MRI evaluation of the effects of extension exercises on the disc fluid content and location of the centroid of the fluid distribution

Correlation between lumbar spinal canal magnetic resonance imaging grading systems and parameters in lumbar spinal canal compromise

Background

There is a need to assess how commonly used classification systems of intervertebral disc degeneration reflect the compromise of neural elements. This study aims to explore the relationship between lumbar discs degenerative diseases using the Pfirrmann and the Combined Task Forces (CTF) of the North American Spine Society (NASS) grading systems as well as qualitative and quantitative grades of lumbar spinal stenosis. This retrospective cohort study included adult patients undergoing non-contrast MR imaging of lumbosacral spine. The radiological assessment included the Pfirrmann grading system, Van Rijn classification, Combined Task Force (CTF) classification, measurement of the cross-sectional area of the dural sac, mid-sagittal antero-posterior diameter of the thecal sac, the degree of dural sac compression at disc level, lateral recesses heights, and intervertebral foramina diameters. The degree of stenosis of the spinal canal and intervertebral foramina was assessed.

Results

One hundred patients were included in the study. At all levels, Pfirrmann grades had a moderate, significant, positive correlation with the severity of stenosis of the central and lateral spinal canals as well as foraminal stenosis. The grades of lumbar spinal canal and foraminal stenosis had a significant positive correlation with degree of disc displacement as assessed by CTF classification and had a significant negative correlation with the quantitative lumbar spinal canal and foraminal measures.

Conclusions

There is a good correlation between Pfirrmann classification, CTF classification of NASS, qualitative grading and quantitative measures of lumbar spinal canal that reflects the severity of lumbar spinal canal stenosis and nerve root compression.

Use of machine learning to select texture features in investigating the effects of axial loading on T2-maps from magnetic resonance imaging of the lumbar discs

BACKGROUND

Recent advances in texture analysis and machine learning offer new opportunities to improve the application of imaging to intervertebral disc biomechanics. This study employed texture analysis and machine learning on MRIs to investigate the lumbar disc's response to loading.

METHODS

Thirty-five volunteers (30 (SD 11) yrs.) with and without chronic back pain spent 20 min lying in a relaxed unloaded supine position, followed by 20 min loaded in compression, and then 20 min with traction applied. T₂-weighted MR images were acquired during the last 5 min of each loading condition. Custom image analysis software was used to segment discs from adjacent tissues semi-automatically and segment each disc into the nucleus, anterior and posterior annulus automatically. A grey-level, co-occurrence matrix with one to four pixels offset in four directions (0°, 45°, 90° and 135°) was then constructed (320 feature/tissue). The Random Forest Algorithm was used to select the most promising classifiers. Linear mixed-effect models and Cohen's d compared loading conditions.

FINDINGS

All statistically significant differences (p < 0.001) were observed in the nucleus and posterior annulus in the 135° offset direction at the L4-5 level between lumbar compression and traction. Correlation (P_2-Offset, P_4-Offset) and information measure of correlation 1 (P_3-Offset, P_4-Offset) detected significant changes in the nucleus. Statistically significant changes were also observed for homogeneity (P_2-Offset, P_3-Offset), contrast (P_2-Offset), and difference variance (P_4-Offset) of the posterior annulus.

INTERPRETATION

MRI textural features may have the potential of identifying the disc's response to loading, particularly in the nucleus and posterior annulus, which appear most sensitive to loading.

LEVEL OF EVIDENCE

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Texture analysis in the classification of T2 -weighted magnetic resonance images in persons with and without low back pain

