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99-427: The technique needs delivery of a gamma-emitting radioisotope (a radionuclide ) into the patient, normally through injection into the bloodstream. On occasion, the radioisotope is a simple soluble dissolved ion, such as an isotope of gallium (III). Usually, though, a marker radioisotope is attached to a specific ligand to create a radioligand , whose properties bind it to certain types of tissues. This marriage allows

198-417: A coronary care unit for possible complications (such as cardiac arrhythmias – irregularities in the heart rate). Depending on the risk assessment, stress testing or angiography may be used to identify and treat coronary artery disease in patients who have had an NSTEMI or unstable angina. There are various risk assessment systems for determining the risk of coronary artery disease, with various emphasis on

297-619: A healthy diet , regularly exercising , maintaining a healthy weight, and not smoking. Medications for diabetes, high cholesterol, or high blood pressure are sometimes used. There is limited evidence for screening people who are at low risk and do not have symptoms. Treatment involves the same measures as prevention. Additional medications such as antiplatelets (including aspirin ), beta blockers , or nitroglycerin may be recommended. Procedures such as percutaneous coronary intervention (PCI) or coronary artery bypass surgery (CABG) may be used in severe disease. In those with stable CAD it

396-539: A SPECT gamma scanner may be built to operate with a conventional CT scanner , with coregistration of images. As in PET/CT , this allows location of tumors or tissues which may be seen on SPECT scintigraphy, but are difficult to locate precisely with regard to other anatomical structures. Such scans are most useful for tissues outside the brain, where location of tissues may be far more variable. For example, SPECT/CT may be used in sestamibi parathyroid scan applications, where

495-683: A combination of genetic predisposition and environmental factors. Organizations such as the Indian Heart Association are working with the World Heart Federation to raise awareness about this issue. Coronary artery disease is the leading cause of death for both males and females and accounts for approximately 600,000 deaths in the United States every year. According to present trends in the United States, half of healthy 40-year-old males will develop CAD in

594-402: A complete tabulation). They include 30 nuclides with measured half-lives longer than the estimated age of the universe (13.8 billion years ), and another four nuclides with half-lives long enough (> 100 million years) that they are radioactive primordial nuclides , and may be detected on Earth, having survived from their presence in interstellar dust since before the formation of

693-456: A dual-headed camera can be used with heads spaced 180 degrees apart, allowing two projections to be acquired simultaneously, with each head requiring 180 degrees of rotation. Triple-head cameras with 120-degree spacing are also used. Cardiac gated acquisitions are possible with SPECT, just as with planar imaging techniques such as multi gated acquisition scan (MUGA). Triggered by electrocardiogram (EKG) to obtain differential information about

792-405: A given age also decreased between 1990 and 2010. In the United States in 2010, about 20% of those over 65 had CAD, while it was present in 7% of those 45 to 64, and 1.3% of those 18 to 45; rates were higher among males than females of a given age. The most common symptom is chest pain or discomfort that occurs regularly with activity, after eating, or at other predictable times; this phenomenon

891-490: A heart attack or myocardial infarction, and immediate emergency medical services are crucial. With advanced disease, the narrowing of coronary arteries reduces the supply of oxygen-rich blood flowing to the heart, which becomes more pronounced during strenuous activities during which the heart beats faster and has an increased oxygen demand. For some, this causes severe symptoms, while others experience no symptoms at all. Symptoms in females can differ from those in males, and

990-431: A myocardial infarction but does not change the overall risk of death. Aspirin therapy to prevent heart disease is thus recommended only in adults who are at increased risk for cardiovascular events, which may include postmenopausal females, males above 40, and younger people with risk factors for coronary heart disease, including high blood pressure , a family history of heart disease, or diabetes . The benefits outweigh

1089-404: A neuropsychological assessment. There are a number of treatment options for coronary artery disease: It is recommended that blood pressure typically be reduced to less than 140/90 mmHg. The diastolic blood pressure however should not be lower than 60 mmHg. Beta-blockers are recommended first line for this use. In those with no previous history of heart disease, aspirin decreases the risk of

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1188-426: A nuclear reactor, a wide array of gamma-emitting radionuclides are naturally produced in the fuel, such as fission products ( cesium-137 , barium-140 and europium-154 ) and activation products ( chromium-51 and cobalt-58 ). These may be imaged using SPECT in order to verify the presence of fuel rods in a stored fuel assembly for IAEA safeguards purposes, to validate predictions of core simulation codes, or to study

1287-414: A number of factors, and "can damage the functions of healthy tissue/organs. Radiation exposure can produce effects ranging from skin redness and hair loss, to radiation burns and acute radiation syndrome . Prolonged exposure can lead to cells being damaged and in turn lead to cancer. Signs of cancerous cells might not show up until years, or even decades, after exposure." Following is a summary table for

