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Objectives To evaluate the incidence of coronary in-stent restenosis (ISR) and neointimal proliferation by coronary CT angiography (CCTA) at 1-year follow-up in asymptomatic patients. Methods 234 patients (mean age: 67 ± 10.2 years, range 39–88 years, 180 males and 54 females) with 379 stents were prospectively enrolled in this study. Binary ISR was classified by CCTA into 4 types using Mehran classification. Neointimal proliferation was similarly classified into focal and diffuse types. All patients with CCTA-revealed ISR or neointimal proliferation underwent further invasive coronary angiography (ICA) for validation. Fisher's exact test was used for comparison. Results ICA revealed patent stents with neointimal proliferation in 39 patients (16.7%, 39/234) and binary ISR in 23 patients (9.8%, 23/234). Lesion-based analysis showed 12 type I ISR lesions, 4 type II ISR lesions, 1 type III ISR lesion and 7 type IV ISR lesions. Among cases with neointimal proliferation, 27 lesions were classified as focal type whereas 13 lesions were classified as diffuse type. Patients with diabetes mellitus were associated with higher incidence of CCTA-revealed neointimal proliferation (21/77 vs. 18/157, p = 0.002) as well as ISR (12/77 vs. 11/157, p = 0.038), compared to patients without diabetes. CCTA was found to have good diagnostic performance for neointimal proliferation and ISR detection as well as classification, with an overall accuracy of 84.4% (54/64). Conclusions Silent ISR as well as neointimal proliferation is not uncommon findings in asymptomatic post-stenting patients at 1-year interval, as revealed by CCTA. Patients with diabetes are prone to have higher incidence of neointimal proliferation.

To assess the diagnostic accuracy of standard axial 64-slice chest CT compared to aortic valve image plane ECG-gated cardiac CT for bicuspid aortic valves.The standard axial chest CT scans of 20 patients with known bicuspid aortic valves were blindly, randomly analyzed for (i) the appearance of the valve cusps, (ii) the largest aortic sinus area, (iii) the longest aortic cusp length, (iv) the thickest aortic valve cusp and (v) valve calcification. A second blinded reader independently analyzed the appearance of the valve cusps. Forty-two age- and sex-matched patients with known tricuspid aortic valves were used as controls. Retrospectively ECG-gated cardiac CT multiphase reconstructions of the aortic valve were used as the gold-standard.Fourteen (21%) scans were scored as unevaluable (7 bicuspid, 7 tricuspid). Of the remainder, there were 13 evaluable bicuspid valves, ten of which showed an aortic valve line sign, while the remaining three showed a normal Mercedes-Benz appearance owing to fused valve cusps. The 35 evaluable tricuspid aortic valves all showed a normal Mercedes-Benz appearance (P=0.001). Kappa analysis=0.62 indicating good interobserver agreement for the aortic valve cusp appearance. Aortic sinus areas, aortic cusp lengths and aortic cusp thicknesses of ≥ 3.8 cm(2), 3.2 cm and 1.6mm respectively on standard axial chest CT best distinguished bicuspid from tricuspid aortic valves (P0.0001 for all). Of evaluable scans, the sensitivity, specificity, positive and negative predictive values of standard axial chest CT in diagnosing bicuspid aortic valves was 77% (CI 0.54-1.0), 100%, 100% and 70% respectively.The aortic valve is evaluable in approximately 80% of standard chest 64-slice CT scans. Bicuspid aortic valves may be diagnosed on evaluable scans with good diagnostic accuracy. An aortic valve line sign, enlarged aortic sinuses and elongated, thickened valve cusps are specific CT features.

To investigate the effects of a new model-based type of iterative reconstruction (M-IR) technique, the iterative model reconstruction, on image quality of prospectively gated coronary CT angiography (CTA) acquired at low-tube-voltage.Thirty patients (16 men, 14 women; mean age 52.2 ± 13.2 years) underwent coronary CTA at 100-kVp on a 256-slice CT. Paired image sets were created using 3 types of reconstruction, i.e. filtered back projection (FBP), a hybrid type of iterative reconstruction (H-IR), and M-IR. Quantitative parameters including CT-attenuation, image noise, and contrast-to-noise ratio (CNR) were measured. The visual image quality, i.e. graininess, beam-hardening, vessel sharpness, and overall image quality, was scored on a 5-point scale. Lastly, coronary artery segments were evaluated using a 4-point scale to investigate the assessability of each segment.There was no significant difference in coronary arterial CT attenuation among the 3 reconstruction methods. The mean image noise of FBP, H-IR, and M-IR images was 29.3 ± 9.6, 19.3 ± 6.9, and 12.9 ± 3.3 HU, respectively, there were significant differences for all comparison combinations among the 3 methods (p0.01). The CNR of M-IR was significantly better than of FBP and H-IR images (13.5 ± 5.0 [FBP], 20.9 ± 8.9 [H-IR] and 39.3 ± 13.9 [M-IR]; p0.01). The visual scores were significantly higher for M-IR than the other images (p0.01), and 95.3% of the coronary segments imaged with M-IR were of assessable quality compared with 76.7% of FBP- and 86.9% of H-IR images.M-IR can provide significantly improved qualitative and quantitative image quality in prospectively gated coronary CTA using a low-tube-voltage.

Objective To evaluates a semi-automated method for Thoracic Aortic Aneurysm (TAA) measurement using ECG-gated Dual Source CT Angiogram (DSCTA). Methods This retrospective HIPAA compliant study was approved by our IRB. Transaxial maximum diameters of outer wall to outer wall were studied in fifty patients at seven anatomic locations of the thoracic aorta: annulus, sinus, sinotubular junction (STJ), mid ascending aorta (MAA) at the level of right pulmonary artery, proximal aortic arch (PROX) immediately proximal to innominate artery, distal aortic arch (DIST) immediately distal to left subclavian artery, and descending aorta (DESC) at the level of diaphragm. Measurements were performed using a manual method and semi-automated software. All readers repeated their measurements. Inter-method, intra-observer and inter-observer agreements were evaluated according to intraclass correlation coefficient (ICC) and Bland–Altman plot. The number of cases with manual contouring or center line adjustment for the semi-automated method and also the post-processing time for each method were recorded. Results The mean difference between semi-automated and manual methods was less than 1.3 mm at all seven points. Strong inter-method, inter-observer and intra-observer agreement was recorded at all levels (ICC ≥ 0.9). The maximum rate of manual adjustment of center line and contour was at the level of annulus. The average time for manual post-processing of the aorta was 19 ± 0.3 min, while it took 8.26 ± 2.1 min to do the measurements with the semi-automated tool (Vitrea version 6.0.0.1 software). The center line was edited manually at all levels, with most corrections at the level of annulus (60%), while the contour was adjusted at all levels with highest and lowest number of corrections at the levels of annulus and DESC (75% and 0.07% of the cases), respectively. Conclusion Compared to the commonly used manual method, semi-automated measurement of vessel dimensions is feasible in the thoracic aorta with the advantage of reduced post-processing time.

To assess the image quality (IQ) of an iterative reconstruction (IR) technique (iDose(4)) from prospective electrocardiography (ECG)-triggered coronary computed tomography angiography (coronary CTA) on a 256-slice multi-detector CT (MDCT) scanner and determine the optimal dose reduction using IR that can provide IQ comparable to filtered back projection (FBP).110 consecutive patients (69 men, 41 women; age: 54 ± 10 years) underwent coronary CTA on a 256-slice MDCT (Brilliance iCT, Philips Healthcare). The control group (Group A, n=21) were scanned using the conventional tube output (120 kVp, 210 mAs) and reconstructed using FBP. The other 4 groups were scanned with the same kVp but successively reduced tube output as follows: B[n=15]: 125 mAs; C[n=22]: 105 mAs; D[n=36]: 84 mAs: E[n=16]: 65 mAs) and reconstructed using IR levels of L3 (Group B), L4 (Group C) and L5 (Groups D and E), to compensate for the noise increase. All images were reconstructed using the same kernel (XCB). Two radiologists graded IQ in a blinded fashion on a 4-point scale (4 - excellent, 3 - good, 2 - fair and 1 - poor). Quantitative measurements of CT values, image noise and contrast-to-noise (CNR) were measured in each group. A receiver-operating characteristic (ROC) analysis was performed to determine a radiation reduction threshold up to which excellent IQ was maintained.There were no significant differences in objective noise, SNR and CNR values among Groups A, B, C, D, and E (P=0.14, 0.09, 0.17, respectively). There were no significant differences in the scores of the subjective IQ between Group A, and Groups B, C, D, E (P=0.23-0.97). Significant differences in image sharpness and study acceptability were observed between groups A and E (P0.05). Using the criterion of excellent IQ (score 4), the ROC curve of dose levels and IQ acceptability established a reduction of 60% of tube output (Group D) as optimum cutoff point (AUC: 0.72, 95% CI: 0.59-0.86). Group D (84 mAs with L5) provided equivalent subjective image ranking (with lumen sharpness taken into account) and objective IQ measurements (noise: 36.5 ± 10.7; SNR: 13.6 ± 4.9; CNR: 16.28 ± 5.4) compared with FBP images in Group A (noise: 35.5 ± 9.4; SNR: 12.4 ± 2.5; CNR: 15.4 ± 3.2) (P=0.14, 0.09, 0.17, respectively). The effective dose (ED) of Group D was 63% lower than that of Group A (1.2 ± 0.1 mSv versus 3.2 ± 0.6 mSv).Iterative reconstruction techniques can provide 63% ED reduction in prospectively-triggered coronary CTA using 256-slice MDCT while maintaining excellent image quality.

