-
DIAGNOSTIC TESTSMost neuroradiologic examinations of the central
nervous system (CNS) consist of computed tomography (CT), mag-netic
resonance imaging (MRI), magnetic resonance angiog-raphy (MRA), and
single-photon emission computed tomog-raphy (SPECT). Figure 341
shows normal contrast-enhanced CT anatomy. Figure 342 shows a
normal MRI brain scan. MRI is more sensitive than CT for detection
of neoplasms (Fig. 343). Small infarcts are also more easily
visualized by MRI, especially if they are located in the cerebellum
(Fig. 344) or brainstem. With diffusion-weighted imaging (DWI),
ischemic lesions can be demonstrated early. DWI is based on
the examination of free water movement. Restricted free water
movement is detected early, paralleling the development of
cytotoxic edema. The imaging sequences used are fast and not as
easily disturbed by inappropriate patient movement. A normal SPECT
scan is shown in Figure 345. SPECT scanning can be used for
evaluating neoplasms (Fig. 346) and demen-tia (Fig. 347).
Imaging of precerebral and cerebral vesselsDuplex sonography
allows for the evaluation of vessel anatomy, along with measurement
of the direction and velocity of blood ow. The degree of stenosis
is calculated from the blood ow
168
34 Section 2: Brain, peripheral nervous system, muscle
Chapter 34 Diagnostic tests and procedures
A B C
D E F
tp
tns
aw
cs
cq
P baba
tca
i
mc
t
sfac ac
cspmc
lgbcpdpc
fh
fm
ec
c
c
cc
sp
cv
sttr
sf
o
bvcv
f
f
llcth
st
ss
cp
3
pgV
Fig 341Normal contrast-enhanced CT anatomy. Figures A through F
show normal CT scans at various levels in the brain. 3, 4, third
and fourth ventricles; ac, anterior cerebral artery; ba, basilar
artery; bv, body of lateral ventricle; c, caudate nucleus; cc,
corpus callosum (genu); cp, cerebral peduncle; csp, cave of septum
pellucidum; cv, internal cerebral vein; f, falx; fh, frontal horn
of lateral ventricle; fm, foramen of Monro; i, infundibulum of
pitu-itary; mc, middle cerebral artery; o, white matter tracts; p,
pons; pc, posterior cerebral artery; pg, pineal gland; sf, sylvian
ssure; sp, septum between lateral ventricles; th, thalamus; tp,
temporal horn; tr, trigone of lateral ventricle.(From Grainger RG,
Allison DJ, Adam A, Dixon AK [eds]: Grainger and Allisons
Diagnostic Radiology: A Textbook of Medical Imaging, 4th ed.
London. Harcourt, 2001.)
Text continued on page 172
Ch33-44-X4919_161-213.indd 168 10/10/08 11:08:24 AM
-
169
Chapter 34: Diagnostic tests and procedures 34
cc
cs
cf
pof
tha
aca
oc
bap
t
BA C
fmth
tl
pgh
ec
cc
fl
tl
cn
pvs
pm
a 3gp
gf
Fig 342Normal MRI. A, T2-weighted sagittal images through the
midline. B, Corneal T2-weighted images through the hippocampi. C,
Coronal T1-weighted images through the level of the third
ventricle. 3,4, third and fourth ventricles; a, amygdala; aca,
anterior cerebral artery; ba, basilar ar-tery; cc, corpus callosum;
cf, calcarine ssure; ch, cerebellar hemisphere; cn, caudate
nucleus; cs, central sulcus; ec, external capsule; fh, frontal
horn; fh, frontal lobe; fm, foramen of Munro; gf, gyrus fusiformis;
gp, globus pallidus; h, hippocampus; mca, middle cerebral artery;
oc, optic chi-asm; oh, occipital horn; p, pons; pg, parahippocampal
gyrus; pm, putamen; pof, parieto-occipital ssure; pvs, perivascular
spaces; sf, sylvian s-sure; t, tectal plate; th, temporal horn;
tha, thalamus; tl, temporal lobe.(From Grainger RG, Allison DJ,
Adam A, Dixon AK [eds]: Grainger and Allisons Diagnostic Radiology:
A Textbook of Medical Imaging, 4th ed. London. Harcourt, 2001.)
A B
C D
Fig 343Oligodendroglioma. A, CT after intravenous contrast
medium shows a large left frontal tumor that involves the cortex.
