Characterization of Placental Microvascular Architecture by MV-Flow Imaging in Normal and Fetal Growth-Restricted Pregnancies

Ultrasound microvascular flow imaging: evaluating fetal mesenteric blood flow and predicting postnatal surgery in meconium peritonitis

OBJECTIVE

This study explored the characteristics of fetal mesenteric blood flow perfusion across various gestational weeks and evaluated the efficacy of Microvascular Flow (MV-Flow) imaging technology in assessing intestinal wall blood flow in fetuses with meconium peritonitis (MP).

METHOD

In this retrospective study, we analyzed 35 fetuses with MP and 160 healthy fetuses. We examined the correlation between the Vascular Index (VI) of mesenteric perfusion and gestational age, conducted an analysis comparing MP operative and non-operative groups, and developed a predictive model for surgical intervention.

RESULTS

The VI value demonstrated no significant change with increasing gestational age (correlation coefficient = 0.005, p = 0.946). For healthy fetuses, VI ranged approximately from 34.66% to 67.26% using the automatic ellipse method. The MP operative group exhibited significantly more cesarean deliveries (100% vs. 52.9%, p = 0.003), shorter gestational periods (34.76 ± 2.16 weeks vs. 37.48 ± 1.55 weeks, p < 0.001), lower birth weights (2762.14 ± 452.76 g vs. 3225.88 ± 339.98 g, p = 0.003), more persistent ascites (92.9% vs. 52.9%, p = 0.021), more frequent intestinal wall echo reductions (57.1% vs. 5.9%, p = 0.004), and lower VI (18.57 ± 5.51% vs. 39.41 ± 7.02%, p < 0.001). A predictive model was established: Logit (P)=8.86 - (0.37* VI) + (1.49* ascites), yielding an area under the curve of 0.857, with 78.6% sensitivity and 88.2% specificity. The VI value was significantly associated with the need for postnatal surgery (OR = 0.689, 95% confidence interval: 0.511 - 0.929, p = 0.015). A Receiver Operating Characteristic curve analysis for VI in predicting postnatal surgery showed an area under the curve of 0.971, with an optimal cutoff value of 35%, achieving 91% sensitivity and 94.4% specificity.

CONCLUSION

MV-Flow imaging effectively quantified fetal bowel wall blood flow perfusion. There was no significant change in VI across different gestational weeks. Significantly lower VI values in MP fetuses indicated an increased risk of intestinal wall necrosis and the potential need for postnatal surgical intervention.

The placental blood perfusion and LINC00473-mediated promotion of trophoblast apoptosis in fetal growth restriction

This study aimed to investigate placental microblood flow perfusion in fetal growth restriction (FGR) both pre- and post-delivery, and explore the influence of LINC00473 and its downstream targets on FGR progression in trophoblast cells. Placental vascular distribution, placental vascular index (VIMV), CD34 expression, and histological changes were compared between control and FGR groups. FGR-related differentially expressed genes (DEGs) were analyzed and validated by quantitative real-time polymerase chain reaction (qPCR) and immunohistochemistry (IHC) in placentae. In vitro experiments examined the regulatory relationships among LINC00473, miR-5189-5p, and StAR, followed by investigations into their impacts on cell proliferation and apoptosis. FGR placentae exhibited irregular shapes, uneven parenchymal echo, stromal dysplasia, ischemic infarction, and variable degrees of thickening in some cases. FGR samples showed less prominent mother vessel lakes, significantly lower VIMV, and decreased CD34 expression. Hematoxylin & eosin (H&E) staining revealed placental fibrosis, fibrin adhesion, infarction, and interstitial dysplasia in FGR. LINC00473, miR-5189-5p, and StAR were identified as DEG, with qPCR demonstrating a significant increase in LINC00473 and a decrease in miR-5189-5p in FGR, while both qPCR and IHC indicated a significant increase in StAR expression. LINC00473 served as an endogenous sponge against miR-5189-5p in human HTR-8/SV neo cells, and StAR expression was regulated by both LINC00473 and miR-5189-5p. Dysregulation of these genes affected cell proliferation and apoptosis. Pathological changes in the placenta are significant contributors to FGR, with placental microblood flow potentially serving as an indicator for monitoring its progression. LINC00473 and its downstream targets may modulate trophoblasts proliferation and apoptosis, thus influencing the onset of FGR, suggesting novel avenues for diagnosis and treatment.

