Dermatoscopy is a widely used non-invasive technique of producing high quality, magnified pictures of structures under the skin surface, which the naked eye cannot see. The technique uses immersion fluids, or Ifs, to reduce light reflection from the skin surface because the reflected light interferes with the images of the skin sub structures. For superior images it is necessary to have the best application techniques.

Dermatoscope application techniques

The total procedure consists of selecting the best immersion fluid and the best techniques of applying the IF and the dermatoscope on the skin. Studies have bee done on volunteers to find the optimal procedure. The two main criteria for optimizing the procedure were air inclusion and picture clarity. Air inclusion refers to air bubbles trapped in the immersion fluid. The fewer the number of air bubbles the better the image quality.

IF selection

Based on past experience, seven IFs have been selected for study. Including;

• Physiological water solutions
• Aqueous disinfectant
• Alcoholic disinfectant
• Ethanol
• Isopropanol
• Liquid paraffin
• Ultra sound gel

To investigate the IFs, one IF was used daily on volunteers.

IF and dermatoscopy application techniques

Next, the study investigated the possible techniques of applying the IF and the dermatoscope.

Three ways were found to apply IF on the skin. These were;

• Using an eye dropper to place IF on the skin first
• Using an eye dropper to place IF on the dermatoscope first
• Using a plastic misting bottle to spray IF on the skin

Three ways were also found to apply the dermatoscope on the skin and these were;

• Placing directly on the skin
• Rubbing on the skin
• Rolling on to the skin

Since for each way to apply the IF there were three ways to apply the dermatosope, there were a total of 9 ways to study.

Results

IF selection: The study showed that the alcoholic IFs had the fewest air bubbles and among them isopropanol had the least. The study, however, preferred ethanol over isopropanol since ethanol does not have the latter’s unpleasant odor and, unlike the alcohol disinfectants, it evaporates leaving no crystals. Liquid paraffin had the highest number of air bubbles.

The study found alcoholic IFs unsuitable for use around the eyes, mucosa, lips, nails and the genitalia since they produce a burning sensation at these places. Instead, ultra sound gel was recommended at these places as being viscous they do not flow. These gels are recommended for all places where liquids should not flow as in convex surfaces and papular lesions.

Liquid paraffin was the least preferred IF for the patients because of its oily feel. They did not mind the other IFs. Liquid paraffin and ultrasound gels should be wiped off the skin as they tend to stick on the skin or stain the clothing.

IF and dermatoscope technique selection: It was found that, whatever the IF used, the combination of direct application of IF on the skin by an eye dropper and the roll-on technique for dermatoscope produced the least air bubbles.

Spraying IFs produced maximum air bubbles and also patient discomfort since only alcoholic IFs could be sprayed, and the alcohol evaporation made the skin quite cold. Liquid paraffin and ultra sound gel were too viscous to be sprayed or applied by an eye dropper. Ultra sound gel was applied direct from the bottle.

Applying the IF directly on the dermatoscope ensures, unlike in other techniques, that the entire glass is covered but compared to direct application on the skin, this procedure produces more bubbles. A quicker way is to place the dermatoscope directly on the skin and immediately tak a a photograph but this also produces many bubbles. Rubbing the dermatoscope after placing it on the skin squeezes out some air bubbles but not all.

Picture clarity was the best with alcohol disinfectant, ethanol and isopropanol, with hardly any difference between them. Water and aqueous disinfectants gave good, though not so sharp, pictures. Some ultra sound gel images were blurred.

Conclusions

Alcoholic IFs because of low viscosity and disinfectant properties were the best IFs. Though isopropanol had the least air bubbles, ethanol was preferred because it has less odor, does not stain and evaporates without leaving crystals.

The more viscous ultrasound gels should be used around the mucous areas, eyes, lips, nails, and genitals because they don’t flow. Moreover, alcohol produces burning sensations at many of these places.

The method of direct application of IF on the skin by an eye dropper combined with the roll-on technique for dermatoscope application gave the best results.