Power Doppler imaging of carotid artery stenosis. Comparison with color Doppler flow imaging and angiography

BACKGROUND AND PURPOSE: Power Doppler imaging (PDI) is a new sonographic technique that has recently been introduced for vascular application. Since the technical principles of PDI may provide increased sensitivity to visualize the continuity of blood flow in arterial stenoses, we investigated the diagnostic significance of PDI and the intermethod relationship for the measurement and classification of internal carotid artery (ICA) stenosis in comparison with both color Doppler flow imaging (CDFI) and angiography. METHODS: One hundred patients with a total of 128 ICA stenoses (50% to 69%, n = 37; 70% to 79%, n = 27; 80% to 99%, n = 64) and 12 ICA occlusions were consecutively investigated by means of PDI, CDFI, and intra-arterial angiography (n = 48). Reduction of the intrastenotic lumen was measured on longitudinal and transverse views of PDI and CDFI for the calculation of the degree of diameter and area stenosis, respectively. Angiographic stenosis was determined with the use of the North American Symptomatic Carotid Endarterectomy Trial (NASCET), European Carotid Surgery Trial (ECST), and common carotid (CC) methods. RESULTS: PDI provided significantly more excellent or good (92% versus 79%; P < .01) displays of the intrastenotic lumen than CDFI, particularly in complicated high-grade stenosis. While linear regression analysis demonstrated a high overall correlation between PDI and CDFI for diameter (r = .88; P < .001) and area stenosis (r = .79; P < .001), categorization of ICA stenosis revealed best agreement for 80% to 99% area stenoses. Since angiography frequently either underclassified (NASCET method) or overclassified (ECST, CC methods) the degree of ICA stenosis in comparison to both PDI and CDFI, the sonographic-angiographic correlation was only moderate (regression coefficients ranged from .62 to .70; P < .001). CONCLUSIONS: PDI further improves the assessment of ICA stenosis by providing better visualization of the stenotic vascular lumen than CDFI. Sonographic imaging of the stenotic plaque on both PDI and CDFI provided a direct measurement of the local degree of stenosis, while the angiographic grade of stenosis essentially depended on the method used for evaluation.     

Evaluation of breast tumors with color Doppler imaging: a comparison with image-directed Doppler ultrasound

Preclinical experience has shown that it is possible to maintain and expand hematopoietic cells in liquid culture systems by provision of optimal combinations of colony-stimulating factors (CSF). Ex vivo hematopoietic cell expansion (HCE) would be expected to reduce harvesting time and effort and could also decrease the infusion dose necessary for hematopoietic reconstitution after bone marrow transplantation. In addition, ex vivo expanded cells might be of value for therapeutic gene transfer. The central question in ex vivo HCE is whether the CSF combinations employed provide not only amplification of the late progenitor pools, but also maintenance or expansion of the stem cell compartment to ensure long term engraftment. Choice of CSF and experimental parameters in the culture system appear to be the most critical factors influencing the outcome of strategies for ex vivo HCE. Moreover, it is essential to define the goal of HCE and to adapt the experimental conditions to obtain the required cell populations. In future work, it remains to test the potential applicability of ex vivo expanded cells and to carefully monitor the possibility of the expansion of tumoral cells in ex vivo proliferation systems.     

Placenta accreta: evaluation with color Doppler US, power Doppler US, and MR imaging

PURPOSE: To determine the value of transabdominal ultrasound (US), transvaginal US, color Doppler US, power Doppler US, and magnetic resonance (MR) imaging in the diagnosis of placenta accreta. MATERIALS AND METHODS: Nineteen patients in the third trimester of pregnancy who were at risk for placenta accreta underwent color Doppler and power Doppler US; 18 patients also underwent MR imaging. Images were interpreted prospectively for signs of accreta by two reviewers. The reviewers' confidence in their diagnosis was graded on a five-point scale. RESULTS: Outcomes at delivery were as follows: normal placenta (n = 11), hysterectomy owing to uncontrollable bleeding (n = 1), and placenta accreta (n = 7). Five cases of lower-uterine-segment placenta accreta were diagnosed with a high level of confidence with vaginal and power Doppler US. In one patient with a posterior placenta who had previously undergone myomectomy, MR imaging enabled the diagnosis of placenta accreta, which was not well depicted at US. CONCLUSION: In patients with a history of uterine scars, vaginal US with power Doppler US performed well in the evaluation of lower-uterine-segment placenta accreta. MR imaging depicts posterior placenta accreta.     

