128-slice Dual-source CT Research Articles

The Left Atrio-Vertebral Ratio: a new simple means for assessing left atrial enlargement on Computed Tomography.

The purpose of this study is to describe a new method to quickly estimate left atrial enlargement (LAE) on Computed Tomography. Left atrial (LA) volume was assessed with a 3D-threshold Hounsfield unit detection technique, including left atrial appendage and excluding pulmonary venous confluence, in 201 patients with ECG-gated 128-slice dual-source CT and indexed to body surface area. LA and vertebral axial diameter and area were measured at the bottom level of the right inferior pulmonary vein ostium. Ratio of LA diameter and surface on vertebra (LAVD and LAVA) were compared to LA volume. In accordance with the literature, a cutoff value of 78 ml/m2 was chosen for maximal normal LA volume. 18% of LA was enlarged. The best cutoff values for LAE assessment were 2.5 for LAVD (AUC: 0.65; 95% CI: 0.58-0.73; sensitivity: 57%; specificity: 71%), and 3 for LAVA (AUC: 0.78; 95% CI: 0.72-0.84; sensitivity: 67%; specificity: 79%), with higher accuracy for LAVA (P=0.015). Inter-observer and intra-observer variability were either good or excellent for LAVD and LAVA (respective intraclass coefficients: 0.792 and 0.910; 0.912 and 0.937). A left atrium area superior to three times the vertebral area indicates LAE with high specificity. • Left atrial enlargement is a frequent condition associated with poor cardiac outcome. • Left atrial enlargement is highly time-consuming to diagnose on CT. • The left atrio-vertebral ratio quickly assesses left atrial enlargement. • A left atrial area > three times vertebral area is highly specific.

Coronary computed tomography angiography using 128-slice dual-source computed tomography in patients with severe calcification.

To compare coronary computed tomography angiography (CTA) and coronary angiography (CAG) with regard to luminal graphic definition of calcified segments using 128-slice dual-source computed tomography (DSCT), specifically for patients with an Agatston score >400. Of 1148 consecutive patients who underwent coronary CTA using a 128-slice DSCT, 132 subjects had severe calcification with an Agatston score >400. Thirty-nine of the 132 patients who had undergone CAG within 3months before or after coronary CTA were included. We investigated the distribution of calcification, and we visually evaluated significant stenosis in the calcified and all segments. Results were compared with CAG. The target group in this study had a very high mean Agatston score of 1771±1724. Results for sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 247 calcified vs all 325 segments were as follows: sensitivity 93.2 vs 92.2%, specificity 83.9 vs 87.5%, PPV 70.8 vs 69.6%, and NPV 96.7 vs 97.3%, respectively. 128-slice DSCT has potential for evaluation of calcified segments in the lumen, even in patients whose Agatston score exceeds 400.

Free-breathing high-pitch 80 kVp dual-source computed tomography of the pediatric chest: Image quality, presence of motion artifacts and radiation dose

ObjectivesTo investigate image quality, presence of motion artifacts and effects on radiation dose of 80kVp high-pitch dual-source CT (DSCT) in combination with an advanced modeled iterative reconstruction algorithm (ADMIRE) of the pediatric chest compared to single-source CT (SSCT). Materials and methodsThe study was approved by the institutional review board. Eighty-seven consecutive pediatric patients (mean age 9.1±4.9years) received either free-breathing high-pitch (pitch 3.2) chest 192-slice DSCT (group 1, n=31) or standard-pitch (pitch 1.2) 128-slice SSCT (group 2, n=56) with breathing-instructions by random assignment. Tube settings were similar in both groups with 80 kVp and 74 ref. mAs. Images were reconstructed using FBP for both groups. Additionally, ADMIRE was used in group 1. Effective thorax diameter, image noise, and signal-to-noise ratio (SNR) of the pectoralis major muscle and the thoracic aorta were calculated. Motion artifacts were measured as doubling boarders of the diaphragm and the heart. Images were rated by two blinded readers for overall image quality and presence of motion artifacts on 5-point-scales. Size specific dose estimates (SSDE, mGy) and effective dose (ED, mSv) were calculated. ResultsAge and effective thorax diameter showed no statistically significant differences in both groups. Image noise and SNR were comparable (p>0.64) for SSCT and DSCT with ADMIRE, while DSCT with FBP showed inferior results (p<0.01). Motion artifacts were reduced significantly (p=0.001) with DSCT. DSCT with ADMIRE showed the highest overall IQ (p<0.0001). Radiation dose was lower for DSCT compared to SSCT (median SSDE: 0.82mGy vs. 0.92mGy, p<0.02; median ED: 0.4 mSv vs. 0.48mSv, p=0.02). ConclusionsHigh-pitch 80kVp chest DSCT in combination with ADMIRE reduces motion artifacts and increases image quality while lowering radiation exposure in free-breathing pediatric patients without sedation.

