- Email: [email protected]
Project title myocardial blood oxygenation assessment using MRI
during reperfusion. Hearts will be supplied 13C enriched substrates to probe enzymatic activity in testing a three-fold hypothesis that: 1) countering depressed PDH activity at reperfusion avoids the production of lactate which otherwise impairs recovery via increased energetic demands due to proton load; 2) activating the branched chain keto-acid dehydrogenase promotes recovery of oxidative metabolism in support of contractility; 3) 13C NMR of intact hearts reflects changes in the balance of cytosolic and mitochondrial metabolites. Experiments explore regulatory mechanisms of enzyme activity that support the recovery of postischemic hearts. Thesaurus Terms: bioenergetics, enzyme activity, heart contraction, myocardial ischemia/hypoxia, pyruvate dehydrogenase, reperfusion cellular respiration, lactate, mitochondria laboratory rabbit, magnetic resonance imaging, stable isotope
Institution:
Fiscal Year: Department: Project Start: Project End: ICD: IRG:
Massachusetts General Hospital 55 Fruit St Boston, MA 02114 2000
Institution:
01-Dec-96 30-Nov-01 National Heart, Lung, And Blood Institute CVA
)ROJECT TITLE MRI OF CORONARY ARTERY DISEASE Grant Number: PI Name:
5R01HL38698-10 Li, Debiao
Abstract: The capabilities of Magnetic Resonance (MR) imaging of the central cardiovascular system (i.e., heart, great arteries and veins, small vessel networks in the thorax) have been advanced in recent years from primarily a definition of the anatomy of the walls of the cardiac chambers and the large vessels to the evaluation of physiologic and hemodynamic parameters using dynamic imaging and blood-signal-enhancing ("bright blood") sequences. Evaluation of the central cardiovascular system in normal and diseased states using MR imaging, however, remains limited due to nonuniformity of the blood signal in the various intracardiac/intravascular blood pools on dynamic display, difficulties with displaying the complex branching patterns of the large vasculature systems in the thorax, and present inability to provide the resolution, complex display, and motion compensation required for imaging small vessel networks, such as the coronary artery system. Our primary goal in this proposed research is to overcome these limitations by means of technical development and application.
Technical development which is planned involves work in the following areas: (1) reduction of phase errors; (2) reduc-
568
tion of in-flow artifact; (3) reduction of periodic motion artifact; and (4) improvement of image resolution and contrast. High resolution, high signal-to-noise MR imaging in the presence of physiologic cardiac and respiratory motion is sought. The application of these techniques is concerned with the following: (5) dynamic display of intracardiac blood pools; (6) static display of the major thoracic arterial systems; and (7) display of small vessel networks in the thorax, especially the coronary arteries and their branches. This clinical aspect of the project will be concerned primarily with the assessment of the capability of our techniques to produce images resembling the corresponding angiographic "gold standards". This aspect will be pursued primarily using volunteer controls and patients. The outcome of this effort would be the improved detection with imaging of the presence or absence of a large range of central cardiovascular diseases, and the improved description of the anatomic and functional aspects of the disease. Thesaurus Terms: There are no thesaurus terms on file for this project.
Fiscal Year: Department: Project Start: Project End: ICD:
IRG:
Northwestern University 303 E Chicago Ave Chicago, IL 60611 1999 Radiology 01 -Aug-93 31-Dec-00 National Heart, Lung, And Blood Institute RNM
}ROJECT TITLE MYOCARDIAL BLOOD OXYGENATION ASSESSMENT USING MRI Grant Number: PI Name:
5R01HL57484-04 Li, Debiao M.
