Magnetic Resonance Signal Characteristics and Experimental Study: Mn(II)-Pectin as an Oral Dual Contrast Agent

Abstract

This study aimed to investigate the feasibility of using Mn(II)-Pectin as an oral abdominal magnetic resonance contrast agent. The Mn(II)-Pectin solution was prepared and diluted to 11 different concentrations and used for magnetic resonance imaging plain scans. The plain scans were performed with an Mn(II)-Pectin solution (1.594 mmol/L) of the same concentration but at different pH (1–7) values or the same pH (pH = 5.4). The contrast agent may be diluted for further animal studies. The scanned sequences were SET1WI, FRFSE T2WI, PDWI, and Flair T2WI. The signal intensity was measured, and the region of interest was selected as 20 mm2. When the Mn(II)-Pectin concentration ranged from 0.1328 mmol/L to 0.3985 mmol/L, the imaging signal of T1WI was strong and stable (undiluted). When the same manganese ion concentration was used, the Mn(II)-Pectin solution shortened the T1, and the T2 relaxation time was stronger than that for pectin and manganese chloride (MnCl2). The changes in signal intensity were similar at different pH values. With T2WI, the signal intensity did not change with the pH. At the same pH (i.e., pH = 5.4), the signal intensity of Mn(II)-Pectin was significantly higher than for MnCl2 on T1WI, the signal intensity of MnCl2 and Mn(II)-Pectin was almost zero on T2WI, and the signal intensity of pectin was significantly higher than that of MnCl2 and Mn(II)-Pectin on PDWI. The Mn(II)-Pectin solution showed short T1 and T2 signal intensities. Its imaging characteristics were similar to those of the MnCl2 solution. The Mn(II)-Pectin solution is not an ordinary indirect blend but is at least a chemical bond change.