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Published byFlora Houston Modified over 9 years ago
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Gd: MR Venography Martin R. Prince, MD, PhD
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Strategies to reduce Gd Dose shorten scan duration time bolus for center of k-space digital subtraction higher relaxivity reduce cardiac output inject vessel directly [Gd] arterial = + [Gd] venous Injection Rate Cardiac Output
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1 T1T1 = R 1 [Gd] Venous Blood 1 T1T1 = R 1 Injection rate Cardiac output Arterial Blood 100:1 dilution 50:1 dilution
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0.1 0 1 5 10 20 30 40 50 60 100 %Gd:DTPA Contrast Agent Dilution 3D SPGR TR/TE/Flip 6.5/1/45º
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TE=1TE=10
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TE=5 TE=3TE=2TE=1
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Conventional Upper Extremity Venography Radiation exposure Multiple stations Variable flow rate Difficult to time breath holding Large dose of iodinated contrast Contrast dilution obscures central veins
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Large caliber iv in forearm Elevate arms with cushions Coil: one arm torso coil two arms body coil Sagittal Locator Coronal 3D Spoiled Gradient Echo 5cc Gd:DTPA in 250 cc NS (50:1) Load 2, 60 cc syringes for each arm Use automatic valve to instantly switch from 1st to 2nd syringe Landmark Direct MR Venography Protocol
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Coronal Plane Anterior to Clavicle Posterior to Right Atrium Superior to Mandible Use Maximum Field-of-View Fast scan to permit breath holding thick slices (4-5mm) zero interpolation (ZIP x 2) partial Fourier imaging (0.5 NEX) Prescription of 3D Imaging Volume
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inject one entire syringe (60 ml) Immediately switch to 2nd syringe start imaging with breath holding during injection of 2nd 60ml syringe Gd injection
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Single Operator Strategy Inject one arm at a time Left arm injection Right arm injection
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Two Operator Strategy : Inject both arms simultaneously
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Vessels that are easily accessible arm vein pedal vein umbilical vein caput medussa brachial artery common femoral artery
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Summary IV injection excellent venograms dilute Gd at least 10:1 inject large volumes two 60 ml syringes per arm inject rapidly breath holding essential repeat as necessary Courtesy of James F. M. Meaney. MD
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