Difference Between Pet And Spect Pdf
File Name: difference between pet and spect .zip
A PET scan of the heart is a noninvasive nuclear imaging test.
PET and SPECT
Nuclear medicine is a medical specialty that uses radioactive tracers radiopharmaceuticals to assess bodily functions and to diagnose and treat disease.
Specially designed cameras allow doctors to track the path of these radioactive tracers. Radioactive tracers are made up of carrier molecules that are bonded tightly to a radioactive atom. These carrier molecules vary greatly depending on the purpose of the scan. For example, in cases where doctors need to know the exact source of intestinal bleeding, they may radiolabel add radioactive atoms to a sample of red blood cells taken from the patient. Any accumulation of radioactivity in the intestines informs doctors of where the problem lies.
For most diagnostic studies in nuclear medicine, the radioactive tracer is administered to a patient by intravenous injection. However a radioactive tracer may also be administered by inhalation, by oral ingestion, or by direct injection into an organ.
The mode of tracer administration will depend on the disease process that is to be studied. The 3D images are computer generated from a large number of projection images of the body recorded at different angles. SPECT imagers have gamma camera detectors that can detect the gamma ray emissions from the tracers that have been injected into the patient.
Gamma rays are a form of light that moves at a different wavelength than visible light. The cameras are mounted on a rotating gantry that allows the detectors to be moved in a tight circle around a patient who is lying motionless on a pallet.
PET scans also use radiopharmaceuticals to create three-dimensional images. A positron is a particle with roughly the same mass as an electron but oppositely charged.
These react with electrons in the body and when these two particles combine they annihilate each other. This annihilation produces a small amount of energy in the form of two photons that shoot off in opposite directions.
The detectors in the PET scanner measure these photons and use this information to create images of internal organs. Click here to watch a short video about how PET scans work. SPECT scans are primarily used to diagnose and track the progression of heart disease, such as blocked coronary arteries. There are also radiotracers to detect disorders in bone, gall bladder disease and intestinal bleeding.
SPECT agents have recently become available for aiding in the diagnosis of Parkinson's disease in the brain, and distinguishing this malady from other anatomically-related movement disorders and dementias. The major purpose of PET scans is to detect cancer and monitor its progression, response to treatment, and to detect metastases.
Glucose utilization depends on the intensity of cellular and tissue activity so it is greatly increased in rapidly dividing cancer cells.
In fact, the degree of aggressiveness for most cancers is roughly paralleled by their rate of glucose utilization. In the last 15 years, slightly modified radiolabeled glucose molecules F labeled deoxyglucose or FDG have been shown to be the best available tracer for detecting cancer and its metastatic spread in the body. Recently, a PET probe was approved by the FDA to aid in the accurate diagnosis of Alzheimer's disease, which previously could be diagnosed with accuracy only after a patient's death.
In the absence of this PET imaging test, Alzheimer's disease can be difficult to distinguish from vascular dementia or other forms of dementia that affect older people. The total radiation dose conferred to patients by the majority of radiopharmaceuticals used in diagnostic nuclear medicine studies is no more than what is conferred during routine chest x-rays or CT exams.
There are legitimate concerns about possible cancer induction even by low levels of radiation exposure from cumulative medical imaging examinations, but this risk is accepted to be quite small in contrast to the expected benefit derived from a medically needed diagnostic imaging study. Like radiologists, nuclear medicine physicians are strongly committed to keeping radiation exposure to patients as low as possible, giving the least amount of radiotracer needed to provide a diagnostically useful examination.
Research in nuclear medicine involves developing new radio tracers as well as technologies that will help physicians produce clearer pictures. A bacterial infection is a common complication of implanting a medical device into the body. With more patients receiving device implants than ever before, infections from implants are a growing problem. Currently, these types of infections are diagnosed based on physical exam results and microbial cultures. However, such techniques are only useful for detecting late stage infections, which usually have already become difficult to treat.
Conversely, medical devices may be needlessly removed when doctors mistake inflammation that is a normal consequence of surgery with inflammation due to an infection. NIBIB is currently supporting research to develop a new family of PET imaging contrast agents that are taken up specifically by bacterial cells, but not human cells. Such imaging agents would allow doctors to visualize early-stage bacterial infections so they can be easily treated, thereby reducing the number of implanted devices that are unnecessarily removed.
They also have the potential to be used for diagnosing infections not associated with medical devices, for example, those affecting the heart or lungs. However, the small region in the brain that must be imaged requires a dedicated brain SPECT imager with special gamma cameras to provide high resolution, which adds to the cost of the procedure.
What are radioactive tracers? What are nuclear medicine scans used for? Are there risks? What is nuclear medicine? Fused CT-PET scans more clearly show tumors and are therefore often used to diagnose and monitor the growth of cancerous tumors. PET contrast agents designed to detect bacterial infections reveal E. Developing new tracers A bacterial infection is a common complication of implanting a medical device into the body.
Reviewed July Program Areas Nuclear Medicine.
