We propose to evaluate and further develop a novel technique based on magnetic resonance (MR) for quantitative assessment of the structure of trabecular bone in normals and patients with clinically established osteoporosis. We intend to determine whether this index of trabecular structure predicts the presence of fractures in patients with osteoporosis and to compare and correlate the findings of this new parameter with bone mineral density measurements. The new technique is based on a measurement of MR T2* which is related to the intrinsic inhomogeneity of the magnetic field in the intertrabecular space, caused by the presence of two phases of different diamagnetic susceptibility: bone and bone marrow. In support of this hypothesis, our preliminary data show that T2* increases in the lumbar vertebrae with age and is markedly increased in patients with clinically evident osteoporosis with fractures. Moreover, we have found that T2* predicts the degree of trabeculation of die distal femur with T2* following the order: diaphysis>metaphysis>epiphysis. Both findings corroborate the expected inverse relationship between trabecular plate density and T2*. A technique, denoted MR interferometry, developed in the investigators' laboratory, permits measurement of T2* from a series of gradient-who images acquired with an array of echo delays, using ROI analysis and curve fitting techniques. We intend to establish a normal baseline by measuring T2* as well as the apparent fat/water ratio (a by-product of the analysis) in 75 normal women. To assess the sensitivity and specificity of this technique in osteoporosis, we compare MR indices of trabecular structure with those obtained from bone mineral density measurements in 75 patients with osteoporosis with and without vertebral compression fractures. Finally, we intend to determine the relationship of the trabecular plate density as predicted by T2* and bone strength by evaluating the relationship among trabecular microstructure, as evaluated by MR microscopy, T2* and mechanical load-bearing capacity on cadaver specimens of human vertebrae.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR040671-03
Application #
2080194
Study Section
Diagnostic Radiology Study Section (RNM)
Project Start
1991-07-01
Project End
1994-12-31
Budget Start
1993-07-01
Budget End
1994-12-31
Support Year
3
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of Pennsylvania
Department
Radiation-Diagnostic/Oncology
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Wehrli, Felix W; Song, Hee Kwon; Saha, Punam K et al. (2006) Quantitative MRI for the assessment of bone structure and function. NMR Biomed 19:731-64
Gomberg, Bryon R; Saha, Punam K; Wehrli, Felix W (2005) Method for cortical bone structural analysis from magnetic resonance images. Acad Radiol 12:1320-32
Wehrli, F W; Hwang, S N; Ma, J et al. (1998) Cancellous bone volume and structure in the forearm: noninvasive assessment with MR microimaging and image processing. Radiology 206:347-57
Song, H K; Wehrli, F W; Ma, J (1997) Field strength and angle dependence of trabecular bone marrow transverse relaxation in the calcaneus. J Magn Reson Imaging 7:382-8
Ma, J; Wehrli, F W; Song, H K et al. (1997) A single-scan imaging technique for measurement of the relative concentrations of fat and water protons and their transverse relaxation times. J Magn Reson 125:92-101
Ma, J; Wehrli, F W; Song, H K (1996) Fast 3D large-angle spin-echo imaging (3D FLASE). Magn Reson Med 35:903-10
Ma, J; Wehrli, F W (1996) Method for image-based measurement of the reversible and irreversible contribution to the transverse-relaxation rate. J Magn Reson B 111:61-9
Wehrli, F W; Ford, J C; Haddad, J G (1995) Osteoporosis: clinical assessment with quantitative MR imaging in diagnosis. Radiology 196:631-41
Wehrli, F W; Ford, J C; Chung, H W et al. (1993) Potential role of nuclear magnetic resonance for the evaluation of trabecular bone quality. Calcif Tissue Int 53 Suppl 1:S162-9
Chung, H; Wehrli, F W; Williams, J L et al. (1993) Relationship between NMR transverse relaxation, trabecular bone architecture, and strength. Proc Natl Acad Sci U S A 90:10250-4

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