YA Anisha, Potturi Ramacharan, PK Ashwini, SG Chethana, Garehatty R Kanthraj
From the Department of Dermatology, Venereology and Leprosy, JSS Medical College and Hospital, JSS Academy of Higher Education and Research (Deemed to be University) Mysuru, Karnataka, India
Correspondence Address:
Garehatty R Kanthraj
Department of Dermatology, Venereology and Leprosy, JSS Medical College and Hospital, JSS Academy of Higher Education and Research (Deemed to be University) Mysuru, Karnataka
India
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/ijd.ijd_656_22
Sir,
Measurement of psoriasis and leg ulcers by counting the crossover points has been described by Bahmer et al.[1] Smartphone applications and computer software for the measurement of skin for follow-up care have been established.[2],[3] Variations in distance and angle of image capture can alter the dimensions. Attempts were made to obtain consistent images.[4] We propose, demonstrate, compare and analyse two practical methods— pre-set grid and grid app methods with respect to capturing images for maintaining constant dimensions.
This study was performed at the Department of Dermatology, JSS Hospital, JSSAHER, Mysuru from October 2020 to February 2021. Plaque Psoriasis and Tinea corporis with well-defined lesions were included.
Digital photographs were captured from two different angles and distances—overview shots from 15 and 30 cm by the principal investigator using Iphone11 (Apple.inc, California, USA) and lateral view shots from 15 and 30 cm by the second author using Oneplus7T (Oneplus Tech, China) in standard light setting without flash.[5]
In pre-set grid method, a standard graph (1 × 1 cm) was printed over a thin A3 flexible transparent sheet which served as a pre-set grid. An estimated portion of the grid was cut and placed over the lesion [Figure 1]. Our pilot trial revealed that the crossover points were constant when the grid was superimposed in a manner such that two edges of the grid touch the margin of the lesion [Supplementary Video].
Figure 1: Illustration of results of crossover point counts in pre-set and grid app method in one of the cases of psoriasis. In pre-set grid method, the grid was superimposed in a manner that two edges of the grid touched the margin of the lesion. In the grid app method, the grid automatically superimposes over the captured image. The number of crossover points remains constant irrespective of the change in distance or angle of image capture in pre-set grid method. However, in the grid app method, crossover point count varies with change in distance and/or angleIn the grid app method, an area calculator app (Grid#, Wang JP, China, version 2.9.1, Apple Store) was used. The captured image gets automatically superimposed by a digital grid. Area in both the methods was obtained by noting the number of crossover points[1][Figure 1]. The differences in the number of crossover points between the two methods were compared and analysed. Statistical analysis was performed by paired sample t-test and software version–SPSS 20.0 (SPSS inc., IBM, NY, USA).
There were 25 patients (15-Psoriasis and 10-Tinea corporis)—16 males and 9 females with a mean age of 42 years. The results were comparable when the pre-set grid and grid app methods were used to measure the lesion at 15 cm overview [Supplementary Table] and [Table 1]. Whereas, in 30 cm overview, 15 cm and 30 cm lateral view, the results showed significant variation between the two methods [Table 1]. The two methods are easy and take an average of two minutes.
Table 1: Summary of results obtained after independent sample t test for pre-set grid and grid app methods at 15 and 30 cm in both over and lateral viewsConsistency in measurement is achieved irrespective of varying distance and/or angle in pre-set grid. However, in the grid app, overview image capture at a fixed distance obtains consistency.
The differences in the values of the crossover points could be due to the grid being at the level of the smartphone in the grid app method, whereas the grid in pre-set grid is at the level of the lesion.
Ill-defined lesions are limitations. We observed that glare encountered due to reflection on the gridsheet was not a barrier for point counting. Serial assessment can be performed by point counting of captured images. The two methods may have significance in future teledermatology practice.
Acknowledgment
Authors are thankful to Dr. Lancy D'souza PhD, Associate Professor in Psychology, Maharaja's College, University of Mysore, Mysore, Karnataka, India for research consultancy and statistical analysis of the data. We acknowledge JSS Academy of Higher Education and Research (JSS AHER) (deemed to be university) for their constant academic encouragement and constructive suggestions in completing this project.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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