Ehsan Samei, Professor of Radiology and Physics  

Ehsan Samei

Office Location: 2424 Erwin Road, Suite 302
Email Address: samei@duke.edu
Web Page: http://www.duke.edu/~samei

Specialties:
Biological physics

Education:
Ph.D., University of Michigan, 1997
M.E., University of Michigan, 1995

Research Categories: Medical Physics

Research Description: Dr. Samei’s research interests include theoretical and experimental methods in medical image formation, analysis, display, and perception, with particular emphasis on factors, methods, and procedures that impede and improve the radiological detection and diagnosis of early cancer. More specifically, his research in recent years has focused on the four areas discussed below. 1. Correlation and stereo imaging for improved early detection of cancer The early detection of lung cancer has been one of the outstanding challenges in radiographic imaging, the significance of which can be discerned only by considering the fact that lung cancer remains the leading cause of cancer death in the US, surpassing breast, prostate, colon, and cervical cancers combined. His prior research has shown that interference of the anatomical structure is the dominant factor in the low detection of early lung cancer in radiographic images. Grounded on this basic understanding, Correlation Imaging (CI) aims to develop a more sensitive image acquisition and processing approach that minimizes this influence, and therefore improves the early detection of lung cancer. The NIH awarded Dr. Samei R21 and R01 grants to study the feasibility of this imaging approach. With that funding, chest correlation and stereo imaging was developed from an initial design into a state-of-the-art prototype imaging system (fully developed and integrated at Duke). The prototype equipment is now being used in a clinical trial to assess the clinical utility of this novel imaging technique. As of now, more than 80 patients have been imaged, and the preliminary findings are very encouraging. Furthermore, Dr. Samei significantly contributed to and served as a key investigator on an R01 grant aimed to develop a cone beam CT imaging system (PI: Martin Tornai, PhD) and tomosynthesis (PI: Joseph Lo, PhD) for breast imaging at Duke. Dr. Samei has an active interest in developing other advanced x-ray imaging techniques for the early detection of cancer including limited angle and inverse geometry CT. 2. Objective assessment and impact of display quality on diagnostic accuracy The way in which medical image data are displayed has a direct influence on diagnosis. This dependency is task-specific, and for many tasks in medical imaging, including the early detection and classification of cancer, has not been fully substantiated in quantitative terms. For the last few years, Dr. Samei has led a national task force (AAPM TG18), and served on an ACR and an IEC committee to define standard testing methodologies for medical display devices. His research in this area is currently focused on the influence of display characteristics on the diagnostic interpretation of breast cancer and lung cancer, the fine-tuning of new testing methodologies, and on the influence of ambient light in diagnostic accuracy. These studies are funded by the NIH and the display industry. 3. Objective assessment and clinical relevance of image quality While image quality is a common term in radiology circles, its quantification has proven to be complex, as many factors contribute to the overall degradation of a medical image. Dr. Samei’s research and prior publications have provided a framework for assessing the performance of digital radiography systems, as recently reflected in an international standard on image quality measurements (IEC 62220-1). He is currently pursuing methods to further streamline the assessment methodologies and include other important contributing yet hitherto ignored factors such as scattered radiation. Furthermore, the connection between diagnostic accuracy and the scientific metrics of image quality is not straightforward. Two studies are now in progress to substantiate the relevance of these quantities in radiography (chest and breast) and in computed tomography (pediatric CT). The former investigation, initiated in his laboratory, is supported by a pre-doctoral grant from the DOD. The pediatric CT research initiative, supported by a current industrial grant from GE, aims to investigate strategies to reduce radiation dose in pediatric CT without compromising diagnostic quality. 