Magnetic resonance elastography is a noninvasive technique to measure the elastic properties of tissues using MRI. It involves vibrating the tissue with an external actuator and using motion encoding gradients on a modified gradient echo MRI sequence to visualize the propagating shear waves. Software then analyzes the wave propagation patterns in the phase images to reconstruct quantitative elasticity maps in kilopascals. The author designed and tested a vibration actuator and modified a gradient echo sequence for a gel phantom study. Results showed the elasticity values measured with MRE agreed with literature values and distinguished between softer and stiffer gel regions as expected.
Magnetic Resonance Elastography is an advanced imaging technique in MRI. This method is a method of "virtual palpation" of internal organs with the help of MRI.
Physicians have used palpation to detect differences in tissue stiffness as an aid to diagnosis based on the fact that the mechanical properties of tissues are often dramatically affected by the presence of disease processes such as cancer, inflammation, and fibrosis. Elastography depends on the same differences in mechanical properties between healthy and abnormal tissues using imaging to detect these differences at depths not reachable by manual palpation and presents data in color-coded display, can be performed with ultrasound, using manual pressure or low frequency sonic waves, or by MR Elastography imaging.
Ultrasound elastography is a relatively advanced technique used to know the stiffness of the tissue. It is a non-invasive technique. Broadly classified into Quasistatic and Dynamic elastography.
Magnetic Resonance Elastography is an advanced imaging technique in MRI. This method is a method of "virtual palpation" of internal organs with the help of MRI.
Physicians have used palpation to detect differences in tissue stiffness as an aid to diagnosis based on the fact that the mechanical properties of tissues are often dramatically affected by the presence of disease processes such as cancer, inflammation, and fibrosis. Elastography depends on the same differences in mechanical properties between healthy and abnormal tissues using imaging to detect these differences at depths not reachable by manual palpation and presents data in color-coded display, can be performed with ultrasound, using manual pressure or low frequency sonic waves, or by MR Elastography imaging.
Ultrasound elastography is a relatively advanced technique used to know the stiffness of the tissue. It is a non-invasive technique. Broadly classified into Quasistatic and Dynamic elastography.
Mammograhy is a radiological modality to examine the breast tissue.
The new technology is gradually replacing the conventional mammography by Digital Breast Tomosynthesis. Tomosynthesis or “3D” mammography is a new type of digital x-ray mammogram which
creates 2D and 3D-like pictures of the breasts.
During a “3D” exam, an X-ray arm sweeps in a slight arc over your breast, taking multiple
low dose x-ray images.
Then, a computer produces synthetic 2D and “3D” images of your breast tissue.
The images include thin one millimeter slices, enabling the radiologist to scroll through
images of the entire breast.
We can always opt for other modalities to rule out diagnosis, like Ultrasound in case of breast. But there is always some pros and cons for a particular investigation.
Mammography is a gold standard investigation for breast over 40 years of age. As there is some limitation of age in mammography, due to the biological effects of radiation.
As we know breasts are one of the radiosensitive organ and USG uses sound waves which is harmless to human body so below the age of 40 years doctors recommed to go for USG first to rule out any type of pathology.
Mammography uses low kvp and high mAs thats why the dose in ammography is significantly low.
Everything regarding the physics of MRA is given along with flow charts and images. Also have covered new advances and refrences taken from MR made easy and some articles related to MRI
Mammography : quality control (quality assurance)Kajal Jha
Mammography quality control. This is the class presentation for the syllabus of BSC MIT at BPKIHS Dharan. It is the concise ppt dealing with the quality control of mammography and hence quality control. Mammography is an x-ray imaging
method used to examine the breast for the early detection of cancer and other breast diseases. It is used as both a diagnostic and screening tool.
- also known as Mastography
Introduction to mammography and its equipment.
Different views on mammography & supplementary views.
Birads mammographic lexicon
Birads ultrasound lexicon
Imaging of suspicious mammary lymph nodes
Categories in BIRADS 2013.
presentation on ultrasound elastography-introduction ,techniques,physics,application, interpretation and future prospects.sourced from multiple articles.
