Gases as structural contrast agents in MRI, Controlling the diffusion by admixture of buffer gases for biomedical applications

LUIS AGULLES PEDRÓS, RODOLFO H. ACOSTA, PETER BLÜMLER, JÖRG SCHMIEDESKAMP, HANS WOLFGANG SPIESS

Tübingen, Alemania

Congreso; 28th Annual Meeting of the Magnetic Resonance Discussion Group of the Society of German Chemists; 2006

Asociación Alemana de Química

Introduction:
One of the most interesting features in spatially resolved experiments done by MRI of
hyperpolarized gases is the optimisation of resolution and contrast by controlling the diffusivity.
Due to the high diffusivity, the NMR signal strength, the resolution and the appearance of the
images are strongly influenced. These factors scale with the diffusion coefficient (DC), the
strength of the magnetic field gradients and timing used in the experiment. Diffusion may not
only limit the MRI resolution, but also distort the line shape of MRI for samples, which contain
boundaries or diffusion barriers within the sampled space [1,2].
Method:
A novel procedure is proposed to control the DC of gases in MRI by admixture of inert buffer
gases (BG) like N2, SF6, Xe or 4He.
Results:
Enhancement of resolution and highlighting of predefined cavity size is achieved. By varying
BG concentration, the SNR enhancement was optimized. This behaviour can be described
mathematically.
Discussion:
The easily applicable method in medical lung MRI enables images and highlighting of a selected
region of interest depending on its cavity size.