• computed tomography angiography
• coronary arteries
• dual-source CT
• low radiation exposure
• photon-counting CT

• Cardiac-gated imaging techniques
• Coronary angiography
• Coronary artery disease

• aortic stenosis
• coarctation of the aorta
• computed tomography
• congenital heart disease
• left ventricular outflow obstruction
• transthoracic echocardiography.

• Child
• Humans
• Child, Preschool
• Ventricular Outflow Obstruction, Left
• Ventricular Outflow Obstruction/diagnostic imaging
• Ventricular Outflow Obstruction/congenital
• Aortic Valve
• Aortic Valve Stenosis
• Tomography, X-Ray Computed

To validate the feasibility of free-breathing, non-gated, high-pitch heart-to-brain computed tomography arteriography (CTA) in acute ischemic stroke and the capability of non-gated heart-to-brain CTA in showing cardiac anatomy.

The study protocol was approved by the institutional medical ethics review board. Free-breathing, non-gated, high-pitch heart-to-brain CTA was performed on patients with acute ischemic stroke referred for multimodal CT using a third-generation dual-source CT. Patients scheduled for ECG-triggered heart-to-brain CTA served as controls. Quantitative and/or qualitative image quality of the four cardiac chambers, left atrial appendage, interventricular and interatrial septa, carotid arteries, and coronary arteries were evaluated and compared between the two groups.

Free-breathing, non-gated, high-pitch heart-to-brain CTA was performed on 30 patients with acute ischemic stroke, whereas the control group included 31 cases. There is no significant difference in the image quality of CTAs between the two groups at cardiac chambers and carotid arteries. The image quality of coronary arteries also showed no significant difference between the two groups. The mean dose length products of CTA in the two groups were 129.1 ± 30.5 mGy cm and 121.6 ± 30.3 mGy cm, respectively. Cardiac abnormality can be shown in patients with acute ischemic stroke.

It is feasible to use free-breathing, non-gated, high-pitch heart-to-brain CTA with dual-source CT in acute ischemic stroke for cardiac etiology screening.

• CT angiography
• cardiac imaging techniques
• computed tomography
• dual-source CT
• stroke

• Bypass grafts and stents
• CT-FFR
• Coronary artery atherosclerosis
• Coronary computed tomographic angiography (CCTA)
• Vulnerable plaque

• Congenital heart disease
• Double outlet right ventricle

• Computed tomography CT
• Coronary CT angiography
• Dual energy CT
• Dual source CT

• cardiac radiosurgery
• stereotactic arrhythmia radioablation
• ventricular tachycardia

• CT angiography
• TAVI
• aorta
• dual-source CT
• high-pitch
• radiation dose

Coronary computed tomography angiography (CCTA) is now widely used in the diagnosis of coronary artery disease since it is a rapid, minimally invasive test with a diagnostic accuracy comparable to coronary angiography. However, to meet demands for increasing spatial and temporal resolution, higher x-ray radiation doses are required to circumvent the resulting increase in image noise. Exposure to high doses of ionizing radiation with CT imaging is a major health concern due to the potential risk of radiation-associated malignancy. Given its increasing use, a number of dose saving algorithms have been implemented to CCTA to minimize radiation exposure to “as low as reasonably achievable (ALARA)” without compromising diagnostic image quality.

The purpose of this review is to outline the most recent advances and current status of dose saving techniques in CCTA.

PubMed, Medline, EMBASE and Scholar databases were searched to identify feasibility studies, clinical trials, and technology guidelines on the technical advances in CT scanner hardware and reconstruction software.

Sub-millisievert (mSv) radiation doses have been reported for CCTA due to a combination of strategies such as prospective electrocardiogram-gating, high-pitch helical acquisition, tube current modulation, tube voltage reduction, heart rate reduction, and the most recent novel adaptive iterative reconstruction algorithms.

Advances in radiation dose reduction without loss of image quality justify the use of CCTA as a non-invasive alternative to coronary catheterization in the diagnosis of coronary artery disease.

• Coronary computed tomography angiography
• effective radiation dose
• image quality
• iterative reconstruction
• prospective electrocardiogram- gating
• tube current modulation
• tube voltage reduction.

