This page will provide information for the terms utilized within this website.
CT – Computed Tomography
Computed tomography (CT), originally known as computed axial tomography (CAT or CAT scan) and body section roentgenography, is a medical imaging method employing tomography where digital geometry processing is used to generate a three-dimensional image of the internals of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation. The word “tomography” is derived from the Greek tomos (slice) and graphia (describing). CT produces a volume of data which can be manipulated, through a process known as windowing, in order to demonstrate various structures based on their ability to block the x-ray beam. Although historically the images generated were in the axial or transverse plane (orthogonal to the long axis of the body), modern scanners allow this volume of data to be reformatted in various planes or even as volumetric (3D) representations of structures.
MRI – Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) is an imaging technique used primarily in medical settings to produce high quality images of the inside of the human body. MRI is based on the principles of nuclear magnetic resonance (NMR), a spectroscopic technique used by scientists to obtain microscopic chemical and physical information about molecules. The technique was called magnetic resonance imaging rather than nuclear magnetic resonance imaging (NMRI) because of the negative connotations associated with the word nuclear in the late 1970’s. MRI started out as a tomographic imaging technique, that is it produced an image of the NMR signal in a thin slice through the human body. MRI has advanced beyond a tomographic imaging technique to a volume imaging technique.
PET/CT – Positron Emission Tomography combined with Computed Tomography
Positron emission tomography, also called PET imaging or a PET scan, is a diagnostic examination that involves the acquisition of physiologic images based on the detection of radiation from the emission of positrons. Positrons are tiny particles emitted from a radioactive substance administered to the patient. The subsequent images of the human body developed with this technique are used to evaluate a variety of diseases. (see CT above)
SPEC/CT – Spectroscopy combined with Computed Tomography
Spectroscopy is the study of spectra, that is, the dependence of physical quantities on frequency. Spectroscopy is often used in physical and analytical chemistry for the identification of substances, through the spectrum emitted or absorbed. A device for recording a spectrum is a spectrometer. Spectroscopy can be classified according to the physical quantity which is measured or calculated or the measurement process.(see CT above)
Radiology is the medical specialty that utilizes imaging technologies to diagnose and sometimes treat diseases. Traditionally it was the branch of medical science dealing with the medical use of X-rays emitted by X-ray machines or other such radiation devices for the purpose of obtaining visual information as part of medical imaging. Radiologists now also use other imaging technologies (such as ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI).) to diagnose or treat disease. Interventional radiology is the performance of (usually minimally invasive) medical procedures with the help of medical imaging.
Radiographs (or Roentgenographs, named after the discoverer of X-rays, Wilhelm Conrad Roentgen (1845-1923)) are often used for evaluation of bony structures and soft tissues. Fluoroscopy and Angiography are special applications of X-ray imaging, where a fluorescent screen or image intensifier tube is connected to a closed-circuit television system, which allows real-time imaging of structures in motion or augmented with a radiocontrast agent. Radiocontrast agents are administered, often swallowed or injected into the body of the patient, to help delineate anatomy such as the blood vessels, the genitourinary system or the gastrointestinal tract. Specific radiocontrast agents are used for specific types of evaluations; for example, barium in a suspension is administered into the gastrointestinal tract and imaged with fluoroscopy or radiography. Radiocontrast agents, which strongly absorb X-ray radiation, in conjunction with the real-time imaging allows demonstration of dynamic processes, such as peristalsis in the digestive tract or blood flow in arteries and veins.
Medical ultrasonography uses ultrasound (high-frequency sound waves) to visualize soft tissue structures in the body in real time. No ionizing radiation is involved, but the quality of the images obtained using ultrasound is highly dependent on the skill of the person (ultrasonographer) performing the exam. The use of ultrasound in medical imaging has developed mostly within the last 30 years. The first ultrasound images were static and two dimensional (2D), but with modern-day ultrasonography 3D reconstructions can be observed in real-time; effectively becoming 4D.
VCT – Volume Computed Tomography
Volume coverage, not slices, changes the way anatomy is imaged and how studies are performed. The LightSpeed ™ VCT Series of scanners combine superior resolution with outstanding coverage making the imaging of difficult patients or procedures more routine.
The LightSpeed ™ VCT Series groundbreaking technology opens the door to new procedures while improving the imaging of existing ones. Improved resolution, reduced acquisitions per study, shorter patient-breath-holds along with the platform’s power to routinely support faster coverage with sub millimeter resolution, allow more robust and repeatable studies. This is critical in emerging procedures such as Coronary Angiographic studies.
Courtesy GE Healthcare Technologies ™