Correlation of diffusion in lumbar intervertebral disks with occlusion of lumbar arteries: a study in adult volunteers

The trajectory characteristics and clinical significance of the left-sided lumbar segmental artery: a prospective cross-sectional radio-anatomical study

Background

Vascular injury to the lumbar segmental arteries is a devastating complication in minimally invasive lumbar interbody fusion. Previous studies on the anatomy of the lumbar segmental arteries are limited. This prospective cross-sectional study aims to quantitatively describe the brief trajectory of the lumbar segmental arteries on the left side (SegAL) and to discuss its clinical significance.

Methods

One hundred and two asymptomatic volunteers were prospectively enrolled and underwent computed tomography angiography (CTA). Anatomical parameters including the existence rate, relative positions and directions of SegAL were measured. Mann-Whitney U tests were performed, and statistical significance was set at P<0.05.

Results

A total of 404 lumbar SegAL were identified. The SegAL of L1, L2 and L3 were identified in all subjects while the L4 SegAL were absent in 9 of 102 (8.8%) and the L5 SegAL were absent in 97 of 102 (95.1%) volunteers. In 25 of 97 (25.8%) volunteers without the L5 SegAL, the branches of the L4 SegAL ran along the disks. Meanwhile, the branches of L3 intersecting over the intervertebral discs (IVD) were found in 8 of 9 (88.9%) subjects without the L4 SegAL and in 4 of 93 (4.3%) subjects with L4 SegAL. The branch angles between the L1, L2 SegAL and the aorta were significantly acute (P<0.05). The L3 SegAL ran approximately vertically with the aorta while the branch angles of the L4 SegAL were significantly blunt (P<0.05). according to the distances measured, on the anterior vertebral walls, the SegAL of L1 and L2 were significantly closer to the inferior vertebral walls than the SegAL of L3 and L4, while on the posterior vertebral walls, the L3 and L4 SegAL were significantly closer to the inferior walls.

Conclusions

Arterial branches may course over the L3-4 and L4-5 IVD spaces and the branches over the L3-4 disks are more likely to be present when L4 segmental arteries are absent, thus posing potential risks of arterial complications. Because of the SegAL adjacent to the disks, the risk of arterial injury may be higher anteriorly at L1 and L2 and higher posteriorly at L3 and L4.

A Simple Scale for Screening Lower-Extremity Arterial Disease as a Possible Cause of Low Back Pain: a Cross-sectional Study Among 542 Subjects

BACKGROUND

Epidemiological, imaging, and anatomical studies suggest an association between proximal arterial atherosclerosis and development of low back pain (LBP).

OBJECTIVES

We aimed to define (1) the frequency and (2) factors associated with exercise-induced proximal ischemia (EIPI) in individuals with LBP and (3) develop a clinical screening scale.

DESIGN

Monocentric cross-sectional study.

PARTICIPANTS

All patients with history of ongoing LBP referred to our exercise investigation laboratory for exercise transcutaneous oximetry (ex-tcPO₂) between January 2011 and December 2017 (n = 542; mean age, 65.4 ± 10.9; 83.9% men).

MAIN MEASURES

EIPI was defined as a decrease from rest of oxygen pressure (DROP) below - 15 mmHg on the lumbar and/or buttock probes. Ex-tcPO₂ is a reliable validated tool for diagnosing EIPI in comparison with arteriography and computed tomography angiography. Ex-tcPO₂ was performed on a treadmill until symptom manifestation or exhaustion. Clinical data were collected using interview questionnaires, medical file review, and clinical examination.

KEY RESULTS

EIPI was diagnosed in 282 patients (52%). Age ≤ 70 years (OR, 2.22; 95% CI, 1.35-3.57; p = 0.002), a history of proximal revascularization (OR, 2.64; 95% CI, 1.50-4.65; p = 0.001), use of antiplatelet medication (OR, 1.71; 95% CI, 0.96-3.06; p = 0.069), a relationship between exercise and LBP (OR, 2.61; 95% CI, 1.49-4.57; p = 0.001), and an abnormal ankle to brachial index (OR, 2.87; 95% CI, 1.77-4.66; p < 0.0001) were identified as EIPI predictors. Using these items, we developed a screening scale that showed an area under the receiver operating characteristics curve of .756. At a score of ≥ 3, the sensitivity, specificity, and accuracy for EIPI were 84%, 55%, and 71%, respectively.

CONCLUSIONS

EIPI was common among our patients with LBP undergoing ex-TcPO₂. Our screening scale could help better select the patients who require angiography.

Association between parity and lumbar spine degenerative disorders in young women

Introduction: Estrogen helps to maintain the health of collagen-containing tissues including the intervertebral disc. Estrogen deficiency after menopause negatively affects the quality of vertebral end plates and induces development of degenerative disc disease (DDD). However, there is no study examining the relationship between parity and spinal degeneration in young women. The aim of this study was to define the relationship between parity and development of vertebral endplate signal changes and DDD in young premenopausal women.Materials and methods: This case-control case study included 224 patients aged 20-40 years with a history of low back pain for at least 3 months. Pfirrmann's grade, Modic changes (MCs), and Schmorl's nodes (SNs) were graded based on magnetic resonance images. Patients' parity, demographics, body mass index, physical activity level, and disability scores were assessed using a questionnaire.Results: The prevalence of abnormal total Pfirrmann's score (>10) and MCs was higher in primiparous patients than multiparous and grand-multiparous; however, it was not statistically significant. The presence of SN was statistically significantly associated with low parity. According to multivariate logistic regression analysis, it was found that the number of births increases by 1 unit, the abnormality in Pfirrmann's score decreases by 1.36 times.Conclusions: This cross-sectional study shows that parity is associated with DDD and vertebral end plate changes. SNs were significantly associated with parity. Modic changes and DDD were less common in grand multipara and multipara young women than in primipara women. These results indicate that low parity may possibly be associated with the development of spinal degeneration.

Assessment of lumbar disc herniaton using fractional anisotropy in diffusion tensor imaging along with conventional T2-weighted imaging

OBJECTIVE

To assess the usefulness of diffusion tensor imaging and its fractional anisotropy map along with conventional T2-weighted imaging in evaluating the anisotropic water diffusion variations of annulus fibres involved in herniation disc pathology.

MATERIALS AND METHODS

Seventy-five patients with previous medical ethics committee approval and informed consent experiencing low back pain were selected for this prospective randomised blinded trial. Lumbar disc fractional anisotropy maps were obtained acquiring diffusion tensor sequences on a 3T machine. The matrix of nucleus pulposus and structures of annulus fibres were analysed using fractional anisotropy textural features to highlight any presence of lumbar disc herniation. Observer variability and reliability between two neuroradiologists were evaluated. The χ² test, two-tailed t test and linear regression analysis were used to focus differences in patients' demographic data and magnetic resonance imaging findings.

RESULTS

Annular fissures with extrusions were identified using diffusion tensor imaging in 10 out of 17 discs (study group) previously assessed as bulging discs using conventional magnetic resonance imaging. Eighteen extrusions out of 39 (study group) disc levels were identified on diffusion tensor imaging compared to eight extrusions highlighted on T2-weighted imaging (P < 0.01). All eight (study group) disc extrusions evaluated on T2-weighted imaging showed annular fissures on diffusion tensor imaging. Seven out of 14 (study group) protrusions highlighted on T2-weighted imaging had no annular fissures on diffusion tensor imaging; thirty-six disc levels in the control group had no evidence of annular fissures on diffusion tensor imaging (P > 0.01).

