Three-dimensional vascular indices calculated using conventional power Doppler and high-definition flow imaging: are there differences?

A 10-Year Retrospective Review of Prenatal Applications, Current Challenges and Future Prospects of Three-Dimensional Sonoangiography

Realistic reconstruction of angioarchitecture within the morphological landmark with three-dimensional sonoangiography (three-dimensional power Doppler; 3D PD) may augment standard prenatal ultrasound and Doppler assessments. This study aimed to (a) present a technical overview, (b) determine additional advantages, (c) identify current challenges, and (d) predict trajectories of 3D PD for prenatal assessments. PubMed and Scopus databases for the last decade were searched. Although 307 publications addressed our objectives, their heterogeneity was too broad for statistical analyses. Important findings are therefore presented in descriptive format and supplemented with the authors’ 3D PD images. Acquisition, analysis, and display techniques need to be personalized to improve the quality of flow-volume data. While 3D PD indices of the first-trimester placenta may improve the prediction of preeclampsia, research is needed to standardize the measurement protocol. In highly experienced hands, the unique 3D PD findings improve the diagnostic accuracy of placenta accreta spectrum. A lack of quality assurance is the central challenge to incorporating 3D PD in prenatal care. Machine learning may broaden clinical translations of prenatal 3D PD. Due to its operator dependency, 3D PD has low reproducibility. Until standardization and quality assurance protocols are established, its use as a stand-alone clinical or research tool cannot be recommended.

Resistance Training Does Not Decrease Placental Blood Flow During Valsalva Maneuver: A Novel Use of 3D Doppler Power Flow Ultrasonography

BACKGROUND

The Valsalva maneuver may increase maternal blood pressure and intra-abdominal pressure, resulting in decreased blood flow to the fetus during resistance training.

HYPOTHESIS

There is no significant reduction in placental blood flow in pregnancy during resistance training in recreational athletes, as documented by a 3-dimensional power flow Doppler ultrasonography.

STUDY DESIGN

Cohort.

LEVEL OF EVIDENCE

Level 3.

METHODS

A cohort of healthy women who participated in recreational athletics was enrolled in a prospective study to assess placental blood flow during a resistance exercise. A 1 repetition maximum (1RM, up to 50 lb) was determined through a modified chest press as a marker of heavy resistance training. Three-dimensional volume measurements and power Doppler flow were determined at the rest phase and during the 1RM lift phase. The vascular flow index (VFI) was calculated to determine placental perfusion during each phase.

RESULTS

A total of 22 women participated. The mean age of participants was 31 years. Gestational age ranged from 13 to 28 weeks. Average 1RM weight lifted was 30 lb. Four women (18%) were able to lift 50 lb, the maximum weight that the study allowed. The remaining 18 women (82%) lifted their true 1RM. Mean VFI during lift phase was 2.185 compared with 2.071 at rest (P = 0.03). There was a slight mean increase in VFI during lift phase, 0.114 (95% CI 0.009-0.182) from 2.071 to 2.185 with lifting (P = 0.03). The 15 women who participated in structured exercise had a mean VFI at rest and during the lift phase of 2.031 and 2.203, respectively (P = 0.01).

CONCLUSION

Three-dimensional power flow Doppler imaging can guide resistance training during pregnancy to prevent fetal injury due to hypoperfusion. Resistance training up to an RM1 of 50 lb did not result in a significant reduction of placental blood flow from resting state in the study population.

CLINICAL RELEVANCE

This technique may be used to guide training parameters among pregnant athletes.

Using Flow Characteristics in Three-Dimensional Power Doppler Ultrasound Imaging to Predict Complete Responses in Patients Undergoing Neoadjuvant Chemotherapy

OBJECTIVES

Strategies are needed for the identification of a poor response to treatment and determination of appropriate chemotherapy strategies for patients in the early stages of neoadjuvant chemotherapy for breast cancer. We hypothesize that power Doppler ultrasound imaging can provide useful information on predicting response to neoadjuvant chemotherapy.