Abstract: This proposal aims to use T2* weighted MRI to measure myocardial blood oxygenation. This is based on the notion that the deoxyhemoglobin is paramagnetic, and its presence in venous blood in the myocardium is expected to shorten T2* of the myocardium, which is the BOLD effect. Therefore, if Changes occur in the extend of blood oxygenation, either because of a reduction, or an increase in myocardial perfusion, this is expected to lead to changes in T2*. The investigations propose to measure T2* by a gradient echo MRI technique. The proposal aims to improve the MRI techniques to measure myocardial T2*. Instead of measuring images at 2TE' s they propose to use 3 TE values, which is expected to improve the accuracy of the calculated T2*. Presaturation pulses will be used to avoid the effect of possible changes in T1, which is to be expected with changes in blood flow. Arterial blood will be
presaturated by a double inversion method, as to avoid interference of an intense blood signal form the LV and the coronary arteries. The techniques will be validated in a series of canine model studies. Myocardial blood flow and oxygenation levels will be manipulated by drug intervention (dobutamine, adenosine), and by hypoxemia induced by reducing oxygen contents of the inspired gas. Then the method will be evaluated on its ability to detect regional changes in blood oxygenation. This will done in a canine model with simulated coronary artery disease. Finally, the proposed methods will be used to measure myocardial oxygenation in patients with coronary artery disease. Thesaurus Terms: blood flow, heart circulation, respira-
tory oxygenation adenosine, coronary artery, coronary disorder, disease model, dobutamine, heart pharmacology, heart rate, myocardium, oxygen consumption, oxyhemoglobin blood flow measurement, clinical research, dog, human subject, magnetic resonance imaging, positron emission tomography
Institution:
Fiscal Year: Department: Project Start: Project End: ICD: IRG:
Northwestern University 303 E Chicago Ave Chicago, IL 60611 2000 Radiology 05-Dec-96 30-Nov-01 National Heart, Lung, And Blood Institute RNM
'ROJECT TITL( QUANTITATIVE SPECT RECONSTRUCTION OF THE CHEST Grant Number: PI Name:
5R01HL51466-03 Liang, Jerome Z.
Abstract: Quantitative reconstruction of radiopharmaceuti-
cal-uptake distribution within human chest and segmentation of reconstructed uptake regions-of-interest (ROIs) using single-photon emission computed tomography (SPECT) with Tc-99m and/or TI-201 labeled agents require simultaneous compensation for photon attenuation, scatter, and depth-dependent detector response and suppression of Poisson noise. This project continues the long-term objectives of the Principal Investigator's NIH First Award: (i) to develop three-dimensional (3D) reconstruction methods which compensate efficiently for attenuation, scatter, and detector-response variation and suppress effectively noise propagation; and (ii) to investigate automatic segmentation methods for accurate quantification of reconstructed ROIs. The specific aims of this project are: (1) To develop simultaneous compensation techniques - A recursive ray-tracing
will be used to compute efficiently attenuation factors; the Klein-Nishina formula will be employed to determine accurately scatter contribution and compared with the multiple energy-window compensation techniques; a depth-dependent convolution will be adapted to compensate effectively for detector-response variation. (2) To develop reconstruction and segmentation algorithms - A maximum a posteriori probability expectation-maximization (MAP-EM) approach will be investigated; its effectiveness of noise suppression and its stability of convergence by including an edge-preserving noise-smoothing a priori constraint will be studied. (3) To implement the reconstruction and segmentation algorithms - A unified MAP-EM algorithm incorporating the compensation techniques will be coded efficiently for parallel-, fan-, and cone-beam reconstructions; the object-specific attenuation map will be reconstructed from transmission scans of a three-head SPECT system using an external radioactive line source (where the truncation of fan-beam collimation will be effectively compensated by a MAP-EM approach with a priori known attenuation coefficients); an automatic MAP-EM segmentation will be investigated