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Because public health and innovation are no longer national issues, regulatory authorities must apply a global view to oversight.
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Research Interests: Clinical Pharmacology, Translational Research, Medicine, Translational Medicine, Clinical Practice, and 8 moreHumans, Biomedical Research, United States, Diffusion of Innovation, Drug Industry, Translational Science, Clinical Pharmacology and Therapeutics, and Pharmacology and pharmaceutical sciences
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Research Interests: Radiology, Medicine, Humans, Female, Male, and 13 moreUrinary Tract Infections, Clinical Sciences, Aged, Middle Aged, Pelvis, Adult, Urinary System, Retrospective Studies, X ray Computed Tomography, Sexually Transmitted Diseases, Acquired immunodeficiency syndrome, hydronephrosis , and Retroperitoneal space
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Research Interests: Chemistry, Biomedical Engineering, Magnetic Resonance Imaging, Magnetic Resonance Spectroscopy, Medicine, and 15 moreAdenosine, Magnesium, Animals, Male, Heart, Hemoglobin, Myocardium, Blood Flow, Coronary Circulation, Calcium Chloride, Erythrocytes, Heart Ventricles, Hemoglobins, Bicarbonates, and Coronary Vessels
Research Interests: Radiology, Chemotherapy, Radiation Therapy, Adolescent, Medicine, and 15 moreHumans, Liver, Female, Male, Hepatocellular Carcinoma, Clinical Sciences, Angiography, Middle Aged, Carcinoma, Computer Assisted Tomography, Adult, Arteriovenous Malformations, Computer, Liver neoplasms, and Colonic Neoplasms
To determine the feasibility of using hemoglobin (Hb) desaturation as an indicator of myocardial oxygenation. High-resolution gradient-echo nuclear magnetic resonance (MR) images of isolated, blood-perfused rabbit hearts were obtained at... more
To determine the feasibility of using hemoglobin (Hb) desaturation as an indicator of myocardial oxygenation. High-resolution gradient-echo nuclear magnetic resonance (MR) images of isolated, blood-perfused rabbit hearts were obtained at various blood oxygenation levels. The hearts were perfused at 37 degrees C with a Langendorff apparatus modified for nuclear MR imaging. The perfusate contained bovine red blood cells in a cardioplegic solution that eliminated motion artifacts and minimized arteriovenous oxygenation differences. Hb saturation was varied (7%-100%) randomly. Perfusion pressure was continuously monitored, and blood samples were obtained. There was a substantial correlation between image signal intensity in the myocardium and Hb saturation in the blood, believed to be due to susceptibility effects of the paramagnetic species deoxyhemoglobin. Direct and noninvasive determination of regional Hb saturation with susceptibility-dependent MR imaging may provide information regarding regional myocardial O2 content.
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The preoperative evaluation of pulmonary sequestration requires delineation of the arterial supply and venous drainage of both the sequestered segment and the neighboring lung. In this case magnetic resonance imaging was the sole modality... more
The preoperative evaluation of pulmonary sequestration requires delineation of the arterial supply and venous drainage of both the sequestered segment and the neighboring lung. In this case magnetic resonance imaging was the sole modality which demonstrated all components of the arterial and venous circulations of a sequestration and the remainder of the ipsilateral lung.
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THE NATIONAL INSTITUTES OF Health (NIH), a component of the US Department of Health and Human Services, supports more biomedical research than any other single entity in the world and plays a key role in shaping future research directions... more
THE NATIONAL INSTITUTES OF Health (NIH), a component of the US Department of Health and Human Services, supports more biomedical research than any other single entity in the world and plays a key role in shaping future research directions and in advancing the health of the biomedical research enterprise. The scope, depth, and momentum of the NIH research portfolio provides me, as director of the agency, with a unique view of the ways in which science is poised to radically transform the practice of medicine. Perhaps the most compelling prospect is the potential to practice preemptive medicine—by making use of precise molecular knowledge to detect disease before symptoms are manifest, and intervening before disease can strike. National Institutes of Health programs both stimulate and complement private-sector medical research and development. In fiscal year (FY) 2004, the $28 billion NIH budget comprised about one third of national biomedical research spending, with pharmaceutical an...
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Centrilobular emphysema (CLE) is a disease defined pathologically. Assessment of the accuracy of high resolution computed tomography (CT) in the diagnosis of centrilobular emphysema has been hampered by a lack of pathologic correlation.... more
Centrilobular emphysema (CLE) is a disease defined pathologically. Assessment of the accuracy of high resolution computed tomography (CT) in the diagnosis of centrilobular emphysema has been hampered by a lack of pathologic correlation. We applied high resolution computed tomography to 20 postmortem lung specimens fixed by a method that allows for direct one-to-one pathologic-radiologic correlation. The degree of centrilobular emphysema was assessed radiologically on a visual grading system based on nonperipheral low-attenuation areas. The lungs were then sectioned along the plane of the CT image, and the degree of centrilobular emphysema was graded pathologically by scoring against a panel of standards. A significant correlation (r = 0.91, p less than 0.005) was found between the pathologic grade and the in vitro CT score.
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To determine if fluid-fluid levels on horizontal-beam radiographs of posttraumatic knee joints always represent lipohemarthrosis. The files of 41 patients with tibial plateau fracture were reviewed retrospectively. Twelve with fluid-fluid... more
To determine if fluid-fluid levels on horizontal-beam radiographs of posttraumatic knee joints always represent lipohemarthrosis. The files of 41 patients with tibial plateau fracture were reviewed retrospectively. Twelve with fluid-fluid levels on radiographs who underwent computed tomography (CT) or magnetic resonance (MR) imaging were selected; CT attenuation and MR signal intensity patterns were used to assess fluid-fluid levels. Simulated hemarthrosis and lipohemarthrosis underwent plain radiography, CT, and MR imaging. Eight patients showed no evidence of fat in the supernatant fluid with either CT (n = 7) or CT and MR imaging (n = 1). Fluid levels resulted from blood separating into cellular elements and supernatant serum. Four patients showed evidence of lipohemarthrosis with either CT (n = 3) or MR imaging (n = 1); in one of these patients, a double fluid-fluid level could be demonstrated retrospectively on plain radiographs. Single fluid-fluid levels in posttraumatic knee ...
