22Author contribution: The project was formulated by SE and EAG, AAS and EAG established the 23 code for oxygen transport modelling with input from SE. SH developed the code and pipeline for 24 DTect, assisted by RWPK and TRA, who additionally optimised staining protocol for input into the 25 DTect packages. RWPK completed all animal work, while ALM and MK conducted all human 26 experiments and tissue collection. RWPK completed tissue processing, analysis and interpretation Abstract 37 Identifying structural limitations in O 2 transport is primarily restricted by current methods employed 38 to characterise the nature of physiological remodelling. Inadequate resolution or breadth of 39 available data has impaired development of routine diagnostic protocols and effective therapeutic 40 strategies. Understanding O 2 transport within striated muscle faces major challenges, most notably 41 in quantifying how well individual fibres are supplied by the microcirculation, which has 42 necessitated exploring tissue O 2 supply using theoretical modelling of diffusive exchange. Having 43identified capillary domains as a suitable model for the description of local O 2 supply, and requiring 44 less computation than numerically calculating the trapping regions that are supplied by each 45 capillary via biophysical transport models, we sought to design a high throughput method for 46 histological analysis. We present an integrated package that identifies optimal protocols for 47 identification of important input elements, processing of digitised images with semi-automated 48 routines, and incorporation of these data into a mathematical modelling framework with computed 49 output visualised as the tissue partial pressure of O 2 (PO 2 ) distribution across a biopsy sample. 50 Worked examples are provided using muscle samples from experiments involving rats and 51 humans. 52 53 Supply, DTect 55 56 New & Noteworthy: Progress in quantitative morphometry and analytical modelling have tended 57 to develop independently. Real diagnostic power lies in harnessing both disciplines within one 58user-friendly package. We present a semi-automated, high-throughput tool for determining muscle 59 phenotype from biopsy material, which also provides anatomically relevant input to quantify tissue 60 oxygenation, in a coherent package not previously available to non-specialist investigators. 61 65 angiogenesis) in striated muscle has been identified as a highly coordinated physiological process 66 (16), and being able to effectively explore the functional importance of targeted interventions or the 67 consequential effect of pathology on microvascular O 2 transport would be a valuable resource for 68 both basic science and translational investigations (46). In a muscle with uniform phenotype, such 69 as cardiac muscle, this presents a relatively straightforward problem that may be solved by 70 approximating a localised supply location (capillaries) and homogenous O 2 demand (fibre MO 2 ) in 71 modelling the outcome (2, 26, 27). In most skeletal musc...
Abstract-Simulation and experimental results from 3-D vector flow estimations for a 62+62 2-D row-column (RC) array with integrated apodization are presented. A method for implementing a 3-D transverse oscillation (TO) velocity estimator on a 3.0 MHz RC array is developed and validated. First, a parametric simulation study is conducted where flow direction, ensemble length, number of pulse cycles, steering angles, transmit/receive apodization, and TO apodization profiles and spacing are varied, to find the optimal parameter configuration. The performance of the estimator is evaluated with respect to relative mean biasB and mean standard deviationσ. Second, the optimal parameter configuration is implemented on the prototype RC probe connected to the experimental ultrasound scanner SARUS. Results from measurements conducted in a flow-rig system containing a constant laminar flow and a straight-vessel phantom with a pulsating flow are presented. Both an M-mode and a steered transmit sequence are applied. Three-dimensional vector flow is estimated in the flow-rig for four representative flow directions. In the setup with 90• beam-to-flow angle, the relative mean bias across the entire velocity profile is (-4.7, -0.9, 0.4)% with a relative standard deviation of (8.7, 5.1, 0.8)% for (vx, vy, vz). The estimated peak velocity is 48.5 cm/s ± 3.0 cm/s giving a -3% bias. The out-of-plane velocity component perpendicular to the cross section is used to estimate volumetric flow rates in the flow-rig at a 90• beam-to-flow angle. The estimated mean flow rate in this setup is 91.2 L/h ± 3.1 L/h corresponding to a bias of -11.1%. In a pulsating flow setup, flow rate measured during five cycles is 2.3 mL/stroke ± 0.1 mL/stroke giving a negative 9.7% bias. It is concluded that accurate 3-D vector flow estimation can be obtained using a 2-D RC addressed array.
In highly trained soccer players, additional speed endurance training is associated with an improved ability to perform repeated high-intensity work. To what extent the training-induced changes in V˙O2 kinetics and mechanical efficiency in type I fibers caused the improvement in performance warrants further investigation.
Current clinical ultrasound (US) systems are limited to show blood flow movement in either 1-D or 2-D. In this paper, a method for estimating 3-D vector velocities in a plane using the transverse oscillation method, a 32×32 element matrix array, and the experimental US scanner SARUS is presented. The aim of this paper is to estimate precise flow rates and peak velocities derived from 3-D vector flow estimates. The emission sequence provides 3-D vector flow estimates at up to 1.145 frames/s in a plane, and was used to estimate 3-D vector flow in a cross-sectional image plane. The method is validated in two phantom studies, where flow rates are measured in a flow-rig, providing a constant parabolic flow, and in a straight-vessel phantom ( ∅=8 mm) connected to a flow pump capable of generating time varying waveforms. Flow rates are estimated to be 82.1 ± 2.8 L/min in the flow-rig compared with the expected 79.8 L/min, and to 2.68 ± 0.04 mL/stroke in the pulsating environment compared with the expected 2.57 ± 0.08 mL/stroke. Flow rates estimated in the common carotid artery of a healthy volunteer are compared with magnetic resonance imaging (MRI) measured flow rates using a 1-D through-plane velocity sequence. Mean flow rates were 333 ± 31 mL/min for the presented method and 346 ± 2 mL/min for the MRI measurements.
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