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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5773_Библиотеки_им_академика_М_И_Перельмана.pdf
XITab le o f Cont ents
Clinical Course (1) .......................... 287
MRI and MR Angiography (10:00 Hours)....... 287
Questions to Answer by Ultrasound Techniques .287
Neurosonologic Findings (12:00 Hours)........ 287
Conventional Angiography (16:00 Hours) ...... 288
Clinical Course (2) .......................... 288
Questions to Answer by Ultrasound Techniques.288
Follow-up Neurosonologic Findings (6 Months).288
Clinical Course (3) .......................... 288
Final Diagnosis ............................. 288
Discussion ................................. 294
Case 25 Progressive M1 Middle Cerebral
Artery Occlusion
Clinical Presentation ........................ 297
Initial Neuroradiologic Findings .............. 297
Suspected Diagnosis ........................ 297
Questions to Answer by Ultrasound Techniques .297
Initial Neurosonologic Findings (Day 2) ........ 297
Conventional Angiography (Day 4) ............ 297
Clinical Course (1) .......................... 298
Clinical Course (2) and Follow-up
Neuroradiologic Findings
Follow-up Neurosonologic Findings (10 Months) 298
Clinical Course (3) .......................... 298
Final Diagnosis ............................. 298
Discussion ................................. 303
Case 26 Extracranial Vertebral Artery
Dissecting Aneurysm following
Basilar Artery Stenting
Clinical Presentation ........................ 306
Initial Neuroradiologic Findings .............. 306
Suspected Diagnosis ........................ 306
Conventional Angiography ................... 306
Clinical Course (1) .......................... 306
Questions to Answer by Ultrasound Techniques .306
Initial Neurosonologic Findings (Day 1) ........ 306
Cranial CT and CTA (Day 1)................... 307
Clinical Course ............................. 307
Final Diagnosis ............................. 307
Discussion ................................. 310
Case 27 Diffuse Cerebral Angiomatosis ....... 312
Clinical Presentation ........................ 312
Initial Neuroradiologic Findings .............. 312
Suspected Diagnosis ........................ 312
Questions to Answer by Ultrasound Techniques .312
Initial Neurosonologic Findings ............... 312
Conventional Angiography ................... 313
................... 297
.................... 298
.............. 306
Clinical Course ............................. 313
Final Diagnosis ............................. 313
Discussion ................................. 316
Case 28 Subclavian Steal Phenomenon in
Subclavian Artery and Internal
Carotid Artery Occlusion
Clinical Presentation ........................ 319
Initial Neuroradiologic Findings .............. 319
Suspected Diagnosis ........................ 319
Questions to Answer by Ultrasound Techniques .319
Initial Neurosonologic Findings (Day 1) ........ 319
Conventional Angiography (Day 2) ............ 320
Clinical Course (1) .......................... 320
Follow-up Neurosonologic Findings (4 Weeks) .320
Clinical Course (2) .......................... 320
Final Diagnosis ............................. 320
Discussion ................................. 326
Case 29 Cerebral Venous Thrombosis......... 331
Clinical Presentation ........................ 331
Initial Neuroradiologic Findings .............. 331
Suspected Diagnosis ........................ 331
Questions to Answer by Ultrasound Techniques 331
Initial Neurosonologic Findings (Day 1) ........ 331
CT Angiography (CTA) (Day 1) ................ 331
Clinical Course (1) .......................... 331
Question to Answer by Ultrasound Techniques .. 331
Follow-up Neurosonologic Findings (Day 90)... 331
Question to Answer by Ultrasound Techniques .332
Follow-up Neurosonologic Findings (Day 180) .. 332
Clinical Course (2) .......................... 332
Final Diagnosis ............................. 332
Discussion ................................. 335
Case 30 Multilocular Extra- and Intracranial
Stenoses and Occlusions
Clinical Presentation ........................ 338
Initial Neuroradiologic Findings (Day 1) ....... 338
Suspected Diagnosis ........................ 338
Questions to Answer by Ultrasound Techniques .338
Initial Neurosonologic Findings (Day 20) ....... 338
Conventional Angiography (Day 22)........... 339
Clinical Course (1) .......................... 339
Questions to Answer by Ultrasound Techniques .339
Follow-up Neurosonologic Findings (Day 29)... 339
Follow-up Neurosonologic Findings (3 Months).340
Final Diagnosis ............................. 340
Discussion ................................. 348
............ 319
............ 338
References...................................................................................... 351
Index ............................................................................................ 375
To access additional material or resources available with this e-book, please visit
http://www.thieme.com/bonuscontent. After completing a short form to verify your e-book
purchase, you will be provided with the instructions and access codes necessary to retrieve
any bonus content.
