Advances in imaging for assessment of ischemic heart disease

Cardiac imaging techniques continue to develop for the noninvasive detection and evaluation of patients with coronary artery disease. These techniques include single photon and positron emission tomography along with computed tomography and magnetic resonance imaging. The new myocardial perfusion tracers 99mTc-hexakis-2-methoxyisobutyl-isonitrile and 99mTc-teboroxime have recently come into general use for these purposes, and their role alongside that of more traditional agents is currently being defined using new imaging protocols and instrumentation. 99mTc-hexakis-2-methoxyisobutyl-isonitrile has also been documented as an important research tool for evaluating both at-risk myocardium and the degree of subsequent myocardial salvage following reperfusion therapies for acute myocardial infarction. Antimyosin antibody imaging is another emerging approach in the evaluation of patients with acute myocardial infarction. Metabolic imaging with 18F-fluoro-2-deoxyglucose using positron emission tomography to detect myocardial segments with compromised blood flow but preserved glucose metabolism is currently the best noninvasive method of identifying viable myocardium in patients with left ventricular dysfunction who may benefit from revascularization. Insights from these studies have led to development of the current 201Tl stress-rest reinjection protocols for viability evaluation using single photon emission computed tomography. Positron emission tomography, in combination with blood flow tracers using kinetic modeling, provides accurate estimates of coronary blood flow and flow reserve. The use of these new imaging techniques will allow increasingly accurate evaluation of patients with suspected and proven coronary artery disease in the future.     

The contribution of positron emission tomography to the study of ischemic heart failure

Cardiac imaging with positron emission tomography offers unrivaled sensitivity and specificity to probe cardiovascular physiology in health and disease. The use of positron emission tomography to noninvasively measure regional myocardial blood flow and assess myocardial viability in patients with ventricular dysfunction and coronary artery disease has contributed greatly to our understanding of the pathophysiology of ischemic heart failure. The advances and the need for further studies to establish both the natural history of such ventricular dysfunction and the role of coronary revascularization are discussed.     

Diagnosis of Double‐Chambered Left Ventricle Using Advanced Cardiovascular Imaging

Double‐chambered ventricle is a rare congenital cardiac abnormality, most commonly affecting the right ventricle. Here, we report a case of an incidental diagnosis of this condition affecting the left ventricle (LV), which is found much less frequently, and the use of contrast echocardiography in its evaluation. The addition of computed tomography (CT), highlighting the blood supply of both chambers by the left anterior descending (LAD) artery allowed us to confirm the diagnosis.     

The role of noninvasive methods of investigation in diagnosis of atherosclerosis

Visualization of the myocardium with the use of various high technologies gains more and more important significance in diseases of cardiovascular system. Large value for investigations of the heart and blood vessels have acquired methods of echocardiography, magnetic resonance tomography, spiral computed tomography, as well as large spectrum of methods of nuclear cardiology. Contemporary value of instrumental methods of investigation for diagnostics of atherosclerosis is discussed in this paper and diagnostic possibilities of various techniques for assessment of the state of myocardium, pathological changes of vascular wall and for visualization of atherosclerotic plaques (AP) are presented. Advantages and drawbacks of methods, their complex application for objective analysis of changes in AP and their clinical significance are considered. Special accent is made on early diagnosis of pathological derangements, because full value information allows making adequate decisions about subsequent curative measures. It is shown that detection and evaluation of early signs of atherosclerosis appears to be determining factor of efficacy of treatment. In patients without obvious symptoms of ischemic heart disease or at the background of postinfarction cardiosclerosis nuclear cardiology with assessment of myocardial perfusion by single photon emission computed tomography and positron emission tomography (PET) appears rather valuable for assessment of viability even when coronary arteries are unchanged. Important significance for detection of cardiosclerosis has also acquired spiral computed tomography, which allows to reveal calcium in blood vessels. The use of multislice computed tomography in perspective might partially replace coronary angiography especially for assessment of degree of stenoses and patency of grafts. On initial stages of atherosclerosis information on AP structure especially on the presence of inflammatory component is very important. Definite successes become noticeable with application of magnetic resonance tomography for detection of AP. However, probably, further perfection of equipment and methodological approaches with the use of novel contrasts is necessary. In this plane definite successes are achieved by PET and combined examinations by methods of PET/CT integrating advantages of both techniques.     

