Shih-Hsien Chen | PubMed Health

PubMed2004

Evaluation of [Gd(Bz-TTDA)]2- as a potential contrast agent in MR imaging of the hepatobiliary system: an animal study.

PURPOSE: To evaluate the potential of a new lipophilic paramagnetic complex [Gd(Bz-TTDA)]2- [(4s)-4-benzyl-3,6,10-tri(carboxymethyl)-3,6,10-triazadodecandioic acid]2- designed for use as a hepatobiliary MR contrast agent. MATERIALS AND METHODS: MR imaging studies for normal and hepatocellular carcinoma (HCC) rat models were performed using a 1.5-T scanner. Sequential multislice T1-weighted turbo field echo (TFE) (TR/TE/flip angle: 15 msec/6.1 msec/25 degrees) coronal images of normal rats were obtained before and after intravenous injections of 0.1 mmol/kg [Gd(Bz-TTDA)]2- in study groups (N = 12) or 0.1 mmol/kg gadopentate dimeglumine (Gd-DTPA)2- in control groups (N = 12). Similar protocols of MR imaging with additional T2-weighted images were used for the rats with implanted HCC in both study and control groups (N = 12, in each group). MR images were analyzed to evaluate the time-enhancement change (% increase of signal-to-noise ratio [SI/N]) in normal liver, renal cortex, renal medulla, and tumors. The liver-lesion contrast-to-noise ratios (CNR) were also evaluated in study and control groups. The rats were killed immediately after the last MR scan to undergo autopsy and histopathologic observation. The acute toxicity test (medial lethal dose, LD50) in mice was also done. RESULTS: The liver enhancement in normal rats reached a plateau 5-50 minutes after injection of [Gd(Bz-TTDA)]2-, maintained for three hours, then gradually declined. Intensity of enhancement in liver, renal cortex, and medulla after injection of [Gd(Bz-TTDA)]2- was significantly higher than with Gd-DTPA. The efficacy of tumor characterization with injection of [Gd(Bz-TTDA)]2- was similar to that of Gd-DTPA at the early dynamic phase of the contrast study. However, the liver-lesion CNRs were significantly higher in the study group in the later phase, when tumor enhancement decreased and liver enhancement persisted. The dose of LD50 in acute toxicity test of [Gd(Bz-TTDA)]2- in mice was 7.5 mmol/kg. CONCLUSION: The preliminary results in this animal study indicated that [Gd(Bz-TTDA)]2- has the potential of becoming a reliable liver MR contrast agent.

Animals↗

PubMedDate not supplied

Ionic versus nonionic paramagnetic contrast media in differentiating between postoperative scar and recurrent disk.

BACKGROUND AND PURPOSE: In theory, ionic solutes diffuse more slowly in cartilage than do nonionic solutes. We tested the hypothesis that the contrast ratio between scar and recurrent disk fragment on MR images is greater after IV administration of an ionic rather than a nonionic contrast medium when a clinical dose is used. METHODS: Twenty patients who had recurrent lumbar disk herniation were enrolled in this study. The enhancement of epidural scar and recurrent disk fragment was measured at 5, 25, 40, and 50 min after IV injection of ionic and nonionic contrast media (0.1 mmol/kg) RESULTS: The enhancement was consistently and significantly higher for scar than for recurrent disk fragment, although the contrast ratio between scar and recurrent disk fragment decreased between 5 and 50 min after the administration of each contrast medium. No significant difference was shown between ionic and nonionic contrast media in the enhancement of recurrent disk fragment at 5, 25, 40, and 50 min after injection. The contrast ratio between scar and recurrent disk fragment was not a significant difference at 5, 25, and 40 min after administration of both contrast media. At 50 min, the contrast ratio between scar and recurrent disk fragment was 1.32 +/- 0.41 with ionic contrast medium and 1.20 +/- 0.56 with nonionic contrast medium. The difference was significant. CONCLUSION: The contrast ratio between scar and recurrent disk fragment is affected by the timing of the imaging. Images obtained immediately after the injection of each contrast medium showed a greater contrast ratio than did delayed images. In addition, with the ionic medium, this difference was greater than with nonionic medium at 5, 25, 40, and 50 min after injection and that difference reached statistical significance at 50 min.

Cicatrix↗