Coronary CT angiography using iterative reconstruction 
vs. filtered back projection: evaluation of image quality

Main Article Content

Teresa Arcadi
Erica Maffei
Cesare Mantini
Andrea Guaricci
Ludovico La Grutta
Chiara Martini
Filippo Cademartiri

Keywords

iterative reconstruction, signal, noise, cardiac CT, filtered back projection

Abstract

Objectives: To compare image quality of iterative reconstruction algorithm(IRIS) vs. standard filtered back projection(FBP) reconstruction in CT Coronary Angiography (CTCA). Materials and methods: Thirty-four consecutive patients underwent CTCA for suspected or known CAD with Dual-Source CT (DSCT-Flash, Siemens). All datasets were reconstructed with 0.75/0.4 and 0.6/0.4 mm slice thickness/increment, using three standard FBP kernels (B26-B30-B46) and three comparable IRIS algorithms (I26-I30-I46). Vascular attenuation and noise were measured. CT vascular attenuation values [HU] were measured in: ascending aorta (Ao), right (RCA) and left (LCA) coronary artery, respectively. Signal-to-noise (SNR) and contrast-to-noise (CNR) ratio were calculated. A p-value<0.05 was considered significant. Results: There was no significant difference between the vascular attenuation values measured with FBP (Ao:458HU, RCA:448HU, LAD:444HU) and IRIS (Ao:456HU, RCA:446HU, LAD:442HU). Difference in noise was significant between FBP (24±SD) and IRIS (19±SD) (r=0.34;p<0.05). Lowest noise was found for IRIS using 0.6 mm (17HU). IRIS provided a SNR and CNR significantly higher with increasing kernel sharpness. SNR was 33.3±25.1, 77.3±51.7, 37.2±36.6, 64.4±59.2, while CNR was 25.32±19.8, 58.0±36.0, 28.6±23.5, 47.6±47.3 for 0.75B, 0.75I, 0.6B and 0.6I, respectively. IRIS showed an improvement in SNR of 57% and 56% for 0.75 mm and 0.6 mm, respectively, and an improvement in CNR of 42% and 40% for 0.75 mm and 0.6 mm. Conclusions: In CTCA, iterative reconstructions provide a significant higher image quality compared with the conventional FBP reconstructions. (www.actabiomedica.it)
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