Evidence of Inter-organ Amino-Acid Transport by Blood Cells in Humans

To evaluate the contribution of blood cellular elements to inter-organ transport of amino acids, net exchange across the leg and splanchnic bed of 17 amino acids was determined in seven healthy postabsorptive subjects by use of both whole blood and plasma for analysis. Arterial-portal venous differences were measured in five additional subjects undergoing elective cholecystectomy. By use of whole blood, significant net release of amino acids was noted from the leg and gut, while a consistent uptake was observed by the splanchnic bed. The output of alanine from the leg and gut and the uptake of this amino acid by the splanchnic bed exceeded that of all other amino acids and accounted for 35-40% of total amino-acid exchange. Transport by way of plasma could not account for total tissue release or uptake of alanine, threonine, serine, glutamine, methionine, leucine, isoleucine, tyrosine, and citrulline. For each of these amino acids, significant tissue exchange was calculated to occur by way of the blood cellular elements, the direction of which generally paralleled the net shifts occurring in plasma. For alanine, 30% of its output from the leg and gut and 22% of its uptake by the splanchnic area occurred by way of blood cells. We conclude that the blood cellular elements, presumably erythrocytes, contribute substantially to the net flux of amino acids from muscle and gut to liver in normal postabsorptive humans. Alanine predominates in the inter-organ transfer of amino acids occurring by way of blood cells as well as plasma.     

Ultrafast computed tomography in management of post-bentall aortic root pseudoaneurysm repair

A giant pseudoaneurysm adjacent to the sternum was diagnosed in a patient who had undergone aortic root replacement with use of the Bentall operation 10 years earlier. Electron-beam computed tomography showed that the right coronary artery, which could not be seen on angiography, originated from the pseudoaneurysm itself. At reoperation, we found that both coronary ostia were detached and that the right coronary ostium was totally detached. The source of the right coronary artery blood flow was the pseudoaneurysm itself The defect at the left coronary artery attachment site was repaired primarily. A vein graft was interposed between the ostium of the right coronary artery and the native aorta, distal to the graft anastomosis.     

Elements of the metabolic syndrome: association with insulin sensitivity and effects of ethnicity

Background: The objectives of the present study were, within a group of 322 healthy European American (EA) and African American (AA) women, to, (1) determine the extent to which insulin sensitivity (Si) was correlated with the elements of the metabolic syndrome using the third Adult Treatment Panel (ATP III) criteria; (2) determine if ethnicity affected the relationships between Si and the elements of the metabolic syndrome; and (3) determine the amount of variance in elements of the metabolic syndrome independently explained by fasting insulin, the acute insulin response to glucose (AIRg), and Si. Methods: Si and AIRg were assessed with a frequently-sampled intravenous glucose tolerance test and minimal modeling; total body fat with dual-energy x-ray absorptiometry; and intra-abdominal adipose tissue (IAAT) with computed tomography scanning. Results: Among all women combined, Si was associated with fasting glucose (r = -0.18, p < 0.01), waist circumference (r = -0.36, p < 0.001), and high-density lipoprotein cholesteraol (HDL-C; r = 0.18, p < 0.01). However, the association of Si with elements of the metabolic syndrome other than fasting glucose and waist circumference differed with ethnicity; among EA, Si was correlated with triglycerides (r = -0.28, p < 0.01) and HDL-C (r = 0.29, p < 0.001), whereas among AA, Si tended to be correlated with systolic blood pressure (r = -0.17, p = 0.059). In multiple regression modeling, fasting insulin was independently related to more elements of the metabolic syndrome (fasting glucose, waist circumference, triglycerides, systolic and diastolic blood pressure) than were Si or AIRg (both related only to fasting glucose), after adjusting for ethnicity, age, and total fat or IAAT. Conclusions: Correlation of Si with elements of the metabolic syndrome differed with ethnic group. Fasting insulin, rather than Si, best predicted most elements of the metabolic syndrome.     

