Feature Of The Week 6/21/09: Laparoscopic optical coherence tomography imaging of human ovarian cancer
Feature Of The Week 6/21/09: Ovarian cancer is the fourth leading cause of cancer-related death among women in the US, largely attributed to late detection due to unreliable symptomology and screening tools without adequate resolution and specificity. As a result, ovarian cancer is often diagnosed at advanced stages, after invasion of adjacent structures or metastasis to a distant site. Women with regional and distant disease have a 5-year survival rate of 71% and 30% (at best), respectively. If diagnosed at the localized stage, the 5-year survival rate is 92%; however, only about 19% of all cases are detected at this stage, typically identified incidentally during another medical procedure.
OCT has particular promise in ovarian cancer diagnostics. Given the additional subsurface information it provides, it has potential for in vivo identification of suspicious lesions and guidance of small biopsy site acquisition in place of total ovary resection. Previous studies of ex vivo OCT imaging in normal and diseased human ovary found OCT capable of resolving tissue level changes, including inclusion cysts, endometrial implants, and superficial tumor masses. Changes in stromal organization and directionality of collagen fibers thought to be associated with malignancy were also suggested.
A recent study by a team from the University of Arizona and University of Connecticut presented interesting results on Laparoscopic optical coherence tomography imaging of human ovarian cancer. This study presented the development and successful implementation of the first ever laparoscopic OCT (LOCT) device to image the ovaries of patients undergoing oophorectomy. OCT images were compared with histopathology to identify preliminary architectural imaging features of normal and pathologic ovarian tissue. Thirty ovaries in 17 primarily peri or post-menopausal women were successfully imaged with LOCT: 16 normal, 5 endometriosis, 3 serous cystadenoma, and 4 adenocarcinoma. Preliminary imaging features developed for each category reveal qualitative differences in the homogeneous character of normal post-menopausal ovary, the ability to image small subsurface inclusion cysts, and distinguishable features for endometriosis, cystadenoma, and adenocarcinoma. The visualization of small epithelial invaginations and inclusions cysts with OCT is of particular importance as these inclusion cysts are suspected to be the precursor lesions for aggressive Type II ovarian carcinoma. The high resolution and subsurface imaging capabilities of OCT allow visualization of these inclusion cysts where they would likely be unidentifiable by laparoscopy alone and could be missed by histologic sections if the entire ovary was not embedded and sectioned. These results support the potential of OCT both as a diagnostic tool and imaging modality for further evaluation of ovarian cancer pathogenesis. Although not within the scope of this pilot study, transvaginal OCT imaging may provide a screening tool for patients known to be high risk for ovarian cancer and future studies will be aimed at evaluating this mode of imaging.