Elasticity Imaging

• Mechanical Imaging

• Breast Mechanical Imaging

• Prostate Mechanical Imaging

• Shear Wave Elasticity Imaging

Mechanical Imaging 

Mechanical Imaging (MI) is a new modality of medical diagnostics that is based on visualizing the sense of touch. In MI, the internal structures of an organ are visualized by measuring the pattern of mechanical stresses on its surface without using any form of radiation [1-3]. The MI device uses an array of pressure sensors and a position sensor mounted on a probe connected to a computer that carries out data processing necessary to obtain and display 2D and 3D images of tissue elasticity.

The most promising applications of MI devices are in those fields of medicine where palpation is proven to be a sensitive tool in detecting and monitoring diseases, such as cancer. Using proprietary algorithms, the MI devices can assess tissue hardness, one of the key characteristics of cancerous lesions, with the sensitivity higher then manual palpation.

Artann has been advancing the MI technology since its inception in 1995, when Artann received its first NIH SBIR grant “New screening method for early detection of breast cancer”. Mechanical Imaging is one of the main areas of research activities of Artann. Development of MI devices for breast and prostate cancer detection was supported by private investment and several SBIR grants from the National Cancer Institute. 

References

1. Sarvazyan A: Model-based imaging. Ultrasound in Med & Biol 2006; 32(11):1712-20.
2. Sarvazyan AP: Mechanical imaging: a new technology for medical diagnostics. Int. J. Med. Inf., 1998, 49: 195-216.

3. Sarvazyan AP, Skovoroda AR: Method and apparatus for elasticity imaging. US Patent 5,524,636 1996.

Breast Mechanical Imaging 

Development of a hand-held Breast Mechanical Imager capable of detecting breast lesions objectively and more sensitively than by manual palpation is currently under way with the support of the Phase II SBIR grant from the National Cancer Institute. An ultimate goal of the project is development of a home-use self-palpation device which will provide a virtual interface between patient and physician for remote screening for breast cancer through detection of changes in mechanical properties of the breast tissue. Data collected on a regular basis will be sent via the Internet to the central database and will be analyzed by a computer and a physician. Monitoring of breast tissue elasticity changes in time will enable the development of an “individual norm” for each patient. The deviation from this individual norm could be indicative on an emerging pathology. Development of the low cost home use device in conjunction with advanced image enhancement algorithms and Internet based data transfer for physician review will create a cost-effective framework for mass population screening.

Publications and Patents

1. Egorov V, Sarvazyan AP: Mechanical Imaging of the Breast. IEEE Transactions on Medical Imaging 2008; 27(9):1275-87.
2. Sarvazyan A, Egorov V, Son JS, Kaufman CS: Cost-effective screening for breast cancer worldwide: current state and future directions. Breast Cancer: Basic and Clinical Research 2008; 1:91–9.
3. Sarvazyan AP, Egorov V: Self-palpation device for examination of breast with 3-D positioning system. US Patent 6,595,933 2003.
4. Sarvazyan AP, Egorov V: Apparatus and method for mechanical imaging of breast. US Patent 6,620,115 2003.
5. Sarvazyan AP, Egorov V: Self-palpation device for examination of breast. US Patent 6,468,231 2002.
6. Sarvazyan AP: Method and device for mechanical imaging of breast. US Patent No 5,860,934 1999.
7. Sarvazyan AP: Device for breast haptic examination. US Patent 5,833,633 1998.
8. Sarvazyan AP: Mechanical Imaging: A new technology for medical diagnostics. Int J Med Inf 1998; 49:195-216.
9. Pashko DA, Pyt’ev YP, Sarvazyan AP, Skovoroda AR: On the ultimate potentialities of classification of pathologies in the problem of diagnostics of breast cancer. Pattern Recognition and Image Analysis, 6, 1996, 510-522.
10. Pashko DA, Pyt’ev YP, Sarvazyan AP: Minimax evaluation of parameters of a nodule in diagnosing breast cancer with the use of a force sensor array. Bulletin of Moscow State University 1996; Ser 3 Physics Astronomy:18-25.

