Advances in Magnetic Resonance Imaging for the assessment of degenerative disc disease of the lumbar spine

Bilateral Carotid Artery Molecular Calcification Assessed by [18F] Fluoride PET/CT: Correlation with Cardiovascular and Thromboembolic Risk Factors

Atherosclerosis, a leading cause of mortality and morbidity worldwide, involves inflammatory processes that result in plaque formation and calcification. The early detection of the molecular changes underlying these processes is crucial for effective disease management. This study utilized positron emission tomography/computed tomography (PET/CT) with [18F] sodium fluoride (NaF) as a tracer to visualize active calcification and inflammation at the molecular level. Our aim was to investigate the association between cardiovascular risk factors and [18F] NaF uptake in the left and right common carotid arteries (LCC and RCC). A cohort of 102 subjects, comprising both at-risk individuals and healthy controls, underwent [18F] NaF PET/CT imaging. The results revealed significant correlations between [18F] NaF uptake and cardiovascular risk factors such as age (β = 0.005, 95% CI 0.003-0.008, p < 0.01 in LCC and β = 0.006, 95% CI 0.004-0.009, p < 0.01 in RCC), male gender (β = -0.08, 95% CI -0.173--0.002, p = 0.04 in LCC and β = -0.13, 95% CI -0.21--0.06, p < 0.01 in RCC), BMI (β = 0.02, 95% CI 0.01-0.03, p < 0.01 in LCC and β = 0.02, 95% CI 0.01-0.03, p < 0.01 in RCC), fibrinogen (β = 0.006, 95% CI 0.0009-0.01, p = 0.02 in LCC and β = 0.005, 95% CI 0.001-0.01, p = 0.01), HDL cholesterol (β = 0.13, 95% CI 0.04-0.21, p < 0.01 in RCC only), and CRP (β = -0.01, 95% CI -0.02-0.001, p = 0.03 in RCC only). Subjects at risk showed a higher [18F] NaF uptake compared to healthy controls (one-way ANOVA; p = 0.02 in LCC and p = 0.04 in RCC), and uptake increased with estimated cardiovascular risk (one-way ANOVA, p < 0.01 in LCC only). These findings underscore the potential of [18F] NaF PET/CT as a sensitive tool for the early detection of atherosclerotic plaque, assessment of cardiovascular risk, and monitoring of disease progression. Further research is needed to validate the technique's predictive value and its potential impact on clinical outcomes.

In situ forming macroporous biohybrid hydrogel for nucleus pulposus cell delivery

Degenerative intervertebral disc disease is a common source of chronic pain and reduced quality of life in people over the age of 40. While degeneration occurs throughout the disc, it most often initiates in the nucleus pulposus (NP). Minimally invasive delivery of NP cells within hydrogels that can restore and maintain the disc height while regenerating the damaged NP tissue is a promising treatment strategy for this condition. Towards this goal, a biohybrid ABA dimethacrylate triblock copolymer was synthesized, possessing a lower critical solution temperature below 37 °C and which contained as its central block an MMP-degradable peptide flanked by poly(trimethylene carbonate) blocks bearing pendant oligoethylene glycol groups. This triblock prepolymer was used to form macroporous NP cell-laden hydrogels via redox initiated (ammonium persulfate/sodium bisulfite) crosslinking, with or without the inclusion of thiolated chondroitin sulfate. The resulting macroporous hydrogels had water and mechanical properties similar to those of human NP tissue and were mechanically resilient. The hydrogels supported NP cell attachment and growth over 28 days in hypoxic culture. In hydrogels prepared with the triblock copolymer but without the chondroitin sulfate the NP cells were distributed homogeneously throughout in clusters and deposited collagen type II and sulfated glycosaminoglycans but not collagen type I. This hydrogel formulation warrants further investigation as a cell delivery vehicle to regenerate degenerated NP tissue. STATEMENT OF SIGNIFICANCE: The intervertebral disc between the vertebral bones of the spine consists of three regions: a gel-like central nucleus pulposus (NP) within the annulus fibrosis, and bony endplates. Degeneration of the intervertebral disc is a source of chronic pain in the elderly and most commonly initiates in the NP. Replacement of degenerated NP tissue with a NP cell-laden hydrogel is a promising treatment strategy. Herein we demonstrate that a crosslinkable polymer with a lower critical solution temperature below 37 °C can be used to form macroporous hydrogels for this purpose. The hydrogels are capable of supporting NP cells, which deposit collagen II and sulfated glycosaminoglycans, while also possessing mechanical properties matching those of human NP tissue.