• 192 × 2 dual-source computed tomography
• 64 single-source computed tomography
• Cardiovascular examinations
• Radiation dose comparison

• Cardiovascular Diseases/diagnostic imaging
• Computed Tomography Angiography/adverse effects
• Computed Tomography Angiography/instrumentation
• Computed Tomography Angiography/methods
• Coronary Angiography/adverse effects
• Coronary Angiography/instrumentation
• Coronary Angiography/methods
• Coronary Artery Disease/diagnostic imaging
• Equipment Safety
• Humans
• Multidetector Computed Tomography/adverse effects
• Multidetector Computed Tomography/instrumentation
• Multidetector Computed Tomography/methods
• Radiation Dosage
• Radiation Exposure
• Radiography, Dual-Energy Scanned Projection/adverse effects
• Radiography, Dual-Energy Scanned Projection/instrumentation
• Radiography, Dual-Energy Scanned Projection/methods
• Retrospective Studies
• Time Factors

To evaluate the image quality, radiation exposure, and means of application in a group of patients who underwent coronary computed tomography angiography (CCTA) performed with low-dose prospective electrocardiography (ECG)-triggered acquisition in which a standard sequence was added if the low-dose sequence did not allow reliable exclusion of coronary stenosis with respect to image quality.

The present study was approved by the Ethics Committee of the Faculty of Medicine, and informed consent was obtained from all patients. The authors performed a retrospective review of 256 consecutive patients referred for CCTA using dual-source CT scanner (Definition FLASH, Siemens, Germany). CCTA was performed using prospective ECG-triggered high-pitch acquisition. In patients with higher heart rates (> 65 bpm) or in whom irregular heart rates were noted prior to the scan, a subsequent CCTA was performed immediately (double flash protocol). The effective radiation dose was calculated for each patient. All images were evaluated by two independent observers for quality on a four-point scale with 1 being non-diagnostic image quality and 4 being excellent.

Mean effective whole-body dose of CCTA was 1.6 ± 0.4 mSv (range, 0.4-5.4) for the entire cardiac examination and 0.9 ± 0.3 mSv (range, 0.4-2.8) for individual prospective ECG-triggered high-pitch CCTAs. In 27 of these patients with higher heart rates or occasional premature ventricular contractions or atrial fibrillation, subsequent CCTAs were performed immediately. The average image quality score was good to excellent with less than 1% unevaluable coronary segments. The double flash protocol resulted in a fully diagnostic CCTA in all cases.

The prospective ECG-triggered high-pitch CCTA technique is feasible and promising in clinical routine with good to excellent image quality and minimal radiation dose. The double flash protocol might become a more robust tool in patients with higher heart rates or arrhythmia.

• computed tomography
• coronary CTA
• image quality
• radiation exposure

To determine the radiation dose and image quality in coronary computed tomography angiography (CCTA) using state-of-the-art dose reduction methods in unselected “real world” patients.

In this single-centre study, consecutive patients in sinus rhythm underwent CCTA for suspected coronary artery disease (CAD) using a 320-row detector CT scanner. All patients underwent the standard CT acquisition protocol at our institute (Morriston Hospital) a combination of dose saving advances including prospective electrocardiogram-gating, automated tube current modulation, tube voltage reduction, heart rate reduction, and the most recent novel adaptive iterative dose reconstruction 3D (AIDR3D) algorithm. The cohort comprised real-world patients for routine CCTA who were not selected on age, body mass index, or heart rate. Subjective image quality was graded on a 4-point scale (4 = excellent, 1 = non-diagnostic).

A total of 543 patients were included in the study with a mean body weight of 81 ± 18 kg and a pre-scan mean heart rate of 70 ± 11 beats per minute (bpm). When indicated, patients received rate-limiting medication with an oral beta-blocker followed by additional intravenous beta-blocker to achieve a heart rate below 65 bpm. The median effective radiation dose was 0.88 mSv (IQR, 0.6-1.4 mSv) derived from a Dose Length Product of 61.45 mGy.cm (IQR, 42.86-100.00 mGy.cm). This also includes what we believe to be the lowest ever-reported radiation dose for a routine clinical CCTA (0.18 mSv). The mean image quality (± SD) was 3.65 ± 0.61, with a subjective image quality score of 3 (“good”) or above for 93% of patient CCTAs.

Combining a low-dose scan protocol and AIDR3D with a 320-detector row CT scanner can provide high quality images at exceptionally low radiation dose in unselected patients being investigated for CAD.

