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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 Measurement of Area and Volume Instrument System for Skin Wounds. MAVIS - II. Introduction (1 of 4). Why Wound Measurement? Chronic wounds are frequent:

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MAVIS-II Measurement of Area and Volume Instrument System for Skin Wounds

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

  2. MAVIS - II Introduction (1 of 4) • 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 Introduction • MAVIS-I • MAVIS-II • Status • Principle • Hardware • Software • Competitors • Development • Examples • Performance venous leg ulcer

  3. MAVIS - II Introduction (2 of 4) • 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 Introduction • MAVIS-I • MAVIS-II • Status • Principle • Hardware • Software • Competitors • Development • Examples • Performance diabetic foot ulcer

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

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

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

  7. MAVIS - II MAVIS - II • 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 • Introduction • MAVIS-I MAVIS-II • Status • Principle • Hardware • Software • Competitors • Development • Examples • Performance

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

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

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

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

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

  13. MAVIS - II Competitors (1 of 2) • Introduction • MAVIS-I • MAVIS-II • Status • Upper ranger: Minolta Vivid 700 • 9 kg, laser scanner • £ 70,000 • Principle • Hardware • Software Competitors • Development • Examples • Performance • Lower range: Minolta 3D 1500 • 0.5 kg, structured light • £ 2,500 • And many others in-between • EOIS “Handy”, Inspec “3D Body Builder”, ….. • common feature: • no wound measurement software !

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

  15. MAVIS - II Future Developments • Introduction • MAVIS-I • MAVIS-II • Status • 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 • Principle • Hardware • Software • Competitors Development • Examples • Performance

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

  17. MAVIS - II Performance (1 of 3) Precision error range (one standard deviation as % of wound area) 12 MAVIS 10 8 6 wound<10 cm² 4 wound 10-40 cm² 2 wound >40 cm² 0 rulers tracings digital photography • Introduction • MAVIS-I • MAVIS-II • Status Wound Area • Principle • Hardware • Software • Competitors • Development • Examples Performance

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

  19. MAVIS - II Performance (3 of 3) • Introduction • MAVIS-I • MAVIS-II • Status • Calibration • against NPL precision artifacts • user control viaconsistency checker • Principle • Hardware • Software • Competitors • Development • Examples Performance

  20. MAVIS - II Summary so far… MAVIS – II is: • Introduction • MAVIS-I • MAVIS-II Status • 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: • Principle • Hardware • Software • Competitors • Development • Examples • Performance www.MedImaging.org/Mavis

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