What is the difference between a CAT scan, an MRI and an X-ray? What is the difference between a CAT scan, an MRI and an X-ray?

These are the most common radiological examinations. When are they used and how are they different? Read on to learn about each.

  •  Computerized Axial Tomography (CAT). Also known as a CAT scan, this exam uses X-rays that come from different angles to create cross-sectional images of the body. This exam is used to find bone lesions and internal lesions, it is also used when a hemorrhage, tumor or certain infections are suspected.
  •  Magnetic Resonance Imaging (MRI). Instead of X-ray radiation, MRIs use a magnetic field and radiofrequency waves. While they do not show a patient’s soft tissues, they do provide information that can only be seen in an MRI, aiding in the diagnosis of abnormal blood vessels, benign or malignant tumors, cancer, birth defects in certain organ and conditions involving internal tissues.
  •  X-rays. This is the simplest exam. Similar to a CAT scan, a single direct X-ray beam is used. This exam helps detect abnormalities in the bones, thorax, teeth, skull and joints.

According to the U.S. National Library of Medicine, other common radiological examinations include:

  • A fluoroscopy scan, which includes the upper gastrointestinal (GI) tract and involves a barium enema
  •   Mammography
  •  Nuclear medicine exams, which include bone scans, thyroid scans and thallium stress tests
  •  Positron emission tomography, also called PET imaging or a PET scan, or when combined with computed tomography, a PET/CT scan
  •   Ultrasound

November 8 is the International Day of Radiology, which celebrates the discovery of X-rays in 1895, when the scientist Wilhelm Conrad Röntgen was able to detect foreign bodies and capture them in photographic films.