Saving Dose in Triple-Rule-Out Computed Tomography Examination Using a High-Pitch Dual Spiral Technique:

Comparison of Triple-Rule-Out Prospectively ECG-triggered Systolic and Diastolic Acquisition Protocol in Patients With Acute Chest Pain

PURPOSE

The purpose of this study was to compare image quality and coronary interpretability of triple-rule-out systolic and diastolic protocols in patients with acute chest pain.

MATERIALS AND METHODS

From March 2016 to October 2017 the authors prospectively enrolled patients with undifferentiated acute chest pain, who were at low to intermediate cardiovascular risk. Those with heart rate >75 bpm underwent a systolic prospectively triggered acquisition (systolic triggering [ST]), and in those with ≤75 bpm, end-diastolic triggering (DT) was instead performed. Examinations were evaluated for coronary artery disease, aortic dissection, and pulmonary embolism. Image quality was assessed using a Likert scale. Coronary arteries interpretability was evaluated both on a per-vessel and a per segment basis. The occurrence of major adverse cardiovascular events was investigated.

RESULTS

The final study population was 189 patients. Fifty-two patients (27.5%) underwent systolic acquisition and 137 (72.5%) underwent diastolic acquisition. No significant differences in overall image quality were observed between DT and ST groups (median score 5 [interquartile ranges 4 to 5] vs. 4 [interquartile ranges 4 to 5], P =0.074). Although both DT and ST protocols showed low percentages of noninterpretable coronary arteries on a per-vessel (1.5% and 6.7%, respectively) and per-segment analysis (1% and 4.7%, respectively), these percentages resulted significantly higher for ST groups ( P <0.001). Obstructive coronary stenosis was observed in 18 patients. Only one case of pulmonary embolism was diagnosed and no cases of aortic dissection were found in our population. No death or major adverse cardiovascular events were observed during follow-up among the 2 groups.

CONCLUSIONS

Results showed that triple-rule-out computed tomography angiography is a reliable technique in patients with acute chest pain and that an ST acquisition protocol could be considered an alternative acquisition protocol in patients with higher heart rate, reaching a good image quality.

Diagnostic Accuracy of Coronary Artery Occlusion and Myocardial Perfusion Defect on Non-Gated Enhanced Chest CT in Predicting Acute Myocardial Infarction

The purpose of this study was to evaluate the diagnostic accuracy of coronary artery occlusion (CAO) and myocardial perfusion defect (MPD) identified on non-gated enhanced chest CT in patients with acute myocardial infarction (AMI). We retrospectively assessed 99 patients with AMI (group 1, n = 33) and without AMI (group 2, n = 66) who underwent non-gated chest CT. We analyzed the presence of MPD and CAO on non-gated chest CT. MPD on the CT was categorized using a three-point scale (0 = no definite MPD; 1 = probable artifact or questionable MPD; 2 = probable MPD). Presence of CAO was defined as an abrupt change of contrast enhancement in a coronary artery segment with no or minimal coronary motion on the CT. There were 42.4% and 12.1% patients with probable MPD (p = 0.002), and 18.2% and 0% patients with CAO (p = 0.001) in groups 1 and 2, respectively. Probable MPD alone and simultaneous presence of CAO and probable MPD to predict AMI resulted in sensitivity, specificity, negative predictive value, and positive predictive valve of 42.4%, 87.9%, 75.3%, and 63.6%, respectively, and 12.1%, 100%, 69.5%, and 100%, respectively. In conclusion, probable MPD alone on non-gated chest CT demonstrated a relatively low sensitivity, high specificity, and modest positive predictive value for the prediction of AMI on non-gated enhanced chest CT. Although it is rare, simultaneous presence of CAO and probable MPD had a high positive predictive value to predict AMI on non-gated enhanced chest CT.

Clinical Applications of Wide-Detector CT Scanners for Cardiothoracic Imaging: An Update

Technical developments in multidetector computed tomography (CT) have increased the number of detector rows on the z-axis, and 16-cm wide-area-coverage CT scanners have enabled volumetric scanning of the entire heart. Beyond coronary arterial imaging, such innovations offer several advantages during clinical imaging in the cardiothoracic area. The wide-detector CT scanner markedly reduces the image acquisition time to less than 1 second for coronary CT angiography, thereby decreasing the volume of contrast material and radiation dose required for the examination. It also eliminates stair-step artifacts, allowing robust improvements in myocardial function and perfusion imaging. Additionally, new imaging techniques for the cardiothoracic area, including subtraction imaging and free-breathing scans, have been developed and further improved by using the wide-detector CT scanner. This article investigates the technical developments in wide-detector CT scanners, summarizes their clinical applications in the cardiothoracic area, and provides a review of the recent literature.

High-pitch Dual-source CT Angiography before TAVI - the Value of ECG Gating

PURPOSE

To investigate image quality, and radiation dose between ECG-gated singlesource and dual-source CT Angiography (CTA) protocols for planning of Trans-catheter Aortic Valve Implantation (TAVI) with a reference non ECG-gated single-source protocol.

METHODS

A total of 120 patients were included in four groups: Non ECG-gated single-source (SS), ECG-gated single-source (SSECG), ECG-gated dual-source high-pitch (DSECG), or non-ECG-gated dual-source high-pitch mode (DS). Qualitative image quality of the aortic annulus, aortic valve, and coronary ostia as well as presence of motion or stair-step artefacts of the thoracic aorta were independently assessed by two readers. Quantitative image quality was assessed to calculate contrast to noise ratio.

RESULTS

Subjective and objective scoring of motion artefacts was significantly reduced in SSECG, DSECG and DS (p= 0.010). The imaging length was comparable between groups. Aortic annulus, aortic valve, and coronary ostia were reliably evaluable in all patients with SSECG, DSECG and DS protocols.

CONCLUSION

High-pitch, dual-source CT angiography of the whole aorta with or without ECG gating is a dose-efficient and time-saving examination strategy before TAVI. However acquisition timing within the cardiac cycle needs to be taken into account.

Computed Tomographic Angiography for Risk Stratification in Patients with Acute Chest Pain - The Triple Rule-out Concept in the Emergency Department

BACKGROUND

Acute chest pain is one of the most common reasons for Emergency Department (ED) visits and hospital admissions. As this could represent the first symptom of a lifethreatening condition, urgent identification of the etiology of chest pain is of utmost importance in emergency settings. Such high-risk conditions that can present with acute chest pain in the ED include Acute Coronary Syndromes (ACS), Pulmonary Embolisms (PE) and Acute Aortic Syndromes (AAS).

