MAVIS-II Measurement of Area and Volume Instrument System for Skin Wounds C.D. Jones, P. Plassmann University of Glamorgan, Medical Computing Research Group

MAVIS - II Introduction  MAVIS-I  MAVIS-II  Status Introduction (1 of 4)  Principle  Hardware  Software  Competitors  Development  Examples  Performance Why Wound Measurement? Chronic wounds are frequent: 8% of bedridden/chairbound patients develop pressure ulcers 3.5% of all adults in the USA suffer from venous leg ulcers alone Wounds are costly: Approx. £ 500 million annually in the UK venous leg ulcer

MAVIS - II Introduction  MAVIS-I  MAVIS-II  Status Introduction (2 of 4)  Principle  Hardware  Software  Competitors  Development  Examples  Performance Why Wound Measurement? Wounds need to be healed: objective information required monitor progress of healing wound assess influence of clinical interventions increasingly important: litigation verify clinical trials diabetic foot ulcer

MAVIS - II Introduction  MAVIS-I  MAVIS-II  Status Introduction (3 of 4)  Principle  Hardware  Software  Competitors  Development  Examples  Performance Existing techniques Area: transparency tracings or photographs 2D only inaccurate (especially on curved wounds) contact with wound  pain, infection Smith & Nephew ‘Visitrak

MAVIS - II Introduction  MAVIS-I  MAVIS-II  Status Introduction (4 of 4)  Principle  Hardware  Software  Competitors  Development  Examples  Performance Existing techniques Volume: fill wound with measured amount of saline or alginate paste messy & time-consuming inaccurate contact with wound  pain, infection

MAVIS - II  Introduction MAVIS-I  MAVIS-II  Status MAVIS - I  Principle  Hardware  Software  Competitors  Development  Examples  Performance Data sheet 110 kg, trolley mounted £ 15,000, only 6 sold non-contact structured light principle

MAVIS - II  Introduction  MAVIS-I MAVIS-II  Status MAVIS - II  Principle  Hardware  Software  Competitors  Development  Examples  Performance Data sheet light, about 1.5 kg, compact non-contact inexpensive to build, few custom parts accuracy & precision better than MAVIS-I full-colour stereo-photogrammetry principle “intelligence” in software not hardware no moving mechanical parts

MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Principle  Hardware  Software  Competitors  Development  Examples  Performance Stereo – Photogrammetry displacement between corresponding points in stereo images = distance challenge: finding corresponding points d Left Image Right Image camera / eyes displacement object point 1 object point 2 left stereo image right stereo image

MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Hardware (1 of 2)  Principle Hardware  Software  Competitors  Development  Examples  Performance Off-the-shelf components any high-resolution digital camera with standard lens adapter & flash stereo adapter (slightly modified) laptop or PC camera + stereo adapter

MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Hardware (2 of 2)  Principle Hardware  Software  Competitors  Development  Examples  Performance In-house range finder

MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Software (1 of 2)  Principle  Hardware Software  Competitors  Development  Examples  Performance Modular design 3-D displacement engine user delineation tool

ulcerated limb correct reconstruction false reconstruction positive volume negative volume MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Software (2 of 2)  Principle  Hardware Software  Competitors  Development  Examples  Performance Modular design ‘minimum surface’ reconstruction measurement, visualisation & output module

MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Competitors (1 of 2)  Principle  Hardware  Software Competitors  Development  Examples  Performance Upper ranger: Minolta Vivid kg, laser scanner £ 70,000 Lower range: Minolta 3D kg, structured light £ 2,500 And many others in-between EOIS “ Handy ”, Inspec “ 3D Body Builder ”, ….. common feature: no wound measurement software !

MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Competitors (2 of 2)  Principle  Hardware  Software Competitors  Development  Examples  Performance Most direct: Vista Medical “VeV 3D” standard digital camera no volume… …but excellent data base 1 year free trial / subscription or purchase

MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Future Developments  Principle  Hardware  Software  Competitors Development  Examples  Performance MAVIS-II improvements (in order of urgency) improve automation (e.g.: image transfer from camera initiated when camera placed next to laptop, then start software) “package” system (own cameras, flash) merging multiple images (e.g. for circumferential wounds) addition of colour analysis (analysis of inflammation / infection status) enable ”telemedicine” features and measurements as online services

MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Examples  Principle  Hardware  Software  Competitors  Development Examples  Performance No more wounds now measurement grid overlay all from a single ‘shot’

MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Performance (1 of 3)  Principle  Hardware  Software  Competitors  Development  Examples Performance Wound Area

MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Performance (2 of 3)  Principle  Hardware  Software  Competitors  Development  Examples Performance Wound Volume saline 0% 10% 20% 30% 40% 3D Scannerscastsrulers min. precision max. precision (large, shallow wounds) (deep, small wounds) precision error range (one standard deviation in % of the wound volume) MAVIS

MAVIS - II  Introduction  MAVIS-I  MAVIS-II  Status Performance (3 of 3)  Principle  Hardware  Software  Competitors  Development  Examples Performance Calibration against NPL precision artifacts user control via consistency checker

MAVIS - II  Introduction  MAVIS-I  MAVIS-II Status Summary so far…  Principle  Hardware  Software  Competitors  Development  Examples  Performance MAVIS – II is: unique inexpensive to manufacture, mainly from standard components lightweight and portable a precise tool for an increasingly important medical task More information, examples, FAQs, etc: