Diagnostic accuracy of high-pitch dual-source CT for the assessment of coronary stenoses: first experience

Objectives

The objective was to prospectively investigate the diagnostic accuracy of high-pitch (HP) dual-source computed tomography coronary angiography (CTCA) compared with catheter coronary angiography (CCA) for the diagnosis of significant coronary stenoses.

Methods

Thirty-five patients (seven women; mean age 62?±?8 years) underwent both CTCA and CCA. CTCA was performed with a second-generation dual-source CT system permitting data acquisition at an HP of 3.4. Patients with heart rates >60 bpm were excluded from study enrolment. All coronary segments were evaluated by two blinded and independent observers with regard to image quality on a four-point scale (1: excellent to 4: non-diagnostic) and for the presence of significant coronary stenoses (defined as diameter narrowing exceeding 50%). CCA served as the standard of reference. Radiation dose values were calculated using the dose-length product.

Results

Diagnostic image quality was found in 99% of all segments (455/459). Non-diagnostic image quality occurred in a single patient with a sudden increase in heart rate immediately before and during CTCA. Taking segments with non-evaluative image quality as positive for disease, the sensitivity, specificity and positive and negative predictive values were 94, 96, 80 and 99% per segment and 100, 91, 88 and 100% per patient. The effective radiation dose was on average 0.9?±?0.1 mSv.

Conclusion

In patients with heart rates ≤60 bpm, CTCA using the HP mode of the dual-source CT system is associated with high diagnostic accuracy for the assessment of coronary artery stenoses at sub-milliSievert doses.     

Performance of turbo high-pitch dual-source CT for coronary CT angiography: first ex vivo and patient experience

Objectives

To evaluate image quality, maximal heart rate allowing for diagnostic imaging, and radiation dose of turbo high-pitch dual-source coronary computed tomographic angiography (CCTA).

Methods

First, a cardiac motion phantom simulating heart rates (HRs) from 60-90 bpm in 5-bpm steps was examined on a third-generation dual-source 192-slice CT (prospective ECG-triggering, pitch 3.2; rotation time, 250 ms). Subjective image quality regarding the presence of motion artefacts was interpreted by two readers on a four-point scale (1, excellent; 4, non-diagnostic). Objective image quality was assessed by calculating distortion vectors. Thereafter, 20 consecutive patients (median, 50 years) undergoing clinically indicated CCTA were included.

Results

In the phantom study, image quality was rated diagnostic up to the HR75 bpm, with object distortion being 1 mm or less. Distortion increased above 1 mm at HR of 80-90 bpm. Patients had a mean HR of 66 bpm (47-78 bpm). Coronary segments were of diagnostic image quality for all patients with HR up to 73 bpm. Average effective radiation dose in patients was 0.6?±?0.3 mSv.

Conclusions

Our combined phantom and patient study indicates that CCTA with turbo high-pitch third-generation dual-source 192-slice CT can be performed at HR up to 75 bpm while maintaining diagnostic image quality, being associated with an average radiation dose of 0.6 mSv.

Key points

? CCTA is feasible with the turbo high-pitch mode. ? Turbo high-pitch CCTA provides diagnostic image quality up to 73 bpm. ? The radiation dose of high-pitch CCTA is 0.6 mSv on average.     

Imaging of pulmonary vein anatomy using low-dose prospective ECG-triggered dual-source computed tomography

Objective

To prospectively investigate the feasibility, image quality and radiation dose estimates for computed tomography angiography (CTA) of the pulmonary veins and left atrium using prospective electrocardiography (ECG)-triggered sequential dual-source (DS) data acquisition at end-systole in patients with paroxysmal atrial fibrillation undergoing radiofrequency ablation.

Methods

Thirty-five patients (mean age 66.2?±?12.6 years) with paroxysmal atrial fibrillation underwent prospective ECG-triggered sequential DS-CTA with tube current (250 mAs/rotation) centred 250 ms past the R-peak. Tube voltage was adjusted to the BMI (<25 kg/m²: 100 kV, >25 kg/m²: 120 kV). Presence of motion or stair-step artefacts was assessed. Effective radiation dose was calculated from the dose-length product.

