Cervical cancer is the eleventh most common cancer in the UK, especially for women under 35. In developed countries, cervical cancer is diagnosed by performing colposcopy. Contrast is enhanced by spraying dilute acetic acid onto the surface of the tissue. In the past decades, it has been shown that abnormal cervical epithelium turns opaque white upon contact with this weak acid whereas normal epithelium is generally not affected. This mechanism is known as aceto-whitening. However, the exact mechanism of this phenomenon is not fully known. In this study, OCT using near infrared light was used to quantify depth-resolved kinetics of aceto-whitening in a simple squamous epithelium model: rabbit cornea. We have found that both the epithelium and stroma brighten with approximately the same time course, reaching a peak reflectivity at about 50 seconds. The most significant increase in reflectivity was seen in the first 20 seconds upon the application of acid, and was measured to be 11dB. This result is compared with phosphate buffered saline solution, which was shown to exhibit no effect. Lactic acid, an alpha-hydroxy acid, has been reported as a negative control for aceto-whitening. However, our OCT results showed a significant epithelial brightening effect of approximately 8 dB in the first 20 seconds. The key difference with acetic acid is the lack of brightening in the corneal stroma. This could be due to inability to permeate through the basal lamina between corneal epithelium and stroma or lack of interaction with stromal keratocytes.
[1]
J Cuzick,et al.
Cytokeratin expression and acetowhite change in cervical epithelium.
,
1994,
Journal of clinical pathology.
[2]
R. Lotan,et al.
Contrast agents for confocal microscopy: how simple chemicals affect confocal images of normal and cancer cells in suspension.
,
2002,
Journal of biomedical optics.
[3]
R. Lotan,et al.
Laser scanning confocal microscopy of cervical tissue before and after application of acetic acid.
,
2000,
American journal of obstetrics and gynecology.
[4]
Julia Gallwas,et al.
Validation of an ex vivo human cervical tissue model for optical imaging studies
,
2012,
Lasers in surgery and medicine.
[5]
Christian Dannecker,et al.
Optical coherence tomography for the diagnosis of cervical intraepithelial neoplasia
,
2011,
Lasers in surgery and medicine.
[6]
C. Balas,et al.
In Vivo Molecular Imaging of Cervical Neoplasia Using Acetic Acid as Biomarker
,
2008,
IEEE Journal of Selected Topics in Quantum Electronics.
[7]
Allan B MacLean.
Acetowhite epithelium.
,
2004,
Gynecologic oncology.
[8]
Judith R Mourant,et al.
Effects of acetic acid on light scattering from cells.
,
2012,
Journal of biomedical optics.