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Keywords:

  • histology;
  • microscopy;
  • computer-assisted learning;
  • education, medical;
  • instruction

Abstract

  1. Top of page
  2. Abstract
  3. DIGITIZATION OF SLIDES AND DISTRIBUTION
  4. VIRTUAL MICROSCOPE LABORATORY
  5. INCORPORATION INTO THE COURSE
  6. EVALUATION
  7. DISCUSSION
  8. CONCLUSION
  9. LITERATURE CITED

Emerging technology now exists to digitize a gigabyte of information from a glass slide, save it in a highly compressed file format, and deliver it over the web. By accessing these images with a standard web browser and viewer plug-in, a computer can emulate a real microscope and glass slide. Using this new technology, the immediate aims of our project were to digitize the glass slides from urinary tract, male genital, and endocrine units and implement them in the Spring 2000 Histology course at the University of Iowa, and to carry out a formative evaluation of the virtual slides of these three units in a side-by-side comparison with the regular microscope laboratory. The methods and results of this paper will describe the technology employed to create the virtual slides, and the formative evaluation carried out in the course. Anat Rec (New Anat) 265:10–14, 2001. © 2001 Wiley-Liss, Inc.

The recent trend in histology education has been to incorporate computers into both instruction and independent student study (Cotter, 1997a, b; Evans et al., 2000; Lee et al., 1997; Lehmann et al., 1999; Mars and McLean, 1996; Spitzer and Whitlock, 1998; Trelease et al., 2000). The movement from glass slides and the microscope to computer images is being driven by the fact that computers, in addition to many other positive attributes, are a very efficient way for students to learn visual material. Although some medical schools are abandoning the microscope in favor of computer programs, there may be concerns regarding the use of this technology alone. Most computer programs are limited to static images that do not functionally resemble the microscope in that they do not allow students to explore relationships by moving the tissue and changing magnification, independently identify structures, and discover relationships. Static images in textbooks and on the computer screen certainly have a role in augmenting the laboratory experience. However, many anatomy and pathology educators believe that viewing slides of human tissue under the microscope (analogous to performing a gross dissection) adds a totally different dimension to learning that is not afforded by still images.

Emerging technology now exists to digitize the entire information of a histologic slide at high power (40×), save it in a highly compressed file format, and deliver it over the web. By accessing these images with a web browser and viewer plug-in, a computer can nearly perfectly emulate a real microscope. Using this new technology, the immediate aims of our project were to:

  1. (1) Digitize the glass slides from urinary tract, male genital, and endocrine units and implement them as a Virtual Microscope Laboratory in the Spring 2000 Histology course at the University of Iowa.

  2. (2) Carry out a formative evaluation of these three units by comparing the Virtual Microscope Laboratory to the regular microscope laboratory.

The methods and results of this paper will describe the technology employed to create the virtual slides, and the formative evaluation carried out in the course.

DIGITIZATION OF SLIDES AND DISTRIBUTION

  1. Top of page
  2. Abstract
  3. DIGITIZATION OF SLIDES AND DISTRIBUTION
  4. VIRTUAL MICROSCOPE LABORATORY
  5. INCORPORATION INTO THE COURSE
  6. EVALUATION
  7. DISCUSSION
  8. CONCLUSION
  9. LITERATURE CITED

The 19 slides evaluated in this study came from the endocrine, urinary tract, and male genital tract units in the University of Iowa Histology course study sets.

A Leica DMR microscope, Ludl motorized stage with auto-focus, Optronics videocamera, and Pentium III computer with two gigabytes of RAM and Windows 2000 were used to digitize the slides. Up to 1,200 (30 × 40) contiguous 40× microscopic fields (640 × 480 pixels at 300 pixels per inch with 24-bit color depth) were captured automatically and tiled together with a 35-pixel overlap into a seamless montage (approximately 18,000 × 18,000 pixels). This resulted in a tagged image file format file (tiff) of approximately one gigabyte for each slide. MicroBrightField Virtual Slice software coordinated the activities of the stage, auto-focus, video-capture, and automatic tiling of the images (http://www.microbrightfield. com). The 1,200 fields capture up to .9 ×.9 cm. of the tissue of each glass slide. If more than .9 ×.9 cm. of tissue were needed to demonstrate the key portions of the specimen, a second file with additional fields was captured. The tiff files were then opened in Adobe Photoshop, edited for background color, and cropped if needed.

