Technical note: Development and evaluation of a standardized technique to assess blood perfusion in teats of dairy cows using power Doppler ultrasonography.

Ample research has described the assessment of dimensional changes for different teat traits, whereas diagnostic techniques to reliably assess blood circulation in teats of dairy cows are limited. Here, we describe the development and evaluation of a scanning technique to quantify blood flow in teats of dairy cows using power Doppler ultrasonography. In 2 consecutive trials, 384 teat scans [trial 1, n = 256 (sagittal plane, n = 128; transverse plane, n = 128); trial 2, n = 128 (transverse plane)] from 16 cows were obtained by the same 2 operators. Perfusion intensity from single images (trial 1) and video images (trial 2) were assessed using a commercially available software program. Intraclass correlation coefficients (ICC) and concordance correlation coefficients (CCC) were used to assess interoperator reproducibility (agreement between measurements performed by different operators) and intraoperator repeatability (agreement between measurements performed by the same operator). In trial 1, interoperator ICC and CCC indicated poor agreement (ICC ≤0.26, CCC ≤0.26). Intraoperator ICC and CCC demonstrated poor agreement between duplicate measurements within operators (ICC ≤0.19, CCC ≤0.19). Modifications after trial 1 included (1) a different ultrasound device, (2) analysis of video clips rather than single images, (3) restriction to 1 sectional plane (i.e., transverse), and (4) a scanning sequence such that repeated scans within operators were measured one after another. Through these modifications, intraoperator repeatability in trial 2 yielded fair to good agreement, with intraoperator ICC and CCC over both operators ranging from 0.44 to 0.70 and from 0.57 to 0.69, respectively, whereas interoperator ICC and CCC showed poor agreement (ICC = 0.35, CCC = 0.34). We conclude that repeatable measurements of blood perfusion intensity of teats in dairy cows can be attained with power Doppler ultrasonography. Power Doppler ultrasonography is a suitable tool to quantify slow flow in small vessels and may be an acceptable diagnostic technique to assess changes in blood circulation that result from machine milking in teats of dairy cows, although further research is necessary to validate this hypothesis.

Color-Doppler sonographic tissue perfusion measurements reveal significantly diminished renal cortical perfusion in kidneys with vesicoureteral reflux.

Vesicoureteral reflux (VUR) and its sequelae may lead to reduced renal perfusion and loss of renal function. Methods to describe and monitor tissue perfusion are needed. We investigated dynamic tissue perfusion measurement (DTPM) with the PixelFlux-software to measure microvascular changes in the renal cortex in 35 children with VUR and 28 healthy children. DTPM of defined horizontal slices of the renal cortex was carried out. A kidney was assigned to the "low grade reflux"-group if the reflux grade of the voiding cystourethrogram was 1 to 3 and to the "high grade reflux"-group if the reflux grade was 4 to 5. Kidneys with VUR showed a significantly reduced cortical perfusion. Compared to healthy kidneys, this decline reached in low and high grade refluxes within the proximal 50% of the cortex: 3% and 12 %, in the distal 50% of the cortex: 21% and 44 % and in the most distal 20 % of the cortex 41% and 44%. DTPM reveals a perfusion loss in kidneys depending on the degree of VUR, which is most pronounced in the peripheral cortex. Thus, DTPM offers the tool to evaluate microvascular perfusion, to help planning treatment decisions in children with VUR.

Color Doppler sonographic dynamic tissue perfusion measurement demonstrates significantly reduced cortical perfusion in children with diabetes mellitus type 1 without microalbuminuria and apparently healthy kidneys.

MOTIVATION: With respect to the devastating consequences of the increasing prevalence of diabetes mellitus, the main reason for end stage renal disease and dialysis in industrialized countries, and the very limited diagnostic and therapeutic possibilities to predict, monitor and prevent diabetic nephropathy (DN), new concepts for early recognition and quantification of the prevailing microvascular changes in DN are urgently needed. MATERIALS AND METHODS: We present the first study of renal cortical tissue perfusion measurement by means of standardized color Doppler sonographic videos evaluated with the PixelFlux software 1 for Dynamic Tissue Perfusion Measurement (DTPM) in 92 patients with DM1 without MA compared to 71 healthy probands. RESULTS: DTPM reveals a highly significant diminution of cortical perfusion in patients with DM1 compared to healthy probands by 31 %, most pronounced in the distal hemicortex (reduction by 50 %) compared to 21 % within the proximal hemicortex. CONCLUSION: Thus, DTPM offers a novel means of numerically describing the state of the renal microvasculature in DM in a patient-friendly, non-invasive, non-ionizing manner.

