Free-breathing non-contrast-enhanced flow-independent MR angiography using REACT: A prospective study for pediatric vessel assessment

Abstract

Purpose

To evaluate the non-contrast-enhanced relaxation-enhanced angiography without contrast (REACT) sequence for the assessment of extrathoracic vessels in pediatric patients compared to contrast-enhanced (CE), multiphasic magnetic resonance angiography (MRA).

Materials and Methods

In this prospective, single-center study, pediatric patients referred for clinically indicated contrast-enhanced MRI of various extrathoracic body regions underwent additional free-breathing REACT and multiphasic, free-breathing CE-MRA at 1.5 T (Philips Ingenia). REACT was acquired using Cartesian k-space order, except in the abdomen, where it was acquired using a radial stack of stars k-space sampling (REACT VANE). The acquisition time was recorded. Image quality (Likert scale 1–5, with 5 being the best) and vessel diameter were evaluated by two independent readers in four predefined vessels in each body region. Furthermore, a quantitative analysis of SNR and CNR was performed.

Results

30 patients (age: 12.3 ± 4 years) successfully completed REACT and CE-MRA. The acquisition time for REACT was 2:49 ± 1:03 min, while abdominal REACT VANE required 4:51 ± 0:52 min. The CE-MRA acquisition time was 3:49 ± 1:03 min. The median image quality ratings were good to excellent (Likert scale 4–5) for both readers. No significant difference in the image quality ratings was found (p = 0.12 – 0.58). Interobserver agreement of image quality ratings of the two readers was moderate to substantial (Cohen’s kappa REACT: 0.58, CE-MRA: 0.64). Vessel diameter measurements showed a strong correlation (r = 0.93) between REACT and CE-MRA with high intraclass correlation coefficients (REACT: 0.97, CE-MRA: 0.97). Quantitative analysis showed a higher venous SNR and higher arterial and venous CNR in REACT (p = 0.001–0.018).

Conclusion

Given the good and comparable image quality, REACT can be useful in vascular imaging in children under free-breathing, while potentially eliminating the need for contrast agent injection.

Key Points

• MR angiography is widely used in pediatric imaging for vessel assessment.

• Contrast-enhanced MRA has limitations due to the use of gadolinium-based contrast agents.

• REACT is a novel contrast-free MRA technique performed during free breathing.

• REACT provides image quality comparable to contrast-enhanced free-breathing MRA.

Citation Format

• Spogis J, Tsiflikas I, Katemann C et al. Free-breathing non-contrast-enhanced flow-independent MR angiography using REACT: A prospective study for pediatric vessel assessment. Rofo 2026; 10.1055/a-2781-8861

Zusammenfassung

Zweck

Ziel dieser Studie war die Evaluation der kontrastmittelfreien Relaxation-Enhanced Angiography without Contrast (REACT)-Sequenz zur Beurteilung extrathorakaler Gefäße bei pädiatrischen Patienten im Vergleich zur kontrastmittelbasierten (CE), multiphasischen Magnetresonanzangiografie (MRA).

Material und Methoden

In dieser prospektiven, monozentrischen Studie erhielten pädiatrische Patienten, die zur klinisch indizierten kontrastmittelverstärkten MRT verschiedener extrathorakaler Körperregionen überwiesen wurden, zusätzlich eine kontrastmittelfreie REACT sowie eine multiphasische CE-MRA unter freier Atmung an einem 1,5 T MRT (Philips Ingenia). Die REACT wurde mittels kartesischem k-Raum-Sampling akquiriert, außer im Abdomen, wo eine radiale Stack-of-Stars-Akquisition (REACT VANE) angewendet wurde. Die Akquisitionszeit wurde aufgezeichnet. Die Bildqualität (Likert-Skala 1–5, wobei 5 die beste Qualität darstellt) und der Gefäßdiameter wurden durch zwei unabhängige Untersucher an vier vordefinierten Gefäßen pro Körperregion bewertet. Darüber hinaus wurde eine quantitative Analyse von SNR und CNR durchgeführt.

