Reliability of standing weight-bearing (0.25T) MR imaging findings and positional changes in the lumbar spine

Upright versus recumbent lumbar spine MRI: Do findings differ systematically, and which correlates better with pain? A systematic review

BACKGROUND CONTEXT

Recumbent MRI is the most widely used image modality in people with low back pain (LBP), however, it has been proposed that upright (standing) MRI has advantages over recumbent MRI because of its ability to assess the effects of being weight-bearing. It has been suggested that this produces systematic differences in MRI parameters and differences in the correlation between MRI parameters and pain or disability in patients thus, potentially adding clinically helpful information.

PURPOSE

This paper aims to review and summarize the available empirical evidence for or against these two hypotheses.

STUDY DESIGN/SETTING

Systematic review of the literature (PROSPERO ID: CRD42017048318). Studies should be based on paired observations of MRI findings in the upright and recumbent positions. Studies needed a minimum of 15 participants.

PATIENT/PARTICIPANT SAMPLE

People aged 18 or older with or without low back pain ± radiculopathy OUTCOME MEASURES: All continuous, ordinal, and dichotomous parameters based on MRI images. All measures of pain or disability.

METHODS

Studies assessing MRI parameters both in upright and recumbent positions on the same individuals measured on continuous, ordinal, or dichotomous scales were included. For each parameter, the expected direction of the difference between recumbent and upright position was specified as an increase, no change, or decrease. Information on the observed distribution of individual differences was extracted from included studies and subjected to meta-analyses if sufficient data was available. Observed differences were then compared with the prespecified expectations. Studies were also screened for information on correlations between patients' pain and/or disability and MRI parameters or differences between patient subgroups defined by patients' pain and/or disability.

RESULTS

19 studies were identified, including 5.082 participants with LBP (16 studies) and 166 participants without low back pain (5 studies). Twenty-five MRI parameters were measured on a continuous scale, ten parameters were assessed on an ordinal scale, and 15 parameters were reported as dichotomous data. The observed differences between recumbent and upright MRI were mostly consistent with the prespecified expectations. Correlations between patients' pain or disability level and MRI parameters were reported in only one study, and three studies reported comparisons of MRI parameters across subgroups of patients defined by pain or disability characteristics. Higher correlations or larger effect sizes when using the upright position were observed in most results reported.

CONCLUSION

For most MRI parameters, the direction of the observed difference between assessment in recumbent and upright positions aligned with the pre-specified expectation implied by the weight-bearing position. This confirms the existence of a systematic difference between the two positions. Performing an MRI upright instead of recumbent position may increase the correlation with pain, but final evidence for this property is still missing. The clinical significance of upright MRI is still unclear, and there is a need to directly investigate the impact of MRI findings on clinical decision-making and patient outcomes.

ISSLS prize in clinical/bioengineering science 2024: How standing and supine positions influence nutrient transport in human lumbar discs?-A serial post-contrast MRI study evaluating interplay between convection and diffusion

PURPOSE

The intervertebral disc being avascular depends on diffusion and load-based convection for essential nutrient supply and waste removal. There are no reliable methods to simultaneously investigate them in humans under natural loads. For the first time, present study aims to investigate this by strategically employing positional MRI and post-contrast studies in three physiological positions: supine, standing and post-standing recovery.

METHODS

A total of 100 healthy intervertebral discs from 20 volunteers were subjected to a serial post-contrast MR study after injecting 0.3 mmol/kg gadodiamide and T1-weighted MR images were obtained at 0, 2, 6, 12 and 24 h. At each time interval, images were obtained in three positions, i.e. supine, standing and post-standing recovery supine. The signal intensity values at endplate zone and nucleus pulposus were measured. Enhancement percentages were calculated and analysed comparing three positions.

RESULTS

During unloaded supine position, there was slow gradual increase in enhancement reaching peak at 6 h. When the subjects assumed standing position, there was immediate loss of enhancement at nucleus pulposus which resulted in reciprocal increase in enhancement at endplate zone (washout phenomenon). Interestingly, when subjects assumed the post-standing recovery position, the nucleus pulposus regained the enhancement and endplate zone showed reciprocal loss (pumping-in phenomenon).