Magnetic resonance imaging findings often do not distinguish between people with and without low back pain (LBP). However, there are still a large number of people who undergo magnetic resonance imaging to help determine the etiology of their back pain. Texture analysis shows promise for the classification of tissues that look similar, and machine learning can minimize the number of comparisons. This study aimed to determine if texture features from lumbar spine magnetic resonance imaging differ between people with and without LBP. In total, 14 participants with chronic LBP were matched for age, weight, and gender with 14 healthy volunteers. A custom texture analysis software was used to construct a gray-level co-occurrence matrix with one to four pixels offset in 0° direction for the disc and superior and inferior endplate regions. The Random Forests Algorithm was used to select the most promising classifiers. The linear mixed-effect model analysis was used to compare groups (pain vs. pain-free) at each level controlling for age. The Random Forest Algorithm recommended focusing on intervertebral discs and endplate zones at L4-5 and L5-S1. Differences were observed between groups for L5-S1 superior endplate contrast, homogeneity, and energy (p = .02). Differences were observed for L5-S1 disc contrast and homogeneity (p < .01), as well as for the inferior endplates contrast, homogeneity, and energy (p < .03). Magnetic resonance imaging textural features may have potential in identifying structures that may be the target of further investigations about the reasons for LBP.

Could compression and traction loading improve the ability of magnetic resonance imaging to identify findings related to low back pain?

BACKGROUND

Diagnostic imaging is routinely used to depict structural abnormalities in people with low back pain (LBP), but most findings are prevalent in people with and without LBP. It has been suggested that LBP is related to changes induced in the spine due to loading. Therefore, new imaging measurements are needed to improve our ability to identify structures relating to LBP.

OBJECTIVES

To investigate the response of the lumbar spine to compression and traction in participants with and without chronic LBP using MRI T₂-mapping.

METHOD

Fifteen participants with chronic LBP were matched for age, weight, and gender with 15 healthy volunteers. All participants underwent MRI under three loading conditions maintained for 20 min each: resting supine, followed by compression and traction, both using 50% body weight. Participants were imaged in the last 5 min of each loading condition. Disc morphometric and fluid-based measurements from T₂-maps were obtained.

RESULTS

Traditional MRI measurements (i.e. disc height, width and mean signal intensity) were not able to capture any differences in the changes measured in response to loading between individuals with and without pain. The location of the T₂ weighted centroid (WC) was able to capture the difference between groups in response to compression in the horizontal (p < 0.01) and vertical direction (p < 0.01), and in response to traction in the vertical direction (p < 0.01). While the location of T₂WC moved anteriorly (Effect Size (ES): 0.44) and inferiorly with compression in those with pain (ES: 0.34), it moved posteriorly (ES: -0.14) and superiorly (ES: -0.05) in the group without pain. In response to traction, the vertical location of T₂WC moved superiorly in both groups but the change was larger in those with pain (ES _Pain = -0.52; ES _{No Pain}: -0.13).

CONCLUSION

The novel measurements of the location of the T₂WC in the intervertebral discs were the only measurements capturing differences in response to loading between those with and without low back pain.

MRI During Spinal Loading Reveals Intervertebral Disc Behavior Corresponding to Discogram Findings of Annular Fissures and Pain Provocation

STUDY DESIGN

Retrospective analysis of prospectively collected data.

OBJECTIVE

The aim of this study was to investigate whether spinal loading, depicted with magnetic resonance imaging (MRI), induces regional intervertebral disc (IVD) differences associated with presence and width of annular fissure and induced pain at discography.

SUMMARY OF BACKGROUND DATA

Annular fissures play a role in low back pain (LBP) but cannot be accurately characterized with conventional MRI. Recently, annular fissures were suggested to influence different load-induced IVD behavior during MRI when comparing LBP-patients and controls. Thus, the loading effect could characterize behavior related to annular fissures noninvasively with MRI.

METHODS

Lumbar spines of 30 LBP-patients were investigated with MRI with and without loading, discography and CT. Five IVD regions were outlined on sagittal MRI images. Difference in normalized signal intensity (SI) with and without loading was calculated for each region. Eighty-three CT-discograms were graded regarding presence and width of fissures. Discograms were classified as pain-positive if a concordant pain response was obtained at a pressure <50 psi.

RESULTS

Comparing IVDs with outer fissures with IVDs without fissures, loading induced different behavior in the two ventral regions and in the posterior region. Higher SI increase in the central region was induced in IVDs with narrower fissures compared to IVDs with wider fissures. In the group of pain-negative discograms, a SI decrease was induced in the dorsal region whereas lack of such in the pain-positive group.