Evaluation of Liver Iron Deposition in Transfusion-Dependent Patients By Dual-Energy CT

▪[Introduction]The launch of the oral iron chelator "Deferasirox" has improved the outcomes of blood transfusion-dependent patients with iron overload in the last decade. Although serum ferritin (SF) remains the mostly commonly used metric to monitor body iron stores for decisions regarding the indication of iron chelate therapy, it is known to be affected by many factors. The liver iron concentration (LIC) is considered to be an indicator of total body iron stores, and the MR imaging-based R2 technique is the standard non-invasive technique used to evaluate LIC. However, this technique is not used in every institution due to some limitations such as its high cost and the requirement for special software. Although the application of CT, which is easy to use and inexpensive, needs to be considered for the evaluation of LIC, the use of conventional single energy CT (SECT) to measure LIC is also limited by normal variations in CT attenuation, predominantly in patients with mild iron overload. Moreover, SECT fails to detect iron in fatty livers, which has an inverse effect on attenuation by lowering CT numbers. Dual-energy CT (DECT) is a technique that is employed to obtain precise information on tissue composition and may be useful for monitoring LIC. It is based on substances showing different densities with two different energies, with each substance displaying its own energy-dependent change in CT attenuation. The role of DECT in monitoring LIC has not yet been clarified in blood transfusion-dependent patients with iron overload. We herein evaluated iron deposition in the livers of blood transfusion-dependent patients using DECT.[Patients and Methods]Seventeen blood transfusion-dependent patients underwent liver DECT using a dual-source 128-slice CT system, and SF levels were measured at same time. DECT images were acquired using a tube voltage pair of 140 kV and 80 kV or 140 kV and 100 kV, and the three-material decomposition of fat, soft tissue, and iron.[Results]The median age of patients was 52 years (range, 25 to 66), and 8 patients were male. Eight patients with AML, 3 with MDS, and 1 each with ALL, lymphoma, aplastic anemia, Evans syndrome, congenital dyserythropoietic anemia, and chronic renal failure underwent DECT. Nine patients had undergone stem cell transplantation before DECT, and 3 were receiving iron chelate therapy. The total number of units of blood transfused was available in 11 out of 17 patients. The median number of units given was 66 (range, 36 to 150). The median SF level was 2346 ng/ml (range, 569 to 7875). We divided patients into three groups based on SF levels: high >3000 ng/ml, intermediate 1000~3000 ng/ml, low <1000 ng/ml. Five patients were classified into the high SF group (range, 3765-7875 ng/ml), 8 into the intermediate SF group (1645-2916), and 4 into the low SF group (569-1240). Four patients in high, 4 in the intermediate, and 2 in the low SF groups showed diffuse iron deposition in the liver on DECT images. One patient in the high, 2 in the intermediate, and 2 patients in the low SF groups showed focal iron deposition in the left lobe of the liver. On the other hand, two patients in the intermediate SF group did not show iron deposition on DECT images. We then divided patients into two groups based on the number of units of blood transfused: 6 patients were classified into the high unit group (range, 66-150 units), and 5 into the low unit group (36-60). Four patients in the high unit and 3 in the low unit groups showed diffuse iron deposition in the liver on DECT images. Two patients in the high unit and 1 in the low unit groups showed focal iron deposition in the left lobe of the liver. One patient in the low unit group did not show iron deposition.[Conclusion]Discrepancies between SF levels and DECT images indicate that DECT is a useful technique for the accurate evaluation of LIC, and the detection of focal iron deposition in the liver may be useful for optimizing iron chelation therapy. DisclosuresNo relevant conflicts of interest to declare.

Computed Tomography Angiography with a 192-slice Dual-source Computed Tomography System: Improvements in Image Quality and Radiation Dose.

