Ultrasound Computed Tomography in Breast Imaging: First Clinical Results of a Custom-Made Scanner

Zusammenfassung

Ziel: Evaluation eines Ultraschall-Computertomografie(USCT)-Systems, mit dem die weibliche Brust aus mehreren Richtungen in koronalen Schnittebenen abgebildet wird, sodass durch ein Full Angle Spatial Compounding (FASC) und eine Berechnung der Schallgeschwindigkeit (speed of sound, SoS) aussagekräftige Bildrekonstruktionen möglich sind. Material und Methoden: Wir entwickelten ein PC-gesteuertes System, bei dem der Schallwandler eines konventionellen Ultraschallsystems in einem Wasserbehälter kreisförmig in mehreren Schnittebenen um die weibliche Brust gefahren wird. In einer Machbarkeitsstudie wurden 3 Probandinnen (26 – 74 Jahre) und eine Patientin mit Mammakarzinom untersucht. Die Frauen lagen in Bauchlage auf einer Patientenliege, wobei die zu untersuchende Brust durch eine Öffnung in den o. g. Wasserbehälter geführt wurde. Zur Berechnung der SoS im Brustgewebe wurden Echosignale eines Reflektors verwendet, welcher der Bewegung des Schallkopfs synchron auf der Brustrückseite folgt. Die Ultraschall-Daten wurden offline in einer selbstentwickelten Software verarbeitet, um die FASC- und SoS-Bilder zu berechnen. Ergebnisse: Die FASC-Bildern wiesen eine Reduktion von Artefakten (z. B. Schallschatten von Cooper-Ligamenten und unregelmäßigen Rändern inhomogener Läsionen) und Speckel auf. Eine klarere Darstellung der Brustgewebearchitektur wurde erreicht. Die Rekonstruktionen der SoS-Bilder lieferten weitere diagnostisch verwertbare Informationen und verminderten bei der FASC-Rekonstruktion geometrische Verzerrungen. Schwierigkeiten ergaben sich bei der Darstellung von thoraxwandnahen und axillären Läsionen. Schlussfolgerung: Erste klinische Ergebnisse zeigen das Potenzial der USCT, eine qualitativ hochwertige, automatisierte und standardisierte Ultraschallbildgebung der Brust zu realisieren.

Abstract

Purpose: To test a system using ultrasound computed tomography (USCT) that superimposes ultrasound data acquired in one cross-sectional plane from multiple angles around the breast (Full Angle Spatial Compounding, FASC) and to reconstruct the distribution of the speed of sound in the breast (SoS reconstruction). Materials and Methods: We developed a system combining a conventional ultrasound scanner with a PC-controlled mechanical setup integrated in a custom-made examination couch. In a feasibility study, 3 volunteers (age 26 – 74 years) and one patient with breast cancer were studied. Subjects were placed in the prone position on this couch, with the breast hanging in a water tank. The ultrasound probe was moved in several planes around the breast. A curved reflector that followed the movement of the probe behind the breast was used to calculate the SoS within the breast tissue. Echo-data was processed offline by custom-made software to calculate both FASC and SoS images. Results: In FASC images a reduction of artifacts (i. e. shadowing of Cooper’s ligaments and irregular edges of inhomogeneous lesions) and speckles as well as clear visualization of the inner architecture of the breast was achieved. SoS images delivered further diagnostic information and helped to compensate for geometric distortions in the computed images. Difficulties in the visualization of lesions near the thoracic wall and/or the axillary are limitations of this technique. Conclusion: The first clinical results of USCT imaging have proven its feasibility as an automated and standardized technique for breast imaging.