Innovative quantitative magnetic resonance tools to detect early intervertebral disc degeneration changes: a systematic review

BACKGROUND CONTEXT

Low back pain (LBP) is the leading cause of disability worldwide, with a tremendous socioeconomic burden. It is mainly caused by intervertebral disc degeneration (IDD), a progressive and age-related process. Due to its ability to accurately characterize intervertebral disc morphology, magnetic resonance imaging (MRI) has been established as one of the most valuable tools in diagnosing IDD. Innovative quantitative MRI (qMRI) techniques able to detect the earliest signs of IDD have been increasingly reported.

PURPOSE

To systematically review available reports on the application of novel qMRI techniques to detect early IDD changes.

STUDY DESIGN

Systematic literature review.

METHODS

A systematic search of PubMed/MEDLINE, Scopus, CINAHL, EMBASE, CENTRAL and Cochrane databases was performed through January 21, 2023. Randomized and nonrandomized studies on innovative qMRI tools able to diagnose early biochemical and architectural IDD changes in patients with or without discogenic LBP were searched. Data on study population, follow-up time (when applicable) and MRI sequence used were recorded. The QUADAS-2 tool was utilized to assess the risk of bias of included studies.

RESULTS

A total of 39 articles published between 2005 and 2022 resulted from the search. All novel qMRI techniques showed an increased capacity to detect early IDD changes thanks to the ability to assess subtle alterations of water content, proteoglycan and glycosaminoglycan concentration, and increased levels of catabolic biomarkers compared to conventional MRI.

CONCLUSIONS

Innovative qMRI techniques have proven effective in identifying premature IDD changes. Further studies are needed to validate their application in wider populations and confirm their applicability in the clinical setting.

Lower effectiveness of facet joint infiltration in patients with concurrent facet joint degeneration and active endplate changes

BACKGROUND CONTEXT

Facet joint degeneration (FJD) and disc degeneration (DD) with associated endplate (EP) changes, specifically Modic 1 changes, might occur concurrently and therefore pose a challenge in the treatment of lower back pain (LBP).

PURPOSE

The aim of the present study was to investigate if the presence of active EP changes (Modic 1) would alter the effect of facet joint infiltrations (FJI) for the treatment of concurrent FJD.

STUDY DESIGN

Prospective cohort study, Level III.

PATIENT SAMPLE

42 patients (Male:20, Female:22) with an average of 58±14 years with FJD on conventional magnetic resonance imaging (MRI) receiving a FJI for treatment of lower back pain were included.

OUTCOME MEASURES

The pain score at baseline, 15 min, 1 day, 1 week and 1 month following FJI as well as the reduction of pain were analyzed. Furthermore, active EP changes on conventional MRI and increased EP metabolic activity on PET/MRI were evaluated and compared.

METHODS

All the patients underwent a (18F)-NaF PET/MRI, conventional MRI and FJI for symptomatic FJD. Active EP changes on conventional MRI and increased EP metabolic activity on PET/MR were analyzed for conformity. The pain score as well as the pain reduction at the above-mentioned time points were compared between patients with and without increased EP metabolic activity in PET/MRI.

RESULTS

The LBP reduction was significantly different between patients with (n=20) and without (n=22) active EP changes at 15 minutes (1.3±2.4 vs. 2.9±2.4, p=.03) and 1 month (0.9±2.3 vs. 2.8±2.9, p<.001) following FJI. The minimal clinically important difference for LBP reduction was reached significantly more often in the absence of active EP changes (73%) compared with patients with active EP changes (35%) 1 month following FJI (p=.03).

CONCLUSIONS

FJI is less effective in LBP reduction of patients with FJD and concurrent active EP changes (eg Modic 1).

Novel Magnetic Resonance Imaging Tools for the Diagnosis of Degenerative Disc Disease: A Narrative Review

Low back pain (LBP) is one of the leading causes of disability worldwide, with a significant socioeconomic burden on healthcare systems. It is mainly caused by degenerative disc disease (DDD), a progressive, chronic, and age-related process. With its capacity to accurately characterize intervertebral disc (IVD) and spinal morphology, magnetic resonance imaging (MRI) has been established as one of the most valuable tools in diagnosing DDD. However, existing technology cannot detect subtle changes in IVD tissue composition and cell metabolism. In this review, we summarized the state of the art regarding innovative quantitative MRI modalities that have shown the capacity to discriminate and quantify changes in matrix composition and integrity, as well as biomechanical changes in the early stages of DDD. Validation and implementation of this new technology in the clinical setting will allow for an early diagnosis of DDD and ideally guide conservative and regenerative treatments that may prevent the progression of the degenerative process rather than intervene at the latest stages of the disease.