Results

All data sets could be integrated into the electroanatomical mapping system. Twenty-two patients (63%) were in sinus rhythm (mean heart rate 69.2?±?11.1 bpm, variability 1.0?±?1.7 bpm) and 13 (37%) showed an ECG pattern of atrial fibrillation (mean heart rate 84.8?±?16.6 bpm, variability 17.9?±?7.5 bpm). Minor step artefacts were observed in three patients (23%) with atrial fibrillation. Mean estimated effective dose was 1.1?±?0.3  and 3.0?±?0.5 mSv for 100 and 120 kV respectively.

Conclusion

Imaging of pulmonary vein anatomy is feasible using prospective ECG-triggered sequential data acquisition at end-systole regardless of heart rate or rhythm at the benefit of low radiation dose.     

Dual-step prospective ECG-triggered 128-slice dual-source CT for evaluation of coronary arteries and cardiac function without heart rate control: a technical note

Purpose

To describe prospective ECG-triggered dual-source CT dual-step pulsing (pECG_{dual_step}) for evaluation of coronary arteries and cardiac function.

Methods

Fifty-one consecutive patients pre- or post-cardiovascular surgery were examined with adaptive sequential tube current modulated (pECG_dual-step) 128-slice dual-source CT without heart rate control (main padding window: 40% RR interval?>65 bpm/70% RR interval?<65 bpm). Image quality of coronary arteries was graded (4-point scale), and cardiac function was evaluated.

Results

Mean HR was 68 bpm. Thirty-seven patients were in stable sinus rhythm (SR); 14 had arrhythmia. Image quality of coronary arteries was diagnostic in 804/816 (98%) of segments. The number of non-diagnostic segments was higher in patients with arrhythmia as compared to those in SR (4% vs. 0.5%; p?=?0.01), and there were fewer segments with excellent image quality (79% vs. 94%; p?<?0.001) and more segments with impaired image quality (p?<?0.001 and p?=?0.002). Global and regional LV function could be evaluated in 41 (80%) and 47 (92%) patients, and valvular function in 48 (94%). In 11/14 of patients with arrhythmia, the second step switched to full mAs, increasing radiation exposure to 8.6 mAs (p?<?0.001). The average radiation dose was 3.8 mSv (range, 1.7–7.9) in patients in SR.

Conclusion

pECG_dual-step128-slice DSCT is feasible for the evaluation of coronary arteries and cardiac function without heart rate control in patients in stable sinus rhythm at a low radiation dose.     

Tube potential can be lowered to 80 kVp in test bolus phase of CT coronary angiography (CTCA) and CT pulmonary angiography (CTPA) to save dose without compromising diagnostic quality

Objectives

The purpose of this study was to determine whether performing the test bolus (TB) of computed tomography coronary angiography (CTCA) and computed tomography pulmonary angiography (CTPA) at 80 kVp reduces dose without compromising diagnostic quality.

Methods

An 80 kVp TB protocol for CTCA and CTPA was retrospectively compared to standard TB protocol (non-obese: 100 kVp, obese: 120 kVp). CT angiogram parameters were unchanged between cohorts. Thirty-seven consecutive 80 kVp TB CTCA images were compared to 53 standard CTCA images. Fifty consecutive CTPAs from each protocol were analysed. Diagnostic quality of the CT angiogram was assessed by: mean attenuation, signal-to-noise ratio (SNR) in the ascending aorta (AA) in CTCA and in the main pulmonary artery (MPA) in CTPA, diagnostic rate, and number of repeated monitoring scans. Mean effective dose was estimated using the dose-length product.

Results

Mean TB effective doses were significantly lower (P?Conclusions Routinely performing TB at 80 kVp, regardless of body habitus, in CTCA and CTPA results in a small but significant dose reduction, without compromising CT angiogram diagnostic quality.

Key Points

? CT coronary angiography is performed to exclude the presence of significant coronary atherosclerosis. ? CT pulmonary angiography is performed to diagnose pulmonary thromboembolism. ? This retrospective study showed dose reduction by performing test bolus at 80 kVp. ? Diagnosis can be made with reduced exposure to ionising radiation.     

