In vitro experiments demonstrated the developed QMT nanoprobe to be a potential theranostic agent for future biomedical applications. PMID:24162005

Liu, Yang; Chang, Zheng; Yuan, Hsiangkuo; Fales, Andrew M; Vo-Dinh, Tuan

2013-12-21

387

Role of Diffusion-Weighted MRI in the Detection of Early Active Sacroiliitis  

Microsoft Academic Search

OBJECTIVE. This study proposed to evaluate the value of diffusion-weighted MRI (DWI) to detect active inflammatory changes in the sacroiliac joints of patients with early axial spondyloarthritis (also spelled spondylarthritis). Su BJECTS AND METHODS. Forty-two patients with chronic low back pain under- went clinical and MRI evaluation for axial spondyloarthritis or early ankylosing spondylitis. STIR, contrast-enhanced T1-weighted, fat-saturated T2-weighted, and

Zulkif Bozgeyik; Salih Ozgocmen; Ercan Kocakoc

2008-01-01

388

Layer-specific intracortical connectivity revealed with diffusion MRI.  

PubMed

In this work, we show for the first time that the tangential diffusion component is orientationally coherent at the human cortical surface. Using diffusion magnetic resonance imaging (dMRI), we have succeeded in tracking intracortical fiber pathways running tangentially within the cortex. In contrast with histological methods, which reveal little regarding 3-dimensional organization in the human brain, dMRI delivers additional understanding of the layer dependence of the fiber orientation. A postmortem brain block was measured at very high angular and spatial resolution. The dMRI data had adequate resolution to allow analysis of the fiber orientation within 4 notional cortical laminae. We distinguished a lamina at the cortical surface where diffusion was tangential along the surface, a lamina below the surface where diffusion was mainly radial, an internal lamina covering the Stria of Gennari, where both strong radial and tangential diffusion could be observed, and a deep lamina near the white matter, which also showed mainly radial diffusion with a few tangential compartments. The measurement of the organization of the tangential diffusion component revealed a strong orientational coherence at the cortical surface. PMID:23099298

Leuze, Christoph W U; Anwander, Alfred; Bazin, Pierre-Louis; Dhital, Bibek; Stüber, Carsten; Reimann, Katja; Geyer, Stefan; Turner, Robert

2014-02-01

389

Layer-Specific Intracortical Connectivity Revealed with Diffusion MRI  

PubMed Central

In this work, we show for the first time that the tangential diffusion component is orientationally coherent at the human cortical surface. Using diffusion magnetic resonance imaging (dMRI), we have succeeded in tracking intracortical fiber pathways running tangentially within the cortex. In contrast with histological methods, which reveal little regarding 3-dimensional organization in the human brain, dMRI delivers additional understanding of the layer dependence of the fiber orientation. A postmortem brain block was measured at very high angular and spatial resolution. The dMRI data had adequate resolution to allow analysis of the fiber orientation within 4 notional cortical laminae. We distinguished a lamina at the cortical surface where diffusion was tangential along the surface, a lamina below the surface where diffusion was mainly radial, an internal lamina covering the Stria of Gennari, where both strong radial and tangential diffusion could be observed, and a deep lamina near the white matter, which also showed mainly radial diffusion with a few tangential compartments. The measurement of the organization of the tangential diffusion component revealed a strong orientational coherence at the cortical surface. PMID:23099298

Leuze, Christoph W.U.; Anwander, Alfred; Bazin, Pierre-Louis; Dhital, Bibek; Stüber, Carsten; Reimann, Katja; Geyer, Stefan; Turner, Robert

2014-01-01

390

[Recent advances in newborn MRI].  