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Background Contrast-enhanced fast magnetic resonance (MR) images of acute, reperfused human infarcts demonstrate regions of hypoenhancement and hyperenhancement. The relations between the spatial extent and time course of these... more
Background Contrast-enhanced fast magnetic resonance (MR) images of acute, reperfused human infarcts demonstrate regions of hypoenhancement and hyperenhancement. The relations between the spatial extent and time course of these enhancement patterns to myocardial risk, infarct, and no-reflow regions have not been well characterized. Methods and Results The proximal left anterior descending coronary artery was occluded in 11 closed-chest dogs for 90 minutes followed by 2 days of reperfusion. Regional blood flow was determined by use of radioactive microspheres. The animals were studied at the 2-day time point with contrast-enhanced fast MRI (Signa 1.5 T, General Electric). Thioflavin-S was administered to demarcate no-reflow regions. The hearts were then excised, sectioned into five base-to-apex slices, stained with 2,3,5-triphenyltetrazolium chloride (TTC), and photographed under room light (for TTC) and ultraviolet light (for thioflavin). The spatial extents of thioflavin-negative, ...
Research Interests: Cardiology, Magnetic Resonance Imaging, Medicine, Dogs, Animals, and 15 moreExploration, Clinical Sciences, Myocardial Infarction, Gadolinium, Myocardium, Public health systems and services research, Time Factors, Circulation, Coronary Circulation, Microspheres, Nuclear Magnetic Resonance Imaging, Organometallic Compounds, Heterocyclic compounds, Contrast Media, and Cardiovascular medicine and haematology
BACKGROUND Measurement of regional left ventricular (LV) function is predicted on the ability to compare equivalent LV segments at different time points during the cardiac cycle. Standard techniques of short-axis acquisition in... more
BACKGROUND Measurement of regional left ventricular (LV) function is predicted on the ability to compare equivalent LV segments at different time points during the cardiac cycle. Standard techniques of short-axis acquisition in two-dimensional echocardiography, cine computed tomography, and standard magnetic resonance imaging (MRI) acquire images from a fixed plane and fail to compensate for through-plane motion. The shortening of the left ventricle along its long axis during systole results in planar images of two different levels of the ventricle, leading to error in any derived functional measurements. LV systolic long-axis motion was measured in 19 normal volunteers using MRI. METHODS AND RESULTS With a selective radio frequency (RF) tissue-tagging technique, three short-axis planes were labeled at end diastole and standard spin-echo images were acquired at end systole in the two- and four-chamber orientations. Persistence of the tags through systole allowed visualization of the...
Research Interests: Magnetic Resonance Imaging, Medicine, Humans, Movement, Technique, and 15 moreExploration, Heart, Clinical Sciences, Public health systems and services research, Circulation, Radio Waves, Reference Values, Nuclear Magnetic Resonance Imaging, Heart Ventricles, SHORT-AXIS, cardiac cycle, Diastole, systole, Cardiovascular medicine and haematology, and ventricle
Research Interests: Biomedical Engineering, Magnetic Resonance Imaging, Medicine, Dogs, Animals, and 15 moreMagnetic Resonance, Perfusion, Fluorine, Body water, Image Enhancement, Gadolinium, Myocardium, Reproducibility of Results, Coronary Circulation, Organometallic Compounds, Protons, Heterocyclic compounds, Extracellular Space, Contrast Media, and Coronary Vessels
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Research Interests: Magnetic Resonance Imaging, Microcirculation, Fluorescent Dyes and Reagents, Echocardiography, Dogs, and 17 moreComplication, Hemodynamics, Animals, The, Acute Myocardial Infarction, Contrast-Enhanced Ultrasound, Myocardial Infarction, Public health systems and services research, Time Factors, Blood Flow, Coronary Circulation, Coronary Artery Disease, Microspheres, Thiazoles, Nuclear Magnetic Resonance Imaging, Time Course, and Contrast Media
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Heart disease and stroke are the leading causes of death in the United States. Although most cardiovascular disease (CVD) is preventable, proven prevention approaches are not being ade- quately applied in clinical practice. 1 This... more
Heart disease and stroke are the leading causes of death in the United States. Although most cardiovascular disease (CVD) is preventable, proven prevention approaches are not being ade- quately applied in clinical practice. 1 This editorial discusses the major opportunities for preventing CVD in the primary care setting, focusing on 3 highly prevalent and treatable conditions: hypertension, high blood cholesterol,
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A technique is presented for rapidly and noninvasively determining aortic distensibility, by NMR measurement of pulse-wave velocity in the aorta. A cylinder of magnetization is excited along the aorta, with Fourier-velocity encoding and... more
A technique is presented for rapidly and noninvasively determining aortic distensibility, by NMR measurement of pulse-wave velocity in the aorta. A cylinder of magnetization is excited along the aorta, with Fourier-velocity encoding and readout gradients applied along the cylinder axis. Cardiac gating and data interleaving improve the effective time resolution to as high as 3 ms. Wave velocities are determined from the position of the foot of the flow wave in the velocity profiles. Evidence of helical flow distal to the aortic arch can be seen in normal subjects, while disturbed flow patterns are visible in patients with aneurysms and dissections.
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A method was devised to computationally segment and measure three-dimensional pulmonary trees in situ. Bronchi and pulmonary vessels were computationally extracted from volumetric computed tomography data based on radiopacity differences... more
A method was devised to computationally segment and measure three-dimensional pulmonary trees in situ. Bronchi and pulmonary vessels were computationally extracted from volumetric computed tomography data based on radiopacity differences between airway wall and airway lumen and between blood and parenchyma, respectively. The tree was reduced to a central axis to facilitate measurement of branch segment length and angle. Cross-sectional area was measured on a reconstructed computed tomography slice perpendicular to this central axis. The method was validated by scanning two Plexiglas phantoms and an intact lung. Reconstructed diameters in the phantoms were accurate for branches > 2 mm. In the lung airway branches between 1 and 2 mm in diameter were often unresolved when their angle of orientation with respect to the axis of the scanner was > 45 degrees. However, if a branch was resolved, its reconstructed diameter was little affected by orientation. This method represents a sig...
