Comparison of vertebral morphometry in the lumbar vertebrae by T1-weighted sagittal MRI and radiograph.

Purpose: In this study, we investigated the usefulness of T1-weighted sagittal MR images at the lumbar vertebrae in the vertebral morphometry, in comparison with lateral radiographs.

Subjects And Methods: The subjects were 42 men (mean age: 53.0 years) and 41 women (mean age: 57.9 years). Both MRI and radiography of the lumbar spine were performed within 1 month. The vertebral body heights and their ratios were measured by the semi-automatic measuring system. The frequency of a vertebral fracture and the absolute value of vertebral body height in both morphometry were compared.

Results: Based on the criteria for prevalent vertebral fracture using vertebral height ratios, the vertebrae were classified into four groups. Group 1 was defined as the vertebrae without fracture (n=347 vertebrae). Groups 2-4 were defined as the vertebrae with fracture; Group 2 by both MRI and X-ray morphometry (n=17), Group 3 by MRI morphometry alone (n=17), and Group 4 by X-ray morphometry alone (n=4). The rate of prevalent vertebral fracture diagnosed by MRI morphometry (8.8%) was higher than that by X-ray morphometry (5.5%). In Group 1, the values of anterior and posterior vertebral height obtained by MRI morphometry were greater than those obtained by X-ray morphometry. On the other hand, the values of central vertebral height obtained by MRI morphometry were smaller than those obtained by X-ray morphometry.

Conclusion: Severe biconcave deformity of vertebra can be detected by both MRI and X-ray morphometry, although mild biconcave deformity can be detected only by MRI morphometry.