CONCLUSIONS

The addition of diffusion tensor imaging sequences and fractional anisotropy mapping to a conventional magnetic resonance imaging protocol could be useful in detecting annular fissures and lumbar disc herniation.

Effect of diminished flow in rabbit lumbar arteries on intervertebral disc matrix changes using MRI T2-mapping and histology

Background

Impaired lumbar artery flow has been reported in clinical and epidemiological studies to be associated with low back pain and lumbar disc degeneration. However, it has not been experimentally demonstrated that impaired lumbar artery flow directly induces intervertebral disc (IVD) degeneration by affecting IVD matrix metabolism. The purpose of this study was to evaluate whether ligation of the lumbar artery can affect degenerative changes in the rabbit IVD.

Methods

New Zealand White rabbits (n = 20) were used in this study. Under general anesthesia, the third and fourth lumbar arteries were double-ligated using vascular clips. The blood flow to the L3/L4 disc (cranial disc) was reduced by ligation of the third lumbar artery and that of the L5/L6 disc (caudal disc) by ligation of the fourth lumbar artery. The blood flow to the L4/L5 disc (bilateral disc) was decreased by ligation of both the third and fourth lumbar arteries. The L2/L3 disc was used as the control. Disc height was radiographically monitored biweekly until 12 weeks after surgery. The rabbits were sacrificed at 4, 8, and 12 weeks after surgery and magnetic resonance imaging (MRI) T2-mapping, histology and immunohistochemistry were assessed.

Results

Lumbar artery ligation did not induce significant changes in disc height between control and ischemic discs (cranial, bilateral and caudal discs) during the 12-week experimental period. T2-values of ischemic discs had no significant trend to be lower than those of the control L2/L3 discs. Histologically, Safranin-O staining changed following ligation of corresponding IVD lumbar arteries. Histological grading scores for disc degeneration, which correlated significantly with MRI T2-values, had significant changes after the surgery. Immunohistochemical analysis showed that the ligation of lumbar arteries significantly affected a change in the percentage of HIF-1α immunoreactive cells of ischemia discs compared to that of control discs four weeks after the surgery (p < 0.05).

Conclusions

The MRI and histology results suggest that diminished flow in lumbar arteries induce mild changes in the extracellular matrix metabolism of rabbit IVDs. These matrix changes, however, were not progressive and differed from the degenerative disc changes seen in the process of human IVD degeneration.

Diffusion based MR measurements correlates with age-related changes in human intervertebral disks

BACKGROUND

Understanding the association between MR parameters and age related deterioration in human intervertebral disks forms an important step in the development of clinical diagnostic protocols for disk disease.

METHODS

Ten unfixed thoracic and lumbar cadaver disk joints, age 37-81 years were imaged at 9.4 T using T2 relaxation (CPMG) and ADC (DWI spin echo) MR protocols. For each MR parameter, spatial maps were computed from the axial images, with the AF and NP segmented based on the T2 maps. Linear regression tested for the correlation between mean and variance (COV) of T2 and ADC with age in the disk, nucleus and annulus, and the effect of thoracic vs. lumbar spine on these correlations.

FINDINGS

In the disk, age negatively correlated with mean ADC (P < 0.001) and positively with COV of ADC (P < 0.001) and T2 (P < 0.05). Age was negatively correlated with mean T2 (P < 0.01), mean ADC (P < 0.001) and positively with COV of ADC (P < 0.001) and T2 (P < 0.05) in the NP and positively correlated with mean T2 (P < 0.05), COV of ADC (P < 0.01) and T2 (P < 0.05) and negatively with mean ADC (P < 0.05) in the AF. Compared to thoracic disks, lumbar disks showed higher mean ADC (P < 0.05), lower mean T2 (P < 0.001) and higher COV of ADC (P < 0.01) and T2 (P < 0.05).

INTERPRETATION

Compared to T2, MR diffusion was a more sensitive measure of age mediated changes in disk tissues. Strong differences in the association of MR parameters with age between the lumbar and thoracic suggest that mechanical environment effects tissue specific MR parameters' association with age.

In vivo correlates between daily physical activity and intervertebral disc health

Physical activity impacts health and disease in multiple body tissues including the intervertebral discs. Fluid flow within the disc is an indicator of disc health that can be observed using diffusion weighted magnetic resonance imaging. We monitored activity levels of 26 participants, age 35-55 yrs, using Actigraph accelerometers for 4 days to evaluate vigorous-intensity activity, moderate to vigorous intensity activity, and sedentary time. Participants underwent structural and diffusion weighted magnetic resonance imaging to evaluate intervertebral disc health and fluid flow. They also underwent bone density scans, carotid artery ultrasounds, a treadmill test, and a physical exam for pain, range of motion, and instability. These measures were used to correlate MRI indicators of intervertebral disc health with participant activity levels. Participants with any vigorous-intensity physical activity compared with no vigorous-intensity activity had significantly greater L5/S1 apparent diffusion coefficient values (p = 0.002), corresponding to higher freedom of diffusive movement for cellular nutrients and metabolic waste. Sagittal T2 values in the L5/S1 were also higher (p = 0.004), corresponding to a higher water content in the discs. Higher apparent diffusion coefficients were also found in participants with more than 30 min compared with less than 30 min of daily moderate to vigorous physical activity (p = 0.03), and in participants with less than 67% awake time as sedentary time compared with more than 67% sedentary time (p = 0.03). Increased dynamic loading through physical activity and decreased static loading from sedentary time benefit intervertebral disc health. Physical activity, particularly vigorous activity, is beneficial in helping maintain intervertebral disc health. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1313-1323, 2018.

Atherosclerotic Disease and its Relationship to Lumbar Degenerative Disk Disease, Facet Arthritis, and Stenosis With Computed Tomography Angiography

BACKGROUND

The intervertebral disk is the largest avascular structure in the body. It relies on passive diffusion from arteries at the periphery of the disk for nutrition. Previous studies have suggested a correlation between vascular disease and lumbar degenerative disk disease (DDD), but the association with facet arthritis and stenosis has not been evaluated.

OBJECTIVE

To evaluate the degree of lumbar artery stenosis, aortic atherosclerosis on computed tomography angiography, and its relationship to lumbar DDD, facet arthritis, and spinal canal stenosis.

DESIGN

Retrospective case review.

SETTING

Academic tertiary care hospital.

PARTICIPANTS

Not applicable.

METHODS

A total of 300 lumbar arteries (150 lumbar artery pairs of the first to fifth lumbar arteries) were evaluated on consecutive computed tomography angiography scans. Severity of vascular disease of lumbar arteries was documented as normal, mild, moderate, severe, or occluded. Aortic vascular disease was documented along the posterior wall where the lumbar arteries originate.

MAIN OUTCOME MEASUREMENTS

The relationship between vascular disease with DDD, facet arthritis, and spinal canal stenosis was examined and further evaluated controlling for age.

RESULTS

Lumbar artery and aortic atherosclerosis had a positive relationship with DDD, facet arthritis, and spinal stenosis that was statistically significant (P < .05) even after controlling for age. The correlation coefficient was greatest in the younger age group when looking at lumbar artery vascular disease with DDD (0.73, confidence interval 0.50-0.96, P < .0001) and aortic vascular disease with DDD (0.72, confidence interval 0.49-0.94, P < .0001). The correlation of vascular disease with facet arthritis and stenosis was not strong in the older age group.

CONCLUSION

Atherosclerotic disease of the lumbar arteries and aorta correlated with lumbar DDD, facet arthritis, and spinal canal stenosis after we adjusted for age, although the correlation with facet arthritis and spinal canal stenosis was not as strong in the older age group.

