Tin-filtered low-dose chest CT to quantify macroscopic calcification burden of the thoracic aorta
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To compare a low-dose, tin-filtered, nonenhanced, high-pitch Sn100 kVp CT protocol (Sn100) with a standard protocol (STP) for the detection of calcifications in the ascending aorta in patients scheduled for cardiac surgery.
Institutional Review Board approval for this retrospective study was waived and the study was HIPAA-compliant. The study included 192 patients (128 men; age 68.8 ± 9.9 years), of whom 87 received the STP and 105 the Sn100 protocol. Size-specific dose estimates (SSDE) and radiation doses were obtained using dose monitoring software. Two blinded readers evaluated image quality on a scale from 1 (low) to 5 (high) and the extent of calcifications of the ascending aorta on a scale from 0 (none) to 10 (high), subdivided into 12 anatomic segments.
The Sn100 protocol achieved a mean SSDE of only 0.5 ± 0.1 mGy and 0.20 ± 0.04 mSv compared with the mean SSDE of 5.4 ± 2.2 mGy achieved with the STP protocol (p < 0.0001). Calcification burden was associated with age (p < 0.0001), but was independent of protocol with mean calcification scores of 0.48 ± 1.23 (STP) and 0.55 ± 1.25 (Sn100, p = 0.18). Reader agreement was very good (STP κ = 0.87 ± 0.02, Sn100 κ = 0.88 ± 0.01). The STP protocol provided a higher subjective image quality than the Sn100 protocol: STP median 4, interquartile range 4–5, vs. SN100 3, 3–4; p < 0.0001) and a slightly better depiction of calcification (STP 5, 4–5, vs. Sn100 4, 4–5; p < 0.0001).
The optimized Sn100 protocol achieved a mean SSDE of only 0.5 ± 0.1 mGy while the depiction of calcifications remained good, and there was no systematic difference in calcification burden between the two protocols.
• Tin-filtered, low-dose CT can be used to assess aortic calcifications before cardiac surgery
• An optimized Sn100 protocol achieved a mean SSDE of only 0.5 ± 0.1 mGy
• The depiction of atherosclerosis of the thoracic aorta was similar with both protocols
• The depiction of relevant thoracic pathologies before cardiac surgery was similar with both protocols
KeywordsMultidetector computed tomography Imaging Radiation exposure Aorta Arteriosclerosis
CT dose index
Picture archiving and communication system
Low-dose, tin-filtered Sn100 kVp CT protocol
Size-specific dose estimates
The authors state that this work did not receive any funding.
Compliance with ethical standards
The scientific guarantor of this publication is Dr. Malte Bongers, M.D.
Conflict of interest
The authors declare general relationships with Siemens Healthcare, Forchheim, Germany. Siemens Healthcare was not involved in this study at any time.
Statistics and biometry
Dr. Alfredo Farjat, Ph.D. kindly provided statistical advice for this study and he is listed as one of the authors.
Written informed consent was waived by the Institutional Review Board.
Institutional Review Board approval was obtained.
• case-control study
• performed at one institution
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