CT Images of Abdomen and Pelvis: Effect of Nonlinear Three-dimensional Optimized Reconstruction Algorithm on Image Quality and Lesion Characteristics

Abstract

The purpose of this study was to retrospectively assess the effect of a postprocessing nonlinear three-dimensional optimized reconstruction algorithm on image quality and lesion characteristics in abdominal and pelvic computed tomographic (CT) images. Institutional review board approved the HIPAA-compliant study protocol; informed consent was waived. Abdominal and pelvic CT images (40 patients; male-female ratio, 20:20; age range, 28-86 years) at 5-mm (n = 20) and 2-mm (n = 20) section thicknesses were postprocessed with the algorithm at three noise reduction levels. Image noise at the level of porta hepatis and acetabulum was evaluated with a five-point scale (1, no or minimal noise; 5, unacceptable noise), and presence and number of lesions and conspicuity were assessed. Statistical analysis was performed (Wilcoxon signed rank test, analysis of variance). Significant noise reduction was noted at all three levels with the algorithm (P < .05). Reduction in image contrast was noted with only one noise reduction level (P < .0001). The algorithm improves image noise without affecting lesion conspicuity and detection on low-dose abdominal and pelvic CT images.

Application of adaptive non-linear 2D and 3D postprocessing filters for reduced dose abdominal CT

“…The significant decrease in mean HU of the liver parenchyma from the early to late contrast phase was due to contrast washout. In general, our results are consistent with previously published phantom and patient studies, with non-linear 2D or 3D filters, on noise and radiation dose reduction for abdominal CT (5,7,8,14,16,19,20). For example, Rizzo et al Some recent CT radiation dose reduction studies using hybrid iterative reconstruction techniques have demonstrated up to 50-75% dose reduction for abdominal examinations (9).…”

“…The study is based on a sample size of only 12 patients. This small number was mainly due to the ethical considerations of exposing patients to additional radiation doses, and is to some extent compensated by using six observers, compared to one to three readers in most earlier studies (4,5,7,14,16,18,21,22). As described above, the chosen sample size was clearly adequate for obtaining significant results for most of the criteria evaluated in our study.…”

“…Image postprocessing filters can operate in an image plane (2D filters) or within a volume including the z-direction (3D filters). Prior studies have evaluated the use of 2D (4-6) or 3D (7,8) filters, but to the best of our knowledge, no direct comparisons of 2D and 3D filters for enabling radiation dose reduction have been published at the time of preparation of this manuscript.…”

Feasibility of Dose Reduction Using Novel Denoising Techniques for Low kV (80 kV) CT Enterography

“…Most of the published clinical studies on noise reduction filters used reduced tube current to achieve images with less radiation dose (8,9,11). Despite the fact that both the reduction of tube current and tube potential cause a decrease in radiation dose, the reduction of tube potential has an important advantage: the increase in image contrast, which is more pronounced for materials with high effective atomic number, like iodine (4).…”

Dosisreduktion und Bildqualität in der MDCT des Oberbauchs: Potenzial eines adaptiven Nachverarbeitungsfilters

“…Es können lineare und nicht lineare Filter unterschieden werden, wobei sich letztere dadurch auszeichnen, dass in die Analyse eines Pixels auch die direkt benachbarten Pixel einbezogen werden. Untersuchungen mit verschiedenen nicht linearen Filtern in den letzten Jahren erbrachten ermutigende Ergebnisse [15,16] …”