Ultrasound Microvessel Imaging of the Human Placenta Demonstrates Altered Vessel Densities in Fetal Growth Restriction With Vascular and Immune Pathologies: A Pilot Case-Control Study

OBJECTIVES

Fetal growth restriction (FGR) is commonly associated with placental dysfunction, increasing perinatal morbidity and mortality. Visualizing placental vessels in utero would be advantageous for identifying functional FGR cause and determining proper management strategies. We aimed to utilize high-sensitivity ultrasound microvessel imaging (HUMI) for quantifying placental vessel density (VD) in pregnancies diagnosed with FGR.

METHODS

This pilot case-control study enrolled subjects in the third trimester with a diagnosis of FGR (n = 40) and gestational age-matched controls with normal fetal growth (n = 20) at a 2:1 ratio, respectively. The Verasonics Vantage ultrasound system was used to perform HUMI on each participant at one timepoint. Scanning involved randomized singular value decomposition-based clutter filtering to identify the villous tree, followed by step-by-step scanning to acquire 3-dimensional-like data. Mean VD was calculated from three ultrasound measurements per subject. Additional clinical and pathology data were also collected and compared.

RESULTS

Sixteen participants were utilized to establish the scanning protocol and 2 met exclusion criteria at delivery. Thus, VD was successfully measured on 42 pregnancies scanned at 35 weeks 5 days on average. In FGR (n = 24), placental VD was significantly reduced compared to controls (P < .01). VD measures were as good at predicting FGR as systolic/diastolic (S/D) ratios (area under the curve 0.86 versus 0.80). In a smaller cohort, VD in placentas with a diagnosis of inflammatory villitis (n = 10) by histology showed an increase in VD compared to those without inflammation (P = .01). Low VD was correlated with increased S/D ratios (P = .03).

CONCLUSIONS

HUMI is useful for identifying altered placental vascularization in utero for FGR. VD may be a valuable indicator for placental health and could lead to improved risk stratification methods considering underlying biology.

Evaluation of fetal cerebral microvascular status and its relationship with fetal growth and development using microvascular imaging technique

The study conducted retrospective analysis design, aiming to explore the use of Microvascular Imaging Technique (MVFI) to assess fetal cerebral microcirculation and analyze the relationship between Microvascular Index (MVI) and fetal growth and development. 100 pregnant women who met the criteria for fetal growth restriction (FGR) provided in the Expert Consensus on Fetal Growth Restriction (2019 Edition) and underwent routine prenatal examinations at the Obstetrics and Gynecology Department of Peking University Third Hospital from January 2021 to June 2023 were selected as the study subjects. A normal fetus with a fetal weight less than 10 % can be classified as FGR, Pregnant women with fetal umbilical artery (UA) systolic and diastolic (S/D) values ≥3 were included in the observation group, while 200 pregnant women with normal fetuses were selected as the control group during the same period. The fetuses' change in both groups were measured using color Doppler ultrasound, including bi-parietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL). The cerebral microcirculation of the fetuses in both groups was evaluated using MVFI, and the MVI values were compared. The clinical characteristics of FGR fetuses with umbilical artery S/D ratio ≥ 3 were summarized, and the correlation between fetal cerebral microvascular status and fetal growth and development was analyzed using Pearson correlation analysis. The outcomes told that the BPD, HC, AC, and FL values of the fetuses in the control group were lower the other's value (P < 0.05), and the MVI and peak systolic velocity of the middle cerebral artery (MCA-PSV) values were also lower in the control group (P < 0.05). Pearson correlation analysis revealed a positive correlation between fetal growth and development and MVI and MCA-PSV values in FGR fetuses. In conclusion, MVFI can monitor and quantitatively analyze fetal intracranial microcirculation, visualize slow blood flow in microvascular structures, and this study provides preliminary evidence of the close relationship between fetal cerebral microcirculation and intrauterine growth and development.