to improve the attenuation map and to facilitate the quantification of reconstructed ROIs. (4) To evaluate the accuracy of reconstruction and segmentation - Criteria, such as rootmean-square error, bias-variance graph, and miss-segment ratio, will be used to quantify the reconstructed images and segmented ROIs against their simulated and experimental 3D anthropomorphic phantoms of human thorax. The proposed unified quantitative methods can reconstruct accurately the uptake distribution in a 128(3) array in less than a half hour using a HP/730 desktop computer, and segment automatically the ROIs. The methods should have significant impact on our ability to diagnose the heart and lung diseases (such as coronary artery disease and pulmonary embolism) and to probe their metabolism. Thesaurus Terms: biomedical equipment development, heart scanning, lung scanning, single photon emission computed tomography computer assisted diagnosis, diagnosis design/evaluation, diagnosis quality/standard, drug metabolism, heart disorder diagnosis, heart metabolism, noninvasive diagnosis, radiopharmacology, respiratory disorder diagnosis bioimaging/biomedical imaging, method development, statistics/biometry
Institution:
Fiscal Year: Department: Project Start: Project End: ICD: IRG:
State University New York Stony Brook Stony Brook, NY 11794 1998 Radiology 01 -Feb-96 31-Jan-00 National Heart, Lung, And Blood Institute ZRG7
569
Institution:
Fiscal Year: Department: Project Start: Project End: ICD: IRG:
Massachusetts General Hospital 55 Fruit St Boston, MA 02114 2000
Institution:
01-Dec-96 30-Nov-01 National Heart, Lung, And Blood Institute CVA
)ROJECT TITLE MRI OF CORONARY ARTERY DISEASE Grant Number: PI Name:
5R01HL38698-10 Li, Debiao
Abstract: The capabilities of Magnetic Resonance (MR) imaging of the central cardiovascular system (i.e., heart, great arteries and veins, small vessel networks in the thorax) have been advanced in recent years from primarily a definition of the anatomy of the walls of the cardiac chambers and the large vessels to the evaluation of physiologic and hemodynamic parameters using dynamic imaging and blood-signal-enhancing ("bright blood") sequences. Evaluation of the central cardiovascular system in normal and diseased states using MR imaging, however, remains limited due to nonuniformity of the blood signal in the various intracardiac/intravascular blood pools on dynamic display, difficulties with displaying the complex branching patterns of the large vasculature systems in the thorax, and present inability to provide the resolution, complex display, and motion compensation required for imaging small vessel networks, such as the coronary artery system. Our primary goal in this proposed research is to overcome these limitations by means of technical development and application.
Technical development which is planned involves work in the following areas: (1) reduction of phase errors; (2) reduc-
568
tion of in-flow artifact; (3) reduction of periodic motion artifact; and (4) improvement of image resolution and contrast. High resolution, high signal-to-noise MR imaging in the presence of physiologic cardiac and respiratory motion is sought. The application of these techniques is concerned with the following: (5) dynamic display of intracardiac blood pools; (6) static display of the major thoracic arterial systems; and (7) display of small vessel networks in the thorax, especially the coronary arteries and their branches. This clinical aspect of the project will be concerned primarily with the assessment of the capability of our techniques to produce images resembling the corresponding angiographic "gold standards". This aspect will be pursued primarily using volunteer controls and patients. The outcome of this effort would be the improved detection with imaging of the presence or absence of a large range of central cardiovascular diseases, and the improved description of the anatomic and functional aspects of the disease. Thesaurus Terms: There are no thesaurus terms on file for this project.
Fiscal Year: Department: Project Start: Project End: ICD:
IRG:
Northwestern University 303 E Chicago Ave Chicago, IL 60611 1999 Radiology 01 -Aug-93 31-Dec-00 National Heart, Lung, And Blood Institute RNM
}ROJECT TITLE MYOCARDIAL BLOOD OXYGENATION ASSESSMENT USING MRI Grant Number: PI Name:
5R01HL57484-04 Li, Debiao M.
