Power Doppler Signal Intensity Research Articles

Comparison of imaging findings between calcific tendinitis with subacromial-subdeltoid bursitis and adhesive capsulitis

Objective To evaluate radiographic and ultrasound (US) findings in the patients with calcific tendinitis of shoulder and compare these imaging findings between the patients with subacromial-subdeltoid (SASD) bursitis and adhesive capsulitis (AC) alone. Methods One hundred-thirty-four shoulders (129 patients, 36 men, 93 women; mean age, 56.9+ 9.3 years; range, 33-84 years) that were diagnosed as calcific tendinitis of shoulder on US were recruited from January 1st 2013 to June 31th 2018. Radiographic morphology of calcification was classified by Gartner and Simons method. US morphology of calcification was classified as arc-shaped, fragmented, nodular, cystic, and linear type. Size of calcification was measured as the maximal diameter on radiograph and US. Power Doppler signal intensity in calcification was graded as no signal, mild, moderate, and severe. Location of calcification in tendon was classified as bursal side, articular side, and full-thickness involvement. The patients were allocated into two groups according to response to US guided injection; group 1 (responder to SASD bursa injection, 75 patients, 21 men, 54 women; mean age, 56.3 ± 9.1 years; range, 33-77 years) and group 2 (responder to glenohumeral joint injection, 54 patients, 15 men, 39 women; mean age, 57.7 ± 9.5 years; range, 43-84 years). Results There was no significant difference of demographic data between two groups. There was a significant difference of US morphology, power Doppler signal intensity, and location of calcification between two groups. Fragmented type was 55 calcifications (75.3%) in group 1 and 18 (24.7%) in group 2, and arc-shaped type was 20 (69.0%) in group 2 and 9 (31.0%) in group 1 (p Articular side location was 39 calcifications (61.9%) in group 2 and 24 (38.1%) in in group 1, and bursal side/full-thickness were 24 (85.7%) / 30 (69.8%) in group 1 and 4 (14.3%) / 13 (30.2%) in group 2 (p Conclusions Our results indicated that the morphology, power Doppler signal intensity, and location of calcification on US is associated with the pain of shoulder calcific tendinitis. Therefore, the US assessment of morphology, power Doppler signal intensity, and location of calcification can help to decide the target of treatment in the patients with shoulder calcific tendinitis.

Understanding the Influence of Flow Velocity, Wall Motion Filter, Pulse Repetition Frequency, and Aliasing on Power Doppler Image Quantification.

Although power Doppler imaging has been used to quantify tissue and organ vascularity, many studies showed that limitations in defining adequate ultrasound machine settings and attenuation make such measurements complex to be achieved. However, most of these studies were conducted by using the output of proprietary software, such as Virtual Organ computer-aided analysis (GE Healthcare, Kretz, Zipf, Austria); therefore, many conclusions may not be generalizable because of unknown settings and parameters used by the software. To overcome this limitation, our goal was to evaluate the impact of the flow velocity, pulse repetition frequency (PRF), and wall motion filter (WMF) on power Doppler image quantification using beam-formed ultrasonic radiofrequency data. The setup consisted of a blood-mimicking fluid flowing through a phantom. Radiofrequency signals were collected using PRFs ranging from 0.6 to 10 kHz for 6 different flow velocities (5-40 cm/s). Wall motion filter cutoff frequencies were varied between 50 and 250 Hz. The power Doppler magnitude was deeply influenced by the WMF cutoff frequency. The effect of using different WMF values varied with the PRF; therefore, the power Doppler signal intensity was dependent on the PRF. Finally, we verified that power Doppler quantification can be affected by the aliasing effect, especially when using a PRF lower than 1.3 kHz. The WMF and PRF greatly influenced power Doppler quantification, mainly when flow velocities lower than 20 cm/s were used. Although the experiments were conducted in a nonclinical environment, the evaluated parameters are equivalent to those used in clinical practice, which makes them valuable for aiding the interpretation of related data in future research.

