Effect of Axial loading on Lumbar spine MRI: Comparative Study of Effect between a Patient Group with Claudication and a Patient Group without Claudication

STUDY DESIGN: This study intended to find out differences of effects by axial loading in MRI examination in a patient group with neurologic claudication and a group without neurologic claudication. OBJECTIVES: It was intended to understand in which group the effects of axial loading can be expected when taking MRI on the lumbar spine. SUMMARY OF THE LITERATURE REVIEW: The study of Willen and Danielson found spinal canal stenosis, which cannot be found by existing methods comparing an MRI taken in bended posture of lumbar without axial loading implementation by MRI taken with axial loading implementation. Hiwatashi et al. also reported that there was a change of treatment direction by laminectomy after axial loading in patients who were intended to take a conservational treatment before the axial loading. MATERIALS AND METHODS: A total of 39 patients and 54 intervertebral discs were compared. The distances from a sagittal plane before and after intervertebral discs were compared by measuring a sectional area of dura mater in a horizontal plane image and two groups were compared by existence of patients' neurologic claudication. RESULTS: The AP diameter before and after a intervertebral discs increased into 41.98 mm from 41.1 mm on the average and the sectional area of dura mater showed 137.47mm2 before loading and 119.86mm2 after loading on the average. There was not a significant difference in the distances before and after axial loading implementation, but a significant difference was found in the sectional area of dura mater. CONCLUSION: Axial loading would contribute to diagnose spinal disease, and especially, spinal canal stenosis in a patient group with claudication.

Diurnal variation in lumbar MRI: Correlation between signal intensity, disc height, and disc bulge

There have been no reports indicating diurnal variations in MRI at different portions of each lumbar disc. Eight asymptomatic healthy volunteers between 22 and 29 years old had MRI of their lumbar spine, twice on the same day (in the morning and evening). Forty lumbar discs were studied and the signal intensity change was measured from three portions of each disc (a total of 120 portions). No visible changes could be detected between scans by blinded observers. However, the calculated signal intensity changes showed an average loss of -20.0% (ant., 5 cases), -19.0% (mid, 2 cases), and -17.5% (post., 1 case). Height loss of the disc showed an average loss of -9.9% (ant., 4 cases), -8.3% (mid., 2 cases), and -10.4% (post., 2 cases). An increase of disc bulge at L4-5 level (18.3%) was pronounced, but L5-S1 level was less than others. Loss of body height averaged a loss of 7 mm (0.39% of body height). There was no correlation between reduced signal intensity and height loss at the ant./post. portion (p = 0.42), but there was a close relation at the mid. portion (p = 0.008). Diurnal change of the disc bulge was not correlated with reduced signal intensity (p = 0.48) or height loss (p = 0.16). Intradiscal fluid change was not necessarily influenced by the disc height loss, and height loss did not necessarily have an effect on disc bulge. But diurnal change showed a trend that was reflected in reduced signal intensity, height loss, and an increase of disc bulge which was more apparent from the ant. portion to the post, portion on moving down to the lower levels. Loss of disc height was one factor in the reduction of body height. These changes occurred randomly throughout 5 lumbar disc levels in each case.