Improving Cell Therapy Survival and Anabolism in Harsh Musculoskeletal Disease Environments

Cell therapies are an up and coming technology in orthopedic medicine that has the potential to provide regenerative treatments for musculoskeletal disease. Despite numerous cell therapies showing preclinical success for common musculoskeletal indications of disc degeneration and osteoarthritis, there have been mixed results when testing these therapies in humans during clinical trials. A theory behind the mixed success of these cell therapies is that the harsh microenvironments of the disc and knee they are entering inhibit their anabolism and survival. Therefore, there is much ongoing research looking into how to improve the survival and anabolism of cell therapies within these musculoskeletal disease environments. This includes research into improving cell function under specific microenvironmental conditions known to exist in the intervertebral disc (IVD) and knee environment such as hypoxia, low-nutrient conditions, hyperosmolarity, acidity, and inflammation. This research also includes improving differentiation of cells into desired native cell phenotypes to better enhance their survival and anabolism in the knee and IVD. This review highlights the effects of specific musculoskeletal microenvironmental challenges on cell therapies and what research is being done to overcome these challenges. Impact statement While there has been significant clinical interest in using cell therapies for musculoskeletal pathologies in the knee and intervertebral disc, cell therapy clinical trials have had mixed outcomes. The information presented in this review includes the environmental challenges (i.e., acidic pH, inflammation, hyperosmolarity, hypoxia, and low nutrition) that cell therapies experience in these pathological musculoskeletal environments. This review summarizes studies that describe various approaches to improving the therapeutic capability of cell therapies in these harsh environments. The result is an overview of what approaches can be targeted and/or combined to develop a more consistent cell therapy for musculoskeletal pathologies.

Quantitative Predictive Imaging Biomarkers of Lumbar Intervertebral Disc Degeneration

Study Design

Observational comparative study.

Purpose

To compare fractional anisotropy (FA) maps with T2 values of the nucleus pulposus (NP) and annulus fibrosus (AF) of intervertebral discs in healthy volunteers and patients to develop a predictive disc health scale.

Overview of Literature

T2-weighted magnetic resonance imaging (MRI) is not sensitive to early morphological changes and provides no quantitative biomarker profile for early degeneration.

Methods

We examined 59 healthy controls and 59 patients with back pain by MRI using T2 relaxometry and diffusion tensor imaging (DTI). Each group was divided into three age subgroups: A (<30 years, n=12); B (30-50 years, n=26); and C (>50 years, n=21). We obtained FA values for AF and NP and T2 values for NP for each intervertebral disc. Furthermore, we calculated the FA (AF/NP) ratios.

Results

We categorized 590 intervertebral discs from 118 participants, 566 of which were analyzed with T2 relaxometry and DTI. The T2 values were as follows: subgroup A, 55.8±4.4 ms; B, 48.5±6.9 ms; C, 45.8±8.7 ms (p<0.050). The T2 values for the healthy controls of the subgroups A, B, and C were >120 ms, 90-100 ms, and 70 ms, respectively (p<0.001). Control subgroup A had higher T2 values and AF/NP ratios than subgroups B and C; the AF values were not significantly different. Control subgroup B had higher T2 values and AF/NP ratios than subgroup C but lower FA (NP).

Conclusions

FA maps of the AF/NP ratio and T2 values of NP are potential microstructure biomarkers of normal and degenerating discs and can help detect early degeneration using a predictive disc health score on a continuous scale.

Correlation Between Expression of High Temperature Requirement Serine Protease A1 (HtrA1) in Nucleus Pulposus and T2 Value of Magnetic Resonance Imaging

