Comparison of Radiation Dose and Image Quality of Triple-Rule-Out Computed Tomography Angiography Between Conventional Helical Scanning and a Strategy Incorporating Sequential Scanning

Abstract

Triple-rule-out computed tomography angiography (TRO CTA), performed to evaluate the coronary arteries, pulmonary arteries, and thoracic aorta, has been associated with high radiation exposure. Utilization of sequential scanning for coronary computed tomography angiography (CCTA) reduces radiation dose. The application of sequential scanning to TRO CTA is much less well defined. We analyzed radiation dose and image quality from TRO CTA performed in a single outpatient center, comparing scans from a period during which helical scanning with electrocardiographically controlled tube current modulation was used for all patients (n=35) and after adoption of a strategy incorporating sequential scanning whenever appropriate (n=35). Sequential scanning was able to be employed in 86% of cases. The sequential-if-appropriate strategy, compared to the helical-only strategy, was associated with a 61.6% dose decrease (mean dose-length product [DLP] of 439 mGy×cm vs 1144 mGy×cm and mean effective dose of 7.5 mSv vs 19.4 mSv, respectively, p<0.0001). Similarly, there was a 71.5% dose reduction among 30 patients scanned with the sequential protocol compared to 40 patients scanned with the helical protocol under either strategy (326 mGy×cm vs 1141 mGy×cm and 5.5 mSv vs 19.4 mSv, respectively, p<0.0001). Although image quality did not differ between strategies, there was a non-statistically significant trend towards better quality in the sequential protocol compared to the helical protocol. In conclusion, approaching TRO CTA with a diagnostic strategy of sequential scanning as appropriate offers a marked reduction in radiation dose while maintaining image quality.

128-slice CT angiography of the aorta without ECG-gating: efficacy of faster gantry rotation time and iterative reconstruction in terms of image quality and radiation dose

“…First of all, prospective ECG-gating leads to a significant increase of imaging time (up to 25 s for thoracicabdominal CTAA) and, consequently, contrast media volume (which correlates to scan time in CT angiographic examinations). Secondly, the average ED of prospectively gated CTAA reported in the medical literature [21][22][23][24][25] is highly variable, and considerably higher (from 7.5 to 18 mSv) compared to our results (5.2 mSv).…”

Triple Rule-out Computed Tomographic Angiography for Chest Pain: A Diagnostic Systematic Review and Meta-Analysis

“…After further review of the title and abstract, the German article was found to include a subset of the same cohort published in another article and was excluded. Seven articles were excluded because they compared different CT protocols instead of comparing TRO CT to a separate diagnostic modality . Nine studies did not compare the TRO CT to another control group .…”

Image Quality and Feasibility of an Ultralow-dose High-pitch Helical Triple–rule-out Computed Tomography Angiography Acquired in the Caudocranial Direction

“…By adjustment of certain parameters including contrast administration and scan length, the TRO scan has been shown to be an accurate imaging method to assess the coronary arteries, PAs, aorta, and lung parenchyma simultaneously. 30 Two prior studies by Bamberg et al 25 and Sommer et al 31 utilized a high-pitch helical acquisition for a TRO scan but demonstrated average doses of 3.82 and 4.08 mSv, respectively. 16 Although ECGtube current modulation and prospective gating have led to dose reductions, the average dose reported for a TRO scan using these methods remains rather high, measuring 19.4 and 7.5 mSv, respectively.…”