Objectives Our aim was to evaluate congenital left ventricular wall abnormalities (clefts, aneurysms and diverticula), describe and illustrate imaging features, discuss terminology problems and determine their prevalence detected by cardiac CT in a single center. Materials and methods Coronary CT angiography images of 2093 adult patients were evaluated retrospectively in order to determine congenital left ventricular wall abnormalities. Results The incidence of left ventricular clefts (LVC) was 6.7% (141 patients) and statistically significant difference was not detected between the sexes regarding LVC ( P = 0.5). LVCs were single in 65.2% and multiple in 34.8% of patients. They were located at the basal to mid inferoseptal segment of the left ventricle in 55.4%, the basal to mid anteroseptal segment in 24.1%, basal to mid inferior segment in 17% and septal–apical septal segment in 3.5% of cases. The cleft length ranged from 5 to 22 mm (mean 10.5 mm) and they had a narrow connection with the left ventricle (mean 2.5 mm). They were contractile with the left ventricle and obliterated during systole. Congenital left ventricular septal aneurysm that was located just under the aortic valve was detected in two patients (0.1%). No case of congenital left ventricular diverticulum was detected. Conclusion Cardiac CT allows us to recognize congenital left ventricular wall abnormalities which have been previously overlooked in adults. LVC is a congenital structural variant of the myocardium, is seen more frequently than previously reported and should be differentiated from aneurysm and diverticulum for possible catastrophic complications of the latter two.

Background Despite advent of rapid arterial revascularization as 1st line treatment for acute myocardial infarction (AMI), incomplete restoral of flow at the microvascular level remains a problem and is associated with adverse prognosis, including pathological ventricular remodeling. We aimed to study the association between multidetector row computed tomography (MDCT) perfusion defects and ventricular remodeling post-AMI. Methods In a prospective study, 20 patients with ST-elevation AMI, treated by primary angioplasty, underwent arterial and late phase MDCT as well as radionuclide scans to study presence, size and severity of myocardial perfusion defects. Contrast echocardiography was performed at baseline and at 4 months follow-up to evaluate changes in myocardial function and remodeling. Results Early defects (ED), late defects (LD) and late enhancement (LE) were detected in 15, 7 and 16 patients, respectively and radionuclide defects in 15 patients. The ED area ( r = 0.74), and LD area ( r = 0.72), and to a lesser extent LE area ( r = 0.62) correlated moderately well with SPECT summed rest score. By univariate analysis, follow-up end-systolic volume index and ejection fraction were both significantly related to ED and LD size and severity, but not to LE size or severity. By multivariate analysis, end-systolic volume index was best predicted by LD area ( p Conclusions LD size and severity on MDCT are most closely associated with pathological ventricular remodeling after AMI and may thus play a role in early identification and treatment of this condition.

To assess prospectively the intra- and interobserver variability, accuracy, and prognostic value of right and left ventricular short-axis diameter (RVd and LVd) measurements for risk stratification in patients with pulmonary embolism (PE) using ECG-gated compared to non-gated CT.Sixty consecutive patients (33 women; mean age 58.7±10.3 years) with suspicion of PE underwent both non-gated and ECG-gated chest CT. RVd and LVd on four-chamber views and intra- and interobserver agreements were calculated for both protocols. RVd/LVd ratios were calculated and were related to 30-days adverse clinical events using receiver operating characteristics with area-under-the-curve (AUC) analyses.Both inter- and intraobserver variability showed narrower limits of agreement for all measurements with ECG-gated as compared to non-gated CT. Diameter measurements were significantly lower using non-ECG-gated CT as compared to ECG-gated CT for RVd and LVd (both p.05). The AUC for the RVd/LVd ratio from ECG-gated CT was significantly larger than that from non-gated CT (0.956, 95% CI: 0.768-0.999 versus 0.675, 95% CI: 0.439-0.860; p=.048).RVd and LVd measurements from ECG-gated chest CT show less intra- and interobserver variability and more accurately reflect ventricular function. In our patient cohort ECG-gated chest CT allows better prediction of short-term outcome of patients with acute PE that needs to be validated in a larger outcome study.

Purpose The left atrial appendage (LAA) is usually known as a long, tubular, hooked structure derived from the left atrium. However, it varies widely in terms of anatomical shape. In this study, anatomical shape variations of the LAA were investigated and classified in vivo in a large group of patients by multidetector computed tomography (MDCT) coronary angiography. Materials and Methods The study included 320 consecutive patients (223 men and 97 women, with a mean age of 58 years) who underwent MDCT coronary angiography. MDCT was performed with a 64-detector-row computed tomographic scanner. LAA anatomical variations were classified as five main types and further divided into subtypes. In addition, we gave the classifications descriptive names according to the anatomical external appearance of the LAA: horseshoe (type 1), hand-finger (type 2a), fan (type 2b), wing (type 2c), hook (type 3), wedge (type 4) and swan (type 5) shapes. The types and subtypes of the LAA variations and the presence of thrombus were recorded. Results In our study, the LAA tip orientation was used and the LAA was divided into type 1, type 2a, 2b, 2c, type 3, type 4 and type 5 in 44 (13.8%), 65 (20.3%), 155 (48.4%), 8 (2.5%), 27 (8.4%), 6 (1.9%) and 15 (4.7%) patients, respectively. LAA thrombus was detected in four patients (1.25%), who had classified LAA shapes of type 2a and type 2b. Conclusions The LAA has multiple anatomical shape variations. We demonstrated previously undefined new shape types of LAA. Knowledge of LAA variations is important in order to avoid procedure-related complications when ablative treatment is to be performed or if surgical procedures are indicated in this region. MDCT coronary angiography provides important and detailed information about determining and evaluating these variations before undertaking a planned procedure in this region.

Background CT coronary angiography (CTCA) is an evolving modality for the diagnosis of coronary artery disease. Radiation burden associated with CTCA has been a major concern in the wider application of this technique. It is important to reduce the radiation dose without compromising the image quality. Objectives To estimate the radiation dose of CTCA in clinical practice and evaluate the effect of dose-saving algorithms on radiation dose and image quality. Methods Effective radiation dose was measured from the dose-length product in 616 consecutive patients (mean age 58 ± 12 years; 70% males) who underwent clinically indicated CTCA at our institution over 1 year. Image quality was assessed subjectively using a 4-point scale and objectively by measuring the signal- and contrast-to-noise ratios in the coronary arteries. Multivariate linear regression analysis was used to identify factors independently associated with radiation dose. Results Mean effective radiation dose of CTCA was 6.6 ± 3.3 mSv. Radiation dose was significantly reduced by dose saving algorithms such as 100 kV imaging (−47%; 95% CI, −44% to −50%), prospective gating (−35%; 95% CI, −29% to −40%) and ECG controlled tube current modulation (−23%; 95% CI, −9% to −34%). None of the dose saving algorithms were associated with a significant reduction in mean image quality or the frequency of diagnostic scans ( P = non-significant for all comparisons). Conclusion Careful application of radiation-dose saving algorithms in appropriately selected patients can reduce the radiation burden of CTCA significantly, without compromising the image quality.

