Abstract
Background: A positive surgical margin (PSM) following oral cancer resection results in local recurrence and poor prognosis. Mono-block tumor specimens, especially from the tumor base, are difficult to evaluate. This inaccurate sampling ultimately leads to a false pathological diagnosis. Lugol's iodine (I2-IK)-enhanced micro-CT is an emerging method to image tumor specimens. This study explores the feasibility of I2-IK-enhanced micro-CT to evaluate the surgical margin for tongue squamous cell carcinoma (TSCC) specimens and to further seek optimal staining parameters.
Methods: Rabbit tongue tissues and human TSCC samples were imaged via I2-IK-enhanced micro-CT. The optimal I2-IK concentration and staining time were determined before clinical application using tissue shrinkage, micro-CT image quality, and effect on pathological diagnosis as assessment criteria. Next, 6 TSCC specimens were used to verify the process feasibility of surgical margin imaging with the optimal parameters. Finally, the possible reason by which I2-IK could enhance micro-CT imaging was validated in vitro.
Results: I2-IK staining influenced specimen shrinkage, micro-CT image quality, and pathological image quality in a concentration- and time-dependent manner. After comprehensively considering these indicators, 3% I2-IK staining for 48 and 12 h were found to be optimal for rabbit tongue tissues and TSCC samples, respectively. This method could provide a detailed 3-D structure of TSCC samples compared with H&E sections. Moreover, tumor and normal tissues could be differentiated by their glycogen content, which has high affinity with I2-IK.
Conclusions: I2-IK-enhanced micro-CT could, thus, indicate the tumor margin and assist pathological sampling in patients with TSCC postoperation.
Keywords: I2-IK, TSCC specimens, micro-CT, pathological examination, surgical margin.
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Figure 1 I2-IK-enhanced micro-CT image for rabbit tongue tissues. (A) Tissue shrinkage during formalin fixation and I2-IK staining (tissue volume normalized to 100%). (B) CNR value of micro-CT image at different times with different concentrations of I2-IK. (C) Micro-CT image data at different times with 3% and 7% I2-IK staining. (D) Micro-CT image and H&E image of the same sections (the structures in the red box indicate mucous, muscle fibers, and blood vessels). (E) Tissue shrinkage during H&E staining. (F) The quality of H&E images with different concentrations of I2-IK. (**P < 0.01, ***P < 0.001).
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