The tiff image was then saved in a highly compressed FlashPix image file format (fpx) using MGI software (http://www.mgisoft.com), which resulted in a fpx file of up to 125 megabytes per slide. Conceptually, the fpx format is a pyramidal stack of replicas of a jpg-compressed image with a full-sized, full resolution image at the base and a small, low-resolution replica at the top of the pyramid. A zoom function changes magnification by 2-fold with each click of the mouse by jumping from one layer in the stack to the next. A click and drag function permits scanning of each layer of the stack in an x-y-axis. When viewing higher resolution fields, the server only brings into RAM the portion of the image being viewed on the computer monitor (http://www.webtools.com/story/ multimedia/TLS19981119S0099).

The total computing time per slide ranged from 2–3 h; however when automatic capture starts the operator is free for 1.5 to 2 h. Once digitized and saved in fpx format, the images were placed on the College of Medicine NT server. MGI server software, delivers the fpx files to the web in standard HTML frames. Currently only Windows platform with Internet Explorer or Netscape is available for delivering fpx files.

Emerging technology now exists to digitize the entire information of a histologic slide at high power (40×), save it in a highly compressed file format, and deliver it over the web.

VIRTUAL MICROSCOPE LABORATORY

  1. Top of page
  2. Abstract
  3. DIGITIZATION OF SLIDES AND DISTRIBUTION
  4. VIRTUAL MICROSCOPE LABORATORY
  5. INCORPORATION INTO THE COURSE
  6. EVALUATION
  7. DISCUSSION
  8. CONCLUSION
  9. LITERATURE CITED

The Virtual Microscope Laboratory web site consists of the syllabus, table of contents, virtual slides, gross images for gross microscopic correlation, and links to additional histology web sites. It is accessible by students in any of the University of Iowa computing centers or cable modem on a password-protected intranet. The virtual slides appear in a 590 × 590 pixel html frame on an 800 × 600 screen. A free viewer plug-in for viewing the virtual slides can be downloaded from the home page of the Virtual Laboratory or from the MGI site. The viewer plug-in navigational tools allow the user to zoom in or out through six levels of magnification (1.25×, 2.5×, 5×, 10×, 20×, and 40×) and click and drag the slide in an x-y axis through the entire surface of the virtual slide while being viewed at any magnification. To the left of the virtual slide is a 200 × 590 frame that contains a whole mount of the slide and text from the Histology laboratory syllabus. Thus, the Virtual Microscope Laboratory with associated slides and syllabus has similar content to that available to students in the regular microscope laboratory, but with added capability to correlate gross images, and link to other web sites. An example of the appearance of a web page is shown in Figure 1.

thumbnail image

Figure 1. A screen shot of a Virtual Microscope Laboratory web page. The upper left frame contains a whole mount of the slide. In the lower left frame is the text of the laboratory syllabus and additional links. Using the navigational tools at the bottom of the right frame, the student can manipulate the virtual slide through six levels of magnification (1.25×, 2.5×, 5×, 10×, 20×, and 40×), starting at the level of the whole mount, as well as click and drag the slide in an x-y axis through the entire surface of the slide, at any magnification. A 40× view of thyroid and parathyroid is illustrated.

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INCORPORATION INTO THE COURSE

  1. Top of page
  2. Abstract
  3. DIGITIZATION OF SLIDES AND DISTRIBUTION
  4. VIRTUAL MICROSCOPE LABORATORY
  5. INCORPORATION INTO THE COURSE
  6. EVALUATION
  7. DISCUSSION
  8. CONCLUSION
  9. LITERATURE CITED

The web address of the Virtual Microscope Laboratory, with three units completed, was given to the students, and they were instructed in the use of the web browser plug-in. They were told that the content was the same as in the regular laboratory slide boxes and syllabus. Students still attended the regular microscope laboratory, but they were able to access the Virtual Microscope Laboratory at any time of day or night on campus, or via cable modem from home.

