The Effect of the Sample Size and Location on Contrast Ultrasound Measurement of Perfusion Parameters

Abstract

Contrast-enhanced ultrasound can be used to quantify tissue perfusion based on region of interest (ROI) analysis. The effect of the location and size of the ROI on the obtained perfusion parameters has been described in phantom, ex vivo and in vivo studies. We assessed the effects of location and size of the ROI on perfusion parameters in the renal cortex of 10 healthy, anesthetized cats using Definity s contrast-enhanced ultrasound to estimate the importance of the ROI on quantification of tissue perfusion with contrast-enhanced ultrasound. Three separate sets of ROIs were placed in the renal cortex, varying in location, size or depth. There was a significant inverse association between increased depth or increased size of the ROI and peak intensity (Po0.05). There was no statistically significant difference in the peak intensity between the ROIs placed in a row in the near field cortex. There was no significant difference in the ROIs with regard to arrival time, time to peak intensity and wash-in rate. When comparing two different ROIs in a patient with focal lesions, such as suspected neoplasia or infarction, the ROIs should always be placed at same depth and be as similar in size as possible. r

Contrast‐enhanced Ultrasonography of the Small Bowel in Healthy Cats

“…8 Several other factors, such as technical scanning variables, contrast medium characteristics, injection technique, and patient-related factors can influence quantitative variables. 2,5,8,[43][44][45][46] Peak intensity values were lower in comparison to those reported by others. 8 The use of different contrast media and different imaging system implies a different number of circulating microbubbles and, as a consequence, a different backscatter response from the tissue that influences the degree of contrast enhancement.…”

“…5,44,46 Because of these reasons, quantitative values obtained from different protocols are not entirely comparable. 2,5,8,[43][44][45][46] Fasting for at least 12 h before contrast-enhanced ultrasonography of the bowel is suggested to minimize the presence of gas and food particles 26 that create strong interference during the activation of the contrast-specific software. Furthermore, fasting is recommended to reduce the peristaltic activity 26 to avoid motion artefact that limits quantitative analysis.…”

Renal perfusion parameters measured by contrast‐enhanced ultrasound in healthy dogs demonstrate a wide range of variability in the long‐term

“…The area of the regions‐of‐interest was kept the same for all dogs at all time points. The regions‐of‐interest were kept approximately at the same depth at all time points . One large region‐of‐interest was used instead of averaging three smaller regions‐of‐interest in order to minimize the influence of local heterogeneity of perfusion .…”

Use of Contrast‐Enhanced Ultrasonography in Chronic Pathologic Canine Testes

“…For inhomogeneous lesions, two regions of interest (ROI) were drawn, one including the area of the lesion and the other including surrounding tissue. Attention was paid to draw ROIs equal in dimension and in depth (Leinonen et al 2011…”