Despite the importance of the vasculature during tumorigenesis and during antiangiogenesis treatm... more Despite the importance of the vasculature during tumorigenesis and during antiangiogenesis treatment, there are few methods available to visualize conveniently the three-dimensional microvascular s...
... saturation of mixed venous (pulmonary artery) blood are at respira-tory frequency and result ... more ... saturation of mixed venous (pulmonary artery) blood are at respira-tory frequency and result from ... with sinusoidal variations in pressure applied to the dog's body sur-face by the ... the pathophysiologic effects of ex-tremely high transient or sustained acceleration encountered in ...
... 71, NO. 3, MARCH 1983 HighlSpeed Three-Dimensional X-Ray Computed Tomography: The Dynamic Spa... more ... 71, NO. 3, MARCH 1983 HighlSpeed Three-Dimensional X-Ray Computed Tomography: The Dynamic Spatial Reconstructor ... Invited Paper Abstmct-Most X-ray (3 scanners require a few seconds to produce a single two-dimensional (2-D) image of a ~ 0 8 s section of the body. ...
ABSTRACT Increasing the spatial resolution of current multislice clinical CT system is always des... more ABSTRACT Increasing the spatial resolution of current multislice clinical CT system is always desirable. However, further resolution improvement by reducing the pixel pitch or the aperture of the detector elements is difficult because of the tradeoff between the pixel size and dose level. In this paper, we demonstrate a methodology for improving spatial resolution of a clinical multislice CT without reducing the detector element size. The flying focal spot (i.e. electron beam wobbling) technique is used to increase the data sampling rate for in-plane (x-y) and z-axis scan acquisitions. In order to reduce the number of focal spot positions to achieve a certain spatial resolution, a super resolution technique using projections onto convex sets (POCS) is applied here to improve projection raw data sampling with reduced number of focal spot positions. The results indicate that it is possible to significantly increase spatial resolution on current multislice clinical CT systems without reducing the detector element size. In absence of noise, super resolution algorithms employing iterative regularization, such as POCS, can reduce the required number of focal spot positions. Thus, technical requirements on the multislice CT systems, such as rotation time and number of projections per rotation, can be much relaxed. However, noise reduction methods and methods of reducing projections per rotation, such as compressed sensing, are needed to work with super resolution technique to keep the radiation exposure from exceeding the current limit of clinical multislice CT.
Quantification of single-kidney glomerular filtration rate with electron-beam computed tomography... more Quantification of single-kidney glomerular filtration rate with electron-beam computed tomography. [Proceedings of SPIE 3978, 539 (2000)]. Lilach O. Lerman, Erik L. Ritman, Laura I. Pelaez, Patrick F. Sheedy II, James D. Krier. Abstract. ...
This note is a reorganization of the examples in [Faridani, Ritman, and Smith, SIAM J. Appl. Math... more This note is a reorganization of the examples in [Faridani, Ritman, and Smith, SIAM J. Appl. Math., 52(1992), pp. 459–484], which became disorganized while the article was in press.
Medical Imaging 1996: Physiology and Function from Multidimensional Images, 1996
ABSTRACT Electron beam computed tomography (EBCT), also known as ultrafast-CT or cine-CT, uses a ... more ABSTRACT Electron beam computed tomography (EBCT), also known as ultrafast-CT or cine-CT, uses a unique scanning architecture which allows for multiple high spatial resolution electrocardiographic triggered images of the beating heart. A recent study has demonstrated the feasibility of qualitative comparisons between EBCT derived 3D coronary angiograms and invasive angiography. Stenoses of the proximal portions of the left anterior descending and right coronary arteries were readily identified, but description of atherosclerotic narrowing in the left circumflex artery (and distal epicardial disease) was not possible with any degree of confidence. Although these preliminary studies support the notion that this approach has potential, the images overall were suboptimal for clinical application as an adjunct to invasive angiography. Furthermore, these studies did not examine different methods of EBCT scan acquisition, tomographic slice thicknesses, extent of scan overlap, or other segmentation, thresholding, and interpolation algorithms. Our laboratory has initiated investigation of these aspects and limitations of EBCT coronary angiography. Specific areas of research include defining effects of cardiac orientation; defining the effects of tomographic slice thickness and intensity (gradient) versus positional (shaped based) interpolation; and defining applicability of imaging each of the major epicardial coronary arteries for quantitative definition of vessel size, cross-sectional area, taper, and discrete vessel narrowing.
Abstract Three main computing aspects encountered in the stress and strain analysis of the intact... more Abstract Three main computing aspects encountered in the stress and strain analysis of the intact heart using the finite element technique, namely, the automatic partitioning of the myocardium of the heart into finite elements, the assemblage of the structural stiffness matrix of the myocardium, and the storage and retrieval of its nonzero coefficients are described. The influence of boundary conditions and different relaxation factors on the speed of convergence to the final solution are also described. Programming for the solution of the large number of simultaneous linear equations generated by the finite element method on computers with capacity not exceeding 32K words of memory required special attention to very compact storage of the stiffness matrix and the retrieval of its coefficients. Computation time for the three-dimensional stress and strain analysis of a heart represented by approximately 7000 finite elements was less than 20–25 min on a CDC 3500 computer operated in the multibatch MASTER mode.