LEVEL OF EVIDENCE

IV.

Diffusion-Weighted MRI Assessment of Adjacent Disc Degeneration After Thoracolumbar Vertebral Fractures

OBJECTIVE

The purpose of this study was to assess, by the mean apparent diffusion coefficient (ADC), if a relationship exists between disc ADC and MR findings of adjacent disc degeneration after thoracolumbar fractures treated by anatomic reduction using vertebral augmentation (VAP).

MATERIALS AND METHODS

Twenty non-consecutive patients (mean age 50.7 years; range 45-56) treated because of vertebral fractures, were included in this study. There were 10 A3.1 and 10 A1.2 fractures (AO classification). Surgical treatment using VAP was applied in 14 cases, and conservative in 6 patients. MRI T2-weighted images and mapping of apparent diffusion coefficient (ADC) of the intervertebral disc adjacent to the fractured segment were performed after a mean follow-up of 32 months. A total of 60 discs, 3 per patient, were analysed: infra-adjacent, supra-adjacent and a control disc one level above the supra-adjacent.

RESULTS

No differences between patients surgically treated and those following a conservative protocol regarding the average ADC values obtained in the 20 control discs analysed were found. Considering all discs, average ADC in the supra-adjacent level was lower than in the infra-adjacent (1.35 ± 0.12 vs. 1.53 ± 0.06; p < 0.001). Average ADC values of the discs used as a control were similar to those of the infra-adjacent level (1.54 ± 0.06). Compared to surgically treated patients, discs at the supra-adjacent fracture level showed statistically significant lower values in cases treated conservatively (p < 0.001). The variation in the delay of surgery had no influence on the average values of ADC at any of the measured levels.

CONCLUSIONS

ADC measurements of the supra-adjacent discs after a mean follow-up of 32 months following thoracolumbar fractures, showed that restoration of the vertebral collapse by minimally invasive VAP prevents posttraumatic disc degeneration.

MRI DWI/ADC signal predicts shrinkage of lumbar disc herniation after O2-O3 discolysis

PURPOSE

Evaluate the discal morpho-structural changes as a predictive sign in the clinical outcome after ozone therapy in lumbar disc herniation using the T2-shine through effect in diffusion-weighted imaging (DWI).

METHOD

One hundred and fifty-four patients suffering from lumbosciatica (89 men and 65 women; age range, 23-62 years) were included, previous MR study performed with FSE-T2 and T2-fat, SE-T1 and DWI sequences, and were randomly assigned to two groups. Seventy-seven patients (control group) underwent conservative treatment with intraforaminal injection of steroid and anaesthetic. The remaining 77 patients (study group) underwent the same treatment with the addition of oxygen-ozone (O2-O3). During the following six months, a MRI follow-up with the same sequences was performed. An intervertebral disc volumetric analysis (IDVA), DWI signal score and post treatment clinical outcome evaluation were performed for an assessment of hernia reduction. χ² test, Student's t test and analysis of covariance were used for comparison of variables.

RESULTS

In the study group, 58 of 77 patients had a successful outcome (responders). In the responders group, DWI T2-shine through effect was present during MRI follow-up and in particular in 53 of 77 patients in six months of follow-up (p < 0.05). Moreover, in the same group a statistically significant disc shrinkage was shown by IDVA in sixth months of follow-up (p < 0.05).

CONCLUSIONS

T2-shine through effect in DWI is present before morphological disc reduction and moreover could be considered as a predictive sign of response to oxygen-ozone treatment.

Plant-Based Diets for the Prevention and Treatment of Disabling Diseases

Overestimates of the efficacy of surgical and pharmacological interventions for the prevention and treatment of chronic disease and underestimates of the associated risks may bias physicians and patients against lifestyle medicine interventions that can be cheaper, safer, and more effective by treating the underlying cause of disease. The leading causes of both death and disability in the United States are diet, followed by smoking. The food and tobacco industries share similar tactics to downplay and obfuscate the risks associated with their products, but physicians can educate themselves about the role lifestyle interventions can play in the prevention and treatment of chronic disease. For example, a diet centered around whole plant foods can be used to successfully treat angina and painful diabetic neuropathy and may help prevent low-back pain and Alzheimer’s disease, all perhaps because of a common underlying vascular component. The delay between recognizing the risks of smoking and effective public health measures may have cost millions of lives. Similar delays in stopping dietary diseases may cost millions more.

In vivo quantification of lumbar disc degeneration: assessment of ADC value using a degenerative scoring system based on Pfirrmann framework

PURPOSE

To evaluate the role of apparent diffusion coefficient (ADC) as a quantitative means to assess the degree of intervertebral disc (IVD) degeneration contextually within the framework of a widely used Pfirrmann classification rather than in a direct correlation with Pfirrmann grades.

METHODS

DWI and T2-weighted (T2w) of lumbar spine were acquired from nine healthy volunteers (age range 27-62 years, mean age 45 years) with a 3T MR scanner. ADC values were obtained from each of the five lumbar discs via a pixel-by-pixel ADC calculation as well as via region of interest-averaged image intensities. Disc degeneration was assessed by a scoring system via sequential application of Pfirrmann scale and use of intensity ratio of IVD/cerebrospinal fluid in T2w for discs in each Pfirrmann grade to be further separated.

RESULTS

A significant correlation was observed between degenerative scores and ADC independent of how ADC was obtained (Spearman's ρ < -0.85, P < 2 × 10(-14)).

CONCLUSIONS

This study demonstrates that previously perceived as an overlap in ADC value existing between different degenerative categories based on a visual inspection can be viewed as a quantitative role of ADC in assessment of disc degeneration. This reinforces the Pfirrmann classification system but also proceeds beyond mere qualitatively determining morphologic states.

Do abnormal serum lipid levels increase the risk of chronic low back pain? The Nord-Trøndelag Health Study

Background

Cross-sectional studies suggest associations between abnormal lipid levels and prevalence of low back pain (LBP), but it is not known if there is any causal relationship.

Objective

The objective was to determine, in a population-based prospective cohort study, whether there is any relation between levels of total cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides and the probability of experiencing subsequent chronic (LBP), both among individuals with and without LBP at baseline.

Methods

Information was collected in the community-based HUNT 2 (1995–1997) and HUNT 3 (2006–2008) surveys of an entire Norwegian county. Participants were 10,151 women and 8731 men aged 30–69 years, not affected by chronic LBP at baseline, and 3902 women and 2666 men with LBP at baseline. Eleven years later the participants indicated whether they currently suffered from chronic LBP.

Results

Among women without LBP at baseline, HDL cholesterol levels were inversely associated and triglyceride levels positively associated with the risk of chronic LBP at end of follow-up in analyses adjusted for age only. Adjustment for the baseline factors education, work status, physical activity, smoking, blood pressure and in particular BMI largely removed these associations (RR: 0.96, 95% CI: 0.85–1.07 per mmol/l of HDL cholesterol; RR: 1.16, 95% CI: 0.94–1.42 per unit of lg(triglycerides)). Total cholesterol levels showed no associations. In women with LBP at baseline and men without LBP at baseline weaker relationships were observed. In men with LBP at baseline, an inverse association with HDL cholesterol remained after complete adjustment (RR: 0.83, 95% CI: 0.72–0.95 per mmol/l).

Conclusion

Crude associations between lipid levels and risk of subsequent LBP in individuals without current LBP are mainly caused by confounding with body mass. However, an association with low HDL levels may still remain in men who are already affected and possibly experience a higher pain intensity.

