M104 T1 L14

Question 1

What are the imaging modalities for the abdomen?

Answer 1

X-ray (plain film) / Fluoroscopy
Ultrasound
CT, MRI

Question 2

What’s the difference between plain imaging and cross-sectional imaging?

Answer 2

plain - xray

cross - CT scan

Question 3

Why is it easier to pick out anatomy on C.T. scans rather than xrays

Answer 3

bc everything is superimposed from front to back whereas CT is a slice where you can see the anatomy in relationship of one part of the anatomy relative to another

Question 4

How does the effect of increasing the spatial resolution of an x-ray differ to when done to an MRI?

Answer 4

xray - increased clarity

MRI - more pixelated, lower level of detail

Question 5

What’s the difference between the level of detail that can be viewed on the MRI than on plain film?

Answer 5

MRI can identify individual muscle fibres, articular cartilage, and muscles in addition to bone, soft tissue and fat that can be seen by plain film.

Question 6

Does MRI or plain film have a higher contrast resolution?

Answer 6

MRI

Question 7

Does MRI or plain film have a higher spatial resolution?

Answer 7

plain film

Question 8

What tissues can be identified by plain film / on an xray?

Answer 8

bone and soft tissue
within soft tissue might be able to pick up difference between fat, the subcutaneous fat, the muscle and other soft tissues deeper

Question 9

What tissues can be identified by an MRI?

Answer 9

bone, articular cartilage, muscles very distinctly from the subcutaneous fat
within the muscles can see individual fibres

Question 10

Why do MRIs have a higher level of detail than plain film?

Answer 10

bc it has many more shades of grey within the soft tissue

Question 11

What are the most common and basic sequences of images that can be produced by an MRI?

Answer 11

the T1 and T2 weighted sequences

Question 12

What is the difference between the T1 and T2 weighted sequences on MRI imaging?

Answer 12

T1 - fluid is black

T2 - fluid is white

Question 13

How are contrast agents administered?

Answer 13

IV or enterally (oral / PR) before a scan

Question 14

In what weighted sequence of MRI imaging do Paramagnetic contrast agents have their strongest effect and why?

Answer 14

in T1 weighted imaging bc they predominantly alter the T1 relaxation time in the tissues in which they have accumulated

Question 15

How do contrast agents differ to the surrounding material on x-rays?

Answer 15

they are either more or less dense than surrounding materials

Question 16

How do contrast agents differ to the surrounding material on MRI scans?

Answer 16

they are paramagnetic, so they have an impact on the MRI signal

Question 17

What are examples of solid viscera?

Answer 17

the liver, kidneys, spleen

Question 18

What are examples of hollow viscera?

Answer 18

the bladder and the bowel

Question 19

Would ultrasound be a good imaging modality for looking at the bowel and why?

Answer 19

no because it is very good at looking at the solid organs, not the hollow organs

Question 20

Where are intra-peritoneal organs located?

Answer 20

within the cavity of the peritoneum

Question 21

Where is the retroperitoneum located?

Answer 21

behind the peritoneum

Question 22

Where is the retroperitoneum located?

Answer 22

behind the peritoneum

Question 23

Do the retro-peritoneal organs have no specific delineating anatomical structures?

Answer 23

no, they don’t

Question 24

What is often used as a first line test for looking at the solid viscera?

Answer 24

ultrasound probes - liver, limbs

Question 25

What imaging modalities are used for the bowels?

Answer 25

X-ray – a good first line test | CT & MRI are increasingly used (avoids endoscopy, uses cannulas instead)

Question 26

On a plain film, what is a normal calibre of the bowels?

Answer 26

large - up to 5 cm | small - up to 3 cm

Question 27

What is the criteria for a dilated bowel?

Answer 27

much more air and wider calibre of bowel

Question 28

What causes a dilate bowel?

Answer 28

a blockage

Question 29

What does free air near the bowel indicate?

Answer 29

that the bowel is ruptured or perforated | that the normal distribution of bowel gas has been disrupted

Question 30

How are the large and small bowels differentiated between on the plain films?

Answer 30

large - is peripheral, frames the small bowel, might contain (liquid, hard) faeces, up to 5cm small - up to 3cm, is more central within the abdomen, contains fluid and air, is constrained by encircling valvulae conniventes, which are more widely spaced in the ileum than they are in the jejunum

Question 31

How do the mucosal folds differ on the bowels?

Answer 31

large - the haustral folds are interspaced with the plicae circulares which are just seen on the edges of the bowel small - the valvulae conniventes lines across the entire width of the small bowel

Question 32

Where are the plicae circulares located?

Answer 32

on the edges of the large bowels - they don't cross the entire width of the bowel

Question 33

What happens to plicae circulares or the valvulae conniventes if the bowel is distended?

Answer 33

they can be effaced or flattened out

Question 34

How large is the caecum on plain film?

Answer 34

9cm

Question 35

What are the plicae circulares otherwise known as?

Answer 35

circular folds valves of Kerckring plicae circulae valvulae conniventes

Question 36

How does a barium contrast cause a double contrast?

Answer 36

one contrast being the barium, the other contrast being the gas the double contrast is where the barium is stuck to the wall of the stomach

Question 37

How are double contrast barium enemas achieved?

Answer 37

both barium and then gas have been put with a tube in the back passage PR the patient is rolled around to try and get the contrast to go up through the sigmoid, up the descending colon along the transverse and back down and then fill up with air

Question 38

How do double contrast barium enemas work?

Answer 38

x-rays of the colon and rectum are taken using two forms of contrast to make the structures easier to see a radiocontrast agent is put into the rectum (PR)

Question 39

What structures are investigated for using a double contrast barium enema?

Answer 39

masses, polyps and lesions within the large bowel

Question 40

Why are double contrast barium enemas diffficult to achieve in elderly patients?

Answer 40

bc they are moved around a lot to get the contast where it needs to flow through internally

Question 41

What group of patients are most likely to need a double contrast barium enema?

Answer 41

elderly patients

Question 42

What are double contrast barium enemas being replaced with?

Answer 42

CT colonographies

Question 43

What does a CT colonography involve?

Answer 43

air is put into the large bowel | a C.T. scan is performed

Question 44

How is a CT colonography carried out?

Answer 44

laxatives are used to clear out the large bowel the patient arrives in the hospital and comes to C.T. scanner a little tube is put in through which air and buscopan are used to relax the bowel when the bowel is well inflated, the C.T. scan produces axial slices which might show abnormalities

Question 45

What is the most common disease to affect the small bowel?

Answer 45

IBD

Question 46

How can a rectal tumour affect the rectal fascia?

Answer 46

causes it to become irregular with some strands and some little nodules

Question 47

How can MRIs be used when analysing rectal tumours?

Answer 47

can be used to stage the rectal tumour - to see exactly how far the tumour is extending into the surrounding tissues whether that patient might be resectable for surgery / whether they need chemo radiotherapy / other treatents