List of Abbreviations
XIII
ACA anterior cerebral artery
AChA anterior choroidal artery
ACoA anterior communicating artery
ACV anterior cerebral vein
ADB angiomatosis Divry–Van Bogaert
ADC apparent diffusion coefficient
AICA anterior inferior cerebellar artery
ATA anterior temporal artery
AVM arteriovenous malformation
BA basilar artery
BIF bifurcation
BVF blood volume flow
BVR basal vein of Rosenthal
BZI border zone infarction
CA calcarine artery
CANCA cytoplasmic antineutrophilic cytoplasmic
antibody
CBF cerebral blood flow
CBV cerebral blood volume
cc cervico-cranial
CCA common carotid artery
CCT cerebral circulation time; cranial computed
tomography
CoS confluens sinuum
CS cavernous sinus
CSF cerebrospinal fluid
CT computed tomograph
CTA computed tomographic angiography
CVR cerebrovascular reactivity
CVT cerebral venous thrombosis
CW circle of Willis
DMCV deep middle cerebral vein
DSA digital subtraction angiography
ECA external carotid artery
EC-IC extracranial-intracranial
EDV enddiastolic velocity
ESR erythrocyte sedimentation rate
FLAIR fluid attenuated inversion recovery
FMD fibromuscular dysplasia
FS fat saturation
FT fetal type
FT-PCA fetal-type posterior cerebral artery
GE gradient echo
HSV herpes simplex virus
ICA internal carotid artery
ICH intracranial hemorrhage
ICP intracranial pressure
ICV internal cerebral vein
IJV internal jugular vein
IMT intima-media-thickness
IPS inferior petrosal sinus
ISS inferior sagittal sinus
LMC leptomeningeal collateral
LSA lenticulostriate artery
MCA middle cerebral artery
MES microembolic signal
MI mechanical index
MIP maximal intensity projection
MRA magnetic resonance angiography
MRI magnetic resonance imaging
MRV magnetic resonance venography
MSCT multislice CT
MSCTA multislice CTA
MTT mean transit time
NIHSS National Institutes of Health Stroke Scale
OA ophthalmic artery
OccA occipital artery
OTA occipitotemporal artery
PC phase-contrast
PCA posterior cerebral artery
PCoA posterior communicating artery
PET positron emission tomography
PI pulsatility index
PICA posterior inferior cerebellar artery
POA parietooccipital artery
PRF pulse repetition frequency
PSV peak systolic velocity
PTA percutaneous transfemoral angioplasty
PTT partial thromboplastin time
rt-PA recombinant tissue plasminogen activator
SA subclavian artery
SAH subarachnoid hemorrhage
SCA superior cerebellar artery
SCOI small centrum ovale infarction
SiS sigmoid sinus
SPECT single photon emission computed
tomography
SphS sphenoparietal sinus
SPS superior petrosal sinus
SSP subclavian steal phenomenon
SSS superior sagittal sinus
STeA superficial temporal artery
STeA-MCA superficial temporal artery-middle cerebral
artery
XIV List of Abbreviations
StS straight sinus
SWS Sturge–Weber syndrome
TAV time-averaged velocity
TCCS transcranial color-coded sonography
TCD transcranial Doppler
TEE transesophageal echocardiography
TIA transient ischemic attack
TIBI thrombosis in brain ischemia
TOF time-of-flight
TR repetition time
TS transverse sinus
TTE transthoracic echocardiography
VA vertebral artery
VG vein of Galen
VV vertebral vein
WG Wegener granulomatosis
WMS Wyburn–Mason syndrome
Introduction
XV
Stroke is the most common brain disease. In spite of the
often homogeneous clinical picture, there are many different causes of stroke. The institution of tailored, targeted
therapy requires rapid etiological classification and evaluation of the vascular status.
