CT pulmonary angiography with a macromolecular contrast medium - A comparative study versus iobitridol in rabbits

RATIONALE AND OBJECTIVES. To compare the pharmacokinetics of a new macromol ecular iodinated contrast medium, prototype P743, with a standard contrast agent (iobitridol) for spiral computed tomography pulmonary angiography in rabbits. METHODS. Manual injection was first used to test the performance of P743 ev en in cases of nonoptimal bolus timing. Then a protocol was designed to com pare vessel enhancement in both first-pass and delayed scans for the two co ntrast agents with the help of a power injector. RESULTS. With manual fast injection, the first pass of iobitridol was obser ved only on proximal scans. Conversely, opacification of vessels was mainta ined during three spiral scans with P743 under the same injection condition s. When optimal bolus timing was performed, higher vessel enhancement was o bserved during bolus first pass with iobitridol (iodine dosage 250 mg I/kg) compared with P743 (150 mg I/kg). However, during the postbolus phase, the decrease in attenuation values was markedly faster with iobitridol than wi th P743. CONCLUSIONS. This study confirmed that P743 remains more intravascular than iobitridol, which may have clinical implications for the diagnosis of pulm onary embolism, for example.