Lilian Albieri, Abstract Co-Author: Nothing to Disclose

Roberto Sasdelli Neto MD, Abstract Co-Author: Nothing to Disclose

Cesar Higa Nomura MD, Presenter: Nothing to Disclose

Gilberto Szarf MD, Abstract Co-Author: Nothing to Disclose

Fernando Uliana Kay MD, Abstract Co-Author: Nothing to Disclose

Adriano Tachibana MD, Abstract Co-Author: Nothing to Disclose

Walther Ishikawa, Abstract Co-Author: Nothing to Disclose

Gustavo Borges Teles MD, Abstract Co-Author: Nothing to Disclose

Rodrigo Caruso Chate MD, Abstract Co-Author: Nothing to Disclose

Fabio Augusto, Abstract Co-Author: Nothing to Disclose

Marcelo Assis Rocha, Abstract Co-Author: Nothing to Disclose

Vinicius Neves Marcos MD, Abstract Co-Author: Nothing to Disclose

Joao Paulo Barcellar Costa Lima MD, Abstract Co-Author: Nothing to Disclose

Bruna Bonaventura Failla, Abstract Co-Author: Nothing to Disclose

Elaine Silva, Abstract Co-Author: Nothing to Disclose

Marcelo Buarque Gusmao Funari MD, Abstract Co-Author: Nothing to Disclose

To compare the estimated effective radiation dose (EERD) in Coronary CTAs performed in patients (Pts) with CABG, scanned with 64- and 320-row CT, without and with IR. We also compared image quality (IQ) between scans performed with 320-row CT without and with IR.

178 patients (Pts) were retrospectively selected from our RIS/PACS system (164 men. Mean age=69 y/o, mean BMI=28.52 kg/m2, w/o significant difference between groups), and divided in 3 groups: 64-CT (Group 01-20 Pts); 320-CT w/o IR (Group 02–94 Pts); 320-CT with IR (Group 03–64 Pts) EERD is expressed in milisievert (mSv) IQ: -Objective assessment by noise and signal-to-noise ratio (SNR) values. -Subjective assessment by 4-level grade scale observed by 2 radiologists in consensus (I–Unacceptable; II–Regular; III–Good; IV–Excellent). Statistical analysis (SPSS with significance level of 5): -The data distribution - histograms, coefficients of kurtosis and asymmetry, and Shapiro-Wilk normality tests. -Asymmetric variables - medians and interquartiles ranges. -Comparisons between 320 w/o and 320 with IR - nonparametric tests of Mann-Whitney. -All other numeric variables - averages and standard deviations and comparisons made by Student's t test. -Gender - absolute frequencies and percentages and comparison of the groups made by Fisher's exact test.

Mean EERD: G1≅27.6 mSv (P25%=24.6; P75%=29.9); G2≅11.2 mSv (P25%=8.4; P75%=16.6); G3≅9.9 mSv (P25%=6.1; P75%=18.8) EERD comparison: -G3xG1 – EERD reduction by 63% (p<0.001) -G3xG2 – EERD reduction by 12% (p<0.05) Mean Noise: G2≅27.8 UH; G3≅35.9 UH; Noise's higher on G3; p<0.001 Mean SNR: G2≅21.6 UH; G3≅17.0 UH; SNR was lower on G3; p<0.001 Subjective IQ: G2 (I-0%; II-1.1%; III-11.7%; IV-87.2%); G3 (I-0%; II-4.6%; III-4.6%; IV-90.8%); p=0.102

EERD can be significantly reduced in Coronary CTA performed in CABG patients, using 320-row CT with IR algorithm, especially when compared to 64-row CT. Despite the increase on image noise and the reduction on SNR, the subjective analysis demonstrated that imaging quality is quite similar to 320-row CT without IR.

This study demonstrates reduction in radiation dose of Coronary CTA in CABG Pts using Iterative Reconstruction, what may reinforce its applicability in this group, once it has high accuracy since 16CT

Albieri, L, Sasdelli Neto, R, Nomura, C, Szarf, G, Kay, F, Tachibana, A, Ishikawa, W, Teles, G, Chate, R, Augusto, F, Rocha, M, Marcos, V, Lima, J, Failla, B, Silva, E, Funari, M, Coronary CT Angiography (Coronary CTA) in patients with Coronary Artery Bypass Grafts (CABG): Comparison of the Estimated Effective Radiation Dose between 64- and 320-row CT Scanners, with and without Iterative Reconstruction (IR).  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14004648.html