Image noise-based dose adaptation in dynamic volume CT of the heart: dose and image quality optimisation in comparison with BMI-based dose adaptation

Objectives

To compare the image quality and radiation dose using image-noise (IN)-based determination of X-ray tube settings compared with a body mass index (BMI)-based protocol during CT coronary angiography (CTCA).

Methods

Two hundred consecutive patients referred for CTCA to our institution were divided into two groups: BMI-based, 100 patients had CTCA with the X-ray tube current adjusted to the patient’s BMI while maintaining a fixed tube potential of 120 kV; IN-based, 100 patients underwent imaging with the X-ray tube current and voltage adjusted to the IN measured within the mid-left ventricle on a pre-acquisition trans-axial image. Two independent cardiac radiologists performed blinded image quality assessment with quantification of the IN and signal-to-noise ratio (SNR) from the mid-LV and qualitative assessment using a three-point score. Radiation dose (CTDI and DLP) was recorded from the console.

Results

Results showed: IN (HU): BMI-based, 30.1?±?9.9; IN-based, 33.1?±?6.7; 32 % variation reduction (P?=?0.001); SNR: BMI-based, 18.6?±?7.1; IN-based, 15.4?±?3.7; 48 % variation reduction (P?<?0.0001). Visual scores: BMI-based, 2.3?±?0.6; IN-based, 2.2?±?0.5 (P?=?0.54). Radiation dose: CTDI (mGy), BMI-based, 22.68?±?8.9; IN-based, 17.16?±?7.6; 24.3 % reduction (P?<?0.001); DLP (mGy.cm), BMI-based, 309.3?±?127.5; IN-based, 230.6?±?105.5; 25.4 % reduction (P?<?0.001).

Conclusions

Image-noise-based stratification of X-ray tube parameters for CTCA results in 32 % improvement in image quality and 25 % reduction in radiation dose compared with a BMI-based protocol.

Key Points

? Image quality and radiation dose are closely related in CT coronary angiography. ? So too are the image quality, radiation dose and body mass index (BMI). ? An image-noise-based CTCA protocol reduces the radiation dose by 25 %. ? It improves inter-patient image homogeneity by 32 %.     

High-pitch dual-source CT angiography of supra-aortic arteries: assessment of image quality and radiation dose

Introduction

High-pitch CT angiography (CTA) is a recent innovation that allows significant shortening of scan time with volume coverage of 43 mm per second. The aim of our study was to assess this technique in CTA of the head and neck.

Methods

CTA of supra-aortic arteries was performed in 50 patients using two acquisition protocols: conventional single-source 64-slice (pitch 1.2) and high-pitch dual-source 128-slice CT (pitch 3.2). Subjective and objective image quality of supra-aortic vessel ostia as well as intra- and extra-cranial segments was retrospectively assessed by blinded readers and radiation dose compared between the two protocols.

Results

Conventional and high-pitch CTA achieved comparable signal-to-noise ratios in arterial (54.3?±?16.5 versus 57.3?±?14.8; p?=?0.50) and venous segments (15.8?±?6.7 versus 18.9?±?8.9; p?=?0.21). High-pitch scanning was, however, associated with sharper delineation of vessel contours and image quality significantly improved at the level of supra-aortic vessel ostia (p?<?0.0001) as well as along the brachiocephalic trunk (p?<?0.0001), the subclavian arteries (p?<?0.0001), proximal common carotid arteries (p?=?0.01), and vertebral V1 segments (p?<?0.0001). Using the high-pitch mode, the dose-length product was reduced by about 35 % (218.2?±?30 versus 141.8?±?20 mGy?×?cm).

Conclusions

Due to elimination of transmitted cardiac motion, high-pitch CTA of the neck improves image quality in the proximity of the aortic arch while significantly lowering radiation dose. The technique thus qualifies as a promising alternative to conventional spiral CTA and may be particularly useful for identification of ostial stenosis.     

High-pitch dual-source CT coronary angiography with low volumes of contrast medium

Objectives

To assess the effect of lower volumes of contrast medium (CM) on image quality in high-pitch dual-source computed tomography coronary angiography (CTCA).