Intervertebral disc height loss demonstrates the threshold of major pathological changes during degeneration

PURPOSE

Quantitative MRI techniques were utilized to study intervertebral disc degeneration. Main focus was to develop a novel approach to quantify disc height loss associated with disc degeneration. Currently there is no universally accepted metric of degeneration based on measurement of disc height. Such quantitative imaging methods would complement qualitative visual assessment methods currently used and offer a valuable diagnostic tool.

METHODS

51 adult participants took part in this MRI study. T2 weighted images were used to obtain disc height index (DHI) and also a semi-quantitative metric based on relative voxel intensities. For DHI, each disc was given a score based on standard deviations from the mean DHI of healthy discs. Diffusion Weighted MRI was used to assess morphological changes in the nucleus pulposus. Conventional Pfirrmann classification was used as the gold standard to assess these quantitative approaches.

RESULTS

At deviations of up to 1.5σ below normative disc height, levels of apparent diffusion coefficient (ADC) and normalized T2 intensity were maintained. Once disc compression reached 1.5σ, there was a massive drop in ADC and normalized T2 intensity. Pfirrmann degeneration scores also increased after the 1.5σ mark.

CONCLUSIONS

This study provides new, unbiased quantitative imaging tools to assess disc degeneration. We observed that these quantitative MRI measures indicate a threshold beyond which major pathological changes take place concurrently. Combined information from DHI, ADC and T2 images construct a set of novel biomarkers that could be used to identify degenerating discs that are approaching the threshold and possibly intervene before major pathologic changes occur.

The association between the history of cardiovascular diseases and chronic low back pain in South Koreans: a cross-sectional study

Background

Cardiovascular disease and related risk factors have been suggested as a mechanism leading to atherosclerosis of the lumbar vessels and consequent lumbar pain or sciatica. But there is continued controversy concerning its generalization. This study examined whether cardiovascular disease or its risk factors were associated with chronic low back pain (cLBP) in Koreans.

Methods

Health surveys and examinations were conducted on a nationally representative sample (n = 23,632) of Koreans. A total of 13,841 eligible participants (aged 20 to 89 years) were examined to determine the association between cardiovascular disease, the Framingham risk score, major cardiovascular risk factors (blood pressure, diabetes, cholesterol, and smoking habits) and chronic LBP.

Results

The total prevalence of cLBP was 16.6% (men: 10.8%, women: 21.1%) and that in patients with a history of cardiovascular diseases was 36.6% (men: 26.5%, women: 47.1%). The results showed that patients’ medical history of cardiovascular disease was significantly associated with cLBP in both men and women when adjusted for covariates (men: OR 2.16; 95%CI 1.34∼3.49; women: OR 2.26; 95%CI 1.51∼3.38). No association was observed between cLBP and the Framingham risk score, medication for hyperlipemia, hypertension, diabetes, and major cardiovascular risk factors (systolic blood pressure, total cholesterol, high density lipoprotein cholesterol, triglycerides, glucose and smoking habits) in either men or women.

Conclusions

The prevalence of cLBP is correlated to a history of cardiovascular disease, but not to the major cardiovascular risk factors from the Framingham study. Further studies on whether these results were affected by psychological factors in patients with a history of cardiovascular diseases or whether new potential risk factors from the artery atherosclerosis hypothesis applying to Koreans exist are needed.

Comparison of apparent diffusion coefficient and T2 relaxation time variation patterns in assessment of age and disc level related intervertebral disc changes

PURPOSE

To compare the variation patterns of ADC and T2 values in different age and intervertebral disc (IVD) levels, thus to identify their sensitivities in assessing age and disc level related IVDs changes.

MATERIALS AND METHODS

The T2 and ADC values were recorded from 345 IVDs of 69 volunteers. Kendall's correlation analysis was used to identify the relationship between age and T2/ADC mean values respectively. The one-way analysis of variance (ANOVA) with post hoc analysis was then applied to test the differences of T2 and ADC values among different IVD levels and age groups, followed by linear regression analysis between age (<45 and >45 years) and T2/ADC mean values. This study was approved by the Ethics Committee of the Chinese Academy of Medical Sciences and the Peking Union Medical College Hospital.

RESULTS

Significant negative correlation was observed between age and T2/ADC mean values. The T2 and ADC values showed significant differences among IVD levels and among age groups except for T2 values in age group 1 (25-34 years) and group 2 (35-44 years), and for ADC values at L1-2 level. Both T2 and ADC values showed significant differences between young (age<45 years) and elderly group (age>45 years) at each IVD level. A linear relationship was observed between age and T2/ADC mean values in the elderly group as well as in the young group for the ADC mean values, while no such tendency was identified in the young group for the T2 mean values.

CONCLUSIONS

ADC values may be a more sensitive parameter than T2 in assessing age and disc level related intervertebral disc changes.

MR assessment of lumbar disk herniation treated with oxygen-ozone diskolysis: the role of DWI and related ADC versus intervertebral disk volumetric analysis for detecting treatment response

We prospectively assessed the diagnostic criteria of morphologic MRI study (MMS) and the accuracy of DWI and related ADC values (DWI-ADC) versus intervertebral disk volumetric analysis (IDVA) for predicting shrinkage of lumbar disk herniation treated with oxygen-ozone (O2-O3) diskolysis. Sixty-eight patients (36 men and 32 women; mean age 39) with lumbosciatica underwent O2-O3 diskolysis. The six-month MRI follow-up was performed with FSE-T2 and T2-fat, SE-T1 and DWI-weighted images. IDVA was determined using OsiriX(®). Diagnostic criteria and accuracy were evaluated with regards to DWI and related ADC in detecting response to ozone therapy. Fifty-eight of 68 patients had successful outcomes (responders), whereas ten patients showed unsatisfactory outcomes (non-responders). MMS showed that a centrally located herniated disk and grade 1 nerve root compression were more common in the responder group (p < 0.05). DWI-ADC and IDVA showed statistically significant shrinkage in the sixth month of follow-up (p < 0.05) with a mean ADC value reduction of 2.10 × 10(-3) mm(2)/s +/- 0.19 SD in the second month of follow-up (p < 0.05). DWI-ADC had an accuracy of 0.81 in detecting response to therapy around the second month of follow-up. DWI-ADC appear to be useful adjuncts to MMS in the follow-up of patients undergoing O2-O3 diskolysis.

Prevalence and sex difference of lumbar disc space narrowing in elderly chinese men and women: osteoporotic fractures in men (Hong Kong) and osteoporotic fractures in women (Hong Kong) studies

OBJECTIVE

Osteoporotic Fractures in Men (Hong Kong) and Osteoporotic Fractures in Women (Hong Kong) represent the first large-scale prospective population-based studies on bone health in elderly (age≥65 years) Chinese men (n=2,000) and women (n=2,000). We undertook the current study to investigate the prevalence of lumbar disc space narrowing in these subjects, and to identify the potential relationship between disc space narrowing and sex, bone mineral density (BMD), and other demographic and clinical data.

METHODS

On lumbar lateral radiographs, L1/L2-L4/L5 disc space was classified into 4 categories: 0=normal; 1=mild narrowing; 2=moderate narrowing; 3=severe narrowing. We compared demographic and clinical data between subjects with and those without total disc space narrowing scores≥3.

