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189Magnetic Resonance Angiography (MRA)
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
A
C
B
D
Fig. A6.8 Various veno graphy t echni ques. (A) MSCT venography, semitransparent 3D rendering, superoposterior view. Extended superior
sinus venous thrombosis is delineated by the tram-track sign (arrows). (B) Contrast-enhanced 3D GE venography (lateral MIP), providing
vessel resolution, that closely approximates that of CT venography, superior to 2D TOF-MRV (lateral MIP) in the same patient (C). (D) MSCT
venography, semitransparent 3D rendering. Note a cortical venous thrombosis with interruption of a cortical vein (arrow).
Contrast-enhanced (ce) 3D MRA
namic imaging techniques are feasible. Special focus on
k-space data collection can help increasing the signalThe ce-MRA technique was developed because of the
methodological limitations of TOF-MRA, caused by saturation eff ects, spin dephasing, restricted fi eld of view,
and relatively long scan times. This technique is the basic method for assessing extracranial brain-supplying
arteries. It requires the use of intravenous gadolinium
for vessel visualization, as the signal is based on the intravascular T1-shortening eff ect of gadolinium. A short
TR is chosen, as well as a short scan time, to allow for
breath-hold imaging. These prerequisites are met when
a FLASH technique is used, spoiling residual transverse
magnetization subsequent to signal read-out. To optimize signal intensity and avoid venous contamination,
proper bolus timing is essential, either by measuring
circulation times beforehand or by applying a fl uoro-
scopic bolus triggering technique (automated or operator-driven). As compared with TOF and PC-MRA,
image artifacts are reduced, in-plane (longitudinal)
vessel imaging is possible (large fi eld of view), and dy-
to-noise ratio, as the contrast information is located
in the center of the k-space; this information should
be read out early when maximum intravascular bolus
concentration is given (Klingebiel et al 2007, Zhang et
al 2007). Willinek and colleagues (2005) encountered
comparable sensitivity and specifi city of ce 3D MRA
and DSA for assessment of steno-occlusive diseases of
the supra-aortic arteries including the cerebral arterial
circle (circle of Willis). A diagnostic image quality com-
parable with those obtained by using CTA and DSA for
detection of arterial stenoses has been established for
supra-aortic arteries when using ce-MR angiography at
3.0 T (Nael et al 2007).
The capacity of ce-MRA for rapid 3D data acquisition
has been exploited for the establishment of time- resolved
(4D) MRA, most commonly using time intervals of
1–2 seconds per 3D volume, but also allowing for subsecond scanning rates. Variants of 4D MRA are known as
TRICKS (time- resolved imaging of contrast kinetics), TREAT
190 6 Angiographic Techniques in Neuroradiology
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
A
B
Fig. A6.9 In-plane saturation artifact in TOF-MRA. Although background suppression and signal-to-noise ratio with TOF-MRA (A) are
superior to contrast-enhanced 3D FLASH MRA (B), the relevant fi nd-
ing of a dissecting sub-basal aneurysm (arrow) of the right ICA after
dissection is masked by in-plane saturation eff ects in TOF-MRA.
(time- resolved echo-shared angiography technique), or
TWIST (time-resolved angiography with stochastic trajectories) (Hadizadeh et al 2014). Generally speaking, these
variants diff er with regard to data acquisition of the k-space.
Although to some extent these techniques trade off image
quality for hemodynamic assessment, it has been shown
that in various settings, such as in detecting intracranial and
spinal dural arteriovenous fi stulas, they can compete with
invasive radiologic techniques (Nishimura et al 2010).
Advantages and Disadvantages
The major craniocervical applications of 3D TOF-MRA
as compared with 3D FLASH MRA are determined by
their technical specifi cations. In TOF-MRA, commonly
used for intracranial MRA, an imaging plane perpendicular to the major fl ow direction is essential (see above),
thus rendering this technique inappropriate for imaging longer vessel segments (e.g., extracranial vessels of
the neck). In contrast, the large fi eld of view and rapid
data acquisition with ce-3D FLASH MRA not only make
it possible to cover the craniocervical vasculature from
the aortic arch to the vertex but also allow dynamic
(time-resolved) imaging.
