Clinical usefulness of objective tongue image devices monitoring in temporal tongue color: a demonstration of successively treated cases with traditional medicines.

BACKGROUND: In Kampo medicine (traditional Japanese medicine), the diagnostic method of observing a patient's tongue is called the 'tongue diagnosis'. Information provided by observation of a patient's tongue is used to help select prescriptions at the initial consultation, monitor treatment effectiveness after therapy begins, and determine whether prescriptions should be changed. Kampo practitioners must therefore accurately compare the patient's past tongue condition with the current condition. However, it can be difficult to remember the precise details regarding a patient's previous tongue's appearance and to consistently make accurate comparisons. Given the need for objective and reproducible method of documenting tongue findings, we investigated the usefulness of our developed Tongue Image Analyzing System (TIAS). The application of the TIAS for two representative patients is described herein.

METHODS: We retrospectively reviewed patients who underwent tongue photography after providing informed consent and selected two cases with contrasting degrees of longitudinal changes in tongue findings. One patient demonstrated subtle changes in tongue color that were difficult to detect with the naked eye, and the other patient showed marked tongue color changes accompanied by changes in the heterogeneity of the tongue coating. We obtained the tongue color values in each case from tongue images photographed by TIAS as RGB data and converted into the CIE L*a*b* color space.

RESULTS: The tongue color of case1 was analyzed at three time points. The color difference from the first consultation (calculated as ΔE 00 using L*a*b* values) increased by ΔE 00 1-2 after 42 days. This change was too subtle to be perceived by the naked eye. The tongue color of case 2, tongue color was analyzed at five time points. The color difference between the first consultation and 105 days later was ΔE 00 10.08, indicating a substantial change in tongue color.

CONCLUSION: TIAS enables standardized longitudinal tongue imaging and facilitates the objective and quantitative comparison of subtle changes in tongue color that may be difficult to discern visually. These findings suggest that TIAS may be useful for objectively documenting and comparing longitudinal changes in tongue findings in clinical practice.