Download Detection of pulmonary and coronary artery anomalies in tetralogy of

Diagnostic and Interventional Imaging (2016) 97, 543—548
CONTINUING EDUCATION PROGRAM: FOCUS. . .
Detection of pulmonary and coronary artery
anomalies in tetralogy of Fallot using
non-ECG-gated CT angiography
A. Hrusca a, A.L. Rachisan a, P. Gach b, H. Pico b,
C. Sorensen b, B. Bonello c, C. Ovaert c, P. Petit b,
V. Fouilloux c, L. Mace c, G. Gorincour b,∗
a
Department de pédiatrie, université de médicine et pharmacie ‘‘Iuliu Hatieganu’’,
3-5 Crisan rue, Cluj, Napoca, Romania
b
Department d’imagerie pédiatrique, hôpital de La Timone Enfants, 264, rue Saint-Pierre,
13385 Marseille cedex 5, France
c
Department de cardiologie, hôpital de La Timone Enfants, 264, rue Saint-Pierre,
13385 Marseille cedex 5, France
KEYWORDS
Tetralogy of Fallot;
Computed
tomography;
Pulmonary artery;
Coronary artery
∗
Abstract
Objectives: To evaluate the use of non-ECG-gated computed tomography (CT) angiography to
describe pulmonary and coronary defects in patients with tetralogy of Fallot (TOF).
Patients and methods: This retrospective study was carried out on TOF patients having undergone pre-operative non-ECG-gated CT angiography between February 2007 and September 2012.
The following clinical parameters were recorded: mean age at CT angiography, sex, the existence of genetic disease and the need to sedate the patient prior to CT angiography. CT data
were analyzed retrospectively to determine the site(s) of pulmonary stenosis (infundibular,
valvular or arterial), the size of pulmonary arteries and the presence of anomalous coronary
artery courses. CT findings were then compared to the anatomy observed during surgery.
Results: Thirty-five patients were included in the study. The mean age was 4.30 ± 1.91 months
(boys/girls = 17/18). Two patients had associated chromosome disorders (one 22q11 microdeletion and one CHARGE syndrome). Sixteen patients (45.71%) were sedated prior to CT. Pulmonary
artery assessment revealed 24 patients (68.57%) with infundibular stenosis, 5 (17.5%) with
infundibular and/or valvular stenosis, and 6 (21%) with anomalous pulmonary arteries. CT
angiography also evidenced anomalous coronary arteries in 8 patients (22.85%).
Corresponding author.
E-mail address: [email protected] (G. Gorincour).
http://dx.doi.org/10.1016/j.diii.2016.03.010
2211-5684/© 2016 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.
544
A. Hrusca et al.
Conclusion: Due to its reduced scanning time and high spatial resolution, non-ECG-gated CT
angiography is a non-invasive imaging modality that provides accurate information on pulmonary
and coronary artery anatomy in patients with TOF.
© 2016 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.
Congenital heart disease (CHD) affects between 6 and 8 per
1000 live births. Half of these babies only have minor anomalies that do not affect cardiac function, rarely alter their
well-being and only exceptionally require surgical management [1]. Tetralogy of Fallot (TOF) is the most common
cyanotic congenital heart defect; the prevalence of TOF is
3.5-9% [2]. Surgical management of TOF, as well as the age
at which it is carried out, depends on the severity and type
of pulmonary obstruction. Early, complete and single-stage
surgical repair is currently the recommended procedure. It is
advised to perform surgery before the age of 3 to 6 months,
or even earlier in symptomatic cases. A small portion of
infants with more complex defects require multiple surgical procedures, intensive care and careful monitoring [3].
Appropriate surgical management is largely dependent on
detailed characterization of the anatomy of the pulmonary
and coronary arteries. Classically, cardiac catheterization
(CC) was performed to describe morphological defects in
TOF patients [4]. However, due to its reduced scanning time
and very high spatial resolution, computed tomography (CT)
can provide accurate information on the intra- and extracardiac anatomy of patients with TOF [5]. The disadvantage
of CT is that patients are exposed to ionizing radiation.
Therefore, the need to perform multiple CT scans should
be carefully assessed [6]. In the present study, the use of
non-ECG-gated CT angiography to describe pulmonary and
coronary artery anomalies in children with TOF was evaluated and compared with intraoperative findings, the gold
standard for this disease.