Purpose To compare image quality of nonenhanced time-resolved 4D steady-state free precession MR angiography (4D SSFP MRA) of cerebral arteries at 1.5 T and 3 T. Materials and methods 12 healthy subjects (mean age 29.4 ± 6.9 years) were studied at both 1.5 T and 3 T. Two different positions of the acquisition slab were evaluated; in one acquisition the imaging slab included the carotid siphon (“Slow”), in the other acquisition the imaging slab was placed superior to the carotid siphon (“Shigh”). Subjective image quality of cerebral arteries was assessed independently by two readers on a 4-point scale. Relative Signal-to-Noise-Ratio (SNR) was determined for the M1 segment of the middle cerebral artery. Results Subjective image quality of the anterior cerebral artery (segments A1, A2) was significantly higher at 1.5 T as compared to 3 T, while 3 T provided significantly higher image quality for segment P3 of the posterior cerebral artery. For the middle cerebral artery (segments M1–M3), image quality was significantly higher at 1.5 T than at 3 T when the carotid siphon was included in the acquisition slab (“Slow”), while no significant difference was found between 1.5 T and 3 T with “Shigh”. Relative SNR was significantly higher at 1.5 T (23.1 ± 5.1) as compared to 3 T (12.1 ± 7.8) for “Slow” and significantly higher at 3 T (29.8 ± 5.9) than at 1.5 T (24.2 ± 3.6) for “Shigh”. Conclusion Our results indicate that 4D SSFP MRA should preferably be performed at 1.5 T with inclusion of the carotid siphon in the acquisition slab, which might be required for the assessment of intracranial collateral flow.

Aim of this study was to compare DNA double-strand breaks (DSBs) in blood lymphocytes of patients undergoing high-pitch helical, low-pitch helical and sequential coronary CT angiography.66 patients were examined with various scan protocols and modes (low-pitch helical scan: 100-120 kV, 320-438 mAs/rot, pitch 0.18-0.39, with or without ECG-pulsing, n=35; prospectively ECG-triggered high-pitch helical scan: 100-120 kV, 320-456 mAs/rotation, pitch 3.2-3.4, n=19; prospectively ECG-triggered sequential scan: 100-120 kV, 150-300 mAs or 320-370 mAs/rotation, n=12) either using a 64-slice or 128-slice dual-source CT or a 128-slice single source CT scanner. Blood samples were obtained before and 30 min after CT and DSBs were analyzed in isolated lymphocytes using γ-H2AX immunofluorescence microscopy. A significant increase of DSBs was measurable 30 min after CTA (range 0.01-0.71/cell). CT induced DSBs showed a significant correlation with the estimated effective dose (ρ=0.90, p0.00001). Both prospectively ECG-triggered sequential (0.10 DSBs/cell, 176 mGy cm, p0.00001) and high-pitch helical scan protocols (0.03 DSBs/cell, 109 mGy cm, p0.00001) led to a significant reduction of median DLP and DSB levels compared to low-pitch helical scans (0.34 DSBs/cell, 828 mGy cm). A reduction of the tube voltage resulted in significantly lower whereas additional calcium scoring resulted in elevated DLP and DNA damages (p0.05 each).In coronary CTA, data acquisition protocols have a significant influence on the X-ray induced DSB levels. Using γ-H2AX immunofluorescence microscopy different scan modes in different CT generations can be compared concerning their biological impact.

Background With the goal of minimizing patient radiation exposure, many centres have adopted prospective ECG-gated computed tomographic coronary angiography. Since image acquisition occurs only during ventricular diastasis, the ability to measure left ventricular (LV) ejection fraction (EF) and LV volumes has been lost. Given that LV volumes have prognostic value, the ability to estimate LV end diastolic volume (EDV) may be clinically desirable. Objective We sought to predict LV EDV using CT coronary angiography (CTA) images obtained during ventricular diastasis. Methods Consecutive patients who underwent retrospective ECG-gated CTA were enrolled. Images were reconstructed at the 75% phase and at end-diastole. LV and left atrial (LA) volumes were measured. Results A total of 153 consecutive patients were analyzed (mean age=56.7±11.2 years; men=56.2%). The mean LV EDV and EF were 144.4±40.2mL and 63.4±9.9%, respectively. There appeared to be a very strong linear relationship between the 75% phase LV volume and LV EDV with an R 2 of 0.993. Using LV and LA volumes at the 75% phase, a prediction model of LV EDV was developed (LV EDV=(1.021×75% phase LV volume)+(0.259×75% phase LA volume), adjusted R 2 =0.995). Conclusion LV EDV can be estimated using CTA data obtained during ventricular diastasis. Further studies are needed to demonstrate that such estimates of LV EDV have incremental prognostic value over coronary artery disease severity assessment with prospective ECG-gated CTA.

The purpose of this study was to determine the optimal systolic and diastolic time delays for electrocardiographic triggering of a non-contrast media enhanced MR angiography using a 3-dimensional fast spin echo sequence in patients suffering from peripheral arterial disease. 12 patients with suspected peripheral arterial disease were examined on a 1.5 T Philips Achieva MR scanner. A cardiac-triggered Volumetric Isotropic T2-weighted fast spin echo sequence was performed using variable trigger delays for systolic and diastolic phase. The signal in the popliteal arteries and anterior tibial arteries of the systolic and diastolic images was measured and optimal delay times for systolic and diastolic phase were determined. Minimum signal to noise ratio (SNR) appears at the time difference ΔT = −21 ms on systolic images of the popliteal arteries. In the anterior tibial arteries the minimum SNR is significantly higher and appears at the time difference ΔT = −14 ms. Diastolic delay times must be chosen as long or as short as possible depending on heart rate. In peripheral vessels triggered non-contrast MR angiography can yield results which are comparable with contrast enhanced MRA techniques. It is crucial to optimize timing parameters.

To evaluate a 100-kilovoltage (kV) tube voltage protocol regarding radiation dose and image quality, in comparison with the standard 120 kV setting in cardiac computed tomography angiography (CCTA).103 patients undergoing retrospective ECG-gated helical 64-slice CCTA were enrolled (100 kV group: 51 patients; 120 kV group: 52 patients). Inclusion criteria were: (1) BMI28 kg/m(2); (2) weight85 kg; (3) coronary calcium score300 Agatston Units (AU). Quantitative image quality parameters were calculated [image noise, contrast-to-noise ratio (CNR), intracoronary CT-attenuation (HU)]. Each coronary artery segment (AHA/ACC-16-segments-classification) was evaluated for image quality on a 4-point scale.There was no statistical difference in age, gender, BMI and eff. tube current (mAs), and the use of ECG-tube current modulation (50.9% vs. 50% of patients) between both groups. 84.2% of patients in the 100 kV group had zero calcium score or less than 100 AU, the remaining had between 100 and 300 AU. The effective radiation dose was significantly lower in the 100 kV group with mean 7.1 mSv+/-2.4 (range, 3.4-11.1) compared to the 120 kV group with 13.4 mSv+/-5.2 (range, 6.3-22.7) (p0.001) (dose reduction, 47%). In the 100 kV group, the use of ECG-dependent tube current modulation reduced the radiation exposure (by 44.8%) to 5.3 mSv+/-1.1 (range, 3.4-8.5 mSv) (p0.001), the dose without was 9.6 mSv+/-1.1 (range, 6.3-11.1). Image noise in the coronary arteries was not different between both groups with 29.8 and 30.5 SD [HU], respectively. CNR in the 100 kV group was with 20.9+/-6.8 for the coronary arteries and with 19.9+/-5.9 for the aorta similar to the 120 kV group. Intraluminal CT-attenuation (HU) of the coronary arteries were higher in the 100 kV group (p0.001). Image quality on 100 kV scans was excellent in 86.3%, good in 9.2%, acceptable in 3.1% of coronary segments; 1.4% were non-interpretable (in 1/4 due to increased image noise because of BMI25 kg/m(2)).The 100 kV protocol significantly reduces the radiation dose in CCTA in patients with a low BMI25 kg/m(2) and a low calcium load while maintaining high image quality and the advantages of helical scan algorithm.

Purpose The aim of our study was to compare the calcium content measured by non-enhanced multidetector-row-computed tomography (MDCT) between patients with significant stenosis of bicuspid (BAV) and tricuspid aortic valve (TAV). Another aim of our study was to assess the accuracy of the non-enhanced MDCT to distinguish BAV and TAV based on the calcified plaque morphology, and to compare the results with the transesophageal echocardiography. Subjects and methods A retrospective analysis of prospectively collected data was performed. Consecutive patients with symptomatic aortic stenosis (AS) admitted to hospital for evaluation before valve surgery underwent clinical evaluation, transthoracic and transesophageal echocardiography, and non-enhanced examination with the 64-detector-row CT using prospective ECG triggering with data acquisition in diastolic phase. The data acquisition started at 55% of the R–R interval. The patients were examined in the supine position in mild inspiration. Data were evaluated using dedicated software for calcium scoring, the volume of calcifications and calcium content were obtained. Results Thirty-seven patients (20 males, age 48–83 years) were enrolled. BAV was present in 13 patients, TAV in 24 patients. The calcium score in patients with severe AS (mean gradient >50 mmHg) was higher than in those with moderate AS (1123 ± 616 mg versus 634 ± 475, P = 0.011). Significant correlation between the calcium scores and transaortic gradients was found (r = 0.53, P = 0.002). The patients with BAV did not differ significantly from those with TAV in the AS severity (58 ± 13 versus 53 ± 20 mmHg), nor in the valve calcium score (1168 ± 717 versus 795 ± 530 mg, P = 0.093). The overall sensitivity to detect BAV in patients with calcified severe AS was 0.923 (12/13) and specificity 0.958 (23/24). The overall accuracy was 0.945 (35/37). Conclusion We observed higher calcium score in patients with severe AS than with moderate AS. However, no difference in aortic valve calcium score between BAV and TAV was found. Thus, in our sample, the aortic valve calcium score correlated with AS severity, not with aortic valve morphology. Based on the calcified plaque space relationship, the aortic BAV and TAV could be distinguished in most cases.

