4. - The basic arrangement of the spinal
system consists of a metameric grid of
trasversely oriented segmental
vessels, connected by various
longitudinal channels -
Primitive embryonic
vascular system of the
spine
http://neuroangio.org/
9. Anterior Spinal Artery
1) Origin from the vertebral arteries
1) Longitudinal vessel connecting
transversely oriented segmental
arteries
3) Located on the ventral surface of
the cord, in the median fissure
10. Origin of the ASA from the Vertebral Arteries
Circle of
Willis
Vertebral
Artery
Vertebral
Artery
ASA
11. Anterior Spinal Artery
1) It is bigger in the cervical and
lumbar tract
2) Larger segments of the ASA are
associated with larger
radiculomedullary arteries at those
levels (Artery of Adamkiewicz –
lumbar; and Lazhortes – cervical)
13. Posterior Spinal Arteries
1) They are two, origin from the
vertebral arteries
2) Dorsal surface of the spinal cord
1) Receiving blood from the
radiculary arteries
18. Venous System of the
Spine
INTRINSIC EXTRINSIC EXTADURAL
CENTRAL PERIPHERAL
PIAL
VENOUS
NETWORK
VENTRAL
AND
DORSAL
MEDIAN
VEINS(axial oriented)
(longitudinal oriented)
19. Lasjaunias and Berenstein 1990; Griessenauer et al. 2015
Intrinsic
System
Extrinsic Pial
network
Anterior
and
posterior
spinal
veins(follow the arteries)
20. Anterior and Posterior Spinal Veins
(number can vary 1 to 3)
Radicular Vein (follows radicular artery)
Radicular veins are the connection between the extrinsic and extradural
venous system!!!
21. Venous System of the
Spine
INTRINSIC EXTRINSIC EXTADURAL
CENTRAL PERIPHERAL
PIAL
VENOUS
NETWORK
VENTRAL
AND
DORSAL
MEDIAN
VEINS(axial oriented)
(longitudinal oriented)
22. Extradural System
1) Internal vertebral plexus (within the vertebral canal)
2) External vertebral plexus (surrounds the vertebral column)
3) Basi-vertebral Plexus (within the vertebral body)
4) Intervertebral veins
30. SPINAL CORD MR ANGIOGRAPHY :
GOALS
1) Localizing normal arteries and
veins (surgical and interventional
applications)
2) Pathology
Aortic Aneurysm surgery: identification of AKA will avoid spinal cord
ischemia
Avoid AKA embolization during treatment of vascular malformations
31. SPINAL CORD MR ANGIOGRAPHY :
REQUIREMENTS
COVERAGE
SPATIAL
RESOLUTION
TEMPORAL
RESOLUTION
“Improving one of these items generally
degrades one or both of the other
requirements”
Backes et al. AJNR 2008
32. COVERAGE
AKA : may originate from any segmental
artery of the thoracolumbar spine
CC FOV = 50 cm
Takase et al. Radiology
2002
35. Phase 1 :
arteries
Phase 2 :
arteries + veins
AJNR Am J Neuroradiol 29:619 –31 Apr 2008
AV circulation
time 9-12 sec
36. SPINAL CORD MR ANGIOGRAPHY :
TECHNIQUE
- TOF and PCA techniques have good
spatial resolution but are not able to
depict the normal spinal arteries
- Vessel-to-background contrast
depends on high flow
- Flow in small spinal vessels is too low
to provide enough signal intensity
changes
- Poor suppression of background tissue
signalPattany PM, Saraf-Lavi E, Bowen BC. MR angiography of the spine and spinal
cord. Top Magn Reson Imaging 2003;14:444–60
37. CONTRAST ENHANCED 3D MR
ANGIOGRAPHY
BOLUS OF CONTRAST: 0.2-0.3 mmol Gd-DTPA/kg at 3 mL/s
SHORTEST TE (2-8 ms): Best signal of enhanced blood / minimizing T2*
degrading effect
SHORTEST TR (< 10 ms): Best suppression of the background (spine, CSF,
cord tissue)
3D Fast-Gradient recalled echo with centric K-space filling
ACQUISITION TIME 40 sec FOR EVERY DATA SET: But the AV transit time is
about 10 sec timing of arrival of bolus + synchronizing centric K space
sampling
NB: scan delay acquisition time is set with 2 ml test bolus by MR
fluoroscopy or with auto triggering
39. AUTOMATED TRIGGERING