METHODS

The solid directional flow of vessels in breast tumors was used as a marker of pathologic complete responses (pCR) in patients undergoing neoadjuvant chemotherapy. Thirty-one breast cancer patients who received neoadjuvant chemotherapy and had tumors of 2 to 5 cm were recruited. Three-dimensional power Doppler ultrasound with high-definition flow imaging technology was used to acquire the indices of tumor blood flow/volume, and the chemotherapy response prediction was established, followed by support vector machine classification.

RESULTS

The accuracy of pCR prediction before the first chemotherapy treatment was 83.87% (area under the ROC curve [AUC] = 0.6957). After the second chemotherapy treatment, the accuracy of was 87.9% (AUC = 0.756). Trend analysis showed that good and poor responders exhibited different trends in vascular flow during chemotherapy.

CONCLUSIONS

This preliminary study demonstrates the feasibility of using the vascular flow in breast tumors to predict chemotherapeutic efficacy.

Are Results of 4-D Ultrasound Angiography Examinations Dependent on the Doppler Technology Applied? Comparison of Results Obtained from an In Vivo Model

We aimed to evaluate the agreement of results obtained by 4-D spatio-temporal image correlation (STIC) angiography with two options of Doppler technology (power Doppler [PD] and high-definition flow [HDF]) from an ovary as an in vivo model. Thirty-eight ovaries were recorded by trans-vaginal ultrasound examination in the first part of the menstrual cycle. Two STIC sequences (4-D HDF and 4-D PD) were stored. Volumetric pulsatility index, volumetric resistance index and volumetric systolic/diastolic index for each of these sequences were calculated, and their mean values were compared and correlated. Agreement between 4-D HDF and 4-D PD was assessed using the intra-class correlation coefficient. Intra-class correlation coefficients for all three indices were high, but 95% confidence intervals and limits of agreement were wide. We conclude that both 4-D power Doppler and 4-D high-definition flow may be used for calculating volumetric pulsatility index, volumetric resistance index and volumetric systolic/diastolic index from a STIC sequence, at least in ovaries used as an in vivo model. However, values obtained by both methods cannot be used interchangeably.

Three-dimensional high-definition flow in the diagnosis of placental lakes

Placental lakes are sonolucent areas often found in the normal placenta. Most of them are asymptomatic. They are sometimes related to placenta accreta or intrauterine fetal growth restriction, among other conditions. Although Doppler sonography is useful for evaluating noxious placental lakes, it is not easy to adapt Doppler studies to conventional two-dimensional color Doppler sonography because of the low-velocity blood flow and high vascularity in the placenta. Here, we demonstrate how three-dimensional high-definition imaging of flow provides a novel visual depiction of placental lakes, which helps substantially with the differential diagnosis. As far as we know, there have been no previous reports of observation of placental lakes using three-dimensional high-definition imaging of flow.

Are there any differences in three-dimensional placental vascular indices obtained using conventional power Doppler and high-definition flow imaging?

OBJECTIVE

The purpose of this study was to determine whether there are differences in values and reproducibility of three-dimensional (3D) vascular indices obtained on placental volumes using power Doppler (PD) or high-definition flow imaging (HDFI) techniques.

METHODS

A prospective study was performed on 121 uncomplicated singleton pregnancies at 11 + 0 to 13 + 6 weeks of gestation. Two placental volumes were acquired from each pregnancy. Vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were then analyzed and compared. In order to assess the reproducibility of the measurements, two additional placental volumes obtained with both PD and HDFI were acquired in 31 pregnancies and the agreement assessed by intraclass correlation coefficients. Inter-observer variability was assessed by analyzing all the volumes by two observers blinded to each other's.

RESULTS

A significant relationship was observed between the vascular indices values obtained with the two techniques (VI Pearson's r=0.891 p<0.001; FI r=0.769 p<0.001; VFI r=0.847 p<0.001). The median values of VI, FI and VFI were significantly higher when obtained with HDFI imaging. In serial recordings, the ICCs resulted higher when volumes were acquired with HDFI rather than with PD techniques. Similarly, HDFI demonstrated a higher inter-observer reproducibility.

CONCLUSIONS

3D vascular indices calculated using HDFI are higher than those calculated using conventional PD. Although the relationship between the two methods is high, HDFI shows a better reproducibility suggesting its potential clinical application.