One test can save your life. Know what a CT Scan Enterography is, why you should have it, who should get it, and where can you get tested as well as get your results fast. If you want to read more about CT Scan Enterography, just click the link below.
Visit: https://www.labfinder.com/labexams/ct-scan-enterography/ and get tested now!
Qualitative analysis of Fruits and Vegetables using Earth’s Field Nuclear Mag...IJERA Editor
Among the imaging techniques, magnetic resonance imaging (MRI) is a non-contact and a non-invasive technique to obtain images of the objects rich in water content and provides an excellent tool to study variation of contrast among the soft issues. It often utilizes a linear magnetic field gradient to obtain an image that combines the visualization of molecular structure and dynamics. It measures the characteristics of hydrogen nuclei of water and nuclei with similar chemical shifts, modified by chemical environment across the object. In the present work, MRI of fresh tomatoes has been recorded using Terranova-MRI for qualitative analysis. The technique is effective, powerful and reliable as an investigative tool in the quality analysis and diagnosis of infections in fruits and vegetables.
A Novel Displacement-amplifying Compliant Mechanism Implemented on a Modified...IJECEIAES
The micro-accelerometers are devices used to measure acceleration. They are implemented in applications such as tilt-control in spacecraft, inertial navigation, oil exploration, etc. These applications require high operating frequency and displacement sensitivity. But getting both high parameter values at the same time is difficult, because there are physical relationships, for each one, where the mass is involved. When the mass is reduced, the operating frequency is high, but the displacement sensitivity decreases and vice versa. The implementation of Displacement-amplifying Compliant Mechanism (DaCM) supports to this dependence decreases. In this paper the displacement sensitivity and operation frequency of a Conventional Capacitive Accelerometer are shown (CCA). A Capacitive Accelerometer with Extended Beams (CAEB) is also presented, which improves displacement sensitivity compared with CCA, and finally the implementation of DACM´s in the aforementioned devices was also carried out. All analyzed cases were developed considering the in-plane mode. The Matlab code used to calculate displacement sensitivity and operating frequency relationship is given in Appendix A.
Mammograhy is a radiological modality to examine the breast tissue.
The new technology is gradually replacing the conventional mammography by Digital Breast Tomosynthesis. Tomosynthesis or “3D” mammography is a new type of digital x-ray mammogram which
creates 2D and 3D-like pictures of the breasts.
During a “3D” exam, an X-ray arm sweeps in a slight arc over your breast, taking multiple
low dose x-ray images.
Then, a computer produces synthetic 2D and “3D” images of your breast tissue.
The images include thin one millimeter slices, enabling the radiologist to scroll through
images of the entire breast.
We can always opt for other modalities to rule out diagnosis, like Ultrasound in case of breast. But there is always some pros and cons for a particular investigation.
Mammography is a gold standard investigation for breast over 40 years of age. As there is some limitation of age in mammography, due to the biological effects of radiation.
As we know breasts are one of the radiosensitive organ and USG uses sound waves which is harmless to human body so below the age of 40 years doctors recommed to go for USG first to rule out any type of pathology.
Mammography uses low kvp and high mAs thats why the dose in ammography is significantly low.
Everything regarding the physics of MRA is given along with flow charts and images. Also have covered new advances and refrences taken from MR made easy and some articles related to MRI
Mammography : quality control (quality assurance)Kajal Jha
Mammography quality control. This is the class presentation for the syllabus of BSC MIT at BPKIHS Dharan. It is the concise ppt dealing with the quality control of mammography and hence quality control. Mammography is an x-ray imaging
method used to examine the breast for the early detection of cancer and other breast diseases. It is used as both a diagnostic and screening tool.
- also known as Mastography
Introduction to mammography and its equipment.
Different views on mammography & supplementary views.
Birads mammographic lexicon
Birads ultrasound lexicon
Imaging of suspicious mammary lymph nodes
Categories in BIRADS 2013.
presentation on ultrasound elastography-introduction ,techniques,physics,application, interpretation and future prospects.sourced from multiple articles.
One test can save your life. Know what a CT Scan Enterography is, why you should have it, who should get it, and where can you get tested as well as get your results fast. If you want to read more about CT Scan Enterography, just click the link below.
