Search results for "Image."
showing 10 items of 6790 documents
Three-dimensional distribution of trabecular bone density and cortical thickness in the distal humerus
2008
One major barrier to osteosynthesis in distal humeral fractures is poor bone quality. This study was an attempt to measure the bone quality in the distal humerus.We measured the distribution of total bone mineral density (BMD), trabecular BMD (tBMD), and cortical thickness (CTh) in the distal humerus using peripheral quantitive computed tomography. Four slices in the infracondylar, supracondylar, and distal disphyseal regions of 25 human cadaver humeri were investigated.Total BMD decreased continuously from the distal diaphysis to the trochlea. Within the infracondylar region, the capitellum was the region of lowest tBMD and CTh (P.001). Measurements in anterior regions were higher than in …
Comparison of three accelerated pulse sequences for semiquantitative myocardial perfusion imaging using sensitivity encoding incorporating temporal f…
2007
Purpose To investigate the parallel acquisition technique sensitivity encoding incorporating temporal filtering (TSENSE) with three saturation-recovery (SR) prepared pulse sequences (SR turbo fast low-angle shot [SR-TurboFLASH], SR true fast imaging with steady precession [SR-TrueFISP], and SR-prepared segmented echo-planar-imaging [SR-segEPI]) for semiquantitative first-pass myocardial perfusion imaging. Materials and Methods In blood- and tissue-equivalent phantoms the relationship between signal intensity (SI) and contrast-medium concentration was evaluated for the three pulse sequences. In volunteers, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and normalized upslopes (N…
Training the Motor Cortex by Observing the Actions of Others During Immobilization
2014
International audience; Limb immobilization and nonuse are well-known causes of corticomotor depression. While physical training can drive the recovery from nonuse-dependent corticomotor effects, it remains unclear if it is possible to gain access to motor cortex in alternative ways, such as through motor imagery (MI) or action observation (AO). Transcranial magnetic stimulation was used to study the excitability of the hand left motor cortex in normal subjects immediately before and after 10 h of right arm immobilization. During immobilization, subjects were requested either to imagine to act with their constrained limb or to observe hand actions performed by other individuals. A third gro…
Mental Imagery Training Increases Wanting of Rewards and Reward Sensitivity and Reduces Depressive Symptoms.
2017
High reward sensitivity and wanting of rewarding stimuli help to identify and motivate repetition of pleasant activities. This behavioral activation is thought to increase positive emotions. Therefore, both mechanisms are highly relevant for resilience against depressive symptoms. Yet, these mechanisms have not been targeted by psychotherapeutic interventions. In the present study, we tested a mental imagery training comprising eight 10-minute sessions every second day and delivered via the Internet to healthy volunteers (N = 30, 21 female, mean age of 23.8 years, Caucasian) who were preselected for low reward sensitivity. Participants were paired according to age, sex, reward sensitivity, …
Single region of interest versus multislice T2* MRI approach for the quantification of hepatic iron overload.
2011
Purpose To evaluate the effectiveness of the single ROI approach for the detection of hepatic iron burden in thalassemia major (TM) patients in respect to a whole liver measurement. Materials and Methods Five transverse hepatic slices were acquired by a T2* gradient-echo sequence in 101 TM patients and 20 healthy subjects. The T2* value was calculated in a single region of interest (ROI) defined in the medium-hepatic slice. Moreover, the T2* value was extracted on each of the eight ROIs defined in the functionally independent segments. The mean hepatic T2* value was calculated. Results For patients, the mean T2* values over segments VII and VIII were significantly lower. This pattern was su…
Improved T2* assessment in liver iron overload by magnetic resonance imaging.
2009
In the clinical MRI practice, it is common to assess liver iron overload by T2* multi-echo gradient-echo images. However, there is no full consensus about the best image analysis approach for the T2* measurements. The currently used methods involve manual drawing of a region of interest (ROI) within MR images of the liver. Evaluation of a representative liver T2* value is done by fitting an appropriate model to the signal decay within the ROIs vs. the echo time. The resulting T2* value may depend on both ROI placement and choice of the signal decay model. The aim of this study was to understand how the choice of the analysis methodology may affect the accuracy of T2* measurements. A softwar…
Volumetry of Ventilated Airspaces by 3He MRI
2001
To develop a validated post-processing routine for volumetry of the ventilated airspaces by 3He MRI.3Helium MRI and pulmonary function tests were performed in seven healthy volunteers. After segmentation of ventilated airspaces, their volumes were calculated. Functional residual capacity (FRC) was used as a reference. For comparison of absolute volumes, correction factors were evaluated.Mean lung volume (+/- standard deviation) calculated from 3He MRI was 4,082 +/- 908 mL and mean FRC was 3,696 +/- 1166 mL, with a mean difference of 386 mL (r = 0.88). After correction for the relative pulmonary air content (factor 0.82), posture (0.72), and the individual tidal volume, 3He MRI volume was 3,…
Three-dimensional (3D) versus two-dimensional (2D) laparoscopic adrenalectomy: A case-control study
2016
Abstract Introduction Laparoscopic adrenalectomy is today considered the gold standard of treatment for adrenal tumors. The development of high definition cameras does not eliminate the major limitation of two-dimensional (2D) laparoscopy: lack of depth perception and loss of spatial orientation. Tree-dimensional (3D) HD laparoscopy was developed as an alternative to conventional 2D laparoscopy. Methods We report our experience with use of 3D vision system for laparoscopic adrenalectomy. Between January 2009 and March 2015 we performed a total of 52 laparoscopic adrenalectomies. In this case-control study we considered 13 laparoscopic adrenalectomies performed with three-dimensional (3D) vi…
Aging Affects the Mental Rotation of Left and Right Hands
2009
BACKGROUND:Normal aging significantly influences motor and cognitive performance. Little is known about age-related changes in action simulation. Here, we investigated the influence of aging on implicit motor imagery. METHODOLOGY/PRINCIPAL FINDINGS:Twenty young (mean age: 23.9+/-2.8 years) and nineteen elderly (mean age: 78.3+/-4.5 years) subjects, all right-handed, were required to determine the laterality of hands presented in various positions. To do so, they mentally rotated their hands to match them with the hand-stimuli. We showed that: (1) elderly subjects were affected in their ability to implicitly simulate movements of the upper limbs, especially those requiring the largest amplit…
Objective measurement of intraocular forward light scatter using Hartmann-Shack spot patterns from clinical aberrometers. Model-eye and human-eye stu…
2007
Purpose To apply software-based image-analysis tools to objectively determine intraocular scatter determined from clinically derived Hartmann-Shack patterns. Setting Aston Academy of Life Sciences, Aston University, Birmingham, United Kingdom, and Department of Optics, University of Valencia, Valencia, Spain. Methods Purpose-designed image-analysis software was used to quantify scatter from centroid patterns obtained using a clinical Hartmann-Shack analyzer (WASCA, Zeiss/Meditec). Three scatter values, as the maximum standard deviation within a lenslet for all lenslets in the pattern, were obtained in 6 model eyes and 10 human eyes. In the model-eye sample, patterns were obtained in 4 sessi…