Assessment of the skeletal status by MR relaxometry techniques of the lumbar spine: comparison with dual X-ray absorptiometry

Purpose: To measure lumbar spine T2*, T2, T2' and T1 MR relaxometry parameters and compare them with lumbar spine bone mineral density (BMD) in a group of postmenopausal women. Materials and methods: Lumbar spine T2*, T2, T2' and T1 MR relaxometry parameters and BMD values were assessed in 10 1 postmenopausal women (mean age: 61.8 +/- 7.1 (1 S.D.) years); of them 63 referred to as control subjects (group A, BMD T-scores greater than or equal to -2.5 S.D.) and 38 as osteoporotic (group B, BMD T-scores < -2.5 S.D.). All magnetic resonance imaging (MRI) examinations were performed on an 1.5 T imaging system using: (a) a 2D single slice multi echo (32 echoes) gradient echo (MEGRE) sequence (TR/TE1/TE32/FA: 160/2.7/74.93 ms/25degrees) for the T2* measurement, (b) a respiratory gated 2D single Slice Multi Echo (16 echoes) Spin Echo (MESE) sequence (TR/TE1/TE16/FA: 2000-2500/22.5/360 ms/90degrees) for the T2 measurement and (c) a 2D single slice multi T1 (18 repeats) turbo Fast Low Angle Shot (turbo FLASH) sequence (TR/TE/T11/T116/FA: 11/4.2/10/5000 ms/10degrees) for the T1 measurement. TT was calculated from its definition equation: (I/T2' = 1/T2* - 1/T2). Lumbar spine BMD was assessed using DXA. Results: All measured parameters showed statistically significant differences between groups A and B (from P < 0.05 to <0.001). All parameters showed significant associations with subject's age ranging from r = 0.245 (P < 0.05) for the T2 up to r = 0.377 (P < 0.001) for the T2*. All parameters showed significant associations with subject's BMD measurements ranging from r = -0.184 (P < 0.05) for the R1 = (1/T1) up to r = -0.345 (P < 0.0005) for the T2. Conclusion: Among the MR relaxometry parameters studied, T2* and T2 showed better discrimination of patients with osteoporosis from control Subjects. (C) 2004 Elsevier Ireland Ltd. All rights reserved.