BACKGROUND Degrading enzymes play an important role in the process of disc degeneration. The objective of this study was to investigate the correlation between the expression of high temperature requirement serine protease A1 (HtrA1) in the nucleus pulposus and the T2 value of the nucleus pulposus region in magnetic resonance imaging (MRI). MATERIAL AND METHODS Thirty-six patients who had undergone surgical excision of the nucleus pulposus were examined by MRI before surgery. Pfirrmann grading of the target intervertebral disc was performed according to the sagittal T2-weighted imaging, and the T2 value of the target nucleus pulposus was measured according to the median sagittal T2 mapping. The correlation between the Pfirrmann grade and the T2 value was analyzed. The expression of HtrA1 in the nucleus pulposus was analyzed by RT-PCR and Western blot. The correlation between the expression of HtrA1 and the T2 value was analyzed. RESULTS The T2 value of the nucleus pulposus region was 33.11-167.91 ms, with an average of 86.64±38.73 ms. According to Spearman correlation analysis, there was a rank correlation between T2 value and Pfirrmann grade (P<0.0001), and the correlation coefficient (rs)=-0.93617. There was a linear correlation between the mRNA level of HtrA1 and T2 value in nucleus pulposus tissues (a=3.88, b=-0.019, F=112.63, P<0.0001), normalized regression coefficient=-0.88. There was a linear correlation between the expression level of HtrA1 protein and the T2 value in the nucleus pulposus tissues (a=3.30, b=-0.016, F=93.15, P<0.0001) and normalized regression coefficient=-0.86. CONCLUSIONS The expression of HtrA1 was strongly related to the T2 value, suggesting that HtrA1 plays an important role in the pathological process of intervertebral disc degeneration.

Using Magnetic Resonance Myelography to Improve Interobserver Agreement in the Evaluation of Lumbar Spinal Canal Stenosis and Root Compression

STUDY DESIGN

Cross-sectional retrospective study designed to assess interobserver agreement.

PURPOSE

To investigate if interobserver agreement using magnetic resonance imaging (MRI) in the evaluation of lumbar spinal canal stenosis and root compression can be improved upon combination with magnetic resonance myelography (MRM).

OVERVIEW OF LITERATURE

The interpretation of lumbar spinal MRI, which is the imaging modality of choice, often has a significant influence on the diagnosis and treatment of low back pain. However, using MRI alone, substantial interobserver variability has been reported in the evaluation of lumbar spinal canal stenosis and nerve root compression.

METHODS

Hardcopies of 30 lumbar spinal MRI (containing a total of 150 disk levels) as well as MRM films were separately reviewed by two radiologists and a neurosurgeon. At each intervertebral disk, the observers were asked to evaluate the thecal sac for the presence and degree of spinal stenoses (mild, moderate, or severe) and presence of root canal compression. Interobserver agreement was measured using weighted kappa statistics.

RESULTS

Regarding lumbar spinal canal stenosis, interobserver agreement between the two radiologists was moderate (kappa, 0.4) for MRI and good (kappa, 0.6) for combination with MRM. However, the agreement between the radiologist and neurosurgeon remained fair for MRI alone or in combination with MRM (kappa, 0.38 and 033, respectively). In the evaluation of nerve root compression, interobserver agreement between the radiologists improved from moderate (kappa, 0.57) for MRI to good (kappa, 0.73) after combination with MRM; moderate agreement between the radiologist and neurosurgeon was noted for both MRI alone and after combination with MRM (kappa, 0.58 and 0.56, respectively).

CONCLUSIONS

Interobserver agreement in the evaluation of lumbar spinal canal stenosis and root compression between the radiologists improved when MRM was combined with MRI, relative to MRI alone.

In-vivo T2-relaxation times of asymptomatic cervical intervertebral discs

Limited research exists on T2-mapping techniques for cervical intervertebral discs and its potential clinical utility. The objective of this research was to investigate the in-vivo T2-relaxation times of cervical discs, including C2-C3 through C7-T1. Ten asymptomatic subjects were imaged using a 3.0 T MR scanner and a sagittal multi-slice multi-echo sequence. Using the mid-sagittal image, intervertebral discs were divided into five regions-of-interest (ROIs), centered along the mid-line of the disc. Average T2 relaxation time values were calculated for each ROI using a mono-exponential fit. Differences in T2 values between disc levels and across ROIs of the same disc were examined. For a given ROI, the results showed a trend of increasing relaxation times moving down the spinal column, particularly in the middle regions (ROIs 2, 3 and 4). The C6-C7 and C7-T1 discs had significantly greater T2 values compared to superior discs (discs between C2 and C6). The results also showed spatial homogeneity of T2 values in the C3-C4, C4-C5, and C5-C6 discs, while C2-C3, C6-C7, and C7-T1 showed significant differences between ROIs. The findings indicate there may be inherent differences in T2-relaxation time properties between different cervical discs. Clinical evaluations utilizing T2-mapping techniques in the cervical spine may need to be level-dependent.

