Feasibility of Weight-based Tube Voltage and Iodine Delivery Rate for Coronary Artery CT Angiography.

PURPOSE: The objective of this study was to evaluate the feasibility of weight-based tube voltage and iodine delivery rate (IDR) for coronary artery CT angiography (CCTA). METHODS: A total of 193 patients (mean age: 58 ± 12 years) with suspected coronary heart disease indicated for CCTA between May and October 2022 were prospectively enrolled. The subjects were divided into five groups according to body weight: < 60 kg, 60 - 69 kg, 70 - 79 kg, 80 - 89 kg, and ≥ 90 kg. The tube voltage and IDR settings of each group were as follows: 70 kVp/0.8 gI/s, 80 kVp/1.0 gI/s, 80 kVp/1.1 gI/s, 100 kVp/1.5 gI/s, and 100 kVp/1.5 gI/s, respectively. Objective image quality data included the CT value and standard deviation (noise) of the aortic root (AR), the proximal left anterior descending branch (LAD), and the distal right coronary artery (RCA), as well as the signal-to-noise ratio and contrast-to-noise ratio of the LAD and RCA. Subjective image quality assessment was performed based on the 18-segment model. Contrast and radiation doses, as well as effective dose (ED), were recorded. All continuous variables were compared using either the one-way ANOVA or the Kruskal-Wallis rank sum test. RESULTS: No significant differences were observed in all objective and subjective parameters of image quality between the groups (P > 0.05). However, significant differences in contrast and radiation doses were observed (P < 0.05). The contrast doses across the weight groups were 27 mL, 35 mL, 38 mL, 53 mL, and 53 mL, respectively, while the ED were 1.567 (1.30, 2.197) mSv, 1.53 (1.373, 1.78) mSv, 2.113 (1.963, 2.256) mSv, 4.22 (3.771, 4.483) mSv, and 4.786 (4.339, 5.536) mSv, respectively. CONCLUSION: Weight-based tube voltage and IDR yielded consistently high image quality, and allowed for further reduction in contrast and radiation exposure during CCTA for coronary artery diseases.

Refining the radiation and contrast medium dose in weight-grouped scanning protocols for coronary CT angiography.

PURPOSE: To refine the currently used, weight-grouped protocol for coronary computed tomography angiography (CCTA), in terms of the radiation and contrast medium dose, through clinical evaluation. METHODS: Following the current routine setting that varies between three weight groups (group A: 55-65 kg, group B: 66-75 kg, group C: 76-85 kg), three additional reduction protocols were proposed to each group, with different combinations of lowered tube voltage (70-100 kVp), tube current (100-220 mAs), and iodine delivery rate (0.8-1.5 gI/s). A total of 321 patients scheduled for CCTA due to suspected coronary artery disease were enrolled, who were randomly assigned to one of the four subgroups of settings under the corresponding weight group. The resulting objective image quality was compared by measuring the contrast-to-noise ratio and signal-to-noise ratio. Subjective image quality was graded by two radiologists using a 4-point Likert scale, on a total of 3848 segments. The optimal protocol for each weight group was determined with respect to the image quality and the applied radiation dose. RESULTS: For all three groups, no significant difference was noticed in objective images quality between subgroups of dose settings (all p > 0.05). The average score on subjective image quality was ≥3 for every subgroup, while the percentage of score 4 showed greater dependence on the setting, ranging from 83.2% to 91.5%, and was chosen to be the determining factor. The optimal dose settings were found to be 80 kVp, 150 mAs, and 1.0 gI/s for patients of 55-75 kg in weight, and 100 kVp, 170 mAs, and 1.5 gI/s for those of 76-85 kg. CONCLUSION: It is feasible to refine the currently used, weight-grouped protocol for CCTA in terms of radiation and contrast medium dose, by use of an optimization strategy where the balance between dose and image quality can be improved in a routine clinical setting.

Characteristics of monosodium urate crystal deposition in the foot in the different stages of gout by dual-energy computed tomography.

OBJECTIVE: To compare the characteristics of monosodium urate (MSU) crystal deposition at specific anatomical sites of the foot detected by dual-energy computed tomography in patients with different stages of gout. MATERIALS AND METHODS: This study included 101 patients with gout, 64 had early gout (<3 years) and 37 had late gout (>3 years). We retrospectively compared the total volumes of MSU crystals, the detection rates, and the morphology of MSU crystals at specific anatomical sites in the foot of the patients with different gout durations. RESULTS: The total volume of MSU crystals in patients with early gout was significantly smaller than that in patients with late gout (P < 0.05). The detection rates and morphology of MSU crystals in the anterior calf tendons, ankle joints, tarsometatarsal joints, and metatarsophalangeal joints differed significantly between the patients with early and late gout (P < 0.05). There were no significant differences in the detection rates of submillimeter MSU crystals at the other specific anatomical sites, except for the tendons of the anterior calf, the ankle joint, and the metatarsal joint (P > 0.05). The submillimeter MSU crystal deposition was most common in the tendons of the posterior calf, the proportions in patients with early gout and late gout were 85.9% and 70.3%. Only submillimeter deposition existed in 52 patients (81.3%) with early gout and 11 patients (29.7%) with late gout at all sites of the foot. CONCLUSION: Dual-energy computed tomography detection of submillimeter MSU crystal deposits in the foot is of great significance for the diagnosis of gout, especially along tendons.