Ultrasound Assessment of Intracranial Dural Arteriovenous Fistulas (DAVF

18-19 JUNE 2013
Part 3/3
Ultrasound Training Course

Intracranial dural arteriovenous
(DAVF)
• Feeding arteries of DAVF show hemodynamic
abnormalities, which include increased blood flow,
systolic and, especially, end-diastolic velocities, and a
decreased resistance index
• Ultrasound assessment before and after interventional
therapy of intracranial DAVF.
• CDS of the ECA is a reliable screening tool for detecting
DAVF.
• Endovascular or surgical therapy of DAVF will reduce or
normalize flow velocities of the feeders and increase the
RI of the ECA
• The additional assessment of the global cerebral
circulation time by using Doppler echo contrast-bolus
tracking may prove useful for screening and follow-up of
DAVF

(DAVF)
• Measurement of flow velocities in draining veins and
sinuses using contrast-enhanced transcranial Doppler
sonography is another technique, which allows the
assessment of hemodynamic changes occurring after
the occlusion of DAVF
• Contrast-enhanced transtemporal CDS may be useful for
screening patients with clinical suspicion of DAVF of
transverse/sigmoid sinus and assessing the results of
interventional therapy.

(DAVF)

(DAVF)
Extracranial color duplex sonography
findings in a patient with a dural fistula
to the transverse sinus. The common
(a) and internal (b) carotid arteries show
normal Doppler spectra, whereas the
external carotid artery (c) shows
increased systolic and, particularly,
diastolic flow velocities.

(DAVF)
Extracranial color duplex sonography
findings in a patient with a dural fistula to
the transverse/sigmoid sinus. The feeding
occipital artery is dilated and shows an
abnormal Doppler spectrum with increased
systolic and, especially, diastolic flow
velocities
(a), divides into two branches with normal
(b) and abnormal (c) Doppler spectra
supplying the dural fistula.

Carotid Cavernous Fistulas
• The confirmation of a CCF depends on cerebral vascular
angiography.
• However, the application of angiography is often limited
because it is invasive and expensive.
• Sometimes, it is not necessary to undergo invasive
diagnostic measures and treatments in low-flow CCFs
because the patients with such kinds of CCFs have more
chance of spontaneous resolution.
• Color Doppler ultrasonography (CDUS), which is much
less expensive and noninvasive, makes monitoring the
blood flow in real time possible.

• Transcranial studies including transtemporal and
transoccipital acoustic windows were performed with
ultrasonography systems equipped with a 2- to 2.5-MHz
sector scan transducer
• The orbital window and carotid vessels were examined
with a 5- to 13-MHz linear array transducer.
• With the patient in a supine position, the internal carotid
artery (ICA), anterior cerebral artery (ACA), middle
cerebral artery (MCA), and posterior cerebral artery
(PCA) and the tip of the basilar artery (BA) were
examined through the temporal window.
• Scanning depths were regularly set between 140 and
160 mm to sufficiently visualize the contralateral skull

• The hypoechoic mesencephalic brain stem in a “heart” or “butterfly”
shape was visualized in axial sections. This section was regarded
as a “standard section” to orientate the circle of Willis by using the
color mode.
• In the normal situation, a symmetric little round cluster of blood flow
was visualized beneath both sides of the strong echo of the anterior
clinoid.
• It is the cross section of the siphonic segment of the ICA
• The maximal cross-sectional areas of the ICA were measured from
the frozen ultrasonographic image by tracing around the round
cluster.
• From the study of healthy subjects, the area ranged from 0.2 to 0.5
cm2.
• The asymmetric cluster of blood flow in this section and the area
larger than 1 cm2 were regarded as abnormal.

• With the patient in a prone position, the vertebral artery
(VA) and lower parts of the BA were insonated through
the occipital foramen and shown as a Y shape.
• Through the orbital window, the ophthalmic artery (OA)
and superior ophthalmic vein (SOV) were observed.
• Special emphasis was placed on maximal systolic
velocity (Vmax) and resistive index (RI).