T₁ρ MRI of human musculoskeletal system

Magnetic resonance imaging (MRI) offers the direct visualization of the human musculoskeletal (MSK) system, especially all diarthrodial tissues including cartilage, bone, menisci, ligaments, tendon, hip, synovium, etc. Conventional MRI techniques based on T1 - and T2 -weighted, proton density (PD) contrast are inconclusive in quantifying early biochemically degenerative changes in MSK system in general and articular cartilage in particular. In recent years, quantitative MR parameter mapping techniques have been used to quantify the biochemical changes in articular cartilage, with a special emphasis on evaluating joint injury, cartilage degeneration, and soft tissue repair. In this article we focus on cartilage biochemical composition, basic principles of T1ρ MRI, implementation of T1ρ pulse sequences, biochemical validation, and summarize the potential applications of the T1ρ MRI technique in MSK diseases including osteoarthritis (OA), anterior cruciate ligament (ACL) injury, and knee joint repair. Finally, we also review the potential advantages, challenges, and future prospects of T1ρ MRI for widespread clinical translation.

Comparison of Farfan modified and Frobin methods to evaluate the intervertebral disc height

OBJECTIVE: To evaluate the reliability and reproducibility of Farfan modified and Frobin methods to measure the intervertebral disc height in radiographs with inter- and intraobserver comparison. METHOD: Six radiographs of different patients treated for low back pain have been collected and digitized, and five lumbar disc of each patient were evaluated by six examiners with different levels of experience. The measures were done in Image Pro Plus 6.0 software. RESULTS: When compared, both methods showed more than 95% concordance. In intraexaminer analysis, both also shown to be reliable and reproducible, with a high level of concordance. By comparing the correlation between classes of examiners, the higher the level of experience, the greater the agreement for both methods. CONCLUSION: Farfan modified and Frobin are reliable methods to measure the disc height in the lateral radiographs. The higher level of experience of the examiner, the higher was the correlation between measurements.

Quantitative T2 mapping to characterize the process of intervertebral disc degeneration in a rabbit model

BACKGROUND

To investigate the potential of T2 mapping for characterizing the process of intervertebral disc degeneration (IDD) in a rabbit model.

METHODS

Thirty-five rabbits underwent an annular stab to the L4/5 discs (L5/6 discs served as internal normal controls). Degenerative changes were graded according to the modified Thompson classification and quantified in T2 respectively at pre-operation, 1, 3, 6, 12 and 24 weeks postoperatively. After MRI analysis, expression analysis of aggrecan and type II collagen gene in nucleus pulposus (NP) was performed using real time polymerase chain reaction (real-time PCR). The longitudinal changes in NP T2 and gene expressions were studied by repeated measures and ANOVA, linear regression was performed for their correlations through the process of IDD. The reliability analysis of method of measurement of NP T2 was also performed.

RESULTS

There was a strong inverse correlation between NP T2 and Thompson grades (r = -0.85). The decline of L4/5 NP T2 through 24 weeks was nonlinear, the most significant decrease was observed in 3 weeks postoperatively (P<0.05). The tendency was confirmed at gene expression levels. NP T2 correlated strongly with aggrecan (R² = 0.85, P<0.01) and type II collagen (R² = 0.78, P<0.01) gene expressions. The intraclass correlation coefficients for interobserver and intraobserver reliability were 0.963 and 0.977 respectively.

CONCLUSIONS

NP T2 correlates well with aggrecan and type II collagen gene expressions. T2 mapping could act as a sensitive, noninvasive tool for quantitatively characterizing the process of IDD in longitudinal study, help better understanding of the pathophysiology of IDD, assist us to detect the degenerative cascade, and develop a T2-based quantification scale for evaluation of IDD and efficacy of therapeutic interventions.

Reliable chemical exchange saturation transfer imaging of human lumbar intervertebral discs using reduced-field-of-view turbo spin echo at 3.0 T

The reduced field-of-view (rFOV) turbo-spin-echo (TSE) technique, which effectively suppresses bowel movement artifacts, is developed for the purpose of chemical exchange saturation transfer (CEST) imaging of the intervertebral disc (IVD) in vivo. Attempts to quantify IVD CEST signals in a clinical setting require high reliability and accuracy, which is often compromised in the conventionally used technique. The proposed rFOV TSE CEST method demonstrated significantly superior reproducibility when compared with the conventional technique on healthy volunteers, implying it is a more reliable measurement. Phantom study revealed a linear relation between CEST signal and glycosaminoglycan (GAG) concentration. The feasibility of detecting IVD degeneration was demonstrated on a healthy volunteer, indicating that the proposed method is a promising tool to quantify disc degeneration.