Abstract: This proposal aims to use T2* weighted MRI to measure myocardial blood oxygenation. This is based on the notion that the deoxyhemoglobin is paramagnetic, and its presence in venous blood in the myocardium is expected to shorten T2* of the myocardium, which is the BOLD effect. Therefore, if Changes occur in the extend of blood oxygenation, either because of a reduction, or an increase in myocardial perfusion, this is expected to lead to changes in T2*. The investigations propose to measure T2* by a gradient echo MRI technique. The proposal aims to improve the MRI techniques to measure myocardial T2*. Instead of measuring images at 2TE' s they propose to use 3 TE values, which is expected to improve the accuracy of the calculated T2*. Presaturation pulses will be used to avoid the effect of possible changes in T1, which is to be expected with changes in blood flow. Arterial blood will be
presaturated by a double inversion method, as to avoid interference of an intense blood signal form the LV and the coronary arteries. The techniques will be validated in a series of canine model studies. Myocardial blood flow and oxygenation levels will be manipulated by drug intervention (dobutamine, adenosine), and by hypoxemia induced by reducing oxygen contents of the inspired gas. Then the method will be evaluated on its ability to detect regional changes in blood oxygenation. This will done in a canine model with simulated coronary artery disease. Finally, the proposed methods will be used to measure myocardial oxygenation in patients with coronary artery disease. Thesaurus Terms: blood flow, heart circulation, respira-
tory oxygenation adenosine, coronary artery, coronary disorder, disease model, dobutamine, heart pharmacology, heart rate, myocardium, oxygen consumption, oxyhemoglobin blood flow measurement, clinical research, dog, human subject, magnetic resonance imaging, positron emission tomography
Institution:
Fiscal Year: Department: Project Start: Project End: ICD: IRG:
Northwestern University 303 E Chicago Ave Chicago, IL 60611 2000 Radiology 05-Dec-96 30-Nov-01 National Heart, Lung, And Blood Institute RNM
'ROJECT TITL( QUANTITATIVE SPECT RECONSTRUCTION OF THE CHEST Grant Number: PI Name:
5R01HL51466-03 Liang, Jerome Z.
Abstract: Quantitative reconstruction of radiopharmaceuti-
cal-uptake distribution within human chest and segmentation of reconstructed uptake regions-of-interest (ROIs) using single-photon emission computed tomography (SPECT) with Tc-99m and/or TI-201 labeled agents require simultaneous compensation for photon attenuation, scatter, and depth-dependent detector response and suppression of Poisson noise. This project continues the long-term objectives of the Principal Investigator's NIH First Award: (i) to develop three-dimensional (3D) reconstruction methods which compensate efficiently for attenuation, scatter, and detector-response variation and suppress effectively noise propagation; and (ii) to investigate automatic segmentation methods for accurate quantification of reconstructed ROIs. The specific aims of this project are: (1) To develop simultaneous compensation techniques - A recursive ray-tracing
will be used to compute efficiently attenuation factors; the Klein-Nishina formula will be employed to determine accurately scatter contribution and compared with the multiple energy-window compensation techniques; a depth-dependent convolution will be adapted to compensate effectively for detector-response variation. (2) To develop reconstruction and segmentation algorithms - A maximum a posteriori probability expectation-maximization (MAP-EM) approach will be investigated; its effectiveness of noise suppression and its stability of convergence by including an edge-preserving noise-smoothing a priori constraint will be studied. (3) To implement the reconstruction and segmentation algorithms - A unified MAP-EM algorithm incorporating the compensation techniques will be coded efficiently for parallel-, fan-, and cone-beam reconstructions; the object-specific attenuation map will be reconstructed from transmission scans of a three-head SPECT system using an external radioactive line source (where the truncation of fan-beam collimation will be effectively compensated by a MAP-EM approach with a priori known attenuation coefficients); an automatic MAP-EM segmentation will be investigated to improve the attenuation map and to facilitate the quantification of reconstructed ROIs. (4) To evaluate the accuracy of reconstruction and segmentation - Criteria, such as rootmean-square error, bias-variance graph, and miss-segment ratio, will be used to quantify the reconstructed images and segmented ROIs against their simulated and experimental 3D anthropomorphic phantoms of human thorax. The proposed unified quantitative methods can reconstruct accurately the uptake distribution in a 128(3) array in less than a half hour using a HP/730 desktop computer, and segment automatically the ROIs. The methods should have significant impact on our ability to diagnose the heart and lung diseases (such as coronary artery disease and pulmonary embolism) and to probe their metabolism. Thesaurus Terms: biomedical equipment development, heart scanning, lung scanning, single photon emission computed tomography computer assisted diagnosis, diagnosis design/evaluation, diagnosis quality/standard, drug metabolism, heart disorder diagnosis, heart metabolism, noninvasive diagnosis, radiopharmacology, respiratory disorder diagnosis bioimaging/biomedical imaging, method development, statistics/biometry
Institution:
Fiscal Year: Department: Project Start: Project End: ICD: IRG:
State University New York Stony Brook Stony Brook, NY 11794 1998 Radiology 01 -Feb-96 31-Jan-00 National Heart, Lung, And Blood Institute ZRG7
569