Superb Microvascular Imaging Generation 4 for Demonstration of Placental Microvasculature

Toshiyuki Hata¹, Tomomi Kawahara², Aya Koyanagi³, Riko Takayoshi⁴, Takahito Miyake⁵

^1,4,5Department of Obstetrics and Gynecology, Miyake Clinic, Okayama, Japan, Department of Perinatology and Gynecology, Kagawa University Graduate School of Medicine, Miki, Kagawa, Japan

^2,3Department of Obstetrics and Gynecology, Miyake Clinic, Okayama, Japan

Corresponding Author: Toshiyuki Hata, Department of Obstetrics and Gynecology, Miyake Clinic, Okayama, Japan, Department of Perinatology and Gynecology, Kagawa University Graduate School of Medicine, Miki, Kagawa, Japan Phone: +810878912174, e-mail: hata.toshiyuki@kagawa-u.ac.jp

Received on: 22 August 2022; Accepted on: 30 September 2022; Published on: 30 June 2023

ABSTRACT

Objective: To present placental microvasculature using superb microvascular imaging generation 4^® (SMI Gen4).

Material and methods: A total of 20 healthy pregnancies were studied to describe placental microvasculature using transabdominal SMI Gen4 at 13–36 weeks of gestation.

Results: Superb microvascular imaging generation 4^® (SMI Gen4) clearly depicted primary, secondary, as well as tertiary stem villous vessels late in the first trimester of pregnancy. Volcanic eruption-like spiral artery jet flow (SAJ) was noted early in the second trimester of pregnancy. Increased placental vascularity was noted after the second trimester of pregnancy.

Conclusion: SMI Gen4 may become a new diagnostic tool for the observation of placental microvasculature late in the first trimester of pregnancy. This modality may provide unique information on the prediction of fetoplacental insufficiency and hypertensive disorder during pregnancy.

How to cite this article: Hata T, Kawahara T, Koyanagi A, et al. Superb Microvascular Imaging Generation 4 for Demonstration of Placental Microvasculature. Donald School J Ultrasound Obstet Gynecol 2023;17(2):109–111.

Source of support: Nil

Conflict of interest: Dr. Toshiyuki Hata is associated as the Scientific Editor of this journal and this manuscript was subjected to this journal’s standard review procedures, with this peer review handled independently of this Scientific Editor and his research group.

Keywords: Firsttrimester, Placental microvasculature, Secondtrimester, Superb Microvascular Imaging Generation 4, Thirdtrimester

Several studies have reported conventional two-dimensional (2D)/three-dimensional (3D) superb microvascular imaging (SMI) features of normal and abnormal placental architectures.¹^,⁷ With the newest advances in Doppler ultrasound technology, SMI generation 4 (SMI Gen4) has been developed to expand the range of visible blood flow from ultra-low to high flow with low noise and good sensitivity.⁸ There has been no study to demonstrate placental microvasculature using SMI Gen4. In this investigation, we showed placental microvasculature using this technique during pregnancy.

A total of 20 normal pregnancies were studied to observe placental microvasculature with SMI Gen4 (Canon Aplio i700, Canon Medical Systems, Tokyo, Japan) with a transabdominal linear probe (Canon i18LX5, 5–18 MHz, Canon Medical Systems, Tokyo, Japan) at 13–36 weeks of gestation. Volume data for 3D-SMI were acquired by fanning the 2D transducer. Smart 3D technology was used to show 3D images.² The study was performed after obtaining approval from the Ethics Committee of Miyake Clinic. The aim of the study was fully explained to all participants who, after that, provided their oral informed consent.

In the normal placenta at 13 week’s gestation, primary, secondary, and tertiary stem villous vessels were clearly noted using SMI Gen4 (Fig. 1). Volcanic eruption-like appearance of spiral artery jet flow (SAJ) was evident at 17 weeks of gestation (Fig. 2). Increased placental vascularity was noted in the second and third trimesters of pregnancy (Figs 3 and 4).