Purpose:This study aims to compare image quality, radiation dose, and the influence of the heart rate on image quality of high-pitch spiral coronary computed tomography angiography (CCTA) using 128-slice (second generation) dual-source CT (DSCT) and a 192-slice DSCT (third generation) scanner.Materials and Methods:Two consecutive cohorts of fifty patients underwent CCTA by high-pitch spiral scan mode using 128 or 192-slice DSCT. The 192-slice DSCT system has a more powerful roentgen tube (2 × 120 kW) that allows CCTA acquisition at lower tube voltages, wider longitudinal coverage for faster table speed (732 m/s), and the use of iterative reconstruction. Objective image quality was measured as the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Subjective image quality was evaluated using a Likert scale.Results:While the effective dose was lower with 192-slice DSCT (1.2 ± 0.5 vs. 0.6 ± 0.3 mSv; P < 0.001), the SNR (18.9 ± 4.3 vs. 11.0 ± 2.9; P < 0.001) and CNR (23.5 ± 4.8 vs. 14.3 ± 4.1; P < 0.001) were superior to 128-slice DSCT. Although patients scanned with 192-slice DSCT had a faster heart rate (59 ± 7 vs. 56 ± 6; P = 0.045), subjective image quality was scored higher (4.2 ± 0.8 vs. 3.0 ± 0.7; P < 0.001) compared to 128-slice DSCT.Conclusions:High-pitch spiral CCTA by 192-slice DSCT provides better image quality, despite a higher average heart rate, at lower radiation doses compared to 128-slice DSCT.

Image Quality and Radiation Dose for Prospectively Triggered Coronary CT Angiography: 128-Slice Single-Source CT versus First-Generation 64-Slice Dual-Source CT.

This study sought to compare the image quality and radiation dose of coronary computed tomography angiography (CCTA) from prospectively triggered 128-slice CT (128-MSCT) versus dual-source 64-slice CT (DSCT). The study was approved by the Medical Ethics Committee at Tongji Medical College of Huazhong University of Science and Technology. Eighty consecutive patients with stable heart rates lower than 70 bpm were enrolled. Forty patients were scanned with 128-MSCT, and the other 40 patients were scanned with DSCT. Two radiologists independently assessed the image quality in segments (diameter >1 mm) according to a three-point scale (1: excellent; 2: moderate; 3: insufficient). The CCTA radiation dose was calculated. Eighty patients with 526 segments in the 128-MSCT group and 544 segments in the DSCT group were evaluated. The image quality 1, 2 and 3 scores were 91.6%, 6.9% and 1.5%, respectively, for the 128-MSCT group and 97.6%, 1.7% and 0.7%, respectively, for the DSCT group, and there was a statistically significant inter-group difference (P ≤ 0.001). The effective doses were 3.0 mSv in the 128-MSCT group and 4.5 mSv in the DSCT group (P ≤ 0.001). Compared with DSCT, CCTA with prospectively triggered 128-MSCT had adequate image quality and a 33.3% lower radiation dose.

Triple rule-out CT angiography protocol with restricting field of view for detection of pulmonary thromboembolism and aortic dissection in emergency department patients: simulation of modified CT protocol for reducing radiation dose

Background Triple rule-out computed tomography (TRO CT) is a CT protocol designed to simultaneously evaluate the coronary, aorta, and pulmonary arteries. Purpose To evaluate potential diagnostic performance of TRO CT with restricted volume coverage for detection of pulmonary thromboembolism (PTE) and aortic dissection (AD). Material and Methods This study included 1224 consecutive patients with acute chest pain who visited the emergency department and underwent TRO CT using a 128-slice dual-source CT. Image data were reconstructed according to the display field of view (DFOV) of coronary CT angiography (CCTA) and TRO CT protocols in each patient. The presence of PTE and AD was evaluated by independent observers in each DFOV. The radiation dose was calculated to evaluate the potential benefits by restricting z-axis coverage to cardiac scan range instead of the whole thorax. Results Among all patients, 22 cases with PTE (1.9%) and nine cases with AD (0.8%) were found. Except for one PTE case, all cases were detected on both DFOV of TRO CT and CCTA. Mean effective dose for evaluation of entire thorax and cardiac scan coverage were 5.9 ± 1.1 mSv and 3.5 ± 0.7 mSv, respectively. Conclusion Isolated PTE and AD outside the CCTA DFOV rarely occur. Therefore, modified TRO CT protocol using cardiac scan coverage can be adopted to detect PTE and AD with reduced radiation dose.

ESTIMATION OF CARDIAC CT ANGIOGRAPHY RADIATION DOSE TOWARD THE ESTABLISHMENT OF NATIONAL DIAGNOSTIC REFERENCE LEVEL FOR CCTA IN IRAN.