TOF- and PC-MRA have the advantage that the use
of contrast medium can be avoided, which is of special
benefi t for pregnant or breast-feeding patients and pa-
tients with severe kidney disease. Nephrogenic systemic
fi brosis (NSF) related to gadolinium use was fi rst de-
scribed in 2006 (Grobner 2006) and prompted the implementation of guidelines for the use of MR contrast media
(Thomsen 2009), with a subsequent signifi cant decrease
in NSF incidence (Daftari Besheli et al 2014).
An inherent advantage of MRA, as compared with the
competing angiographic techniques, is that it does not involve exposure to ionizing radiation, another important
issue especially in pregnancy and early childhood.
Absolute contraindications to MRI have been defi ned
as electronically, magnetically, and mechanically activated
implants (such as defi brillators and cardiac pacemakers)
as well as ferromagnetic foreign bodies if not encapsulated subcutaneously by fi brous tissue. Relative contraindi-
cations are cochlear implants and noncardiac pacemakers
(e.g., nerve stimulators or insulin pumps): Recently a new
generation of cardiac pacemakers has been introduced
and proven to be “conditionally safe,” meaning that MR
scanning is considered safe if certain precautions (e.g., a
maximum of 1.5 T) are established (Gimbel et al 2013).
Lead wires pose a risk because of the potential of current
induction in a powerful magnetic fi eld. Most prosthetic
heart valves are exposed to a higher stress by cardiac hemodynamics than that exerted by the MR scanner. Osteosynthetic material is usually anchored, but might cause
induction heating. In addition, image quality may be severely degraded. The majority of other metallic implants,
such as modern surgical clips, do not represent a hazard.
Nevertheless, in each individual case the patient has to be
thoroughly investigated with respect to these contraindications and guidelines (Chow and Nazarian 2014).
Vas cular sten ts, comm only encou ntered nowa days in
elderly patients, have been shown to suff er from defl ec-
tion forces that may exceed safety limits in high fi eld scan-
ners in an experimental setting (Shellock 2002). However,
in patients who are scheduled for MRI several weeks after
stent angioplasty, endothelial overgrowth of the implant
device makes stent displacement very unlikely. Tattoos
and permanent make-up, even without iron constituents,
may cause skin burns (Franiel et al 2006) and the patient
has to be informed accordingly.
Disadvantages of TOF-MRA are limited spatial resolution and the exaggeration of the degree of stenosis as the
fl ow within the vessel and not the vessel diameter itself de-
fi nes the signal. Also, TOF-MRA is inappropriate for diff er-
entiating a high-grade stenosis or near-occlusion from an
occlusion. Another limitation of 3D TOF-MRA with regard
to aneurysm assessment is that turbulent intra-aneurysm
fl ow may obscure the pathology or result in underestimation of the volume and neck size of the aneurysm (see Fig.
A6.9). Nevertheless, especially younger patients with a
family history of subarachnoid hemorrhage (SAH) caused
by aneurysm are commonly referred to MRA for assessment. Limited suitability of 3D TOF-MRA for assessing
smaller aneurysms (<3 mm) has also been reported (Mine
et al 2015). Good sensitivity for detecting more clinically relevant aneurysms (>3 mm diameter) was reported,
although 3-T TOF-MRA performed signifi cantly less well
than DSA in terms of aneurysm characterization (neck size,
bleb detection, branching arteries).
TOF-MRA is, however, usually the preferred method
for analyzing intracranial vessels. The main reason is the
191Computed Tomographic Angiography (CTA)
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
large fi eld of view (FOV) as well as the coronal slab plane
in ce-MRA which is chosen for maximum coverage along
the longitudinal course of cervical vessels, thus limiting
imaging of the intracranial vasculature. Also, the large
FOV decreases spatial resolution and the coronal slab restricts coverage of vessels in the sagittal plane (e.g., the
parietooccipital arteries).
In the acute SAH setting, limited feasibility for MRA
in patient assessment has been reported (Pierot et al
2013), mostly due to lack of patient compliance. In a
recent meta-analysis both TOF-MRA and ce-MRA have
been shown to be highly accurate for the detection of any
r e c a n a l i z a t i o n i n i n t r a c r a n i a l a n e u r y s m s t r e a t e d w i t h
endovascular coil occlusion (van Amerongen et al 2014).
