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Keywords:

Angiography, Animals, Carcinoma, Hepatocellular, Cell Division, Contrast Media, Disease Models, Animal, Dose-Response Relationship, Drug, Gadolinium, Gadolinium DTPA, Image Enhancement, Liver Neoplasms, Experimental, Magnetic Resonance Imaging, Male, Mesoporphyrins, Metalloporphyrins, Neoplasm Transplantation, Rats, Rats, Wistar, Tissue Distribution, Science & Technology, Life Sciences & Biomedicine, Radiology, Nuclear Medicine & Medical Imaging, MAGNETIC RESONANCE IMAGING, CONTRAST AGENT, METALLOPORPHYRIN, LIVER, NEOPLASM, ANIMAL EXPERIMENT, MICROANGIOGRAPHY, MANGANESE-MESOPORPHYRIN, PHOTODYNAMIC THERAPY, TISSUE DISTRIBUTION, PHOTOFRIN-II, NUDE-MICE, HEMATOPORPHYRIN, MEDIA, RAT, PORPHYRINS, 1103 Clinical Sciences, Nuclear Medicine & Medical Imaging, 3202 Clinical sciences

Abstract:

Rationale and objectives 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. Conclusion Metalloporphyrins did not prove to be tumor specific. However, the observed affinity for nonviable tissue has elicited other potential applications for these agents.