CMR-Flow

1343621 - Respiratory Resolved flow in Congenital Heart Disease: A 5D flow MRI Study

Thursday, January 26, 2023

5:40 PM – 5:50 PM

Location: Silver Pearl 2

Presenting Author(s)

Elizabeth Weiss, BSc

MD/PhD Candidate
Northwestern University
Chicago, Illinois, United States

Primary Author(s)

Elizabeth Weiss, BSc

MD/PhD Candidate
Northwestern University
Chicago, Illinois, United States

Co-Author(s)

CR

Cynthia K. Rigsby, MD

Chair
Ann & Robert H. Lurie Children's Hospital of Chicago
Chicago, Illinois, United States
Joshua D. Robinson, MD

Pediatric Cardiologist
Ann & Robert H. Lurie Children's Hospital of Chicago
Chicago, Illinois, United States
JB

Justin Baraboo, BSc

PhD Candidate
Northwestern University
Chicago, Illinois, United States
Liliana Ma, MD, PhD

Resident
Ascension RMC and Northwestern University
Mariana Falcao, MSc

PhD Candidate
Lausanne University Hospital and University of Lausanne
Lausanne, Vaud, Switzerland
CR

Christopher W. Roy, PhD

Post Doc
Lausanne University Hospital and University of Lausanne (UNIL)
Prilly, Vaud, Switzerland
Matthias Stuber, PhD

Professor
University Hospital (CHUV) and University of Lausanne (UNIL)
Lausanne, Switzerland
Mark Markl, PhD

Professor
Northwestern University

Disclosure(s):

Joshua D. Robinson, MD: No relevant disclosure to display

Background: Respiration has been shown to drive hemodynamic changes in healthy individuals¹ and those with congenital heart disease (CHD).²Yet, conventional flow methods are often limited to acquisition during a single respiration state (breath-hold, navigator-gated). 5D flow MRI³ is a new free-running, self-gated technique that enables 3D velocity quantification over both cardiac and respiratory cycles. However, the original respiratory gating method is amplitude-based and does not reflect physiologic respiratory phases. Here, we develop a novel physiology-driven respiratory gating method to assess the impact of respiration in CHD patients using 5D flow MRI.

Methods: 22 patients with CHD (17±11yrs, M/F: 12/10) undergoing a clinically indicated CMR with ferumoxytol were consented for an 8.5-minute 5D flow add-on. The cohort was divided into 3 anatomical subgroups: single ventricle disease (SVD, n=5), pulmonary artery disease (PA, n=7), shunt (n=5). Superior-inferior readouts were used to extract cardiac and respiratory signals for retrospective gating. The novel respiratory gating method sorted readouts on a per-breath basis, assigning the max and min 25% of signal to end-expiration and end-inspiration respectively. The remaining points were assigned to expiration and inspiration based on signal slope. Net flow was measured in the ascending aorta (Ao), main pulmonary artery (MPA), left and right pulmonary arteries (LPA & RPA), and inferior and superior vena cava (IVC & SVC). The range of net flow over respiration was normalized to the mean over respiration. Median flow curves were normalized to end-expiration.

Results: Overall, the caval veins had larger respiratory driven flow changes than the pulmonary arteries and aorta (40% vs 17% & 12%, p< 0.001). The pulmonary arteries had larger flow changes across the 4 RS than the Ao (17% vs 12%, p< 0.01; Fig2b). In sub-group analysis, Ao of SVD patients had less respiratory driven flow than the pulmonary arteries and caval veins (9% vs 34% & 51%, p< 0.01). In shunt patients, respiration had a larger impact on the caval veins than the pulmonary arteries and the Ao (28% vs 13% & 11%, p< 0.01, Fig2a). Additionally, in the IVC of SVD and shunt patients (Fig3d), inspiration had a positive percent change in flow while expiration had a negative percent change.

Conclusion: We demonstrated a novel respiratory gating method based on physiologic respiratory phases and detected respiration driven flow changes in CHD patients. We found that respiration has more impact on pulmonary arteries and caval veins than the aorta. Additionally, we found that anatomy plays a role. In shunt patients, pulmonary arteries did not have more respiratory driven flow changes than the Ao, but in SVD patients, where the pulmonary arteries are passively filled, there was a large, significant difference. In many cases, the change in flow during inspiration and expiration were opposite, suggesting that the prior method, which grouped data from these phases, may be inadequate.