New DVD 'virtual' microscope at UNC-Chapel Hill

03/02/04



Monkey tissue samples being used by the histology class from the virtual microscope.

CHAPEL HILL -- First-year medical students at the University of North Carolina at Chapel Hill are finding less need to adjust a traditional microscope in their histology curriculum. Instead, they are using their computers and a unique DVD to study the exacting science concerned with the minute structure of cells, tissues and organs.

This virtual microscope allows students to instantaneously receive high-resolution images of individual tissue slides at the click of a mouse button. Images can be adjusted continuously to fill all or part of a screen, and different magnifications may be viewed simultaneously, something not possible with traditional light microscopes.

UNC professors of cell and development biology Drs. William Koch and Peter Petrusz developed the virtual microscope for the histology course.

"As a viewing device, the light microscope is difficult to use, mechanically complicated and requires following strict rules in order to get optimal images," Petrusz said. "The fields you see are limited to the capabilities of the given objective lens, and that means having either a low-resolution image over a relatively large field where you don't see detail or you focus on a very small field with high resolution and you don't see the big picture.

"Our virtual version has a continuous magnification, so you can always select the optimal one to see whatever you want to see, while the big picture, the overview, is always available."

The interactivity of the new DVD is designed to appeal to today's computer-savvy medical students, who can save the screen images, print them, annotate them and label anatomical structures and layers using common computer applications.

The medical histology DVD at UNC differs from other such technology in linking syllabus text directly to specific images, making a paper manual unnecessary. In addition, the technology does not require switching between multiple CDs, adding ease in navigation.

To make sure the DVD images met their exacting demands, Petrusz and Koch sent sample tissue sections to several outside imaging technology companies. They eventually selected one providing high-resolution images far superior to the others, Koch said.

"Scanning, in this case, is a step-by-step process taking one square area at a time, producing hundreds or thousands of little squares, or tiles," he said. "Like mosaics, these little pieces must be assembled seamlessly, very smooth and correct. It's a very critical part of the process."

Each resulting image is gigabyte size. Images are then encoded and compressed with computer programs developed that assure minimal loss.

This viewing program is known as MrSid, the acronym for multi-resolution seamless image database. The new DVD is cost-effective. Typically, medical schools struggle to maintain their teaching microscopes. UNC has hundreds of microscopes that are at least 30 years old, difficult to maintain and ripe for replacement. Replacement costs may approach $1 million, even without taking into account support personnel.

"The virtual microscope eliminates that need," Petrusz said.

With about 160 medical students and 10 to 20 faculty, UNC's histology course needs nearly 200 slides of the same structures and of good quality. "This is a practical impossibility," Petrusz said. "But in the new system, everyone sees the same high-quality images."

Still, Koch said, the new virtual microscopy technology has not erased practicing physicians' need for traditional microscopes.

"That's why we kept instructional material for using the light microscope in the syllabus," he said. "Included in the resources for this course is a video demonstrating use of the light microscope. Students also have the opportunity to work with microscopes."

The DVD can be used beyond the first year of medical school, for review while taking pathology or any other time students want to review the basic material, Koch and Petrusz said. They can carry the histology course with them.

"In assessing how histology had been traditionally taught to medical students, we decided that traditional methods were not only inefficient, but would become increasingly so," said Dr. Vytas A. Bankaitis, professor and chair of cell and developmental biology.

"Technical difficulties associated with uneven tissue slide quality, and an aging set of microscopes with which to view these slides, conspire to reduce quality teaching time. We decided a virtual format offered a superior and long-term solution to the major challenges of histology instruction."

Next for the DVD is a third dimension: depth. "The company we work with is developing a new viewer having the ability to focus vertically. It will allow us to resolve structures that are too thick for the current system," Petrusz said.

Dr. Gerald Gordon, research assistant professor of cell and developmental biology, helped Koch and Petrusz with computer-related issues during the DVD's development.

Source: Eurekalert & others

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