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).

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).

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

PMID: 19760421

Posted in Computed Tomography and tagged , , .

2 Comments

  1. This and the posted article by Leschka et al., report initial results with a new dual-source scanner generation with high-pitch mode.
    In selected patient coronary, CTA is performed at sub-miliSievert doses.

  2. Results of the study show that diagnostic, high-quality images can be obtained in patients with low heart rates using prospectively ECG-gated high-pitch exams with effective doses below 1.0 mSv.
    While most of the discussion concentrates on the technical features of high-pitch spiral acquisitions on dual source scanners, there is a result that also merits being mentioned – High quality images were acquired using boluses of contrast of only 60cc! (Iodine concentration not disclosed). The reduction in image acquisition time with this new generation scanners will probably permit the use of tighter-shorter boluses of contrast.

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