A Single-Pot Template Reaction Towards a Manganese-Based T1 Contrast Agent.

Manganese-based contrast agents (MnCAs) have emerged as suitable alternatives to gadolinium-based contrast agents (GdCAs). However, due to their kinetic lability and laborious synthetic procedures, only a few MnCAs have found clinical MRI application. In this work, we have employed a highly innovative single-pot template synthetic strategy to develop a MnCA, MnLMe , and studied the most important physicochemical properties in vitro. MnLMe displays optimized r1 relaxivities at both medium (20 and 64 MHz) and high magnetic fields (300 and 400 MHz) and an enhanced r1 b =21.1 mM-1  s-1 (20 MHz, 298 K, pH 7.4) upon binding to BSA (Ka =4.2×103  M-1 ). In vivo studies show that MnLMe is cleared intact into the bladder through renal excretion and has a prolonged blood half-life compared to the commercial GdCA Magnevist. MnLMe shows great promise as a novel MRI contrast agent.