1386-418: A result of rare events such as spontaneous fission or uncommon cosmic ray interactions. Radionuclides are produced as an unavoidable result of nuclear fission and thermonuclear explosions . The process of nuclear fission creates a wide range of fission products , most of which are radionuclides. Further radionuclides can be created from irradiation of the nuclear fuel (creating a range of actinides ) and of

1485-427: A role. The diagnosis of CAD depends largely on the nature of the symptoms and imaging. The first investigation when CAD is suspected is an electrocardiogram (ECG/EKG), both for stable angina and acute coronary syndrome. An X-ray of the chest , blood tests and resting echocardiography may be performed. For stable symptomatic patients, several non-invasive tests can diagnose CAD depending on pre-assessment of

1584-558: A safe and feasible procedure that may offer some advantages over conventional CABG though it is more expensive. As of 2010, CAD was the leading cause of death globally resulting in over 7 million deaths. This increased from 5.2 million deaths from CAD worldwide in 1990. It may affect individuals at any age but becomes dramatically more common at progressively older ages, with approximately a tripling with each decade of life. Males are affected more often than females. The World Health Organization reported that: "The world's biggest killer

1683-416: A significant role in stiffening the arteries and inducing the early phase of coronary arteriosclerosis . This can be seen in a so-called metastatic mechanism of calciphylaxis as it occurs in chronic kidney disease and hemodialysis . Although these people have kidney dysfunction, almost fifty percent of them die due to coronary artery disease. Plaques can be thought of as large "pimples" that protrude into

1782-440: A stable nuclide or will sometimes produce a new unstable radionuclide which may undergo further decay. Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay. However, for a collection of atoms of a single nuclide the decay rate, and thus the half-life ( t 1/2 ) for that collection, can be calculated from their measured decay constants . The range of

1881-410: A true 3D representation can be helpful, such as tumor imaging, infection ( leukocyte ) imaging, thyroid imaging or bone scintigraphy . Because SPECT permits accurate localisation in 3D space, it can be used to provide information about localised function in internal organs, such as functional cardiac or brain imaging. Myocardial perfusion imaging (MPI) is a form of functional cardiac imaging, used for

1980-421: Is Technetium (99mTc) exametazime . Tc is a metastable nuclear isomer that emits gamma rays detectable by a gamma camera. Attaching it to exametazime allows it to be taken up by brain tissue in a manner proportional to brain blood flow, in turn allowing cerebral blood flow to be assessed with the nuclear gamma camera. Because blood flow in the brain is tightly coupled to local brain metabolism and energy use,

2079-578: Is a summary table for the 989 nuclides with half-lives longer than one hour (including those that are stable), given in list of nuclides . This list covers common isotopes, most of which are available in very small quantities to the general public in most countries. Others that are not publicly accessible are traded commercially in industrial, medical, and scientific fields and are subject to government regulation. Ischemic heart disease Coronary artery disease ( CAD ), also called coronary heart disease ( CHD ), or ischemic heart disease ( IHD ),

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2178-417: Is a type of heart disease involving the reduction of blood flow to the cardiac muscle due to a build-up of atheromatous plaque in the arteries of the heart . It is the most common of the cardiovascular diseases . CAD can cause stable angina , unstable angina , myocardial ischemia, and myocardial infarction . A common symptom is angina, which is chest pain or discomfort which may travel into

2277-570: Is another way of risk assessment. In one study the relative risk of incident coronary events was 91% higher among participants at high genetic risk than among those at low genetic risk. Up to 90% of cardiovascular disease may be preventable if established risk factors are avoided. Prevention involves adequate physical exercise , decreasing obesity , treating high blood pressure , eating a healthy diet , decreasing cholesterol levels, and stopping smoking . Medications and exercise are roughly equally effective. High levels of physical activity reduce

2376-410: Is available. In the absence of ST-segment elevation, heart damage is detected by cardiac markers (blood tests that identify heart muscle damage). If there is evidence of damage ( infarction ), the chest pain is attributed to a "non-ST elevation MI" (NSTEMI). If there is no evidence of damage, the term "unstable angina" is used. This process usually necessitates hospital admission and close observation on

2475-507: Is called a myocardial infarction (commonly referred to as a heart attack). It leads to damage, death, and eventual scarring of the heart muscle without regrowth of heart muscle cells. Chronic high-grade narrowing of the coronary arteries can induce transient ischemia which leads to the induction of a ventricular arrhythmia , which may terminate into a dangerous heart rhythm known as ventricular fibrillation , which often leads to death. Typically, coronary artery disease occurs when part of

2574-593: Is called a radiopharmaceutical . On Earth, naturally occurring radionuclides fall into three categories: primordial radionuclides, secondary radionuclides, and cosmogenic radionuclides. Many of these radionuclides exist only in trace amounts in nature, including all cosmogenic nuclides. Secondary radionuclides will occur in proportion to their half-lives, so short-lived ones will be very rare. For example, polonium can be found in uranium ores at about 0.1 mg per metric ton (1 part in 10 ). Further radionuclides may occur in nature in virtually undetectable amounts as

