AJR 2005; 184:1924-1931
© American Roentgen Ray Society
Incidental Finding on MDCT of Patent Ductus Arteriosus: Use of CT and MRI to Assess Clinical Importance
Orly Goitein,
Carl R. Fuhrman and
Joan M. Lacomis
Department of Radiology, University of Pittsburgh Medical Center, 200
Lothrop St., Rm. 4660 CHP MT, Pittsburgh, PA 15213-2582.
Received June 30, 2004;
accepted after revision September 29, 2004.
Address correspondence to J. M. Lacomis.
Abstract
OBJECTIVE. The purpose of this article is to describe the imaging
features of patent ductus arteriosus (PDA) identified on chest MDCT performed
for other indications and to describe the additional functional information
that cardiac MRI can provide about these lesions.
CONCLUSION. The daily use of MDCT studies for the evaluation of
pulmonary embolic disease or aortic abnormalities can reveal incidental PDAs.
Small incidental PDAs can be identified on chest MDCT angiography timed for
either the pulmonary arteries or the aorta. Using multiplanar reformations,
one can assess PDA location, caliber, length, and presence of calcifications.
The presence of a "positive" or a "negative contrast
jet" verifies a patent shunt. Cardiac MRI shows the detailed anatomic
and morphologic features of a PDA. Hemodynamic information revealing the
presence and severity of a significant shunt is obtainable using
velocity-encoded MRI, allowing accurate shunt calculation. Using MDCT and MRI,
information regarding the clinical significance of an incidental PDA can
influence management decisions. The imaging information was used to determine
that one PDA required intervention.
Introduction
Isolated patent ductus arteriosus (PDA) is estimated to account for
10-12% of all congenital heart anomalies
[1]. Persistence of a patent
ductus occurs as a result of failure of mechanisms that normally lead to
ductus closure with the change from fetal to adult circulation in the first
days of life [1]. Typically, in
adults, the presence of PDA is investigated only after patients become
symptomatic [2]. Traditionally,
the initial noninvasive diagnostic techniques are Doppler echocardiography and
MRI
[3-5];
however, the increasing use of contrast-enhanced MDCT angiography for the
evaluation of pulmonary embolic and aortic abnormalities has led to the
occasional identification of this abnormality. Because asymptomatic PDAs are
often small, they can be easily missed unless special attention is directed to
this specific anatomic region. Detailed anatomic and physiologic information
is necessary to consider the appropriate clinical management. Both MDCT
angiography and cardiac MRI can depict the precise anatomy of this abnormality
[5-7].
The purpose of this study is to outline the imaging features of incidental
PDAs on MDCT angiography and to emphasize the unique contribution of cardiac
MRI in hemodynamic cardiac evaluation that is necessary for clinical
interventional decisions.
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Fig. 1A. —65-year-old woman with scleroderma, severe pulmonary artery
hypertension, and cardiac murmur. Ao = aorta. AAo = ascending aorta, DAo =
descending aorta, PA = pulmonary artery. MDCT images (pulmonary embolic
protocol) obtained with mediastinal window settings (level, 400 H; width, 40
H) show markedly enlarged caliber of pulmonary artery and dilatation of
ascending aorta (A) and tubular structure (black asterisk)
abutting aorta with adjacent coarse calcifications (white arrow,
B).
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Fig. 1B. —65-year-old woman with scleroderma, severe pulmonary artery
hypertension, and cardiac murmur. Ao = aorta. AAo = ascending aorta, DAo =
descending aorta, PA = pulmonary artery. MDCT images (pulmonary embolic
protocol) obtained with mediastinal window settings (level, 400 H; width, 40
H) show markedly enlarged caliber of pulmonary artery and dilatation of
ascending aorta (A) and tubular structure (black asterisk)
abutting aorta with adjacent coarse calcifications (white arrow,
B).
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Fig. 1C. —65-year-old woman with scleroderma, severe pulmonary artery
hypertension, and cardiac murmur. Ao = aorta. AAo = ascending aorta, DAo =
descending aorta, PA = pulmonary artery. With optimized window settings (level
400 H; width, 280 H), tubular structure (asterisk) can be seen
abutting aorta. Unenhanced blood can be seen flowing from aorta to pulmonary
artery via patent ductus arteriosus (PDA) (white arrow). Adjacent
coarse calcifications are marked with black arrow.