2D-TOF is a technique that has been widely used for
ruling out dural sinus venous thrombosis, but suff ers
from inherent image artifacts that may simulate the pathology, and must be reliably ruled out (Ayanzen et al
2000). For these reasons, 2D-TOF venography should be
replaced by ce-MRV (Klingebiel et al 2007).
Cervicocranial MRA, together with cross-sectional
MRI is a proven modality for detecting intramural hematoma when ICA and/or vertebral artery (VA) dissection is presumed; due to its technique, including image
subtraction, vascular pathology close to the skull is easily
depicted without interference by bony structures, unlike
unsubtracted CTA.
PC-MRA is still in limited use for specifi c indications
such as vessel scout scans, fl ow quantifi cation, and thick
slab imaging of specifi c vessels (superior sagittal sinus),
although providing information about fl ow velocity as
well as fl ow direction. Longer scan times, inferior spatial
resolution, and increased operator demands when
c o m p a r e d w i t h 3 D T O F - M R A a l l r e p r e s e n t d i s a d v a n t a g e s
for the daily clinical use of PC-MRA.
Computed Tomographic
Angiography (CTA)
Historical Development
CT uses X-rays to generate cross-sectional images derived
from serial and digitally postprocessed images taken
around a single axis of rotation. The term is derived from
the Greek words tomos (slice) and graphien (to write).
X-rays pass through the body, and the diff erence be-
tween emitted signal intensity and intensity measured
by the detector elucidates the attenuation characteristics within a body plane of interest. To reconstruct
the image, an inversion of the Radon transformation is
used. Godfrey Hounsfi eld was awarded the Nobel Prize
for his work on several prototype CT scanners (Ambrose
and Hounsfi eld 1973) together with Allan M. Cormack, a
physicist, in 1979. The fi rst CT studies in humans were
performed in 1971.
Subsequent technical improvements have led to several generations of scanners, with the introduction of multislice CT (MSCT) in 1999 (Hu 1999) as one of the milestones
in the history of the technique. Although CT applications
for assessment of intracranial vascular pathology were
d e s c r i b e d a s e a r l y a s t h e 1 9 7 0 s ( M i c h e l s e t a l 1 9 7 7 ) , i t w a s
A
B
Fig. A6.10 Dual-source CT venogram without (A) and with
(B) bone subtraction, lateral projection.
not until the introduction of spiral (also called helical) CT
in 1990 by W. Kalendar (Kalendar and Polacin 1991), that
this technique was considered as an alternative to conventional angiography in selected cases (Napel et al 1992).
The multislice technique has been continuously refi ned
from scanners providing 4 detector rows with a minimum
collimation of 0.5 mm (resulting in high- resolution z-axis
coverage of 2 mm per rotation) to 256 and 320 detector
rows (Klingebiel et al 2002, 2008, 2009). The 320-row
scanner type (Aquilion ONE, Toshiba Medical Systems)
provides high-resolution z-axis coverage of 160 mm,
a l l o w i n g f o r w h o l e - b r a i n i m a g i n g b y j u s t o n e g a n t r y r o tation. Clinical implications of extensive brain coverage
by these modern CT scanners include time-resolved vessel and perfusion imaging (4D imaging), wherein the CT
data are exploited for dynamic CTA as well as for highresolution whole-brain perfusion (Klingebiel et al 2009).
The introduction of so-called dual-source (or
d u a l - e n e r g y ) C T s c a n n e r s ( D S C T ) i n 2 0 0 6 , p r i m a r i l y f o cusing on high temporal resolution for cardiac imaging
(Flohr et al 2006), also had an impact on supra-aortic
vessel assessment (Fig. A6.10). DSCT uses two X-ray
tubes with diff erent voltages and is capable of sepa-
rating iodine from bone or metallic artifacts, based on
their diff erent absorption spectra. Accordingly, it al-
lows for removal of the skull and hard plaques, and it
has been proven to correlate well (r = 0.95) with DSA
in the assessment of calcifi ed carotid stenosis (Uotani
et al 2009). DSCT also appears to be a powerful tool in
artifact reduction (e.g., metallic implants) as well as in
192 6 Angiographic Techniques in Neuroradiology
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
d i ff erentiating intracranial hemorrhage from contrast
extravasation (Phan et al 2012).
