Color Doppler dynamic tissue perfusion measurement: a novel tool in the assessment of renal parenchymal perfusion in children with vesicoureteral reflux.

INTRODUCTION: Vesicoureteral reflux (VUR) occurs in 20-50% of children suffering from recurrent urinary tract infections (UTIs) and is associated with an increased risk of renal scarring and impaired renal function. Early detection of renal perfusion deterioration would allow for the implementation of more aggressive treatment and potentially prevent further damage to the renal parenchyma. The aim of the study was to assess renal parenchymal perfusions in children with recurrent UTIs with and without coexisting VUR, and compare the findings with the results of healthy patients. MATERIAL AND METHODS: Color Doppler sonographic dynamic renal parenchymal perfusion measurements were performed with PixelFlux (Chameleon-Software, Germany) software in 77 children with recurrent UTIs and coexisting VUR and in 30 children with UTIs without VUR. The findings were compared with the results of 53 healthy children. RESULTS: Cortical parenchymal perfusion of children suffering from UTIs and VUR was significantly reduced when compared to the control group. Statistically significant differences (p < 0.05) were found in all perfusion parameters (i.e. mean velocity (v mix ), mean perfused area (A mix ), mean perfusion intensity (I mix ), tissue pulsatility index (TPI), and tissue resistance index (TRI)) between the control group and children suffering from UTIs and VUR, particularly VUR grades III and IV. There were no significant differences between the UTI group and the control group. No differences were found between the controls and VUR grade II. CONCLUSIONS: Renal parenchymal perfusion decreases significantly with higher grades of VUR.

Quantitative software analysis of ultrasonographic textures in experimental testicular torsion.

AIM: Ultrasonography (US) has high diagnostic value in testicular torsion but is vulnerable to several potential errors, especially in the early period. Echotexture (ETX) analysis software provides a numerical expression of B-mode images and allows quantitative evaluation of blood flow due to ischemic damage using power Doppler US (PDUS) analysis. Our aim in this study was to determine the diagnostic value and effective parameters of EXT analysis software in the early period of torsion using B-mode and PDUS images. MATERIALS AND METHODS: In this study, eight rats were used. Following anesthesia, the right testis was rotated to a 1080-degree counterclockwise position whereas the left testis was left in place to have a control group. B-mode and PDUS images of both sides were recorded with a portable US device immediately (0 hour) and 1 and 2 hours after torsion. The B-mode images were analyzed in terms of gradient, homogeneity, and contrast using the BS200pro software (BAB Digital Imaging System 2007, Ankara, Turkey). Intensity (I)-red and area (A)-red values were measured on PDUS images with the Pixelflux (Version 1.0, Chameleon-Software, Leipzig, Germany). The data were evaluated by the Mann-Whitney U and Wilcoxon tests. RESULTS: Data from B-mode US image EXT analysis showed no significant difference between the right and left testicles in 0 to 2 hours (p > 0.05). The values obtained from PDUS analysis (I-red and A-red) significantly decreased at the testicular torsion side at the end of the second hour (p < 0.05). I-red and A-red values at 0 to 1 hour of torsion indicated similar blood flow alterations (p > 0.05) whereas the flow was significantly lower at 2 hours (p < 0.05). CONCLUSION: In experimental testicular torsion, ischemic changes can be detected by PDUS power/angio mode using blood flow alterations as early as the second hour. Tissue damage cannot be evaluated within the first 2 hours of torsion with B-mode ETX analysis.

Quantitative assessment of urethral vascularity in nulliparous females using high-frequency endovaginal ultrasonography.

PURPOSE: To assess the vascular parameters in the urethra of nulliparous females and to compare the vascularity among various parts of the urethra, using high-frequency endovaginal ultrasonography (EVUS). METHODS: Twenty-two nulliparous women, mean age 27 years, underwent EVUS using a biplane transducer at 12 MHz frequency. Color Doppler examinations of the urethra were recorded and further evaluated off-line using special software (Pixel Flux) for quantitative assessment of the vascularity. The urethra was divided into four regions of interest (ROIs) in the midsagittal plane and three ROIs in the axial plane. The following parameters were measured: velocity (V), perfused area (A), perfusion intensity (I), pulsatility index (PI), and resistance index (RI). Interobserver and intraobserver reproducibility analysis was also performed. RESULTS: In midsagittal plane, the midurethra presented the highest value of V and lowest value of A. The intramural part showed the lowest value of I and the highest values of RI and PI. In the distal urethra, the highest value of I and the lowest value of RI was seen. In the axial plane, the values of V, A, and I were statistically significantly higher in the external part of the midurethra compared with the internal part. Excellent interobserver and intraobserver reproducibility was shown in the majority of parameters for the entire urethra. CONCLUSIONS: Vascularity differs in different parts of the urethra. Pixel Flux is a valuable tool for providing reproducible quantitative analysis of vascular parameters for the entire urethra.

Tissue pulsatility index: a new parameter to evaluate renal transplant perfusion.