In the 1970s, conventional invasive angiography was
practically the only method for visualizing the arteries
supplying the brain. In the 1980s, magnetic resonance
imaging (MRI) and MR angiography (MRA) were developed, and since the end of the 1990s, computed tomography (CT) has metamorphosed from simple penchymal to
angiologic imaging. The latter two techniques are now
well established, though they do have limitations: MRI
requires compliance and may not be used in patients
with a pacemaker, whereas CT angiography (CTA) involves
radiation exposure and the administration of a contrast
agent.
Diagnostic ultrasound is a noninvasive technique. It was
introduced in the early 1970s and became a reliable
method for neurovascular imaging in the 1980s with the
use of extracranial color-coded duplex sonography and
transcranial Doppler (TCD) techniques. The development
of transcranial color-coded sonography (TCCS) in the early
1990s was another milestone for the technique. TCCS
greatly facilitated vessel identification because of the additional spatial information derived from B-mode and colormode images. In the late 1990s, TCCS reached a diagnostic
sensitivity equal to TCD. Compared with the current generation of TCCS ultrasound systems, TCD is no longer an
acceptable alternative, particularly because of theinherent
problem of precise vascular identification and considerable operator dependency. The combination of extra- and
intracranial duplex ultrasound permits an almost complete assessment of all brain-supplying vessels with a
single bedside device. For comparison, in myocardial infarctions, the target vessels can be assessed only with
invasive or CT angiography. In our opinion the TCD technique, which is currently still widely used, will lose its
importance in vascular diagnostics because of the abovementioned limitations and the developments in TCCS, MR
and CT imaging. However, TCD is likely to remain, and may
even gain importance, as a method for functional assessments in stroke diagnostics. This is because of its ability to
detect microemboli and assess cerebrovascular reactivity,
for example, and because it allows continuous bilateral
monitoring. Until now, conventional digital subtraction
angiography (DSA) has been the gold standard in diagnos-
tics of the brain-supplying arteries purely because of its
sensitivity. It is used in primary stroke diagnostics in many
countries. At the beginning of this decade, DSA was a
frequent part of the routine diagnostic algorithm in our
hospital, too. However, in recent years MRA, CTA, and
ultrasound have increasingly come to the fore. Thus it
seemsthatDSAwillloseitssignificanceinacutestroke—except for the therapeutic option of intraarterial
thrombolysis—in favor of less invasive diagnostic methods.
But which method is the best for acute diagnosis as well
as chronic phases of brain ischemia? In contrast with
cardiology, doctors treating stroke patients have several
angiologic methods—partly competing, partly complementary—at their disposal. A rapid and valid assessment
of extra- and intracranial vascular pathology is essential,
particularly for thrombolysis outside the classic 3-hour
timeframe. MRA, CTA, and ultrasound can be equally important here. However, each of these methods has its
strengthsand weaknesses. Examplesof limitations include
availability of equipment and/or trained staff, patient restrictions (such as avoiding MRI in patients with pacemakers or contrast imaging in patients with relevant allergies), restrictions due to the inability to identify certain
vessel segments, and the associated cost implications. Our
book describes the use of these methods. However, the
focus of our presentations is the neurosonologic examination, as we want to emphasize the ultrasound techniques
and compare them in a sensible context with the other
available angiologic methods.
The concept of this book is based on the authors’ (J.M.
Valdueza, S.J. Schreiber, J.E. Roehl) teaching experiences in
ultrasound courses over the past 8 years. We realized that
the presentation of real-life cases induced the greatest
interest among our course participants, subsequently
leading to lasting learning. The book is divided into two
parts. Part A outlines the necessary basic principles, with a
particular focus on the precise description of ultrasound
anatomy and the related examination techniques. The
enclosed DVD contains video sequences of a complete
extra- and intracranial arterial and venous duplex examination. Part A describesand explains technical and devicerelated aspects that are necessary to know for clinical
application of the techniques. This section also includes a
discussion of the basic principles of cerebral hemodynamics and the typical constellations of pathologic findings.
The principal aspects of stroke from a clinico-radiological
XVI Introduction
point of view are presented in a separate chapter. Part A
ends with an overview of the current available radiologic
techniques: DSA, MRA, and CTA (R. Klingebiel).