Effectiveness of microvascular flow imaging for radiofrequency ablation in recurrent thyroid cancer: comparison with power Doppler imaging

OBJECTIVES

To compare microvascular flow imaging (MVFI) and power Doppler ultrasonography imaging (PDUS) for detecting intratumoral vascularity in recurrent thyroid cancer both before and after radiofrequency ablation (RFA).

METHODS

This retrospective study included 80 patients (age, 57 ± 12 years; 54 women) with 110 recurrent tumors who underwent RFA between January 2021 and June 2023. A total of 151 PDUS and MVFI image sets were analyzed (85 pre-RFA, 66 post-RFA). Two readers assessed vascularity on the images using a four-point scale with a 2-week interval between PDUS and MVFI to estimate inter-reader agreement. Intra-reader agreement was determined by reinterpreting images in reverse order (MVFI-PDUS) after a 1-month gap. Additionally, diagnostic performance for identifying viable tumors after RFA was assessed in 44 lesions using thyroid-protocol CT as a reference standard.

RESULTS

MVFI demonstrated higher vascular grades than PDUS, both before (reader 1: 3.04 ± 1.15 vs. 1.93 ± 1.07, p < 0.001; reader 2: 3.20 ± 0.96 vs. 2.12 ± 1.07, p < 0.001) and after RFA (reader 1: 2.44 ± 1.28 vs. 1.67 ± 1.06, p < 0.001; reader 2: 2.62 ± 1.23 vs. 1.83 ± 0.99, p < 0.001). Inter-reader agreement was substantial (κ = 0.743) and intra-reader agreement was almost perfect (κ = 0.840). MVFI showed higher sensitivity (81.5%-88.9%) and accuracy (84.1%-86.4%) than PDUS (sensitivity: 51.9%, p < 0.01; accuracy: 63.6-70.5%, p < 0.04), without sacrificing specificity.

CONCLUSION

MVFI was superior to PDUS for assessing intratumoral vascularity and showed good inter- and intra-reader agreement, highlighting its clinical value for assessing pre-RFA vascularity and accurately identifying post-RFA viable tumors in recurrent thyroid cancer.

CLINICAL RELEVANCE STATEMENT

Microvascular flow imaging (MVFI) is superior to power-Doppler US for assessing intratumoral vascularity; therefore, MVFI can be a valuable tool for assessing vascularity before radiofrequency ablation (RFA) and for identifying viable tumors after RFA in patients with recurrent thyroid cancer.

KEY POINTS

The value of microvascular flow imaging (MVFI) for evaluating intratumoral vascularity is unexplored. MVFI demonstrated higher vascular grades than power Doppler US before and after ablation. Microvascular flow imaging showed higher sensitivity and accuracy than power Doppler US without sacrificing specificity.

Visualization of placental villi: Three-dimensional ultrasound imaging shows coral-like placental villous trees

We introduce a new microflow imaging technique, which can show the blood perfusion and morphological structure of placental villi.

Immediate Effect of Electro-acupuncture on Endometrial Blood Flow in Patients with Recurrent Implantation Failure: A Randomized Controlled Trial

OBJECTIVE

To investigate the immediate effects of electro-acupuncture (EA) on endometrial blood flow among recurrent implantation failure (RIF) patients.

METHODS

Eighty RIF patients, enrolled from March 2022 to December 2022, were randomly allocated into either the EA group (40 cases) or the waiting-list (WL) group (40 cases) by using a random number table. The EA group underwent acupuncture at points of Shenting (GV 24), Baihui (GV 4), Benshen (GB 13), bilateral Zigong (EX-CA 1), Huangshu (KI 16), Sanyinjiao (SP 6) and Xuehai (SP10), and electric acupuncture apparatus was connected to EX-CA 1, KI 16, SP 6, and SP 10 with disperse-dense waves at 4/20 Hz frequencies for 30 min after transvaginal ultrasound, while the WL group received no intervention. The primary outcome measured was the endometrial volume blood flow. The secondary outcomes included the bilateral uterine artery index, endometrial volume, endometrial blood flow type, vascular distribution index (VIMV) for endometrial and ovary, clinical pregnancy rate, and embryo implantation rate.

