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Updated: Mar 10, 2026
Registered Bioimaging of Nanomaterials for Diagnostic and Therapeutic Monitoring
Published on: December 9, 2010
Magnetic Resonance Imaging Signal Characteristics of Medishield: Early Postoperative Profile in a Rabbit
Edin Nevzati1, Jatta Berberat1, Jehuda Soleman1
1Department of Neurosurgery, Kantonsspital Aurau, Aarau, Switzerland.
Objective:
Application of Medishield to the nerve root is common during spinal surgery to create a mechanical barrier from pain mediators and reduce scar formation. However, Medishield's signal characteristics on magnetic resonance imaging (MRI) have not yet been examined.
Methods:
Microsurgical interlaminotomy was performed on 2 lower lumbar segments in 17 adult New Zealand white rabbits. After dural exposure, applications of 1 mL (autologous blood clot or Medishield) were randomized for each level. On postoperative days 1 through 3, various MRI sequences in 1.5T were performed including T1-weighted, T2-w, T1-gadolinium-weighted, susceptibility-weighted and turbo inversion recovery magnitude (TIRM) sequence. Signaling characteristics were analyzed by 3 blinded observers. Inter-rater agreement was calculated using Fleiss's kappa coefficient (κ). Positive and negative likelihood ratios in detecting Medishield by MRI were determined.
Results:
Of 24 MRIs performed, TIRM sequence identified Medishield with the highest likelihood ratio. Medishield's positive likelihood ratio was highest (5.8) on postoperative day 1 with interobserver agreement of 93% (κ = 0.75); these rates declined to 2.5 and 1.4 on postoperative days 2 and 3 with interobserver agreements of 71% (κ = 0.43) and 83% (κ = 0.67), respectively. Medishield adherence was confirmed in each rabbit by histologic examinations.
Conclusion:
Understanding that radiologic detection of Medishield diminished over time as its signal characteristics became less distinguishable from a blood clot is essential in clinical practice. Medishield was detected on postoperative day 1 but not 2 days later after hemodynamic changes had occurred. These results may provide a guide for postoperative findings, such as differential diagnosis of hematoma.
Insights
Magnetic resonance imaging (MRI) can detect Medishield nerve root barrier on postoperative day 1, but detection decreases over time. This study examined Medishield
Area of Science:
- Neurosurgery
- Radiology
- Biomaterials
Background:
- Medishield is applied to nerve roots during spinal surgery to prevent scarring and block pain mediators.
- The magnetic resonance imaging (MRI) signal characteristics of Medishield have not been previously evaluated.
Purpose of the Study:
- To assess the MRI signal characteristics of Medishield.
- To determine the detectability of Medishield using various MRI sequences over time.
Main Methods:
- Microsurgical interlaminotomy was performed on rabbit lumbar segments.
- Medishield and autologous blood clot were applied and randomized.
- Postoperative MRIs were acquired on days 1-3 using multiple sequences (T1-weighted, T2-w, T1-gadolinium-weighted, susceptibility-weighted, TIRM).
- Signal characteristics were analyzed by blinded observers, and likelihood ratios were calculated.
Main Results:
- The Turbo Inversion Recovery Magnitude (TIRM) sequence demonstrated the highest likelihood ratio for Medishield detection.
- Medishield was most detectable on postoperative day 1 (positive likelihood ratio = 5.8) with high interobserver agreement (93%).
- Detectability and interobserver agreement decreased significantly on postoperative days 2 and 3.
Conclusions:
- Radiologic detection of Medishield diminishes postoperatively as its signal becomes less distinct from a blood clot.
- Medishield is detectable on day 1 but not by day 3 due to hemodynamic changes.
- Findings aid in the postoperative interpretation of imaging, including differentiating Medishield from hematoma.