This paper investigates high-resolution reconstructions from efficiently sampled data in parallel... more This paper investigates high-resolution reconstructions from efficiently sampled data in parallel-beam tomography, in particular, local tomography. A class of sampling schemes is defined and characterized, and it is shown that the standard scheme and the interlaced scheme of Cormack (Cormack A M 1978 Phys. Med. Biol. 23 1141-8) are most promising. An error analysis for the filtered backprojection algorithm for both global and local tomography is presented. The analysis provides insights on how to realize the theoretically superior resolution of the interlaced scheme in practice. A numerical experiment with real data indicates the feasibility of high-resolution local tomography using the interlaced scheme.
Although the rat is the most common animal model used in studying osteoporosis, it is often used ... more Although the rat is the most common animal model used in studying osteoporosis, it is often used inappropriately. Osteoporosis is a disease that most commonly occurs in humans long after growth plate fusion with the associated cessation of longitudinal bone growth, but there has been a question as to when or to what extent the rat growth plate fuses. To investigate this question, we used microcomputed X-ray tomography, at voxel resolutions ranging from (5.7 micro m)(3) to (11 micro m)(3), to image the proximal epiphyseal growth plates of both male (n = 19) and female (n = 15) rat tibiae, ranging in age from 2 to 25 months. The three-dimensional images were used to evaluate fusion of the epiphyseal growth plate by quantitating the amount of cancellous bone that has bridged across the growth plate. The results suggest that the time course of fusion of the epiphyseal growth plate follows a sigmoidal pattern, with 10% of the maximum number of bridges having formed by 3.9 months in the male tibiae and 5.8 months in the female tibiae, 50% of the maximum number of bridges having formed by 5.6 months in the male tibiae and 5.9 months in the female tibiae, and 90% of the total maximum of bridges have formed by 7.4 months for the males and 6.5 months for the females. The total volume of bridges per tibia at the age at which the maximum number of bridges per tibia has first formed is 0.99 mm(3)/tibia for the males and 0.40 mm(3)/tibia for the females. After the maximum number of bridges (-290 for females, -360 for males) have formed the total volume of bridges per tibia continues to increase for an additional 7.0 months in the males and 17.0 months for the females until they reach maximum values (-1.5 mm(3)/tibia for the males and -2.2 mm(3)/tibia for the females).
Despite the importance of the vasculature during tumorigenesis and during antiangiogenesis treatm... more Despite the importance of the vasculature during tumorigenesis and during antiangiogenesis treatment, there are few methods available to visualize conveniently the three-dimensional microvascular s...
... saturation of mixed venous (pulmonary artery) blood are at respira-tory frequency and result ... more ... saturation of mixed venous (pulmonary artery) blood are at respira-tory frequency and result from ... with sinusoidal variations in pressure applied to the dog's body sur-face by the ... the pathophysiologic effects of ex-tremely high transient or sustained acceleration encountered in ...
... 71, NO. 3, MARCH 1983 HighlSpeed Three-Dimensional X-Ray Computed Tomography: The Dynamic Spa... more ... 71, NO. 3, MARCH 1983 HighlSpeed Three-Dimensional X-Ray Computed Tomography: The Dynamic Spatial Reconstructor ... Invited Paper Abstmct-Most X-ray (3 scanners require a few seconds to produce a single two-dimensional (2-D) image of a ~ 0 8 s section of the body. ...
ABSTRACT Increasing the spatial resolution of current multislice clinical CT system is always des... more ABSTRACT Increasing the spatial resolution of current multislice clinical CT system is always desirable. However, further resolution improvement by reducing the pixel pitch or the aperture of the detector elements is difficult because of the tradeoff between the pixel size and dose level. In this paper, we demonstrate a methodology for improving spatial resolution of a clinical multislice CT without reducing the detector element size. The flying focal spot (i.e. electron beam wobbling) technique is used to increase the data sampling rate for in-plane (x-y) and z-axis scan acquisitions. In order to reduce the number of focal spot positions to achieve a certain spatial resolution, a super resolution technique using projections onto convex sets (POCS) is applied here to improve projection raw data sampling with reduced number of focal spot positions. The results indicate that it is possible to significantly increase spatial resolution on current multislice clinical CT systems without reducing the detector element size. In absence of noise, super resolution algorithms employing iterative regularization, such as POCS, can reduce the required number of focal spot positions. Thus, technical requirements on the multislice CT systems, such as rotation time and number of projections per rotation, can be much relaxed. However, noise reduction methods and methods of reducing projections per rotation, such as compressed sensing, are needed to work with super resolution technique to keep the radiation exposure from exceeding the current limit of clinical multislice CT.
