Conventional Spectral Doppler Research Articles

Evaluation of diagnostic value of Doppler ultrasound in the diagnosis of malignant breast masses.

Breast cancer is the leading cause of cancer mortality in women, and it is on the rise in Iran. Therefore, an early-stage diagnosis of breast cancer is of critical importance. Because ultrasound is one of the available, inexpensive, and minimally invasive techniques for distinguishing malignant from benign masses, a comparison of conventional ultrasound, color Doppler, and spectral Doppler findings can be useful. The purpose of this study was to determine the diagnostic value of sonographic indices, specifically Doppler parameters, in identifying the nature of breast masses. This is a cross-sectional study, with diagnostic value analysis. Before undergoing a biopsy, 80 patients with breast masses underwent B-mode and Doppler breast ultrasound. The ultrasound findings were then compared to pathologic results to determine which groups were malignant or benign. The resulting data were analyzed using statistical tests and diagnostic values with SPSS 22 software. B-mode grey-scale ultrasound indices such as mass shape, mass margin, mass orientation, and posterior features, as well as Doppler indices such as vascularity, RI (Resistive Index), PI (Pulsatility Index), and PSV (Peak Systolic Velocity), were found to be statistically significant with pathological findings. Color Doppler revealed vascularity in 65% of benign and 84% of malignant masses. The diagnostic value results revealed that mass shape, mass margin, mass orientation, and posterior features all play a significant role in predicting lesion malignancy, with a sensitivity of 92%, 58%, 64%, 56%, and specificity of 59%, 66%, 82%, and 84%, respectively. The RI, PI, and PSV indices were significantly higher in malignant masses, and all of them had remarkable diagnostic values in predicting malignancy, with a (Area Under The Curve) AUC of 0.863, 0.882, 0.702, a sensitivity of 84% and 84%, 68%, and a specificity of 83%, 86%, and 62%, respectively, at the optimal cut-off points (0.65, 1.32, 12.40) obtained from the Receiver Operating Characteristics (ROC) curves.

A comparison of ultrafast and conventional spectral Doppler ultrasound to measure cerebral blood flow velocity during inguinal hernia repair in infants

BackgroundUltrafast cerebral Doppler ultrasound enables simultaneous quantification and visualization of cerebral blood flow velocity. The aim of this study is to compare the use of conventional and ultrafast spectral Doppler during anesthesia and their potential to show the effect of anesthesiologic procedures on cerebral blood flow velocities, in relation to blood pressure and cerebral oxygenation in infants undergoing inguinal hernia repair. MethodsA single-center prospective observational cohort study in infants up to six months of age. We evaluated conventional and ultrafast spectral Doppler cerebral ultrasound measurements in terms of number of successful measurements during the induction of anesthesia, after sevoflurane induction, administration of caudal analgesia, a fluid bolus and emergence of anesthesia. Cerebral blood flow velocity was quantified in pial arteries using conventional spectral Doppler and in the cerebral cortex using ultrafast Doppler by peak systolic velocity, end diastolic velocity and resistivity index. ResultsTwenty infants were included with useable conventional spectral Doppler images in 72/100 measurements and ultrafast Doppler images in 51/100 measurements. Intraoperatively, the success rates were 53/60 (88.3%) and 41/60 (68.3%), respectively. Cerebral blood flow velocity increased after emergence for both conventional (end diastolic velocity, from 2.01 to 2.75 cm/s, p < 0.001) and ultrafast spectral Doppler (end diastolic velocity, from 0.59 to 0.94 cm/s), whereas cerebral oxygenation showed a reverse pattern with a decrease after the emergence of the infant (85% to 68%, p < 0.001). ConclusionIt is possible to quantify cortical blood flow velocity during general anesthesia using conventional and ultrafast spectral Doppler cerebral ultrasound. Cerebral blood flow velocity and blood pressure decreased, while regional cerebral oxygenation increased during general anesthesia. Ultrafast spectral Doppler ultrasound offers novel insights into perfusion within the cerebral cortex, unattainable through conventional spectral ultrasound. Yet, ultrafast Doppler is curtailed by a lower success rate and a more rigorous learning curve compared to conventional method.