Visit: https://www.labfinder.com/labexams/ct-scan-enterography/ and get tested now!
Qualitative analysis of Fruits and Vegetables using Earth’s Field Nuclear Mag...IJERA Editor
Among the imaging techniques, magnetic resonance imaging (MRI) is a non-contact and a non-invasive technique to obtain images of the objects rich in water content and provides an excellent tool to study variation of contrast among the soft issues. It often utilizes a linear magnetic field gradient to obtain an image that combines the visualization of molecular structure and dynamics. It measures the characteristics of hydrogen nuclei of water and nuclei with similar chemical shifts, modified by chemical environment across the object. In the present work, MRI of fresh tomatoes has been recorded using Terranova-MRI for qualitative analysis. The technique is effective, powerful and reliable as an investigative tool in the quality analysis and diagnosis of infections in fruits and vegetables.
A Novel Displacement-amplifying Compliant Mechanism Implemented on a Modified...IJECEIAES
The micro-accelerometers are devices used to measure acceleration. They are implemented in applications such as tilt-control in spacecraft, inertial navigation, oil exploration, etc. These applications require high operating frequency and displacement sensitivity. But getting both high parameter values at the same time is difficult, because there are physical relationships, for each one, where the mass is involved. When the mass is reduced, the operating frequency is high, but the displacement sensitivity decreases and vice versa. The implementation of Displacement-amplifying Compliant Mechanism (DaCM) supports to this dependence decreases. In this paper the displacement sensitivity and operation frequency of a Conventional Capacitive Accelerometer are shown (CCA). A Capacitive Accelerometer with Extended Beams (CAEB) is also presented, which improves displacement sensitivity compared with CCA, and finally the implementation of DACM´s in the aforementioned devices was also carried out. All analyzed cases were developed considering the in-plane mode. The Matlab code used to calculate displacement sensitivity and operating frequency relationship is given in Appendix A.
Applications of Artificial Neural Network and Wavelet Transform For Conditio...IJMER
The vibration analysis of rotating machinery indicates of the condition of potential faults such
as unbalance, bent shaft, shaft crack, bearing clearance, rotor rub, misalignment, looseness, oil whirl
and whip and other malfunctions. More than one fault can occur in a rotor. This paper describes the
application of Artificial Neural Network (ANN) and Wavelet Transform (WT) for the prediction of the
effect of the combined faults of unbalance and bearing clearance on the frequency components of
vibration signature of the rotating machinery. The experimental data of frequency components and
corresponding Root Mean Square (RMS) velocity (amplitude) data are used as inputs to train the ANN,
which consists of a three-layered network. The ANN is trained using an improved multilayer feed forward
back propagation Levenberg-Marquardt algorithm. In particular, an overall success rates achieved were
99.78% for unbalance, 99.81% bearing clearance, and 99.45% for the combined faults of unbalance and
bearing clearance. The wavelet transform approach enables instant to instant observation of different
frequency components over the full spectrum. A new technique combining the WT with ANN performs
three general tasks data acquisition, feature extraction and fault identification. This method is tested
successfully for individual and combined faults of unbalance and bearing clearance at a success rate of
99.99%.
INVERSIONOF MAGNETIC ANOMALIES DUE TO 2-D CYLINDRICAL STRUCTURES –BY AN ARTIF...ijsc
Application of Artificial Neural Network Committee Machine (ANNCM) for the inversion of magnetic
anomalies caused by a long-2D horizontal circular cylinder is presented. Although, the subsurface targets
are of arbitrary shape, they are assumed to be regular geometrical shape for convenience of mathematical
analysis. ANNCM inversion extract the parameters of the causative subsurface targets include depth to the
centre of the cylinder (Z), the inclination of magnetic vector(Ɵ)and the constant term (A)comprising the
radius(R)and the intensity of the magnetic field(I). The method of inversion is demonstrated over a
theoretical model with and without random noise in order to study the effect of noise on the technique and
then extended to real field data. It is noted that the method under discussion ensures fairly accurate results
even in the presence of noise. ANNCM analysis of vertical magnetic anomaly near Karimnagar, Telangana,
India, has shown satisfactory results in comparison with other inversion techniques that are in vogue.The
statistics of the predicted parameters relative to the measured data, show lower sum error (<9.58%) and
higher correlation coefficient (R>91%) indicating that good matching and correlation is achieved between
the measured and predicted parameters.
