Abstract
BackgroundDuring contrast enhanced ultrasound (CEUS), the features of the regions of interest (ROI) can affect the value of the perfusion-related parameters obtained from a time intensity curve (TIC). In veterinary medicine, conflicting have been reported on the influence of ROI size and location on renal CEUS. There are some disagreeing evidences regarding the optimal method for selecting ROI in quantitative analysis of renal perfusion using CEUS.The aim of this study was to evaluate the effect of the size and location of ROIs in the spleen of conscious dogs on perfusion variables determined using sulphur hexafluoride contrast-enhanced ultrasounds.ResultsA prospective observational study on 15 client-owned mixed-breed adult dogs was performed using a system equipped with contrast-tuned imaging technology. Qualitative and quantitative assessments of the spleen enhancement pattern were carried out. Three square ROIs (0.05 cm2) were manually drawn in a row and spaced 1 mm apart, placing adjacent ROIs at three different depths. Three medium rectangular ROIs (0.3 cm2) include the 3 smallest ROIs in each row, indicated by the letters A, B and C, and a single large square ROI (1 cm2) was drawn containing all previous ROIs. Software analysis of time-intensity curves generated within each ROI allowed us to calculate the perfusion-related parameters: peak enhancement, time to peak, regional blood flow, mean transit time and regional blood volume.The coefficient of variation for all blood-related parameters was always lower in the larger ROI than in the other smaller ROIs. ROI A and B, positioned proximally and medially, levels respectively, showed similar coefficients of variation to the largest ROI. The analysis of variance model exhibited a significant effect of location and size of the ROIs in the quantitative analysis of canine spleen perfusion, with a reduction of perfusion-related parameters in the distal ROI.ConclusionsThe recommendation for a quantitative CEUS examination of a dog’s spleen is to analyze splenic perfusion by drawing a sufficiently large ROI proximal to the ultrasound beam on the splenic parenchyma. This may be of clinical relevance in the diagnosis of splenic diseases.
Highlights
During contrast enhanced ultrasound (CEUS), the features of the regions of interest (ROI) can affect the value of the perfusion-related parameters obtained from a time intensity curve (TIC)
Brightness and its distribution inside a ROI are analyzed in order to describe typical enhancement patterns for a tissue or lesion compared to the adjacent tissue and to obtain the perfusion-related parameters calculated from time intensity curves (TICs) in a selected ROI [1]
The goal of this study was to evaluate the effect of the ROI size and location on perfusion-related parameters in the spleen in not-sedated dogs, based on the hypothesis that the ROI variables would significantly affect the mean value of canine splenic perfusionrelated parameters
Summary
During contrast enhanced ultrasound (CEUS), the features of the regions of interest (ROI) can affect the value of the perfusion-related parameters obtained from a time intensity curve (TIC). Contrast-enhanced ultrasound (CEUS) is an imaging technique useful to obtain a reliable quantification of tissue perfusion based on region of interest (ROI) analysis. It is performed by injecting into the bloodstream gasfilled microbubbles, stabilized by an outer shell; these microbubbles cause an enhancement of the microcirculation, providing the quali-quantitative assessment of perfusion changes in an organ or tissue in real-time [1]. Data obtained with this method need to be processed with a dedicated software that allows to analyze signals from the blood-pool agents without background noise. Brightness and its distribution inside a ROI are analyzed in order to describe typical enhancement patterns for a tissue or lesion compared to the adjacent tissue and to obtain the perfusion-related parameters calculated from time intensity curves (TICs) in a selected ROI [1]
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