New treatments and imaging strategies in degenerative disease of the intervertebral disks

Seeing the unseen: The role of bioimaging techniques for the diagnostic interventions in intervertebral disc degeneration

Intervertebral Disc Degeneration is a pathophysiological condition that primarily affects the spinal discs, causing back pain and neurological deficits. It is caused by the contribution of several factors such as genetic predisposition, age-related degeneration, and lifestyle choices like obesity and physical activity. Even though there are medications to treat pain, there is a lack of medicines for a complete cure. The main difficulty lies in poor diagnosis of the morphological and functional changes in the disc. With the ever-increasing research on bioimaging techniques, new techniques are being developed and repurposed to evaluate disc shape and composition, and their defects like thinning or deformities on the disc, leading to the proper diagnostic intervention in intervertebral disc degeneration. In this review, we aim to present a comprehensive overview of the imaging techniques used in the pre-clinical and clinical stages for the diagnosis of intervertebral disc degeneration. First, we will discuss about patho-anatomy and the pathophysiology of degenerative disc disease with the significance and a brief description of various dyes and tracers utilized for bioimaging. Then we will shed light on the latest advancements in diagnostic modalities in intervertebral disc degeneration; concluded by an analysis of the repercussions of the methodologies and experimental systems employed in identifying mechanisms and developing therapeutic strategies in intervertebral disc degeneration.

Deep Learning Assisted Classification of T1ρ-MR Based Intervertebral Disc Degeneration Phases

BACKGROUND

According to the T1ρ value of nucleus pulposus, our previous study has found that intervertebral disc degeneration (IDD) can be divided into three phases based on T1ρ-MR, which is helpful for the selection of biomaterial treatment timing. However, the routine MR sequences for patients with IDD are T1- and T2-MR, T1ρ-MR is not commonly used due to long scanning time and extra expenses, which limits the application of T1ρ-MR based IDD phases.

PURPOSE

To build a deep learning model to achieve the classification of T1ρ-MR based IDD phases from routine T1-MR images.

STUDY TYPE

Retrospective.

POPULATION

Sixty (M/F: 35/25) patients with low back pain or lower limb radiculopathy are randomly divided into training (N = 50) and test (N = 10) sets.

FIELD STRENGTH/SEQUENCES

1.5 T MR scanner; T1-, T2-, and T1ρ-MR sequence (spin echo).

ASSESSMENT

The T1ρ values of the nucleus pulposus in intervertebral discs (IVDs) were measured. IVDs were divided into three phases based on the mean T1ρ value: pre-degeneration phase (mean T1ρ value >110 msec), rapid degeneration phase (mean T1ρ value: 80-110 msec), and late degeneration phase (mean T1ρ value <80 msec). After measurement, the T1ρ values, phases, and levels of IVDs were input into the model as labels.

STATISTICAL TESTS

Intraclass correlation coefficient, area under the receiver operating characteristic curve (AUC), F1-score, accuracy, precision, and recall (P < 0.05 was considered significant).

RESULTS

In the test dataset, the model achieved a mean average precision of 0.996 for detecting IVD levels. The diagnostic accuracy of the T1ρ-MR based IDD phases was 0.840 and the AUC was 0.871, the average AUC of 5-folds cross validation was 0.843.

DATA CONCLUSION

The proposed deep learning model achieved the classification of T1ρ-MR based IDD phases from routine T1-MR images, which may provide a method to facilitate the application of T1ρ-MR in IDD.

EVIDENCE LEVEL

4 TECHNICAL EFFICACY: Stage 2.

Three Stages on Magnetic Resonance Imaging of Lumbar Degenerative Spine

PURPOSES

To propose a new lumbar degenerative staging system using the current radiological classification system.

METHODS

A cross-sectional analysis of retrospective databases between January 2018 and December 2022 was performed. Total of 410 patients for Modic changes, paravertebral muscle fat infiltration, disc degeneration, articular process degeneration, vertebral endplate degeneration and other structures, and disc displacement, Spondylolisthesis, and stenosis, and grouped patients according to stage were assessed. Visual analog scale, Japanese Orthopaedic Association, and Oswestry Disability Index scores were used to assess low back pain strength, neurological function, and quality of life, respectively.

RESULTS

The lumbar degeneration staging system consists of 8 variables, which can be divided into 3 steps: early, middle and late, and the correlation between each variable is strong (P < 0.05). The later the staging, the worse the Japanese Orthopaedic Association, visual analog scale, and Oswestry Disability Index scores.

CONCLUSIONS

Patients with later stages have worse clinical scores. This staging system recommends a uniform classification to assess lumbar degeneration.

Perspective on Intradiscal Therapies for Lumbar Discogenic Pain: State of the Science, Knowledge Gaps, and Imperatives for Clinical Adoption

Specific clinical diagnostic criteria have established a consensus for defining patients with lumbar discogenic pain. However, if conservative medical management fails, these patients have few treatment options short of surgery involving discectomy often coupled with fusion or arthroplasty. There is a rapidly-emerging research effort to fill this treatment gap with intradiscal therapies that can be delivered minimally-invasively via fluoroscopically guided injection without altering the normal anatomy of the affected vertebral motion segment. Viable candidate products to date have included mesenchymal stromal cells, platelet-rich plasma, nucleus pulposus structural allograft, and other cell-based compositions. The objective of these products is to repair, supplement, and restore the damaged intervertebral disc as well as retard further degeneration. In doing so, the intervention is meant to eliminate the source of discogenic pain and avoid surgery. Methodologically rigorous studies are rare, however, and based on the best clinical evidence, the safety as well as the magnitude and duration of clinical efficacy remain difficult to estimate. Further, we summarize the US Food and Drug Administration's (FDA) guidance regarding the interpretation of the minimal manipulation and homologous use criteria, which is central to designating these products as a tissue or as a drug/device/biologic. We also provide perspectives on the core evidence and knowledge gaps associated with intradiscal therapies, propose imperatives for evaluating effectiveness of these treatments and highlight several new technologies on the horizon.

Effect of spinal-pelvic sagittal balance on the clinical outcomes after lumbar fusion surgery

BACKGROUND

Spinal-pelvic sagittal balance is important for maintaining energy-efficient posture in normal and diseased states.Few reports to date have evaluated the effect of spinal-pelvic sagittal balance on clinical outcomes after lumbar interbody fusion in patients with lumbar degenerative diseases (LDD).

METHODS

A total of 303 patients treated with posterior lumbar interbody fusion surgery for lumbar degenerative disease from January 2012 to December 2019 were enrolled in this retrospective study according to the inclusion criteria. Preoperative and postoperative spinal-pelvic sagittal parameters including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) and lumbar lordosis (LL) of the patients were evaluated and compared. 163 patients whose postoperative PI-LL ≤ 10° were divided into the spinal-pelvic match group (Group M), while 140 patients were divided into the spinal-pelvic mismatch group (Group MM). Preoperative and postoperative Oswestry Disability Index (ODI) and Visual Analog Scale (VAS) for back pain of both groups were compared.

