Early intervertebral disc degeneration changes in asymptomatic weightlifters assessed by t1ρ-magnetic resonance imaging

A new perspective on intervertebral disc calcification-from bench to bedside

Disc degeneration primarily contributes to chronic low back and neck pain. Consequently, there is an urgent need to understand the spectrum of disc degeneration phenotypes such as fibrosis, ectopic calcification, herniation, or mixed phenotypes. Amongst these phenotypes, disc calcification is the least studied. Ectopic calcification, by definition, is the pathological mineralization of soft tissues, widely studied in the context of conditions that afflict vasculature, skin, and cartilage. Clinically, disc calcification is associated with poor surgical outcomes and back pain refractory to conservative treatment. It is frequently seen as a consequence of disc aging and progressive degeneration but exhibits unique molecular and morphological characteristics: hypertrophic chondrocyte-like cell differentiation; TNAP, ENPP1, and ANK upregulation; cell death; altered Pi and PPi homeostasis; and local inflammation. Recent studies in mouse models have provided a better understanding of the mechanisms underlying this phenotype. It is essential to recognize that the presentation and nature of mineralization differ between AF, NP, and EP compartments. Moreover, the combination of anatomic location, genetics, and environmental stressors, such as aging or trauma, govern the predisposition to calcification. Lastly, the systemic regulation of calcium and Pi metabolism is less important than the local activity of PPi modulated by the ANK-ENPP1 axis, along with disc cell death and differentiation status. While there is limited understanding of this phenotype, understanding the molecular pathways governing local intervertebral disc calcification may lead to developing disease-modifying drugs and better clinical management of degeneration-related pathologies.

Prevalence of degenerative vertebral disc changes in elite female Crossfit athletes - a cross-sectional study

BACKGROUND

Crossfit athletes consistently recruit or transfer high levels of repetitive forces through the spine, and MRI has documented a higher rate of intervertebral disc degeneration in athletes compared with matched controls. The aim of this study was to evaluate early degenerative spinal disc changes in elite female CrossFit athletes quantified by 3.0 Tesla magnetic resonance imaging (MRI) matched with female none-athletes.

METHODS

In a cross-sectional single-center study 19 asymptomatic adult participants, nine German female elite Crossfit athletes and ten female participants underwent spinal MRI (3.0T). Demographic data, spinal clinical examination results and sport-specific performance parameters were collected prior to the MRI. The primary outcome was the prevalence of degenerative spinal disc changes. The secondary outcome was the grade of degeneration using Pfirrmann grading.

RESULTS

A total of 437 discs underwent spinal MRI (3.0T). The prevalence of early degenerative disc disease was not increased. Pfirrmann degenerative grade did not show significant differences among groups.

CONCLUSION

Asymptomatic female elite Crossfit athletes do not show an increased prevalence of degenerative disc disease. Compared to a sex-matched control group, high training volume in Crossfit does not correlate to a higher incidence of degenerative disc changes in young females.

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.

The burden of low back pain in children and adolescents with overweight and obesity: from pathophysiology to prevention and treatment strategies

Nonspecific low back pain (LBP) is one of the most common causes of disability, affecting all individuals at least once in their lifetime. Such a condition is also becoming increasingly frequent in the pediatric population, especially in children and adolescents with overweight/obesity. Furthermore, new-onset LBP during adolescence has been demonstrated to be a strong predictor of developing LBP later in life, contributing to poorer outcomes and increasing social and medical costs. Several causes and different mechanisms have been considered for the development of LBP in pediatric individuals affected by obesity. For this reason, planning adequate prevention and treatment strategies, mainly through conservative lifestyle changes, would be crucial to anticipate the negative consequences of persisting LBP in adulthood. The aim of this narrative review was to characterize the relationship between LBP and overweight/obesity in the pediatric population, highlighting epidemiological and pathophysiological aspects. In addition, prevention and treatment approaches will be reviewed considering the need to reduce the burden of LBP on this population. According to our search, LBP was more frequent in children and adolescents with overweight and obesity and has been associated with several anthropometric and lifestyle factors, including lumbar hyperlordosis, sedentary habits, physical inactivity, carrying a heavy schoolbag, low vitamin D levels, psychosocial ill-being, and premature intervertebral disc degeneration. Most of these conditions may be addressed with conservative strategies mainly consisting of dietary adjustments, physical exercise, education programs, and physical therapy.

