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Updated: Jan 12, 2026
Intraoperative Ultrasound in Spinal Surgery
Published on: August 17, 2022
Performance of magnetic resonance imaging in discriminating between intra- and extradural versus extradural-only
Seungbo Lee1, Hyun-Jun Jang2, Sung Jun Ahn3
1Department of Radiology, Gangnam Severance Hospital, Research Institute of Radiological Science, Center for Clinical Imaging Data Science, Yonsei University College of Medicine, Seoul, Korea; Department of Radiology, Shinsegae Seoul Hospital, Seoul, Korea.
Study Design:
Retrospective cohort study.
Summary Of Background Data:
Preoperative identification of intradural extension in nerve sheath tumors (NSTs) is crucial for surgical planning. While MRI is the primary imaging modality, reliable markers distinguishing intra- and extradural (IED) from extradural-only (EDO) NSTs remain uncertain.
Objective:
To assess the diagnostic utility of MRI features in differentiating IED from EDO NSTs.
Methods:
Forty-five patients with confirmed IED or EDO NSTs were retrospectively reviewed. Two radiologists analyzed MRI features, including cerebrospinal fluid (CSF) claw sign and candy shape, with interobserver agreement assessed. Fisher's exact test and receiver operating characteristic analysis were performed.
Results:
Nine cases were IED, and 36 were EDO NSTs. Interobserver agreements of all imaging features between the two radiologists were excellent. IED tumors showed significantly more CSF claw sign and candy shape, and the prediction performance was assessed for these two imaging features. The CSF claw sign showed AUC values of 0.875 and 0.889, while the candy shape showed AUC values of 0.847 and 0.958.
Conclusion:
CSF claw sign and candy shape are useful MRI findings to differentiate between IED and EDO NSTs.
