Imaging in Inflammatory Disorders and Infection Flashcards
What is molecular imaging?
Molecular imaging is a technique that visualizes and measures biological processes at the molecular and cellular levels in the body. It uses radiotracers to target specific molecules, allowing for non-invasive, real-time imaging of diseases like cancer, neurological disorders, and cardiovascular diseases. Common techniques include PET, SPECT, and MRI. Molecular imaging helps in early disease detection, treatment monitoring, and understanding disease mechanisms, providing valuable insights into patient care.
Radionuclide imaging versus x-rays
Radionuclide imaging is better for assessing function and metabolism, whereas X-rays excel at providing detailed images of anatomical structures.
Radionuclide imaging is more specialized and offers a deeper insight into disease processes, while X-rays are faster and commonly used for routine imaging like bone fractures.
Both techniques have radiation exposure, but radionuclide imaging involves the use of radioactive materials, which require additional safety protocols.
Properties of an ideal isotope
Appropriate half-life for sufficient imaging time without prolonged radiation exposure.
Emits detectable radiation that can be easily captured by imaging devices.
Low radiation dose to minimize risk to the patient.
Selective targeting of specific tissues or organs for more accurate diagnostics.
Efficient production in reliable, scalable quantities.
Minimal toxicity and biocompatibility.
Favorable chemical properties for use in radiopharmaceuticals with long shelf life.
Clear imaging resolution for high-quality images.
Biological clearance from the body with minimal accumulation.
Radiopharmaceuticals, gamma camera, image production
Radiopharmaceuticals are radioactive compounds used in medical imaging, consisting of a radioisotope bound to a biologically active molecule that targets specific tissues. These compounds emit radiation, such as gamma rays, which can be detected by a gamma camera to produce images of internal processes.
A gamma camera detects the radiation emitted by the radiopharmaceutical, converting it into electrical signals that form an image. This helps visualize functional and metabolic activities in organs or tissues, such as in cancer detection, cardiac imaging, and neurological studies.
Radiopharmaceuticals combined with gamma cameras enable detailed, non-invasive imaging of diseases at the molecular level, aiding in diagnosis and treatment monitoring.
Single photon emission tomography (SPECT)
Single Photon Emission Computed Tomography (SPECT) is a nuclear imaging technique that captures 3D images of the body’s internal functions. It works by injecting a radiopharmaceutical that emits gamma rays, which are detected by a rotating gamma camera. These images are then reconstructed to show the distribution of the radiopharmaceutical, providing functional information about organs or tissues.
SPECT is used in cardiology to assess blood flow, in neurology to study brain function, and in oncology for detecting tumors. It offers valuable functional insights but has lower resolution compared to other imaging techniques like CT or MRI and involves the use of radioactive materials.
Positron emission tomography (PET)
Positron Emission Tomography (PET) is an imaging technique that provides functional, molecular-level insights into the body by detecting metabolic activity. A radiotracer, often fluorodeoxyglucose (FDG), is injected into the body, and as it emits positrons, gamma rays are detected to create 3D images of areas with high metabolic activity, such as tumors.
PET is widely used in cancer detection, neurological disorders (e.g., Alzheimer’s), and cardiac assessments. It offers high sensitivity for early disease detection and monitoring but has lower spatial resolution compared to other imaging techniques and requires radioactive tracers, making it expensive and less accessible.
Examples of inflammatory and infectious diseases
Inflammatory diseases occur when the immune system causes inflammation without infection, examples include rheumatoid arthritis, inflammatory bowel disease, psoriasis, lupus, multiple sclerosis, and asthma.
Infectious diseases are caused by pathogens such as bacteria, viruses, fungi, or parasites. Examples include influenza, tuberculosis, HIV/AIDS, malaria, pneumonia, hepatitis, and sepsis.
Both types involve immune system activation, but inflammatory diseases result from abnormal immune responses, while infectious diseases are triggered by external pathogens.
Discuss a little about radiation in medical imaging
Radiation in medical imaging uses ionizing radiation (X-rays, gamma rays) to create images of the body for diagnosis and treatment. Common techniques include X-rays, CT scans, and nuclear medicine (SPECT and PET), which help detect conditions like cancer, heart disease, and neurological disorders.
While these methods provide valuable, non-invasive diagnostic information, ionizing radiation carries risks such as increased cancer risk and tissue damage. To minimize these risks, imaging should only be used when necessary (justification) and with the lowest possible radiation dose (optimization).
