Size and change rule of apparent diffusion coefficient of normal lumbar spine

Objective To investigate the apparent diffusion coefficient(ADC) value and the size of normal lumbar spine 1-5,and discuss the rule of ADC changed in lumbar with age.Methods A total of 125 normal volunteers were enrolled,male 78,female 47,aged 12-68 years old,mean age 43.21 years old(standard deviation 11.75 years old).More specifically,26 cases were ≤ 20 years old,male 17,female 9;61 cases were aged 20-40 years old,male 37,female 24;38 cases were 40 years old,male 26,female 12.The normal lumbar spine confirmed by clinical data and magnetic resonance imaging(MRI) were retrospectively analyzed,and the sizes of the region of interest(ROI) were 33,66,132,165,198,231,264,297 mm2,respectively.The mean ADC of lumbar spine 1st-5th and the mean ADC value of total vertebrae lumbar spine were calculated.All of the results were analyzed statistically,which were divided into 3 groups: ≤ 20 years old group,20-40 years old group and 40 years old group,and the 3 groups of mean ADC value were calculated.Results The ADC(× 10-4 mm2/s) value of total vertebrae lumbar spine was 1.92 ± 0.79,values of 1st-5th lumbar vertebral ADC(× 10-4mm2/s) were 2.00 ± 0.76,1.88 ± 0.71,1.87 ± 0.87,1.88 ± 0.83 and 1.99 ± 0.75,respectively.The t test showed no significant difference between 1st and 5th lumbar vertebrae,and no significant difference among lumbar vertebrae 2nd,3rd and 4th(P 0.05),the difference was statistically significant(P 0.05) between the 1st or 5th lumbar vertebrae and 2nd,3rd or 4th lumbar vertebrae.The ADC values reduced gradually from lumbar vertebrae 1st to 3rd,and the ADC values of lumbar vertebra 1st was closed to lumbar vertebra 5th.The ADC(× 10-4mm2/s) value in the groups of ≤ 20 years old,20-40 years old and 40 years old were 1.94 ± 0.77,1.93 ± 0.82,1.89 ± 0.79,respectively,and no significant difference was observed among the 3 groups(P 0.05).Conclusion It is demonstrated that the lumbar vertebral ADC(× 10-4mm2/s) average is about 1.92 ± 0.79,which are large in the two ends and small in the middle lumbar vertebrae.Measurement of the lumbar lesion ADC value should be selected in normal conditions,and ADC values of the nearest normal vertebral body is relatively appropriate as a comparison.With the increase of age,the ADC value of lumbar vertebrae would have a downward trend.