CONCLUSION

The spinal loading-effect, depicted with MRI, reveals different regional behaviors between IVDs with outer fissures compared to those without, and between IVDs with narrow and broad fissures, as well as within posterior annulus between pain-positive and pain-negative discograms. Findings are of importance for future attempts to uncover phenotypes of painful IVDs.

LEVEL OF EVIDENCE

2.

The importance of level stratification for quantitative MR studies of lumbar intervertebral discs: a cross-sectional analysis in 101 healthy adults

PURPOSE

To investigate whether quantitative T2-times depend on lumbar intervertebral disc (IVD) level.

METHODS

The lumbar spine (Th12/L1-L5/S1) of 101 participants (53.5% female, 30.0[± 3.6]years, 173.5[± 9.6]cm and 69.9[± 13.4]kg), without history of back pain, was examined on a 3T scanner with sagittal T2-mapping. All IVDs were stratified according to Pfirrmann grade and lumbar level, with mean T2-time determined for the entire IVD volume and in five subregions of interests.

RESULTS

Significant level-dependent T2-time differences were detected, both for the entire IVD volume and its subregions. For the entire IVD volume, Pfirrmann grade 2 IVDs displayed 9-18% higher T2-times in Th12/L1 IVDs compared to L2/L3-L5/S1 IVDs (0.001 > p < 0.004) and significantly different T2-times in L1/L2-L2/L3 IVDs compared to most of the IVDs in the lower lumbar spine. In Pfirrmann grades 1, 3 and 4 IVDs, no significant level-dependent T2-time differences were observed for the entire IVD. More pronounced results were observed when comparing IVD subregions, with significant level-dependent differences also within Pfirrmann grade 1 and grade 3 IVDs. For example, in posterior IVD subregions mean T2-time was 80-82% higher in Th12/L1 compared to L3/L4-L4/L5 Pfirrmann grade 1 IVDs (p < 0.05) and 10-14% higher in L5/S1 compared to L3/L4-L4/L5 Pfirrmann grade 3 IVDs (0.02 > p < 0.001).

DISCUSSION

Significant level-dependent T2-time differences within several Pfirrmann grades, both for the entire IVD volume and for multiple IVD subregions, were shown in this large cohort study. The T2-time differences between levels existed in both non-degenerated and degenerated IVDs. These findings show the importance of stratifying for lumbar level when quantitative IVD studies are performed using T2-mapping. These slides can be retrieved under Electronic Supplementary Material.

A randomized clinical trial comparing the McKenzie method and motor control exercises in people with chronic low back pain and a directional preference: 1-year follow-up

OBJECTIVE

The primary objective of this study was to compare the long-term (1-year follow-up) effects of the McKenzie method and motor control exercises on trunk muscle thickness in people with chronic low back pain (LBP) and a directional preference.

DESIGN

Randomized controlled trial.

SETTING

A secondary public health facility in Sydney, Australia.

PARTICIPANTS

Seventy adults with greater than 3-month history of LBP and a directional preference.

INTERVENTIONS

Participants were randomized to receive 12 treatments of either the McKenzie method or motor control exercises over 8-weeks.

OUTCOME MEASURES

Muscle thickness of the transversus abdominis, obliquus internus, and obliquus externus measured from ultrasound images. Secondary outcomes included function, perceived recovery, and pain. Outcomes were collected at baseline, post intervention at 8-weeks, and at 1-year follow-up by blinded assessors. The current paper focuses on the 1-year follow-up.

RESULTS

Fifty-eight participants completed data collection for the primary outcome at 1-year. There were no significant between group differences for changes in trunk muscle thickness for any of the three investigated muscles: transversus abdominis [3%, 95% confidence interval (CI): -5%, 11%], obliquus internus [-4%, 95% CI: -9%, 2%] and obliquus externus [3%, 95% CI: -4%, 11%]. Similarly, there were no significant differences between groups for the secondary outcomes of function, perceived recovery and pain.

CONCLUSION

Trunk muscle thickness, function, perceive recovery and pain are similar between patients receiving McKenzie method or motor control exercises at a 1-year follow-up in a population of people with chronic LBP and a directional preference. Clinical Trials Registration number CTRN12611000971932.