What are the advantages to increased pitch in coronary computed tomography angiography (CCTA)?

Updated: Dec 21, 2017
  • Author: Eugene C Lin, MD; Chief Editor: Eugene C Lin, MD  more...
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With dual-source scanners, the pitch can be increased at high heart rates to reduce radiation dose.

Increasing the pitch will decrease the radiation dose, as the patient is exposed to radiation for a shorter period of time. The pitch can be increased at higher heart rates, because the time necessary to collect data throughout the cardiac cycle is decreased when the R-R interval is shorter.

However, single-source scanners typically do not allow pitch to be increased at high heart rates. Single-source scanners usually need to utilize multisegment reconstruction to increase temporal resolution at high heart rates, and multisegment reconstruction requires a low pitch. In this technique, the data required for image reconstruction are selected from multiple sequential heart cycles. This technique requires retrospective gating and a regular heart rate. [39] For data from several cardiac cycles to be used for image reconstruction, the same position has to be covered by the detector during consecutive cardiac cycles. Thus, the pitch must be lowered, which will increase radiation dose. Multisegment reconstruction is effective in improving temporal resolution only at specific heart rates (the heart rate and gantry rotation time need to be desynchronized).

A dual-source scanner has greater temporal resolution, and multisegment reconstruction is not necessary at high heart rates. This allows the pitch to be increased, and dose decreased, at higher heart rates.

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