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[Significance of the high-intensity zone located in the posterior annulus fibrosus for diagnosing discogenic low back pain].

OBJECTIVE
To investigate the prevalence of high-intensity zone (HIZ) and the correlation between HIZ and low back pain (LBP).


METHODS
The data of 1000 unselected cases, 566 males and 434 females, aged 49.49 (12 - 86), who underwent lumbar MRI were analyzed to examine the prevalence of HIZ. 200 of the 1000 cases with HIZ which had complete clinical history records, 112 males and 88 females, aged 52.29 (18 - 86), were divided into LBP (n = 115) and non-LBP series (n = 85). CT discography (CTD) was performed in 16 discs in 11 cases with HIZ and the correlation between the modified Dallas' discogram scale and pain reproduction in provocation discography was explored.


RESULTS
HIZ located in posterior annulus fibrosus (AF) was shown in 378 discs in 317 cases, most located in L4/5 and L5/S1 (74.8%) and the location in left side (153 HIZs) was more common than that in right side (94 HIZs). HIZs were shown in superior region (15.4%), middle region (28.8%), as well as inferior region (55.8%) in sagittal plane. 115 of the 200 cases with HIZ who had complete clinical history records (57.5%) were symptomatic and 85 cases (42.5%) were asymptomatic. According to the modified Dallas' discogram scale, LBP could be provoked in 8 of the 9 patients with grade IV and could not be provoked in 6 of the 7 patients with the grade III.


CONCLUSION
Whether HIZ is accompanied with LBP is related to the degree of disc degeneration. When CTD showed the degree of modified Dallas' grade IV and over most of the patients will show LBP. HIZ only indicates the possibility of discogenic LBP and can not replace provocation discography.