DISCUSSION

The concept of Triple Rule-out Computed Tomographic Angiography (TRO-CTA) for patients presenting with acute chest pain in the ED is based on the use of coronary computed tomographic angiography as a single imaging technique, able to diagnose or exclude three lifethreatening conditions in one single step: ACS, AAS and PE. TRO-CTA protocols have been proved to be efficient in the ED for diagnosis or exclusion of life-threatening conditions and for differentiation between various etiologies of chest pain, and application of the TRO-CTA protocol in the ED for acute chest pain of uncertain etiology has been shown to improve the further clinical evaluation and outcomes of these patients.

CONCLUSION

This review aims to summarize the main indications and techniques used in TRO protocols in EDs, and the role of TRO-CTA protocols in risk stratification of patients with acute chest pain.

High-pitch, 120 kVp/30 mAs, low-dose dual-source chest CT with iterative reconstruction: Prospective evaluation of radiation dose reduction and image quality compared with those of standard-pitch low-dose chest CT in healthy adult volunteers

PURPOSE

Objective of this study was to evaluate the effectiveness of the iterative reconstruction of high-pitch dual-source chest CT (IR-HP-CT) scanned with low radiation exposure compared with low dose chest CT (LDCT).

MATERIALS AND METHODS

This study was approved by the institutional review board. Thirty healthy adult volunteers (mean age 44 years) were enrolled in this study. All volunteers underwent both IR-HP-CT and LDCT. IR-HP-CT was scanned with 120 kVp tube voltage, 30 mAs tube current and pitch 3.2 and reconstructed with sinogram affirmed iterative reconstruction. LDCT was scanned with 120 kVp tube voltage, 40 mAs tube current and pitch 0.8 and reconstructed with B50 filtered back projection. Image noise, and signal to noise ratio (SNR) of the infraspinatus muscle, subcutaneous fat and lung parenchyma were calculated. Cardiac motion artifact, overall image quality and artifacts was rated by two blinded readers using 4-point scale. The dose-length product (DLP) (mGy∙cm) were obtained from each CT dosimetry table. Scan length was calculated from the DLP results. The DLP parameter was a metric of radiation output, not of patient dose. Size-specific dose estimation (SSDE, mGy) was calculated using the sum of the anteroposterior and lateral dimensions and effective radiation dose (ED, mSv) were calculated using CT dosimetry index.

RESULTS

Approximately, mean 40% of SSDE (2.1 ± 0.2 mGy vs. 3.5 ± 0.3 mGy) and 34% of ED (1.0 ± 0.1 mSv vs. 1.5 ± 0.1 mSv) was reduced in IR-HP-CT compared to LDCT (P < 0.0001). Image noise was reduced in the IR-HP-CT (16.8 ± 2.8 vs. 19.8 ± 3.4, P = 0.0001). SNR of lung and aorta of IR-HP-CT showed better results compared with that of LDCT (22.2 ± 5.9 vs. 33.0 ± 7.8, 1.9 ± 0.4 vs 1.1 ± 0.3, P < 0.0001). The score of cardiac pulsation artifacts were significantly reduced on IR-HP-CT (3.8 ± 0.4, 95% confidence interval, 3.7‒4.0) compared with LDCT (1.6 ± 0.6, 95% confidence interval, 1.3‒1.8) (P < 0.0001). SNR of muscle and fat, beam hardening artifact and overall subjective image quality of the mediastinum, lung and chest wall were comparable on both scans (P ≥ 0.05).

CONCLUSION

IR-HP-CT with 120 kVp and 30 mAs tube setting in addition to an iterative reconstruction reduced cardiac motion artifact and radiation exposure while representing similar image quality compared with LDCT.

Comparison of Chest Pain Protocols for Electrocardiography-Gated Dual-Source Cardiothoracic CT in Children and Adults: The Effect of Tube Current Saturation on Radiation Dose Reduction

Objective

To compare radiation doses between conventional and chest pain protocols using dual-source retrospectively electrocardiography (ECG)-gated cardiothoracic computed tomography (CT) in children and adults and assess the effect of tube current saturation on radiation dose reduction.

Materials and Methods

This study included 104 patients (16.6 ± 7.7 years, range 5–48 years) that were divided into two groups: those with and those without tube current saturation. The estimated radiation doses of retrospectively ECG-gated spiral cardiothoracic CT were compared between conventional, uniphasic, and biphasic chest pain protocols acquired with the same imaging parameters in the same patients by using paired t tests. Dose reduction percentages, patient ages, volume CT dose index values, and tube current time products per rotation were compared between the two groups by using unpaired t tests. A p value < 0.05 was considered significant.

Results

The volume CT dose index values of the biphasic chest pain protocol (10.8 ± 3.9 mGy) were significantly lower than those of the conventional protocol (12.2 ± 4.7 mGy, p < 0.001) and those of the uniphasic chest pain protocol (12.9 ± 4.9 mGy, p < 0.001). The dose-saving effect of biphasic chest pain protocol was significantly less with a saturated tube current (4.5 ± 10.2%) than with unsaturated tube current method (14.8 ± 11.5%, p < 0.001). In 76 patients using 100 kVp, patient age showed no significant differences between the groups with and without tube current saturation in all protocols (p > 0.05); the groups with tube current saturation showed significantly higher volume CT dose index values (p < 0.01) and tube current time product per rotation (p < 0.001) than the groups without tube current saturation in all protocols.

Conclusion

The radiation dose of dual-source retrospectively ECG-gated spiral cardiothoracic CT can be reduced by approximately 15% by using the biphasic chest pain protocol instead of the conventional protocol in children and adults if radiation dose parameters are further optimized to avoid tube current saturation.

Improved assessment of mediastinal and pulmonary pathologies in combined staging CT examinations using a fast-speed acquisition dual-source CT protocol

OBJECTIVES

To demonstrate the feasibility of fast Dual-Source CT (DSCT) and to evaluate the clinical utility in chest/abdomen/pelvis staging CT studies.