RESULTS

There was no significant difference between the two groups in demographic and surgical data, except for blood loss in surgery. LL, PI, PT and SS of the patients at final follow-up were all statistically different from the preoperative values in the two groups(P < 0.05). There was no significant difference in LL, PI, PT and SS between the two groups before surgery. At the final follow-up, LL, PI and PT differed significantly between the two groups(P < 0.05). Compared with the preoperative results, ODI and VAS of low back in both groups decreased significantly at the final follow-up (P < 0.05). Significant differences in VAS and ODI were found between the two groups at the final follow-up (P < 0.05). The improvement rates of VAS and ODI of Group M are both significantly higher than Group MM. Regression analysis showed that age and spinal-pelvic match had significant effects on the improvement of patients' low back pain at the final follow-up.

CONCLUSIONS

lumbar interbody fusion can significantly improve the prognosis of patients with LDD. In terms of outcomes with an average follow-up time of more than 2 years, the spinal-pelvic match has a positive effect on patients' quality of life and the release of low back pain.

Degenerative Lumbar Spine Disease: Imaging and Biomechanics

Chronic low back pain (CLBP) is one of the most common diagnoses encountered when considering years lived with disability. The degenerative changes of the lumbar spine include a wide spectrum of morphological modifications visible on imaging, some of them often asymptomatic or not consistent with symptoms. Phenotyping by considering both clinical and imaging biomarkers can improve the management of CLBP. Depending on the clinical presentation, imaging helps determine the most likely anatomical nociceptive source, thereby enhancing the therapeutic approach by targeting a specific lesion. Three pathologic conditions with an approach based on our experience can be described: (1) pure painful syndromes related to single nociceptive sources (e.g., disk pain, active disk pain, and facet joint osteoarthritis pain), (2) multifactorial painful syndromes, representing a combination of several nociceptive sources (such as lumbar spinal stenosis pain, foraminal stenosis pain, and instability pain), and (3) nonspecific CLBP, often explained by postural (muscular) syndromes.

Lumbar Intervertebral Disc and Discovertebral Segment, Part 1: An Imaging Review of Normal Anatomy

The intervertebral disc is designated the most important cartilaginous articulation of the vertebral column that functions to withstand compressive biomechanical forces and confer strength and flexibility to the spine. A thorough study of the complex fine structure and anatomic relationships of the intervertebral disc is essential for the characterization of the integrity of each individual structure in the discovertebral segment. This elaborate work in human cadavers explores the sophisticated internal structure of the normal intervertebral disc and the discovertebral segment, providing detailed data derived from the dissection of specimens through imaging and close anatomic-histologic correlation. Familiarity with the normal appearances and basic functional properties of the lumbar intervertebral disc and discovertebral segment is fundamental for the recognition of aberrations that may have important clinical implications in patients with low back pain. In Part I of this article, the anatomic structure and features of the discovertebral complex in adults will be described.

Multi-scanner and multi-modal lumbar vertebral body and intervertebral disc segmentation database

Magnetic resonance imaging (MRI) is widely utilized for diagnosing and monitoring of spinal disorders. For a number of applications, particularly those related to quantitative MRI, an essential step towards achieving reliable and objective measurements is the segmentation of the examined structures. Performed manually, such process is time-consuming and prone to errors, posing a bottleneck to its clinical applicability. A more efficient analysis would be achieved by automating a segmentation process. However, routine spine MRI acquisitions pose several challenges for achieving robust and accurate segmentations, due to varying MRI acquisition characteristics occurring in data acquired from different sites. Moreover, heterogeneous annotated datasets, collected from multiple scanners with different pulse sequence protocols, are limited. Thus, we present a manually segmented lumbar spine MRI database containing a wide range of data obtained from multiple scanners and pulse sequences, with segmentations of lumbar vertebral bodies and intervertebral discs. The database is intended for the use in developing and testing of automated lumbar spine segmentation algorithms in multi-domain scenarios.

Measurement(s)	Vertebral Body • Intervertebral Disc
Technology Type(s)	Magnetic Resonance Imaging

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.

Effects of different pedicle screw insertion depths on sagittal balance of lumbar degenerative spondylolisthesis, a retrospective comparative study

BACKGROUND

Few reports to date have evaluated the effects of different pedicle screw insertion depths on sagittal balance and prognosis after posterior lumbar interbody and fusion (PLIF) in patients with lumbar degenerative spondylolisthesis (LDS).

METHODS

A total of 88 patients with single-level PLIF for LDS from January 2018 to December 2019 were enrolled. Long screw group (Group L): 52 patients underwent long pedicle screw fixation (the leading edge of the screw exceeded 80% of the anteroposterior diameter of vertebral body). Short screw group (Group S): 36 patients underwent short pedicle screw fixation (the leading edge of the screw was less than 60% of the anteroposterior diameter of vertebral body). Local deformity parameters of spondylolisthesis including slip degree (SD) and segment lordosis (SL), spino-pelvic sagittal plane parameters including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS) and lumbar lordosis (LL), Oswestry Disability Index (ODI), and Visual Analog Scale (VAS) for back pain of both groups were compared. Postoperative complications, including vertebral fusion rate and screw loosening rate, were recorded.

RESULTS

Except that PI in Group S at the final follow-up was not statistically different from the preoperative value (P > 0.05), other parameters were significantly improved compared with preoperative values one month after surgery and at the final follow-up (P < 0.05). There was no significant difference in parameters between Group L and Group S before and one month after surgery (P > 0.05). At the final follow-up, SD, SL, LL, PT and PI-LL differed significantly between the two groups (P < 0.05). Compared with the preoperative results, ODI and VAS in both groups decreased significantly one month after surgery and at the final follow-up (P < 0.05). Significant differences of ODI and VAS were found between the two groups at the final follow-up (P < 0.05). Postoperative complications were not statistically significant between the two groups (P > 0.05).

CONCLUSIONS

PLIF can significantly improve the prognosis of patients with LDS. In terms of outcomes with an average follow-up time of 2 years, the deeper the screw depth is within the safe range, the better the spino-pelvic sagittal balance may be restored and the better the quality of life may be.

Association between spinal alignment and biochemical composition of lumbar intervertebral discs assessed by quantitative magnetic resonance imaging

Background

To evaluate potential associations between spinopelvic parameters and the biochemical composition of lumbar intervertebral discs using quantitative magnetic resonance imaging in asymptomatic young adults.