Objectives: Contrast media (CM) injection protocols should be customized to the individual patient. Aim of this study was to determine if software tailored CM injections result in diagnostic enhancement of the coronary arteries in computed tomography angiography (CTA) and if attenuation values were comparable between different weight categories. Materials and methods: 265 consecutive patients referred for routine coronary CTA were scanned on a 2nd generation dual-source CT. Group 1 (n = 141) received an individual CM bolus based on weight categories (39-59 kg; 60-74 kg; 75-94 kg; 95-109 kg) and scan duration ('high-pitch: 1 s; "dual-step prospective triggering": 7 s), as determined by contrast injection software (Certegra (TM) P3T, Bayer, Berlin, Germany). Group 2 (n = 124) received a standard fixed CM bolus; Iopromide 300mgI/m1; volume: 75 ml; flow rate: 7.2 ml/s. Contrast enhancement was measured in all proximal and distal coronary segments. Subjective and objective image quality was evaluated. Statistical analysis was performed using SPSS (IBM, version 20.0). Results: For group 1, mean attenuation values of all segments were diagnostic (>325 HU) without statistical significant differences between different weight categories (p > 0.17), proximal vs. distal: 449 +/- 65-373 +/- 58 HU (39-59 kg); 443 +/- 69-367 +/- 81 HU (60-74 kg); 427 +/- 59-370 +/- 61 HU (75-94 kg); 427 +/- 73-347 +/- 61 HU (95-109 kg). Mean CM volumes were: 55 +/- 6 ml (39-59 kg); 61 +/- 7 ml (60-74 kg); 71 +/- 8 ml (75-94 kg); 84 +/- 9 ml (95-109 kg). For group 2, mean attenuation values were not all diagnostic with differences between weight categories (p 0.330). Conclusions: Individually tailored CM injection protocols yield diagnostic attenuation and a more homogeneous enhancement pattern between different weight groups. CM volumes could be reduced for the majority of patients utilizing individualized CM bolus application.

To evaluate the accuracy of multidetector computed tomography (MDCT) in assessing myocardial delayed enhancement and left ventricle wall thickness in hypertrophic cardiomyopathy (HCM) compared with cardiac magnetic resonance (CMR) as the reference standard.Eighty consecutive patients (59 male; 53.2 ± 13.0 years) were examined with MDCT, followed by CMR 1 day later. Cardiac CT angiography and a delayed CT were performed. CMR was performed according to a standardized protocol. Left ventricle wall thickness and positions of myocardial delayed enhancement were identified in both CMR and CT images according to the American Heart Association left ventricle 17-segment model. Myocardial delayed enhancement was characterized as "dense" (areas with clear defined borders) or "diffuse" and then quantified using both techniques.Left ventricle wall thickness determined by MDCT was significantly correlated with CMR (R=0.88, P0.01). Compared with CMR, MDCT accurately diagnosed 74 of 78 (94.9%) patients and 1243 of 1326 (93.7%) segments. For dense myocardial delayed enhancement, MDCT significantly correlated with CMR (R=0.88, P0.01) and slightly underestimated myocardial delayed enhancement (mean, -3.85%; lower and upper limits of agreement, -13.40% and 5.70%, respectively).MDCT provides reliable quantification of myocardial delayed enhancement and evaluation of left ventricle wall thickness and has a good correlation with CMR in patients with HCM when a comprehensive cardiac CT protocol is used and can be applied for intervention planning.

To compare the effectiveness of dark blood (DB) versus bright blood (BB) sequences. To assess the intra and inter-observer variability and inter-study reproducibility between BB versus DB. To evaluate image quality level in the two sequences.In a setting of 138 patients we performed CMR using cardiac gated Gradient-multiecho single breath-hold BB and DB sequences in the middle ventricular septum. Each acquisition was repeated during the same exam. Truncation method was used to account for background noise. Image quality (IQ) was assessed using a 5 point grading scale and image analysis was conducted by 2 experienced observers.Compared with the conventional BB acquisition, the coefficient of correlation and significance of the DB technique was superior for intra-observer reproducibility (p0.001), inter-observer reproducibility (p0.001) and inter-study reproducibility (p0.001). The variability is also lower for DB sequences for T2* values14 ms. Assessment of artifacts showed a superior score for DB versus BB scans (4 versus 3, p0.001).Improvement in terms of inter observer and inter study variability using DB sequences was obtained. The greatest disparity between them was seen in inter-study reproducibility and higher IQ in DB was seen. Study demonstrates better performance of DB imaging compared to BB in presence of comparable effectiveness.

Tube current modulation in retrospective ECG gated cardiac computed tomography (CT) results in increased image noise and may reduce the accuracy of left ventricular (LV) ejection fraction (EF) and mass assessment.To examine the effects of a novel CT phase-based noise reduction (NR) algorithm on LV EF and mass quantification as compared to cardiac magnetic resonance (CMR).In 40 subjects, we compared the LV EF and mass between CT and CMR. In a subset of 24 subjects with tube current modulated CT, the effect of phase-based noise reduction strategies on contrast-to-noise ratio (CNR) and the assessment of LV EF and mass was compared to CMR.There was excellent correlation between CT and CMR for EF (r=0.94) and mass (r=0.97). As compared to CMR, the limits of agreement improved with increasing strength of NR strategy. There was a systematic underestimation of LV mass by CT compared to CMR with no NR (-10.3±10.1g) and low NR (-10.3±12.5g), but was attenuated with high NR (-0.5±8.3g). Studies without NR had lower CNR compared to low and high NR at both the ES phase and ED phase (all p0.01).A high NR strategy on tube current modulated functional cardiac CT improves correlation of EF compared to CMR and reduces variability of EF and mass evaluation by increasing the CNR. In an effort to reduce radiation dose with tube current modulation, this strategy provides better image quality when LV function and mass quantification is needed.

To reduce radiation dose for retrospective ECG-triggered helical 256-slice CTCA by determining an optimal body size index to prospectively adjust tube current.102 consecutive patients with suspected CAD underwent retrospective ECG-triggered CTCA using 256-slice CT scanner. Six body size indexes including BMI, nipple level (NL) bust, thoracic anteroposterior diameter at NL, chest circumference (CC) at NL, left main and right coronary artery (RCA) origin level were measured and their correlation with noise was evaluated using linear regression. An equation was developed to use this index to adjust tube current. Additional 102 consecutive patients were scanned with the index-based mAs adjustment. A t-test for independent samples was used to compare radiation dose levels with and without the index-based mAs selection method.Linear regression indicated that CC RCA had the best correlation with noise (R2=0.603). Effective radiation dose was reduced from 16.6±0.9 to 9.8±2.7 mSv (p0.01), i.e. 40.9% lower dose with the CC RCA-adapted tube current method. The image quality scores indicated no significant difference with and without the size-based mAs selection method.An accessible measure of body size, such as CC RCA, can be used to adapt tube current for individualized radiation dose control.

