Written by: Edmond Truelove, DDS, MSD
My History With Fluorescence Visualization
My colleagues and I at the University of Washington have utilized tissue fluorescence since 2008 in research and patient care activities focused on improving assessment methods of oral mucosal tissues. Over the years, our interest in patient assessment methods has ranged from detecting and diagnosing mucosal lesions to diagnosing and classifying acute and chronic types of orofacial pain. We have published on the topic of diagnostic processes including methods that supplement the use of visual and tactile evaluation of mucosal tissues via fluorescence visualization, cytology, and vital tissue staining.
There have been favorable and dissenting views about the diagnostic value of fluorescence visualization in dental diagnostics. Those critical of that technology and other supplemental diagnostic technologies base criticism on the assumption that they aim to result in a definitive diagnosis when, in fact, they are designed to enhance detection of a change that may represent a pathological process and, therefore, deserve further consideration and assessment.
The most important aspect of patient evaluation is the detection of a finding that may or may not represent a pathological process; for example, the detection of a dark spot on a tooth that may represent staining or invasive dental caries. Detection of the spot is not a specific diagnosis of caries. It is a signal of possible caries presence. Additional clinical steps are necessary to make a final diagnosis of invasive caries (explorer probing, radiographs, perhaps even exploratory tooth surface or restoration removal). In my opinion, the use of the VELscope (LED Dental) for oral examinations is analogous to the use of supplemental technologies that help identify tooth changes that may represent invasive caries, thus triggering the need for additional definitive diagnostic steps.
One of our first endeavors related to the use of a fluorescence device (VELscope) was to conduct a simple Quality Improvement Study (QIS) to explore the potential value of adding its use to our examination protocol of the oral mucosa during dental examination of regular dental patients. The purpose of a QIS is to see if minor changes in an usual process improve the outcome. QIS is not a randomized controlled study since it seeks to only test whether one change can make a difference. We determined that briefly inspecting the mucosa using the tissue fluorescence after standard visual and tactile examination resulted in a significant increase in the detection of mucosal changes not seen or detected during the routine visual examination.1
Typical examples of these types of changes can be seen in Figures 1 and 2. Figure 1 shows changes in the right buccal mucosa that are more dominant and extend much further, as seen with the fluorescence imaging compared with the normal white light image, suggesting the additional value fluorescence visualization brings in assessing the extent of a mucosal change and response to treatment. Figure 2 depicts an enlargement on the hard palate next to the molar that could represent a subepithelial tissue mass with inflammatory change. The ability to visualize the change under fluorescence thus aided both detection and assessment.
Of the 650 patients evaluated in the QIS, changes deserving further evaluation were found in 69 patients. The addition of the fluorescence imaging part of the QIS took less than 2 minutes per patient. Of the 69 additional mucosal findings not detected in the standard examination, 5 cases of oral dysplasia (varying degrees of dysplasia) were detected along with other types of mucosal pathology.
In addition to assessing the use of fluorescence imaging as part of routine diagnostics of dental patients, we have also used the technology in our oral medicine clinical service to assist us in more detailed assessment of known mucosal changes/lesions that might present with areas of epithelial dysplasia. Other uses of fluorescence included assessment of inflammatory changes and the presence of indicators of possible recurrent dysplastic change in areas of prior-treated dysplasia. On numerous occasions, changes not seen with routine visual and tactile assessment but identified with fluorescence visualization have led to decisions to initiate additional definitive diagnostic steps that resulted in the detection of new or recurrent dysplasia. In those cases, the technology has enhanced our ability to detect early changes of a potentially serious nature that are too vague or nonspecific to be detected by experienced clinical experts. Again, the use of fluorescence imaging in our clinical service has been used to identify changes that may benefit from further assessment. These range from simple clinical followup to biopsy, not to make definitive diagnoses (that step requires histopathologic evaluation).
Although we found that adding fluorescence examination to our routine oral assessments beneficial, it occurred to me at that time that it would be useful when using the technology and discovering a potentially abnormal area to be able to quickly switch to normal white light visualization to immediately compare the 2 clinical presentations without changing my angle or field of view. This was not straightforward since the scope only provided fluorescence visualization. This situation was ameliorated for photo documentation with the introduction by the manufacturer of an iPod touch with a custom scope adapter, which facilitated not only fluorescence photographs through the scope handpiece but also white light photographs. This was achieved by quickly removing the magnetically attached adapter from the scope handpiece and acquiring photographs using the iPod touch with the built-in flash. Nevertheless, a more seamless method would have been very useful.