The importance of inflammatory biomarkers in non-specific acute and chronic low back pain: a systematic review

OBJECTIVE

The purpose of this study was to systematically review the evidence on inflammatory biomarkers as analytic predictors of non-specific low back pain (NsLBP). Low back pain (LBP) is the number one cause of disability globally, posing a major health problem that causes an enormous social and economic burden, and there is an increasing interest on the importance of biomarkers in quantifying and even emerge as potential therapeutic tools to LBP.

METHODS

A systematic search was conducted on July 2022 in Cochrane Library, MEDLINE and Web of Science for all the available literature. Cross-sectional, longitudinal cohort or case-control studies that evaluated the relationship between inflammatory biomarkers collected from blood samples and low back pain in humans were considered eligible for inclusion, as well as prospective and retrospective studies.

RESULTS

The systematic database search resulted in a total of 4016 records, of which 15 articles were included for synthesis. Sample size comprised a total of 14,555 patients with LBP (acute LBP (n = 2073); chronic LBP (n = 12482)) and 494 controls. Most studies found a positive correlation between classic pro-inflammatory biomarkers and NsLBP, namely C-reactive protein (CRP), interleukin 1 (IL-1) and IL-1β, interleukin 6 (IL-6) and tumour necrosis factor α (TNF-α). On the other hand, anti-inflammatory biomarker interleukin 10 (IL-10) demonstrated a negative association with NsLBP. Four studies have made direct comparisons between ALBP and CLBP groups regarding their inflammatory biomarkers profile.

CONCLUSIONS

This systematic review found evidence of increased levels of pro-inflammatory biomarkers CRP, IL-6 and TNF-α and decreased levels of anti-inflammatory biomarker IL-10 in patients with LBP. Hs-CRP was not correlated with LBP. There is insufficient evidence to associate these findings with the degree of pain severity or the activity status of the lumbar pain over time.

Single-cell transcriptomics reveals heterogeneity and intercellular crosstalk in human intervertebral disc degeneration

The complexity of the human intervertebral disc (IVD) has hindered the elucidation of the microenvironment and mechanisms underlying IVD degeneration (IVDD). Here we determined the landscapes of nucleus pulposus (NP), annulus fibrosus (AF), and immunocytes in human IVD by scRNA-seq. Six NP subclusters and seven AF subclusters were identified, whose functional differences and distribution during different stages of degeneration (Pfirrmann I-V) were investigated. We found MCAM⁺ progenitor in AF, as well as CD24⁺ progenitor and MKI67⁺ progenitor in NP, forming a lineage trajectory from CD24⁺/MKI67⁺ progenitors to EffectorNP_⅓ during IVDD. There is a significant increase in monocyte/macrophage (Mφ) in degenerated IVDs (p = 0.044), with Mφ-SPP1 exclusively found in IVDD but not healthy IVDs. Further analyses of the intercellular crosstalk network revealed interactions between major subpopulations and changes in the microenvironment during IVDD. Our results elucidated the unique characteristics of IVDD, thereby shedding light on therapeutic strategies.

Interventional Minimally Invasive Treatments for Chronic Low Back Pain Caused by Lumbar Facet Joint Syndrome: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVE

To investigate the efficacy of nonsurgical interventional treatments for chronic low back pain (LBP) caused by facet joint syndrome (FJS).

METHODS

A systematic review of the literature was conducted to identify studies that compared interventional treatments for LBP due to FJS among them, with usual care or sham procedures. Studies were evaluated for pain, physical function, disability, quality of life and employment status. The RoB-2 and MINORS tools were utilized to assess the risk of bias in included studies.

RESULTS

Eighteen studies published between January 2000 and December 2021 were included (1496 patients, mean age: 54.31 years old). Intraarticular (IA) facet joint (FJ) injection of hyaluronic acid (HA) did not show significant difference compared to IA corticosteroids (CCS) in terms of pain and satisfaction. FJ denervation using radiofrequency (RF) displayed slightly superior or similar outcomes compared to IA CCS, physical therapy, or sham procedure. IA CCS showed better outcomes when combined with oral diclofenac compared to IA CCS or oral diclofenac alone but was not superior to IA local anesthetic and Sarapin. IA platelet-rich plasma (PRP) led to an improvement of pain, disability and satisfaction in the long term compared to IA CCS.

