Visualization of the spiral artery jet in fetal growth-restricted pregnancy by utilizing spatiotemporal image correlation with high-definition flow

Morphological evaluation of placental vessels for perinatal diagnosis is difficult using conventional ultrasound (US) because of the nature of the tortuous vasculature and coexisting fetomaternal circulation [1]. Spatiotemporal image correlation with high-definition flow (STIC-HDF) is a novel volume analysis approach that uses threeand fourdimensional (3D/4D) US to visualize hemodynamics and tissue perfusion [2]. We herein present our first experience in reconstructing angiographic vascular flow images of a spiral artery jet and swirling flow within a placental lake (PL) using STIC-HDF. A 32-year-old pregnant woman (gravida 1, para 0) was referred to our outpatient unit at 36 ? 3 weeks of gestation because her unborn child was small for gestational age. A US examination, including Doppler US, confirmed normal anatomic findings but showed asymmetric fetal growth restriction (FGR) with a 2-week smaller abdominal circumference and a PL. The patient underwent ritodrine tocolysis to avoid premature labor between 33 and 37 weeks of gestation. The lesion was examined by STIC-HDF with a curved-array transducer (2–5 MHz) (Voluson E8; GE, Milwaukee, WI, USA). STIC-HDF depicted the actual conditions of the large spiral artery jet feeding into the PL with turbulence (Figs. 1, 2). Several follow-up examinations were conducted until birth. A healthy female infant weighing 1770 g (1-/5-min Apgar score, 8/9; umbilical artery blood pH, 7.33) was delivered by elective cesarean section because of breech presentation and FGR at 38 ? 1 weeks of gestation. Pathological examination showed subchorionic spaces surrounded by normal villi and fibrin deposition without subchorionic hematoma or chorionic angioma. These findings were consistent with the diagnosis of a placental lake [1]. To the best of our knowledge, this is the first report of the use of STIC-HDF to confirm 3D/4D angiographic images of so-called mega-jets [1] with flow into a PL and swirling flow in vivo. STIC-HDF allows acquisition of a gated single cardiac cycle in a 4D volume triggered by HDF signals, providing both imageand time-related information [2]. In the present case, 4D cine angiography generated by STIC-HDF revealed the actual condition of the large spiral artery jet and swirling flow within the placental lake in vivo, which is not achievable with conventional US. These findings may highlight the usefulness of STIC-HDF as a tool with which to qualitatively evaluate spiral artery jets in vivo. However, further assessment of its validity, reproducibility,