DOI:10.2214/AJR.07.3430
AJR 2009; 192:259-266
© American Roentgen Ray Society
Cardiac MRI and Pulmonary MR Angiography of Sinus Venosus Defect and Partial Anomalous Pulmonary Venous Connection in Cause of Right Undiagnosed Ventricular Enlargement
Henryk Kafka1,2,3,4 and
Raad H. Mohiaddin1,3
1 Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London,
United Kingdom.
2 Adult Congenital Heart Centre, Royal Brompton Hospital, London, United
Kingdom.
3 National Heart and Lung Institute, Imperial College, London, United
Kingdom.
4 Department of Radiology, Division of Cardiology, Queen's University
Cardiovascular Laboratory, Kingston General Hospital, 76 Stuart St., Kingston,
ON K7L 2V7, Canada.
Received November 11, 2007;
accepted after revision July 1, 2008.
H. Kafka is a Detweiler Fellow of the Royal College of Physicians and
Surgeons of Canada and has received funding support from the Department of
Medicine at Queen's University, Kingston, ON, Canada.
Address correspondence to H. Kafka
(kafkamd{at}usa.net).
FOR YOUR INFORMATION
A data supplement for this article can be viewed in the online version of
the article at:
www.ajronline.org.
Abstract
OBJECTIVE. Patients may be referred for cardiology assessment
because of an enlarged right ventricle (RV) with no cause apparent on
echocardiography. Cardiac MRI can contribute to the management of these
patients by detecting sinus venosus defect or partial anomalous pulmonary
venous connection (PAPVC). We sought to show how often sinus venosus defect or
PAPVC was detected on MRI in patients with an enlarged RV without a previously
established definite diagnosis.
MATERIALS AND METHODS. First cardiac MRI scans obtained over a
4-year period in adults with an undiagnosed cause of RV enlargement were
searched for the MRI diagnosis of sinus venosus defect or PAPVC.
RESULTS. Thirty-seven patients (25 female, 12 male) met the study
criteria. Nineteen patients had a cardiac MRI diagnosis of sinus venosus
defect, with PAPVC being present in 95% of those patients. All PAPVCs
associated with sinus venosus defect were from the right side. Eleven of the
19 patients with sinus venosus defect underwent surgery at our institution.
Sinus venosus defect was confirmed in all 11 cases. Of the 37 patients, 36 had
PAPVC, which was right-sided in 27 patients (75%), left-sided in seven
patients (19.4%), and bilateral in two patients (5.6%). Three patients had
scimitar veins. The common defects associated with PAPVC were sinus venosus
defect in 18 patients (50%) and secundum atrial septal defect in six patients
(17%).
CONCLUSION. This article about cardiac MRI in adults with sinus
venosus defect and PAPVC shows that cardiac MRI can reliably detect and
quantify these lesions when other methods have not provided a complete
diagnosis for the cause of right heart enlargement.
Keywords: congenital heart disease MR angiography MRI partial anomalous pulmonary venous connection sinus venosus defect
Introduction
Most adult patients with an enlarged right ventricle (RV) detected
on transthoracic echocardiography (TTE) will have readily apparent causes,
such as an atrial septal defect (ASD). But there are situations in which no
definite cause of enlarged RV is revealed on TTE. Before a diagnosis of RV
cardiomyopathy or primary pulmonary hypertension is made, other less apparent
causes [1,
2] must be considered, such as
sinus venosus defect or partial anomalous pulmonary venous connection (PAPVC).
Although TTE has not been very good at revealing these anomalies
[3], good detection rates
[4,
5] have been reported for
transesophageal echocardiography (TEE). Despite the use of TEE, there are
patients in whom the cause of RV enlargement remains unexplained or
incompletely explained. Cardiac MRI has been successfully used in patients
with intracardiac and extracardiac shunts
[6-11],
but to our knowledge there have been no systematic analyses of cardiac MRI for
the detection and quantification of sinus venosus defect in the adult. In this
study, we sought to show that cardiac MRI plays an important role in the
detection of sinus venosus defect and PAPVC in the adult patient for whom
other investigations have not provided a complete explanation for an enlarged
RV.
Materials and Methods
Subject Selection
All first cardiac MRI scans in patients with an enlarged RV obtained
between June 2002 and May 2006 were reviewed, searching for a cardiac MRI
diagnosis of sinus venosus defect or PAPVC. The study group of 37 patients
included only those subjects in whom there had been no definite complete
diagnosis before cardiac MRI. The cardiac MRI scans were reviewed and
conclusions confirmed using the criteria outlined in the following text. Notes
regarding previous investigations, as well as operative notes for surgery at
our institution, were reviewed.