CONCLUSION

FJS is a common cause of LBP that can be managed with several different strategies, including nonsurgical minimally invasive approaches such as IA HA, CCS, PRP and FJ denervation. However, available evidence showed mixed results, with overall little short-term or no benefits on pain, disability, and other investigated outcomes.

Comprehensive assessment of in vivo lumbar spine intervertebral discs using a 3D adiabatic T1ρ prepared ultrashort echo time (UTE-Adiab-T1ρ) pulse sequence

BACKGROUND

T_1ρ has been extensively reported as a sensitive biomarker of biochemical changes in the nucleus pulposus (NP) and annulus fibrosis of intervertebral discs (IVDs). However, no T_1ρ study of cartilaginous endplates (CEPs) has yet been reported because the relatively long echo times (TEs) of conventional clinical T_1ρ sequences cannot effectively capture the fast-decaying magnetic resonance signals of CEPs, which have very short T₂/T₂*s. This can be overcome by using ultrashort echo time (UTE) T_1ρ acquisitions.

METHODS

Seventeen subjects underwent UTE with adiabatic T_1ρ preparation (UTE-Adiab-T_1ρ) and T₂-weighted fast spin echo imaging of their lumbar spines. Each IVD was manually segmented into seven regions (i.e., outer anterior annulus fibrosis, inner anterior annulus fibrosis, outer posterior annulus fibrosis, inner posterior annulus fibrosis, superior CEP, inferior CEP, and NP). T_1ρ values of these sub-regions were correlated with IVD modified Pfirrmann grades and subjects' ages. In addition, T_1ρ values were compared in subjects with and without low back pain (LBP).

RESULTS

Correlations of T_1ρ values of the outer posterior annulus fibrosis, superior CEP, inferior CEP, and NP with modified Pfirrmann grades were significant (P<0.05) with R values of 0.51, 0.36, 0.38, and -0.94, respectively. Correlations of T_1ρ values of the outer anterior annulus fibrosis, outer posterior annulus fibrosis, and NP with ages were significant with R equal to 0.52, 0.71, and -0.76, respectively. T_1ρ differences of the outer posterior annulus fibrosis, inferior CEP, and NP between the subjects with and without LBP were significant (P=0.005, 0.020, and 0.000, respectively).

CONCLUSIONS

The UTE-Adiab-T_1ρ sequence can quantify T_1ρ of whole IVDs including CEPs. This is an advance, and of value for comprehensive assessment of IVD degeneration.

Physical Activity for the Treatment of Chronic Low Back Pain in Elderly Patients: A Systematic Review

Chronic low back pain (CLBP) affects nearly 20-25% of the population older than 65 years, and it is currently the main cause of disability both in the developed and developing countries. It is crucial to reach an optimal management of this condition in older patients to improve their quality of life. This review evaluates the effectiveness of physical activity (PA) to improve disability and pain in older people with non-specific CLBP. The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were used to improve the reporting of the review. Individual risk of bias of single studies was assessed using Rob 2 tool and ROBINS-I tool. The quality of evidence assessment was performed using GRADE analysis only in articles that presents full data. The articles were searched in different web portals (Medline, Scopus, CINAHL, EMBASE, and CENTRAL). All the articles reported respect the following inclusion criteria: patients > 65 years old who underwent physical activities for the treatment of CLBP. A total of 12 studies were included: 7 randomized controlled trials (RCT), 3 non-randomized controlled trials (NRCT), 1 pre and post intervention study (PPIS), and 1 case series (CS). The studies showed high heterogeneity in terms of study design, interventions, and outcome variables. In general, post-treatment data showed a trend in the improvement for disability and pain. However, considering the low quality of evidence of the studies, the high risk of bias, the languages limitations, the lack of significant results of some studies, and the lack of literature on this argument, further studies are necessary to improve the evidences on the topic.

Robotic Spine Surgery and Augmented Reality Systems: A State of the Art

Instrumented spine procedures have been performed for decades to treat a wide variety of spinal disorders. New technologies have been employed to obtain a high degree of precision, to minimize risks of damage to neurovascular structures and to diminish harmful exposure of patients and the operative team to ionizing radiations. Robotic spine surgery comprehends 3 major categories: telesurgical robotic systems, robotic-assisted navigation (RAN) and virtual augmented reality (AR) systems, including AR and virtual reality. Telesurgical systems encompass devices that can be operated from a remote command station, allowing to perform surgery via instruments being manipulated by the robot. On the other hand, RAN technologies are characterized by the robotic guidance of surgeon-operated instruments based on real-time imaging. Virtual AR systems are able to show images directly on special visors and screens allowing the surgeon to visualize information about the patient and the procedure (i.e., anatomical landmarks, screw direction and inclination, distance from neurological and vascular structures etc.). The aim of this review is to focus on the current state of the art of robotics and AR in spine surgery and perspectives of these emerging technologies that hold promises for future applications.

MRI-detected spinal disc degenerative changes in athletes participating in the Rio de Janeiro 2016 Summer Olympics games

Objective

To describe the frequency and the distribution of degenerative disc disease (DDD) detected in athletes who underwent spine MRI in the 2016 Summer Olympic Games in Rio de Janeiro.

Methods

Data on spine MRI examinations from the 2016 Summer Olympics were retrospectively analyzed. We assessed the frequency of DDD of the cervical (Cs), thoracic (Ts), and lumbar (Ls) spine using Pfirrmann’s classification. Grade II and III were considered as mild, grade IV as moderate, and grade V as severe disc degeneration. Data were analyzed according to the location of the degenerative disc, type of sport, age-groups, and gender of the athletes.

Results

One hundred out of 11,274 athletes underwent 108 spine MRI’s (21 C, 6 T, and 81 L) (53% Females (F), 47% Males (M)). The frequency of DDD was 40% (42% F, 58% M) over the entire spine (28% mild, 9% moderate and 3% severe). There were 58% (12%F, 88%M) of the cervical spine discs that showed some degree of degeneration (44% mild, 13.5% moderate and 1% severe). Athletics, Boxing, and Swimming were the sports most affected by DDD in the Cs. There were 12.5% of the thoracic discs that showed some degree of degeneration, all were mild DDD and were exclusively seen in female athletes. There were 39% (53% F, 47% M) of the lumbar discs with DDD (26% mild, 9% moderate, and 4% severe).

Conclusion

Athletes who underwent spine MRI during the 2016 Summer Olympic Games show a high frequency of DDD of cervical and lumbar spines. Recognition of these conditions is important to develop training techniques that may minimize the development of degenerative pathology of the spine.

Comparison of MRI cross-sectional area and functions of core muscles among asymptomatic individuals with and without lumbar intervertebral disc degeneration

BACKGROUND

Previous studies suggested that patients with symptomatic intervertebral disc degeneration (IDD) of lumbar spine have reduced cross-sectional area (CSA) and functions of core muscles. However, reduced CSA and functions of core muscles have been observed not only in patients with symptomatic IDD but also in patients with other subgroups of low back pain (LBP). Thus, it is uncertain whether reduced CSA and functions of core muscles lead to IDD and LBP, or pain leads to reduced CSA and functions of core muscles in patients with symptomatic IDD. Therefore, this study aimed to compare the CSA and functions of core muscles between asymptomatic participants with and without IDD in magnetic resonance imaging (MRI).

METHODS

Twenty asymptomatic participants (12 men and 8 women) participated in this study. Ten participants had asymptomatic IDD at L4-5. The others were healthy controls (without IDD at all levels of lumbar spine). The CSA of core muscles was measured using MRI. Maximal isometric trunk flexor strength and side bridge strength were measured by a Smart KEMA strength sensor. Trunk flexor endurance test, side bridge endurance test and plank endurance test were used to measure core endurance. Double legs loading test was used to measure core stability. Mann-Whitney U test was used to compare the differences between two groups.

RESULTS

There were no significant differences in core muscle functions between the two groups (p > 0.05). Moreover, there was no significant difference in CSA between the two groups (p > 0.05).