In Part B, we present 30 case histories of selected pa-
tients managed in the Department of Neurology of the
University Charité Hospital of the Humboldt University
Berlin (Germany) between the years 2000 and 2005.
Each case is divided into two sections: the case report
and a discussion. The case reports, their diagnostic algorithm, and the therapeutic strategy are presented in chronologic order. Each case report begins with a short history
of the presenting complaint and a description of the initial
radiologic findings. On these grounds, we have formulated
a hypothesis and angiologic questions to be answered by
ultrasound. The findings of extra- and intracranial colorcoded duplex sonography are controlled for plausibility
and the postulated hypothesis is confirmed or rejected. A
final diagnosis is then made on the basis of the findings of
all the diagnostic procedures, including the parenchymal
and vascular imaging. In more than 20 of the cases, additional video sequences of the ultrasound studies are provided on the DVD accompanying this book to give a better
impression of the real examination situation and also to
emphasize the advantages of the ultrasound technique as
the single noninvasive real-time imaging method. In cases
with a complex hemodynamic constellation, we have provided additional schematic drawings that illustrate the
occlusive process and collateral situation. The case discussion is divided into a clinical and an angiologic-anatomic
part. The former gives a short overview of the diagnosed
diseaseaswellasspecificdiagnosticandtherapeuticaspects of the case. The latter focuses on ultrasound-related
or general angiologic questions arising from the individual
case.
According to the complexity of the ultrasound examination, the presented cases are categorized into three levels
of difficulty: low, medium, and high (10 cases in each
category). This allows readers to use the book according
to their level of expertise. Beginners can start by reading
the general part and progressively approach more complex questions. Experienced examiners may focus on the
case reportsand only consult the general part if necessary.
What will be the gold standard of neuro-angiologic
diagnostics in 10 years’ time? MRA, CTA, and ultrasound
are currently undergoing rapid and successful develop-
ments. Methods that were thought to be out of date are
suddenly surprising the experts with new approaches and
perspectives. The basic anatomy will not change, but the
expectation of more and more accurate anatomic vascular
classification is increasing. This particularly applies to the
diagnosis of intracranial stenoses as they are probably
underestimated as a cause of cerebral ischemia. Consequently, complete imaging is required not only of the
extracranial brain-supplying arteries but also of the more
distal segments of the major intracranial vessels.
We believe that the clinical attending physician as well
as the radiologist should know the methodologic principles of the available angiologic techniques and that they
should be aware of the particular strengths and weaknesses of these methods so that they can offer the patient
the best diagnosis, using the most economically viable
techniques. Our particular interest is to promote the duplex ultrasound technique while giving the user a better
understanding of the technique’s potential within the clinical context. In our opinion, color-coded duplex sonography has a good chance to sustain or even further improve
its position in the field of diagnostics because of its wide
availability, low cost, and noninvasive character.
The book is aimed at all doctors, in particular neurologists, neurosurgeons, internists, angiologists, and (neuro-)
radiologists, who treat neurologic or neurosurgical patients with vascular diseases.
We would like to thank all those who directly or indirectly contributed to this book. We especially want to
express our profound gratitude to our wives and partners
for their constant support and understanding. We thank
Dr. Florian Doepp for his contribution to the topic of embolus detection and Juliane Gruß for her patience while
taking the images to demonstrate the exact placement of
the ultrasound probe. Our particular thanks go to Dr.
Niksha Ranpura who contributed to the linguistic improvement of this project. And finally, we also want to
thank Dr. Cliff Bergman, Rachel Swift, and Elisabeth Kurz
from Thieme Publishers for their quick and reliable support in all developmental phases of this book.