Methods

Our study group comprised 93 asymptomatic volunteers aged 20-40 years (49 women and 44 men). Lumbar spine T2-weighted images and T2 relaxometry were acquired on a 1.5T MRI scanner. Spinopelvic parameters including sacral slope, pelvic tilt, pelvic incidence, lumbar lordosis, thoracic kyphosis, thoracolumbar alignment, sagittal vertical axis, spinosacral angle, C2 pelvic angle, and T1S1 and L1S1 length were measured on panoramic spine radiographs.

Results

Lumbar lordosis decrease correlates with discrete dehydration of nucleus pulposus at all lumbar levels. Also low values of sacral slope, pelvic tilt, pelvic incidence, thoracic kyphosis and spinosacral angle were associated with decrease of T2 relaxation times on annulus fibrosus.

Conclusions

In conclusion, spinopelvic parameters presented a discrete association with lumbar disc composition and water content.

Characterization of microenvironmental changes in the intervertebral discs of patients with chronic low back pain using multiparametric MRI contrasts extracted from Z-spectrum

PURPOSE

Z-spectral MRI data were analyzed to produce multiparametric metabolic and microenvironmental contrasts for identifying intervertebral discs with/without pain symptom and sore pain.

METHODS

Z-spectra data were collected from the lumbar discs of 26 patients with non-specific chronic low bck pain (CLBP) and 21 asymptomatic controls (AC) with a chemical exchange saturation transfer (CEST). Data were fitted to quantify the CEST effects from glycosaminoglycan, amide proton transfer (APT), nuclear Overhauser enhancement (NOE), semi-solid magnetization transfer contrast effects, and the direct saturation of water. Multiparametric maps were computed from the fitted peak amplitudes, and the average values were calculated from all five lumber discs. Those parameters were compared between the CLBP and AC groups and between the subgroups with and without (Nsore) sore pain.

RESULTS

The discs in symptomatic patients have lower water content, collagen-bound water and collagen than the discs in AC (P < 0.05). Additionally, Z-sepctral MRI indicated that the discs in the sore subgroup had less water, collagen-bound water and collagen, and likely lower pH compared to the Nsore subgroup (P < 0.05). Lower pH as measured with reduced APT and NOE effects may be an important pathological factor causing sore pain of the back.

CONCLUSION

Z-spectral MRI with its multiparametric metabolic and microenvironmental contrasts has been demonstrated to identify discs with and without pain symptom or sore pain, providing more important information of CLBP.

Preoperative imaging of spinopelvic pathologies : State of the art

The field of musculoskeletal diagnostics and personalized medicine has undergone a revolutionary transformation due to a deeper understanding of skeletal biomechanics and due to technological advancements. Analogous to this transformation, our understanding of spinopelvic conditions has experienced a paradigm shift in terms of both static and dynamic changes in spinopelvic pathologies and enabled a more accurate delineation of the drivers of disability. The purpose of this review is to describe the standard and state of the art of preoperative diagnostic and planning methods for common spinopelvic pathologies and to discuss both the added clinical value and limitations. The rationale is to accelerate the accurate and timely diagnosis and as well as the efficient and safe preoperative workflow.

The Optimal Timing of Hydrogel Injection for Treatment of Intervertebral Disc Degeneration: Quantitative Analysis Based on T1ρ MR Imaging

STUDY DESIGN

Animal experimental study.

OBJECTIVE

The aim of this study was to investigate the optimal time of hydrogel injection for regenerating intervertebral disc degeneration (IDD) based on T1ρ magnetic resonance imaging (MRI).

SUMMARY OF BACKGROUND DATA

Currently, different approaches are being pursued to regenerate the IDD. However, the optimal timing for the regenerative intervention is unclear.

METHODS

The slowly, progressive IDD models were established in 18 rhesus monkeys. On the basis of the MR T1ρ values of the discs, the rhesus monkeys were divided into severe (T1ρ values: <81 ms), moderate (T1ρ values: 81∼95 ms), and mild (T1ρ values: 96∼110 ms) degeneration groups. Biocompatible hydrogel was injected into the central part of the nucleus pulposus of the discs under fluoroscopic guidance. Treatment effects were investigated using radiography, T1ρ MRI, and histology until 12 months postoperatively.

RESULTS

After injection, the T1ρ values of all the discs increased significantly at 1 month postoperatively, and then remained at approximately 110 ms in the mild and moderate groups during the whole observation period, with no significant difference compared to the values at 1 month (P > 0.05). However, in the severe group, the T1ρ values decreased significantly after 1 month and leveled at approximately 70 ms after 6 months, with significant difference compared to the values at 1 month (P < 0.05). In the mild and moderate groups, there were no significant differences between preoperative histological scores and those at 12 months (P > 0.05). However, the histological score in the severe group at 12 months was significantly higher than the preoperative scores (P < 0.05).

CONCLUSION

This study suggested that the moderate degenerative stage of IDD (T1ρ values from 95 to 80 ms) could be the optimal time for hydrogel injection aimed at the regenerative intervention, based on T1ρ-MR imaging technique and quantitative analysis.

LEVEL OF EVIDENCE

N/A.

In silico feasibility assessment of extracorporeal delivery of low-intensity pulsed ultrasound to intervertebral discs within the lumbar spine

Low intensity pulsed ultrasound (LIPUS) may have utility for non-invasive treatment of discogenic lower back pain through stimulating, remodeling and accelerating healing of injured or degenerated intervertebral disc (IVD) tissues. This study investigates the feasibility of delivering LIPUS to lumbar IVDs between L2 and S1 spine vertebra using a planar extracorporeal phased array (8 × 8 cm, 1024 elements, 500 kHz). Three 3D anatomical models with heterogenous tissues were generated from patient CT image sets and used in the simulation-based analysis. Time-reversal acoustic modeling techniques were applied to optimize posterior-lateral placement of the array with respect to the body to facilitate energy deposition in discrete target regions spanning the annulus fibrosus and central nucleus of each IVD. Forward acoustic and biothermal simulations were performed with time-reversal optimized array placements and driving amplitude/phase settings to predict LIPUS intensity distributions at target sites and to investigate off-target energy deposition and heating potential. Simulation results demonstrate focal intensity gain of 5-168 across all IVD targets and anatomical models, with greater average intensity gain (>50) and energy localization in posterior, posterolateral, and lateral target sites of IVDs. Localized LIPUS delivery was enhanced in thinner patient anatomies and in the high lumbar levels (L2-L3 and L3-L4). Multiple amplitude/phasing illumination patterns could be sequenced at a fixed array position for larger regional energy coverage in the IVD. Biothermal simulations demonstrated that LIPUS-appropriate exposures of 100 mW cm^-2 I_SPTA to the target disc region would result in <1 °C global peak temperature elevation for all cases. Hence, simulations suggest that spatially-precise extracorporeal delivery of therapeutically relevant LIPUS doses to discrete regions of lumbar IVDs is feasible and may be useful in clinical management of discogenic back pain.

