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64-MDCT Effective for Evaluating Aortic Valve Area

December 16, 2008
Written by: , Filed in: Cardiac Imaging
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A recent study was conducted to evaluate how measurement of the aortic valve
area (AVA) on gated 64-MDCT compares with that obtained by transesophageal
echocardiography (TEE).

The aortic valve area, as obtained on 64-MDCT with retrospective gating,
strongly correlates with that of echocardiography, and has a high sensitivity
and specificity for detecting severe aortic stenosis.

Design
Retrospective review.

Participants
80 patients who had a clinical diagnosis of aortic stenosis, and had both a CT
and TEE within three months of each other.

Methodology
CTs were performed on a 64-MDCT scanner using iodinated contrast and
retrospective ECG gating. The reconstructed slice thickness was 1.25 mm. The
aortic valve was evaluated with multiplanar reformatted images of the aortic
root. On a sagittal plane, the aortic valve was centered, and then a
reformatting plane was used to generate a paracoronal oblique long-axis view
of the aortic root, aortic valve, and left ventricular outflow tract.

Another reformatting plane was used to make a double-oblique short-axis view
of the aortic valve. These short-axis views were evaluated in all phases of
the cardiac cycle. The AVA was measured on the image that best showed the
maximum valve opening in mid-left ventricular systole.

The aortic valve area was measured using planimetry in which the area of
contrast between the aortic valve leaflets excluding calcifications was
measured. In addition, aortic valve calcifications were graded on a 4-point
scale in which 0 equaled no calcification and 4 equaled severe calcifications.
On TEE, the AVA was obtained by measuring the smallest valve orifice area
during mid-systole using a short-axis view of the aortic valve. Patients with
a left ventricular ejection fraction <50% on TEE were excluded from analysis of detection of moderate and severe aortic stenosis. [text_ad] Results
The median AVA on TEE was 0.7 ± 0.9 cm2. There was strong correlation of AVA
between CT and TEE (n=63; r=0.84; P <0.001), and no difference in valve area (-0.06 ± 0.48 cm2; P =0.33). There was also a strong correlation of AVA between CT and transthoracic echocardiography (n=46; r=0.83; P <0.001), and a small overestimation of AVA with CT compared with transthoracic echocardiography (0.17 ± 0.33 cm2; P <0.001). The sensitivity and specificity of CT compared with TEE for visualization of severe aortic stenosis (defined by TEE as AVA <1 cm2) was 92.1% (35 of 38) and 89.5% (17 of 19), respectively. There was fair agreement of calcification grade between CT and TEE. Conclusions
AVA as obtained on 64-MDCT with retrospective gating strongly correlates with
echocardiography and has high sensitivity and specificity for detecting severe
aortic stenosis.

Reviewer’s Comments
The authors have demonstrated that with careful attention to methodology, the
AVA can be very nicely evaluated with gated 64-MDCT.

Author: Vineet R. Jain, MD

Reference:
LaBounty TM, Sundaram B, et al. Aortic Valve Area on 64-MDCT Correlates
With Transesophageal Echocardiography in Aortic Stenosis.
AJR;
2008;191 (December): 1652-1658:

Cardiac CTA: What You Need to Know
 
 University of California San Francisco, Department of Radiology
 Course Director: Gautham P. Reddy, MD, MPH

 
  Coronary artery disease is the leading cause of morbidity and mortality in industrialized countries. With the advent of 64-detector CT scanners, CT has become an essential tool for evaluation of the heart and great vessels, and is a promising technique for assessment of the coronary arteries.
 
  Click here to read more or order:
  Cardiac CTA: What You Need to Know
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