Anatomy and imaging Flashcards
Name the three planes which pass through the body in anatomical position, and describe their location
Coronal - vertical, divides body into anterior and posterior
Sagittal - vertical, through nose (if median sagittal plane)
Transverse/horizontal/axial - divides body into superior and inferior
What does the word ‘ventral’ describe?
Structures relative to the front of the body (anterior)
What does the word ‘dorsal’ describe?
Structures relative to the back of the body (posterior)
What does the word ‘cranial’ mean?
Towards the head (superior)
What does the word ‘caudal’ mean?
Towards the tail (inferior)
What does the word ‘rostral’ mean?
Towards the nose (eg. forebrain is rostral to hindbrain)
Who invented the X-ray machine?
Wilhelm Roentgen, in 1895, produced the first radiographic exposure of his wife’s hand
How much do air, bone, water and fat attenuate X-rays in relation to each other?
Air attenuates them a little
Then, in increasing order;
Fat, water, bone
Suggest a substance that could be used to demonstrate the gastrointestinal tract on an X-ray
Barium sulphate (suspension), as it is an insoluble, relatively high-density, non-toxic salt Air can be added to the suspension which is called a double-contrast study
What contrast agent could be used intravenously or intra-arterially to visualise the arteries, veins, and other structures and why? What other structures can be visualised by this method?
Iodine, as it has a relatively high atomic mass and is naturally excreted via the urinary system. This is why it can also be used to visualise the kidneys, bladder and ureter in intravenous urography
What is subtraction angiography?
It is used to get around the issue of overlying bony structures. Two images are taken, one before the injection of the contrast media and one after, and the images are combined to create a solitary image of contrast only
Which plane does a CT scanner obtain images in?
Axial
What is the difference in the appearance of fat and fluids in T1 and T2 weighted MRI images?
T1 - dark fluid, bright fat
T2 - bright fluid, intermediate fat
What type of radiation is used in nuclear medicine imaging?
Gamma rays
Suggest a radiopharmaceutical commonly used in nuclear medicine imaging?
Technetium 99m, often combined with other complex molecules
In simple terms, how does a PET scanner work?
Tissues that actively metabolise glucose take up more of an injected radioactive compound such as FDG, so they produce a ‘hot spot’; this is often used in the detection of cancer.
Which direction are most chest radiographs taken in?
PA
AP is sometimes used if the patient is too unwell to stand
Which direction are most abdominal radiographs taken in?
AP supine position
Erect plain abdominal radiograph sometimes used if small bowel obstruction is suspected
How are most CT images orientated?
In the axial plane
Observer looks from feet upwards towards head
The uppermost border of the image is anterior
The patient’s left is on the observer’s right
