In vivo increase of the human lens equatorial diameter during accommodation

1996 ◽  
Vol 271 (3) ◽  
pp. R670-R676 ◽  
Author(s):  
R. A. Schachar ◽  
C. Tello ◽  
D. P. Cudmore ◽  
J. M. Liebmann ◽  
T. D. Black ◽  
...  
Keyword(s):  
High Resolution ◽  
Comparative Studies ◽  
Human Subjects ◽  
Human Lens ◽  
Small Displacement ◽  
Ultrasound Images ◽  
Video Images ◽  
Equatorial Diameter ◽  
Eye Rotation

The movement of the human lens equator during accommodation was examined in vivo. High-resolution ultrasound images of the lens equator were obtained from young human subjects whose amplitude of accommodation was controlled with 1% tropicamide and 2% pilocarpine. To avoid errors that otherwise arise from eye rotation or other movement, the cornea and sclera were used as positional references in comparative studies of the video images obtained from the unaccommodated and accommodated states. During accommodation, the movement at the lens equator involved small displacement; i.e., < 100 microns, and the equator did not move anteriorly or posteriorly but peripherally toward the sclera. These results indicate that the lens equator is under increased zonular tension during accommodation, in contradiction to Helmholtz's widely accepted theory of accommodation.

Ultrasound Imaging Characterization of Soft Tissue Dynamics of the Seated Human Body

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Daisuke Yamada ◽  
Alperen Değirmenci ◽  
Robert D. Howe
Keyword(s):  
Ultrasound Imaging ◽  
Human Body ◽  
Human Subjects ◽  
Excitation Amplitude ◽  
Whole Body ◽  
Ultrasound Images ◽  
Body Dynamics ◽  
Excitation Pattern

Abstract To characterize the dynamics of internal soft organs and external anatomical structures, this paper presents a system that combines medical ultrasound imaging with an optical tracker and a vertical exciter that imparts whole-body vibrations on seated subjects. The spatial and temporal accuracy of the system was validated using a phantom with calibrated internal structures, resulting in 0.224 mm maximum root-mean-square (r.m.s.) position error and 13 ms maximum synchronization error between sensors. In addition to the dynamics of the head and sternum, stomach dynamics were characterized by extracting the centroid of the stomach from the ultrasound images. The system was used to characterize the subject-specific body dynamics as well as the intrasubject variabilities caused by excitation pattern (frequency up-sweep, down-sweep, and white noise, 1–10 Hz), excitation amplitude (1 and 2 m/s2 r.m.s.), seat compliance (rigid and soft), and stomach filling (empty and 500 mL water). Human subjects experiments (n = 3) yielded preliminary results for the frequency response of the head, sternum, and stomach. The method presented here provides the first detailed in vivo characterization of internal and external human body dynamics. Tissue dynamics characterized by the system can inform design of vehicle structures and adaptive control of seat and suspension systems, as well as validate finite element models for predicting passenger comfort in the early stages of vehicle design.

scholarly journals High Resolution Ultrasound of Fillers and Their Implications in Aesthetic Medicine: A Study in Human Cadavers

2021 ◽  
Vol 6 (2) ◽  
Keyword(s):  
High Resolution ◽  
Silicone Oil ◽  
Calcium Hydroxyapatite ◽  
Filler Materials ◽  
Ultrasound Images ◽  
Ultrasound Evaluation ◽  
Liquid Silicone ◽  
Human Cadavers ◽  
And Behavior