MRI signal distribution within the intervertebral disc as a biomarker of adolescent idiopathic scoliosis and spondylolisthesis

Background

Early stages of scoliosis and spondylolisthesis entail changes in the intervertebral disc (IVD) structure and biochemistry. The current clinical use of MR T2-weighted images is limited to visual inspection. Our hypothesis is that the distribution of the MRI signal intensity within the IVD in T2-weighted images depends on the spinal pathology and on its severity. Therefore, this study aims to develop the AMRSID (analysis of MR signal intensity distribution) method to analyze the 3D distribution of the MR signal intensity within the IVD and to evaluate their sensitivity to scoliosis and spondylolisthesis and their severities.

Methods

This study was realized on 79 adolescents who underwent a MRI acquisition (sagittal T2-weighted images) before their orthopedic or surgical treatment. Five groups were considered: low severity scoliosis (Cobb angle ≤50°), high severity scoliosis (Cobb angles >50°), low severity spondylolisthesis (Meyerding grades I and II), high severity spondylolisthesis (Meyerding grades III, IV and V) and control. The distribution of the MRI signal intensity within the IVD was analyzed using the descriptive statistics of histograms normalized by either cerebrospinal fluid or bone signal intensity, weighted centers and volume ratios. Differences between pathology and severity groups were assessed using one- and two-way ANOVAs.

Results

There were significant (p < 0.05) variations of indices between scoliosis, spondylolithesis and control groups and between low and high severity groups. The cerebrospinal fluid normalization was able to detect differences between healthy and pathologic IVDs whereas the bone normalization, which reflects both bone and IVD health, detected more differences between the severities of these pathologies.

Conclusions

This study proves for the first time that changes in the intervertebral disc, non visible to the naked eye on sagittal T2-weighted MR images of the spine, can be detected from specific indices describing the distribution of the MR signal intensity. Moreover, these indices are able to discriminate between scoliosis and spondylolisthesis and their severities, and provide essential information on the composition and structure of the discs whatever the pathology considered. The AMRSID method may have the potential to complement the current diagnostic tools available in clinics to improve the diagnostic with earlier biomarkers, the prognosis of evolution and the treatment options of scoliosis and spondylolisthesis.

T1ρ magnetic resonance imaging quantification of early lumbar intervertebral disc degeneration in healthy young adults

STUDY DESIGN

Cross-sectional study using T1ρ magnetic resonance imaging (MRI) of lumbar spine in healthy young adults.

OBJECTIVE

To evaluate early intervertebral disc degeneration (IDD) quantified by T1ρ- and T2-weighted MRI in asymptomatic young adults and to correlate T1ρ value with Pfirrmann degenerative grade, sex, and body mass index (BMI).

SUMMARY OF BACKGROUND DATA

Intervertebral disc starts early to degenerate losing proteoglycan content in the nucleus pulposus (NP). A potential tool for the study of early stage of IDD is T1ρ MRI. T1ρ relaxation time of human discs has been correlated to proteoglycan content in previous studies.

METHODS

T1ρ- and T2-weighted images of the lumbar spine were obtained for 63 asymptomatic young subjects (34 men and 29 women; mean age, 22.95 ± 1.8 yr), with a 1.5-T MRI scanner. T1ρ mapping and values in the NP and anulus fibrosus (n = 315) were obtained. Degenerative grade was assessed using T2-weighted images, according to the Pfirrmann scale. Differences in T1ρ value between sexes, BMI, and linear regression analyses with degenerative grade were determined.

RESULTS

T1ρ values of NPs were significantly higher than those of anulus fibrosus at all levels. T1ρ values were significantly lower in women at L3-L4 and L4-L5 discs (P < 0.05). T1ρ values decreased linearly with degenerative grade. However, nondegenerated discs (Pfirrmann grades 1 and 2) showed a wide range of T1ρ relaxation time. No significant correlation was observed between T1ρ value and BMI.

CONCLUSION

The data of this study showed a significant difference in IDD onset between sexes. T1ρ values correlate with Pfirrmann degenerative grade in young adults. However, the wide distribution of T1ρ values in healthy intervertebral disc highlights the low sensitivity of Pfirrmann grade to detect the early IDD changes. T1ρ can be potentially used as a clinical tool to identify early IDD and to create a reliable quantitative scale.

