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Full-Text Articles in Medicine and Health Sciences
Scan-Rescan And Intra-Observer Variability Of Magnetic Resonance Imaging Of Carotid Atherosclerosis At 1.5 T And 3.0 T, Arvin Vidal, Yves Bureau, Trevor Wade, J David Spence, Brian K Rutt, Aaron Fenster, Grace Parraga
Scan-Rescan And Intra-Observer Variability Of Magnetic Resonance Imaging Of Carotid Atherosclerosis At 1.5 T And 3.0 T, Arvin Vidal, Yves Bureau, Trevor Wade, J David Spence, Brian K Rutt, Aaron Fenster, Grace Parraga
Medical Biophysics Publications
Carotid atherosclerosis measurements for eight subjects at baseline and 14 +/- 2 days later were examined using 1.5 T and 3.0 T magnetic resonance imaging (MRI). A single observer blinded to field strength, subject and timepoint manually segmented carotid artery wall and lumen boundaries in randomized images in five measurement trials. Mean increases in the signal-to-noise ratios (SNR) for T1-weighted images acquired at 3.0 T compared to 1.5 T were 90% (scan) and 80% (rescan). Despite significantly improved SNR and contrast-to-noise ratios (CNR) for images acquired at 3.0 T, vessel wall volume (VWV) intra-observer variability was not significantly different using …
Mapping And Quantifying Hyperpolarized 3he Magnetic Resonance Imaging Apparent Diffusion Coefficient Gradients, Andrea Evans, David G Mccormack, Giles Santyr, Grace Parraga
Mapping And Quantifying Hyperpolarized 3he Magnetic Resonance Imaging Apparent Diffusion Coefficient Gradients, Andrea Evans, David G Mccormack, Giles Santyr, Grace Parraga
Medical Biophysics Publications
We measured hyperpolarized 3He magnetic resonance imaging (MRI) apparent diffusion coefficients (ADC) and quantified ADC gradients in each three-by-three voxel region of interest (ROI). Such local ADC gradients can be represented in vector maps showing the magnitude (|G3x3|) and direction of ADC gradients, providing a qualitative visualization tool and quantitative measurement of airway and air space heterogeneity. Twenty-four subjects (15 male, mean age=67+/-7 yr) with global initiative for chronic obstructive lung disease (GOLD) stage II (n=9, mean age 68+/-6 yr), GOLD stage III chronic obstructive pulmonary disease (COPD; n=7, mean age 67+/-8 yr), and age-matched healthy volunteers (n=8, mean age …
Quantification Of Carotid Vessel Wall And Plaque Thickness Change Using 3d Ultrasound Images, Bernard Chiu, Micaela Egger, J David Spence, Grace Parraga, Aaron Fenster
Quantification Of Carotid Vessel Wall And Plaque Thickness Change Using 3d Ultrasound Images, Bernard Chiu, Micaela Egger, J David Spence, Grace Parraga, Aaron Fenster
Medical Biophysics Publications
Quantitative measurements of carotid plaque burden progression or regression are important in monitoring patients and in evaluation of new treatment options. 3D ultrasound (US) has been used to monitor the progression or regression of carotid artery plaques. This paper reports on the development and application of a method used to analyze changes in carotid plaque morphology from 3D US. The technique used is evaluated using manual segmentations of the arterial wall and lumen from 3D US images acquired in two imaging sessions. To reduce the effect of segmentation variability, segmentation was performed five times each for the wall and lumen. …
Freesurfer-Initiated Fully-Automated Subcortical Brain Segmentation In Mri Using Large Deformation Diffeomorphic Metric Mapping., Ali R Khan, Lei Wang, Mirza Faisal Beg
Freesurfer-Initiated Fully-Automated Subcortical Brain Segmentation In Mri Using Large Deformation Diffeomorphic Metric Mapping., Ali R Khan, Lei Wang, Mirza Faisal Beg
Brain and Mind Institute Researchers' Publications
