CARE Dose 4D combined with sinogram-affirmed iterative reconstruction improved the image quality and reduced the radiation dose in low dose CT of the small intestine

Abstract

Objective: Multislice computed tomography (MSCT) has been used for diagnosis of small intestinal diseases. However, the radiation dose is a big problem. This study was to investigate whether CARE Dose 4D combined with sinogram-affirmed iterative reconstruction (SAFIRE) can provide better image quality at a lower dose for imaging small intestinal diseases compared to MSCT.

Methods: The noise reduction ability of SAFIRE was assessed by scanning the plain water mold using SOMATOM Definition Flash double-source spiral CT. CT images at each stage of radiography for 239 patients were obtained. The patients were divided into groups A and B were based on different tube voltage and current or the image recombination methods. The images were restructured using with filtered back projection (FBP) and SAFIRE (S1-S5). The contrast noise ratio (CNR), CT Dose index (CTDI), subjective scoring, and objective scoring were compared to obtain the best image and reformation parameters at different stages of CT.

Results: Twenty-six restructuring patterns of tube voltage and current were obtained by FBP and SAFIRE. The average radiation dose using CARE Dose 4D combined with SAFIRE (S4-S5) reduced approximately 74.85% compared to conditions where the tube voltage of 100 kV and tube current of 131 mAs for patients with MSCT small intestinal CT enterography at plain CT scan, arterial stage, small intestine, and portal venous phase. The objective and subjective scoring were all significantly different among groups A and B at each stage.

Conclusions: Combination of CARE Dose 4D and SAFIRE is shown to decrease the radiation dose while maintaining image quality.

Keywords: CARE Dose 4D; SAFIRE; image quality; radiation dose; small intestinal diseases.

Figure 1

The contrast noise ratio (CNR) of the image at each stage via multislice CT enterography. CNR = (CT _{blood vessels} − CT_muscle)/SD_muscle.

Figure 2

The reconstructed images which was made by FBP under the tube voltage of 120 kV and tube current of 200 mAs (patient: male, 46 yr, BMI = 21.2). (a) The reconstructed images which was made by FBP under the tube voltage of 100 kV and tube current of 131 mAs (patient: male, 46 yr, BMI = 21.2). (b–g). The reconstructed images which was made by SAFIR (S1–S5) under the tube voltage of 100 kV and tube current of 131 mAs (patient: male, 46 yr, BMI = 21.2). BMI, body mass index.

Figure 3

The MSCT radiography of small intestine under different tube voltage and current. (a). The images was reconstructed using FBP under the tube voltage of 120 kV and tube current of 200 mAs at arterial phase (patient A: male, 54 yr, BMI = 21.6). (b)The images was reconstructed by SAFIRE 4 and collected by CARE Dose 4D under the tube voltage of 100 kV and tube current of 295 mAs at arterial phase (patient B: male, 56 yr BMI = 21.3). (c) The images was reconstructed by SAFIRE 4 and collected by CARE Dose 4D under the tube voltage of 100 kV and tube current of 262 mAs at arterial phase (patient C: male, 54 yr, BMI = 21.4). (d) The images was reconstructed by SAFIRE 4 and collected by CARE Dose 4D under the tube voltage of 100 kV and tube current of 230 mAs at arterial phase (patient D: male, 53 yr, BMI = 21.3). (e) The images was reconstructed by SAFIRE 4 and collected by CARE Dose 4D under the tube voltage of 100 kV and tube current of 196 mAs at arterial phase (patient E: male, 55 yr, BMI = 21.7). (f) The images was reconstructed by SAFIRE 4 and collected by CARE Dose 4D under the tube voltage of 100 kV and tube current of 164 mAs at arterial phase (patient F: male, 52 yr, BMI = 21.5). (g) The images was reconstructed by SAFIRE 4 and collected by CARE Dose 4D under the tube voltage of 100 kV and tube current of 131 mAs at arterial phase (patient G: male, 56 yr, BMI = 21.2). (h) The images was reconstructed by SAFIRE 4 and collected by CARE Dose 4D under the tube voltage of 100 kV and tube current of 98 mAs at arterial phase (patient H: male, 53 yr, BMI = 21.3). (i) The images was reconstructed by SAFIRE 4 and collected by CARE Dose 4D under the tube voltage of 80 kV and tube current of 207 mAs at arterial phase (patient I: male, 55 yr, BMI = 21.4). BMI, body mass index

Figure 4

The changes of CTDI and CNR in groups under different scan conditions (a) and reconfiguration method (b) A1‐control group (CG), 120 Kv, 200 mAs, FBP; A2–100 kV, 295 mAs; A3–100 kV, 262 mAs; A4–100 kV, 230 mAs; A5–100 kV, 196 mAs; A6–100 kV, 164 mAs; A7–100 kV, 131 mAs; A8–100 kV, 98 mAs; A9–80 kV, 275 mAs. CG‐control group; FBP: B0; S1: SAFIRE, B1; S2: SAFIRE, B2; S3: SAFIRE, B3; S4: SAFIRE, B4; S5: SAFIRE, B5.