Ferumoxytol‐enhanced magnetic resonance angiography provides comparable vascular conspicuity to CT angiography in dogs with intrahepatic portosystemic shunts

Abstract

Computed tomography angiography (CTA) is currently the gold standard imaging modality for anatomically characterizing canine hepatic vascular anomalies; with conventional, gadolinium‐enhanced MR angiography being less frequently utilized. However, both imaging modalities are limited by a brief, first pass peak of contrast medium in the vasculature that necessitates precisely timed image acquisition. A long‐acting purely intravascular magnetic resonance imaging (MRI) contrast agent, ferumoxytol, offers the potential to reduce complexity of magnetic resonance angiography (MRA) protocol planning by ensuring diagnostic contrast medium concentration in all the vessels that are targeted for imaging. Aims of this prospective, pilot, methods comparison study were to develop an optimized MRA protocol using ferumoxytol in dogs with hepatic vascular anomalies, perform a dose escalation trial to compare image quality with four‐dose regimens of ferumoxytol, and compare accuracy of vascular anatomic depiction based on the gold standard of CTA. Six dogs (10.7–36.1 kg) with portosystemic shunts (four intrahepatic left divisional shunts and two intrahepatic right divisional shunts) were recruited for inclusion in the study. A dose‐escalation trial was performed to compare image quality at four incremental dose levels of ferumoxytol (1, 2, 3, and 4 mg/kg) and to compare the accuracy of vascular anatomic detection to CTA. Ferumoxytol contrast‐enhanced MRA (CE‐MRA) at 4 mg/kg provided similar conspicuity of normal and abnormal vasculature compared to CTA with a minimal decrease in spatial resolution. Findings indicated that ferumoxytol holds promise for comprehensive, single breath hold CE‐MRA of all abdominal vessels in dogs with portosystemic shunts. Background information provided in this study can be used to support development of other future applications such as intracranial and cardiac MRA, real‐time imaging, flow quantification, and potentially sedated MRI imaging.

Unveiling the next generation of MRI contrast agents: current insights and perspectives on ferumoxytol-enhanced MRI

“…Its significant particle size ensures long retention in the blood pool, preventing substantial leakages from the vascular bed, and it can bypass kidney clearance [ 15 ]. Conventional CAs, GBCAs, can permeate from the vascular bed into the extracellular fluid swiftly, resulting in a brief intravascular retention time ranging between 2 and 11 minutes [ 16 ]. The abbreviated intravascular half-life presents challenges for the practicing radiologist in choosing the right imaging time frame, especially when imaging the venous system.…”

Enlargement of the hepatic artery is present in dogs with a congenital extrahepatic portosystemic shunt and is independent of shunt insertion into the systemic circulation

“…Computed tomographic angiography is widely regarded as the gold standard for noninvasive diagnosis of congenital portosystemic shunts, superseding intraoperative mesenteric portovenography and ultrasonographic assessment 3,8 . Magnetic resonance angiography is also reported for diagnosis of portosystemic shunts but this is not in routine clinical use 9–12 . More recent literature has focused on the standardization of naming conventions with regard to portosystemic vascular anomalies, and there is ongoing research into the pathophysiology underlying the development of these anomalies 3,4 .…”

“…3,8 Magnetic resonance angiography is also reported for diagnosis of portosystemic shunts but this is not in routine clinical use. [9][10][11][12] More recent literature has focused on the standardization of naming conventions with regard to portosystemic vascular anomalies, and there is ongoing research into the pathophysiology underlying the development of these anomalies. 3,4 In a previous review of the anatomical conformations of extrahepatic portosystemic shunts (EHPSS), 94% of extrahepatic shunts in the dog were comprised of left gastrophrenic, left gastroazygos, splenocaval, or right gastrocaval shunts.…”

Lymphotropic nanoparticle magnetic resonance imaging for diagnosing metastatic lymph nodes in dogs with malignant head and neck tumours

“…Until recently, the utility of iron nanoparticles has been limited due to a lack of a commercial product. As a result, there have been only a few veterinary related articles looking at the use of iron nanoparticles as a negative contrast agent, primarily as an agent for imaging of the reticuloendothelial system and kidneys 24–26 . Recently a product called ferumoxytol (Feraheme) received FDA approval.…”

“…As a result, there have been only a few veterinary related articles looking at the use of iron nanoparticles as a negative contrast agent, primarily as an agent for imaging of the reticuloendothelial system and kidneys. [24][25][26] Recently a product called ferumoxytol (Feraheme) received FDA approval. Feraheme is indicated for the treatment of iron deficiency anaemia (IDA) in adult patients who have intolerance to oral iron or have had unsatisfactory response to oral iron or who have chronic kidney disease (CKD) as an iron supplement for people with anaemia.…”