Coronary artery disease (CAD) is the leading cause of death globally, resulting from the pathological dysfunction of the coronary arteries. It occurs when changes in the arterial walls lead to the accumulation of atherosclerotic plaques, causing narrowing and constriction of the vascular lumen, ultimately limiting blood flow[15]. For individuals with CAD, early diagnosis and treatment are essential to improve their chances of survival. In recent years, Coronary Computed Tomography Angiography (CCTA) has gained widespread use in the diagnosis of coronary artery disease due to its rapid and minimally invasive nature[14]. However, the parameters associated with CCTA examinations, including injection rates, iodinated contrast agent volumes, and radiation doses, have consistently been a focal point of clinical concern[16].In the process of conducting CCTA examinations, it is imperative to reduce the potential adverse effects on patients by ensuring image quality while lowering the injection rate of iodinated contrast agents, reducing their volume, and minimizing radiation exposure. This requires careful consideration to balance the trade-offs between image quality and patient safety[17][18].
In this study, we employed the "Three-Low" technique, which involves low injection rates, low iodinated contrast agent volumes, and low radiation doses in the scan protocol. This approach offers several advantages:
1、Low Iodinated Contrast Agent Injection Rate to Reduce the Risk of Contrast Agent Leakage:
Achieving the optimal iodinated contrast agent application scheme is critical in CCTA examinations. The diagnostic capacity for coronary artery disease primarily depends on the optimal opacification of the small coronary blood vessels[21]. The rapid intravenous injection of a large volume of high-concentration iodinated contrast agent is necessary for this purpose. However, due to the high concentration and viscosity of iodinated contrast agents, rapid injection over a short duration can lead to vascular damage and the potential for leakage[19]. Adverse reactions to iodinated contrast agents are common risk factors for developing contrast-induced encephalopathy (CIE)[20]. Fortunately, in most cases, iodinated contrast agent extravasation results in mild symptoms such as redness, swelling, local erythema, and pain. In rare instances, severe extravasation can lead to skin blistering, tissue necrosis, and, in extremely rare cases, compartment syndrome[22]. Therefore, adopting a low injection rate is crucial to reduce extravasation risk and minimize adverse reactions in patients. The pre-experimental BMI ranged from 20 to 25. In the injection parameters, the iodine delivery rate (IDR) is a critical factor in vascular attenuation. To address this, we designed a stepwise, low iodine delivery rate injection scheme tailored to variations in BMI. The experimental group exhibited satisfactory image quality, consistent with our expectations. Compared to the control group, significant reductions in attenuation were observed in the root of the aorta and the three major coronary vessel branches. The increased number of ideal vessels achieved our study objectives.
2、The use of a low iodinated contrast agent volume offers several benefits. It not only reduces the risk of allergic reactions but also serves as a preventive measure against acute kidney injury and contrast-induced nephropathy:
CCTA injection protocols are typically tailored to individual patient characteristics, and reducing the iodinated contrast agent volume has the potential to prevent adverse effects, including allergic reactions and acute kidney injury, associated with high contrast agent doses[25]. While CT has become a rapid and efficient diagnostic tool for coronary artery disease in recent years, high doses of contrast agents can increase the risk of acute kidney injury and contrast-induced nephropathy. It has been well-documented that the significant side effects of iodinated contrast agents, due to their high concentration and viscosity, occur after intravenous and arterial administration, especially in high-risk patients, with acute kidney injury incidence rates ranging from 25% to 50% [23][24]. Therefore, the extensive use of iodinated contrast agents can have a severe impact on the physical and mental health of patients. In our study, the contrast agent dose was reduced from 45-50ml to 35-40ml, representing an 11.1% reduction in dose. The iodine intake was decreased from 18.88±0.70 to 15.07±0.62, resulting in a 9.1% reduction in iodine intake for patients. This further helps to prevent acute kidney injury and the development of contrast-induced nephropathy in patients.
3、Low radiation dosage can help mitigate the harm caused by ionizing radiation to the human body.
Humans are consistently exposed to various forms of radiation, and most hospitals around the world use radiation for diagnosing or treating cancer. While this imaging technology has its benefits, there has been ongoing controversy regarding the potential cancer risks associated with these studies[26]. Research has shown that excessive ionizing radiation can lead to cellular damage and increase the risk of cancer, with the risk escalating as the radiation dose increases. Therefore, higher doses are associated with greater risks[27].
4、Enhancing image quality is crucial for improving the diagnosis of medical conditions.
The research findings suggest that using a lower tube voltage (100KV) in the CCTA protocol results in increased vascular enhancement and provides a similar signal-to-noise ratio (SNR) compared to the traditional 120KV approach. Furthermore, it reduces radiation exposure by 50% in contrast to the 120KV method [29]. Lower tube voltage can also enhance the contrast of iodine in the images because the attenuation coefficient of iodine-based contrast increases at lower X-ray photon energy, allowing the contrast agent to absorb lower-energy X-rays more effectively and thus improving the overall image quality of the CCTA [28]as shown in the figure1-2.In this study, the tube voltage was lowered from the traditional 120KV to 100KV, and the results indicated that the experimental group had superior CT values for LAD, LCX, RCA, and aortic CT values compared to the control group.as shown in the figure3-4. Additionally, the experimental group exhibited a higher SNR, indicative of better image quality, in contrast to the control group. However, it's worth noting that using lower tube voltage led to an increase in background noise in the images. This increase in noise had a relatively minor impact on vascular imaging but a more significant effect on soft tissue imaging. Therefore, the 100KV protocol is considered to offer better overall diagnostic image quality and is suitable for conducting CCTA.
This study has several limitations:1、The study focused on individuals with normal BMI (20-25 kg/m²), and the impact of lower tube voltage techniques (such as 80KV) on individuals with lower BMI or higher BMI was not investigated. Further research is needed to assess whether different tube voltage settings are suitable for patients with varying BMI.2、The sample sizes in each group were relatively small. Conducting larger-scale studies with more participants would provide stronger and more conclusive evidence regarding the effectiveness of the "Triple-Low" technique in different patient populations.3、The study did not specifically address the impact of heart rates greater than or equal to 70 beats per minute on image quality. This is an important factor, as high heart rates can affect image quality in cardiac imaging. Future studies may explore this aspect to provide a more comprehensive understanding of the technique's applicability.
Addressing these limitations in future research can further validate the findings and provide more comprehensive insights into the use of the "Triple-Low" technique in CCTA.
In summary, the use of the "Triple-Low" technique in performing CCTA scans has several benefits. It increases the success rate of CCTA scans in patients with poor vascular conditions, reduces the occurrence of iodine contrast agent extravasation, minimizes the risk of allergic reactions, prevents acute kidney injury and contrast-induced nephropathy, and lowers the potential harm of ionizing radiation to the human body. Additionally, the "Triple-Low" technique enhances image quality and improves disease diagnosis. These findings support the clinical application and wider adoption of the "Triple-Low" technique in CCTA procedures.