Quantitative analysis of lumbar intervertebral disc abnormalities at 3.0 Tesla: value of T(2) texture features and geometric parameters

T(2) relaxation time mapping provides information about the biochemical status of intervertebral discs. The present study aimed to determine whether texture features extracted from T(2) maps or geometric parameters are sensitive to the presence of abnormalities at the posterior aspect of lumbar intervertebral discs, i.e. bulging and herniation. Thirty-one patients (21 women and 10 men; age range 18-51 years) with low back pain were enrolled. MRI of the lumbar spine at 3.0 Tesla included morphological T(1) - and T(2) -weighted fast spin-echo sequences, and multi-echo spin-echo sequences that were used to construct T(2) maps. On morphological MRI, discs were visually graded into 'normal', 'bulging' or 'herniation'. On T(2) maps, texture analysis (based on the co-occurrence matrix and wavelet transform) and geometry analysis of the discs were performed. The three T(2) texture features and geometric parameters best-suited for distinguishing between normal discs and discs with bulging or herniation were determined using Fisher coefficients. Statistical analysis comprised ANCOVA and post hoc t-tests. Eighty-two discs were classified as 'normal', 49 as 'bulging' and 20 showed 'herniation.' The T(2) texture features Entropy and Difference Variance, and all three pre-selected geometric parameters differed significantly between normal and bulging, normal and herniated, and bulging and herniated discs (p < 0.05). These findings suggest that T(2) texture features and geometric parameters are sensitive to the presence of abnormalities at the posterior aspect of lumbar intervertebral discs, and may thus be useful as quantitative biomarkers that predict disease.

The Fernstrom ball revisited

INTRODUCTION

In 1959, Harmon was the first to implant a vitallium sphere into the intervertebral disc space in order to preserve mobility and maintain disc height in patients with back pain secondary to degenerative disc disease. Fernstrom reported good results after implantation of stainless steel spheres. However, a reduction in disc height frequently occurred secondary to sphere subsidence into the endplates. This often led to revision surgery, and the concept was abandoned.

MATERIALS AND METHODS

We report on four patients who underwent cobalt-chrome sphere implantation, and later presented to us with symptoms that were a direct result of sphere subsidence. All four patients presented with low back pain and/or lower extremity pain, and some with weakness. Imaging demonstrated that all patients had a loss of disc space height with sphere subsidence. Three patients underwent sphere removal, anterior interbody fusion using femoral ring allograft and posterior pedicle or facet screw fixation. In the fourth patient, the sphere was subsided into both the L5 and S1 endplates prohibiting removal. The patient underwent a posterior L5-S1 posterolateral fusion and facet screw fixation. The length of time from sphere implantation to the revision surgery ranges from 8 to 41 months.

RESULTS

Ten months to 3 years after the revision surgery, all four patients reported an improvement in outcome.

CONCLUSION

To the best of our knowledge, this is the first report describing the complications resulting from cobalt chrome sphere implantation and revision strategies for managing the recently resurrected cobalt chrome sphere.

Magnetization transfer ratio mapping of intervertebral disc degeneration

The magnetization transfer ratio of the lumbar discs was spatially quantified from age-matched subjects and the nucleus pulposus magnetization transfer ratio was correlated with T2-weighted Pfirrmann grades. A moderate and significant linear correlation between magnetization transfer ratio and Pfirrmann grades was observed, suggesting that nucleus pulposus collagen relative density increases with degeneration. High-resolution axial magnetization transfer ratio maps revealed elevated magnetization transfer ratio in the nucleus pulposa of injured and heavily degenerated discs. In the injured disc, significant elevation in nucleus pulposa magnetization transfer ratio was not accompanied by significant decrease in disc height. This observation may suggest a possible increase in absolute collagen content, in addition to increased collagen relative density. In summary, magnetization transfer MRI of the disc may serve as a noninvasive diagnostic tool for disc degeneration, in addition to other MRI techniques specific to proteoglycan content.

In vitro evaluation of a manganese chloride phantom-based MRI technique for quantitative determination of lumbar intervertebral disc composition and condition

The application of MRI as a non-invasive, quantitative tool for diagnosing lumbar intervertebral disc degeneration is currently an area of active research. The objective of this study was to examine, in vitro, the efficacy of a manganese chloride phantom-based MRI technique for quantitatively assessing lumbar disc composition and degenerative condition. Sixteen human lumbar discs were imaged ex vivo using T2-weighted MRI, and assigned a quantitative grade based on the relative signal intensities of nine phantoms containing serial concentrations of manganese chloride. Discs were then graded macroscopically for degenerative condition, and water and uronic acid (glycosaminoglycan) contents were determined. MRI ranking exhibited significant and strong negative correlation with nucleus pulposus uronic acid content (r = -0.78). MRI grades were significantly higher for degenerate discs. The technique described presents immediate potential for in vitro studies requiring robust, minimally invasive and quantitative determination of lumbar disc composition and condition. Additionally, the technique may have potential as a clinical tool for diagnosing lumbar disc degeneration as it provides a standardised series of reference phantoms facilitating cross-platform consistency, requires short scan times and simple T2-weighted signal intensity measurements.

