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A new method based on the multiple beam procedure to obtain ultrasonic angle independent Doppler color (AIDC) images using Doppler color imaging with a sector transducer has been developed. The transducer was sequentially placed at three locations with different direction orientations to acquire velocity information for the same flow field. Equations have been derived and used to obtain the velocity amplitude and flow direction angle for each point in the flow field from the acquired velocity data and the known positions of the transducer. AIDC images then can be reconstructed. To evaluate the feasibility of this method, AIDC images using a sector transducer have been reconstructed for steady flow fields in a latex tube model and for blood flow in the abdominal aorta of normal human subjects. The quantitative results obtained using this method were in reasonably good agreement with those obtained from existing reference methods.

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An experimental system has been used to acquire Doppler color images using a linear transducer from an ultrasound scanner to reconstruct angle independent Doppler color (AIDC) images in normal carotid arteries in 21 volunteers. Images were first taken from relatively straight segments in the common carotid artery, and comparisons were made in a small area at the center stream. At peak systole, the correlation coefficient of the velocity amplitudes between AIDC imaging (AIDCI) and duplex scanning was 0.94; the correlation coefficient between the flow angles measured from AIDCI and the angles of the vessel wall was 0.99. Periodic variations of the flow angle over the cardiac cycle were always observed by AIDCI, whereas the changes in the geometric angle of the vessel itself were insignificant. This observation suggests that the AIDCI technique is sensitive to alterations of flow direction. On the other hand, the deviation of the flow angle from a fixed correction angle in duplex scanning may cause a certain degree of error in velocity determination. AIDC images were also obtained at the carotid bifurcation. The results show that the AIDCI technique is able to depict major flow features, such as velocity skewing, flow separation, flow reversal and vortical flow, in a complex flow field.

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Doppler color imaging can easily render flow information within the vessels and simultaneously provide anatomic information for diagnostic purposes. However, the angle dependence problem of the Doppler velocity measurement is a significant barrier for continuing progress toward quantitative clinical applications of this technology. This paper presents a method and the computer implementation for reconstruction of the 2-D flow velocity field (angle independent) in ultrasound Doppler color imaging. Formulae for deriving angle independent velocity amplitude and angle direction from the color images acquired with a linear array transducer are given. The hardware configuration of the data acquiring and processing system is described. Major considerations in the development of algorithms, especially the strategies for reducing the computation time are presented.

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A multiple beam technique was utilized to obtain angle independent Doppler color images (AIDCI) using an ultrasonic scanner with a linear transducer. A quantitative study using steady flow models has been performed to evaluate the accuracy of this method in velocity measurements. The results show that the velocity amplitudes measured with this method correlated with those calculated from the measured flow rates (r = 0.95-0.98). The flow angles obtained with this method also correlated with those calculated from the coordinates of the tube image (r = 0.93-0.96). To improve the interpretation of the angle independent results, a method for visualizing two-dimensional flow fields is presented and compared with two existing methods.

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Data from flow-cytometric analysis of DNA of Ehrlich ascites tumor cells were fitted using non-linear least squares curve fitting routines. Analysis of rates of synthesis from the derived S-period profiles revealed a pattern of changing rates of DNA synthesis during the S-period. Three main peaks are seen whose trough to through periods range from 0 to 16%, 16 to 65%, 65 to 100% of the DNA synthesized during S. The differences between the peak rates and rates in the intervening troughs are small, about 10% of the maximum, but these occur reproducibly. Some differences in the DNA distribution profiles, hence rate profiles, can be seen among samples taken at different times during the day. These are thought to reflect the effects of circadian rhythms, but they are not large enough to obscure the general pattern of rate shifts that occur during the S-period. Analyses of radioactivity of 3H-thymidine pulse labelled cells, sorted across the S-period, were in accord with the results obtained from the DNA distributions. A parallel analysis of DNA and histones showed a correspondence in the timing and direction of shifts in rate for both during the middle part of the S-period.

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Flow cytometry of cellular DNA content revealed ploidy abnormalities in 15% of 170 patients with various leukemias, in 50% of 26 patients with malignant lymphomas, and in 68% of 110 patients with multiple myeloma, for an overall incidence of DNA content abnormality of 37% in 306 patients with hematologic malignancies. Since the incidence of ploidy abnormality in over 100 solid tumors exceeded 90%. DNA flow cytometry is also ideally suited to screen for bone marrow metastases. Cell separation by centrifugal elutriation was shown to permit enrichment of aneuploid cells, including one example where cells with abnormal DNA content were not recognized in the unfractionated sample. Biparametric measurements of acridine orange-stained cells for DNA and RNA content analysis were suitable to enhance the discriminatory power of flow cytometric detection of lymphoma and myeloma tumor cells in heterogeneous cell populations of bone marrow and lymph nodes. DNA/RNA measurements in leukemia, (the disease category with the lowest incidence of abnormal DNA mode) revealed a markedly higher mean RNA content in acute myeloid leukemia compared with normal or acute lymphoblastic leukemia bone marrow. While these different RNA content patterns were found in whole marrow, cell separation by centrifugal elutriation of normal marrow disclosed cell subpopulations of myeloid precursor cells with a RNA content pattern similar to that of unseparated AML marrow. Hence, the described differences in RNA content between normal and AML marrow seem to be related to the greater heterogeneity of differentiated cells in normal marrow and per se do not appear to be a unique feature of the leukemia disease process.

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Flow-cytometric analysis of acriflavin-Feulgen stained chicken erythrocytes shows a complex distribution of amounts of deoxyribonucleic acid fluorescence, the profile consisting of a main peak and a right hand shoulder. This bimodal distribution, an artifact characteristically seen on analysis of flattened cells using orthogonal flow systems, results from fluorescence emission in preferred directions stemming from the combined effects of refractility and orientation of the cells. The shoulder disappears on analysis of lysed erythrocyte ghosts, also on analysis of cells in a medium whose refractive index approximates that the cells. An orientation effect for matrue erythrocytes was indicated by reanalysis of fractions after sorting on the basis of high and low fluorescence or scatter signals. Both fractions gave the original range of values on reanalysis, although some changes in shape of the profile and in the peak positions for the sorted cells were seen. Sodium dodecyl sulfate treatment of stained cells "loosened" the cells' structure, yielding lowered scatter values, and fluorescence values approaching those of the shoulder. The average fluorescence emission of the erythrocytes was lower than that of reticulocytes and lymphocytes. The values of the latter correspond closely, although coincidently, to that the erythrocyte shoulder values. Dual parameter analysis of forward light scatter, and fluorescence, which was detected at 90 degrees to the laser beam, showed the low fluorescence to be accompanied by low scatter signal, and the high fluorescence among the cells with the high scatter signal. The lowered forward scatter signal is due to a wider scattering of light from cells oriented edge-on to the detector, and loss of signal beyond the acceptance angle of the detector. These results suggest that the preferred directions for fluorescence are in the plane of the cells, and the values are dependent on the cells' orientation in the stream. These interpretations were supported by the results of analysis of partially oriented cells. The approaches used and conclusions arrived at are similar to those of Gledhill et al (16), Van Dilla et al (37), in their analysis of fluorescence of flat sperm cells although the affects in the case of the erythrocytes are less extreme.

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