2673-503: Is characterized by heart problems that result from atherosclerosis. Atherosclerosis is a type of arteriosclerosis which is the "chronic inflammation of the arteries which causes them to harden and accumulate cholesterol plaques (atheromatous plaques) on the artery walls". CAD has several well-determined risk factors that contribute to atherosclerosis. These risk factors for CAD include "smoking, diabetes, high blood pressure (hypertension), abnormal (high) amounts of cholesterol and other fat in

2772-415: Is found in cardiac muscle; it is a 'cytolinker' that connects actin and desmin to facilitate cytoskeletal function and vesicular movement. The endocytic pathway is further modulated by changes in tubulin , a key microtubule protein, and fidgetin , a tubulin-severing enzyme that is a marker for cardiovascular risk identified by genome-wide association study . Protein recycling would be modulated by changes in

2871-491: Is inferior to non-invasive imaging methods due to the risk of false negative and false positive test results. The use of non-invasive imaging is not recommended on individuals who are exhibiting no symptoms and are otherwise at low risk for developing coronary disease. Invasive testing with coronary angiography (ICA) can be used when non-invasive testing is inconclusive or show a high event risk. The diagnosis of microvascular angina (previously known as cardiac syndrome X –

2970-459: Is ischemic heart disease, responsible for 13% of the world's total deaths. Since 2000, the largest increase in deaths has been for this disease, rising by 2.7 million to 9.1 million deaths in 2021." It is estimated that 60% of the world's cardiovascular disease burden will occur in the South Asian subcontinent despite only accounting for 20% of the world's population. This may be secondary to

3069-687: Is linked to an increased risk of coronary disease. The consumption of different types of fats including trans fat (trans unsaturated), and saturated fat , in a diet "influences the level of cholesterol that is present in the bloodstream". Unsaturated fats originate from plant sources (such as oils). There are two types of unsaturated fats, cis and trans isomers. Cis unsaturated fats are bent in molecular structure and trans are linear in structure. Saturated fats originate from animal sources (such as animal fats) and are also molecularly linear in structure. The linear configurations of unsaturated trans and saturated fats allow them to easily accumulate and stack at

Single-photon emission computed tomography - Misplaced Pages Continue

3168-452: Is made by comparing stress images to a further set of images obtained at rest which are normally acquired prior to the stress images. MPI has been demonstrated to have an overall accuracy of about 83% ( sensitivity : 85%; specificity : 72%) (in a review, not exclusively of SPECT MPI), and is comparable with (or better than) other non-invasive tests for ischemic heart disease. Usually, the gamma-emitting tracer used in functional brain imaging

3267-493: Is made in an expensive medical cyclotron and "hot-lab" (automated chemistry lab for radiopharmaceutical manufacture), and then delivered immediately to scanning sites because of the natural short 110-minute half-life of Fluorine-18 . In the nuclear power sector, the SPECT technique can be applied to image radioisotope distributions in irradiated nuclear fuels. Due to the irradiation of nuclear fuel (e.g. uranium) with neutrons in

3366-468: Is more effective than hemoglobin A1c (HbA1c) for detecting dysglycemia in patients with coronary artery disease. The study highlighted that 2-hour post-load glucose levels of at least 9 mmol/L were strong predictors of cardiovascular outcomes, while HbA1c levels of at least 5.9% were also significant but not independently associated when combined with OGTT results. A diet high in fruits and vegetables decreases

3465-489: Is most commonly used to provide rapid relief for acute angina attacks and as a complement to anti-anginal treatments in patients with refractory and recurrent angina. When nitroglycerine enters the bloodstream, it forms free radical nitric oxide, or NO, which activates guanylate cyclase and in turn stimulates the release of cyclic GMP. This molecular signaling stimulates smooth muscle relaxation, ultimately resulting in vasodilation and consequently improved blood flow to regions of

3564-533: Is no evidence that they change mortality, the risk of revascularization procedures, or the rate of non-fatal myocardial infarction. Antibiotics for secondary prevention of coronary heart disease Early studies suggested that antibiotics might help patients with coronary disease to reduce the risk of heart attacks and strokes. However, a 2021 Cochrane meta-analysis found that antibiotics given for secondary prevention of coronary heart disease are harmful for people with increased mortality and occurrence of stroke. So,

3663-626: Is preventing further sequelae of already established disease. Effective lifestyle changes include: Aerobic exercise , like walking, jogging, or swimming, can reduce the risk of mortality from coronary artery disease. Aerobic exercise can help decrease blood pressure and the amount of blood cholesterol (LDL) over time. It also increases HDL cholesterol. Although exercise is beneficial, it is unclear whether doctors should spend time counseling patients to exercise. The U.S. Preventive Services Task Force found "insufficient evidence" to recommend that doctors counsel patients on exercise but "it did not review