Reproducibility of color Doppler imaging in orbital vessels

The purpose of this study was to evaluate the short-term reproducibility, the long-term reproducibility, and the reproducibility of the measurements made between two different examiners of blood-flow velocity in extraocular vessels using color Doppler imaging (CDI). In a group of 10 healthy volunteers, measurements of the peak-systolic velocity (PSV), end-diastolic velocity (EDV), and resistivity index (RI) in the ophthalmic artery and the central retinal artery as well as one lateral and one medial short posterior ciliary artery were performed. The best intraindividual reproducibility, expressed as the relative error, was found for the PSV and RI measured in the ophthalmic artery (OA; PSV 5.9%, RI 3.1%) and the central retinal artery (CRA; PSV 7.7%, RI 4.7%). The PSV and RI determined in the posterior ciliary arteries were less reproducible but as much so as the EDV measured in the OA (11.8%) and CRA (19.9%). No systematic trend could be found between the first and second measurements. However, the long-term fluctuation was considerable high. Measurements of PSVs showed good concurrence between the two observers in all four vessels measured. The EDVs and RIs differed statistically significantly between the two observers. This difference was most pronounced in the posterior ciliary arteries.     

Diagnosis of adnexal malignancies by using color Doppler energy imaging as a secondary test in persistent masses

In this study we evaluated the histomorphology and ultrastructure of the oviduct of newly hatched chicks, as well as the immunohistochemical expression of progesterone receptor (PR) in this tissue after follicle-stimulating hormone (FSH) treatment on days 13, 15 and 17 of embryonic development. Results indicated a marked difference in the histology of the oviduct of newly hatched chicks treated with FSH. Magnum mucosa from these animals presented a pseudostratified epithelium with evaginations from the lumen into the epithelium and from the latter into the stroma beneath where tubular glands are formed. In contrast magnum mucosa from control animals presented columnar epithelium with no evaginations. In magnum epithelium FSH also induced the formation of cilia and microvilli projections into the lumen as well as an increase in the wall and lumen areas and in the density of nuclei per unitarea. PR immunoreactivity was only observed in the oviduct of FSH treated animals. PR was located in the nucleus of epithelial luminal cells, mucosal stromal cells and smooth muscle cells. These findings suggest that FSH induces an adequate hormonal milieu for the cytodifferentiation and PR gene expression in the chick oviduct.     

Antenatal diagnosis of velamentous umbilical cord insertion and vasa previa with color Doppler imaging

The effect of various anionic surfactants on the initial rate of 5-aminosalicylic acid peroxidation with horseradish peroxidase was studied. With increasing surfactant concentration, this rate first decreased, then increased, and again decreased. We conclude that these changes were due to an inhibition of the enzyme, a subsequent change in the enzyme conformation accompanied by the enhanced accessibility of its active site to the substrate, and the final protein denaturation, respectively.     

Objective assessment of nickel sulfate patch test reactions with laser Doppler perfusion imaging

Several liquid, semi-solid and solid delivery systems were formulated and tested to devise a method of reproducibly administering accurate micro-doses of calcium into a 700 microns diameter cavity in a rat maxillary incisor tooth, in the absence of hydroxyl ions. Development of this delivery system was necessary to facilitate studies of the mechanisms of pulpal repair and odontoblast differentiation. The principal requirements for the delivery system were that it should be easily administered into a small pulp exposure in the rat incisor and that a greater than 1000-fold range in calcium ion concentrations could be incorporated and delivered for a period of 2-3 days, preferably in an acidic environment to minimize the effect of non-specific nucleation under alkaline conditions. Poly- (ethylene) glycol microspheres were found to be an ideal vehicle. Under the in vitro dissolution conditions used, complete release of all calcium salts occurred within 12-15 hours, except for the very water-insoluble calcium stearate. It was anticipated that the release of calcium ions would be significantly more prolonged in vivo because of the physical constraints of the prepared cavity as well as the restricted access to fluid flow.     