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Fig. 1D. —65-year-old woman with scleroderma, severe pulmonary artery
hypertension, and cardiac murmur. Ao = aorta. AAo = ascending aorta, DAo =
descending aorta, PA = pulmonary artery. Oblique multiplanar reformation with
optimized window settings (level, 400 H; width, 280 H) shows unenhanced blood
flowing from less-opacified aorta to maximally enhanced pulmonary artery via
PDA, forming "negative jet" (black arrow). Adjacent
coarse calcifications are marked with white arrow. Appropriate window settings
(level, 400 H; width, 280 H) are necessary to show jet.
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The physiologic consequences of a PDA are determined by both its size and
the difference between the systemic and pulmonary vascular resistances. These
will determine the degree of left-to-right shunting
[1]. Before the introduction of
antibiotic therapy, infective endocarditis (IE) was a common fatal
complication of many processes, including PDA. Wide use of antibiotics and PDA
closure have reduced the incidence of IE significantly; however, IE prevention
is still a main indication for PDA closure
[1,
8]. Interestingly, in the
setting of a PDA with the presence of hemodynamically significant pulmonary
hypertension, because the left-to-right shunt is restricted or reversed, there
is actually a protective mechanism against the development of IE
[1,
8]. Although a small ductus
accompanied by a small shunt does not cause significant hemodynamic
derangement, it may predispose to endocarditis, especially if accompanied by
an audible murmur [1,
2]. The decision to treat an
adult with a small PDA is therefore influenced by the presence or absence of a
murmur. Conversely, according to the latest consensus statement by the
Canadian Cardiovascular Society on treatment of adults with congenital heart
diseases, the risk of endocarditis for patients with a small silent PDA is
unknown but is probably very low with only sporadic case reports existing in
the literature. The consensus statement recommends no intervention for a
small, inaudible PDA [2].
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Fig. 1E. —65-year-old woman with scleroderma, severe pulmonary artery
hypertension, and cardiac murmur. Ao = aorta. AAo = ascending aorta, DAo =
descending aorta, PA = pulmonary artery. MDCT with volume-rendered 3D
reconstruction shows aorta and pulmonary artery with PDA (white
asterisk) connecting two and adjacent coarse calcifications (white
arrow).
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Fig. 1F. —65-year-old woman with scleroderma, severe pulmonary artery
hypertension, and cardiac murmur. Ao = aorta. AAo = ascending aorta, DAo =
descending aorta, PA = pulmonary artery. On cardiac steady-state free
precession MR images, axial plane (F) and sagittal plane (G)
images show dephasing of blood (white arrows) in pulmonary artery
caused by blood flow from aorta to pulmonary artery via PDA.
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Fig. 1G. —65-year-old woman with scleroderma, severe pulmonary artery
hypertension, and cardiac murmur. Ao = aorta. AAo = ascending aorta, DAo =
descending aorta, PA = pulmonary artery. On cardiac steady-state free
precession MR images, axial plane (F) and sagittal plane (G)
images show dephasing of blood (white arrows) in pulmonary artery
caused by blood flow from aorta to pulmonary artery via PDA.
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Fig. 1H. —65-year-old woman with scleroderma, severe pulmonary artery
hypertension, and cardiac murmur. Ao = aorta. AAo = ascending aorta, DAo =
descending aorta, PA = pulmonary artery. Volume-rendered 3D-reconstruction
gadolinium-enhanced MR angiogram shows aorta and pulmonary artery with PDA
(asterisk) connecting the two.
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In this setting, findings of chest radiographs and ECGs are uniformly
normal [1].
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Fig. 1I. —65-year-old woman with scleroderma, severe pulmonary artery
hypertension, and cardiac murmur. Ao = aorta. AAo = ascending aorta, DAo =
descending aorta, PA = pulmonary artery. Ten months after PDA closure, MDCT
(pulmonary embolic protocol) oblique multiplanar reconstruction with optimized
window settings (level, 400 H; width, 280 H) shows that PDA occluder is in
place (arrowhead) with adjacent calcifications (arrow).
Absence of jet verifies functionality of occluder.
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PDA on Echocardiography
Echocardiographic detection of PDA relies on the presence of left-sided
heart chamber enlargement or turbulent flow in the proximal pulmonary artery
or both. Thus, small PDAs can be missed on routine echocardiography (unless
specifically interrogated)
[3].
Incidental PDA on MDCT Angiography
Nongated MDCT angiography preformed for other indications, timed for either
the pulmonary artery or the aorta, can show incidental PDAs. MDCT enables
precise visualization of the location, size, presence and extent of
calcification, and the relationship to adjacent anatomic structures.