4. Quantitative imaging By and large, since its inception, radiology as a discipline has been developed as a qualitative discipline in which physicians “interpret” medical images to gain diagnostic insights. However, current, mostly digital, medical images contain a large amount of information, which if effectively harnessed, can be invaluable in the quantification of the disease, in the assessment of the effectiveness of various therapeutic regimens, and in providing tractability of the medical information toward evidenced-based and patient-specific medicine. The main technical obstacle preventing this potential has been the lack of certainty about the extent to which image data can be analyzed quantitatively in light of various sources of variability (eg, case variability, patient positioning, system variability, etc). However, there is little doubt that the future of radiology is quantitative, and additional research is warranted to lead to that transition. Dr. Samei has recently initiated a number of research projects aiming to assess the relative magnitude of the sources of variability in diagnostic radiology, and from that to devise approaches by which robust quantitative data can be extracted from medical images. Initial projects have focused on CT and breast tomosynthesis. Additional projects are planned for digital mammography and digital radiography. He is also fostering additional quantitative imaging projects led by other faculty members in RAI Labs. With the preliminary results of these ongoing initiatives, he aims to lead RAI Labs toward a comprehensive program project on quantitative imaging. 5.Molecular imaging X-ray imaging is now used extensively throughout the world due to its low cost, widespread availability, speed, ease of interpretation, and exquisite representation of anatomy. However, it has to date been limited to structural imaging. But, the underlying processes behind many human diseases occur at the molecular level, suggesting many advantages that the imaging of these molecular and functional processes can provide. In spite of the dominance, cost-effectiveness and maturity of x-ray imaging, almost all molecular imaging investigators have focused their research on non-x-ray based technologies such as MRI, nuclear medicine, and optical imaging techniques. Dr. Samei has recently initiated a few preliminary studies to assess how conventional x-ray imaging can be extended to provide molecular and functional information. The overall goal of his investigation is to develop x-ray-based molecular and functional imaging methods. While maintaining the key advantages of x-ray imaging, the proposed method will provide functional images that have higher spatial and temporal resolution than what is currently possible through more “conventional” functional imaging methods (eg, Nuclear Medicine and fMRI), and that are inherently co-registered to anatomical information. The method employs nano-particle, “smart,” liposomal contrast agents to reveal specific functional and molecular processes and physiological functions within the human body, initially for the purpose of early detection of cancer and cardiovascular disease, the two leading causes of death world-wide. The pursuit of this project is particularly timely in light of recent developments in the fabrication of stable nano-particle liposomes and the development of antibody labeling methods. The application of functional and molecular imaging to x-ray technology has the potential to profoundly impact global clinical practice by spreading the benefits of functional imaging through a more accessible technology, unleashing the power and the promise of molecular imaging for many.