In recent years, with the introduction of 64-slice CT and dual-source CT technology, coronary CT angiography (CCTA) has emerged as a useful diagnostic imaging modality as a non-invasive assessment of coronary heart disease.CT produces a larger radiation dose than other imaging tests and cardiac CT involves higher radiation dose with the advances in the spatial and temporal resolution. The aims of this study are patient dose assessment and establishment of national diagnostic reference level for CCTA in Iran.A questionnaire was sent to CCTA centers. Data for patient and CT protocols were obtained. The volumetric CT dose index (CTDIvol), dose length product (DLP) and total DLP were considered in the 32 cm standard body phantom. Calculation of estimated effective dose (ED) was obtained by multiplying the DLP by a conversion factor [k=0.014 mSv (mGy·cm)-1]. Mean value of CTDIvol and DLP for CCTA was 50 mGy and 825 mGy·cm. The third quartile (75th) of the distribution of mean CTDIvol (66.54 mGy) and DLP (1073 mGy·cm) values was expressed as the diagnostic reference level (DRL) for CCTA in Iran. The median of ED was 10.26 mSv and interquartile range of ED was 7.08-15.03 mSv. A large variety in CTDIvol and DLP among CT scanner and different sites due to variability in CT parameter is noted. It seems that training could help to reduce patient's dose.

Pre-test probability of obstructive coronary stenosis in patients undergoing coronary CT angiography: Comparative performance of the modified diamond-Forrester algorithm versus methods incorporating cardiovascular risk factors

BackgroundCurrent guidelines recommend the use of the Modified Diamond-Forrester (MDF) method to assess the pre-test likelihood of obstructive coronary artery disease (CAD). We aimed to compare the performance of the MDF method with two contemporary algorithms derived from multicenter trials that additionally incorporate cardiovascular risk factors: the calculator-based ‘CAD Consortium 2’ method, and the integer-based CONFIRM score. MethodsWe assessed 1069 consecutive patients without known CAD undergoing coronary CT angiography (CCTA) for stable chest pain. Obstructive CAD was defined as the presence of coronary stenosis ≥50% on 64-slice dual-source CT. The three methods were assessed for calibration, discrimination, net reclassification, and changes in proposed downstream testing based upon calculated pre-test likelihoods. ResultsThe observed prevalence of obstructive CAD was 13.8% (n=147). Overestimations of the likelihood of obstructive CAD were 140.1%, 9.8%, and 18.8%, respectively, for the MDF, CAD Consortium 2 and CONFIRM methods. The CAD Consortium 2 showed greater discriminative power than the MDF method, with a C-statistic of 0.73 vs. 0.70 (p<0.001), while the CONFIRM score did not (C-statistic 0.71, p=0.492).Reclassification of pre-test likelihood using the ‘CAD Consortium 2’ or CONFIRM scores resulted in a net reclassification improvement of 0.19 and 0.18, respectively, which would change the diagnostic strategy in approximately half of the patients. ConclusionsNewer risk factor-encompassing models allow for a more precise estimation of pre-test probabilities of obstructive CAD than the guideline-recommended MDF method. Adoption of these scores may improve disease prediction and change the diagnostic pathway in a significant proportion of patients.

Temporal resolution measurement of 128-slice dual source and 320-row area detector computed tomography scanners in helical acquisition mode using the impulse method

PurposeTo analyse the temporal resolution (TR) of modern computed tomography (CT) scanners using the impulse method, and assess the actual maximum TR at respective helical acquisition modes. MethodsTo assess the actual TR of helical acquisition modes of a 128-slice dual source CT (DSCT) scanner and a 320-row area detector CT (ADCT) scanner, we assessed the TRs of various acquisition combinations of a pitch factor (P) and gantry rotation time (R). ResultsThe TR of the helical acquisition modes for the 128-slice DSCT scanner continuously improved with a shorter gantry rotation time and greater pitch factor. However, for the 320-row ADCT scanner, the TR with a pitch factor of <1.0 was almost equal to the gantry rotation time, whereas with pitch factor of >1.0, it was approximately one half of the gantry rotation time. The maximum TR values of single- and dual-source helical acquisition modes for the 128-slice DSCT scanner were 0.138 (R/P=0.285/1.5) and 0.074s (R/P=0.285/3.2), and the maximum TR values of the 64×0.5- and 160×0.5-mm detector configurations of the helical acquisition modes for the 320-row ADCT scanner were 0.120 (R/P=0.275/1.375) and 0.195s (R/P=0.3/0.6), respectively. ConclusionBecause the TR of a CT scanner is not accurately depicted in the specifications of the individual scanner, appropriate acquisition conditions should be determined based on the actual TR measurement.