Analysis of intervertebral discs adjacent to thoracolumbar A3 fractures treated by percutaneous instrumentation and kyphoplasty

INTRODUCTION

Percutaneous instrumentation and kyphoplasty can be used to treat A3 fractures at T12-L1. However, the effect on adjacent intervertebral discs remains controversial. The purpose of this retrospective study was to analyze the degeneration of the discs adjacent to the fracture and to determine its relationship with age, vertebral body deformity and clinical scores.

MATERIALS AND METHODS

Twenty-nine patients (11 females, 18 males; average age 47 years, 27-63 years) were examined at 2.2 years' follow-up (2.0-2.5). Radiographic measurements were taken preoperatively, postoperatively, at follow-up: regional and local kyphosis, sagittal index, vertebral body compression ratio, and disc height index. The Pfirrmann grade was determined on an MRI taken at the final assessment. Clinical scores were the pain level (VAS), EQ-5D-3L, and ODI. The relationships between Pfirrmann grades, age and radiographic parameters were analyzed.

RESULTS

Local kyphosis decreased from 12.4° to 7.3° postoperatively (p<0.0001), increased to 8.4° after instrumentation removal (p=0.139) and remained stable at the last follow-up (p=0.891). The sagittal index decreased from 12.3° to 7.3° postoperatively (p<0.0001) increased to 8.3° before the instrumentation was removed (p=0.764) and increased to 10.6° (p<0.05) at the last follow-up. The vertebral body compression ratio decreased from 23% to 14% postoperatively (p<0.0001) and remained stable at 17% at the last follow-up (p=0.310). The cranial disc height index was 32% preoperatively, 31% postoperatively (p=0.073), 29% at 1year (p=0.650), and decreased again to 23% at 2 years (p<0.0001). There was a significant relationship between disc degeneration and age (p=0.015), local kyphosis (p=0.008) and vertebral body compression ratio (p=0.002). The disc adjacent to the fracture was more likely to have a higher Pfirrmann grade than the control disc above it (OR=269.5). At the final assessment, the average pain level was 2.3, the EQ-5D-3L was 0.862, and the ODI was 11.8%. There was no significant relationship between the Pfirrmann grades and the clinical scores.

CONCLUSION

The risk for cranial disc degeneration after percutaneous instrumentation and kyphoplasty of A3 fractures is low. The height of the cranial disc decreased after the instrumentation was removed. The risk for disc degeneration is related to age and vertebral body deformity. Disc degeneration does not appear to impact quality of life.

Circulating miR-155-5p as a Novel Biomarker of Lumbar Degenerative Disc Disease

MINI: Circulating microRNAs provide an insight into current disease states. Comparing patients with degenerative disc disease to healthy controls, patients with disc disease were found to have significantly downregulated levels of miR-155-5p. This marker was found to be an accurate diagnostic predictor for the presence of degeneration (P = 0.006).

STUDY DESIGN

Case-control study measuring differential gene expression of circulating microRNA (miRNA) in patients with degenerative disc disease (DDD).

OBJECTIVE

To identify miRNA dysregulation in serum samples of patients with DDD compared to healthy controls (HC).

SUMMARY OF BACKGROUND DATA

Early DDD can be a difficult diagnosis to make clinically, with lack of positive and specific findings on physical exam or advanced imaging. miRNAs are a class of molecules that act as gene regulators and have been shown to be dysregulated in local degenerative disc tissue. However, to date no studies have identified dysregulation of serum miRNA in patients with DDD.

METHODS

Whole blood samples were obtained from 69 patients with DDD and 16 HC. Patient-reported outcomes were collected preoperatively and degree of DDD was classified using Pfirrmann grade on preoperative imaging. Differential gene expression analysis using a screening assay for several hundred miRNAs and further characterization for five specific miRNAs (miR-16-5p, miR-21-5p, miR-142-3p, miR-146a-5p, and miR-155-5p) was performed. In addition, a pro-inflammatory cytokine multiplex assay and bioinformatics analysis were done.

RESULTS

The initial screening assay showed 13 miRNA molecules that were significantly dysregulated in DDD patients, with miR-155-5p showing significant downregulation (p = 0.027) and direct interactions with the pro-inflammatory cytokine IL-1β, and the tumor suppressor genes p53 and BRAF. Analyzing the whole cohort, miR-155 showed an almost four-fold downregulation in DDD patients (-3.94-fold, P < 0.001) and was the sole miRNA that accurately predicted the presence of disc degeneration (P = 0.006). Downregulation of miR-155 also correlated with increased leg pain (P = 0.018), DDD (P = 0.006), and higher Pfirrmann grade (P = 0.039). On cytokine analysis, TNF-α (0.025) and IL-6 (P < 0.001) were significantly higher in DDD patients.

CONCLUSION

Serum miR-155-5p is significantly downregulated in patients with DDD and may be a diagnostic marker for degenerative spinal disease.

LEVEL OF EVIDENCE

N/A.

Synthetic MRI of the lumbar spine at 3.0 T: feasibility and image quality comparison with conventional MRI

Background

Synthetic magnetic resonance imaging (MRI), which can generate multiple morphologic MR images as well as quantitative maps from a single sequence, is not widely used in the spine at 3.0 T.

Purpose

To investigate the feasibility of synthetic MRI of the lumbar spine in clinical practice at 3.0 T.

Material and Methods

Eighty-four patients with lumbar diseases underwent conventional T1-weighted images, T2-weighted images, short-tau inversion recovery (STIR) images, and synthetic MRI of the lumbar spine at 3.0 T. The quantitative and qualitative image quality and agreement for detection of spinal lesions between conventional and synthetic MRI were compared by two radiologists.

Results

The signal-to-noise ratios of synthetic MRI showed an inferior image quality in the vertebrae and disc, whereas were higher for spinal canal and fat on the synthetic T1-weighted, T2-weighted, and STIR images. The contrast-to-noise ratios of the synthetic MRI was superior to conventional sequences, except for the vertebrae–disc contrast-to-noise ratio on T1-weighted imaging ( P =  0.005). Image quality assessments showed that synthetic MRI had greater STIR fat suppression ( P <  0.001) and fluid brightness ( P =  0.014), as well as higher degree of artifacts ( P <  0.001) and worse spatial resolution ( P =  0.002). The inter-method agreements for detection of spinal lesions were substantial to perfect (kappa, 0.614–0.925).

Conclusion

Synthetic MRI is a feasible method for lumbar spine imaging in a clinical setting at 3.0-T MR. It provides morphologic sequences with acceptable image quality, good agreement with conventional MRI for detection of spinal lesions and quantitative image maps with a slightly shorter acquisition time compared with conventional MRI.

