The Relationship between the 24-hour Fluctuations in Schlemm’s Canal and Intraocular Pressure: An Observational Study using High-Frequency Ultrasound Biomicroscopy

Objective: Ultrasound BioMicroscopy (UBM), or high-frequency ultrasound, is a novel technique used for assessment of anatomy and physiology small research animals. In this study, we evaluate the UBM assessment of the re-endothelialization process following denudation of the carotid artery in rats. Methods: Ultrasound BioMicroscopy data from three different experiments were analyzed. A total of 66 rats of three different strains (Sprague-Dawley, Wistar and Goto-Kakizaki) were included in this study. All animals were subjected to common carotid artery balloon injury and examined with UBM 2 and 4 weeks after injury. Re-endothelialization in UBM was measured as the length from the carotid bifurcation to the distal edge of the intimal hyperplasia. En face staining with Evans-blue dye was performed upon euthanization at 4 weeks after injury followed by tissue harvest for morphological and immunohistochemical evaluation. Results: A significant correlation (Spearman r=0.63,p<0.0001) and an agreement according to Bland-Altman test was identified when comparing all measurements of re-endothelialization in high frequency ultrasound and en face staining. Analysis by animal strain revealed a similar pattern and a significant growth in re-endothelialization length measured in UBM from 2 to 4 weeks could be identified. Immunohistochemical staining for von Willebrand factor confirmed the presence of endothelium in the areas detected as re-endothelialized by the ultrasound assessment. Conclusion: Ultrasound BioMicroscopy can be used for longitudinal in vivo assessment of the re-endothelialization following arterial injury in rats.

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High-Frequency Ultrasound Biomicroscopy of the Anterior Segment Morphometry before and Immediately after Pars Plana Vitrectomy

European Journal of Ophthalmology ◽

10.5301/ejo.2010.4949 ◽

2011 ◽

Vol 21 (2) ◽

pp. 173-178 ◽

Cited By ~ 12

Author(s):

Meira Neudorfer ◽

Nir Oren ◽

Adiel Barak

Keyword(s):

High Frequency ◽

Pars Plana Vitrectomy ◽

Anterior Segment ◽

Ultrasound Biomicroscopy ◽

High Frequency Ultrasound ◽

Pars Plana ◽

Frequency Ultrasound

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Intraocular Pressure–dependent Corneal Elasticity Measurement Using High-frequency Ultrasound

Ultrasonic Imaging ◽

10.1177/0161734619858386 ◽

2019 ◽

Vol 41 (5) ◽

pp. 251-270 ◽

Cited By ~ 4

Author(s):

Laurentius O. Osapoetra ◽

Dan M. Watson ◽

Stephen A. McAleavey

Keyword(s):

Intraocular Pressure ◽

High Resolution ◽

High Frequency ◽

Wave Speed ◽

Biomechanical Properties ◽

Single Element ◽

High Frequency Ultrasound ◽

Spatially Resolved ◽

Corneal Biomechanical Properties ◽

Frequency Ultrasound

Measurement of corneal biomechanical properties can aid in predicting corneal responses to diseases and surgeries. For delineation of spatially resolved distribution of corneal elasticity, high-resolution elastography system is required. In this study, we demonstrate a high-resolution elastography system using high-frequency ultrasound for ex-vivo measurement of intraocular pressure (IOP)-dependent corneal wave speed. Tone bursts of 500 Hz vibrations were generated on the corneal surface using an electromagnetic shaker. A 35-MHz single-element transducer was used to track the resulting anti-symmetrical Lamb wave in the cornea. We acquired spatially resolved wave speed images of the cornea at IOPs of 7, 11, 15, 18, 22, and 29 mmHg. The IOP dependence of corneal wave speed is apparent from these images. Statistical analysis of measured wave speed as a function of IOP revealed a linear relation between wave speed and IOP cs = 0.37 + 0.22 × IOP, with the coefficient of determination R2 = 0.86. We also observed depth-dependent variations of wave speed in the cornea, decreasing from anterior toward posterior. This depth dependence is more pronounced at higher IOP values. This study demonstrates the potential of high-frequency ultrasound elastography in the characterization of spatially resolved corneal biomechanical properties.

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High frequency ultrasound assessment of systemic sclerosis skin involvement: intra-observer repeatability and relationship with clinician assessment and dermal collagen content

The Journal of Rheumatology ◽

10.3899/jrheum.200234 ◽

2020 ◽

pp. jrheum.200234

Author(s):

Victoria A. Flower ◽

Shaney L. Barratt ◽

Darren J. Hart ◽

Amanda B. Mackenzie ◽

Jacqueline A. Shipley ◽

...

Keyword(s):

Systemic Sclerosis ◽

High Frequency ◽

Convergent Validity ◽

Objective Assessment ◽

Collagen Content ◽

Skin Thickness ◽

High Frequency Ultrasound ◽

Dermal Collagen ◽

The Relationship ◽

Frequency Ultrasound

Objective The modified Rodnan skin score (mRSS) remains the preferred method for skin assessment in systemic sclerosis (SSc). There are concerns regarding high inter-observer variability of mRSS and negative clinical trials utilising mRSS as the primary endpoint. High frequency ultrasound (HFUS) allows objective assessment of cutaneous fibrosis in SSc. We investigated the relationship between HFUS with both mRSS and dermal collagen. Methods Skin thickness (ST), echogenicity and novel Shear wave elastography (SWE) were assessed in 53 SSc patients and 15 healthy controls (HC) at the finger, hand, forearm and abdomen. The relationship between HFUS parameters with mRSS (n=53) and dermal collagen (10 SSc patients and 10 HC) was investigated. Intra-observer repeatability of HFUS was calculated using intra-class correlation coefficients (ICCs). Results HFUS assessment of ST (hand/forearm) and SWE (finger/hand) correlated with local mRSS at some sites. Subclinical abnormalities in ST, echogenicity and SWE were present in clinically uninvolved SSc skin. Additionally, changes in echogenicity and SWE were sometimes apparent despite objectively normal ST on HFUS. ST, SWE and local mRSS correlated strongly with collagen quantification (rho 0.697, 0.709, 0.649 respectively). Intra-observer repeatability was high for all HFUS parameters (ICCs for ST 0.946-0.978, echogenicity 0.648- 0.865 and SWE 0.953-0.973). Conclusion Our data demonstrates excellent reproducibility and reassuring convergent validity with dermal collagen content. Detection of subclinical abnormalities is an additional benefit of HFUS. The observed correlations with collagen quantification support further investigation of HFUS as an alternative to mRSS in clinical trial settings.

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