Yang Hou MD, Presenter: Nothing to Disclose

Shu Xu BS, Abstract Co-Author: Nothing to Disclose

Wenli Guo, Abstract Co-Author: Nothing to Disclose

Qiyong Guo MD, Abstract Co-Author: Nothing to Disclose

Iterative reconstruction techniques have demonstrated the ability to enable dose reduction for certain clinical applications. We quantitatively and qualitatively evaluated an iterative reconstruction algorithm for low-dose prospectively triggered coronary CTA (CCTA) using a cardiac phantom.

A cardiac anthropomorphic phantom (IBA ,Germany) was scanned using prospective ECG-triggered CCTA protocols at standard dose (D1: 120 kVp, 200 mAs) and 3 levels of radiation dose reduction (D2: 120kVp, 140mAs; D3: 120 kVp, 100 mAs; D4: 120 kVp, 60 mAs) on a 256-slice CT (Brilliance iCT, Philips). The routine dose scan (D1) was reconstructed using conventional filtered backprojection (FBP) and the low-dose scans (D2–D4) with an iterative reconstruction algorithm (iDose, Philips). The iDose reconstructions were performed at noise reduction strengths targeted to compensate for the dose reduction with which they were acquired(e.g., 30%, 50%, & 70% dose reduction acquisitions were reconstructed using 30%, 50%, & 70% iDose strengths, respectively). Two radiologists blinded to acquisition technique evaluated images for contrast, sharpness, image noise, and Image quality, using a 4-point scale (1: non-diagnostic, 4: better than routine dose). Quantitative noise measurements were performed. Data were analyzed using the Wilcoxon signed-rank test.

Objective noise with standard and reduced (30%, 50%, 70%) dose levels were 14.7 ± 1.8, 15 ± 2.1, 15.3 ± 2.0, & 15 ± 1.7, respectively, showing no significant difference (p > 0.05). Median image quality scores for sharpness, image quality and contrast were [D1, D2, D3, D4; p-value]: [3, 3.5, 3, 2; p>0.05] [3, 3.5, 3, 2.5; p>0.05] and [3, 4, 3, 4; p<0.05]. Hence, low-contrast was found to be significantly better in some iDose reconstructions, while all other metrics were not significantly different among the reconstructions.

The iDose iterative reconstruction algorithm enables CCTA acquisition with up to 70% less dose compared to a standard scan protocol with no increase in objective image noise. In addition, the algorithm may improve low-contrast resolution as rated by expert observers.

The iDose iterative reconstruction algorithm enables lowering CCTA dose.

Hou, Y, Xu, S, Guo, W, Guo, Q, Low-Dose 256-Slice Coronary CTA with a Model-based Iterative Reconstruction Algorithm: Cardiac Phantom Feasibility Study.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9010960.html