INVERSIONOF MAGNETIC ANOMALIES DUE TO 2-D CYLINDRICAL STRUCTURES –BY AN ARTIF...ijsc
Application of Artificial Neural Network Committee Machine (ANNCM) for the inversion of magnetic
anomalies caused by a long-2D horizontal circular cylinder is presented. Although, the subsurface targets
are of arbitrary shape, they are assumed to be regular geometrical shape for convenience of mathematical
analysis. ANNCM inversion extract the parameters of the causative subsurface targets include depth to the
centre of the cylinder (Z), the inclination of magnetic vector(Ɵ)and the constant term (A)comprising the
radius(R)and the intensity of the magnetic field(I). The method of inversion is demonstrated over a
theoretical model with and without random noise in order to study the effect of noise on the technique and
then extended to real field data. It is noted that the method under discussion ensures fairly accurate results
even in the presence of noise. ANNCM analysis of vertical magnetic anomaly near Karimnagar, Telangana,
India, has shown satisfactory results in comparison with other inversion techniques that are in vogue.The
statistics of the predicted parameters relative to the measured data, show lower sum error (<9.58%) and
higher correlation coefficient (R>91%) indicating that good matching and correlation is achieved between
the measured and predicted parameters.
Inversion of Magnetic Anomalies Due to 2-D Cylindrical Structures – By an Art...ijsc
Application of Artificial Neural Network Committee Machine (ANNCM) for the inversion of magnetic anomalies caused by a long-2D horizontal circular cylinder is presented. Although, the subsurface targets are of arbitrary shape, they are assumed to be regular geometrical shape for convenience of mathematical analysis. ANNCM inversion extract the parameters of the causative subsurface targets include depth to the centre of the cylinder (Z), the inclination of magnetic vector(Ɵ)and the constant term (A)comprising the radius(R)and the intensity of the magnetic field(I). The method of inversion is demonstrated over a theoretical model with and without random noise in order to study the effect of noise on the technique and then extended to real field data. It is noted that the method under discussion ensures fairly accurate results even in the presence of noise. ANNCM analysis of vertical magnetic anomaly near Karimnagar, Telangana, India, has shown satisfactory results in comparison with other inversion techniques that are in vogue.The statistics of the predicted parameters relative to the measured data, show lower sum error (<9.58%) and higher correlation coefficient (R>91%) indicating that good matching and correlation is achieved between the measured and predicted parameters.
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Vibration Analysis and Modelling of a Cantilever Beam Muhammad Usman
This report in cooperates the techniques, adopted for the evaluation of vibration analysis of a cantilever beam using both techniques i.e. theoretical as well as the practical ones. Computer based analysis of a beam were also performed using Solid Works and Mat Lab software. These techniques helped a lot in finding the natural frequencies and in making the vibrational characteristic behavior of a cantilever beam thus steel used as a material.
2. 2
Outline
• Elasticity.
• Magnetic Resonance elastography (MRE).
• Vibration Actuator.
• Modification of Gradient-recalled echoes (GRE)
Sequence.
• Reconstruction Software.
• Agar Gel Phantom.
• Equipment and Experimental setup.
• Results.
• Conclusion Challenges and Future Plans.
3. 3
Elasticity
• Elasticity is the Physical Property of material.
• Hooke’s law described the basic property of elasticity
of a spring as: F = kx. Where x is the stretch of spring
and k is spring constant.
• Consider cube instead of spring then we have four
elastic constants:
• E = Young’s Modulus
• G = Shear Modulus.
• K = Bulk Modulus
• σ = Poisson’s ratio
4. 4
Elasticity: Relationship between the
Young’s modulus and the normal strain.
(Source: Magnetic Resonance Elastography : in vivo Measurements of Elasticity for Human Tissue
Takenori OIDA, Akira AMANO and Tetsuya MATSUDA)
5. 5
Elasticity: Relationship between
the shear modulus and the shear strain.
