Considering hounsfield units in native CT- scans for diagnosing spondylodiscitis

Area of Science:

• Radiology
• Medical Imaging
• Spinal Diagnostics

Background:

• Current data limits the use of native Computer Tomography (CT) scans as a diagnostic tool for spondylodiscitis, often reserving them for bony destruction assessment or when Magnetic Resonance Imaging (MRI) is contraindicated.
• The diagnostic value of CT scans in early spondylodiscitis detection, particularly concerning density distribution patterns, remains underexplored.

Purpose of the Study:

• To investigate if spondylodiscitis causes a significant, measurable pattern in the density distribution of affected vertebral bodies and intervertebral discs using Hounsfield Units (HU) on native CT scans.
• To determine if HU measurements can serve as a valuable tool for the early diagnosis of spondylodiscitis.

Main Methods:

• A retrospective analysis of 136 patients treated for spondylodiscitis was conducted.
• Data from patients with both MRI and CT scans of the spine were included.
• Hounsfield Units (HU) were measured in axial CT planes for affected intervertebral discs and vertebral bodies, as well as for unaffected adjacent levels as a reference.

Main Results:

• Affected intervertebral discs showed a significant average decrease in HU of 26.0% compared to unaffected adjacent discs (p < 0.001).
• Affected vertebral bodies demonstrated a significant average increase in HU of 33.77% compared to unaffected adjacent vertebrae (p < 0.001).
• These HU changes were consistent across different spinal regions (cervical, thoracic, lumbar) and independent of the degree of bony destruction.

Conclusions:

• A reduction in intervertebral disc HU by approximately 25% and/or an increase in vertebral body HU by approximately 30% compared to adjacent structures is indicative of spondylodiscitis.
• These quantitative CT findings can aid in the early diagnosis of spondylodiscitis, even in the absence of apparent bone destruction and irrespective of the affected spinal location.