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Interventional Neuroradiology 17: 472-476, 2011 www.centauro.it
472
Intravascular Ultrasound and Virtual
Histology of Basilar Artery
Atherosclerotic Lesion
A Case Report
A. LÓPEZ-RUEDA1, A. GONZÁLEZ GARCÍA2, M. AGUILAR PÉREZ3,
I. GUTIÉRREZ JARRÍN2, A. MAYOL DEYÁ2
1 Interventional Neuroradiology, Hospital Clinic i Provincial; Barcelona, Spain
2 Interventional Neuroradiology, Hospitales Universitarios Virgen del Rocío; Seville, Spain
3 Klinik für Neuroradiologie, Katharinenhospital, Klinikum Stuttgart; Stuttgart, Germany
Key words: brain, cerebral, anterior communicating, aneurysm
Summary
To our knowledge, this paper presents the first
intravascular ultrasound and virtual histology
(IVUS-VH) study in the basilar artery. IVUS-
VH serves to characterize and determine the ex-
tension of the plaque and we also to check stent
placement.
Introduction
Although the composition of intracranial
atherosclerotic plaque has been researched us-
ing different imaging techniques, endovascular
ultrasound remains a technique not regularly
employed in interventional neuroradiology.
The initial validation for intravascular ultra-
sound and virtual histology (IVUS-VH) came
from an ex vivo model utilizing 51 excised and
sectioned human left anterior descending coro-
nary arteries 1. This demonstrated the potential
of this imaging tool for the analysis of plaque
vulnerability. The CAPITAL (Carotid Artery
Plaque Virtual histology Evaluation) study 2 re-
ported a strong correlation between plaque
characterization and subsequent true histologi-
cal examination of the plaque following endar-
terectomy. This is the first description, to our
knowledge, of IVUS-VH of the basilar artery
(BA), with the VH characterization of the
atherosclerotic plaque in an intracranial artery.
Case Report
A 57-year-old man with hypertension, alcohol
and tobacco abuse, diabetic retinopathy treated
with laser therapy, and IIb intermittent claudi-
cation, was evaluated for headache, gait instabil-
ity and vertigo. On physical examination, left
homonymous inferior quadrantanopia without
paresis or impaired sensation was detected.
Cranial MRI showed acute ischemic lesions
in the cerebellum and occipital lobes while MR
angiography disclosed severe stenosis in the
left vertebrobasilar junction, with BA involve-
ment, and in the right intrapetrous internal ca-
rotid artery (Figure 1). The right vertebral ar-
tery was hypoplastic.
The use of IVUS-VH was approved by our
institutional review board and written informed
consent was obtained. The patient was under
general anesthesia, with IV heparin (5000 U)
having been administered dual antiplatelet ther-
apy for the previous three days (aspirin 125 mg/
day and clopidogrel 75 mg/day). The four-vessel
cerebral angiography showed a hypoplastic right
Abbreviation key
IVUS = Intravascular Ultrasound
VH = Virtual Histology
BA = Basilar Artery
LVA = Left Vertebral Artery
PICA = Postero Inferior Cerebellar Artery
A. López-Rueda Intravascular Ultrasound and Virtual Histology of Basilar Artery Atherosclerotic Lesion
473
system at a rate of 0.5 mm/ second. During
pullback, continuous grey-scale IVUS was re-
corded. Radiofrequency data were captured at
the top of the R wave using a commercially
available system (In.Vision Gold, Volcano Cor-
poration Rancho Cordova, CA, USA). The da-
ta were stored on digital video discs. There
were no difficulties crossing the stenosis or
withdrawing the device over the stenosis. In
these B-mode images we detected a 90% sten-
otic lesion (Figure 2C). Virtual histology analy-
sis was performed for each frame, and the area
of each plaque constituent (fibrous, fibro-fatty,
calcific, and necrotic core) was determined in
an automated fashion using Volcano S5 soft-
ware (Volcano Corp). The process is time-con-
suming because adjustments to the borders
that delineate the plaque are usually necessary.
The intracranial plaque was studied with
IVUS-VH, showing a fibrolipid plaque without
necrotic core or calcium (Figure 2D). With
IVUS, the length of the plaque was assessed,
detecting the origin of the left PICA, which no
longer showed pathological intimal thickening.
The BA located above the brainstem and sur-
rounded by cerebrospinal fluid (Figure 2B) was
observed in IVUS. The stenosis was predilated
with a 3×12 mm balloon (Gateway, Boston Sci-
entific, Fremont Co., CA, USA) and a 4×15
vertebral artery, severe stenosis at origin of left
vertebral artery (LVA) and in the proximal BA.
We decided to treat the stenotic lesion since the
patient had only one vertebral artery. First,
IVUS-VH was performed on the lesion at the
origin of the LVA. The atherosclerotic plaque,
that caused a stenosis of almost 80%, was an
eminently fibrolipidic plaque. A balloon-ex-
panding stent was performed with excellent
revascularization. In post-stenting IVUS, the
correct placement of the stent was confirmed
with good stent apposition on the artery wall.