(Source: Magnetic Resonance Elastography : in vivo Measurements of Elasticity for Human Tissue
Takenori OIDA, Akira AMANO and Tetsuya MATSUDA)
6. 6
Elasticity: Bulk modulus K and the
Poisson’s ratio σ
EG
EG
K
39
• Bulk Modulus measures the substances resistance to
uniform compression
• Poisson’s ratio is the ratio of the stretching of a material
in one direction to the contraction of the material in the
other direction.
• Measuring E and G in case of MRE, the K and σ can
be calculated from these formulas:
G
GE
2
2
7. 7
Magnetic Resonance Elastography
• Physicians routinely use palpation to detect
the elastic properties of tissues.
• Differences in elasticity can help facilitate the
diagnosis of tumors.
• Difficult to obtain such properties in vivo by
using conventional methods.
• MRE has been developed that provides
noninvasive in vivo measurement of elasticity
for Human tissue.
8. 8
MRE: Method
• MRE is a method which calculates Elastic
modulus by measuring the waves caused by
oscillating the material externally.
• Wavelength of the propagating waves can be
easily acquired from MRI phase Images.
• In hard material waves travel fast and have longer
wavelength compare to soft materials where
waves travel slow and have shorter wavelength.
9. 9
MRE: Theory
• Mostly actuators produce
transverse waves and shear
modulus can be calculated
using equations below:
• Young's modulus can be
calculated with the application
of longitudinal waves
2
G f
(Images Source: Yin M, Rouvière O, Glaser KJ, Ehman RL. Diffraction-biased shear wave fields generated
with longitudinal magnetic resonance elastography drivers. Magn Reson Imag. 26(6):770-80, Jul. 2008.)
10. 10
MRE: Required components
• Hardware device to oscillate the
scanned region at known frequency
called actuator.
• MRI Pulse sequence with motion
encoding gradients to encode motion.
• Software to estimate the Wavelength
from the acquired Phase images and
reconstruct elasticity map.
13. 13
MRE: GRE Pulse Sequence
( Source: Thesis, Magnetic Resonance Elastography at 3 Tesla: Implementation, Validation and Application to
a degenerative Disc Model by Timothy Christian Dunn. 1995)
14. 14
MRE: Elasticity Estimation
Mathematical techniques are used to convert the phase difference
image into elasticity map.
Figure 1:Magnitude Image Figure 2: Phase Difference Image
Figure 3: Interpolated Wave Propagation Figure 4:Stiffness map
(Source: http://mayoresearch.mayo.edu/ehman_lab/mrw-wave.cfm)
20. 20
Modified GRE Sequence
• Siemens GRE sequence is modified using
Siemens Integrated Development
Environment for Applications (IDEA).
• Create parameters in the sequence special
card related to MRE.
• Programmed bipolar motion encoding
gradients (MEGs) in the sequence. MEGs
can be applied in any one of the three axis.
24. 24
Reconstruction Software
• Use the free software available on Mayo Clinic
Website Called MRE/Wave. Link is
http://mayoresearch.mayo.edu/ehman_lab/mrw
-wave.cfm
• This software use Local Frequency Estimation
(LFE) algorithm to reconstruct elasticity maps
from phase data.
• LFE uses the output of different filters to
calculate the local spatial frequency of the
shear wave propagation.
25. 25
Local frequency estimation (LFE)
(a) Test image with two regions of 4 and 8 cycles per image. (b) Local frequency estimate for Test Image.
Source: (Manduca, A., Muthupillai, R., Rossman, P.J., Greenleaf, J.F. and Ehman, R.L., 1996.
Image processing for magnetic resonance elastography. SPIE Med Img 2710, 616-623)
(Vertical Profile)
28. 28
Experimental procedure
• Sequence Parameters selected:
TR = 120ms / TE = 31.3ms
No of slices = 1, Slice thickness = 5mm
FOV = 20cm X 20cm, Resolution = 256 X 256.
Spine coil Coil used was and no filters selected.
• MRE parameters:
Frequency = 250 Hz and 125 Hz,
MEG amplitude 10mT/m,MEG Cycles = 4
and pre-MEG STIM = 2.
RO MEG ON and other two axes off.