PubMed

The accurate morphological exploration of the brain is a major challenge in neonatology that advances in magnetic resonance imaging (MRI) can now provide. MRI is the gold standard if an hypoxic ischemic pathology is suspected in a full term neonate. In prematures, the specific role of MRI remains to be defined, secondary to US in any case. We present a state of the art of hardware and software technical developments in MRI. The increase in magnetic field strength (3 tesla) and the emergence of new MRI sequences provide access to new information. They both have positive and negative consequences on the daily clinical data acquisition use. The semiology of brain imaging in full term newborns and prematures is more extensive and complex and thereby more difficult to interpret. The segmentation of different brain structures in the newborn, even very premature, is now available. It is now possible to dissociate the cortex and basal ganglia from the cerebral white matter, to calculate the volume of anatomical structures, which improves the morphometric quantification and the understanding of the normal and abnormal brain development. MRI is a powerful tool to analyze the neonatal brain. The relevance of the diagnostic contribution requires an adaptation of the parameters of the sequences to acquire and of the image processing methods. PMID:24837857

Morel, B; Hornoy, P; Husson, B; Bloch, I; Adamsbaum, C

2014-07-01

391

MRI-Guided Electrophysiology Intervention  

PubMed Central

Catheter ablation is a first-line treatment for many cardiac arrhythmias and is generally performed under X-ray fluoroscopy guidance. However, current techniques for ablating complex arrhythmias such as atrial fibrillation and ventricular tachycardia are associated with sub-optimal success rates and prolonged radiation exposure. Pre-procedure 3-D magnetic resonance imaging (MRI) has improved understanding of the anatomic basis of complex arrhythmias and is being used for planning and guidance of ablation procedures. A particular strength of MRI compared to other imaging modalities is the ability to visualize ablation lesions. Post-procedure MRI is now being applied to assess ablation lesion location and permanence with the goal of identifying factors leading to procedure success and failure. In the future, intra-procedure real-time MRI, together with the ability to image complex 3-D arrhythmogenic anatomy and target additional ablation to regions of incomplete lesion formation, may allow for more successful treatment of even complex arrhythmias without exposure to ionizing radiation. Development of clinical grade MRI-compatible electrophysiology devices is required to transition intra-procedure MRI from preclinical studies to more routine use in patients. PMID:23908787

Halperin, Henry R.; Kolandaivelu, Aravindan

2010-01-01

392

Conjugation to Biocompatible Dendrimers Increases Lanthanide T2 Relaxivity of Hydroxypyridinone (HOPO) Complexes for Magnetic Resonance Imaging (MRI)  

PubMed Central

Magnetic resonance imaging (MRI) contrast agents represent a worldwide billion-dollar market annually. While T1 relaxivity enhancement contrast agents receive greater attention and a significantly larger market share, the commercial potential for T2 relaxivity enhancing contrast agents remains a viable diagnostic option due to their increased relaxivity at high field strengths. Improving the contrast and biocompatibility of T2 MRI probes may enable new diagnostic prospects for MRI. Paramagnetic lanthanides have the potential to decrease T1 and T2 proton relaxation times, but are not commercially used in MRI diagnostics as T2 agents. In this article, oxygen donor chelates (hydroxypyridinone, HOPO, and terephthalamide, TAM) of various lanthanides are demonstrated as biocompatible macromolecular dendrimer conjugates for the development of T2 MRI probes. These conjugates have relaxivities up to 374 mm?1s?1 per dendrimer, high bioavailability, and low in vitro toxicity. PMID:23539072

Klemm, Piper J.; Floyd, William C.; Andolina, Christopher M.; Fréchet, Jean M. J.; Raymond, Kenneth N.

2013-01-01

393

Conjugation to Biocompatible Dendrimers Increases Lanthanide T2 Relaxivity of Hydroxypyridinone (HOPO) Complexes for Magnetic Resonance Imaging (MRI).  

