Reporting of Facet Joint Inflammation in Lumbar Spine MRI Studies in Patients With Low Back Pain

Abstract

Study design: Retrospective.

Objective: We aimed to assess the frequency of facet joint inflammatory features noted in routine radiology reports of lumbar spine magnetic resonance imaging (MRI) studies among patients with chronic low back pain.

Summary of background data: Facet joint arthropathy is one of the most common causes of chronic low back pain. It may encompass various inflammatory imaging characteristics, such as facet joint effusion, bone marrow edema, and soft tissue edema. The extent to which radiology reports mention inflammatory features of the lumbar facet joints and the accuracy of these reports have not been investigated.

Materials and methods: The authors performed a chart review on 49 subjects with previous facet-related interventions ( i.e . medial branch blocks or intra-articular facet joint injection) and MRI available in the medical record. One senior musculoskeletal radiologist and a musculoskeletal radiology fellow graded the inflammatory features using a published facet joint inflammation grading system [Gold Standard (GS)]. The authors identified the inflammatory markers mentioned in the radiology reports and calculated the sensitivity and positive predictive value of the radiology reports compared with GS readings.

Results: Compared with the GS, the sensitivity of radiology reports for facet joint effusion, bone marrow, and soft tissue edema ranged from 6% to 22%, and the positive predictive value ranged from 25% to 100%. L4/5 had the highest number of cases with inflammatory features noted on the reports.

Conclusion: Inflammatory findings, such as facet joint effusion, bone marrow edema, and soft tissue edema, are not commonly identified in radiology reports. Further investigations are needed to determine the clinical importance of MRI-detected lumbar facet joint inflammatory features as a potential mechanism of nociception and as a predictor of outcomes following injections or other therapies.

Figure 1.. Diagram of the screening process of the included subjects.

Inclusion and exclusion criteria were applied to the original group of 380 cases to obtain a final sample of 50 subjects. One subject was excluded because their MRI report was unavailable in Epic, leaving us with 49 subjects included in the final analysis.

Figure 2.. Examples of MRIs with discordant and concordant grades when comparing gold standard readings and radiology reports.

A. Discordant: Left Parasagittal STIR (left) and Axial T2-weighted MR demonstrate hypertrophic changes of the facet joints bilaterally, with bone marrow edema in the left pedicle of L4 (arrow) and adjacent soft tissue edema (asterisk), per gold standard reading. The official radiology report described “Moderate to severe bilateral facet joint and ligamentum flavum hypertrophy,” although neither the osseous nor soft tissue edema was described. B. Discordant: Left Parasagittal STIR (left) and Axial T2-weighted MR demonstrate a large left facet effusion (arrows), per gold standard reading. The official radiology report described “facet changes” without mentioning the facet effusion. C. Concordant: Right Parasagittal STIR (left) and Axial T2-weighted MR demonstrate bone marrow edema within the pedicles of L3 and L4 (arrows), per gold standard reading. Note facet arthropathy with severe subchondral remodeling (asterisks). The official radiology report described “severe facet hypertrophy associated with edema within the bilateral pedicles.” D. Concordant: Right Parasagittal STIR (left) and Axial T2-weighted MR demonstrate a moderate right facet effusion at L4-L5 (arrows), per gold standard reading. The official radiology report described “fluid within the right facet joint with a small extra canalicular synovial cyst.” Figure 2A. Bone marrow edema in the left pedicle of L4 (arrow) Adjacent soft-tissue edema (asterisk) Figure 2B. Large left facet effusion (arrows) Figure 2C. Bone marrow edema within the pedicles of L3 and L4 (arrows) Facet arthropathy with severe subchondral remodeling (asterisks) Figure 2D. Right facet effusion at L4-L5 (arrows)

Figure 2.. Examples of MRIs with discordant and concordant grades when comparing gold standard readings and radiology reports.

A. Discordant: Left Parasagittal STIR (left) and Axial T2-weighted MR demonstrate hypertrophic changes of the facet joints bilaterally, with bone marrow edema in the left pedicle of L4 (arrow) and adjacent soft tissue edema (asterisk), per gold standard reading. The official radiology report described “Moderate to severe bilateral facet joint and ligamentum flavum hypertrophy,” although neither the osseous nor soft tissue edema was described. B. Discordant: Left Parasagittal STIR (left) and Axial T2-weighted MR demonstrate a large left facet effusion (arrows), per gold standard reading. The official radiology report described “facet changes” without mentioning the facet effusion. C. Concordant: Right Parasagittal STIR (left) and Axial T2-weighted MR demonstrate bone marrow edema within the pedicles of L3 and L4 (arrows), per gold standard reading. Note facet arthropathy with severe subchondral remodeling (asterisks). The official radiology report described “severe facet hypertrophy associated with edema within the bilateral pedicles.” D. Concordant: Right Parasagittal STIR (left) and Axial T2-weighted MR demonstrate a moderate right facet effusion at L4-L5 (arrows), per gold standard reading. The official radiology report described “fluid within the right facet joint with a small extra canalicular synovial cyst.” Figure 2A. Bone marrow edema in the left pedicle of L4 (arrow) Adjacent soft-tissue edema (asterisk) Figure 2B. Large left facet effusion (arrows) Figure 2C. Bone marrow edema within the pedicles of L3 and L4 (arrows) Facet arthropathy with severe subchondral remodeling (asterisks) Figure 2D. Right facet effusion at L4-L5 (arrows)

Figure 3.. The number of cases with identified lumbar facet joint inflammatory features based on MRI radiology reports.

A bar graph reporting the number of cases where the Gold Standard (GS) readers and the official radiologist reported inflammatory features at each lumbar spine level. The GS readers noted more inflammation than the radiology reports at all three levels, and the L4/5 had the most inflammation. = Gold standard reader = Radiology report