EVALUATION

  1. Top of page
  2. Abstract
  3. DIGITIZATION OF SLIDES AND DISTRIBUTION
  4. VIRTUAL MICROSCOPE LABORATORY
  5. INCORPORATION INTO THE COURSE
  6. EVALUATION
  7. DISCUSSION
  8. CONCLUSION
  9. LITERATURE CITED

The formative evaluation of the three units was performed during the Spring 2000 Histology course at the University of Iowa College of Medicine. The evaluation form shown in Table 1 {Table 1} was distributed to 158 students via the web at the end of the course. Since this was a formative evaluation, and the use of the Virtual Microscope Laboratory was not mandatory, filling out the evaluation was voluntary. Thirty-nine students responded for a return rate of 25%. Some of the respondents did not code a response to all questions on the survey; thus, analyses of items were conducted with fewer than 39 responses.

The first six items of the evaluation were designed to compare student perceptions of different aspects of performance of the regular microscope laboratory with the Virtual Microscope Laboratory. Table 2 displays the means (M) and standard deviations (SDs) for student responses to each item and the total score. For all six of the evaluation items, the mean rating for the virtual microscope was more favorable compared with the traditional microscope laboratory.

Table 1. Evaluation form used for the survey
Please use the following scale to evaluate the Regular Microscope vs. Virtual Microscope Laboratories.
1 = Strongly Agree 2 = Agree 3 = Neutral 4 = Disagree 5 = Strongly Disagree
Regular Microscope Laboratory vs. Virtual Microscope Laboratory
Please Note: 1 = “excellent rating” 5 = “poor rating”
1. The method was an efficient use of my time.1234512345
2. Directions for use of the Microscope were clear.1234512345
3. Microscopic images were clear.1234512345
4. Navigation of the slides with the microscope was easy.1234512345
5. The method optimized the information I needed to learn histology.1234512345
6. The microscope was sufficiently accessible.1234512345
Please provide specific comments about each microscope laboratory:
1. How would you improve each microscope laboratory?
2. What would you keep the same about each microscope laboratory?
3. Other comments about the microscope laboratories.
How much time did you spend using the Virtual Microscope Laboratory?
 <1 hr  ∼1 hr  ∼2 hr  >2 hr
Table 2. Summary of responses to survey questions 1–6
Type of LaboratoryItem 1 (n = 29)Item 2 (n = 29)Item 3 (n = 29)Item 4 (n = 28)Item 5 (n = 29)Item 6 (n = 28)Total
RegularM = 3.41M = 2.31M = 2.72M = 2.78M = 3.21M = 2.93M = 17.28
 microscopeSD = 1.09SD = 1.39SD = 1.44SD = 1.42SD = 1.18SD = 1.36SD = 5.60
VirtualM = 2.34M = 2.24M = 2.41M = 2.45M = 2.41M = 2.21M = 14.00
 microscopeSD = 1.49SD = 1.50SD = 1.40SD = 1.57SD = 1.43SD = 1.64SD = 8.37

Paired two-tailed t-tests were conducted on the differences between the responses for each of the six matched questions (regular vs. virtual) and the total. Across the characteristics measured by the six items, the Virtual Microscope Laboratory was rated higher than the regular microscope laboratory (t = 2.03, P = .05). When items were evaluated separately, item one (The method was an efficient use of my time), and item six (The microscope was sufficiently accessible) displayed highly significant differences between the two modes of presentation, with the Virtual Microscope Laboratory more preferred. For the remaining four items (Directions for use of the microscope were clear; Microscopic images were clear; Navigation of the slides with the microscope was easy; The method optimized the information I needed to learn histology) students felt that the virtual microscope was at least as good as the regular microscope, but the difference in responses was not significant.