Vector Flow Imaging of the Ascending Aorta in Patients with Tricuspid and Bicuspid Aortic Valve Stenosis Treated with Biological and Mechanical Implants

Aortic valve stenosis (AS) is treated with biological prostheses (BPs) and mechanical prostheses (MPs). Vector flow imaging (VFI), an angle-independent ultrasound method, can quantify flow complexity (vector concentration (VC)) and secondary rotation (SR). Ten patients (mean age: 70.7 y) with tricuspid AS scheduled for BPs, 10 patients (mean age: 56.2 y) with bicuspid AS scheduled for MPs and 10 patients (mean age: 63.9 y) with normal aortic valves were scanned intra-operatively on the ascending aorta with VFI and conventional spectral Doppler. Bicuspid AS (peak systolic velocity (PSV): 380.9 cm/s, SR: 16.7 Hz, VC: 0.21) had more complex flow (p < 0.02) than tricuspid AS (PSV: 346.1 cm/s, SR: 17.1 Hz, VC: 0.33). Both groups had more complex and faster flow (p < 0.0001) than normal aortic valve patients (PSV: 124.0 cm/s, SR: 4.3 Hz, VC: 0.79). VC (r = 0.87) and SR (r = 0.89) correlated to PSV. After surgery, flow parameters changed (p < 0.0001) for patients with MPs (PSV: 250.4 cm/s, SR: 9.8 Hz, VC: 0.54) and BPs (PSV: 232.4 cm/s, SR: 12.5 Hz, VC: 0.61), with MPs having slower SR (p < 0.01). None of the implants had normal flow (p < 0.0001). In conclusion, VFI can provide new flow parameters for AS and implant assessment.

Fetal Myocardial Performance Index in the Third Trimester of Pregnancy: Feasibility and Reproducibility of Conventional Spectral Doppler versus Spectral Tissue Doppler Technique.

This study aims to compare completion rates and reproducibility of myocardial performance index (MPI) using conventional spectral Doppler versus tissue Doppler in an unselected high-risk third trimester population. This was a prospective cross-sectional study of high-risk pregnancies at ≥28 + 0 weeks' gestation. Conventional spectral and tissue Doppler MPI of the left ventricle (LV) and right ventricle (RV) was attempted on all patients. Seventy-nine pregnancies were evaluated. LV tissue Doppler MPI was completed more frequently than LV conventional spectral Doppler MPI (63/79, 79.7% vs. 45/79, 55.7%), p-value <0.01. RV tissue Doppler MPI was completed more frequently than RV conventional spectral Doppler MPI (68/79, 86% vs. 42/79, 53.2%), p-value <0.01. In obese subjects (n = 50) LV tissue Doppler MPI was completed more frequently than LV conventional spectral Doppler MPI (37/50, 74% vs. 26/50, 52%), p-value <0.01. RV tissue Doppler MPI was completed more frequently than RV conventional spectral Doppler MPI (40/50, 80% vs. 25/50, 50%), p-value <0.01. intraclass correlation coefficient for all modalities ranged between 0.73 and 0.93, except for LV conventional spectral Doppler intraobserver variability which was 0.22. Tissue Doppler had statistically higher completion rates than conventional spectral Doppler, including the obese subgroup, with evidence of strong reproducibility in the third trimester.

The assessment of cardiac function with tissue Doppler imaging in fetuses with congenital diaphragmatic hernia

