Spatiotemporal image correlation combined with high-definition live rendering mode and tomographic ultrasound imaging for evaluating fetal cardiac hemangioma in the right atrium: a case description

Introduction

Fetal cardiac masses are rare, with an incidence of 0.14–0.26‰ among live births, and cardiac hemangiomas are even more uncommon, accounting for 10–15% of fetal cardiac tumors (0.01–0.03‰ among live births) (1-4). To the best of our knowledge, this is the first report describing the evaluation of a fetal right atrial intracardiac mass via spatial-temporal image correlation (STIC) combined with high-definition live (HD live) rendering and tomographic ultrasound imaging (TUI). The combined application of these two three-dimensional (3D) ultrasounds techniques provides enhanced diagnostic information, facilitating the accurate diagnosis of hemangioma and guiding the formulation of perinatal management strategies. Previous studies have demonstrated the utility of 3D ultrasound and HD live rendering mode in the evaluation of fetal cardiac tumors, suggesting that these techniques could potentially offer additional diagnostic insights (5,6).

Case presentation

A 27-year-old primigravid woman (G1P0) was referred for targeted fetal echocardiography at 30 weeks of gestation following the incidental detection of an intracardiac mass during routine third-trimester ultrasound. She had no family history of congenital heart disease or genetic syndromes, and the results of noninvasive prenatal screening were unremarkable. Fetal echocardiography was performed with a Voluson E10 ultrasound system (GE HealthCare, Chicago, IL, USA) equipped with a volumetric convex transducer (2–5 MHz). All procedures in this study were performed in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of West China Second University Hospital, Sichuan University (ethics No. K2019060). Written informed consent was obtained from the patient for the publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Two-dimensional (2D) echocardiography revealed a well-circumscribed, homogeneous hyperechoic mass in the fetal right atrium, 13 mm × 12 mm in size (Figure 1A), accompanied by approximately 3 mm of pericardial effusion. Color Doppler imaging failed to visualize intralesional blood flow due to the rapid fetal heart rate (Figure 1B). STIC volume acquisition was performed in accordance with the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) Practice Guidelines for fetal cardiac screening (7). The acquisition parameters included a sweep angle of 30°, a volume rate of 280 Hz, and an acquisition time of 2 seconds (yielding approximately 560 frames per volume). The quality of each acquired volume was immediately assessed based on the following criteria: (I) absence of fetal movement or breathing artifacts, (II) complete inclusion of the cardiac mass and surrounding structures within the volume box, and (III) adequate spatial and temporal resolution for reliable offline postprocessing analysis. Volumes that did not meet these quality criteria were re-acquired. HD live rendering was performed with the following settings: surface rendering mode, a threshold value of 40, and a transparency of 60. HD live rendering was used to generate 3D surface reconstructions, which clearly delineated the contour of the mass, its extensive endocardial attachment, and its anatomical relationship with the tricuspid valve (Figure 1C-1E). TUI produced multiplanar parallel slices (analogous to computed tomography), which clearly demonstrated the heterogeneous internal echoes of the mass and multiple small anechoic areas (with a maximum size of 3 mm × 2 mm) while suggesting the absence of gross myocardial invasion (Figure 1F,1G). Antenatal follow-up examinations demonstrated no evidence of fetal cardiac dysfunction, valvular obstruction, or arrhythmias. The patient underwent vaginal delivery at 40 weeks of gestation. Neonatal echocardiography (Figure 2A,2B) demonstrated an enlarged right atrial mass measuring 17 mm × 21 mm in size, accompanied by 4 mm of pericardial effusion. Cardiac magnetic resonance imaging (MRI) (Figure 3A-3D) revealed a 21 mm × 18 mm round mass originating from the right atrial lateral wall. The asymptomatic infant underwent surgical resection at 1 month of age, and histopathological examination confirmed the diagnosis of a mixed capillary-cavernous hemangioma of the right atrium. To date, the infant remains in good clinical condition.

