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Magnetic resonance imaging in a spinal abscess model. Preliminary report
V M Runge1, N M Williams, C Lee
1University of Kentucky, Lexington 40536-0098, USA. runge@pop.uky.edu
Rational And Objectives:
Magnetic resonance (MR) scan technique and lesion detectability were evaluated using a newly developed spinal abscess model in the New Zealand White rabbit.
Methods:
To create the lesion, an epidural needle was inserted under fluoroscopic guidance in the lumbar region and advanced to penetrate the ligamentum flavum. Next, polyethylene tubing was fed through the needle into the epidural space. A mixed suspension of Staphylococcus aureus (Cowan I) and blue polystyrene microspheres then was injected. Lesions were evaluated by MR imaging in four animals at multiple time points (3, 6, and 9 days). Imaging was performed at 1.5 tesla using a surface coil. Precontrast T2-and T1-weighted scans were first obtained. The T1-weighted scans were acquired both with and without fat saturation, and were repeated after intravenous contrast administration. The contrast agent used was gadoteridol (gadolinium HP-DO3A or ProHance) at a dose of 0.3 mmol/kg.
Results:
On prospective film review, postcontrast scans proved superior for lesion detection. A spinal abscess could be identified postcontrast in all cases, irrespective of the use of fat saturation. The next best imaging technique for lesion detection was the T2-weighted scan, with 5 of 8 lesions noted thereon. Visualization of lesion margins proved to be a primary factor in prospective lesion identification. Region of interest image analysis demonstrated the postcontrast scans to be superior to all precontrast scan techniques for conspicuity of the interface between the abscess and the compressed spinal cord, with these results statistically significant. The lesions were characterized histologically by infiltrates of heterophils into the meninges and outer spinal cord with accompanying mild hemorrhage, fibrin exudation, and bacterial colonies. The lesions in three animals were confirmed to be in the epidural space, with the lesion in one animal in the subdural space.
Conclusions:
The current animal model was developed to study spine infection and, specifically, imaging characteristics and lesion detectability on MR. With the increased use of epidural catheters for pain management and the large number of acquired immunodeficiency syndrome cases, epidural infection is becoming an increasingly important clinical problem. Imaging technique, in particular the use of intravenous contrast, is critical for lesion detection and evaluation.
Insights
This study developed a rabbit model for spinal abscesses, finding that contrast-enhanced magnetic resonance (MR) scans are crucial for detecting these infections. Postcontrast imaging significantly improves visualization of spinal abscesses and their margins.
Area of Science:
- Radiology
- Infectious Disease
- Animal Models
Background:
- Epidural infection is an increasing clinical concern, particularly with the rise of epidural catheter use and acquired immunodeficiency syndrome (AIDS) cases.
- Effective diagnostic imaging is essential for timely detection and management of spinal infections.
Purpose of the Study:
- To evaluate magnetic resonance (MR) scan techniques for lesion detectability in a newly developed spinal abscess model.
- To assess the efficacy of different MR imaging sequences and contrast administration for identifying spinal epidural infections.
Main Methods:
- A spinal abscess model was created in New Zealand White rabbits by injecting Staphylococcus aureus and microspheres into the epidural space.
- MR imaging was performed at 1.5 tesla using T2-weighted, T1-weighted (with and without fat saturation), and postcontrast T1-weighted sequences.
- Gadoteridol was administered intravenously as the contrast agent at a dose of 0.3 mmol/kg.
Main Results:
- Postcontrast MR scans were superior for detecting spinal abscesses, identifying lesions in all cases.
- T2-weighted scans were the next most effective, detecting 5 of 8 lesions.
- Enhanced visualization of lesion margins and the interface between the abscess and spinal cord was achieved with postcontrast imaging, with statistically significant results.
Conclusions:
- The developed animal model is effective for studying spinal infections and MR imaging characteristics.
- Intravenous contrast administration is critical for accurate lesion detection and evaluation in spinal epidural infections.
- This research highlights the importance of advanced MR imaging techniques in diagnosing challenging clinical scenarios like epidural abscesses.