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High-resolution computed tomography (HRCT) as a tool for investigation of bronchovascular and pulmonary responses to various physiologic and pharmacologic stimuli is a new field of application. The potential of this method has only... more
High-resolution computed tomography (HRCT) as a tool for investigation of bronchovascular and pulmonary responses to various physiologic and pharmacologic stimuli is a new field of application. The potential of this method has only recently been investigated in animal experiments. To date, research has focused on the determination of airway responses in the context of agonist challenge such as aerosolized or i.v. histamine, isotonic saline, halothane anesthesia, and hypoxia. Likewise, physiologic HRCT has been used in the elucidation of the pulmonary circulatory response to acute hypervolemia and hypoxia. Early results indicate that significant observations can be derived from HRCT as it is the only existing method that not only detects physiologic responses but, unlike existing methods, can characterize their site and locoregional differences. In this article, the rationale for and present status of physiologic HRCT is presented.
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To reconstruct three-dimensional (3D) myocardial deformations from orthogonal sets of parallel-tagged magnetic resonance (MR) images. Displacement information in the direction normal to the undeformed tag planes was obtained at points... more
To reconstruct three-dimensional (3D) myocardial deformations from orthogonal sets of parallel-tagged magnetic resonance (MR) images. Displacement information in the direction normal to the undeformed tag planes was obtained at points along tag lines. Three independent sets of one-dimensional displacement data were used to fit an analytical series expression to describe 3D displacement as a function of deformed position. The technique was demonstrated with computer-generated models of the deformed left ventricle with data from healthy human volunteers. Model deformations were reconstructed with a 3D tracking error of less than 0.3 mm. Error between estimated and observed one-dimensional displacements along the tags in 10 human subjects was 0.00 mm +/- 0.36 (mean +/- standard deviation). Robustness to noise in the tag displacement data was demonstrated by using a Monte Carlo simulation. The combination of rapidly acquired parallel-tagged MR images and field-fitting analysis is a valu...
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To determine whether extraction of pulmonary vessels from computed tomographic (CT) images with automated segmentation improves the detection of pulmonary nodules. Simulated nodules were superimposed on normal spiral CT images. Eight... more
To determine whether extraction of pulmonary vessels from computed tomographic (CT) images with automated segmentation improves the detection of pulmonary nodules. Simulated nodules were superimposed on normal spiral CT images. Eight patients referred for CT assessment of pulmonary nodules were selected for clinical evaluation. Vessels were extracted from both the simulation and clinical study with a three dimensional seeded region-growing algorithm. Three experienced radiologists were asked to locate the nodules and assign a level of confidence to their findings. Sensitivity and proportion of false-positive results per case (FPC) were calculated. Observer performance was evaluated by alternate free-response receiver operating characteristic analysis. Extraction of vascular structures from CT scans improved sensitivity from 63% to 84% in the simulation study and from 58% to 78% in the clinical study. The proportion of FPC decreased from 52% to 24% and from 55% to 12%, respectively. ...
Research Interests: Algorithms, Radiology, Multivariate Analysis, Humans, Computer Simulation, and 14 moreFemale, Renal cell Carcinoma, Male, Confidence intervals, ROC Curve, Lung, Aged, Middle Aged, Carcinoma, Observer Variation, Adult, Sensitivity and Specificity, X ray Computed Tomography, and *Radiographic Image Enhancement
Regional deformation abnormalities in the heart wall provide a good indicator of ischemia. Myocardial tagging with magnetic resonance imaging is a new method of assessing heart wall motion during contraction. Current methods of myocardial... more
Regional deformation abnormalities in the heart wall provide a good indicator of ischemia. Myocardial tagging with magnetic resonance imaging is a new method of assessing heart wall motion during contraction. Current methods of myocardial tagging either do not provide two-dimensional information or lack a coordinate system well adapted to the morphology of the heart. In this article, the authors describe a new tagging method that provides a true polar coordinate system, with both radial and angular dimensions. This is accomplished with use of a section-selective version of spatially modulated magnetization resulting in striped tags (STAGs). These STAG planes are placed in the myocardium in a star pattern so that they intersect on the long axis of the heart and stripes appear through the width of the heart wall. In the short-axis view during contraction, rotation around the long axis yields angular information such as shear and twist, while separation of the stripes within the myocar...
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Changes in airway resistance are reported to account for only a portion of changes in total lung resistance. The fraction of total lung resistance caused by airway resistance is difficult to quantify in vivo. High-resolution computed... more
Changes in airway resistance are reported to account for only a portion of changes in total lung resistance. The fraction of total lung resistance caused by airway resistance is difficult to quantify in vivo. High-resolution computed tomography (HRCT) has potential application for directly measuring changes in airway size in vivo. In the present investigation, we studied five anesthetized mongrel dogs using HRCT to locate and measure changes in airway area after aerosol histamine challenge in the absence and presence of deep inspiration. We also related changes in total lung resistance to changes in airway area. We found that in all dogs after histamine aerosol challenge, airway area decreased (range, 23 +/- 7 to 67 +/- 5%, mean +/- SEM), and total lung resistance increased (range, 191 to 378%). After deep inspiration (equal to three times tidal volume), four of the five dogs showed further significant decreases in airway area (range, 13 +/- 6 to 71 +/- 8%), whereas all five dogs sh...
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Over a 31-month period, 100 patients with malignant hepatic tumors were preoperatively evaluated with three imaging techniques. The results of intravenously enhanced computed tomography (CT) scan, selective hepatic arterial contrast CT,... more
Over a 31-month period, 100 patients with malignant hepatic tumors were preoperatively evaluated with three imaging techniques. The results of intravenously enhanced computed tomography (CT) scan, selective hepatic arterial contrast CT, and magnetic resonance imaging (MRI) were compared with operative findings. A total of 227 lesions were identified, with the sensitivity for tumor detection being arteriographically enhanced CT 94% (p less than 0.01), MRI 70%, and CT 66%. This advantage for arteriographically enhanced CT was most marked for lesions less than 1 cm in diameter (82% versus 20% for MRI and 5% for CT; p less than 0.01). Arteriographically enhanced CT was also most sensitive in assessing tumor margins. MRI was clearly superior to arteriographically enhanced CT or CT in detecting vascular involvement (85% versus 30% and 8%, respectively; p less than 0.01). No imaging technique was sensitive in determining extrahepatic involvement. Arteriographically enhanced CT was also best at predicting the operative procedure. The combination of arteriographically enhanced CT and MRI was the best predictor of true disease. We conclude that both arteriographically enhanced CT and MRI should be used for preoperative assessment of hepatic malignancies.
