Hole-burning diffusion measurements in high magnetic field gradients

Abstract

We describe methods for the measurement of translational diffusion in very large static magnetic field gradients by NMR. The techniques use a "hole-burning" sequence that, with the use of fringe field gradients of 42 T/m, can image diffusion along one dimension on a submicron scale. Two varieties of this method are demonstrated, including a particularly efficient mode called the "hole-comb," in which multiple diffusion times comprising an entire diffusive evolution can be measured within the span of a single detected slice. The advantages and disadvantages of these methods are discussed, as well as their potential for addressing non-Fickian diffusion, diffusion in restricted media, and spatially inhomogeneous diffusion.

Signal enhancement by diffusion: experimental observation of the “DESIRE” effect

“…2. In accordance with previous publications [17] the measured saturation width (2a exp ) can be defined by the FWHM of a Gaussian fit to the corresponding profile. The calculated and experimental slice thickness values, 2a calc and 2a exp , are plotted in Fig.…”

“…MR images are produced by detecting this missing magnetization via subtraction of images with and without saturation [16]. The expected enhancements, as well as the experimental requirements for the ''DESIRE'' method have been described in detail elsewhere [16] ''hole-burning'' techniques have been used in spectroscopic measurements of diffusion in various media [17][18][19][20]. In this paper, we report the first MR images obtained using the DESIRE technique, attaining signal enhancements of about one order of magnitude.…”

Magnetization tagging decay to measure long‐range 3He diffusion in healthy and emphysematous canine lungs

“…Particularly slow diffusion in an intense field gradient has been measured in supercooled glycerol by means of a multiple hole-burning method (23). We note that the method of stimulated echoes involves spatially modulated longitudinal magnetization, similar to the magnetization shown in Fig.…”

Diffusion-weighted imaging with a rapid repeated hole-burning sequence

“…In our diffusion hole-burning sequence, the z-magnetization is selectively saturated in certain locations and evolves after saturation according to diffusion and T 1 -relaxation. This saturation occurs on a subvoxel level, in contrast to the diffusion measurement method using a hole-burning sequence described in [12]. To this end, several stripes are ''burned'' (i.e., saturated) within one voxel (Fig.…”