RESULTS

Disc space narrowing was more common in elderly women than in elderly men. The mean±SD disc space narrowing score for the 4 discs was 2.71±2.21 for men and 3.08±2.50 for women (P<0.0001). For the 3 age groups of 65-69 years, 70-79 years, and ≥80 years, the average disc space narrowing score increased with increasing age in both men and women, and to a greater degree in women than in men. The average disc space narrowing score differences between women and men were 0.12, 0.40, and 0.90, respectively, in the 3 age groups. For both men and women, a disc space narrowing score≥3 was associated with older age, higher spine and hip BMD, low back pain, and restricted leg mobility.

CONCLUSION

The prevalence and severity of disc space narrowing are higher in elderly women than in elderly men. With increasing age, disc space narrowing progresses at a greater rate in women than in men. A disc space narrowing score≥3 is associated with higher spine and hip BMD.

Apparent diffusion coefficient in normal and abnormal pattern of intervertebral lumbar discs: initial experience

The aim of the present study was to compare the relationship of morphologically defined non-bulging/herniated, bulging and herniated intervertebral lumbar discs with quantitative apparent diffusion coefficient (ADC). Thirty-two healthy volunteers and 28 patients with back pain or sciatica were examined by MRI. All intervertebral lumbar discs from L1 to S1 were classified according to morphological abnormality and degenerated grades. The ADC values of nucleus pulposus (NP) were measured and recorded. The significant differences about mean ADC values of NP were found between non-bulging/herniated discs and bulging discs as well as herniated discs (P < 0.05), whereas there were no significant differences in ADC values between bulging and herniated discs (P > 0.05). Moreover, statistically significant relationship was found in the mean ADC values of NP between "non-bulging/herniated and non-degenerated discs" and "non-bulging/herniated degenerated discs" as well as herniated discs (P < 0.05). Linear regression analysis between ADC value and disc level revealed an inverse correlation (r = -0.18). The ADC map of the NP is a potentially useful tool for the quantitative assessment of componential and molecular alterations accompanied with lumbar disc abnormalities.

Assessment of mechanical properties of isolated bovine intervertebral discs from multi-parametric magnetic resonance imaging

BACKGROUND

The treatment planning of spine pathologies requires information on the rigidity and permeability of the intervertebral discs (IVDs). Magnetic resonance imaging (MRI) offers great potential as a sensitive and non-invasive technique for describing the mechanical properties of IVDs. However, the literature reported small correlation coefficients between mechanical properties and MRI parameters. Our hypothesis is that the compressive modulus and the permeability of the IVD can be predicted by a linear combination of MRI parameters.

METHODS

Sixty IVDs were harvested from bovine tails, and randomly separated in four groups (in-situ, digested-6h, digested-18h, digested-24h). Multi-parametric MRI acquisitions were used to quantify the relaxation times T1 and T2, the magnetization transfer ratio MTR, the apparent diffusion coefficient ADC and the fractional anisotropy FA. Unconfined compression, confined compression and direct permeability measurements were performed to quantify the compressive moduli and the hydraulic permeabilities. Differences between groups were evaluated from a one way ANOVA. Multi linear regressions were performed between dependent mechanical properties and independent MRI parameters to verify our hypothesis. A principal component analysis was used to convert the set of possibly correlated variables into a set of linearly uncorrelated variables. Agglomerative Hierarchical Clustering was performed on the 3 principal components.

RESULTS

Multilinear regressions showed that 45 to 80% of the Young's modulus E, the aggregate modulus in absence of deformation HA0, the radial permeability kr and the axial permeability in absence of deformation k0 can be explained by the MRI parameters within both the nucleus pulposus and the annulus pulposus. The principal component analysis reduced our variables to two principal components with a cumulative variability of 52-65%, which increased to 70-82% when considering the third principal component. The dendograms showed a natural division into four clusters for the nucleus pulposus and into three or four clusters for the annulus fibrosus.

CONCLUSIONS

The compressive moduli and the permeabilities of isolated IVDs can be assessed mostly by MT and diffusion sequences. However, the relationships have to be improved with the inclusion of MRI parameters more sensitive to IVD degeneration. Before the use of this technique to quantify the mechanical properties of IVDs in vivo on patients suffering from various diseases, the relationships have to be defined for each degeneration state of the tissue that mimics the pathology. Our MRI protocol associated to principal component analysis and agglomerative hierarchical clustering are promising tools to classify the degenerated intervertebral discs and further find biomarkers and predictive factors of the evolution of the pathologies.

Nutrient transport in human annulus fibrosus is affected by compressive strain and anisotropy

The avascular intervertebral disc (IVD) receives nutrition via transport from surrounding vasculature; poor nutrition is believed to be a main cause of disc degeneration. In this study, we investigated the effects of mechanical deformation and anisotropy on the transport of two important nutrients--oxygen and glucose--in human annulus fibrosus (AF). The diffusivities of oxygen and glucose were measured under three levels of uniaxial confined compression--0, 10, and 20%--and in three directions--axial, circumferential, and radial. The glucose partition coefficient was also measured at three compression levels. Results for glucose and oxygen diffusivity in AF ranged from 4.46 × 10(-7) to 9.77 × 10(-6) cm(2)/s and were comparable to previous studies; the glucose partition coefficient ranged from 0.71 to 0.82 and was also similar to previous results. Transport properties were found to decrease with increasing deformation, likely caused by fluid exudation during tissue compression and reduction in pore size. Furthermore, diffusivity in the radial direction was lower than in the axial or circumferential directions, indicating that nutrient transport in human AF is anisotropic. This behavior is likely a consequence of the layered structure and unique collagen architecture of AF tissue. These findings are important for better understanding nutritional supply in IVD and related disc degeneration.

Dynamic contrast enhanced-magnetic resonance imaging study of the nutrition pathway for lumbar intervertebral disk cartilage of normal goats

OBJECTIVE

Study of the nutrition pathway for lumbar intervertebral disk cartilage of normal goats.

METHODS

Four lumbar intervertebral disks from each of eight 24-month-old goats (32 disks) were studied. After the goats had been anesthetized, signal intensity changes in the regions of interest (ROI) were observed by dynamic contrast enhanced magnetic resonance scanning. Before and after enhancement at the time points of 0, 5, 10, and 30 mins, and 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 hs, the ROI signal intensity was measured, and the time-signal intensity curve and peak times analyzed.

RESULTS

Signal intensity in the vertebral bodies reached a peak at 0 min and decreased quickly thereafter. Signal intensity in the cartilage endplate zones reached the first peak at 30 mins and then went down slightly before increasing to a second peak at 2 hs. Signal intensity in the nuclei pulposus was negative within 5 mins, increased slowly to a peak at 2 hs, and declined thereafter.

CONCLUSION

Nutrient metabolism of the lumbar intervertebral disks of normal goats occurs mainly through the cartilage end-plate pathway.

Assessment of the Correlation between Apparent Diffusion Coefficient and Intervertebral Disk Degeneration Using 3 Tesla MRI

The objective is to use DW-MR imaging using 3 Tesla MRI to assess the correlation between the mean ADC with degenerative disk disease (DDD). We recruited 34 subjects and used DWI-MR to image lumbar intervertebral disks. We acquired a T2W scan and DWIs. The disks were graded for DDD. Assessment of correlation between mean ADC was made. 170 disks were evaluated. The observed sample correlation between mean ADC and disk degeneration was r = 0.65 [0.55-0.73]. The observed sample correlation between mid-sagittal ADC and disk degeneration was r = 0.61 [0.51-0.70]. The differences between mean ADC of each grade were significant, except between grades 4 and 5. There is a correlation of 0.65 between the mean ADC and disk degeneration. This correlation is not strong enough to use the ADC to determine DDD in clinical settings. There was no evident difference in ADC between the studied anatomic lumbar levels.