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Patients with adenocarcinoma of the prostate confined to the gland (stage B) are candidates for a potentially curative surgical procedure (radical retropubic prostatec- tomy). However, patients with adenocarcinoma that penetrates the... more
Patients with adenocarcinoma of the prostate confined to the gland (stage B) are candidates for a potentially curative surgical procedure (radical retropubic prostatec- tomy). However, patients with adenocarcinoma that penetrates the capsule or invades the seminal vesicles (stage C) are no longer considered good candidates for surgical cure of their disease. The purpose of this study was to compare the
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Over a 31-month period, 100 patients with malignant hepatic tumors were preoperatively evaluated with three imaging techniques. The results of intravenously enhanced computed tomography (CT) scan, selective hepatic arterial contrast CT,... more
Over a 31-month period, 100 patients with malignant hepatic tumors were preoperatively evaluated with three imaging techniques. The results of intravenously enhanced computed tomography (CT) scan, selective hepatic arterial contrast CT, and magnetic resonance imaging (MRI) were compared with operative findings. A total of 227 lesions were identified, with the sensitivity for tumor detection being arteriographically enhanced CT 94% (p less than 0.01), MRI 70%, and CT 66%. This advantage for arteriographically enhanced CT was most marked for lesions less than 1 cm in diameter (82% versus 20% for MRI and 5% for CT; p less than 0.01). Arteriographically enhanced CT was also most sensitive in assessing tumor margins. MRI was clearly superior to arteriographically enhanced CT or CT in detecting vascular involvement (85% versus 30% and 8%, respectively; p less than 0.01). No imaging technique was sensitive in determining extrahepatic involvement. Arteriographically enhanced CT was also best at predicting the operative procedure. The combination of arteriographically enhanced CT and MRI was the best predictor of true disease. We conclude that both arteriographically enhanced CT and MRI should be used for preoperative assessment of hepatic malignancies.
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A series of patients with documented predominantly interstitial pulmonary disease was examined by routine and high-resolution computed tomography (CT) and compared to a series of twenty-one normals. Inspiratory-expiratory lung density... more
A series of patients with documented predominantly interstitial pulmonary disease was examined by routine and high-resolution computed tomography (CT) and compared to a series of twenty-one normals. Inspiratory-expiratory lung density measurements were also obtained at predetermined levels. Several basic CT signs of interstitial disease were identified: finely irregular and thickened pleural surfaces; irregular vascular shadows; thickened and irregular bronchial walls making bronchi visible over a longer portion of their course in the lungs; reticular network of lines with three patterns easily distinguishable by the size of their reticular element; hazy patches of increased density of various sizes distinguishable from alveolar filling processes by the fact that vessels can still be visualized through them; and nodules of various sizes. Micronodules are often associated with a small or medium-size reticular network and in most cases seem to represent points of confluence rather than isolated nodules. The hematogenous origin of some nodules can be specifically suggested when feeding vessels are demonstrated on thin-section scans. Nodules associated with a large network of thickened septa are suggestive of lymphangitic carcinomatosis. Inspiratory-expiratory density gradients can be more useful in confirming the diagnosis of interstitial disease than absolute measurements.
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ABSTRACT This week an international panel announces a list of 14 Grand Challenges in Global Health, and scientists throughout the world will be invited to submit grant proposals to pursue them with funds provided by the Bill and Melinda... more
ABSTRACT This week an international panel announces a list of 14 Grand Challenges in Global Health, and scientists throughout the world will be invited to submit grant proposals to pursue them with funds provided by the Bill and Melinda Gates Foundation. We describe the characteristics of these challenges and the process by which they were formulated and selected after receiving over 1000 responses to a "call for ideas" from the scientific community.
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Research Interests: Biomedical Engineering, Magnetic Resonance Imaging, Fourier Analysis, Humans, Computer Simulation, and 16 moreBlood, Structural equation models, Heart rate, Heart, Magnetics, Theoretical Models, Image Enhancement, Myocardial Infarction, Gadolinium, Myocardium, Magnetic, Coronary Circulation, Radio Waves, Organometallic Compounds, Heterocyclic compounds, and Contrast Media
Research Interests: Biomedical Engineering, Magnetic Resonance Imaging, Dogs, Animals, Magnetic Resonance, and 13 moreFluorine, Body water, Image Enhancement, Gadolinium, Myocardium, Time Factors, Reproducibility of Results, Coronary Circulation, Organometallic Compounds, Protons, Heterocyclic compounds, Extracellular Space, and Contrast Media
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This study examined whether the correlation of systolic wall thickening (%WT) by nuclear magnetic resonance (NMR) imaging with wall thickening by sonomicrometry (SM) is improved by using a three-dimensional volume element model of the... more
This study examined whether the correlation of systolic wall thickening (%WT) by nuclear magnetic resonance (NMR) imaging with wall thickening by sonomicrometry (SM) is improved by using a three-dimensional volume element model of the left ventricular wall. Left ventricular wall obliquity with respect to the imaging plane causes overestimation of wall thickness by planar imaging techniques. Wall thickness perpendicular to the endocardial surface can be accurately calculated by three-dimensional reconstruction of left ventricular wall segments. Sonomicrometers were placed transmurally in 11 dogs (left anterior descending artery territory) with an imaging marker, visible on NMR imaging, sewn to the epicardial crystal. Two adjacent NMR short-axis image planes were radially segmented by four perpendicular spin-saturated planes (tags), dividing the myocardium into eight volume elements, one of which contained the sonomicrometer crystal pair. Left ventricular thickness and thickening were calculated by four methods: 1) linear = distance between epicardium and endocardium at midpoint in the segment with the sonomicrometer; 2) planar = area of that segment divided by the mean of the endocardial and epicardial arc lengths; 3) biplanar = average of wall thicknesses calculated by the planar method from the segment with sonomicrometers and the corresponding segment located in the adjacent short-axis imaging plane; and 4) three-dimensional = volume of the element with the sonomicrometers divided by the mean of the endocardial and epicardial surface areas. Regressions for all methods using pooled data from control periods and during ischemia: Linear %WT = 0.59 + 1.31 SM%WT (r = 0.71, SEE = 0.28, p < 0.0002) Planar %WT = 1.43 + 1.62 SM%WT (r = 0.87, SEE = 0.19, p < 0.0001) Biplanar %WT = 2.09 + 1.46 SM%WT (r = 0.90, SEE = 0.15, p < 0.0001) Three-dimensional %WT = 0.19 + 1.49 SM%WT (r = 0.95, SEE = 0.10, p < 0.0001) Nuclear magnetic resonance imaging with tissue tagging allows accurate noninvasive assessment of systolic wall thickening. The three-dimensional volume element approach, by accounting for obliquity between the image plane and the left ventricular wall, provides the strongest correlation between NMR imaging and percent systolic wall thickening by sonomicrometer crystals.
