Changes in apparent diffusion coefficient and T2 values in the lumbar intervertebral disc under short-time axial load
10.3969/j.issn.2095-4344.2015.31.025
- VernacularTitle:短时轴向负荷下腰椎间盘表观弥散系数值及T2值的变化
- Author:
Zhaoxi CAI
;
Zehong YANG
;
Yong LI
;
Jianyu CHEN
;
Bingjia LAI
- Publication Type:Journal Article
- Keywords:
Lumbar Vertebrae;
Intervertebral Disk;
Diffusion Tensor Imaging;
Diffusion Magnetic Resonance Imaging
- From:
Chinese Journal of Tissue Engineering Research
2015;(31):5051-5056
- CountryChina
- Language:Chinese
-
Abstract:
BACKGROUND:Disc functional magnetic resonance imaging studies are mostly carried out under lying and a non-load state, and do not reflect the changes in morphology and function of the upright human body under disc load conditions. Therefore, we need to study characteristics of disc functional magnetic resonance imaging in the upright state. OBJECTIVE: To analyze the effect of axial load on apparent diffusion coefficient and T2 of intervertebral discs. METHODS:The study consisted of 17 patients with low back pain aged 34-65 years. Before and after axial load, T2 weighted MR imaging, T1 weighted MR imaging, diffusion tensor imaging, and T2-mapping imaging of the lumbar spine were performed. Load quality was 40%-50% body weight. At 10 minutes after axial load, another diffusion tensor imaging was performed. After 15-minute load, another T2-mapping sequence was scanned. Diffusion tensor imaging scan parameters: single echo-planar imaging, repetition time 2 500 ms, echo time 89 ms, six diffusion directions, b value of 400 s/mm2, sweep time 4:10 minutes. Raw data of diffusion tensor imaging were used to construct apparent diffusion coefficient map and b0 map. Apparent diffusion coefficient value of intervertebral discs was calculated before and after loading. T2 map was automaticaly constructed using T2-mapping sequence to measure apparent diffusion coefficient and T2 values in the whole intervertebral disc of nucleus pulposus, and the changes of them were analyzed under short-time axial load. RESULTS AND CONCLUSION:Pfirrmann grading results in 17 patients with 85 discs were obtained as folows: 0 in Grade I, 26 in Grade II, 19 in Grade III, 30 in Grade IV, and 10 in Grade V. Al 85 disc T2 relaxation time mapping and 84 disc apparent diffusion coefficient mapping were accepted. Under short-time axial load in 84 discs, apparent diffusion coefficient reduced in the whole disc (reduced 38×10-3 mm2/s,Z=2.567,P < 0.05) and nucleus pulposus (reduced 62×10-3mm2/s,Z=3.461,P < 0.05). Apparent diffusion coefficient changes mainly affected Grade Pfirrmann III discs (reduced 55×10-3mm2/s,Z=2.556,P < 0.05). T2 changes mainly affected normal intervertebral discs (Pfirrmann grade II). Under the load, T2 value of intervertebral discs diminished (reduced 3.17 ms,Z=2.967,P < 0.05). No significant difference in apparent diffusion coefficient and T2 value was detected under the load in other grades of the intervertebral discs (P > 0.05). These results suggest that changes in apparent diffusion coefficient and T2 values were different due to different Pfirrmann grades under short-time axial load. To evaluate magnetic resonance imaging function of intervertebral discs, we should choose different evaluation method according to different degeneration degrees.
