The aim of this study was to compare the accuracy of coronary artery calcium scoring (CACS) on cardiac computed tomographic images using hybrid iterative reconstruction (hIR) and a low tube current as well as on images acquired with a filtered back projection (FBP) algorithm and a normal tube current.
Patients (N = 77) with suspected coronary artery disease were subjected to 2 CACS evaluations based on their Agatston, volume, and mass scores. One CACS evaluation was performed on images obtained with a 364-mA tube current and reconstructed with FBP; the other was performed on images obtained with a 73-mA tube current and reconstructed with hIR at iDose4. All scans were performed with the prospective electrocardiogram-triggered method using a 256-slice computed tomographic scanner (Brilliance iCT; Philips). We assessed agreement between calcium scores obtained with FBP and with IR using the percentage difference and Bland-Altman analysis.
The effective radiation doses for CACS at 80 mA s with FBP and at 16 mA s with IR were 1.20 and 0.24 mSv, respectively (k = 0.014). The mean Agatston, volume, and mass scores at 80 mA s with FBP as well as at 16 mA s with IR were 390.7, 146.5, and 63.2 as well as 377.7, 142.5, and 62.2, respectively. The percentage difference between FBP and hIR for the Agatston, volume, and mass score was 20.7%, 20.7%, and 27.1%, respectively. Bland-Altman analysis showed that there was no systemic bias.
The radiation dose for CACS can be reduced at a low tube current and hIR without affecting the calcium score.
From the *Department of Diagnostic Radiology, Kure Medical Center, Kure; †Department of Diagnostic Radiology, Hiroshima City Hospital; and ‡Department of Diagnostic Radiology, Hiroshima University Hospital, Hiroshima, Japan.
Received for publication June 20, 2014; accepted September 8, 2014.
Reprints: Noriaki Matsuura, PhD, MD, Department of Radiology, Hirohsima City Hospital, 7-33 Motomachi, Naka-ku, Hiroshima 730-8518, Japan. Present address: Department of Diagnostic Radiology, Kure Medical Center, 3-1 Aoyama-cho, Kure City, Hiroshima 737-0023, Japan (e-mail: email@example.com).
The authors declare no conflict of interest.