Resource Center – Glossary
Most Frequently Ordered Imaging
1. Lumbar – Lower Back. Common Injury - Bulging or Herniated Disc
2. Cervical - Upper Neck. Common Injury – Cervical Disc Degeneration
3. Thoracic – Mid-Back. Common Injury – Thoracic Outlet Syndrome
4. Upper Joint Extremities - Finger, Hand, Wrist, Elbow, Humerus, Scapula, Shoulder,
Clavicle. Common Injury – Rotator Cuff Tear
5. Extremities - Hands, Fingers, Elbows, Wrists, Knees, Feet and Ankles. Common Injury – Carpal Tunnel Syndrome
Most Commonly Used MRI Equipment
- High Field Closed Magnets 1.0T – 3.0T
The closed magnet configuration refers to a tube-like tunnel, which was the
original shape of the most MRI scanners. The field strengths of these closed
scanners range from .35 Tesla up to 3.0 Tesla. All high field superconducting MRI scanners
are of the closed configuration type
- High Field Open Magnets .6T – 1.5T
Open magnets, which have been developed more recently, typically are either
permanent magnets or resistive electromagnets. The typical open configuration
consists of two large, rounded, horizontally oriented metal discs which are the
poles of the magnet between which the patient is placed. These magnets have no
sides and are thus “open”. In general, open magnets are considered low to midfield
and have magnetic field strengths of 0.2 to 0.7 Tesla.
- Stand-Up MRI
The Stand Up MRI allows all parts of the body, particularly the spine and joints, to be imaged in a weight-bearing state. The revolutionary scanner features the only MRI-compatible, motorized, multi-positional, patient positioning system, which has been engineered to be fully functional inside the scanner’s magnetic field. It can position the patient for the full range of conventional “lie-down” MRI scanning, or upright for weight-bearing studies.
Most Commonly Used Diagnostic Tests
- MRI – (Magnetic Resonance Imaging) MRI uses a large circular magnet and radio waves to generate signals from protons in the body. These signals are used to construct images of internal structures
- CT – (Computerized Axial Tomography) A series of X-rays that show the human body in slices. The X-ray mechanism, which surrounds the body, “inches” its way along the area being examined, taking multiple tomograms. The computer is used to turn the tomograms into pictures.
- Nuclear Medicine - Nuclear medicine is a branch of medical imaging that uses small amounts of radioactive material to diagnose and determine the severity of or treat a variety of diseases, including many types of cancers, heart disease, gastrointestinal, endocrine, neurological disorders and other abnormalities within the body. Because nuclear medicine procedures are able to pinpoint molecular activity within the body, they offer the potential to identify disease in its earliest stages as well as a patient’s immediate response to therapeutic interventions.
- X-Rays – The wave length of this energy is shorter than those of visible light. X-rays possess the properties of penetrating most substances, of acting on a photographic film or plate, and of causing a fluorescent screen to give off light. In low doses X-rays are used for making images that help to diagnose disease.
CT vs MRI
|Application:||Suited for bone injuries, lung and chest imaging ,cancer detection||Suited for ligament and tendon injury, spinal cord injury, brain tumors|
|Principle:||X-ray attenuation was detected by detector & DAS system, follow by math model (back projection model) to calculate the value of pixelism then become an image.||Makes use of the fact that body tissue contains lots of water (and hence protons) which gets aligned to large magnetic field to produce net MDM vector. The decay of MDM is detected as MR signal.|
|Details of soft tissues:||Less tissue contrast compared to MRI||Much higher detail in the soft tissues|
|Details of bony structures:||Provides good details about bony structures||Less detailed compared to CT scan|
|Ability to change the imaging plane without moving the patient:||with capability of MDCT, after helical scan with Multi-plane Reformation function. Operator can construct any plane.||MRI machines can produce images in any plane|
|Principal used for imaging:||Uses X-rays for imaging||Uses large external field, RF pulse and 3 different gradient fields|
|Effects on the body:||Despite being small, CT can pose the risk of irradiation.||No biological hazards have been reported with the use of the MRI.|
|Acronym for:||Computed tomography||Magnetic Resonance Imaging|
|Scope of application:||CT can outline bone inside the body very accurately.||MRI is more versatile than the X-Ray and is used to examine a large variety of medical conditions.|
|About:||CT Scan or Computed tomography is a medical imaging obtained using X-rays. The radiation is passed through the body and received by a detector and then integrated by a computer to obtain a cross sectional image that is displayed on the screen.||Magnetic resonance imaging (MRI) is a medical imaging technique most commonly used in radiology to visualize detailed internal structure and limited function of the body.|