MRI - MRA Anatomy

MR ANGIOGRAPHY
Review 7

Learning Objectives
To describe clinical indications for MRA examinations in the circulatory system . To understand and recognize anatomy and landmarks. To show the proper scan protocols and procedures.

TOPICS
Indications
Heart Circulation
Contrast rate
General scanning protocols
Circle of Willis
Carotid artery
Thoracic aorta
Pulmonary
Abdominal
Renal
Lower Leg

MR ANGIOGRAPHY
What is MRA?
It is an increase of contrast in the vessels by maximizing signal from flowing blood or suppressing the signal from stationary residing tissue.

Digital subtraction MRA ( Out dated method )
Time of Flight MRA
Phase contrast MRA
Velocity encoding technique
Contrast enhanced MRA

MRA Advantages

No Ionizing Radiation
3-Dimensional
Rare Allergic Reactions
Anatomy and Physiology
High Accuracy

Time of Flight ( TOF )
TOF manipulates the longitudinal magnetization of stationary spins. TOF used coherent gradient echo sequences in combination with gradient moment rephasing to enhance flow. The TR is kept below the T1 relaxation time of the stationary tissue ( T1 recovery is prevented ). Inflow of protons produce siginal. Sat bands are used to in the opposite direction of the vessel you want to visualize.
In carotid MRA put sat pulse above.

Disadvantages of TOF
If a vessel is parallel to the FOV according to the velocity it can be saturated out and the vessel can be misdiagnosed.
High signal from background tissue (fat has a short t1 relaxation time shows bright)

TOF 2D AND 3D
2D is slice by slice
Coverage large area
Sensitive to slow flow
Low resolution is a disadvantage
In-plane saturation is a disadvantage
Venetian blind and pulsation artifacts
3D is a volume
High SNR
Thin contiguous slices
Only can cover a small area is the disadvantage

Phase contrast MRA
Uses differences in velocity
This will have an effect of phase shifts in moving spins, and provide image contrast in flowing vessels
Velocity encoding ( VENC )
VENC compensates for projected flow velocity in the vessels ( used in CMR )

Phase Contrast MRA
Analogous to Doppler ultrasound
Phase shifts in moving spins (i.e. blood) are measured
Phase is proportional to velocity
Allows quantification of blood flow and velocity
Flow Quantification analysis software used to produce
characteristic curves

Phase Contrast

CMR

Phase Contrast

Contrast Enhanced MRA

Contrast enhanced MRA
Uses a 3D T1 GE sequence
Uses a bolus injection
Timed with the arterial phase and can be repeated for the venous phase

MRI Compatible Power Injectors
Programmable
Automatic Injection
MRI Compatible
Allows rapid arterial injection of Gd-DTPA
www.medrad.com

INDICATIONS
Dissection
Aneurysms
Plaque
Stenosis
Morphology
Pre and Post surgical assessment
Arteriovenous malformation

Circle of Willis

Lateral cow MIP
1- INTERNAL CAROTID ARTERY
2- BASILAR ARTERY
3- POSTERIOR CEREBRAL ARTERY
4- MIDDLE CEREBRAL ARTERY
4
3
1
2

POSTERIOR VIEW MIP
1- ACA
2- MCA
3- PCA
4- ACA
5- BA
6- ICA
7 VERT
1
4
2
5
6
3
7

L-R MIP

A-P TUMBLE

POSTERIOR CIRCULATION
5
1- VERT
2- PICA
3- BAS
4- SCA
5- PCA
4
3
2
1

ANTERIOR CIRCULATIOM
1- ACA
2- MCA
3- SIPH
4- ICA
1
2
3
4

RAW DATA

MRV

CAROTID ANATOMY

ANATOMY

TOF Carotid

Blow up of Bifucation
1- COMMON CAROTID ARTERY
3- EXTERNAL ARTERY
3
2
1

CAROTID MRA WITH CONTRAST

PHASE CONTRAST SCOUTS

CAROTID
1- TOP OF ARCH
2- BRACHIOCEPHALIC ARTERY
3- RT. SUBCLAVIAN
4- RT. COMMON CAROTID
5- LT. COMMON CAROTID
6- LT. SUBCLAVIAN
7- VERTEBRAL ARTERY
7
4
5
3
6
2
1

CAROTID MRA WITH GADO
1- BIFUCATION C3/4
2- INTERNAL CAROTID
3- EXTERNAL CAROTID
4- VERTEBRAL ARTERY
3
4
2
1

VRT
1- EXTERNAL CAROTID ARTERY
3- VERTEBRAL ARTERY
1
2
3

VRT POSTERIOR VIEW
1- LT SUBCLAVIAN ARTERY
3- LT COMMON CAROTID ARTERY
4- VERTEBRAL ARTERIES
5- BASILAR ARTERY
5
4
3
1
2

MRP
1- BRACHIOCEPHALIC VEIN
3- LT COMMON CAROTID ARTERY
4- LT SUBCLAVIAN ARTERY
2
3
1
4

MPR
1
3
2
1- RT SUBCLAVIAN ARTERY
2- RT. COMMON CAROTID ARTERY
3- LT.COMMON CAROTID ARTERY
4- LT VERTEBRAL ARTERY
5- LT.SUBCLAVIAN ARTERY
5
4

MPR
1- CAROTID ARTERYS
2- VERTEBRAL ARTERYS
1
2

MPR
1- RT INTERNAL CAROTID
2- RT EXTERNAL CAROTID
3- LT INTERNAL CAROTID
4- LT EXTERNAL CAROTID
5- VERTEBRAL ARTERY
3
2
1
4
5

