Whole Slide Imaging

What is Whole Slide Imaging?

Whole slide imaging (WSI) – also known as virtual microscopy or Whole Slide Scanning – is a rather young technology to digitally scan and archive whole slides in high resolution. During scanning, images are taken of each field of view across the entire microscopy slide. Simultaneously, the images are stitched together by the whole slide imaging software to create a single digital image file in full resolution. These whole slide images can then be stored for archiving and documentation, and it can also be shared for consultation and for teaching purposes.

How does Whole Slide Imaging work?

Whole Slide Scanners take separate images of each field of view across the entire slide with high speed. The separately acquired images are then stitched together during the scanning process to generate a single digital image in full resolution. There are different types of slide scanners on the market: some slide scanners focus on high-throughput applications and can scan thousands slides per day in a highly automated fashion. These scanners can be integrated in automated workflows including slide barcoding, tissue staining and data file management. Typically, this whole slide imaging technology is highly optimized for a certain sample type. Thus, the scanners are equipped with a single objective and a dedicated imaging mode that acquires best image quality of the sample type of interest. Box scanners, however, can only scan one slide at a time but are rather cheap to purchase and have a very small footprint. Also these box scanners typically come with a dedicated configuration of objectives and imaging modes.

In contrast, microscope-based scanners offer slightly higher throughput but most importantly, they provide much higher flexibility for whole slide imaging in terms of sample type and imaging settings and therefore offer a very broad range of applications.

What role does Whole Slide Imaging play in Digital Pathology?

The technology of whole slide imaging developed rapidly over the last decade, as storage of large datasets, barcoding and file tracing as well as data exchange were improving tremendously. Thus, digital pathology workflows emerged with the whole slide imaging technology and enabled pathologists to send image files of whole slides to their colleagues from all over the world in order to discuss non-obvious cases or to consult experts on specific tissue types or diseases.

Moreover, digital slides are advantageous over tissue sections as color changes or degradation issues due to long-term storage conditions may compromise the quality of the physical tissue slides. Pathologists thus aimed to digitally archive tissue slides in order to maintain quality over time and to be able to analyze the tissue after years and decades. This can be very crucial in oncology as cancer can re-emerge after years and comparative analyses can provide helpful information for diagnosis and treatment.

What are the main benefits of Whole Slide Imaging?

Apart from its important role in digital pathology described above, whole slide imaging opens the door into digital whole slide image analysis employing artificial intelligence (AI) solutions. Pathologists are highly experienced and well-trained experts in their fields. To reduce their hands-on time, AI algorithms can be trained to recognize tissue patterns and specific cell types and to support the analysis with whole slide imaging. In addition, AI can accurately quantify the abundance of certain cell types within tissue sections and thus to help pathologists with image analysis and with diagnosis, and therefore to find the optimal treatment.

How do the solutions from MMI for Whole Slide Imaging differentiate themselves from competitors?

Since the MMI CellScan whole slide imaging system is a microscope-based scanning device, it offers full flexibility of a research microscope and can additionally be employed for standard (fluorescence) microscopy applications. Scanning is not limited to one resolution, but changing objectives or switching between brightfield and fluorescence imaging modes can be performed with just one mouse click (if installed on a fully motorized microscope such as the Nikon Ti2E or the Olympus IX83). The MMI CellScan, in addition to standard microscopy slides, is compatible with various sample formats such as MMI Membrane Slides for laser microdissection as well as well plates and dishes. This combination makes the MMI CellScan a highly versatile scanning system offering many features and parameter settings for optimal scanning of any sample type.

Intriguingly, the MMI CellScan whole slide imaging system can uniquely be combined with laser microdissection allowing for remote work since imaging analysis, cell selection and annotation can be performed directly in the whole slide image. MMI offers additional solutions to easily transfer files and information from the MMI CellScan to the remote desk and then to the MMI CellCut Laser Microdissection system to enable remote workflow options.

Whole Slide Images acquired by the MMI CellScan are saved in the open file format called BigTIFF which is compatible with the free MMI CellViewer as well as many other slide viewer and whole slide image analysis software packages, including AI image analysis tools.