Introduction: This study aimed to evaluate the cardiac function of fetuses with congenital diaphragmatic hernia by conventional echocardiography and spectral tissue Doppler imaging (s-TDI) and to evaluate the relationship between cardiac function and the severity of pulmonary hypoplasia. We also aimed to investigate the effect of diaphragmatic hernia side on fetal cardiac function.Methods: Fetal cardiac function were evaluated in 28 fetuses (20 with left-sided and 8 with right-sided) complicated with isolated congenital diaphragmatic hernia (CDH) and 56 gestational age matched control in this single center prospective study. s-TDI measurements were obtained at the right atrioventricular valve annulus. The annular peak velocities and their ratios, the time periods of cardiac cycle and myocardial performance index were calculated.Results: In comparison to controls, significantly prolonged isovolumetric contraction time (ICT′) and isovolumetric relaxation time (IRT′) and, significantly shortened ejection time (ET′) were observed in fetuses with CDH by s-TDI. Fetuses with CDH also had higher myocardial performance index (MPI′) z-scores compared to controls. There were no significant differences in terms of s-TDI cardiac function parameters between fetuses with right- and left-sided CDH. In correlation analysis, a significant positive correlation was found between ET′ value and o/e LHR.Conclusion: The signs of both systolic and diastolic altered function were observed in fetuses with CDH with s-TDI independent of the side of the hernia, and a significant positive correlation was observed between fetal cardiac systolic function and the severity of pulmonary hypoplasia.

PhD defence about the ultrasound technique Vector Flow Imaging

Thor Bechsgaard, MD, defended the PhD thesis “In Vivo Vector Flow Imaging of Venous Flow in the Lower Extremities of healthy Volunteers and Patients with Chronic Venous Disease” on the 17th of December. The work leading to the thesis was a collaboration between the Department of Diagnostic Radiology at University Hospital Copenhagen, Rigshospitalet and Technical University of Denmark. The PhD thesis compared the relatively new ultrasound technique with the conventional technique spectral Doppler ultrasound in healthy volunteers and patients with chronic venous disease. The technical thesis found comparable precision of the relatively new technique in all three published journal paper: “Vector and Doppler Ultrasound Velocities Evaluated in a Flow Phantom and the Femoropopliteal Vein”, “Evaluation of Peak Reflux Velocities with Vector Flow Imaging and Spectral Doppler Ultrasound in Varicose Veins”, and “Respiratory Variability of Peak Velocities in the Common Femoral Vein Estimated with Vector Flow Imaging and Doppler Ultrasound”. The thesis is available on Researchgate.com: https://www.researchgate.net/publication/330 370 583_PhD-thesis_In_Vivo_Vector_Flow_Imaging_of_Venous_Flow_in_the_Lower_Extremities_of_Healthy_Volunteers_and_Patients_with_Chronic_Venous_Diseases .

Feasibility of UltraFast Doppler in Post-operative Evaluation of Hepatic Artery in Recipients following Liver Transplantation

To determine the feasibility of using UltraFast Doppler in post-operative evaluation of the hepatic artery (HA) after liver transplantation (LT), we evaluated 283 simultaneous conventional and UltraFast Doppler sessions in 126 recipients over a 2-mo period after LT, using an Aixplorer scanner The Doppler indexes of the HA (peak systolic velocity [PSV], end-diastolic velocity [EDV], resistive index [RI] and systolic acceleration time [SAT]) by retrospective analysis of retrieved waves from UltraFast Doppler clips were compared with those obtained by conventional spectral Doppler. Correlation, performance in diagnosing the pathologic wave, examination time and reproducibility were evaluated. The PSV, EDV, RI and SAT of spectral and UltraFast Doppler measurements exhibited excellent correlation with favorable diagnostic performance. During the bedside examination, the mean time spent for UltraFast clip storing was significantly shorter than that for conventional Doppler US measurements. Both conventional and UltraFast Doppler exhibited good to excellent inter-analysis consistency. In conclusion, compared with conventional spectral Doppler, UltraFast Doppler values correlated excellently and yielded acceptable pathologic wave diagnostic performance with reduced examination time at the bedside and excellent reproducibility.

Left Ventricular Diastolic Dysfunction Assessed by Conventional Echocardiography and Spectral Tissue Doppler Imaging in Adolescents With Arterial Hypertension.

