As we’re made mostly of fat and water, there’s plenty of hydrogen to detect. Excited hydrogen ions emit signals toward the MRI scanner which, based on the intensity of the signal, creates a gray-scale image. MRIis an imaging modality that, besides anatomy, can also show physiological processes in the body (functional MRI - fMRI). MRI works by using magnetic fields and radiofrequency pulses to excite protons (hydrogen ions) in our body. Furthermore, CT imaging can be combined with radiological contrasts which act as visualisation aids. CT machines can also switch between the “bone window” and “soft tissue window”, depending on which structures we want to observe. These techniques offer variations in the “slice” thickness and the radiation dose used to create the image.

There are many CT techniques, such as single slice CT (SSCT), spiral CT and multi slice CT (MSCT). The advantages of CT over x-ray radiography are that it enables a three-dimensional insight into the body, giving a more accurate presentation of the area of interest. If the density is altered, we express that by using basic CT terminology hyperdense, hypodense or isodense when compared to some other structure. Every tissue in the body has its normal density familiar to radiologists. Density is expressed in Hounsfield unit (HUs), which spans from +1000 for bones (bright), 0 for water (gray), to -1000 for air (dark). As CT uses x-rays, the image also depends on tissue density. This gives us a cross-sectional slice of the specific body region. It rotates around a stationary person creating multiple cross-sectional images, which can then be rendered into a 3D image. CT works by using x-rays too but the machine is more advanced. Radiography is most often used in chest x-rays (cxr), abdominal and skeletal x-rays.Īntrum of Highmore, Maxillary paranasal sinusĬomputed tomography (CT), earlier referred to as computed axial tomography (CAT), is another non-invasive imaging procedure. X-ray continues to be a highly utilized medical imaging modality as it offers high spatial resolution and enables comprehensive visualization of structures which can be hard to perceive in axial (cross sectional) perspectives.

Lucency refers to dark (black) areas of the graph.Density or opacity refers to bright (white) areas of the graph.These rules translate into a basic radiographic language Other tissues are somewhere in between of this grayscale. Dense tissues ( bone) will absorb most of the rays and come out on the radiograph as white, while air doesn’t block any rays and comes out as black. Thus creating a 2 dimensional (flat) image called a radiograph. These waves pass through the person’s body, with some rays being absorbed by the tissues and others reaching the radiographic film behind. Radiography is the imaging method which uses x-rays or electromagnetic waves. Spectrum of imaging methods used for examining the function of specific body parts by using gamma-radiation emitting radiopharmaceuticals (radioactive pharmaceuticals) Key facts X-ray radiographyĪn imaging technique which uses beams of electromagnetic waves (x-rays) to produce radiographs that depict the tissues in two dimensions based on their density.Ĭommonly used for assessment of chest, abdominal and skeletal anatomy.Īn imaging technique which uses X-ray beams to produce images that depict the tissues in two and three dimensions based on their density.Ĭommonly used for assessment of musculoskeletal system, parenchyma of solid organs, distribution of body fluids.Īn imaging technique which uses radio-waves and magnetic fields to produce images based on the tissue’s proton (hydrogen) levels.Ĭommonly used for examination of soft and nervous tissues.Īn imaging method which uses high frequency sound waves to depict tissues based on their density. In this page we have gathered everything you need to get started with medical imaging. Don’t worry if you can’t give a perfect analysis initially, as besides knowledge, it takes practice to become an imaging master. Even if you haven’t, we’ve prepared this page in an easily digestible way. We suggest you check out our Kenhub material on this topic. Scan interpretation will be a lot easier for you if you have analyzed cross-sectional anatomy images. The preferred method depends on the structures we wish to examine. MRI is the safest among the three, although each technique has its benefits. X-ray and CT require the use of ionizing radiation while MRI uses a magnetic field to detect body protons. The most frequently used imaging modalities are radiography ( X-ray), computed tomography ( CT) and magnetic resonance imaging ( MRI). It gathers several non-invasive methods for visualizing the inner body structures. Radiological anatomy is where your human anatomy knowledge meets clinical practice.

Mri vs xray