Tumor enhancement using Mn-metalloporphyrin in mice: magnetic resonance imaging and histopathologic correlation.

PURPOSE: To determine the signal enhancement characteristics of tumors after administration of a metalloporphyrin derivative, HOP-9P (13, 17-bis (1-carboxypropionyl) carbamoylethyl-3, 8-bis (1-phenylpropyloxyethyl)-2, 7, 12, 18-tetramethyl-porphyrinato manganese (III)) and to determine whether HOP-9P is tumor-necrosis specific. MATERIALS AND METHODS: Ten C3H/He mice bearing a SCC VII tumor in the right flank were examined using T1-weighted conventional spin echo magnetic resonance (MR) imaging before contrast injection, and five minutes, one hour, and 24 hours after intravenous administration of 0.1 mmol/kg of HOP-9P. Following the imaging schedule, the mice were sacrificed, and sectioned in the same axial planes as the MR images. Based on an MR imaging-histopathologic correlation, mean signal intensities were measured, and signal-to-noise ratios (SNR) were calculated for both pure viable component and admixture of necrotic and viable component of the tumor. RESULTS: Mean SNR of the pure viable component peaked at one hour (35.0 +/- 3.8) and maintained that level until 24 hours (34.6 +/- 3.6). Mean SNR of the admixture of necrotic and viable component peaked at 24 hours (44.3 +/- 12.1). CONCLUSION: Although different enhancement patterns were seen between the pure viable component and the admixture of necrotic and viable component, HOP-9P enhanced both of the two components.

Assessment of a potential tumor-seeking manganese metalloporphyrin contrast agent in a mouse model.

The performance of a newly developed potential tumor-seeking magnetic resonance (MR) contrast agent alpha-Aqua-13,17-bis(1-carboxypropionyl) carbamoylethyl-3,8-bis(1-phenethyloxyethyl)-beta-hydroxy-2,7,12,18-tetramethyl-porphyrinato manganese (III) (HOP-8P) was tested using a mouse model. Tumor-bearing (SCC-VII) mice were imaged using a 1.5T MR imager before and after intravenous administration of 0.1 mmol/kg of HOP-8P. A biodistribution analysis was performed using an optical emission spectrometer. Significant enhancement of the transplanted tumor was observed in MR images 24 h after intravenous injection of HOP-8P. The biodistribution assessment of manganese also correlated with the results of the imaging study. During the 24-h period following contrast administration, HOP-8P was consistently cleared from the circulation, liver, kidneys, and muscle; however, it was progressively accumulated within the tumor. HOP-8P is a promising tumor-seeking metalloporphyrin MR contrast agent with a wide imaging window.