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64-MDCT Reliably Evaluates Right Ventricular Function

April 15, 2009
Written by: , Filed in: Cardiac Imaging
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A recent study was conducted to evaluate the ability of 64-MDCT to assess right ventricle (RV) function compared with MRI.

The Study

38 patients who underwent cardiac 64-MDCT followed by cardiac MRI were evaluated. Mean time delay between studies was 54 +/- 17 minutes. Patients underwent the cardiac 64-MDCT for evaluation of coronary artery disease.

Methodology
All patients with a heart rate >70 bpm received a beta-blocker, which was 50 or 100 mg of metoprolol.

The 64-MDCT used retrospective ECG-gating and did not use tube current modulation.

IV contrast was administered to optimize enhancement of coronary arteries using the test-bolus technique.

Contrast (10 mL) was injected at 5 mL/second followed by 50 mL saline chaser.

The time between contrast injection and greatest enhancement of the ascending aorta was used as the scanning delay.

Mean amount of IV contrast given was 75 +/- 2 mL.

Images were obtained every 5% of the cardiac cycle and double oblique reformations of the right ventricle were constructed using a slice thickness of 5 mm without an interslice gap on a separate workstation.

Slices from the apex of the right ventricle to the tricuspid valve were included, and endocardial contours of the RV were manually drawn on the end-systole and end-diastole images.

The RV outflow tract was included in the chamber and papillary muscles were also included. Simpson’s method was used to tabulate RV ejection fraction.

MRIs were performed on a 1.5-T scanner. Prospective triggering was applied for ECG synchronization, and 50 phases for 1 cardiac cycle were obtained at each slice position.

A balanced fast-field echo sequence was used, and slice thickness was 5.0 mm without an interslice gap. Short-axis images were analyzed using the same software as was the 64-MDCT.

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

Results
For men, mean heart rate was 64.0 +/- 1.7 bpm during MDCT and 63.0 +/- 1.5 bpm during MRI; for women, mean heart rate was 67.0 +/- 2.4 bpm during MDCT and 64.0 +/- 2.6 bpm during MRI.

During MDCT, the calculated radiation exposure for men was 11.3 +/- 1.0 mSv and for women, it was 16.9 +/- 1.1 mSv.

There was excellent correlation between 64-MDCT and MRI for end-diastolic volume (r = 0.99), end-systolic volume (r = 0.98), stroke volume (r = 0.98), and ejection fraction (r = 0.97).

Mean RV ejection fraction calculated on CT was 51.0% +/- 7.8% and on MRI, it was 51.4% +/- 7.3%.

Conclusions
Retrospective ECG-gated cardiac 64-MDCT reliably evaluates right ventricular function compared with cardiac MRI.

Reviewer’s Comments
It is interesting that, although timing of contrast was geared toward optimal enhancement of coronary arteries, the ability to evaluate right ventricle function was not significantly hindered. One limitation of this article was the need to give beta-blockers, which may affect RV volumes.

Author: Vineet R. Jain, MD


Reference:

Plumhans C, Muhlenbruch G, et al. Assessment of Global Right Ventricular Function on 64-MDCT Compared With MRI. AJR; 2008; 190 (May): 1358-1361

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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