CONCLUSIONS

There was no significant difference in CSA and core muscle functions between asymptomatic participants with and without IDD. These findings indicate that a degenerative or bulging disc in asymptomatic individuals has little effect on CSA and functions of core muscles, especially in young age. Therefore, the general core endurance test or strength test could not differentiate asymptomatic people with and without IDD of lumbar spine.

TRIAL REGISTRATION NUMBER

Clinical Research information Service. KCT0004061. Registered 13 June 2019. retrospectively registered.

The association between occupational loading and spine degeneration on imaging - a systematic review and meta-analysis

Background

There are inconsistencies in findings regarding the relationship of occupational loading with spinal degeneration or structural damage. Thus, a systematic review was conducted to determine the current state of knowledge on the association of occupational loading and spine degeneration on imaging.

Methods

We performed electronic searches on MEDLINE, CINAHL and EMBASE. We included cross-sectional, case control and cohort studies evaluating occupational loading as the exposure and lumbar spine structural findings on imaging as the outcomes. When possible, results were pooled.

Results

Seventeen studies were included in the review. Ten studies evaluated the association of occupational loading with disc degeneration (signal intensity), four of which were pooled into a meta-analysis. Of the 10 studies, only two did not identify a relationship between occupation loading and disc degeneration. A meta-analysis including four of the studies demonstrated an association between higher loading and degeneration for all spinal levels, with odds ratios between 1.6 and 3.3. Seven studies evaluated disc height narrowing and seven evaluate disc bulge, with six and five identifying an association of loading and with imaging findings respectively. Three studies evaluated modic changes and one identified and association with occupational load.

Conclusions

There was moderate evidence suggesting a modest association between occupational loading and disc degeneration (signal intensity), and low-quality evidence of an association between occupational loading and disc narrowing and bulging.

Lessons learned from intervertebral disc pathophysiology to guide rational design of sequential delivery systems for therapeutic biological factors

Intervertebral disc (IVD) degeneration has been associated with low back pain, which is a major musculoskeletal disorder and socio-economic problem that affects as many as 600 million patients worldwide. Here, we first review the current knowledge of IVD physiology and physiopathological processes in terms of homeostasis regulation and consecutive events that lead to tissue degeneration. Recent progress with IVD restoration by anti-catabolic or pro-anabolic approaches are then analyzed, as are the design of macro-, micro-, and nano-platforms to control the delivery of such therapeutic agents. Finally, we hypothesize that a sequential delivery strategy that i) firstly targets the inflammatory, pro-catabolic microenvironment with release of anti-inflammatory or anti-catabolic cytokines; ii) secondly increases cell density in the less hostile microenvironment by endogenous cell recruitment or exogenous cell injection, and finally iii) enhances cellular synthesis of extracellular matrix with release of pro-anabolic factors, would constitute an innovative yet challenging approach to IVD regeneration.

Incidence rates and characteristics of abnormal lumbar findings and low back pain in child and adolescent weightlifter: A prospective three-year cohort study

Purpose

The purpose of this three-year cohort study was to assess the incidence rates and characteristics of abnormal lumbar findings and low back pain (LBP) in child and adolescent weightlifting athletes using magnetic resonance imaging (MRI) and medical questionnaires. This study evaluated subclinical sports injuries, which in turn may help prevent competition-specific injuries and improve performance levels.

Materials and methods

Between 2014 and 2016, twelve participants who had been competing in weightlifting events for at least 2 years were enrolled in this study. The mean age of the participants at the start of this study was 11.4 ± 2.0 years, and there were 6 boys and 6 girls. Annual medical questionnaire surveys and lumbar examinations using MRI were performed during the 3-year follow-up. The incidence rates and variations of LBP and abnormal MRI findings were evaluated.

Results

At the start of this study, there were no positive findings of LBP, and abnormal lumbar findings on MRI were observed in only 2 participants. At the 2-year follow-up, 1 participant had LBP, and 8 of 12 participants had abnormal lumbar findings. In the final year, only 3 participants had LBP; however, abnormal lumbar findings were observed on MRI in 11 participants. Among these, lumbar spondylolysis was observed in 4 participants, lumbar disc protrusion or extrusion in 2 participants, and lumbar disc degeneration in 9 participants.

