A Comparison of the Image Quality and Radiation Dose With Routine Computed Tomography and the Latest Gemstone Spectral Imaging Combination of Different Scanning Protocols in Computed Tomography Angiography of the Kidney.

OBJECTIVE: The objective of our study was to compare the image quality and radiation dose of computed tomography angiography (CTA) of the kidney in patients with different body mass indexes using routine CT and the latest gemstone spectral imaging (GSI) combination of different scanning protocols with the adaptive statistical iterative reconstruction 2.0 algorithm. METHODS: A total of 90 patients who had undergone a CTA of the kidney were divided into 3 groups (A, B, and C), with 30 patients in each group. Group A underwent a routine CT examination, whereas groups B and C underwent GSI with different scanning protocols. All images were restructured using the adaptive statistical iterative reconstruction 2.0. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of all images were calculated when the kidney CTA was completed. Each subjective image evaluation used a 5-point scoring method and was conducted by 2 independent radiologists. The CT dose index of volume and the dose-length product were recorded, and the mean value was calculated. The dose-length product was converted to the effective dose. All data were compared with a 1-way analysis of variance. RESULTS: The SNR, CNR, and subjective image quality in group A were significantly lower than those in groups B and C (P < 0.01). There were no significant differences in SNR, CNR, and subjective image quality between groups B and C. The effective dose of group C decreased by 46.05% and 15.03% relative to those of groups A and B, respectively (P < 0.01). CONCLUSIONS: The latest GSI with different scanning protocols can more effectively reduce the radiation dose than can the routine CT scan mode for a kidney CTA while still maintaining diagnostic image quality.

CT Pulmonary Angiography Using Automatic Tube Current Modulation Combination with Different Noise Index with Iterative Reconstruction Algorithm in Different Body Mass Index: Image Quality and Radiation Dose.

RATIONALE AND OBJECTIVES: This study aimed to determine the appropriate body mass index (BMI)-dependent noise index (NI) setting in computed tomography pulmonary angiography (CTPA) with automatic tube current modulation with adaptive statistical iterative reconstruction (ASiR). MATERIALS AND METHODS: A total of 480 patients who had a CTPA were divided into group A (18.5 kg/m2 ≤ BMI < 25 kg/m2), group B (25 kg/m2 ≤ BMI < 30 kg/m2), and group C (BMI ≥ 30 kg/m2), according to their BMI values; each group had 160 patients. The three groups were further randomly divided into four subgroups: A1, A2, A3, A4; B1, B2, B3, B4; and C1, C2, C3, C4, with corresponding NI values of 26, 36, 40, and 46, respectively. All images were restructured with the ASiR algorithm, and the images with the lowest NI (26 Hounsfield units) in each group were used as reference standard. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for the pulmonary artery of each group were calculated. Subjective image quality was evaluated using a five-score method by two independent radiologists. The CT dose index of volume and dose-length product were recorded and were converted to effective dose (ED). SNR and CNR in the group A, B, and C subgroups were compared to repeated measures analysis of variance, and the subjective score, Volumetric CT dose index of volume, dose-length product, and ED were compared to one-way analysis of variance. RESULTS: For groups A and B, the SNR, CNR, and subjective scores of the images in their subgroups showed no statistical differences (P >.05). The ED in subgroups A4 and B4 was significantly lower than that in subgroups A1 (by 33.24%) and B1 (by 34.47%) (P <.01). For group C, there was no significant difference in the SNR, CNR, and the subjective image scores between subgroups C3 and C1 (P >.05). The ED in subgroup C3 was significantly lower than the ED in subgroup C1 (by 47.75%) (P <.01) CONCLUSIONS: Patient BMI-dependent NI settings that are higher than the recommended value may be used in CTPA with automatic tube current modulation and ASiR to effectively reduce radiation dose while maintaining diagnostic image quality.

A Comparison of the Image Quality and Radiation Dose Using 100-kVp Combination of Different Noise Index and 120-kVp in Computed Tomography Pulmonary Angiography.

OBJECTIVE: The objective of our study was to compare the image quality and radiation dose of computed tomography pulmonary angiography (CTPA) in patients with different body mass indexes using 100-kVp combination of different noise indexes (NIs) and 120-kVp scan protocol with the adaptive statistical iterative reconstruction 2.0 algorithm (ASiR 2.0). METHODS: A total of 120 patients who had undergone a CTPA were divided into 4 groups (A, B, C, and D), with 30 patients in each group. Group A underwent 120-kVp CT scan protocol in combination with NI = 25, while groups B, C, and D underwent 100-kVp CT scan protocol in combination with NI = 30, 35, and 40, respectively. All images were restructured using ASiR 2.0. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of all images were calculated when the CTPA was completed. Each subjective image evaluation used a 5-point scoring method and was conducted by 2 independent radiologists. The CT dose index of volume and dose-length product were recorded, and the mean value was calculated. The dose-length product was converted to the effective dose. RESULTS: There were no significant differences in SNR, CNR, and subjective image quality among the groups A, B, C, and D. The effective dose of group D decreased by 48.33% and 27.27% relative to groups A and B, respectively (P < 0.01). CONCLUSIONS: The 100-kVp CT scan protocol in combination with NI = 40 can more effectively reduce the radiation dose than can the 120-kVp CT scan protocol in combination with NI = 25 for a CTPA while still maintaining diagnostic image quality.