Written responses on the second part of the evaluation form were supportive of the virtual microscope. Students commented that they “greatly appreciated the virtual microscope lab ” and thought that “the virtual histology laboratory is great as an addition to the regular lab.” Some students “didn't think it should replace the regular lab.” Others stated that “the move around and zoom in/out function is like looking at the real microscope.” Many students wanted “to make sure the virtual scope could be reached from everywhere, including off campus.” Furthermore, some students commented that they were hoping to use the virtual microscope laboratory to replace “spending hours in the microscope lab, searching aimlessly; we could sit while a histology professor points out the important features, zooming in and out across the slide,” and “this virtual process can be so much more productive for students, and more stimulating also.” Others said: “I do see the need for some experience with the real microscope.” Additionally, a few students noted that the Virtual Microscope Laboratory “was quite helpful, however, without an instructor there, it was difficult to find many of the structures.” Some students wanted more information in the virtual microscope laboratory such as “arrows to structures that were difficult for an inexperienced viewer to locate” and “a mechanism to quiz our progress.” Nearly all of the students who responded to the evaluation indicated that they had used the Virtual Microscope Laboratory more than 2 hours.

In addition to student evaluation, student use of the Virtual Microscope Laboratory was tracked on the University of Iowa web server using a Microsoft FlashStats program. This program tabulates the number of times an URL is accessed. Hits on the home page of the Virtual Microscope Laboratory were tabulated by day and by time of day. Student use peaked at 12:30 pm and again at 9:00 pm, dropping off from 1:00 am until 6:00 am. The frequency of hits by day went up markedly in proximity to examinations.

DISCUSSION

  1. Top of page
  2. Abstract
  3. DIGITIZATION OF SLIDES AND DISTRIBUTION
  4. VIRTUAL MICROSCOPE LABORATORY
  5. INCORPORATION INTO THE COURSE
  6. EVALUATION
  7. DISCUSSION
  8. CONCLUSION
  9. LITERATURE CITED

Based on the limited formative evaluation carried out in this study, a Virtual Microscope Laboratory appears to be a viable addition to, if not a potential replacement for, real microscopes and glass slides. Students gave significantly higher ratings to the accessibility and efficiency of the Virtual Microscope Laboratory vs. the regular microscope laboratory. Regular microscope laboratories were open during the day, but the additional accessibility of the Virtual Microscope Laboratory after hours was taken advantage of by students, especially preceding practical examinations. In addition, students rated the quality of images and navigation of the virtual microscope equal to or better than a real microscope. Virtual slides are always in focus with ideal condenser and light adjustment, thus decreasing the student time and some of the frustration in operating a real microscope.

Based on this positive information, we plan to carry out laboratory sessions next year in two venues. One will be in a laboratory equipped only with computer work-stations and a computer projector for faculty demonstrations. The other venue will be in a laboratory equipped with multi-headed microscopes, plus a computer projector for faculty demonstrations. After introductory sessions to acquaint students with the real and virtual laboratories, the class will be allowed to attend either venue during regularly scheduled laboratory time with an instructor present. Students will also have the opportunity to use any modality outside of scheduled class time; however, the real microscope laboratory will only be open weekdays 8 am to 5 pm, Tues/Thurs/Fri and 8 am to 8 pm, Mon/Wed. At the end of the course, all students will be required to fill out a subjective evaluation form, attendance in the two venues will be tabulated, computer use outside of class will be tracked, and examination scores will be compared with the previous year's results.

Students gave significantly higher ratings to the accessibility and efficiency of the Virtual Microscope Laboratory vs. the regular microscope laboratory.

Development of a Public Domain Set of Virtual Slides

We have received funding from a National Library of Medicine Information Systems Grant to develop a public domain Database of Microscopic Anatomy using the technology described in this study. Our long-term aim is to develop a comprehensive set of high-quality peer-reviewed digital replicas of slides that, when completed, will be extensively used by course directors to augment or replace glass slides and microscopes. Because the glass slides from our course are mostly commercially purchased, they cannot be put in the public domain. Thus, we will be asking histology instructors around the world to contribute to this Database. A Virtual Slide Box of Histology, which contains some of the slides contributed to the Database from our institution, can be accessed at http:\\www.medicine.uiowa.edu/pathology/nlm_histology. This web site also contains the MGI viewer plug-in site.