Areas of Interest:
Medical Physics

Representative Publications   (More Publications)

  1. AS Chawla, RS Saunders, S Singh, JY Lo, E Samei, Towards optimized acquisition scheme for multiprojection correlation imaging of breast cancer., Academic radiology, United States, vol. 16 no. 4 (April, 2009), pp. 456-63  [abs].
  2. BJ Pollard, E Samei, AS Chawla, J Baker, S Ghate, C Kim, MS Soo, N Hashimoto, The influence of increased ambient lighting on mass detection in mammograms., Academic radiology, United States, vol. 16 no. 3 (March, 2009), pp. 299-304  [abs].
  3. X Li, E Samei, Comparison of patient size-based methods for estimating quantum noise in CT images of the lung., Medical physics, United States, vol. 36 no. 2 (February, 2009), pp. 541-6  [abs].
  4. C Castella, MP Eckstein, CK Abbey, K Kinkel, FR Verdun, RS Saunders, E Samei, FO Bochud, Mass detection on mammograms: influence of signal shape uncertainty on human and model observers., Journal of the Optical Society of America. A, Optics, image science, and vision, United States, vol. 26 no. 2 (February, 2009), pp. 425-36  [abs].
  5. X Li, E Samei, DM Delong, RP Jones, AM Gaca, CL Hollingsworth, CM Maxfield, CW Carrico, DP Frush, Three-dimensional simulation of lung nodules for paediatric multi-detector array CT., The British journal of radiology (January, 2009)  [abs].
  6. X Li, E Samei, WP Segars, GM Sturgeon, JG Colsher, DP Frush, Patient-specific dose estimation for pediatric chest CT., Medical physics, United States, vol. 35 no. 12 (December, 2008), pp. 5821-8  [abs].
  7. E Samei, JY Lo, TT Yoshizumi, JL Jesneck, JT Dobbins, CE Floyd, HP McAdams, CE Ravin, Comparative scatter and dose performance of slot-scan and full-field digital chest radiography systems., Radiology, United States, vol. 235 no. 3 (June, 2005), pp. 940-9  [abs].
  8. RS Saunders, E Samei, JL Jesneck, JY Lo, Physical characterization of a prototype selenium-based full field digital mammography detector., Medical physics, United States, vol. 32 no. 2 (February, 2005), pp. 588-99  [abs].
  9. E Samei, A Rowberg, E Avraham, C Cornelius, Toward clinically relevant standardization of image quality., Journal of digital imaging : the official journal of the Society for Computer Applications in Radiology, United States, vol. 17 no. 4 (December, 2004), pp. 271-8  [abs].
  10. E Samei, SL Wright, Luminance and contrast performance of liquid crystal displays for mammographic applications., Technology in cancer research & treatment, United States, vol. 3 no. 5 (October, 2004), pp. 429-36  [abs].
  11. E Samei, RS Saunders, JY Lo, JT Dobbins, JL Jesneck, CE Floyd, CE Ravin, Fundamental imaging characteristics of a slot-scan digital chest radiographic system., Medical physics, United States, vol. 31 no. 9 (September, 2004), pp. 2687-98  [abs].
  12. U Neitzel, S Günther-Kohfahl, G Borasi, E Samei, Determination of the detective quantum efficiency of a digital x-ray detector: comparison of three evaluations using a common image data set., Medical physics, United States, vol. 31 no. 8 (August, 2004), pp. 2205-11  [abs].
  13. H Jung, HJ Kim, WS Kang, SK Yoo, K Fujioka, M Hasegawa, E Samei, Assessment of flat panel LCD primary class display performance based on AAPM TG 18 acceptance protocol., Medical physics, United States, vol. 31 no. 7 (July, 2004), pp. 2155-64  [abs].
  14. RS Saunders, E Samei, C Hoeschen, Impact of resolution and noise characteristics of digital radiographic detectors on the detectability of lung nodules., Medical physics, United States, vol. 31 no. 6 (June, 2004), pp. 1603-13  [abs].
  15. RL McKinley, MP Tornai, E Samei, ML Bradshaw, Simulation study of a quasi-monochromatic beam for x-ray computed mammotomography., Medical physics, United States, vol. 31 no. 4 (April, 2004), pp. 800-13  [abs].
  16. RS Saunders, E Samei, A method for modifying the image quality parameters of digital radiographic images., Medical physics, United States, vol. 30 no. 11 (November, 2003), pp. 3006-17  [abs].
  17. SR Turner, E Samei, BS Hertzberg, DM DeLong, R Vargas-Voracek, A Singer, CH Maynor, MA Kliewer, Sonography of fetal choroid plexus cysts: detection depends on cyst size and gestational age., Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine, United States, vol. 22 no. 11 (November, 2003), pp. 1219-27  [abs].
  18. E Samei, Image quality in two phosphor-based flat panel digital radiographic detectors., Medical physics, United States, vol. 30 no. 7 (July, 2003), pp. 1747-57  [abs].