Conclusion

This prospective 3-year cohort study of 12 child and adolescent weightlifters revealed abnormal lumbar findings in 11 participants at a high rate on MRI examination. Children and adolescents undergoing resistance training at the competition level could potentially have irreversible changes in the lumbar vertebra without symptoms.

Surgical anatomy, radiological features, and molecular biology of the lumbar intervertebral discs

The intervertebral disc (IVD) is a joint unique in structure and functions. Lying between adjacent vertebrae, it provides both the primary support and the elasticity required for the spine to move stably. Various aspects of the IVD have long been studied by researchers seeking a better understanding of its dynamics, aging, and subsequent disorders. In this article, we review the surgical anatomy, imaging modalities, and molecular biology of the lumbar IVD. Clin. Anat. 30:251-266, 2017. © 2017 Wiley Periodicals, Inc.

Downregulation of miR-27b is Involved in Loss of Type II Collagen by Directly Targeting Matrix Metalloproteinase 13 (MMP13) in Human Intervertebral Disc Degeneration

STUDY DESIGN

A microRNA (miRNA) study.

OBJECTIVE

The purpose of this study was to identify intervertebral disc degeneration (IDD)-specific miRNAs, followed by functional validation of results.

SUMMARY OF BACKGROUND DATA

IDD is the major contributor to back radicular pain, and the molecular mechanisms underlying this disease are not completely understood. Accumulating evidence suggests that miRNAs play an important role in IDD, but the role of specific miRNAs involved in this disease remains elusive.

METHODS

An initial screening of nucleus pulposus (NP) tissues, miRNA expression by miRNA microarray, was performed using samples from 10 patients with degenerative disc disease and 10 patients with lumbar fracture (as controls). Subsequently, differential expression was validated using quantitative reverse transcriptase PCR (qRT-PCR). The level of differentially expressed miRNAs in degenerative NP tissues was investigated, and then functional analysis of the miRNAs in regulating collagen II expression was carried out. Western blotting and luciferase reporter assays were also used to detect the target gene.

RESULTS

We identified 23 miRNAs that were differentially expressed (16 upregulated and 7 downregulated) in patients compared with controls. After qRT-PCR confirmation, miR-27b was significantly downregulated in degenerative NP tissues when compared with controls. Moreover, its level was correlated with grade of disc degeneration. Overexpression of miR-27b promoted type II collagen expression in NP cells. Bioinformatics target prediction identified matrix metalloproteinase 13 (MMP13) as a putative target of miR-27b. Futhermore, luciferase reporter assays demonstrated that miR-27b directly targets MMP13 and affects the protein expression of MMP13 in NP cells. Expression of MMP13 negatively correlated with miR-27b expression in degenerative NP tissues.

CONCLUSION

The downregulation of miR-27b induces type II collagen loss by directly targeting MMP13, leading to the development of IDD. Our study also underscores the potential of miR-27b as a novel therapeutic target in human IDD.

LEVEL OF EVIDENCE

3.

T1ρ magnetic resonance: basic physics principles and applications in knee and intervertebral disc imaging

T1ρ relaxation time provides a new contrast mechanism that differs from T1- and T2-weighted contrast, and is useful to study low-frequency motional processes and chemical exchange in biological tissues. T1ρ imaging can be performed in the forms of T1ρ-weighted image, T1ρ mapping and T1ρ dispersion. T1ρ imaging, particularly at low spin-lock frequency, is sensitive to B0 and B1 inhomogeneity. Various composite spin-lock pulses have been proposed to alleviate the influence of field inhomogeneity so as to reduce the banding-like spin-lock artifacts. T1ρ imaging could be specific absorption rate (SAR) intensive and time consuming. Efforts to address these issues and speed-up data acquisition are being explored to facilitate wider clinical applications. This paper reviews the T1ρ imaging's basic physic principles, as well as its application for cartilage imaging and intervertebral disc imaging. Compared to more established T2 relaxation time, it has been shown that T1ρ provides more sensitive detection of proteoglycan (PG) loss at early stages of cartilage degeneration. T1ρ has also been shown to provide more sensitive evaluation of annulus fibrosis (AF) degeneration of the discs.