Abnormal Conditions of the Diskovertebral Segment: MRI With Anatomic-Pathologic Correlation

OBJECTIVE. The purpose of this article is to review the appearance of various abnormalities that affect the lumbar intervertebral disk and diskovertebral segment through anatomic-pathologic correlation in cadavers. CONCLUSION. Familiarity with the pathologic conditions in and around the intervertebral disk is important in recognizing such conditions as a potential source of symptoms. We revisit the principal role of MRI in evaluating these abnormalities and excluding other sources of significant clinical manifestations.

Stem cell therapy in discogenic back pain

Chronic low back pain has both substantial social and economic impacts on patients and healthcare budgets. Adding to the magnitude of the problem is the difficulty in identifying the exact causes of disc degeneration with modern day diagnostic and imaging techniques. With that said, current non-operative and surgical treatment modalities for discogenic low back pain fails to meet the expectations in many patients and hence the challenge. The objective for newly emerging stem cell regenerative therapy is to treat degenerative disc disease (DDD) by restoring the disc's cellularity and modulating the inflammatory response. Appropriate patient selection is crucial for the success of stem cell therapy. Regenerative modalities for discogenic pain currently focus on the use of either primary cells harvested from the intervertebral discs or stem cells from other sources whether autogenic or allogenic. The microenvironment in which stem cells are being cultured has been recognized to play a crucial role in directing or maintaining the production of the desired phenotypes and may enhance their regenerative potential. This has led to a more specific focus on innovating more effective culturing techniques, delivery vehicles and scaffolds for stem cell application. Although stem cell therapy might offer an attractive alternative treatment option, more clinical studies are still needed to establish on the safety and feasibility of such therapy. In this literature review, we aim to present the most recent in vivo and in vitro studies related to the use of stem cell therapy in the treatment of discogenic low back pain.

A comparative study of diffusion kurtosis imaging and T2* mapping in quantitative detection of lumbar intervertebral disk degeneration

PURPOSE

To assess the feasibility of diffusion kurtosis imaging (DKI) for diagnosing lumbar intervertebral disk degeneration (IDD) and to compare the potential of DKI and T2* mapping in the diagnosis of early IDD.

METHODS

Sagittal T2WI, DKI, and T2* mapping were performed in 75 subjects with 375 lumbar intervertebral disks at a 3.0-T MRI. DKI-related parameters including mean kurtosis (MK), mean diffusivity (MD), fractional anisotropy (FA), and T2* values were calculated for each disk which was segmented into three regions: nucleus pulposus (NP), anterior annulus fibrosus (AAF), and posterior annulus fibrosus (PAF).

RESULTS

MK and FA were positively correlated with Pfirrmann grade (all P < 0.001). MD and T2* were negatively correlated with Pfirrmann grade (all P < 0.001) except for T2* value of AAF (r = 0.087, P > 0.05). MK and FA values increased, while MD and T2* values decreased with age. No statistical significance was found between men and women (P > 0.05). Cephalic lumbar disks (L1/L2 and L2/L3) got lower MK and FA values than caudal lumbar disks (L4/L5 and L5/S1) (all P < 0.05), while cephalic lumbar disks got higher MD value than caudal lumbar disks (all P < 0.05). ROC analysis demonstrated that MK, MD, and FA showed significantly higher diagnostic accuracies than T2*, especially in NP and PAF.

CONCLUSIONS

DKI can be used to assess human lumbar IDD. And DKI was more sensitive to the quantitative detection of early lumbar IDD than T2* mapping. These slides can be retrieved under Electronic Supplementary Material.

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.

Paraspinal Muscle DTI Metrics Predict Muscle Strength

Background

The paraspinal muscles play an important role in the onset and progression of lower back pain. It would be of clinical interest to identify imaging biomarkers of the paraspinal musculature that are related to muscle function and strength. Diffusion tensor imaging (DTI) enables the microstructural examination of muscle tissue and its pathological changes.

Purpose

To investigate associations of DTI parameters of the lumbar paraspinal muscles with isometric strength measurements in healthy volunteers.

Study Type

Prospective.

Subjects

Twenty‐one healthy subjects (12 male, 9 female; age = 30.1 ± 5.6 years; body mass index [BMI] = 27.5 ± 2.6 kg/m²) were recruited.

Field Strength/Sequence

3 T/single‐shot echo planar imaging (ss‐EPI) DTI in 24 directions; six‐echo 3D spoiled gradient echo sequence for chemical shift encoding‐based water–fat separation.

Assessment

Paraspinal muscles at the lumbar spine were examined. Erector spinae muscles were segmented bilaterally; cross‐sectional area (CSA), proton density fat fraction (PDFF), and DTI parameters were calculated. Muscle flexion and extension maximum isometric torque values [Nm] at the back were measured with an isokinetic dynamometer and the ratio of extension to flexion strength (E/F) calculated.

Statistical Tests

Pearson correlation coefficients; multivariate regression models.

Results

Significant positive correlations were found between the ratio of extension to flexion (E/F) strength and mean diffusivity (MD) (P = 0.019), RD (P = 0.02) and the eigenvalues (λ1: P = 0.026, λ2: P = 0.033, λ3: P = 0.014). In multivariate regression models λ3 of the erector spinae muscle λ3 and gender remained statistically significant predictors of E/F (R²_adj = 0.42, P = 0.003).

Data Conclusion

DTI allowed the identification of muscle microstructure differences related to back muscle function that were not reflected by CSA and PDFF. DTI may potentially track subtle changes of back muscle tissue composition.

Level of Evidence: 3

Technical Efficacy: Stage 2

J. Magn. Reson. Imaging 2019;50:816–823.

Validity of a Smartphone Application (Sagittalmeter Pro) for the Measurement of Sagittal Balance Parameters

OBJECTIVE

The study was aimed to compare the validity, reproducibility, precision, and efficiency of a picture archiving and communication system (PACS) and a smartphone application, which is an educative app to easily measure sagittal balance parameters (SagittalMeter Pro), for measuring spinopelvic sagittal parameters.

METHODS

Three spine surgeons measured lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) on standing posteroanterior radiographs of 30 patients using PACS and SagittalMeter Pro. Measurements were repeated a week after the original measurements. Intraobserver and interobserver variabilities and reliabilities of each parameter (LL, PI, SS, and PT) were calculated for both techniques. Comparisons were performed using the paired t-test. Results are expressed as mean ± standard deviation and P values of < 0.05 were considered significant.

RESULTS

PACS to SagittalMeter Pro differences between the mean absolute values of LL, PI, SS, PT were 0.50°, 0.82°, 0.81°, 0.34°, respectively, and intraobserver and interobserver variabilities were similar. Excellent intraobserver and interobserver reliabilities were obtained for PACS and SagittalMeter Pro as demonstrated by values >0.86 and >0.84, respectively. Measurement times for PACS and SagittalMeter Pro were 36.63 ± 7.55 and 14.57 ± 1.96 seconds, respectively, and this difference was significant (P = 0.001).

