Medical Imaging Diagnosis & Treatment

Diagnosis of Disease Effective decisions depend on correct diagnosis Distinguishing one disorder or disease from another Signs and symptoms Medical history Collecting information about event Present illnesses and past medical problems Physical examination Orderly evaluation of the body and its function Noninvasive techniques and other vital signs (pulse) Medical Imaging used for diagnostic and follow-up purposes

History  Anatomic imaging began at the turn of the century with Wilhelm Roentgen's discovery of X-ray radiation in 1896  Evolved into computerized systems that allow scientist and physicians to look inside the body with amazing accuracy Allow visualization of structures inside the body Diagnosis of anatomical and physiological disorders No trauma or surgery  Advances in medical diagnosis go hand in hand with anatomic imaging  Conventional radiography (X-rays) have been in use since the late 1940’s

Cross-sectional Anatomy  Variety of machines & techniques used, depending on body part being examined  In order to visualize and study the structural arrangements of various organs, the body may be sectioned (cut) and diagrammed accordingly to the planes of reference  The structural arrangements of the body produced by imaging technologies are presented as transverse, sagittal, or frontal sections Sagittal & frontal sections are usually less difficult to understand

Cross-sectional Anatomy  The sagittal plane divides the body into unequal right and left portions. The midsagittal plane passes lengthwise through the midplane of the body, dividing it into equal right and left halves.  Frontal or coronal plane also pass lengthwise and divide the human body into front and back portions.  Transverse planes, also called horizontal, or cross-sectional planes, divide the body into superior (upper) and inferior (lower) portions.

Careers in Medical Imaging  Imaging for medical purposes involves a team of professionals Radiologists (imaging expert) Radiographers (X-ray technologists) Sonographers (ultrasound technologists) Medical Physicists Nurses Biomedical Engineers

Medical Imaging Techniques X-rays Computerized tomography (CT) scans Magnetic resonance imaging (MRI) scans Positron emission tomography (PET) scans Ultrasound images Nuclear Imaging Digital subtraction angiography images (DSA) Some imaging tests are painless & easy Some techniques require you to stay still for long periods of time Some tests involve exposure to small amounts of radiation

X-rays - Radiography First medical imaging tool Form of electromagnetic radiation  Different absorption rates of different tissues  Radiation passes through relatively less dense structures, but denser tissues and structures absorb the radiation Images of parts of the body in different shades of black and white  Dense structures (bone) will appear white, soft tissue will appear gray, and empty space (air) will appear black Images are two-dimensional Useful for producing images of bone and the dense, wet lungs of pneumonia sufferers Mammograms use X-rays to look for breast cancer

X-rays Contrast Study: Adding radio-opaque substances (substances X-rays cannot penetrate), such as barium, allows imaging of certain soft tissues.

CT Scan (CAT) Computed Tomography or Computed Axial Tomography Literally means to cut or section (Gr. tomos) the body and use the computer to write (Gr. grapho) a picture of the section Invented in 1972 by Hounsfield and Cormack CT scans also involve X-rays, however, the rays are delivered in multiple directions A patient is placed into a scanner and moves slowly through a circular rim A computer combines the data of each X-ray shot from multiple angles and forms two-dimensional slices of the patient’s body Useful for observing cross sectional pictures of soft tissue, bone, and blood vessels.

A.D – Alzheimer’s disease

MRI Major Breakthrough in Medical Imaging Nikola Tesla discovered the Rotating Magnetic Field in 1882, MRI was developed in 1977 A patient is placed into a scanner that produces a very powerful magnetic field, which affects the nuclei of the atoms in the patient's body The magnetic field produced by the scanner causes the hydrogen protons in the patient's body to align in the same direction  A second magnetic field is established that raised the energy of hydrogen protons and ultimately causes them to release energy detected by sensors in the scanner Can form high contrast images of soft tissue, data is processed by a computer to form an image

Advantages of MRI MRI does not expose the patient to radiation Produces images showing the contrast between different tissues, MRI scans are often more detailed than CT scans and the contrast between healthy and abnormal tissues is greater Areas containing the least amounts of water (e.g. bone) appear dark on MRI scans, while those containing most water (e.g. fatty tissue) appear bright. MRI scans are especially useful for investigating disorders of the brain and spinal cord, the heart and blood vessels, and the bones and joints. In some cases, a chemical called an MRI contrast agent is injected into a vein before the scan, which improves the contrast between different types of body tissue, making it easier to spot any abnormalities. Medical images appear in shades of black, white, gray… but can often be combined with other types of scans such as PET, and the images are overlaid

Drawbacks of MRI Unsuitable for people with any type of metal in their body (magnetic fields can interfere with those devices), Not to be used in patients with pacemaker, Can take a long time Patients may feel claustrophobic, they need to remain still on a flat table while slowly moving through a narrow tube. Expensive

Positron Emission Tomography (PET) Scan Uses properties of atomic nuclei Technology behind PET was developed in the 1970’s Images represent biological processes in the body In PET imaging, a tracer is injected into the body The tracer is a molecule used in metabolism which contains a radioactive isotope with a short half-life that decays by emitting positrons (a type of antimatter)  Tracer can be taken orally, inhaled as a gas, or injected into the vein. When a positron encounters an electron in the body, they annihilate and emit a pair of photons (light particles) which are detected by the PET machine.  The PET image shows where the tracer molecule is found and in what concentration

PET continued PET imaging is used in oncology (cancer) and for detecting certain brain diseases. PET scans are commonly combined with CT or MRI scans in a single medical imaging system that can show both anatomy and function. Images appear in color with different cell activity shown in reds, yellows, blues, etc.

PET/CT Scan Overlay Cancer patient before & after treatment