mavis-ii measurement of area and volume instrument system for skin wounds c.d. jones, p. plassmann...
TRANSCRIPT
MAVIS-II Measurement of Area and Volume Instrument System for Skin Wounds
MAVIS-II Measurement of Area and Volume Instrument System for Skin Wounds
C.D. Jones, P. PlassmannUniversity 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
Principle Hardware Software Competitors Development Examples Performance
Stereo – Photogrammetry• displacement between corresponding
points in stereo images = distance
• challenge: finding corresponding points
d
Left Image
Left Image
Right Image
Right Image
camera / eyes
displacementobject 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 reconstructionfalse reconstruction
positivevolume
negativevolume
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 700 • 9 kg, laser scanner• £ 70,000
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 !
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 >40 cm²
wound 10-40 cm²
wound<10 cm²
0
2
4
6
8
10
12
rulers tracings digital photography
Precision error range
(one standard deviation as % of wound area)
MAVIS
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 Scanners casts rulers
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 viaconsistency 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:
www.MedImaging.org/Mavis