Morphologic Characteristics and Clinical Significance of Computed Tomography and Magnetic Resonance Imaging Findings of Spinal Epidural Gas

Abstract

Objective: To evaluate the morphologic characteristics and clinical significance of epidural gas based on computed tomography (CT) and magnetic resonance imaging (MRI) findings and to determine their relationship with radiculopathy.

Materials and methods: Between March 2009 and November 2018, 110 epidural gas lesions were identified in 103 patients who underwent both CT and MRI for suspected herniated disc in the authors' institution. Patterns of epidural gas were classified as air pseudocyst, air cyst, air-contained disc herniation, and honeycomb-like air cyst. These gas patterns were compared, and possible correlations between these gas patterns and radiculopathy were evaluated.

Results: Overall agreement between CT and MRI findings for evaluation of all lesions and for differentiation of epidural gases was good (kappa [κ] = 0.775). Air pseudocysts demonstrated a moderate correlation (κ = 0.496) and air cysts showed a good correlation (κ = 0.661) with radiculopathy on MRI, whereas air-contained disc herniation and honeycomb-like cysts demonstrated a strong correlation (κ = 0.810 and 0.927, respectively) with radiculopathy on MRI.

Conclusions: This study's results help delineate new classifications of epidural gases. In addition, lumbar epidural gas with disc material (e.g., air-contained disc herniation and honeycomb-like cysts) on MRI was associated with radiculopathy.

Keywords: Cysts; Intervertebral disc; Intervertebral disc degeneration; Magnetic resonance imaging; Spine.