The use of fillers for cosmetic or therapeutic purposes is very common and it’s increasing daily. Although it’s true that in most cases the results are as expected, the use of these substances is not free from the development of complications, even when it’s performed by highly trained medical physicians. On the other hand, these substances can be used indiscriminately by untrained personnel leading to a serious public health complication known as iatrogenic allogenosis, which leads to problems related to malpractice. Most of the time, professionals are consulted for a second opinion regarding the use of these substances, because use of these substances might be unknown due to the patients denying or forgetting the use of these. The presence of a previous unknown filler in aesthetic areas that require treatment may trigger severe or irreversible reactions, especially if non-absorbable fillers were injected. High resolution ultrasound is an extremely useful diagnostic tool for the identification of fillers. In this paper we will describe the ultrasound appearance of hyaluronic acid, calcium hydroxyapatite, liquid silicone, silicone oil, biopolymers, and Polymethylmethacrylate (PPMA) and then we compare it with it’s reported appearance in previous studies. The injection of the substances was carried out in human cadavers with the intention of gathering ultrasound images as similar to the imaging behavior of these substances in vivo. The obtained images can be used as precise references in the ultrasound evaluation, diagnosis, follow-up and behavior of the filler materials in the benefit of a comprehensive approach in the management of patients.

scholarly journals Versatility of high resolution ultrasonography in the assessment of granulomas and radicular cysts: a comparative in vivo study

2019 ◽  
Vol 48 (6) ◽  
pp. 20190082 ◽  
Author(s):  
Gül Sönmez ◽  
Kıvanç Kamburoğlu ◽  
Funda Yılmaz ◽  
Cemre Koç ◽  
Emre Barış ◽  
...  
Keyword(s):  
High Resolution ◽  
Root Canal ◽  
Statistical Significance ◽  
Root Canal Treatment ◽  
Histopathological Analysis ◽  
Ultrasound Images ◽  
Diagnostic Potential ◽  
Pre Treatment ◽  
Periapical Radiography

Objectives: To evaluate and compare the diagnostic potential of high resolution ultrasound with periapical radiographs (PR) and CBCT in assessing granulomas and radicular cysts. Methods: This study included a total of 33 teeth from 33 patients with periapical lesions. Subjects were distributed among three groups. A consisted of teeth that were extracted. B consisted of teeth treated with root-canal treatment followed by apical surgery. C consisted of teeth treated with root-canal treatment only. Pre-treatment PR, ultrasound and CBCT images were obtained for Groups A, B and C and 6 month post-treatment PR and ultrasound images were obtained for Groups B and C. In addition, histopathological analysis was performed on lesions in Groups A and B. Lesions were classified as either cystic lesions or granulomas. Width, height, depth, surface area and volume of lesions were measured using the built-in softwares of the appropriate imaging modalities. Measurements were compared by Wilcoxon and paired sample t tests. Ultrasound and histopathological findings were compared with κ and Mc Nemar. Statistical significance was set at p < 0.05. Results: κ coefficient (0.667; p = 0.002) suggested good agreement between ultrasound and histopathology. No statistically significant differences were found among periapical radiography, CBCT and ultrasound in the pre-treatment measurements of lesion width ( p = 0.308) or between CBCT and periapical radiography in the pre-treatment measurements of lesion height ( p = 0.863). In all cases, mean measurement values for all variables were lower for ultrasound than for CBCT. Conclusion: Ultrasound provided useful information for the diagnosis and assessment of granulomas and radicular cysts.

scholarly journals The Membranous Labyrinth in vivo from high-resolution Temporal CT data

2018 ◽  
Author(s):  
Hisaya Tanioka
Keyword(s):  
High Resolution ◽  
Inner Ear ◽  
Human Subjects ◽  
Membranous Labyrinth ◽  
3D Images ◽  
Temporal Bone Ct ◽  
Normal Human ◽  
Ct Data ◽  
Good Agreement

A prerequisite for the modeling and understanding of the inner ear mechanics needs the accurate created membranous labyrinth. I present a semi-automated methodology for accurate reconstruction of the membranous labyrinth in vivo from high-resolution temporal bone CT data of normal human subjects. I created the new technique which was combined with the segmentation methodology, transparent, thresholding, and opacity curve algorithms. This technique allowed the simultaneous multiple image creating without any overlapping regions in the inner ear has been developed. The reconstructed 3D images improved the membranous labyrinth geometry to realistically represent physiologic dimensions. These generated membranous structures were in good agreement with the published ones, while this approach was the most realistic in terms of the membranous labyrinth. The precise volume rendering depends on proprietary algorithms so that different results can be obtained, and the images appear qualitatively different. For each anatomical question, a different visualization technique should be used to obtain an optimal result. All scientists can create the membranous labyrinth in vivo in real time like a retinal camera.

