Quantifizierung der Signalmodulation des blutbildenden Knochenmarkes in Gradienten-Echo-Sequenzen

Abstract

The signals from spongy bone on gradient echo sequences depend on the fat and water proton content as well as the differences in magnetic susceptibility at the border between the trabeculae and the bone marrow. From the signal intensities for different echo times, signal modulation was quantified by a special algorithm and at the same time the T2 relaxation time was calculated. Using a fat-water phantom, it was shown that the product of the initial fat and water signal intensity (modulation coefficient) is applicable to indicate the extent of signal modulation and thereby the chemical shift and, moreover, to indicate changes in the fat/water ratio sensitively. In 16 individuals of different ages (23 to 64 years, average 42.4 years) there was a tendency for the T2 relaxation time from the spongiosa of lumbar vertebrae to increase with age, this can be explained by a reduction in the trabecular content, causing reduction in the magnetic inhomogeneity of the bone marrow. The results indicate the usefulness of the sequence and the mathematical model for evaluating the spongy bone in cases of osteoporosis and of malignant haematological disorders.

MRI of bone marrow: opposed-phase gradient-echo sequences with long repetition time

“…3) [2]. According to the geometry, there was a linear change in Q F/W from one end of the long axis of the phantom to the other.…”

“…The TE for inphase or opposed-phase imaging is dependent on B o and the phase shift Df selected. Echo time is shorter the higher the B o [2] and the smaller the number of fatwater cycles [3,4]. TE = Df/Dn Dn = 3.5´10 ±6´w /2p Df = 3.5´10 ±6´T E´w/2p…”