diagnosis of dti - npuap€¦ · diagnosis of dti ‐ engineering view ‐ makoto takahashi, d....

DiagnosisofDTI‐EngineeringView‐

MakotoTAKAHASHI,D.Eng.

HokkaidoUniversity,Japan

2002‐2007‐2012/2013

PresentaHonaboutShearForceatEPUAPin2002

2002‐2007‐2012/2013

Dr.JoyceBlack

(NPUAPPresident)

VeryimportantconferenceTurningpoint

Many UnKnowns about Shear Force

Dr. Laura EdsbergNPUAP at San Antonio in 2007

2002‐2007‐2012/2013UnKnowns! UnKnowns! UnKnowns!

2002‐2007‐2013

‘Tenyears’past…..!

Couldweextendourknowledge?What’snewtoday?

Today’sTopics

• FORCEontheskinsurface

• FEMmodelattheHIPandHEEL

• Bloodflowattheforearmunderpressureandshearforce

• UltrasonographyforDTI

Today’sTopics




• UltrasoundgraphyforDTI

NPUAPSTAGE(2007)

STAGEISTAGEIISTAGEIIISTAGEIV

SuspectedDeepTissueInjury Unstageable/Unclassified

h]p://minds.jcqhc.or.jp/n/medical_user_main.php

SuspectedDeepTissueInjury–depthunknown

• Purpleormaroonlocalizedareaofdiscoloredintactskinorblood‐filledblisterduetodamageofunderlyingsodHssuefrompressureand/orshear.TheareamaybeprecededbyHssuethatispainful,firm,mushy,boggy,warmerorcoolerascomparedtoadjacentHssue.DeepHssueinjurymaybedifficulttodetectinindividualswithdarkskintones.EvoluHonmayincludeathinblisteroveradarkwoundbed.Thewoundmayfurtherevolveandbecomecoveredbythineschar.EvoluHonmayberapidexposingaddiHonallayersofHssueevenwithopHmaltreatment.h]p://www.npuap.org/resources/educaHonal‐and‐clinical‐resources/npuap‐pressure‐ulcer‐stagescategories/

Causes of Tissue DamageInternal Factors:

Tissue / Cell Integrity

Anatomical Structure

etc

External / Interface Factors:

External Force

Skin Contact Conditions

Temperature and Humidity

Toxicity etc

etc

External Force

One of the Most Risk Factors

which causes Tissue Damage

z

x

yShear Force

Shear Force

Pressure

P

Z torque

Y torque

X torque

Force on Skin Surface

Three linear forces

Pressure, Shear

Three rotational forces

Six Degrees of Freedom

1st Shear Force Initiative

was started at 8th EPUAP,2005 in Aberdeen

Analysis of External Force Evaluation and Measurement

TwoDsofFinMarkeHng(Predia,molten)

One axis type strain gauge detects a shear force at skinsurface which is parallel to the skin

A self-inflatable air balloon measures a pressure whichis normal force at skin

96mm

70mm

Face：Shear force sensor

Back：Surface pressure sensor

Where

Skin Surface and Shallow Tissue

Middle Tissue

Deep Tissue

Where and How Shear Force works in Tissue

How

Shear Force at Skin Surface

Normal Force at Skin Surface

Today’sTopics





NormalForceatSkinSurfacechangestoShearForceatDeepTissuewithBonyProminence

Normal+ShearForceatSkinSurfacechangestoBigShearForceatDeepTissuewithBonyProminence

FiniteElementMethod(ModifiedModelfromChow(1978))

3D 3layerbuttock model

Bone

Muscle Fat

Skin

Future works

Today’sTopics





Blooddynamicsoftheskinandtheradialartery

Motorand

Gear Box

A/D000

PC BaseInstrument

PC

D/A

Pressure

Ultra soundinstrument

US probe

Indenter

Laser prove

Laser DopplerBlood Flowmeter

Radial artery

Shearforce

Pressure

Ball Screw

Load CellShear force

Blood Flow

Blood Velocity

Blood Volume

Pressure+ShearForece

Pressure75 mmHg

ShearForce

!