RESULTS

In the EA group, there was a notable decrease in the bilateral pulsatility index and a significant improvement in the endometrial blood flow type post-EA (P<0.05). Both the endometrial blood flow type and VIMV for the endometrium and right ovary were markedly higher in the EA group compared to the WL group post-treatment (P<0.05). Conversely, no significant disparities were observed in vascular index, flow index, vascular blood flow index, uterine arterial blood flow indices, endometrial volume, clinical pregnancy rate and embryo implantation rate between the two groups after treatment (P>0.05). Besides, no adverse events related to EA were observed.

CONCLUSIONS

EA can promptly ameliorate VIMV for the endometrial and right ovary, and endometrial blood flow type. Future randomized controlled trials are warranted to investigate the long-term effects of EA on blood flow of RIF patients and its implications for pregnancy outcomes. (Trial registration No. ChiCTR2200057377).

The Placenta in Congenital Heart Disease: Form, Function and Outcomes

The maternal-fetal environment, controlled and modulated by the placenta, plays a critical role in the development and well-being of the fetus, with long-term impact through programming of lifelong health. The fetal cardiovascular system and placenta emerge at the same time embryologically, and thus placental form and function are altered in the presence of congenital heart disease (CHD). In this review, we report on what is known about the placenta from a structural and functional perspective when there is CHD. We describe the various unique pathologic findings as well as the diagnostic imaging tools used to characterize placental function in utero. With growing interest in the placenta, a standardized approach to characterizing placental pathology has emerged. Furthermore, application of ultrasonography techniques and magnetic resonance imaging now allow for insights into placental blood flow and functionality in vivo. An improved understanding of the intriguing relationship between the placenta and the fetal cardiovascular system will provide opportunities to develop novel ways to optimize outcomes. Once better understood, therapeutic modulation of placental function offered during the vulnerable period of fetal plasticity may be one of the most impactful ways to alter the course of CHD and its complications.

New microvascular ultrasound techniques: abdominal applications

Microvascular ultrasound (MVUS) is a new ultrasound technique that allows the detection of slow-velocity flow, providing the visualization of the blood flow in small vessels without the need of intravenous contrast agent administration. This technology has been integrated in the most recent ultrasound equipment and applied for the assessment of vascularization. Compared to conventional color Doppler and power Doppler imaging, MVUS provides higher capability to detect intralesional flow. A growing number of studies explored the potential applications in hepatobiliary, genitourinary, and vascular pathologies. Different flow patterns can be observed in hepatic and renal focal lesions providing information on tumor vascularity and improving the differential diagnosis. This article aims to provide a detailed review on the current evidences and applications of MVUS in abdominal imaging.

Visualisation of microvascular flow in benign uterine disorders: a pilot study of a new diagnostic technique

BACKGROUND

Uterine disorders have clear overlapping symptoms and ultrasound discrimination is not always easy. Accurately measuring vascularity is of diagnostic and prognostic value. Power Doppler is limited to imaging only the larger vessels. Assessment of the microvasculature requires advanced machine settings.

OBJECTIVES

In this pilot study, we aimed to test the feasibility of microvascular flow imaging of benign uterine disorders.

MATERIAL AND METHODS

Two experienced gynaecologists (JH, RL) randomly applied power Doppler and MV-flowTM mode during a single day, in ten patients each visiting the outpatient clinic. Images of eight patients were labelled with a diagnosis by the attending physicians and collected as coded data.

MAIN OUTCOME MEASURES

Microvascular flow images of normal uterine architecture including the fallopian tube, and of benign disorders such as fibroids, adenomyosis, endometriosis and uterine niches were collected. For both Doppler techniques, qualitative descriptive evaluation of the vascular architecture and a quantitative vascular index of fibroids were provided. Finally, we evaluated the effect of the cardiac cycle.

RESULTS

All microvascular flow images showed more distinctive vascular structures than visible on power Doppler. Calculating a vascular index for fibroids on 2D MV-flowTM images was easily performed on-site. During the cardiac cycle a higher vascular index (VI 75.2) is obtained in systole as compared with diastole (VI 44.0).

