Investigative Procedures Flashcards
what are the structures in a plain abdominal x ray ?
gut visible when there is gas in it,
small bowel normally less than 3 cm diameter and centrally placed,
when dilated can be recognised b transverse folds,
large bowel less than 6 cm diameter and peripherally placed,
can be recognised by folds that partly traverse the lumen
what should be assessed when examining an abdominal x ray ?
calcification in kidney, ureter, bladder, biliary tree,
dilated gut,
free intraperitoneal gas indicating bowel perforation,
gas in abnormal places e.g. biliary tree,
foreign bodies,
pathological calcification
describe bowel contrast radiology
examines upper GI tract,
barium swallow for oesophagus, barium meal for stomach and duodenum,
progress of contrast examined by x ray fluoroscopic screening
what are the general principles of CT ?
series of thin transverse slices,
precise fan shaped beam of x rays pulsed from different angles, transmitted radiation recorded electronically,
radiation counts analysed by computer
what are the applications of CT ?
investigating areas difficult to examine with radiology,
staging of disease e.g. lymphoma,
planning surgery,
guiding needles during biopsy of masses or drainage of fluid collections
what are the principles of MRI ?
powerful electromagnetic filed applied to the body aligning all protons of hydrogen nuclei,
protons excited by pulses of radio waves which cause them to resonate and emit signals that can be recorded,
these are analyse dot produce a computer image
what are the principles of ultrasound ?
non invasive, painless, safe,
transducer transmits and receives ultrasound,
an image is generated electronically and shows bright spots on a dark screen,
the brightness is proportional to the sound reflectivity of the tissue interface
what are the applications of ultrasound in surgery ?
distinguish between solid and cystic lesions,
detect abdominal masses,
abnormal fluid,
percutaneous interventional procedures,
measuring physical dimensions e.g. aneurysm
what are the principles of bone scanning ?
phosphate based agents labelled with technetium,
taken up by areas of increased bone deposition and resorption,
lack of specificity
what is bone scanning useful for ?
useful for suspected bone metastases, occult fractures, osteomyelitis, metabolic bone disease
what does PET stand for ?
positron emission tomography
how does PET work ?
detects gamma rays emitted by positron emitting radionuclide tracer introduced into the body on a biologically active molecule, usually an analogue of glucose