Cardiac-gated MDCT has been previously shown to identify these defects in
patients with known PDAs detected by echocardiography or catheter angiography
[6,
7]. The axial source images
should first be assessed for the caliber of the main pulmonary artery
(Fig. 1A). A main pulmonary
artery greater than 3 cm in diameter can occur normally in large patients or
abnormally, not only in pulmonary hypertension but also in other abnormal
conditions including pulmonic stenosis and Takayasu's arteritis
[9]. The presence of a small
tubular structure, separate or continuous with either the aorta or the
pulmonary artery, is suspicious for a PDA (Figs.
1B and
2A). Associated calcifications
may be present. Multiplanar reformations are of major importance in
establishing a correct diagnosis of a PDA. Positive diagnosis of PDA relies on
the ability to prove a continuous and patent connection between the aorta and
the pulmonary artery with evident flow (Figs.
1D,
2C,
2D, and
4B). A small diverticulum at
the site of the ductus can have similar features on the axial images (Figs.
3A,
3B,
3C). Complex cases with
concomitant different abnormalities can be accurately assessed using
multiplanar reformations (Figs.
4A,
4B, and
4C). The presence of a
"negative jet" of unenhanced blood flowing from the aorta to the
pulmonary artery via the PDA (seen in studies timed for the pulmonary artery)
or of a "positive jet" of enhanced blood flowing from the aorta to
the unenhanced pulmonary artery via the PDA (seen in studies timed for the
aorta) verifies the presence of a shunt (Figs.
1C,
1D, and
2B,
2C,
2D). Vascular window settings
(length, 400 H; width, 280 H) are used to accurately identify the presence of
such jets because the standard mediastinal window settings can obscure such
subtle findings (Figs. 1B,
1C,
1D,
2C, and
2D). Three-dimensional
volume-rendered models can assist in showing the anatomic relationship of the
aorta, the pulmonary artery, and the PDA
(Fig. 1E).
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Fig. 2A. —49-year-old man evaluated for questionable aortic root
dilatation seen on transthoracic echocardiography. Ao = aorta. AAo= ascending
aorta, DAo = descending aorta, PA = pulmonary artery, LV = left ventricle.
Axial MDCT (aortic protocol) with mediastinal window settings (level,
400 H; width, 40 H) show thin tubular structure (asterisk) between
ascending and descending aorta (A). This patent ductus arteriosus (PDA)
has horizontal orientation, making it more obvious on axial images. Lower
level (B) shows thin "positive jet" (arrow) of
contrast media flowing from maximally enhanced aorta to less-opacified
pulmonary artery.
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Fig. 2C. —49-year-old man evaluated for questionable aortic root
dilatation seen on transthoracic echocardiography. Ao = aorta. AAo= ascending
aorta, DAo = descending aorta, PA = pulmonary artery, LV = left ventricle.
Sagittal multiplanar reconstruction (C) with mediastinal window
settings (level, 400 H; width, 40 H) and (D) with optimized window
settings (level, 400 H; width, 280 H) show that contrast-enhanced PDA forms
subtle "positive jet" (arrow) flowing through PDA
(asterisk) from enhanced aorta to less-opacified pulmonary artery.
Appropriate use of window settings is necessary to identify this subtle
finding.
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Fig. 2D. —49-year-old man evaluated for questionable aortic root
dilatation seen on transthoracic echocardiography. Ao = aorta. AAo= ascending
aorta, DAo = descending aorta, PA = pulmonary artery, LV = left ventricle.
Sagittal multiplanar reconstruction (C) with mediastinal window
settings (level, 400 H; width, 40 H) and (D) with optimized window
settings (level, 400 H; width, 280 H) show that contrast-enhanced PDA forms
subtle "positive jet" (arrow) flowing through PDA
(asterisk) from enhanced aorta to less-opacified pulmonary artery.
Appropriate use of window settings is necessary to identify this subtle
finding.
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Fig. 4B. —72-year-old male trauma patient who underwent
contrast-enhanced axial CT to assess thoracic involvement (single detector,
5-mm collimation) with mediastinal window settings (level, 400 H; width, 40
H). Ao = aorta, AAo = ascending aorta, DAo = descending aorta, PA = pulmonary
artery. Sagittal multiplanar reconstruction shows that PDA (asterisk)
connects aorta and pulmonary artery. Multiplanar reconstruction quality is
degraded because collimation of source images was 5 mm on this study done with
single-detector scanner.
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Fig. 3A. —79-year-old man who underwent MDCT angiography (pulmonary
embolic protocol) with mediastinal window settings (level, 400 H; width, 40
H). Ao = aorta, AAo = ascending aorta, DAo = descending aorta, PA = Pulmonary
artery. Axial image shows tubular structure (asterisk) below aortic
arch suggestive of patent ductus arteriosus (PDA).
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Fig. 3B. —79-year-old man who underwent MDCT angiography (pulmonary
embolic protocol) with mediastinal window settings (level, 400 H; width, 40
H). Ao = aorta, AAo = ascending aorta, DAo = descending aorta, PA = Pulmonary
artery. Sagittal multiplanar reconstruction shows structure to be diverticulum
(asterisk) originating from aorta with no connection to pulmonary
artery.
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Fig. 3C. —79-year-old man who underwent MDCT angiography (pulmonary
embolic protocol) with mediastinal window settings (level, 400 H; width, 40
H). Ao = aorta, AAo = ascending aorta, DAo = descending aorta, PA = Pulmonary
artery. Sagittal multiplanar reconstruction with bone window settings (level,
2,500 H; width, 800 H), shows tiny calcified area abutting diverticulum
(arrow).
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Fig. 4A. —72-year-old male trauma patient who underwent
contrast-enhanced axial CT to assess thoracic involvement (single detector,
5-mm collimation) with mediastinal window settings (level, 400 H; width, 40
H). Ao = aorta, AAo = ascending aorta, DAo = descending aorta, PA = pulmonary
artery. Tubular structure, which is patent ductus arteriosus (PDA)
(asterisk), is seen below aortic arch. Bilateral pleural effusions
and atelectasis are also seen.
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Fig. 4C. —72-year-old male trauma patient who underwent
contrast-enhanced axial CT to assess thoracic involvement (single detector,
5-mm collimation) with mediastinal window settings (level, 400 H; width, 40
H). Ao = aorta, AAo = ascending aorta, DAo = descending aorta, PA = pulmonary
artery. At higher level, subtle aortic flap (arrowhead) is
identified. This patient had aortic tear in descending aorta, which was
surgically corrected.
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Fig. 2B. —49-year-old man evaluated for questionable aortic root
dilatation seen on transthoracic echocardiography. Ao = aorta. AAo= ascending
aorta, DAo = descending aorta, PA = pulmonary artery, LV = left ventricle.
Axial MDCT (aortic protocol) with mediastinal window settings (level,
400 H; width, 40 H) show thin tubular structure (asterisk) between
ascending and descending aorta (A). This patent ductus arteriosus (PDA)
has horizontal orientation, making it more obvious on axial images. Lower
level (B) shows thin "positive jet" (arrow) of
contrast media flowing from maximally enhanced aorta to less-opacified
pulmonary artery.
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PDA on MRI
Cardiac MRI has become an invaluable tool for accurate noninvasive
evaluation of cardiovascular anatomy function and shunt-volume calculation. It
allows cardiac imaging in multiple planes without patient exposure to ionizing
radiation or the need for iodinated contrast administration. Cardiac MRI can
clearly depict the connection between the aorta and the left pulmonary artery
just distal to the origin of the left subclavian artery
[5] (Figs.
1F,
1G, and
2E,
2F,
2G).
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Fig. 2E. —49-year-old man evaluated for questionable aortic root
dilatation seen on transthoracic echocardiography. Ao = aorta. AAo= ascending
aorta, DAo = descending aorta, PA = pulmonary artery, LV = left ventricle.
Cardiac MRI steady-state free precession (cardiac MR SSFP) images. In axial
image (E), horizontally oriented PDA (asterisk) is seen as
tubular structure coursing between ascending and descending aorta. Axial image
(F) and coronal image (G) cardiac MR SSFP show blood flow via
the PDA (asterisk) from the aorta to the pulmonary artery causing
dephasing (arrow) within pulmonary artery.
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Fig. 2F. —49-year-old man evaluated for questionable aortic root
dilatation seen on transthoracic echocardiography. Ao = aorta. AAo= ascending
aorta, DAo = descending aorta, PA = pulmonary artery, LV = left ventricle.
Cardiac MRI steady-state free precession (cardiac MR SSFP) images. In axial
image (E), horizontally oriented PDA (asterisk) is seen as
tubular structure coursing between ascending and descending aorta. Axial image
(F) and coronal image (G) cardiac MR SSFP show blood flow via
the PDA (asterisk) from the aorta to the pulmonary artery causing
dephasing (arrow) within pulmonary artery.
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Fig. 2G. —49-year-old man evaluated for questionable aortic root
dilatation seen on transthoracic echocardiography. Ao = aorta. AAo= ascending
aorta, DAo = descending aorta, PA = pulmonary artery, LV = left ventricle.
Cardiac MRI steady-state free precession (cardiac MR SSFP) images. In axial
image (E), horizontally oriented PDA (asterisk) is seen as
tubular structure coursing between ascending and descending aorta. Axial image
(F) and coronal image (G) cardiac MR SSFP show blood flow via
the PDA (asterisk) from the aorta to the pulmonary artery causing
dephasing (arrow) within pulmonary artery.
