Assessment of In Vivo Lumbar Inter-Vertebral Motion: Reliability of a Novel Dynamic Weight-Bearing Magnetic Resonance Imaging Technique Using a Side-Bending Task

Lumbar Spine Anatomy in Supine versus Weight- Bearing Magnetic Resonance Imaging: Detecting Significant Positional Changes and Testing Reliability of Quantification

STUDY DESIGN

Testing between and within group differences and assessing reliability of measurements.

PURPOSE

To study and compare lumbar spine morphology in supine and weight-bearing (WB) magnetic resonance imaging (MRI).

OVERVIEW OF LITERATURE

Upright lumbar MRI may uncover anatomical changes that may escape detection when using conventional supine imaging. This study quantified anatomical dimensions of the lumbar spine in the supine and WB MRI, compared specific morphometric differences between them, and tested the intra-rater reliability of the measurements. Repeated measures analysis was used to compare within- and between-session measurements performed on the supine and WB images. Reliability and agreement were assessed by calculating intraclass correlation (ICC) coefficient.

METHODS

Data from 12 adults without any history of back pain were used in this study. Sagittal T2-weighted images of the lumbar spine were acquired in the supine and WB positions twice (in two separate sessions scheduled within a week). Linear, angular dimensions, and cross-sectional areas (CSAs) were measured using proprietary software. Supine and WB data acquired from the two imaging sessions were tested for intra-rater reliability. Quantified data were normalized for each session to test the significance of differences. ICC was calculated to test the reliability of the measurements.

RESULTS

Linear, angular, and CSA measurements demonstrated strong within-position (supine and WB) correlations (r -values, 0.75-0.97). Between-position (supine vs. WB) differences were significant for all measured dimensions (p<0.05). Between-session measurements demonstrated a strong correlation (r -values, 0.64-0.83). Calculated ICC showed strong agreement among the measurements.

CONCLUSIONS

Anatomical dimensions of the lumbar spine may demonstrate consistent and significant differences between supine and WB MRI for specific structural parameters.

Load-Bearing Shifts in Laminar and Ligament Morphology: Comparing Spinal Canal Dimensions Using Supine versus Upright Lumbar MRI in Adults without Back Pain

Purpose  The effects of weight bearing on lumbar spinal canal dimensions are not well reported the low back pain (LBP) literature. Since axial loading induces changes in anatomical configuration of the lumbar spine, supine spine imaging may not uncover dimensional changes associated with physiological weight bearing that could be demonstrated in imaging in the upright position. Methods  This study compared anteroposterior spinal canal dimensions measured at the level of the intervertebral discs in the supine and upright lumbar spine magnetic resonance images in adults without a history or current back pain. Additionally, interlaminar distances were measured between the centers of adjacent laminae involving a spinal segment. These parameters were utilized to ascertain the deformation incurred at the ligamentum flavum due to load bearing. Results  Within and between-sessions t -tests, factorial and repeated-measures analysis of variance showed significant alterations in canal dimensions at certain levels, secondary to the upright positioning of the spine. Measurement reliability assessed between sessions and scanning positions using intraclass correlation coefficients demonstrated strong agreement. Conclusion  Imaging studies involving physiological weight bearing may be useful to understand the potential etiological effects of such changes in mechanical LBP.

The reliability of video fluoroscopy, ultrasound imaging, magnetic resonance imaging and radiography for measurements of lumbar spine segmental range of motion in-vivo: A review

BACKGROUND

Lower back pain (LBP) is a principal cause of disability worldwide and is associated with a variety of spinal conditions. Individuals presenting with LBP may display changes in spinal motion. Despite this, the ability to measure lumbar segmental range of motion (ROM) non-invasively remains a challenge.

OBJECTIVE

To review the reliability of four non-invasive modalities: Video Fluoroscopy (VF), Ultrasound imaging (US), Magnetic Resonance Imaging (MRI) and Radiography used for measuring segmental ROM in the lumbar spine in-vivo.

METHODS

The methodological quality of seventeen eligible studies, identified through a systematic literature search, were appraised.

RESULTS

The intra-rater reliability for VF is excellent in recumbent and upright positions but errors are larger for intra-rater repeated movements and inter-rater reliability shows larger variation. Excellent results for intra- and inter-rater reliability are seen in US studies and there is good reliability within- and between-day. There is a large degree of heterogeneity in MRI and radiography methodologies but reliable results are seen.

CONCLUSIONS

Excellent reliability is seen across all modalities. However, VF and radiography are limited by radiation exposure and MRI is expensive. US offers a non-invasive, risk free method but further research must determine whether it yields truly consistent measurements.