José M. Valdueza
Stephan J. Schreiber
Jens-Eric Roehl
Randolf Klingebiel
Part A Principles and Rules
1 Flow and UltrasoundBasics................... 2
2 Vascular Anatomy and Structure
of UltrasoundExamination ................... 13
3 Intracranial Hemodynamics and Functional
Tests...................................... 54
4 Pathogenesis of Stroke....................... 64
5 Vascular Pathology.......................... 76
6 Angiographic Techniques inNeuroradiology..... 111
2
1
FlowandUltrasoundBasics
Flow Dynamics ................................ 2
Physics of Flow................................. 2
FlowPattern andFlow Velocity ................... 2
Ultrasound Principles ........................... 3
DopplerEffect.................................. 3
Flow Dynamics
Physics of Flow
The flow of a liquid substance in a tubular system can be
described by the following physical rules. According to
Hagen–Poiseuille’slaw,flowvelocityinastraighttube
depends on the pressure gradient (Dp), the vessel diameter
(r) and the vessel length (l) (Fig.A1.1). This function, in
general, also applies to the human vascular system in
which pressure is generated by the pump function of the
heart. However, the pressure gradient is difficult to assess
accurately because the diameter of the blood vessels in the
system varies and vessels rarely follow a straight path. This
restricts the direct application of the Hagen–Poiseuille law
in clinical practice.
DopplerShift and Flow Velocity................... 4
Ultrasound Systems ............................ 6
Ultrasound Transducer........................... 6
Imaging Modalities, Parameters,and Settings....... 7
Flow Pattern and Flow Velocity
Flow in a vessel system can be linear or turbulent depending on the vessel size and flow velocity (Figs A1.2–A1.4).
Our example in Figure A1.2 shows the water flow in a
segment of the Colorado River as it flows through the
Grand Canyon (Colorado, USA). The width of the river
changes from relatively wide with calm flow to narrow,
and cataracts can be seen in this segment. The river then
widens again and the flow becomes calmer. Within the
calm areas the water flow is steady but flow velocity
increases distinctly within the narrowing, i. e., within the
stenosis (Fig. A1.3). While flow in the wider segments of
the river is laminar, it changes to turbulent within the
narrowed areas (Fig. A1.4). Applying this phenomenon to
the human vasculature, flow velocity increase occurs in
I
V
P
r
2
∆P·r
/8·η·I
V=
P–P*=V·8·η·I/π·r
Fig. A1.1 Hagen–Poiseuille’s law. V= mean velocity; P–P*= pressure
gradient; l = vessel length; r = vesselradius, h: dynamic fluid viscosity.
4
P*
Fig. A1.2 The pattern of flow of water in the Colorado River as it
flows through the Grand Canyon (Colorado, USA). Note the normal,
calm flow in the wider segments of the river and the increase in flow
and turbulence in the narrow segment. (Reproduced from Google
Earth, Mount View, USA.)
Ultrasound Principles 3
Laminar flow Laminar flowTurbulence
Flow velocity
Vessel narrowing
=stenosis
Vessel narrowing
=stenosis
Fig. A1.3 Schematic drawing of the changes in flow velocity around
and within a vessel narrowing: Normal initial flow velocity, increased
velocity within the stenosis and normalized flow afterward.
any case of vessel narrowing. In addition, this phenomenon can be observed in vessel segments with a raised
pressure gradient, i.e., hyperperfusion within a normalsized vessel. If flowvelocity reaches a certain magnitude, it
changes from laminar to turbulent. This is why turbulent
flow is always looked for in vessel stenosis. Turbulence can
also be seen in regions with vessel elongation, kinking, or
hyperperfusion, which sometimes limits its diagnostic
value.
Ultrasound Principles
Doppler Effect
Diagnostic ultrasound enables visualization and measurement of the phenomenon of flow dynamics. Ultrasound is
generated by oscillating piezoelectric elements, emitting
frequencies in the nonaudible range between 20 kHz and
1 GHz (Hz = Hertz = number of oscillations per second).
This frequency travels through the human body tissues in
the form of a wave. While traveling through tissue at a
speed of approximately 1500 m/s, the wave is reflected by
various structures which may be resting (tissue) or moving
(blood corpuscles, mainly erythrocytes). The reflected
wave is then analyzed. When there is a frequency shift
between the emitted and received frequency, a “Doppler
effect” has occurred, named after the physicist Christian A.
Doppler (Fig. A1.5).
The Doppler effect can easily be explained using audible
sound. Consider a chamber tone “A” tuning fork emitting
sound with a frequency of 440 Hz (Fig.A1.6). This frequency travels with the speed of sound (330 m/s) toward
an observer, who can hear exactly the same frequency of
440 Hz. However, if the observer rides a bicycle at a speed
of 18 km/h (5 m/s) towards thetuning forkhis speed would
lead to the subjective registration of a higher frequency,
i. e., 447 Hz in our example.