Patients and methods
Patients
This retrospective study was carried out on all of the
children with TOF in our database having undergone nonECG-gated CT angiography between February 2007 and
September 2012, prior to surgical repair. Signed consent was
obtained from all the parents of patients included in this
study. The evaluation criteria for these patients were the
mean age at CT, the child’s sex, the existence of an associated genetic disease and the need to sedate the patient
prior to CT.
Computed tomography
During the period covered by the study, all patients with
TOF were scanned using same CT scanner (Definition 64,
SIEMENS, Erlangen, Germany) and the following protocol:
acquisition 64 × 0.6 mm, 80 kV, 100 mAs, rotation time
0.33 s, manual intravenous injection in the arm of iodinated
contrast agent (iobitridol 300 mg/L; Xenetix, Guerbet,
Villepinte, France) at a dose of 2 ml/kg. Owing to the
ventricular septal defect, multi-phase injection protocols
were not possible. The following CT data were assessed:
• the site(s) of pulmonary stenosis (infundibular, valvular or
arterial);
• the size of the pulmonary arteries in mm (infundibulum
and valve measured in the sagittal plane on a multiplanar
reconstruction [MPR] slice, pulmonary arteries measured
at the hila on axial slices);
• the presence of anomalous coronary artery courses.
Pulmonary stenosis sites and coronary artery courses
were analyzed qualitatively under blind conditions and then
compared to the anatomy observed during surgery.
Statistical analysis
Results were expressed as means ± standard deviations. Pulmonary and coronary artery defects, as determined by
CT angiography, were compared and evaluated against
reference surgical findings. Data were analyzed using the
Statistical Package for Social Sciences® (SPSS) 21.0 software
for Windows® .
Results
During the study period, pre-operative non-ECG-gated CT
angiography was performed for 35 children with TOF. The
mean age at CT was 4.30 ± 1.91 months; the ratio of
boys/girls was 17:18. Two patients had associated chromosome disorders: a 6.6-month-old girl with a 22q11
microdeletion and a 8.7-month-old girl with CHARGE syndrome. For 16 patients (45.71%), sedation was necessary
prior to performing CT angiography.
Table 1 provides the CT findings for pulmonary artery
anatomy in our patients. Twenty-four patients (68.57%)
were determined as having infundibular stenosis, 5 patients
(17.5%) were determined as having infundibular and/or
valvular stenosis and 6 patients (21%) showed anomalous
pulmonary arteries. Table 2 shows the diameters measured
for the pulmonary trunk (PT), right pulmonary artery (RPA)
and left pulmonary artery (LPA). Compared with the gold
standard, i.e. surgical findings, the overall precision of CT
angiography for characterizing pulmonary artery anatomy
was 92,1%. The following anomalies were ‘‘missed’’ using
CT angiography: 1 valvular stenosis and 2 LPA stenoses.
Detection of pulmonary and coronary artery anomalies in tetralogy of Fallot
Table 1
545
Comparison of CT and surgical findings for the pulmonary arteries.
Pulmonary artery defect
Surgical findings
CT findings
Infundibular stenosis
Infundibular and/or valvular stenosis
Pulmonary artery stenosis
24
6
8
24
5
6
Table 2 Mean diameters of the pulmonary trunk, right
pulmonary artery (RPA) and left pulmonary artery (LPA)
measured by CT.
Number of
patients
Mean ± SD
PT
RPA
LPA
21
33
31
8.1 ± 2.65
7.08 ± 1.99
7.33 ± 2.27
Anomalous coronary artery courses were identified using
CT angiography in 8 patients (22.85%) which led to an
overall precision of 88.88% (8/9), with only one infundibular artery anomaly observed during surgery that had not
been detected using CT angiography. The following coronary artery anomalies were detected using CT angiography:
infundibular artery arising from the right coronary artery (2
patients), large conus branch arising from the right coronary artery (3 patients; Fig. 1), small conus branch arising
from the right coronary artery (2 patients) and a single right
coronary artery from which arise both the interventricular
artery and the circumflex artery (1 patient).
Discussion
The survival rate of neonates with TOF has increased over
the years with the improvement of diagnostic procedures
Figure 1. 3D volume reconstruction of a 6-month-old patient
showing the circumflex artery (1), a large conus branch of the right
coronary artery (2) and the left anterior descending artery (3) arising from the left coronary artery.
and the care of patients with CHDs. According to the latest
reports, surgical repair of TOF—generally performed during the first year of life—is successful in 98% of infants.