This public domain Database, when completed, will consist of approximately 150 digitized high-resolution virtual microscopic slides of every adult human organ and tissue. We are saving the virtual slides in native tiff format so that they may be converted to other file formats: fpx, jpg, jpg 2000. Additionally, the Database will contain images of gross organs and gross anatomy images from the Visible Human data set downloaded from the Visible Human Slice Server (http://visiblehuman.epfl.ch/) (Spitzer and Whitlock, 1998; see also Bacro et al., 2000). These gross images will allow students to make gross-microscopic correlations.

The end user will be able to use the virtual slides in this public domain Database in several ways.

  1. (1) The URL can be accessed by students and used as a virtual slide box for histology courses.

  2. (2) Faculty can project the slides in laboratories or lecture halls.

  3. (3) Faculty can capture and download images from any field at any magnification on the virtual slide for use in PowerPoint presentations, educational software programs, or for conversion to 2 × 2 color slides.

  4. (4) Histology faculty can access the URL of individual slides (in fpx format) and create their own virtual slide box or virtual laboratory.

  5. (5) We will be able to provide the original tiff or fpx image files, via tape or DVD, to those who want to manipulate and serve the images themselves.

We believe the Database will allow faculty to develop teaching strategies that promote self-directed learning by students outside of structured laboratories. Access to microscopic slides via computer will allow students the flexibility of studying at any computer on campus or in the future at home when cable modem or DVDs become commonplace (e.g., see Bacro et al., 2000). Independent student group learning will be promoted because computer monitors can be viewed by multiple participants. These potential outcomes are all consistent with emerging educational goals in medical and dental curricula.

The capability to create seamless digitized facsimiles of entire histologic specimens is just emerging. Although digitization of a smaller portion of a slide, such as with QuickTime VR (Trelease et al., 2000), may currently be more practical, we believe there is an educational advantage to visualization of the entire specimen at low power, coupled with the ability to zoom into any portion of the slide at 40×. The current capability of the technology described in this study is to capture only about 1 square centimeter of the surface of a slide at 40×. As technology advances, we estimate the acquisition time will decrease by half and processing capability will increase, so that up to 4 square centimeters of a histologic slide can be captured and delivered in the near future. Computer technology is advancing at an exponential rate. What might seem technically impractical today may seem technically trivial in three years.

Should Physicians Know How to Use a Microscope?

It can be argued that medical students need to learn how to use an actual microscope. Most practicing physicians do not use the microscope, especially to look at histologic slides; however, many primary care physicians in office practice will use the microscope to look at gram stains, urine sediments, and blood smears. We believe this set of students should learn to use the microscope in the context of learning to look at those specimens. The goal of microscopic anatomy and pathology education is to teach students normal and abnormal human structure, not how to use the microscope. With all that said, we still believe it is important to introduce the students to microscopes and glass slides at the beginning of their histology education, so they have a concept and appreciation of the source of the tissue and the images that appear on the computer screen.

CONCLUSION

  1. Top of page
  2. Abstract
  3. DIGITIZATION OF SLIDES AND DISTRIBUTION
  4. VIRTUAL MICROSCOPE LABORATORY
  5. INCORPORATION INTO THE COURSE
  6. EVALUATION
  7. DISCUSSION
  8. CONCLUSION
  9. LITERATURE CITED

The transformation to teaching histology on the computer may be inevitable. In the future, institutions will not be able to support multi-purpose computer learning centers plus large microscope laboratories, especially if microscopic morphology can be effectively taught via computer. We believe the Virtual Microscope Laboratory and the emerging technology described in this project assists with the transformation in a way that will maintain many of the educational advantages inherent in using a real microscope and glass slides.

LITERATURE CITED

  1. Top of page
  2. Abstract
  3. DIGITIZATION OF SLIDES AND DISTRIBUTION
  4. VIRTUAL MICROSCOPE LABORATORY
  5. INCORPORATION INTO THE COURSE
  6. EVALUATION
  7. DISCUSSION
  8. CONCLUSION
  9. LITERATURE CITED