T2* Mapping of the Adult Intervertebral Lumbar Disc: Normative Data and Analysis of Diurnal Effects.

In this prospective study, we sought to establish normative data for T2* analysis of lumbar intervertebral discs (IVDs). Further, potential diurnal effects regarding T2* relaxometry of the lower spine were examined. Lumbar IVDs of young, healthy, adult men (n = 20) and women (n = 20; mean age = 24.5 ± 2.9 years) were assessed. Magnetic resonance imaging including T2* mapping was performed on a 3-T scanner. Mid-sagittal T2* values were obtained in five regions: anterior annulus fibrosus (AF), anterior nucleus pulposus (NP), central NP, posterior NP, and posterior AF. Zonal and segmental differences, as well as diurnal variations between the T2* analysis in the morning and the evening and effects of unloading, were analyzed. Discs with signs of degeneration on morphological images or imaging artifacts were excluded. We noted a zonal and segmental T2* distribution with high values in the NP, low T2* values in the AF and a T2* increase towards the caudal NP. We observed no diurnal differences between the mean T2* values in the morning and in the evening (p = 0.748). The effect of unloading the spine was low (maximum T2* difference between four measurements = 13.6 ms; significant difference noted only between the 0 and 15-min measurement). The T2* values obtained in this study will serve as normative values for future T2* measurements. There are no diurnal influences, and we suggest that unloading of the spine has no demonstrable effect after 30 min on the T2* results.