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
*.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