Diagnostic imaging findings provide key information, such as
anatomical data and hemodynamic indices, prior to repair
surgery for patients with TOF. With the improved spatial and
temporal resolution of multidetector CT, and its capacity to
produce static as well as 3D reconstructed images of the
heart and main vessels, this imaging modality is now one of
the main techniques used to assess the anatomy of patients
with TOF [7].
More than 10% of patients with TOF display central
or peripheral pulmonary artery stenosis. CT can be used
to visualize in detail pulmonary artery patency or pulmonary atresia in more severe cases of TOF [8—12]. Our
study confirms the accuracy of CT angiography for detecting pulmonary artery defects in patients with TOF because
even though three valvular/arterial anomalies were missed,
these defects were not considered as crucial for planning surgery. In addition, it has been shown that a slight
kinking where the ductus arteriosus used to insert can
cause stenosis to be underestimated. For children with
TOF, CT angiography therefore represents a less invasive
pre-operative imaging option than conventional angiography due to the good distribution of contrast agent within
the viable segment of the pulmonary arteries, distal to the
site of hypoplasia/atresia [13]. The existence, confluence,
patency and size of the pulmonary arteries can be clearly
described using CT angiography [14]. Similarly to magnetic resonance imaging, ECG-gated CT angiography with
dedicated dynamic-mode multi-phase reconstruction could
demonstrate the dynamic nature of stenosis, but patients
would be exposed to a higher level of radiation [15,16].
The present study shows that non-ECG-gated CT angiography, which exposes the patient to less radiation, performs
well for detecting pulmonary artery defects. In addition,
the impact of the size of the pulmonary arteries on surgical management is subject to debate. For patients with
TOF, one should bear in mind that the pulmonary arteries
are under filled and that their real size remains unknown,
whatever the imaging technique used [17]. Nonetheless,
it is still crucial to characterize pulmonary artery morphology in patients with TOF. Similarly to the results
reported by Ling et al. [12], CT assessment resulted in the
accurate detection of pulmonary artery defects in 92.1%
of cases. This is close to the accuracy achieved using
CC [18]. Nevertheless, although CC can provide hemodynamic data and useful vascular access for dilatation
or embolization, it is rarely used in children because of
the increased risk of vascular damage, hemorrhage and
infection [19].
The increased incidence (11%) of anomalous coronary
arteries in patients with CHDs has been reported previously
546
[20]. Such anomalies of the coronary arteries are usually
detected during catheterization. The precise course of such
anomalous arteries can be difficult to determine in patients
with complex CHDs [21,22]. The incidence of coronary artery
anomalies is 5—12% in patients with TOF. Our results demonstrate how accurately these anomalies can be diagnosed
(accuracy = 90%) using CT angiography. Both knowing the origin and the course of coronary arteries are important for
planning surgery. Even when not ECG-gated, 16-slice multidetector CT scans have been reported to provide good views
of the proximal coronary artery [23].
The main limitation of ECG-gated CT angiography is the
amount of ionizing radiation given to the patient. However, the benefits of this non-invasive diagnostic modality
outweigh the potential risks associated with radiation. It
is notably used for assessing coronary damage in adults
and acquired lesions (i.e. Kawasaki’s disease) in children
[24] when the entire coronary artery courses, even the
most distal segments, need to be visualized [25,26]. For
children with TOF, only the origins and proximal segments
need to be visualized [27]. Hence, we here confirm our
hypothesis concerning the suitability of non-ECG-gated CT
angiography for pre-operative assessment in patients with
TOF.
Most CHDs are not associated with a syndrome. The syndromes the most frequently associated with CHDs is Down
syndrome [28], followed by Turner syndrome. In our study,
two patients had an associated syndrome; one had CHARGE
syndrome and other a 22q11.2 deletion. 22q11.2 microdeletions are found in approximately 2% of patients with CHDs
and more specifically in more than 50% of patients with
conotruncal heart defects [29]. The genetic factors, specific embryonic mechanisms and cellular features involved
can determine the type of heart defect developed by these
patients [30,31]. Hence, being aware of the existence of
certain syndromes may be a helpful guide when assessing
such patients using CT [32]. For example, patients with TOF,
pulmonary atresia and 22q11 deletions are more likely to
develop other specific anomalies of the pulmonary arteries
[33].