Spatiotemporal image correlation with spherical sampling and high-definition flow: new 4-dimensional method for assessment of tissue vascularization changes during the cardiac cycle: reproducibility analysis

OBJECTIVES

To describe and assess the interobserver reproducibility of a new method for evaluation of ovarian vascularization using spatiotemporal image correlation-high definition flow (STIC-HDF).

METHODS

Stored 4-dimensional (4D) STIC-HDF volume data from 39 healthy pre-menopausal fertile women (aged <35 years) examined in the follicular part of the menstrual cycle by transvaginal sonography were assessed by two different examiners blinded from each other (one in Spain the other in Poland). Using 1-cm(3) spherical sampling, the vascularization index (VI) from the most vascularized part of the ovarian stroma was calculated at two different moments of the cardiac cycle (systole and diastole). System settings were kept constant for all patients (pulse repetition frequency, 0.6 kHz; gain, 0.2) with a depth of 40 mm. Analysis was performed offline using 4D software on a personal computer. On the basis of VI and vascularization-flow index (VFI) values during systole and diastole, 4 new 4D indices were defined: 4D systolic/diastolic volumetric index (4D-SDVI = VI(syst)/VI(diast)), 4D hemodynamic volumetric index (4D-HVI = [VI(syst) + VI(diast)]/[VI(syst) - VI(diast)]), 4D systolic/diastolic vascularization-flow index (4D-SDVFI = VFI(syst)/VFI(diast)), and 4D hemodynamic vascularization-flow index (4D-HVFI = [VFI(syst) + VFI(diast)]/[VFI(syst)- VFI(diast)]). Reproducibility of measurements was estimated by calculating the intraclass correlation coefficient (ICC).

RESULTS

The systolic VI, diastolic VI, 4D-SDVI, 4D-HVI, systolic VFI, diastolic VFI, and 4D-HVFI showed good reproducibility (ICC, 0.992, 0.994, 0.879, 0.915, 0.995, 0.995, and 0.893, respectively). The 4D-SDVFI showed moderate reproducibility (ICC, 0.797).

CONCLUSIONS

We describe 4 new 4D vascular indices for assessing tissue vascularization using STIC-HDF technology. Assessment of ovarian vascularization using this STIC-HDF spherical sampling is reliable. The calculation of these new indices is reproducible between two different examiners.

Spatiotemporal image correlation using high-definition flow: a new method for assessing ovarian vascularization

OBJECTIVE

The purpose of this study was to describe a new method for assessing ovarian vascularization using spatiotemporal image correlation (STIC)-high-definition flow (HDF).

METHODS

Thirty healthy premenopausal fertile women were assessed in the follicular part of the menstrual cycle by transvaginal sonography. A 4-dimensional STIC-HDF volume was obtained from the nondominant ovary to assess 3-dimensional (3D) vascular indices (vascularization index [VI] and flow index [FI]) during one cardiac cycle in each women. Using 1-cm(3) spherical sampling, we calculated the VI and FI from the most vascularized part of the ovarian stroma at two different moments of the cardiac cycle (systole and diastole). System settings were kept constant for all of the patients (pulse repetition frequency, 0.9 kHz; gain, 0.8; and depth, 40 mm). We calculated the VI and FI ratios between systole and diastole.

RESULTS

The mean VI during systole (11.485%; SD, 6.7%) was significantly higher than during diastole (8.653%; SD, 5.6%; P < .0001). The mean FI values during systole (47.799 [unitless]; SD, 5.8) and diastole (47.791; SD, 6.0) were nearly identical (P = .993). The VI ratio was 1.35 (95% confidence interval, 1.28-1.42), which means that the mean VI was 35% higher during systole compared to diastole, whereas the FI during systole and diastole remained constant (FI ratio, 1.00; 95% confidence interval, 0.96-1.04). There was a high correlation between VI values during systole and diastole (r(2) = 0.94), whereas this correlation was weaker for the FI (r(2) = 0.45).

CONCLUSIONS

The STIC-HDF method allows assessment of 3D vascular indices throughout the cardiac cycle. Vascularization index calculation is affected by the moment of the cardiac cycle during which the measurement is taken. However, it seems that FI calculation is not affected by the cardiac cycle in the normal nondominant ovary.