• Effective radiation dose
• Tube voltage
• Tube current
• Iterative reconstruction
• Coronary computed tomography angiography
• Image quality
• Prospectively electrocardiogram gating

• Cardiac CT protocol
• Computed tomography angiography
• ECG gating
• Radiation exposure

• Pacemakers
• dual-energy CT
• dual-source CT
• implantable cardioverter-defibrillator (ICD)
• metal artifact reduction

• Artifacts
• Defibrillators, Implantable
• Humans
• Metals
• Pacemaker, Artificial
• Phantoms, Imaging
• Tomography, X-Ray Computed/methods

Recent studies demonstrated that sinogram affirmed iterative reconstructions (SAFIRE) can produce higher-resolution images with greater robustness for the reduction of various imaging artefacts. Eighty-five patients were prospectively evaluated and underwent a high-pitch spiral acquisition CT scan. In-stent noise, signal-to-noise ratio(SNR), stent-lumen attenuation increase ratio (SAIR), and subjective image quality score were measured and compared between the SAFIRE and Filter back projection (FBP) reconstructions. Conventional coronary angiography served as the standard of reference. In 159 evaluated stents, SAFIRE was superior to FBP with regards to in-stent noise, SNR, SAIR, and image quality score. On per-stent analysis, SAFIRE vs. FBP reconstruction yielded 85% vs. 85%sensitivity, 89% vs. 78%specificity, 73% vs. 57%positive predictive value, 95% vs. 94%negative predictive value, and 0.87 vs. 0.82 area under curve, although these improvements did not reach statistical significance (P > 0.05). However, in the subgroup of small diameter stents (≤3 mm; n = 95), specificity(82% vs. 62%), positive predictive value(66% vs. 50%) and area under curve (0.81 vs. 0.70) improved significantly (P < 0.05) with SAFIRE. SAFIRE image reconstruction can thus improve the evaluation for ISR, especially in smaller stents.

• Computed tomography
• Congenital heart disease
• Coronary artery fistula

• Adult
• Aged
• Arterio-Arterial Fistula/congenital
• Arterio-Arterial Fistula/diagnosis
• Arterio-Arterial Fistula/surgery
• China
• Coronary Vessel Anomalies/diagnosis
• Coronary Vessel Anomalies/surgery
• Coronary Vessels/diagnostic imaging
• Female
• Humans
• Male
• Middle Aged
• Preoperative Care/methods
• Pulmonary Artery/abnormalities
• Pulmonary Artery/diagnostic imaging
• Reproducibility of Results
• Tomography, X-Ray Computed/methods
• Vascular Surgical Procedures/methods

• Coronary angiography
• High-pitch spiral mode
• Percutaneous coronary intervention
• Stent

• Contrast media
• Coronary computed tomography angiography
• Image quality
• Iodine concentration
• Safety

• Computed tomography angiography
• coronary arteries
• heart rate
• high-pitch
• low radiation dose

• Aorta
• CT angiography
• Dual-source CT
• High-pitch CT

• CT
• adults
• artifacts
• lung
• thorax

• dual-energy CT
• molecular CT imaging
• spectral CT

We aimed to report the image quality, relationship between heart rate and image quality, amount of contrast agent given to the patients and radiation doses in coronary CT angiography (CTA) obtained by using high-pitch prospectively ECG-gated “Flash Spiral” technique (method A) or retrospectively ECG-gated technique (method B) using 128×2-slice dual-source CT.

A total of 110 patients who were evaluated with method A and method B technique with a 128×2-detector dual-source CT device were included in the study. Patients were divided into three groups based on their heart rates during the procedure, and a relationship between heart rate and image quality were evaluated. The relationship between heart rate, gender and radiation dose received by the patients was compared.

A total of 1760 segments were evaluated in terms of image quality. Comparison of the relationship between heart rate and image quality revealed a significant difference between heart rate <60 beats/min group and >75 beats/min group whereas <60 beats/min and 60–75 beats/min groups did not differ significantly. The average effective dose for coronary CTA was calculated as 1.11 mSv (0.47–2.01 mSv) for method A and 8.22 mSv (2.19–12.88 mSv) for method B.

Method A provided high quality images with doses as low as <1 mSv in selected patients who have low heart rates with a high negative predictive value to rule out coronary artery disease. Although method B increases the amount of effective dose, it provides high diagnostic quality images for patients who have a high heart rate and arrhythmia which makes it is difficult to obtain images.

