Localization of metalloporphyrin-induced "specific" enhancement in experimental liver tumors: comparison of magnetic resonance imaging, microangiographic, and histologic findings.
OBJECTIVE
We investigated the tumor specificity of gadolinium mesoporphyrin (Gd-MP) and manganese tetraphenylporphyrin (Mn-TPP) as magnetic resonance (MR) imaging contrast agents.


METHODS
Fifteen rats with multiple hepatocellular carcinomas and eight rats with implanted Novikoff hepatomas were given intravenous injections of either Gd-MP or Mn-TPP at 0.05 mmol/kg, which was compared with nonspecific gadopentetate dimeglumine (0.3 mmol/kg). T1-weighted spin-echo images were obtained before and up to 48 hr after injection and compared with corresponding microangiograms and histologic specimens. The relative enhancement of organs and tumors was plotted as a function of time.


RESULTS
Initially, both metalloporphyrins behaved as nonspecific agents, similar to gadopentetate dimeglumine, and enhanced the tumor by perfusion and diffusion. However, metalloporphyrins, but not gadopentetate dimeglumine, caused a delayed (> or = 3 hr) enhancement in some compartments of certain lesions. The MR imaging-microangiography-histology matching technique revealed that those compartments were actually nonviable components, including necrosis (n = 10), thrombosis (n = 7), and cystic secretion (n = 3), but not viable tumor tissue.


CONCLUSIONS
Metalloporphyrins did not prove to be tumor specific. However, the observed affinity for nonviable tissue has elicited other potential applications for these agents.
Ni
Y
Y
Department of Radiology, University Hospitals Leuven, Belgium.
Marchal
G
G
Yu
J
J
Lukito
G
G
Petré
C
C
Wevers
M
M
Baert
A L
AL
Ebert
W
W
Hilger
C S
CS
Maier
F K
FK
D000792:Angiography; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis* / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D003287:Contrast Media; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005682:Gadolinium / Q000493:pharmacokinetics; D019786:Gadolinium DTPA / Q000493:pharmacokinetics; D007089:Image Enhancement / Q000379:methods; D008114:Liver Neoplasms, Experimental / Q000175:diagnosis* / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D008297:Male; D008652:Mesoporphyrins / Q000493:pharmacokinetics; D008665:Metalloporphyrins / Q000493:pharmacokinetics; D009368:Neoplasm Transplantation; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution
D003287:Contrast Media; D008652:Mesoporphyrins; D008665:Metalloporphyrins; C041471:manganese tetraphenylporphyrin; D005682:Gadolinium; D019786:Gadolinium DTPA