Practical recommendations
M. Neuss, B. Schnackenburg
Angiography
n General problems
n Stents: No solution since stents currently
used effectively shield signal from inside the
stent lumen.
n Timing: It is possible that because of cardiovascular comorbidity not one timing suits all
patients with suspected renal artery stenosis.
Therefore, we recommend not to use a fixed
interval after the injection of contrast agent,
but to time on the fly using a 2D time resolved angio.
Renal arteries
Imaging of the renal arteries can be done in a
reliable way. For the sake of spatial resolution
we use a five-element phased array coil placed
over the upper part of the abdomen.
The use of parallel imaging techniques is preferred since they reduce breathhold time or increase spatial resolution if breathhold time is
kept constant.
15–18 ml of contrast agent, 20 ml of saline,
flow 3 ml/s in both.
n Scan procedure
1. Survey in SSFP technique, 3 stacks in transverse, sagittal, coronal orientation, 15–20
slices each, slice thickness 8–10 mm, negative
gap 1 mm.
2. Stack of transverse and coronal slices in SSFP
technique covering the kidneys. Slice thickness 8 mm, negative gap 2–4 mm, free
breathing. Spatial resolution 1.5 ´ 1.5 ´ 8 mm
(M/P/S).
3. If significant pathology of the aorta, acquire
proton-density weighted anatomical images
in blackblood technique with identical geometry as step 2.
4. Plan MR-angiography in coronal orientation.
We use 40–45 slices in a parallel imaging
contrast-enhanced 3D-T1TFE-angio tech-
nique, slice thickness 1.5–1.7 mm, matrix
352, resulting in a reconstructed voxel size of
1.1 ´ 1.1 ´ 1.7 mm (M/P/S). For the timing of
the angiography we use a 2D time resolved
angiography started at the injection of the
contrast agent. The actual 3D angiography is
started when the contrast agent enters the abdominal aorta.
5. For printouts of the angiography we reconstruct maximum intensity projections at an
angle of 38.
n Specific problems
n Stents: See above
n Timing: See above
n Foldover: Even if you use a subtraction technique, backfolding of the arm that you use
for injection of the contrast agent will occur.
Check for backfolding before injecting the
contrast agent, if necessary have the patient
raise the arms above the head or fold on the
abdomen.
Subclavian artery
For imaging of a suspected stenosis of a subclavian artery information on the suspected localization of the stenosis is preferable. To avoid interference with the detection of the stenosis it is
important to use the alternate arm for the injection of contrast agent.
If there is a suspected one-sided proximal
stenosis, it is possible to use a head-neck coil.
The advantage of this approach is that by using
this coil system it is possible to image the carotid, vertebral, and basilar arteries at the same
time. The reader is referred to the section on
carotid and vertebral arteries.
In other cases we use a five-system phased
array coil placed high on the thorax. Using an
angiography in an oblique sagittal orientation
imaging of both subclavian and axillar arteries
is possible, the origin and the proximal third of
the other supraaortic branches is visualized in
this approach in very good quality as well.
Using this approach the injection rate of contrast agent has to be at least 4 ml/s to prevent
the subclavian vein from still containing a lot of
contrast agent. 15–18 ml of contrast agent, 20
ml saline, flow 4–5 ml/s in both.
n Scan procedure
n Scan procedure
1. Survey in SSFP technique, 3 stacks in transverse, sagittal, coronal orientation, 15–20
slices each, slice thickness 8–10 mm, negative
gap 1 mm. If questions about the course of
the subclavian arteries remain, transverse
slices in SSFP technique covering the area of
interest. Slice thickness 8 mm, negative gap
2–4 mm, end-expiratory trigger.
2. Plan MR angiography in oblique sagittal orientation that is close to coronal. We use 40–
45 slices in a parallel imaging contrastenhanced 3D-T1TFE-angio technique, slice
thickness 1.5–1.7 mm, matrix 352, resulting
in a reconstructed voxel size of 1.1 ´ 1.1 ´
1.7 mm (M/P/S). For the timing of the angiography we use a 2D time-resolved angiography started at the injection of the contrast
agent. The actual 3D angiography is started
when the contrast agent enters the ascending
aorta.
3. For printouts of the angiography we reconstruct maximum intensity projections at an
angle of 38.
1. Survey, in transverse, sagittal, coronal orientation.
2. Inflow scout, maximum intensity projection
of inflow scout for further planning.
