Determination of H relaxation times of water in human bone marrow by fat‐suppressed turbo spin echo in comparison to MR spectroscopic methods

Abstract

Relaxation times of water were measured in human vertebral bodies by a fat-suppressed dual-echo turbo spin echo/turbo inversion recovery MRI sequence. Comparison was made with T1 and T2 values obtained by localized 1H-MR spectroscopy. The accuracy of the results and the diagnostic potential of the fast quantitative MRI technique were evaluated in 20 volunteers, 11 patients with osteoporosis, 6 patients with lymphoma, and 6 patients with bone marrow metastasis. No significant alterations of T1 and T2 relaxation times of water and fat were found in osteoporosis. With both methods, an increase in the T1 values of the water resonance by 16% was observed in lymphomas, which was highly significant (P < .001) in the MRS measurements, and an elevation by the same amount was obtained by the MRI sequence for the metastases (P = .040). A strong reduction of fat fraction was quantified by MRS in the tumorous cases. T2 of the water resonance increased by more than 30% (P < .003) in metastases. Water T2 values obtained by the MRI sequence showed systematic deviations from the MRS results, especially at short echo spacings.

Multiparameter MRI assessment of normal-appearing and diseased vertebral bone marrow

“…Träber et al at 1.5 T reported an increase in T1 of water of 16% in malignant lesions compared with normal vBM [14]. We found an increase of 43% in malignant lesions compared with normal-appearing vBM in the same patient, possibly explained by the higher ratio of free to fixed water in tumours.…”

“…A separate determination of relaxation times and ADCs for both components might avoid this misinterpretation. [14,15]. The standard deviations and the IPV of T1 in fat are relatively large, possibly caused by partially insufficient water suppression in the present study.…”

“…Bulk T1 and T2 relaxation times [5][6][7] and ADCs [8][9][10][11][12] of vBM were determined in various studies, reflecting average parameters of both components without permitting them to be separated. Only a few studies separately determined the parameters for the fat and water components in normal vBM as well as in pathological conditions [13][14][15].…”

“…Since both pathologies are expected to change the tissue physiology differently, quantitative imaging might therefore be able to differentiate between benign and malignant lesions and overcome the limitations of qualitative criteria. T2 [14,23,24], T1 [14,23] and especially the ADC [25][26][27][28][29][30][31] were evaluated in this context.…”

Hybrid Imaging: Instrumentation and Data Processing

“…Moreover, the imaging of cortical bone is a challenge in MR given the fast relaxation times of solid materials [206]. As a consequence, it is not possible to distinguish between cortical bone and air in most MR sequences [207].…”