High-dose Gd-DTPA vs. Bis-Gd-mesoporphyrin for monitoring laser-induced tissue necrosis

Purpose: To compare Bis-Gd-mesoporphyrin (Bis-Gd-MP), a contrast agent with a reported. high affinity to necrotic tissue, with high-dose gadopentate dimeglumin (Gd-DTPA) for defining laser-induced muscle and liver necrosis by contrast-enhanced (CE) MRI. Materials and Methods: Laser-induced interstitial thermotherapy (LITT) was performed. in the muscle and liver tissue of New Zealand White rabbits (1500 J and 2100 J; n = 80 lesions). The animals were randomly assigned to a group that received 0.3 mmol/kg bw Gd-DTPA or a group that received 0.05 mmol/kg bw Bis-Gd-MP. Following contrast injection, dynamic MRI was performed on muscle lesions with a T1-weighted, two-dimensional, fast low-angle shot (FLASH) sequence. The liver and muscle lesions were then repeatedly imaged for six hours after contrast injection using a T1-weighted spin-echo (SE) sequence. Central and peripheral lesion enhancement was determined and correlated with gross pathology, and microscopy findings. Results: Both contrast agents allowed precise determination of lesion diameters with an average accuracy of 6.8% +/- 1.3%. Rim enhancement during dynamic MRI was superior for Gd-DTPA (P < 0.001) and revealed slightly higher lesion diameters compared to the results of follow-up MR studies. A persistent enhancement of necrotic liver and muscle tissue was observed for both contrast agents throughout the observation period, suggesting that simple diffusion-type processes may underlie the supposed affinity of Bis-Gd-MP for tissue necrosis. Conclusion:, Bis-Gd-MP and Gd-DTPA are equally well suited for postinterventional lesion assessment in LITT. (c) 2005 Wiley-Liss, Inc.