Prostate Mechanical Imaging 

The Prostate Mechanical Imager is a portable cost-effective device for prostate cancer detection mimicking digital rectal examination. The device may allow every general practitioner to examine the prostate and identify abnormalities not only with the accuracy of an experienced urologist but also more sensitively, reliably, objectively, quantitatively and with a permanent record. The device will be used in clinical practice for both diagnostic and screening purposes in evaluating patients for prostate cancer.
Artann is working with the ProUroCare Medical, Inc., a Minnesota based company, on development of the ProUroScan™, a first commercial device for the prostate cancer detection built on the principles of the Mechanical Imaging technology. The ProUroScan™ is an imaging device designed to standardize the documentation of the size and shape of the prostate as well as to detect the presence and hardness of nodules within the prostate. The ProUroScan™ uses pressure sensor arrays and a 3-D positioning sensor mounted in the transrectal probe to measure temporal and spatial variations in the surface stress patterns in compressed tissue. To date the Prostate Mechanical Imager with 3-D reconstruction capability was validated in extensive laboratory experiments and tested in preliminary clinical studies.

Examples of prostate examination results obtained by the Mechanical Imager

Publications and Patents

1. A new 3D imaging technique for prostate examination. Nature Clinical Practice Urology 2008; 5:291-2.
2. Weiss R, Egorov V, Ayrapetyan S, Sarvazyan N, Sarvazyan A: Prostate mechanical imaging: a new method for prostate assessment. Urology 2008 Mar; 71(3):425-9.
3. Egorov V, Ayrapetyan S, Sarvazyan A: Prostate mechanical imaging: 3-d image composition and feature calculations. IEEE Transactions on Medical Imaging 2006; 25(10):1329-40.
4. Egorov V, Sarvazyan A, Ayrapetyan S: Prostate mechanical imaging: 3-D image composition and feature calculations. IEEE Trans Med Imaging 2006; in press.
5. Sarvazyan A: Model-based imaging. Ultrasound in Med & Biol 2006; 32(11):1712-20.
6. Sarvazyan AP, Egorov V: Real time mechanical imaging of the prostate. USA Patent 6,569,108 2003 May.
7. Weiss R, Hartanto V, Perrotti M, Cummings K, Bykanov A, Egorov V, Sobolevsky S: In vitro trial of the pilot prototype of the prostate mechanical imaging system. Urology 2001; 58:1059-63.
8. Sarvazyan AP, Egorov V: Device for palpation and mechanical imaging of the prostate USA Patent 6,142,959 2000 Nov.
9. Sarvazyan AP: Method for using a transrectal probe to mechanically image the prostate gland. US Patent 5,922,018 1999.
10. Sarvazyan AP: Mechanical Imaging: A new technology for medical diagnostics. Int J Med Inf 1998; 49:195-216.
11. Niemczyk P, Cummings KB, Sarvazyan AP, Bancilla E, Ward WS, Weiss RE: Correlation of mechanical imaging and histopathology of radical prostatectomy specimens: a pilot study. Urology 1998; 160:797-801.
12. Sarvazyan AP: Computerized palpation is more sensitive than human finger. Proc 12th Int Symposium on Biomedical Measurements and Instrumentation 1998; Dubrovnik-Croatia, 523-4.
13. Sarvazyan AP, Spector AA: Computerized palpation of the prostate: experimental and mathematical modeling of the stress-strain fields. Proc IEEE Symposium on Computer-Based Medical Systems 1998; Lubbock, Texas, 110-12.
14. Sarvazyan AP: Method and device for mechanical imaging of prostate. US Patent 5,785,663 1998.
15. Sarvazyan AP: Apparatus for measuring mechanical parameters of the prostate and for imaging the prostate using such parameters. US Patent 5,836,894 1998.
16. Sarvazyan AP: Knowledge-based mechanical imaging of the prostate. Proc MEDTEC’97 1997; Tysons Corner, VA, USA, 87-94.
17. Niemczyk P, Sarvazyan AP, Fila A, Amenta P, Ward WS, Javidian P, Breslauer K, Cummings KB: Mechanical Imaging, a new technology for cancer detection. Surgical Forum 1996; 47:823-5.