CONCLUSION

Microvascular flow imaging allowed detailed visualisation of the uterine vascular architecture and is easy to use.

WHAT IS NEW?

Microvascular flow imaging may be of added value for diagnosing uterine disorders, as well as for pre- and post-operative assessment of suited surgical techniques. Yet, validation with histology and clinical outcomes is required.

A rare case of bilateral testicular metastasis from ileocecal NET: multiparametric US detection

Testicular metastasis are rare findings and bilateral metastasis of testes are extremely rare. Here we are describing for the first time a case of bilateral testicular metastasis in a patient with a known ileocecal valve NET using an in-depth ultra-sound studying including microvascular flow imaging (MV-flow), ultra-sound new technique, able to detect small vessel slow-signal.

Use of new microcirculation software allows the demonstration of dermis vascularization

AIMS

Current ultrasound (US) Doppler techniques cannot demonstrate the vascularization of the dermis. The purpose of this study was to investigate whether the new Superb Vascular Imaging (SMI) and Microvascular Flow (MV-Flow) techniques improve the detection of normal dermis vessels. SMI and MV-Flow were compared side-by-side to conventional power-Doppler (PD) imaging.

METHODS

By using US, 50 healthy volunteers were evaluated at level of five body areas: forehead, forearm, palm, buttock, and thigh. Two off-site operators evaluated the images to assess the difference between SMI and PD imaging and between MV-Flow and PD imaging in terms of dermis flow amount. A 0-3 scoring system was adopted.

RESULTS

SMI scored grade 0 in 0% of body areas, grade 1 in 58%, grade 2 in 33%, and grade 3 in 9%. In comparison with SMI, PD scored grade 0 in 38% of body areas, grade 1 in 56%, grade 2 in 6%, and grade 3 in 0%. MV-Flow scored grade 0 in 0% of body areas, grade 1 in 52%, grade 2 in 43%, and grade 3 in 6%. Comparted to MV-Flow, PD scored grade 0 in 53% of body areas, grade 1 in 34%, grade 2 in 13%, and grade 3 in 0%. The difference in terms of sensitivity was statistically significant for all the body areas investigated.

CONCLUSIONS

We found both SMI and MV-Flow to be superior to PD imaging and capable to demonstrate normal vascularization of the dermis.

Imaging of placental circulations by 4D sonography with high-definition flow and spatiotemporal image correlation technology

Conventionally, two- and three- dimensional color Doppler ultrasonography are used to examine the placental vascularization, but there are limitations in the examinations. In this report, spatiotemporal image correlation (STIC) volume acquisition in high-definition flow, displayed in glass-body mode was used to study the placental vascularization in eight pregnancies. At 20 weeks' gestation, STIC technique allowed visualization of blood flow in the intraplacental branches of the umbilical artery (IPB) and the spiral artery jets in a cardiac cycle. In particular, blood flow from a mega jet penetrating more than half of the placental thickness was demonstrated. Small blood flow from a tertiary order branch of the IPB traversing the placenta and sharply diminishing into the uterine wall was also demonstrated. There were differences in the IPB pattern between normal pregnancies and pregnancies at risk of fetal growth restriction/pre-eclampsia. There were also differences in the appearance of IPB between 20- and 33-weeks' gestation. The results of this report support that it is feasible to use STIC technology to study the placental vascularization. This novel application of STIC technology can increase the understanding of the complex vascularization.

Microvascular assessment of fascio-cutaneous flaps by ultrasound: A large animal study

Objectives: Blood perfusion quality of a flap is the main prognostic factor for success. Microvascular evaluation remains mostly inaccessible. We aimed to evaluate the microflow imaging mode, MV-Flow, in assessing flap microvascularization in a pig model of the fascio-cutaneous flap. Methods: On five pigs, bilateral saphenous fascio-cutaneous flaps were procured on the superficial femoral vessels. A conventional ultrasound evaluation in pulsed Doppler and color Doppler was conducted on the ten flaps allowing for the calculation of the saphenous artery flow rate. The MV-Flow mode was then applied: for qualitative analysis, with identification of saphenous artery collaterals; then quantitative, with repeated measurements of the Vascularity Index (VI), percentage of pixels where flow is detected relative to the total ultrasound view area. The measurements were then repeated after increasing arterial flow by clamping the distal femoral artery. Results: The MV-Flow mode allowed a better follow-up of the saphenous artery's collaterals and detected microflows not seen with the color Doppler. The VI was correlated to the saphenous artery flow rate (Spearman rho of 0.64; p = 0.002) and allowed to monitor the flap perfusion variations. Conclusion: Ultrasound imaging of microvascularization by MV-Flow mode and its quantification by VI provides valuable information in evaluating the microvascularization of flaps.