Reproducibility of semi-automatic coronary plaque quantification in coronary CT angiography with sub-mSv radiation dose

IntroductionCoronary computed tomographic angiography (CTA) can characterize coronary atherosclerotic plaque components as calcified and non-calcified. Quantitative measurements of coronary plaque burden by coronary CTA may play a role in serial studies to determine disease progression or response to medical therapies. The reproducibility from repeated assessment of such quantitative measurements from low-radiation dose coronary CTA has not been previously assessed. PurposeTo evaluate the interscan, interobserver and intraobserver reproducibility for coronary plaque volume assessment using semi-automatic plaque analyses algorithm in low radiation dose coronary CTA. MethodsIn 50 consecutive patients undergoing two 128-slice dual source CT scans within 12 days with a mean radiation dose of 0.7 mSv per coronary CTA, the interscan, interobserver and intraobserver reproducibility of coronary plaque assessment using validated software (AutoPlaq) were evaluated. ResultsInterscan, interobserver and intraobserver agreement for non-calcified and calcified plaque volumes were excellent (Spearman rho 0.87–0.99). Interscan mean percentage difference in non-calcified and calcified plaque volumes were 0.1% (p = 0.8) and 1.9% (p = 0.19) with limits of agreement of ±11% and ±48.5%; per inter- and intraobserver mean percentage differences were 0.1% (p = 0.25) and 0.3% (p = 0.001), and 0.3% (p = 0.33) and 0.4% (p = 0.59) with limits of agreement of ±7% and ±32.9%, and ±6.6% and ±32.1%, respectively. ConclusionA semi-automatic plaque assessment algorithm in repeated low radiation dose coronary CTA allows for high reproducibility of coronary plaque characterization and quantification measures.

Diagnostic performance and radiation dose of lower extremity CT angiography using a 128-slice dual source CT at 80 kVp and high pitch.

Multi-detector computed tomography (MDCT) angiography is now used for the diagnosing patients with peripheral arterial disease. The dose of radiation is related to variable factors, such as tube current, tube voltage, and helical pitch. To assess the diagnostic performance and radiation dose of lower extremity CT angiography (CTA) using a 128-slice dual source CT at 80 kVp and high pitch in patients with critical limb ischemia (CLI). Twenty-eight patients (mean, 64.1 years; range, 39-80 years) with CLI were enrolled in this retrospective study and underwent CTA using a 128-slice dual source CT at 80 kVp and high pitch and subsequent intra-arterial digital subtraction angiography (DSA), which was used as a reference standard for assessing diagnostic performance. For arterial segments with significant disease (>50% stenosis), overall sensitivity, specificity, and accuracy of lower extremity CTA were 94.8% (95% CI, 91.7-98.0%), 91.5% (95% CI, 87.7-95.2%), and 93.1% (95% CI, 90.6-95.6%), respectively, and its positive and negative predictive values were 91.0% (95% CI, 87.1-95.0%), and 95.1% (95% CI, 92.1-98.1%), respectively. Mean radiation dose delivered to lower extremities was 266.6 mGy.cm. Lower extremity CTA using a 128-slice dual source CT at 80 kVp and high pitch was found to have good diagnostic performance for the assessment of patients with CLI using an extremely low radiation dose.

Automated Tube Voltage Adaptation in Combination with Advanced Modeled Iterative Reconstruction in Thoracoabdominal Third-Generation 192-Slice Dual-Source Computed Tomography: Effects on Image Quality and Radiation Dose

To evaluate image quality and radiation exposure of portal venous-phase thoracoabdominal third-generation 192-slice dual-source computed tomography (DSCT) with automated tube voltage adaptation (TVA) in combination with advanced modeled iterative reconstruction (ADMIRE). Fifty-one patients underwent oncologic portal venous-phase thoracoabdominal follow-up CT twice within 7 months. The initial examination was performed on second-generation 128-slice DSCT with fixed tube voltage of 120 kV in combination with filtered back projection reconstruction. The second examination was performed on a third-generation 192-slice DSCT using automated TVA in combination with ADMIRE. Attenuation and image noise of liver, spleen, renal cortex, aorta, vena cava inferior, portal vein, psoas muscle, and perinephric fat were measured. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Radiation dose was assessed as size-specific dose estimates (SSDE). Subjective image quality was assessed by two observers using five-point Likert scales. Interobserver agreement was calculated using intraclass correlation coefficients (ICC). Automated TVA set tube voltage to 90 kV (n = 8), 100 kV (n = 31), 110 kV (n = 11), or 120 kV (n = 1). Average SSDE was decreased by 34.9% using 192-slice DSCT compared to 128-slice 120-kV DSCT (7.8 ± 2.4 vs. 12.1 ± 3.2 mGy; P < .001). Image noise was substantially lower; SNR and CNR were significantly increased in 192-slice DSCT compared to 128-slice DSCT (all P < .005). Image quality was voted excellent for both acquisition techniques (5.00 vs. 4.93; P = .083). Automated TVA in combination with ADMIRE on third-generation 192-slice DSCT in portal venous-phase thoracoabdominal CT provides excellent image quality with reduced image noise and increased SNR and CNR, whereas average radiation dose is reduced by 34.9% compared to 128-slice DSCT.

