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Deconvolution of Compartmental Water Diffusion Coefficients in Yeast-Cell Suspensions Using Combined T1 and Diffusion Measurements

โœ Scribed by Matthew D. Silva; Karl G. Helmer; Jing-Huei Lee; Sam S. Han; Charles S. Springer Jr.; Christopher H. Sotak


Publisher
Elsevier Science
Year
2002
Tongue
English
Weight
211 KB
Volume
156
Category
Article
ISSN
1090-7807

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โœฆ Synopsis


An NMR method is presented for measuring compartmentspecific water diffusion coefficient (D) values. It uses relaxography, employing an extracellular contrast reagent (CR) to distinguish intracellular (IC) and extracellular (EC) 1 H 2 O signals by differences in their respective longitudinal (T 1 ) relaxation times. A diffusionweighted inversion-recovery spin-echo (DW-IRSE) pulse sequence was used to acquire IR data sets with systematically and independently varying inversion time (TI) and diffusion-attenuation gradient amplitude (g) values. Implementation of the DW-IRSE technique was demonstrated and validated using yeast cells suspended in 3 mM Gd-DTPA 2-with a wet/dry mass ratio of 3.25 : 1.0. Twodimensional (2D) NMR data were acquired at 2.0 T and analyzed using numerical inverse Laplace transformation (2D-and sequential 1D-ILT) and sequential exponential fitting to yield T 1 and water D values. All three methods gave substantial agreement. Exponential fitting, deemed the most accurate and time efficient, yielded T 1 : D (relative contribution) values of 304 ms : 0.023 ร— 10 -5 cm 2 /s (47%) and 65 ms : 1.24 ร— 10 -5 cm 2 /s (53%) for the IC and EC components, respectively. The compartment-specific D values derived from direct biexponential fitting of diffusion-attenuation data were also in good agreement. Extension of the DW-IRSE method to in vivo models should provide valuable insights into compartment-specific water D changes in response to injury or disease.


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