Minimizing Metallic Subcutaneous ICD Artifact Utilizing Ferumoxytol Contrast and Wideband Sequencing in an Adult Patient with Tetralogy of Fallot

Description of Clinical Presentation: A 35 year old female presented to establish care with our adult congenital heart disease (ACHD) clinic. Her anatomy included tetralogy of Fallot with right sided aortic arch s/p 5 mm central shunt from the ascending aorta to main pulmonary artery in infancy, followed by complete intracardiac repair with a transannular patch and PDA ligation at 1 year of age. She developed palpitations with Holter monitor showing premature ventricular contractions (PVCs) and non-sustained ventricular tachycardia (NSVT) at 30 years of age. She subsequently underwent RVOT PVC ablation. 1 month later, she underwent Sapien transcatheter pulmonary valve replacement (PVR) for severe pulmonary insufficiency. 4 months after transcatheter PVR, she underwent subcutaneous ICD placement for primary prevention. Following these interventions, she was asymptomatic with only mild orthostatic lightheadedness. At 35 years of age, she underwent repeat routine screening cardiac MRI to assess her anatomy, ventricular volumes, and ventricular function. Given the presence of her ICD, the greatest challenge was ventricular volume assessment due to ICD artifact.

Diagnostic Techniques and Their Most Important Findings: Cardiac MR was performed utilizing an 8 channel body coil on a 1.5 T GE Signa scanner. Three plane localizer, axial stack, SSFP single shot axial stack, as well as SSFP and FGRE cine sequences including: 2 chamber left, 4 chamber, ventricular short-axis stack, left ventricular outflow tract, and right ventricular outflow tract sequences were performed. FGRE cine was performed with wideband sequencing at 125 Hz. 190 mg of ferumoxytol (3.06 mg/kg) (8 mg/mL dilution, 23.75 mL total) was administered as a slow infusion over 15 minutes to help minimize artifact. . Phase contrast was performed at the level of the aortic valve, pulmonary valve. MRA information was acquired afterwards, and MIP, MPR, and 3D surface rendering, post-processing techniques were performed later.

Learning Points from this Case: ICD leads commonly cause significant artifact making interpretation of ventricular volume and function difficult. FGRE cine with wideband sequencing at 125 Hz with ferumoxytol contrast improved visualization of the ventricular wall by reducing subcutaneous ICD lead and generator artifact allowing more precise contours and visualization of the wall motion (Figures 1 and 2). Additionally, this technique minimized artifact from the Sapien valve in the RVOT (Figure 3). We would recommend ferumoxytol early in the study prior to short axis and 4 chamber cine imaging. In ACHD patients where cross sectional imaging remain essential criteria for determining intervention to optimize care in these patients, accurate measurements of ventricular size and function are imperative as they can alter the clinical course. Our experiences with this case illustrate how ferumoxytol contrast in addition to wideband sequencing may be a novel and effective methodology to reduce artifact due to ICD/pacemaker leads and generator’s in the growing adult congenital population.

Figure 1. Coronal single shot SSFP showing significant metallic artifact from the subcutaneous ICD generator.
Figure 2. (A) 4 chamber cine FSPGR without contrast and (B) with ferumoxytol contrast, demonstrating improved image quality with sharper ventricular borders and significant reduction in artifact. Right ventricular outflow tract (RVOT) cine FSPGR without (C) and with ferumoxytol contrast (D) demonstrating improved ventricular border and RVOT clarity despite transcatheter Sapien valve in the RVOT.
Figure 3. Short axis cine FSPGR without contrast (A) and with ferumoxytol contrast (B), demonstrating improved image quality and reduction in metallic artifact distortion from S-ICD and transcatheter Sapien pulmonary valve.