Power Doppler 'blanching' after the application of transducer pressure

The aim of this study was to determine if transducer pressure modifies power Doppler assessments of rheumatoid arthritis synovium at the metacarpophalangeal joints and metatarsophalangeal joints. Five rheumatoid arthritis patients of varying degrees of 'disease activity' and damage were assessed with power Doppler ultrasound scanning of the dominant hand second to fifth metacarpophalangeal joints. Two rheumatoid arthritis patients had their dominant foot first to fifth metatarsophalangeal joints assessed with power Doppler ultrasound. Ultrasonography was performed with a high frequency transducer (14 MHz) with a colour mode frequency of 10 Mhz, and a standard colour box and gain. In the joint that showed the highest power Doppler signal, an image was made. A further image was taken after transducer pressure was applied. In all patients, there was increased flow to at least one joint. After pressure was applied, power Doppler signal intensity markedly reduced in all images and in some there was no recordable power Doppler signal. Increased transducer pressure can result in a marked reduction or obliteration in power Doppler signal. This power Doppler 'blanching' shows the need for further studies to evaluate sources of error and standardization before power Doppler ultrasound becomes a routine measure of 'disease activity' in rheumatoid arthritis.

Computer analysis of three-dimensional power angiography images of foetal cerebral, lung and placental circulation in normal and high-risk pregnancy

Three-dimensional (3-D) ultrasound (US) has greatly improved evaluation of organ circulation. The aim of this study was to explore the possible use of this new technique in normal and high-risk pregnancies. Fetal brain, lung and placenta 3-D power Doppler signal intensity were recorded in 115 normal singleton pregnancies (24 to 42 weeks gestation) and in 67 high-risk pregnancies. Mean image pixel signal intensity was calculated for each organ and a brain-lung ratio. In normal pregnancy, placental and lung signal intensity increased until 33, with a rapid decrease after 38, weeks of gestation. Fetal cerebral signal intensity increased with gestational age. Placental and fetal lung signal intensity was significantly lower in high-risk pregnancies than in the control group, with increased fetal brain and brain-lung ratios. The present results suggest a reduction of placental perfusion after 38 weeks of gestation in normal pregnancy, with redistribution of fetal circulation. Lung signal intensity increased abruptly at 32 weeks of gestation, which might reflect lung maturity. The new method showed signs of centralization of fetal circulation at the end of gestation. The results might suggest a possible clinical use for fetal surveillance in high-risk pregnancies. (E-mail: saemundur.gudmundsson@obst.mas.lu.se)

Comparison of power Doppler and velocimetry in predicting outcome of high‐risk pregnancy

Purpose: To prospectively evaluate semiquantitative computer analysis of power Doppler (PD) signals in the placenta, fetal brain, lung, liver, kidney and spleen in high‐risk pregnancies in relationship to perinatal outcome and also to compare tissue blood flow in the fetal brain and placenta with Doppler velocimetry.Methods: PD signals were recorded in 180 high‐risk pregnancies between 27 and 41 weeks of gestation. Images from PD scans angiographics were transmitted for computer analysis of pixel intensity. Mean flow signal intensity was recorded for each organ. The PD brain/lung ratio was calculated. The PD results were plotted on reference values and related to perinatal outcome. Middle cerebral (MCA), umbilical (UA) and uterine artery (Ut. A) velocimetry was also performed.Results: High‐risk pregnancies displayed lower PD signal intensity from the placenta, fetal lung, liver and kidney as compared to normal. However, the brain and spleen signals showed higher intensities suggesting increased tissue perfusion. PD signals from the fetal brain, lung, placenta and PD brain/lung ratio were correlated with perinatal outcome. The PD signal intensity from the fetal liver, kidney and spleen showed poor correlation with perinatal outcome. Fetal brain tissue blood flow showed better correlation with the outcome than MCA velocimetry. Placental tissue blood flow results were similar in predicting outcome to those obtained by means of UA and Ut. A velocimetry.Conclusions: In comparison with conventional Doppler velocimetry, computer analysis of PD signals, give similar results in the prediction of adverse perinatal outcome.