Figs 1A and B: A normal placenta at 13 weeks of gestation; SMI Gen4 clearly depicts intraplacental vessels; PSV, primary stem villous vessel; SSV, secondary stem villous vessel; TSV, tertiary stem villous vessel; (A) 2D image; (B) 3D image

Figs 2A and B: A normal placenta at 17 weeks of gestation; SMI Gen4 clearly depicts intraplacental vessels and the volcanic eruptionlike appearance of SAJ; CSV, chorionic surface vessel; DV, decidual vessel; PSV, primary stem villous vessel; SSV, secondary stem villous vessel; TSV, tertiary stem villous vessel; (A) 2D image; (B) 3D image

Figs 3A and B: A normal placenta at 27 weeks of gestation; SMI Gen4 clearly demonstrates intraplacental vessels’ CSV, chorionic surface vessel; DV, decidual vessel; PSV, primary stem villous vessel; SSV, secondary stem villous vessel; TSV, tertiary stem villous vessel; (A) 2D image; (B) 3D image

Figs 4A and B: A normal placenta at 36 weeks and 5 days of gestation; SMI Gen4 clearly shows luxuriant intraplacental vessels; CSV, chorionic surface vessel; DV, decidual vessel

Using conventional SMI, only primary and secondary stem villous vessels were identified, while tertiary stem villous vessels could not be demonstrated in the first trimester of pregnancy.² In the present investigation, fine primary, secondary, as well as tertiary stem villous vessels could be clearly noted using SMI Gen4 at 13 weeks of gestation. Moreover, the volcanic eruption-like appearance of SAJ was evident at 17 weeks of gestation. However, the image quality of placental microvasculature in the third and third trimesters of pregnancy using the new technique was the same as those of conventional SMI. This technique may provide novel information on the early prediction of fetoplacental insufficiency and hypertensive disorder of pregnancy in future clinical practice and trials.

REFERENCES

1. Hasegawa J, Suzuki N. SMI for imaging of placental infarction. Placenta 2016;47:96–98. DOI: 10.1016/j.placenta.2016.08.092

2. Hata T, Kanenishi K, Yamamoto K, et al. Microvascular imaging of thick placenta with fetal growth restriction. Ultrasound Obstet Gynecol 2018;51(6):837–839. DOI: 10.1002/uog.18837

3. Mack LM, Mastrobattista JM, Gandhi R, et al. Characterization of placental microvasculature using superb microvascular imaging. J Ultrasound Med 2019;38(9):2485–2491. DOI: 10.1002/jum.14919

4. Hasegawa J, Kurasaki A, Hata T, et al. Diagnosis of placenta accreta spectrum using ultra-high-frequency probe and Superb Microvascular Imaging. Ultrasound Obstet Gynecol 2019;54:705–707. DOI: 10.1002/uog.20207

5. Furuya N, Hasegawa J, Homma C, et al. Novel ultrasound assessment of placental pathological function using superb microvascular imaging. J Matern Fetal Neonatal Med 2022;35(16):3036–3039. DOI: 10.1080/14767058.2020.1795120

6. Furuya N, Hasegawa J, Doi M, et al. Accuracy of prenatal ultrasound in evaluating placental pathology using superb microvascular imaging: a prospective observation study. Ultrasound Med Biol 2022;48(1):27–34. DOI: 10.1016/j.ultrasmedbio.2021.09.002

7. Hata T, Koyanagi A, Takayoshi R, et al. Superb microvascular imaging assessment of placenta using an 18-MHz probe. Donald School J Ultrasound Obstet Gynecol 2021;15(3):312–322. DOI: 10.5005/jp-journals-10009-1714

8. Hata T, Kawahara T, Koyanagi A, et al. Superb microvascular imaging generation 4 for depiction of fetal peripheral microvessels. Donald School J Ultrasound Obstet Gynecol 2022;16(4):329–334. DOI: 10.5005/jp-journals-10009-1945

________________________
© The Author(s). 2023 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and non-commercial reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.