To investigate the radiation dose and image quality of prospective ECG-triggering dual-source CT angiography in infants with complex congenital heart disease (CHD) in comparison with retrospective ECG-gated scanning.Ninety-six infants less than 1 year old (60/36 male/female, age: 4.8 ± 2.7 months, weight: 5.8 ± 1.8 kg) with complex CHD were enrolled. Three image acquisition protocols were set: group 1: 80 kV, 100 mA, retrospective ECG-gated protocol; group 2: 80 kV, 100 mA, prospective ECG-triggering protocol with acquisition window of 380 ms; group 3: 80 kV, 100 mA, prospective ECG-triggering protocol with acquisition window of 200 ms. Patients were selected to any one of the protocols randomly. The signal-to-noise ratios (SNR) were calculated in the ascending aorta and the pulmonary artery trunk. Image quality was assessed by a five-point score. A score of3 represents non-diagnostic. Effective radiation dose (ED) was calculated.Image quality score of groups 1, 2 and 3 were 4.1 ± 0.4, 4.0 ± 0.6 and 4.2 ± 0.6 (p = 0.224). SNR of ascending aorta and pulmonary artery trunk among them had no statistical difference (all p0.05). The average ED (median) of groups 1, 2 and 3 were 1.17 ± 0.07 mSv (1.25 mSv), 0.72 ± 0.24 mSv (0.78 mSv) and 0.48 ± 0.41 mSv (0.39 mSv). Any two of the three groups had significant differences (all p0.001).Prospective ECG-triggering DSCT angiography associated with a significantly lower ED than retrospective protocol, while maintaining image quality for diagnosis. Prospective ECG-triggering DSCT angiography could be used as a very important second-line diagnostic tool in infants with complex CHD.

Objective The purpose of this study was to evaluate the correlation between bolus-tracking parameters and heart rate (HR) with attenuation of the ascending aorta and create a linear regression model for predicting coronary attenuation in coronary computed tomography angiography (CCTA). Methods A total of 50 patients (31 men, 19 women; mean age, 67.2 ± 10.8 y) underwent CCTA using a 320-detector CT scanner. A bolus-tracking scan was performed to optimize the scan timing. The average HR under normal breathing for 10 s was recorded just before the bolus-tracking scan started. Attenuation values of the pulmonary artery at 7 s (PA 7 ) and 10 s (PA 10 ) after the beginning of the injection were recorded during the bolus-tracking scan and the ascending aortic attenuation (CE AAo ) was measured during the diagnostic scan. Results A positive correlation was observed between PA 7 and CE AAo ( r = 0.41, P = 0.003) and PA 10 and CE AAo ( r = 0.66, P AAo ( r = −0.46, P = 0.15). A multivariable linear regression model for predicting CE AAo was evaluated, and the residual error between the predicted and the measured CE AAo was within approximately ±100 HU. Conclusions Coronary attenuation could be predicted using HR and pulmonary artery attenuation during the bolus-tracking method.

To evaluate the influence of different heart rates and arrhythmias on scanner performance, image acquisition and applied radiation exposure in prospectively ECG triggered computed tomography (pCT).An ECG simulator (EKG Phantom 320, MüllerSebastiani Elektronik GmbH, Munich, Germany) was used to generate different heart rhythms and arrhythmias: sinus rhythm (SR) at 45, 60, 75, 90 and 120/min, supraventricular arrhythmias (e.g. sinus arrhythmia, atrial fibrillation) and ventricular arrhythmias (e.g. ventricular extrasystoles), pacemaker-ECGs, ST-changes and technical artifacts. The analysis of the image acquisition process was performed on a 64-row multidetector CT (Brilliance, Philips Medical Systems, Cleveland, USA). A prospectively triggered scan protocol as used for routine was applied (120 kV; 150 mAs; 0.4s rotation and exposure time per scan; image acquisition predominantly in end-diastole at 75% R-R-interval, in arrythmias with a mean heart rate above 80/min in systole at 45% of the R-R-interval; FOV 25 cm). The mean dose length product (DLP) and its percentage increase from baseline (SR at 60/min) were determined.Radiation exposure can increase significantly when the heart rhythm deviates from sinus rhythm. ECG-changes leading to a significant DLP increase (p0.05) were bifocal pacemaker (61%), pacemaker dysfunction (22%), SVES (20%), ventricular salvo (20%), and atrial fibrillation (14%). Significantly (p0.05) prolonged scan time (8 s) could be observed in bifocal pacemaker (12.8 s), pacemaker dysfunction (10.7 s), atrial fibrillation (10.3 s) and sinus arrhythmia (9.3 s).In prospectively ECG triggered CT, heart rate and rhythm can provoke different types of scanner performance, which can significantly alter radiation exposure and scan time. These results might have an important implication for indication, informed consent and contrast agent injection protocols.

Objective To compare prospectively ECG gated CT pulmonary angiography (CTPA) with routine helical ungated CTPA for cardiac related motion artifacts and patient radiation dose. Subjects and methods Twenty patients with signs and symptoms suspicious for pulmonary embolism and who had a heart rate below 85 were scanned with prospectively ECG gated CTPA. These gated exams were matched for several clinical parameters to exams from twenty similar clinical patients scanned with routine ungated helical CTPA. Three blinded independent reviewers subjectively evaluated all exams for overall pulmonary artery enhancement and for several cardiac motion related artifacts, including vessel blurring, intravascular shading, and double line. Reviewers also measured pulmonary artery intravascular density and image noise. Patient radiation dose for each technique was compared. Fourteen clinical prospectively ECG gated CTPA exams from a second institution were evaluated for the same parameters. Results Prospectively ECG gated CTPA resulted in significantly decreased motion-related image artifact scores in lung segments adjacent to the heart compared to ungated CTPA. Measured image noise was not significantly different between the two types of CTPA exams. Effective dose was 28% less for prospectively ECG gated CTPA (4.9 mSv versus 6.8 mSv, p = 0.02). Similar results were found in the prospectively ECG gated exams from the second institution. Conclusion Compared to routine helical ungated CTPA, prospectively ECG gated CTPA may result in less cardiac related motion artifact in lung segments adjacent to the heart and significantly less patient radiation dose.

To compare ECG-gated and non-gated CT angiography of the aorta at the same radiation dose, with regard to motion artifacts (MA), diagnostic confidence (DC) and signal-to-noise-ratios (SNRs).Sixty consecutive patients prospectively randomized into two groups underwent 64-row CT angiography, with or without dose-modulated ECG-gating, of the entire aorta, due to several pathologies of the ascending aorta. MA and DC were both assessed using a four-point scale. SNRs were calculated by dividing the mean enhancement by the standard deviation. The dose-length-product (DLP) of each examination was recorded and the effective dose was estimated.Dose-modulated ECG-gating showed statistically significant advantages over non-gated CT angiography, with regard to MA (p0.001) and DC (p0.001), at the aortic valve, at the origin of the coronary arteries, and at the dissection membrane, with a significant correlation (p0.001) between MA and DC. At the aortic wall, however, ECG-gated CT angiography showed statistically significant fewer MA (p0.001), but not a statistically significant higher DC (p=0.137) compared to non-gated CT angiography. At the supra-aortic vessels and the descending aorta, the ECG-triggering showed no statistically significant differences with regard to MA (p=0.861 and 0.526, respectively) and DC (p=1.88 and 0.728, respectively). The effective dose of ECG-gated CT angiography (23.24mSv; range, 18.43-25.94mSv) did not differ significantly (p=0.051) from that of non-gated CT angiography (24.28mSv; range, 19.37-29.27mSv).ECG-gated CT angiography of the entire aorta reduces MA and results in a higher DC with the same SNR, compared to non-gated CT angiography at the same radiation dose.

Purpose To investigate feasibility and image quality and to calculate radiation dose estimates for computed tomography angiography (CTA) of the great thoracic vessels in infants and toddlers with congenital heart disease (CHD) using end-systolic prospective electrocardiography-triggered sequential dual-source data acquisition. Methods This study was institutional review board approved; informed consent was obtained. Twenty children (age 1.2 ± 1.1 years) underwent 22 prospective ECG-triggered sequential dual-source CTA examinations (Somatom Definition, Siemens) with tube current (250 mAs/rot) centered at 250 ms past the R-peak in the cardiac cycle (end-systole). Tube voltage was set to 80 kV. Image quality was evaluated by two readers independently using a four-point grading scale (4 = excellent, 1 = non-diagnostic). Radiation dose estimates were calculated from the dose-length-product (DLP). Results All CT images showed diagnostic image quality (mean score 3.67 ± 0.67, κ = 0.85). Stair-step artifacts were present in one and breathing artifacts in 4 patients, with neither impairing diagnostic image quality. Mean heart rate (bpm) was 107.6 ± 12.1 (76–130), mean heart rate variability (bpm) was 2.5 ± 2.0 (1–9). Mean scan length (mm) was 90.7 ± 22.7 (50–134). Mean estimated effective dose was 0.32 ± 0.11 mSv. Conclusion Prospective ECG-triggered sequential dual source CTA is feasible in infants and toddlers with CHD, thereby allowing almost motion-free imaging of the great thoracic vessels with the benefit of a low radiation dose.

