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MRS432- CT > CT abdo protocols > Flashcards

CT abdo protocols Flashcards

1
Q

CT portal venous abdo indications

A 
Acute abdo pain
Trauma
Oncology staging/follow up
? Mass
Abscess
Ascites
Diverticulitis
Appendicitis and other non-descript abdo symptoms
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2
Q

CT portal venous abdo protocl

A

Most common type of abdominal scan

Scans performed supine feet first arms raised out of FOV

Scan on inspiration

AP or duel scanogram

Scan from 2cm above diaphragm to base of pelvis

Slices overlapping 1-1.5mm thick

Standard recon algorithm and S.T. window approx. WW 400 WL 40

MPR’s Ax, Sag and Cor 2-5mm

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3
Q

CT portal venous abdo contrast requirements

A

Oral contrast usually used (water or opaque as per department protocol)

IV contrast via cannula. 50-75ml @ 2.5-3.5 ml/sec

Timing of scan is 70-80 sec post inj.

If bolus tracking, place tracker over descending aorta just above diaphragm with a delay between 40-50 sec post threshold

This timing allows for optimal enhancement of internal organs

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4
Q

Portal venous abdo possible pathologies

A 
Mass
Abscess
Ascites
Diverticulitis
Appendicitis
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5
Q

CT post contrast abo indications (15)

A 
Injuries following trauma 
Masses 
Ascites 
Abscess or intra-abdominal collection 
Initial staging of Lymphoma/Oncology/Metastases staging 
Inflammatory bowel disease  i.e. Crohn’s disease 
Colon cancer 
Acute cholecystitis
Acute appendicitis 
Bleeding 
Unexplained abdominal pain 
Melanoma 
Ovarian cancer 
Testicular cancer 
Bowel obstruction
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6
Q

CT post contrast protocl

A

Scans performed supine feet first arms raised out of FOV

Scan on inspiration

AP or duel scanogram

Scan from 2cm above diaphragm to base of pelvis

Slices overlapping 1-1.5mm thick

Standard recon algorithm and S.T. window approx. WW 400 WL 40

MPR’s Ax, Sag and Cor 2-5mm

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7
Q

CT post contrast, contrast requirements

A

Oral contrast usually used (water or opaque as per department protocol)

IV contrast via cannula. 50-75ml @ 2.5-3.5 ml/sec

Timing of scan is 70-80 sec post inj.

If bolus tracking, place tracker over descending aorta just above diaphragm with a delay between 5-10 sec post threshold

This timing allows for optimal enhancement of internal organs

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8
Q

Possible CT abdo post contrast pathologies

A 
mass
ascites
abscess
Crohn's disease
colon cancer
melanoma
ovarian cancer
testicular cancer
bowel obstruction
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9
Q

CT urogram or CT IVP indications

A 
Evaluation and detection of renal mass
Bladder pathology
Complex cysts
Neuroblastoma
Haematuria
Hydronephrosis
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10
Q

CT urogram or CT IVP protocol

A

Scans performed supine feet first arms raised out of FOV

Scan on inspiration

AP or duel scanogram

Scan from:
Non contrast scan of the complete abdomen

Arterial scan of the upper abdomen to crests only

Delayed phase is through the complete abdomen

Slices overlapping 1-1.5mm thick

Standard recon algorithm and S.T. window approx. WW 400 WL 40

MPR’s Ax, Sag and Cor 2-5mm

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11
Q

CT urogram or CT IVP contrast requirements

A

Oral contrast usually used (water or opaque as per department protocol)

IV contrast via cannula. 50-75ml @ 2.5-3.5 ml/sec

If bolus tracking, place tracker over descending aorta just above diaphragm:
Arterial 5 - 10 second
Delayed approx. 10 minutes

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12
Q

CT urogram or CT IVP possible pathologies

A

RCC
Neuroblastoma
Heamaturia
Hydronephrosis

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13
Q

3 phase liver/pancreas indications (8)

A 
Hepatic cell carcinoma
Pancreatic Cancer 
Pancreatitis 
Metastases
Cirrhosis / Alcoholic liver disease 
Haemangioma / Hyper-vascular lesions  
Pancreatic abscess or Pseudocyst 
Jaundice - Obstructive and non-obstructive jaundice
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14
Q

3 phase liver/pancreas protocol

A

Scans performed supine feet first arms raised out of FOV

Scan on inspiration

AP or duel scanogram

Scan from:
Non contrast, delayed phase and arterial of the upper abdomen to crest

