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Diagnostic Imaging 3 > lower GI Tract pathology and imaging > Flashcards

lower GI Tract pathology and imaging Flashcards

1
Q

what is the lower GI tract

A

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

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2
Q

primary functions of GI tract

A
  • absorption of water
  • waste products from digestion
  • waste removal
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3
Q

the appendix

A

a small, thin pouch about 5-10cm long

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4
Q

appendicitis

A
  • inflammation of the appendix

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

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5
Q

clinical indication of appendicitis

A
  • central abdomen pain
  • pain travels to rt hand side and becomes constant and severe
  • loss of appetite, nausea, vomiting, diarrhoea and fever
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6
Q

ultrasound abdo/pelvis appendicitis

A
  • transabdominal approach
  • faecal matter and air-filled bowel may prohibit visualisation
  • obese and bariatric patients are harder to visualise
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7
Q

CT adbo/pelvis with contrast appendicitis

A
  • iv contrast - 3mls/s , delay 20 seconds
  • breathing instructions
  • patient is supine with arms above head
  • venous phase - above diaphragm to symphysis pubis
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8
Q

clinical indications of large bowel pathologies

A
  • mass
  • obstruction
  • weight loss
  • anaemia
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9
Q

abdominal x-ray

A
  • patient lies supine
  • MSP perpendicular to table
  • ASIS equidistant from table top - no rotation
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10
Q

AXR centring point

A
  • level of the iliac crests

- arrested respiration

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11
Q

AXR collimation

A

sup - diaphragm
inf - symphysis pubis
lat - skin margins

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12
Q

abdo/pelvis CT with contrast

A

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

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13
Q

CT colonoscopy

A
  • rectal catheter is inserted and large bowel is inflated, to get a detailed view of the lining of the bowel
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14
Q

MR colonoscopy

A

similar to CT colonoscopy

  • non ionising radiation
  • however Mr risks still apply
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15
Q

patient prep to clear bowel (2 days b4 procedure)

A
  • 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
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16
Q

patient prep to clear bowel ( 1 day before procedure)

A
  • no solid food
  • drink as much clear fluid as possible (150 mls every hour)
  • 7pm 50 mls gastrographin with squash
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17
Q

patient prep to clear bowel (day of procedure)

A
  • do not eat any food
  • drink as much water as you like
  • after procedure, eat normally
18
Q

prior to scanning bowel (colonoscopy)

A
  • catheter inserted into rectum
  • wash hands
  • ppe
  • patient lays lateral, with knees bent
  • buscopan is used
  • catheter is lubricated
19
Q

colonoscopy CT scan protocol

A
  • inflate colon with air
  • perform supine and prone views
  • iv contrast if carcinoma is suspected
  • single breath-hold aquisition
20
Q

MR protocol - bright lumen technique

A
  • water and gadolinium enema
  • t1 weighted imaging
  • ## lumen appears bright because of the presence of gadolinium and polyps are visible as filling defects
21
Q

MR protocol - bright lumen technique

A
  • water and gadolinium enema
  • t1 weighted imaging
  • ## lumen appears bright because of the presence of gadolinium and polyps are visible as filling defects
22
Q

MR protocol - black lumen technique

A
  • 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
23
Q

Bowel obstruction

A
  • A mechanical blockage of the bowel
  • where a structural pathology physically blocks the passage
  • dilated bowel (>6cm, or >9cm at caecum
24
Q

Diverticular disease

A
  • 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
25
Q

ulcerative colitis

A
  • 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
26
Q

ulcerative colitis ct

A

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

27
Q

ulcerative colitis MR

A
  • thickening of mucosal lining

- my show inflamed transverse colon

28
Q

Crohn’s disease

A
  • 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
29
Q

crohn’s disease CT

A
  • thickened bowel wall, narrowing of lumen
30
Q

MR crohn’s disease

A
  • shows marked bowel wall thickening and luminal narrowing of the terminal ileum
31
Q

pathologies associated with bowel motility

A
  • chronic functional constipation indications
  • infrequent bowel movements/ difficult passage stools that persists for several weeks
  • colonic inertia
  • delayed transit
32
Q

colonic transit test/ sitzmark study

A
  • time taken for food residues to move through colon
  • severity of constipation
  • helps diagnose primary cause of constipation
33
Q

colonic transit test/ sitzmark study procedure

A
  • 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
34
Q

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

A
  • 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
35
Q

clinical indications defacting issues

A
  • pelvic floor pain
  • evacuatory difficulty
  • bulging or prolapsed rectum
36
Q

defacting proctogram usingf fluoro or mri

A
  • image of the rectum as it passes stool

- investigation gives morphological and functional information

37
Q

defacting proctogram - fluoroscopy procedure

A
  • 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
38
Q

defacting proctogram MRI procedure

A
  • 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.
39
Q

rectocele

A
  • end of large intestine pushes against and moves the back wall of the vagina
  • may be a bulging in rectal floor
40
Q

rectal prolapse

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

Diagnostic Imaging 3 (18 decks)

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