Quantitative three-dimensional power Doppler angiography: a flow-free phantom experiment to evaluate the relationship between color gain, depth and signal artifact

Objectives To evaluate the presence of false flow three-dimensional (3D) power Doppler signals in `flow-free` models. Methods 3D power Doppler datasets were acquired from three different flow-free phantoms (muscle, air and water) with two different transducers and Virtual Organ Computer-aided AnaLysis was used to generate a sphere that was serially applied through the 3D dataset. The vascularization flow index was used to compare artifactual signals at different depths (from 0 to 6 cm) within the different phantoms and at different gain and pulse repetition frequency (PR F) settings. Results Artifactual Doppler signals were seen in all phantoms despite these being flow-free. The pattern was very similar and the degree of artifact appeared to be dependent on the gain and distance from the transducer. False signals were more evident in the far field and increased as the gain was increased, with false signals first appearing with a gain of 1 dB in the air and muscle phantoms. False signals were seen at a lower gain with the water phantom (-15 dB) and these were associated with vertical lines of Doppler artifact that were related to PRF, and disappeared when reflections were attenuated. Conclusions Artifactual Doppler signals are seen in flow-free phantoms and are related to the gain settings and the distance from the transducer. In the in-vivo situation, the lowest gain settings that allow the detection of blood flow and adequate definition of vessel architecture should be used, which invariably means using a setting near or below the middle of the range available. Additionally, observers should be aware of vertical lines when evaluating cystic or liquid-containing structures. Copyright (C) 2010 ISUOC. Published by John Wiley & Sons, Ltd.

Analysis of placenta vascularization in patients with uterine altered artery Doppler flow velocity exams

Background: One of the frequent questions in obstetric practice is to determine placental vascular changes that may account for abnormal Doppler flow velocity alterations in maternal uterine vessels from women and fetuses without pregnancy pathology. Methods: A retrospective morphometric study was realized using 27 placentas from patients submitted for Doppler flow velocity exam during pregnancy. The placentas were morphologically examined using hematoxylin-eosin staining. Measurements of villi were made with the use of a video camera coupled to a common light microscope and a computer with automatic image analyzing software. Results: Of the 27 placentas, 13 (48%) were of patients showing unaltered Doppler and 14 (52%) showing altered Doppler. The number of stem villi vessels was significantly larger in the placentas of patients with Doppler exam alterations (P = 0.003). This group also presented greater stem villi vessel thickness, although without significant difference. The number of intermediary and terminal villi vessels was greater in the placentas of patients with altered Doppler exams (P < 0.001), and a greater terminal villi area was observed in these cases (P < 0.001). Conclusion: The morphological proof that uterine artery Doppler flow velocity exam alterations are associated with placental vascular alterations demonstrates the importance of this exam during prenatal care, even in the absence of maternal-fetal alterations.

Influence of aging, tidal volume, and respiratory rate on Doppler echocardiographic indices of diastolic function in normal male subjects: A quantitative evaluation

Background: Although the influence of respiration on ventricular filling, as evaluated by Doppler technique, and the evaluation of diastolic velocities of mitral valve annulus (MVA), as measured by Doppler tissue imaging (DTI), can provide valuable information for the study of left ventricular (LV) diastolic function, the concomitant effects of aging, tidal volume (TV), and respiratory rate (RR) on these velocities have not been quantitatively investigated. Methods: We evaluated 12 normal male volunteers (Group I) aged 20-26 years (mean: 22.8) and 8 normal subjects aged 41 to 54 years old (mean: 45.9) (Group II). Using DTI we measured peak early (E-a) and late (A(a)) velocities of longitudinal axis expansion at lateral and medial MVA. Doppler mitral and tricuspid flow velocities were measured: peak early (E) and late (A) inflow velocity, early (E-i) and late (A(i)) flow integral, and deceleration time of peak early mitral flow velocity (DT). Respiratory cycles were simultaneously recorded at RR of 9, 12, 15, and 18 cycles/min and TV of 600 and 900 mL during respiration (RESP). Results and conclusions: (1) E, A, and A(i) in MV had negligible change during respiration, but E-i was significantly reduced during inspiration; (2) DT reduced slightly with inspiration, but the change was significant only with TV of 900 mL; (3) an important increase of E in right ventricular flow was observed during inspiration; (4) variations of RR and TV did not significantly influence right and left ventricular inflow in normal subjects, in the conditions of this investigation; (5) a significant increase of E-a at medial MVA was documented during inspiration only in young subjects; (6) a significant decrease of A(a) at medial MVA was observed during inspiration in both groups of volunteers; (7) RR and TV did not influence MVA velocities in young and adult subjects; (8) a consistent reduction in E-a and a significant increase in A(a) were observed with increasing age; (9) these changes were more conspicuous and consistent than those documented in ventricular filling when young and middle-age men are compared, suggesting that the DTI is more sensitive to detect changes in diastolic function; and (10) in addition, these data suggest that, for evaluation of diastolic function, in clinical context, it is not necessary to control rigorously RR or TV.

Intestinal bacterial overgrowth after Roux-en-Y gastric bypass

The aim of the present study was to report the occurrence of serious subnutrition, associated to intestinal bacterial overgrowth, in two patients submitted to bariatric surgery. Two female patients (body mass index, 49 and 50 kg/m(2), respectively) were submitted to Y-en-Roux gastric bypass. The first patient evolved a 52% loss of body weight within 21 months after surgery; the other, a 34% loss of initial body weight within 15 months after surgery, results corresponding, respectively, to 62 and 45 kg weight losses. However, both patients reported asthenia, hair fallout, and edema, and one also reported diarrhea, but none was feverish. Their respective albuminemias were of 24 and 23 g/l. A respiratory hydrogen test suggested bacterial hyperproliferation. Thirty days after ciprofloxacin and tetracyclin treatments, they showed improved albumin levels and nutritional states, both confirmed by results of hydrogen breath tests. Bacterial overgrowth is an important complication that can compromise clinical evolution of patients submitted to intestinal surgery like gastroplasty with Y-Roux anastomosis. In cases of clinical suspicion or a confirmed diagnosis, adequate antibiotics, sometimes requiring to be cyclically repeated, should be administered.

Evaluation of ductus venosus and inferior vena cava by using multiple Doppler ultrasound parameters in healthy fetuses

The objective of this study was to describe multiple Doppler ultrasound parameters of ductus venosus and inferior vena cava in fetuses at gestational ages ranging from 22 to 38 weeks. In this prospective observational study, Doppler ultrasound exams were performed in 45 healthy fetuses at 22, 26, 34, and 38 weeks. Maximum venous velocity, minimum venous velocity, venous pulsatility index, and venous acceleration time (VAT) (defined as the time between minimum and maximum venous velocity) were evaluated at those gestational periods. Increase in the velocities and decrease in the pulsatility index were observed in these vessels throughout gestational age. The VAT increased with gestational age. The VAT, a Doppler parameter still not described elsewhere, increased during pregnancy could be related to a longer period of time needed to fill the atrium in bigger hearts. In this study, we provide reference values for VAT in healthy fetuses.