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Research Interests: Magnetic Resonance Imaging, Microcirculation, Fluorescent Dyes and Reagents, Echocardiography, Dogs, and 17 moreComplication, Hemodynamics, Animals, The, Acute Myocardial Infarction, Contrast-Enhanced Ultrasound, Myocardial Infarction, Public health systems and services research, Time Factors, Blood Flow, Coronary Circulation, Coronary Artery Disease, Microspheres, Thiazoles, Nuclear Magnetic Resonance Imaging, Time Course, and Contrast Media
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High resolution CT of a fixed-inflated air-dried lung was obtained from a patient with rounded atelectasis. The dense periphery of the mass was shown to correspond to an invagination of the pleura, and the central lucency to slightly... more
High resolution CT of a fixed-inflated air-dried lung was obtained from a patient with rounded atelectasis. The dense periphery of the mass was shown to correspond to an invagination of the pleura, and the central lucency to slightly aerated atelectatic lung parenchyma.
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Fifty hepatic hemangiomas in 38 patients were evaluated by CT using sequential scanning following bolus injection. Lesions were assessed for the following CT features: (a) low density lesion on unenhanced scan; (b) early peripheral... more
Fifty hepatic hemangiomas in 38 patients were evaluated by CT using sequential scanning following bolus injection. Lesions were assessed for the following CT features: (a) low density lesion on unenhanced scan; (b) early peripheral contrast enhancement; (c) progressive opacification from the periphery to the center; (d) a delay of at least 3 min before total opacification; and (e) eventual isodense appearance with or without unopacified cleft. The criteria for diagnosis of hepatic hemangioma were (d) and (e) plus at least two of the remaining three features. Forty-eight lesions were identified by CT; 38 displayed all five features, five lesions were missing one feature, and five lesions did not meet the criteria for diagnosis. Larger lesions required a significantly longer period to opacify (p less than 0.05). The positive predictive value of CT in the diagnosis of hemangioma was 100%.
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We report a case of a 35-year-old woman with a mucinous biliary cystadenoma of the liver. The patient presented with the acute onset of upper abdominal pain and jaundice, symptoms caused by bleeding into the cystadenoma. Findings of a... more
We report a case of a 35-year-old woman with a mucinous biliary cystadenoma of the liver. The patient presented with the acute onset of upper abdominal pain and jaundice, symptoms caused by bleeding into the cystadenoma. Findings of a variety of imaging modalities including ultrasound, CT angiography, MR imaging, and endoscopic retrograde cholangiopancreatography are correlated and verified by pathological studies performed on the material obtained surgically.
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ABSTRACT
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We report the application of myocardial tagging by MR to define tissue planes and differentiate contractile from noncontractile tissue in a neonate with congenital cardiac rhabdomyoma. Using custom-written pulse programming software, six... more
We report the application of myocardial tagging by MR to define tissue planes and differentiate contractile from noncontractile tissue in a neonate with congenital cardiac rhabdomyoma. Using custom-written pulse programming software, six 2 mm thick radiofrequency (RF) slice-selective presaturation pulses (tags) were used to label the chest wall and myocardium in a star pattern in diastole, approximately 60 ms before the R-wave gating trigger. This method successfully delineated the myocardium from noncontractile tumor, providing information that influenced clinical management. This RF tagging technique allowed us to confirm the exact intramyocardial location of a congenital cardiac tumor.
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More accurate noninvasive estimation of prostate size is important in therapeutic trials for benign prostatic hyperplasia. The accuracy of MRI and transrectal ultrasound (TRUS) in assessing prostate weight was evaluated in 48 patients who... more
More accurate noninvasive estimation of prostate size is important in therapeutic trials for benign prostatic hyperplasia. The accuracy of MRI and transrectal ultrasound (TRUS) in assessing prostate weight was evaluated in 48 patients who underwent radical prostatectomy for stage A or B cancer. The volume derived from the wet weight of the freshly excised specimen was used as a reference. We compared that volume with volume estimates derived from the three-axis linear dimension measurement by MRI and TRUS using a tissue density of 1.05 g/cc and the standard formula for an ellipsoid object. Prostate and seminal vesicle volumes were also computed by contouring T2-weighted 5 mm thick contiguous MR images using a semiautomatic edge detection program and pixel summation. Three-axis volume MRI method versus volume from wet weight has slightly less scatter than TRUS three-axis method (r = 0.85 vs r = 0.81). Contoured MR volume method has the least scatter r = 0.93, statistically better than the linear axis method. Contoured MRI volumetric analysis appears superior to linear MRI or TRUS methods in estimating true prostate volume.