Technical Aspects
Until the introduction of MSCT into clinical imaging,
comprehensive cervicocranial vascular imaging by spiral
CT was limited by the heat-load capacity of the X-ray tube
as well as by radiation exposure issues. The introduction of
multislice CT not only meant multiple row scanning (4, 16,
64, up to 320 rows) instead of just one row, but was also associated with an increased rotational speed (0.5 s/rotation)
and improved heat-load capacity. Taken together these
qualities permitted comprehensive high-resolution cervicocranial vessel assessment from the aortic arch up to the
superior sagittal sinus ( Klingebiel et al 2002). Almost simultaneously, various workstations for postprocessing of the
high-image-load delivered by MSCT were introduced into
the market. These workstations signifi cantly facilitated 2D
as well as 3D rendering of up to ~800 slices (cervicocranial
CTA), enabling meaningful condensation of abundant image information into just a handful of color-coded photorealistic image reconstructions. With the introduction of
4D cerebrovascular imaging by 256–320-row scanners,
comprehensive stroke imaging protocols (3D cervical CTA,
4D cranial CTA and perfusion imaging) resulted in >8,000
cross-sectional images (Siebert et al 2009). Only dedicated
workstations connected to the scanner via local networks
are able to postprocess these volumes of data and new concepts are required as to how, and which, elements of this
abundant study data are transferred to a picture archiving
and communication system (PACS).
In terms of radiation exposure, overbeaming and
overscanning became important keywords in MSCT.
Overbeaming means extending the cone beam beyond
the outer borders of activated detectors to avoid critically low doses with respect to image quality in the outskirts of the detector row. In consequence, the border
zone areas were redundantly exposed, causing increased
radiation exposure to the patient (Tzedakis et al 2005).
Overbeaming is signifi cantly reduced in 64-slice scanner
as compared with the 4-slice-scanner generation. This
rendered MSCT scanners with a higher number of detector rows more suitable for cervicocranial CTA than
the basic 4-slice scanners. Overscanning means that to
be able to reconstruct the images, the multislice scanner
needs an extra rotation at the start and at the end of the
spiral scan. For scan lengths of more than 30–35 cm, as
in cervicocranial CTA, this eff ect is negligible.
ED fi gures for cervicocranial CTA have been report-
ed to range between 4.7 and 5.6 mSv (Cohnen et al
2006, Diekmann et al 2010, Mnyusiwalla et al 2009).
Recent CT techniques, using iterative reconstruction,
low- voltage, automatic exposure control, and/or high
pitch protocols, have led to dose reductions of >50%. ED
fi gures as low as 0.2–0.28 mSv have been demonstrated
in cerebral CTA using 80 kVp (G.Z. Chen et al 2015, Sabarudin et al 2014), as opposed to 1.9 mSv in the study
by Cohnen et al (2006).
After ensuring adequate intravenous access by using
an 18–20-gauge venous cannula, the patient is connected
to a power injector. If possible, the side of minor clinical
interest should be chosen for venous access, as the high injection pressure may push contrast medium upward into
the cervical vessels, obscuring the contours of the proximal
common carotid artery as well as that of the internal carotid artery, especially in patients with venous valvular insuffi ciency. Usually, the scan is started in one of two ways:
(1) A low-dose, dynamic scan is performed at the level of
the internal carotid artery and the spiral scan is then initiated as soon as the operator detects the arrival of contrast
medium at the chosen level; or (2) a so-called “sure start”
protocol is used. This protocol usually means that a region
of interest is defi ned in the aortic arch or descending aorta,
where a predetermined density level automatically triggers initiation of the spiral scan. Correct venous line placement is still important, even though injection velocities up
to 20 mL/s, as required in the initial CTP protocols (Koenig
et al 1998) are no longer necessary, due to the widespread
use of deconvolution algorithms in CT perfusion imaging
(Hoeff ner et al 2004). Routinely, a total of 50–80 mL of
contrast medium (nonionic iodinated medium, containing
370 mg/mL iodine) is administered over 20 s, chased by a
bolus of 20–30 mL isotonic saline.
Advantages and Disadvantages
Although technical progress has led to a signifi cant de-
crease in radiation exposure in all CTA procedures, the
indication for CTA has to be carefully weighed against alternative imaging techniques for each individual patient,
considering especially whether the expected diagnostic
information might be obtained by a procedure without radiation exposure. Alternate techniques such as ultrasound
and MR as well as invasive catheter angiography are available in most major hospitals during normal working hours.
