Archived: July 29, 2004
Texas Space Grant Consortium Research Report (1996)
Alfred L. Johnston, Director of the Sealy & Smith Laboratory for Medical Ultrasonics
The Texas Space Grant Consortium (TSGC) provided research funding to initiate several three dimensional (3D) Ultrasound projects (Heart Volume & Muscle Volume) for the NASA Life Sciences. 3D ultrasonic image reconstruction combines quantitative measurements with dynamic visual presentations. Jorge Torres, Clarence Nicodemus, and Alfred Johnston are the major contributors to this work. The site for these projects was the University of Texas Medical Branch Sealy & Smith Medical Ultrasonics Laboratory, in which digital video resources provide capabilities for computer animation, 3D image reconstruction, quantitative measurements, and video editing. Advanced Visual Systems (AVS) and Softimage (SI) software were used for rendering 3D images.
Heart volume measurements, derived from ultrasonic sector scanning, acquire a data file of two dimensional short axis views along the long axis of the heart. The phased array scanner is oriented with a parasternal long axis view, and the short axis views are collected by a movement across the left ventricle, beginning at the aortic valve, and completed at the apex of the heart. An electromagnetic or acoustical locator orients the intersecting planes in spatial coordinates necessary for 3D imaging. A wire frame surface rendering of the left ventricle is placed in the long axis view to assure that the series of short axis views have been correctly measured (manual or automatic edge detection). The left ventricle is then evaluated for changes in time (end systolic and end diastolic volumes) and by dynamic visual presentation (spatial orientation).
Muscle Volume measurements, realized from ultrasonic linear array scanning, acquire a data file of two dimensional transverse images along the longitudinal motion of the scanhead, on the skin, over the muscle of interest. A Doppler locator technique is under investigation to automate the determination of scanhead spatial orientation. The Extensor Carpi Ulnaris muscle was reconstructed from one sweep across the muscle with a commercially available linear array transducer. Larger muscles will require larger arrays than now available or employ curved arrays or sector scans.
The Johnson Space Center acquired Advanced Technology Laboratories (ATL) HDI 3000 ultrasound scanners in 1996, which provide 2D image quality necessary for 3D reconstruction of the heart's left ventricle and the skeletal muscle of interest during long exposures to microgravity conditions. David Martin, a NASA JSC sonographer, provided the UTMB medical ultrasonics program heart and muscle images, acquired with this NASA equipment purchased for the International Space Station. Multitasking Software Management (MSM), the medical ultrasound development initiated by Ron Daigle, ATL Atlantis Technical Director, was introduced In 1997. Advancements in microprocessor technology are fully exploited in the HDI 1000 system architecture. These concepts recently announced by ATL were presented to JSC personnel (Sue Fortney and Dennis Grounds) in a meeting held at the Universities Space Research Association (USRA) Houston site on April 12,1996.
Heart and muscle quantitative measurements and dynamic 3D visualization digital videos were presented to Sue Fortney, Human Research Facility Project Scientist, on January 23, 1997. At this meeting we proposed a combined muscle volume and bone strength measurement system, combining work at UT Southwestern Medical Center (UTSWMC) in Dallas and UT Medical Branch in Galveston. UTMB Medical Ultrasonics Program participants are working with Peter Antich at UT Southwestern, [the originator of the bone strength technique, Ultrasound Critical Angle Reflectometry (UCR)]. This collaboration and joint endeavor of academia, government, and industry combine the resources of two University of Texas Medical Centers, two NASA divisions (Headquarters, Washington DC and JSC, Houston), and two industry participants (Rockwell International, Houston and ATL, Bothell, WA).
Last Modified: Tue Feb 17, 1998