Objective:To evaluate the efficacy of the “double-low” scanning protocol (low tube voltage and low-concentration contrast agent) combined with the artificial intelligence iterative reconstruction (AIIR) algorithm for abdominal CT enhancement in patients with obesity and to identify the optimal AIIR reconstruction algorithm level.Methods:From April 2024 to July 2024, patients with a body mass index≥30.00 kg/m2 who underwent abdominal CT enhancement at the Affiliated Hospital of Hebei University were prospectively included. All patients were randomly assigned to groups A or B. Patients in Group A accepted the conventional scanning protocol (automatic tube voltage selection and a contrast agent concentration of 350 mg/ml) with reconstruction using the Karl 3D iterative reconstruction algorithm at levels 3-5. The “double-low” protocol (a fixed tube voltage of 80 kVp and a contrast agent concentration of 320 mg/ml) with AIIR algorithm reconstruction at levels 1-5 were performed in Group B. CT values and image noises were measured, including the right posterior liver lobe at the level of the first porta hepatis and subcutaneous fat at the third lumbar level during arterial and portal venous phases, abdominal aorta at the third lumbar vertebra during the arterial phase, and portal vein trunk during the portal-venous-phase. Radiation dose, total iodine intake, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and subjective image quality scores were recorded. The optimal reconstruction levels for arterial-phase and portal-venous-phase images were identified for each group by repeatedly measured ANOVA. The figure of merit (FOM) was calculated for the best images in both groups, and comparisons were made in terms of image quality, radiation dose, and iodine intake using an unpaired t-test or Wilcoxon test. Results:Overall, 150 patients with obesity were collected, and each group included 75 cases. In group A, compared with levels 3 and 4 ( P<0.001), the Karl 3D level 5 algorithm yielded significantly higher SNR, CNR values, and subjective scores, designating level 5 as the optimal reconstruction level. In group B, the AIIR level 4 algorithm achieved higher SNR and CNR values than level 5 and achieved higher subjective scores than levels 3 and 5 ( P<0.001), which means that level 4 was the optimal reconstruction level. Images reconstructed with AIIR level 4 in group B exhibited significantly higher CT, SNR, CNR, FOM values, and subjective scores than those reconstructed with Karl 3D level 5 in group A ( P<0.001). Compared with group A, the volume CT dose index values, dose-length product, and size-specific dose estimate based on water equivalent diameter in Group B were reduced by 56.75%, 58.29%, and 56, 71% during the arterial phase, and 56.70%, 58.27%, and 56.88% during the portal venous phase, respectively. Total iodine intake was significantly reduced by 10.71% in group B ( P<0.001). Conclusions:The “double-low” scanning protocol combined with AIIR algorithm significantly reduced radiation dose and iodine intake during abdominal CT enhancement in patients with obesity, without compromising image details, increasing noise, or altering image quality. AIIR level 4 was the optimal image reconstruction level for arterial-phase and portal-venous-phase in obese patients.

Objective:To evaluate the efficacy of the “double-low” scanning protocol (low tube voltage and low-concentration contrast agent) combined with the artificial intelligence iterative reconstruction (AIIR) algorithm for abdominal CT enhancement in patients with obesity and to identify the optimal AIIR reconstruction algorithm level.Methods:From April 2024 to July 2024, patients with a body mass index≥30.00 kg/m2 who underwent abdominal CT enhancement at the Affiliated Hospital of Hebei University were prospectively included. All patients were randomly assigned to groups A or B. Patients in Group A accepted the conventional scanning protocol (automatic tube voltage selection and a contrast agent concentration of 350 mg/ml) with reconstruction using the Karl 3D iterative reconstruction algorithm at levels 3-5. The “double-low” protocol (a fixed tube voltage of 80 kVp and a contrast agent concentration of 320 mg/ml) with AIIR algorithm reconstruction at levels 1-5 were performed in Group B. CT values and image noises were measured, including the right posterior liver lobe at the level of the first porta hepatis and subcutaneous fat at the third lumbar level during arterial and portal venous phases, abdominal aorta at the third lumbar vertebra during the arterial phase, and portal vein trunk during the portal-venous-phase. Radiation dose, total iodine intake, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and subjective image quality scores were recorded. The optimal reconstruction levels for arterial-phase and portal-venous-phase images were identified for each group by repeatedly measured ANOVA. The figure of merit (FOM) was calculated for the best images in both groups, and comparisons were made in terms of image quality, radiation dose, and iodine intake using an unpaired t-test or Wilcoxon test. Results:Overall, 150 patients with obesity were collected, and each group included 75 cases. In group A, compared with levels 3 and 4 ( P<0.001), the Karl 3D level 5 algorithm yielded significantly higher SNR, CNR values, and subjective scores, designating level 5 as the optimal reconstruction level. In group B, the AIIR level 4 algorithm achieved higher SNR and CNR values than level 5 and achieved higher subjective scores than levels 3 and 5 ( P<0.001), which means that level 4 was the optimal reconstruction level. Images reconstructed with AIIR level 4 in group B exhibited significantly higher CT, SNR, CNR, FOM values, and subjective scores than those reconstructed with Karl 3D level 5 in group A ( P<0.001). Compared with group A, the volume CT dose index values, dose-length product, and size-specific dose estimate based on water equivalent diameter in Group B were reduced by 56.75%, 58.29%, and 56, 71% during the arterial phase, and 56.70%, 58.27%, and 56.88% during the portal venous phase, respectively. Total iodine intake was significantly reduced by 10.71% in group B ( P<0.001). Conclusions:The “double-low” scanning protocol combined with AIIR algorithm significantly reduced radiation dose and iodine intake during abdominal CT enhancement in patients with obesity, without compromising image details, increasing noise, or altering image quality. AIIR level 4 was the optimal image reconstruction level for arterial-phase and portal-venous-phase in obese patients.