GI MRI

Question 1

What are the common MRI exams in the abdomen?

Answer 1

• Liver
• MRCP
• small bowel
• Pancreas
• Rectum
  -Fistula

Question 2

What does ANTT stand for?

Answer 2

Aseptic Non-touch technique

Question 3

How long do we have to observe after contrast injection?

Answer 3

30 mins

Question 4

What are the common drugs used in GI MRI?

Answer 4

Buscopan - antispasmodic
Primovist - contrast (liver specific)
Gadovist - contrast
Mannitol - sugar based molecule - it distends the bowel to view lumen/ walls

Question 5

What are the T1 sequences used for GI imaging?

Answer 5

Fast field echoes (FLASH, FSE or SPGR)
3D spoiled GE with fat sat (VIBE / eTHRIVE)

Question 6

How do fluids appear and what’s the weighting of T1/2 balanced gradients?

Answer 6

T1 weighing but with T2 bright fluids

Question 7

Why do we do a DWI?

Answer 7

• DWI shows active disease
• Tumours in the rectum
• Inflammation in small bowel

May reduce the need for contrast

Question 8

Why do T2 images with longer TEs

Answer 8

To differentiate between cysts and Haemangioma

Question 9

What happens to cysts and haemangiomas with long TEs?

Answer 9

Haemangiomas - lose signal after longer TE
Cysts remain high signal

Question 10

How long to liver scans take?

Answer 10

45 min
NBM 4 hours prior

Question 11

Why do we use MRI for liver scanning?

Answer 11

Characterisation of liver lesions/ staging of tumours

Cirrhosis or fatty liver

Question 12

Which contrast do we use for liver scanning?

Answer 12

Primovist or gadovist

Question 13

What a re the special considerations with primovist?
What level risk is it?

Answer 13

All pt must have eGFR
Medium risk
transient dysponea in 30% of patients
Can lengthen QT interval - contraindicated with arrhythmias

Question 14

How do we characterise liver lesions on MRI?
5 stages

Answer 14

1. Pre-contrast
2. arterial - full contrast after st bolus for liver (25-30 sec)
3. Portal venous phase (80 - 1.20 sec)
4. 3 min post con = equilibrium phase
5. 15 min post con = delayed phase

Question 15

How much primovist is excreted in the billary tree?

Answer 15

50%

Question 16

How much contrast will Met’s take up?

Answer 16

None

Question 17

How do they differentiate between lesions in MRI with contrast?

Answer 17

Different lesions will take up and eliminate at different times

Question 18

How do haemangiomas take up contrast?

Answer 18

They take contrast up rapidly, starting at the outside then filling in centripetally

Question 19

How does focal nodual hyperplasia appear on MRI?

Answer 19

Holds onto contrast - scar on liver with central dark patch

Question 20

How does cirrhosis appear on MRI

Answer 20

Fibrosed and irregular contour

Question 21

How do we assess fatty liver on MRI?
What the TE of the 2 phases?

Answer 21

We use dual echo fast field T1

During TI relaxation fats and water relax at different speeds due to the different density in hydrogen protons

H Out of phase = TE = 2.3ms
H Inphase = TE- 4.6ms

Question 22

How big should a spleen be?

Answer 22

No more than 14 cm but average 11 -12cm

Question 23

What is MRCP and what’s it used for?
How long does it take?

Answer 23

MR cholangiopancreatography

Is used to look for obstruction of bile and pancreatic ducts causes _ stones/ tumours etc.

Non - con and no drug _ -takes 15 min
NBM - hours

Question 24

Which weighting is a MRCP?

Answer 24

T2. Long TE only signal from fluids

Question 25

What is involved in MRI pancreas?

Answer 25

30 min - NBM 4 hours
Dynamic contrast scan

Used to look for Ca in head of pancreas
IPMN - Introduction papillarymuscneus neoplasm

Question 26

What is the name of small bowel MRI?

Answer 26

MR enterography

Question 27

What is involved with Small bowel MR(SMBO)?

Answer 27

Can be contrast or non con
20 min with 1 hour prep and 4 hour NBM

+/- Gadovist, Buscopan, mannitol

Question 28

What is SMBO MR used to for?

Answer 28

To distinguish between IBS and IBD
To monitor Crohn’s disease, and to look for strictures

Question 29

What is the prep for SMBO MR?

Answer 29

Mannitol
- Long chain, sugar molecule
- 200 mils monitor in 1200 mils of water over 45 minutes
- Laxative effect and descends the bowel

Buscopan
- Anti spasmodic
- IM or IV
- Acting
- Minimises, peristatic motion and reduces flow voids on T2 TSE

Question 30

What are the 3 stages of enhancement for small bowel?

Answer 30

1. Homogeneous
2. Mucosal
3. Layered

1-3 increasing severity

Question 31

What is the definition of a fistula?

Answer 31

Abnormal tract
Leads from One mucus surface to another

Or

From Mucus surface to the skin

Question 32

What is the definition of a sinus?

Answer 32

An abnormal tract from the skin or mucus surface to a deep, seated area of suppuration (pus)

Question 33

What are the symptoms of anal fistulas?

Answer 33

• Pain/throbbing
  *redness and swelling
• offensive discharge
• Passing blood/ pus when defecting
• occasionally causes bowel incontinence

Question 34

What is involved in an MR Fistula and what are they used for?

Answer 34

Non con and no drug
20 min - no NBM

Demonstrated disease progression
Predicts prognosis

Question 35

What does Dixon MR fat suppressed show?

Answer 35

Fistula detail more clear

Question 36

What does MR Dixon in phase echo show?

Answer 36

Anatomy clearly

Question 37

What are the treatments for anal fistulas?

Answer 37

Fistulotomy - cutting open the fistula - heals into a flat scar

Setons procedure - Silicone strong placed in fistula to allow drainage

Question 38

What is involved with MR rectum?

Answer 38

Non con - around 45 min no NBM needed

Used to stage rectal carcinoma and decide treatment protocols

Drugs - IM/IV Buscopan