Diagnostic and Interventional Radiology
Modality-based (US, CT, MRI, PET-CT) Imaging - Original Article

Correlation of 18F-FDG PET/CT uptake with severity of MRI findings and epidural steroid injection sites in patients with symptomatic degenerative disease of the lumbar spine: a retrospective study

1.

NYU Langone Health, New York University School of Medicine, New York, USA

2.

Department of Radiology, NYU Langone Health, Musculoskeletal Division Langone Orthopedic Hospital, New York, USA

Diagn Interv Radiol 2021; 27: 580-586
DOI: 10.5152/dir.2021.20438
Read: 98 Downloads: 35 Published: 20 August 2020

PURPOSE 
We aimed to retrospectively correlate 18F-fluorodeoxyglucose (18F-FDG) metabolic activity with lumbar spine magnetic resonance imaging (MRI) findings and epidural steroid injection sites in patients with symptomatic degenerative disease of the lumbar spine.

METHODS
A database search was conducted for patients receiving epidural injections <12 months after a positron emission tomography/computed tomography (PET/CT). Maximum standard uptake values (SUVmax) were measured at the facet joints, neural foramina, and spinal canal. Severity of facet arthrosis, disc degeneration, neuroforaminal, and canal stenosis was determined on MRI using previously described grading scales. Spearman rank coefficient assessed association between PET/CT FDG uptake and severity of MRI findings. The SUVmax was also compared with injection sites.

RESULTS
Twenty-five patients were included, comprising MRI (n=19) and injection (n=22 patients; 18 interlaminar, 8 transforaminal) groups. Injections were performed an average of 2.6 months after PET/CT. The greatest SUVmax occurred at the L5-S1 spinal canal (mean SUVmax = 2.25). A statistically significant, positive correlation between uptake and grade of spinal canal stenosis was seen only at L4-L5 (r=0.60, p = 0.007). No other significant association was found with spinal canal or neuroforaminal stenosis, or grade of facet joint or disc degeneration. All patients reported symptomatic improvement after injections with mean pain score improvement of 4.4 on a 10-point scale (SD, 2.9). There was moderate agreement between sites of epidural injection and highest SUVmax (κ= 0.591, p < 0.001). 

CONCLUSION
18F-FDG metabolic activity on PET/CT corresponds with MRI findings about the lumbar spinal column, but there is no significant correlation between severity of MRI findings and radiotracer uptake. Given the moderate agreement between metabolic activity and levels of symptomatic spinal stenosis, further studies are warranted to fully evaluate the diagnostic potential of FDG PET/CT as a surrogate for guiding epidural injections.

You may cite this article as: Lam M, Burke CJ, Walter WR. Correlation of 18F-FDG PET/CT uptake with severity of MRI findings and epidural steroid injection sites in patients with symptomatic degenerative disease of the lumbar spine: a retrospective study. Diagn Interv Radiol 2021; 27:580-586

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