However, the majority of stroke patients are critically ill
patients beyond reproductive age in whom time-effi cient,
operator-independent, comprehensive assessment of the
craniocervical vasculature is required 24/7, with as few
limitations to vital parameter monitoring as possible. No
other modality combines these qualities, making MSCT the
undisputed fi rst-line imaging modality in stroke patients
(Donahue and Wintermark 2015).
Given technically correct performance of CTA, high
intravascular contrast is achieved, ensuring 2D and 3D
reconstructions of unprecedented image quality. When
time effi ciency is the issue in stroke imaging, the strik-
ingly short data acquisition fi gures for comprehensive
craniocervical CTA are often mentioned; but the clinical
imaging time also includes image data reconstruction, data
transfer (local workstation and/or PACS), as well as postprocessing before the fi nal radiologic study report can be
delivered to the referring neurologist. Thus, time effi ciency
in the assessment of stroke patients is not just a matter of
the number of detector rows but of appropriate internal
network structures and postprocessing facilities.
Contraindications to CTA are the same as those in
any iodine-using X-ray study and include impaired renal
function, hyperthyroidism, and iodine allergy. Yet, for vital diagnostic purposes, these contraindications might
be overcome by either kidney protective measures such
as intravenous fl uids, acetylcysteine injection and/or
dialysis, thyroid-blocking drugs, or pretreatment with
193Computed Tomographic Angiography (CTA)
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
antihistaminic drugs as well as intravenous cortisone.
Moreover, it has been shown that functional stroke CT
(CTA, CT perfusion) did not increase the incidence of contrast-induced nephropathy (Adalsteinsson et al 2003).
Spatial resolution and vessel-to-background ratio are
the decisive factors for delineating small vascular details,
e.g., very fi ne vessels in cerebral vasculitis (Fig. A6.11).
In a comparative study of DSA and MSCTA the smallest
arterial size reliably detected with MSCTA was 0.7 mm,
versus 0.4 mm for DSA (Villablanca et al 2007). In a
meta-analysis of 50 studies comparing CTA and DSA for
aneurysm assessment in SAH patients (Westerlaan et al
2011), the pooled sensitivity and specifi city fi gures for
CTA amounted to 98% and 100% (even though most studies used 4-row scanners). Thus, in most centers SAH patients are primarily assessed by CTA (especially outside
normal working hours), followed by DSA in negative CTA
studies or if necessary for treatment planning. This strategy was also shown to be most cost-eff ective (Sailer et al
2014), another important issue in times of limited healthcare resources (Fig. A6.12).
Although 4D-CTA carries the highest radiation exposure, it has also been shown to deliver abundant clinical
relevant information, not only in regard to intracranial
vascular malformations, but especially in ischemic stroke:
4D-CTA better defi ned thrombus burden and collateral
vessel status (Kortman et al 2015, Siebert et al 2012).
In terms of intracerebral hemorrhage (e.g., hemorrhagic stroke), the “spot sign” (Fig. A6.13) as detected in
CTA has been shown to be a reliable imaging biomarker
for hematoma expansion with prognostic and therapeu-
CBA
Fig. A6.12 DSA (A) and MSCTA (B) comparison for aneurysm
assessment. Atypical presumptive mycotic aneurysm at the
right-sided T-junction level (arrows). Both techniques provide
equivalent diagnostic information.
Fig. A6.11 Cerebral vasculitis,
frontal projections. DSA, left ICA
injection (A), shows multiple vessel irregularities (arrows), some
of which are more pronounced
on MSCTA images (B) or even
3D TOF-MRA (C). MCA stenosis
seems exaggerated by TOF-MRA
(C), indicating increased stenosis
sensitivity but ineffi cient steno-
sis grading. Moreover, resolution
of detail is clearly inferior to DSA
and CTA.
BA
tic implications (Du et al 2014). A higher sensitivity for
spot sign detection was described when using CT perfusion (Koculym et al 2013).
Both CT and MRI are able to comprehensively assess
the craniocervical vasculature and provide all information necessary for decision-making and therapy planning
in stroke patients. Yet, scanner availability, compliance
and safety issues, as well as time- and cost-eff ectiveness
all speak in favor of CT-based evaluation of acute stroke
patients (Hoeff ner et al 2004, Tong et al 2015).