MR imaging assessment of lumbar intervertebral disk degeneration and age-related changes: apparent diffusion coefficient versus T2 quantitation

BACKGROUND AND PURPOSE

T2 and ADC mappings are 2 quantitative MR imaging tools for assessing IVDD. This study aimed to compare these 2 measures in detecting IVDD and its age-related changes.

MATERIALS AND METHODS

Thirty-seven asymptomatic volunteers and 28 patients with back pain or sciatica were examined, and their lumbar disk T2 and ADC maps were quantified via sagittal imaging protocols at 1.5T. For all participants, the Pfirrmann system was used by 2 radiologists for grading disks. T2 and ADC values in the inner portion of disks were measured, and their variances in different grades were analyzed by 1-way ANOVA testing. The ability of T2 and ADC measures to differentiate IVDD grades was compared on the basis of their ROC curves. For asymptomatic subjects, the correlations between age and the 2 MR imaging measures were assessed by the Pearson 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 among grades I-IV, but not between grades IV and V. There were no significant ADC differences among grades I-III. Moreover, the areas under the 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).

CONCLUSIONS

T2 quantitation provides a more sensitive and robust approach for detecting and characterizing the early stage of IVDD and age-related disk changes.

Diffusion weighted inner volume imaging of lumbar disks based on turbo-STEAM acquisition

A magnetic resonance imaging (MRI) technique for diffusion weighted imaging (DWI) is described which, in contrast to echo planar imaging (EPI), is insensitive to off-resonance effects caused by tissue susceptibility differences, magnetic field inhomogeneities, or chemical shifts. The sequence combines a diffusion weighted (DW) spin-echo preparation and a stimulated echo acquisition mode (STEAM) module. Inner volume imaging (IVI) allows reduced rectangular field-of-view (FoV) in the phase encode direction, while suppressing aliasing artifacts that are usually the consequence of reduced FoVs. Sagittal turbo-STEAM images of the lumbar spine were acquired at 3.0T with 2.0 × 2.0 mm² in-plane resolution and 7 mm slice thickness with acquisition times of 407 ms per image. To calculate the apparent diffusion coefficient (ADC) in lumbar intervertebral disks (IVDs), the DW gradients were applied in three orthogonal gradient directions with b-values of 0 and 300 s/mm². For initial assessment of the ADC of normal and abnormal IVDs a pilot study with 8 subjects was performed. Mean ADC values of all normal IVDs were (2.27±0.40)×10⁻³ mm²/s and (1.89±0.34)×10⁻³ mm²/s for turbo-STEAM IVI and SE-EPI acquisition, respectively. Corresponding mean ADC values, averaged over all abnormal disks, were (1.93±0.39)×10⁻³ mm²/s and (1.51±0.46)×10⁻³ mm²/s, respectively, indicating a substantial ADC decrease (p<0.001).

Effect of pathology type and severity on the distribution of MRI signal intensities within the degenerated nucleus pulposus: application to idiopathic scoliosis and spondylolisthesis

BACKGROUND

Disc degeneration is characterized by a loss of cellularity, degradation of the extracellular matrix, and, as a result, morphological changes and biomechanical alterations. We hypothesized that the distribution of the MR signal intensity within the nucleus zone of the intervertebral disc was modified according to the pathology and the severity of the pathology. The objective of this study was to propose new parameters characterizing the distribution of the signal intensity within the nucleus zone of lumbar intervertebral discs, and to quantify these changes in patients suffering from spondylolisthesis or idiopathic scoliosis.

METHODS

A retrospective study had been performed on T2-weighted MR images of twenty nine patients suffering from spondylolisthesis and/or scoliosis. The high intensity zone of the nucleus pulposus was semi-automatically detected. The distance "DX" between the center weighted by the signal intensity and the geometrical center was quantified. The sum of the signal intensity on the axis perpendicular to the longitudinal axis of the disc was plotted for each position of the longitudinal axis allowing defining the maximum sum "SM" and its position "PSM".

RESULTS

"SM" was clearly higher and "PSM" was more shifted for scoliosis than for spondylolisthesis. A two-way analysis of variance showed that the differences observed on "DX" were not attributed to the pathology nor its severity, the differences observed on "SM" were attributed to the pathology but not to its severity, and the differences observed on "PSM" were attributed to both the pathology and its severity.

CONCLUSIONS

The technique proposed in this study showed significant differences in the distribution of the MR signal intensity within the nucleus zone of intervertebral discs due to the pathology and its severity. The dependence of the "PSM" parameter to the severity of the pathology suggests this parameter as a predictive factor of the pathology progression. This new technique should be useful for the early diagnosis of intervertebral disc pathologies as it highlights abnormal patterns in the MRI signal for low severity of the pathology.

Diffusion-weighted MR imaging in musculoskeletal radiology: applications in trauma, tumors, and inflammation

Diffusion-weighted imaging is a noninvasive magnetic resonance technique that is capable of measuring icroscopic movement of water molecules (ie, random or Brownian motion) within biologic tissues. Diffusion weighting is achieved with a pulsed-field gradient that leaves "static" spins unaffected but causes dephasing of spin ensembles that experience different motion histories according to their diffusion paths, with respect to the direction of the gradient. This article focuses on the interesting opportunities of the use of diffusion weighted imaging in the diagnosis of musculoskeletal diseases, including trauma, tumor, and inflammation.

Intervertebral disk degeneration related to reduced vertebral marrow perfusion at dynamic contrast-enhanced MRI

OBJECTIVE

The purpose of this study was to use dynamic contrast-enhanced MRI to ascertain the relation between intervertebral disk degeneration and lumbar vertebral marrow blood perfusion.

SUBJECTS AND METHODS

We recruited 25 patients (50 vertebral bodies) who underwent dynamic contrast-enhanced MRI of the lumbar spine. The peak signal enhancement of each vertebral body was calculated from the time signal after curve fitting of a pharmacokinetic model. We controlled for other variables that might have affected blood perfusion by assessing two vertebral bodies in each patient. The 25 patients were divided into three groups. In group 1, one of the vertebral bodies (L1 or L3) evaluated was between two adjacent normal disks and the other was between two adjacent degenerated disks. In group 2, each of the two vertebral bodies evaluated was between two normal disks. In group 3 each of the two vertebral bodies evaluated was between two degenerated disks.

RESULTS

Without normalization by minimization of other variables, there were no statistically significant differences in original peak enhancement values among groups 1, 2, and 3 (p = 0.179). After normalization, the peak enhancement in group 1 (0.846 +/- 0.060) was significantly lower than that in group 2 (0.988 +/- 0.047) (p = 0.003) or group 3 (0.973 +/- 0.081) (p = 0.008).

CONCLUSION

After normalization, lumbar vertebral marrow perfusion correlated well with intervertebral disk degeneration evaluated with dynamic contrast-enhanced MRI. Blood perfusion was 14% less in the vertebral body marrow between two degenerated disks than in vertebral marrow between two normal disks.