Fig. A1.4 Schematic drawing of the flow pattern around and within
a vessel narrowing: Initial laminar flow changing to turbulent flow
within the stenosis, with the normal laminar flow pattern resuming
after the stenosis.
Fig. A1.5 Christian A. Doppler (1803–1853).
The human auditory system (Fig. A1.7)isabletorecognize a Doppler frequency shift of the audible sound. An
ambulance with sirens moving toward or away from us
will lead to characteristic changes in the received sound
pitch. All ultrasound systems are constructed in a pattern
which resembles the human hearing system (Fig. A1.8).
The difference between emitted and received frequencies
(Doppler shift) is caused by the reflection of ultrasound by
various moving reflectors—the corpuscular blood components.
The received frequency is amplified (corresponding to
the function of the tympanic membrane and ossicles). A
demodulator subtracts the received from the emitted frequency (f*– f)whichisthendirectlysenttoaspeaker,as
theDopplershiftiswithintheaudiblekHzrangeofthe
human ear. In addition, flow direction is determined, depending on whether f*– f is positive or negative. Finally,
the received frequency spectrum is processed by a Fourier
1 Flow and Ultrasound Basics4
440Hz
330m/s
330m/s
Fig. A1.6 Example of the Doppler effect occurring within the range
of the audible sound. An observer evaluates the sound emitted by a
tuning fork. Top: The observer stands still. The emitted frequency is
identical to the received frequency. Bottom: The observer is moving
toward the acoustic source, therefore passing more quickly through
the sound waves resulting in a subjectively higher received frequency.
Acoustic Doppler shift analysis
Moving
acoustic
source
Fig. A1.7 Schematic drawing of the human auditory apparatus and
its ability to detect a frequency shift of a moving acoustic source.
Ultrasound Doppler shift analysis
Emitter (f)
Receiver (f*)
Tympanic
membrane
Inner ear and central
nervous system
Amplifier
440Hz
447Hz?
5m/s
Middle ear
Demodulator
(f*– f)
(Frequency)
Tenor
Baritone
Bass
1
2 3 (Time)
Loud Medium Low
Fig. A1.9 Explanation of Fourier analysis with the example of achoir.
A frequency analysis is performed over time. At defined timepoints
the song is analyzed and documented in colored boxes according to
the active singers (= frequencies) and to the strength at which they
sing, i.e., point 1 depicts the moment when the tenor is loudest, the
baritone sings at moderate volume and the bass has the weakest
sound.
analysis. This calculation can be explained by the following
example: An observer is asked to analyze the male voices
of a choir. At timepoints 1, 2, and 3 seconds, he is asked to
mark on a diagram how loud he can hear the tenor, baritone, and bass. At time points 1 and 2, the tenor is the
loudest, the baritone is moderately loud, and the bass is
the quietest. At time point 3, the tenor is silent while the
bass is loudest (Fig. A1.9). Applying this to Doppler frequencies, a large Doppler shift translates into high flow
velocity and a small Doppler shift translates into a low flow
velocity, while the volume depends on the number of
reflectors, moving with a given flow velocity. In our example (Fig. A1.10), most erythrocytes are flowing fast, a moderate number are slower, and a small number are very
slow, which is usually the case in regions with a laminar
flow pattern.
Extension of frequency step numbers of timepoints per
second leads to a typical Doppler spectrum (Fig. A1.11).
The exact number of frequency steps varies from 64 to 256
depending on the Doppler or duplex ultrasound system
being used.
Discriminator
of flow direction
Frequency analysis
Fourier analysis
Fig. A1.8 Schematic drawing demonstrating the analogy of a diagnostic ultrasound machine to the human auditory system.
Speaker
Doppler Shift and Flow Velocity
To transfer the Doppler shift (= a frequency in kHz) into
flow velocities (cm/s or m/s) the Doppler formula needs to
be applied (Equation A1.1). As the formula includes the
cosine of the insonation angle, exact flow velocity can only
be calculated if the ultrasound beam is directly in line with
the direction of blood flow in the vessel segment being
analyzed (cosine of 0° insonation angle =1). Therefore,