Evaluation of Low-kVp Low-Volume Iodinated Contrast Protocol for Coronary CT Angiography Using Retrospective ECG Gating

Objective The aim of this study was to evaluate the use of low peak kilovoltage (kVp) low-volume iodinated contrast protocol for performing coronary computed tomography (CT) angiography (CCTA) in patients using retrospective electrocardiogram (ECG) gating. Materials and Methods Hundred prospective patients undergoing CCTA were studied in two groups, A and B, using 70 kilovoltage (kV) and 120 kV protocols with half and standard intravenous volumes of injected iodinated contrast, respectively. All patients had heart rates less than 100 beats/min and body mass index (BMI) less than 31 kg/m2. Both the groups were evaluated for signal-to-noise (S/N) and contrast-to-noise (C/N) ratios along with radiation dose delivered in millisievert (mSv), and for image quality (IQ), on per patient and per segment basis. Results Patients with group A showed statistically reduced radiation dose of 1.86 mSv compared with 6.86 mSv in group B patients. Marked reduction in image noise with statistically improved S/N and C/N ratios in all coronary vessels was seen in group A. S/N ratios in group A were 20.25, 18.68, 19.04, 17.41, and 18.69 for aorta, left main, left anterior descending, right coronary, and left circumflex arteries while they were 13.34, 11.12, 10.96, 9.74, and 8.67 in group B patients. C/N ratios were also higher in all vessels in group A patients, that is, 19.48, 19.48, 19.04, 19.48, and 17.68, compared with group B patients, who had 12.43, 10.03, 9.23, 9.57, and 8.23 ratios (p < 0.0001). No significant difference in IQ per patient and per vessel was seen between both the groups. Discussion Retrospective ECG-gated low-kVp low-volume iodinated contrast protocol provides good diagnostic quality angiograms in patients with BMI up to 31 kg/m2 and with heart rates of less than 100 beats/min with three times reduced radiation dose. The reduced volume of contrast reduces the cost as well as the chance of contrast-induced nephropathy.

How Can an Updated 320 Multi Detector Computed Tomography Low Dose Protocol Help in Assessment of Coronary Heart Disease

Background Coronary artery disease (CAD) is the single most common cause of death in the developed world, responsible for about I in every 5 deaths. The morbidity, mortality, and socioeconomic importance of this disease make timely accurate diagnosis and cost-effective management of CAD of the utmost importance. The recent years showed an overall increase in the use of CT for imaging of the heart and coronary arteries, coronary CT angiography is a rapidly growing technique that offers distinct advantages over traditional imaging techniques. However, because of rapid growth of this technique, radiation dose safety has been placed under the spotlight. Integration of dosesaving techniques will go a long way in maintaining diagnostic image quality and improving patient safety. Objectives The purpose of our study is the assessment of coronary artery disease by 320 MDCT and its capabilities of maintaining the quality of images and dose reduction improving patient safety. Patients and Methods This study was performed at New Cairo Police Hospital (Radiology department) and at Center in East Cairo, From October 2018 to October 2019, a total of 39 patients who had referred for CTCA for suspicion of coronary artery disease enrolled in our prospective study. Results In this study we used MDCT 64 with retrospective ECG-gating in 25.6% of patients (10 patients) and MDCT 320 with Retrospective ECG-gating was used in 25.6% (10 patients) and with Prospective ECG-gating in 48.8% (19 patients).we compared the radiation dose between prospective ECG-gating and retrospective ECG-gating acquisition techniques among all study population by the effective dose (ED) which is calculated from the DLP of the coronary scan. The effective radiation dose (ED) median was significantly lower in the prospective ECG-gating technique (7 msv) in comparison to retrospective ECG-gating technique (23 msv). We also compared the difference in radiation dose between MDCT 320 and 64 using retrospective ECG gating acquisition technique, the median (ED) was significantly lower in the 320 MI)CT technique (20 msv) in comparison to 64 MDCT (26 msv). The last comparison was the difference Of radiation dose between patients who underwent through MDCT 320 using two different techniques (prospective and retrospective), the median effective dose was lower in the prospective ECG-gating technique (7 msv) in comparison to retrospective ECG-gating technique (20 msv) this difference is also of high statistical significant value. Conclusion Prospective ECG-Gated CT coronary angiography protocol impressively reduces effective radiation doses in comparison to retrospective ECG-gated technique on 320 MDCT and is still sensitive for diagnosing significant coronary stenosis for patients with suspected CAD. Retrospective Coronary CT angiography can be performed with 320-MDCT with less radiation doses compared to 64-MDCT.

Cardiac computed tomography imaging of a giant ascending aortic double chambers pseudoaneurysm infiltrating into the sternum

In this report we show an unusual case of a giant ascending aortic double chambers pseudoaneurysm eroding the sternum. The patient was an asymptomatic 22-year-old man who underwent CT Angiography with ECG gating and who previously underwent aortic valve replacement.

Technical principles of cardiovascular CT

This chapter covers the technical mechanisms by which CT scanners work. X-ray tube voltage is explained, and the effects of changing voltage on radiation exposure and the resultant CT image are defined. Scan pitch for both single- and multi-slice CT have their formulae given, and the effects of changing pitch are described. Both spatial and temporal resolution are discussed, and multi-segment reconstruction concepts are explained. ECG gating, including retrospective and prospective gating are covered. Finally, axial and helical scanning acquisition modes are described.

Precipitation of de novo atrial fibrillation during Shockwave Intravascular Lithotripsy® after pacing capture during the treatment of proximal right coronary artery disease: a case report

Background Shockwave Intravascular Lithotripsy® has been recently translated to the treatment of coronary artery disease with a long history of use for ureteric stones where it has been observed to have caused cardiac arrhythmias. The risk of arrhythmia with the use of this method in coronary artery disease is currently unknown. Case summary A 72-year-old man undergoing planned percutaneous intervention to a heavily calcified proximal right coronary artery (RCA) lesion using S-IVL developed pacing capture from the device and subsequently new atrial fibrillation (AF) during the procedure. The technique resulted in successful treatment of the coronary lesion and he spontaneously reverted within an hour of the procedure before discharge. Discussion We postulate the pulsed energy delivered to break apart the calcium has the capacity to cause depolarization, and therefore, affect cardiac rhythm as seen in treatment of renal stones in the past before the introduction of routine electrocardiogram (ECG) gating. In this case, the proximity of the RCA to the right atrium caused short circuiting and development of AF in a susceptible patient. Both the pacing implications and the risk of arrhythmia needs to be investigated further and the potential for ECG gating of the pulsed energy to mitigate this effect needs to be explored to enhance the safety of this technique.