Spectral Cytopathology of Cervical Cells Infected with Human Papillomavirus.
Nada A Farhat, Nora V Laver, Kristi Bedrossian, Jennifer M Schubert, Benjamin L Bird, Milos Miljkovic, Max Diem. Tufts Medical Center, Boston, MA; Northeastern University, Boston, MA
Background: Infrared micro-spectral imaging (IRMSI) is a novel approach for cytological diagnosis. This optical technique detects subtle biochemical changes in cells. Computer based algorithms analyze spectral differences within individual cells and provides an objective and reproducible tool for cytological diagnosis. These spectral differences may be observed before morphological changes are seen, providing additional sensitivity for earlier diagnosis. We report the use of this technique to analyze both healthy and human Papillomavirus (HPV) infected cervical squamous cells.
Design: Spectral Cytopathology (SCP), a combined technique employing IRMSI for data collection and analysis by multivariate statistics, was used to investigate exfoliated cervical samples and cultured cervical cells (C33A, HeLa, CaSki, SiHa) with different numbers of episomal copies of HPV. All specimens were prepared onto infrared (IR) microscope slides. The unstained slides were interrogated by a beam of IR light that samples pixels (6.25 µm x 6.25 µm in size) on the sample spot. A 4 mm x 4 mm IR image, which contains 409,600 complete IR spectra, was recorded from each sample. Pixels located on an individual cell were co-added, resulting in one IR spectrum for each cell that describe its discrete biochemical composition. Approximately 500-1000 cells were collected from each sample spot. Multivariate methods of analysis were then used to differentiate the cellular spectra and correlate them with conventional cytology & HPV DNA testing.
Results: This study included 48 clinical samples that were diagnosed by traditional cytology, assayed for high-risk strains of HPV (Digene Hybrid Capture II), and analyzed by SCP. The study reports a sensitivity of 91% and a specificity of 57% to detect high-risk HPV. We believe our reported poor specificity could be due to: the reported low specificity of the Digene test when compared to more sophisticated PCR based methods of viral detection, or SCP is detecting the presence of low-risk strains of HPV which are not detected by the current DNA test. We are conducting a study on cultured cervical cells that compose a different number of episomal copies of high-risk strains of HPV to determine SCP's sensitivity for viral load and latent viruses. These results will be reported.
Conclusions: We have identified biochemical differences in morphologically normal cells that contain high-risk strains of HPV by use of SCP. These results suggest that SCP could provide a potent adjunct diagnostic tool for cytopathologists.
Tuesday, March 1, 2011 9:30 AM
Poster Session III # 91, Tuesday Morning