Manuel Patino MD, Presenter: Nothing to Disclose

Jorge Mario Fuentes MD, Abstract Co-Author: Nothing to Disclose

Koichi Hayano MD, Abstract Co-Author: Nothing to Disclose

Avinash Ranesh Kambadakone MD, FRCR, Abstract Co-Author: Nothing to Disclose

Jennifer W. Uyeda MD, Abstract Co-Author: Nothing to Disclose

Dushyant V. Sahani MD, Abstract Co-Author: Research Grant, General Electric Company

To compare the performance of three Hybrid Iterative Reconstruction Techniques (h-IRTs) (ASIR, iDose4, SAFIRE) with their respective strengths on image noise reduction on low-dose Computed Tomography (CT) exams using Filtered Back Projection (FBP) as standard reference. Also, to compare image noise reduction between h-IRTs and Model Based IRTs (MB-IRTs) (MBIR/Veo and IMR) on low dose exams.

An anthropomorphic abdomen phantom was scanned at 100 - 120 kVp and different mAs (25-100) on three CT systems (GE Discovery CT750-HD, ASIR, MBIR/Veo; Philips iCT, iDose4, IMR; and Siemens Somatom, SAFIRE). Images were reconstructed using FBP and various strengths of IRTs. Nine noise measurements (ROI mean size 423 mm2) on extra-colonic fat for the strengths of IRTs were recorded and compared to FBP using ANOVA. Radiation dose in CTDIvol and DLP was also compared.

There was no significant difference on radiation dose and image noise on FBP between the scanners (p>0.05). Gradual image noise reduction was observed with each increment of h-IRT’s strength with maximum noise suppression around 50% (48.2-53.9%). Similar noise reduction was achieved on the scanners by applying specific h-IRT strengths. Maximum noise reduction on MB-IRTs was higher (68.3-81.1%) than that on h-IRTs (p<0.05).

By using constant scan parameters, radiation dose and image noise on FBP are similar for different manufacturer CT scanners. Significant image noise reduction is achieved on low-dose CT images rendered with IRTs. The image noise on various scanners can be matched by applying specific h-IRTs strengths. MB-IRTs attain substantially higher noise reduction over h-IRTs irrespective of the radiation dose.

This study lends the opportunity to understand the impact of various IRTs and influence of their strengths on the image noise. Since implementation of these techniques in clinical practice can be complex, this experience can assist in optimizing abdomen CT protocols with standard and modified dose scan parameters.

Patino, M, Fuentes, J, Hayano, K, Kambadakone, A, Uyeda, J, Sahani, D, A Quantitative Comparison of Noise Reduction across Five Commercial (Hybrid and Model Based) Iterative Reconstruction Techniques: An Anthropomorphic Phantom Study.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14010948.html