Pulmonary catabolism of interleukin 6 evaluated by lung perfusion of normal and smoker rats

Cytokines such as interleukin 6 are involved in the pulmonary inflammation arising as a result of smoking. By use of isolated and perfused lung preparations we have evaluated the role of the lungs in the catabolism of human recombinant interleukin 6 both in normal rats and in rats subjected to an acute cigarette smoking episode. When interleukin 6 was incorporated into the lung perfusion medium, neither control nor smoke-exposed rat lungs cleared the cytokine and only 0.1 +/- 0.2% of the total dose was recovered in the bronchoalveolar lavage fluid. When, on the other hand, the same amount of interleukin 6 was instilled into the bronchoalveolar tree, concentrations of the cytokine in the perfusate increased progressively so that after 3 h up to 70.1 +/- 9.8% and 40.9 +/- 22.5% of the administered dose, as measured by immunoenzymatic test, had been transferred from the bronchial lumen to the perfusion medium of either control or smoker rat lungs, respectively, indicating significantly (P < or = 0.05) different behaviour of the cytokine in the two experimental groups. Total recoveries of the administered interleukin 6 evaluated in smoke-exposed rat lungs were 55.3 +/- 23.2%, significantly lower than those for control rat lungs (83.9 +/- 11%). Determination of biological activity gave values always lower than those measured by immunoenzymatic test, indicating loss of biological activity during the transalveolar transit. It appears that the transfer of interleukin 6, especially in smokers, is almost exclusively unidirectional, from the alveolar space to the plasmatic pool with degradation during the transalveolar passage.     

Conventional color Doppler velocity sonography versus color Doppler energy sonography for the diagnosis of acute experimental torsion of the spermatic cord

OBJECTIVE: We compared color Doppler velocity sonography and color Doppler energy sonography for the diagnosis of spermatic cord torsion in a canine model and determined the degree of torsion necessary to acutely halt testicular blood flow. MATERIALS AND METHODS: Spermatic cord torsion was created in five dogs by exposing and rotating the ipsilateral testis 0 degree, 180 degrees, 270 degrees, 360 degrees, 450 degrees, and 540 degrees. Detorsion followed. The testicles were scanned at each torsion stop using both color Doppler velocity sonography and color Doppler energy sonography. Doppler parameters were optimized (by phantom and test scans) and maintained at a tolerable noise level throughout the experiment. Readers who were unaware of the degree of torsion compared flow in the rotated and contralateral control testes. RESULTS: Flow became undetectable by color Doppler velocity sonography and color Doppler energy sonography at 450 degrees in four of five cases and at 540 degrees in one of five cases. We found no significant difference between the velocity and the energy techniques for detecting this absence of flow (p > .05, Wilcoxon test). We found a significant difference in degree of flow for both techniques when comparing controls and all degrees of torsion combined (p < .006, Mann-Whitney test), but significance was achieved at lesser degrees of torsion with the velocity technique than with the energy technique (180 degrees and 360 degrees, respectively, Wilcoxon test). CONCLUSION: Color Doppler energy sonography was not significantly more sensitive than color Doppler velocity sonography for the diagnosis of spermatic cord torsion in this model. Complete occlusion of arterial inflow occurred at 450-540 degrees of torsion.     

Detection of acute rejection of heart transplantation by Doppler color imaging

Doppler tissue imaging is a new technique of measuring the velocities of myocardial wall motion. In order to assess its value in the diagnosis of acute rejection, the velocities of the interventricular septum and left ventricular posterior wall were measured in systole and early diastole in 34 cardiac transplant patients at the time of their endomyocardial biopsy, using an M mode left parasternal short axis view. During 40 episodes of acute rejection (26 mild and/or moderate, 10 sub-severe and 4 severe), the wall velocities decreased significantly (p < 0.001) both in the interventricular septum and endocardium of the posterior wall. Myocardial velocities were significantly slower in sub-severe or severe rejection than in mild or moderate rejection. The most sensitive criterion was the measurement of posterior wall endocardial velocity in early diastole, a decrease of 10% having a sensitivity of 92% whereas the sensitivity of usual Doppler echocardiographic parameters is only 73%. Acute rejection, even mild cases, can be diagnosed with excellent sensitivity by measuring myocardial velocities by Doppler tissue imaging. This technique has the advantage of being non-invasive, reproducible and reliable in the follow-up of cardiac transplant patients.     

