Department of Surgical and Radiological Sciences, University of California Davis, School of Veterinary Medicine, Davis, California, USA.
Diagnostic Cardiovascular Imaging Research Laboratory, Department of Radiology, David Geffen School of Medicine, University of California Los Angeles, School of Medicine, Davis, California, USA.
Vet Radiol Ultrasound. 2021 Jul;62(4):463-470. doi: 10.1111/vru.12963. Epub 2021 Feb 26.
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.
计算机断层血管造影术（CTA）目前是犬肝脏血管异常解剖特征的金标准成像方式；而常规的钆增强磁共振血管造影术则较少应用。然而，这两种成像方式都受到血管内造影剂短暂的首过峰值的限制，这就需要精确的图像采集时间。一种长效的纯血管内磁共振成像（MRI）造影剂，ferumoxytol，通过确保所有目标血管都具有诊断性造影剂浓度，有可能降低磁共振血管造影（MRA）方案规划的复杂性。本前瞻性、初步、方法比较研究的目的是开发一种使用肝血管异常犬的 ferumoxytol 的优化 MRA 方案，进行剂量递增试验，比较 ferumoxytol 四种剂量方案的图像质量，并比较基于 CTA 的金标准的血管解剖结构描绘的准确性。本研究纳入了 6 只（10.7-36.1kg）具有门体分流（4 只肝内左部分流和 2 只肝内右部分流）的犬。进行了一项剂量递增试验，以比较 ferumoxytol 的四个递增剂量水平（1、2、3 和 4mg/kg）的图像质量，并比较血管解剖结构检测的准确性与 CTA。4mg/kg 的 ferumoxytol 对比增强磁共振血管造影（CE-MRA）与 CTA 相比，提供了相似的正常和异常血管的显影，空间分辨率仅略有下降。研究结果表明，ferumoxytol 有望在具有门体分流的犬中进行全面的、单次屏气的腹部所有血管的 CE-MRA。本研究提供的背景信息可用于支持其他未来应用的开发，如颅内和心脏 MRA、实时成像、流量量化，以及潜在的镇静 MRI 成像。