Methods

One-hundred consecutive patients (body weight 65–85 kg, stable heart rate ≤65 bpm, cardiac index ≥2.5 L/min/m²) referred for CTCA were prospectively enrolled. Patients were randomly assigned to one of five groups of different CM volumes (G₃₀, 30 mL; G₄₀, 40 mL; G₅₀, 50 mL; G₆₀, 60 mL; G₇₀, 70 mL; flow rate 5 mL/s each, iodine content 370 mg/mL). Attenuation within the proximal and distal coronary artery segments was analysed.

Results

Mean attenuation for men and women ranged from 345.0 and 399.1 HU in G₃₀ to 478.2 and 571.8 HU in G₇₀. Mean attenuation values were higher in groups with higher CM volumes (P?<?0.0001) and higher in women than in men (P?<?0.0001). The proportions of segments with attenuation of at least 300 HU in G₃₀, G₄₀, G₅₀, G₆₀ and G₇₀ were 89 %, 95 %, 98 %, 98 % and 99 %. CM volume of 30 mL in women and 40 mL in men proved to be sufficient to guarantee attenuation of at least 300 HU.

Conclusions

In selected patients high-pitch dual-source CTCA can be performed with CM volumes of 40 mL in men or 30 mL in women.

Key Points

? High-pitch dual-source coronary angiography is feasible with low contrast media volumes. ? Traditional injection rules still apply: higher volumes result in higher enhancement. ? The patient’s gender is a co-factor determining the level of contrast enhancement. ? Volumes can be reduced down to 30–40 mL in selected patients.     

Diagnostic accuracy of dual-source CT coronary angiography with prospective ECG-triggering on different heart rate patients

Objective

To evaluate the diagnostic accuracy of dual-source CT (DSCT) prospective ECG-triggering coronary angiography in patients with different heart rate (HR).

Methods

103 patients with suspected coronary artery disease underwent DSCT prospective ECG-triggered coronary angiography and invasive coronary angiography (ICA). The patients were grouped by HR during CT scans: low HR (??60?bpm, n?=?34); medium HR (60?n?=?36) and high HR (>70?bpm, n?=?33). The sensitivity and specificity of DSCT in detecting ??50% stenosis were compared among subgroups where ICA was the gold standard. Image quality was scored using a 4-point scale.

Results

A total of 1,580 (95.9%) coronary artery segments were evaluable. Sensitivity and specificity were 82.8% and 98.4%, 88.3% and 98.7%, and 80.3% and 98.6% for different subgroups (all p?>?0.05). The overall area under the curve of the receiver-operating characteristic analysis was 0.94. The image quality scores were 3.1?±?0.3, 3.1?±?0.3 and 3.0?±?0.4 for subgroups (p?>?0.05). The overall average effective radiation dose was 3.60?±?1.60?mSv.

Conclusion

DSCT coronary angiography with prospective ECG-triggering could be just as accurate in patients with medium to high HR compared to those with low HR.     

Accuracy, image quality and radiation dose comparison of high-pitch spiral and sequential acquisition on 128-slice dual-source CT angiography in children with congenital heart disease

Objectives

To compare accuracy, image quality and radiation dose between high-pitch spiral and sequential modes on 128-slice dual-source computed tomographic (DSCT) angiography in children with congenital heart disease (CHD).

Methods

Forty patients suspected with CHD underwent 128-slice DSCT angiography with high-pitch mode and sequential mode respectively. All the anomalies were confirmed by the surgical and/or the conventional cardiac angiography (CCA) findings. The diagnostic accuracy, the subjective and objective image quality and effective radiation doses were compared.

Results

There was no significant difference in diagnostic accuracy (χ ² ?=?0.963, P?>?0.05), the objective parameters for image quality (P?>?0.05) and the image quality of great vessels (u?=?167.500, P?>?0.05) between the two groups. The image quality of intracardiac structures and coronary arteries was significantly better in the sequential mode group than that in the high-pitch group (u?=?112.500 and 100.000, P?t?=?5.287, P?Conclusions Both the high-pitch and the sequential modes for 128-slice DSCT angiography provide high accuracy for the assessment of CHD in children, while the high-pitch mode, even with some image quality decrease, further significantly lowers the radiation dose.

Key Points

? Modern CT provides excellent anatomical detail of congenital heart disease. ? Dual source CT systems offer high-pitch spiral and sequential modes. ? The high-pitch mode provides high accuracy for the assessment of CHD. ? A few images using the high-pitch mode were occasionally slightly degraded. ? But the high-pitch mode significantly lowers the radiation dose.     