3762-541: Is termed stable angina and is associated with narrowing of the arteries of the heart . Angina also includes chest tightness, heaviness, pressure, numbness, fullness, or squeezing. Angina that changes in intensity, character or frequency is termed unstable. Unstable angina may precede myocardial infarction . In adults who go to the emergency department with an unclear cause of pain, about 30% have pain due to coronary artery disease. Angina, shortness of breath, sweating, nausea or vomiting, and lightheadedness are signs of

3861-423: Is time-consuming, and it is essential that there is no patient movement during the scan time. Movement can cause significant degradation of the reconstructed images, although movement compensation reconstruction techniques can help with this. A highly uneven distribution of radiopharmaceutical also has the potential to cause artifacts. A very intense area of activity (e.g., the bladder) can cause extensive streaking of

3960-434: Is unclear if PCI or CABG in addition to the other treatments improves life expectancy or decreases heart attack risk. In 2015, CAD affected 110 million people and resulted in 8.9 million deaths. It makes up 15.6% of all deaths, making it the most common cause of death globally. The risk of death from CAD for a given age decreased between 1980 and 2010, especially in developed countries . The number of cases of CAD for

4059-425: Is very similar to planar gamma camera imaging, the same radiopharmaceuticals may be used. If a patient is examined in another type of nuclear medicine scan, but the images are non-diagnostic, it may be possible to proceed straight to SPECT by moving the patient to a SPECT instrument, or even by simply reconfiguring the camera for SPECT image acquisition while the patient remains on the table. To acquire SPECT images,

Single-photon emission computed tomography - Misplaced Pages Continue

4158-466: The Solar System , about 4.6 billion years ago. Another 60+ short-lived nuclides can be detected naturally as daughters of longer-lived nuclides or cosmic-ray products. The remaining known nuclides are known solely from artificial nuclear transmutation . Numbers are not exact, and may change slightly in the future, as "stable nuclides" are observed to be radioactive with very long half-lives. This

4257-528: The list of 989 nuclides with half-lives greater than one hour. A total of 251 nuclides have never been observed to decay, and are classically considered stable. Of these, 90 are believed to be absolutely stable except to proton decay (which has never been observed), while the rest are " observationally stable " and theoretically can undergo radioactive decay with extremely long half-lives. The remaining tabulated radionuclides have half-lives longer than 1 hour, and are well-characterized (see list of nuclides for

4356-527: The Earth was formed. At least another 60 radionuclides are detectable in nature, either as daughters of primordial radionuclides or as radionuclides produced through natural production on Earth by cosmic radiation. More than 2400 radionuclides have half-lives less than 60 minutes. Most of those are only produced artificially, and have very short half-lives. For comparison, there are about 251 stable nuclides . All chemical elements can exist as radionuclides. Even

4455-497: The Tc-exametazime tracer (as well as the similar Tc-EC tracer) is used to assess brain metabolism regionally, in an attempt to diagnose and differentiate the different causal pathologies of dementia . Meta-analysis of many reported studies suggests that SPECT with this tracer is about 74% sensitive at diagnosing Alzheimer's disease vs. 81% sensitivity for clinical exam ( cognitive testing , etc.). More recent studies have shown

4554-467: The accuracy of SPECT in Alzheimer's diagnosis may be as high as 88%. In meta analysis, SPECT was superior to clinical exam and clinical criteria (91% vs. 70%) in being able to differentiate Alzheimer's disease from vascular dementias. This latter ability relates to SPECT's imaging of local metabolism of the brain, in which the patchy loss of cortical metabolism seen in multiple strokes differs clearly from

4653-603: The air in the detector's ionization chamber . A small electric voltage is applied to the ionized air which gives rise to a small electric current. In the presence of smoke, some of the ions are neutralized, thereby decreasing the current, which activates the detector's alarm. Radionuclides that find their way into the environment may cause harmful effects as radioactive contamination . They can also cause damage if they are excessively used during treatment or in other ways exposed to living beings, by radiation poisoning . Potential health damage from exposure to radionuclides depends on

4752-413: The arterial walls when consumed in high amounts (and other positive measures towards physical health are not met). High levels of cholesterol in the bloodstream lead to atherosclerosis. With increased levels of LDL in the bloodstream, "LDL particles will form deposits and accumulate within the arterial walls, which will lead to the development of plaques, restricting blood flow". The resultant reduction in

4851-476: The behavior of the nuclear fuel in normal operation, or in accident scenarios. Reconstructed images typically have resolutions of 64×64 or 128×128 pixels, with the pixel sizes ranging from 3–6 mm. The number of projections acquired is chosen to be approximately equal to the width of the resulting images. In general, the resulting reconstructed images will be of lower resolution, have increased noise than planar images, and be susceptible to artifacts . Scanning

4950-543: The blood (dyslipidemia), type 2 diabetes and being overweight or obese (having excess body fat)" due to lack of exercise and a poor diet. Some other risk factors include high blood pressure , smoking , diabetes , lack of exercise, obesity , high blood cholesterol , poor diet, depression , family history , psychological stress and excessive alcohol . About half of cases are linked to genetics. Smoking and obesity are associated with about 36% and 20% of cases, respectively. Smoking just one cigarette per day about doubles