Compared to conventional echocardiography, spectral tissue Doppler imaging (s-TDI) allows more precise evaluation of diastolic cardiac function. The purpose of this study was to conduct s-TDI to analyze the slow movement of the left ventricular (LV) myocardium in adolescents with systemic arterial hypertension (HT) and to determine whether patients with HT suffer from LV diastolic dysfunction. The study group comprised 69 consecutive patients (48 boys and 21 girls aged 14–17 years [mean, 15.5 ± 1.1 years]) with primary HT, and the control group comprised 48 healthy participants (24 boys and 24 girls aged 14–17 years [mean, 15.8 ± 1.3 years]). Physical examinations, 24-hour arterial blood pressure monitoring, conventional 2-dimensional and Doppler echocardiography, and s-TDIs were performed. Analysis revealed that study group participants were significantly heavier and had greater LV mass indices than controls (P < 0.001). There were no differences between the velocities of E waves (peak early filling of mitral inflow), but the deceleration times of the mitral E waves were significantly shorter whereas the A waves survived longer in the study group than in the control group. The velocities of A waves (peak late filling of mitral inflow) were elevated (P = 0.041), and the E/A wave pattern (E/A = 1.8 ± 0.4) was normal. These results suggest pseudonormalization, a type of LV diastolic dysfunction in adolescents with HT.In the study group, when the sample volume was positioned at the septal or lateral insertion site of the mitral leaflet, the e′ wave velocity was significantly depressed whereas the a′ wave velocity was elevated, compared to those of the control group (P < 0.001).The e′/a′ ratios from the septal and lateral insertion sites were lower, whereas the E/e′ ratio from the septal insertion site was significantly higher in the study group, similar to that seen in atrial reversal velocity (P < 0.001).These findings indicate that using sTDI to find and measure diastolic LV failure is valuable when the probe is placed at the septal and lateral mitral valve annuli during examination.Changes in the myocardium appear similar to those seen in adults.

Comparison of Carotid Artery Blood Velocity Measurements by Vector and Standard Doppler Approaches

Although severely affected by the angle dependency, carotid artery peak systolic velocity measurements are widely used for assessment of stenosis. In this study, blood peak systolic velocities in the common and internal carotid arteries of both healthy volunteers and patients with internal carotid artery stenosis were measured by two vector Doppler (VD) methods and compared with measurements obtained with the conventional spectral Doppler approach. Although the two VD techniques were completely different (using the transmission of focused beams and plane waves, respectively), the measurement results indicate that these techniques are nearly equivalent. The peak systolic velocities measured in 22 healthy common carotid arteries by the two VD techniques were very close (according to Bland–Altman analysis, the average difference was 3.2%, with limits of agreement of ±8.6%). Application of Bland–Altman analysis to comparison of either VD technique with the spectral Doppler method provided a 21%–25% average difference with ±13%–15% limits of agreement. Analysis of the results obtained from 15 internal carotid arteries led to similar conclusions, indicating significant overestimation of peak systolic velocity with the spectral Doppler method. Inter- and intra-operator repeatability measurements performed in a group of 8 healthy volunteers provided equivalent results for all of the methods (coefficients of variability in the range 2.7%–6.9%), even though the sonographers were not familiar with the VD methods. The results of this study suggest that the introduction of vector Doppler methods in commercial machines may finally be considered mature and capable of overcoming the angle-dependent overestimation typical of the standard spectral Doppler approach.

Left ventricular radial colour and longitudinal pulsed-wave tissue Doppler echocardiography in 39 healthy domestic pet rabbits

This paper reports radial colour and longitudinal mitral annulus pulsed-wave tissue Doppler findings in a large cohort of healthy, adult pet rabbits. Thirty-nine rabbits (22 Dwarf Lops, 14 French Lops and three Alaskans) underwent conscious echocardiography. The median age of the rabbits was 22 months and the median weight was 2.8 kg (Dwarf Lop 2.4 kg/French Lop 6.0 kg). Adequate radial colour and longitudinal pulsed-wave tissue Doppler traces were obtained in 100% and 85% of cases, respectively. Most systolic tissue Doppler parameters were significantly higher in French Lops than in Dwarf Lops. Separation of mitral inflow diastolic waves was present in 40% of cases using conventional spectral Doppler and in >60% of cases using pulsed-wave tissue Doppler which could be beneficial when evaluating diastolic function in rabbits. This study can be used as a reference for normal echocardiographic tissue Doppler values for adult rabbits undergoing conscious echocardiography in clinical practice.