The main limitations of our study are the limited number of patients included and its retrospective nature. In
addition, some patients with CHDs can present developmental anomalies that are particularly difficult to assess
except using ECG-gated CT angiography or selective coronary angiography [33,34]. Another study is underway in our
department comparing the diagnostic accuracy and dose of
after ionizing radiation used during ECG-gated CT angiography and non-ECG-gated CT angiography for patients with
TOF.
A. Hrusca et al.
Take-home messages
• Tetralogy of Fallot (TOF) is the most common of all
cyanotic congenital heart diseases (CHDs).
• Appropriate surgical management of TOF is largely
dependent on detailed characterization of the
anatomy of the pulmonary and coronary arteries.
• Multidetector CT scanning is one of the imaging
modalities used to assess patients with TOF.
• The main limitation of CT is the amount of ionizing
radiation the patient is exposed to.
Clinical case
A baby girl aged 9 months, known to have tetralogy of Fallot associated with duodenal stenosis, annular pancreas,
choanal stenosis and dysmorphic features diagnosed as
CHARGE syndrome.
She was brought to the hospital for pre-operative assessment (pulmonary and coronary arteries).
CT scanning was performed under sedation, using helical acquisition with injection in the arterial phase without
cardiac gating.
CT scans show atrial and visceral situs solitus, a right bulboventricular loop with a dextro-positioned aorta consistent
with TOF. The scans show atrioventricular and ventriculoarterial concordance (SDS). The aortic arch is straight and
divides into four supra-aortic trunks. No anomalies of the
pulmonary or systemic venous return are observed; no pleural or cardiac effusion is observed. Stenosis appears to be
mostly sub-valvular and valvular. The pulmonary branches
appear to be satisfactory with a RPA measuring 8 mm and
a LPA measuring 10 mm at the hila. The venticular septal
defect and right ventricle hypertrophy typically observed
in TOF are visible. Coronary artery assessment reveals the
existence of a single coronary artery (Fig. 2).
Conclusion
Due to its reduced scanning time, high spatial resolution,
and the low dose of ionizing radiation needed, non-invasive
non-ECG-gated CT angiography is sufficient to provide accurate information on pulmonary and coronary artery anatomy
in patients with TOF [35]. It therefore represents a reasonable imaging alternative for the pre-operative assessment
of such patients. Larger-scale prospective studies need to
be carried out to support our findings.
Figure 2. 3D volume reconstruction showing a single coronary
artery (arrow).
Detection of pulmonary and coronary artery anomalies in tetralogy of Fallot
Questions
1) Which two syndromes are most frequently associated
with tetralogy of Fallot?
A - VACTERL (vertebral anomalies, anal atresia, cardiac defects, tracheoesophageal fistula and/or
esophageal atresia, renal and radial anomalies and
limb defects);
B - CHARGE (coloboma, heart defects 75%, atresia of the
nasal choanae, retardation of growth and/or mental
development, genital abnormalities and ear abnormalities);
C - Pentalogy of Cantrell (midline abnormalities);
D - Alagille (biliary tract hypoplasia);
E - DI GEORGE.
2) What are the most frequently observed heart defects in
patients with tetralogy of Fallot?
A - Right-sided aortic arch;
B - Anomalous coronary arteries;
C - Left superior vena cava;
D - Multiples ventricular septal defects;
E - Various defects: TAPVC, Ebstein’s anomaly, double
aortic arch, aortic valve anomaly.
3) Which of the following CHDs is the most common?
A - Transposition of the great vessels;
B - Ventricular inversion;
C - Tetralogy of Fallot;
D - Coarctation of the aorta;
E - Pulmonary atresia with ventricular septal defect.
Answers
A) Answers A and B. The most common underlying genetic
anomalies are: 22q11, 8p23, and 6q microdeletions, and
trisomy 21, 18 or 13.
B) A in 25% of patients, B in 10% of patients (with
either anomalous branches crossing the infundibulum, an
anomalous origin of the LAD from the RCA or right sinus,
an accessory LAD, or a single (right of left) coronary
ostium), and C in 8% of patients.
C) Answer C.
Disclosure of interest
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[9]
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[12]
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[15]
[16]
[17]
[18]
[19]
[20]
The authors declare that they have no competing interest.
[21]
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