Splenic Pseudocyst Associated with Hypersplenism

A patient with hypersplenism, who was found to have a splenic pseudocyst containing an organized hematoma, is described. There are only two patients with splenic pseudocyst and hypersplenism and an additional two patients with splenic cysts and hypersplenism reported in the world literature. The hypersplenism associated with splenic cysts and pseudocysts is explained on the basis of an expansion of the plasma volume and the total blood volume, an increased destruction of red blood cells and a pooling of blood in the enlarged spleen. The combined use of ultrasonography and computerized tomography has increased the accuracy of noninvasive diagnosis and made more invasive examinations unnecessary. When the ultrasound is technically unsuccessful or when it shows a mixed echo pattern, one should resort to computerized tomography with which it is possible, almost invariably, to differentiate between cysts and neoplasms.     

Formation of a morphologically complex system by peroxidase-positive lysosomal elements in human monocytes

Computer-aided three-dimensional reconstruction of serial ultrathin sections revealed that freshly prepared monocytes from human blood contained endogenous peroxidase (PO) not only in cytoplasmic granules, but also in long contorted tubules and in complex elements, which consisted of both tubular and granular components. The various PO- positive elements formed an intricate system, which was separate from all other cytoplasmic structures, including the endoplasmic reticulum and the Golgi apparatus. Because the PO-positive elements in monocytes are known to be primary lysosomes, which are involved in host defense mechanisms, we suggest that the antimicrobial functions of human blood monocytes are exerted by functionally and morphologically diverse subcompartments of a complex system rather than by separate uniform granules.     

Visualization by 256-slice computed tomography of mycotic aortic root aneurysms in infective endocarditis

Infective endocarditis (IE) may lead to mycotic aortic root aneurysm formation. Herein is described the preoperative use of ECG-gated contrast-enhanced 256-slice cardiac computed tomography (CT) to optimize surgical planning by visualizing the location and extent of the mycotic aneurysm in two patients with complicated IE. In both cases, CT revealed a large aortic root mycotic aneurysm, accurately determined its location and extent, and also depicted the close relationship of the aneurysm to the major blood vessels. Intraoperative surgical findings corresponded to preoperative CT findings in both cases. Multislice CT is a valuable technique in patients with complicated IE that helps to optimize preoperative surgical planning.     

When More Is Better: Underused Advanced Imaging Exams That Can Improve Outcomes and Reduce Cost of Care

Appropriate use of resources is a tenet of care transformation efforts, with a national campaign to reduce low-value imaging. The next level of performance improvement is to bolster evidence-based screening, imaging surveillance, and diagnostic innovation, which can avert more costly, higher-risk elements of unnecessary care like emergent interventions. Clinical scenarios in which underused advanced imaging can improve outcomes and reduce total cost of care are reviewed, including abdominal aortic aneurysm surveillance, coronary artery disease diagnosis, and renal mass characterization. Reliable abdominal aortic aneurysm surveillance imaging reduces emergency surgery and can be driven by radiologists incorporating best practice standardized recommendations in imaging interpretations. Coronary computed tomography angiography in patients with stable and unstable chest pain can reduce downstream resource use while improving outcomes. Preoperative ^99mTc-sestamibi single-photon emission computed tomography (SPECT) reliably distinguishes oncocytoma from renal cell carcinoma to obviate unnecessary nephrectomy. As technological advances in diagnostic, molecular, and interventional radiology improve our ability to detect and cure disease, analyses of cost effectiveness will be critical to radiology leadership and sustainability in the transition to a value-based reimbursement model.     