BCA
Fig. A6.13 CTA (A) and plain
CT on admission (B), with only
CTA showing a “dot sign” (arrow) within the parenchymal
hematoma. (C) Follow-up CT
reveals progress of intracranial hemorrhage (ICH) into the
left lateral ventricle.
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
Part B Case Histories
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
Case 1 Right Extracranial Internal Carotid
Artery Stenosis . . . . . . . . . . . . . . . . . . . . . . . . . 197
Case 2 Free-fl oating Thrombus of the
Left Internal Carotid Artery . . . . . . . . . . . . . . . 205
Case 3 Left Common Carotid Artery Occlusion . . . . . 210
Case 4 Left Temporal Arteriovenous Malformation . . 215
Case 5 Left M1 Middle Cerebral Artery Stenosis . . . . . 222
Case 6 Left P2 Posterior Cerebral Artery Stenosis . . . . . 230
Case 7 Cerebral Circulatory Arrest . . . . . . . . . . . . . . . 235
Case 8 Basilar Artery Occlusion in Bilateral
Intracranial V4 Vertebral Artery Stenosis . . . . . 244
Case 9 Moyamoya Disease . . . . . . . . . . . . . . . . . . . . . . 251
Case 10 Thrombolysis of M1 Middle Cerebral
Artery Occlusion . . . . . . . . . . . . . . . . . . . . . . . . 260
Case 11 Secondary Occlusion in Left-sided
Extracranial Internal Carotid
Artery Dissection . . . . . . . . . . . . . . . . . . . . . . 269
Case 12 Extracranial Bilateral Internal Carotid
Artery and Right Vertebral Artery
Occlusion, and Left Vertebral
Artery Stenosis . . . . . . . . . . . . . . . . . . . . . . . . . 281
Case 13 Right Internal Carotid Artery Stenosis
in Fibromuscular Dysplasia and
Granulomatosis with Polyangiitis
(formerly Wegener’s Granulomatosis) . . . . . . 288
Case 14 Isolated Left Carotid Siphon Stenosis . . . . . . . 295
Case 15 Near-occlusion of the Right and
High-grade Stenosis of the Left
Extracranial Internal Carotid Artery . . . . . . . . 300
Case 16 Giant Cell Arteritis with Bilateral
Intracranial V4 Vertebral Artery Stenosis . . . . . 313
Case 17 Ascending Left Middle Cerebral Artery
Occlusion in an HIV-positive Patient . . . . . . . 320
Case 18 Traumatic Bilateral Internal Carotid and
Vertebral Artery Dissection with
Right-sided Embolic Middle Cerebral
Artery Occlusion . . . . . . . . . . . . . . . . . . . . . . . 327
Case 19 Bilateral Extracranial Vertebral Artery
Dissection with Distal Occlusion of the
Right Vertebral Artery . . . . . . . . . . . . . . . . . . . 339
Case 20 Right Internal Carotid Artery
Dissection with Fast Recanalization . . . . . . . . 345
Case 21 Mid-basilar Artery Occlusion Due to
Intracranial Dissection . . . . . . . . . . . . . . . . . . . 354
Case 22 Right Mid-part M1 Middle Cerebral
Artery Occlusion with Prominent
Early Temporal Branch and Patent
Foramen Ovale . . . . . . . . . . . . . . . . . . . . . . . . . 362
Case 23 Takayasu’s Arteritis with Right-sided
Subclavian Steal . . . . . . . . . . . . . . . . . . . . . . . . 372
Case 24 Dissection of the Right Extracranial
Internal Carotid Artery and Left M1
Middle Cerebral Artery . . . . . . . . . . . . . . . . . . . 380
Case 25 Progressive Right M1 Middle Cerebral
Artery Occlusion Treated with
Extracranial–Intracranial Bypass Surgery . . . . . 388
Case 26 Extracranial Left Vertebral Artery
Dissecting Aneurysm Following
Basilar Artery Stenting . . . . . . . . . . . . . . . . . . . 396
Case 27
Case 28 Subclavian Steal in Left Subclavian
Case 29 Cerebral Venous Thrombosis . . . . . . . . . . . . . 420
Case 30 Multilocular Extra- and Intracranial
Diff
use Cerebral Angiomatosis . . . . . . . . . . . . 402
Artery and Right Internal Carotid
Artery Occlusion Leading to
Extracranial–Intracranial Bypass Surgery . . . . . 409
Stenoses and Occlusions . . . . . . . . . . . . . . . . . 427
Case 31 Dissection of the Right Internal Carotid
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
Artery C6 Segment . . . . . . . . . . . . . . . . . . . . . 440
