Ultra high speed transaxial image reconstruction of the heart, lungs, and circulation via numerical approximation methods and optimized processor architecture.
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Blood Circulation↗
Biomedical subjects
B K Gilbert
Publications and source records attributed to B K Gilbert.
Application of optimized parallel processing digital computers and numerical approximation methods to the ultra high-speed three-dimensional reconstruction of the intact thorax.
In order to achieve the computational capability to carry out many thousands of cross-sectional reconstructions, necessary to support a prototype high temporal and spatial resolution cylindrical scanning multiaxial tomographic unit, a series of design, software simulation, and fabrication studies is underway to develop a special-purpose high-speed reconstruction computer. This processor will rely upon integrated circuit arithmetic components of advanced design, and highly parallel architecture to execute X-ray based transaxial reconstruction algorithms at the rate of hundreds of cross sections/sec.
Computers↗
Quantitative imaging of the structure and function of the heart, lungs, and circulation.
A 28-x-ray-source, cylindrical-scanning, transaxial tomographic x-ray-imaging system is in the process of being fabricated. This system will scan synchronously up to 250 parallel transverse cross sections of the human body over an axial range of 25 cm within 0.01 second at a maximum rate of 60 scans per second. The system will provide numerous variations of scanning configurations to permit quantitative assessment of the relative importance of transverse section thickness, image contrast, spatial and temporal resolution, and related computerized algorithms and display techniques. Synchronous imaging at high temporal resolution of a three-dimensional volume--for example, the heart--eliminates the need for successive periods of breath-holding and gated imaging techniques and is essential for quantitation of cardiovascular and pulmonary function and structure in intact animals or humans. Initial clinical applications are expected to be in the early detection of lung cancer and the diagnosis of the nature and degree of congenital and acquired cardiovascular disabilities.
Animals↗
Continuous determination of beat to beat stroke volume from aortic pressure pulses in the dog.
Present methods for measurement of stroke volume from the aortic pressure pulse are not suitable for beat-to-beat determinations during non-steady state conditions because these methods assume that each systolic ejection is equal to the peripheral runoff during the same beat. We have tested a new method which allows determination of an aortic pressure-volume conversion factor over a wide range of pressures during transient changes in stroke volume and infusions of vasoactive drugs in 6 dogs with chronically implanted aortic electromagnetic flowmeters. Each aortic diastolic pressure decay is approximated by an exponential the time constant of which is used to calculate the pressure loss during systole due to blood flow into the periphery. The total increment in aortic pressure due to systolic ejection, if there were no flow from the aorta during systole, then is calculated. The total systolic increment (delta PSV) is assumed to describe the pressure-volume characteristics during systole and is related to stroke volume by a constant multiplier that is derived from the indicator-dilution measurements of cardiac output. The values for beat-to-beat variations that were determined by use of the aortic electromagnetic flowmeter and by this aortic pressure pulse method were found to be within the range of measurement errors of stroke volume determined from individual aortic electromagnetic flow pulses.
Animals↗
A charge coupled transversal filter for biomedical signal conditioning.
The analysis and processing of biological signals is often hampered by the contamination of these low frequency, often low amplitude waveforms by motion artifact in fluid-filled catheter systems and skin electrodes, power line hum, and so on. Although noise suppression techniques have relied upon low pass filtration of the analog signals with active or passive RLC filters, even the most recent active RLC filter implementations display operational characteristics not entirely satisfactory for low frequency applications.
Analog-Digital Conversion↗
A charge coupled transversal filter for biomedical signal conditioning.
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Analog-Digital Conversion↗