Lumbar spine MRI axial loading in patients with degenerative spine pathologies: Its impact on the Radiological findings and treatment decision

Axial loading during supine MRI for improved assessment of lumbar spine: comparison with standing MRI

BACKGROUND

There are no studies comparing the morphologic changes of lumbar spines between supine axial-loaded and 90° standing magnetic resonance imaging (MRI) examinations of patients with spinal stenosis.

PURPOSE

To determine whether axial-loaded MRI using a compression device demonstrated similar morphology of intervertebral disc, dural sac, and spinal curvature as those detected by 90° standing MRI in individuals with suspected spinal stenosis.

MATERIAL AND METHODS

A total of 54 individuals suspected of having spinal stenosis underwent both axial-loaded and standing MRI studies. The outcome measures included seven radiologic parameters of the lumbar spine: measures of the intervertebral disc (i.e. cross-sectional area [DA], disc height [DH], and anteroposterior distance [DAP]), dural sac (cross-sectional area [DCSA]), spinal curvature (i.e. lumbar lordosis [LL] and L1-L3-L5 angle [LA]), and total lumbar spine height (LH).

RESULTS

For agreement between the two methods, intraclass correlation coefficient (ICC) ≥ 0.8 was found for all seven radiologic parameters. Supine axial-loaded MRI underestimated LL but remained correlated (ICC = 0.83) with standing MRI. Minor differences between the two methods (≤5.0%) were observed in DA, DCSA, DAP, LA, and LH, while a major difference was observed in LL (8.1%).

CONCLUSION

Using a compression device with the conventional supine MRI to simulate weight-bearing on the lumbar spine generated MRI morphology, which was strongly correlated with those from a standing MRI.

Lumbosacral spinal compression device with the use of a cushion back support in supine MRI

BACKGROUND

We hypothesized that axial-loaded magnetic resonance imaging (MRI), modified with the use of a cushion placed behind the lower back (i.e. BS-MRI method), would simulate the standing position more accurately than an axial-loaded MRI without a cushion back support (BS).

PURPOSE

To determine whether the BS-MRI method demonstrated similar morphologies on intervertebral disc (IVD), dural sac, and spinal curvature as those detected on 90° standing MRIs in individuals with suspected spinal stenosis.

MATERIAL AND METHODS

Twenty-five subjects underwent a BS-MRI, as well as axial-loaded and standing MRI studies. Outcome measures were four radiographic parameters of the lumbar spine: IVD height (DH); dural sac cross-sectional area (DCSA); and spinal curvature (i.e. lumbar lordosis [LL] and L1-L3-L5 angle [LA]).

RESULTS

Major differences (>5%) between standing MRI and BS-MRI methods were observed in DCSA, DH, and LL. Major differences between standing and axial loaded MRIs were observed only in DCSA and LA. Although BS-MRIs demonstrate an image of the lumbar spine curvature (i.e. LA) which is closer to that when standing than axial-loaded MRIs, it is likely to overestimate both narrowing of dural sac and extent of LL.

CONCLUSION

Using a compression device with a BS to simulate weight-bearing on the lumbar spine is not recommended due to: (i) overestimation of the narrowing of the dural sac and extent of LL; and (ii) underestimation of loss of disc height. Supine axial-loading produced DCSA and DH which were strongly correlated with those detected with standing MRIs. Exceptions were that LL and LA were underestimated.

Correlation Between Dural Sac Size in Dynamic Magnetic Resonance Imaging and Clinical Symptoms in Patients with Lumbar Spinal Stenosis

OBJECTIVE

To assess the dynamic change of the dural sac size in patients with lumbar spinal stenosis (LSS) from supine to standing position and their correlation with clinical symptoms.

METHODS

A total of 110 patients with LSS were prospectively enrolled to undergo both supine (0°) and standing (78°) magnetic resonance imaging (MRI). Dural sac cross-sectional area (DCSA) and dural sac anteroposterior diameter (DAPD) at the most constricted spinal level in supine and standing MRI were measured and compared. Clinical symptoms were assessed by duration of disease, claudication distance, visual analog scale (VAS) score of leg pain, and Chinese Oswestry Disability Index score of low back pain. The correlation between the parameters and clinical symptoms was analyzed by Pearson correlation coefficient (r).

RESULTS

Mean minimum DCSA and DAPD in the standing position were significantly smaller (both P < 0.01) than in the supine position. DCSA and DAPD in standing MRI and their changes had better correlation with the intermittent claudication distance and VAS score of leg pain than in the supine position. A more than 15 mm² reduction of DSCA was observed in patients with shorter claudication distance and more severe VAS score of leg pain (both P < 0.01).

CONCLUSIONS

Dural sac size on MRI was reduced significantly from supine to standing position. Standing MRI and the changes of DCSA significantly correlated with claudication distance and VAS score of leg pain in patients with LSS. Therefore, standing MRI provides more radiologic information correlating with clinical symptoms in patients with LSS than supine MRI.