Evaluation of methemoglobin as an autologous intravascular MRI contrast agent

✍ Scribed by Stefan Duewell; Claudia E. Kasserra; Peter Jezzard; Robert S. Balaban

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 348 KB
• Volume: 35
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.1910350521

✦ Synopsis

Abstract

Methemoglobin (MetHb) was evaluated as an intravascular paramagnetic contrast agent. Methemoglobin formation was induced by 4‐dimethylaminophenol (4‐DMAP), causing a reduction in blood T~2~* in vitro. The 4‐DMAP generated metHb with a time constant of 62 s. A 4‐DMAP bolus did not decrease measurably the signal intensity in the in vivo rabbit kidney in the first pass. At steady state, a MetHb concentration of 24.8 ± 2.3% resulted in a signal decrease of 9.2 ± 2.6% in the kidney. Methemoglobin is an effective vascular T~2~* relaxation agent, but the formation of MetHb by 4‐DMAP is too slow for first‐pass imaging. A more effective conversion agent resulting in a bolus of at least 25% MetHb within 5 s would result in a detectable first‐pass signal and a viable contrast technique.