Prospectively ECG-triggered sequential dual-source coronary CT angiography in patients with atrial fibrillation: comparison with retrospectively ECG-gated helical CT

Objective

To investigate the feasibility of applying prospectively ECG-triggered sequential coronary CT angiography (CCTA) to patients with atrial fibrillation (AF) and evaluate the image quality and radiation dose compared with a retrospectively ECG-gated helical protocol.

Methods

100 patients with persistent AF were enrolled. Fifty patients were randomly assigned to a prospective protocol and the other patients to a retrospective protocol using a second-generation dual-source CT (DS-CT). Image quality was evaluated using a four-point grading scale (1 = excellent, 2 = good, 3 = moderate, 4 = poor) by two reviewers on a per-segment basis. The coronary artery segments were considered non-diagnostic with a quality score of 4. The radiation dose was evaluated.

Results

Diagnostic segment rate in the prospective group was 99.4 % (642/646 segments), while that in the retrospective group was 96.5 % (604/626 segments) (P?<?0.001). Effective dose was 4.29?±?1.86 and 11.95?±?5.34 mSv for each of the two protocols (P?<?0.001), which was a 64 % reduction in the radiation dose for prospective sequential imaging compared with retrospective helical imaging.

Conclusion

In AF patients, prospectively ECG-triggered sequential CCTA is feasible using second-generation DS-CT and can decrease >60 % radiation exposure compared with retrospectively ECG-gated helical imaging while improving diagnostic image quality.

Key Points

? Coronary computed tomographic angiography (CCTA) can be difficult in patients with arrhythmias. ? Prospectively ECG-triggered sequential CCTA is feasible in patients with atrial fibrillation. ? Prospective sequential imaging can improve quality compared with retrospective analysis. ? Prospective sequential imaging decreases radiation exposure by 64 % compared with retrospective mode.     

Dose reduction in dynamic CT stress myocardial perfusion imaging: comparison of 80-kV/370-mAs and 100-kV/300-mAs protocols

Objectives

To determine the effect of reduced 80-kV tube voltage with increased 370-mAs tube current on radiation dose, image quality and estimated myocardial blood flow (MBF) of dynamic CT stress myocardial perfusion imaging (CTP) in patients with a normal body mass index (BMI) compared with a 100-kV and 300-mAs protocol.

Methods

Thirty patients with a normal BMI (<25 kg/m²) with known or suspected coronary artery disease underwent adenosine-stress dual-source dynamic CTP. Patients were randomised to 80-kV/370-mAs (n?=?15) or 100-kV/300-mAs (n?=?15) imaging. Maximal enhancement and noise of the left ventricular (LV) cavity, contrast-to-noise ratio (CNR) and MBF of the two groups were compared.

Results

Imaging with 80-kV/370-mAs instead of 100-kV/300-mAs was associated with 40 % lower radiation dose (mean dose–length product, 359?±?66 vs 628?±?112 mGy?cm; P?<?0.001 ) with no significant difference in CNR (34.5?±?13.4 vs 33.5?±?10.4; P?=?0.81) or MBF in non-ischaemic myocardium (0.95?±?0.20 vs 0.99?±?0.25 ml/min/g; P?=?0.66). Studies obtained using 80-kV/370-mAs were associated with 30.9 % higher maximal enhancement (804?±?204 vs 614?±?115 HU; P?<?0.005), and 31.2 % greater noise (22.7?±?3.5 vs 17.4?±?2.6; P?<?0.001).

Conclusions

Dynamic CTP using 80-kV/370-mA instead of 100-kV/300-mAs allowed 40 % dose reduction without compromising image quality or MBF. Tube voltage of 80-kV should be considered for individuals with a normal BMI.

Key Points

? CT stress perfusion imaging (CTP) is increasingly used to assess myocardial function. ? Dynamic CTP is feasible at 80-kV in patients with normal BMI. ? An 80-kV/370-mAs protocol allows 40 % dose reduction compared with 100-kV/300-mAs. ? Contrast-to-noise ratio and myocardial blood flow of the two protocols were comparable.     