Carotid Cavernous Fistulas:
Temporal window
A, Axial cross section showing a
symmetric little round cluster of
blood flow of the normal intracranial
ICA.
B, Orientation: 1 indicates ipsilateral
ICA; 2, contralateral ICA; 3,
contralateral skull bone; and 4,
ipsilateral anterior clinoid.
C, Color-coded image showing an
abnormal mosaic flow
flash of the CCF in the left
cavernous sinus area (arrow) and a
normal round cluster of the
contralateral ICA (arrow). D,
Orientation: 1 indicates CCF;
2, contralateral ICA; 3, contralateral
skull bone; and 4, anterior clinoid.
The asymmetric cluster of blood flow beneath both sides of the anterior clinoid was
visualized in axial sections. A cross section of the ipsilateral ICA was presented as
irregular mosaic color shade. Its area was much larger than that of the contralateral
ICA (range, 1.7–5.2 cm2; Figure 1, C and D).

Spectrum of a CCF showing
turbulent blood flow. The peak
velocity ranged from 65 to 190
cm/s. Peak velocity decreased
immediately with compression of
the ipsilateral carotid artery and
increased rapidly right after relief
of the compression and ascended
slightly higher than that before
compression.

The RI of the ipsilateral ICA was lower than that of the contralateral ICA
and that in the control group. The Vmax of the ipsilateral MCA, ACA, and
OA was significantly lower than that of the contralateral arteries and that
in the control group. The RI of the ipsilateral ACA and bilateral VA was
lower than that in the control group. The RI of the ipsilateral PCA was
lower than that of the contralateral artery.

Transorbital CDUS
A, Transorbital color-coded image
showing a normal SOV with blue
blood flowing away from the
transducer.
B, Doppler mapping showing a
continuous low-velocity venous
spectral wave of the normal SOV
C, Color-coded image of the
orbit ipsilateral to the CCF
showing an engorged SOV
with red flow toward the
transducer.
D, Doppler mapping of the
SOV showing high-velocity and
low-resistance arterialized
blood flow with a reversed
direction.
Transorbital CDUS showed a markedly dilated SOV in the affected side in all patients. The
shape of the spectra wave revealed that blood flow changed to an arterialized pattern in a
reversed direction with high velocity (34.5 ± 8.7 cm/s) and a low RI (0.31 ± 0.08)

Characteristic Ultrasonographic
Images
• Color Doppler ultrasonography makes it possible to monitor the
hemodynamic alteration.
• Here are some features that are useful in identifying a CCF.
– Color Doppler imaging shows an irregular color mosaic flash in the
cavernous region that is markedly larger than the normal cross-sectional
area of the ICA.
– When the ipsilateral carotid artery is compressed, the color mosaic
decreases or disappears.
– It is important to adjust the color gain properly; otherwise, excessive
gain may cause pseudoimaging of “overflow.”
– The blood flow draining from the high-pressure artery to the low-
pressure venous sinus was turbulent, disordered, and of multidirectional
spectra.
– The bruit is synchronous with the heart rhythm.
– The velocity decreased immediately when the carotid compression test
was performed and increased rapidly right after relief to slightly higher
than before the test.

• The arteriovenous direct shunting causes intracranial “steal
phenomena.”
• To compensate the ischemic area, the distribution of blood flow in
the brain has to be adjusted functionally through the circle of Willis.
• The RI of blood flow in the ICA proximal to the CCF decreased.
• The velocity of blood flow in the ICA may increase apparently if the
fistula is large.
• Blood velocity of the vascular branches distal to the fistula, such as
the MCA, ACA, and OA, decreased but increased in those of the
healthy side as compensation.
• The RI of blood flow in the ACA in the healthy side reduced through
the function of the anterior communication artery
• As the posterior vascular circle of the brain, the vertebrobasilar
artery system showed a reduced RI attributable to the adjustment of
blood flow.
• In a large fistula, the velocity of blood flow in the PCA and BA in the
affected side may obviously increase.
Ultrasonographic for Follow-up
Study

• Changes in the SOV were the most characteristic,
appearing as a dilated lumen, reversed blood flow, and
arterialized spectra with high velocity and a low RI.
However, sometimes these characteristics may not be
as obvious.
• Because different types of CCFs have different
hemodynamic alteration and different draining routes,
clinical features such as pulsating exophthalmos may not
come out.
• In this situation, careless detection is prone to miss the
diagnosis
Study

Study
• Color Doppler ultrasonography is more convenient than
digital subtraction angiography for the long-term follow-
up study of a CCF.
• A complete embolization means that no abnormal color
flash exits the affected site; blood flow parameters of
relevant vessels return to normal; and abnormal changes
in the SOV disappear.
• Part embolization means that the abnormal color flash
shrinks, and the velocity of blood flow decreases while
disordered spectra can be observed.