5049-581: The bone morphogenic proteins are members of the TGF-beta superfamily, and likewise impact Treg differentiation. Several of the transcripts ( TMEM98 , NRCAM , SFRP5 , SHISA2 ) are elements of the Wnt signaling pathway, which is a major determinant of Treg differentiation. Limitation of blood flow to the heart causes ischemia (cell starvation secondary to a lack of oxygen) of the heart's muscle cells . The heart's muscle cells may die from lack of oxygen and this

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5148-517: The brain, which works to assess regional brain glucose metabolism, to provide very similar information about local brain damage from many processes. SPECT is more widely available, because the radioisotope used is longer-lasting and far less expensive in SPECT, and the gamma scanning equipment is less expensive as well. While Tc is extracted from relatively simple technetium-99m generators , which are delivered to hospitals and scanning centers weekly to supply fresh radioisotope, FDG PET relies on FDG, which

5247-473: The channel of an artery, causing partial obstruction to blood flow. People with coronary artery disease might have just one or two plaques or might have dozens distributed throughout their coronary arteries . A more severe form is chronic total occlusion (CTO) when a coronary artery is completely obstructed for more than 3 months. Microvascular angina is a type of angina pectoris in which chest pain and chest discomfort occur without signs of blockages in

5346-516: The circulating immune system would be related to the immune synapse . One of the most differentially expressed genes, fibromodulin (FMOD), which is increased 2.8-fold in CAD, is found mainly in connective tissue and is a modulator of the TGF-beta signaling pathway. However, not all of the RNA changes may be related to the immune synapse. For example, Nebulette , the most down-regulated transcript (2.4-fold),

5445-431: The combination of chemical properties and their radiation (tracers, biopharmaceuticals). The following table lists properties of selected radionuclides illustrating the range of properties and uses. Key: Z  =  atomic number ; N  =  neutron number ; DM = decay mode; DE = decay energy; EC =  electron capture Radionuclides are present in many homes as they are used inside

5544-410: The combination of ligand and radiopharmaceutical to be carried and bound to a place of interest in the body, where the ligand concentration is seen by a gamma camera. Instead of just "taking a picture of anatomical structures", a SPECT scan monitors level of biological activity at each place in the 3-D region analyzed. Emissions from the radionuclide indicate amounts of blood flow in the capillaries of

5643-429: The diagnosis of ischemic heart disease . The underlying principle is that under conditions of stress, diseased myocardium receives less blood flow than normal myocardium. MPI is one of several types of cardiac stress test . A cardiac specific radiopharmaceutical is administered, e.g., Tc- tetrofosmin (Myoview, GE healthcare), Tc-sestamibi (Cardiolite, Bristol-Myers Squibb) or Thallium-201 chloride. Following this,

5742-409: The diameter of their blood vessels, leading to decreased progression of atherosclerosis. In contrast, females who had high levels of work-related stress experienced a decrease in the diameter of their blood vessels and significantly increased disease progression. Having a type A behavior pattern , a group of personality characteristics including time urgency, competitiveness, hostility, and impatience,

5841-552: The different variables above. A notable example is Framingham Score , used in the Framingham Heart Study . It is mainly based on age, gender, diabetes, total cholesterol, HDL cholesterol, tobacco smoking, and systolic blood pressure. When predicting risk in younger adults (18–39 years old), the Framingham Risk Score remains below 10–12% for all deciles of baseline-predicted risk. Polygenic score

5940-421: The evidence for the effectiveness of physical activity to reduce chronic disease, morbidity, and mortality", only the effectiveness of counseling itself. The American Heart Association , based on a non-systematic review, recommends that doctors counsel patients on exercise. Psychological symptoms are common in people with CHD, and while many psychological treatments may be offered following cardiac events, there

6039-793: The evidence is weak. Specifically, its use does not change the risk of death in this group. In those who have had a stent, more than 12 months of clopidogrel plus aspirin does not affect the risk of death. Revascularization for acute coronary syndrome has a mortality benefit. Percutaneous revascularization for stable ischaemic heart disease does not appear to have benefits over medical therapy alone. In those with disease in more than one artery, coronary artery bypass grafts appear better than percutaneous coronary interventions . Newer "anaortic" or no-touch off-pump coronary artery revascularization techniques have shown reduced postoperative stroke rates comparable to percutaneous coronary intervention. Hybrid coronary revascularization has also been shown to be

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6138-433: The gamma camera is rotated around the patient. Projections are acquired at defined points during the rotation, typically every 3–6 degrees. In most cases, a full 360-degree rotation is used to obtain an optimal reconstruction. The time taken to obtain each projection is also variable, but 15–20 seconds is typical. This gives a total scan time of 15–20 minutes. Multi-headed gamma cameras can accelerate acquisition. For example,