Laser Doppler perfusion imaging of skin blood flow using red and near-infrared sources

At present, scanning laser Doppler imaging uses a 633-nm helium-neon laser (RED) as the only light source, but this restricts its ability to measure blood flow (i) at darkly pigmented skin and (ii) from deeper or subdermal structures. Because near-infrared (NIR) light is known to penetrate deeper into tissue and to be less absorbed than RED, two imagers were adapted to include a NIR laser diode source (one of 830 nm for UK studies; one of 780 nm for leprosy field trials) in parallel with the existing RED source. In human hands representing a range of skin pigmentations, RED scans were unobtainable at the darkest areas of skin, but intact NIR scans could be collected in all cases. In experiments at the rat knee and the dorsal human hand, NIR and RED values were similar on normal skin. Over underlying vessels, however, NIR values greatly exceeded RED values, an effect abolished by occlusion. Similarly, in patients with leprosy and in healthy controls in Spain, fingerpulp NIR values exceeded RED values to the greatest degree when thermoregulatory flow was highest, i.e., when the deeper-lying arteriovenous anastomoses were open. Over areas of experimental inflammation, NIR gave higher values and also exhibited a greater degree of spatial heterogeneity than RED. We conclude that some current limitations of laser Doppler imaging technology can be overcome by the use of NIR laser diode sources.     

Comparison of regional myocardial velocities assessed by quantitative 2-dimensional and M-mode color Doppler tissue imaging: influence of the signal-to-noise ratio of color Doppler myocardial images on velocity estimators of the Doppler tissue imaging system

M-mode color Doppler imaging of the myocardium affords a greater sampling rate and signal-to-noise (S/N) ratio than 2-dimensional (2D) imaging. In this study, we compared myocardial velocities assessed by 2D and M-mode Doppler tissue imaging (DTI) at the same site and evaluated the influence of the S/N ratio on velocity estimates of the currently used DTI systems. In patients with and without impaired regional left ventricular function, myocardial velocities assessed by 2D DTI were lower than those obtained with M-mode DTI. The difference between regional velocities derived from both imaging techniques was positively correlated with the extent of the "black zone," which could be considered as indirectly reflecting the S/N ratio for each frame. Thus in the clinical setting and on currently used echocardiographs, 2D DTI may provide underestimated regional myocardial velocities when compared with M-mode, mainly because of the influence of the lower sampling rate and S/N ratio on velocity estimators of the imaging system.     

Association between carotid lesions evaluated by Doppler color echocardiography and cardiovascular risk factors in the elderly. Preliminary results

BACKGROUND: The valuation of the extracranial carotid by echo color-Doppler takes on an extraordinary importance for the prevention of cerebral ictus at geriatric age. In this "naturalistic" study a population of old people (> 65 yrs) of Cagliari's province was considered in order to: 1) discriminate the lesions of the carotid that are imputed to atherosclerotic disease by anatomic changes of the arterial wall caused by aging; 2) study relations between lesions of the carotid and cardiovascular risk factors. METHODS: The carotids of 50 old subjects were studied by echo color-Doppler and the lesion classified in different classes of severity, according to the hemodynamic standard, comparing them with the presence of the most important cardiovascular risk factors. Hypercholesterolemia was the most frequent risk factor (76%), followed by hypertension (62%), over-weight (54%) and smoking (42%). Moreover a diffused intima-media thickening (IMT) was constant in all the subjects with values > 0.75 mm; athero-sclerotic plaques were even present in 39 subjects which only in 4 cases could be considered at risk of cerebral ischemia. RESULTS: A significant correlation between the severity of the lesions and levels of total cholesterol and LDL cholesterol for the male sex emerged, while for smoking only a trend of correlation has been obtained. CONCLUSIONS: Considering this experience it is suggested that in old subjects the presence of a diffused IMT with values > 0.75 mm must be considered as a marker of aging of the arterial wall of the carotid and not as a cardiovascular risk factor as reported in the literature for the middleaged.     