  19. E Samei, MJ Flynn, E Peterson, WR Eyler, Subtle lung nodules: influence of local anatomic variations on detection., Radiology, United States, vol. 228 no. 1 (July, 2003), pp. 76-84  [abs].
  20. E Samei, MJ Flynn, An experimental comparison of detector performance for direct and indirect digital radiography systems., Medical physics, United States, vol. 30 no. 4 (April, 2003), pp. 608-22  [abs].
  21. E Samei, JG Hill, GD Frey, WM Southgate, E Mah, D Delong, Evaluation of a flat panel digital radiographic system for low-dose portable imaging of neonates., Medical physics, United States, vol. 30 no. 4 (April, 2003), pp. 601-7  [abs].
  22. JT Dobbins, E Samei, HG Chotas, RJ Warp, AH Baydush, CE Floyd, CE Ravin, Chest radiography: optimization of X-ray spectrum for cesium iodide-amorphous silicon flat-panel detector., Radiology, United States, vol. 226 no. 1 (January, 2003), pp. 221-30  [abs].
  23. E Samei, MJ Flynn, An experimental comparison of detector performance for computed radiography systems., Medical physics, United States, vol. 29 no. 4 (April, 2002), pp. 447-59  [abs].
  24. E Samei, JA Seibert, CE Willis, MJ Flynn, E Mah, KL Junck, Performance evaluation of computed radiography systems., Medical physics, United States, vol. 28 no. 3 (March, 2001), pp. 361-71  [abs].
  25. E Mah, E Samei, DJ Peck, Evaluation of a quality control phantom for digital chest radiography., Journal of applied clinical medical physics / American College of Medical Physics, United States, vol. 2 no. 2 (2001), pp. 90-101  [abs].
  26. MT Ryan, KM Spicer, D Frei-Lahr, E Samei, GD Frey, H Hargrove, G Bloodworth, Health physics consequences of out-patient treatment of non-Hodgkin's lymphoma with 131I-radiolabeled anti-B1 antibody., Health physics, UNITED STATES, vol. 79 no. 5 Suppl (November, 2000), pp. S52-5  [abs].
  27. KJ Kearfott, S Han, EC Wagner, E Samei, CK Wang, Numerical simulation of a TLD pulsed laser-heating scheme for determination of shallow dose and deep dose in low-LET radiation fields., Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine, England, vol. 52 no. 6 (June, 2000), pp. 1419-29  [abs].
  28. E Samei, MJ Flynn, WR Eyler, Detection of subtle lung nodules: relative influence of quantum and anatomic noise on chest radiographs., Radiology, UNITED STATES, vol. 213 no. 3 (December, 1999), pp. 727-34  [abs].
  29. MJ Flynn, E Samei, Experimental comparison of noise and resolution for 2k and 4k storage phosphor radiography systems., Medical physics, UNITED STATES, vol. 26 no. 8 (August, 1999), pp. 1612-23  [abs].
  30. E Samei, MJ Flynn, DA Reimann, A method for measuring the presampled MTF of digital radiographic systems using an edge test device., Medical physics, UNITED STATES, vol. 25 no. 1 (January, 1998), pp. 102-13  [abs].
  31. E Samei, MJ Flynn, WR Eyler, Simulation of subtle lung nodules in projection chest radiography., Radiology, UNITED STATES, vol. 202 no. 1 (January, 1997), pp. 117-24  [abs].
  32. E Samei, KJ Kearfott, A limited bibliography of the Federal Government-funded human radiation experiments., Health physics, UNITED STATES, vol. 69 no. 6 (December, 1995), pp. 885-91  [abs].
  33. KJ Kearfott, S Han, KL McMahan, E Samei, Sensitivity of a mixed field dosimetry algorithm to uncertainties in thermoluminescent element readings., Health physics, UNITED STATES, vol. 68 no. 3 (March, 1995), pp. 340-9  [abs].
  34. E Samei, AAPM/RSNA physics tutorial for residents: technological and psychophysical considerations for digital mammographic displays., Radiographics : a review publication of the Radiological Society of North America, Inc, United States, vol. 25 no. 2 , pp. 491-501  [abs].
  35. E Samei, JA Seibert, K Andriole, A Badano, J Crawford, B Reiner, MJ Flynn, P Chang, AAPM/RSNA tutorial on equipment selection: PACS equipment overview: general guidelines for purchasing and acceptance testing of PACS equipment., Radiographics : a review publication of the Radiological Society of North America, Inc, United States, vol. 24 no. 1 , pp. 313-34  [abs].
  36. GH Beute, MJ Flynn, WR Eyler, E Samei, DL Spizarny, CJ Zylak, Chest radiographic image quality: comparison of asymmetric screen-film, digital storage phosphor, and digital selenium drum systems--preliminary study., Radiographics : a review publication of the Radiological Society of North America, Inc, UNITED STATES, vol. 18 no. 3 , pp. 745-54  [abs].