mra of abdominal aortic aneurysms martin r. prince, md, phd
TRANSCRIPT
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
www.Mrprotocols.com
AAA Surgical Planning Issues• Proximal extent: classification• Distal Extent• Size• Character
– inflammatory– shaggy
• Associated Aneurysms• Occlusive Disease• Anatomic Variants
www.Mrprotocols.com
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
www.Mrprotocols.com
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
www.Mrprotocols.com
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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