CONCLUSIONS

For the first time, present study documented acute effects of physiological loading and unloading on nutrition of human discs in vivo. While during rest, solutes diffused gradually into disc, the diurnal short loading and unloading redistribute small solutes by convection. Standing caused rapid solute depletion but promptly regained by assuming resting supine position.

Facet Joint Syndrome: Pathophysiology, Diagnosis, and Treatment

Facet joint osteoarthritis (OA) is the most frequent form of facet joint syndrome. Medical history, referred pain patterns, physical examination, and diagnostic imaging studies (standard radiographs, magnetic resonance imaging, computed tomography and single-photon emission computed tomography) may suggest but not confirm lumbar facet joint (LFJ) syndrome as a source of low back pain (LBP). However, the diagnosis and treatment of facet joint syndrome is still controversial and needs further study. It is widely acknowledged that block with local anesthetic is perhaps the most effective method to establish a diagnosis of pain from LFJ. Particularly, there are different rates of success among different populations selected for diagnostic block with various positive criteria. Currently, in addition to conservative treatments for pain such as painkillers, functional exercises, and massage, there are many other methods, including block, denervation of the nerves that innervate the joints by radiofrequency, freezing or endoscopy, and injections. Due to the limited duration of pain relief from neurolysis of medial branch, many scholars have recently turned their targets to dorsal roots and LFJ capsules. Therefore, we reviewed the latest research progress of facet joint syndrome from diagnosis to treatment.

Reliability of reporting differences in degenerative MRI findings of the lumbar spine from the supine to the upright position

OBJECTIVE

To determine the inter-rater reliability of identifying differences and types of differences in lumbar degenerative findings comparing supine and upright MRI.

MATERIALS AND METHODS

Fifty-nine participants, low back pain patients (LBP) with or without leg pain and no-LBP individuals were consecutively enrolled to receive supine and upright MRI of the lumbar spine. Three raters independently evaluated the MRIs for degenerative spinal pathologies and compared for differences. Presence/absence of degenerative findings were recorded for all supine and upright images, and then differences from the supine to the upright positions were classified into no-change, appeared, disappeared, worsened, or improved at each individual disc level. Reliability and agreement were calculated using Gwet's agreement coefficients (AC₁ or AC₂) and absolute agreement.

RESULTS

Inter-rater reliability of evaluating differences in eight degenerative lumbar findings comparing the supine and upright MRI position, ranged from 0.929 to 0.996 according to Gwet's agreement coefficients (AC₂). The total number of positive MRI findings in the supine position ranged from 270 to 453, with an average of 366 per rater. Observed differences from supine to upright MRI ranged from 18 to 80, with an average of 56 per rater.

CONCLUSION

Inter-rater reliability was found overall acceptable for classification of differences in eight types of degenerative pathology observed with supine and upright MRI of the lumbar spine. Results were primarily driven by high numbers and high reliability of rating negative findings, whereas agreement regarding positive findings and positive positional differences was lower.

Lumbar spondylolisthesis: STATE of the art on assessment and conservative treatment

INTRODUCTION

There is weak relationship between the presence of lumbar spondylolisthesis [SPL] and low back pain that is not always associated with instability, either at the involved lumbar segment or at different spinal levels. Therefore patients with lumbar symptomatic SPL can be divided into stable and unstable, based on the level of mobility during flexion and extension movements as general classifications for diagnostic and therapeutic purposes. Different opinions persist about best treatment (conservative vs. surgical) and among conservative treatments, on the type, dosage, and progression of physical therapy procedures.

PURPOSE AND IMPORTANCE TO PRACTICE

The aim of this Masterclass is to provide clinicians evidence-based indications for assessment and conservative treatment of SPL, taking into consideration some subgroups related to specific clinical presentations.

CLINICAL IMPLICATIONS

This Masterclass addresses the different phases of the assessment of a patient with SPL, including history, imaging, physical exam, and questionnaires on disability and cognitive-behavioral components. Regarding conservative treatment, self- management approaches and graded supervised training, including therapeutic relationships, information and education, are explained. Primary therapeutic procedures for pain control, recovery of the function and the mobility through therapeutic exercise, passive mobilization and antalgic techniques are suggested. Moreover, some guidance is provided on conservative treatment in specific clinical presentations (lumbar SPL with radiating pain and/or lumbar stenosis, SPL complicated by other factors, and SPL in adolescents) and the number/duration of sessions.

