Prospective ECG-Triggered Coronary CT Angiography: Clinical Value of Noise-Based Tube Current Reduction Method with Iterative Reconstruction

Abstract

ObjectivesTo evaluate the clinical value of noise-based tube current reduction method with iterative reconstruction for obtaining consistent image quality with dose optimization in prospective electrocardiogram (ECG)-triggered coronary CT angiography (CCTA).Materials and MethodsWe performed a prospective randomized study evaluating 338 patients undergoing CCTA with prospective ECG-triggering. Patients were randomly assigned to fixed tube current with filtered back projection (Group 1, n = 113), noise-based tube current with filtered back projection (Group 2, n = 109) or with iterative reconstruction (Group 3, n = 116). Tube voltage was fixed at 120 kV. Qualitative image quality was rated on a 5-point scale (1 = impaired, to 5 = excellent, with 3–5 defined as diagnostic). Image noise and signal intensity were measured; signal-to-noise ratio was calculated; radiation dose parameters were recorded. Statistical analyses included one-way analysis of variance, chi-square test, Kruskal-Wallis test and multivariable linear regression.ResultsImage noise was maintained at the target value of 35HU with small interquartile range for Group 2 (35.00–35.03HU) and Group 3 (34.99–35.02HU), while from 28.73 to 37.87HU for Group 1. All images in the three groups were acceptable for diagnosis. A relative 20% and 51% reduction in effective dose for Group 2 (2.9 mSv) and Group 3 (1.8 mSv) were achieved compared with Group 1 (3.7 mSv). After adjustment for scan characteristics, iterative reconstruction was associated with 26% reduction in effective dose.ConclusionNoise-based tube current reduction method with iterative reconstruction maintains image noise precisely at the desired level and achieves consistent image quality. Meanwhile, effective dose can be reduced by more than 50%.

Radiation dose and diagnostic image quality associated with iterative reconstruction in coronary CT angiography: A systematic review

“…Dose‐length‐product values generally corresponded to CTDI vol as they are derived from multiplying CTDI vol with scan length (cm). Four studies did not report the DLP . The DLP for FBP is significantly higher (426 ± 226 mGy.cm) than IR (241 ± 106 mGy.cm) with a difference in the mean ± SD of 186 ± 120 mGy.cm ( P = 0.019).…”

“…Dose indicators (CTDI vol , DLP and E D ) were extracted from studies where available (Tables and ). Six studies did not provide CTDI vol values . CTDI vol for FBP ranged from 16.20 to 60.30 mGy while for IR was from 11.30 to 36.90 mGy.…”

“…The 14 studies recruited a total sample size of 3428 patients . The ratio of male to female was 1664 to 1706 patients, one study did not provide the ratio between gender (Table ) …”

“…The mean ± SD of tube current for FBP and IR across five studies was 481.32 ± 331.26 and 327.56 ± 189.06 respectively indicating approximately 68% reduction in tube current used . Nine studies did not provide values for tube current . Three studies were performed on each of the following IR techniques; ASIR (GE Healthcare, Milwaukee, WI, USA); SAFIRE (Siemens Healthcare, Erlangen, Germany); AIDR (Toshiba Medical Systems Co Ltd., Otowara, Japan); iDose (Philips Healthcare, Best, the Netherlands); and two studies were performed with IRIS (Siemens Healthcare) …”

Computed tomography coronary angiography should be performed in all patients with Marfan Syndrome prior to aortic root replacement

“…Good quality CT coronary angiography has become widely available, and can be performed with radiation doses lower than 2 mSv [9]. Exposure to such a low quantity of radiation seems acceptable to minimize the risk of iatrogenic myocardial infarction caused by accidental damage to an aberrant coronary artery during aortic root replacement in these young patients.…”