Performance Evaluation of Adaptive Imaging Based on Multiphase Apodization with Cross-correlation: A Pilot Study in Abdominal Ultrasound

2018 ◽  
Vol 40 (4) ◽  
pp. 195-214
Author(s):  
Junseob Shin ◽  
Yu Chen ◽  
Harshawn Malhi ◽  
Frank Chen ◽  
Jesse Yen
Keyword(s):  
Cross Correlation ◽  
Human Subjects ◽  
Vena Cava ◽  
Ultrasound Image ◽  
Abdominal Ultrasound ◽  
Image Contrast ◽  
Ultrasound Images ◽  
Adaptive Imaging ◽  
Weighting Matrix

Degradation of image contrast caused by phase aberration, off-axis clutter, and reverberation clutter remains one of the most important problems in abdominal ultrasound imaging. Multiphase apodization with cross-correlation (MPAX) is a novel beamforming technique that enhances ultrasound image contrast by adaptively suppressing unwanted acoustic clutter. MPAX employs multiple pairs of complementary sinusoidal phase apodizations to intentionally introduce grating lobes that can be used to derive a weighting matrix, which mostly preserves the on-axis signals from tissue but reduces acoustic clutter contributions when multiplied with the beamformed radio-frequency (RF) signals. In this paper, in vivo performance of the MPAX technique was evaluated in abdominal ultrasound using data sets obtained from 10 human subjects referred for abdominal ultrasound at the USC Keck School of Medicine. Improvement in image contrast was quantified, first, by the contrast-to-noise ratio (CNR) and, second, by the rating of two experienced radiologists. The MPAX technique was evaluated for longitudinal and transverse views of the abdominal aorta, the inferior vena cava, the gallbladder, and the portal vein. Our in vivo results and analyses demonstrate the feasibility of the MPAX technique in enhancing image contrast in abdominal ultrasound and show potential for creating high contrast ultrasound images with improved target detectability and diagnostic confidence.

Pharmacological treatment with L-DOPA may reduce striatal dopamine transporter binding in in vivo imaging studies

2016 ◽  
Vol 55 (01) ◽  
pp. 21-28 ◽  
Author(s):  
C. Antke ◽  
H. Hautzel ◽  
H.-W. Mueller ◽  
S. Nikolaus
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Binding Sites ◽  
Human Subjects ◽  
Synaptic Cleft ◽  
Presynaptic Terminal ◽  
Imaging Studies ◽  
Psychiatric Conditions ◽  
Da Release

SummaryNumerous neurologic and psychiatric conditions are treated with pharmacological compounds, which lead to an increase of synaptic dopamine (DA) levels. One example is the DA precursor L-3,4-dihydroxyphenylalanine (L-DOPA), which is converted to DA in the presynaptic terminal. If the increase of DA concentrations in the synaptic cleft leads to competition with exogenous radioligands for presynaptic binding sites, this may have implications for DA transporter (DAT) imaging studies in patients under DAergic medication.This paper gives an overview on those findings, which, so far, have been obtained on DAT binding in human Parkinson’s disease after treatment with L-DOPA. Findings, moreover, are related to results obtained on rats, mice or non-human primates. Results indicate that DAT imaging may be reduced in the striata of healthy animals, in the unlesioned striata of animal models of unilateral Parkinson’s disease and in less severly impaired striata of Parkinsonian patients, if animal or human subjects are under acute or subchronic treatment with L-DOPA. If also striatal DAT binding is susceptible to alterations of synaptic DA levels, this may allow to quantify DA reuptake in analogy to DA release by assessing the competition between endogenous DA and the administered exogenous DAT radioligand.

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