FUTURE RESEARCH PRIORITIES

Some steps to improve the diagnostic-therapeutic approach in SPL are to identify the best cluster of clinical tests, define different lumbar SPL subgroups, and investigate the effects of treatments based on that classification, similarly to the approach already proposed for non-specific LBP.

Please be upstanding - A narrative review of evidence comparing upright to supine lumbar spine MRI

OBJECTIVES

The objective of the review was to examine the evidence comparing upright to supine MRI of the lumbar spine.

KEY FINDINGS

A literature search identified 14 articles comparing data where subjects had been scanned in both supine and upright positions on the same scanner. Lumbar spine anatomy is dynamic and therefore subject to morphological changes when transitioning from the supine to the upright position. There is strong evidence to suggest structural changes in spinal morphology due to radiographic positioning, and that upright positioning is better for evaluating spondylolisthesis.

CONCLUSION

It has been demonstrated that the scanning position is important in the outcome of the MRI examination of the lumbar spine. With this in mind, it would be beneficial for guidance to be written and adopted to improve the consistency and quality of scanning.

IMPLICATIONS FOR PRACTICE

As upright MRI occupies a niche in the scanning sector, many professionals are unaware of its capabilities. This article aims to increase awareness of the use of upright MRI in evaluating the lumbar spine.

Dynamic MRI is reliable for evaluation of the lumbosacral spine in healthy dogs

Magnetic resonance imaging (MRI) is commonly used to diagnose degenerative lumbosacral stenosis; however, studies show limited correlation between imaging and clinical signs. The purpose of this prospective observer agreement study was to use dynamic MRI of the lumbosacral (LS) spine of healthy dogs to determine reliable reference ranges. Twenty-two healthy large breed dogs were prospectively enrolled. MRI of the LS spine was performed in T2-weighted, T1-weighted, and T2-weighted SPACE sequences in neutral, flexed, and extended positions. Four observers performed image analyses. Measurements included LS angle, vertebral canal height and area, and LS foraminal areas. Ordinal categorical assessment of loss of fat signal in the foramina, LS compression, intervertebral disc (IVD) degeneration, spondylosis, and IVD protrusion was also performed. The majority of values were significantly larger in flexion versus neutral position, and significantly smaller in extension versus neutral position (P < .05). Subclinical compression and IVD protrusion was noted in a neutral position in 45% and 55% of dogs and in an extended position in 85% and 73% of dogs, respectively. Interobserver agreement was strong (intracluster correlation coefficient [ICC] > .5) except for the L7:LS vertebral canal area ratio (ICC ≤ .03). Intraobserver agreement was high (rho > .5) for all measurements except for the mid-L6:LS vertebral canal height ratio (rho = .38). There was poor interobserver agreement for loss of fat signal in the foramina and evidence of compression. This study provides the groundwork for future studies using dynamic MRI to evaluate dogs with signs of clinical LS disease.

Effects of standing on lumbar spine alignment and intervertebral disc geometry in young, healthy individuals determined by positional magnetic resonance imaging

BACKGROUND

Most diagnostic imaging of the spine is performed in supine, a relatively unloaded position. Although the spine is subjected to functional loading that changes the spinal alignment and intervertebral disc geometry, little data exists on how healthy spines adapt to standing. This study seeks to quantify the changes of the lumbar spine from supine to standing in young, back-healthy individuals using a positional magnetic resonance imaging system.

METHODS

This is an observational study that examined the changes in the lumbar spine alignment and intervertebral disc geometry between supine and standing of forty participants (19 males/21 females) without a history of low back pain. The regional lumbar spinal alignment was measured by the sagittal Cobb angle. Segmental intervertebral disc measurements included the segmental Cobb angle, anterior-to-posterior height ratio, and intervertebral disc width measured at L1/L2 - L5/S1 levels. Intra-class correlation was performed for intra- and inter-observer measurements.