PP.32.13

Objective: Adrenal venous sampling (AVS) is the preferred method to distinguish excess unilateral from bilateral aldosterone secretion in patients with primary aldosteronism. Although it is invasive and expensive conventional CT adrenal imaging is considered to be inferior to AVS. To examine whether 128-slice dual-source CT using strict standardized radiological diagnostic criteria may approach the diagnostic performance of AVS. Design and method: From May 2012 to August 2014 we performed both AVS and 128-slice dual-source CT in 50 consecutive patients with PA. AVS was pursued after correction of hypokalemia and adjustment of antihypertensive therapy, under continuous ACTH infusion. Blood samples were taken from both adrenal veins (AV) and the lower caval vein (LCV). Selective cannulation was defined as an AV/LCV ratio for cortisol of ≥3. Lateralization was defined as a dominant/non-dominant ratio for aldosterone-to-cortisol of ≥4. In addition suppression of the contralateral side was required. Computer tomography imaging was performed using 128-slice dual-source CT with a 1mm-thickness slice. As a diagnostic criterion of adrenal nodule on CT-scan a focal change > 7 mm was used. A diffuse thickening of adrenal limbs > 5 mm was thought to fit with adrenal hyperplasia. A unilateral change (adenoma/hyperplasia) was defined as a change within one single adrenal gland with normal contralateral gland. Bilateral abnormalities included bilateral adenomas and/or bilateral adrenal hyperplasia. Results: The cannulation failed in 2 (4%) subjects. No complications were observed during and after procedures. Twentythree patients (48%) demonstrated unilateral aldosterone production (14 left-sided, 9 right-sided), and 25 (48%) patients were characterized by bilateral aldosterone production. In 43,8% of the patients there was disagreement between results of AVS vs CT. In 11 subjects (22.9%) a unilateral change was found on CT-scan, while there was no lateralization on AVS. In 7 patients (14,6%) CT–scan revealed bilateral abnormalities or symmetrical normal adrenal glands whereas in AVS unilateral aldosterone secretion was observed. In 2 cases there was complete discordance between the affected sides as diagnosed by CT and AVS. Conclusions: Despite adopting strict radiological criteria to differentiate uni- from bilateral disease, the diagnostic performance of 128-slice dual-source CT-scan is inferior to that of AVS.

Dose levels and image quality of second-generation 128-slice dual-source coronary CT angiography in clinical routine.

To compare radiation exposure and image quality of second-generation 128-slice dual-source CT (DSCT) coronary angiography (cCTA) protocols. We retrospectively analyzed data from four groups with 25 patients, each examined by one of the following DSCT cCTA protocols: prospectively ECG-gated high-pitch (group 1) or sequential (group 2) acquisition, retrospectively ECG-gated acquisition in dual-energy (DECT, group 3) or dual-source (group 4) mode. CT dose index volume, dose length product, estimated radiation dose, contrast-to-noise- and signal-to-noise-ratios were compared. Subjective image quality was rated by two observers blinded to the protocols. High-pitch DSCT showed a mean estimated radiation dose of 1.27±0.62mSv, significantly (p<0.01) lower than sequential (2.04±0.94mSv), dual-energy (3.97±1.29mSv) or dual-source (8.11±4.95mSv) acquisition. Image noise showed no statistical difference (p>0.91), ranging from 15.2±4.4 (group 2) up to 24.5±22.0 (group 4). Each protocol showed diagnostic image quality in at least 98.1% of evaluated coronary segments without significant differences (p>0.05). Prospectively ECG-gated DSCT protocols enable cCTA with significant dose reduction and consistently diagnostic image quality. In patients requiring retrospectively ECG-gated DSCT for functional analysis or due to arrhythmia, dual-energy mode should be preferred over dual-source mode as it significantly decreases estimated dose without compromising image quality.

128-slice dual-source CT coronary angiography with prospectively electrocardiography-triggered high-pitch spiral mode: radiation dose, image quality, and diagnostic acceptability.