METHODS

45 cancer patients with two follow-up combined chest/abdomen/pelvis staging CT examinations (maximally ±10 kV difference in tube potential) were included. The first scan had to be performed with our standard protocol (fixed pitch 0.6), the second one using a novel fast-speed DSCT protocol (fixed pitch 1.55). Effective doses (ED) were calculated, noise measurements performed. Scan times were compared, motion artefacts and the diagnostic confidence rated in consensus reading.

RESULTS

ED for the standard and fast-speed scans was 9.1 (7.0-11.1) mSv and 9.2 (7.4-12.8) mSv, respectively (P = 0.075). Image noise was comparable (abdomen; all P > 0.05) or reduced for fast-speed CTs (trachea, P = 0.001; ascending aorta, P < 0.001). Motion artefacts of the heart/the ascending aorta (all P < 0.001) and breathing artefacts (P < 0.031) were reduced in fast DSCT. The diagnostic confidence for the evaluation of mediastinal (P < 0.001) and pulmonary (P = 0.008) pathologies was improved for fast DSCT.

CONCLUSIONS

Fast DSCT for chest/abdomen/pelvis staging CT examinations is performed within 2 seconds scan time and eliminates relevant intrathoracic motion/breathing artefacts. Mediastinal/pulmonary pathologies can thus be assessed with high diagnostic confidence. Abdominal image quality remains excellent.

KEY POINTS

• Fast dual-source CT provides chest/abdomen/pelvis staging examinations within 2 seconds scan time. • The sevenfold scan time reduction eliminates relevant intrathoracic motion/breathing artefacts. • Mediastinal/pulmonary pathologies can now be assessed with high diagnostic confidence. • The coverage of the peripheral soft tissues is comparable to single-source CT. • Fast and large-volume oncologic DSCT can be performed with 9 mSv effective dose.

Computed Tomography Diagnosis of Nonspecific Acute Chest Pain in the Emergency Department: From Typical Acute Coronary Syndrome to Various Unusual Mimics

It is a challenging task for emergency department physicians to establish a precise and rapid diagnosis based only on clinical and laboratory findings in patients who present with nonspecific acute chest pain. In this circumstance, CT angiography can provide important clues to the diagnosis. To provide a rapid diagnosis of acute coronary syndrome (ACS) and its various mimics, the physician should enumerate each possible cause of acute chest pain on the basis of an objective assessment of pretest probability. On the basis of clinical suspicion, the appropriate CT protocol should then be performed. Moreover, radiologists should be familiar with typical CT findings of ACS and its various mimics to assist the emergency department physician in diagnosing patients with nonspecific acute chest pain. This review article presents an overview on choosing an appropriate CT protocol in patients with nonspecific acute chest pain and provides specific CT findings of ACS and various mimics of ACS.

Imaging of the Postsurgical Thoracic Aorta: A State-of-the-Art Review

Techniques for repair of the aorta currently include open and endovascular methods, hybrid approaches, minimally-invasive techniques, and aortic branch vessel reimplantation or bypass. Collaboration among radiologists and vascular and cardiothoracic surgeons is essential. An awareness of the various surgical techniques, expected postoperative appearance, and potential complications is essential for radiologists. This review will cover the postoperative appearance of the thoracic aorta with a focus on the ascending aorta. The value of three-dimensional image evaluation will also be emphasized.

High-Pitch Low-Dose Whole-Body Computed Tomography for the Assessment of Ventriculoperitoneal Shunts in a Pediatric Patient Model: An Experimental Ex Vivo Study in Rabbits

OBJECTIVE

The aim of this study was to assess the diagnostic value of whole-body low-dose (LD) computed tomography (CT) for the detection of ventriculoperitoneal (VP) shunt complications in pediatric patients compared with radiographic shunt series (SS) in an ex vivo rabbit animal model.

METHODS

In the first step, 2 optimized LD-CT imaging protocols, with high pitch (pitch, 3.2), low tube voltages (70 kVp and 80 kVp), and using both filtered back projection and iterative reconstruction, were assessed on a 16-cm solid polymethylmethacrylate phantom regarding signal-to-noise ratio and radiation dose. Taking both radiation dose and signal-to-noise ratio into account, the LD-CT protocol (80 kVp; 4 mA; pitch, 3.2) was identified as most appropriate and therefore applied in this study.After identification of appropriate LD-CT protocol, 12 VP shunts were implanted in 6 rabbit cadavers (mean weight, 5.1 kg). Twenty-four mechanical complications (extracranial and extraperitoneal malpositioning, breakages, and disconnections) were induced in half of the VP shunts. Low-dose CT and conventional SS were acquired in standard fashion. Dose-area products (DAPs) for SS and LD-CT were collected; effective radiation doses for both SS and LD-CT were estimated using CT-Expo (v. 2.3.1.) and age-specific effective dose (ED) estimates. Qualitative scoring of diagnostic confidence on a 5-point Likert scale (1, very low diagnostic confidence; 5, excellent diagnostic confidence) and blinded readings of both SS and LD-CTs were performed.

RESULTS

Among the 24 VP shunt complications, LD-CT yielded excellent sensitivity and specificity for the detection of VP shunt complications (sensitivity, 0.98; specificity, 1; 95% confidence interval, 0.92-1) with excellent interobserver agreement (κ = 0.90). Shunt series yielded good sensitivity and specificity (sensitivity, 0.75; specificity, 1; 95% confidence interval, 0.58-0.92) with moderate interobserver agreement (κ = 0.56). No false-positive findings were registered. Compared with SS, LD-CT yielded significantly lower ED and DAPs (ED, 0.039 vs 0.062 mSv; DAP, 20.5 vs 26.3; P < 0.05).

CONCLUSIONS

In this experimental ex vivo pediatric patient model, LD-CT yields excellent sensitivity for the detection of VP shunt complications at higher diagnostic confidence and lower radiation exposure compared with SS.

Cardiovascular Imaging: The Past and the Future, Perspectives in Computed Tomography and Magnetic Resonance Imaging

Today's noninvasive imaging of the cardiovascular system has revolutionized the approach to various diseases and has substantially affected prognostic information. Cardiovascular magnetic resonance (MR) and computed tomographic (CT) imaging are at center stage of these approaches, although 5 decades ago, these technologies were unheard of. Both modalities had their inception in the 1970s with a primary focus on noncardiovascular applications. The technical development of the various decades, however, substantially pushed the envelope for cardiovascular MR and CT applications. Within the past 10-15 years, MR and CT technologies have pushed each other in cardiac applications; and without the "rival" modality, neither one would likely not have reached its potential today. This view on the history of MR and CT in the field of cardiovascular applications provides insight into the story of success of applications that once have been ideas only but are at prime time today.

