Imaging is the use of various techniques to create images of the human body for diagnostic and therapeutic purposes. The term “imaging” encompasses a wide range of modalities, including X-ray, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine.
X-ray is the oldest and most commonly used form of medical imaging. X-rays are a type of electromagnetic radiation with short wavelength and high energy. When x-rays pass through the body, they interact with tissues in different ways depending on the tissue’s density. Dense tissues such as bone absorb more x-rays than less dense tissues such as soft tissue or air. This difference in absorption results in an image that shows contrast between different types of tissues.
Ultrasound is another common imaging modality that uses sound waves to create images of the body. Ultrasound waves are produced by a transducer that is placed against the skin. The waves bounce off internal structures and are captured by the transducer, which converts them into electrical signals that are then displayed on a screen as an image. Ultrasound can be used to visualize many different structures within the body, including muscles, tendons, joints, blood vessels, and organs. It is often used for pregnant women to assess fetal health and development or to guide needle biopsies and other procedures.
CT scanning combines special x-ray equipment with sophisticated computers to produce three-dimensional (3D) images of internal organs and structures. CT scans are often used to diagnose cancer or other diseases because they can show very small abnormalities that might not be detectable on regular x-rays or ultrasound exams. CT scans can also be used to guide needle biopsies or other interventions because of their high level of detail.
MRI uses powerful magnets and radio waves instead of x-rays to produce detailed 3D images of internal organs and structures without using ionizing radiation . MRIs provide excellent contrast between different types of tissue so they are often used to evaluate problems with the brain , spine , joints , heart , or blood vessels . MRIs can also be used during some interventional procedures , such as biopsies , surgeries , or implantations . MRI contrast agents may be given intravenously before the exam begins in order to improve visualization of certain structures .
Molecular imaging is a new field that combines traditional medical imaging with molecular biology . Molecular imaging allows doctors to see how cells function at a very small scale by tracking specific molecules within those cells . This information can help doctors diagnose disease earlier , choose more effective treatments , monitor patients for side effects from treatment