Coronary CT angiography by modifying tube voltage and contrast medium concentration: Evaluation of image quality and radiation dose

Artificial Intelligence Algorithm-Based Computed Tomography Image in Assessment of Acute Renal Insufficiency of Patients Undergoing Percutaneous Coronary Intervention

This study was aimed to analyze the changes in renal function of patients undergoing percutaneous coronary intervention (PCI) surgery and the characteristics of their computed tomography (CT) image based on artificial intelligence algorithms. In this study, 104 patients with coronary atherosclerotic heart disease (CAHD) were treated as the research objects. They were divided into an experimental group (patients who underwent CAG and PCI within 1 week after enhanced coronary CT (ECCT)) and the control group (patients who underwent CAG and PCI within 1-3 weeks after ECCT). Renal imaging scans of patients were performed by CT based on discrete inseparable shear transform (DNST) optimized algorithm, which was named as O-DNST. The results showed that the serum creatinine (Scr), blood urea nitrogen (BUN), and urine protein (UP) levels of patients in the experimental group were significantly higher than those of the control group 24-72 hours after surgery, while the levels of endogenous creatinine clearance (Ccr) and estimated glomerular filtration rate (eGFR) were significantly lower than those of the control group (P < 0.05). The levels of β2 microglobulin (β2-MG), C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor (TNF-α) in the experimental group were significantly higher than those in the control group 24-72 hours after surgery (P < 0.05). The incidence of contrast-induced nephropathy (CIN) in the experimental group (15.38%) was significantly higher than that in the control group (5.8%), and the difference was statistically significant (P < 0.05). The results showed that repeated application of contrast agent in a short period of time can promote the increase of serum inflammation levels in PCI patients, which may be a risk factor for CIN in PCI patients.

Comparison of image quality and radiation dose using different pre-ASiR-V and post-ASiR-V levels in coronary computed tomography angiography

OBJECTIVE

To determine the optimal pre-adaptive and post-adaptive level statistical iterative reconstruction V (ASiR-V) for improving image quality and reducing radiation dose in coronary computed tomography angiography (CCTA).

METHODS

The study was divided into two parts. In part I, 150 patients for CCTA were prospectively enrolled and randomly divided into 5 groups (A, B, C, D, and E) with progressive scanning from 40% to 80% pre-ASiR-V with 10% intervals and reconstructing with 70% post-ASiR-V. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective image quality was assessed using a 5-point scale. The CT dose index volume (CTDIvol) and dose-length product (DLP) of each patient were recorded and the effective radiation dose (ED) was calculated after statistical analysis by optimizing for the best pre-ASiR-V value with the lowest radiation dose while maintaining overall image quality. In part II, the images were reconstructed with the recommended optimal pre-ASiR-V values in part I (D group) and 40%-90% of post-ASiR-V. The reconstruction group (D group) was divided into 6 subgroups (interval 10%, D0:40% post-ASiR-V, D1:50% post - ASiR-V, D2:60% post-ASiR-V, D3:70% post-ASiR-V, D4:80% post-ASiR-V, and D5:90% post-ASiR-V).The SNR and CNR of D0-D5 subgroups were calculated and analyzed using one-way analysis of variance, and the consistency of the subjective scores used the k test.

RESULTS

There was no significant difference in the SNRs, CNRs, and image quality scores among A, B, C, and D groups (P > 0.05). The SNR, CNR, and image quality scores of the E group were lower than those of the A, B, C, and D groups (P < 0.05). The mean EDs in the B, C, and D groups were reduced by 7.01%, 13.37%, and 18.87%, respectively, when compared with that of the A group. The SNR and CNR of the D4-D5 subgroups were higher than the D0-D3 subgroups, and the image quality scores of the D4 subgroups were higher than the other subgroups (P < 0.05).

CONCLUSION

The wide-detector combined with 70% pre-ASiR-V and 80% post-ASiR-V significantly reduces the radiation dose of CCTA while maintaining overall image quality as compared with the manufacture's recommendation of 40% pre-ASiR-V.

Japanese Survey of Radiation Dose Associated With Coronary Computed Tomography Angiography - 2013 Data From a Multicenter Registry in Daily Practice

BACKGROUND

Although coronary computed tomography angiography (CTA) is frequently used for identifying coronary artery disease, no studies have investigated the radiation dose in detail in Japan. The aim of this study was to estimate the radiation dose of coronary CTA in Japanese clinical practice and to identify the independent predictors associated with radiation dose.Methods and Results:A multicenter, retrospective, observational study (54 institutions) was conducted for estimating the radiation dose of coronary CTA in 2,469 patients between January and December 2013. Independent predictors associated with radiation dose were investigated on linear regression analysis. Median dose-length product (DLP) was 809.0 mGy·cm (IQR, 350.0-1,368.8 mGy·cm), corresponding to an estimated radiation dose of 11 mSv. The DLP per site significantly differed between institutions (median DLP per site, 92-2,131 mGy·cm; P<0.05). Independent predictors associated with radiation dose on multivariable linear regression were body weight, heart rate, non-stable sinus rhythm, scan length, tube voltage setting, electrocardiogram (ECG)-gated scanning protocol, and the image reconstruction technique (P<0.05 each).

CONCLUSIONS

The coronary CTA radiation dose was relatively high in 2013, and it varied significantly between institutions. Effective strategies for radiation dose reduction were low tube voltage ≤100 kVp, retrospective ECG-gated scanning with dose modulation technique, prospective ECG-gated scanning, and the iterative reconstruction technique.