The original VELscope units we utilized were large and attached to a separate “plug-in” base unit. Later generations became more portable and recharged rather than “plugged in.” Although I liked the portability of these later units, they required an internal fan for cooling and, like other fan-based devices, fan noise and airflow can be distracting.
As I used the various units over time, I realized that enlarging the field of view would be advantageous because it allows for the assessment of a larger area of the mucosa, allowing for a better comparison of findings with adjacent normal mucosa.
Another factor that sometimes limited the ability to examine a tissue change, or photography of the change, was reflectance caused by saliva, serum, and other liquids. This could often be especially problematic for photo documentation since reflections from the illumination source would appear in photographs and could obscure the color of underlying tissue, hindering comparative assessment when examined later.
Incorporating Nonpolarized and Polarized White Light Visualization
I was recently given an opportunity to review and assess a preproduction version of a new VELscope system called the VELscope Mantis (LED Dental). I have been encouraged by finding that this new unit has addressed the limitations of prior versions. Most importantly, it has integrated white light and blue light-induced fluorescence visualization into one device.
It achieves this by integrating white and blue LEDs into the unit and positioning them around a significantly larger viewport than in previous VELscope models (Figures 3 and 4).
Because observing natural tissue fluorescence requires a special optical filter, the device is equipped with a filter wheel, which is rotated to position the filter over the viewing port for fluorescence visualization and rotated again to move it out of the viewing port for normal white light visualization. The control scheme, which I found straightforward and rather novel, is to simply rotate the filter wheel to one of 3 positions for viewing tissue with one of 3 visual modes: normal white light, polarized white light, or fluorescence visualization. The device automatically activates the LED light source appropriate for that viewing mode. The only other control is the main power button to turn the unit on or off.
The normal white light and fluorescence visualization modes are self-explanatory. The third visual mode allows you to see the polarized white light reflectance from the tissue. I was intrigued to find that viewing tissue in this mode essentially blocked the surface reflections from white LEDs, illuminating the tissue and resulting in a noticeably clearer and color-saturated view of the oral mucosa. The technical team who designed the device pointed out to me that just as fluorescence visualization complements but does not replace traditional white light visualization of tissue, so too is the polarized visualization mode a complement but not a replacement for traditional visualization. The point is that surface reflections can be a distraction when looking at the underlying tissue color, but they provide the benefit of helping visualize surface texture and contour. This is important because the roughness or smoothness of a mucosal surface can be an indicator of tissue health or pathology.
Another notable feature is the ability to insert an iPhone into the jaws on the back of the device (Figure 5) and position it such that the lenses of the camera are centered in the viewport (Figure 6), resulting in an ability to acquire good-quality white light, polarized white light, and fluorescence clinical photographs.
My understanding from the manufacturer is that apps GRIP&SHOOT and G&S Dental (on the Apple store) work with supported iPhone models so that you can use the buttons on the handpiece to acquire photographs and zoom the camera. This is a valuable feature since it allows one-handed operation of the device during the acquisition of clinical photographs, leaving the other hand free to retract tissue. I don’t own an iPhone, but I tried taking some photographs using a Samsung Galaxy phone (albeit using my other hand to touch the phone screen to control the phone camera), and I was able to obtain excellent images
My impressions of the device based on this initial evaluation are described below:
1. Integrating a white light source into what had previously been a fluorescence-only device is very helpful because it directly illuminates the tissue being inspected without needing to adjust the dental unit light. The quality of the white light was excellent, providing a clear and vivid visualization of the oral mucosa. The LEDs used for this device are comparable to the type used for surgical lighting used in operating rooms, ideal for visualizing and imaging oral mucosal tissues.
2. I liked incorporating the polarized white light visualization mode for its ability to suppress white light surface reflections of the illumination light, enhancing the ability to visualize underlying color and assess tissue architecture. I think it could be a useful complement to the traditional non-polarized view. Polarized visualization is useful in the imaging of skin lesions, and I will be curious to see if it has new applications in the visualization of oral mucosa. Another nice feature when using polarized visualization is that the device automatically boosts the intensity of the white light to compensate for the light absorbed by the polarizing filter, resulting in no perceived change in brightness when switching from the normal white light mode to polarized.