Case 32 Right Temporal Hemorrhage in Pial
Arteriovenous Malformation . . . . . . . . . . . . . . 444
Case 33 Subarachnoid Hemorrhage after
Rupture of Left Supraophthalmic
Internal Carotid Artery Aneurysm . . . . . . . . . 448
Case 34 Right-sided Occipital Dural
Arteriovenous Fistula . . . . . . . . . . . . . . . . . . . . 460
Case 35 Left Distal Vertebral Artery Occlusion
and Right Vertebral Artery Hypoplasia
with Retrograde Basilar Artery Flow . . . . . . . . 470
Case 36 Postpartum Angiopathy (Reversible
Cerebral Vasoconstriction Syndrome) . . . . . . 476
Case 37 Left Anterior Choroidal Artery Infarction
in Left Supraophthalmic Internal Carotid
Artery Occlusion . . . . . . . . . . . . . . . . . . . . . . . 483
Case 38 Left-sided Amaurosis in Left Central
Retinal Artery Occlusion . . . . . . . . . . . . . . . . . 489
Case 39 Combined Chronic Right-sided
Extracranial Internal Carotid Artery
and Middle Cerebral Artery Occlusion . . . . . . 494
Case 40 Left Internal Carotid Artery Occlusion
and Ipsilateral Arteriovenous
Malformation in Infl ammatory
Bowel Disease . . . . . . . . . . . . . . . . . . . . . . . . . 500
Case 41 Right Internal Carotid Artery
as the Remaining Patent
Brain-supplying Artery . . . . . . . . . . . . . . . . . . . 509
Case 42 Left Internal Carotid Artery Aplasia as
an Incidental Diagnosis in Optic
Neuritis in Lupus Erythematosus . . . . . . . . . . . 517
Case 43 Sickle Cell Disease . . . . . . . . . . . . . . . . . . . . . . . 524
Case 44 Transient Global Amnesia with Left
Hippocampal Diff usion-weighted
Lesion and Asymptomatic Right
Middle Cerebral Artery Infarction
in High-grade Right M1 Stenosis . . . . . . . . . . 529
Case 45 Bilateral Proximal Vertebral Artery
Stenosis and Bilateral Middle
Cerebral Artery Aneurysm . . . . . . . . . . . . . . . 535
Case 1
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
Right Extracranial Internal Carotid Artery Stenosis
197
Clinical Presentation
A 70-year-old man presented to the emergency department with a sudden onset of numbness in his left arm.
He had a history of cigarette smoking (but had discontinued smoking 10 years before admission), arterial
hypertension, hyperlipoproteinemia, peripheral arterial
occlusive disease with femoral artery stenting several
years prior, and a 50% right-sided internal carotid artery (ICA) stenosis (NASCET criteria) diagnosed 1 year
prior. The patient was being treated with metoprolol,
simvastatin, and aspirin/dipyridamole. His neurologic
examination on admission was within normal limits and
thrombolysis was therefore not performed.
Initial Neuroradiologic Findings
Initial cranial CT showed no signs of ischemia (not shown).
Suspected Diagnosis
Right-hemispheric transient ischemic attack (TIA) in the
right middle cerebral artery (MCA) territory with transient sensory defi cits of the left arm.
Questions to Answer Using Ultrasound
Techniques
• Was it possible to confi rm the 50% (NASCET criteria)
right ICA stenosis?
• Was there any stenosis progression?
• If so, what was the grade of stenosis?
and comparable on both sides. There were no pathologic fi ndings in the left ICA (Fig. B1.1, Fig. B1.2, Fig. B1.3,
Fig. B1.4, Fig. B1.5; see also Video
B1.1).
Contrast-enhanced Harmonic Imaging
For advanced plaque analysis, contrast harmonic imaging was performed. 1 mL SonoVue was injected
intravenously into an antecubital vein and the pattern of contrast arrival was analyzed in a longitudinal
and cross-sectional imaging plane. Imaging revealed
a marked irregular surface within the stenosis with
several circumscribed ulcerations which were visible
as contrast traces extending into the plaque material
(Fig. B1.6 and Video
contrast-enhanced harmonic imaging see Chapter 1,
“Harmonic Imaging and Ultrasound Contrast Agents”
under “Imaging Modalities, Parameters, and Settings.”)