Automated Tube Voltage Selection for Radiation Dose Reduction in CT Angiography Using Different Contrast Media Concentrations and a Constant Iodine Delivery Rate

OBJECTIVE

The purpose of this study was to systematically investigate radiation dose reduction using automated tube voltage selection during CT angiography (CTA) and to evaluate the impact of contrast medium (CM) injection protocols on dose reduction.

MATERIALS AND METHODS

A circulation phantom containing the thoracic and abdominal vasculature was used. Four different concentrations of CM (iopromide 300 and 370 mg I/mL and iomeprol 350 and 400 mg I/mL) were administered while maintaining an identical iodine delivery rate (1.8 g I/s) and total iodine load (20.0 g). Three different scanning protocols for CTA of the thoracoabdominal aorta were used: protocol A, no dose modulation; protocol B, automated tube current modulation (CARE Dose4D); and protocol C, automated tube voltage selection (CARE kV). The dose-length product was recorded to calculate the effective dose. Attenuation values (in Hounsfield units), image noise levels, and signal-to-noise ratios (SNRs) in six predefined intravascular sites (three thoracic and three abdominal) were measured by two readers. All values were analyzed using the Kruskal-Wallis test and two-way ANOVA.

RESULTS

There was a significant reduction in the effective dose (in millisieverts) for protocols B (mean ± SD, 2.03 ± 0.1 mSv) and C (1.00 ± 0.0 mSv) compared with protocol A (4.34 ± 0.0 mSv). The dose was reduced by 53% for protocol B and by 77% for protocol C. No significant differences were found in the effective dose among the different CM injection protocols within the scanning protocols; all p values were > 0.05. The attenuation values and SNRs were comparable among all the different CM injection protocols; all p values were > 0.05.

CONCLUSION

A large radiation dose reduction (77%) can be achieved using automated tube voltage selection independent of the CM injection protocol.

Automated tube voltage selection in thoracoabdominal computed tomography at high pitch using a third-generation dual-source scanner: image quality and radiation dose performance

OBJECTIVES

The objective of this study was to evaluate the radiation dose and image quality performance of thoracoabdominal examinations with an automated tube voltage selection (tube voltage adaptation), tube current modulation, and high pitch using a third-generation dual-source computed tomography (CT) compared intraindividually with 120-kV examinations with tube current modulation with special attention on clinically relevant lesions in the liver, the lungs, and extrahepatic soft tissues.

MATERIALS AND METHODS

This study was approved by the institutional review board. Computed tomography of the body was performed using a third-generation dual-source system in 95 patients (mean body mass index, 25 kg/m²; range, 18-35 kg/m²). For 49 of these patients, all calculated tube settings and resulting dose values were recorded for each of the 12 gradual contrast weightings of the tube voltage adaptation algorithm. Spiral CT was performed for all patients with an intermediate weighting (grade 7) in a portal venous phase at 120 reference kV, 180 reference mAs, and pitch of 1.55. Objective image quality was assessed on the basis of contrast-to-noise ratio. Subjective image quality was assessed on the basis of clarity and sharpness of anatomical and pathological structures as well as interfering beam hardening and spiral and motion artifacts (heart, lungs, diaphragm). Previous examinations on a 64-slice scanner served as reference.

RESULTS

All examinations were rated good or excellent for clinical diagnosis. Automated tube voltage selection resulted in significantly lower effective radiation dose (9.5 mSv) compared with the reference (12.0 mSv; P < 0.01). Contrast-to-noise ratio and image quality of soft tissue lesions were significantly increased (P < 0.01). Motion artifacts were significantly reduced (P < 0.01).

CONCLUSIONS

Automated tube voltage adaptation combined with high-pitch protocols allows for a substantial radiation dose reduction while substantially increasing the image quality, even at large-volume exposure.

Calcium Scoring and Cardiac Computed Tomography

Although recent advances in noninvasive imaging technologies have potentially improved diagnostic efficiency and clinical outcomes of patients with acute chest pain, controversy remains regarding much of the accumulated evidence. This article reviews the role of coronary computed tomography (CT) angiography in the assessment of coronary risk, and its usefulness in the emergency department in facilitating appropriate disposition decisions. Also discussed is coronary artery calcification incidentally found on CT scans when done for indications such as evaluation of pulmonary embolism or lung cancer. The evidence base and clinical applications for both techniques are described, together with cost-effectiveness and radiation exposure considerations.

Triple Rule Out versus CT Angiogram Plus Stress Test for Evaluation of Chest Pain in the Emergency Department

Introduction

Undifferentiated chest pain in the emergency department (ED) is a diagnostic challenge. One approach includes a dedicated chest computed tomography (CT) for pulmonary embolism or dissection followed by a cardiac stress test (TRAD). An alternative strategy is a coronary CT angiogram with concurrent chest CT (Triple Rule Out, TRO). The objective of this study was to describe the ED patient course and short-term safety for these evaluation methods.

Methods

This was a retrospective observational study of adult patients presenting to a large, community ED for acute chest pain who had non-diagnostic electrocardiograms (ECGs) and normal biomarkers. We collected demographics, ED length of stay, hospital costs, and estimated radiation exposures. We evaluated 30-day return visits for major adverse cardiac events.

Results

A total of 829 patients underwent TRAD, and 642 patients had TRO. Patients undergoing TRO tended to be younger (mean 52.3 vs 56.5 years) and were more likely to be male (42.4% vs. 30.4%). TRO patients tended to have a shorter ED length of stay (mean 14.45 vs. 21.86 hours), to incur less cost (median $449.83 vs. $1147.70), and to be exposed to less radiation (median 7.18 vs. 16.6mSv). No patient in either group had a related 30-day revisit.

Conclusion

Use of TRO is feasible for assessment of chest pain in the ED. Both TRAD and TRO safely evaluated patients. Prospective studies investigating this diagnostic strategy are needed to further assess this approach to ED chest pain evaluation.

First Clinical Evaluation of High-Pitch Dual-Source Computed Tomographic Angiography Comparing Automated Tube Potential Selection With Automated Tube Current Modulation

OBJECTIVE

To investigate and compare the use of automated tube potential selection (ATPS) with automated tube current modulation (ATCM) in high-pitch dual-source computed tomographic angiography (CTA) for imaging the whole aorta without electrocardiogram synchronization.