Study
• CDUS possesses the following features in diagnosis of
CCFs.
– It is inexpensive, noninvasive, and easily repeated.
– The size and extent of the CCF focus can be
observed directly.
– Combined with the traumatic history, clinical
characteristics, hemodynamic alteration of relevant
vessels, and changes in the SOV specific to the CCF,
CDUS can confirm the diagnosis of a CCF accurately.
– In addition, CDUS is of great value in accessing the
therapeutic effect of CCFs.

Cerebral Veins and Sinuses
• The superficial cerebral veins cannot be imaged with ultrasound
methods.
• However, usually, three of the surface veins of the brain appear
dominant and may serve as important collaterals.
• Their recruitment can be assumed by indirect ultrasound findings.
• The superficial middle cerebral vein connects to the sphenoparietal
(SPaS) or cavernous sinus (60%), or to the pterygoid plexus (14%).
• The superior anastomotic (Trolard’s) vein drains towards the
superior sagittal sinus (SSS) and the inferior anastomotic (Labbé’s)
vein joins the transverse sinus (TS).
• Only major tributaries of paired cavernous sinuses, the SPaS and
the superior petrosal sinus (SPS), can be depicted by ultrasound.

• The deep middle cerebral vein (dMCV) is formed by insular veins,
follows a medial course in close proximity to the middle cerebral
artery (MCA) within the lateral sulcus, and empties into the basal
vein (BV) (of Rosenthal).
• Together with the internal cerebral veins (ICV) the BV usually joins
the great cerebral vein (GCV) (vein of Galen).
• The GCV originates above the pineal gland, describes a convex
arch around the splenium of the corpus callosum, and joins the
straight sinus (SRS).
• In order to examine intracranial veins and sinuses a low-flow
sensitive color program with a low wall filter setting has to be used
and the pulse repetition frequency needs to be reduced.

Venous ultrasound anatomy and examination technique with
transcranial color-coded duplex sonography (TCCS).
a Ultrasound anatomy,
b–f examination technique, and typical TCCS appearance
and characteristic venous Doppler spectrum
•The blue plane represents the examination plane, light
blue the examination plane of previous step.
•The red arrows indicate the movement of the
transducer and the resultant change of the insonation
plane.
•The vessels marked in red are the ones that can be
examined in the given examination plane.
dMCV = Deep middle cerebral vein;
ICV = internal cerebral vein;
SSS = superior sagittal sinus;
GCV = great cerebral vein (of Galen);
SRS = straight sinus;
SPS = superior petrosal sinus;
BV = basal vein (of Rosenthal);
SPaS = sphenoparietal sinus;
MCA = middle cerebral artery;
ACA = anterior cerebral artery;
TS = transverse sinus;
ipsil.= ipsilateral;
contral.= contralateral.

The table summarizes studies of
cohorts of more than 40 subjects. TCCS
Transcranial color-coded duplex
sonography;
TCD = transcranial Doppler
sonography;
TBW = temporal bone window;
OBW = occipital bone window;
FBW = frontal bone window;
TFBW = transforaminal bone window;
N = cohort size; ø
Age = average age in years;
dMCV = deep middle cerebral vein;
BV = basal vein (of Rosenthal);
GCV = great cerebral vein (of Galen);
SRS = straight sinus;
TS = transverse sinus;
SSS = superior sagittal sinus;
IPS = inferior petrosal sinus;
ICV = internal cerebral vein;
SPaS = sphenoparietal sinus;
SPS = superior petrosal sinus;
FV = flow velocity in cm/s;
DR = detection rate in percentage.
Flow velocities are given as peak
systolic/end-diastolic velocities,
otherwise as mean velocities. Data in
brackets indicate the range, values
given as plus/minus show the standard
deviation.
When a range is given for detection
rates, this indicates the variation in
different age groups.

Temporal Arteritis
• With improving ultrasound technology it is possible to reach both
axial and lateral resolutions of about 0.1mm and to easily delineate
the temporal arteries.
• Three findings are important for the diagnosis of temporal arteritis:
– Dark (hypoechoic), circumferential wall thickening (‘halo’) around the
lumen of an inflamed temporal artery, which represents vessel wall
edema.
– Stenoses are present if blood-flow velocity is more than twice the rate
recorded in the area of stenosis compared with the area before the
stenosis
– perhaps with wave forms demonstrating turbulence and reduced velocity
behind the area of stenosis.
– Acute occlusions in which the ultrasound image is similar to that of
acute embolism in other vessels, showing hypoechoic material in the
former artery lumen with absence of color signals.