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Quantitative computed tomographic (CT) measurement of pulmonary nodules has not been widely applied despite favorable reports. Its usefulness has been questioned by some investigators. A series of experiments on six different scanners was... more
Quantitative computed tomographic (CT) measurement of pulmonary nodules has not been widely applied despite favorable reports. Its usefulness has been questioned by some investigators. A series of experiments on six different scanners was undertaken to study the factors that affect the applicability of this technique. The type of reconstruction algorithm, the design of the CT system, the true slice thickness, and the beam kilovoltage were the most important factors identified. These factors can produce large variations in the CT numbers of pulmonary nodules, preventing direct comparison of results from scanner to scanner. Before undertaking studies of pulmonary nodules, the effect of these variables in each individual scanner should be evaluated. Despite the current lack of standardization, reliable CT number measurements using a specific kilovoltage and slice thickness should be possible on every modern scanner provided it is positionally uniform and gives a linear response to varying densities. We propose that the CT number above which a pulmonary nodule can be considered benign should be the representative CT number of a 1 cm diameter syringe filled with a hydrous calcium chloride solution of 40 mg/ml of water and scanned in air. A better understanding of the physics of lung nodule densitometry is necessary for the proper application of this technique in the management of patients with solitary pulmonary nodules.
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... Noninvasive Assessment of Myocardial Stunning from Short-Term Coronary Occlusion Using Tagged Magnetic Resonance Imaging Dara L. Kraitchman,l Hanns B. Hillenbrand,' lzlem Oznur,' Joao AC Lima,lI2 Elliot R. McVeigh,l Elias A.... more
... Noninvasive Assessment of Myocardial Stunning from Short-Term Coronary Occlusion Using Tagged Magnetic Resonance Imaging Dara L. Kraitchman,l Hanns B. Hillenbrand,' lzlem Oznur,' Joao AC Lima,lI2 Elliot R. McVeigh,l Elias A. Zerhouni,l and David A. Bluemkel ...
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There is a continuing need for a greater sensitivity of magnetic resonance imaging (MRI) in the diagnosis of avascular necrosis (AVN). Previously, it was demonstrated that a dynamic MRI method, with gadolinium-DTPA (Gd-DTPA) enhancement,... more
There is a continuing need for a greater sensitivity of magnetic resonance imaging (MRI) in the diagnosis of avascular necrosis (AVN). Previously, it was demonstrated that a dynamic MRI method, with gadolinium-DTPA (Gd-DTPA) enhancement, can detect acute changes not seen on spin-echo images after arterial occlusion in a dog model. Because venous congestion appears to be a more directly relevant hemodynamic abnormality in a majority of clinical AVN cases, the authors extended the dynamic MRI technique to study changes in venous occlusion. Dynamic MRI of the proximal femur was performed in five adult dogs before and after unilateral ligation of common iliac and lateral circumflex veins. Sixteen sequential gradient-recalled pulse sequence (GRASS) images (time resolution = 45 mseconds, echo time = 9 mseconds, flip angle = 65 degrees) were obtained immediately after a bolus intravenous injection of 0.2 mmol/kg of Gd-DTPA. Simultaneous measurements of regional blood flow were made using the radioactive microsphere method. After venous ligation, there was a 25% to 45% decrease in the degree of enhancement compared with preligation values on the ligated side. The decrease in cumulative enhancement (integrated over the entire time course) was statistically significant. The occlusion technique was verified by confirming a statistically significant decrease in blood flow determined by the microsphere method. Dynamic Gd-DTPA-enhanced fast MRI technique can detect acute changes in bone marrow perfusion due to venous occlusion. This technique may have applications in the early detection of nontraumatic AVN.
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Research Interests:
... Michael A. Guttman, Elias A. Zerhouni, and Elliot R. McVeigh Johns Hopkins University Analysis of Cardiac Function from MR Images ... 2 Short-axis and long-axis image geome-try. Colored lines indicate radial, circum-ferential, and... more
... Michael A. Guttman, Elias A. Zerhouni, and Elliot R. McVeigh Johns Hopkins University Analysis of Cardiac Function from MR Images ... 2 Short-axis and long-axis image geome-try. Colored lines indicate radial, circum-ferential, and longitudinal directions. ...
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Research Interests:
Page 1. Eur. Radiol. 4, 243-253 (1994) © Springer-Verlag 1994 European Radiology Gastrointestinal radiology Evaluation of the pancreas by MRI Yoshimasa Imanishi 1. , Vivian Y. Hou 2, Alexandra C. Chako 2, Clare MC Tempany ...
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The clinical, radiographic, and pathologic features of 17 patients with documented peripheral primitive neuroectodermal tumor (PNET) were evaluated in a retrospective study. The age at diagnosis ranged from 9 months to 46 years (median,... more
The clinical, radiographic, and pathologic features of 17 patients with documented peripheral primitive neuroectodermal tumor (PNET) were evaluated in a retrospective study. The age at diagnosis ranged from 9 months to 46 years (median, 15.8 years). Primary sites of involvement were the abdomen (n = 8), extremities (n = 5), chest (n = 1), temporal bone (n = 1), maxilla (n = 1), and diploe (n = 1). At the time of diagnosis, six patients had distant metastases; all of these patients died, with an average survival of 8.8 months. Radiologic workup included standard radiographs, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and bone scintigraphy. The radiographic appearance of these tumors was not specific for differentiation of PNETs from other types of bone and soft tissue tumors. The typical appearance resembled large non-calcified, soft tissue masses with cystic or necrotic areas. Heterogeneous enhancement with intravenous contrast agents was evident on CT, as was an intermediate signal intensity on Tl-weighted images and hyperintense signal on T2-weighted and STIR sequences. After gadolinium administration, variable enhancement was seen. MRI and CT were useful in predicting resectability, in detecting distant metastases, and in the evaluation of response to treatment. Surgery was performed in all cases, either for definitive diagnosis or for therapy. All patients received combined chemotherapy and radiotherapy and five patients received autologous bone marrow transplantation. Clinical follow-up was obtained over a mean period of 3 years (range 1 day to 6 years). Prognosis was poor with a median survival of 3.4 years. Our experience in 17 patients with peripheral neuroectodermal tumors indicates that although their radiologic features are non-specific, they should be included in differential diagnosis of soft tissue tumors of aggressive behavior, especially in a young age group. CT and MRI are useful in delineating the extent and resectability of tumor and in monotoring treatment.