In-Line Phase-Contrast X-ray Imaging and Tomography for Materials Science

X-ray phase-contrast imaging and tomography make use of the refraction of X-rays by the sample in image formation. This provides considerable additional information in the image compared to conventional X-ray imaging methods, which rely solely on X-ray absorption by the sample. Phase-contrast imaging highlights edges and internal boundaries of a sample and is thus complementary to absorption contrast, which is more sensitive to the bulk of the sample. Phase-contrast can also be used to image low-density materials, which do not absorb X-rays sufficiently to form a conventional X-ray image. In the context of materials science, X-ray phase-contrast imaging and tomography have particular value in the 2D and 3D characterization of low-density materials, the detection of cracks and voids and the analysis of composites and multiphase materials where the different components have similar X-ray attenuation coefficients. Here we review the use of phase-contrast imaging and tomography for a wide variety of materials science characterization problems using both synchrotron and laboratory sources and further demonstrate the particular benefits of phase contrast in the laboratory setting with a series of case studies.     

Value of scanning electron microscopy in evaluation of peripheral red blood cells shape in patients with pulmonary tuberculosis for treatment effectiveness evaluation]

The morphology of red blood cells in patients with pulmonary tuberculosis was studied by scanning electron microscopy during enterosorption. The use of an enterosorbent caused a significant decrease in the count of abnormally changed cell elements and an increase in normocytes, which suggests that detoxification has a stimulating effect. Enterosorption promotes less content of altered peripheral red blood cells, which leads to improvement of its cellular composition in the presence of clinical manifestations of the decreased rate of a tuberculous process in the lung and which is suggestive of the detoxifying impact of this treatment.     

Computer tomography in cardiology. 1. Methods

The authors discuss the methodology of the computer-aided tomography of the heart which is to include dynamic scanning with, if indicated, synchronous ECG paralleled with the intravenous bolus administration of the contrast medium. The synchronization with ECG makes it possible to obtain a computer-aided tomographic image of the heart at any phase of the cardiac cycle. Computer-aided tomography was performed in 306 patients with various forms of heart disease. Five levels of scanning can be identified under normal conditions which present all structural elements of the heart.     

X-ray computed tomography and magnetic resonance imaging of the cardiovascular system

Both electron beam (or ultrafast) x-ray computed tomography and magnetic resonance imaging are developing cardiovascular imaging modalities that can provide high temporal and spatial resolution images of the beating heart and the great vessels in the outpatient setting. The three-dimensional registration of these images has facilitated numerous studies, showing that these devices are capable of quantitating cardiovascular anatomy, function, and blood flow. Continued research employing these methodologies has examined both applications that are complementary to more traditional noninvasive cardiology tools, such as two-dimensional echocardiography and radionuclide and perfusion imaging, as well as applications unique to computed tomography or magnetic resonance imaging. This review discusses progress made in x-ray computed tomography, focusing on the application of electron beam computed tomography and new applications of magnetic resonance imaging within the past 2 years. Specific comments are made regarding these applications, as well as the limitations of both with regard to general clinical applications.     

Imaging of the thyroid: Recent advances

Although thyroid scintigraphy and ultrasound continues to be the mainstay of the diagnostic imaging of the thyroid gland, there have been several recent advances that are of interest to both radiologists and endocrinologists. In this review article, the authors discuss recent progress in imaging of the thyroid by use of radionuclide imaging including single photon-emission computed tomography/positron emission tomography, ultrasonography (USG), USG elastography, computed tomography (CT), magnetic resonance imaging (MRI), and optical coherence tomography.     

Cyclic Deformation Induced Residual Stress Evolution and 3D Short Fatigue Crack Growth Investigated by Advanced Synchrotron Tomography Techniques

Diffraction and phase contrast tomography techniques were successfully applied to an austenitic–ferritic duplex stainless steel representing exemplarily a metallic material containing two phases with different crystal structures. The reconstructed volumes of both phases were discretized by finite elements. A crystal plasticity finite-element analysis was executed in order to simulate the development of the experimentally determined first and second order residual stresses, which built up due to the manufacturing process of the material. Cyclic deformation simulations showed the single-grain-resolved evolution of initial residual stresses in both phases and were found to be in good agreement with the experimental results. Solely in ferritic grains, residual stresses built up due to cyclic deformation, which promoted crack nucleation in this phase. Furthermore, phase contrast tomography was applied in order to analyze the mechanisms of fatigue crack nucleation and short fatigue crack propagation three-dimensionally and nondestructively. The results clearly showed the significance of microstructural barriers for short fatigue crack growth at the surface, as well as into the material. The investigation presented aims for a better understanding of the three-dimensional mechanisms governing short fatigue crack propagation and, in particular, the effect of residual stresses on these mechanisms. The final goal was to generate tailored microstructures for improved fatigue resistance and enhanced fatigue life.     