Dual-source computed tomography (CT) enables CT coronary angiography (CTCA) with a prospectively electrocardiography (ECG)-triggered high-pitch spiral (HPS) mode. To evaluate the radiation dose, image quality, and diagnostic acceptability of the HPS mode in CTCA and to compare HPS with the step-and-shoot (SAS) and low-pitch spiral (LPS) modes. One hundred and thirty-eight patients who underwent CTCA with a 128-slice dual-source CT scanner were retrospectively included in this study. Seventeen patients (average heart rate of ≤65 beats per minute [bpm] prior to acquisition) were evaluated in the HPS mode, 88 (average heart rate of >65 and ≤80 bpm prior to acquisition) in the SAS mode, and 33 (average heart rate of >80 bpm prior to acquisition or patients with an unstable heart rhythm) in the LPS mode. Radiation dose and image noise were recorded for each patient. Diagnostic acceptability was graded using a four-point scale (1, unacceptable; 2, suboptimal; 3, acceptable; 4, fully acceptable). The effective dose in the HPS mode was 1.5 ± 0.2 mSv, which was lower than that in SAS (8.9 ± 2.7 mSv) and LPS (21.5 ± 4.3 mSv) modes. There were no significant differences in the image noise levels in the descending aorta and left atrium. The average per-patient diagnostic acceptability was 3.2, 3.6, and 3.7 in HPS, SAS, and LPS modes, respectively. The radiation dose is lower with HPS than with other modes, and the HPS mode-acquired images of patients with heart rates of ≤65 bpm are nearly acceptable for diagnostic image interpretation.

Improved non-calcified plaque delineation on coronary CT angiography by sonogram-affirmed iterative reconstruction with different filter strength and relationship with BMI.

To prospectively compare non-calcified plaque delineation and image quality of coronary computed tomography angiography (CCTA) obtained with sinogram-affirmed iterative reconstruction (IR) with different filter strengths and filtered back projection (FBP). A total of 57 patients [28.1% females; body mass index (BMI) 29.2±6.5 kg/m(2)] were investigated. CCTA was performed using 128-slice dual-source CT. Images were reconstructed with standard FBP and sinogram-affirmed IR using different filter strength (IR-2, IR-3, IR-4) (SAFIRE, Siemens, Germany). Image quality of CCTA and a non-calcified plaque outer border delineation score were evaluated by using a 5-scale score: from 1= poor to 5= excellent. Image noise, contrast-to-noise ratio (CNR) of aortic root, left main (LM) and right coronary artery, and the non-calcified plaque delineation were quantified and compared among the 4 image reconstructions, and were compared between different BMI groups (BMI <28 and ≥28). Statistical analyses included one-way analysis of variance (ANOVA), least significant difference (LSD) and Kruskal-Wallis test. There were 71.9% patients in FBP, 96.5% in IR-2, 96.5% in IR-3 and 98.2% in IR-4 who had overall CCTA image quality ≥3, and there were statistical differences in CCTA exam image quality score among those groups, respectively (P<0.001). Sixty-one non-calcified plaques were detected by IR-2 to IR-4, out of those 11 (18%) were missed by FBP. Plaque delineation score increased constantly from FBP (2.7±0.4) to IR-2 (3.2±0.3), to IR-3 (3.5±0.3) up to IR-4 (4.0±0.4), while CNRs of the non-calcifying plaque increased and image noise decreased, respectively. Similarly, CNR of aortic root, LM and right coronary artery improved and image noise declined from FBP to IR-2, IR-3 and IR-4. There were no significant differences of image quality and plaque delineation score between low and high BMI groups within same reconstruction (all P>0.05). Significant differences in image quality and plaque delineation scores among different image reconstructions both in low and high BMI groups (all P<0.001) were found. I4f revealed the highest image quality and plaque delineation score. IR offers improved image quality and non-calcified plaque delineation as compared with FBP, especially if BMI is increasing. Importantly, 18% of non-calcified plaques were missed with FBP. IR-4 shows the best image quality score and plaque delineation score among the different IR-filter strength.

