Compatibilità dei Dispositivi Meccatronici nella …Compatibilità dei Dispositivi Meccatronici...
Transcript of Compatibilità dei Dispositivi Meccatronici nella …Compatibilità dei Dispositivi Meccatronici...
Compatibilità dei Dispositivi Meccatronici nella Risonanza Magnetica Interventistica e Funzionale
Vincenzo PositanoFondazione Toscana Gabriele [email protected]
Why we should use a mechatronic device inside MRI ?
Interventional MRI (i-MRI)ElastographyfMRI paradigms
State of Art
ISMRM 2008
State of Art
State of Art
Gassert et al, Eng Med Biol Mag, 2008
ISI Web 2008
Real time iMRIHigh image quality
High fieldsHomogeneityFast gradients
Interventional MRI (i-MRI)
3 T
4 TOpen, low field(1.0 T) MRI
7 T
9.4 T
1.5 T
Close, high field MRI
Robotic surgery
Eyes MR Images
Hands Mechatronic Devices
Interventional MRI (i-MRI)
Interventional MRI (i-MRI)
Gassert et al, Eng Med Biol Mag, 2008
Bricault et al, Eng Med Biol Mag, 2008
Surgeon compatibility☺
Functional MRI (fMRI)
StimulusStimulus Response
BOLD Signal
Detects MRI signal variation due to BOLD effect
Very low signal changes (< 5%)
Stimuli knowledge and recording is important
Functional MRI (fMRI)
Audio/video Audio/video Touch Touch
Waveguide
Scanner Room
Shielded Cable
Console Room
AcquisitionSetup: instrumentationampsNI-DAQ Card
Reproducibility, stability, and recording of the imposed stimulaReproducibility, stability, and recording of the imposed stimulation tion paradigm are needed.paradigm are needed.
Mechatronics devices may be employed to meet the requirements Mechatronics devices may be employed to meet the requirements
Functional MRI (fMRI)
Functional MRI (fMRI)
Vanello et al, IEEE Trans Mechatronics, 2008
MARIARC, Liverpool, UK
MR Compatibility
MR safe (no hazard)
MR compatible (preserves image quality)
MR Compatibility
Static magnetic field1.5 -3.0 T
RF63 -126 Mhz
Gradients20-50 mT/s
Safety: static magnetic field
Strong (very strong!) attractive force on ferromagnetic materials
Projectile effect
Safety: Radiofrequency/Gradients
Heating of conductive materials
Shielded electronicsNo wire loops
Giovannetti et al, Concepts Magn Res B, 2004
Safety: Radiofrequency/Gradients
If possible, move components outside the scanner room
WaveguideScanner Room
Shielded Cable
Console Room
AcquisitionSetup: instrumentationampsNI-DAQ Card
MR Compatibility: artefacts
Assessment of image quality with and without the device under testing
Screw
Arunkumat et al, Diagn Neuroradiol, 1998
ROI 1
ROI 2
SNR, CNR
Standard measurements
Image ArtefactsDefines standard sequences for
determining artifact so the amount ofartifact for different devices can becompared
No acceptance criteria:Depending on region of interest,different amounts of artifact are acceptable
In some cases, artifacts are desirable(biopsy needles, image guided surgery)
MR compatibility
ASTM F2052-06 for Measurement of Magnetically InducedDisplacement Force on Medical Devices in the MR Environment
ASTM F2119-01 for Evaluation of MRImage Artifacts from Passive implants
ASTM F2182-02a for Measurement of Measurement of Radio Frequency Induced Heating Near Passive Implants During MRI
ASTM F2213-06 for Measurement of Magnetically Induced Torqueon Medical Devices in the MR Environment
MR compatibility
No ferromagnetic components
Aluminum, copper, etc…
Magnetic susceptibility close to air/human tissue (plastic polymers, fiberglass, carbon fibers)
Actuators(hydrostatic, piezoelectric, cable transmission)
Sensors(optical fibers)
fMRI actuator
Roger Gassert, Laboratory of Robotic Systems, Losanna
The master actuator: DC torque motor (a), master hydraulic cylinder (b), hydraulic pump (c) and circuitry (d) as well as disconnectable hydrostatic transmission (e) and security switches (f)
The slave module: A) open version showing the slave hydraulic piston (a) and the tactile pad (b). The ultrasonic motor is located beneath the tactile pad. B) The closed module showing the touch-pad (c) and the disconnectable (d) hydrostatic transmission
fMRI actuator (design)
Copper tubeCopper tubeDimensions: outer diameter 35.2mm, inner diameter 32mm, length 1Dimensions: outer diameter 35.2mm, inner diameter 32mm, length 140mm.40mm.Following results regard the copper tube into the bore, fixed orFollowing results regard the copper tube into the bore, fixed or in movement (in movement (zz--transltransl.): we can .): we can note that this experiment does not create significant artefacts note that this experiment does not create significant artefacts in the MR images.in the MR images.
Copper fixed tubeCopper fixed tube
Slice nSlice n°°11
22 55 1010 1515
p SNRp SNR 0.01260.0126 0.8850.885 0.310.31 0.73390.7339 0.5550.555
p SDp SD 0.1080.108 0.0650.065 0.8970.897 0.1590.159 0.8850.885
Copper tube in movement (Copper tube in movement (zz--transltransl.).)
Slice nSlice n°° 11 22 55 1010 1515
p SNRp SNR 0.11440.1144 0.03290.0329 0.9780.978 0.580.58 0.770.77
p SDp SD 0.660.66 0.8030.803 0.8370.837 0.980.98 0.590.59
fMRI actuator (design)
Electromagnetic simulator (GEMS)Electromagnetic simulator (GEMS)
Giovannetti et al, Concepts Magn Res B, 2008
fMRI actuator (testing)
Activation maps
No device Non-compatible device. Compatible device
Scan 1 vs. Scan 2 Scan 1 vs. Scan 39% 60%11% 91%
overlapijRsizeijR
Scan 1 Scan 2 Scan 3
Nicola Vanello, University of Pisa
Conclusions
The lack of harmful effects on the patient and the operator make MR well suited for "interventional radiology", where the images produced by an MRI scanner are used to guide a minimally-invasive procedure intraoperativelyand/or interactively.
Robotic may play a significant role in the field, allowing the use of high performance scanners
Design of compatible MRI mechatronics devices is a challenging task
iMRI represents a transformation from conventional hand-eye-coordination to interactive, navigational operations (Virtual Reality)