Elasticity Imaging

• Mechanical Imaging

• Breast Mechanical Imaging

• Prostate Mechanical Imaging

• Shear Wave Elasticity Imaging

Mechanical Imaging 

Mechanical Imaging (MI), also called “tactile imaging”, “stress imaging”, or “computerized palpation”, 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.

Dr. A. Sarvazyan, Chief Scientific Officer of Artann, started developing Mechanical Imaging technology in the late 80s. In 1992, he filed the first USA patent on MI. Artann has been advancing the MI technology since its inception in 1995. Till now, MI is one of the main areas of research activities of Artann. With the support of numerous NIH SBIR grants, Artann has developed several generations of MI devices for prostate and breast cancer imaging, as disclosed in 11 issued and 5 pending patents.

MI closely mimics manual palpation, since the MI probe with a pressure sensor array mounted on its face acts similar to human fingers during clinical examination, slightly compressing soft tissue by the probe and detecting resulting changes in the pressure pattern. Mechanical properties of tissues, i.e. Young’s modulus and viscosity, are highly sensitive to tissue structural changes accompanying various physiological and pathological processes. A change in Young’s modulus of tissue during the development of a tumor could reach thousands of percent.

References

• Sarvazyan AP: Mechanical imaging: a new technology for medical diagnostics. Int. J. Med. Inf., 1998, 49: 195-216.

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

Breast Mechanical Imaging 

Mechanical Imaging of breast, being developed by A. Sarvazyan since the late 80s, was the first project of Artann, funded by NIH in 1995. Physical basis and general principles and algorithms underlying the breast MI technology were disclosed in the USA patent filed by Sarvazyan in 1992. The Breast Mechanical Imager (BMI) developed under several NIH SBIR grants electronically captures the sense of touch to provide a sensitive, repeatable, quantitative, and permanently stored record of the breast examination. The device includes a probe with a pressure sensor array, an electronic unit, and a laptop computer.

Clinical data collected at four different sites for 187 cases have demonstrated BMI‘s capability for characterizing and differentiating benign and malignant breast lesions. Histologically confirmed malignant breast lesions demonstrated increased hardness and strain hardening as well as decreased mobility in comparison with benign lesions. Statistical analysis of data on 154 benign and 33 malignant lesions revealed BMI’s average sensitivity of 89.4% and specificity of 88.9% with a standard deviation of ±7.8%. The study had indicated BMI potential for a cost effective device for cancer diagnostics that could be positioned as an adjunct to mammography and utilized as a screening device for breast cancer detections. The table below shows a few examples of clinical data obtained by BMI.

Advantages of BMI include inherently low cost, ease-of-use, portability, and minimal training required. Cost analysis of currently used breast screening and diagnostic modalities showed that BMI may be over ten times more cost-effective than mammography.

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 

Prostate Mechanical Imager (PMI) developed in Artann with the support of NIH grants is a new tool for prostate cancer screening allowing for visualization of prostate in terms of its elastic properties. An image of the prostate and its internal structures is generated by the PMI based on the measurement of the mechanical stress patterns on the gland surface through the rectal wall with pressure sensor arrays. PMI provides a real-time 3-D image of the prostate and detects the presence and location of abnormalities within the gland. The PMI enables a physician to visually examine and store a 3-D reconstructed image of the prostate and evaluate prostate volume, elasticity and elasticity contrast.

PMI has been evaluated in a pilot clinical study with 168 patients. Results of this study were published in the journal Urology and this publication has been featured in the Research Highlights section of Nature Clinical Practice Urology.

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. In preparation for the FDA clearance, the PMI technology is currently being validated in a multi-site clinical study.

Examples of prostate examination results obtained by the Mechanical Imager

Publications and Patents

1. Egorov V, Sarvazyan AP: Calibration chamber for prostate mechanical imaging probe. USA Design Patent D609,801 2010.
2. A new 3D imaging technique for prostate examination. Nature Clinical Practice Urology 2008; 5:291-2.
3. 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.
4. 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.
5. Egorov V, Sarvazyan A, Ayrapetyan S: Prostate mechanical imaging: 3-D image composition and feature calculations. IEEE Trans Med Imaging 2006; in press.
6. Sarvazyan A: Model-based imaging. Ultrasound in Med & Biol 2006; 32(11):1712-20.
7. Sarvazyan AP, Egorov V: Real time mechanical imaging of the prostate. USA Patent 6,569,108 2003 May.
8. Weiss R et al: In vitro trial of the pilot prototype of the prostate mechanical imaging system. Urology 2001; 58:1059-63.
9. Sarvazyan AP, Egorov V: Device for palpation and mechanical imaging of the prostate USA Patent 6,142,959 2000 Nov.
10. Sarvazyan AP: Method for using a transrectal probe to mechanically image the prostate gland. US Patent 5,922,018 1999.
11. Sarvazyan AP: Mechanical Imaging: A new technology for medical diagnostics. Int J Med Inf 1998; 49:195-216.
12. Niemczyk P et al: Correlation of mechanical imaging and histopathology of radical prostatectomy specimens: a pilot study. Urology 1998; 160:797-801.
13. Sarvazyan AP: Computerized palpation is more sensitive than human finger. Proc 12th Int Symposium on Biomedical Measurements and Instrumentation 1998; Dubrovnik-Croatia, 523-4.
14. 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.
15. Sarvazyan AP: Method and device for mechanical imaging of prostate. US Patent 5,785,663 1998.
16. Sarvazyan AP: Apparatus for measuring mechanical parameters of the prostate and for imaging the prostate using such parameters. US Patent 5,836,894 1998.
17. Sarvazyan AP: Knowledge-based mechanical imaging of the prostate. Proc MEDTEC’97 1997; Tysons Corner, VA, USA, 87-94.
18. Niemczyk P et al: Mechanical Imaging, a new technology for cancer detection. Surgical Forum 1996; 47:823-5.

Shear Wave Elasticity Imaging 

Shear Wave Elasticity Imaging (SWEI) is a method of tissue elasticity assessment and visualization developed and patented by A. Sarvazyan, Chief Scientific Officer of Artann. 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 speaking, 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.

In SWEI, 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 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 license to SWEI and patents in this field is 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.