Research Interests: Computed Tomography, Magnetic Resonance Imaging, Ultrasound, Adolescent, Aggressive Behavior, and 19 moreHumans, Child, Female, Male, Infant, Follow-up studies, Differential Diagnosis, Clinical Sciences, Middle Aged, Combination chemotherapy, Adult, Survival Rate, Soft Tissue, Temporal Bone, Soft Tissue Tumor, X ray Computed Tomography, Retrospective Study, Bone Scintigraphy, and Age Groups
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Research Interests:
Paragangliomas occurring in the liver are rare. We report a patient with a history of nonfunctional paragangliomas in the head and neck who developed liver metastases years later. We discuss findings on cross-sectional imaging modalities,... more
Paragangliomas occurring in the liver are rare. We report a patient with a history of nonfunctional paragangliomas in the head and neck who developed liver metastases years later. We discuss findings on cross-sectional imaging modalities, including magnetic resonance imaging (MRI), which demonstrate the hypervascular nature of the liver masses.
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Research Interests:
Research Interests: Magnetic Resonance Imaging, Microcirculation, Humans, Left Ventricular Assist Device, Female, and 15 moreMale, Follow-up studies, Acute Myocardial Infarction, Contrast-Enhanced Ultrasound, Clinical Sciences, Aged, Middle Aged, Myocardial Infarction, Coronary heart disease, Public health systems and services research, Adverse Event, Prognosis, Circulation, Infarct Size, and Heart Ventricles
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Myocardial reperfusion is pivotal to the prognosis of patients with acute myocardial infarction. In these patients, coronary flow is generally assessed by angiography and tissue perfusion by tracer scintigraphy. This study was designed to... more
Myocardial reperfusion is pivotal to the prognosis of patients with acute myocardial infarction. In these patients, coronary flow is generally assessed by angiography and tissue perfusion by tracer scintigraphy. This study was designed to examine whether magnetic resonance imaging (MRI) provides information on myocardial perfusion and damage beyond that supplied by angiography and thallium scintigraphy after acute myocardial infarction. Twenty-two patients with recent myocardial infarction had ECG, echocardiography, coronary angiography, and fast contrast-enhanced MRI. Twelve patients also had exercise thallium scintigraphy. Time-intensity curves obtained from infarcted and noninfarcted regions were correlated with coronary anatomy and left ventricular function. Two perfusion patterns were observed in infarcted regions by comparison with the normal myocardial pattern. All patients but 1 had persistent myocardial hyperenhancement within the infarcted region up to 10 minutes after contrast. In 10 patients, this hyperenhanced region surrounded a subendocardial area of decreased signal at the center of the infarcted region associated with coronary occlusion at angiography, Q waves on ECG, and greater regional dysfunction by echocardiography. Moreover, the extent and location of the MRI abnormalities correlated well with the extent and location of the fixed single-photon emission computed tomography thallium defects. Large human infarcts, associated with prolonged obstruction of the infarct-related artery, are characterized by central dark zones surrounded by hyperenhanced regions on MRI. Conversely, reperfused infarcts with less regional dysfunction have uniform signal hyperenhancement. The MRI hyperenhanced segment correlates well with the fixed scintigraphic defect in patients with acute myocardial infarction.
Research Interests: Magnetic Resonance Imaging, Electrocardiography, Echocardiography, Humans, Female, and 16 moreMale, Heart, Creatine Kinase, Clinical Sciences, Middle Aged, Coronary Angiography, Single Photon Emission Computed Tomography, Myocardial Infarction, Gadolinium, Myocardium, Public health systems and services research, Circulation, Organometallic Compounds, Heterocyclic compounds, Contrast Media, and Thrombolytic Therapy
High-resolution computed tomography was used to directly determine the short-term effects of intravascular volume expansion on airway caliber. The change in airway cross-sectional area caused by intravascular volume expansion (30 ml/kg,... more
High-resolution computed tomography was used to directly determine the short-term effects of intravascular volume expansion on airway caliber. The change in airway cross-sectional area caused by intravascular volume expansion (30 ml/kg, Ringer's lactate) was studied in six anesthetized mini-pigs within 5 min. Twenty-five of 27 large airways (diameter, 2.01 to 5.0 mm) demonstrated decreased internal cross-sectional area (10.56 +/- 1.26 vs 8.66 +/- 1.03 mm2, p < 0.001). Twenty of 24 small airways (diameter, 0.75 to 2.0 mm) showed decreased internal cross-sectional area (1.82 +/- 0.16 vs 1.44 +/- 0.16 mm2, p < 0.001). These changes were rapidly (< 6 min) reversed by intravascular volume reduction. The external airway cross-sectional area did not change. These data suggest rapid, reversible bronchial mucosal vascular engorgement as a cause of increased airway resistance in heart failure.
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Research Interests:
Page 1. DOI 10.1378/chest.106.3.920 1994;106;920-924 Chest Mitzner Robert H. Brown,Christian Herold, Elias A. Zerhouni and Wayne ... Robert H. Brown, MD, MPH; ChristianHerold, MD; Elias A. Zerhouni, MD; and Wayne Mitzner, Ph.D. ...
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Research Interests:
Research Interests:
Magnetic resonance imaging (MRI) may be an excellent tool to define atherosclerotic plaque composition, but surface MRI (SMRI) suffers from a low signal-to-noise ratio and low resolution of arterial images. Intravascular MRI (IVMRI)... more
Magnetic resonance imaging (MRI) may be an excellent tool to define atherosclerotic plaque composition, but surface MRI (SMRI) suffers from a low signal-to-noise ratio and low resolution of arterial images. Intravascular MRI (IVMRI) represents a potential solution for acquiring high-quality in vivo images of atherosclerotic plaques. Isolated segments of 11 thoracic human aortas obtained at autopsy were imaged by IVMRI using an intravascular receiver catheter coil designed and built at our institution. Images obtained by IVMRI were compared with corresponding images obtained by SMRI and with histopathological aortic cross sections. The intensity of intimal thickness and plaque components was graded by IVMRI and histopathology using a score of 1 for mild, 2 for moderate, and 3 for severe intensity. IVMRI had an agreement of 75% with histopathology in fibrous cap grading (37.5% expected, kappa = 0.60, P < 0.001) and of 74% in necrotic core grading (39% expected, kappa = 0.57, P < 0.001). Intraplaque calcification was correctly graded by IVMRI in six of the eight plaques in which histopathology recognized calcium. The analysis of intimal thickness showed 80% agreement between IVMRI and histopathology (52% expected, kappa = 0.59, P < 0.001). IVMRI image features were similar to those of SMRI. In addition, IVMRI accurately determined atherosclerotic plaque size in comparison with histopathology and SMRI (slope = 1.25 cm2, r = 0.99, P < 0.001 for luminal area by IVMRI vs histopathology; slope = 0.97 cm2, r = 0.996, P < 0.001 for luminal area by IVMRI vs SMRI). IVMRI has the potential to provide important prognostic information in patients with atherosclerosis because of its ability to accurately assess both plaque composition and size.
