Prabhakar Rajiah MD, FRCR, Presenter: Nothing to Disclose

Paul Schoenhagen MD, Abstract Co-Author: Nothing to Disclose

Sandra Simon Halliburton PhD, Abstract Co-Author: Research grant, Siemens AG Medical Advisory Board, Koninklijke Philips Electronics NV

To evaluate image quality and radiation dose in ECG-referenced and non-ECG-referenced CT scans of the pulmonary veins.

Patients were scanned supine during an expiratory breath-hold using a 256-slice CT scanner (Brilliance iCT) following the administration of 75-90 ml of contrast. Standard acquisition parameters were used for prospectively ECG-triggered axial (120 kVp, 130-350 mAs), retrospectively ECG-gated helical (120 kVp, 130–1300 mAs/slice, 0.2 pitch), and non-gated helical (120 kVp, 130-300 mAs/slice, 0.8 pitch) techniques. Axial imaging was the standard, but gated helical was used in patients with high heart rates (> 65 bpm) or large body size (assessed visually). on-gated helical technique was used for all patients in atrial fibrillation.The individual pulmonary veins and the left atrium, including the left atrial appendage, were evaluated for anatomy, stenosis and thrombus, and graded for motion on a 0-4 scale (0, no motion).

150 patients were studied, of which 50 patients were evaluated with axial, 50 with gated helical, and 50 with non-gated helical techniques. Variant venous anatomy was seen in 40 (28%), left atrial thrombus in 2(1.4%), slow flow in 11(8%) and pulmonary vein stenosis in 8(6%) of patients. Non-gated helical scans had the shortest acquisition times (3.4±0.4s vs 7.1±1.4s for axial and 6.1±2.4s for gated helical) and the lowest effective radiation dose (3.9±1.0 mSv vs. 4.8±1.4 mSv for axial and 10.7±2.7mSv for gated helical). Image quality was excellent for visualization of pulmonary veins in all the 3 techniques, although the incidence of motion artifacts was slightly greater for non-gated images in both the pulmonary veins (0.3±0.5 vs 0.04±0.2 for axial and 0.04±0.2 for gated helical) and the left atrial appendage (1.1±0.7 vs 0.01 ±0.13 for axial and 0.5±0.6 for gated helical).

Nongated CT offers reduced scan time and radiation dose compared to ECG-triggered axial or ECG-gated helical scanning but equivalent diagnostic image quality. Although a slight increase in motion was observed compared with gated techniques, particularly in evaluation of left atrial appendage, non-gated helical CT is very helpful in patients with atrial fibrillation.

Prospectively gated axial scans have the least radiation dose in CT pulmonary vein studies. In atrial fibrillation, non gated scan can acquire images without significant motion artifacts.

Rajiah, P, Schoenhagen, P, Halliburton, S, Nongated Computed Tomography (CT) Angiography of the Pulmonary Veins for Patients with Atrial Fibrillation.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9003913.html