1. A new imaging technique called differential structured illumination microendoscopy (DSIMe) was developed as a portable system that takes images of cells during surgical procedures.
2. DSIMe improved the contrast of images and was successfully used to image 5 biopsy patients with cervical adenocarcinoma in situ.
Evidence Rating Level: 2 (Good)
Study Rundown: Biopsies and surgical procedures for tumors and other atypical cellular events involve precision in determining the margin between non-cancerous and cancerous cells. Current techniques used for imaging are not optimal due to multiple inconveniences with either capabilities of the device or the images obtained. Therefore, DSIMe was created to overcome the current obstacles in these techniques.
Currently, structured illumination microendoscopy (SI) allows for the sectioning of cells for nuclear visualization, however, any motion during this procedure significantly impairs the clarity of the images obtained. By using an algorithm for image stabilization, the DSIMe platform improved upon this problem. Fluorescent beads were placed on slides and images were obtained at various distances to determine the sectioning capabilities of DSIMe. DSIMe was found to have improved optical sectioning compared to SI. Similar to high resolution microendoscopy, a contrast agent was used to fluorescently stain the nucleus of selected cells. Unlike high resolution microendoscopy, however, DSIMe allowed for greater cellular detail in the images obtained due to its sectioning capabilities. When tested on mouse colon and stomach tissue, DSIMe was found to improve the contrast between the components of these organs. DSIMe was also found to distinguish between normal epithelium and neoplastic cells with improved image contrast in patients with cervical adenocarcinoma in situ (AIS).
In this preliminary study, DSIMe was shown to be an optimal technique used for surgical procedures, and was even been shown to be effective during cervical biopsies. Since this technology was piloted on a small cohort of patients, the benefits of this technique for other procedures still needs to be assessed as well as the cost needed to reproduce and implement such a technology. However, this new form of microendoscopy already shows substantial benefits.
In-Depth [animal and human subject study]: To overcome the difficulties with SI in producing clear sectioned images, a motorized disc grating was used and rotated at a rate relative to the exposure time of the image, a number calculated using an algorithm for image stabilization. After being placed on a slide, 15 µM fluorescent microspheres were imaged and compared to widefield images. DSIMe produced optimal optical sectioning images that improved with an increase in the frequency of modulation.
DSIMe was then tested on tissue samples of mouse colon and stomach. Following the application of 0.01% Proflavine in PBS to stain the nucleus of the cells, the images of these tissues were found to improve the contrast between the glands and lumen, 28 ± 7% higher in colon tissue and 48 ± 20% in stomach tissue compared to widefield images.
Finally, DSIMe was used during conization on 5 patients with AIS. Similar to the mouse tissue, Proflavine was topically applied to the cervix prior to imaging. This technique distinguished between normal squamous epithelium and high-grade squamous epithelial cells, and was able to provide an improvement in the contrast of the image taken. This technique also allowed for improved visualization of nuclear morphology in regards to density, size, and pleomorphism, allowing for improved determination of high-grade epithelium from normal squamous epithelium.
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