Evaluation of tenosynovitis in patients with seronegative rheumatoid arthritis using microvascular flow imaging

OBJECTIVES

The purpose of this research was investigate the potential use of MVFI (microvascular flow imaging) in the assessment of tenosynovitis in cases with SNRA (seronegative rheumatoid arthritis).

METHODS

Fifty-six SNRA cases and 20 HCs (healthy controls) were enrolled, and all of them were subjected to ultrasonographic examination of the compartments I-VI of the extensor tendons of the wrist, flexor carpi radialis and flexor tendons of the five digits. Each tendon synovial sheath was semi-quantitatively scored by GS (gray-scale) ultrasound, PD (power Doppler) ultrasound, and MVFI. The PD and MVFI scores for each tendon synovial sheath were added up for each patient to get the total scores. GS scores, PD scores, and MVFI scores of tendon synovial sheaths were compared between the two groups. The correlations of total PD scores and total MVFI scores with DAS28 (disease activity scores in 28 joints), ESR (erythrocyte sedimentation rate), and CRP (C-reactive protein) were analyzed.

RESULTS

(1) In the HC group (480 tendons), GS revealed abnormalities in 29 (6.04%) tendon synovial sheaths. The GS score was 1.03 ± 0.18 with the predominance of GS grade 1 (96.55%). In the SNRA group (1,344 tendons), GS detected abnormalities in 418 tendon synovial sheaths (31.10%). The GS score was 1.97 ± 0.53 with the predominance of GS grade 2 (71.77%). There were significant differences in the GS examination rate and grade for tenosynovitis between the two groups (P < 0.05). (2) In the SNRA group, involvement of the extensor carpi ulnaris in the 6^th dorsal compartment was the most common among all extensor tendons; the flexor tendon of the third digit was the most commonly affected among all flexor tendons. (3) In the HC group, the MVFI and PD scores were 0 for tendon synovial sheaths upon GS examination. In the SNRA group, the blood flow display rate of abnormal tendon synovial sheaths indicated by GS was 83.49% and 64.59% upon MVFI and PD, respectively. The results of the two imaging techniques were significantly different (P < 0.05). The blood flow grade of abnormal tendon synovial sheaths indicated by GS was significantly different between MVFI and PD (P < 0.05), which was higher upon MVFI than PD. (4) The total MVFI score and the total PD score in the SNRA group were correlated positively with CRP, ESR and DAS28 (P < 0.05).

CONCLUSION

MVFI is a more sensitive way in detection of blood flow in the tendon synovial sheaths of SNRA cases, which may be used in clinic to evaluate disease activity and tenosynovitis in SNRA cases.

Doppler evaluation of normal and abnormal placenta

Doppler techniques are needed for the evaluation of the intraplacental circulation and can be of great value in the diagnosis of placental anomalies. Highly sensitive Doppler techniques can differentiate between the maternal (spiral arteries) and fetal (intraplacental branches of the umbilical artery) components of the placental circulation and assist in the evaluation of the placental functional units. A reduced number of placental functional units can be associated with obstetric complications, such as fetal growth restriction. Doppler techniques can also provide information on decidual vessels and blood movement. Abnormal decidual circulation increases the risk of placenta accreta. Doppler evaluation of the placenta greatly contributes to the diagnosis and clinical management of placenta accreta, vasa previa, placental infarcts, placental infarction hematoma, maternal floor infarction, massive perivillous fibrin deposition and placental tumors. However, it has a limited role in the diagnosis and clinical management of placental abruption, placental hematomas, placental mesenchymal dysplasia and mapping of placental anastomoses in monochorionic twin pregnancies. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.