29. 29
Results: Phase difference Images at 250 Hz
(Image at 0 degree phase delay) (Image at 45 degree phase delay)
(Image at 90 degree phase delay) (Image at 135 degree phase delay)
1% Gel Cylinder
3% Gel Cylinder
30. 30
Results: Wave Propagation and Elasticity
map at 250Hz
(Wave propagation. Scale bar is in µm (micron)) (Elasticity Map. Scale bar is in kilopascals( KPa))
1% Gel Cylinder 3% Gel Cylinder1% Gel Cylinder 3% Gel Cylinder
31. 31
Results: Phase Difference Images at 125 Hz
(Image at 0 degree phase delay) (Image at 45 degree phase delay)
(Image at 90 degree phase delay) (Image at 135 degree phase delay)
1% Gel Cylinder
3% Gel Cylinder
32. 32
Results: Wave Propagation and Elasticity
map at 125Hz
(Wave propagation. Scale bar is in µm (micron)) (Elasticity Map. Scale bar is in kilopascals( KPa))
1% Gel Cylinder 3% Gel Cylinder1% Gel Cylinder 3% Gel Cylinder
34. 34
Conclusion
• Elasticity values measured are comparable to the
values available in literature.
• Electromagnetic coil has a tendency to produce
artifacts.
• Phantom boundary seems to be less elastic
because of air and water on the sides.
• Assumption of local homogeneity in reconstruction
creates inaccurate results near boundaries and
place limit on resolution.
35. 35
Challenges
• Spatial resolution of MRE can be improved by
increasing the frequency, however the high
frequency waves will be attenuated more
rapidly compared to lower frequency waves.
• Sample size needs to accommodate half a
shear wave in the MRE image in order to
measure the stiffness.
• Water and air exists between layers in
phantom damped and distorted the waves.
36. 36
Future Plans: Actuator
• Size of actuator.
• Weight of coil.
• Pivot point needs better design.
• Vertically adjustable actuator
head.
• Other types of actuators.
37. 37
Future Plans: Sequence
• Eight different phase offsets in
one motion cycle.
• Modification of Image calculation
part of the sequence.
• Programming of other sequences
like SE for MRE.
38. 38
Future Plans: Reconstruction
Software
• Development of reconstruction
software.
• Use other algorithms like Algebraic
Inversion of the differential equation
or Overlapping subzone technique.
• Addition of new filtering techniques.
39. 39
Remote Vibration Generator
(Ingolf Sack, Bernd Beierbach, Uwe Hamhaber, Dieter Klatt and Jurgen Braun. Non-invasive measurement of brain
viscoelasticity using magnetic resonance elastography. NMR Biomed. 2008 Mar; 21(3):265-71)
40. 40
Coil Actuator
(Takenori Oida, Akira Amano and Tetsuya Matsuda. Magnetic Resonance Elastography: in vivo Measurements
of Elasticity for Human Tissue. Proceedings of the 12th International Conference on Informatics Research for
Development of Knowledge Society Infrastructure (ICKS’04) 0-7695-2150-9/04, 2004 IEEE.)
42. 42
MRE Parameters
Image Number Motion Encoding Gradient MEG PHASE MEG Delay
1 RO MEG ON Pos 0
2 RO MEG ON Neg 0
3 RO MEG ON Pos 45
4 RO MEG ON Neg 45
5 RO MEG ON Pos 90
6 RO MEG ON Neg 90
7 RO MEG ON Pos 135
8 RO MEG ON Neg 135
43. 43
MRE SE Pulse Sequence
(Thesis : Magnetic Resonance Elastography at 3 Tesla: Implementation, Validation and Application to
a degenerative Disc Model by Timothy Christian Dunn. 1995)
44. 44
Wave Image and shear stiffness Map
in four hepatic fibrosis patients
(Meng Yin, PhD, Jun Chen, PhD, Kevin J. Glaser, PhD, Jayant A. Talwalkar, MD, and Richard L. Ehman, MD.
Abdominal Magnetic Resonance Elastography. Top Magn Reson Imaging. 2009 Apr; 20(2):79-87.
45. 45
Coil in Main Magnetic Field
Direction of Main Magnetic field