Blood pool MRI contrast agent use in pediatric patients for vascular imaging

Learning Objectives We review the imaging technique, discuss advantages/disadvantages, and provide examples of cases where blood pool (BP) contrast MRI may provide new options for pediatric disease detection and monitoring. Background BP contrast agents are a relatively new and promising option in the MR assessment of disease, but currently the experience and published/recognized indications for the use of these agents are limited in the pediatric population. Gadofoveset trisodium (Ablavar) binds reversibly to albumin causing a prolonged BP residence and increasing T1 shortening. Although aortoiliac disease in adults is currently the only FDA-approved indication, other potential applications for BP agents are under investigation. Compared to traditional MRA, BP agents allow for both arterial and venous phase imaging, as well as delayed venous imaging independent of bolus timing. This enables repeat imaging without re-injection, covering a larger anatomic area, e.g. head to foot, if necessary. Clinical Findings/Procedure Details We retrospectively reviewed all MRI studies performed at our institution in children using Ablavar over the past 12 months. After dynamic arterial and early venous phase imaging, delayed venous imaging was performed with high resolution SPGR or MRA imaging with combined respiratory and ECG gating, reconstructed into orthogonal planes. Patient demographic, clinical history, exam indication, MRI technique, and imaging findings as they pertained to dynamic MRA and BP imaging were recorded. The most common indication for utilization of BP contrast agent in our population was for pediatric venography (n=9/22). Other indications included evaluation of liver vessel patency/anatomy (n=7), vasculitis (n=2), acute GI bleeding (n=2), vascular supply of an intra-abdominal mass (n=1), and for refractory hypertension (n=1). Conclusion and/or Teaching Points Blood pool MRI contrast agents can be extremely useful in pediatric imaging for certain indications, particularly for high-resolution venous imaging covering a large area. Optimization of technique and understanding BP imaging benefits/limitations are fundamental to performing an exam with excellent image quality that provides a high degree of diagnostic confidence.