METHODS

Two groups of 60 patients underwent CTA on a dual-source computed tomographic device in high-pitch mode: ATCM (with 100-kV fixed tube potential) was used in group 1 and ATPS (with the same image quality options) in group 2. For the evaluation of radiation exposure, CT dose index and dose-length product were analyzed. Contrast and image quality were assessed by 2 independent observers.

RESULTS

The ATPS group received a higher radiation dose than the ATCM group (P < 0.001) because in 80% of patients, the software switched to use of a 120-kV tube potential. In all cases, images of the aorta were of sufficient quality.

CONCLUSIONS

High-pitch dual-source CTA of the aorta using ATPS is feasible in clinical routine, but is associated with higher radiation exposure than the ATCM protocol. This finding contradicts previously evaluations of ATPS based on single-source techniques.

Imaging modalities in children with vascular ring and pulmonary artery sling

PURPOSE

Our aim is to compare new non-invasive imaging modalities in the evaluation of vascular ring (VR) and pulmonary artery sling (PAS) and to understand the role of bronchoscopy in comparison with them in assessing tracheobronchial tree.

METHODS

We have retrospectively analyzed the data from 41 patients with a VR or a PAS diagnosed at Bambino Gesù Children's Hospital of Rome, between 2008 and 2012. Age, gender, presenting symptoms, clinical history, comorbidities, imaging modalities used for diagnosis (cardiac magnetic resonance [CMR], computed tomography [CT], tracheobronchoscopy [TB]) and surgical treatment were recorded.

RESULTS

The vascular anatomy was completely defined in all patients, whether evaluated by CMR or CT, with a diagnostic accuracy of 100% based on surgical observation. All CT exams were performed without sedation with a mean dose-length product (DLP32 ) of 29 ± 9 and an effective dose of 1.56 ± 0.6 mSv, range 0.5-2.5 mSv. CMR required general anesthesia in all patients but involved no exposure to ionizing radiation. CT performed better than CMR in assessing tracheal stenosis when compared to TB. It detected complete tracheal cartilage rings in 2/3 patients with PAS, besides tracheomalacia and/or bronchomalacia in 54% of patients.

CONCLUSIONS

Both cross-sectional imaging modalities (CT and CMR) can reliably and accurately diagnose these congenital vascular anomalies. While CT involves exposure to ionizing radiation, it avoids the risks related to anesthesia needed for CMR, and provides a more accurate assessment of tracheobronchial anatomy. TB remains a fundamental tool in tracheomalacia diagnosis in VR symptomatic patients and PAS.

Energy Limits in Second Generation High-pitch Dual Source CT - Comparison in an Upper Abdominal Phantom

Objectives:

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.

Materials and Methods:

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.

Results:

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.

Conclusion:

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.

70 kV computed tomography of the thorax: valence for computer-assisted nodule evaluation and radiation dose - first clinical results

BACKGROUND

Computed tomography (CT) is the gold standard for evaluation of pulmonary nodules and is at the same time responsible for the majority of the collective effective dose.

PURPOSE

To evaluate radiation dose and efficacy of computer-assisted detection (CAD) for solid pulmonary nodules in low dose chest CT performed at 70 kV.

MATERIAL AND METHODS

CAD was performed upon chest CT with 70 kV and 100 kV (gold standard) at manufacture's recommended tube current of 87 mAs (collimation, 64 × 0.6 mm). Detection rate for pulmonary nodules and size measurements of both techniques were compared to each other. Radiation dosage in terms of effective dose (E) was measured using an Alderson-Rando Phantom.

RESULTS

Seventy-four patients with 301 solid nodules were included in the study. CAD detection rate was similar for 70 kV (94.7%) and 100 kV (92.4%). Mean transversal nodule diameter was 5.5 mm for 70 kV and 5.7 mm for 100 kV with an average volume of 0.12 mL (both techniques). Derived from the phantom measurements patient examinations resulted in an E of 0.51 mSv (70 kV) versus 2.02 mSv (100 kV).

CONCLUSION

70 kV low-dose chest CT is suitable for CAD based lung nodule analysis at a fraction of the radiation burden of the standard technique. Since the measurements are highly accurate, 70 kV CT could be used for detection of pulmonal lesions as well as follow-up studies.

Effect of high-pitch dual-source CT to compensate motion artifacts: a phantom study

RATIONALE AND OBJECTIVES

To evaluate the potential of high-pitch, dual-source computed tomography (DSCT) for compensation of motion artifacts.

MATERIALS AND METHODS

Motion artifacts were created using a moving chest/cardiac phantom with integrated stents at different velocities (from 0 to 4-6 cm/s) parallel (z direction), transverse (x direction), and diagonal (x and z direction combined) to the scanning direction using standard-pitch (SP) (pitch = 1) and high-pitch (HP) (pitch = 3.2) 128-detector DSCT (Siemens, Healthcare, Forchheim, Germany). The scanning parameters were (SP/HP): tube voltage, 120 kV/120 kV; effective tube current time product, 300 mAs/500 mAs; and a pitch of 1/3.2. Motion artifacts were analyzed in terms of subjective image quality and object distortion. Image quality was rated by two blinded, independent observers using a 4-point scoring system (1, excellent; 2, good with minor object distortion or blurring; 3, diagnostically partially not acceptable; and 4, diagnostically not acceptable image quality). Object distortion was assessed by the measured changes of the object's outer diameter (x) and length (z) and a corresponding calculated distortion vector (d) (d = √(x(2) + z(2))).

RESULTS

The interobserver agreement was excellent (k = 0.91). Image quality using SP was diagnostically not acceptable with any motion in x direction (scores 3 and 4), in contrast to HP DSCT where it remained diagnostic up to 2 cm/s (scores 1 and 2). For motion in the z direction only, image quality remained diagnostic for SP and HP DSCT (scores 1 and 2). Changes of the object's diameter (x), length (z), and distortion vectors (d) were significantly greater with SP (overall: x = 1.9 cm ± 1.7 cm, z = 0.6 cm ± 0.8 cm, and d = 1.4 cm ± 1.5 cm) compared to HP DSCT (overall: x = 0.1 cm ± 0.1 cm, z = 0.0 cm ± 0.1 cm, and d = 0.1 cm ± 0.1 cm; each P < .05).