Pixelwise quantification of placental perfusion visualized by 3D power Doppler sonography.

PURPOSE: We present a new method for noninvasive automatic measurement of perfusion intensity (PixelFlux method) in standardized 3 D power Doppler sonography to quantify differences of perfusion intensities among different placental layers. MATERIALS AND METHODS: Power Doppler sonographic videos of anterior and central placentas were recorded at various gestational ages (13 to 38 weeks) under defined conditions in 22 women with uncomplicated pregnancies which ended in the delivery of an appropriately grown fetus. Tissue perfusion intensity in four placental layers was calculated as the product of the Doppler amplitude and the perfused area encoded by power Doppler signals related to the area of the respective layer. Measurements are given as the percentage of maximal possible perfusion. RESULTS: Significant differences in placental perfusion intensities in the uterine wall (6.6 %), the maternal flow within the intervillous space (2.4 %), the fetal flow within placental villi (1.6 %) and the chorionic plate (9.3 %) were demonstrated with a continuous increase in the uterine wall and the placental villi. CONCLUSION: Placental perfusion intensity was quantified noninvasively from 3 D power Doppler signal data in an easily accomplishable manner with a new software-based measurement procedure. There are significant differences in perfusion intensities among placental layers. Placenta perfusion measurement with the PixelFlux method is feasible and can discern significant perfusion differences among different placenta layers.

Three-dimensional volumetric spatially angle-corrected pixelwise fetal flow volume measurement.

PURPOSE: Early attempts to calculate fetal global perfusion used 2 D images. The results were not sufficiently reliable. That's why RI measurements are still in use despite the fact that they do not reflect the amount of blood passing through the fetus. We present a novel three-dimensional approach to overcome these limitations. MATERIALS AND METHODS: In 124 singleton pregnancies between the 23rd and 4st gestational week, a three-dimensional color Doppler sonographic record of the umbilical cord was made, resulting in 281 volume data sets. With dedicated software (PixelFlux) the spatial angle of the umbilical vein was calculated and the true global fetal perfusion was calculated from its horizontal transection as the product of the area of all pixels and the spatial angle-corrected velocity. To validate the PixelFlux technique, phantom flow measurements were carried out. RESULTS: Phantom flow measurements revealed a highly significant correlation of actual flow volumes and those measured by the PixelFlux technique (p < 0.001; rPearson = 0.987 - 0.991) with an even higher interobserver correlation (p < 0.001; rPearson = 0.997). We found a significant correlation of fetal volume flow to gestational age and weight (r = 0.529 at spatial angles below 30° to r = 0.724 at spatial angles below 5°) and a significant influence of the spatial angle on this correlation (p = 0.003; r = -0.865). CONCLUSION: Spatial angle-corrected global fetal perfusion measurement improves existing approaches to fetal perfusion evaluation, and is feasible, simple and fast. Thus, it can be recommended to explore the relationship of fetal perfusion and disturbances of fetal development.

Changes of renal flow volume in the hemolytic-uremic syndrome--color Doppler sonographic investigations.

Varying degrees of vascular occlusion can be found in the hemolytic-uremic syndrome (HUS). This is the rationale for Doppler sonographic investigations of renal blood flow in children with HUS. In 1989 a first report suggested a close relationship between normalization of the resistive index (RI) of renal blood flow with the restitution of urine flow in affected children. Later reports did not confirm these initial findings. The aim of this paper is to describe renal volume perfusion quantitatively in children with HUS. The renal arteries in 35 patients with HUS (1 month to 15 years) were investigated at the onset of HUS by color Doppler ultrasonography. Flow volume measurements were carried out in the 1st week and in the 2nd to 4th week after onset of the disease. These data were compared with measurements from a healthy pediatric population of 69 children. Statistically significant changes in renal perfusion occur in the flow volume of the kidneys. The flow volume dropped to 32% (34%) in the 1st week of the disease compared with the normal population and recovered in 2-4 weeks to 117% (65%) of the normal flow volume (left kidney in parentheses). The new technique of volumetric perfusion measurement overcomes some drawbacks of the traditional RI, which may have led to some confusion in the past.