MR Venography Ivan Pedrosa, M.D. Beth Israel Deaconess Medical Center Harvard Medical School Boston, MA.

MR Venography

Ivan Pedrosa, M.D.Beth Israel Deaconess Medical Center

Harvard Medical School

Boston, MA

Why MR Imaging?

• Conventional venographyConventional venography

– Multiple injectionsMultiple injections– I.V. access in affected edematous extremityI.V. access in affected edematous extremity– Radiation / iodinated contrastRadiation / iodinated contrast

• USUS

– Limited in central veinsLimited in central veins– Limited FOV and anatomic landmarksLimited FOV and anatomic landmarks

Why MR Imaging?

• CTCT

– RadiationRadiation– Iodinated contrastIodinated contrast– Pitfalls due to poor opacification / Pitfalls due to poor opacification /

mixing artifactsmixing artifacts

• Nephrogenic Systemic Nephrogenic Systemic Fibrosis (NSF)Fibrosis (NSF)– Increased indications for non-contrast Increased indications for non-contrast

MRVMRV

MRV

• TechniquesTechniques

– Dark Blood ImagingDark Blood Imaging– Bright Blood ImagingBright Blood Imaging– Gd-enhanced MRVGd-enhanced MRV

• Clinical ApplicationsClinical Applications

– ChestChest– AbdomenAbdomen– PelvisPelvis

MRV techniques

Non-contrast MRVNon-contrast MRVDark blood SequencesDark blood Sequences Bright blood SequencesBright blood Sequences

Double IR Spin echo TOF

Double IR SSFSE GRE (Cine)

Dynamic SSFSE FIESTA (Cine)

Phase Contrast

Gd-enhanced MRVGd-enhanced MRV

3D FS T1-W GRE (VIBE, LAVA, THRIVE)

Spin Echo (“dark blood”)

180º

90º 90º

180º

HAlf-Fourier Single shot Turbo Spin Echo (HASTE or SSFSE)

SSFSE/HASTE

• One second to collect the whole image

• Dark blood• Protons exit slice

• Slow flow - ↑↑ SI• Thrombus - ↓↑ SI

K space

90º

180º

Dynamic HASTE

• Intravascular

signal void

VALSALVA

• Valsalva– intrathoracic P– Venous return

• T2 of blood is long

• Valsalva– intrathoracic P– Venous return

• T2 of blood is long

Dynamic HASTE VALSALVA

DB HASTE (“dark blood”)

90º

180º 180º

TI

180º 180º

TI

Double IR T1 FSE

IR-T1W Cardiac-gated IR-HASTE

1 slice (~16 sec) breath-hold ~20 slices ( sec) breath-hold

2 slices with ASSET

Bright blood Sequences

• TOF• GRE (Cine)• FIESTA (Cine)• Phase Contrast

Time-of-Flight (TOF)

Time-of-Flight (TOF)

Time-of-Flight (TOF)

Time-of-Flight (TOF)

Time-of-Flight (TOF)

Time-of-Flight (TOF)

Time-of-Flight (TOF)

Time-of-Flight (TOF)

TOF

TOF optimization for slow flow

TOF: in-plane saturation

Axial acquisitionSagittal SagittalGad-MRV

TOF optimization for slow flow

• Slice perpendicular to vessel of interest

• Decrease slice thickness

• Cardiac gating?

ECG ECG TracingTracing

Blood flow Blood flow (Pulse (Pulse Oximeter)Oximeter)

Systole (arterial)

True FISP / FIESTA / Balanced FFE

• True Fast Imaging with Steady-state Precession

• Gradients are fully balanced in order to recycle the transverse magnetization in long T2 species

• Contrast

– T2 / T1 ratio– Blood vessels are brightBlood vessels are bright (T2 of blood is )

True FISP

Pros

• Fast

– Road map

• No breathing artifacts

• Thrombus

– Filling defect SI

• Cine True FISP

– FIESTA

Cons

• Artifacts

– Pulsatile flow– Off-resonace

• Acute / subacute thrombus

True FISP

True FISP

True FISP Gd-enhanced MRV

True FISP

True FISP Gd-enhanced MRV

L

Pedrosa I. AJR 2005

Phase Contrast (PC)• 2 equal and opposite Venc gradients between the

excitation and echo.• With stationary protons, phase shifts induced by the first

gradient are reversed and canceled by the second gradient.

