The diffusion coefficient of lipids, D(l), within bone marrow, fat deposits and metabolically active intracellular lipids in vivo will depend on several factors including the precise chemical composition of the lipid distribution (chain lengths, degree of unsaturation, etc.) as well as the temperature. As such, D(l) may ultimately prove of value in assessing abnormal @entity844 distributions linked to diseases such as @entity1577 , @entity6 and @entity301 . A sensitive temperature dependence of D(l) may also prove of value for MR-guided thermal therapies for @entity3478 or disease within other fatty tissues like the breast. Measuring diffusion coefficients of high molecular weight lipids in vivo is, however, technically difficult for a number of reasons. For instance, due to the much lower diffusion coefficients compared to water, much higher b factors than those used for central nervous system applications are needed. In addition, the pulse sequence design must incorporate, as much as possible, immunity to motion, susceptibility and chemical shift effects present whenever body imaging is performed. In this work, high b-factor line scan diffusion imaging sequences were designed, implemented and tested for D(l) measurement using a 4.7-T horizontal bore animal scanner. The gradient set available allowed for b factors as high as 0.03 micros/nm(2) (30,000 s/mm(2)) at echo times as short as 42 ms. The methods were used to measure lipid diffusion coefficients within the marrow of @entity35 paws in vivo, yielding lipid diffusion coefficients approximately two orders of magnitude smaller than typical tissue water diffusion coefficients. Phantom experiments that demonstrate the sensitivity of lipid diffusion coefficients to chain length and temperature were also performed.

In vivo lipid diffusion coefficient measurements in XXXX bone marrow.

@entity844 :: ('CHEBI:35366', 'Chemical') :: ['fatty acid'] @entity6 :: ('MESH:D003920', 'Disease') :: ['diabetes'] @entity3478 :: ('MESH:D001859', 'Disease') :: ['bone tumors'] @entity301 :: ('MESH:D003327', 'Disease') :: ['coronary heart disease'] @entity35 :: ('10116', 'Species') :: ['rat'] @entity1577 :: ('MESH:D003550', 'Disease') :: ['cystic fibrosis']
@entity35 :: (10116,Species) :: ['rat']