Association between visual degeneration of intervertebral discs and the apparent diffusion coefficient

The value of apparent diffusion coefficient (ADC) measurements in intervertebral disc has been studied because ADC provides an estimate of free diffusion of unbound water and could be used as a quantitative tool to estimate degenerative changes. However, the challenging nature of diffusion imaging of spine and limited numbers of subjects in earlier studies has produced contradictory findings. We aimed to determine the relation between ADC and visual degenerative changes in lumbar intervertebral discs in a sufficiently large homogeneous study group. Lumbar spines of 228 volunteer middle-aged men were MR imaged at 1.5 T including anatomic and diffusion-weighted imaging. ADC values, T2 signal intensity and height, and width of the three lowest lumbar intervertebral discs were measured and disc degeneration visually graded. The calculated average ADC of 530 measured discs was 2.01 x 10(-3) mm(2)/s+/-0.29 (+/-S.D.). The reduction in ADC between visually normal and moderately degenerated discs was 4%. Severely degenerated discs showed 5% larger ADC values than normal discs, presumably due to free water in cracks and fissures of those discs. T2 signal intensity of the disc was significantly correlated with the ADC values, whereas other measured parameters did not show correlation. There was no evident difference in ADC between the studied anatomic lumbar levels. Because there is considerable overlap between ADC values of normal and degenerated discs, we conclude that ADC measurements of intervertebral discs, at least with current technology, have limited clinical value.

Association of lumbar artery narrowing, degenerative changes in disc and endplate and apparent diffusion in disc on postcontrast enhancement of lumbar intervertebral disc

OBJECTIVE

A decreased supply of nutrition to the intervertebral disc can lead to disc degeneration. Nutrient supply can be simulated in vivo by measuring gadolinium enhancement of the disc. We aimed to study the changes associated with disc degeneration that may have effect on the nutrition of the disc, i.e. lumbar artery narrowing, Modic changes, endplate defects, and apparent diffusion coefficient (ADC) in nucleus pulposus.

PATIENTS AND METHODS

Twenty male volunteers underwent a lumbar spine examination at 1.5 T for anatomical imaging, diffusion weighted imaging, magnetic resonance angiography, and for T1 relaxation time quantification of contrast enhancement of intervertebral disc.

RESULTS

Enhancement of the disc increased with degeneration. Disc space narrowing associated strongly with the enhancement (Pearson's correlation coefficient 0.46, P < 0.001). The enhancement rate in discs adjacent to Modic type 2 changes was 24%, adjacent to type 1/2 changes 58%, and 13% in the absence of Modic changes. Discs adjacent to endplate defects enhanced 32% compared to 10% of normal endplates. Lumbar artery narrowing or ADC in the disc were not associated with the enhancement.

CONCLUSION

Increased enhancement of a degenerated disc is associated mostly with disc space narrowing and with the presence of degenerative endplate changes and endplate defects.

Factors associated with lumbar intervertebral disc degeneration in the elderly

BACKGROUND CONTEXT

Lumbar intervertebral disc degeneration (DD) precedes degenerative diseases of the lumbar spine. Various factors in addition to normal aging are reported to be associated with DD, and recently atherosclerosis and risk factors for cardiovascular diseases (cardiovascular risk factors) have received much attention; however, the links between these risk factors and DD are unclear.

PURPOSE

By correlating magnetic resonance images (MRI) with suspected degenerative disc risk factors such as obesity, cardiovascular risk factors, and atherosclerosis, we hope to clarify the factors associated with DD.

STUDY DESIGN/SETTING

An observational study.

PATIENT SAMPLE

Two hundred seventy adults (51-86 years old) who participated in a health promotion program.

OUTCOME MEASURES

DD evaluated based on the signal intensity of MR T2-weighted mid-sagittal images of the lumbar spine.

METHODS

Age, gender, body mass index (BMI), low-density lipoprotein cholesterol (LDLc), triglyceride (TG), glycosylated hemoglobin (HbA(1c)), brachial-ankle pulse wave velocity (baPWV) as an index of atherosclerosis, osteo-sono-assessment index (OSI) calculated from quantitative ultrasound assessment of the calcaneus as an index of bone mineral density (BMD), history of low back pain (LBP), smoking and drinking habits, and physical loading related to occupations and sports were assessed. The univariate relationships between DD and the variables were evaluated, and finally, odds ratios (OR) and 95% confidence intervals (CI) for the associations of each factor with DD were calculated using logistic regression at each disc level.

RESULTS

Aging correlated significantly with DD of L1/2 (OR, 2.14), L2/3 (OR, 3.56), L3/4 (OR, 2.84), and L4/5 (OR, 3.05); high BMI, with L2/3 (OR, 2.98), L3/4 (OR, 3.58), L4/5 (OR, 2.32), and L5/S1 (OR, 3.34); high LDLc, with L4/5 (OR, 2.65); occupational lifting, with L1/2 (OR, 4.25); and sports activities, with L5/S1 (OR, 3.36).

CONCLUSIONS

Aging, high BMI, high LDLc, occupational lifting, and sports activities are associated with DD. The results of this study raise our index of suspicion that cardiovascular risk factors and particular physical loading may contribute to DD; however additional studies are required to further investigate associations between DD and these factors.

Lumbar degenerative disk disease

The sequelae of disk degeneration are among the leading causes of functional incapacity in both sexes and are a common source of chronic disability in the working years. Disk degeneration involves structural disruption and cell-mediated changes in composition. Mechanical, traumatic, nutritional, and genetic factors all may play a role in the cascade of disk degeneration, albeit to variable degree in different individuals. The presence of degenerative change is by no means an indicator of symptoms, and there is a very high prevalence in asymptomatic individuals. The etiology of pain as the symptom of degenerative disease is complex and appears to be a combination of mechanical deformation and the presence of inflammatory mediators. The role of imaging is to provide accurate morphologic information and influence therapeutic decision making. A necessary component, which connects these two purposes, is accurate natural history data. Understanding the relationship of etiologic factors, the morphologic alterations, which can be characterized with imaging, and the mechanisms of pain production and their interactions in the production of symptoms will require more accurate and reproducible stratification of patient cohorts.

2H double quantum filtered (DQF) NMR spectroscopy of the nucleus pulposus tissues of the intervertebral disc

Deuterium (2H) double-quantum filtered (DQF) NMR spectroscopy of nucleus pulposus (NP) tissues from human intervertebral discs is reported. The DQF spectral intensities, DQ build-up rates, and DQF-detected rotating-frame spin-lattice relaxation times are sensitive to the degree of hydration of the NP tissue, and display a monotonous correlation with age between 15 and 80 years. The implications of this work are that the changes in water dynamics as detected via DQF NMR spectroscopy may be used as a probe of tissue degeneration in NP, particularly in the early stages of degeneration to which most standard NMR methods are not sensitive.

Correlation between diffusion in lumbar intervertebral disks and lumbar artery status: evaluation with fresh blood imaging technique

PURPOSE

To evaluate the correlation of the lumbar artery status with the diffusion values in lumbar vertebral disks in patients with low back problems using a fresh blood imaging (FBI) technique.

MATERIALS AND METHODS

First, both digital subtraction angiography (DSA) and MR angiography (MRA) was performed, and the weighted kappa value between DSA and MR angiography in evaluating the status of lumbar arteries was calculated. Then, The sagittal diffusion-weighted MR images in 260 intervertebral disks (L1-2 to L4-5) and MR angiographic images using FBI technique in the corresponding 260 lumbar artery pairs (total of 520 arteries) of the 65 patients with low back problems were separately evaluated by two radiologists.

RESULTS

The weighted kappa value between DSA and MRA in evaluating the status of lumbar arteries in both observes indicated good agreement. There were significant correlations between the status of lumbar arteries and the ADC values of the lumbar disks in all orthogonal directions (x, y, and z) at all intervertebral levels except L4-5 by both observers (P < 0.001).

CONCLUSION

There is a strong association between the diminished flow in lumbar arteries and the decreased diffusion of lumbar intervertebral disks at all intervertebral levels except at L4-5.