Application of optimal contrast medium injection protocol for 128-slice dual-source computed tomography in children with Tetralogy of Fallot

To compare the image qualities of different contrast medium injection protocols for 128-slice dual-source computed tomography (DSCT) in children with Tetralogy of Fallot (TOF). A total of 60 patients with TOF were randomly divided into groups A, B and C (n = 20 each). And 128-slice DSCT angiography was performed with sequential mode according to the contrast injection protocols: the volume of contrast medium was 1.2, 1.2 and 1.5 ml/kg and the injection time 10, 12 and 15 s respectively. Contrast medium was followed by a saline bolus for 10 s. Enhancement and noise of ascending aorta, main pulmonary artery, descending aorta and left ventricle were quantified. Signal-to-noise ratio (SNR), dose-length product (DLP) and effective dose (ED) were calculated. The absolute difference of left and right ventricular attenuations was calculated to represent the image uniformity. Subjective image quality was assessed by two radiologists in consensus. No significant difference existed in attenuation or SNR between three groups in the same evaluated anatomic regions. No significant difference existed in image quality of heart chamber and great vessels. The image uniformity (81 ± 65) and subjective image quality of artifacts of superior vena cava were significantly better in group B than those in groups A and C (179 ± 178, 106 ± 66, P < 0.05). The contrast medium injection protocol of 1.2 ml/kg volume contrast medium injected within 12 s may enhance the image quality of 128-slice dual-source CT in children with TOF.

Automated attenuation-based tube voltage selection for body CTA: Performance evaluation of 192-slice dual-source CT.

To assess radiation dose and image quality in body CT-angiography (CTA) with automated attenuation-based tube voltage selection (ATVS) on a 192-slice dual-source CT (DSCT). Forty patients (69.5 ± 9.6years) who had undergone body CTA with ATVS (ref.kVp 100, ref.mAs 90) using a 2x192-slice CT in single-source mode were retrospectively included. All patients had undergone prior CTA with a 2x128-slice CT and ATVS with identical imaging and contrast media protocols, serving for comparison. Images were reconstructed with iterative reconstruction at similar strength levels. Radiation dose was determined. Image quality was assessed semi-quantitatively (1:excellent, 5:non-diagnostic), aortic attenuation, noise and CNR were determined. As compared to 128-slice DSCT, 192-slice DSCT selected tube voltages were lower in 30 patients (75%), higher in 3 (7.5%), and similar in 7 patients (17.5%). CTDIvol was lower with 192-slice DSCT (4.7 ± 1.9mGy vs. 5.8 ± 2.1mGy; p < 0.001). Subjective image quality, mean aortic attenuation (342 ± 67HU vs. 268 ± 67HU) and CNR (9.8 ± 2.5 vs. 8.2 ± 2.9) were higher with 192-slice DSCT (all p < 0.01), all datasets being diagnostic. Our study suggests that ATVS of 192-slice DSCT for body CTA is associated with an improved image quality and further radiation dose reduction of 19% compared to 128-slice DSCT. • 192-slice DSCT allows imaging from 70kVp to 150kVp at 10kVp increments. • 192-slice DSCT allows for radiation-dose reduction in body-CTA with ATVS. • Subjective and objective image quality increase compared to 128-slice DSCT.

Application of Prospective ECG-Gated High-Pitch 128-Slice Dual-Source CT Angiography in the Diagnosis of Congenital Extracardiac Vascular Anomalies in Infants and Children

PurposeTo investigate the value of prospective ECG-gated high-pitch 128-slice dual-source CT (DSCT) angiography in the diagnosis of congenital extracardiac vascular anomalies in infants and children in comparison with transthoracic echocardiography (TTE).MethodsEighty consecutive infants or children clinically diagnosed of congenital heart disease and suspected with extracardiac vascular anomaly were enrolled, and 75 patients were finally included in this prospective study. All patients underwent prospective ECG-gated high-pitch DSCT angiography after TTE with an interval of 1–7 days. The diagnostic accuracy and sensitivity of high-pitch DSCT angiography and TTE were compared according to the surgical/CCA findings. The image quality of DSCT was assessed using a five-point scale. The effective radiation dose (ED) was calculated.ResultsA total of 17 congenital heart diseases and 162 separate extracardiac vascular anomalies were confirmed by surgical/CCA findings in 75 patients. The diagnostic accuracy of high-pitch DSCT angiography and TTE was 99.67% and 97.89%, respectively. The sensitivity of high-pitch DSCT angiography and TTE was 97.53% and 79.62%, respectively. There was significant difference regarding to the diagnostic accuracy and the sensitivity between high-pitch DSCT angiography and TTE (χ2 = 23.561 and 28.013, P<0.05). The agreement on the image quality scoring of DSCT between the two observers was excellent (κ = 0.81), and the mean score of image quality was 4.1±0.7. The mean ED of DSCT was 0.29±0.08 mSv.ConclusionsProspective ECG-gated high-pitch 128-slice DSCT angiography with low radiation dose and high diagnostic accuracy has higher sensitivity compared to TTE in the detection of congenital extracardiac vascular anomalies in infants and children.