Cardiac CT Angiography More Sensitive than Transesophageal Echocardiography in Reliably Detecting Patent Foramen Ovale

The objective of a recent study was to evaluate the ability of ECG-gated cardiac CTA to detect patent foramen ovale (PFO) compared with transesophageal echocardiography (TEE).

The study has concluded that gated cardiac CT angiography (CTA) using a 64-MDCT scanner is a feasible method for detecting patent foramen ovale (PFO).

Participants
20 patients who had undergone cardiac CTA and had a previous TEE were included in this retrospective analysis.

Methodology
All CTs were performed with a 64-MDCT scanner. There were three CT criteria for visualizing a PFO:

1. visualization of a “flap” in the left atrium at the expected position of the septum primum;
2. visualization of a continuous “column” of contrast in between the septum primum and septum secundum; and
3. visualization of a “jet” of contrast from this column into the right atrium.

End-diastole axial images were used for image interpretation, as well as 2D multiplanar reformations of these images, particularly coronal oblique projections through the interatrial septum. The TEEs were independently reviewed for the presence of PFO by two cardiologists.

Results of the Study
Six of 20 (30%) patients were found to have a PFO on TEE:

1. On CT, 8 of 20 met criterion 1 or had a “flap” in the left atrium at the expected position of the septum primum;
2. 5 of 20 patients had a “flap” and a continuous “column” of contrast in between the septum primum and septum secundum (criterion 2);
3. and 4 of 20 patients had a “flap” and a continuous “column” of contrast and a “jet” of contrast from this column into the right atrium (criterion 3).

If criteria 2 or 3 were present, criterion 1 was also always present. Utilizing criterion 1 only, all patients who had a PFO on TEE were also identified on CT.

In the 2 patients in which no PFO was seen on TEE but criterion 1 was met on CT, 1 of these patients also had a continuous “column” of contrast. Statistically, using only criterion 1, all six cases of TEE-proven PFO were seen on CT (100% sensitivity).

Twelve of 14 patients were correctly identified as not having a PFO on CT using TEE as the gold standard (86% specificity). Utilizing all three criteria, the sensitivity decreased to 66% and the specificity increased to 100%.

Conclusions
Gated cardiac CTA using a 64-MDCT scanner is a feasible method for detecting PFO.

Reviewer’s Comments
The authors have demonstrated that with careful attention to fine detail, a great deal of cardiac pathology can be gleaned with 64-MDCT.

Author: Vineet R. Jain, MD

Reference
Williamson EE, Kirsch J, et al. ECG-Gated Cardiac CT Angiography Using 64-MDCT for Detection of Patent Foramen Ovale.
AJR Am J Roentgenol; 2008; 190 (April): 929-933: