An Ex Vivo Study of Filum Terminale in Children and Fetuses Based on Optical Coherence Tomography.

Objective: To distinguish ex vivo normal and abnormal filum terminale (FT) in pathology based on optical coherence tomography (OCT). Methods: A total of 14 ex vivo FTs, freshly imaged via OCT after being cut, were excised from the scanned region for histopathological examination (HPE). Qualitative analysis was performed by 2 blinded assessors. Results: We performed OCT imaging of all specimens and validated them qualitatively. In the fetal FTs, we observed large amounts of fibrous tissue scattered throughout with a few capillaries but no adipose tissue. In tight filum terminale syndrome (TFTS), adipose infiltration and capillaries were significantly increased, with obvious fibroplasia and disarrangement. OCT images showed increased adipose tissue in which the adipocytes were arranged in a grid-like pattern; dense, disordered fibrous tissue and vascular-like tissue were present. The diagnostic results of OCT and HPE were consistent (Kappa = 0.659; P = .009, <.01), and there was no statistically significant difference in diagnosing TFTS using a Chi-square test (P > .05). The area under the curve (AUC) for OCT (AUC = 0.966; 95% CI, 0.903 to 1.000) was better than magnetic resonance imaging (MRI) (AUC = 0.649; 95% CI, 0.403 to 0.896). Conclusion: OCT can quickly obtain clear images of FT's inner structure, contribute to diagnosing TFTS and will be an indispensable complement to MRI and HPE. More FT sample studies in vivo are needed to confirm the high accuracy rate of OCT.