BACKGROUND: : Chronic allograft nephropathy (CAN) is characterized by loss of parenchymal perfusion. We applied therefore the novel parameter Tissue Pulsatility Index (TPI) to quantify transplant perfusion in the long-term surveillance of renal transplants. METHODS: : Color Doppler sonographic videos of renal transplants from 38 renal transplant recipients were recorded under defined conditions. TPI was calculated as ratio of the difference of mean systolic and diastolic velocities of the entire region and the average velocity. RESULTS: : TPI was significantly different between the proximal and distal cortical layers (1.12 vs. 1.56, respectively P=0.000). In patients with elevated creatinine as a measure of compromised function, significantly (P=0.016) higher values (TPI=1.70) were found at distal cortical level compared to patients with normal creatinine (TPI=1.34). After transplantation, TPI rises significantly: 1.10 in 0-1 years vs. 1.41 in 1-2.9 years, P=0.002; 1.10 in 0-1 years vs. 1.37 in 3-4.9 years, P=0.000; 1.10 in 0-1 years vs. 1.31 in 7-8.9 years, P=0.049). TPI declines later on in our population to significantly lowered values in the group more than 9 years after transplantation (1.10 in 0-1 years vs. 0.94 in >9 years, P=0.044). CONCLUSION: : With the novel TPI, we could demonstrate significant differences between proximal and distal cortical perfusion, between compromised and well-functioning transplants, and could observe significant changes of transplant perfusion at various points at the posttransplantation time scale.

Dynamic tissue perfusion measurement: a novel tool in follow-up of renal transplants.

BACKGROUND: The authors applied the novel method of noninvasive dynamic color Doppler sonographic parenchymal perfusion measurement to renal transplants. METHODS: Color Doppler sonographic videos of renal transplants from 38 renal transplant recipients were recorded under defined conditions. Specific tissue perfusion was calculated as mean flow velocity encoded by color Doppler signals of a region of interest during one full heart cycle. RESULTS: The authors could demonstrate significant differences of central versus peripheral cortical perfusion intensity (1.36 vs. 0.60 cm/sec) and a significant loss of perfusion intensity in the posttransplantation period in the peripheral cortex from 1.06 cm/sec in the first year to a minimum of 0.39 cm/sec in the 3- to 5-year interval, with stronger perfusion in longer surviving transplants: 0.71 cm/sec more than 9 years after transplantation. In the central cortex, a similar but less pronounced pattern could be demonstrated. A significant drop of parenchymal perfusion was found in patients with elevated serum creatinine (1.36 cm/sec in cases with normal and 0.82 cm/sec in those with elevated creatinine at the proximal cortical level). The perfusion ratio of the central 50% and the peripheral 50% shows marked changes over time: in the first year, the ratio was 2.99, climbing to 5.56 at the 3- to 5-year interval and declining later on. CONCLUSIONS: Cortical tissue perfusion in renal transplants was quantified noninvasively from color Doppler signal data in an easily accomplishable manner. Renal transplants showed a marked decline in tissue perfusion after transplantation. Perfusion is significantly lower in transplant function loss with elevated serum creatinine.

New method of dynamic color doppler signal quantification in metastatic lymph nodes compared to direct polarographic measurements of tissue oxygenation.

Tumor growth depends on sufficient blood and oxygen supply. Hypoxia stimulates neovascularization and is a known cause for radio- and chemoresistance. The objective of this study was to investigate the use of a novel ultrasound technique for the dynamic assessment of vascularization and oxygenation in metastatic lymph nodes. Twenty-four patients (age 44-78 years) with cervical lymph node metastases of squamous cell head and neck cancer were investigated by color duplex sonography and 17 (age 46-78 years) were investigated additionally with polarography. Sonography was performed after contrast enhancer infusion under defined conditions. Intranodal perfusion data (color hue, colored area) were measured automatically by a novel software technique. This allows an evaluation of blood flow dynamics by calculating perfusion intensity--velocity, perfused area, as well as the novel parameters tissue resistance index (TRI) and tissue pulsatility index (TPI)--for each point of a complete heart cycle. Tumor tissue pO(2) was measured by means of polarographic needle electrodes placed intranodally. The sonographic and polarographic data were correlated using Pearson's test. Sonography demonstrated a statistically significant inverse correlation between hypoxia and perfusion and significant TPI and TRI changes with different N-stages. The percentage of nodal fraction with less than 10 mmHg oxygen saturation was significantly inversely correlated with lymph node perfusion (r = -0.551; p = 0.021). Nodes with a perfusion of less than 0.05 cm/sec flow velocity showed significantly larger hypoxic areas (p = 0.006). Significant differences of TPI and TRI existed between nodes in stage N(1) and N(2)/N(3) (p = 0.028 and 0.048, respectively). This new method of dynamic signal quantification allows a noninvasive and quantitative assessment of tumor and metastatic lymph node perfusion by means of commonly available ultrasound equipment.

A new method of color Doppler perfusion measurement via dynamic sonographic signal quantification in renal parenchyma.

OBJECTIVE: Perfusion quantification of tissues is an important goal to evaluate the state of blood supply of an organ. We developed a method to quantify tissue perfusion via color Doppler signal quantification from sonographic videos and applied this to describe renal parenchymal perfusion in healthy kidneys. METHOD: Color Doppler sonographic videos of renal perfusion from both kidneys of 87 healthy children (age 2 weeks to 16 years) were recorded under defined conditions. Perfusion data (color hue, color area) were measured in a standardized region of interest automatically. Signal intensity was calculated as whole ROIs (regions of interest) mean flow velocity (cm/s) encoded by color Doppler signals during one full heart cycle. RESULTS: Normal signal intensity values are: 1.86 cm/s in the region encompassing central 50% of the renal cortex and 0.56 cm/s in the peripheral 50% of the renal cortex. These differences are significant. Signal intensity of both kidneys did not differ. CONCLUSION: Signal intensity of cortical tissue in healthy kidneys was quantified noninvasively from color Doppler signal data in an easily accomplishable manner with new measurement software. Normal values for this technique have been calculated. Possible further applications might be all situations, where perfusion changes could be expected like inflammation, renal insufficiency, vascular diseases and tumors.