Translated Abstract
Background and Purpose：Low back pain (LBP) and/or sciatica is one of the common diseases that influence people‘s life and healthy, and intervertebral disk degeneration (IVDD) is a leading cause of lumbar spine related lower-back pain. Over the past few years, stem cell transplantation of the intervertebral disc has been considered as the most effective therapies of IVDD. Therefore，it is very important to develop an objective and accurate tool for detecting early stage of IVDD to prevent and treat IVDD. MRI analysis can reflect both the macromolecular structure concentrations and structural integrity in the disks, which has been considerated the best method of estimating and studying IVDD in humans in vivo. Traditional clinical MRI emphasizes the signal intensity and morphologic changes of intervertebral disk on T2-weighted imaging (T2WI). However, it is a semiquantitative method and can not assess the IVDD accurately. Diffusion-weighted MR imaging is a noninvasive method of measuring diffusion of water within tissue in vivo. Since intervertebral disk is the largest avascular structure in human body and dependent on diffusion for nutrition, measuring ADC values of intervertebral disks could be used as a quantitative tool to assess disk degeneration. The quantitative transverse relaxation time (T2) based on T2 map has been reported not only to reflect the molecular environment in disk that consists of water, proteins, fat, collagen and other solutes, but also to correlate with the structural integrity of the intervertebral discs. Therefore, T2 may serve as a potential quantitative and sensitive method for detecting the IVDD at early stage. This study included the following five parts to assessment of lumbar intevertebral disc degeneration based on ADC map and T2 map, in order to provide accurate and quantitative imaging informations about biological changes of IVDD and supply foundation on treatment in LBP.1 Assessment of the reliability of lumbar intevertebraldisc degenerated grading system based on MRIObjective：To eveluate the reliability of lumbar intevertebral disc degenerated grading system, and determine a grading system with the highest reliability as standard in this study.Materials and Methods：40 patients with LBP and/or sciatica and 20 asymptomatic volunteers was consecutively recruited in this prospective study. All participants underwent routine lumbar MRI. Based on sagittal T2WI, three radiologists with different experience worked independently and graded 300 lumbar intevertebral disks twice according to different grading systems, included Pfirrmann’s, Griffith’s and Modified Pfirrmann’s grading system. To evaluate the reliability of different grading systems, intra-observer and inter-observer agreements were tested by using kappa statistics.Result：Regarding the three grading reproducibility by different radiologists, the inter-observer and intra-observer reliability of Pfirrmann’s grading system was good or excellent (kappa value ranges: 0.651-0.791 and 0.781-0.845, respectively). The kappa values of inter-observer and intra-observer reliability of Griffith’s grading system were 0.649-0.801 and 0.762-0.865, respectively. The kappa values of inter-observer and intra-observer reliability of Modified Pfirrmann’s grading system were 0.695-0.822 and 0.795-0.890, respectively.Conclusion：In three grading systems about lumbar IVDD, the inter-observer and intra-observer reliability of Modified Pfirrmann’s grading system is the highest one in these systems. So it is considered as the grading system for detecting IVDD based on T2WI in this study.2 Quantitative assessment of lumbar intervertebral diskdegeneration based on MR T2 mapObjective：To evaluate the clinical performance of T2 map for detecting of lumbar intervertebral disk degeneration (IVDD). Materials and Methods：Sagittal fast spin echo T2WI and T2 map were acquired with 1.5 T MR in 46 participants. Disks from L1 to S1 were classified based on the Modified Pfirrmann grading system. T2 value of all nucleus pulposus (NP), anterior and posterior annulus fibrosus (AF) were measured and their variances in different grades were analyzed with one-way ANOVA test. Correlations between T2 value of NP/AF and age/grades were analyzed by Pearson correlation test. Results：Totally 229 disks were measured. ①T2 value of NP decreased while the IVDD grade increased except grade IV and V, significant differences of T2 value of NP were found between other grades (P＜0.05). ②T2 value of anterior AF increased with the increasing of IVDD grade, but there was no significant difference of T2 value of anterior AF between grade I and II, grade I and IV, grade II and IV (P＞0.05). ③Linear regression analysis between T2 value of NP and age revealed significant inverse correlation (P＜0.01), but there was no significant correlation between T2 value of neither anterior AF or posterior AF and age (P＞0.01). Conclusion：T2 measurement of NP is a non–invasive and quantitative tool for detecting the IVDD