Quantification of single-kidney glomerular filtration rate with electron-beam computed tomography... more Quantification of single-kidney glomerular filtration rate with electron-beam computed tomography. [Proceedings of SPIE 3978, 539 (2000)]. Lilach O. Lerman, Erik L. Ritman, Laura I. Pelaez, Patrick F. Sheedy II, James D. Krier. Abstract. ...
This note is a reorganization of the examples in [Faridani, Ritman, and Smith, SIAM J. Appl. Math... more This note is a reorganization of the examples in [Faridani, Ritman, and Smith, SIAM J. Appl. Math., 52(1992), pp. 459–484], which became disorganized while the article was in press.
Medical Imaging 1996: Physiology and Function from Multidimensional Images, 1996
ABSTRACT Electron beam computed tomography (EBCT), also known as ultrafast-CT or cine-CT, uses a ... more ABSTRACT Electron beam computed tomography (EBCT), also known as ultrafast-CT or cine-CT, uses a unique scanning architecture which allows for multiple high spatial resolution electrocardiographic triggered images of the beating heart. A recent study has demonstrated the feasibility of qualitative comparisons between EBCT derived 3D coronary angiograms and invasive angiography. Stenoses of the proximal portions of the left anterior descending and right coronary arteries were readily identified, but description of atherosclerotic narrowing in the left circumflex artery (and distal epicardial disease) was not possible with any degree of confidence. Although these preliminary studies support the notion that this approach has potential, the images overall were suboptimal for clinical application as an adjunct to invasive angiography. Furthermore, these studies did not examine different methods of EBCT scan acquisition, tomographic slice thicknesses, extent of scan overlap, or other segmentation, thresholding, and interpolation algorithms. Our laboratory has initiated investigation of these aspects and limitations of EBCT coronary angiography. Specific areas of research include defining effects of cardiac orientation; defining the effects of tomographic slice thickness and intensity (gradient) versus positional (shaped based) interpolation; and defining applicability of imaging each of the major epicardial coronary arteries for quantitative definition of vessel size, cross-sectional area, taper, and discrete vessel narrowing.
Abstract Three main computing aspects encountered in the stress and strain analysis of the intact... more Abstract Three main computing aspects encountered in the stress and strain analysis of the intact heart using the finite element technique, namely, the automatic partitioning of the myocardium of the heart into finite elements, the assemblage of the structural stiffness matrix of the myocardium, and the storage and retrieval of its nonzero coefficients are described. The influence of boundary conditions and different relaxation factors on the speed of convergence to the final solution are also described. Programming for the solution of the large number of simultaneous linear equations generated by the finite element method on computers with capacity not exceeding 32K words of memory required special attention to very compact storage of the stiffness matrix and the retrieval of its coefficients. Computation time for the three-dimensional stress and strain analysis of a heart represented by approximately 7000 finite elements was less than 20–25 min on a CDC 3500 computer operated in the multibatch MASTER mode.
This paper investigates high-resolution reconstructions from efficiently sampled data in parallel... more This paper investigates high-resolution reconstructions from efficiently sampled data in parallel-beam tomography, in particular, local tomography. A class of sampling schemes is defined and characterized, and it is shown that the standard scheme and the interlaced scheme of Cormack (Cormack A M 1978 Phys. Med. Biol. 23 1141-8) are most promising. An error analysis for the filtered backprojection algorithm for both global and local tomography is presented. The analysis provides insights on how to realize the theoretically superior resolution of the interlaced scheme in practice. A numerical experiment with real data indicates the feasibility of high-resolution local tomography using the interlaced scheme.
Although the rat is the most common animal model used in studying osteoporosis, it is often used ... more Although the rat is the most common animal model used in studying osteoporosis, it is often used inappropriately. Osteoporosis is a disease that most commonly occurs in humans long after growth plate fusion with the associated cessation of longitudinal bone growth, but there has been a question as to when or to what extent the rat growth plate fuses. To investigate this question, we used microcomputed X-ray tomography, at voxel resolutions ranging from (5.7 micro m)(3) to (11 micro m)(3), to image the proximal epiphyseal growth plates of both male (n = 19) and female (n = 15) rat tibiae, ranging in age from 2 to 25 months. The three-dimensional images were used to evaluate fusion of the epiphyseal growth plate by quantitating the amount of cancellous bone that has bridged across the growth plate. The results suggest that the time course of fusion of the epiphyseal growth plate follows a sigmoidal pattern, with 10% of the maximum number of bridges having formed by 3.9 months in the male tibiae and 5.8 months in the female tibiae, 50% of the maximum number of bridges having formed by 5.6 months in the male tibiae and 5.9 months in the female tibiae, and 90% of the total maximum of bridges have formed by 7.4 months for the males and 6.5 months for the females. The total volume of bridges per tibia at the age at which the maximum number of bridges per tibia has first formed is 0.99 mm(3)/tibia for the males and 0.40 mm(3)/tibia for the females. After the maximum number of bridges (-290 for females, -360 for males) have formed the total volume of bridges per tibia continues to increase for an additional 7.0 months in the males and 17.0 months for the females until they reach maximum values (-1.5 mm(3)/tibia for the males and -2.2 mm(3)/tibia for the females).
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