Shear Wave Elasticity Imaging 

Shear Wave Elasticity Imaging (SWEI) is another method of tissue elasticity assessment and visualization developed by A. Sarvazyan and associates. Core patents on SWEI filed by Sarvazyan are assigned to Artann Laboratories [1,2].  In SWEI, the radiation force of focused ultrasound remotely induces localized shear waves, which are visualized by ultrasonic or MRI methods in order to assess tissue elasticity.  Generally, SWEI is a branch of both the Ultrasonic Elasticity Imaging (UEI) and Magnetic Resonance Elastography (MRE) - the rapidly maturing areas in the biomedical engineering. Development of SWEI was started in the original studies of A.. Sarvazyan in the Russian Academy of Sciences. Later, SWEI was studied in collaboration with the researchers at the University of Michigan [3-6]. UEI has already established a distinct niche among other methods of medical imaging and was successfully used to visualize various organs or lesions in organs including liver, prostate gland, breast, coronary arteries, etc.  SWEI expands the fields of application of UEI as well as MRE by allowing characterization and imaging of such tissues as brain, which cannot be deformed or stressed by an outside vibrator. 

SWEI relies on Radiation Force of the focused ultrasound which produces a remote mechanical excitation in a small region.  Acoustic radiation force is an example of a universal wave-based phenomenon that introduces unidirectional force on the absorbing or reflecting targets in the wave path. Radiation force is produced by a change in the ultrasonic wave energy density of an incident acoustic field.  Radiation force exerted by a focused ultrasonic beam acts as a virtual finger remotely probing the elasticity of tissue.  Analytical equations describing the spatial and temporal behavior of the radiation force induced shear displacement and waves in tissue-like media have been derived [7,8]. SWEI with MRI detection of the radiation force induced shear waves has been first realized in the NIH funded collaborative research project between Artann and the University of Michigan.  SWEI with Doppler ultrasound detection of radiation force induced shear waves has been realized in another NIH funded research project conducted in Artann in collaboration with the University of Paris and Kharkov State University, Ukraine [9,10].

A limited license to SWEI and Artann’s patents in this field was granted to Supersonic Imagine.

Publications and Patents

1. Sarvazyan AP: Method and device for shear wave elasticity imaging. US Patent 5,606,971 1997.
2. Sarvazyan AP, Rudenko OV: Method and apparatus for elasticity imaging using remotely induced shear wave. US Patent 5,810,731 1998.
3. Sarvazyan AP, Rudenko OV, Swanson SD, Fowlkes JB, Emelianov SY: Shear wave elasticity imaging -- A new ultrasonic technology of medical diagnostics. Ultrasound Med Biol 1998; 24:1419-35.
4. Sarvazyan AP, Skovoroda AR, Emelianov SY, Fowlkes JB, Pipe JG, Adler RS, Buxton RB, Carson PL: Biophysical bases of elasticity imaging. Acoustical Imaging 1995; 21(ed Jones JP, Plenum Press, New York and London), 223-40.
5. Fowlkes JB, Emelianov SY, Pipe JG, Carson PL, Adler RS, Sarvazyan AP, Skovoroda AR: Possibility of cancer detection through measurement of elasticity properties. Radiology 1992; 185:123-4.
6. Fowlkes JB, Emelianov SY, Pipe JG, Skovoroda AR, Adler RS, Carson PL, Sarvazyan AP: Magnetic resonance imaging techniques for detection of elasticity variation. Med Phys 1995; 22:1771-8.
7. Rudenko OV, Sarvazyan AP, Emelianov SY: Acoustic radiation force and streaming induced by focused nonlinear ultrasound in a dissipative medium. J Acoust Soc Am 1996; 99:2791-98.
8. Ostrovsky L, Sutin A, Il’inskii Y, Rudenko O, Sarvazyan A: Radiation force and shear motions in inhomogeneous media. J Acoust Soc Am 2007; 121(3):1324-31.
9. Barannik EA, Girnyk A, Tovstiak V, Marusenko AI, Emelianov SY, Sarvazyan AP: Doppler ultrasound detection of shear waves remotely induced in tissue phantoms and tissue in vitro. Ultrasonics 2002; 40:849-52.
10. Barannik EA, Girnyk A, Tovstiak V, Marusenko AI, Volokhov VA, Sarvazyan AP, Emelianov SY: The influence of viscosity on the shear strain remotely induced by focused ultrasound in viscoelastic media. J Acoust Soc Am 2004; 115(5):2358-64.