Review of postcontrast MRI studies on diffusion of human lumbar discs

Diffusion is the only source of nutrition to the intervertebral discs, and alteration of diffusion is considered to be the final common pathway for disc degeneration. Yet diffusion remains poorly understood due to the paucity of reliable methods to study diffusion noninvasively in humans in vivo. In recent years, postcontrast MRI has emerged as a powerful and reliable tool for analyzing diffusion in lumbar discs. Since it is noninvasive and safe, it can be used to document the process of diffusion temporally over a period of 24 hours. Well-designed studies have shown that diffusion is a very slow process, and that the endplate is the main structure that controls the process of diffusion. Contrast MRI studies have also made it possible to identify endplate breaks in vivo. In the future this technique may be applied to study the influence of smoking, mechanical loading of the discs, abnormal posture, and atherosclerosis of the lumbar arteries on diffusion. These conditions have all been implicated in disc degeneration through a final common pathway of altered diffusion and decreased nutrition. This review article focuses on the current knowledge, methodology, various factors that influence the diffusion properties of the discs, and future applications of this promising technique.

In vivo quantification of delayed gadolinium enhancement in the nucleus pulposus of human intervertebral disc

PURPOSE

To quantify the delayed contrast agent enhancement in the nucleus pulposus of the intervertebral disc by means by T1 relaxation time measurements, and to correlate the enhancement with visual grading of disc degeneration. Diffusion of nutrients through the endplate is a key factor in tissue viability in the intervertebral disc. It can be simulated in vivo using magnetic resonance imaging (MRI) by measuring delayed gadolinium (Gd) enhancement of the disc.

MATERIALS AND METHODS

Twenty male volunteers underwent a lumbar spine examination at 1.5T. T2-weighted sagittal images were used to score disc degeneration. T1 relaxation times were measured before and 90 minutes after intravenous administration of Gd-DTPA-BMA by applying a series of sagittal single-slice inversion-recovery fast spin-echo (IR-FSE) scans.

RESULTS

A total of 93 discs were analyzed. A statistically significant decrease in the T1 relaxation time of the nucleus pulposus was observed as a result of contrast-agent intake. The percentage change in the T1 relaxation rate for individual discs was up to 126%. A positive trend was observed between the change in the T1 relaxation rate and the grading of disc degeneration.

CONCLUSION

Quantification of delayed enhancement of the intervertebral disc may provide a new means of studying alterations in degenerative disc disease (DDD) that explain the variation in diffusion into the intervertebral disc.

Diffusion weighted MR imaging in acute vertebral compression fractures: differentiation between malignant and benign causes

Aim

The primary objective of this study was to evaluate the specificity and sensitivity of diffusion weighted MR imaging (DWI) in the differentiation and characterisation between benign and malignant vertebral compression fractures compared with conventional T1 WI, T2 WI and fat suppressed contrast enhanced T1 WI in the Malaysian population.

Materials and Methods

Thirty five patients with 68 vertebral compression fractures were imaged using the conventional T1 WI, T2 WI, fat suppressed contrast enhanced T1-weighted, and steady state free precession diffusion-weighted (SSFP DWI) sequences on a 1.5 T MR scanner. Signal intensities were analysed qualitatively for all the sequences by comparison to adjacent normal marrow. A quantitative assessment of the signal intensity in the SSFP DWI was also performed.

Results

T1 WI and T2 WI images are of limited diagnostic value because of the variability in signal intensities. Contrast enhanced images had sensitivity and specificity of 93% and 71%, respectively with a negative predictive value (NPV) of 93%. On diffusion-weighted MR imaging, sensitivity was 87% with specificity of 92%. The positive predicative value (PPV) and NPV were both 90%. The quantitative assessment of ratio revealed a statistical significant difference between the benign (0.96) and the malignant (1.73) group of lesion (Mann-Whitney U-test, p=0.0001).

Conclusions

We found that absence of contrast enhancement has a high NPV (90%) while SSFP DWI has both a high PPV (90%) and high NPV (90%) in detecting malignant vertebral compression fractures. Furthermore, in our study the ratio of lesion intensity technique offers an excellent criterion to differentiate between the benign and malignant lesions, and the presence of iso- or hypointensity of the collapsed vertebral bodies is suggestive of a benign lesion while hyperintensity is highly suggestive of malignancy. We also found that using the NLMR showed a statistical significant difference between the malignant and benign groups (p<0.0001) with osteoporotic and malignant lesions have mean values of 0.96 (SD 0.25) and 1.73 (SD 0.4) respectively.

Assessment of compressive modulus, hydraulic permeability and matrix content of trypsin-treated nucleus pulposus using quantitative MRI

A clinical strength MRI and intact bovine caudal intervertebral discs were used to test the hypotheses that (1) mechanical loading and trypsin treatment induce changes in NMR parameters, mechanical properties and biochemical contents; and (2) mechanical properties are quantitatively related to NMR parameters. MRI acquisitions, confined compression stress-relaxation experiments, and biochemical assays were applied to determine the NMR parameters (relaxation times T1 and T2, magnetization transfer ratio (MTR) and diffusion trace (TrD)), mechanical properties (compressive modulus H(A0) and hydraulic permeability k(0)), and biochemical contents (H(2)O, proteoglycan and total collagen) of nucleus pulposus tissue from bovine caudal discs subjected to one of two injections and one of two mechanical loading conditions. Significant correlations were found between k(0) and T1 (r=0.75,p=0.03), T2 (r=0.78, p=0.02), and TrD (r=0.85, p=0.007). A trend was found between H(A0) and TrD (r=0.56, p=0.12). However, loading decreased these correlations (r=0.4, p=0.2). The significant effect of trypsin treatment on mechanical properties, but not on NMR parameters, may suggest that mechanical properties are more sensitive to the structural changes induced by trypsin treatment. The significant effect of loading on T1 and T2, but not on H(A0) or k(0), may suggest that NMR parameters are more sensitive to the changes in water content enhanced by loading. We conclude that MRI offers promise as a sensitive and non-invasive technique for describing alterations in material properties of intervertebral disc nucleus, and our results demonstrate that the hydraulic permeability correlated more strongly to the quantitative NMR parameters than did the compressive modulus; however, more studies are necessary to more precisely characterize these relationships.

A morphometric study and variations on the lumbar arteries of human fetuses

Lumbar arteries are in series with the posterior intercostal arteries. The aim of this study has been to investigate the morphometric data on the abdominal aorta of the human fetus and define different types of origin variations of the lumbar artery. Initially, the latex solution colored with red ink was injected into the thoracic aorta. The abdominal aorta and its branches were dissected and examined bilaterally in 120 fetuses (ranging between 16 and 32 post-menstrual weeks) and the anatomic variations recorded. Fourteen fetuses with variations were studied and photographed. The origins and morphologic variations of the lumbar arteries were defined and classified. The morphological relationship of the lumbar arteries to the abdominal aorta and the length and width (diameter) of the vessels were investigated by performing measurements using a digital calliper (mm). The frequency and the types of the different variations determined in the present study have been listed. Abdominal aortic branches and Lumbar artery aneurysms are rare lesions with potentially life-threatening consequences and they are difficult to access anatomically and formidable to manage operatively. During the performance of conventional or open surgical replacement of an abdominal aortic aneurysm with prosthetic grafts, the surgeon needs precise knowledge of the anatomy of the abdominal aortic branches and immediate retroperitoneal structures. The variations on the lumbar arteries may have clinical importance. When this region is under diagnostic and/or surgical investigation using computed tomography scan or diagnostic angiography, the possibility of these variations should be take into consideration to avoid complications.