Hematologic bone marrow disorders: quantitative chemical shift MR imaging.

Abstract

Twenty-one in vivo studies of bone marrow of the lumbar spine were performed with a 0.6-T commercial MR imager and proton chemical shift imaging techniques. Six healthy volunteers served as controls. Multiple measurements in the volunteers demonstrated reproducibility within errors of 5% for fat fraction and 6% for T1 of water. Ten patients who had histologically proved leukemia or aplastic anemia were then examined. The data show that changes in fat fraction represent the underlying reason for many of the changes observed in conventional spin-echo (SE) images of these disorders. Although both conventional and chemical shift images showed differences among the pathologic groups and healthy volunteers, fat fraction determined with chemical shift imaging was the single best discriminator among them. A two-point estimate of fat fraction was also evaluated. This rapid imaging protocol performed almost as well as the complete quantitative analysis in discriminating between pathologic and healthy tissue and showed improved discrimination compared with conventional SE techniques.

Two‐point water‐fat imaging with partially‐opposed‐phase (POP) acquisition: An asymmetric Dixon method

“…[5] and [6]. Figure 4c and d show the successfully separated and identified water and fat images, respectively.…”

“…Simple methods have been proposed to achieve phase correction when phase errors are limited to a certain range (5,6). For a more general solution, Yeung and Komos (7) added a "third point" at (Ϫ180°) to the double acquisitions at (0°, 180°) in Dixon's method, and attempted to achieve phase correction by using phase unwrapping.…”

“…Such a tissue mask is readily obtained by comparing all pixels in the image M 1 ϭ | I 1 |, with the standard deviation (SD) n of a noise field n(x, y) obtained as the difference between M 1 and the sum of B and S as described in Eqs. [5] and [6], respectively. This difference is nonzero due to the absolute value operations in Eqs.…”

“…This difference is nonzero due to the absolute value operations in Eqs. [5] and [6], and its value essentially reflects the noise level in the data that is quantified by the SD defined as…”

Quantitative Assessment of Bone Marrow Cellularity by Magnetic Resonance Imaging in Workers with Long-Term Exposure to Solvents.

“…It takes additional time of several minutes for the measurement, but it does not need additional hardware. Several other techniques, chemical shift misregistration artifact 29,30) , inner volume spectroscopic CPMG image technique 31) , or MR spectroscopy [31][32][33] , can provide a good assessment of the bone marrow cellularity, with use of additional instruments.…”