In Vivo Lateral Blood Flow Velocity Measurement Using Speckle Size Estimation

In previous studies, we proposed blood measurement using speckle size estimation, which estimates the lateral component of blood flow within a single image frame based on the observation that the speckle pattern corresponding to blood reflectors (typically red blood cells) stretches (i.e., is “smeared”) if blood flow is in the same direction as the electronically controlled transducer line selection in a 2-D image. In this observational study, the clinical viability of ultrasound blood flow velocity measurement using speckle size estimation was investigated and compared with that of conventional spectral Doppler of carotid artery blood flow data collected from human patients in vivo. Ten patients (six male, four female) were recruited. Right carotid artery blood flow data were collected in an interleaved fashion (alternating Doppler and B-mode A-lines) with an Antares Ultrasound Imaging System and transferred to a PC via the Axius Ultrasound Research Interface. The scanning velocity was 77 cm/s, and a 4-s interval of flow data were collected from each subject to cover three to five complete cardiac cycles. Conventional spectral Doppler data were collected simultaneously to compare with estimates made by speckle size estimation. The results indicate that the peak systolic velocities measured with the two methods are comparable (within ±10%) if the scan velocity is greater than or equal to the flow velocity. When scan velocity is slower than peak systolic velocity, the speckle stretch method asymptotes to the scan velocity. Thus, the speckle stretch method is able to accurately measure pure lateral flow, which conventional Doppler cannot do. In addition, an initial comparison of the speckle size estimation and color Doppler methods with respect to computational complexity and data acquisition time indicated potential time savings in blood flow velocity estimation using speckle size estimation. Further studies are needed for calculation of the speckle stretch method across a field of view and combination with an appropriate axial flow estimator.

Intraoperative Cardiac Ultrasound Examination Using Vector Flow Imaging

Conventional ultrasound (US) methods for blood velocity estimation only provide one-dimensional and angle-dependent velocity estimates; thus, the complexity of cardiac flow has been difficult to measure. To circumvent these limitations, the Transverse Oscillation (TO) vector flow method has been proposed. The vector flow method implemented on a commercial scanner provided real-time, angle-independent estimates of cardiac blood flow. Epicardiac and epiaortic, intraoperative US examinations were performed on three patients with stenosed coronary arteries scheduled for bypass surgery. Repeating cyclic beat-to-beat flow patterns were seen in the ascending aorta and pulmonary artery of each patient, but these patterns varied between patients. Early systolic retrograde flow filling the aortic sinuses was seen in the ascending aorta as well as early systolic retrograde flow in the pulmonary artery. In diastole, stable vortices in aortic sinuses of the ascending aorta created central antegrade flow. A stable vortex in the right atrium was seen during the entire heart cycle. The measurements were compared with estimates obtained intraoperatively with conventional spectral Doppler US using a transesophageal and an epiaortic approach. Mean differences in peak systole velocity of 11% and 26% were observed when TO was compared with transesophageal echocardiography and epiaortic US, respectively. In one patient, the cardiac output derived from vector velocities was compared with pulmonary artery catheter thermodilution technique and showed a difference of 16%. Vector flow provides real-time, angle-independent vector velocities of cardiac blood flow. The technique can potentially reveal new information of cardiovascular physiology and give insight into blood flow dynamics.

Total isovolumic time, a marker of left ventricular global dyssynchrony, is prolonged with age

Cardiologia CROATICA Background and Aim: Total isovolumic time (T-IVT) and Tei index both reflect global left ventricular (LV) global dyssynchrony. They have been shown to be sensitive in responding to myocardial revascularization and in predicting clinical outcome in heart failure patients. Since most of these patients are senior, determining the exact effect of age on such parameters remains mandatory. The aim of this study was to investigate the effect of age on LV T-IVT and Tei index compared with conventional systolic and diastolic parameters in a group of normal individuals. Methods: We studied 47 healthy subjects, mean age 62 ±12 years, 23 males using conventional spectral Doppler echocardiography and tissue-Doppler imaging. T-IVT was measured as [60 — (total ejection time + total filling time) in s/min], and Tei index calculated as (T-IVT/ejection time). Results: LV ejection fraction was 68 ±6%, E/A ratio 1 ±0.4, filling time 538 ±136 ms, ejection time 313 ±26 ms, T-IVT 7.7 ±2.6 s/min and Tei index 0.41 ±0.14. Age strongly correlated with T-IVT (r=0.8, p<0.001) and Tei index (r=0.7, p<0.001). Age also correlated, although to a lesser extent, with E/A ratio (r=-0.6, p<0.001), but not bearing any relationship with global or segmental systolic function measurements. Conclusions: In normal individuals, age is associated with exaggerated LV global dyssynchrony and diastolic function disturbances, but systolic function remains unaffected.

