Flashcards in Investigative Procedures In Surgery Deck (14)
What are the different types of investigative procedures?
Plain abdominal x-Ray
Bowel contrast radiography
Biliary contrast radiography
What is conventional radiology?
Differential X-ray absorption:
-radioluscent, black eg gas, fat. Absorbs few xrays
-radiopaque, white eg bone. Absorbs more xrays
Gut is visible when there's gas in it. Normal small bowel is less than 3cm in diameter and centrally placed. Normal large bowel is less than 6cm in diameter and peripherally placed.
What is the contrast medium used in contrast radiography?
(There's direct and indirect contrast) the medium is barium sulphate, gastraffin, iodinated benzoic acid derivatives.
What is bowel contrast radiography?
It's used to examine the upper GI tract. Barium suspension is given orally and it's progress is observed by X-ray fluoroscopic screening. The large bowel is examined by means of contrast given rectally. For small bowel a barium meal may be 'followed through'
What is biliary contrast radiography?
A side viewing duodenoscope can be used to inspect the duodenal papilla. Cannula can be inserted and contrast injected into the common bike duct and separately into the pancreatic duct.
What is urography?
To examine the kidneys and urinary collecting systems. Uses intravenous contrast which is concentrated and excreted by the kidneys. The urinary tract is examined sequentially from kidneys to bladder on abdominal films taken at intervals after the injection.
What is angiography?
Intravenous or intra arterial injection of a contrasted medium
What is a CT scan?
A computerised tomography scan. A series of thin transverse slices (can be computatised when all images are fed into the computer and a single image is produced). Precise fan shaped beam of X-rays are pulsed from dif angles and the transmitted radiation is recorded electronically.
What's an MRI?
Magnetic resonance imaging. Powerful magnetic field is applied to the body aligning protons of all hydrogen nuclei. The protons are excited by pulses of radio waves which cause them to resonate emitting signals which can be recorded. These are analysed to produce a computer image.
What's an ultrasound?
A transducer transmits and receives ultrasound. An image is generated electronically, bright spots show up on a dark screen. The brightness is proportional to the sound reflectivity of the tissue interface. Used I distinguish between solid and cystic lesions. Also used to detect abdominal masses, abnormal fluid. And for percutaneous interventional procedures. Used to measure physical dimensions eg an aneurism.
What is bone scanning?
When phosphate based agents are labelled with technetium and taken up by areas of increased bone deposition and resorption. Useful for suspected bone metasteses, occult fractures, osteomyelitis and metabolic bone disease.
What's a PET scan?
Position emission tomography. Detects gamma rays emitted by position emitting radionuclide tracer introduced into the body on a biologically active molecule usually an analogue of glucose.