Comparison of [18F] FDG-PET/MRI and Clinical Findings for Assessment of Suspected Lumbar Facet Joint Pain: A Prospective Study to Characterize Candidate Nonanatomic Imaging Biomarkers and Potential Impact on Management.

BACKGROUND AND PURPOSE: Prior retrospective studies have suggested that both T2 hyperintensity and gadolinium enhancement on fat-suppressed MR imaging are associated with lumbar facet joint pain, but prospective evaluation of FDG-PET/MR imaging with a standardized protocol and correlation to clinical findings are lacking. The primary aim was to prospectively assess a standardized FDG-PET/MRI protocol in patients with suspected facetogenic low back pain, with determination of the concordance of imaging and clinical findings. MATERIALS AND METHODS: Ten patients with clinically suspected facetogenic low back pain were prospectively recruited with a designation of specific facet joints implicated clinically. Subsequently, patients underwent an FDG-PET/MR imaging examination with gadolinium. Each facet joint was graded for perifacet signal change on MR imaging and FDG activity. The frequency and correlation of MR imaging, FDG-PET, and clinical findings were determined. RESULTS: FDG activity showed high concordance with high overall MR imaging scores (concordance correlation coefficient = 0.79). There was concordance of the clinical side of pain with the side of high overall MR imaging scores and increased FDG activity on 12/20 (60%) sides. Both a high overall MR imaging score (concordance correlation coefficient = 0.12) and FDG-PET findings positive for increased activity (concordance correlation coefficient = 0.10) had low concordance with the specific clinically implicated facet joints. Increased FDG activity or high MR imaging scores or both were present in only 10/29 (34%) facet joints that had been clinically selected for percutaneous intervention. Eleven (11%) facet joints that had not been selected for treatment demonstrated these imaging findings. CONCLUSIONS: There was low concordance of perifacet signal change and FDG activity with clinically implicated facet joints. This could indicate either the potential to change patient management or a lack of biomarker accuracy. Therefore, additional larger randomized studies with the use of comparative medial branch blocks would be useful to further investigate the clinical utility of these findings.

Partial lumbosacral transitional vertebra resection for contralateral facetogenic pain.

STUDY DESIGN: Case report of surgically treated mechanical low back pain from the facet joint contralateral to a unilateral anomalous lumbosacral articulation (Bertolotti's syndrome). OBJECTIVES: To describe the clinical presentation, diagnostic evaluation, and management of facet-related low back pain in a 17-year-old cheerleader and its successful surgical treatment with resection of a contralateral anomalous articulation. SUMMARY OF BACKGROUND DATA: Lumbosacral transitional vertebrae are common in the general population. Bertolotti's syndrome is mechanical low back pain associated with these transitional segments. Little is known about the pathophysiology and mechanics of these vertebral segments and their propensity to be pain generators. Treatment of this syndrome is controversial, and surgical intervention has been infrequently reported. METHOD: A retrospective chart analysis and radiographic review were performed. RESULTS: Repeated fluoroscopically guided injections implicated a symptomatic L6-S1 facet joint contralateral to an anomalous lumbosacral articulation. Eventually, a successful surgical outcome was achieved with resection of the anomalous articulation. CONCLUSION: Clinicians should consider the possibility that mechanical low back pain may occur from a facet contralateral to a unilateral anomalous lumbosacral articulation, even in a young patient. Although reports of surgical treatment of Bertolotti's syndrome are infrequent, resection of the anomalous articulation provided excellent results in this patient, presumably because of reduced stresses on the symptomatic facet.

31P nuclear magnetic resonance spectroscopic evidence that canine nucleus pulposus and anulus fibrosus cells differ in principal organophosphorus biomolecules.

STUDY DESIGN: 31P Nuclear magnetic resonance spectroscopy was used to compare amounts and types of principal organophosphorus biomolecules in canine intervertebral disc tissues ex vivo. OBJECTIVE: The goal of this study was to compare principal organophosphorus biomolecules in nucleus pulposus, anulus fibrosus, and in isolated nucleus pulposus and anulus fibrosus cells. SUMMARY OF BACKGROUND DATA: There is no published information on principal organophosphorus biomolecules in disc tissues for any animal. METHODS: Canine nucleus pulposus and anulus fibrosus were shown by hematoxylin-eosin staining to be healthy tissues characteristic of adult dogs. Viable cells liberated from these disc tissues by sequential protease digestion were directly visualized by light microscopy of wet mounts. 31P nuclear magnetic resonance spectra were recorded at room temperature for 12 hours according to conventional published methods. RESULTS: No resonances were detected for intact nucleus pulposus and anulus fibrosus tissue. 31P nuclear magnetic resonance spectra of viable chondrocyte-like cells from anulus fibrosus featured two distinctive resonance peaks consistent with phosphomonoesters and phosphodiesters. After undigested anulus fibrosus was removed, no resonances were detected. 31P nuclear magnetic resonance spectra of viable chondrocyte-like cells from nucleus pulposus before and after removal of undigested tissue featured only one resonance peak consistent with phosphodiesters. CONCLUSIONS: A phosphomonoester-containing biomolecule is present in healthy canine anulus fibrosus tissue but not in nucleus pulposus tissue, nor in nucleus pulposus cells or anulus fibrosus cells. A phosphodiester-containing biomolecule is present principally in nucleus pulposus cells. This study demonstrated that canine chondrocyte-like cells from nucleus pulposus and anulus fibrosus are phenotypically distinctive in principal organophosphorus biomolecules.

Quantification of lumbar intradiscal deformation during flexion and extension, by mathematical analysis of magnetic resonance imaging pixel intensity profiles.

STUDY DESIGN: A magnetic resonance imaging study of the internal kinematic response of normal lumbar intervertebral discs to non-weight-bearing flexion and extension. OBJECTIVES: To quantify the pattern of magnetic resonance imaging pixel intensity variation across discs, and noninvasively monitor displacement of the nucleus pulposus during sagittal-plane movements. SUMMARY OF BACKGROUND DATA: Invasive techniques used to study intradiscal movements of the nucleus pulposus have suggested that it moves posteriorly during flexion and anteriorly during extension. A noninvasive study based on magnetic resonance images gave similar results for normal young women. Quantification has been problematic, and the invasive procedures may have altered disc dynamics. METHODS: Ten male subjects (age, 21-38 years) with healthy backs were positioned in a magnetic resonance imaging portal with their lumbar spine stabilized in flexion and extension by supporting pads. For each disc, a T2-weighted image was obtained, as was a computer-generated profile of pixel intensities along a horizontal mid-discal transect. Mathematical curve-fitting regression analysis was used to characterize the shape of the intensity profile and to compute the point of maximum pixel intensity. RESULTS: A single equation fitted the profile for all normal discs. The intensity peak shifted posteriorly during flexion, anteriorly during extension. CONCLUSIONS: Automated mathematical modeling of magnetic resonance imaging pixel data can be used to describe the fundamental shape of the pixel intensity profile across a normal lumbar disc, to determine the precise location of the site of maximum pixel intensity, and to measure the movement of this peak with flexion and extension. This technique may be of value in recognizing incipient degenerative changes in lumbar discs.