4D Flow MRI using retrospective valve tracking for assessing atrioventricular valve regurgitantion in Fontan patients

Presenting Author(s)

• 

  Masaki Kodaira, MD, PhD

  Associate Professor
  Keio University
  Shinjuku, Tokyo, Japan

Primary Author(s)

• 

  Masaki Kodaira, MD, PhD

  Associate Professor
  Keio University
  Shinjuku, Tokyo, Japan

Co-Author(s)

• HM

  Hirozumi Mori, MD

  Instructor
  Keio University School of Medicine, Tokyo, Japan
• TO

  Takayuki Oyanagi, MD

  Associate Professor
  Keio University Hospital
  Shinjuku, Tokyo, Japan
• SM

  Shigeki Miura, RT

  Technologist
  Keio University Hospital
  Shinjuku, Tokyo, Japan
• SM

  Sari Motomatsu

  Chief
  Keio University Hospital, Japan
• RT

  Ryo Tsukada

  Deputy Chief
  Keio University Hospital, Japan
• NS

  Naofumi Suumitomo, MD, PhD

  Associate Professor
  Keio University Hospital
  Shinjuku, Tokyo, Japan
• TN

  Takehiro Nakahara, MD, PhD

  Associate Professor
  Keio University School of Medicine, Tokyo, Japan
• YY

  Yoshitake Yamada, MD, PhD

  Keio University School of Medicine, Japan
• NK

  Naritaka Kimura, MD, PhD

  Assistant Professor
  Keio University School of Medicine, Tokyo, Japan
• MJ

  Masahiro Jinzaki, MD

  Professor
  Keio University School of Medicine, Japan
• MI

  Masaki Ieda, MD, PhD

  Professor
  Keio University Hospital
  Shinjuku, Tokyo, Japan

Background: Atrioventricular valve regurgitation (AVVR) is a major determinant of adverse outcomes in patients with single-ventricle physiology after Fontan surgery. Accurate quantification of AVVR is therefore critical in this population. In the general population, retrospective valve tracking with 4D flow MRI is the most commonly applied technique for evaluating mitral regurgitation. However, its validity in patients with single-ventricle physiology following Fontan surgery remains uncertain. We aimed to evaluate the accuracy of this method in this unique cohort.

Methods: Nine patients with single-ventricle physiology after Fontan operation underwent cardiac magnetic resonance (CMR), including 4D flow MRI, at our center between March 2024 and July 2025. Examinations were performed on a 1.5T GE Artist scanner, and image post-processing was conducted using cvi42 (version 6.2.2; Circle Cardiovascular Imaging). AVVR was quantified using two approaches: (1) the retrospective valve tracking method, and (2) a conventional indirect 2D phase-contrast (PC) method, calculated as single-ventricle stroke volume from SSFP imaging minus sinotubular junction (STJ) forward flow, divided by single-ventricle forward stroke volume minus aortic regurgitation (Figure 1). Agreement between the two methods was evaluated using Pearson correlation analysis.

Results: Tricuspid atresia was the most common underlying diagnosis. Seven patients had undergone extracardiac conduit (ECC) Fontan, while two had atriopulmonary connection (APC) Fontan surgery. Both quantification methods demonstrated mild AVVR, with mean regurgitant fractions of 3.46% using the valve tracking method and 3.47% using the indirect 2D PC method. As shown in Figure 2, a strong correlation was observed between the two techniques (r = 0.945, p = 0.0001).

Conclusion: Retrospective valve tracking with 4D flow MRI provides a reliable approach for quantifying AVVR in patients with single-ventricle physiology after Fontan surgery.

Patient clinical characteristics

Patient	Age	Sex	Diagnosis	Type of Fontan surgery
1	45	Male	Transposition of the great arteries with hypoplastic left ventricle	APC
2	43	Female	Tricuspid atresia	ECC
3	34	Male	Double inlet right ventricle	ECC
4	23	Male	Tricuspid atresia	ECC
5	31	Female	Tricuspid atresia	ECC
6	23	Female	Tricuspid atresia	ECC
7	43	Male	Double inlet left ventricle	ECC
8	25	Male	Criss-cross heart with double outlet right ventricle	ECC
9	35	Male	Tricuspid atresia	APC

ECC denotes extracardiac conduit; APC atriopulmonary connection.Figure 1. Comparison between the two techniques to assess atrioventricular regurgitant fraction. 4D denotes 4-dimensional; SSFP steady-state free-precession; 2D PC 2-dimensional phase contrast.
Figure 2. Comparision of 4D flow MRI valve tracking vs. 2D PC indirect calculation for quantification of AVVRF. r = Pearson correlation coefficient. AVRRF denotes atrioventricular regurgitant fraction; 2D PC 2-dimensional phase contrast. .