Radiation dose considerations by intra-individual Monte Carlo simulations in dual source spiral coronary computed tomography angiography with electrocardiogram-triggered tube current modulation and adaptive pitch

Objectives

To evaluate radiation dose levels in patients undergoing spiral coronary computed tomography angiography (CTA) on a dual-source system in clinical routine.

Methods

Coronary CTA was performed for 56 patients with electrocardiogram-triggered tube current modulation (TCM) and heart-rate (HR) dependent pitch adaptation. Individual Monte Carlo (MC) simulations were performed for dose assessment. Retrospective simulations with constant tube current (CTC) served as reference. Lung tissue was segmented and used for organ and effective dose (ED) calculation.

Results

Estimates for mean relative ED was 7.1?±?2.1?mSv/100?mAs for TCM and 12.5?±?5.3?mSv/100?mAs for CTC (P?70?bpm, 29?±?12%). However lowest ED is achieved at high HR (5.2?±?1.5?mSv/100?mAs), compared with intermediate (6.7?±?1.6?mSv/100?mAs) and low (8.3?±?2.1?mSv/100?mAs) HR when automated pitch adaptation is applied.

Conclusions

Radiation dose savings up to 52% are achievable by TCM at low and regular HR. However lowest ED is attained at high HR by pitch adaptation despite inferior radiation dose reduction by TCM.

Key Points

? Monte Carlo simulations allow for individual radiation dose calculations. ? ECG-triggered tube current modulation (TCM) can effectively reduce radiation dose. ? Slow and regular heart rates allow for highest dose reductions by TCM. ? Adaptive pitch accounts for lowest radiation dose at high heart rates. ? Women receive higher effective dose than men undergoing spiral coronary CT-angiography.     

Feasibility of prospectively ECG-triggered high-pitch coronary CT angiography with 30 mL iodinated contrast agent at 70 kVp: initial experience

Objectives

To evaluate the feasibility, image quality and radiation dose of prospectively ECG-triggered high-pitch coronary CT angiography (CCTA) with 30 mL contrast agent at 70 kVp.

Methods

Fifty-eight patients with suspected coronary artery disease, a body mass index (BMI) of less than 25 kg/m², sinus rhythm and a heart rate (HR) of less than 70 beats per minute (bpm) were prospectively enrolled in this study. Thirty mL of 370 mg I/mL iodinated contrast agent was administrated at a flow rate of 5 mL/s. All patients underwent prospectively ECG-triggered high-pitch CCTA on a second-generation dual-source CT system at 70 kVp using automated tube current modulation.

Results

Fifty-six patients (96.6 %) had diagnostic CCTA images and two patients (3.4 %) had one vessel with poor image quality each rated as non-diagnostic. No significant effects of HR, HR variability and BMI on CCTA image quality were observed (all P?>?0.05). Effective dose was 0.17?±?0.02 mSv and the size-specific dose estimate was 1.03?±?0.13 mGy.

Conclusion

Prospectively ECG-triggered high-pitch CCTA at 70 kVp with 30 mL of contrast agent can provide diagnostic image quality at a radiation dose of less than 0.2 mSv in patients with a BMI of less than 25 kg/m² and an HR of less than 70 bpm.

Key points

? Prospectively ECG-triggered high-pitch CCTA at 70 kVp/30 mL contrast agent is feasible. ? Diagnostic image quality can be obtained at a radiation dose of less than 0.2 mSv. ? This protocol is suitable for normal-weight patients with slow heart rate.     

Coronary artery stent imaging with 128-slice dual-source CT using high-pitch spiral acquisition in a cardiac phantom: comparison with the sequential and low-pitch spiral mode

Objective

To evaluate coronary stents in vitro using 128-slice-dual-source computed tomography (CT).

Methods

Twelve different coronary stents placed in a non-moving cardiac/chest phantom were examined by 128-slice dual-source CT using three CT protocols [high-pitch spiral (HPS), sequential (SEQ) and conventional spiral (SPIR)]. Artificial in-stent lumen narrowing (ALN), visible inner stent area (VIA), artificial in-stent lumen attenuation (ALA) in percent, image noise inside/outside the stent and CTDIvol were measured.

