Comparison of free-running whole-heart 5D and 4D flow imaging to standard 2D phase contrast in patients with congenital heart disease

Thursday, February 5, 2026

5:00 PM - 5:10 PM

Location: Americas II & III and Hall 4 (2nd Lower Level)

Presenting Author(s)

Fabienne Dirbach, MD

Physician, PhD student
Lausanne University Hospital and University of Lausanne
Lausanne, Vaud, Switzerland

Primary Author(s)

Fabienne Dirbach, MD

Physician, PhD student
Lausanne University Hospital and University of Lausanne
Lausanne, Vaud, Switzerland

Co-Author(s)

ET

Estelle Tenisch, MD

Physician
University Hospital (CHUV) and University of Lausanne (UNIL), Switzerland
MP

Milan Prsa, MD

Cardiologist
University Hospital (CHUV) and University of Lausanne (UNIL), Switzerland
Christopher W. Roy, PhD

Lecturer
Lausanne University Hospital (CHUV) and University of Lausanne (UNIL)
Lausanne, Vaud, Switzerland
PG

Paolo Garelli, MSc

PhD student
University Hospital (CHUV) and University of Lausanne (UNIL), Switzerland
SF

Sara Faessler

MS
Lausanne University Hospital and University of Lausanne, Vaud, Switzerland
DR

David Rodrigues, MSc

Deputy chief radiology technician
Lausanne University Hospital and University of Lausanne, Switzerland
EA

Efena Akporeha, MSc

PhD Candidate
Lausanne University Hospital
Lausanne, Vaud, Switzerland
Mariana Falcão, PhD

PhD
University Hospital (CHUV) and University of Lausanne (UNIL)
Lausanne, Vaud, Switzerland
MM

Michael Markl, PhD

Professor
Northwestern University Feinberg School of Medicine
Chicago, Illinois, United States
MS

Matthias Stuber, PhD

Professor/Director
CIBM/CHUV/UNIL
Lausanne, Switzerland
Davide Piccini, PhD

Collaboration Manager
Siemens Healthineers
Lausanne, Vaud, Italy
Juerg Schwitter, MD

Full Professor
University Hospital and University of Lausanne
Lausanne, Vaud, Switzerland
Tobias Rutz, MD

Medical doctor
University Hospital and University of Lausanne
Lausanne, Vaud, Switzerland

Background: Flow quantification by cardiac magnetic resonance (CMR) is essential for diagnosis-making and follow-up in congenital heart disease (CHD). Standard 2D phase contrast (2DPC) sequences require, however, precise image plane prescription resulting in long scan times.¹ Accelerated free-breathing 3D whole heart flow sequences promise a faster image acquisition, improved ease-of-use, and retrospective flow measurements in virtually all vessels. This study therefore compares 2DPC to accelerated 4D flow with prospective respiratory navigation² and free-running radial fully self-gated respiratory and cardiac motion-resolved 5D flow.^3,4

Methods: Patients with CHD were scanned on a 1.5T scanner. 2DPC was performed in the ascending, descending aorta (AA, DA), main, right and left pulmonary artery (MPA, RPA, LPA) and superior vena cava (SVC). By a prototype whole-heart free-running 3D radial PC CMR sequence end-expiratory 5D flow images were obtained.^3,4 Finally, 4D flow data were collected.² 3D vessel segmentation was performed for 5D and 4D flow datasets. Net flow volumes were compared between 2DPC, 4D and 5D flow Peak velocities determined by 2DPC, 4D and 5D flow were compared to those obtained by transthoracic echocardiography (TTE).

Results: 59 CHD patients (age 28±13y, 42% women, aortopathy 6, arterial switch transposition of great arteries (TGA) 3, atrial switch TGA 5, bicuspid aortic valve 4, cyanotic heart disease 2, Ebstein 4, Fontan 4, Ross 10, right ventricular outflow tract pathology 18, shunt lesion 3) were included.