Purpose To evaluate the effect of a small field of view (FOV) for step-and-shoot coronary computed tomography angiography (CCTA) on craniocaudal z -coverage per scan step, image quality, and radiation exposure. Methods 53 patients underwent prospectively ECG-gated CCTA on a 256-slice MDCT scanner using either a FOV > 250 mm (group 1, n = 29) or a FOV ≤ 250 mm (group 2, n = 24). Craniocaudal z -coverage was determined on coronal multiplanar reformations. Image noise, signal-to-noise ratio, contrast-to-noise ratio, and qualitative image parameters were assessed. Radiation dose was estimated from the dose length product and was standardized for a scan range from the main pulmonary artery to the diaphragm in order to make both groups comparable. Results Diagnostic image quality was achieved in 91.3% of the coronary artery segments of group 1 and 89.9% in group 2 ( p = 0.201). There were no major differences in image noise, SNR, and CNR between both groups. A smaller FOV leads to an increase of craniocaudal coverage of a single CT scan step ( r = − 0.879; p ≤ 0.001). There was an increase of 23.8% of the mean z -coverage per scanned subvolume in group 2 (59.9 mm vs. 48.8 mm). Radiation dose was significantly lower in group 2 (229 vs. 285 mGy cm, respectively). Conclusion The use of a small transverse FOV for step-and-shoot CCTA at a wide detector CT scanner leads to an increased z -coverage. 2 scan volumes are enough to image the cardiac anatomy. Radiation dose is decreased without negative impact on image quality.

To investigate the dose reduction potential of low kV triple-rule-out dual-source CT angiography (TRO-CTA) in non-obese (BMI ≤ 25 kg/m(2)) patients with acute chest pain.Sixty consecutive patients were randomly assigned to two different retrospectively ECG-gated TRO-CTA protocols in this prospective trial: Thirty patients were examined with a 120-kV standard protocol (320 reference mAs with automatic tube current modulation, automatically adapted pitch and ECG-pulsing) and served as the control group (group 1), an otherwise identical 100 kV protocol was used in the other thirty patients (group 2) for a radiation dose reduction. Subjective image quality was assessed on a 5 point scale (1: excellent, 5: non-diagnostic) by two blinded observers. Quantitative image analysis assessed vascular attenuation, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in different vascular segments. The effective dose was calculated from the dose length product (DLP) using a conversion coefficient of 0.017 mSvmGy(-1)cm(-1).There was no significant difference of age, BMI, heart rate, pitch or scan length between both patient groups. Subjective image quality was rated similar in both groups (group 1: 1.2 ± 0.4, group 2: average score=1.3 ± 0.5). Vessel attenuation was significantly higher in group 2 than in group 1 (ascending aorta: 456 ± 83 HU vs. 370 ± 78 HU, p0.001; pulmonary artery: 468 ± 118 HU vs. 411 ± 91 HU, p=0.03; left coronary artery: 437 ± 110 HU vs. 348 ± 89 HU, p0.001), however, there was no significant difference in SNR (13.2 ± 7.6 vs. 14.5 ± 7.5, p=0.49) or CNR (13.8 ± 6.6 vs. 15.9 ± 7.7, p=0.25). The effective radiation dose of the 100 kV protocol was significantly lower (9.6 ± 3.2 mSv vs. 18.1 ± 9.4 mSv, p0.0001).TRO-CTA with 100 kV is feasible in non-obese patients and results in diagnostic image quality and significantly reduced radiation dose.

To compare diagnostic performance and applicability of prospectively versus retrospectively gated 64-slice computed tomography coronary angiography (pro-CTCA vs. retro-CTCA) in a heterogeneous patient population compared to invasive coronary angiography.77 patients referred to an ECG-gated-CT of the chest were retrospectively included. Pro-CTCA was applied, whenever possible, alternatively retro-CTCA was performed. All coronary artery segments≥1.5 mm were analysed and image quality was assessed.In 39 patients retro-CTCA and in 38 patients pro-CTCA was applied, mean heart rate (HR) was 69.5±9.1 min(-1) and 62.8±5.9, respectively. For a stenosis≥50% segment-based (patient-based) analysis revealed a sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of 97%, 98%, 71%, 100% (91%, 82%, 67%, 96%) using retro-CTCA and 94%, 97%, 75%, 99% (93%, 96%, 93%, 96%) using pro-CTCA. Sensitivity and NPV increased in the pro-CTCA group in patients with a HR65. Vessel-based analysis showed lower diagnostic performance for the right coronary artery (RCA) using pro-CTCA, which increased when HR65. Image quality did not differ significantly in both groups.Prospectively triggered CTCA in a heterogeneous patient group has a very high diagnostic accuracy and image quality, when used in HR≤65. A low HR is of special importance for the evaluation of the RCA.

Purpose: To perform a systematic review of the radiation dose and diagnostic accuracy of prospective versus retrospective ECG-gated multislice CT coronary angiography. Materials and methods: A search of Pubmed/Medline and Sciencedirect databases for English literature was performed to identify studies comparing prospective and retrospective ECG-gated multislice CT angiography in the diagnosis of coronary artery disease. Effective dose, dose length product, image quality and diagnostic value were compared between two groups of studies. Results: 22 studies were included for analysis. The mean effective dose of prospective ECG-gated scans was 4.5 mSv (95% CI: 3.6, 5.3 mSv), which is significantly lower than that of retrospective scans, which is 13.8 mSv (95% CI: 11.5, 16.0 mSv) (p < 0.001). The mean dose length product was 225 mGy cm (95% CI: 188, 262 mGy cm) and 822 mGy cm (95% CI: 630, 1013 mGy cm) for the prospective and retrospective ECG-gated scans, respectively, indicating a statistically significant difference between these two protocols (p < 0.0001). The mean sensitivity and specificity of multislice CT angiography in the diagnosis of coronary artery disease was 97.7% (95% CI: 93.7%, 100%) and 92.1% (95% CI: 87.2%, 97%) for prospective ECGgated scans; 95.2% (95% CI: 91%, 99.5%) and 94.4% (95% CI: 88.5%, 100%) for retrospective ECG-gated scans, respectively, with no significant difference for sensitivity but significant difference for specificity (p = 0.047). Conclusion: Multislice CT coronary angiography with prospective ECG-gating leads to a significant reduction of radiation dose when compared to that of retrospective ECG-gating, while offering comparable image quality and diagnostic value.

Objective To evaluate the feasibility of low dose target-CTA volume scan for left atrium and pulmonary veins imaging using 320-row CT. Methods Forty-two patients (females 12, males 30; mean age 55.2 years; mean body mass index (BMI) 25.7 kg/m 2 ) with persistent or intermittent atrial fibrillation before catheter ablation were enrolled in this study. Scan protocol was target-CTA volume scan under prospective ECG-gating. The target of the exposure was only set at 40% of the R–R interval (which was at the left atrium maximal volume). The exposure time was minimal setting (350 ms). Tube voltage 100 kV (BMI ≤ 25 kg/m 2 ) or 120 kV (BMI > 25 kg/m 2 ), tube current 350–420 mA, and field of view of 180 mm × 180 mm–200 mm × 200 mm were used. The scanning range was from the level of the tracheal bifurcation to the diaphragm, and enabled to cover the left atrium and central pulmonary veins (120–140 mm). All of patients were divided into two groups according kV setting (100 kV and 120 kV). The image quality (good, moderate and poor) was evaluated by two reviewers. The CT-attenuation, image noise and contrast to noise ratio (CNR) of left atrium and every pulmonary vein branch were evaluated, respectively. The effective dose (ED) was calculated using a conversion coefficient for the chest 0.017. Results Of 42 patients, the image quality was good in 26 cases (62%) and moderate in 16 cases (38%). There was no statistical difference in the CT-attenuation and CNR of left atrium and central pulmonary veins between the two groups ( P > 0.05). The mean ED was 1.90 ± 0.19 mSv (range 1.57–2.25 mSv) in 100 kV group, and 3.83 ± 0.31 mSv (range 3.39–4.54 mSv) in 120 kV group. Conclusions The low dose target-CTA volume scan is feasible in pulmonary veins and left atrium imaging using 320-row CT. Slim patients can be scanned at 100 kV setting without loss of image quality.