CONCLUSIONS

The study shows PACS and SagittalMeter Pro are equivalent in terms of their abilities to measure spinopelvic sagittal parameters, and that the time required to obtain measurements was significantly less for SagittalMeter Pro. We believe that SagittalMeter Pro may be helpful when planning spinal surgery.

Advancing cell therapies for intervertebral disc regeneration from the lab to the clinic: Recommendations of the ORS spine section

Intervertebral disc degeneration is strongly associated with chronic low back pain, a leading cause of disability worldwide. Current back pain treatment approaches (both surgical and conservative) are limited to addressing symptoms, not necessarily the root cause. Not surprisingly therefore, long-term efficacy of most approaches is poor. Cell-based disc regeneration strategies have shown promise in preclinical studies, and represent a relatively low-risk, low-cost, and durable therapeutic approach suitable for a potentially large patient population, thus making them attractive from both clinical and commercial standpoints. Despite such promise, no such therapies have been broadly adopted clinically. In this perspective we highlight primary obstacles and provide recommendations to help accelerate successful clinical translation of cell-based disc regeneration therapies. The key areas addressed include: (a) Optimizing cell sources and delivery techniques; (b) Minimizing potential risks to patients; (c) Selecting physiologically and clinically relevant efficacy metrics; (d) Maximizing commercial potential; and (e) Recognizing the importance of multidisciplinary collaborations and engaging with clinicians from inception through to clinical trials.

Are radio-contrast agents commonly used in discography toxic to the intact intervertebral disc tissue cells?

In the literature, there have been no studies showing clear results on how radio-contrast pharmaceuticals would affect intact disc tissue cells. In this context, it was aimed to evaluate the effects of iopromide and gadoxetic acid, frequently used in the discography, on intact lumbar disc tissue in pharmaco-molecular and histopathological level. Primary cell cultures were prepared from the healthy disc tissue of the patients operated in the neurosurgery clinic. Except for the control group, the cultures were incubated with the indicated radio-contrast agents. Cell viability, toxicity and proliferation indices were tested at specific time intervals. The cell viability was quantitatively analysed. It was also visually rechecked under a fluorescence microscope with acridine orange/propidium iodide staining. Simultaneously, cell surface morphology was analysed with an inverted light microscope, while haematoxylin and eosin (H&E) staining methodology was used in the histopathological evaluations. The obtained data were evaluated statistically. Unlike the literature, iopromide or gadoxetic acid did not have any adverse effects on the cell viability, proliferation and toxicity (P < 0.05). Although this study reveals that radio-contrast pharmaceuticals used in the discography, often used in neurosurgical practice, can be safely used, it should be remembered that this study was performed in an in vitro environment.

ABCs of the degenerative spine

Degenerative changes in the spine have high medical and socioeconomic significance. Imaging of the degenerative spine is a frequent challenge in radiology. The pathogenesis of this degenerative process represents a biomechanically related continuum of alterations, which can be identified with different imaging modalities. The aim of this article is to review radiological findings involving the intervertebral discs, end plates, bone marrow changes, facet joints and the spinal canal in relation to the pathogenesis of degenerative changes in the spine. Findings are described in association with the clinical symptoms they may cause, with a brief review of the possible treatment options. The article provides an illustrated review on the topic for radiology residents.

TEACHING POINTS

• The adjacent vertebrae, intervertebral disc, ligaments and facet joints constitute a spinal unit. • Degenerative change is a response to insults, such as mechanical or metabolic injury. • Spine degeneration is a biomechanically related continuum of alterations evolving over time.

Value of delayed gadolinium-enhanced magnetic resonance imaging of cartilage for the pre-operative assessment of cervical intervertebral discs

The study was performed to preoperatively assess the cartilage integrity of cervical intervertebral discs (IVDs) using Delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC). Therefore, 53 cervical intervertebral discs of nine preoperative patients with neck and shoulder/arm pain scheduled for discectomy (five females, four males; mean age: 47.1 ± 8.4 years; range: 36-58 years) were included for biochemical analysis in this retrospective study. The patients underwent 3T magnetic resonance imaging (MRI) including biochemical imaging with dGEMRIC and morphological, sagittal T2 weighted (T2w) imaging. Cervical IVDs were rated using an MRI based grading system for cervical IVDs on T2w images. Region-of-interest measurements were performed in the nucleus pulposus (NP) and annulus fibrosus (AF) and a dGEMRIC index was calculated. Our results demonstrated that IVDs scheduled for discectomy showed significantly lower dGEMRIC index compared to IVDs that did not require surgical intervention in NP and AF (NP: 898.4 ± 191.9 ms vs. 1,150.3 ± 320.7 ms, p = 0.008; AF: 738.7 ± 183.8 ms vs. 984.6 ± 178.9 ms, p = 0.008). For Miyazaki score 3, the dGEMRIC indices were significantly lower in IVDs scheduled for surgery compared to non-operated discs for NP (p = 0.043) and AF (p = 0.018). In conclusion we could demonstrate that biochemical imaging with dGEMRIC is feasible in cervical IVDs. Significantly lower dGEMRIC index suggested GAG depletion in degenerated cervical IVD, scheduled for discectomy. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1824-1830, 2017.

In vivo diffusion MRS investigation of non-water molecules in biological tissues

Diffusion MRS of non-water molecules offers great potential in directly revealing various tissue microstructures and physiology at both cellular and subcellular levels. In brain, ¹ H diffusion MRS has been demonstrated as a new tool for probing normal tissue microstructures and their pathological changes. In skeletal muscle, ¹ H diffusion MRS could characterize slow and restricted intramyocellular lipid diffusion, providing a sensitive marker for metabolic alterations, while ³¹ P diffusion MRS can measure ATP and PCr diffusion, which may reflect the capacity of cellular energy transport, complementing the information from frequently used ³¹ P MRS in muscle. In intervertebral disk, ¹ H diffusion MRS can directly monitor extracellular matrix integrity by quantifying the mobility of macromolecules such as proteoglycans and collagens. In tumor tissue, ¹³ C diffusion MRS could probe intracellular glycolytic metabolism, while ¹ H diffusion MRS may separate the spectrally overlapped lactate and lipid resonances. In this review, recent diffusion MRS studies of these biologically relevant non-water molecules under normal and diseased conditions will be presented. Technical considerations for diffusion MRS experiments will be discussed. With advances in MRI hardware and diffusion methodology, diffusion MRS of non-water molecules is expected to provide increasingly valuable and biologically specific information on tissue microstructures and physiology, complementing the traditional diffusion MRI of small and ubiquitous water molecules. Copyright © 2016 John Wiley & Sons, Ltd.

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.