Recent advances in thoracic x-ray computed tomography for pulmonary imaging

The present article reviews recent advances in pulmonary computed tomography (CT) imaging, focusing on the application of dual-energy CT and the use of iterative reconstruction. Dual-energy CT has proven to be useful in the characterization of pulmonary blood pool in the setting of pulmonary embolism, characterization of diffuse lung parenchymal diseases, evaluation of thoracic malignancies and in imaging of lung ventilation using inhaled xenon. The benefits of iterative reconstruction have been largely derived from reduction of image noise compared with filtered backprojection reconstructions which, in turn, enables the use of lower radiation dose CT acquisition protocols without sacrificing image quality. Potential clinical applications of iterative reconstruction include imaging for pulmonary nodules and high-resolution pulmonary CT.     

Chest radiographic findings in cystic fibrosis.

Radiographic imaging modalities that have been applied to the staging and prognostication of the lung lesion in cystic fibrosis (CF) include conventional chest radiographs, computed tomography (CT), and magnetic resonance imaging (MRI). Conventional chest radiographs are usually adequate to detect the salient radiographic features of CF and provide objective parameters for longitudinal disease progression. Although the lung manifestations of CF can be highly variable most patients with CF demonstrate some of the classic chest radiographic findings that reflect chronic bronchiectasis: hyperinflation, bronchial thickening and dilatation, peribronchial cuffing, mucoid impaction, cystic radiolucencies, an increase in interstitial markings, and scattered nodular densities. Complications of advanced CF include atelectasis, mucoid impaction, pneumothorax, pneumomediastinum, pulmonary hemorrhage, cardiomegaly, and enlargement of the pulmonary artery with cor pulmonale. Scoring systems have been developed to grade the chest radiograph in CF and to more accurately quantitate the severity of disease. Currently, the Brasfield system is in widest use. These radiographic scoring systems correlate well with pulmonary function data in both the pediatric and adult CF populations. High-resolution computed tomography (HRCT) is clearly more sensitive and accurate than conventional chest radiography in delineating the extent and severity of bronchiectasis and other parenchymal and airway lesions in CF. Quantifiable scoring systems using HRCT have been developed to assess disease severity in CF. The use of MRI in the clinical management of CF has been limited. MRI may be helpful in determining the cause of linear lung markings, differentiating mucous plugging, and peribronchial thickening from normal pulmonary blood vessels. MRI is an excellent imaging modality to differentiate hilar or mediastinal adenopathy from blood vessels or mediastinal fat.     

Molecular imaging of plaques in coronary arteries with PET and SPECT

Coronary artery disease remains a major cause of mortality. Presence of atherosclerotic plaques in the coronary artery is responsible for lu-men stenosis which is often used as an indicator for determining the severity of coronary artery disease. However, the degree of coronary lumen stenosis is not often related to compromising myocardial blood flow, as most of the cardiac events that are caused by atherosclerotic plaques are the result of vulnerable plaques which are prone to rupture. Thus, identification of vulnerable plaques in coronary arteries has become increas-ingly important to assist identify patients with high cardiovascular risks. Molecular imaging with use of positron emission tomography （PET） and single photon emission computed tomography （SPECT） has fulfilled this goal by providing functional information about plaque activity which enables accurate assessment of plaque stability. This review article provides an overview of diagnostic applications of molecular imaging tech-niques in the detection of plaques in coronary arteries with PET and SPECT. New radiopharmaceuticals used in the molecular imaging of coro-nary plaques and diagnostic applications of integrated PET/CT and PET/MRI in coronary plaques are also discussed.