6237-402: The gamma rays within the patient can lead to significant underestimation of activity in deep tissues, compared to superficial tissues. Approximate correction is possible, based on relative position of the activity, and optimal correction is obtained with measured attenuation values. Modern SPECT equipment is available with an integrated X-ray CT scanner. As X-ray CT images are an attenuation map of

6336-437: The half-lives of radioactive atoms has no known limits and spans a time range of over 55 orders of magnitude. Radionuclides occur naturally or are artificially produced in nuclear reactors , cyclotrons , particle accelerators or radionuclide generators . There are about 730 radionuclides with half-lives longer than 60 minutes (see list of nuclides ). Thirty-two of those are primordial radionuclides that were created before

6435-436: The harms most favorably in people at high risk for a cardiovascular event, where high risk is defined as at least a 3% chance over a five-year period, but others with lower risk may still find the potential benefits worth the associated risks. Clopidogrel plus aspirin (dual anti-platelet therapy) reduces cardiovascular events more than aspirin alone in those with a STEMI . In others at high risk but not having an acute event,

6534-450: The heart affected by atherosclerotic plaque. Stable coronary artery disease (SCAD) is also often called stable ischemic heart disease (SIHD). A 2015 monograph explains that "Regardless of the nomenclature, stable angina is the chief manifestation of SIHD or SCAD." There are U.S. and European clinical practice guidelines for SIHD/SCAD. In patients with non-severe asymptomatic aortic valve stenosis and no overt coronary artery disease,

6633-399: The heart in various parts of its cycle, gated myocardial SPECT can be used to obtain quantitative information about myocardial perfusion, thickness, and contractility of the myocardium during various parts of the cardiac cycle, and also to allow calculation of left ventricular ejection fraction , stroke volume, and cardiac output. SPECT can be used to complement any gamma imaging study, where

6732-466: The heart muscle). Diagnosis is clear-cut if ECGs show elevation of the " ST segment ", which in the context of severe typical chest pain is strongly indicative of an acute myocardial infarction (MI); this is termed a STEMI (ST-elevation MI) and is treated as an emergency with either urgent coronary angiography and percutaneous coronary intervention (angioplasty with or without stent insertion) or with thrombolysis ("clot buster" medication), whichever

6831-428: The heart muscle). If part of the heart seems to receive an insufficient blood supply, coronary angiography may be used to identify stenosis of the coronary arteries and suitability for angioplasty or bypass surgery . In minor to moderate cases, nitroglycerine may be used to alleviate acute symptoms of stable angina or may be used immediately before exertion to prevent the onset of angina. Sublingual nitroglycerine

6930-414: The heart rate is raised to induce myocardial stress, either by exercise on a treadmill or pharmacologically with adenosine , dobutamine , or dipyridamole ( aminophylline can be used to reverse the effects of dipyridamole). SPECT imaging performed after stress reveals the distribution of the radiopharmaceutical, and therefore the relative blood flow to the different regions of the myocardium. Diagnosis

7029-787: The heart's blood supply due to atherosclerosis in coronary arteries "causes shortness of breath, angina pectoris (chest pains that are usually relieved by rest), and potentially fatal heart attacks (myocardial infarctions)". The heritability of coronary artery disease has been estimated between 40% and 60%. Genome-wide association studies have identified over 160 genetic susceptibility loci for coronary artery disease. Several RNA Transcripts associated with CAD - FoxP1 , ICOSLG , IKZF4/Eos , SMYD3 , TRIM28 , and TCF3/E2A are likely markers of regulatory T cells (Tregs), consistent with known reductions in Tregs in CAD. The RNA changes are mostly related to ciliary and endocytic transcripts, which in

7128-474: The imaged regions. In the same way that a plain X-ray is a 2-dimensional (2-D) view of a 3-dimensional structure, the image obtained by a gamma camera is a 2-D view of 3-D distribution of a radionuclide . SPECT imaging is performed by using a gamma camera to acquire multiple 2-D images (also called projections ), from multiple angles. A computer is then used to apply a tomographic reconstruction algorithm to

7227-509: The images and obscure neighboring areas of activity. This is a limitation of the filtered back projection reconstruction algorithm. Iterative reconstruction is an alternative algorithm that is growing in importance, as it is less sensitive to artifacts and can also correct for attenuation and depth dependent blurring. Furthermore, iterative algorithms can be made more efficacious using the Superiorization methodology. Attenuation of

7326-520: The immune synapse, there were numerous transcripts that related directly to T cell function and the control of differentiation. Butyrophilin is a co-regulator for T cell activation. Fibromodulin is a modulator of the TGF-beta signaling pathway, a primary determinant of Tre differentiation. Further impact on the TGF-beta pathway is reflected in concurrent changes in the BMP receptor 1B RNA (BMPR1B), because