PubMed

Magnetic resonance imaging (MRI) contrast agents represent a worldwide billion-dollar market annually. While T1 relaxivity enhancement contrast agents receive greater attention and a significantly larger market share, the commercial potential for T2 relaxivity enhancing contrast agents remains a viable diagnostic option due to their increased relaxivity at high field strengths. Improving the contrast and biocompatibility of T2 MRI probes may enable new diagnostic prospects for MRI. Paramagnetic lanthanides have the potential to decrease T1 and T2 proton relaxation times, but are not commercially used in MRI diagnostics as T2 agents. In this article, oxygen donor chelates (hydroxypyridinone, HOPO, and terephthalamide, TAM) of various lanthanides are demonstrated as biocompatible macromolecular dendrimer conjugates for the development of T2 MRI probes. These conjugates have relaxivities up to 374 mm(-1)s(-1) per dendrimer, high bioavailability, and low in vitro toxicity. PMID:23539072

Klemm, Piper J; Floyd, William C; Andolina, Christopher M; Fréchet, Jean M J; Raymond, Kenneth N

2012-04-01

394

MRI of radiation-induced tumors of the head and neck in post-radiation nasopharyngeal carcinoma.  

PubMed

The aim of this study was to document the sites and MRI features of radiation-induced tumors (RITs) in the head and neck following treatment for nasopharyngeal carcinoma (NPC). The MRI examinations and clinical records of 20 patients with 21 RITs were reviewed retrospectively. RITs developed 3-30 years after radiotherapy and included eleven squamous cell carcinomas, six sarcomas, two neuroendocrine carcinomas, one mucoepidermoid carcinoma and one meningioma. RITs arose in the maxillary region (9), oro/hypopharynx and oral cavity (5), external auditory canal (4), nasopharynx and sphenoid sinus (2) and brain (1). Radiation-induced carcinoma and sarcoma had MRI features that were useful to distinguish them from recurrent NPC. To improve early detection of RITs, the check areas on an MRI of a patient with previous NPC treated by radiation should always include the maxillary region, tongue, and external auditory canal/temporal bone. PMID:19142643

Abrigo, Jill M; King, Ann D; Leung, Sing Fai; Vlantis, Alexander C; Wong, Jeffrey K T; Tong, Michael C F; Tse, Gary M K; Ahuja, Anil T

2009-05-01

395

MRI guidance for focused ultrasound surgery  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) based monitoring has been shown in recent years to enhance the effectiveness of minimally or noninvasive thermal therapy techniques, such as focused ultrasound surgery. MR imaging's unique soft tissue contrast and ability to image in three dimensions and in any orientation make it extremely useful for treatment planning and for imaging the tissue response to the therapy. The temperature sensitivity of several intrinsic parameters enables MRI to visualize and quantify the progress an ongoing thermal treatment. The most useful temperature-sensitive parameter appears to be the proton resonant frequency, which allows for precise and accurate temperature measurements in water-based tissues. By acquiring a time series of quantitative temperature images, it is possible to monitor the accumulated thermal dose delivered to the target tissue and accurately predict the areas that are thermally ablated, while at the same time ensuring nearby critical structures are not heated. The method is currently used in an FDA approved focused ultrasound device for the treatment of uterine fibroids. Our research and clinical experience with these techniques will be reviewed.

McDannold, Nathan; Hynynen, Kullervo

2005-09-01

396

Breast cancer classification with mammography and DCE-MRI  

Microsoft Academic Search

Since different imaging modalities provide complementary information regarding the same lesion, combining information from different modalities may increase diagnostic accuracy. In this study, we investigated the use of computerized features of lesions imaged via both full-field digital mammography (FFDM) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in the classification of breast lesions. Using a manually identified lesion location, i.e. a

Yading Yuan; Maryellen L. Giger; Hui Li; Charlene Sennett

2009-01-01

397

The NIH MRI study of normal brain development.  

PubMed

MRI is increasingly used to study normal and abnormal brain development, but we lack a clear understanding of "normal". Previous studies have been limited by small samples, narrow age ranges and few behavioral measures. This multi-center project conducted epidemiologically based recruitment of a large, demographically balanced sample across a wide age range, using strict exclusion factors and comprehensive clinical/