Fully-automated brain segmentation methods have not been widely adopted for clinical use because of issues related to reliability, accuracy, and limitations of delineation protocol. By combining the probabilistic-based FreeSurfer (FS) method with the Large Deformation Diffeomorphic Metric Mapping (LDDMM)-based label-propagation method, we are able to increase reliability and accuracy, and allow for flexibility in template choice. Our method uses the automated FreeSurfer subcortical labeling to provide a coarse-to-fine introduction of information in the LDDMM template-based segmentation resulting in a fully-automated subcortical brain segmentation method (FS+LDDMM). One major advantage of the FS+LDDMM-based approach is that the automatically generated segmentations generated are …
Effects Of Early Gestation Gh Administration On Placental And Fetal Development In Sheep., Casey D Wright, Ryan J Orbus, Timothy Regnault, Russell V Anthony
Effects Of Early Gestation Gh Administration On Placental And Fetal Development In Sheep., Casey D Wright, Ryan J Orbus, Timothy Regnault, Russell V Anthony
Paediatrics Publications
Ovine GH (oGH) is synthesized in placental tissue during maximal placental growth and development. Our objectives were to localize oGH mRNA in the placenta, and study the impact of exogenous GH on twin pregnancies during the normal window (35-55 days of gestational age; dGA) of placental expression. In situ hybridization localized oGH mRNA in uterine luminal epithelium but not in tissues of fetal origin. While maternal GH and IGF-I concentrations were increased (P
Preimplantation Embryo Programming: Transcription, Epigenetics, And Culture Environment., Veronique Duranthon, Andrew J Watson, Patrick Lonergan
Preimplantation Embryo Programming: Transcription, Epigenetics, And Culture Environment., Veronique Duranthon, Andrew J Watson, Patrick Lonergan
Obstetrics & Gynaecology Publications
Preimplantation development directs the formation of an implantation- or attachment-competent embryo so that metabolic interactions with the uterus can occur, pregnancy can be initiated, and fetal development can be sustained. The preimplantation embryo exhibits a form of autonomous development fueled by products provided by the oocyte and also from activation of the embryo's genome. Despite this autonomy, the preimplantation embryo is highly influenced by factors in the external environment and in extreme situations, such as those presented by embryo culture or nuclear transfer, the ability of the embryo to adapt to the changing environmental conditions or chromatin to become reprogrammed …
Chronic Late-Gestation Hypoglycemia Upregulates Hepatic Pepck Associated With Increased Pgc1alpha Mrna And Phosphorylated Creb In Fetal Sheep., Paul J Rozance, Sean W Limesand, James S Barry, Laura D Brown, Stephanie R Thorn, Dan Loturco, Timothy Regnault, Jacob E Friedman, William W Hay
Chronic Late-Gestation Hypoglycemia Upregulates Hepatic Pepck Associated With Increased Pgc1alpha Mrna And Phosphorylated Creb In Fetal Sheep., Paul J Rozance, Sean W Limesand, James S Barry, Laura D Brown, Stephanie R Thorn, Dan Loturco, Timothy Regnault, Jacob E Friedman, William W Hay
Paediatrics Publications
Hepatic glucose production is normally activated at birth but has been observed in response to experimental hypoglycemia in fetal sheep. The cellular basis for this process remains unknown. We determined the impact of 2 wk of fetal hypoglycemia during late gestation on enzymes responsible for hepatic gluconeogenesis, focusing on the insulin-signaling pathway, transcription factors, and coactivators that regulate gluconeogenesis. Hepatic phosphoenolpyruvate carboxykinase and glucose-6-phosphatase mRNA increased 12-fold and 7-fold, respectively, following chronic hypoglycemia with no change in hepatic glycogen. Chronic hypoglycemia decreased fetal plasma insulin with no change in glucagon but increased plasma cortisol 3.5-fold. Peroxisome proliferator-activated receptor-gamma coactivator-1alpha mRNA …