B - Alternative Imaging modalities Flashcards
What modalities exist within radiology?
Radiography
Computed Tomography
Fluoroscopy
Nuclear Medicine
Ultrasound
Interventional Radiography
Cardiac Radiography
Theatre Imaging
Magnetic Resonance Imaging
DEXA
How does Ultrasound work?
Uses sound waves to assess anatomy and pathology
Uses a small transducer/probe and Ultrasound gel
The transducer sends and receives inaudible, high frequency sound waves
Some tissues absorb sound waves and some deflect them
As the sound waves interact with organs, fluid and tissues the transducer records changes in the pitch of the sound wave
From these changes an image is created
What different types of Ultrasound are there?
Skin Surfaces
Transvaginal – To assess uterus and ovaries
Transrectal – To assess prostate conditions
Transoesophageal Echocardiogram – For obtaining clear heart images
Doppler – Images blood flow through vessels
Bone Sonography – Helps to identify Osteoporosis
3D/4D Imaging
What are the Pro’s of Ultrasound?
Safe
Non invasive
Quick
No ionising radiation
Portable
Easy to Use
Widely available
Cheap compared to other modalities
Real time imaging
What are the con’s of ultrasound?
Sound waves do not transmit through dense areas such as bone
Can Be Uncomfortable
Do not travel well through air I.e bowel
What Can Ultrasound Demonstrate?
Structure and movement of internal organs
Blood flow and blood vessels
Guide needle biopsies
Diagnose heart conditions
Confirming and Dating Pregnancy
Diagnosing conditions of the Liver, Gall Bladder, Spleen, Pancreas, Kidneys, Bladder, Uterus, Ovaries, Eyes, Thyroid and Testicles
Detect and Treat soft tissue injuries
What can you see on MSK Ultrasound?
Tendon tears
Tendonitis in the Rotator Cuff, Achilles Tendon and Others
Muscle tears
Masses
Fluid Collections/Effusions
Ligament sprains and tears
Inflammation
Nerve Entrapments I.e. Carpal Tunnel Syndrome
Benign and malignant Soft Tissue Tumours
Ganglion Cysts
Hernias
Foreign Bodies
Dislocation of the Hip in Infants
Torticollis
How do you interpret ultrasounds?
Fluid = BLACK
Tissue = GREY
The MORE DENSE the tissue is, the BRIGHTER WHITE it will appear
Bone will always be the brightest
Usually described by a tissues Echogenicity (ability to bounce soundwaves)
HYPERECHOGENIC = brighter as they have higher echogenicity
HYPOECHOGENIC = darker as tissues have lower echogenicity
ANECHOGENIC = areas that lack any echogenicity appear totally dark
Contrast enhancement can be used in the form of microbubbles
What is Computed Tomography?
Cross sectional Imaging giving “slices” of the body
CT is based on the fundamental principle that the density of the tissue passed by the X-ray beam can be measured from the calculation of theattenuation coefficient
CT allows the reconstruction of the density of the body, by two-dimensional section perpendicular to the axis of the acquisition system
The emitter of X-rays rotates around the patient and the detector, placed in diametrically opposite side, picks up the image of a body section (beam and detector move in synchrony).
What are the Pro’s of Computed Tomography?
Quick
Widely available
Ideal for whole body trauma scanning
Few restrictions
Comprehensive
Accurate
Painless
Planning Ability
Reconstructions
What are the cons of Computed Tomography?
Uses ionising radiation
Contrast Risk
Unsuitable for pregnant patients
Misdiagnosis
Expensive
How do you interpret a CT scan?
When interpreting at CT scan, it is important to determine the orientation. Images are most commonly presented in the transverse plane, and are orientated so that we arelooking up the body from the patient’s toes.
A helpful way to get your bearings is the acronymRALP. Starting at the 9 o’clock position and moving clockwise in 90 degree intervals, we are looking at theRight,Anterior,Left andPosterior aspects of the patient.
The density of the body tissue determines the degree to which the x-rays are attenuated. In turn, this affects the brightness and contrast of the imaged tissues.
Those tissues withhighattenuation coefficients(strong absorption)show upwhite, and those which absorb withlow attenuation coefficients(weak absorption)show upblack.
This is quantified by the Hounsfield Scale of radiodensity. Tissues with a high Hounsfield score have a high attenuation coefficient, and so appear white
How do you interpret a CT scan?
When interpreting at CT scan, it is important to determine the orientation. Images are most commonly presented in the transverse plane, and are orientated so that we arelooking up the body from the patient’s toes.
A helpful way to get your bearings is the acronymRALP. Starting at the 9 o’clock position and moving clockwise in 90 degree intervals, we are looking at theRight,Anterior,Left andPosterior aspects of the patient.
The density of the body tissue determines the degree to which the x-rays are attenuated. In turn, this affects the brightness and contrast of the imaged tissues.
Those tissues withhighattenuation coefficients(strong absorption)show upwhite, and those which absorb withlow attenuation coefficients(weak absorption)show upblack.
This is quantified by the Hounsfield Scale of radiodensity. Tissues with a high Hounsfield score have a high attenuation coefficient, and so appear white
What are 3 windows of a CT scan?
Bone Window
Soft Tissue Window
Lung Window
What is Magnetic Resonance Imaging?
Cross sectional imaging modality which acquires images using the application of radio frequency waves and a strong magnetic field
Creates slices of the body in all planes
Scanner consists of a large tunnel like tube in which the patient lays for the duration of the examination
