Imaging Protocol
This page describes the image capture methodology, quality control system, and protocol flexibility available for atopic dermatitis clinical trials using Legit.Health.
Smartphone-based capture
Legit.Health uses standard smartphone cameras for image acquisition. No specialised photography equipment is required.
Traditional clinical photography often relies on systems like Canfield VISIA, which require per-site hardware, per-site calibration, and significant rental or purchase costs. Smartphone-based capture eliminates these costs while maintaining the image quality needed for AI scoring.
The Legit.Health mobile application guides investigators through the capture process with visual perspective silhouettes, real-time DIQA quality checks, and immediate feedback on image adequacy.
Standard body area protocol
Atopic dermatitis affects multiple body areas. The standard protocol captures photographs covering all clinically relevant regions:
| Body area | Perspectives | Coverage | Notes |
|---|---|---|---|
| Face | 1 frontal | Periorbital, perioral | High-priority for facial AD |
| Neck/chest | 1 frontal | Anterior trunk, neck folds | Flexural involvement |
| Back | 1 posterior | Posterior trunk | Large surface area |
| Arms (bilateral) | 2 (left, right) | Antecubital fossae, dorsal surface | Key flexural sites |
| Legs (bilateral) | 2 (left, right) | Popliteal fossae, anterior surface | Key flexural sites |
| Hands | Optional | Palmar and dorsal | Per protocol requirement |
The protocol is configurable to match the study's body area coverage requirements. All images are validated in real time by the DIQA algorithm before submission.
Capture time
The full body area protocol takes approximately 3–5 minutes using the guided Legit.Health mobile application. The app provides perspective silhouettes and real-time quality feedback for each image.
Alternative perspective protocols
The number and type of body areas captured can be adapted to match any study protocol:
| Protocol | Perspectives | Use case |
|---|---|---|
| Full body | 7–9 perspectives | Complete SCORAD with BSA |
| Flexural focus | 4 perspectives (antecubital + popliteal) | Flexural-dominant AD |
| Face only | 1–3 perspectives | Facial AD studies |
| Target lesion | 1–2 perspectives | Intensity scoring only (no BSA) |
DIQA: Dermatology Image Quality Assessment
What is DIQA?
DIQA (Dermatology Image Quality Assessment) is an AI-powered image quality assessment algorithm that evaluates every captured image in real time before it is accepted for analysis. It was developed by Legit.Health and published in the Journal of the American Academy of Dermatology (Hernández Montilla et al., 2023).
What DIQA evaluates
| Quality dimension | What it checks | Why it matters |
|---|---|---|
| Focus | Sharpness of the image; absence of motion blur | Out-of-focus images can obscure small lesions, leading to undercounting |
| Lighting | Adequate, even illumination; absence of harsh shadows or glare | Poor lighting creates shadows that mimic or hide lesions |
| Framing | Correct anatomical region captured at the required angle | Incorrect framing means the AI analyses the wrong area |
| Resolution | Sufficient pixel density for lesion detection | Low resolution makes small features undetectable |
How it works in the workflow
- The investigator captures an image through the mobile application
- DIQA evaluates the image immediately (sub-second processing)
- If the image passes: it is accepted and queued for AI scoring
- If the image fails: the investigator receives immediate feedback explaining the quality issue and must recapture
Configurable thresholds
The DIQA pass/fail threshold is configurable per study protocol. Sponsors can choose stricter thresholds for pivotal studies (rejecting more images to ensure the highest quality) or more lenient thresholds for real-world evidence studies.
Patient preparation
- Remove clothing from the area being photographed
- No moisturiser or topical treatments applied within 2 hours of the visit (unless protocol specifies otherwise)
- Hair pinned back for face and neck assessments
- Remove jewellery from the area being photographed
- Neutral, well-lit background; standard smartphone flash or even natural light
Environmental conditions
- Patient positioning: Seated or standing comfortably, remaining still during capture
- Background: Neutral, non-reflective background to reduce artefacts
- Lighting: Well-lit environment with even illumination. Natural light or smartphone flash can be used. Avoid harsh directional lighting that creates deep shadows.
- Distance: Approximately 30–50 cm from camera to skin surface, adjusted per body area
Consistency across visits
The most important principle is consistency: the same lighting conditions, the same distance, the same angles, and the same patient preparation at every visit. Consistent capture conditions ensure that score changes between visits reflect actual clinical changes, not variations in image acquisition.
Anonymization
All photographs are processed with automatic face anonymization. The system applies irreversible blurring to facial features, ensuring patient privacy for stored and exported images.
Irreversible face blurring applied