Gadobenate Dimeglumine-enhanced MR of VX2 Carcinoma in Rabbit Liver: Usefulness of the Delayed Phase Imaging and Optimal Pulse Sequence

Cho, Seung Il; Lee, Jeong Min; Kim, Young Kon; Kim, Chong Soo

Abstract

PURPOSE: To assess the diagnostic value of delayed imaging using gadobenate dimeglumine(MultiHance) and to determine the optimal pulse sequence for the detection of VX2 carcinoma lesions in the rabbit.
MATERIALS AND METHODS
Twelve VX2 carcinomas implanted in the livers of eleven New Zealand rabbits were studied. All patients underwent an MR protocol consisting of precontrast T2-and T1-weighted sequences, followed by repetition of the T1-weighted sequence at 0 to 30 (arterial phase), 31-60 (portal phase), and 40 minutes (delayed phase) after the intravenous administration of 0.1 mmol/kg of gadobenate dimeglumine. The signal-to-noise ratio (SNR) of the liver and VX2 tumor, and the lesion-to-liver contrast-to-noise ratio (CNR) of precontrast and postcontrast MR images were quantitativlely analyzed, and two experienced radiologists evaluated image quality in terms of lesion conspicuity, artifact, mass delineation, and vascular anatomy.
RESULTS
Liver SNR was significantly higher at delayed imaging than at precontrast, arterial, and portal imaging (p<0.05), while lesion SNR was significantly higher at delayed imaging than at precontrast imaging (p<0.05). Lesion CNR was higher at delayed imaging than at precontrast and portal phase imaging (p<0.05), but there was no difference between arterial and delayed imaging. The latter provided better mass delineation than precontrast, arterial and portal phase imaging (p<0.05). While in terms of lesion conspicuity and vascular anatomy, the delayed phase was better than the arterial phase (p<0.05) but similar to the precontrast and portal phase. During the delayed phase, the gradient-echo sequence showed better results than the spin-echo in terms of liver SNR, and lesion SNR and CNR (p<0.05).
CONCLUSION
Because it provides better lesion conspicuity and mass delineation by improving liver SNR and lesion-to-liver CNR, the addition of the delayed phase to a dynamic MRI sequence after gadobenate dimeglumine administration facilitates lesion detection. For delayed-phase imaging, the gradient-echo sequence is superior to the spin-echo sequence.