Diurnal Fluid Change in Lumbar Discs and Vertebral Marrow with MRI Signal Intensity

Park, Chong Oon

Abstract

No reports in the recorded literature have indicated diurnal variations in MRI of the intervertebral disc and marrow at the different portions of each disc and vertebral body. Eight healthy asymptomatic 8 healthy volunteers between 23 and 29 years old under-went twice-daily MRI of their lumbar spine(AM, PM). forty lumbar discs were studied and the change in signal intensity was measured at three portions of each disc(a total of 120 portions: "a", "b"; middle, and "c"; posterior portion) and vertebral marrow adjacent to each end plate(a total of 240 portions). No visible changes between scans could be detected by blind observers. Calculated signal intensity changes, however, showed an average loss of 20%, 19% and 17.5% at the anterior, middle, and posterior portion, respectively. Signal intensity change at"a"portion was more pronounced at the L2-3 level, at "b"portion at the L4-5, and at"c"portion at the L1-2. Height loss of the disc was on an average 9.9%(anterior), 8.3%(middle), and 10.4% (posterior), but at all portions, was most pronounced at L3-4 level. Signal intensity in the vertebral marrow showed an average increase of 7.8%(anterior), 9.4%(middle) and 9.8%(posterior), the change was most pronounced at the lower, posterior portion, and around the L5 vertebral body. The degree of signal intensity change in the disc did not necessarily correlate with the degree of disc height loss(ant./post.: p<0.42) and marrow signal change(ant.: p<0.15, post.: p<0.18) at two portions of each level. Only at the middle portion, did signal intensity change correlate with disc height loss(p<0.008) and marrow change(p<0.0061). Our conclusions were as follows: 1) there is a diurnal variation in the fluid content of the disc and vertebral marrow; 2) the height of the discs and the change in signal intensity of the disc and marrow tended to be more pronounced from the anterior to posterior portion on moving down to the lower levels; 3) loss of disc height was most severe at L3-4.