Lumbar intervertebral discs T2 relaxometry and T1ρ relaxometry correlation with age in asymptomatic young adults

BACKGROUND

To investigate the detection of intervertebral disc (IVD) composition aging-related changes using T2 and T1ρ relaxometry in vivo in asymptomatic young adults.

METHODS

We recruited ninety asymptomatic and young adults (42 men and 48 women) between 20 and 40 years old. T2 and T1ρ lumbar spine mappings were acquired using 1.5 T magnetic resonance imaging (MRI) scanner. Two independent observers manually segmented 450 lumbar discs in all slices. They also performed sub region segmentation of annulus fibrosus (AF) and nucleus pulposus (NP) at the central MRI sagittal slices.

RESULTS

There was no difference between men and women for T2 (P=0.37) or T1ρ relaxometry (P=0.97). There was a negative correlation between age (20-40 years) and IVD T2 relaxation time of the whole disc (r=-0.30, P<0.0001), NP (r=-0.20 to -0.51, P<0.05) and posterior AF (r=-0.21 to -0.31, P<0.05) at all lumbar disc levels. There was no statistical correlation between aging and IVD T1ρ relaxation both for NP and AF.

CONCLUSIONS

T2 relaxometry detected gradual IVD dehydration in the first two decades of adulthood. We observed no significant variation of T1ρ or volumetry with aging in our study group. Our results suggest that T2 mapping may be more appropriate to detect early IVD aging changes.

MR Imaging and Radiographic Imaging of Degenerative Spine Disorders and Spine Alignment

Advances in MR imaging technologies, as well as the widening of their availability, boosted their use in the diagnosis of spinal disorders and in the preoperative planning of spine surgeries. However, the most consolidated approach to the assessment of adult patients with spinal disorders is based on the analysis of full standing radiographs (posteroanterior and laterolateral views). In this article, the radiographic spinal and pelvic parameters, which have relevance in the clinical management of adults with spinal disorders, are summarized.

Computed Tomography Findings Associated with Clinical Outcome After Dynamic Posterior Stabilization of the Lumbar Spine

OBJECTIVE

To evaluate whether preoperative multirow detector computed tomography (MDCT) findings were associated with clinical outcome 24 months after dynamic stabilization for painful degenerative lumbar spine disease.

METHODS

Preoperative MDCT examinations of 63 patients (66 ± 11.7 years; 60% women) treated with a dynamic screw rod system for painful degenerative segmental instability with/without spinal stenosis were assessed for quantitative and qualitative parameters defining degenerative changes of the thoracolumbar spine, including grades of disc herniation, degenerative spondylolisthesis, vertebral body sclerosis, cross-sectional area of the spinal canal at disc level, intervertebral disc height, ancillary bone mineral density, and anteroposterior diameter of intervertebral foramina. Clinical performance was assessed at baseline and 24 months with quantitative scales, including the Oswestry Disability Index and Short-Form 36 physical component summary. For statistical analysis classification and regression trees, linear regression and nonparametric tests were used.

RESULTS

Clinical scores improved substantially over 24 months compared with preoperative values (delta Oswestry Disability Index -32.1 ± 17.2, delta Short-Form 36 physical component summary 4.9 ± 2.3). Physical component summary improvement was significantly better in patients with lower grades of disc herniation (P < 0.001) and/or spondylolisthesis (P = 0.011), lower cross-sectional area of the spinal canal (P = 0.043), high intervertebral disc height (P = 0.006), and high grades of vertebral body sclerosis (P = 0.002). Patients with high bone mineral density and initially low diameter of intervertebral foramina showed a significantly better improvement of Oswestry Disability Index (P < 0.05).

CONCLUSIONS

Clinical improvement after dynamic stabilization was significantly associated with 7 independent baseline imaging findings. Preoperative evaluation of these MDCT parameters may improve therapy selection for patients with degenerative lumbar spine disease.

Fibrin-genipin annulus fibrosus sealant as a delivery system for anti-TNFα drug

BACKGROUND CONTEXT

Intervertebral discs (IVDs) are attractive targets for local drug delivery because they are avascular structures with limited transport. Painful IVDs are in a chronic inflammatory state. Although anti-inflammatories show poor performance in clinical trials, their efficacy treating IVD cells suggests that sustained, local drug delivery directly to painful IVDs may be beneficial.

PURPOSE

The purpose of this study was to determine if genipin cross-linked fibrin (FibGen) with collagen Type I hollow spheres (CHS) can serve as a drug-delivery carrier for infliximab, the anti-tumor necrosis factor α (TNFα) drug. Infliximab was chosen as a model drug because of the known role of TNFα in increasing downstream production of several pro-inflammatory cytokines and pain mediators. Genipin cross-linked fibrin was used as drug carrier because it is adhesive, injectable, and slowly degrading hydrogel with the potential to seal annulus fibrosus (AF) defects. CHS allow simple and nondamaging drug loading and could act as a drug reservoir to improve sustained delivery.

STUDY DESIGN/SETTING

This is a study of biomaterials and human AF cell culture to determine drug release kinetics and efficacy.

METHODS

Infliximab was delivered at low and high concentrations using FibGen with and without CHS. Gels were analyzed for structure, drug release kinetics, and efficacy treating human AF cells after release.

RESULTS

Fibrin showed rapid infliximab drug release but degraded quickly. CHS alone showed a sustained release profile, but the small spheres may not remain in a degenerated IVD with fissures. Genipin cross-linked fibrin showed steady and low levels of infliximab release that was increased when loaded with higher drug concentrations. Infliximab was bound in CHS when delivered within FibGen and was only released after enzymatic degradation. The infliximab released over 20 days retained its bioactivity as confirmed by the sustained reduction of interleukin (IL)-1β, IL-6, IL-8, and TNFα concentrations produced by AF cells.

CONCLUSIONS

Direct mixing of infliximab into FibGen was the simplest drug-loading protocol capable of sustained release. Results show feasibility of using drug-loaded FibGen for delivery of infliximab and, in the context with the literature, show potential to seal AF defects and partially restore IVD biomechanics. Future investigations are required to determine if drug-loaded FibGen can effectively deliver drugs, seal AF defects, and promote IVD repair or prevent further IVD degeneration in vivo.

An update on the management of chronic lumbar discogenic pain

Lumbar degenerative disc disease without disc herniation, also known as discogenic pain, is an elusive diagnosis of chronic low back pain. Lumbar provocation discography and fusion surgery have been frequently utilized for several decades as the gold standards for the diagnosis and treatment of symptomatic lumbar discogenic pain, though controversial, based on conjecture, rather than evidence. In addition to lumbar fusion, various other operative and nonoperative modalities of treatments are available in managing chronic lumbar discogenic pain. This review provides an updated assessment of the management of chronic lumbar discogenic pain with a critical look at the many modalities of treatments that are currently available.

