Use of Visia-CR Generation 7 in Aesthetic Skin Assessment
Historically, evaluations of laser treatments have involved subjective analyses. Recently, non-invasive skin imaging modalities that provide objective numerical measurements have become prominent in assessing the efficacy of facial rejuvenation treatments. One such modality is the VISIA-CR Complexion Analysis System. Previous research using this system has demonstrated its efficacy as an objective measure of facial skin. However, the version of this device developed for research includes many more metrics per analyzable feature, as opposed to the single value per feature previously provided. We aim to detail the measurement parameters the latest VISIA-CR system can capture along with their clinical relevance.
Methods/Technique
:The VISIA-CR system utilizes standard lighting to detect wrinkles, spots, pores, and texture and cross-polarized and UV lighting to detect subsurface skin features such as brown spots, red spots, UV spots, and porphyrins. For each feature, the VISIA-CR provides information on metrics including mean intensity, background intensity, intensity, mean contrast intensity, fractional area, count, and score. For the wrinkles feature, there are additional area parameters that calculate the area of wrinkles within various ranges of thickness, allowing the user to see the progression of coarse and fine wrinkles. For this review, we utilized the face of a healthy volunteer to demonstrate the meaning of the parameters the VISIA-CR Generation 5 can capture.
Results/Complications
:Per feature, there are four intensity metrics. Mean intensity (MI) measures the average intensity of detected features and background intensity (BI) measures the average intensity of the skin surrounding the detected features within a region of interest. Both range from 0 to 255, with lower values being darker. Mean contrast intensity (MCI) and intensity (I) are both measures of the difference the MI and BI, where MCI is the absolute value of the difference and I is the difference normalized to a value from -1 to 1. Thus, the lightness or darkness of the features themselves and the underlying skin can be determined both separately and together. Additional metrics include fractional area (FA) which describes the percentage of the region of interest made up of the detected feature, count (C) which details the individual number of detected features, and score (S) which is a measure of feature severity. S varies slightly depending on the feature, with S for spot algorithms (visible spots, UV spots, brown spots, and red spots) incorporating both FA and I whereas S for all other features is based only on FA. These metrics can be determined per feature in four views: frontal, left oblique, right oblique, and nose. The region of interest for each feature in the frontal view for our healthy volunteer is depicted in Figure 1. These images would be possible with the previous version of the VISIA imaging system, however, only a single value would be returned in the analysis of these images with that system.
For example, in the frontal view, our healthy volunteer had a MI of 93.01, a BI of 119.32, a FA of 15.41%, a C of 72, and a S of 0.33 for brown spots. This provides a more complete understanding than any one metric alone, as C may paradoxically increase while the FA decreases if spots are broken up. Likewise, with the breakdown in intensities, the greyscale intensity of the background skin and the feature of interest can be followed over time, which is particularly useful for studies conducted during times of high ultraviolet light exposure that may result in increased pigmentation of the overall skin. Laser treatments aimed at targeting pigment could thus be assessed in detail using these metrics.
Likewise, treatments aimed at improving texture or other features could also be assessed objectively this imaging system, allowing in-depth conclusions to be drawn from pre- and post-treatment photos. For the wrinkles feature, there are eight additional area parameters and a mean thickness (in millimeters) parameter that can be followed over time.
Conclusion
:Ultimately, the VISIA-CR is a valuable tool in the objective assessment of facial skin and can detail the greyscale intensity, area, count, and overall severity of eight different features involved in determining skin health. In this manner, it provides a more granular analysis compared to the previous version of the system.