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Volatile anesthetics are effective at preventing and reversing bronchospasm, but their effects on baseline airway tone are controversial. While tantalum bronchography has been used in the past to measure one-dimensional airway diameter... more
Volatile anesthetics are effective at preventing and reversing bronchospasm, but their effects on baseline airway tone are controversial. While tantalum bronchography has been used in the past to measure one-dimensional airway diameter changes, this method has inherent problems associated with the irritant effects of tantalum. Until recently, no other direct noninvasive in vivo method to assess airway caliber was available. The present investigation assesses the effects of the inhalation anesthetic halothane on individual unstimulated airways in vivo. Ten studies were performed in seven dogs. All dogs were initially anesthetized with 15 mg/kg thiopental followed by a 10-mg.kg-1 x h-1 maintenance dose. Following tracheal intubation the lungs were mechanically ventilated (15 ml/kg, 15 beats/min). The dogs subsequently received increasing doses of halothane (range 0.5-1.5%). On a separate day, the dogs were pretreated with atropine (0.2 mg/kg) and the study was repeated. Fifty sequential high-resolution computed tomography scans were obtained using a 1-s scan time, 137 kVp, 220 mA, 2-mm slice thickness, and 1-mm table feed. Airway areas ranging in size from 3 to 22 mm in diameter were measured and analyzed by one way analysis of variance and Bonferroni pair-wise comparisons of means. Halothane in concentrations of 0.5%, 1.0%, and 1.5% showed significant dose-dependent dilation of the airways (percent increase from control) that averaged 90 +/- 19% (mean +/- SEM), 128 +/- 20%, and 182 +/- 27%, respectively (P = .017). Atropine pretreatment alone significantly dilated the airways to 151 +/- 25% (P = .002) of their baseline value. Halothane caused no further airway dilation in atropine pretreated dogs. Halothane dilates baseline airways by blocking baseline vagal tone. Since baseline airway tone, airway wall thickness, and initial airway diameter are major determinants of airway reactivity, the observed dilation by halothane may be one of the mechanisms by which inhalational anesthetics decrease airway reactivity.
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Research Interests:
Computed tomography (CT) with thin sections (2-5 mm) was used to assess tissue density in 91 apparently noncalcified pulmonary nodules in 88 patients. The study included 45 primary lung malignancies and 13 metastases proven by subsequent... more
Computed tomography (CT) with thin sections (2-5 mm) was used to assess tissue density in 91 apparently noncalcified pulmonary nodules in 88 patients. The study included 45 primary lung malignancies and 13 metastases proven by subsequent lung biopsy or thoracotomy. There were 33 benign lesions of which 13 were biopsy proven. The other 20 nodules were presumed benign on the basis of serial radiography showing no growth. A representative CT number based on the 32 most dense voxels was calculated for each lesion. For the primary malignancies, the mean representative CT number was 92 H, with a standard deviation of 18 H. The highest representative CT number for any malignant lesion was 147 H. Of the 33 benign lesions, 20 had a representative CT number of 164 H or greater. It is presumed that nodules with representative CT numbers of 164 H are benign, and that diffuse calcification likely accounts for the higher CT number of some benign lesions. CT has proven to be more objective and more sensitive than standard tomography in assessing the density of pulmonary nodules.
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Fluid collections are an important component of severe pancreatitis because they may produce a detectable mass and may be responsible for prolongation of fever and pain. Among 59 cases of clinically verified pancreatitis, 32 were shown by... more
Fluid collections are an important component of severe pancreatitis because they may produce a detectable mass and may be responsible for prolongation of fever and pain. Among 59 cases of clinically verified pancreatitis, 32 were shown by CT to be complicated by pancreatic and/or extrapancreatic fluid collections. Pancreatic fluid collections, diagnosed in 16 patients, were typically on the anterior or anterolateral surface of the gland and were covered only by a thin layer of fibrous connective tissue. Extrapancreatic fluid collections were detected in the lesser sac (19 cases), anterior pararenal space (15), posterior pararenal space (six), in or around the left lobe of the liver (five), in the spleen (three), and in the mediastinum (one). The potential undesirable consequences of escape of pancreatic juice are necrosis, abscess formation, or prolonged inflammation of the peripancreatic tissues. Relative preservation of pancreatic integrity as observed by CT was regularly found in patients with large extrapancreatic fluid collections, suggesting that escape of pancreatic juice produces a beneficial decompression of the pancreatic duct system.
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Research Interests:
Because of the wide variety of types of silicone breast implants, modifications, and surgical procedures, a number of normal variants and potentially misleading appearances can be encountered on MR images of breast implants. Familiarity... more
Because of the wide variety of types of silicone breast implants, modifications, and surgical procedures, a number of normal variants and potentially misleading appearances can be encountered on MR images of breast implants. Familiarity with these findings is essential to proper interpretation of these images. The purpose of this essay is to illustrate the overlap in appearances of MR images in different clinical scenarios. When confusing findings are present, confirmation of the surgical history can usually clarify the matter.
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Comparison is made between the reliability of two imaging methods (ultrasound and magnetic resonance imaging) to measure changes in the size of the liver in patients undergoing treatment for Gaucher disease. The reliability of either... more
Comparison is made between the reliability of two imaging methods (ultrasound and magnetic resonance imaging) to measure changes in the size of the liver in patients undergoing treatment for Gaucher disease. The reliability of either modality in estimating liver size is comparable, as is the reliability of demonstrating changes in the size of the liver with time. The precision of the two measurements is roughly the same.