Portal venous through the complete abdomen

Slices overlapping 1-1.5mm thick

Standard recon algorithm and S.T. window approx. WW 400 WL 40

MPR’s Ax, Sag and Cor 2-5mm

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15
Q

3 phase liver/pancreas contrast requirements

A

Oral contrast usually used (water or opaque as per department protocol)

IV contrast via cannula. 50-75ml @ 2.5-3.5 ml/sec

If bolus tracking, place tracker over descending aorta just above diaphragm:
Arterial 5 - 10 second
Venous 45 - 70 second
Delayed 5 minutes

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16
Q

3 phase liver/pancreas possible pathologies

A 
hepatic cell carcinoma
pancreatic ca
pancreatitis
mets
cirrhosis
pancreatic abscess
jaundice
17
Q

possible protocol alterations for trauma

A

Trauma patient: lots of staff, quick scan, organised room ready to scan
Fast non-con scan to prevent patient movement and risk of repeating
- If patient hard on hearing turn auto instructions up as you need to remove hearing aids
- Trauma or unconscious patient place equipment away from area to be scanned as much as possible and turn off auto instructions

18
Q

Possible protocol alterations for paediatrics

A
  • Paediatric patient: parent in the room, sedations/ GA, secure head, organised and quick scan, simple explanation
  • Fast non-con scan to prevent patient movement and risk of repeating
  • If patient hard on hearing turn auto instructions up as you need to remove hearing aids
  • Trauma or unconscious patient place equipment away from area to be scanned as much as possible and turn off auto instructions
19
Q

Possible protocol alterations for geriatrics

A
  • Geriatrics: secure head, explain simply, organised and quick scan
  • Fast non-con scan to prevent patient movement and risk of repeating
  • If patient hard on hearing turn auto instructions up as you need to remove hearing aids
  • Trauma or unconscious patient place equipment away from area to be scanned as much as possible and turn off auto instructions
20
Q

Possible protocol alterations for uncooperative patients

A
  • Uncooperative: immobilisation devices, alter parameters for a fast scan, staff to help
  • Contrast volume dependent on patient size
  • Fast non-con scan to prevent patient movement and risk of repeating
  • If patient hard on hearing turn auto instructions up as you need to remove hearing aids
  • Trauma or unconscious patient place equipment away from area to be scanned as much as possible and turn off auto instructions
21
Q

Dose reduction strategies

A
  • Appropriate scan range: image relevant anatomy
  • Pitch closer to 1 to decrease scan time (critical cases)
  • Making the non con scan a fast scan: reducing dose and reducing risk of having to repeat scan
  • Change contrast volume (dependent on patient size)
  • Change technical factors dependent on patient size: reduce kV, mAs
  • Change tube rotation time (slow down to gain appropriate exposure)
  • Reduce scan range to reduce radiation exposure and maximise resolution
  • SFOV is appropriate: tight to maximise spatial resolution
  • Automatic exposure control: Automatically adjusts exposure (mA) for attenuation differences of tissue types and thicknesses. Tight collimation: Accurate pre-patient collimation reduces dose post-patient collimation picks up unhelpful scatter and improves image quality
  • Bowtie filter: shape’s and hardens the beam increasing uniformity, removes low energy x-rays and increases average energy beam; lower absorbed dose to patient
  • Centre patient in isocentre correctly
  • Lead shielding if needed
22
Q

What protocol would you do for the following and what are possible pathologies?

  • 58 year old male
  • 5 days of dull abdominal pain with diarrhoea
  • Fevers for 2 days (indicates inflammatory response)
  • Heart rate 98 bpm
  • Blood pressure 100/75
  • Respiration rate 32
  • On examination; tenderness left lower quadrant
  • Nil per rectum blood
A

Portal venous abdomen due to left lower quadrant pain: suggestive of any abdominal pathology (most likely bowel related)

  • Diverticulitis: fevers associated with abdominal pain
  • Bowel obstruction: dull bowel pain
  • Early stage of bowel cancer: dull abdo pain, diarrhoea
  • Pt History: previous surgery, urology? Risk of perforation
  • Ulcerative colitis
  • Crohn’s disease
23
Q

Indications of a CTA AAA

A

? Aneurysm
? Dissection
Surgical planning

24
Q

Contrast of CTA AAA

A

75-100mL @4-5mL/sec
18g cannula
ROI over descending aorta

25
Q

Protocol of CTA AAA

A

Scan on inspiration

Scan from above aortic arch to iliac arteries

Standard algorithm

Reformat ax. Cor. Sag

MRS432- CT (15 decks)

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