4D and 5D flow underestimated net flow volumes compared to 2DPC which was more pronounced for 4D flow, in smaller vessels and DA (table 1). Internal consistency between systemic and pulmonary outputs was highest for 4D flow, with 5D flow showing similar agreement but slightly wider confidence intervals, while 2DPC had the largest variability (Fig. 1). Peak velocities did not differ between TTE and 5D flow in AA and MPA but were underestimated by 2DPC and 4D flow (AA: TTE 120±46, 2DPC 108±36, 4D flow 107±36, 5D flow 115±40 cm/s, p< 0.03 TTE vs 2DPC and 4D flow, p=0.253 TTE vs 5D flow; MPA TTE 168±86, 2DPC 153±78, 4D flow 142±62, 5D flow 145±72 cm/s, p< 0.03 TTE vs 2DPC and 4D flow, p=0.071 TTE vs 5D flow). The differences between TTE and 2DPC, 4D and 5D flow velocities increased with higher TTE velocity (Fig. 2).

Conclusion: In this typical CHD cohort with a high prevalence of right and left-sided valvulopathies, 4D and 5D flow techniques provided flow measurements broadly comparable to 2DPC. While 4D and 5D flow tend to underestimate net flow volumes, they demonstrated a better internal consistency than 2DPC. 5D flow achieved the highest accuracy in peak velocity assessment when compared with TTE, highlighting its potential as a non-invasive tool for comprehensive hemodynamic evaluation. However, further technical improvement is needed to address current underestimation of net flow volumes, particularly in the DA, the latter likely due to susceptibility artefacts.

Table 1 Comparison of net volumes (ml), (mean and SD) between 2DPC vs. 4D and 5D flow

	2DPC	4D	5D	p
AA, ml	72.57 ±19.26*	61.62 ±16.37	68.56± 22.16	0.010
DA, ml	46.35 ±12.66^†	40.66 ±11.84	33.86 ±10.98	< 0.001
MPA, ml	75.29±26.98	65.88±17.12	68.36±23.28	0.094
RPA, ml	42.90±15.43^§	32.69±12.91	34.24±15.17	< 0.001
LPA, ml	34.32±13.69^#	26.28±9.97	26.99±11.53	< 0.001
SVC, ml	25.93±9.81^‡	20.24±7.57	18.63±7.19	< 0.001

P-values refer to analyses of variance (ANOVA) with Bonferroni post-hoc analyses for comparison of bias between the three sequences.

*p=0.008 2DPC vs. 4D

^†p= < 0.001 2DPC vs 5D, p=0.03 2DPC vs 4D, p=0.007 4D vs 5D

^§p < 0.001 2DPC vs 4D, p=0.005 2D vs 5D

^#p < 0.001 2DPC vs 4D, p=0.003 2DPC vs 5D

^‡p < 0.001 2DPC vs 4D, p< 0.001 2DPC vs 5D

Abbreviations: AA = ascending aorta, DA = descending aorta, MPA = main pulmonary artery, RPA = right pulmonary artery, LPA = left pulmonary artery, SVC = superior vena cavaFigure 1: Bland-Altman analyses for comparison of internal consistency (Patients w/o shunt or Fontan physiology), net volume. P-values refer to ANOVA with Tukey post-hoc analyses for comparison of bias between the three sequences. MPA vs AA: 2D vs 4D vs 5D: p=0.079; 2D vs 4D p=0.283; 2D vs 5D p= 0.785; 4D vs 5D p=0.064 RPA+LPA vs MPA: 2D vs 4D vs 5D, 2D vs 4D and 2D vs 5D: p= <0.001; 4D vs 5D: p=0.863 Abbreviations: see table 1
Figure 2: Correlation of bias (cm/s) vs velocity between TTE versus 2DPC, 4D and 5D flow CMR (all patients). Abbreviations: TTE = transthoracic echocardiography