Ergebnisse

30 Patienten (Alter: 12,3 ± 4 Jahre) erhielten sowohl eine REACT als auch CE-MRA. Die Akquisitionszeit für REACT betrug 2:49 ± 1:03 min, während die abdominale REACT VANE 4:51 ± 0:52 min erforderte. Die Akquisitionszeit für CE-MRA lag bei 3:49 ± 1:03 min. Die mediane Bildqualität wurde von beiden Untersuchern als gut bis exzellent bewertet (Likert-Skala 4–5) ohne signifikante Unterschiede zwischen den Sequenzen (p = 0,12–0,58). Die Interobserver-Übereinstimmung der Bildqualitätsbewertungen war moderat bis substanziell (Cohen’s kappa: REACT 0,58; CE-MRA: 0,64). Die Gefäßdiameter zeigten eine hohe Korrelation zwischen REACT und CE-MRA (r = 0,93) mit hohen Intraklassen-Korrelationskoeffizienten (REACT: 0,97; CE-MRA: 0,97). In der quantitativen Analyse zeigte die REACT höhere venöse SNR-Werte sowie höhere arterielle und venöse CNR-Werte im Vergleich zur CE-MRA (p= 0,001 – 0,018).

Schlussfolgerung

Angesichts der guten und vergleichbaren Bildqualität könnte die REACT-Sequenz eine nützliche Technik für die Gefäßbildgebung unter freier Atmung bei Kindern darstellen – mit dem Potenzial, auf die Gabe von Kontrastmitteln zu verzichten.

Kernaussagen

• Die MR-Angiografie ist eine etablierte Bildgebung zur Beurteilung der Gefäße bei pädiatrischen Patienten.

• Die kontrastmittelangehobene MRA ist durch den Einsatz gadoliniumhaltiger Kontrastmittel limitiert.

• REACT ist eine neuartige, kontrastmittelfreie MRA-Technik unter freier Atmung.

• REACT zeigt eine mit CE-MRA vergleichbare Bildqualität.