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Fig. 1A —23-year-old woman with partial anomalous pulmonary venous
connections. Phase images of through-plane velocity maps for quantifying flow
in pulmonary artery and aorta in this patient with two anomalous right
pulmonary venous connections and secundum atrial septum defect (patient 37).
PA = pulmonary artery, Ao = aorta.
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Fig. 1B —23-year-old woman with partial anomalous pulmonary venous
connections. Phase images of through-plane velocity maps for quantifying flow
in pulmonary artery and aorta in this patient with two anomalous right
pulmonary venous connections and secundum atrial septum defect (patient 37).
PA = pulmonary artery, Ao = aorta.
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Fig. 1C —23-year-old woman with partial anomalous pulmonary venous
connections. Velocity-versus-time curves for blood flow in aorta and pulmonary
artery. Qp/Qs = pulmonary-to-systemic blood flow ratio.
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Cardiac MRI and Contrast-Enhanced MR Angiography
Cardiac MRI was performed using a Sonata 1.5-T or an Avanto 1.5-T scanner
(both by Siemens Medical Solutions). Multislice single-shot spinecho images
using HASTE were obtained in three orthogonal planes to define the cardiac
anatomy. In some patients, steady-state free precession (SSFP) multislice
images were also obtained to improve definition of the blood-tissue borders.
Turbo spin-echo imaging was often undertaken to delineate the edges of the
sinus venosus defect. Ventricular volumes, ventricular mass, and systolic
function were calculated using a stack of short-axis ECG-gated cine images.
Cine phasecontrast velocity flow maps were obtained in accordance with
established protocols and practice
[12] to better detect the
anomalous flow patterns and to calculate the pulmonary-to-systemic (Qp/Qs)
blood flow ratio (Figs. 1A,
1B, and
1C and
Table 1). Contrast-enhanced MR
angiography (CE-MRA) was also performed in some patients. The decision to
perform CE-MRA was made by the individual performing the scanning. In those
cases, the coronal orientation was used during breath-hold at end-inspiration
before and after the IV administration of gadopentetate dimeglumine
(Magnevist, Schering) [11].
The bolus was timed to the arrival of the contrast agent in the ascending
aorta. Imaging parameters are summarized in
Table 2.
Specific scanning techniques used for sinus venosus
defect—Sinus venosus defect is not a defect of the atrial septum.
Rather, the mouth of the caval vein, usually the superior vena cava (SVC), has
biatrial connections [1,
2] overriding the rim of the
oval fossa, producing an extraseptal interatrial communication. It is this
overriding of the caval vein across the atrial septum that forms the basis for
the imaging diagnosis of the sinus venosus defect
[1,
2]. Therefore, the preferred
views for the sinus venosus defect are the transverse and sagittal planes that
are perpendicular to the border between the SVC and the left atrium. SSFP cine
imaging in these planes produces better delineation of blood-tissue borders
(Figs. 2A, and
2B). Cine phase-contrast
velocity flow mapping can high-light the location and size of the sinus
venosus defect (Figs. 3A,
3B,
3C,
3D,
3E, and
3F and Fig. S3, AVI cine
images, in supplemental data at
www.ajronline.org).

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Fig. 2A —44-year-old man with sinus venosus defect. Transverse steady-state
free precession cine frame (A) shows sinus venosus defect
(arrow) between superior vena cava (asterisk) and left
atrium (LA). Superior nature of this defect and absence of an upper rim of
defect are evident in sagittal image (B). Ao = aorta, PA = pulmonary
artery, RPA = right pulmonary artery, RA = right atrium.
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Fig. 2B —44-year-old man with sinus venosus defect. Transverse steady-state
free precession cine frame (A) shows sinus venosus defect
(arrow) between superior vena cava (asterisk) and left
atrium (LA). Superior nature of this defect and absence of an upper rim of
defect are evident in sagittal image (B). Ao = aorta, PA = pulmonary
artery, RPA = right pulmonary artery, RA = right atrium.
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Fig. 3A —Velocity flow mapping in three patients with sinus venosus defect.
(See also Figs. S3A-S3F in supplemental data at
www.ajronline.org).
Transverse images in 32-year-old man with sinus venosus defect (patient 24).
Steady-state free precession cine image (A) shows sinus venosus defect
(black arrow) between left atrium (LA) and superior vena cava (SVC)
(asterisk). Corresponding in-plane velocity flow map (B) shows
dark inflow from pulmonary vein (white arrow) into LA crossing sinus
venosus defect and entering SVC.
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Fig. 3B —Velocity flow mapping in three patients with sinus venosus defect.
(See also Figs. S3A-S3F in supplemental data at
www.ajronline.org).
Transverse images in 32-year-old man with sinus venosus defect (patient 24).
Steady-state free precession cine image (A) shows sinus venosus defect
(black arrow) between left atrium (LA) and superior vena cava (SVC)
(asterisk). Corresponding in-plane velocity flow map (B) shows
dark inflow from pulmonary vein (white arrow) into LA crossing sinus
venosus defect and entering SVC.
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Fig. 3C —Velocity flow mapping in three patients with sinus venosus defect.
(See also Figs. S3A-S3F in supplemental data at
www.ajronline.org).
Sagittal images in 35-year-old woman with sinus venosus defect (patient 4).
Steady-state free precession cine frame (C) shows superior nature of
sinus venosus defect (arrow) between LA and SVC (asterisk).
Corresponding in-plane velocity flow map (D) shows dark inflow from LA
across sinus venosus defect (arrow) into right atrium (RA).
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Fig. 3D —Velocity flow mapping in three patients with sinus venosus defect.
(See also Figs. S3A-S3F in supplemental data at
www.ajronline.org).
Sagittal images in 35-year-old woman with sinus venosus defect (patient 4).
Steady-state free precession cine frame (C) shows superior nature of
sinus venosus defect (arrow) between LA and SVC (asterisk).
Corresponding in-plane velocity flow map (D) shows dark inflow from LA
across sinus venosus defect (arrow) into right atrium (RA).
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Fig. 3E —Velocity flow mapping in three patients with sinus venosus defect.
(See also Figs. S3A-S3F in supplemental data at
www.ajronline.org).
Coronal images in 18-year-old woman with sinus venosus defect (patient 20).
FLASH image (E) shows bright flow disturbance in SVC
(asterisk) related to flow through sinus venosus defect.
Through-plane velocity flow map (F) in same position as Eshows
sinus venosus defect as dark region of flow (arrow) from LA. Ao =
aorta.
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Fig. 3F —Velocity flow mapping in three patients with sinus venosus defect.
(See also Figs. S3A-S3F in supplemental data at
www.ajronline.org).
Coronal images in 18-year-old woman with sinus venosus defect (patient 20).
FLASH image (E) shows bright flow disturbance in SVC
(asterisk) related to flow through sinus venosus defect.
Through-plane velocity flow map (F) in same position as Eshows
sinus venosus defect as dark region of flow (arrow) from LA. Ao =
aorta.
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Specific scanning techniques used for PAPVC— The anomalous
connection of a right pulmonary vein can be to the right atrium (RA), the SVC,
the SVC-RA junction, or, less commonly, the inferior vena cava (IVC).
Transverse imaging is best suited to detect these connections because that
plane allows cross-sectional visualization of the caval veins and the RA
(Figs. 4A,
4B,
4C, and
4D). Flow from the pulmonary
vein into the RA can be confirmed with cine phase-contrast velocity flow
mapping (Figs. 5A,
5B,
5C, and
5D). The most common left
anomalous venous connection is that of the left upper pulmonary vein to a
vertical vein that drains up to the brachio cephalic vein and from there to
the SVC (Figs. 6A,
6B, and
6C). CE-MRA (Figs.
6A,
6B, and
6C) has been suggested for
better definition of both right and left anomalous connections
[9-11].

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Fig. 4A —46-year-old woman with partial anomalous pulmonary venous connection
and sinus venosus defect. LA = left atrium, asterisk indicates superior vena
cava (SVC). Turbo spin-echo image shows connection of right upper pulmonary
vein (arrow) to SVC.
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Fig. 4B —46-year-old woman with partial anomalous pulmonary venous connection
and sinus venosus defect. LA = left atrium, asterisk indicates superior vena
cava (SVC). Slice 20 mm caudad to A clearly shows sinus venosus defect
(arrow).
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Fig. 4C —46-year-old woman with partial anomalous pulmonary venous connection
and sinus venosus defect. LA = left atrium, asterisk indicates superior vena
cava (SVC). Steady-state free precession cine still images at same levels as
Aand Balso show sinus venosus defect (arrow, D).
Arrow in C indicates anomalous connection of upper pulmonary vein to
SVC.