B1.2). (For further reading about
Transcranial Duplex Sonography
All detectable intracranial vessels including the ophthalmic arteries (OAs) revealed normal and symmetric fl ow
signals (not shown).
Conclusion
Nearly unchanged right ICA stenosis of 50–60% according
to the NASCET criteria (equaling 70–75% using ECST criteria) directly above the carotid bifurcation. The anechoic stenotic material was thought to be a smooth-surfaced
“soft plaque” and not a fresh, unorganized intravascular
thrombus.
Initial Neurosonologic Findings
Extracranial Duplex Sonography
B-mode sonography revealed generalized atherosclerotic
vessel wall thickening. The color-fl ow image of the right
ICA showed a lumen reduction distal to the carotid bifurcation caused by a large anechoic mass. Doppler spectrum
analysis in the narrowing revealed a raised fl ow velocity
of 225/99 cm/s with mild fl ow turbulence. Cross- sectional
insonation confi rmed a marked reduction of the vessel di-
ameter. Distal of the stenosis, the ICA Doppler spectrum
almost normalized (fl ow velocity: 109/33 cm/s). Blood
fl ow in the common carotid arteries (CCA) was regular
MRI
Diff usion-weighted MRI sequences showed an acute
right-sided partial territorial MCA infarct of assumed embolic origin within the region of the sensory cortex. No
old ischemic lesions were seen. MR angiography (MRA)
was not performed (Fig. B1.7).
CT Angiography
CT angiography (CTA) showed segmental ICA narrowing
with an ulcerated surface directly above the bifurcation.
The stenotic segment extended ~2 cm. The calculated
198 Case 1 Right Extracranial Internal Carotid Artery Stenosis
Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers
All rights reserved. Usage subject to terms and conditions of license.
ICA-L
Fig. B1.1 Extracranial duplex, longitudinal plane. Normal fl ow
signal in the left ICA (fl ow velocity 62/22 cm/s).
ICA-R
ICA-R
Fig. B1.2 Extracranial duplex, transversal plane, color-mode image.
Cross-sectional imaging of the right ICA with marked segmental
narrowing caused by nonechogenic material. Left: Diameter reduction assessment, bulb diameter 8.8 mm, residual perfused diameter
2.1 mm resulting in a calculated 76% local-grade stenosis. Right:
Identical image but area reduction assessment, bulb area 55 mm
residual perfused area 10 mm
ICA-R
2
, resulting in a calculated 82% stenosis.
2
,
Fig. B1.3 Extracranial duplex, longitudinal plane, color-mode
image. Right ICA with lumen narrowing over a distance of ~2 cm.
Note the intrastenotic color aliasing phenomenon, indicating locally raised fl ow velocity.
grade of stenosis was 73% according to ECST criteria (local
stenosis grade) and 54% according to the NASCET criteria
(Fig. B1.8, Fig. B1.9, Fig. B1.10). There were no pathologic
fi ndings in the distal ICA or the MCA on the aff ected side.
Fig. B1.4 Extracranial duplex, longitudinal plane. Doppler spectrum analysis of the right ICA with intrastenotic fl ow velocity of
225/99 cm/s.
terectomy (CEA). Intraoperatively, a soft plaque with
an irregular surface was removed (Fig. B1.11). There
was no evidence of a fresh thrombus. The operation
and postoperative clinical course were uneventful. No
further ischemic attacks occurred. Transthoracic echocardiography and a 24-hour electrocardiogram (ECG)
Clinical Course
were normal.
Considering the clinical event during best medical
treatment, the anechoic high-grade stenosis identi-
Final Diagnosis
fi ed using ultrasound, and the demarcation of a hyperacute ischemia in the corresponding distal intracranial
vascular territory, a symptomatic stenosis requiring
interventional treatment was diagnosed. Two days after admission, the patient underwent carotid endar-
Symptomatic right-sided high-grade ICA stenosis with a
lumen reduction of 70–80% (ECST criteria), corresponding to 50–60% (NASCET criteria) caused by anechoic
plaque.
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