3. Plan MR angiography in coronal orientation.
We use 120 slices in a contrast-enhanced
3D-T1TFE-angio technique, slice thickness
0.5–0.55 mm, matrix 432, resulting in a reconstructed voxel size of 0.68 ´ 0.68 ´ 0.5 mm
(M/P/S). For the timing of the angiography
we use a 2D time resolved angiography (use
coil built into the magnet!) started at the injection of the contrast agent. The actual 3D angiography is started when the contrast agent
enters the tip of the lung parenchyma, at the
latest when arriving in the left ventricle.
4. For printouts of the angiography we reconstruct maximum intensity projections at an
angle of 38 in sagittal and transverse orientation.
n Specific problems
n Stents: See above.
n Timing: Carotid artery angiography is affected most by timing problems since late
timing results in jugular vein signal affecting
visualization of the carotid bulb at the origin
of the internal carotid artery.
Left sided valvular regurgitations are a serious problem since they slow down the progress of the contrast bolus after the 3D angio
sequence has been started when the contrast
agents reached the pulmonary parenchyma.
When information is available on significant
left-sided valvular regurgitations, start 3D angio only when contrast agent enters the left
ventricle.
Vertebral arteries outside FOV: A serious
problem that occurs if the head and neck are
not aligned with the receiver coil system.
Should become apparent in survey and needs
to be corrected by angulating the FOV.
n Stents: See above
n Timing: See above
n Foldover: Do dummy run first to check, increase size of RFOV if necessary. Have patient
not raise the arms since this may cause apparent stenosis of subclavian artery.
Carotid arteries, vertebral arteries,
basilar artery, Circulus of Willis
Using high field (³ 1.5 T) magnetic resonance
angiography image quality is sufficient to obviate the need for arterial DSA. It is mandatory to
use a dedicated receiver coil system for head
and neck.
The same coil system is used for suspected
proximal stenosis of the subclavian artery on
one side. In this case the FOV has to be moved
to one side to cover the proximal part of one
subclavian artery. If a distal stenosis or a stenosis on both sides is suspected, the reader is referred to the section on angiography of subclavian arteries. 15–18 ml of contrast agent, 20 ml
saline, flow 3 ml/s in both.
n Specific problems
Arteries of the lower extremities
Using high field (³ 1.5 T) magnetic resonance
angiography image quality is sufficient to obviate the need for arterial DSA. Using a system
that moves the table while the contrast bolus is
passing through the body an angiography of the
pelvic, upper and lower leg arteries can be acquired using a single injection of contrast agent.
This approach usually employs the receiver coil
built into the magnet. In other cases a dedicated
coil system is used.
Use available information on prior bypass
surgery. Extraanatomical bypasses such as femoro-femoral cross-over bypasses need to be
taken into account.
2 ml timing bolus contrast agent first (see
below), 8 ml saline, 2 ml/s for both, 10 ml saline, 0.2 ml/s. Angiography: 10 ml of contrast
agent, 2 ml/s, 10 ml of contrast agent 0.2 ml/s,
20 ml of saline, 0.2 ml/s. In severe obstructive
disease: 15–20 ml of contrast agent, 2 ml/s,
10 ml of contrast agent, 0.2 ml/s, 20 ml of saline,
0.2 ml/s.
n Scan procedure
1. Survey with inflow angio, 3 parallel stacks of
transverse slices, 30 slices each, slice thickness 3.3 mm, gap 11 mm.
2. 2D time resolved angiography in coronal orientation covering the pelvic arteries, 1 slice,
80 mm. 2 ml of contrast agent. Load images
after completion, read time when maximum
contrast appears in the pelvic arteries. This is
the time when your actual angiography has
to be started.
3. Plan subtraction angiography in coronal orientation. We use 3 stacks of 60 slices each,
slice thickness 1.7 mm, matrix 304, resulting
in a reconstructed voxel size of 0.84 ´ 0.84 ´
1.7 mm (M/P/S). The subtraction background
is acquired first, breathhold in inspiration for
the level of pelvic arteries. Injection of contrast agent, breathing commands such that
the patient is holding the breath in inspiration at the moment the contrast bolus is arriving in the pelvic arteries (time read from
2D angio). Table movement and free breathing for upper and lower leg arteries.
4. For printouts of the angiography we reconstruct maximum intensity projections at an
angle of 68 in sagittal orientation.
n Specific problems
n Timing: Should not be a major issue if a timing bolus is used.
n Insufficient contrast enhancement: A problem
if severe occlusive disease is present. Increase
total amount of contrast agent injected. If severe occlusive disease is suspected an additional 3D angio in lower leg position can be
acquired immediately after the actual moving
table angiography has been accomplished.
n Venous enhancement: Depends to some extent on the size of the patient. In short patients start the angiography 2 s earlier than
you would otherwise. In some patients with
severe occlusive disease the contrast agent
crosses in the calf muscles from the arteries
into muscle veins. We have no solution for
this problem.