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Fig. 2H. —49-year-old man evaluated for questionable aortic root
dilatation seen on transthoracic echocardiography. Ao = aorta. AAo= ascending
aorta, DAo = descending aorta, PA = pulmonary artery, LV = left ventricle.
Gadolimium-enhanced MR angiography. 3D volume rendering depicts the AO, PA,
and horizontally oriented PDA (asterisk) connecting them.
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Steady-state free precession (SSFP) sequences can show the dephasing of
blood associated with the flow via a patent PDA (Figs.
1F,
1G,
2F, and
2G). However, SSFP and similar
sequences may cause visual underestimation of the jet visualized, as a result
of their short TEs. In this scenario, cine MRI fast gradient-echo sequences
may accurately show the dephasing jet
[10]. This allows hemodynamic
evaluation of small PDAs. The use of nontraditional off-axis planes or
orthogonal planes may facilitate the precise anatomic delineation of the PDA.
MR angiography volume-rendered 3D models show the anatomic relationships of
the aorta, the pulmonary artery, and the PDA (Figs.
1H and
2H). Velocity-encoded cine MRI
sequences can assess the simultaneous blood flow in the proximal aorta
(QLVSV, left ventricular stroke volume) and in the proximal main
pulmonary artery (QRVSV, right ventricular stroke volume); these
should be approximately equal in the absence of a shunt
[5,
11]. Because the measurements
are taken proximal to the PDA, in the presence of a left-to-right shunt,
QLVSV will equal the QRVSV + Qshunt. The
QLVSV/QRVSV ratio represents the severity of the shunt. Qs
is defined as the QLVSV - Qshunt and Qp is defined
as QRVSV + Qshunt. Therefore, because Qp and
Qs are calculated distal to the shunt, the Qp/Qs ratio
represents the severity of the shunt. At a Qp/Qs ratio greater than
1.7, transcatheter closure using an excluder or surgery is usually warranted
[8]
(Fig. 1I).
References
- Therrien, J. Webb GD. Congenital heart disease in adults. In:
Braunwald E, ed. Heart disease: a textbook of cardiovascular
medicine. Philadelphia, PA: Saunders, 2001:1589
-1621
- Therrien J, Warnes C, Daliento L, et al. Canadian Cardiovascular
Society Consensus Conference 2001 update: recommendations for the management
of adults with congenital heart disease. Part III. Can J
Cardiol 2001;17:1135
-1158[Medline]
- Milne MJ, Sung RY, Fok TF, Crozier IG. Doppler echocardiographic
assessment of shunting via the ductus arteriosus in newborn infants.
Am J Cardiol1989; 64:102
-105[Medline]
- Pennell DJ, Underwood R. Magnetic resonance imaging of the heart.
Br J Hosp Med1993; 49: 90-95,
98-102[Medline]
- Wang ZJ, Reddy GP, Gotway MB, Yeh BM, Higgins CB. Cardiovascular
shunts: MR imaging evaluation. RadioGraphics,2003
[spec no]: S181-S194
- Morgan-Hughes GJ, Marshall AJ, Roobottom C. Morphologic assessment
of patent ductus arteriosus in adults using retrospectively ECG-gated
multidetector CT. AJR2003; 181:749
-754[Abstract/Free Full Text]
- Morgan-Hughes GJ, Villaquiran J, Roobottom CA, Ring NJ, Kuo J,
Marshall AJ. Calcified patent ductus arteriosus diagnosed following aortic
valve replacement. Ann Thorac Surg2003; 76:271
-273[Abstract/Free Full Text]
- Friedman WF, Silverman N. Congenital heart disease in infancy and
childhood. In: Braunwald E, ed. Heart disease: a textbook of
cardiovascular medicine. Philadelphia: Saunders,2001
: 1505-1591
- Kuriyama K, Gamsu G, Stern RG, Cann CE, Herfkens RJ, Brundage BH.
CT-determined pulmonary artery diameters in predicting pulmonary hypertension.
Invest Radiol1984; 19:16
-22[Medline]
- Didier D. Assessment of valve disease: qualitative and
quantitative. Magn Reson Imaging Clin N Am2003; 11: 115-134,
vii[Medline]
- Varaprasathan GA, Araoz PA, Higgins CB, Reddy GP. Quantification of
flow dynamics in congenital heart disease: applications of velocity-encoded
cine MR imaging. RadioGraphics2002; 22:895
-906[Abstract/Free Full Text]
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Abstract
Introduction