Correlação entre as classificações de Pfirrmann e Modic na degeneração do disco intervertebral lombar

OBJETIVO: correlacionar as alterações encontradas nas ressonâncias magnéticas lombares quanto às classificações de Pfirrmann e Modic. MÉTODOS: foram selecionadas 54 ressonâncias lombossacras de pacientes ambulatoriais (23 homens e 31 mulheres) que já se encontravam em investigação por sua comorbidade. Foram classificados 264 discos intervertebrais (L1 a S1) quanto ao grau de degeneração segundo Pfirrmann. A presença de alterações de sinal de corpo vertebral foi registrada quanto à classificação de Modic. Foi aplicado teste χ2, adotando níveis de significância inferiores a 0,05 (a=5%). RESULTADOS: a média de idade pesquisada foi de 48,4 anos (26 a 77 anos). Observou-se maior prevalência de Pfirrmann tipo IV (31,1%). Em 88,3% da amostra o sinal de Modic estava ausente, assim como Modic 3; 60% das alterações Modic 2 foram relacionadas ao Pfirrmann tipo V, e 36,4% das alterações Modic 1 foram igualmente distribuídas entre Pfirrmann tipo IV e V. Encontrou-se associação estatisticamente significante entre as alterações de Modic e de Pfirrmann (p<0,001). CONCLUSÃO: houve uma clara associação entre as classificações estudadas ao se comparar os estágios mais avançados de Pfirrmann (IV e V) com Modic tipo 1 e 2.

In vivo 3.0-tesla magnetic resonance T1rho and T2 relaxation mapping in subjects with intervertebral disc degeneration and clinical symptoms

The purpose of this study is (1) to determine the correlation between T(1rho) and T(2) and degenerative grade in intervertebral discs using in vivo 3.0-T MRI, and (2) to determine the association between T(1rho) and T(2) and clinical findings as quantified by the SF-36 Questionnaire and Oswestry Disability Index. Sixteen subjects participated in this study, and each completed SF-36 and Oswestry Disability Index questionnaires. MRI T(1rho) and T(2) mapping was performed to determine T(1rho) (77 discs) and T(2) (44 discs) in the nucleus of the intervertebral disc, and T(2)-weighted images were acquired for Pfirrmann grading of disc degeneration. Pfirrmann grade was correlated with both T(1rho) (r = -0.84; P < 0.01) and T(2) (r = -0.61; P < 0.01). Mixed-effects models demonstrate that only T(1rho) was associated with clinical questionnaires (R(2) (SF-36) = 0.55, R(2) (O.D.I.) = 0.56; P < 0.05). Although the averaged values of T(1rho) and T(2) were significantly correlated, they presented differences in spatial distribution and dynamic range, thus suggesting different sensitivities to tissue composition. This study suggests that T(1rho) may be sensitive to early degenerative changes (corroborating previous studies) and clinical symptoms in intervertebral disc degeneration.

Measurement of intervertebral disc pressure with T 1ρ MRI

The aim of this study is to demonstrate T(1ρ) MRI's capability for measuring intervertebral disc osmotic pressure. Self-coregistered sodium and T(1ρ) -weighted MR images were acquired on ex vivo bovine intervertebral discs (N = 12) on a 3 T clinical MRI scanner. The sodium MR images were used to calculate effective nucleus pulposus fixed-charge-density (mean = 138.2 ± 27.6 mM) and subsequently osmotic pressure (mean = 0.53 ± 0.18 atm), whereas the T(1ρ) -weighted images were used to compute T(1ρ) relaxation maps. A significant linear correlation (R = 0.56, P < 0.01) between nucleus pulposus fixed-charge-density and T(1ρ) relaxation time constant was observed. More importantly, a significant power correlation (R = 0.72, P < 0.01) between nucleus pulposus osmotic pressure as predicted by sodium MRI and T(1ρ) relaxation time constant was also observed. The current clinical method for assessing disc pressure is discography, which is an invasive procedure that has been shown to have negative effects on disc biomechanical and biochemical properties. In contrast, T(1ρ) MRI is noninvasive and can be easily implemented in a clinical setting due to its superior signal-to-noise ratio compared with sodium MRI. Therefore, T(1ρ) MRI may serve as a noninvasive clinical tool for the longitudinal evaluation of disc osmotic pressure.