FINDINGS

The intra-observer intra-class correlation consistency model ranged from 0.76 to 0.98 with the inter-observer correlation ranging from 0.68 to 0.99. The Cobb angle decreased in standing. The L5/S1 segmental Cobb angle decreased in standing. The L2/L3 and L3/L4 anterior-to-posterior height ratios increased and the L5/S1 anterior-to-posterior height ratio decreased in standing. No difference in intervertebral disc widths was observed from supine to standing.

INTERPRETATIONS

We established normative data for a back-healthy population, using a positional magnetic resonance imaging system, that could inform future investigations that examine the standing-induced adaptations of the lumbar spine in individuals with spinal or intervertebral disc pathologies.

Imaging of the spine: Where do we stand?

The number of patients presenting with spine-related problems has globally increased, with an enormous growing demand for the use of medical imaging to address this problem. The last three decades witnessed great leaps for diagnostic imaging modalities, including those exploited for imaging the spine. These developments improved our diagnostic capabilities in different spinal pathologies, especially with multi-detector computed tomography and magnetic resonance imaging, via both hardware and software improvisations. Nowadays, imaging may depict subtle spinal instability caused by various osseous and ligamentous failures, and could elucidate dynamic instabilities. Consequently, recent diagnostic modalities can discern clinically relevant spinal canal stenosis. Likewise, improvement in diagnostic imaging capabilities revolutionized our understanding of spinal degenerative diseases via quantitative biomarkers rather than mere subjective perspectives. Furthermore, prognostication of spinal cord injury has become feasible, and this is expected to be translated into better effective patient tailoring to management plans with better clinical outcomes. Meanwhile, our confidence in diagnosing spinal infections and assessing the different spinal instrumentation has greatly improved over the past few last decades. Overall, revolutions in diagnostic imaging over the past few decades have upgraded spinal imaging from simple subjective and qualitative indices into a more sophisticated yet precise era of objective metrics via deploying quantitative imaging biomarkers.

Correlation of listhesis on upright radiographs and central lumbar spinal canal stenosis on supine MRI: is it possible to predict lumbar spinal canal stenosis?

OBJECTIVE

To investigate whether upright radiographs can predict lumbar spinal canal stenosis using supine lumbar magnetic resonance imaging (MRI) and to investigate the detection performance for spondylolisthesis on upright radiographs compared with supine MRI in patients with suspected lumbar spinal canal stenosis (LSS).

MATERIALS AND METHODS

In this retrospective study, conventional radiographs and MR images of 143 consecutive patients with suspected LSS (75 female, mean age 72 years) were evaluated. The presence and extent of listhesis (median ± interquartile range) were assessed on upright radiographs and supine MRI of L4/5. In addition, the grade of central spinal stenosis of the same level was evaluated on MRI according to the classification of Schizas and correlated with the severity/grading of anterolisthesis on radiographs.

RESULTS

Anterolisthesis was detected in significantly more patients on radiographs (n = 54; 38%) compared with MRI (n = 28; 20%), p < 0.001. Pairwise comparison demonstrated a significantly larger extent of anterolisthesis on radiographs (9 ± 5 mm) compared with MRI (5 ± 3 mm), p < 0.001. A positive correlation was found regarding the extent of anterolisthesis measured on radiographs and the grade of stenosis on MRI (r = 0.563, p < 0.001). Applying a cutoff value of ≥5 mm anterolisthesis on radiographs results in a specificity of 90% and a positive predictive value of 78% for the detection of patients with LSS, as defined by the Schizas classification.

CONCLUSION

Upright radiographs demonstrated more and larger extents of anterolisthesis compared with supine MRI. In addition, in patients with suspected LSS, the extent of anterolisthesis on radiographs (particularly ≥5 mm) is indicative of LSS and warrants lumbar spine MRI.

Current concept in upright spinal MRI

Magnetic resonance imaging (MRI) is the established technique for evaluating the spine. Unfortunately, the supine position of the patient during conventional MRI scanning does not truly reflect the physiological forces experienced by the discoligamentous structures during normal upright posture and ambulation. Upright MRI is a relatively new technique that allows the patient to be scanned in several different weight-bearing positions, which may potentially demonstrate occult pathology not visualised in the supine position. The imaging technique and current clinical indications of upright spinal MRI would be discussed.