OBJECTIVE: To compare radiation doses delivered at prospectively ECG-triggered sequential- (SEQ), retrospectively ECG-gated spiral- (RETRO) and prospectively ECG-triggered high-pitch spiral- (HP) computed tomography coronary angiography (CTCA) protocols, as well as catheter coronary angiography (CCA) using an anthropomorphic phantom. MATERIALS AND METHODS: An anthropomorphic Alderson phantom equipped with 50 thermoluminescent dosimeters (TLDs) was scanned using different CTCA protocols and an uncomplicated diagnostic CCA examination was simulated. Absorbed doses were experimentally determined and effective doses calculated using the dose-length product (DLP) for CTCA and the dose-area product (DAP) for CCA, as well as according to International Commission on Radiation Protection (ICRP) publications 60 and 103. RESULTS: Effective organ doses were significantly lower for HP protocols (100kV: 0.17±0.26mSv; 120kV: 0.26±0.39mSv) compared to SEQ protocols (100kV: 0.50±0.79mSv; 120kV: 0.90±1.41mSv; each p

To test our hypothesis that distension and displacement in various segments of the healthy thoracic aorta are significant and can be predicted based on clinical characteristics.Sixty-one Caucasian volunteers without cardiovascular disease (49 ± 16 years, range 19-82; 28 men, 33 women) divided into two age groups (A:50, B: ≥ 50 years) underwent 1.5-T MRI. ECG-gated dynamic data sets were acquired at five locations perpendicular to the thoracic aorta. Aortic distension and Centre of Mass (CoM) displacement were determined as percentages of diastolic aortic diameter. A multiple linear regression model including age group, gender, location, mean arterial blood pressure, heart rate and body mass index was tested.Mean aortic distension averaged over all locations was 11.2 ± 4.1% (age group A) and 6.7 ± 3.3% (age group B), mean displacement 15.1 ± 8.3% (A) and 11.0 ± 6.2% (B). Systolic and diastolic aortic diameter and CoM position significantly differed at all locations (p0.001). Distension and displacement could be predicted based on the regression model (p0.001). Age group A and women exhibited significantly greater distension and displacement compared to age group B (p0.001) and men (p0.01), respectively. Distension increased, displacement decreased from proximal to distal.Distension and translational displacement are significant at all levels of the thoracic aorta and can be predicted based on clinical characteristics.

To obtain consistent CCTA image quality and patient dose optimization with an individualized tube current selection method based on analysis of CT scout scans.The study received a waiver of informed consent from the institutional review board. Initially 100 patients (Group A) underwent CCTA with a fixed mA. The scout view pixel value and CCTA image noise were measured. Their correlation was studied to establish a formula to determine the required mA for obtaining a CT exam with a specific image noise. One hundred patients (Group B) were then scanned with the formula-determined mA. CCTA image quality, image noise and effective dose from the two groups were statistically analyzed. CT findings for 32 Group B patients were compared with the conventional coronary angiography.An average CCTA image noise of 27.6 HU was obtained (target 27 HU) using the formula with more uniform image noise in Group B (standard deviation 2.4 HU) than in Group A (4.1 HU). There was no statistical difference between image quality scores for the two groups. The effective dose for Group B (7.8 mSv) was 30% lower than for Group A (11.2 mSv) (p0.01). CCTA sensitivity, specificity, positive predictive value, negative predictive value, and stenosis detection accuracy were 94.9%, 92.1%, 88.9%, 96.5% and 93.2%, respectively, for stenosis greater than 50%.CCTA mA selection based upon the image characteristics of the CT scout view provides an individualized protocol that generates consistent image quality and helps to reduce overall patient dose.

To determine whether prospective electrocardiogram (ECG)-gated delayed contrast-enhanced dual-source computed tomography (DCE-DSCT) can accurately delineate the extension of myocardial infarction (MI) compared with delayed enhanced cardiac MR (DE-MR).Eleven patients were examined using dual-source CT and cardiac MR in 2 weeks after a first reperfused MI. DCE-DSCT scan protocol was performed with prospective ECG-gating sequential scan model 7 min after contrast administration. In a 17-model, infarcted myocardium detected by DE-MR was categorized as transmural and subendocardial extension. Segment of infarcted location and graded transmurality were compared between DCE-MDCT and DE-MR.In all eleven patients, diagnostic quality was obtained for depicting delayed enhanced myocardium. Agreement between DCE-DSCT and MR was good on myocardial segment based comparison (kappa=0.85, p0.001), and on transmural and subendocardial infarction type comparison (kappa=0.82, p0.001, kappa=0.52, p0.001, respectively). CT value was higher on infarcted region than that of normal region (100.02±9.57 HU vs. 72.63±7.32 HU, p0.001). Radiation dose of prospectively ECG-gating protocol were 0.99±0.08 mSv (0.82-1.19 mSv).Prospective ECG-gated DCE-DSCT can accurately assess the extension and the patterns of myocardial infarction with low radiation dose.

Purpose The purpose of the study was to compare 100 kV and 120 kV prospective electrocardiograph (ECG)-triggered axial coronary 64-detector CT angiography (64-MDCTA) in soft plaque diagnosis. Materials and methods Coronary artery models (n = 5) with artificial soft plaques (−32 HU to 53 HU at 120 kV) with three stenosis levels (25%, 50% and 75%) on a cardiac phantom (mimicking slim patient's environment) were scanned in heart rates of 55, 60 and 65 beats per minute (bpm). Four kinds of intracoronary enhancement (205 HU, 241 HU, 280 HU and 314 HU) were simulated. The soft plaque density and the measurement error of stenosis (in percentage), evaluated by two independent observers, were compared between 100 kV and 120 kV. The radiation dose was estimated. Results Interobserver correlation of the measurement was excellent (density; r = 0.95 and stenosis measure; r = 0.97). Neither the density of soft plaque nor the measurement error of stenosis was different between 100 kV and 120 kV (p = 0.22 and 0.08). The estimated radiation doses were 2.0 mSv and 3.3 mSv (in 14 cm coverage) on 100 kV and 120 kV prospective ECG-triggered axial scans, respectively. Conclusion The 100 kV prospective ECG-triggered coronary MDCTA has comparable performance to 120 kV coronary CTA in terms of soft plaque densitometry and measurement of stenosis, with a reduced effective dose of 2 mSv.

To explore feasibility of dual-source CT (DS-CT) prospective ECG-gated coronary angiography in patients with heart rate (HR) higher than 70beat per minute (bpm), and evaluate image quality and radiation dose with comparison to retrospective ECG-gated spiral scan.One hundred patients who underwent DS-CT coronary angiography (DS-CTCA) with mean HR higher than 70bpm but below 110bpm were enrolled in the study, 50 were scanned by adaptive sequential scan and another 50 were analyzed by retrospectively gated CT scan. The imaging quality of coronary artery segments in the two groups was evaluated using a four-point grading scale by two independent reviewers. Patient radiation dose was calculated by multiplying dose length product by conversion coefficient of 0.017.There was no significant difference between the two groups for mean HR (p=0.305), HR variability (p=0.103), body mass index (p=0.472), and scan length (p=0.208). There was good agreement for image quality scoring between the two reviewers (Kappa=0.72). Coronary evaluability of adaptive sequential scan was 99.7% (608 of 610 segments), while that of retrospective gated scan was 98.7% (614 of 622 segments), showing similar coronary evaluability (p=0.061). Effective doses of adaptive sequential scan and retrospective gated scan were 5.1±1.6 and 11.8±4.5mSv, respectively (p0.001), showing that adaptive sequential scan reduced radiation dose by 57% compared with that of retrospective gated scan.In patients with 70-110bpm HR, DS-CTCA adaptive sequential scan shows similar image quality as retrospective ECG-gated spiral scan with 57% reduction of radiation dose.

Objective To compare image quality, diagnostic accuracy and radiation dose of prospective and retrospective electrocardiogram (ECG) gated dual source computed tomography (DSCT) for the evaluation of the coronary stent, using conventional coronary angiography (CA) as a standard reference. Design, setting and patients Sixty patients (heart rates ≤70 bpm) with previous stent implantation who were scheduled for CA were divided in two groups, receiving either prospective or retrospective ECG gated DSCT separately. Two reviewers scored coronary stent image quality and evaluated stent lumen. Results There was no significant difference in image quality between the two groups. In the prospective group, there were 86.4% (51/59) stents with interpretable images, in the retrospective group, there were 87.5% (49/56) stents with interpretable images. Image quality was not influenced by age, body mass index or heart rate in either group, but heart rate variability had a weak impact on the image quality of the prospective group. Image noise was higher in the prospective group, but this difference reached statistical significance only by using a smooth kernel reconstruction. Per-stent based sensitivity, specificity, and positive and negative predictive value were 100%, 84.1%, 68.2%, and 100%, respectively, in the prospective CT angiography group and 94.4%, 86.8%, 77.3%, and 97.1%, respectively, in the retrospective CT angiography group. There was a significant difference in the effective radiation dose between the two groups, mean effective dose in the prospective and retrospective group was 2.2 ± 0.5 mSv (1.5–3.2 mSv) and 14.6 ± 3.3 mSv (10.0–20.4 mSv) ( p Conclusions Compared with retrospective CT angiography, prospective CT angiography has a similar performance in assessing coronary stent patency, but a lower effective dose in selected patients with regular heart rates ≤70 bpm.

