Cross Sectional Anatomy of the Abdomen (1/3 DONE) Flashcards
List 7 imaging techniques.
1 - Plain radiographs / x-ray.
2 - Barium / fluoroscopy.
3 - Ultrasound.
4 - Endoscopy.
5 - CT.
6 - MRI.
7 - PET.
What is the range of frequencies used for ultrasound?
5-20MHz.
List 3 soft tissue structures that are often visualised using ultrasound.
1 - Liver.
2 - Kidneys.
3 - Upper biliary tree.
Why is the pancreas and bowel often seen incompletely using ultrasound?
Because stomach gas covers the body / tail in some areas.
List 3 things that plain film radiography / x rays can be used to asses in the digestive system.
1 - Bowel dilation.
2 - Free air (gas external to the bowel lumen).
3 - Abnormal calcification (e.g. renal stones).
How would a large bowel obstruction differ from a small bowel obstruction on a plain film radiography / x-ray?
- With a large bowel obstruction, there will be peripherally located loops, whereas with a small bowel obstruction, there will be centrally located loops.
- With a large bowel obstruction, haustral folds can be seen, whereas with a small bowel obstruction, valvular conniventes can be seen.
What are haustral folds?
The pouches of the large intestine that give the colon its segmented appearance.
What are valvulae conniventes?
The circular folds that project into the lumen of the small intestine.
Which structures can be visualised using fluoroscopy with barium as a contrast medium?
The gut.
Which structures can be visualised using fluoroscopy with iodine as a contrast medium?
- Blood vessels.
- Bile ducts.
- The renal collecting system.
List the phases of contrast in an intravenous contrast CT scan.
1 - Pulmonary arterial.
2 - Arterial (20s).
3 - Parenchymal.
4 - Portal (70s).
5 - Excretory urographic phase (10 minutes).
In which phase of contrast of an intravenous contrast CT scan is the aorta enhanced the most?
The arterial phase (20s).
List 3 neutral contrast agents that might be used to distend the lumen of the gut in a CT.
Give an example of a positive contrast agent.
Neutral contrast agent:
1 - Water.
2 - Air.
3 - CO2.
Positive contrast agent:
4 - Iodine.
Why might it help to distend the lumen of a gut during a CT scan?
Distending the lumen makes it easier to see the bowel wall.
How will a positive contrast agent appear differently to a neutral contrast agent on a CT scan?
A positive contrast agent will appear whiter (it will absorb more x-rays).
Give an example of an advantage and disadvantage of MRI as compared to CT.
Advantage: MRI can detect smaller changes in contrast.
Disadvantage: MRI has a lower resolution.
Give an example of an intravenous contrast agent used in MRI.
Gadolinium.
What are the types of MRI images?
T1 and T2.
What is the difference between T1 and T2 MRI images?
T1 highlights fat whereas T2 highlights water.
Which structure defines the plane of division of the lobes of the liver?
The middle hepatic vein.
Which ligament lines the division between the lobes of the liver?
The falciform ligament.
Which two veins merge to form the portal vein?
The splenic vein and the superior mesenteric vein.
From which artery is the hepatic artery derived?
It is one of three divisions from the coeliac trunk.
Describe the Couinaud system of liver segmentation.
- Subdivisions of the liver are based on branches of the hepatic artery.
- Superior and inferior segments are marked by the plane of the portal vein.
