Diagnostic imaging Flashcards
what are the five radiographic opacities?
air (black) fat soft tissue/fluid mineral (bone) metallic (white)
what are the five basic radiographic signs of abnormalities looked for in a systematic evaluation?
number size shape location opacity
what must be assessed to ensure completeness of a radiographic study?
correct patient and region
complete study (two orthogonal views)
identify and label radiographs
assess image quality
what is assessed for when looking at imagine quality?
exposure collimation (all four edges) position (straight and well centred) contrast artefacts
what is the first stage of assessing the radiograph?
searching the radiograph for lesions
what is the second part of assessing the radiographic image?
descriptions (report findings)
how in depth description of a radiograph have to be?
sufficient enough for someone to mentally reconstruct the image
significant aspects systematically described
do normal features on a radiographic imagine need describing?
no, if it isn’t described its considered normal
when assessing the shape of a lesion, what must be described?
overall shape
shape of margins
definition of margins
what interpretive principles can be applied to radiographs?
mass effect - if something changes in size it will have an effect on the surrounding structures
effacement - loss of normal contrasting opacity
multiple lesions - single lesions are rare
specific signs
what are some limitations of radiographic imaging?
2D representation of 3D structure
only shows change in anatomy no other information
only a small snapshot in time (lesion might not appear at some times)
no information about function
what property of an ultrasound wave determines how well it penetrates tissue?
wavelength (frequency)
what does the amount of reflection of ultrasound waves by tissue depend on?
echo-density of the tissue (bone reflects fully)
what are the three types of head of an ultrasound probe?
linear
convex
sector
what does high ultrasound wave frequency correlate to?
higher resolution
what are artefact due to reflection called on ultrasound?
reverberation
when is reverberation on ultrasound useful?
useful to tell the widest part of a tube
what are the artefacts due to refraction of ultrasounds effect?
position a structure is viewed
what are the three possible outcomes of a dominant follicle in a cow?
ovulate
turnover (regress then grow again)
cystic
what is the first diagnostic information to determine when ultra sounding cattle ovaries?
is there a CL, cyst or follicle
when do we ultrasound scan cows for reproductive purposes?
earlier the better but later is more accurate as to whether the animal will produce a live calf
where will the uterus be found if the animal is pregnant?
over the pelvic brim
what are clues in the cattle uterus that the animal is pregnant?
CL on ovary that last ovulated
fetus in uterine horn
fluid in the horn
roughly what ages is the amniotic vesicle visible in cattle ultrasound?
day 40
what ways can foetuses be ages?
crown-rump length
biparietal distance
trunk diameter
how can cattle foetuses be sexed?
genital tubercle migrates at around day 56
just behind umbilicus in males and between hind legs and tail in females
what are some common uterine abnormalities that cause cloudy fluid?
mucometra
endometritis
pyometra
what types of imaging modalities can be used in equine?
radiography nuclear scintigraphy ultrasonography MRI CT
what is radiography mainly used to image?
bone articular and periarticular structure soft tissue (swelling and mineralisation)
what is kVp on a radiography machine?
speed of electrons
what is mA on a radiography machine?
number of electrons release
what is S on a radiography machine?
time
what should be reported first when reading radiographic films, before the report?
area that has been imaged
quality of the film
what are the three phases of a film report?
recognition (search)
descriptive (report)
interpretation (differential diagnosis)
what should be analysed when discussing film quality?
positioning collimation contrast exposure labelling artefacts (Pink Camels Collect Extra Large Apples)
what is the recognition phase of a film report?
systematic search to identify abnormal findings, normal findings and normal variations
what is the descriptive phase of a film report?
categories finding according to radiographic signs
what are the radiographic signs used to categorise the descriptive phase of radiographic findings?
size shape position number margination opacity
what is described in the interpretation phase of a film report?
history
signalment
clinical signs
diagnostic tests
what is ultrasonography used to image mainly in equine medicine?
tendons and ligaments
how can the contact area for ultrasound scanning be improved?
clip and clean skin
ultrasound gel
standoff
alcohol (not clipped)
what aspects of lesions are described when looking at ultrasound?
size shape position number margination echogenicity
what is nuclear medicine (gamma scintigraphy) used for in equine medicine?
detect areas of actively turning over of bone
how does gamma scintigraphy work?
polyphosphonate (body thinks of it as calcium) is labeled and put into body, the machine can then pick this up where it is being used
what are the phases of scanning of gamma scintigraphy?
phase I - blood pool (rarely used)
phase II - soft tissue
phase III - bone
what is the major issue of using MRI for horses?
MRI machines can’t fit the whole horse through (mainly used for feet)
what are the advantages of MRI use in equine medicine?
highly detailed
specific and sensitive diagnosis
