Feasibility of ferumoxytol‐enhanced neonatal and young infant cardiac MRI without general anesthesia

Abstract

Purpose To assess the feasibility of ferumoxytol-enhanced anesthesia-free cardiac MRI in neonates and young infants for complex congenital heart disease (CHD). Methods With IRB-approval, 21 consecutive neonates and young infants (1 day – 11 weeks old, median age of 3 days) who underwent a rapid two-sequence (MRA and 4D flow) MRI protocol with intravenous ferumoxytol without sedation (n = 17) or light sedation (n = 4) at 3T (except one case at 1.5T) between June 2014 and February 2016 were retrospectively identified. Medical records were reviewed for indication, any complications, if further diagnostic imaging was performed after MRI, and surgical findings. Two radiologists scored the images in two sessions on a five-point scale for overall image quality and delineation of various anatomical structures. Confidence interval of proportions for likelihood of requiring additional diagnostic imaging after MRI was determined. For the possibility of reducing the protocol to a single rapid sequence, Wilcoxon-rank sum test was used to assess whether 4D flow and MRA significantly differed in anatomical delineation. Results One of 21 patients (4.8%, 80% confidence interval 0–11%) required additional imaging, a CTA to assess lung parenchyma and peripheral pulmonary arteries. Only 1 out of 13 patients (7.7%) with operative confirmation had a minor discrepancy between radiology and operative reports (80% confidence interval 0–17%). 4D flow was significantly superior to MRA (p<0.05) for the evaluation of systemic arteries, valves, ventricular trabeculae, and overall quality. Using Cohen’s kappa coefficient, there was good interobserver agreement for the evaluation of systemic arteries by 4D flow (κ = 0.782), and systemic veins and pulmonary arteries by MRA (κ > 0.6). Overall 4D flow measurements (mean κ = 0.64–0.74) had better internal agreement compared to MRA (mean κ = 0.30–0.64). Conclusion Ferumoxytol-enhanced cardiac MRI, without anesthesia, is feasible for the evaluation of complex CHD in neonates and young infants, with a low likelihood of need for additional diagnostic studies. The decreased risk by avoiding anesthesia must be balanced against the potential for adverse reactions with ferumoxytol.

Free‐breathing pediatric chest MRI: Performance of self‐navigated golden‐angle ordered conical ultrashort echo time acquisition

“…Thus, ferumoxytol likely at least improved PA delineation in our cohort. With its long blood pool residence time (circulating half‐life 14–15 hours) and long relaxivity, ferumoxytol permits longer scan times, while preserving vascular signal . As such, contrast enhancement remained robust despite the average 5‐minute length of our UTE acquisition.…”

“…This ultrasmall superparamagnetic iron oxide medication was developed to treat anemia but has shown promise as a contrast agent, although is not approved by the US Food and Drug Administration for such use. Ferumoxytol had been administered per established, albeit off‐label, institutional protocol in patients undergoing 4D flow for cardiovascular indications and is not required for our conical UTE acquisition . However, we suspect it may further enhance the signal‐to‐noise ratio (SNR) and overall image quality.…”

“…Because of its favorable signal properties, ferumoxytol may also facilitate free‐breathing acquisition (using multiple signal averages) and lesser anesthesia requirements . Moreover, unlike gadolinium‐based agents, ferumoxytol does not precipitate nephrogenic systemic fibrosis (NSF) and can be administered to patients with renal failure .…”

“…All scans were enhanced with ferumoxytol (Feraheme, AMAG Pharmaceuticals, Waltham, MA), injected intravenously before imaging as a slow infusion over 5–15 minutes using a diluted volume in normal saline (3 mg/kg with 1:5 dilution or 0.1 mL/kg) . Vital signs were monitored for 30 minutes after ferumoxytol administration in the radiology department or an inpatient unit under the supervision of an advanced cardiac life support (ACLS) or pediatric advanced life support (PALS)‐certified physician.…”

A comprehensive literatures update of clinical researches of superparamagnetic resonance iron oxide nanoparticles for magnetic resonance imaging

“…As a blood pool contrast agent, ferumoxytol provides a much longer temporal window for data acquisition than extracellular agents, allowing imaging to be performed repeatedly beginning as early as the arterial phase and continuing into later phases. This could be of use in imaging of smaller arteries, where extended imaging periods could be leveraged to obtain high-resolution imaging with high signal-to-noise ratio, in applications where venous enhancement can be tolerated (43)(44)(45)(46)(47)(48)(49) (Figure 4). Compared to those with kidney transplants, many patients with severe renal insufficiency are dependent on hemodialysis via a peripheral arteriovenous fistula.…”