CONCLUSION

High-pitch DSCT significantly decreases motion artifacts in various directions and improves image quality.

Triple rule-out computed tomographic angiography for chest pain: a diagnostic systematic review and meta-analysis

OBJECTIVES

The objective was to compare the image quality, diagnostic accuracy, radiation exposure, and contrast volume of "triple rule-out" (TRO) computed tomography (CT) to other diagnostic modalities commonly used to evaluate patients with nontraumatic chest pain (dedicated coronary, pulmonary embolism [PE], and aortic dissection CT; invasive coronary angiography; and nuclear stress testing).

METHODS

Four electronic databases were searched, along with reference lists and contacted content experts, for relevant studies from inception until October 2012. Eligible studies enrolled patients with nontraumatic chest pain, shortness of breath, suspected acute coronary syndrome (ACS), PE, or aortic dissection; used at least 64-slice CT technology; and compared TRO CT to another diagnostic modality.

RESULTS

Eleven studies enrolling 3,539 patients (791 TRO and 2,748 non-TRO) were included (one randomized controlled trial and 10 observational). There was no significant difference in image quality between TRO and dedicated CT scans. TRO CT had the following pooled diagnostic accuracy estimates for coronary artery disease: sensitivity of 94.3% (95% confidence interval [CI] = 89.1% to 97.5%), specificity of 97.4% (95% CI = 96.1% to 98.4%), positive likelihood ratio (LR+) of 17.71 (95% CI = 3.92 to 79.96), and negative likelihood ratio (LR-) of 0.08 (95% CI = 0.02 to 0.27). There were insufficient numbers of patients with PE or aortic dissection to generate diagnostic accuracy estimates for these conditions. Use of TRO CT involved greater radiation exposure (mean difference [MD] = 4.84 mSv, 95% CI = 1.65 to 8.04 mSv) and contrast exposure (MD = 38.0 mL, 95% CI = 28.1 to 48.0 mL) compared to non-TRO CT patients.

CONCLUSIONS

Triple rule-out CT is highly accurate for detecting coronary artery disease. Given the low (<1%) prevalence of PE and aortic dissection in the included studies, and the increased radiation and contrast exposure, there are insufficient data to recommend use of TRO CT in the diagnosis of these conditions.

Determinants of second-order bile duct visualization at CT cholangiography in potential living liver donors

OBJECTIVE

The purpose of this article is to investigate the determinants of second-order bile duct visualization at CT cholangiography in living potential liver donors.

MATERIALS AND METHODS

We retrospectively identified 143 potential living liver donors (83 men and 60 women; mean age, 37 years) evaluated with CT cholangiography, which included a slow infusion of iodipamide meglumine with CT acquisition 15 minutes after biliary contrast agent administration. Two readers independently scored the visualization of the second-order bile duct branches on a previously established 4-point scale (0 = not seen, 1 = faintly seen, 2 = well seen, and 3 = excellent visualization). Multivariate analysis was used to investigate the correlation between visualization scores and potential determinants of second-order bile duct opacification, specifically age, body mass index, creatinine level, total and direct bilirubin levels, alkaline phosphatase level, aspartate aminotransferase level, alanine aminotransferase level, patient maximum linear width, CT noise, and hepatosplenic attenuation difference at unenhanced CT.

RESULTS

The mean (± SD) second-order bile duct visualization scores were 2.35 ± 0.66 and 2.55 ± 0.60 for readers 1 and 2, respectively. In the multivariate analysis, the only independent predictors of reduced second-order bile duct visualization were higher alkaline phosphatase level (p = 0.01) and higher CT noise (p = 0.02).

CONCLUSION

Higher serum alkaline phosphatase level and higher CT noise in potential living liver donors indicate a higher risk of poor second-order bile duct visualization at CT cholangiography.

Iterative reconstructed ultra high pitch CT pulmonary angiography with cardiac bowtie-shaped filter in the acute setting: effect on dose and image quality

PURPOSE

To evaluate the effect of a cardiac bowtie-shaped filter in an ultra high pitch CTPA protocol at 100 kV on image quality and radiation dose.

MATERIALS AND METHODS

Retrospective study of 100 patients referred for CTPA. 50 patients scanned with a standard 100 kV protocol at pitch 2.8 (Protocol A) and 50 patients scanned with a 100 kV protocol at pitch 3.2 with a cardiac bowtie-shaped filter (Protocol B). All other scanning parameters kept constant. Images from both groups reconstructed with filtered back projection and iterative reconstruction. Central pulmonary vessel attenuation and background noise were quantitatively measured and signal-to-noise (SNR) and contrast-to-noise (CNR) were calculated. Two radiologists performed qualitative assessment grading visualization of the pulmonary vasculature and noise level. CTDIvol and DLP were recorded and effective dose was calculated.

RESULTS

CTDIvol, DLP and effective dose were significantly (p<0.0001) lower in Protocol B (2.3 ± 0.5 mGy, 78.4 ± 16.5 mGycm, 1.4 ± 0.3 mSy, respectively) compared to Protocol A (4.3 ± 0.5 mGy, 152.0 ± 19.6 mGycm, 2.7 ± 0.3 mSy, respectively). Protocol B had significantly (p<0.0001) higher noise than Protocol A (23.8 ± 6.9 HU vs 36.8 ± 7.3 HU) and lower SNR (11.8 ± 3.7 HU vs 19.2 ± 8.1 HU) and CNR (10.3 ± 3.7 HU vs 24.9 ± 13.4 HU) but there was no significant difference in the subjective visualization of the pulmonary vasculature (p=0.63). Furthermore, iterative reconstruction significantly (p<0.0001) improves image noise (29.4 ± 5.5 HU from 36.8 ± 7.3 HU).

CONCLUSION

The addition of a cardiac bowtie-shaped filter with an ultra high pitch CTPA protocol at 100 kV resulted in a 48% dose reduction without significantly affecting diagnostic image quality. In addition, the use of iterative reconstruction significantly improves image quality by reducing noise permitting the possibility for further dose reduction strategies.

