Molecular magnetic resonance imaging of atrial clots in a swine model.

BACKGROUND: The detection and differentiation of intracardiac masses is still challenging and may include neoplasms and thrombi. The aim of this study was the investigation of a targeted, fibrin-specific contrast agent (EP-2104R) for molecular targeted magnetic resonance imaging (MRI) of left atrial clots. METHODS AND RESULTS: Chronic human thrombi were surgically implanted in the left atrial appendage of 5 swine. Molecular MRI was performed with a navigator-gated, free-breathing, cardiac-triggered 3D inversion-recovery, black-blood, gradient-echo sequence before and after systemic administration of 4 micromol/kg EP-2104R. MR images were analyzed by 2 investigators, and the contrast-to-noise ratio was calculated. Location of clots was confirmed by autopsy, and the gadolinium concentration in the clots was assessed. Before contrast agent administration, thrombi were not visible on black-blood MR images. After contrast administration, all atrial clots (n=5) were selectively visualized as white spots with a high contrast-to-noise ratio (clot/blood, 29.7+/-8.0). The gadolinium concentration in the clots averaged 74+/-45 micromol/L. CONCLUSIONS: The fibrin-specific MR contrast agent EP-2104R allows for selective and high-contrast visualization of left atrial clots by means of molecular targeted MRI.

Standard-protocol moving-table magnetic resonance angiography for planning of interventional procedures in patients with peripheral vascular occlusive disease.

PURPOSE: This study aimed to evaluate the usefulness of magnetic resonance angiography (MRA) for the planning of interventional procedures in the lower extremity vascular territory. MATERIALS AND METHODS: Patients with peripheral vascular occlusive disease (PVOD) underwent MRA for planning of percutaneous interventional treatment. Digital subtraction angiography was performed in patients scheduled for interventional treatment and served as the standard of reference. RESULTS: In 148 out of 150 cases (98.7%), the necessity for an intervention was recognized correctly; 137 out of 150 interventions (91.3%) were correctly planned based on MRA results. CONCLUSION: Contrast-enhanced MRA of the lower extremities is a safe, noninvasive tool for preinterventional assessment of patients with PVOD. It allows exact planning of endovascular interventions.