3. The fluorescence visualization mode had been modified slightly from earlier versions to better show the characteristic orange and reddish colors indicative of mucosal surface bacterial colonization. I noticed that effect and think that, in addition to the more established uses of fluorescence visualization, the modification could be useful to assess surface bacterial colonization on areas of mucosa that indicate microbial adherence associated with infection or colonization suggestive of a pathological process.
4. The field of view is almost twice as large as that of earlier VELscope devices, making it easier to view localized areas of potential abnormality within the context of surrounding normal tissue. The use of magnification during mucosal assessment is not hampered.
5. The user interface of the device is simple and intuitive: just turn it on and rotate the filter wheel to select the visualization mode—it is difficult to go wrong.
6. The ability to easily photo document all 3 visualization modes with a wide range of phone models is a major advantage of this new system compared to earlier models. See Figures 7 to 9 for an illustrative example of a quality set of clinical photographs that can be easily obtained using an iPhone by rotating the filter wheel a couple of times. Note the differences between the nonpolarized and polarized photographs: in the polarized photograph, the surface reflections from the white LEDs have been completely suppressed, and the higher contrast, more saturated colors afford an improved view of the ventral tongue vasculature.
It is also worth mentioning that acquiring images on an iPhone means all of Apple’s extensive suite of features for sharing and uploading are available. This should facilitate the transfer of clinical images into the patient record.
7. Some care is needed to protect and disinfect the filter wheel, but it is easily detached for cleaning and disinfection.
8. The handpiece portion for gripping the device felt ergonomic and fit my hand acceptably.
9. The unit works cordlessly and is powered by an internal lithium-ion rechargeable battery. I did not test the run-time, but I have been informed that it is significantly longer than previous VELscope models. It is my understanding, based on information from the manufacturer, that it will work for multiple days of typical use before needing to be recharged.
10. A nice surprise was that there was no fan, meaning completely silent operation of the unit, which I appreciated.
Help in the Management of Oral Lesions
Oral mucosa often exhibits changes other than dysplasia that require detection, diagnosis, monitoring, and/or treatment. The process of detecting potential abnormalities includes several components. First is detailed history taking, second is visual assessment, and third is palpation with tactile assessment of surface and subsurface tissues. Symptoms triggered during examination (pain, burning, paresthesia) are part of the detection and diagnostic process.
Whether or not clinicians use a visual aid, such as the VELscope, or other fluorescence visualization methods once they detect an area of mucosal change that they suspect may be abnormal, they are faced with the same problem: how to manage the patient moving forward. Since it can sometimes be difficult for busy general practitioners to decide the best next steps after detecting a tissue change or other clinical findings, LED Dental asked me to help establish the Clinical Decision Support Service to assist clinicians in making diagnostic and management strategies decisions. That service can be accessed at oralmedicine.com, where clinicians are guided through a detailed case submission form in which information on patient and lesion history can be provided and clinical photographs uploaded. Upon review by a panel of oral medicine specialists or clinical oral pathologists, clinicians are sent a report with expert suggestions and guidance that help the clinician make timely decisions that can sometimes be delayed due to (a) indecision typical in a busy general practice, (b) lack of frequently encountering such problems, or (c) issues of access to other providers who can provide assistance. The service does not provide definitive diagnoses. Instead, it provides options for diagnoses to consider and potential actions the clinician can consider, including those related to the management of the patient.
I am hopeful that new oral mucosal visualization tools, such as the VELscope Mantis and resources like the web-based Clinical Decision Support Service, will help dental practitioners enhance care for their patients presenting with oral mucosal changes.
REFERENCES
1. Truelove EL, Dean D, Maltby S, et al. Narrowband (light) imaging of oral mucosa in routine dental patients. Part I: Assessment of value in detection of mucosal changes. Gen Dent. 2011;59(4):281–9.
ABOUT THE AUTHOR
Dr. Truelove completed his dental and specialty training in oral medicine at Indiana University. He served as clinical chair there before becoming the founding chair of the Department of Oral Medicine at the University of Washington, where he is currently professor emeritus. His professional and academic activities include a long history of patient care in the field of oral medicine and orofacial pain. He has served as chair of the Council on Scientific Affairs of the American Dental Association and chair of the American Board of Oral Medicine of which he continues to be a member. He has received numerous academic honors, been awarded several NIH clinical research grants and authored more than 200 scientific papers in addition to numerous textbook chapters. He can be reached at etruelove@comcast.net.
Disclosure: Dr. Truelove is an unpaid consultant and has received educational honorarium from VELscope.