Key words

USCT - FASC - speed of sound - breast ultrasound - breast cancer

References

• 1 Fletcher S W, Black W, Harris R et al. Report of the International Workshop on screening for Breast Cancer.  J Natl Cancer Inst. 1993;  85 1644-1656
• 2 Merz E, Eichhorn K H, Madjar H et al. Indication for and possibilities of gynecological breast sonography after the introduction of mammography screening in Germany.  Ultraschall in Med. 2009;  30 3-5
• 3 Chiorean A R, Durna M M, Dudea S M et al. Sonoelastographically guided preoperative localization of suspicious breast microcalcifications detected with mammography.  Ultraschall in Med. 2009;  30 492-493
• 4 Svensson W E, Pandian A J, Hashimoto H. The Use of Breast Ultrasound Color Doppler Vascular Pattern Morphology Improves Diagnostic Sensitivity with Minimal Change in Specificity.  Ultraschall in Med. 2010;  ; Epub ahead of print
• 5 Irwig L, Houssami N, Vliet van C. New technologies in screening for breast cancer: a systematic review of their accuracy.  Br J Cancer. 2004;  90 2118-2122
• 6 Shipley J A, Duck F A, Goddard D A et al. Automated quantitative volumetric breast ultrasound data-acquisition system.  Ultrasound in Medicine and Biology. 2005;  31 905-917
• 7 Sinha S P, Goodsitt M M, Roubidoux M A et al. Automated ultrasound scanning on a dual-modality breast imaging system: Coverage and motion issues and solutions.  Journal of Ultrasound in Medicine. 2007;  26 645-655
• 8 U-Systems, Inc. .San Jose, CA, USA; 03/2009 http://www.u-sys.com
• 9 Lehmann C D, Andre M P, Fecht B A et al. Through-Transmission US Applied to Breast Imaging.  Acad Radiol. 2000;  7 100-107
• 10 Carson P L, Meyer C R, Scherzinger A L et al. Breast imaging in coronal planes with simultaneous pulse echo and transmission ultrasound.  Science. 1981;  214 1141-1143
• 11 Hiller D, Ermert H. Ultrasound Computerized Tomography using Transmission and Reflection Mode: Application to Medical Diagnosis.  Acoustical Imaging,. 1982;  12 553-562 , Plenum Press, New York
• 12 Hiller D, Ermert H. Tomographic Reconstruction of B-Scan Images.  Acoustical Imaging. 1982;  10 347-364, Plenum Press New York
• 13 Röhrlein G, Ermert H. Speckle in ultrasound computerized reflection mode tomography.  Acoustical Imaging. 1987;  15 341-357, Plenum Press, New York
• 14 Schreiman J S, Gisvold J J, Greenleaf J F et al. Ultrasound transmission computed tomography of the breast.  Radiology. 1984;  150 523-530
• 15 Jago J, Whittingham T A. Experimental Studies in Transmission Ultrasound Computed Tomography.  Phys Med Biol. 1991;  36 1515-1527
• 16 Leconte I, Fellah L. US and dense breasts: where do we stand?.  J Radiol. 2008;  89 1169-1179
• 17 Duric N, Littrup P, Poulo L et al. Detection of breast cancer with ultrasound tomography: first results with the Computed Ultrasound Risk Evaluation (CURE) prototyp.  Med Phys. 2007;  34 773-785
• 18 TechniScan Medical Systems, Inc . Salt Lake City, USA; 03/2009 http://www.techniscanmedicalsystems.com
• 19 Ashfaq M, Ermert H. Ultrasound Spiral Computed Tomography for Differential Diagnosis of Breast Tumors using a Conventional Ultrasound System.  Acoustical Imaging. 2003;  27 627-633, Kluwer Academic/Plenum Publisher, New York
• 20 Hansen C, Hüttebräuker N, Wilkening W et al. Ultrasonographic Contrast Agent Imaging of Sub-Millimeter Vessel Structures with Spatial Compounding: In-vitro Analyses.  Biomed Tech. 2007;  52 274-283
• 21 Hansen C, Hüttebräuker N, Wilkening W et al. Ultrasound Imaging of the Forearm using Full Angle Spatial Compounding.  Proceedings CARS 2008 Int J Comput Assist Radiol Surg. 2008;  3 S361-S362
• 22 Brunke S, Insana M, Dahl J et al. An Ultrasound Research Interface for a Clinical System.  IEEE Trans Ultrason Ferroelect Freq Contr. 2007;  54 198-210
• 23 Foster F S, Strban M, Austin G. The Ultrasound Macroscope: Initial Studies of Breast Tissue.  Ultrason Imaging. 1984;  6 243-261
• 24 Chang C H, Huang S W, Yang H C et al. Reconstruction of Ultrasonic Sound velocity and Attenuation Coefficient using Linear Arrays: Clinical Assessment.  Ultrasound Med Biol. 2007;  33 1681-1687
• 25 Duck F A. Physical Properties of Tissue. London: Academic Press; 1990
• 26 Weiwad W, Heinig A, Goetz L et al. Direct measurement of sound velocity in various specismens of breast tissue.  Invest Radiol. 2000;  35 721-726
• 27 Hansen C, Hüttebräuker N, Wilkening W et al. Full Angle Spatial Compounding for Improved Replenishment Analyses in Contrast Perfusion Imaging: In-vitro Studies.  IEEE Trans Ultrason Ferroelect Freq Contr. 2008;  55 819-831
• 28 Kass M, Wettkin A, Terzopoulus D. Snakes Active Contour Models.  Int J Computervision. 1987;  1 321-331
• 29 Kak A C, Malcolm S. Principles of Computerized Tomographic Imaging. New York: IEEE Press; 1988
• 30 Hansen C, Hüttebräuker N, Wilkening W et al. Three-dimensional Reconstruction of Fine Vascularity in Ultrasound Breast Imaging using Contrast-enhanced Spatial Compounding: In-vitro Analyses.  Acad Radiol. 2008;  15 1155-1164