• In moving protons, the second gradient does not quite cancel out phase shifts induced by the first gradient

• These phase shifts are detected and proportional to the amount of motion in the direction of the encoding gradients

Phase Contrast (PC)

• Venc gradient applied in the slice (superior-inferior) direction

• In the phase (velocity) image

– Gray represents stationary background tissues

– White represents blood flowing caudally (towards feet)

– Black represents blood flowing cranially (towards head)

– The intensity of white or black represents the magnitude of velocity in the respective directions

Phase Phase ImageImage

Magnitude Magnitude ImageImage

High velocity flow High velocity flow towards the head towards the head (Ascending aorta)(Ascending aorta)

Moderate velocity Moderate velocity flow towards the head flow towards the head

(Pulmonary artery)(Pulmonary artery)

Moderate velocity Moderate velocity flow towards the feet flow towards the feet (SVC)(SVC)

High velocity flow High velocity flow towards the feet towards the feet (Descending aorta)(Descending aorta)

Phase Contrast (PC)

• If Venc is chosen to be too low, aliasing (“wrap-around artifact”) occurs when velocities exceed that value causing velocities to mimic a “lower” value

• If Venc is chosen to be too high, sensitivity to slow flow and accuracy of quantitative analysis of velocity/flow are diminished

• Venc for venous imaging?

– 40-60 cm/sec

VencVenc set to set to 140 cm/sec, 140 cm/sec, appropriate appropriate

for this for this volunteervolunteer

VencVenc set to set to 70 cm/sec, 70 cm/sec, too low for too low for

this volunteer. this volunteer. Aliasing or Aliasing or

“wrap-around” “wrap-around” results in the results in the high-velocity high-velocity flow areas of flow areas of

the aorta.the aorta.

Phase ImagesPhase Images

Phase Contrast (PC)

Venc = 40 cm/sec

Phase Contrast (PC)

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3D PC

Gadolinium-enhanced MRV

• Indirect MRV Indirect MRV

• Direct MRVDirect MRV

Indirect Venography

• I.V. access in any peripheral veinI.V. access in any peripheral vein

– Antecubital vein (Right UE)Antecubital vein (Right UE)

• GadoliniumGadolinium– Single dose (~Single dose (~20 cc) @ 2 cc/seg20 cc) @ 2 cc/seg

– Single dose (~Single dose (~20 cc) @ 0.8 cc/seg20 cc) @ 0.8 cc/seg

– 20 cc saline @ 0.8 cc/seg20 cc saline @ 0.8 cc/seg

• 3D GRE T13D GRE T1• SubtractionsSubtractions

– Venogram-like MIP reconstructionsVenogram-like MIP reconstructions

Double dose GdDouble dose GdSingle injection/dual rateSingle injection/dual rate

Timing arterial phase

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Indirect Venography

VENOUS PHASE

SUBTRACTION

- =

ARTERIALPHASE

Indirect Venography

SUBSTRACTION MIP

Direct Venography

• I.V. access in affected extremity or bilateral

• Gadolinium

– 5 cc Gd in 100 cc saline (1:20)

• Tourniquet in lower extremities

• 3D GRE T1

Li W et al. J Magn Reson Imaging 1998; 8(3): 630-3

Direct Venography

Thrombus Characterization

– Bland thrombusBland thrombus

– No enhancement– Variable SI

– Tumor thrombusTumor thrombus

–Enhancement on Gd-MRVEnhancement on Gd-MRV» Subtractions!» Absence of enhancement does NOT exclude

tumor thrombus

SI on T2-weighted imagesSI on T2-weighted images

Tumor thrombus: Intravenous leiomyomatosis

U

Staging

• Acute thrombusAcute thrombus– Enlargement of vein by intraluminal thrombusEnlargement of vein by intraluminal thrombus SI on T2-weighted imagesSI on T2-weighted images

• Vessel wallVessel wall• ThrombusThrombus

– Perivascular soft tissue edemaPerivascular soft tissue edema SI on T1-weighted images (subacute)SI on T1-weighted images (subacute)

• Chronic thrombusChronic thrombus– Vein attenuated or not visibleVein attenuated or not visible– Venous collateralsVenous collaterals– ↓↓ SI on all sequencesSI on all sequences

Acute thrombosis of the portal vein

T2W

T1W post-contrast

Paget von Schrotter syndrome or “effort” thrombosis

Chronic Thrombosis

Venous thrombosis

Is the thrombosis acute or chronic?

Do I need to anticoagulate this patient?

Acute/subacute thrombosis

brachiocephalic vein: chronic occlusion

Central catheter malfunction

Fibrin sheathFibrin sheath

Clinical Indications

SVC syndrome

Venous Access

• CCentral cathetersentral catheters

– Hemodyalisis– Chemotherapy– Parenteral nutrition– Thrombosis in first 3 months (10%)

• MRV chestMRV chest

– 15 pts with occlusion or stenosis central veins15 pts with occlusion or stenosis central veins– Venous access possible in 14 pts Venous access possible in 14 pts

Shinde TS et al. Radiology 1999;213:555-560

51 yo male with PE

Papillary carcinoma

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IVC in Renal Cell Carcinoma

Pulmonary Embolism

Isolated Iliac Vein DVT

Conclusion

• Central veins of the chestCentral veins of the chest, abdomen and , abdomen and pelvispelvis

– Limited evaluation with USLimited evaluation with US

• Whole-body venous roadmapWhole-body venous roadmap

– Vascular accessVascular access

• PregnancyPregnancy