Results
This study enrolled 100 consecutive patients at time of undergoing CT or
MRI of chest as a part of their medical care. Participant
characteristics are described in Table 1. 88% of studies were completed
by an imager with less than 1 year of experience. 2% of study subjects
had sedation or anesthesia prior to echocardiogram, and 6% of study
echocardiograms were reported as challenging or not possible due to
limited acoustic windows.
Successful imaging of the trachea by tracheal sweep was possible in 97%
(95% CI 95 – 100), p < 0.01. Right aortic arch was present
in 4% of patients. There were no diagnoses of double aortic arch. There
were no missed diagnoses of aortic arch anomalies, and the correct
diagnosis of AoA sidedness and absence of DAA was 100% when the trachea
was seen. Right aortic arch was correctly diagnosed in every patient
where present. Kappa coefficient was 0.9. There were 3 tracheal sweeps
that were non-diagnostic with poor acoustic windows: one patient had a
BSA > 2.5 m2 and BMI greater than 40, a
second patient had chronic lung disease and tracheostomy dependence, and
the third had a progressive mediastinal mass. 2 of 3 non-diagnostic
echocardiograms for arch sidedness were performed by an imager with less
than 1 year of experience. Tracheal imaging was possible in patients
with various non-cardiac pathologies including chronic lung disease,
cystic fibrosis, mediastinal masses, and pectus excavatum. It was also
possible in patients with complex cardiac disease including heterotaxy
with hypoplastic left heart syndrome, transposition of the great
arteries, truncus arteriosus, tetralogy of Fallot, complete
atrioventricular canal, absent pulmonary valve, and other concerns for
aortopathy.
Successful imaging of trachea-to-PA relationship could rule out PA sling
in 91% (95% CI 85 – 97), p = 0.12. Excluding 6 patients who had
previous surgical PA intervention, success rate was 97% (95% CI
93-100), p = 0.04. There were no missed diagnoses of PA sling with
correct identification of PA anatomy was made 100% of the time when the
trachea was seen. Kappa coefficient was 1.0. After exclusion of patients
with previous PA surgery, there were 3 studies where tracheal-PA
relationship was non-diagnostic with poor acoustic windows: one patient
was status-post surgical repair of interrupted aortic arch, a second
patient had chronic lung disease, and the third had a progressive
mediastinal mass. All non-diagnostic studies for assessing PA sling were
performed by an imager with less than 1 year of experience.