Localization and staging of cervical intraepithelial neoplasia using double ratio fluorescence imaging

A phase zero evaluation of a new fluorescence imaging technique for diagnosing cervical intraepithelial neoplasia (CIN) was performed. The fluorescence imaging prototype performed quantitative imaging of Protoporphyrin induced by a topically applied aminolevulinic acid using double ratio (DR) fluorescence imaging technique developed by our group. A total of 38 patients were in the protocol, with 16 colposcopically selected for biopsy. Fluorescence images of these 16 patients were taken, 19 sites were biopsied, and the disease was staged histopathologically. DR fluorescence imaging of the cervix using our general purpose prototype appeared to be cumbersome but feasible. In four cases strongly localized fluorescent hotspots were observed at the location where the disease was colposcopically visible. In the other cases the fluorescence showed a more diffuse multifocal image. The value of the DR determined at the site of biopsy correlated in a statistically significant way with the histopathologically determined stage of the disease [Spearman rank correlation, r=0.881, p<0.001 (confidence interval 0.7044-0.9552)]. This suggests that noninvasive staging of CIN using this technique is feasible. We believe that the results of this study justify the development of a dedicated device that combines regular white light colposcopy with DR fluorescence imaging.