Temporal Arteritis
Transverse and longitudinal ultrasound images of right temporal artery
show a hypoechoic halo in the artery wall (halo sign).

Temporal Arteritis
Transverse and longitudinal ultrasound images of left temporal artery
also show the halo sign. Note also stenosis of the arterial
lumen.

Temporal Arteritis
Flow velocity in left temporal artery is increased over 2 m/s due
to stenosis. Bilateral temporal arteritis was diagnosed.

Temporal Arteritis
Duplex ultrasound of the temporal arteries:
a longitudinal view of a normal frontal ramus;
b transverse view of a normal frontal ramus;
c transverse view of a
frontal ramus in active
temporal arteritis. The
arrow shows the
hypoechoic wall swelling
(‘halo’).
d Longitudinal view of a frontal ramus in active temporal arteritis. The sagittal diameter of the
hypoechoic wall swelling is 0.9mm (++). The colored area delineates increased blood flow
velocity, which is suspicious for a stenosis. e pw-Doppler ultrasound of a frontal ramus in
active temporal arteritis. Peak flow velocity is 86 cm/s in the stenosis (1+) and 19 cm/s behind
the stenosis (2+). f Inflammatory occlusion (↓) of a parietal ramus in active temporal arteritis.

Temporal Arteritis
• High-resolution B-mode ultrasound and Doppler
ultrasound have been used as diagnostic tools to
substitute the biopsy of the temporal artery.
• This halo sign has above 80–90 % specificity, but the
sensitivity is below 70 %, not very far from those of the
temporal biopsy.
• The presence of a halo sign is practically diagnostic in
the presence of compatible symptoms, but its absence
does not rule out vasculitis.
• Ultrasound findings disappear in about 2 weeks after the
onset of treatment with corticosteroids.

Deep Venous Thrombosis
• Compression ultrasonography is the diagnostic
procedure of choice for the assessment of patients with
suspected DVT.
• It has been shown to be highly sensitive and specific for
the diagnosis of DVT, particularly in the lower extremities
in symptomatic patients.
• Sensitivity and specificity are near 100 % in the
femoropopliteal segment.
• Sensitivity decreases in isolated calf thrombi and in
asymptomatic patients.

A venous US scan of the right leg was performed. Transverse
ultrasound uncompressed (a) and compressed (b) images show a
non-compressible superficial femoral vein (arrowhead ).

Longitudinal ultrasound image
shows the distended vein
(posterior to the artery) with
intraluminal clot ( arrows ).
Color Doppler longitudinal image shows normal flow in
the superficial femoral artery and no flow in the
superficial femoral vein.

Functional Transcranial Doppler
Sonography
• Since the first demonstration of noninvasive Doppler ultrasound
pericranial recordings of the cerebral blood flow velocities (CBFV) in
the basal cerebral arteries, functional transcranial Doppler
sonography (fTCD) has been established as a complementary
perfusion-sensitive neuroimaging tool.
• Like functional magnetic resonance imaging (fMRI) and positron
emission tomography, fTCD is based on the close linkage between
local neural activity and regional cerebral blood flow (rCBF) changes
(neurovascular coupling)
• Recent developments in fTCD have shown that the technique can
assess language function reliably in adults and children.
• Functional TCD thus has the potential to assess hemispheric
differences in activation for a wide range of brain functions in normal
subjects and patients.

Sonography
Measurement of the CBFV in the
basal arteries through the
transtemporal cranial window:
In most fTCD studies the M1-
segment of the MCA is insonated at
a depth of 40–60 mm.
The two probe positions illustrate
the dependency of the recorded
flow velocity as a cosine function of
the insonation angle.
In case of the lower probe position,
this results in a negative deviation
of 15% of the absolute velocity in
the insonated vessel segment.
ACA, MCA, and PCA = Anterior,
middle, and posterior cerebral
arteries.

