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Gd: MR Venography

Gd: MR Venography. Martin R. Prince, MD, PhD. Injection Rate. [ Gd] arterial = + [Gd] venous. Cardiac Output. Strategies to reduce Gd Dose. shorten scan duration time bolus for center of k-space digital subtraction higher relaxivity reduce cardiac output

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Gd: MR Venography

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  1. Gd: MR Venography Martin R. Prince, MD, PhD

  2. Injection Rate [Gd]arterial = + [Gd]venous Cardiac Output 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

  3. Injection rate 1 1 = R1 = R1 • [Gd] T1 T1 Cardiac output Arterial Blood Venous Blood 100:1 dilution 50:1 dilution

  4. %Gd:DTPA Contrast Agent Dilution 50 60 40 0 30 0.1 100 20 1 10 5 3D SPGR TR/TE/Flip 6.5/1/45º

  5. TE=1 TE=10

  6. TE=1 TE=2 TE=3 TE=5 TE=10

  7. 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

  8. Landmark Direct MR Venography Protocol • 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

  9. Prescription of 3D Imaging Volume • 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)

  10. Gd injection • inject one entire syringe (60 ml) • Immediately switch to 2nd syringe • start imaging with breath holding • during injection of 2nd 60ml syringe

  11. Single Operator Strategy Inject one arm at a time Left arm injection Right arm injection

  12. Two Operator Strategy: Inject both arms simultaneously

  13. Vessels that are easily accessible • arm vein • pedal vein • umbilical vein • caput medussa • brachial artery • common femoral artery

  14. 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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