Evaluation of high-pitch flash scan for pulmonary venous CTA on a 128-slice dual source CT: compared with prospective ECG-triggered sequence scan

To compare the image quality (IQ) and radiation dose of high-pitch scan and prospective ECG-triggered sequence scan on a 128-slice DSCT system for patients with atrial fibrillation (AF). Pulmonary venous (PV) CTA was performed with two protocols, including high-pitch scan and prospective ECG-triggered sequence scan. For each protocol, 20 sex, age and body-mass-index (mean 24.2 kg/m(2)) matched patients were identified. Two experienced radiologists, who were blinded to the scan protocols, independently graded the CT images of the two groups by a 5-point scale for subjective IQ assessment. Measured CT attenuation (Hounsfield units ± standard deviation), signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) at various anatomic locations were also recorded for objective IQ evaluation. Radiation exposure parameters [dose length product (DLP) and effective radiation dose (ERD)] were compared. Twenty-three patients (57.5 %) showed an ECG pattern of AF in total. Subjective IQ was rated excellent in 100 % for the high-pitch scan group, while minor step artifacts were observed in two patients (10 %) with arrhythmia for the prospective ECG-triggered sequence group. There was no significant difference on IQ, neither by subjective, nor by objective measures (SNR, CNR) between the two groups. The ERD of high-pitch flash scan and prospective ECG-triggered sequence scan were 0.9 (± 0.25) and 2.9 (± 0.69) mSv, respectively. Significantly lower radiation was achieved by using high-pitch flash scan (P < 0.05). High-pitch flash scan can provide similar subjective and objective IQ compared with prospective ECG-triggered sequence scan for PV CTA, while radiation exposure was significantly reduced.

[Possibilities for exposure reduction in computed tomography examination of acute chest pain]

CLINICAL/METHODICAL ISSUE

Electrocardiogram-gated (ECG) computed tomography (CT) investigations can be accompanied by high amounts of radiation exposure. This is particularly true for the investigation of patients with unclear and acute chest pain.

STANDARD RADIOLOGICAL METHODS

The common approach in patients with acute chest pain is standard spiral CT of the chest.

METHODICAL INNOVATIONS

The chest pain or triple-rule-out CT protocol is a relatively new ECG-gated protocol of the entire chest. This article reviews and discusses different techniques for the CT investigation of patients with acute chest pain.

PERFORMANCE

By applying the appropriate scan technique, the radiation exposure for an ECG-gated protocol must not necessarily be higher than a standard chest CT scan

ACHIEVEMENTS

Aortic pathologies are far better depicted by ECG-gated scan protocols and depending on the heart rate coronary artery disease can also be detected at the same time.

PRACTICAL RECOMMENDATIONS

The use of ECG-triggered scans will not support the diagnostics of the pulmonary arteries. However, in unspecific chest pain an ECG-triggered scan protocol can provide information on the differential diagnosis.

Dose and image quality of high-pitch dual source computed tomography for the evaluation of cervical lymph node status - comparison to regular 128-slice single source computed tomography

PURPOSE

A high-pitch dual-source CT (DSCT) was compared to a standard single-source CT protocol in terms of dose and image quality for malignant lymphoma staging.

MATERIALS AND METHODS

Data from 43 patients who underwent DSCT (group 1) of the neck for staging of malignant lymphoma and 40 patients who underwent regular single source CT (group 2) were investigated retrospectively. Volume CT dose index (CTDIvol), dose length product (DLP), background noise (BN), attenuation values, signal-to-noise-ratio (SNR), scan time, effective tube current-time product (eff. mAs), subjective diagnostic image quality and artifact burden were compared.

RESULTS

CTDIvol (5.5 ± 0.8 mGy vs. 12.4 ± 1.4 mGy), DLP (172 ± 27 mGycm vs. 344 ± 60 mGycm, p<0.0001), eff. mAs (98 ± 15 mAs vs. 183 ± 20 mAs, p<0.0001) and scan time (0.64 ± 0.05 s vs. 8.21 ± 0.72 s) were lower for group 1. BN was higher (p<0.001) for group 1 with a mean difference of 2.6 HU. SNR for sternocleidomastoid and pectoral muscle was lower (6.6-12.3 vs. 7.8-19.1) for group 1. Subjective image quality (1.55 ± 0.6 vs. 1.42 ± 0.5) and artifact burden (1.62 ± 1.0 vs. 1.57 ± 0.9) were not rated significantly different (p=0.47 and p=0.80) with a good inter-observer agreement (κ=0.59-0.90).

CONCLUSION

High-pitch DSCT allows reduction of patient dose for cervical lymphoma staging while diagnostic image quality is preserved.

Estimated radiation dose and image quality comparison of the scan protocols in dual-source computed tomography coronary angiography

INTRODUCTION

Radiation exposure from computed tomography coronary angiography (CTCA) is of particular concern and several techniques have been introduced to lower the radiation dose. In this study, we aimed to compare the diagnostic image quality and estimated radiation dose of the three CTCA acquisition protocols in a recently introduced second generation dual-source computed tomography.

METHODS

Two hundred consecutive subjects underwent dual-source CTCA by using high-pitch spiral, sequential and retrospective spiral protocols. Effective radiation dose, expressed in millisieverts, was calculated as the product of the dose-length product times a conversion factor of 0.014. Image quality was evaluated on a per-segment basis, with a four-point scale.

RESULTS

For the high-pitch spiral, sequential and retrospective spiral protocols, mean effective radiation doses were 1.41 ± 0.56, 5.50 ± 2.06 and 7.79 ± 2.25 mSv and mean per-subject image scores were 2.8 ± 0.7, 2.2 ± 0.8 and 2.5 ± 0.8, respectively. Radiation dose of the high-pitch mode was significantly lower (P < 0.001) than the sequential and retrospective spiral modes, and statistical analysis for image quality revealed a significant difference between the high-pitch spiral and the sequential modes (P < 0.05).

CONCLUSION

Dual-source CTCA using high-pitch acquisition considerably lowers radiation exposure in subjects with a low and stable heart rate and maintains good image quality, especially when the subjects have a body mass index ≤25 and a tube voltage of 80 or 100 kV is used. However, when sequential and retrospective spiral modes are used in the same device, mean radiation doses can increase roughly three and five times more, respectively.

Impact of coronary calcium score on the prevalence of coronary artery stenosis on dual source CT coronary angiography in caucasian patients with an intermediate risk

PURPOSE

To investigate the prevalence of significant coronary artery stenosis on coronary computed tomography angiography (cCTA) in symptomatic Caucasian patients with an intermediate risk score at different levels of coronary artery calcification (CAC).