It is predominantly solid with irregular en-hancement, but there
are also cysts and coarse cal-ci cation. B, Follow-up after 2 years
with CT. T2-weighted MRI (C) and T1-weighted postcontrast MRI (D)
show more extensive cyst formation and cal-ci cation than on the
rst scan. The calci cation is much less apparent on MRI and appears
as nonspe-ci c low signal areas. Posterior in ltration of the
tu-mor is, however, best seen on MRI (C). Note that the patient had
undergone a left frontal craniotomy after the rst scan.(From
Grainger RG, Allison DJ, Adam A, Dixon AK [eds]: Grainger and
Allisons Diagnostic Radiology: A Textbook of Medical Imaging, 4th
ed. London. Harcourt, 2001.)
Ch33-44-X4919_161-213.indd 169 10/10/08 11:08:27 AM
-
170
34 Section 2: Brain, peripheral nervous system, muscle
A B CFig 344Top of the basilar syndrome. T2-weighted MRI show
multiple infarcts in the basilar and posterior cerebral artery
territories including the left thalamus (A), both occipital lobes
(B) and cerebellar hemispheres (C). Note the absence of ow void in
the distal basilar artery in B (arrow).(From Grainger RG, Allison
DJ, Adam A, Dixon AK [eds]: Grainger and Allisons Diagnostic
Radiology: A Textbook of Medical Imaging, 4th ed. London. Harcourt,
2001.)
Fig 34599mTcHMPAO single-photon emission computed tomography
scan of the brain: axial (left) and sagittal (right) images. A,
anterior; R, right; L, left; P, posterior.(From Grainger RG,
Allison DJ, Adam A, Dixon AK [eds]: Grainger and Allisons
Diagnostic Radiology: A Textbook of Medical Imaging, 4th ed.
London. Harcourt, 2001.)
Fig 346201Tl single-photon emission computed tomography scan in
a 40-year-old man with a left frontotemporal mass on MRI. This
reveals the high uptake typical of high-grade glioma, which was con
rmed on biopsy to be a glioblastoma.(Courtesy of Professor Donald
M. Hadley, Glasgow.)
Ch33-44-X4919_161-213.indd 170 10/10/08 11:08:29 AM
-
171
Chapter 34: Diagnostic tests and procedures 34
A B
C D
E F
Fig 347Single-photon emission computed tomography scans of
normal subject (A); patient with Alzheimers disease showing
bilateral parietal lobe abnor-malities more marked on the right
side (B); patient with frontotemporal dementia, showing bilateral
frontal lobe abnormalities (C); patient with pro-gressive
supranuclear palsy, showing bilateral anterior abnormalities (D);
patient with corticobasal degeneration, showing asymmetrical right
fronto-parietal abnormality (E); patient with Creutzfeldt-Jakob
disease, showing multifocal cortical abnormalities (F).(From Tallis
R, Fillit H: Brockelhurstss Textbook of Geriatric Medicine and
Gerontology, 6th ed. London, Churchill Livingstone, 2003.)
Ch33-44-X4919_161-213.indd 171 10/10/08 11:08:31 AM
-
172
34 Section 2: Brain, peripheral nervous system, muscle
A B CFig 348Imaging of precerebral and cerebral vessels. A,
Color-coded Doppler sonography of the internal carotid artery close
to the bifurcation in a patient with pronounced atherosclerotic
changes and stenosis causing slowing of blood ow and turbulence
(green and blue signals). B, Contrast-enhanced magnetic resonance
angiography showing a tight stenosis of the internal carotid artery
(arrow). C, Conventional angiography showing a very tight stenosis
of the internal carotid artery (arrow).(From Crawford, MH, DiMarco
JP, Paulus WJ [eds]: Cardiology, 2nd ed. St. Louis, Mosby,
2004.)
Anteriorcommunicating
artery
Posteriorcommunicating
artery
External carotidartery
Common carotidartery
Anterior cerebralartery
Middle cerebralarteryBasilar artery
Vertebral artery
Internal carotidartery
Fig 349Magnetic resonance angiogram showing the arterial supply
to the brain.(From Crawford, MH, DiMarco JP, Paulus WJ [eds]:
Cardiology, 2nd ed. St. Louis, Mosby, 2004.)
velocity. Color-coded Doppler signals help visualize the
direc-tion of blood ow (Fig. 348 )
Conventional angiography (see Fig. 348C) allows good
visualization of the aortic arch and the origins of the neck
arter-ies but has a potential risk of nephrotoxicity, allergic
reactions, and thromboembolism.
