Apparent diffusion coefficients and T2 relaxation time measurements to evaluate disc degeneration. A quantitative MR study of young patients with previous vertebral fracture.

PURPOSE: To assess the suitability of apparent diffusion coefficient (ADC) measurements to evaluate degeneration processes of the vertebral disc and to compare the results with T2 relaxation time measurements in both degenerated and normal intervertebral discs. MATERIAL AND METHODS: Fourteen young patients (8.8-20.8 years old) who had had a vertebral compression fracture at least 1 year earlier, underwent MR studies with diffusion imaging in three orthogonal directions and T2 relaxation time measurements. ADC values and T2 relaxation times of both degenerated and normal intervertebral discs were compared to the values of 20 healthy young asymptomatic control subjects. RESULTS: In the degenerated discs of patients, the ADCx and ADCy values were decreased compared to earlier determined values of healthy controls. ADC values in the z-direction in degenerated discs did not differ significantly from the values of controls. T2 relaxation times were shorter in the degenerated discs of patients compared to the values of controls. The greatest changes in both these values were observed in degenerated discs followed by discs with normal signal intensity adjacent to primary trauma area and secondary trauma area. CONCLUSION: We suggest that decreased ADC values reflect the lost integrity of the intervertebral disc. ADC measurements at MR may prove sensitive depicting of early degenerative changes in vertebral discs.

Correlation of diffusion in lumbar intervertebral disks with occlusion of lumbar arteries: a study in adult volunteers.

PURPOSE: To evaluate the correlation of the diffusion values in lumbar intervertebral disks with lumbar artery status and the degree of disk degeneration. MATERIALS AND METHODS: Sagittal T2-weighted images of the lumbar spine were obtained in 37 asymptomatic volunteers aged 22-68 years. The apparent diffusion coefficient (ADC) of 98 lumbar intervertebral disks was determined, and two-dimensional time-of-flight magnetic resonance angiography was performed on the corresponding 98 lumbar artery pairs (total arteries = 196). The degree of disk degeneration and the status of lumbar arteries were evaluated independently by two radiologists. ADC calculations were performed on the basis of the average signal intensities of the selected region of interest in lumbar disks. The association between ADC values of disks, the disk degeneration, and the status of lumbar arteries of the same level were analyzed with analysis of covariance, and pairwise analysis between groups (Scheffé post hoc multiple comparison) was performed with statistical software. P values less than .01 were considered significant. RESULTS: The lumbar arterial status correlated strongly with the diffusion values of intervertebral disks, and the ADC values decreased with higher degrees of arterial narrowing. The correlation between disk degeneration and diffusion was not significant. Eight severely degenerated disks with normal lumbar artery status and diffusion values were found. CONCLUSION: Impaired flow in lumbar arteries is significantly associated with decreased diffusion in lumbar disks and may play an important role in disk degeneration.

Apparent diffusion coefficient in thoracolumbar intervertebral discs of healthy young volunteers.

Apparent diffusion coefficient values (ADC) of healthy intervertebral discs of young volunteers in the thoracolumbar spine were determined using a single-shot EPI sequence. ADC(z) was in the lumbar spine slightly higher than ADC(x) or ADC(y). In vivo diffusion measurements of intervertebral discs may offer a novel diagnostic tool to evaluate disc diseases in early phases.

Post-traumatic findings of the spine after earlier vertebral fracture in young patients: clinical and MRI study.

STUDY DESIGN: A study comparing magnetic resonance imaging findings of degenerative changes in intervertebral discs in young patients with previous wedge-shaped compression fracture and age-matched and sex-matched control subjects. OBJECTIVES: To find out the role of fractures in disc degeneration and to assess the clinical outcome of the patients. SUMMARY OF BACKGROUND DATA: Several experimental studies have postulated that trauma is one of the major reasons for disc degeneration. Wedge compression fractures in vertebrae of children have been considered insignificant, but this has not been verified in the literature. METHODS: Fourteen patients 8.8 to 20.8 years of age (mean, 15.5 years) with a history of wedge-shaped vertebral compression fracture at least 1 year previously (mean, 3.8 years) and asymptomatic healthy control subjects were studied by thoracolumbar spine magnetic resonance imaging. The patients also underwent a clinical examination. RESULTS: Eight (57%) of the 14 patients had disc degeneration, and seven of them had it at the trauma level. Of these 7 subjects, 6 also had endplate damage at this level. The association between endplate damage and adjacent intervertebral disc degeneration was significant (P < 0.01). Only 2 of the patients were symptomatic. In the control group, only 1 subject had disc degeneration with endplate changes and disc herniation. CONCLUSIONS: The patients had more disc degeneration than did those in the control group. Endplate injury was strongly associated with disc degeneration. No correlation between previous vertebral fracture and back pain was seen in this study.