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Fig. 4D —46-year-old woman with partial anomalous pulmonary venous connection
and sinus venosus defect. LA = left atrium, asterisk indicates superior vena
cava (SVC). Steady-state free precession cine still images at same levels as
Aand Balso show sinus venosus defect (arrow, D).
Arrow in C indicates anomalous connection of upper pulmonary vein to
SVC.
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Fig. 5A —57-year-old man with sinus venosus defect and right partial
anomalous pulmonary venous connection. LA = left atrium, RA = right atrium,
RPA = right pulmonary artery, RV = right ventricle. Oblique axial steady-state
free precession cine image (A) shows anomalous connection of right
upper pulmonary vein (arrowhead). Sinus venosus defect
(arrow) is also evident at this level. Bright white signal in this
velocity flow map (B) confirms flow from pulmonary vein into RA.
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Fig. 5B —57-year-old man with sinus venosus defect and right partial
anomalous pulmonary venous connection. LA = left atrium, RA = right atrium,
RPA = right pulmonary artery, RV = right ventricle. Oblique axial steady-state
free precession cine image (A) shows anomalous connection of right
upper pulmonary vein (arrowhead). Sinus venosus defect
(arrow) is also evident at this level. Bright white signal in this
velocity flow map (B) confirms flow from pulmonary vein into RA.
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Fig. 5C —57-year-old man with sinus venosus defect and right partial
anomalous pulmonary venous connection. LA = left atrium, RA = right atrium,
RPA = right pulmonary artery, RV = right ventricle. Coronal steady-state free
precession cine image shows connection of right pulmonary vein to RA-superior
vena cava junction (arrowhead).
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Fig. 5D —57-year-old man with sinus venosus defect and right partial
anomalous pulmonary venous connection. LA = left atrium, RA = right atrium,
RPA = right pulmonary artery, RV = right ventricle. Dark signal in this
velocity flow map shows flow (arrowhead) from anomalous pulmonary
vein into RA.
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Fig. 6A —Contrast-enhanced MR angiography maximum-intensity-projection
coronal images in three patients with partial anomalous pulmonary venous
connection. Ao = aorta, RA = right atrium. 18-year-old woman with anomalous
connection of right pulmonary vein (arrow) to superior vena cava
(SVC) (asterisk). PA = pulmonary artery.
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Fig. 6B —Contrast-enhanced MR angiography maximum-intensity-projection
coronal images in three patients with partial anomalous pulmonary venous
connection. Ao = aorta, RA = right atrium. 63-year-old woman with anomalous
connection of left upper pulmonary vein to vertical vein (arrow) that
drains into brachiocephalic vein (BV) and from there into SVC
(asterisk). RPA = right pulmonary artery.
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Fig. 6C —Contrast-enhanced MR angiography maximum-intensity-projection
coronal images in three patients with partial anomalous pulmonary venous
connection. Ao = aorta, RA = right atrium. 45-year-old woman with anomalous
scimitar vein. Image shows that all right pulmonary veins are connected to an
anomalous vein (arrow) that, in turn, drains into inferior vena cava
(IVC).
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Results
A total of 37 patients (25 female, 12 male; age range, 16-75 years; median
age, 40 years) met the criteria for inclusion
(Table 1). Twenty-five of the
37 had been referred for cardiac MRI by cardiologists from outside our
institution. All 37 had undergone TTE at the referring center before cardiac
MRI. The indications for TTE were dyspnea in 18, murmur in eight, palpitation
or rhythm disorder in five, chest discomfort in one, and an abnormal chest
radiograph in one. One patient was being followed up after previous repair of
a tetralogy of Fallot, and in three patients the reason for the initial
echocardiogram was not apparent from the notes. The findings before referral
are summarized in Table 1.
Sinus Venosus Defect
A total of 19 patients (10 female, nine male) had a cardiac MRI diagnosis
of sinus venosus defect. Qp/Qs ranged from 1.5 to 4. Of these 19 patients with
sinus venosus defect, 18 (95%) had the associated finding of PAPVC. These 18
patients had a total of 30 anomalous pulmonary venous connections (1.6 per
patient), all from the right side. No patient had a left-sided PAPVC or
scimitar vein associated with the sinus venosus defect. Two patients with
sinus venosus defect also had secundum ASD.
Of the 19 patients with sinus venosus defect, 11 have since undergone
surgery at our institution (Table
3). The sinus venosus defect was confirmed in all 11 cases, as
were all associated PAPVCs identified on cardiac MRI. At surgery, no other
anomalous veins in addition to those documented on MRI were found. In the one
case with a sinus venosus defect (patient 12) for which no PAPVC was
identified on MRI, no anomalous vein was seen at surgery. The two secundum
ASDs that had been diagnosed in addition to the sinus venosus defect were
confirmed at surgery.
