Gd: MR Venography

Martin R. Prince, MD, PhD

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 RateCardiac Output

1T1

= R1 • [Gd]

Venous Blood

1T1

= R1

Injection rate

Cardiac output

Arterial Blood

100:1 dilution 50:1

dilution

0.1

0

1

510

20

30

40

5060

100

%Gd:DTPA Contrast Agent Dilution

3D SPGR TR/TE/Flip 6.5/1/45º

TE=1 TE=10

TE=10TE=5

TE=3TE=2TE=1

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

• 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

• 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

• inject one entire syringe (60 ml)

• Immediately switch to 2nd syringe

• start imaging with breath holding

during injection of 2nd 60ml syringe

Gd injection

Single Operator StrategyInject one arm at a time

Left arm injection

Right arm injection

Two Operator Strategy:

Inject both arms simultaneously

Vessels that are easily accessible

• arm vein

• pedal vein

• umbilical vein

• caput medussa

• brachial artery

• common femoral artery

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 necessaryCourtesy of James F. M. Meaney. MD