Diffusion tensor imaging in multiple sclerosis: assessment of regional differences in the axial plane within normal-appearing cervical spinal cord.

BACKGROUND AND PURPOSE: Evaluation of the spinal cord is important in the diagnosis and follow-up of patients with multiple sclerosis. Our purpose was to investigate diffusion tensor imaging (DTI) changes in different regions of normal-appearing spinal cord (NASC) in relapsing-remitting multiple sclerosis (RRMS). METHODS: Axial DTI of the cervical spinal cord was performed in 24 patients with RRMS and 24 age- and sex-matched control subjects. Fractional anisotropy (FA) and mean diffusivity (MD) were calculated in separate regions of interest (ROIs) in the anterior, lateral, and posterior spinal cord, bilaterally, and the central spinal cord, at the C2-C3 level. Patients and control subjects were compared with respect to FA and MD with the use of an exact Mann-Whitney test. Logistic regression and receiver operating characteristic (ROC) curve analysis assessed the utility of each measure for the diagnosis of RRMS. RESULTS: DTI metrics in areas of NASC in MS were significantly different in patients compared with control subjects; FA was lower in the lateral (mean +/- SD of 0.56 +/- 0.10 versus 0.69 +/- 0.09 in control subjects, P < .0001), posterior (0.52 +/- 0.11 versus 0.63 +/- 0.10, P < .0001), and central (0.53 +/- 0.10 versus 0.58 +/- 0.10, P = .049) NASC ROIs. Assessing DTI metrics in the diagnosis of MS, a sensitivity of 87.0% (95% confidence interval [CI], 66.4 to 97.1) and a specificity of 91.7% (95% CI, 73.0 to 98.7) were demonstrated. CONCLUSION: The NASC in RRMS demonstrates DTI changes. This may prove useful in detecting occult spinal cord pathology, predicting clinical course, and monitoring disease progression and therapeutic effect in MS.

Comparison of rates of change in bone density as measured by dual-energy X-ray absorptiometry and quantitative computed tomography in osteoporotic females treated with fluoride.

We conducted a retrospective comparison of the rates of change in vertebral bone density measured by two densitometric techniques: dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) in osteoporotic women treated with fluoride. To compare both densitometric methods, lumbar vertebral bone density was determined before and during fluoride therapy in 104 osteoporotic women. All patients signed an informed consent under a protocol approved by our University Institutional Review Board. All subjects had at least three serial measurements using both densitometric techniques over the studied time period. Linear regression was used to calculate rate of change values for each patient. In agreement with previous published reports, lumbar density increased linearly over time both with DXA and QCT. Rates of change determined by DXA and QCT were significantly correlated (r = 0.88, p < 0.0001) and this relationship was independent of the magnitude of the increase in density. Either densitometric technique may be used to evaluate the axial skeletal response to fluoride therapy.