Quantitative and qualitative evaluation of hybrid iterative reconstruction, with and without noise power spectrum models: A phantom study

Abstract

The purpose of this phantom study was to investigate the feasibility of dose reduction with hybrid iterative reconstruction, with and without a noise power spectrum (NPS) model, using both quantitative and qualitative evaluations. Standard dose (SD), three‐quarter dose (TQD), and half‐dose (HD) of radiation were used. Images were reconstructed with filtered back projection (FBP), adaptive iterative dose reduction 3D (AIDR 3D) (MILD, STR), and AIDR 3D enhanced (eAIDR 3D) (eMILD, eSTR). An NPS analysis, task‐based modulation transfer function (MTF task) analysis, and comparisons of low‐contrast detectability and image texture were performed. Although the eAIDR 3D had a higher NPS value in the high‐frequency range and improved image texture and resolution as compared with AIDR 3D at the same radiation dose and iteration levels, it yielded higher noise than AIDR 3D. Additionally, although there was no statistically significant difference between SD‐FBP and the TQD series in the comparison of the mean area under the curve (AUC), the mean AUC was statistically significantly different between SD‐FBP and the HD series. NPS values in the high‐frequency range, 10% MTF task values, low‐contrast detectability, and image textures of TQD‐eMILD were comparable to those of SD‐FBP. Our findings suggested that using eMILD can reduce the radiation dose by 25%, while potentially maintaining diagnostic performance, spatial resolution, and image texture; this could support selecting the appropriate protocol in a clinical setting.

Improvement of Image Quality Using Hybrid Iterative Reconstruction with Noise Power Spectrum Model in Computed Tomography During Hepatic Arteriography

“…Therefore, eAIDR is superior to AIDR for visualizing tiny structures on CT arteriography which provides highcontrast images [7].…”

“…This is because the mean CT attenuation of feeding arteries in eAIDR was significantly higher than that of AIDR, which improved the SNR of the feeding arteries in eAIDR. Therefore, eAIDR is superior to AIDR for visualizing tiny structures on CT arteriography which provides high-contrast images [ 7 ].…”

“…The hybrid iterative reconstruction (HIR) with a noise power spectrum (NPS) model is expected to reduce image noise without degrading the spatial resolution [ 7 8 ]. We thus speculated that HIR with the NPS model would be useful for CTHA, and we conducted the present study to assess the objective and subjective image quality of HIR with NPS model for CTHA as compared to both filtered back projection (FBP) and HIR without NPS model.…”

Feasibility of thin-slice abdominal CT in overweight patients using a vendor neutral image-based denoising algorithm: Assessment of image noise, contrast, and quality

“…In theory, slice thickness has a strong linear influence on the number of photons used to produce the images, and thinner slices use fewer photons, resulting in increased image noise and deteriorated low-contrast resolution [18], which is a critical issue because noise may substantially decrease low-contrast detectability for abdominal CT examinations. In addition, CT examinations in the overweight population are challenging because there is a tradeoff between image noise and radiation dose [6,7,12,19]. Sometimes, a modified CT protocol is adopted to obtain optimal image quality in abdominal CT, which includes high tube current and/or slow rotation time; this is associated with concerns regarding potential exposure to high-dose radiation [20].…”

“…For each averaged image, an ROI was placed around the two objects as shown in Fig 2F. MTF values were calculated using the radial edge method, with contrasts of 100 and 340 HU using the CT measure version 0.97b [12].…”