!"#

!"$

!"%

!"&

'

'"#

! !"#( !"( !")( '

Shear Force [N/cm²]

Nor

mal

ized

Blo

od F

low

SkinCapillary

RadialArtery

100 mmHg

50 mmHg

75 mmHg

ANCOVA **p < 0.01

*p < 0.05

**

*

Blood flow with Pressure and ShearForce

Blood flow of the radial artery more decrease

Today’sTopics





UltrasonographyforDTIResearch• Bedsidemeasurement

• LowcostfordataacquisiHon

Boneshape,SodHssuethickness,Skinshape

• ShortHmeforacquisiHon–abouttenminutes

• Bodyshapedatabydigitalcamera

• ElasHcitymeasurementbydurometer

UltrasonographyforDTIResearch• Subjectswerefourelderlies

• SixultrasonogramweretakenatlateralposiHon

median:redline horizontal:greenline

• Ittookintenminutes

Bonemodel Measurementskinregion

UltrasonogramofMediancrosssecHon

Z

X

Y

Subject2(T.O)83yrsH138cmBW30.9kg

UltrasonogramofHorizontalcrosssecHon

X

Y

26

Z

Subject2(T.O)83yrsH138cmBW30.9kg

MediancrosssecHon

Sacralcrest

Base27

HorizontalcrosssecHon

28

Sacralcrest

Base

CurvefipngfromBoneImaging

MediansecHon(0.5mminterval)

29

Sacralcrest

Base

HorizontalsecHon(0.5mminterval)

MediansecHon(0.5mminterval) HorizontalsecHon(0.5mminterval)

ExtrapolaHonoftheSacralcrest

30

TissuelayerThicknessofSubjects

ThicknessoftheSkin

ThicknessoftheSodHssuelayersismeasuredbyUSimaging

（a）thicknessofHssue

ThicknessoftheFatlayer

Sacralcrest

（b）differenceinthickness

skinfat

Total

Simplified3DSacralmodel

• ThemodelwasconstructedbySimulaHonsodware(ANSYS)ofFiniteElementMethod(FEM)

• VolumerenderingaderextrapolaHonusingthesplinecurvesforthesacrum,thefatlayerandtheskin

(b)Thesacrum,FatandSkin（a）thesacralcrestandthebase　

Sacrum

Fat

Skin

FEMmodelanditsmaterialproperHes

• Elementtypeistetrahedronandtennodes• Numbersofelementsarearound100,000• BoneandSkinarelinearelasHc(Table1)• FatlayerissuperelasHcofOgden‐Foam

model(Table2)

Table1.BoneandSkinlayer

Ogden’sEquaHon

Table2.Ogden‐Foamparameters

SimplifiedSacralregionmodelWuetal.,2002

Yang’smodulus（MPa）

Poisson’sraCo

Bone 20000 0.3

Skinlayer

0.85 0.49

μ1（kPa） α1 μ2（kPa） α2 μ3（kPa） α3 β

‐181.15 5.511 30.69 6.571 153.64 5.262 2

• Solidplateispushed3mmdown

• HighvaluesofequivalentstressarefoundatboundariesofHssues

• Lowstressaccordingtomorethickness

Results

MediansecHon(sbjST) thicknessvs.stress

[MPa]

SuspectedDeepTissueInjury

sDTImodelandUSImaging

DTIisdefinedasafuncHon

Nextstepstodo

Summary‐fromNewDeepWorld

• 2007NPUAPconferencewasepoch‐makingfromsurfacetodeepregion

• Overseveraldecades,wehaveinvesHgatedpressureulcersatthe‘Shallow’area

• Inthisdecade,wehavepreparedsometoolstoresearchinto‘Deep’region

It’sBmetogrowin‘Deep’knowledgefromNew‘Deep’World!

diagnosis of dti - npuap€¦ · diagnosis of dti ‐ engineering view ‐ makoto takahashi, d....

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