Application of ASiR in combination with noise index in the chest CT examination of preschool-age children

Abstract

Purpose: To evaluate the application of adaptive statistical iterative reconstruction (ASIR) for chest CT scans of preschool-age children.

Method: Sixty children, ages 0 to < 1, 1 to < 3, and 3 to < 6 years, who underwent CT non-contrast-enhanced and enhanced scans were included. The non-contrast-enhanced scan sequences were performed with noise indexes (NIs) of 11, 14, and 16 for the 0 to < 1, 1 to < 3, and 3 to < 6 year age groups, respectively. Collected data were reconstructed using ASIR in increments of 10%, ranging from 0 to 100%, to generate 11 image groups. The signal-to-noise ratio, image noise, and other features of images obtained using ASIR with different weights were compared and analyzed. The best weight ranges for ASIR of chest CT scans of children at different ages within the range of 0-6 years were obtained. Enhanced scan sequence: The NI default was 9, and the data were subjected to the filtered back projection reconstruction algorithm. All other scanning parameters were the same as those used in the non-contrast-enhanced scan sequence.

Results: In the 0 to < 1 year group, the image qualities were scored as 3 or above with ASIR weights of 50% for the lung window and 40% for the mediastinal window; in the 1 to < 3 year group, the image qualities were scored as 3 or above with ASIR weights of 60% for the lung window and 50% for the mediastinal window; in the 3 to < 6 year group, the image qualities were scored as 3 or above with ASIR weights of 70% for the lung window and 60% for the mediastinal window.

Conclusion: For low-dose chest CT scans of preschool-age children, application of the ASIR technique significantly improved image quality and reduced image noise. The optimum weights of image ASIR were 50%, 60%, and 70% for the lung window and 40%, 50%, and 60% for the mediastinal window for the 0 to < 1, 1 to < 3, and 3 to < 6 year groups, respectively.

Keywords: Adaptive statistical iterative reconstruction; Chest; Children; Noise index; X-ray computed tomography.