Ventricular Structure and Function in Children With Sickle Cell Disease Using Conventional and Tissue Doppler Echocardiography

Conventional 2-dimensional, M-mode, and spectral Doppler echocardiographic techniques have documented abnormal ventricular function in adults with sickle cell disease (SCD), but assessments in children are conflicting. Tissue Doppler echocardiography (TDE) provides additional information about myocardial function. Two-dimensional, M-mode, tricuspid regurgitation jet velocity (TRJV) data, and tissue Doppler echocardiographically derived myocardial velocity measurements of left ventricular (LV) and right ventricular function were taken from children with SCD compared to those of similar healthy historical controls and correlated with clinical characteristics and hemoglobin levels. Compared to 55 controls, 54 children with SCD (mean age 14.2 years, range 6 to 21) had a larger left ventricle, greater LV mass, and higher LV fractional shortening; 30% had increased pulmonary artery pressure (TRJV ≥2.5 m/s). Conventional echocardiographic measurements of LV systolic function and spectral Doppler measurements of LV and right ventricular diastolic function were essentially normal, but TDE indicated that 31% of SCD children had evidence of LV diastolic dysfunction (peak early diastolic velocity of LV inflow Doppler/peak early diastolic velocity at lateral mitral valve annulus >8), a finding that correlated with lower hemoglobin levels. Although decreasing hemoglobin levels in children with SCD correlated with LV hypertrophy, LV dilation, and LV diastolic dysfunction, long-term transfusion or hydroxyurea therapy did not affect these measurements. In conclusion, 1/3 of children with SCD had tissue Doppler echocardiographic evidence of LV diastolic dysfunction, which was correlated with hemoglobin levels. Adding serial assessments of ventricular function with TDE to conventional echocardiography may detect early cardiac changes, especially in children with severe anemia.

État de l’art en imagerie médicale – RSNA 2010: 96th Assembly and Annual Meeting, November 28 to December 3 2010, Mc Cormick Place, Chicago Illinois

To determine the feasibility of using UltraFast Doppler in post-operative evaluation of the hepatic artery (HA) after liver transplantation (LT), we evaluated 283 simultaneous conventional and UltraFast Doppler sessions in 126 recipients over a 2-mo period after LT, using an Aixplorer scanner The Doppler indexes of the HA (peak systolic velocity [PSV], end-diastolic velocity [EDV], resistive index [RI] and systolic acceleration time [SAT]) by retrospective analysis of retrieved waves from UltraFast Doppler clips were compared with those obtained by conventional spectral Doppler. Correlation, performance in diagnosing the pathologic wave, examination time and reproducibility were evaluated. The PSV, EDV, RI and SAT of spectral and UltraFast Doppler measurements exhibited excellent correlation with favorable diagnostic performance. During the bedside examination, the mean time spent for UltraFast clip storing was significantly shorter than that for conventional Doppler US measurements. Both conventional and UltraFast Doppler exhibited good to excellent inter-analysis consistency. In conclusion, compared with conventional spectral Doppler, UltraFast Doppler values correlated excellently and yielded acceptable pathologic wave diagnostic performance with reduced examination time at the bedside and excellent reproducibility.