Figure 1 Fetal right atrial hemangioma at 30 weeks’ gestation evaluated by 2D echocardiography, color Doppler, and STIC combined with HD live rendering and TUI. (A) Two-dimensional four-chamber view demonstrated a well-circumscribed, homogeneous hyperechoic mass (yellow arrow) in the fetal right atrium, accompanied by a small amount of pericardial effusion (green arrow). (B) Color Doppler imaging indicated no obvious blood flow signal within the mass. (C-E) STIC volume acquisition combined with HD live rendering provided high-definition 3D surface views of the right atrial hemangioma. The round-like mass with an irregular surface and its attachment to the atrial septum in close proximity to the tricuspid valve leaflets—spatial relationships that are difficult to appreciate on 2D imaging alone—were clearly demonstrated. (F,G) TUI multislice display revealed heterogeneous internal echotexture with multiple discrete anechoic cystic spaces (green arrows), suggesting vascular channels present within a hemangioma. Contiguous slices also demonstrated an intact myocardial wall with no evidence of gross invasion. 2D, two-dimensional; 3D, three-dimensional; HD, high-definition; STIC, spatial-temporal image correlation; TUI, tomographic ultrasound imaging.

Figure 2 Neonatal echocardiographic four-chamber view confirming the prenatal diagnosis. (A) A clear, well-circumscribed, relatively homogeneous hyperechoic mass was demonstrated in the neonatal right atrium. (B) No obvious blood flow signal was found within the mass.

Figure 3 Postnatal cardiac MRI. (A) Cardiac cine sequence showed a round-like mass arising from the right lateral wall of the right atrium protruding into the cardiac cavity, with motion synchronous to cardiac contraction, measuring approximately 21 mm × 18 mm in size. (B) The lesion manifested as a slightly hyperintense signal on fat-saturated T2-weighted imaging. (C) On T1-weighted imaging, there was a heterogeneous isointense signal of the mass, with multiple cribriform hypointense foci within the lesion. (D) Marked homogeneous enhancement of the mass was observed on delayed-phase postcontrast imaging. MRI, magnetic resonance imaging.

Discussion

Fetal cardiac hemangiomas are extremely rare benign vascular endothelial tumors, accounting for less than 3% of fetal cardiac tumors; right atrial hemangiomas are particularly uncommon, with only 50 cases reported worldwide. The small anechoic cystic spaces within hemangiomas correspond to dilated vascular channels, and the identification of this imaging feature in prenatal examinations facilitates precise qualitative diagnosis (8). Although 2D echocardiography serves as the first-line screening method for fetal cardiac masses, advanced 3D techniques (i.e., STIC, HD live, and TUI) can improve diagnostic accuracy by facilitating the detection of microcystic changes.

STIC enables rapid and reproducible acquisition of cardiac volume data, and multimodal offline postprocessing provides additional diagnostic information.

The combination of STIC and HD (STIC-HD) can clarify the 3D spatial relationship between the mass and adjacent cardiac structures (9). STIC-HD can, in this case, provide an intuitive visualization of the mass contour, its precise spatial relationship with the tricuspid valve, and the full extent of its endocardial attachment. This comprehensive anatomical assessment may serve as a valuable reference for planning postnatal surgical intervention, and prospective validation is thus warranted.

TUI has the potential to offer the additional advantage of multiplanar tomographic display, allowing for a systematic, slice-by-slice evaluation of the internal architecture of the mass. In our case, TUI clearly demonstrated the heterogeneous internal echoes and multiple small anechoic cystic spaces, which represent the vascular channels characteristic of a hemangioma. Moreover, the contiguous tomographic slices enabled a confident exclusion of gross myocardial invasion, a finding of major prognostic significance. However, it should be acknowledged that fetal MRI offers superior soft-tissue contrast and remains the reference standard for the definitive exclusion of subtle myocardial infiltration. In our case, postnatal MRI provided additional tissue characterization that further indicated the vascular nature of the mass, although fetal MRI was not performed.