Comparison of power Doppler and velocimetry in predicting outcome of high-risk pregnancy

Objective: Prospectively evaluate semi-quantitative computer analysis of power Doppler (PD) signals in the placenta, fetal brain, lung, liver, kidney and spleen in high-risk pregnancies in relationship to perinatal outcome and also to compare tissue blood flow in the fetal brain and placenta with Doppler velocimetry. Methods: PD signals were recorded in 180 high-risk pregnancies between 27 and 41 weeks of gestation. Images from PD angiographic scans were transmitted for computer analysis of pixel intensity. Mean flow signal intensity was recorded for each organ. The PD brain/lung ratio was calculated. The PD results were plotted on reference values and related to perinatal outcome. Middle cerebral (MCA), umbilical (UA) and uterine artery (Ut. A) velocimetry was also performed. Results: High-risk pregnancies displayed lower PD signal intensity from the placenta, fetal lung, liver and kidney as compared to normals. However, the brain and spleen signals showed higher intensities suggesting increased tissue perfusion. PD signals from the fetal brain, lung, placenta and PD brain/lung ratio were correlated with perinatal outcome. The PD signal intensity from the fetal liver, kidney and spleen showed poor correlation with perinatal outcome. Fetal brain tissue blood flow showed better correlation with the outcome than MCA velocimetry. Placental tissue blood flow results were similar in predicting outcome to those obtained by means of UA and Ut. A velocimetry. Conclusion: In comparison with conventional Doppler velocimetry, computer analysis of PD signals, give similar results in the prediction of adverse perinatal outcome.

Improved characterisation of focal liver tumours: dynamic power Doppler imaging using NC100100 echo-enhancer

Objective: To assess the vascularisation of focal hepatic tumours using NC100100, enhanced power Doppler imaging. Methods: Twenty-two patients with focal liver tumours (12 metastases and ten hemangiomas) were studied. Using standardised settings, power Doppler imaging with ATL HDI3000 was performed before and after intravenous administration of NC100100 contrast agent. The video-recorded examinations were digitised for off-line analysis on a personal computer. Regions of interest were defined over the entire tumour and a neighbouring area of the normal liver parenchyma. The temporal changes of the mean power Doppler signal intensity (PDSI) was quantified to provide contrast agent wash-in (PDSI-time) curves for the initial 40 s. Results: Liver metastases were characterised by a rapid increase in PDSI, while the PDSI-time curves within hemangiomas were flat. The PDSI within the tumour increased significantly in ten subjects with liver metastases and only one subject with hemangioma. An enhanced rim around hemangiomas was seen in four subjects. There was no clear relationship between the contrast agent dose and the peak PDSI within metastases. Conclusions: Power Doppler imaging with NC100100 contrast agent enhances tumour visualisation and may aid differential diagnosis of focal liver lesions.

Intravascular contrast agent in the ultrasonography of ectopic pregnancy.

The aim of this study was to characterize the effect of an intravascular ultrasound contrast agent in the adnexal circulation and to evaluate the applicability of the contrast agent in imaging ectopic trophoblastic blood flow. Thirty-three color Doppler and 13 power Doppler examinations were performed among 30 patients with ectopic pregnancy, first without and then with galactose-based contrast agent enhancement. The effect of the contrast agent was evaluated both visually (color Doppler) and with computerized power Doppler signal intensity measurements. The Doppler signal intensity from the adnexal blood circulation increased within 30 s after antebrachial injection, yielding an effect that was recognizable up to 2-4 min later. There was a clear enhancement of trophoblastic flow after addition of the contrast agent in all except one of the ectopic pregnancies. In 12% of the cases, trophoblastic flow could be imaged only by using the contrast agent. The contrast agent increased the amount of recognizable vascular areas around the trophoblastic mass in 91% of the examinations, resulting in a more complete peritrophoblastic ring. The increase in the mean intensity of the power Doppler signal was 7.8% (p < 0.01). The intravascular ultrasound contrast agent has a recognizable effect on Doppler ultrasonographic examination of the adnexal circulation. It appears to be of help when examining ectopic pregnancies where the finding in color flow imaging is ambiguous. The use of a contrast agent may also facilitate localization of trophoblastic tissue in a hemorrhagic adnexal mass.

