The Absence of Medical Visual Language Standardisation: An Inclusive and Usability Design Challenge

Introduction: Medical imaging operates as a visual communication system through which clinicians interpret complex physiological data. In cardiology, modalities such as echocardiography, MRI and CT, rely on colour scales, contrast gradients and symbolic cues to convey diagnostic meaning. However, while technical standards govern data acquisition and formatting, there is no unified framework/standard regulating how visual information is presented. This absence introduces variability in interpretation, increases cognitive load, and raises challenges for inclusive design. Differences in clinical experiences, neurodiversity, age, cultural interpretation of colour, and colour-vision deficiency may all influence how imaging outputs are understood. This review aims to evaluate how the absence of standardised visual language in medical imaging affects usability, diagnostic interpretation, and inclusive design outcomes.
Methods: A narrative review was conducted across PubMed, Google Scholar and regulatory repositories (ISO, FDA, MHRA). The literature search covered a ten-year period (2015-2025) and used the following search terms: "colour coding," "semiotics," "cardiology imaging," "medical visual communication," "standardisation," and "usability engineering." Eleven relevant publications were analysed.
Results: The literature shows that colour and semiotic indicators act as cognitive scaffolds that shape diagnostic reasoning. Variations in colour mapping and display calibration can influence accuracy and response time, with perfusion MRI studies reporting differences of up to 18% depending on colour scale selection (Zabala-Travers et al. 2015). Inconsistent symbol conventions and interface logic across platforms increase mental workload by requiring clinicians to translate between visual systems (MHRA 2021). Although usability standards prioritise clarity and consistency, they do not regulate visual semiotics in imaging environments (ISO 62366-1:2015). This lack of standardisation may disproportionately affect interpretation, speed, and decision-making across differing expertise, and colour sensitivity, raising broader inclusive design concerns.
Conclusion: Medical imaging should be understood as a designed communication system rather than a neutral technical output. Colour mapping and symbolic variability influence interpretation and cognitive workload, yet limited research examines how these systems perform across clinicians with differing expertise/experiences. Could standardised colour hierarchies reduce diagnostic variability? Does navigating heterogeneous imaging systems increase cognitive load? And how inclusive are current visual conventions? Developing a coherent medical visual language offers a pathway to improving interpretive reliability. Given that medical error remains a leading cause of mortality in the United States, the absence of validated visual standards warrants recognition as a safety concern. Visual standardisation should therefore be positioned not as aesthetic refinement, but as a patient-safety and inclusive design responsibility within healthcare systems.

References:
ISO. (2015). ISO 62366-1:2015 Medical devices — Application of usability engineering to medical devices — Part 1: Application of usability engineering. Geneva: ISO. https://www.iso.org/standard/63179.html

Medicines and Healthcare products Regulatory Agency (MHRA). (2021). Guidance on applying human factors and usability engineering to medical devices. Version 2.0. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/970563/Human-Factors_Medical-Devices_v2.0.pdf

Zabala-Travers, S., Choi, M., Cheng, W.C. and Badano, A., 2015. Effect of color visualization and display hardware on the visual assessment of pseudocolor medical images. Medical Physics, 42(6), pp.2942–2954. https://doi.org/10.1118/1.4921125