Keywords

vascular - MR angiography - MR imaging

Publication History

Received: 04 June 2025

Accepted after revision: 02 January 2026

Article published online:
30 January 2026

• References

• 1 Chung T. Magnetic resonance angiography of the body in pediatric patients: experience with a contrast-enhanced time-resolved technique. Pediatr Radiol 2005; 35: 3-10
• 2 Mathur M, Jones JR, Weinreb JC. Gadolinium Deposition and Nephrogenic Systemic Fibrosis: A Radiologist's Primer. Radiographics 2020; 40: 153-162
• 3 McDonald JS, McDonald RJ, Jentoft ME. et al. Intracranial Gadolinium Deposition Following Gadodiamide-Enhanced Magnetic Resonance Imaging in Pediatric Patients: A Case-Control Study. JAMA Pediatr 2017; 171: 705-707
• 4 McDonald RJ, Levine D, Weinreb J. et al. Gadolinium Retention: A Research Roadmap from the 2018 NIH/ACR/RSNA Workshop on Gadolinium Chelates. Radiology 2018; 289: 517-534
• 5 Chavhan GB, Babyn PS, John P. et al. Pediatric Body MR Angiography: Principles, Techniques, and Current Status in Body Imaging. AJR Am J Roentgenol 2015; 205: 173-184
• 6 Yoneyama M, Zhang S, Hu HH. et al. Free-breathing non-contrast-enhanced flow-independent MR angiography using magnetization-prepared 3D non-balanced dual-echo Dixon method: A feasibility study at 3 Tesla. Magn Reson Imaging 2019; 63: 137-146
• 7 Andia ME, Henningsson M, Hussain T. et al. Flow-independent 3D whole-heart vessel wall imaging using an interleaved T2-preparation acquisition. Magn Reson Med 2013; 69: 150-157
• 8 Eggers H, Brendel B, Duijndam A. et al. Dual-echo Dixon imaging with flexible choice of echo times. Magn Reson Med 2011; 65: 96-107
• 9 Pennig L, Wagner A, Weiss K. et al. Imaging of the pulmonary vasculature in congenital heart disease without gadolinium contrast: Intraindividual comparison of a novel Compressed SENSE accelerated 3D modified REACT with 4D contrast-enhanced magnetic resonance angiography. J Cardiovasc Magn Reson 2020; 22: 8
• 10 Pennig L, Wagner A, Weiss K. et al. Comparison of a novel Compressed SENSE accelerated 3D modified relaxation-enhanced angiography without contrast and triggering with CE-MRA in imaging of the thoracic aorta. Int J Cardiovasc Imaging 2021; 37: 315-329
• 11 Betz LH, Dillman JR, Towbin AJ. et al. Respiratory-Triggered Flow-Independent Noncontrast Non-ECG-Gated MRV (REACT) Versus CE-MRV for Central Venous Evaluation in Children and Young Adults: A Six-Reader Study. AJR Am J Roentgenol 2023; 221: 240-248
• 12 Isaak A, Luetkens JA, Faron A. et al. Free-breathing non-contrast flow-independent cardiovascular magnetic resonance angiography using cardiac gated, magnetization-prepared 3D Dixon method: assessment of thoracic vasculature in congenital heart disease. J Cardiovasc Magn Reson 2021; 23: 91
• 13 Isaak A, Mesropyan N, Hart C. et al. Non-contrast free-breathing 3D cardiovascular magnetic resonance angiography using REACT (relaxation-enhanced angiography without contrast) compared to contrast-enhanced steady-state magnetic resonance angiography in complex pediatric congenital heart disease at 3T. J Cardiovasc Magn Reson 2022; 24: 55
• 14 Hoyer UCI, Lennartz S, Abdullayev N. et al. Imaging of the extracranial internal carotid artery in acute ischemic stroke: assessment of stenosis, plaques, and image quality using relaxation-enhanced angiography without contrast and triggering (REACT). Quant Imaging Med Surg 2022; 12: 3640-3654
• 15 Janssen JP, Rose S, Kaya K. et al. Non-contrast-enhanced MR-angiography of Extracranial Arteries in Acute Ischemic Stroke at 1.5 Tesla Using Relaxation-Enhanced Angiography Without Contrast and Triggering (REACT). Clin Neuroradiol 2024;
• 16 Tan EJ, Zhang S, Tirukonda P. et al. REACT – A novel flow-independent non-gated non-contrast MR angiography technique using magnetization-prepared 3D non-balanced dual-echo dixon method: Preliminary clinical experience. Eur J Radiol Open 2020; 7: 100238
• 17 Dillman JR, Trout AT, Merrow AC. et al. Non-contrast three-dimensional gradient recalled echo Dixon-based magnetic resonance angiography/venography in children. Pediatr Radiol 2019; 49: 407-414
• 18 Spogis J, Katemann C, Zhang S. et al. Feasibility and Implementation of a 4D Free-Breathing Variable Density Stack-of-Stars Functional Magnetic Resonance Urography in Young Children Without Sedation. Invest Radiol 2024; 59: 271-277
• 19 Chandarana H, Feng L, Block TK. et al. Free-Breathing Contrast-Enhanced Multiphase MRI of the Liver Using a Combination of Compressed Sensing, Parallel Imaging, and Golden-Angle Radial Sampling. Investigative Radiology 2013; 48: 10-16
• 20 Endler CH-J, Kukuk GM, Peeters JM. et al. Dynamic Liver Magnetic Resonance Imaging During Free Breathing: A Feasibility Study With a Motion Compensated Variable Density Radial Acquisition and a Viewsharing High-Pass Filtering Reconstruction. Investigative Radiology 2022; 57: 470-477
• 21 Holm S. A Simple Sequentially Rejective Multiple Test Procedure. Scandinavian Journal of Statistics 1979; 6: 65-70
• 22 Forbes-Amrhein MM, Dillman JR, Trout AT. et al. Frequency and Severity of Acute Allergic-Like Reactions to Intravenously Administered Gadolinium-Based Contrast Media in Children. Invest Radiol 2018; 53: 313-318
• 23 Brown EG, Adkins ES, Mattei P. et al. Evaluation of Image-Defined Risk Factor (IDRF) Assessment in Patients With Intermediate-risk Neuroblastoma: A Report From the Children's Oncology Group Study ANBL0531. J Pediatr Surg 2024; 161896
• 24 Harder FN, Budjan J, Nickel MD. et al. Intraindividual Comparison of Compressed Sensing-Accelerated Cartesian and Radial Arterial Phase Imaging of the Liver in an Experimental Tumor Model. Investigative Radiology 2021; 56: 433-441
• 25 Yoon JH, Lee JM, Yu MH. et al. Evaluation of Transient Motion During Gadoxetic Acid–Enhanced Multiphasic Liver Magnetic Resonance Imaging Using Free-Breathing Golden-Angle Radial Sparse Parallel Magnetic Resonance Imaging. Investigative Radiology 2018; 53: 52-61
• 26 Janssen JP, Gertz RJ, Tristram J. et al. Accelerating non-contrast MR angiography of the thoracic aorta using compressed SENSE with deep learning reconstruction. Eur J Radiol 2025; 192: 112403
• 27 Erdem S, Jack A, Doctor P. et al. Feasibility of magnetization-transfer-contrast relaxation-enhanced angiography without contrast and triggering (REACT) imaging at 1.5 T combined with deep learning-based reconstruction for cardiovascular visualization. Quant Imaging Med Surg 2025; 15: 3222-3236