Contrast enhancement of PC-3 prostate cancer for magnetic resonance imaging: Animal studies using tumor-localizing Mn-metalloporphyrin (THF-Mn-ASP)

Purpose: The objective of the present study was to test, in nude mouse PC-3 tumors, the contrast enhancement of 2,4-bis(1-tetrahydro-fulfuroxyethyl)-deuteroporphynyl(IX)-6-7-bisaspartic acid (THF-Mn-ASP), which is a hematoporphyrin derivative and depresses T1 relaxation time on magnetic resonance (MR) imaging. Materials and Methods: THF-Mn-ASP or gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) was intravenously administered, and MR imaging of the tumors transplanted into nude mice was performed on T1-weighted images. Results: After administration of THF-Mn-Asp, the signal intensity of PC-3 tumors increased and the tumor/muscle intensity ratio was highest at about 1 hour, The tumor/muscle intensity ratio, in contrast, was highest at about 5 minutes after administration of Gd-DTPA. The increase in intensity ratio was 32% in THF-Mn-ASP and 28% in Gd-DTPA. Conclusion: The preliminary study suggested that THF-Mn-Asp has a predilection to accumulate in PC-3 tumors, and it seems to provide good contrast enhancement with tumor specificity for MR imaging.