MPR
1- INTERNAL CAROTID
2- BASILAR ARTERY
1
2

MPR CINE

CIRCULATION IN THE HEART

THORACIC AORTA ANATOMY

ANATOMY

ANEURYSM

Thoracic MRA MIP
3
2
1- AORTIC ROOT
2- ASCENDING AORTA
3- AORTIC ARCH
4- DESCENDING AORTA
4
1

Thoracic MRA MIP
1- RT. CORONARY ARTERY
3- LT. COMMON COROTID ARTERY
4- LT. SUBCLAVIAN ARTERY
3
2
4
1

Thoracic VRT
1- SINUSE OF VALSALVA
2- AORTIC ROOT
1

MIPS CINE

Aorta MPR CINE

Pulmonary Angio
1
2
1- PULMONARY TRUNK
2- PULMONARY VEINS
3- LEFT ATRIUM
2
3
2

Pulmonary VRT

Pulmonary Angio

ABDOMINAL AORTA

CELIAC TRUNK

SMA

IMA

HEPATIC PORTAL VEIN

HEPATIC PORTAL VEIN
Note that the portal vein drains blood into the liver, not from the liver. The blood entering the liver from the portal vein, after being cleaned by the liver, flows into the inferior vena cava via the hepatic veins. The inferior mesenteric vein usually does not directly connect to the hepatic portal vein; it drains into the splenic vein.

Abdominal Aorta

Abdominal Aorta Posterior
5
1- RENAL ARTERY LEFT
2- ABDOMINAL AORTA
3- RENAL ARTERY RIGHT
4- SPLENIC ARTERY
5- HEPATIC ARTERY
4
3
1
2

Abdominal Aorta Anterior
3
1- RENAL ARTERY RIGHT
2- HEPATIC ARTERY
3- SPLENIC ARTERY
4-SUPERIOR MESENTERIC ARTERY
5- INFERIOR MESENTERIC ARTERY
2
1
4
5

LOWER ABD AORTA
1- COMMON ILIAC ARTERIES
2- INTERNAL ILIAC ATERIES
3- IMA
4- EXTERNAL ILIAC ARTERY
3
1
4
2

Abdominal Aorta Lateral
1
1- CELIAC TRUNK
2- SMA
3- IMA
2
3

Abdominal Aorta VRT

SMA
Celiac
SMA
Celiac
IMA
Reconstructing Sagittal MIP of Aorta
Use axial image as a guide to reconstruct sagittal MIP of aorta
Axial reformation
Sagittal subvolume MIP

Volume Rendering
May Hide Dissections
Normal

MPR CELIAC TRUNK
1- HEPATIC ARTERY
2- SPLENIC ARTERY
3- LT. GASTRIC ARTERY
4- ABDOMINAL AORTA
1
2
4
3

Abdominal MPR

Aortic Dissection

Abdominal Aortic Aneurysm
Coronal MIP
Sag T1
Sag MIP
3D Gadolinium MR Angiography

Coronal 3D Gd MRA of Portal Vein

Coronal Plane
Field of view = width of patient (28-32 cm)
Thick slices: 3-5 mm
Zero padding
Fast enough for breath holding
TR < 10 msec
TE < 3 msec
Partial Fourier imaging (0.5 NEX)
Adjust phase encoding steps (128-224)
Three phases
Arterial
Portal venous
Equilibrium

Arterial
Portal-venous
www.MRprotocols.com

RENAL MRA
RENAL ARTERIES ARE AT THE LEVEL OF L1-L2

Renal circulation

MPR OF RENAL

Renal MRA MIP
3
1- RENAL ARTERY
2- SMA
3- RENAL ARTERY
2
1

Renal MRA VRT
1- LEFT RENAL ARTERY
2- RIGHT RENAL ARTERY
3- ABDOMINAL AORTA
3
1
2
POSTERIOR VIEW

Volume Rendering
May Hide Dissections
Normal

Axial reformation
Right Renal Artery
Coronal Oblique MIP Reform
Axial Oblique Reformation
Right Renal Artery
Right Renal Artery
Right Renal Artery: Perpendicular MIPs

Stenosis Pre and Post Angioplasty
Pre angioplasty
Post angioplasty

71 year-old male with hypertension
Arterial phase
Venous phase
Equilibrium phase

2 STAGE RENAL SCAN
Arterial phase
Venous phase
Venous phase

DUAL PHASE
3D Gd: arterial phase
3D Gd: venous phase

LOWER LEG CTA
Peripheral Vascular Disease:
Occlusive and Aneurismal Disease
Evaluate extent of disease
Plan future intervention
Extremity CTA Indications
Assess previous surgery
Trauma
Congenital changes

LOWER LEG ARTERY

UPPER STAGE RUNOFF
1- COMMON ILIAC ARTERY
2- INTERNAL ILIAC ARTERY
3- EXTERNAL ILIAC ARTERY
1
2
3

2ND STAGE RUNOFF

2ND STAGE RUNOFF
2
1- DEEP FEMORAL
2- FEMORAL ARTERY
1

3RD STAGE RUNOFF
1- POPLITEAL ARTERY
2- ANTERIOR TIBIAL ARTERY
3- PERONEAL ARTERY
4- POSTERIOR ARTERY
1
2
3
4

Runoff MRA

MRA Summary