What is dual-source CT?

Updated: Dec 21, 2017
  • Author: Eugene C Lin, MD; Chief Editor: Eugene C Lin, MD  more...
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The primary advantage of dual-source CT is greater temporal resolution.

A dual-source CT contains 2 tube/detector sets, arranged at 90º angles to each other. In CCTA, the data are typically reconstructed from a 180º rotation (partial scan reconstruction) to maximize temporal resolution. If the gantry rotation time is 330 msec, a single-source CT performing CCTA with partial scan reconstruction has a temporal resolution of 165 msec. With 2 tubes, only a quarter rotation is needed for data collection, and the temporal resolution is 83 msec.

The higher temporal resolution of dual-source CT allows CCTA to be performed at higher heart rates without the use of beta blockers.

Although the tube current is doubled with 2 tubes, the scan time is halved, and the tube current-time product (mAs) is unchanged as compared with single-source CT. [42] However, radiation dose can usually be lower than that with single-source CT. Because of higher temporal resolution, the pitch can be increased at higher heart rates, which will decrease dose (see Radiation Dose). In addition, other dose-reduction techniques, such as ECG-dependent tube current modulation and prospectively triggered sequential scanning (see Radiation Dose), can be optimally used with the increased temporal resolution of a dual-source scanner.

In addition, simultaneous data acquisition can be performed with the tubes operating at different voltages (80 kV and 140 kV). [42] This offers the possibility of improved tissue differentiation, but it is unclear what impact this will have on CCTA.

In a meta-analysis of 25 studies, [43] dual-source CT had a per-patient sensitivity of 99% and specificity of 89%. Accuracy remained high in a systematic review of the use of dual-source CT in difficult-to-image patient groups. [44]

In an in vitro evaluation of in-stent lumen visibility of 27 commonly used modern coronary stents, Gassenmaier et al reported that use of third-generation dual-source CTA enables stent lumen visibility of up to 80% in metal stents and 100% in bioresorbable stents. CTA may be a valid alternative for detection of in-stent restenosis. [45]

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