Abstract
To assess the structure of cancellous tissue in the vertebral bone marrow, we analyzed the restricted diffusion using diffusion kurtosis. On a 1.5T MRI, single-shot diffusion echo planar imaging was used with b values of 0, 20, 120, 500, 1200 and 2200 s/mm2, and a sensitivity encoding technique. Apparent diffusion kurtosis (Kapp) and apparent diffusion coefficient (Dapp) were calculated from diffusion kurtosis analysis based on non-Gaussian diffusion theory. Kapp and Dapp were determined in the lumbar vertebral body of seven normal subjects, and then compared with the bone mineral density (BMD) obtained with dual-energy X-ray absorptiometry. Moreover, fat fraction (FF) of the bone marrow was measured with spectral presaturation with inversion recovery in the same subject. A strong positive correlation was found between Kapp and BMD (R2 = 0.63, P = 0.034) , and FF (R2 = 0.72, P = 0.015) . However, there was no significant correlation between Dapp and BMD, and FF. These results indicating the greater utility of the Kapp than that of the Dapp. Water-restricted diffusion analysis with diffusion kurtosis makes it possible to obtain more detailed information on the structure of cancellous tissue and the bone metabolism.
