Quantitative Assessment Of High Intensity Zone(HIZ)

Study Design:To establish a series of quantitative measurements for HIZ, and to evaluate the difference of HIZ between symptomatic for low back pain (LBP) and asymptomatic population.Materials and methods:From July2011to July2012, a series of consecutive patients were recruited retrospectively. All patients underwent MRI of the lumbar spine and a defined HIZ was explored (Group A). There were28males and20females aged from24to63years (44.3±9.2years). The asymptomatic controls were those who underwent MRI of the lumbar spine during the same period (Group B).There were28males and20females aged from23to62years (43.8±10.8years). To use ImageJ software to gain the following dates:(1)Area of disc.(2) Area of HIZ (3) CSF-adjusted mean signal of HIZ (4) Ratio of area of HIZ. The reliability of the quantitative assessment of HIZ was evaluated.Results:Excellent intraobserver agreement was obtained for area of disc, area of HIZ, CSF-adjusted mean signal of HIZ, ratio of area of HIZ, and MRI index, ranging from0.838to0.977. Although interobserver reliability was a little bit lower than intraobserver as expected, excellent agreement was also obtained (ICC=0.809～0.935). CSF-adjusted mean signal of HIZ was55.43±9.77in Group A and46.78±10.33in Group B, respectively (P=0.003). Conclution:The quantitative variables were compared between symptomatic and asymptomatic subjects, indicating much brighter intensity in patients with LBP. This quantitative measurements reveal both excellent intra-and interobserver reliability.