Prospectively ECG-triggered high-pitch spiral acquisition for coronary CT angiography using dual source CT: technique and initial experience

Objective
We evaluated radiation exposure and image quality of a new coronary CT angiography protocol, high-pitch spiral acquisition, using dual source CT (DSCT).

Materials and methods
Coronary CTA was performed in 25 consecutive patients with a stable heart rate of 60 bpm or less after premedication, using 2 x 128 0.6-mm sections, 38.4-mm collimation width and 0.28-s rotation time. Tube settings were 100 kV/320 mAs and 120 kV/400 mAs for patients below and above 100-kg weight, respectively. Data acquisition was prospectively ECG-triggered at 60 % of the R-R interval using a pitch of 3.2 (3.4 for the last 10 patients). Images were reconstructed with 75-ms temporal resolution, 0.6-mm slice thickness and 0.3-mm increment. Image quality was evaluated using a four-point scale (1 = excellent, 4 = unevaluable).

Results

• Mean range of data acquisition was 113 +/- 22 mm, mean duration was 268 +/ 23 ms.
• Of 363 coronary artery segments, 327 had an image quality score of 1, and only 2 segments were rated as “unevaluable”.
• Mean dose-length product (DLP) was 71 +/- 23 mGy cm.
• Mean effective dose was 1.0 +/- 0.3 mSv (range 0.78-2.1 mSv).
• For 21 patients with a body weight below 100 kg, mean DLP was 63 +/- 5 mGy cm (0.88 +/- 0.07 mSv; range 0.78-0.97 mSv).

Conclusion
Prospectively ECG-triggered high-pitch spiral CT acquisition provides high and stable image quality at very low radiation dose.

Full text: Eur Radiol. 2009 Sep 4. [Epub ahead of print]

Authors:
Lell M, Marwan M, Schepis T, Pflederer T, Anders K, Flohr T, Allmendinger T, Kalender W, Ertel D, Thierfelder C, Kuettner A, Ropers D, Daniel WG, Achenbach S.