All 19 patients with sinus venosus defect had undergone TTE before referral
for cardiac MRI, and 11 had also undergone TEE. No patient had sinus venosus
defect diagnosed on TTE before referral. In four cases, TEE had detected a
sinus venosus defect or a possible sinus venosus defect and in those cases
cardiac MRI had been requested to confirm a sinus venosus defect and to search
for a possible PAPVC. In six additional patients, TTE or TEE had reported ASD
or possible ASD, including one primum defect. In only one of these patients
did cardiac MRI actually find an ASD in addition to the sinus venosus
defect.
Partial Anomalous Pulmonary Venous Connection
A total of 60 anomalous pulmonary venous connections were shown in 36
patients. Anomalous connections were right-sided in 27 patients (75%),
left-sided in seven (19.4%), and bilateral in two (5.6%). The patients with
right-sided connections included three with scimitar veins
[13,
14]. A single anomalous
pulmonary vein connection was seen in 18 patients (50%), two anomalous
connections in 12 (33.3%), and three in six patients (16.6%). Of the 60
abnormal connections, 31 (51.7%) were to the SVC, four (6.7%) were to the
SVC-RA junction, 10 (16.6%) were to the RA, six (10%) were to the IVC, and
nine (15%) were to a vertical vein on the left that communicated with the
brachiocephalic vein. The most common associated defect was sinus venosus
defect in 18 (50%) of these patients. Secundum ASD was present in six
patients, including two who already had a sinus venosus defect. An intact
septum was present in 14 patients (38.8%), including eight of the nine
patients with a left connection and all three patients with a scimitar
vein.
Twenty of these 36 patients with PAPVC underwent CE-MRA as part of their
cardiac MRI examination. Although CE-MRA did provide clear delineation of the
anomalous vessels and their distal aspects (Figs.
6A,
6B, and
6C), CE-MRA did not reveal any
new anomalous vessels that had not already been identified on the unenhanced
tomographic still and cine cardiac MRI.
Of the patients with PAPVC, 13 have undergone surgery at our institution,
two with bilateral PAPVC and 11 with right PAPVC. At surgery, all the cardiac
MRI findings were confirmed in 12 patients
(Table 3); but in patient 6,
although the secundum ASD was confirmed, the anomalous vein was not confirmed.
No additional anomalous veins were identified at surgery in any of the
patients.
All 36 patients with PAPVC had undergone TTE and 15 had undergone TEE
before cardiac MRI. In patient 1, TTE correctly diagnosed an anomalous left
pulmonary vein connection. In patient 4, TTE suggested a possible anomalous
right vein that was confirmed at cardiac MRI. In patient 17, a possible
anomalous left pulmonary vein was suggested by TTE and subsequently seen on
cardiac MRI, but the anomalous right vein in the same patient was not detected
on TTE. In the 15 patients undergoing TEE, TEE had not identified the 14
patients with anomalous right pulmonary veins or the one patient with an
anomalous left pulmonary vein.
Discussion
Sinus Venosus Defects
Sinus venosus defects are uncommon and their clinical recognition has been
difficult [3], with only 12% of
sinus venosus defects confidently diagnosed on TTE
[4]. Using a combination of
TTE, TEE, and cardiac catheterization in a largely pediatric study of 16
patients, sinus venosus defect was confidently diagnosed in only one patient,
was suspected in seven, and was not suspected in eight patients before the
cardiac MRI examination that clearly imaged the sinus venosus defect in all
the patients [15]. The most
consistent TTE finding in patients with sinus venosus defect has been RV
enlargement [4], and that was
the case in our series, with RV dilatation in all 19 patients with sinus
venosus defect. In the past, it has been this RV dilatation that has prompted
the use of special TTE views
[3] or referral for TEE
[4]. Sinus venosus defect can
have important long-term hemodynamic consequences, but early detection and
surgical treatment are associated with low morbidity and mortality rates, with
survival similar to that of a matched population
[16].
TEE has been reported to be accurate for the detection of sinus venosus
defect [4]. In our series, of
the 11 patients with sinus venosus defect who had undergone TEE, it is not
clear why TEE had detected the sinus venosus defect, or possible sinus venosus
defect, in only four of the 11 patients. A previous smaller retrospective
study noted that TEE missed a sinus venosus defect in two of the nine patients
with sinus venosus defect documented on cardiac MRI
[9]. CT has been used to detect
sinus venosus defect [17], but
it does not provide the same functional and flow information as cardiac
MRI.