Comparison of T1ρ and T2* Relaxation Mapping in Patients with Different Grades of Disc Degeneration at 3T MR

BACKGROUND

T1ρ and T2* relaxation times are capable of providing information about early biochemical changes in intervertebral disk degeneration (IVDD). The purpose of this study was to assess and compare T1ρ and T2* mapping in IVDD with reference to Pfirrmann grade.

MATERIAL AND METHODS

Lumbar sagittal T2-weighted, T1ρ and T2* relaxation MRI were performed at 3.0T in 42 subjects covering discs L1-L2 to L5-S1. All the discs were morphologically assessed according to the Pfirrmann grade. Regions of interest (ROIs) were drawn over the T1ρ and T2*mappings, including nucleus pulposus (NP) and annulus fibrosus (AF). Wilcoxon signed rank test, Kruskal-Wallis test, and Spearman rank correlation were performed.

RESULTS

The difference in T1ρ and T2* values between NP and AF were highly significant (P<0.001). The trends of decreasing T1ρ and T2* values of both NP and AF with increasing Pfirrmann grades was significant (P<0.01), particularly between Pfirrmann grade II and III (P<0.001), whereas T2* mapping was additionally able to detect changes in the AF between Pfirrmann grade I and II (P<0.05). Pfirrmann grades were inversely significantly correlated with both T1ρ and T2* values in the NP (r=-0.69, P<0.001; r=-0.56, P<0.001) and AF (r=-0.45, P<0.001; r=-0.26, P<0.001).

CONCLUSIONS

The process of IVDD can be detected by T1ρ and T2* mapping, particularly at early stage, and both methodologies displayed roughly comparable performance.

Clinical management of radicular pain

This review provides an overview of the diagnosis and treatment strategies for the management of radicular pain. While it is not as common as axial spinal pain, radicular pain combines the advantage of leveraging appropriate diagnostic strategies and definitive treatments with well-informed outcome measures. Multiple diagnostic measures include not only history and physical examination, but also imaging. The treatment modalities include pharmacologic management, physical and rehabilitation measures, interventional techniques and surgical treatments. Here, the authors describe the prevalence and pathophysiology of radicular pain, risk factors, diagnostic strategies, treatment modalities and the evidence for these management strategies. Finally, the authors show the efficacy of conservative management, despite surgical management being the gold standard.

T1ρ and T2 mapping of the intervertebral disk: comparison of different methods of segmentation

BACKGROUND AND PURPOSE

Intervertebral disk biochemical composition could be accessed in vivo by T1ρ and T2 relaxometry. We found no studies in the literature comparing different segmentation methods for data extraction using these techniques. Our aim was to compare different manual segmentation methods used to extract T1ρ and T2 relaxation times of intervertebral disks from MR imaging. Seven different methods of partial-disk segmentation techniques were compared with whole-disk segmentation as the reference standard.

MATERIALS AND METHODS

Sagittal T1ρ and T2 maps were generated by using a 1.5T MR imaging scanner in 57 asymptomatic volunteers 20-40 years of age. Two hundred eighty-five lumbar disks were separated into 2 groups: nondegenerated disk (Pfirrmann I and II) and degenerated disk (Pfirrmann III and IV). In whole-disk segmentation, the disk was segmented in its entirety on all sections. Partial-disk segmentation methods included segmentation of the disk into 6, 5, 4, 3, and 1 sagittal sections. Circular ROIs positioned in the nucleus pulposus and annulus fibrosus were also used to extract T1ρ and T2, and data were compared with whole-disk segmentation

RESULTS

In the nondegenerated group, segmentation of ≥5 sagittal sections showed no statistical difference with whole-disk segmentation. All the remaining partial-disk segmentation methods and circular ROIs showed different results from whole-disk segmentation (P < .001). In the degenerated disk group, all methods were statistically similar to whole-disk segmentation. All partial-segmentation methods, including circular ROIs, showed strong linear correlation with whole-disk segmentation in both the degenerated and nondegenerated disk groups.

CONCLUSIONS

Manual segmentation showed strong reproducibility for T1ρ and T2 and strong linear correlation between partial- and whole-disk segmentation. Absolute T1ρ and T2 values extracted from different segmentation techniques were statistically different in disks with Pfirrmann grades I and II.

Growth factors and platelet-rich plasma: promising biological strategies for early intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is a complex process with the mechanism not fully elucidated. The current clinical treatments for IDD are mainly focused on providing symptomatic relief without addressing the underlying cause of the IDD. Biological therapeutic strategies to repair and regenerate the degenerated discs are drawing more attention. Growth factor therapy is one of the biological strategies and holds promising prospects. As a promising bioactive substance, platelet-rich plasma (PRP) is considered to be an ideal growth factor "cocktail" for intervertebral disc (IVD) restoration. Results from many in vitro and in vivo studies have confirmed the efficacy of growth factors and PRP in IVD repair and regeneration. It is essential to advance the research on growth factor therapy and associated mechanism for IDD. This article reviews the background of IDD, current concepts in growth factor and PRP-related therapy for IDD. Future research perspectives and clinical directions are also discussed.

Form and function of the intervertebral disc in health and disease: a morphological and stain comparison study

Multiple histologic measurements are commonly used to assess degenerative changes in intervertebral disc (IVD) structure; however, there is no consensus on which stains offer the clearest visualization of specific areas within the IVD. The objective of this study was to compare multiple tinctorial stains, evaluate their ability to highlight structural features within the IVD, and investigate how they influence the capacity to implement a degeneration scoring system. Lumbar IVDs from seven human autopsy specimens were stained using six commonly used stains (Hematoxylin/Eosin, Toluidine Blue, Safranin-O/Fast Green, Extended FAST, modified Gomori's Trichrome, and Picrosirius Red Alcian Blue). All IVDs were evaluated by three separate graders to independently determine which stains (i) were most effective at discerning different structural features within different regions of the IVDs and (ii) allowed for the most reproducible assessment of degeneration grade, as assessed via the Rutges histological scoring system (Rutges et al. A validated new histological classification for intervertebral disc degeneration. Osteoarthritis Cartilage, 21, 2039-47). Although Trichrome, XFAST and PR/AB stains were all effective at highlighting different regions of whole IVDs, we recommend the use of PR/AB because it had the highest degree of rater agreement on assigned degeneration grade, allowed greater resolution of degeneration grade, has an inferential relationship between color and composition, and allowed clear differentiation of the different regions and structural disruptions within the IVD. The use of a standard set of stains together with a histological grading scheme can aid in the characterization of structural changes in different regions of the IVD and may simplify comparisons across the field. This collection of human IVD histological images highlights how IVD degeneration is not a single disease but a composite of multiple processes such as aging, injury, repair, and disease, each of which are unique to the individual.