OBJECTIVE: To compare P792 (gadomelitol, a rapid clearance blood pool MR contrast agent) with gadolinium-tetraazacyclododecanetetraacetic acid (Gd-DOTA), a standard extracellular agent, for their suitability to diagnose a pulmonary embolism (PE) during a first-pass perfusion MRI and 3D contrast-enhanced (CE) MR angiography (MRA). MATERIALS AND METHODS: A perfusion MRI or CE-MRA was performed in a rabbit PE model following the intravenous injection of a single dose of contrast agent. The time course of the pulmonary vascular and parenchymal enhancement was assessed by measuring the signal in the aorta, pulmonary artery, and lung parenchyma as a function of time to determine whether there is a significant difference between the techniques. CE-MRA studies were evaluated by their ability to depict the pulmonary vasculature and following defects between 3 seconds and 15 minutes after a triple dose intravenous injection of the contrast agents. RESULTS: The P792 and Gd-DOTA were equivalent in their ability to demonstrate PE as perfusion defects on first pass imaging. The signal from P792 was significantly higher in vasculature than that from Gd-DOTA between the first and the tenth minutes after injection. The results suggest that a CE-MRA PE could be reliably diagnosed up to 15 minutes after injection. CONCLUSION: P792 is superior to Gd-DOTA for the MR diagnosis of PE.
Animals ; Contrast Media/administration & dosage ; Heterocyclic Compounds/administration & dosage/*diagnostic use ; Imaging, Three-Dimensional ; Injections, Intravenous ; Magnetic Resonance Angiography/*methods ; Magnetic Resonance Imaging/*methods ; Organometallic Compounds/administration & dosage/*diagnostic use ; Pulmonary Embolism/*diagnosis ; Rabbits