Prenatal differential diagnosis of fetal cardiac tumors is essential for informed counseling. The most common tumor, rhabdomyoma, typically appears on TUI as multiple, homogeneous, hyperechoic intramural nodules without cystic components. Teratomas are characterized by a complex heterogeneous appearance on TUI, often with both cystic and solid elements and occasional calcifications. Fibromas most commonly present as a solitary, large, solid, homogeneous intramural mass. On TUI, they manifest as a uniform echotexture without the anechoic vascular spaces seen in hemangiomas. In contrast, our case of hemangioma was distinguished by STIC-HD delineation of an endocardial right atrial mass and TUI demonstration of heterogeneous internal echotexture with multiple small anechoic cystic spaces, corresponding to its vascular nature. The presence of these features, coupled with the absence of gross myocardial invasion on TUI, aided in narrowing the differential diagnosis prenatally. For right atrial masses specifically, nontumorous entities such as a prominent Eustachian valve or Chiari network must also be considered. These structures can be distinguished from a true neoplasm by their characteristic anatomical location and the absence of mass-like echotexture on TUI. The very rare right atrial myxoma represents another differential consideration: on STIC-HD, a myxoma typically appears as a mobile, pedunculated mass attached to the interatrial septum, which is in contrast to the broad-based, sessile endocardial attachment observed in our case of hemangioma.

Several limitations of STIC-HD and TUI should be acknowledged. First, the diagnostic quality of these 3D reconstructions is contingent upon optimal volume acquisition. Fetal movement, maternal body habitus, and unfavorable fetal position can introduce motion artifacts that degrade image resolution and potentially obscure fine details. Second, both image acquisition and the subsequent offline postprocessing analysis are operator-dependent and require substantial expertise. Third, despite the ability of TUI to delineate internal tumor architecture, its soft-tissue contrast resolution is inferior to that of fetal MRI. In our case, fetal MRI was not obtained, which might have limited the definitive prenatal assessment of subtle myocardial infiltration; however, postnatal MRI partially mitigated this limitation. Finally, while the detection of anechoic cystic spaces strongly suggests the diagnosis of a vascular tumor, these imaging features are not entirely specific, and histopathological examination remains necessary for achieving a definitive diagnosis.

Asymptomatic infant cardiac hemangiomas create clinical dilemmas. Guidelines for such cases favor propranolol or surveillance, with surgery being reserved for refractory heart failure, severe obstruction, or malignant arrhythmias. Although operation would be typically avoided for a case of an asymptomatic newborn, early open-heart resection was decided upon in our case due to the persistence of a right atrial mass, an unclear pathology, and elevated risks of tumor enlargement, hemodynamic disturbance, arrhythmia, embolism, and problematic future surgery. A multidisciplinary cardiac team weighed the risks involved, finalized plans via shared decision-making, and obtained parental informed consent. Uniform guidelines on intervention timing are lacking, and practices across centers are inconsistent. As this was a personalized strategy, it should not be universally adopted in similar patients.

The value of advanced 3D sonographic techniques, including STIC-HD, in characterizing fetal cardiac tumors has been emphasized in the recent literature (6,10). This case supports the added value of STIC, HD live, and TUI in the prenatal characterization of rare fetal cardiac masses, particularly in defining internal echotexture and anatomical relationships, which is critical for guiding perinatal management decisions. However, as this report is based on a single case, confirmation and selection bias cannot be ruled out. Thus, the diagnostic value of the findings remains preliminary and for the generation of hypotheses only. Larger prospective cohort studies are required to verify whether advanced 3D sonography offers additional clinical benefits as compared with conventional 2D echocardiography.

Acknowledgments

The authors would like to express their gratitude to the reviewers for their valuable professional comments and suggestions.

Footnote

Funding: This work was supported by grants from Technology Project of Sichuan Province of China (Nos. 2024YFFK0367 and 2024YFFK0078) and the National Natural Science Foundation of China (No. 82270249).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2026-1007/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Ethics Committee of West China Second University Hospital, Sichuan University (ethics No. K2019060). Written informed consent was obtained from the patient for the publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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