Imaging of the left atrium is regularly performed prior to pulmonary vein isolation. The aim of the study was to evaluate the feasibility of contrast-enhanced high-resolution magnetic resonance angiography (MRA) of the left atrium using the blood-pool contrast agent gadofosveset trisodium in comparison to noncontrast MRA.Twenty consecutive patients were examined by free-breathing electrocardiogram-gated whole-heart MRA (reconstructed spatial resolution, 0.7mm x 0.6mm x 0.8mm) with a noncontrast T2-prepared steady state free precession sequence (T2-prep SSFP) and a gadofosveset trisodium-enhanced inversion-recovery SSFP sequence (CE IR-SSFP). Contrast-to-noise ratio (CNR) of blood in the left atrium was determined. Depiction of the left atrium was rated by two radiologists in consensus. A cardiologist segmented the MR data sets and rated depiction of the left atrium.Five of 20 patients had irregular breathing patterns with navigator efficiency less than 35% and were excluded from evaluation. CNR was significantly higher for CE IR-SSFP compared with T2-prep SSFP (18.4+/-5.3 vs. 11.7+/-3.5, p0.01). Depiction of the left atrium by T2-prep SSFP was rated as good in four patients, moderate in ten patients, and poor in one patient, whereas depiction of the left atrium by CE IR-SSFP was rated as excellent in nine patients, good in four patients, and moderate in two patients. CE IR-SSFP allowed for semiautomated segmentation of the left atrium in 15 patients, whereas T2-prep SSFP allowed for segmentation only in ten patients.Gadofosveset trisodium-enhanced MRA of the left atrium is feasible with significantly improved image quality compared to noncontrast MRA.

The aim of the study was to estimate radiation exposure of coronary calcium scoring and angiography using ECG-gated and ECG-triggered dual-source computed tomography.An Alderson Rando phantom equipped with thermoluminescent dosimeters was used for all dose measurements. Effective dose was calculated according to ICRP 103. Radiation exposure was performed on a dual-source computed tomography (DSCT) scanner with standard protocols for calcium scoring (DSCT-Ca) and coronary angiography (DSCTA) at different heart rates (40-100 beats/min). Furthermore, a scanning protocol with ECG-triggering as well as a standard chest CT scan were evaluated.Depending on gender, heart rate and ECG-pulsing, the effective dose of a complete cardiac DSCT (DSCT-Ca and DSCTA) scan varies from 10.2 to 32.6mSv. The effective radiation dose increased significantly with lower heart rates (p0.035). ECG-pulsing reduced the radiation exposure significantly in DSCTA (p0.001). Due to breast tissue in the primary scan range, females' doses showed an increase up to 69.9% compared to males in scan protocols without ECG-pulsing. Prospective ECG-triggered DSCTA resulted in estimated effective doses from 2.8mSv (males) to 4.1mSv (females).The ECG-pulsing technique has proven its effectiveness to reduce effective dose in coronary CT angiography and is recommended for all patients with regular heart rates. The patient's heart rate influences the radiation exposure with a significant decrease at higher heart rates. Due to its lower dose, ECG-triggered DSCTA should be implemented for special indications, i.e. for diagnosis of pathologies of the aortic root and the ascending aorta.

To evaluate whether dynamic computed tomography (CT)-imaging can provide functional vessel information in patients with chronic aortic dissection type Stanford-B (ADB).In 32 patients, ECG-gated CT-angiography images were obtained. Cross-sectional area change and wall distensibility were investigated by semiautomatic vessel area segmentation at the end of aortic arch. Significance of distensibility differences was tested with regard to the aortic diameter, and the oscillation of the intimal flap was analyzed.The aorta could be segmented successfully in all patients. These were separated into three subgroups: (A) 6 patients with an aortic diameter4 cm and without a visible intimal flap, (B) 9 patients with an aortic diameter4 cm, and (C) 17 individuals with an aortic diameteror = 4 cm; (B) and (C) having a visible intimal flap. Differences in distensibility between the subgroups were not significant. Overall mean distensibility was D(tot)=(1.3+/-0.6) x 10(-5) Pa(-1). Analysis of intimal flap oscillation showed a pulsatile short axis diameter decrease of the true lumen of up to 29%.Dynamic, ECG-gated CT-angiography can demonstrate pulsatile changes in aortic area and a highly variable motion of the intimal flap. Aortic distensibility appears independent of diameter or presence of a intimal flap. Follow-up studies may show correlation with possible complications.

Motion artifacts, which can mimic thickened bronchial wall and the cystic appearance of bronchiectasis, constitute a potential pitfall in the diagnosis of interstitial or bronchial disease. Therefore, purpose of our study was to evaluate whether 64-detector row CT (64-MDCT) enables a reduction in respiratory or cardiac motion artifacts in the lung area on thin-section CT without ECG gating, and to examine the correlation between cardiac motion artifact and heart rate.Thirty-two patients with suspected diffuse lung disease, who underwent both 8- and 64-MDCT (gantry rotation time, 0.5 and 0.4s, respectively), were included. The heart rates of an additional 155 patients were measured (range, 48-126 beats per minute; mean, 76 beats per minute) immediately prior to 64-MDCT, and compared to the degree of cardiac motion artifact. Two independent observers evaluated the following artifacts on a monitor without the knowledge of relevant clinical information: (1) artifacts on 8- and 64-MDCT images with 1.25-mm thickness and those on 64-MDCT images with 0.625-mm thickness in 32 patients; and (2) artifacts on 64-MDCT images with 0.625-mm thickness in 155 patients.Interobserver agreement was good in evaluating artifacts on 8-MDCT images with 1.25-mm thickness (weighted Kappa test, kappa=0.61-0.71), and fair or poor in the other evaluations (kappa0.31). Two observers stated that cardiac motion artifacts were more significant on 8-MDCT than on 64-MDCT in all 32 patients. Statistically significant differences were found at various checkpoints only in comparing artifacts between 8- and 64-MDCT for 1.25-mm thickness (Wilcoxon's signed-rank test, p0.0017). Cardiac motion artifacts on 64-MDCT had no significant correlation with heart rate (Spearman's correlation coefficient by rank test).The high temporal resolution of 64-MDCT appears to reduce cardiac motion artifact that can affect thin-section scans of the lung parenchyma.

Background Important to the risk stratification and management of cardiac patients is the assessment of left ventricular function (LVEF), thus imaging modalities which can provide both anatomical and functional data is desirable. Electrocardiographic (ECG) gated multi-detector computed tomographic (MDCT) images may provide accurate assessment of LV ejection fraction, volume and dimensions but have shown systemic errors in the past due to slow gantry rotation speed. Methods Between May 2004 and January 2005, 306 patients underwent ECG-gated cardiac CT studies at the Massachusetts General Hospital. Patients with available CT data sets and a recent (within 3 months) ECHO and/or SPECT perfusion imaging were included in the study. ECG-gated data sets were acquired either with a 16-slice or with a 64-slice MDCT. Functional MDCT data sets were reconstructed in 10 cardiac phases (5–95%) with 1.5 mm slices. Images were processed and interpreted by two observers blinded to ECHO and SPECT results. Results A total of 69 patients had MDCT and ECHO or SPECT within 3 months (33 had 16-slice and 36 had 64-slice MDCT). There was fair correlation between LVEF measured by 16-slice MDCT and ‘ECHO or SPECT’ (62 ± 10% vs. 62 ± 10%; r = 0.56). There was poor correlation between LVEF measured by 16-slice MDCT and ECHO (64 ± 10% vs. 59 ± 11%; r = 0.26) and there was good correlation between LVEF measured by 16-slice MDCT and SPECT (62 ± 11% and 64 ± 9%, respectively; r = 0.76). There was very good correlation between LVEF measured by 64-slice MDCT and ‘ECHO or SPECT’ (57 ± 15% vs. 58 ± 13%; r = 0.86). There was very good correlation between LVEF measured by MDCT and ECHO (56 ± 14% vs. 54 ± 15%; r = 0.89) and between LVEF measured by 64-slice MDCT and SPECT (60 ± 13% and 60 ± 14%, respectively; r = 0.90). Conclusion The assessment of LVEF and LV dimensions with 64-slice MDCT provide values which are similar to those obtained by echocardiography and Tc-99m gated SPECT. The accuracy of the 64-slice MDCT with a gantry rotation speed of 330 ms (when compared to ECHO and SPECT) may be superior to that of the 16-slice MDCT at 420 ms gantry rotation.