Evaluate of the effect of low tube voltage on the radiation dosage using 640-slice coronary CT angiography

More sustainable use of iodinated contrast media - Why?

OBJECTIVES

Based on a narrative review of the literature to 1) assess the need for and 2) report methods to help deliver a sustainable approach to iodinated contrast media (ICM) administration.

KEY FINDINGS

Acute ICM shortages have been noted in the literature. As demand for contrast-enhanced imaging continues to increase and access to raw materials becomes more limited, such events may increase. Evidence from the literature has documented a range of iodinated contrast reduction strategies. These include individualised contrast-media dosing, multi-dose bulk ICM vials, switching to alternative modalities or the increased use of non-contrast examinations. The optimisation of imaging parameters, the use of saline chasers, and alternative contrast agents should be further considered. Given the rising concerns regarding the presence and effects of ICMs in waste and drinking water, further consideration of strategies for managing waste and excreted ICMs are starting to emerge.

CONCLUSIONS

Sustainable ICM practices are needed to help avoid supply shortages and to help protect our environment. Such practices must be led and supported locally, nationally, and internationally. Sustainable ICM practices must be reflected within professional Standards of Proficiencies and be adopted by all members of the multidisciplinary team.

IMPLICATIONS FOR PRACTICE

Changes to working practices surrounding the sustainable use of ICMs will likely become commonplace. New methods to ensure optimised ICM dosage with minimal wastage will be more heavily featured in departmental practices. Correct disposal of waste and excreted ICMs will also form part of future changes to practice.

Effects of combining multiple dose reduction techniques on coronary computed tomography angiography

BACKGROUND

Coronary computed tomography angiography (CCTA) is the preferred non-invasive examination method for coronary heart disease. However, the radiation from computed tomography has become a concern since public awareness of radiation hazards continue to increase.

AIM

To explore the value of multiple dose reduction techniques for CCTA.

METHODS

Consecutive normal and overweight patients were prospectively divided into two groups: Group A₁, patients who received multiple dose reduction scans (n = 82); and group A₂, patients who received conventional scans (n = 39). The scan parameters for group A₁ were as follows: Isocentric scan, tube voltage = 80 kV, and tube current control using 80% smart milliampere. The scan parameters for group A₂ were as follows: Normal position, tube voltage = 100 kV, and smart milliampere.

RESULTS

The average effective doses (EDs) for groups A₁ and A₂ were 1.13 ± 0.35 and 3.36 ± 1.30 mSv, respectively. There was a statistically significant difference in ED between the two groups (P < 0.01). Furthermore, noise was significantly lower, and both signal-to-noise ratio and contrast signal-to-noise ratio were higher in group A₂ when compared to group A₁ (P < 0.01). Moreover, the subjective image quality (IQ) scores were excellent in both groups, in which there was no significant difference in subjective IQ score between the two groups (P = 0.12).

CONCLUSION

Multiple dose reduction scan techniques can significantly decrease the ED of patients receiving CCTA examinations for clinical diagnosis.

Association between magnetic resonance imaging of carotid artery and coronary stenosis detected by computed tomography angiography

OBJECTIVE

To investigate the correlation between carotid artery stenosis (CAS) measured by magnetic resonance imaging (MRI) and the coronary stenosis (CS) determined by computed tomography angiography (CTA).

METHODS

In this prospective study, 42 subjects diagnosed with coronary artery disease (CAD) underwent MRI and CTA examinations. The severity degree and number of CAS, the score, detection rate and type of carotid plaque, and also the severity degree and number of CS were assessed. Spearman's rank correlation test was used to evaluate the correlation between CAS and CS.

RESULTS

CS was detected in 42 (100%) subjects, while CAS was detected in 36 (85.7%) subjects. Distribution of CAS severity grades in multiple-vessel group was significantly different from other groups, which with more moderate and severe stenosis (p < 0.05). A positive and significant correlation between the CAS severity and CS severity (r = 0.612, p < 0.05), and the number of involved coronary vessels (r = 0.572, p < 0.05) were observed, respectively. Both detection rate (r = 0.587, p < 0.05) and score (r = 0.735, p < 0.05) of carotid plaque showed a good correlation with the number of involved coronary vessels. After carotid MRI, 71 carotid plaques were detected in 42 subjects, with an incidence rate of 9.9% in subjects with mild CS, 18.3% in moderate CS and 71.8% in severe CS.

CONCLUSION

Correlation between CAS measured by MRI and CS determined by CTA was identified in present study. These results indicated that the non-invasive CAS evaluation employing the MRI may be clinically useful for the assessment of CS.

Application of Low Tube Potentials in CCTA: Results From the PROTECTION VI Study

OBJECTIVES

The aim of this study was to assess the use of low tube potentials for coronary computed tomography angiography (CCTA) in worldwide clinical practice and its influence on radiation exposure, contrast agent volume, and image quality.

BACKGROUND

CCTA is frequently used in clinical practice. Lowering of tube potential is a potent method to reduce radiation exposure and to economize contrast agent volume.

METHODS

CCTAs of 4,006 patients from 61 international study sites were analyzed regarding very-low (≤80 kVp), low (90 to 100 kVp), conventional (110 to 120 kVp), and high (≥130 kVp) tube potentials. The impact on dose-length product (DLP) and contrast agent volume was analyzed. Image quality was determined by evaluation of the diagnostic applicability and assessment of the objective image parameters signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR).

RESULTS

When compared with conventional tube potentials, low tube potentials were used in 56% of CCTAs (≤80 kVp: 9%; 90 to 100 kVp: 47%), which varied among sites from 0% to 100%. Tube potential reduction was associated with low-cardiovascular risk profile, low body mass index (BMI), and new-generation scanners. Median radiation exposure was lowered by 68% or 50% and median contrast agent volume by 25% or 13% for tube potential protocols of ≤80 kVp or 90 to 100 kVp when compared with conventional tube potentials, respectively (all p < 0.001). With the use of lower tube potentials, the frequency of diagnostic scans was maintained (p = 0.41), whereas SNR and CNR significantly improved (both p < 0.001). Considering BMI eligibility criteria, 58% (n = 946) of conventionally scanned patients would have been suitable for low tube potential protocols, and 44% (n = 831) of patients scanned with 90 to 100 kVp would have been eligible for very-low tube potential CCTA imaging of ≤80 kVp.

CONCLUSIONS

This large international registry confirms the feasibility of tube potential reduction in clinical practice leading to lower radiation exposure and lower contrast volumes. The current registry also demonstrates that this strategy is still underused in daily practice. (PROspective multicenter registry on radiaTion dose Estimates of cardiac CT angIOgraphy iN daily practice in 2017 [PROTECTION-VI]; NCT02996903).