J Korean Soc Magn Reson Med.  2002 Jun;6(1):35-40.

The Synthesis and MR Properties of New Macromolecular MR Contrast Agent

Affiliations
  • 1Department of Diagnostic Radiology, College of Medicine, Kyungpook National University and Hospital, Korea.
  • 2Department of Chemistry, KAIST, Korea.
  • 3Department of Biomedical Engineering, Kyungpook National University, Korea.
  • 4Department of Veterinary Medicine, Kyungpook National University, Korea.
  • 5The Biomedical Research Institude, Kyungpook National University Hospital, Korea.

Abstract

PURPOSE: To evaluate the NMR relaxation properties and imaging characteristics of tissue-specificity for a newly developed macromolecular MR agent.
MATERIALS AND METHODS
Phthalocyanine (PC) was chelated with paramagnetic ion, Mn. 2.01g(5.2 mmol) of Phthalocyanine was mixed with 0.37g (1.4 mmol) of Mn chloride at 310 degrees C for 36 hours and then purified by chromatography (CHC13/CH3OH 98/2 v/v, Rf, 0.76) to obtain 1.04g (46%) of MnPC (molecular weight = 2000d), The T1/T2 relaxivity of MnPC was measured in 1.5T(64 MHz) MR using 0.1 mM MnPC. The MR image characteristics of MnPC was evaluated using spin-echo (TR/TE = 500/14 msec) and gradient-echo (FLASH) (TR/TE = 80/4 msec, flip angle = 60) techniques in 1.5T MR scanner. The images of rabbit liver were obtained every 10 minutes up to 4 hours. To study the effect of concentration on image, 20 mM, 50 mM, 100 mM of MnPC were tested.
RESULTS
The relaxivities of MnPC at 1.5T (64MHz) were R1 = 7.28 mM-1S-1, R2 = 55.56 mM-1S-1. Compared to the values of Gd-DTPA (R1[= 4.8 mM-1S-1), R2[= 5.2 mM-1S-1]), both T1/T2 relaxivities of MnPC were higher than those of Gd-DTPA. For both of SE and FLASH techniques, the contrast enhancement reached maximum at 10 minutes after bolus injection and the enhancement continued for more than 2 hours. When compared with small molecular weight liver agents such as Gd-EOB-DTPA, Gd-BOPTA and MnDPDP, MnPC was characterized by more prolonged enhancement time. The time course of MR images also revealed biliary excretion of MnPC.
CONCLUSION
We developed a new macromolecular MR agent, MnPC. The relaxivities of MnPC were higher than those of small molecular weight Gd-chelate. Hepatic uptake and biliary excretion of MnPC suggests that this agent is a new liver-specific MR agent.

Keyword

Contrast Agent; Liver, Relaxation; Paramagnetism; Macromolecule

MeSH Terms

Chromatography
Gadolinium DTPA
Liver
Molecular Weight
Relaxation
Gadolinium DTPA
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