Two-Dimensional Flow Index Mapping for Hemodynamic Imaging: A Feasibility Study

The resistive index (RI) is a functional hemodynamic index used to measure flow resistance within an organ, such as the kidney, to assess if there is any vascular disease associated with that organ. Currently, the measurement of RI values using spectral Doppler ultrasound (US) is performed in one location at a time. As a result, RI values are typically obtained only from a few locations. To visualize the entire two-dimensional distribution of RI values, we developed a method called two-dimensional flow index mapping (2D-FIM). To evaluate this method, we performed a feasibility study using 16 kidney data sets, with eight from healthy volunteers with normal native kidneys and eight from kidney transplant recipients. Quadrature-demodulated baseband Doppler data were used to calculate the spatial distribution of RI values using 2D-FIM. For comparison, the intrarenal RI values at different levels of renal arterial branches were measured with conventional spectral Doppler US. The RI values determined from 2D-FIM were compared with those from spectral Doppler US, which led to a Pearson correlation coefficient of 0.84. There was no significant difference between 2D-FIM– and spectral Doppler US–produced RI values. With the ability to visualize RI in more than one dimension, 2D-FIM could help guide placement of the spectral Doppler range gate to regions of abnormal RI, thus potentially reducing exam times. (E-mail: ykim@u.washington.edu)

Lung Tissue Blood Perfusion Changes Induced by in utero Tracheal Occlusion in a Rabbit Model of Congenital Diaphragmatic Hernia

Objective: To analyze the impact of in utero tracheal occlusion (TO) on lung tissue blood perfusion, as measured by fractional moving blood volume (FMBV) and conventional spectral Doppler, in a rabbit model of congenital diaphragmatic hernia (CDH). Methods: In 50 fetal rabbits, a left CDH was surgically created at 23 days of gestational age (GA). At 28 days of GA, the surviving CDH fetuses were randomly assigned to undergo either TO (CDH+TO group) or a sham operation (CDH group). Twenty littermates, which were not operated on, served as internal normal controls. At 30 days of GA, lung perfusion estimated by FMBV and spectral Doppler of the proximal intrapulmonary artery were evaluated in the right lung during cesarean section. Doppler waveform analysis included the pulsatility index (PI), peak early diastolic reverse flow and peak systolic velocity. Results: Eleven CDH fetuses, 9 CDH+TO and 20 controls were suitable for the study. CDH fetuses showed a significantly higher PI [8.0 (SD 1.8) vs. 5.22 (SD 1.1), p < 0.001] and lower FMBV [13.5% (SD 4.6) vs. 23.0% (SD 2.1), p < 0.001] than the controls. In contrast, CDH+TO fetuses had a significantly lower PI [5.8 (SD 2.3) vs. 8.0 (SD 1.8), p = 0.015] and higher FMBV [27.6% (SD 7.1) vs. 13.5% (SD 4.6), p < 0.001] than CDH fetuses, with values similar to the controls. Peak early diastolic reverse flow and peak systolic velocity showed nonsignificant differences among the study groups. The lung to body weight ratio at necropsy correlated positively with lung FMBV (r = 0.60, p < 0.001) and negatively with the pulmonary artery PI (r = –0.48, p < 0.01). Conclusion: Tracheal occlusion is consistently associated with increased lung tissue perfusion and decreased intrapulmonary impedance in a rabbit model of CDH.

Myocardial tissue Doppler assessment of diastolic function in the growth‐restricted fetus

Myocardial tissue Doppler (MTD) is a technique for the measurement of myocardial velocities in systole and diastole. This study evaluates the use of MTD in the assessment of cardiac diastolic function in fetuses with intrauterine growth restriction (IUGR) with placental insufficiency and in appropriate-for-gestational age (AGA) fetuses with hypertensive mothers. This study included 14 IUGR fetuses with placental insufficiency (Group 1), 13 AGA fetuses with hypertensive mothers (Group 2), and 29 AGA fetuses with healthy mothers (Group 3). Patients with other diseases were excluded. All fetuses had a gestational age of at least 25 weeks. MTD assessment was performed with the sample volume placed at the basal segment of the left ventricular side wall (LV), the interventricular septum (IVS) and the right ventricular free wall (RV). E'/A' ratios were calculated for each location. Mitral and tricuspid flows were assessed by conventional spectral pulsed Doppler. Significant differences were found between groups for E'/A' at the IVS (P < 0.001) and LV (P = 0.009), with a higher mean (+/- SD) value in Group 1 (IVS: 0.92 +/- 0.28; LV: 0.85 +/- 0.19) than in Groups 2 (IVS: 0.62 +/- 0.09; LV: 0.68 +/- 0.14) and 3 (IVS: 0.71 +/- 0.14; LV: 0.69 +/- 0.15). In the RV, there was no statistically significant difference in the E'/A' ratio (P = 0.2). No differences were observed for mitral and tricuspid flow velocities and ratios. Using MTD, the ratios between early and late diastolic myocardial velocities are higher in IUGR fetuses than in AGA fetuses at the IVS and the LV, regardless of the presence of maternal hypertension. MTD may be more sensitive than atrioventricular spectral Doppler for the detection of ventricular diastolic dysfunction in IUGR fetuses.

