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


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.


CONCLUSIONS
Bis-Gd-MP and Gd-DTPA are equally well suited for postinterventional lesion assessment in LITT.
Bremer
Christoph
C
Department of Clinical Radiology, University of Muenster, Muenster, Germany. bremerc@uni-muenster.de
Bankert
Joerg
J
Filler
Timm
T
Ebert
Wolfgang
W
Tombach
Bernd
B
Reimer
Peter
P
D000818:Animals; D003287:Contrast Media; D019786:Gadolinium DTPA; D006979:Hyperthermia, Induced / Q000009:adverse effects / Q000379:methods*; D007834:Lasers; D008099:Liver / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008652:Mesoporphyrins; D008665:Metalloporphyrins; D018482:Muscle, Skeletal / Q000473:pathology; D009336:Necrosis; D011817:Rabbits; D011832:Radiation Injuries / Q000473:pathology*; D018709:Statistics, Nonparametric
D003287:Contrast Media; D008652:Mesoporphyrins; D008665:Metalloporphyrins; C118579:gadophrin-2; D019786:Gadolinium DTPA