Angiogenesis of gynecologic tumors studied with color Doppler

Angiogenesis is obligatory event in solid tumors growth. Weak muscular layer in the newly formed tumoral vessels results in decreased resistance to blood flow and characteristic Doppler signal. The number and arrangement of the blood vessels differ between benign and malignant lesions as well. Parameters mentioned above enable a precise ultrasound differential diagnosis between benign and malignant tumors. Malignant uterine tumors are better perfused and have lower resistance to blood flow than benign ones. Benign lesions with secondary changes (necrosis) may have lowered resistance indices. The finding of pathological perfusion makes the diagnosis of endometrial carcinoma also very accurate. High sensitivity of the transvaginal color Doppler in detecting newly formed blood vessels in an early stages of ovarian cancer may establish this technique as a screening method for this still very high lethality disease.     

3-D reconstruction of intracranial vessels using a color Doppler energy method--initial experiences]

Transcranial Doppler sonography and colour Doppler imaging provide good information on the basal arterial brain vessels, but cannot provide images comparable to angiographic images. However, comparable displays could be achieved by a 3-dimensional calculation of images collected by a computer. These images of intracranial vessels are supplied by the new Doppler imaging modality Colour Doppler Energy (CDE). Tilting of the acquired data can then be oriented analogous to angiography, CT and MRI projections. Initial results with this method are very promising.     

Analysis of blood flow in adnexal tumors by using color Doppler imaging and pulsed spectral analysis

Because of various contradictory reports in the literature and an increasingly urgent need for preoperative evaluation of adnexal masses before laparoscopic surgery, our aim was to disclose if examination by means of color Doppler ultrasound is useful in distinguishing benign from malignant adnexal tumors in our population. Prior to surgery, pulsed color Doppler velocimetry of the adnexal blood supply was performed in a prospective study in 80 patients with benign and 40 with malignant adnexal tumors. Vascularization was equally frequent in both groups of tumors. Blood vessels of benign tumors had a diffuse, intraseptal or intraproliferative location significantly more often and malignant tumor vessels more often exhibited a diffuse, intraseptal or intraproliferative location (p < 0.01). The mean value of RI+/-SD was 0.56+/-0.14 in benign and 0.33+/-0.13 in malignant tumors. The differences in RI between benign and malignant tumors are statistically significant (p < 0.01). In detecting malignant adnexal tumors, the sensitivity of RI < or = 0.40 is 82%, its specificity 97%, positive predictive value 94%, negative predictive value 92% and its accuracy 92%. The analysis of vascularization presence seems not to have any value in predicting the nature of adnexal tumors, and blood vessels arrangement, as well as measured RI < or = 0.40, allows us to predict the presence of malignancy with limited reliability.     

Comparison of myocardial velocities by tissue color Doppler imaging in normal subjects and in dilated cardiomyopathy

The authors studied 35 normal subjects (41 +/- 6 years) and 22 patients with idiopathic dilated cardiomyopathy 48 +/- 7 years; ejection fraction: 31 +/- 12%) in order to determine normal values of myocardial velocities and to demonstrate the sensitivity of Doppler tissue imaging in detecting a significant decrease in myocardial velocities in patients with abnormal left ventricular contractility. Interventricular septal and left ventricular posterior wall velocities were recorded by M mode long axis parasternal views. In normal subjects, a velocity gradient in the posterior wall was observed, higher in the endocardium than in epicardium, in systole (5.1 +/- 1.5 versus 2.8 +/- 1 cm/s, p < 0.01), and early diastole (13.7 +/- 3.5 versus 5.7 +/- 2 cm/s, p < 0.001) and late diastole at the time of atrial contraction (2.7 +/- 2.1 versus 1.8 +/- 1.7 cm/s, p < 0.01). Moreover, the velocities are higher in the posterior wall than in the interventricular septum throughout the cardiac cycle. Finally, the velocities are higher in early diastole than in systole, both in the interventricular septum and posterior wall. In the group of patients with idiopathic dilated cardiomyopathy, the intramyocardial velocities were lower than in normal subjects. In addition, the velocity gradient in the posterior wall was absent in 15 of the 22 patients. The authors conclude that Doppler tissue imaging provides new information in the analysis of myocardial function both in systole and diastole.