PET and SPECT Scanners
Nuclear medicine imaging modalities, such as single-photon emission computed tomography SPECT and positron emission tomography PET , utilize radioisotope labeled biomolecules, and detection of gamma rays produced via radioactive decay, in order to generate 3D functional images of the body . While these two modalities are not identical, the theoretical principles and practical imaging procedure on which they operate is largely conserved Figure 1. In both, radioactive biomolecules radiotracers synthesized from radionuclides elemental radioisotopes are first administered to the patient. Following radiotracer administration, and prior to scanning, patients are typically asked to sit quietly for a period of time in order to allow the radiotracer to mobilize to, and interact with, the tissue region of interest. During this waiting period, patients are asked to refrain from physical movement to prevent radiotracers from concentrating in moving organs skeletal muscles, heart, etc.
Positron emission tomography PET  is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes , and in other physiological activities including blood flow , regional chemical composition, and absorption. Different tracers are used for various imaging purposes, depending on the target process within the body. For example, 18F-FDG is commonly used to detect cancer , NaF-F18 is widely used for detecting bone formation, and oxygen is sometimes used to measure blood flow. PET is a common imaging technique , a medical scintillography technique used in nuclear medicine. Gamma rays are emitted and detected by gamma cameras to form a three-dimensional image, in a similar way that an X-ray image is captured. PET scan images can be reconstructed using a CT scan performed using one scanner during the same session. One of the disadvantages of a PET scanner is its high initial cost and ongoing operating costs.
Nuclear medicine is a medical specialty that uses radioactive tracers radiopharmaceuticals to assess bodily functions and to diagnose and treat disease. Specially designed cameras allow doctors to track the path of these radioactive tracers. Radioactive tracers are made up of carrier molecules that are bonded tightly to a radioactive atom. These carrier molecules vary greatly depending on the purpose of the scan. For example, in cases where doctors need to know the exact source of intestinal bleeding, they may radiolabel add radioactive atoms to a sample of red blood cells taken from the patient.
seen, for example, in the case of cardiac PET vs. SPECT. Coronary perfusion and myocardial viability are most commonly In this paper, the first three sections compare capabi- lities in PET and /3D05 proceedings. pdf. 98 Mawlawi O.
Positron Emission Tomography (PET)
Corresponding author. Recent developments in the imaging techniques of positron emission tomography PET and single photon emission computed tomography SPECT now allow the non-invasive tracking of such molecular targets of known relevance to ND in vivo. This article summarizes recent findings of PET and SPECT studies using these novel methods, and discusses their potential role in the field of drug development for ND as well as future clinical applications in regard to differential diagnosis of ND and monitoring of disease progression. Descriptors: Positron emission tomography; Single photon emission tomography; Neurodegenerative diseases; Neuroinflammation; Brain lipid metabolism.
Oyebola O. Schindler, Lihui Wei, R. Glenn Wells, Terrence D.
Дверь приоткрылась на несколько сантиметров.
Стратмор выдержал паузу и посмотрел ей прямо в. - Чтобы он получил второй ключ. - Что еще за второй ключ. - Тот, что Танкадо держал при .
Хейл наклонил голову набок, явно заинтригованный такой скрытностью. И, как бы желая обратить все в игру, сделал еще один шаг. Но он не был готов к тому, что произошло в следующее мгновение. Сохраняя ледяное спокойствие, Сьюзан ткнула указательным пальцем в твердокаменную грудь Хейла и заставила его остановиться. Хейл в шоке отпрянул, поняв, что она не шутит: Сьюзан Флетчер никогда еще до него не дотрагивалась, даже руки не коснулась. Правда, это было не то прикосновение, какое он рисовал в воображении, представляя себе их первый физический контакт, но все же… Хейл долго с изумлением смотрел на нее, затем медленно повернулся и направился к своему терминалу.
Стратмор выключил телефон и сунул его за пояс. - Твоя очередь, Грег, - сказал. ГЛАВА 81 С мутными слезящимися глазами Беккер стоял возле телефонной будки в зале аэровокзала. Несмотря на непрекращающееся жжение и тошноту, он пришел в хорошее расположение духа. Все закончилось. Действительно закончилось.
SPECT detection uses a sheet of detectors that detect single gamma rays, whereas PET uses a ring of detectors that detects pairs of photons. As SPECT detects all single gamma rays, a collimator is required to reduce scatter, as described in the SPECT instrumentation page, while in PET no collimator is required.
Ты не сделаешь ничего подобного! - оборвал его Стратмор. - Этим ты лишь усугубишь свое положе… - Он не договорил и произнес в трубку: - Безопасность. Говорит коммандер Тревор Стратмор. У нас в шифровалке человек взят в заложники. Быстро пришлите сюда людей.
Подумала она удивленно и с облегчением и попыталась выскользнуть из-под. - Милый, - глухо прошептала. - Позволь, я переберусь наверх. - Но немец даже не шевельнулся.
Он постучал. - Hola. Тишина. Наверное, Меган, подумал .
Постарайтесь пройти по нему до конца. Сьюзан вздохнула: - Программа принимает ключ только в цифровой форме. Мне кажется, что тут содержится некий намек на то, что это за цифра.