in early stage based on T2 map.3 Systematic review the apparent diffusion coefficientin normal and degenerated lumbar intervertebral disksObjective：This study aimed to evaluate the ADC values of normal and degenerated intervertebral lumbar disks by meta-analysis. Materials and Methods：Articles published from 2000 to 2010 about the ADC values of IVDD were searched in Cochrane library, Pubmed, OVID database and CNKI for relevant English and Chinese articles. According to the criteria recommended by Cochrane Method Group, two reviewers independently extracted data back-to-back from included studies. The heterogeneity tests were performed and the corresponding effect models were selected to obtain the pooled weighted effect size and corresponding 95% CI by Stata version 10.0. Results：Fifteen studies were included in meta-analysis according to inclusion criteria. The pooled ADC values and 95% CI of the normal intervertebral lumbar disks is 1.90 (1.76～2.04)×10-3mm2/sec. The normal intervertebral lumbar disks of L1-L2、L2-L3、L3-L4、L4-l5、L5-S1 are 1.94 (1.87～2.01), 1.93 (1.87～1.99), 1.97 (1.90～2.04), 1.92 (1.85～1.99) and 1.89 (1.82～1.96)×10-3mm2/sec respectively. The pooled ADC values and 95% CI of the degenerated intervertebral lumbar disks is 1.55 (1.37～1.73)×10-3mm2/sec. The degenerated intervertebral lumbar disks of L1-L2、L2-L3、L3-L4、L4-l5、L5-S1 are 1.49 (1.12～1.86)，1.43 (0.96～1.89), 1.48 (1.06～1.75), 1.44 (1.03～1.85), 1.66 (1.55～1.77) ×10-3mm2/sec respectively. Significant difference of the pooled mean ADC values is found between normal and degenerated disks, which was also found in disks of different levels (P＜0.05).Conclusion：Meta analysis indicated that the range about ADC values of IVDD is lower than that of normal lumbar intervertebral disks, and it may serve as an useful quantitative standard to assess the IVDD.4 Quantitative assessment of lumbar intervertebral diskdegeneration and age-related changes based on T2 and ADC mapObjective：To compare two measures in detecting IVDD and their age-related changes.Materials and Methods：37 asymptomatic volunteers and 28 patients with back pain or sciatica were examined and their lumbar disk T2 and ADC maps quantified via sagittal imaging protocols at 1.5 Tesla. For all participants, Modified Pfirrmann‘s system was used for grading disks by two radiologists. T2 and ADC values in the inner portion of disks were measured and their variances in different grades were analyzed by one–way ANOVA test. The ability of T2 and ADC measures for differentiating IVDD grades was compared based on their receiver operating characteristic (ROC) curves. For asymptomatic subjects, the correlations between age and the two MR measures were assessed by Pearson‘s correlation test. Results：Both T2 and ADC values were found to decrease with the increasing Pfirrmann grades except T2 in grade V. Significant T2 differences were seen between grades I to IV, but not between grades IV and V. There were no significant ADC differences between grades I to III. Moreover, the areas under ROC curves differed significantly (0.95 and 0.67 for T2 and ADC, respectively). Linear regression analysis revealed that T2 yielded more significant correlation with age (r = - 0.77) than ADC did (r = - 0.37).Conclusion：Compared with ADC map, T2 quantitation provides a more sensitive and robust approach for detecting and characterizing the early stage of IVDD and age-related disk changes.5 Quantitative research of bulging and herniation in lumbarintevertebral disk based on T2 and ADC mapObjective：Comparison of T2 and ADC values in normal, bulging and herniated of lumbar intervertebral disks based on T2 and ADC map.Materials and Methods：Sixty patients with back pain or sciatica were examined by MRI and their lumbar disk T2WI, T2 and ADC maps quantified via sagittal imaging protocols. All disks were classified morphologically according to degenerated grades and herniated groups by two radiologists. To evaluate differences between the classified groups, ANOVA with post hoc Games–Howell was used. Moreover, the correlations between ADC and T2 values and disk level were assessed by Spearman correlation test. Results：Linear regression analysis between ADC and T2 values and disc level revealed inverse correlation (r=－0.18, r＝-0.19, P＜0.01). The significant difference of mean ADC value was found between normal disks and bulging discs as well as herniated disks. Whereas there was no significant difference in mean ADC value between bulging and herniated disks. Moreover, the mean T2 values of normal group was the highest and the herniated group was the lowest, the bulging group was middle. Significant difference of mean T2 value was found between any groups. Significant ADC and T2 differences were seen between any degenerated grades. Conclusion：Compared with ADC map, T2 map is a more sensitively and accurately quantitative tool to assess componential and molecular alterations accompany with disk bulging or herniation.
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