Results

Mean ALN was 46% for HPS, 44% for SEQ and 47% for SPIR without significant difference. Mean VIA was similar with 31% for HPS, 30% for SEQ and 33% for SPIR. Mean ALA was, at 5% for HPS, significantly lower compared with ?11% for SPIR (p?=?0.024), but not different from SEQ with ?1%. Mean image noise was significantly higher for HPS compared with SEQ and SPIR inside and outside the stent (p?<?0.001). CTDIvol was lower for HPS (5.17 mGy), compared with SEQ (9.02 mGy) and SPIR (55.97 mGy), respectively.

Conclusion

The HPS mode of 128-slice dual-source CT yields fewer artefacts inside the stent lumen compared with SPIR and SEQ, but image noise is higher. ALN is still too high for routine stent evaluation in clinical practice. Radiation dose of the HPS mode is markedly (less than about tenfold) reduced.     

Diagnostic performance of computed tomography coronary angiography to detect and exclude left main and/or three-vessel coronary artery disease

Objectives

To determine the diagnostic performance of CT coronary angiography (CTCA) in detecting and excluding left main (LM) and/or three-vessel CAD (“high-risk” CAD) in symptomatic patients and to compare its discriminatory value with the Duke risk score and calcium score.

Materials and methods

Between 2004 and 2011, a total of 1,159 symptomatic patients (61?±?11 years, 31 % women) with stable angina, without prior revascularisation underwent both invasive coronary angiography (ICA) and CTCA. All patients gave written informed consent for the additional CTCA. High-risk CAD was defined as LM and/or three-vessel obstructive CAD (≥50 % diameter stenosis).

Results

A total of 197 (17 %) patients had high-risk CAD as determined by ICA. The sensitivity, specificity, positive predictive value, negative predictive value, positive and negative likelihood ratios of CTCA were 95 % (95 % CI 91–97 %), 83 % (80–85 %), 53 % (48–58 %), 99 % (98–99 %), 5.47 and 0.06, respectively. CTCA provided incremental value (AUC 0.90, P?<?0.001) in the discrimination of high-risk CAD compared with the Duke risk score and calcium score.

Conclusions

CTCA accurately excludes high-risk CAD in symptomatic patients. The detection of high-risk CAD is suboptimal owing to the high percentage (47 %) of overestimation of high-risk CAD. CTCA provides incremental value in the discrimination of high-risk CAD compared with the Duke risk score and calcium score.

Key Points

? Computed tomography coronary angiography (CTCA) accurately excludes high-risk coronary artery disease. ? CTCA overestimates high-risk coronary artery disease in 47?%. ? CTCA discriminates high-risk CAD better than clinical evaluation and coronary calcification.     

Assessment of coronary artery disease and calcified coronary plaque burden by computed tomography in patients with and without diabetes mellitus

Purpose

To compare the coronary atherosclerotic burden in patients with and without type-2 diabetes using CT Coronary Angiography (CTCA).

Methods and Materials

147 diabetic (mean age: 65?±?10?years; male: 89) and 979 nondiabetic patients (mean age: 61?±?13?years; male: 567) without a history of coronary artery disease (CAD) underwent CTCA. The per-patient number of diseased coronary segments was determined and each diseased segment was classified as showing obstructive lesion (luminal narrowing >50%) or not. Coronary calcium scoring (CCS) was assessed too.

Results

Diabetics showed a higher number of diseased segments (4.1?±?4.2 vs. 2.1?±?3.0; p??400 (p?p?p?p?=?0.003) and obstructive CAD (12.5% vs. 3.8%, p?=?0.01). Among patients with CCS????10 all diabetics with obstructive CAD had a zero CCS and one patient was asymptomatic.

Conclusions

Diabetes was associated with higher coronary plaque burden. The present study demonstrates that the absence of coronary calcification does not exclude obstructive CAD especially in diabetics.     

Anomalous origin of the coronary artery from the wrong coronary sinus evaluated with computed tomography: “High-risk” anatomy and its clinical relevance

Objective

The aim of the study was to assess coronary arteries arising from the wrong coronary sinus, including CT-evaluated high-risk anatomic features, clinical symptoms and cardiac events during follow-up.

Methods

A total of 7,115 patients scheduled for 64-slice or dual-source cardiac CT were screened for the presence of isolated anomalous origin of the coronary artery from the wrong coronary sinus.

