Gin-Chung Liu MD, Presenter: Nothing to Disclose

Twei-Shiun Jaw MD, Abstract Co-Author: Nothing to Disclose

Paul Ming-Chen Shih MD, Abstract Co-Author: Nothing to Disclose

Chien-Hung Lee Lee, Abstract Co-Author: Nothing to Disclose

Tsyh-Jyi Hsieh MD, Abstract Co-Author: Nothing to Disclose

Lo-Yeh Lee MD, Abstract Co-Author: Nothing to Disclose

Yu-Jen Chen, Abstract Co-Author: Nothing to Disclose

Chiao-Yun Chen MD, Abstract Co-Author: Nothing to Disclose

To assess the diagnostic accuracy, image quality, and radiation dose of 80-kVp CT images for patients with colorectal cancers using a new commercialized iterative reconstruction algorithm, sinogram affirmed iterative reconstruction (SAFIRE).

Sixty-four consecutive patients (39 men, 25 women; mean age, 66 years) with known colorectal malignancy underwent dual-energy CT (DECT). Data were reconstructed as a weighted average of the 140- and 80-kVp acquisitions, simulating 120kVp, and a pure 80kVp data set. Standard convolution filtered back projection (FBP) and SAFIRE were used to reconstruct the weighted-average (protocol A, B) and 80kVp image sets (protocol C, D). For the four protocols, the mean image noise; signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) relative to muscle for the tumor, aorta, liver, spleen, pancreas and kidneys were measured. The effective dose for each protocol was also assessed. Two independent readers were invited to score the four data sets for tumor detection and image quality. Local tumor stage was determined using the TNM system. Histopathology of resection specimens served as gold standard. Analysis of variance was used for statistical analysis.

Compared with the FBP data set at weighted average (protocol A,B) and 80kVp image sets (protocol C, D), the SAFIRE reconstruction demonstrated significantly lower image noise (P < .001). Protocol D (80kVp, SAFIRE) yielded significantly higher CNRs for the tumor, aorta, liver, spleen, pancreas and kidneys than did protocol A, B and C (P < .0001 for all comparisons). Protocol D also had significantly higher SNR for the tumor, aorta, liver, spleen, pancreas and kidneys than did protocol A and C (P < .001). No statistically significant difference in tumor detection was observed between the four protocols. Overall accuracy for tumor staging was 95.3% [61 of 64] with the four protocols. Mean effective dose decreased by 41% between the weighted average protocol (6.23mSv ±0.80) and the 80-kVp protocol (3.68mSv ±0.47).

The 80kVp images with SAFIRE reconstruction is able to provide high SNR, CNR with good accuracy for tumor staging. It can also significantly reduce patient’s radiation exposure.

In patients with colorectal cancer, the low tube voltage CT scan with raw-data based SAFIRE iterative reconstructions can significantly reduce radiation dose without compromising image quality or diag

Liu, G, Jaw, T, Shih, P, Lee, C, Hsieh, T, Lee, L, Chen, Y, Chen, C, Low Radiation Dose Protocol for Colorectal Cancer Using Dual-Energy CT: Usefulness of Low Tube Voltage and Sinogram Affirmed Iterative Reconstruction.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12031786.html