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Belly Up vs. Belly Down MRI | What are we missing? Prone MRI vs. Supine MRI in Low Back Pain Patients

Prone MRI

Goal of the Study?

It is not uncommon to encounter remarkable pain patients with unremarkable MRI findings in clinical settings. Conventional MRI is done lying down, facing up (supine) in a recumbent and off-loading environment. This group of researchers out of The University Hospital Sanitas La Moraleja in Madrid, Spain, wanted to compare supine (face-up) MRI to prone (face-down) MRI in lower back pain patients to see the difference in the MRI findings.


Why are they doing this study?

Posture does matter in most cases of lower back pain. Patients complain of symptom exacerbation in different positions like sitting, lying down in particular positions, standing, walking or bending. However, the standard, thought to be the ‘gold standard’, is supine MRI. However, this position often relieves a patient’s back and/or leg pain symptoms. In this research study published in Pain Physician1 the group of researchers wanted to see if there were MRI changes to the spine when the patients were lying face down vs face up.


What was done in this study?

Nineteen low back pain sufferers, with a mean age of 48.7 years old, with an average numerical pain scale of 6.5 out of a scale of 0-10. They looked at radiological findings and the changes related to disc bulging, ligamentum flavum buckling and/or thickening. The researchers also looked at varying grades of spondylolisthesis and facet joint subluxations resulting in foraminal stenosis. In other words, they were looking at how much the vertebra slid and how much more narrow the exiting holes became when the patients lie on their stomachs instead of lying on their backs.


What did they find?

Four patterns of changes were seen when people were imaged on their stomachs rather than their backs. They found that in over 50% of the people, disc problems were only seen in the prone position. They saw 52.6% of cases showing increased thickness in the ligamentum flavum in the prone position that was otherwise not seen in the supine position. They also saw varying degrees of listhesis (slippage of vertebrae) and facet joint spacing differences in 26.3% of those lying on their stomach compared to those lying on their backs.


Why do these findings matter?

This simply designed study has revealed postural anatomical changes related to the imaging position. This would seem obvious from a layman’s standpoint; however, medicine has relied so much on supine MRI imaging as the gold standard position to investigate pathoanatomical findings. There is very often a clinical disconnect between a patient’s symptoms and the associated pathology seen in MRI, likely because MRI imaging has been standardized to be taken belly-up. Many spine problems are missed or misguided in treatment approaches if a proper assessment (including appropriate MRI positioning) is not conducted. Research like this allows a better match of pathoanatomical findings and the associated treatments.


At Dynamic Disc Designs, we create dynamic human anatomy models showing a dynamic disc that changes shape and position with different postures as well as the ligamentum flavum thickening under extension. Explore how you can connect a patient to their postional symptoms with a ddd model.

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