Results

Anomalous origin of the coronary artery was found in 54 (0.76 %) patients (29 men, 25 women, mean age 60.9?±?11.6 years). Sixteen (30 %) patients with abnormal right coronary origin (ARCA) more commonly had a slit-like orifice (15 vs. 3; p?p?p?p?=?0.03). Patients with ARCA tended to show higher occurrence of cardiac events in the follow-up than individuals with ALCA and ALCx (5 vs. 4; p?=?NS).

Conclusions

High-risk anatomy features are most common in patients with ARCA and these patients also have higher prevalence of chest pain and cardiac events in the follow-up than individuals with ALCA and ALCx.

Key Points

? Multislice computed tomography enables detection and evaluation of the coronary artery anomalies. ? Anomalous anatomy of the coronary artery potentially influences the prevalence of adverse events. ? Adverse events tend to be most common in anomalous right coronary arteries.     

High-pitch dual-source CT angiography of the aortic valve-aortic root complex without ECG-synchronization

Purpose

To compare image quality and radiation dose of high-pitch computed tomography angiography(CTA) of the aortic valve-aortic root complex with and without prospective ECG-gating compared to a retrospectively ECG-gated standard-pitch acquisition.

Materials and Methods

120 patients(mean age 68?±?13 years) were examined using a 128-slice dual-source CT system using prospectively ECG-gated high-pitch(group A; n?=?40), non-ECG-gated high-pitch(group B; n?=?40) or retrospectively ECG-gated standard-pitch(C; n?=?40) acquisition techniques. Image quality of the aortic root, valve and ascending aorta including the coronary ostia was assessed by two independent readers. Image noise was measured, radiation dose estimates were calculated.

Results

Interobserver agreement was good(κ?=?0.64–0.78). Image quality was diagnostic in 38/40 patients(group A), 37/40(B) and 38/40(C) with no significant difference in number of patients with diagnostic image quality among all groups (p?=?0.56). Significantly more patients showed excellent image quality in group A compared to groups B and C(each, p?<?0.01). Average image noise was significantly different between all groups(p?<?0.05). Mean radiation dose estimates in groups A and B(each; 2.4?±?0.3 mSv) were significantly lower compared to group C(17.5?±?4.4 mSv; p?<?0.01).

Conclusion

High-pitch dual-source CTA provides diagnostic image quality of the aortic valve-aortic root complex even without ECG-gating at 86% less radiation dose when compared to a standard-pitch ECG-gated acquisition.     

Accuracy of dual-energy computed tomography for the measurement of iodine concentration using cardiac CT protocols: validation in a phantom model

Purpose

To assess the accuracy of dual-energy CT (DECT) for the quantification of iodine concentrations in a thoracic phantom across various cardiac DECT protocols and simulated patient sizes.

Materials and methods

Experiments were performed on first- and second-generation dual-source CT (DSCT) systems in DECT mode using various cardiac DECT protocols. An anthropomorphic thoracic phantom was equipped with tubular inserts containing known iodine concentrations (0–20 mg/mL) in the cardiac chamber and up to two fat-equivalent rings to simulate different patient sizes. DECT-derived iodine concentrations were measured using dedicated software and compared to true concentrations. General linear regression models were used to identify predictors of measurement accuracy

Results

Correlation between measured and true iodine concentrations (n?=?72) across CT systems and protocols was excellent (R?=?0.994–0.997, P?<?0.0001). Mean measurement errors were 3.0?±?7.0 % and ?2.9?±?3.8 % for first- and second-generation DSCT, respectively. This error increased with simulated patient size. The second-generation DSCT showed the most stable measurements across a wide range of iodine concentrations and simulated patient sizes.

Conclusion

Overall, DECT provides accurate measurements of iodine concentrations across cardiac CT protocols, strengthening the case for DECT-derived blood volume estimates as a surrogate of myocardial blood supply.

Key Points

? Dual-energy CT provides new opportunities for quantitative assessment in cardiac imaging. ? DECT can quantify myocardial iodine as a surrogate for myocardial perfusion. ? DECT measurements of iodine concentrations are overall very accurate. ? The accuracy of such measurements decreases as patient size increases.