Sonography
Prototype fTCD setup for language lateralization: blood flow velocities in the
basal arteries (here the middle cerebral arteries; MCAs) are bilaterally monitored by a
commercially available TCD device. Stimulus presentation is accomplished by computer
display. CBFV envelope curve are stored with the simultaneously recorded marker signal for
segmentation of event-related signal intervals. Offline analysis is performed by AVERAGE, a
program for automated blood flow data analysis

Sonography
Averaged event-related CBFV modulations resulting from 30 repetitions of a language lateralization
paradigm (PDLT; picture description language task) in an 8-year-old child.
The left y-axis indicates the relative perfusion increases between the left and right middle cerebral arteries
(MCAs) during resting period (baseline) and task performance (PDLT) as the difference between the
averaged relative perfusion changes in the left and right MCA (right y-axis in blue).
Positive values by calculation indicate left hemispheric dominance and vice versa.
An fTCD language lateralization index (LI; red column; 7.8%) with confidence bands (indicated in green) is
calculated by the maximum increase during a defined period of interest

Pain: Non-invasive functional
neurosurgery using ultrasound
• Researchers in Switzerland (2009) have shown that chronic pain
can be alleviated through thermal ablation of thalamic tissue by
high-intensity focused ultrasound.
• Mri-guided focused ultrasound (mrgFus), is used to treating brain
tissues with ultrasound.
• Martin and colleagues used transcranial mri-guided highintensity
focused ultrasound (tcmrgHiFu) to perform lesions of the central
lateral thalamic nuclei in nine patients with chronic neuropathic pain
• These interventions relied on the capacity of tcmrgHiFu to heat
brain tissues to temperatures >53 °C to achieve thermal ablations
through multiple, repeated sonication events.
• All patients receiving the outpatient tcmrgHiFu procedure remained
awake and responsive during the entire neurosurgical intervention,
which resulted in thalamotomies ≈4 mm in diameter.

Non-invasive functional
neurosurgery using ultrasound
Potential applications of ultrasonic neuromodulation for the noninvasive treatment of
brain disorders.
Through both thermal and non-thermal (mechanical) mechanisms, ultrasound has been
shown to exert numerous bioeffects on brain tissues that could provide a basis for non-
invasive therapies for neurological and psychiatric disorders.

• The integration of external beam radiotherapy (EBRT) and
highintensity focused ultrasound (HIFU), with a case history taken
from their collection of bone metastasis treatments using magnetic
resonance-guided high-intensity focused ultrasound (MRgFUS)
• HIFU is only employed for palliative treatment of bone metastases
(pain reduction), when the disease has become systemic.
• In several cases, complete success (pain palliation and total
metastasis ablation) has been obtained.

Measurement of optic nerve
sheath diameter by ultrasound: a
means of detecting acute raised
intracranial pressure in hydrocephalus
• The evaluation of the optic nerve
sheath diameter is a simple non-
invasive procedure, which is a
potentially useful tool in the
assessment and monitoring of
children with hydrocephalus
suspected of having raised
intracranial pressure.
• A non-invasive method of
determining whether ICP is raised by
using ocular ultrasound to detect
dilation of the optic nerve sheath 3
mm behind the eye has recently
been described

Delayed reversal of ONS distension- initial
scan. ONUS performed in a 66-year-old
patient who became acutely unresponsive
two days after removal of an EVD. Scan
performed prior to placement of new EVD.
The ocular globe is the hypoechoic
structure in the upper part of the images
and the ONS the linear hypoechoic
structure behind the globe.
Caliper A identifies a point 3 mm behind
the retina while Caliper B measures the
ONSD.
ONSD is 0.55 cm, suggestive of raised
ICP. Opening pressure was >50 mmHg.

Delayed reversal of ONS distension- early
post-treatment scan. ONUS performed
twenty minutes after first measurement.
The ocular globe is the hypoechoic structure
in the upper part of the images and the ONS
the linear hypoechoic structure behind the
globe.
Caliper A identifies a point 3 mm behind the
retina while Caliper B measures the ONSD.
ONSD is 0.53 cm, suggestive of continued
intracranial hypertension.
Simultaneously recorded ICP from EVD was
only 10 mmHg.

Conclusions
The specificity and PPV of ONSD measurement for the detection of raised
ICP are substantially decreased in the presence of significant acute ICP
fluctuation.
ONSD measured on the initial brain CT scan is independently associated
with ICU mortality rate (when ≥ 7.3 mm) in severe TBI patients.
The sensitivity and specificity of bedside sonographic measurement of optic
nerve sheath diameter is inadequate to aid medical decision making in
children with suspected increased intracranial pressure.
Key messages
• Optic nerve sheath distension on bedside ultrasound imaging is less
predictive of intracranial hypertension when intracranial pressure is acutely
fluctuating between high and normal.
• Delayed reversal of optic nerve sheath distension is one possible
explanation for this decrease in positive predictive value.

Ultrasound Assessment of Intracranial Dural Arteriovenous Fistulas (DAVF

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