- IV contrast injection followed by
continuous image acquisition
- When the desired signal intensity
is reached the proper contrast
enhancement is started
- Automated triggering is better for
the centric k-space filling
- Better for Pediatric MRA: Tot
volume injected in children is 1-2
mL
- From segmental arteries there are feeding vessels for the bone marrow(D in the figure)
- Than segmental arteries divides in intercostal branches and dorsal branches, which goes to the posterior element of the column (H in figure) and to the pia/dura and medulla (Ka and P)
L’aorta non si vede in questa figura, G si chiama PRETRANSVERSE ANASTOMOTIC NETWORK
This shows the origin from the vertebral arteries.
…not to be confused with….
Another scream from greys anatomy….. I don’t know why I had thisobsession with greys anatomy preparing this presentation…. But anyway…
Intrinsic system : Longitudinal (1) and axial (2;3) oriented intrinsic system. In red. You will never see this intrinsic system on imaging.
Extrinisc pial network: on the surface of the spine (green): remember the pia is the closest membrane surrounding the spinal cord!!
Extrinsix longitudinal veins (anterior and posterior) : in yellow they follow the anterior and posterior spinal arteries.
In this pic there are 3 post and 1 ant but the number can vary according to the spinal segment and the person.
Internal and external vertebral plexi are anterior and posterior
Where the blood from intervertebral veins goes?
CERVICAL LEVEL VEIN OF THE NECK, THORACIC LEVEL: VEIN OF THE THORAX , LUMBAR VEINS
LEFT: Cervical level, vein drainage vertebral plexus of the vertebral artery, vertebral veins and deep cervical vein.
RIGHT:
Note the cervical venous drainage and the thoracic drainage through intervertebral veins.
Our expert DEREK
Balancment among : coverage , spatial resolution and temporal resolution
Let’s explain every single of these goal: 1) coverage , because the aka (very important!) can may originate from any semgnetal artery of the thoracolumbar spine , so it has a variable location.
Let’s explain every single of these goals
Let’s explain every single of these goals
AV circulation time depends upon age, anesthesia, segment of the spine analyzed.
Shortest TE (eco time) means best signal of enhanced blood because of the T1 shortening of the blood with high concentration of Gadolinium
Shortest TR (repetition time): the background have relatively longer T1 relaxation time in comparison with enhanced blood.
Centric K space filling means that the lowest spatial frequency point are sampled first, this central points contribute most to overall image contrast which is timed to arrival of arterial bolus.
This is the second technique to coordinate the acquisition with the arterial time. It is better in case of central fillin of k-space since the k space is filled in the center at peak of enhancement.
NB: second phase will be also useful in order to identify vertebral levels which is birght in
Parameter proposed by Backes for a 1.5 T we have already seen most of them. Just remember the frequency encoding is CC because follow the major axis of the body part to be analyzed (in this case being the spine).
Remember a phase of precontrast acquisition used for subtraction.
Acquisition is sagittal
GARV GREAT ANTERIOR RADICULO-MEDULLARY VEIN
(A) MR image from a patient with acute onset of paraplegia shows extensive serpiginous flow voids (white curved arrow) along the dorsal surface of the spinal cord and increased signal (white solid arrow) within the cord, reflecting edema. (B) MRA MIP image shows the tortuous draining veins (white open arrow) of the AVM, corresponding to the flow voids.