• Coronary Angiography
• Heart Rate
• Image Enhancement
• Multidetector Computed Tomography
• Radiation Dosage
• Radiology

• Coronary angiography
• Dual source CT
• High-pitch spiral acquisition
• Image quality
• Radiation dose

• CT perfusion
• cardiac dual-energy CT
• diagnostic accuracy
• plaque characterization
• radiation dose aspects
• specifications of DECT

• Body mass index
• computed tomography (CT)
• coronary angiography
• noise

• Cardiac-Gated Imaging Techniques/methods
• Child
• Child, Preschool
• Double Outlet Right Ventricle/diagnosis
• Double Outlet Right Ventricle/diagnostic imaging
• Female
• Humans
• Infant
• Infant, Newborn
• Male
• Tomography, X-Ray Computed/methods

The aim of our study was to find out how much energy is applicable in second-generation dual source high-pitch computed tomography (CT) in imaging of the abdomen.

We examined an upper abdominal phantom using a Somatom Definition Flash CT-Scanner (Siemens, Forchheim, Germany). The study protocol consisted of a scan-series at 100 kV and 120 kV. In each scan series we started with a pitch of 3.2 and reduced it in steps of 0.2, until a pitch of 1.6 was reached. The current was adjusted to the maximum the scanner could achieve. Energy values, image noise, image quality, and radiation exposure were evaluated.

For a pitch of 3.2 the maximum applicable current was 142 mAs at 120 kV and in 100 kV the maximum applicable current was 114 mAs. For conventional abdominal imaging, current levels of 200 to 260 mAs are generally used. To achieve similar current levels, we had to decrease the pitch to 1.8 at 100 kV — at this pitch we could perform our imaging at 204 mAs. At a pitch of 2.2 in 120 kV we could apply a current of 206 mAs.

We conclude our study by stating that if there is a need for a higher current, we have to reduce the pitch. In a high-pitch dual source CT, we always have to remember where our main focus is, so we can adjust the pitch to the energy we need in the area of the body that has to be imaged, to find answers to the clinical question being raised.

• Abdominal imaging
• computer tomography
• high-pitch

• Child
• Child, Preschool
• Coronary Angiography/methods
• Echocardiography/methods
• Electrocardiography/methods
• Female
• Heart Defects, Congenital/diagnosis
• Humans
• Infant
• Male
• Prospective Studies
• Radiation Dosage
• Vascular Malformations/diagnosis

• Contrast media
• Coronary CT angiography
• Iterative reconstruction
• Low tube voltage
• Radiation dose

To investigate the impact of high pitch cardiac CT vs. retrospective ECG gated CT on the quantification of calcified vessel stenoses, with assessment of the influence of tube voltage, reconstruction kernel and heart rate.

A 4D cardiac movement phantom equipped with three different plaque phantoms (12.5%, 25% and 50% stenosis at different calcification levels), was scanned with a 128-row dual source CT scanner, applying different trigger types (gated vs. prospectively triggered high pitch), tube voltages (100-120 kV) and heart rates (50–90 beats per minute, bpm). Images were reconstructed using different standard (B26f, B46f, B70f) and iterative (I26f, I70f) convolution kernels. Absolute and relative plaque sizes were measured and statistically compared. Radiation dose associated with the different methods (gated vs. high pitch, 100 kV vs. 120 kV) were compared.

Compared to the known diameters of the phantom plaques and vessels both CT-examination techniques overestimated the degrees of stenoses. Using the high pitch CT-protocol plaques appeared larger (0.09 ± 0.31 mm, 2 ± 8 percent points, PP) in comparison to the ECG-gated CT-scans. Reducing tube voltage had a similar effect, resulting in higher grading of the same stenoses by 3 ± 8 PP. In turn, sharper convolution kernels lead to a lower grading of stenoses (differences of up to 5%). Pairwise comparison of B26f and I26f, B46f and B70f, and B70f and I70f showed differences of 0–1 ± 6–8 PP of the plaque depiction. Motion artifacts were present only at 90 bpm high pitch experiments. High-pitch protocols were associated with significantly lower radiation doses compared with the ECG-gated protocols (258.0 mGy vs. 2829.8 mGy CTDI_vol, p ≤ 0.0001).

Prospectively triggered high-pitch cardiac CT led to an overestimation of plaque diameter and degree of stenoses in a coronary phantom. This overestimation is only slight and probably negligible in a clinical situation. Even at higher heart rates high pitch CT-scanning allowed reliable measurements of plaque and vessel diameters with only slight differences compared ECG-gated protocols, although motion artifacts were present at 90 bpm using the high pitch protocols.

• DLP
• Dose recommendation
• High-pitch
• Prospective-triggered
• Radiation dose reduction