MRA (Fig. 349) is useful for detection of carotid artery
stenosis (see Fig. 348B) and suspected carotid or vertebral ar-tery
dissection. MRA is also useful for evaluating the aortic arch (Fig.
3410) and the intracranial circulation (Fig.
3411).ELECTROENCEPHALOGRAPHYElectroencephalography (EEG) is a
measure of the electrical activity generated by the central nervous
system. It is useful to document abnormalities of the brain that
are not associated with detectable structural alterations in brain
tissue. It also pro-vides a continuous measure of cerebral function
over time. Electroencephalographic signals are generated by the
cerebral cortex. Different parts of the cortex generate distinct
uctua-tions. The uctuations also differ with eye opening and in the
sleep and waking states. Figure 3412 shows an electroencepha-logram
of a normal subject; an electroencephalogram of a brain-dead
patient is shown in Figure 3413.
Ch33-44-X4919_161-213.indd 172 10/10/08 11:08:41 AM
-
173
Chapter 34: Diagnostic tests and procedures 34
Fig 3410Contrast-enhanced MRA of aortic arch. A
three-dimensional gradient-echo sequence has been acquired during
the rst pass of an intrave-nously injected gadolinium bolus. It
shows the origins of the great ves-sels. Note also that there is
background opaci cation of the pulmonary vessels.(From Grainger RG,
Allison DJ, Adam A, Dixon AK [eds]: Grainger and Allisons
Diagnostic Radiology: A Textbook of Medical Imaging, 4th ed.
London. Harcourt, 2001.)
ACCM
CSA1 M2M1
PCOM
BA
petr CAP1P2
Fig 3411Three-dimensional TOF MRA of the intracranial
circulation, axially col-lapsed maximum intensity projection. A1,
precommunicating segment of anterior cerebral artery; ACOM,
anterior communicating artery; BA, basilar artery; CS, carotid
siphon; M1, rst (horizontal) segment of mid-dle cerebral artery;
M2, M2 segments of middle cerebral artery; P1, precommunicating
segment of posterior cerebral artery; P2, P2 seg-ment of posterior
cerebral artery; PCOM, posterior communicating artery; petr CA,
petrous segment of internal carotid artery.(From Grainger RG,
Allison DJ, Adam A, Dixon AK [eds]: Grainger and Allisons
Diagnostic Radiology: A Textbook of Medical Imaging, 4th ed.
London. Harcourt, 2001.)
Eyesopen
Eyesclosed
Fp1-F3
Fp1-F7
Fp2-F8
Fp2-F4
F3-C3
C3-P3
P3-01
F4-C4
C4-P4
P4-02
F7-T3
T3-T5
T5-01
F8-T4
T4-T6
T6-02
1 sec300 V
Fig 3412A posteriorly predominant 9-Hz alpha rhythm is present
when the eyes are closed and is attenuated by eye opening in the
electroencephalo-gram of this normal subject. Electrode placements
in this and Figure 34-13 are as follows. A, earlobe; C, central; F,
frontal; Fp, frontopolar; O, occipital; P, parietal; Sp, sphenoid;
T, temporal. Right-sided place-ments are indicated by even numbers
and left-sided placements by odd numbers.(From Goetz CG, Pappert
EJ: Textbook of Clinical Neurology, Philadelphia, WB Saunders,
1999)
Ch33-44-X4919_161-213.indd 173 10/10/08 11:08:44 AM
-
174
34 Section 2: Brain, peripheral nervous system, muscle
Fp1-C3
C3-O1
Fp1-T3
T3-O1
Fp2-C4
C4-O2
Fp2-T4
T4-O2
T3-CZ
CZ-T4
10 kOhm resistor
Dorsum of hand
ECG
1 sec 20 V
Fig 3413Electrocerebral silence in the electroencephalogram of a
brain-dead patient following attempted resuscitation after
cardiopulmonary arrest. See Figure 34-12 for electrode
placements.(From Goetz CG, Pappert EJ: Textbook of Clinical
Neurology. Philadelphia, WB Saunders, 1999.)
Ch33-44-X4919_161-213.indd 174 10/10/08 11:08:46 AM