Noninvasive assessment of testicular torsion in rabbits using frequency-domain near-infrared spectroscopy: prospects for pediatric urology

We present a quantitative near-IR spectroscopy study of the absolute values of oxygen saturation of hemoglobin before and after surgically induced testicular torsion in adult rabbits. Unilateral testicular torsions (0, 540, or 720 deg) on experimental testes and contralateral sham surgery on control testes are performed in four adult rabbits. A specially designed optical probe for measurements at multiple source-detector distances and a commercial frequency-domain tissue spectrometer are used to measure absolute values of testicular hemoglobin saturation. Our results show: (1) a consistent baseline absolute tissue hemoglobin saturation value of 78+/-5%, (2) a comparable tissue hemoglobin saturation of 77+/-6% after sham surgery, and (3) a significantly lower tissue hemoglobin saturation of 36+/-2% after 540- and 720-deg testicular torsion surgery. Our findings demonstrate the feasibility of performing frequency-domain, multidistance near-IR spectroscopy for absolute testicular oximetry in the assessment of testicular torsion. We conclude that near-IR spectroscopy has potential to serve as a clinical diagnostic and monitoring tool for the assessment of absolute testicular hemoglobin desaturation caused by torsion, with the possibility of serving as a complement to conventional color and spectral Doppler ultrasonography.

Noninvasive assessment of left-to-right shunting in ventricular septal defects by the proximal isovelocity surface area method on Doppler colour flow mapping

The proximal isovelocity surface area (PISA), which is the zone of flow convergence appearing on the left ventricular septal surface where flow approaching the defect accelerates, allows quantitative estimation of ventricular septal defect (VSD) flow and defect area on colour Doppler imaging. In the present study, the clinical applicability and reliability of the PISA method in assessing the amount of left-to-right shunting in patients with VSDs were evaluated. Fifty-eight patients aged 0.25 to 15 years (mean age 4.3+/-4.4 years) with VSDs were prospectively studied. Maximum PISA radius in peak systole (r), peak velocity (V(max)) and velocity time integral (VTI(VSD)) of flow through the VSD were measured. In addition, peak VSD flow (2pir(2) Nyquist limit [NL]), amount of left-to-right shunting (Qp-Qs = heart rate x [2pir(2) x NL x VTI(VSD)]/V(max)) and defect area ([2pir(2) x NL]/V(max)) were calculated. There were significant positive correlations between Qp-Qs values calculated by PISA and other spectral Doppler methods using the cross-sectional area, as well as the VTI of pulmonary-aortic (r=0.73, P<0.001) or mitral-tricuspid (r=0.58, P<0.001) flows and cardiac catheterization (20 patients, r=0.82, P<0.001). PISA-derived left-to-right-shunting discriminated moderate to large defects from small defects, which were classified according to the catheter-derived Qp/Qs ratio (2 or greater versus less than 2; P=0.001) or clinical evaluation (P<0.001). The present study demonstrated that the PISA method is a reliable semiquantitative method to determine the amount of left-to-right shunting of VSDs and to discriminate moderate to large defects from small defects. Consequently, this method may serve as a simple and useful adjunct to conventional spectral Doppler methods in the noninvasive assessment of patients with VSDs.