7425-428: The increased troponin T (above 14 pg/mL) was found associated with an increased 5-year event rate of ischemic cardiac events ( myocardial infarction , percutaneous coronary intervention , or coronary artery bypass surgery ). Diagnosis of acute coronary syndrome generally takes place in the emergency department , where ECGs may be performed sequentially to identify "evolving changes" (indicating ongoing damage to

7524-404: The larger coronary arteries of their hearts when an angiogram (coronary angiogram) is being performed. The exact cause of microvascular angina is unknown. Explanations include microvascular dysfunction or epicardial atherosclerosis. For reasons that are not well understood, females are more likely than males to have it; however, hormones and other risk factors unique to females may play

7623-411: The lightest element, hydrogen , has a well-known radionuclide, tritium . Elements heavier than lead , and the elements technetium and promethium , exist only as radionuclides. Unplanned exposure to radionuclides generally has a harmful effect on living organisms including humans, although low levels of exposure occur naturally without harm. The degree of harm will depend on the nature and extent of

7722-484: The more even or "smooth" loss of non-occipital cortical brain function typical of Alzheimer's disease. Another recent review article showed that multi-headed SPECT cameras with quantitative analysis result in an overall sensitivity of 84-89% and an overall specificity of 83-89% in cross sectional studies and sensitivity of 82-96% and specificity of 83-89% for longitudinal studies of dementia. Tc-exametazime SPECT scanning competes with fludeoxyglucose (FDG) PET scanning of

7821-433: The most common household smoke detectors . The radionuclide used is americium-241 , which is created by bombarding plutonium with neutrons in a nuclear reactor. It decays by emitting alpha particles and gamma radiation to become neptunium-237 . Smoke detectors use a very small quantity of Am (about 0.29 micrograms per smoke detector) in the form of americium dioxide . Am is used as it emits alpha particles which ionize

7920-633: The most common symptom reported by females of all races is shortness of breath. Other symptoms more commonly reported by females than males are extreme fatigue, sleep disturbances, indigestion, and anxiety. However, some females experience irregular heartbeat, dizziness, sweating, and nausea. Burning, pain, or pressure in the chest or upper abdomen that can travel to the arm or jaw can also be experienced in females, but females less commonly report it than males. Generally, females experience symptoms 10 years later than males. Females are less likely to recognize symptoms and seek treatment. Coronary artery disease

8019-449: The multiple projections, yielding a 3-D data set. This data set may then be manipulated to show thin slices along any chosen axis of the body, similar to those obtained from other tomographic techniques, such as magnetic resonance imaging (MRI), X-ray computed tomography (X-ray CT), and positron emission tomography (PET). SPECT is similar to PET in its use of radioactive tracer material and detection of gamma rays. In contrast with PET,

8118-412: The myocardium. Stable angina is short-term chest pain during physical exertion caused by an imbalance between myocardial oxygen supply and metabolic oxygen demand. Various forms of cardiac stress tests may be used to induce both symptoms and detect changes by way of electrocardiography (using an ECG), echocardiography (using ultrasound of the heart) or scintigraphy (using uptake of radionuclide by

8217-458: The nucleus as gamma radiation ; transferred to one of its electrons to release it as a conversion electron ; or used to create and emit a new particle ( alpha particle or beta particle ) from the nucleus. During those processes, the radionuclide is said to undergo radioactive decay . These emissions are considered ionizing radiation because they are energetic enough to liberate an electron from another atom. The radioactive decay can produce

8316-416: The proteasomal regulator SIAH3 , and the ubiquitin ligase MARCHF10 . On the ciliary aspect of the immune synapse, several of the modulated transcripts are related to ciliary length and function. Stereocilin is a partner to mesothelin , a related super-helical protein, whose transcript is also modulated in CAD. DCDC2 , a double-cortin protein, is a modulator of ciliary length. In the signaling pathways of

8415-442: The radiation produced, the amount and nature of exposure (close contact, inhalation or ingestion), and the biochemical properties of the element; with increased risk of cancer the most usual consequence. However, radionuclides with suitable properties are used in nuclear medicine for both diagnosis and treatment. An imaging tracer made with radionuclides is called a radioactive tracer . A pharmaceutical drug made with radionuclides

8514-466: The rare coronary artery disease that is more common in females, as mentioned, is a diagnosis of exclusion. Therefore, usually, the same tests are used as in any person suspected of having coronary artery disease: Stable angina is the most common manifestation of ischemic heart disease, and is associated with reduced quality of life and increased mortality. It is caused by epicardial coronary stenosis which results in reduced blood flow and oxygen supply to

8613-460: The risk of CAD. Lack of exercise has been linked to 7–12% of cases. Exposure to the herbicide Agent Orange may increase risk. Rheumatologic diseases such as rheumatoid arthritis , systemic lupus erythematosus , psoriasis , and psoriatic arthritis are independent risk factors as well. Job stress appears to play a minor role accounting for about 3% of cases. In one study, females who were free of stress from work life saw an increase in