METHOD

In total, 383 consecutive symptomatic Caucasian patients (147 females, 60 ± 13 years) with an intermediate risk score underwent nonenhanced CT for CAC scoring immediately before contrast-enhanced cCTA on a dual-source CT scanner. Additionally clinically indicated invasive coronary angiography (ICA) was performed in 90 patients. The prevalence of significant coronary artery stenosis (>50%) on cCTA and ICA was correlated at different CAC score levels.

RESULTS

Of 121 patients with a zero CAC score, none had significant coronary artery stenosis on cCTA or ICA. Coronary CTA diagnosed in 54 of 70 patients with high CAC score (>400), a significant stenosis. Subsequent ICA confirmed significant stenosis in 30 of 32 patients. Sensitivity and a negative predictive value of CAC score ruling out significant stenosis on cCTA were 100% and 100%, respectively, using cutoff value of zero and specificity and positive predictive value to predict significant stenosis on cCTA were 79% and 51%, respectively, using a cutoff value of >400.

CONCLUSION

Significant coronary artery stenosis is extremely unlikely, with an estimated risk of 4 in 1000 patients in symptomatic Caucasian patients with an intermediate risk score and negative CAC score. To reduce radiation exposure, radiation-free tests should be considered for differential diagnosis of chest pain in these patients.

Virtual monochromatic spectral imaging for the evaluation of hypovascular hepatic metastases: the optimal monochromatic level with fast kilovoltage switching dual-energy computed tomography

OBJECTIVES

The purpose of this study was to select the optimal monochromatic level for virtual monochromatic spectral (VMS) imaging to minimize the image noise of the liver parenchyma and to acquire a high contrast-to-noise ratio (CNR) of hypovascular hepatic metastases in the portal-dominant phase.

MATERIALS AND METHODS

This study was conducted with the approval of our institutional review board, and written informed consent was obtained from all the participating patients. Ninety patients with hepatic metastases were scanned by fast kilovoltage switching dual-energy computed tomography in the portal-dominant phase. One hundred one sets of VMS images in the range of 40 to 140 keV at 1-keV intervals were reconstructed. The image noise of the liver parenchyma in each patient and the CNR of each metastasis (n = 303) were measured on all the 101 VMS image sets. Data were analyzed by the paired t test and mixed-effects model. Bonferroni's method was used for multiple comparisons.

RESULTS

The lowest noise of the liver parenchyma was obtained in 6, 15, 31, 29, 7, 1, and 1 patient at 67, 68, 69, 70, 71, 72, and 73 keV, respectively. The mean noise of the liver parenchyma on the 69-keV VMS images in all 90 patients was significantly lower than that on the 67-, 68-, 71-, 72-, and 73-keV VMS images (P < 0.001); however, there was no significant difference in the mean noise of the liver parenchyma between the 69-keV and 70-keV VMS images (P = 0.279). For 95% of the hepatic metastases (288/303 metastases), the highest metastasis-to-liver CNR was obtained in the 66- to 71- keV VMS images. The mean metastasis-to-liver CNR for the 303 metastases was numerically highest at 68 keV; however, there was no significant difference in the mean metastasis-to-liver CNR between the 68-keV and 69-keV images (P = 0.737) or between the 68-keV and 70-keV images (P = 0.103).

CONCLUSIONS

VMS imaging at approximately 70 keV (69-70 keV) yielded the lowest image noise of the liver parenchyma and a high CNR for hypovascular hepatic metastases in the portal-dominant phase.

Which should be the routine cross-sectional reconstruction mode in spectral CT imaging: monochromatic or polychromatic?

OBJECTIVE

To provide evidence for the selection of an optimal cross-sectional reconstruction mode in spectral CT imaging of the abdomen, we compared the monochromatic images with polychromatic images.

METHODS

Three phase-enhanced CT scans of the abdomen were recorded using the spectral imaging technique on 100 patients. Images were reconstructed using two modes: polychromatic and 70 keV monochromatic. The following variables were then compared: contrast-to-noise ratio (CNR) of the liver, spleen, gallbladder, kidney and pancreas, and the noise. Paired t-tests were used to compare differences between the two sets of images. Three experienced doctors graded the quality of the images with a five-point scale. The image quality scores were compared with a non-parametric rank sum test.

RESULTS

Compared with polychromatic images, the 70 keV monochromatic mode images yielded significantly greater tissue-to-fat CNR and lower noise (p<0.001 for all comparisons). The image quality of the 70 keV monochromatic mode showed significantly better results than the polychromatic mode (p<0.001).

CONCLUSIONS

In abdominal spectral CT imaging, 70 keV monochromatic mode reconstruction images were better than those reconstructed using the polychromatic mode. The monochromatic mode may become the routine reconstruction mode for cross-sectional images.

High-pitch dual-source CT coronary angiography: analysis of the impact on image quality of altered electrocardiography waves during data acquisition

Electrocardiography (ECG) "altered waves" sometimes occur during data acquisition when computed tomography coronary angiography (CTCA) is performed with the prospectively ECG-triggered high-pitch (Flash spiral) mode using a second-generation dual-source CT. The aim of this study was to assess the effect of the ECG altered waves on image quality. Seventy-three consecutive patients with stable sinus rhythm ≤ 65 beats per minute were retrospectively enrolled in this study. CTCA was performed using the Flash spiral mode in which the data acquisition was prospectively triggered at 60 % of the R-R interval and completed within one cardiac cycle. The ECG waves before and during data acquisition were analyzed for grouping purposes. Image quality was evaluated using a four-point scale (1 = best, 4 = unevaluatable). Thirty patients (group 1) were found to have ECG altered waves during data acquisition, while 43 patients (group 2) had ECG "stable waves." The altered waves were seen as the baseline drifting; the broad, erected, or inverted P wave or QRS complexes; and a new wave. However, the length of the R-R interval did not change during the data acquisition. There were no significant differences in image quality scores between the two groups on the per-patient (2 ± 0.87 vs. 2.2 ± 0.74, P = 0.273) or per-segment (1.27 ± 0.54 vs. 1.32 ± 0.55, P = 0.577) basis. There were no significant differences in coronary evaluatability as well (per-patient; 93.3 vs. 95.3 %, P = 0.352; per-segment; 99.4 vs. 99.6 %, P = 1.0). CTCA image quality is not affected by ECG altered waves during data acquisition using the Flash spiral mode in low and stable heart rate patients. Thus, the ECG altered waves are considered artifacts.