lower GI Tract pathology and imaging

Question 1

what is the lower GI tract

Answer 1

starts with the caecum, ascending colon, transverse colon, descending colon and sigmoid colon

Question 2

primary functions of GI tract

Answer 2

• absorption of water
• waste products from digestion
• waste removal

Question 3

the appendix

Answer 3

a small, thin pouch about 5-10cm long

Question 4

appendicitis

Answer 4

• inflammation of the appendix

- occurs when the appendix becomes infected or blocked by stool, FB or tumour

Question 5

clinical indication of appendicitis

Answer 5

• central abdomen pain
• pain travels to rt hand side and becomes constant and severe
• loss of appetite, nausea, vomiting, diarrhoea and fever

Question 6

ultrasound abdo/pelvis appendicitis

Answer 6

• transabdominal approach
• faecal matter and air-filled bowel may prohibit visualisation
• obese and bariatric patients are harder to visualise

Question 7

CT adbo/pelvis with contrast appendicitis

Answer 7

• iv contrast - 3mls/s , delay 20 seconds
• breathing instructions
• patient is supine with arms above head
• venous phase - above diaphragm to symphysis pubis

Question 8

clinical indications of large bowel pathologies

Answer 8

• mass
• obstruction
• weight loss
• anaemia

Question 9

abdominal x-ray

Answer 9

• patient lies supine
• MSP perpendicular to table
• ASIS equidistant from table top - no rotation

Question 10

AXR centring point

Answer 10

• level of the iliac crests

- arrested respiration

Question 11

AXR collimation

Answer 11

sup - diaphragm
inf - symphysis pubis
lat - skin margins

Question 12

abdo/pelvis CT with contrast

Answer 12

the contrast identifies presences of mass, signs of inflammation and bowel wall ischemia.
3mls/s delay 70 seconds

Question 13

CT colonoscopy

Answer 13

• rectal catheter is inserted and large bowel is inflated, to get a detailed view of the lining of the bowel

Question 14

MR colonoscopy

Answer 14

similar to CT colonoscopy

• non ionising radiation
• however Mr risks still apply

Question 15

patient prep to clear bowel (2 days b4 procedure)

Answer 15

• patient drinks as much fluid as possible
• 7-9am given a list of foods allowed for breakfast
• 12 noon - given a list of foods allowed for lunch
• after this no solid food is eaten
• 7pm - gastrographin (50 mls) mixed with squash

Question 16

patient prep to clear bowel ( 1 day before procedure)

Answer 16

• no solid food
• drink as much clear fluid as possible (150 mls every hour)
• 7pm 50 mls gastrographin with squash

Question 17

patient prep to clear bowel (day of procedure)

Answer 17

• do not eat any food
• drink as much water as you like
• after procedure, eat normally

Question 18

prior to scanning bowel (colonoscopy)

Answer 18

• catheter inserted into rectum
• wash hands
• ppe
• patient lays lateral, with knees bent
• buscopan is used
• catheter is lubricated

Question 19

colonoscopy CT scan protocol

Answer 19

• inflate colon with air
• perform supine and prone views
• iv contrast if carcinoma is suspected
• single breath-hold aquisition

Question 20

MR protocol - bright lumen technique

Answer 20

• water and gadolinium enema
• t1 weighted imaging
• ## lumen appears bright because of the presence of gadolinium and polyps are visible as filling defects

Question 21

MR protocol - bright lumen technique

Answer 21

• water and gadolinium enema
• t1 weighted imaging
• ## lumen appears bright because of the presence of gadolinium and polyps are visible as filling defects

Question 22

MR protocol - black lumen technique

Answer 22

• water enema for luminal distention and intravenous infusion of gadolinium for enhancement of colonic wall
• after complete filling, a 3D T1-weighted sequence is performed before and after iv administration
• lumen appears dark on t1 sequence, enhancement of colonic wall and inflammatory changes can be seen.
• a 2d/3d sequence is used before administration - T2/T1 Weighted- allows to see filling defects - lumen appears bright

Question 23

Bowel obstruction

Answer 23

• A mechanical blockage of the bowel
• where a structural pathology physically blocks the passage
• dilated bowel (>6cm, or >9cm at caecum

Question 24

Diverticular disease

Answer 24

• a condition that occurs when small puches, or sacs, form and push outward through weak spots in the wall of colon
• Contrast enhanced CT shows multiple gas filled outpouchings from the sigmoid colon - indicating diverticular disease

Question 25

ulcerative colitis

Answer 25

- inflammation occurs in the colon (large intestines) and rectum - development of small ulcers on the colon;s inner lining, which produce pus and mucus - causes abdominal discomfort and frequent emtying of colon

Question 26

ulcerative colitis ct

Answer 26

contrast enhanced CT sdcan shows minimal diffuse thickening of the sigmoid colon - small strands of inflammatory stranding

Question 27

ulcerative colitis MR

Answer 27

- thickening of mucosal lining | - my show inflamed transverse colon

Question 28

Crohn's disease

Answer 28

- inflammation occurs in the colon and rectum - can affect thickness of the digestive tract wall - spreads through all wall in the interstines- causing small tears to the lining

Question 29

crohn's disease CT

Answer 29

- thickened bowel wall, narrowing of lumen

Question 30

MR crohn's disease

Answer 30

- shows marked bowel wall thickening and luminal narrowing of the terminal ileum

Question 31

pathologies associated with bowel motility

Answer 31

- chronic functional constipation indications - infrequent bowel movements/ difficult passage stools that persists for several weeks - colonic inertia - delayed transit

Question 32

colonic transit test/ sitzmark study

Answer 32

- time taken for food residues to move through colon - severity of constipation - helps diagnose primary cause of constipation

Question 33

colonic transit test/ sitzmark study procedure

Answer 33

- patient swallows capsules containing 10-24 soft rubber shapes (radio-opaque markers) - 1 capsule followed by abdomen x-ray 5 days later - oir 1 capsule at the same time each day for 3-5 days with abdo x-rays taken on day 5-7

Question 34

outcomes on day 5 abdo x-ray colonic transit test/ sitzmark study

Answer 34

- fewer than 25% of markers left, suggests normal transit constipation - more than 25% of markers left and evenly spread throughout colon is consistent with slow transit constipation - more than 25% of markers left congregated in the recto-sigmoid are indicative of an outlet obstruction

Question 35

clinical indications defacting issues

Answer 35

- pelvic floor pain - evacuatory difficulty - bulging or prolapsed rectum

Question 36

defacting proctogram usingf fluoro or mri

Answer 36

- image of the rectum as it passes stool | - investigation gives morphological and functional information

Question 37

defacting proctogram - fluoroscopy procedure

Answer 37

- patient changes into gown - barium paste is made in the consistency of soft srool and is injected into the rectum - patient sits laterally on a radiolucent commode - in front of fluoro unit - both videofluoroscopy and spot images captured while patient is asked to rest, squeeze, cough, strain, defecate and strain

Question 38

defacting proctogram MRI procedure

Answer 38

- patient changes into gown and completes questionnaire - patient lays supine - disposable endorectal coil is used to image anal sphincters - t1 and t2 spin echo - coil is removed and a paste mixture of gadolinium is put into the patient - images are acquired whilst the patient is resting, squeezing, defacating in supine. images are acquired every 1-1.4 secs.

Question 39

rectocele

Answer 39

- end of large intestine pushes against and moves the back wall of the vagina - may be a bulging in rectal floor

Question 40

rectal prolapse

Answer 40

- bowel moves moves out of the rectum and back in again, or remaining outside the body, producing a prolapse appearance after defaction