MRA ofAbdominal Aortic Aneurysms

Martin R. Prince, MD, PhD

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AAA DefinitionNormal Abdominal Aorta = 1.4-2.1 cm*

Aneurysmal Abdominal Aorta > 3 cm*

*measure outer wall to outer wall

6.9 cmwww.Mrprotocols.com

AAA Natural HistoryExpansion rate = 2-4 mm/year

– Larger aneurysms expand faster than small diameter aneurysms

– > 5mm in 6 months risk of rupture

Risk of Rupture (over 5 years)

< 4 cm 2% follow

4-5 cm 3-12% +/- repair

> 5 cm 25-41% repair 9.2 cm

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Imaging AAA• Ultrasound - screening and following

• CT - suspected rupture- following with precision

• MRA - pre-operative planning- following with precision

• Angio - contraindication to MR- resolving issues- stent graft placement

Ultrasound

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AAA Surgical MortalityElective: 4%

6% w/ late complications

Ruptured: 49%

(23%-69%)

CT shows aortic rupturewww.Mrprotocols.com

AAA MRA Technique

• Sag T1 or SSFSE 7 min• Coronal 3D Gd MRA 30s x 3• Axial 2D TOF post Gd 7 min• Axial 3D PC (Venc = 30 cm/sec) 8min

Total imaging time ~24 minutes

Sequences Time

Sag T1www.Mrprotocols.com

3D Gd MRA • Gd dose = 40 ml

• Gd bolus timing is critical

• SmartPrep 8 sec image acquisition delay

• 3 mm slices: Zip 1.5mm

• Include iliac arteries

• Exclude anterior part of AAA

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Check iliac Artery Position

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Axial 2D Time of Flight

• Post Gd

• Thick slices

• 4 NEX

• Respiratory compersation

• No saturation pulse

• Cover from celiac to femoral head

• Use large Gap (10-20 cm)

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Axial 3D PC

• Post Gd

• 2.5 mm slice thickness

• encode in all 3 directions

• Venc = 30 cm/sec

• reconstruct overlapping axial MIPs

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AAA Surgical Planning Issues• Proximal extent: classification• Distal Extent• Size• Character

– inflammatory– shaggy

• Associated Aneurysms• Occlusive Disease• Anatomic Variants

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AAA Classification• Thoraco abdominal• suprarenal• pararenal• juxtarenal• infrarenal

Thick MIP Thinner MIPwww.Mrprotocols.com

Suprarenal AAA

Aneurysm ends above celiac

Sag Oblique MIPwww.Mrprotocols.com

AAA Classification• Thoraco abdominal• suprarenal• pararenal• juxtarenal• infrarenal

Coronal MIP Sagittal MIPwww.Mrprotocols.com

Pararenal

Coronal MIP Sagittal MIPAxial MIP

Renal artery arises from aneurysm

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AAA Classification• Thoraco abdominal• suprarenal• pararenal• juxtarenal• infrarenal

Coronal MIP

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Juxtarenal

9mm

Aneurysm begins within 1 cm of renal artery origins:

Clamp above renals

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AAA Classification• Thoraco abdominal• suprarenal• pararenal• juxtarenal• infrarenal

Thick MIP Thinner MIP

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Infrarenal AAA> 1cm between AAA & renal artery

3.2 cm

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AAA Surgical Planning Issues• Proximal extent: classification• Distal Extent• Size• Character

– inflammatory– shaggy

• Associated Aneurysms• Occlusive Disease• Anatomic Variants

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AAA Surgical Planning Issues• Proximal extent: classification• Distal Extent• Size• Character

– inflammatory– shaggy

• Associated Aneurysms• Occlusive Disease• Anatomic Variants

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AAA Surgical Planning Issues• Proximal extent: classification• Distal Extent• Size• Character

– inflammatory– shaggy

• Associated Aneurysms• Occlusive Disease• Anatomic Variants

Retroperitoneal enhancement

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AAA Surgical Planning Issues• Proximal extent: classification• Distal Extent• Size• Character

– inflammatory– shaggy

• Associated Aneurysms• Occlusive Disease• Anatomic Variants

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AAA Surgical Planning Issues• Proximal extent: classification• Distal Extent• Size• Character

– inflammatory– shaggy– dissecting

• Associated Aneurysms• Occlusive Disease• Anatomic Variants

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AAA Surgical Planning Issues• Proximal extent: classification• Distal Extent• Size• Character

– inflammatory– shaggy

• Associated Aneurysms• Occlusive Disease• Anatomic Variants

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Aneurysms associated with AAA

• thoracic aorta• iliac• common femoral• popliteal• renal• visceral

Coronal MIP Sag MIP

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Renal Artery Aneurysms

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AAA Surgical Planning Issues• Proximal extent: classification• Distal Extent• Size• Character

– inflammatory– shaggy

• Associated Aneurysms• Occlusive Disease• Anatomic Variants

Coronal MIP

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Post tube graft:iliac aneurysms

left renal artery stenosis

Coronal MIP Mag Coronal thin MIPwww.Mrprotocols.com

AAA Surgical Planning Issues• Proximal extent: classification• Distal Extent• Size• Character

– inflammatory– shaggy

• Associated Aneurysms• Occlusive Disease• Anatomic Variants

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AAA w/accessory renal arteries

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Retroaortic left renal vein

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Summary

• MRA for pre-op AAA evaluation• Gd is essential• No nephrotoxicity• Analyze data systematically

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