Then an exchange-length 0.014-inch micro-
wire was passed through the basilar stenosis
and prior to intervention, IVUS-VH images
were obtained using a 2.9F microcatheter (Ea-
gle Eye Gold catheter, Volcano Corporation,
Rancho Cordova, CA, USA) with an incorpo-
rated 20-MHz phased-array with a 64 piezoe-
lectric transducer. This may result in inferior
gray scale IVUS images when compared to the
contemporary rotational catheter system. The
procedure was carried out with rapid-exchange
monorail systems; the IVUS-VH beginning
from the distal vessel, at least 10 mm distal to
the culprit lesion and progressing in a retro-
grade direction to the most distal vertebral ar-
tery free of disease (Figure 2A). The catheter
was pulled back using the motorized pull-back
A B
Figure 1 A) DWI shows acute ischemic lesions in the left occipital lobe. B) MR angiography shows severe stenoses in the
left vertebrobasilar junction (arrow) and in the right intrapetrous internal carotid artery.
Intravascular Ultrasound and Virtual Histology of Basilar Artery Atherosclerotic Lesion A. López-Rueda
474
Figure 2 A) Road mapping over Eagle catheter (arrow) through the stenosis in the left vertebrobasilar junction. B) B-mode
IVUS image shows the LVA above the brainstem (star), surrounded by cerebrospinal fluid (white point). The picture shows
the postero-inferior cerebellar artery (PICA) (arrowhead) emerging from the left vertebral artery (arrow), whose wall is
composed of 2 hyperechoic lines with a hypoechoic line in the middle. The hypoechogenic line represents the middle layer
of the artery. C) B-mode IVUS image in the zone of maximum stenosis shows an eccentric plaque leaving the lumen close to
a part of the wall without plaque. D) Image of IVUS-VH in a maximum stenosis fibrolipidic plaque without necrotic core or
calcium.
A B
C D
www.centauro.it Interventional Neuroradiology 17: 472-476, 2011
475
carotid arteries for the same purpose. With this
procedure we can detect vulnerable plaque and
embolic risk areas within each plaque. In our
case, the atherosclerotic plaque of the BA was
an eccentric fibrolipid plaque, without necrotic
core and calcium areas. Such necrotic core and
calcium areas, when in contact with the lumen,
are defined in the CAPITAL study as vulnera-
ble areas (embolic areas). IVUS is also useful
to determine the extent of plaque, and to thus
determine the length and diameter of the stent.
Microcatheter navigability in the posterior cir-
culation is better than in the anterior circula-
tion because the artery has no bone anchor, un-
like the internal carotid artery that is anchored
to the petrous bone at the intrapetrous seg-
ment. Several cases of IVUS in an intracranial
artery have been described in the literature 3,4.
Takayama et al. are the only ones to use VH.
They published a case of angioplasty and stent-
ing with the assistance of IVUS-VH in intracra-
neal vertebral artery stenosis 5. In this case, the
IVUS-VH study was performed after balloon
dilatation, its artifact the VH study. The other
two cases were aided by IVUS in angioplasty
and stenting, without performing VH of the
plaque 3,4. To our knowledge this is the first
IVUS-VH study in the basilar artery.
Wingspan stent (Boston Scientific, Fremont
Co., CA, USA) was placed. In the IVUS after
stenting (Figure 3) we found a correct stent po-
sition, covering the plaque and well-adapted to
the vessel wall. The patient awoke from an-
esthesia without any complications. He was
kept on dual antiplatelet therapy for six months.
Discussion
Intravascular ultrasound and virtual histology
(IVUS-VH) is a procedure that enables us to
study atherosclerotic plaque, characterize it and
determine its length and composition. By color
coding, VH study shows four plaque compo-
nents: fibrous (dark green), fibrolipid (yellow/
green), necrotic core (red) and calcium (white).
No intraplaque hemorrhage can be detected by
IVUS-VH. The CAPITAL study 2 was carried
out on extracranial carotid plaque. It offers a
quantitative and morphological classification of
atherosclerotic plaque, defining six types of
plaque and identifying the most vulnerable, i.e.
those with a higher risk of embolism. The IVUS-
VH procedure started to be used in coronary
arteries for plaque characterization and an aid
to angioplasty and stenting. It was later used in
Figure 3 A) Post-stenting angiographic control with good results. B) Post-stenting ultrasound study confirms the correct
placement and the recovery of the arterial lumen. The stent can be seen in the hyperechoic lines without acoustic shadowing
(arrow) located between the lumen and residual plaque.
A B
Intravascular Ultrasound and Virtual Histology of Basilar Artery Atherosclerotic Lesion A. López-Rueda
476
5 Takayama K, Taoka T, Nakagawa H, et al. Successful
percutaneous transluminal angioplasty and stenting for
symptomatic intracranial vertebral artery stenosis us-
ing intravascular ultrasound virtual histology. Radiat
Med. 2007; 25: 243-246.
References
1 Diethrich EB, Margolis MP, Reid DB, et al. Virtual his-
tology intravascular ultrasound assessment of carotid
artery disease: the Carotid Artery Plaque Virtual His-
tology Evaluation (CAPITAL) Study. J Endovasc Ther.
2007; 14: 676-686.
2 Nair A, Kuban BD, Tuzcu EM, et al. Coronary plaque
classification with intravascular ultrasound radiofre-
quency data analysis. Circulation. 2002; 106: 2200-2206.
3 Wehman JC, Holmes DR Jr, Hanel RA, et al. Intravas-
cular ultrasound for intracranial angioplasty and stent
placement: technical case report. Neurosurgery. 2006;
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4 Meyers PM, Schumacher C, Gray WA, et al. Intravas-
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Antonio López-Rueda, MD
C/ Costa de la Luz, 76, 4ºC
04009 Almería (Spain)
Tel.: 652245767
Fax: 950149863
E-mail: alrueda81@hotmail.com