Partial Anomalous Pulmonary Venous Connection
A retrospective series of TEE in 43 adults established TEE as a reliable
tool to detect PAPVC [5]. Of
those 43 patients, 81% had right-sided anomalous veins. A retrospective CT
study of 29 adults described a surprising predilection for left-sided
anomalous veins, with 79% having left-sided veins
[18], and speculated that CT
may underreport right-sided veins because the anomalous right upper lobe vein
is subtle on both contrast-enhanced and unenhanced CT
[18]. MDCT has been proposed
as a better technique to visualize anomalous pulmonary veins, with the
advantage of shorter scanning times that would be of special importance for
children and for patients with claustrophobia
[19]. Both ECG-gated and
nongated studies have been used
[17-19].
MDCT does have the ongoing concerns about iodine-based contrast material and
the risks associated with the radiation dose
[20].
Cardiac MRI has been successful in the detection of PAPVC
[7,
8]. In our series, the
distribution of right-sided to left-sided lesions was similar to that reported
in TEE studies [5]. Not only
can cardiac MRI detect the extracardiac anomalous vessels without the need for
radiation, it can also clearly delineate the intracardiac anatomy, especially
the presence of sinus venosus defect
[6,
15]. Furthermore, velocity
flow mapping allows accurate assessment of the Qp/Qs without the need for, or
the risk associated with, cardiac catheterization
[21].
In patient 6, cardiac MRI diagnosed a large secundum defect, without a
posterior rim, as well as an anomalous connection of the right upper PV. At
surgery, the secundum ASD was confirmed, but the surgeon reported that no true
anomalous connection of the right veins to the RA was seen. In 1957, Bedford
et al. [22] commented on
"large fossa ovalis defects in which the posterior rim is lacking or
rudimentary, so that the right pulmonary veins communicate virtually with both
atria," labeling such cases as having pseudoanomalous right pulmonary
veins.
In studies of TEE for PAPVC diagnosis, undetected anomalous veins have been
reported at surgery [4,
5]. In one study, in addition
to the 37 veins identified with TEE, another 10 veins were found at surgery.
These were right-sided and connected to the upper SVC
[4]. No anomalous veins not
detected by cardiac MRI were identified at surgery in our study or in the
report by Valente et al. [15].
This is probably due to the large field of view of cardiac MRI that allows the
complete imaging of the full extent of the SVC.
The use of CE-MRA in these patients with PAPVC has been advocated as a way
to improve diagnosis and reduce the patient's time in the scanner
[9-11].
However, recent concerns about complications associated with gadolinium
contrast agents have led to recommendations that "other imaging
techniques that do not require the administration of gadolinium should be
taken into consideration" for at-risk patients
[23]. In the 20 patients who
underwent CE-MRA in addition to 2D scanning, we observed that the diagnosis of
PAPVC could have been made from the 2D images alone. It must be kept in mind
that these were retrospective nonblinded observations, but they do suggest
that 2D cardiac MRI can be as accurate for the diagnosis and localization of
PAPVC as CE-MRA.
Limitations
We have reported a highly selected group, and these results cannot be used
to assess the frequency of PAPVC or sinus venosus defect. No conclusion can be
drawn about the accuracy of TTE or TEE because we scanned only those patients
in whom a conclusive diagnosis had not been made. We did not scan every
patient with a dilated RV who underwent echocardiography. Although we can
state that a cardiac MRI diagnosis of sinus venosus defect or PAPVC is quite
likely to be correct, no comment can be made about the ability of CE-MRA to
rule out sinus venosus defect or PAPVC because no patient with a normal scan
was sent for surgical confirmation.
In conclusion, cardiac MRI can reliably detect, delineate, and quantify
sinus venosus defect and PAPVC in patients for whom other methods have not
provided a diagnosis for the cause of right heart dilatation and can do so
without the need for gadolinium contrast agents. As a result, we recommend
that cardiac MRI be performed when sinus venosus defect or PAPVC is suspected
on echocardiography or clinically and in the case of patients with RV
dilatation for whom no cause has been determined by other diagnostic means.
The performance of cardiac MRI should be carefully considered before making a
final diagnosis of idiopathic pulmonary hypertension or RV cardiomyopathy.
Acknowledgments
We thank Siew Yen Ho and Hideki Uemura for their expert advice on anatomic
and surgical issues involved in sinus venosus defects.
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