Stephen Choy MD, Presenter: Nothing to Disclose

Dennis Parhar BSc, Abstract Co-Author: Nothing to Disclose

Kevin Lian MD, Abstract Co-Author: Nothing to Disclose

Luck Jan-Luck Louis MD, Abstract Co-Author: Nothing to Disclose

Tim O'Connell MD, Meng, Abstract Co-Author: President, Resolve Radiologic Ltd

Katharine Grant PhD, Abstract Co-Author: Employee, Siemens AG

Patrick McLaughlin FFR(RCSI), Abstract Co-Author: Nothing to Disclose

Savvas Nicolaou MD, Abstract Co-Author: Nothing to Disclose

We conducted a retrospective intra-individual study to compare the image noise, signal-to-noise ratio (SNR) and subjective image quality between CT images acquired with a dual source, split dose imaging protocol reconstructed at full and half dose with filtered back projection (FBP) and a novel third generation modeled iterative reconstruction algorithm (SAFIRE+). 

53 consecutive patients underwent contrast enhanced CT abdomen using a standardized dual source, single energy CT protocol (100kV, ref mAs 162, 32x0.6 mm) on a 128-slice CT scanner (Definition FLASH, Siemens Healthcare, Germany). Half dose images using projection data only from detector A were retrospectively generated from scanner raw data. The full dose dataset was reconstructed with FBP, while the half dose dataset was reconstructed with FBP and SAFIRE+ from strengths 1 to 5. Region of interest analysis was performed on four structures within the abdomen and assessed for noise and SNR. Qualitative interpretation was performed by a radiologist with 8 years of experience. Diagnostic acceptability, subjective noise and spatial resolution were graded on a 10 point scale. Statistical analysis was done with repeated measures analysis of variance and Wilcoxon signed rank test.

There was a statistically significant decrease in objective noise and increase in SNR for 50% dose SAFIRE+ strength 4 and 5 compared to 100% dose FBP (p<0.01). No statistically significant difference in noise and SNR was measured for SAFIRE+ strength 3 compared to 100% dose FBP. With increasing strength of SAFIRE+, there was a progressive reduction in noise and increase in SNR (p<0.01). Qualitative analysis revealed a progressive increase in diagnostic acceptability, decrease in subjective noise and increase in spatial resolution for 50% dose images reconstructed with increasing strengths of SAFIRE+ (p<0.01).

Half dose CT images reconstructed with SAFIRE+ at a strength of 3 are equivalent with full dose images reconstructed with FBP. Unlike previous generations of hybrid iterative reconstruction, increased image quality scores were demonstrated at higher SAFIRE+ strengths, potentially allowing dose reductions on the order of 50%.

A novel third generation modeled iterative reconstruction algorithm (SAFIRE+) may allow for a 50% dose reduction in abdominal CT acquisition protocols while maintaining image quality and image noise.

Choy, S, Parhar, D, Lian, K, Louis, L, O'Connell, T, Grant, K, McLaughlin, P, Nicolaou, S, Comparison of Image Noise and Quality between Dual-source, Full Dose Abdominal CT Scans Reconstructed with Filtered Back Projection and Half Dose Scans Reconstructed with Third Generation Modeled Iterative Reconstruction Algorithm (SAFIRE+).  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14016350.html