8712-493: The risk of cardiovascular disease and death. Vegetarians have a lower risk of heart disease, possibly due to their greater consumption of fruits and vegetables. Evidence also suggests that the Mediterranean diet and a high fiber diet lower the risk. The consumption of trans fat (commonly found in hydrogenated products such as margarine ) has been shown to cause a precursor to atherosclerosis and increase

8811-552: The risk of coronary artery disease by about 25%. Life's Essential 8 are the key measures for improving and maintaining cardiovascular health, as defined by the American Heart Association. AHA added sleep as a factor influencing heart health in 2022. Most guidelines recommend combining these preventive strategies. A 2015 Cochrane Review found some evidence that counseling and education to bring about behavioral change might help in high-risk groups. However, there

8910-410: The risk of coronary artery disease. Evidence does not support a beneficial role for omega-3 fatty acid supplementation in preventing cardiovascular disease (including myocardial infarction and sudden cardiac death ). There is tentative evidence that intake of menaquinone ( Vitamin K 2 ), but not phylloquinone ( Vitamin K 1 ), may reduce the risk of CAD mortality . Secondary prevention

9009-492: The risk profile. Noninvasive imaging options include; Computed tomography angiography (CTA) (anatomical imaging, best test in patients with low-risk profile to "rule out" the disease), positron emission tomography (PET), single-photon emission computed tomography (SPECT)/nuclear stress test/myocardial scintigraphy and stress echocardiography (the three latter can be summarized as functional noninvasive methods and are typically better to "rule in"). Exercise ECG or stress test

9108-875: The shoulder, arm, back, neck, or jaw. Occasionally it may feel like heartburn . In stable angina , symptoms occur with exercise or emotional stress , last less than a few minutes, and improve with rest. Shortness of breath may also occur and sometimes no symptoms are present. In many cases, the first sign is a heart attack . Other complications include heart failure or an abnormal heartbeat . Risk factors include high blood pressure , smoking , diabetes , lack of exercise, obesity , high blood cholesterol , poor diet, depression , and excessive alcohol consumption. A number of tests may help with diagnosis including: electrocardiogram , cardiac stress testing , coronary computed tomographic angiography , biomarkers ( high-sensitivity cardiac troponins ) and coronary angiogram , among others. Ways to reduce CAD risk include eating

9207-414: The smooth, elastic lining inside a coronary artery (the arteries that supply blood to the heart muscle) develops atherosclerosis . With atherosclerosis, the artery's lining becomes hardened, stiffened, and accumulates deposits of calcium, fatty lipids, and abnormal inflammatory cells – to form a plaque . Calcium phosphate (hydroxyapatite) deposits in the muscular layer of the blood vessels appear to play

9306-490: The surrounding structures, yielding activation products . This complex mixture of radionuclides with different chemistries and radioactivity makes handling nuclear waste and dealing with nuclear fallout particularly problematic. Synthetic radionuclides are deliberately synthesised using nuclear reactors , particle accelerators or radionuclide generators: Radionuclides are used in two major ways: either for their radiation alone ( irradiation , nuclear batteries ) or for

9405-604: The technique is useful in locating ectopic parathyroid adenomas which may not be in their usual locations in the thyroid gland. The overall performance of SPECT systems can be performed by quality control tools such as the Jaszczak phantom . Radioisotope A radionuclide ( radioactive nuclide , radioisotope or radioactive isotope ) is a nuclide that has excess numbers of either neutrons or protons , giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ways: emitted from

9504-481: The tissues, this data can be incorporated into the SPECT reconstruction to correct for attenuation. It also provides a precisely registered CT image, which can provide additional anatomical information. Scatter of the gamma rays as well as the random nature of gamma rays can also lead to the degradation of quality of SPECT images and cause loss of resolution. Scatter correction and resolution recovery are also applied to improve resolution of SPECT images. In some cases

9603-637: The tracers used in SPECT emit gamma radiation that is measured directly, whereas PET tracers emit positrons that annihilate with electrons up to a few millimeters away, causing two gamma photons to be emitted in opposite directions. A PET scanner detects these emissions "coincident" in time, which provides more radiation event localization information and, thus, higher spatial resolution images than SPECT (which has about 1 cm resolution). SPECT scans are significantly less expensive than PET scans, in part because they are able to use longer-lived and more easily obtained radioisotopes than PET. Because SPECT acquisition

9702-406: The use of antibiotics is not currently supported for preventing secondary coronary heart disease. A thorough systematic review found that indeed there is a link between a CHD condition and brain dysfunction in females. Consequently, since research is showing that cardiovascular diseases, like CHD, can play a role as a precursor for dementia, like Alzheimer's disease, individuals with CHD should have

9801-501: Was insufficient evidence to show an effect on mortality or actual cardiovascular events. In diabetes mellitus , there is little evidence that very tight blood sugar control improves cardiac risk although improved sugar control appears to decrease other problems such as kidney failure and blindness . A 2024 study published in The Lancet Diabetes & Endocrinology found that the oral glucose tolerance test (OGTT)

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