Acoustically Stimulated Transient Power Scattering Explains Enhanced Detection of the Very Low Velocities in Myocardial Capillaries by Power Doppler Imaging: An In Vitro Study

Background: Although enhanced detection of myocardial perfusion signals by power Doppler imaging during contrast echocardiography has been noted, flow velocities in the coronary microvasculature should generally be below the threshold for Doppler motion detection. It has been suggested that in this situation nonlinear scattering related to acoustically stimulated microsphere oscillation or destruction may be responsible for the detected Doppler shift. Methods and Results: This study examined the behavior of MRX 115 (ImaRx Pharmaceuticals) microbubbles during harmonic and nonharmonic power Doppler imaging at varying power outputs (mechanical indexes 0.3, 0.5, 0.7, and 0.9) in a perfusion tube model under zero-flow conditions. Boluses of MRX 115 0.5-mL suspension were introduced into the model, and flow was halted during each imaging period. Once power Doppler imaging was implemented, a signal was detected as unique sparkling color pixels corresponding to individual bubble destruction events, even in the absence of contrast movement. This phenomenon continued until all contrast bubbles disappeared from the region subjected to power Doppler imaging, usually within 35 to 40 seconds. Off-line videointensity measurements showed that initial power Doppler signal intensity and maximum signal decay rates increased parallel to increasing power output and were substantially greater for nonharmonic than for harmonic imaging modes. Conclusion: This relationship between signal intensity and decay rate and acoustic power output suggests that transient scattering related to bubble destruction is responsible for generation of the power Doppler signal in the absence of flow. This would explain the enhanced detection of the very low velocity flows in the myocardial capillaries by power Doppler contrast imaging. (J Am Soc Echocardiogr 1999;12:643-9.)

Fetal and placental power Doppler imaging in normal and high-risk pregnancy

Objective: Computer analysis of organ power Doppler (PD) imaging has recently become available. The aim of the study was to evaluate gestational trends in placenta-, fetal lung-, liver- and kidney-blood flow in normal pregnancies and relate it to signals in high-risk pregnancies. Methods: PD signals were recorded in normal singleton pregnancies between 26 and 42 weeks of gestation. Signals were also recorded in 63 high-risk pregnancies. Fixed preinstalled PD system installations for each organ were used during examinations. Images from PD scan were recorded on video tape and off-line analysed by computer. Mean flow signal intensity was calculated for each organ. Umbilical and uterine artery Doppler velocimetry were also recorded in high-risk pregnancies. Results: PD signals from the four organs indicated increasing organ blood flow until approximately 34 weeks of gestation, from where the organ signals seemed to decrease. High-risk pregnancies seemed to have lower PD signal intensity, which was more pronounced in cases with signs of placental vascular resistance. Conclusion: The results suggest that a decrease in fetal organ blood flow might indicate a centralisation of fetal circulation in normal pregnancy at term, as a physiological response to a decrease in placental perfusion. In the high-risk pregnancies the placental and fetal organ blood flow seem to be even further reduced, suggesting a more intense centralisation of circulation.

Intravascular Ultrasound Contrast Agent: An Aid in Imaging Intervillous Blood Flow?

The aim of this study was to evaluate the applicability of an intravascular ultrasound contrast agent in examination of the uteroplacental circulation.Uteroplacental circulation in 25 singleton third trimester pregnancies was examined by power Doppler, first without and then with contrast agent enhancement (Levovist\\R, Schering AG, Germany). Eight subjects had fetal growth retardation and 17 had normal-sized fetuses. The effect of the contrast agent was evaluated using computerized power Doppler signal intensity measurements.The Doppler signal intensity in the uteroplacental vessels increased within 25 sec of brachial venous injection of the contrast agent, yielding an effect which was recognizable up to 5–8min later. There was clear enhancement of uteroplacental flow imaging after addition of the contrast agent in all of the examined pregnancies. The mean percentual intensity changes after administration of the contrast agent were 33 per cent (P<0.001) in the sub-placental myometrial area and 8 per cent (P<0.001) in the intraplacental area. No association was found between fetal growth retardation and intensity changes or absolute intensity parameters.In conclusion, intravascular ultrasound contrast agent facilitates imaging of the uteroplacental circulation. It may have a valuable role in determination of intervillous blood flow and in imaging blood perfusion in different regions of the placenta.