Special Radiographic Procedures: MN Zephyr Vascular Imaging

Transcription

Special Radiographic Procedures:
Practical Vascular Imaging
Daniel A. Feeney DVM, MS
Professor of Veterinary Radiology
College of Veterinary Medicine
University of Minnesota
UNIVERSITY OF MINNESOTA
Veterinary Medical Center
MN Zephyr
Vascular Imaging
• Selective (including semi-selective):
– arterial
– venous
• Non-selective:
– venous only
• Parenchymal:
– splenic
– transhepatic
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Selective Angiography
• Indications:
– High-detail vascular imaging
– Shunt evaluation
• Contraindications:
–
–
–
–
Contrast medium hypersensitivity
Dehydration
Combined hepatic and renal failure
Coagulopathy or active anticoagulation
• Supplies:
– Sterile, iodinated [ionic or nonionic] contrast medium
– Preformed catheters (end-hole preferred for pressure,
side hole preferred for injection) [? Seldinger needle]
– Anticoagulated saline flush
– Power injector [arterial injections only] (@ 0.5ml/kg)
– Fluoroscope or C-arm for catheter guidance
– Suture material for tightening vessel around catheter
– Pressure monitor for “pull-through” stenosis evaluation
– Rapid image capture mechanism (video, digital, film)
• Precautions:
– Vascular perforation/direct wall injection
– Judicious anticoagulation/catheter flushing
• Technique:
– Insert catheter into access vessel of choice
– Advance catheter (under fluoroscopic guidance)
to desired point of injection/pressure
measurement
– Measure pressures, if applicable
– Make and capture injection “sequence”
– Flush
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• Interpretation:
– Regional morphology
• Chamber size, shape, location, connections
• Vessel size, shape, location, connections
– Flow direction (? normal, ? shunt)
– Pressure evaluation (? “above” and “below”
stenosis/valve/shunt)
• Caveats:
– Technically difficult
– Risky (don’t exceed 2.0 ml/lb total dose)
– Constant threat of thromboembolism
[worse with nonionic contrast medium]
– Be sure what you are trying to diagnose is
treatable and/or of prognostic value
(normal R/L ventricle)
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(PDA)
(Pulmonic Stenosis)
(Aortic Stenosis)
4
(VSD)
(normal operative splenoportogram)
[Diagram from J.P. Toombs, DVM, MS]
(Cranial Mesenteric Portogram)
[patent ductus venosis]
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(Operative Mesenteric Portogram)
[congenital portal-postcaval shunt]
[congenital portal-azygous shunt]
[acquired portosystemic shunt]
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(Semi-selective Renal Angiogram)
[end-stage kidneys]
Non-selective Angiography
• Indications:
– Identify chamber/vessel size, shape, etc.
– Assess blood flow direction
– Assess vessel invasion by local masses
– Dehydration
– Combined renal and hepatic failure
– Previous contrast medium reactions
• Supplies:
– Necessary instruments and catheters to gain access to
the vein of choice
– Sterile, iodinated (ionic or nonionic) contrast medium
• Precautions:
– Beware or thromboembolism
– Beware of contrast medium reactions
– Keep expectations realistic
(this is not a selective study)
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• Technique:
– Insert catheter into vessel
– Hand-inject contrast medium (@ 0.5mg.kg)
– Expose radiograph (regular machine, lateral or
VD view) at the appropriate time post
injection
•
•
•
•
2-5 seconds post injection for right ventricle
4-8 seconds post injection for left ventricle
Reassess as necessary
Reinject up to 4X
• Interpretation:
– Regional morphology
• Chamber size, shape, location, connections
• Vessel size, shape, location, connections
– Flow direction (? normal, ? shunt)
– NOTE:
technique not good for LÆR shunts
technique not good for distal arterial/limb
evaluation
• Caveats:
– Not good for LÆR shunts
– Not good for distal arterial/limb
evaluation
– Subject to rate of injection and filming rate
problems requiring frequent re-injection
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(Normal Feline Nonselective Angiocardiogram)
(Normal Canine Nonselective Angiocardiogram)
(Normal Cranial and Caudal Vena Cavogram)
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(Feline Aortic Thromboembolism)
(CVC Study/Retroperitoneal Mass)
(CVC Obstruction)
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(Adrenal Mass/CVC Invasion)
(Adrenal Mass/Aortic Partial Entrapment)
(A-V Fistula)
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Direct Parenchymal Injection
• Indications:
–
–
–
–
Assess splenic venous drainage pattern
?? assess lymph node morphology
?? assess miscellaneous parenchymal organ drainage
Assess cavity integrity (cavity injected)
– Coagulopathy
– Contrast medium sensitivity
• Supplies:
– Catheter of sufficient strength with stylet
– Injection extender (to limit stress on catheter)
– Sterile, iodinated [ionor or nonionic] contrast
medium
• Precautions:
– Bleeding
– Organ injury
• Technique:
– Direct parenchymal/cavity injection
of 0.5 ml/kg
– Film immediately after the injection is
terminated and shortly thereafter as long as
medium persists
– If attempting pleurography/peritoneography,
roll patient to assure contrast distribution
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• Interpretation:
– Where does contrast medium flow from organ
– Where does contrast medium flow within organ
• Caveats:
– Organ not injected (frequently a problem when
trying to perform transabdominal
splenoportography)
– Inadequate injection volume or flow rate
– Leakage from injection site hindering
evaluation
(Transabdominal Splenoportogram)
[portal-azygous shunt]
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Direct Cavitary Injection
(Positive Contrast Peritoneogram)
[Normal/Diaphragmatic Hernia]
Lymphatic Imaging
• Indications:
– Identify drainage status of regional nodes
(mets)
– Define internal node anatomy (mets)
– Find local lymphatic vessels and clarify their
status (lymphangectasia/thoracic duct)
Lymphatic Imaging
• Technique:
– Direct node or lymphatic tributary injection
(find using toe-web injection of NMB) of
“small” amount of sterile, iodinated contrast
medium
– Film immediately after the injection is
terminated and shortly thereafter as long as
medium persists
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Lymphatic Studies
(From Getty)
Lymphatic Studies
(Normal Lymphangiogram)
Lymphatic Studies
(Urethral TCC Æ Sublumbar Nodes)
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DMIR Steam
Practical Vascular Imaging
• Closing Comments:
– Limited use
– Much replaced by ultrasound, particularly
color-flow
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Special Radiographic Procedures: MN Zephyr Vascular Imaging

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