A virtual automated process to aid

Abdominal Aorta Aneurysm diagnosis and

treatments

Dr. Simone Bartesaghi, PhD

Prof. Giorgio Colombo

Simone Bartesaghi

2 Summary

1. Topic and main objective of the research

2. State of the art

3. Methodological approach

4. Validation

5. Virtual Surgery application of the CFD Embedded

process

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Topic and main objective of the research

3

Fast response Cost reduction

Ethics: from

IN-VIVO to

IN-SILICO (Virtual)

Mortality /year

15.000 USA 6000 in Italy

Dead in minutes in case of rupture 50% of the time..

Size of AAA diameter…

When surgical intervention ?

Max AAA diameter

5,5 cm for MEN

5,0cm for WOMEN

SPECIFIC TOPIC

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Topic and main objective of the research

4

Sometimes the only diameter is not enough for risk

evaluation; necessity of more information about the

disease:

HEMODYNAMICS INDICES GIVE THE RISK LEVEL

LITERATURE REVIEW: RULE OF THE INDICATORS

USEFUL IN DIAGNOSTIC

NUMERICAL (CFD)

OSI LEVEL ( > 0.45), TAWSS LEVEL ( < 0.4Pa and > 15Pa )

are indicators of possible complicance

T

dttsWSS

TdttsWSS

OSI

0

,

0

,

15.0 T

dttsWSST

TAWSS

0

,1

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Topic and main objective of the research 5

AUTOMATIC WORKFLOW FOR RISK EVALUATION IN ABDOMINAL

AORTA ANEURYSM

SETUP PHYSICS

STRATEGY

RUN SIMULATION

EXPORT DATA

PERFORM TIME

INTEGRATION

COMPUTE

HEMODYNAMIC

INDICES

3D RENDERING

WITH SCALAR

DISTRIBUTION

READ THE CAD

MODEL

GRID GENERATION

STRATEGY

BOUNDARY LAYER

BOUNDARY

CONDITIONS

AAA DIAMETER:

4,8 CM

SEGMENTATION

TECHNIQUE

STRATEGY

COMPUTE

GEOMETRIC

PROPERTIES

BOUNDARY

EXTRUSION

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

State of the art

6

DIAGNOSTIC BY NUMERICAL APPROACH (CFD)

ALREADY EXIST!!

Standardization of Computational Fluid Dynamic (CFD) Techniques Used

to Evaluate Performance and Blood Damage Safety in Medical

Devices: An FDA Critical Path Initiative

EU project HAEMODEL

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Methodological approach

7

USUAL CFD IN CLINICAL APPROACH: LIMITATIONS

• Lack of CFD experts inside clinics, simulations done

outside clinics

• CFD simulations done with “State of the Art” manual

approach

• High costs/time because of the non automatic approach

CFD IN EMBEDDED APPROACH: BENEFITS

• Direct process from DICOM to OSI/TAWSS distribution

• Automatic workflow begins immediately with the CT scan

• Less costs/time (no CFD expert)

CLINICS NEED AN AUTOMATIC PROCESS TO AVOID

EMPLOYING CFD EXPERTS

NECESSITY TO DEFINE CERTAIN FEATURE

(GEOMETRY, CFD MODELLING, COMPUTING,

VISUALIZATION, REPORTING)

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Methodological approach

8

% 60IT-100IT % 30IT-60IT

SEGMENTATION and THRESHOLD LEVELS

P4

P1

SMOOTHING

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Methodological approach

9

BOUNDARY EXTRUSION

NO EXTRUSION IN-OUT EXTRUSION

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Methodological approach

10

• Read the CAD model

• Grid generation

• Boundary conditions

BASED ON EXTRACTED RULES:

Mesh topology: tetrahedral, polyhedral, hexahedral

Mesh sensitivity study: verification procedure proposed by

Roache

Boundary layer: influence of the number of prisms layer

Spatial dimension: 2D vs 3D for standard benchmark

geometry and systematic geometry variation

WALL NO-SLIP

OUTLET

FLOW SPLIT

VELOCITY

INLET

BENCHMARK

AUTOMATIC PRE-PROCESSING

WORKFLOW PROCEDURE:

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Methodological approach

11

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Methodological approach

12

WSS, Re=450

MESH VERIFICATION

BL INFLUENCE

2D vs 3D

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Methodological approach

13

• Read the grid

• Setup physics

• Run simulation

• Export data

BASED ON EXTRACTED RULES:

Time step: verification procedure proposed by Roache

Iteration: verification procedure proposed by Roache

Fluid rheology: Newtonian vs non-Newtonian

Algorithms: discretization order in space and in time,

coupling algorithm

Steady vs Unsteady: diastolic, systolic and Womerslay cycle

Viscous solver: laminar and LES

AUTOMATIC WORKFLOW

PROCEDURE TO SETUP AND RUN

THE SIMULATION

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Methodological approach

14

TIME STEP

ITERATIONS

NEWTONIAN

NON NEWTONIAN

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Methodological approach

15

LAMINAR solver LES solver

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Methodological approach

16

OSI TAWSS AVERAGE

VELOCITY

• Read CFD data

• Perform time integration

• Compute hemodynamic

indices

• 3D rendering with scalar

distribution

WSS RRT

AUTOMATIC WORKFLOW

PROCEDURE TO:

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Methodological approach

17

AUTOMATIC PROCESS CONCEPTS: RULES AND KNOW-HOW

DICOM

StarCCM+ mesher

StarCCM+ solver

INPUT

OUTOPUT

TOOL

OUTOPUT

OUTOPUT

OUTOPUT

TOOL

TOOL

TOOL

*.stl

*.ccm

*.case

*.pdf

*.java

*.sim

*.py

*.dcm

*.txt

Simone Bartesaghi

Validation

18

CLINICAL APPLICATIONS

• 1st step: application of the embedded procedure for the

meshing, computing and visualization phase; two patient-

specific CFD-ready anatomy cases are provided by Nuovo

Ospedale di San Giovanni di Dio, Firenze, CAD model by

Alamanni, et al. (2012).

• 2nd step: application of the entire workflow, with also the

rule-based optimal procedure to reconstruct the 3D

anatomy. Two public domain DICOM PACS

(http://www.osirix-viewer.com/datasets/) are used to perform

this step

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Validation

19

CLINICAL APPLICATIONS, 1st step

1 year ago

before rupture

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Validation

20

1 year ago

before rupture

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Validation

21

CLINICAL APPLICATIONS, 2nd step

DP1 DP2

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

P1 P4

Validation

22

CLINICAL VALIDATION

A first step in the validation procedure is done by:

• Comparing 3D embedded results with an extensive 2D

simulation (Alamanni, et al. 2012).

• DICOM images from Nuovo Ospedale di San Giovanni di

Dio, Firenze

P1

P4 • Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Validation

23

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Virtual Surgery

24

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

D B C

A

Simone Bartesaghi

Virtual Surgery

25

BEFORE STENT AFTER STENT

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Virtual Surgery

26

BEFORE STENT

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

Virtual Surgery

27

AFTER STENT

• Summary

• Research topic

and main

objective

• State of the art

• Methodological

approach

• Validation

• Virtual Surgery

Simone Bartesaghi

28

• Prof. Giorgio Colombo, Politecnico di Milano

• Dr. Neri Alamanni, Dr. Marco Lotti, Configuratori.it

• Dr. Emiliano Chisci. Medico Chirurgo Specialista in Chirurgia Vascolare,

Firenze

• Ospedale “Nuovo Ospedale di San Giovanni di Dio (TORREGALLI)”, Firenze

• Dr. Raffaele Ponzini, CINECA, SCAI HPC dep.

• Dr. Luca Antiga, OROBIX, VMTK developer

• Dr. Anthony Massobrio and Ing. Carlo Pettinelli, CD-adapco, TorinoUniversity

Acknowledgement

CONTACTS:

Simone Bartesaghi, PhD

• simone.bartesaghi@gmail.com

• www.simonebartesaghi.com