A Structured Literature Review and International Consensus Validation of FORTA Labels of Oral Anticoagulants for Long-Term Treatment of Atrial Fibrillation in Older Patients (OAC-FORTA 2019).

INTRODUCTION: Evidence regarding safety and efficacy of oral anticoagulants for the treatment of atrial fibrillation (AFib) in older adults has been assessed regarding the age appropriateness of oral anticoagulants (OAC) according to the FORTA (Fit fOR The Aged) classification (OAC-FORTA). Three years after its first version (OAC-FORTA 2016), an update was initiated to create OAC-FORTA 2019. METHODS: A structured review of randomized controlled clinical trials and summaries of individual product characteristics was performed to detect newly emerged evidence on oral anticoagulants in older patients with AFib. This review was used by an interdisciplinary panel of European experts (N = 10) in a Delphi process to label OACs according to FORTA. RESULTS: A total of 202 records were identified and 11 studies finally included. We found four new trials providing relevant data on efficacy and safety of warfarin, apixaban, dabigatran or rivaroxaban in older patients with AFib. In the majority of studies comparing the non-vitamin-K oral anticoagulants (NOACs) with warfarin, NOACs were superior to warfarin regarding at least one relevant clinical endpoint. The mean consensus coefficient significantly increased from 0.867 (OAC-FORTA 2016) to 0.931 (p < 0.05) and the proposed FORTA classes were confirmed in all cases during the first round (consensus coefficient > 0.8). Warfarin, dabigatran, edoxaban and rivaroxaban were assigned to the FORTA B label, acenocoumarol, fluindione and phenprocoumon were labeled FORTA C and only apixaban was rated as FORTA A. CONCLUSION: OAC-FORTA 2019 confirms that AFib can be successfully treated with positively labeled antithrombotics at advanced age.

Appropriateness of Oral Anticoagulants for the Long-Term Treatment of Atrial Fibrillation in Older People: Results of an Evidence-Based Review and International Consensus Validation Process (OAC-FORTA 2016).

BACKGROUND: Age appropriateness of anticoagulants for stroke prevention in atrial fibrillation is uncertain. OBJECTIVE: To review oral anticoagulants for the treatment of atrial fibrillation in older (age >65 years) people and to classify appropriate and inappropriate drugs based on efficacy, safety and tolerability using the Fit-fOR-The-Aged (FORTA) classification. METHODS: We performed a structured comprehensive review of controlled clinical trials and summaries of individual product characteristics to assess study and total patient numbers, quality of major outcome data and data of geriatric relevance. The resulting evidence was discussed in a round table with an interdisciplinary panel of ten European experts. Decisions on age appropriateness were made using a Delphi process. RESULTS: For the eight drugs included, 380 citations were identified. The primary outcome results were reported in 32 clinical trials with explicit and relevant data on older people. Though over 24,000 patients aged >75/80 years were studied for warfarin, data on geriatric syndromes were rare (two studies reporting on frailty/falls/mental status) and missing for all other compounds. Apixaban was rated FORTA-A (highly beneficial). Other non-vitamin K antagonist oral anticoagulants (including low/high-intensity dabigatran and high-intensity edoxaban) and warfarin were assigned to FORTA-B (beneficial). Phenprocoumon, acenocoumarol and fluindione were rated FORTA-C (questionable), mainly reflecting the absence of data. CONCLUSIONS: All non-vitamin K antagonist oral anticoagulants and warfarin were classified as beneficial or very beneficial in older persons (FORTA-A or -B), underlining the overall positive assessment of the risk/benefit ratio for these drugs. For other vitamin-K antagonists regionally used in Europe, the lack of evidence should challenge current practice.

Accuracy of prospectively ECG-triggered very low-dose coronary dual-source CT angiography using iterative reconstruction for the detection of coronary artery stenosis: comparison with invasive catheterization.

OBJECTIVE: To evaluate the image quality and diagnostic accuracy of very low-dose computed tomography (CT) angiography (CTA) for the evaluation of coronary artery stenosis. BACKGROUND: Iterative reconstruction (IR) has shown to substantially reduce image noise and hence permit the use of very low-dose data acquisition protocols in coronary CTA. METHODS: Fifty symptomatic patients with an intermediate likelihood for coronary artery disease underwent coronary CTA (heart rate: 59 ± 5 bpm, prospectively ECG-triggered axial acquisition, 100 kV, 160 mAs, 2 × 128 × 0.6 mm collimation, 60 mL contrast, 6 mL/s) prior to invasive coronary angiography. CTA images were reconstructed using both standard filtered back projection (FBP) and a raw data-based IR algorithm [Sinogram Affirmed Iterative Reconstruction (SAFIRE), Siemens Healthcare]. Subjective image quality (four-point Likert scale from 0 = non-diagnostic to 3 = excellent image quality), image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), as well as the presence of coronary stenosis >50% were independently determined by two observers. RESULTS: The mean dose-length product was 46.8 ± 3.5 mGy cm (estimated effective dose 0.66 ± 0.05 mSv). IR led to significantly improved objective image quality compared with FBP (image noise: 41 ± 12 vs. 49 ± 11 HU, P < 0.0001; CNR: 16 ± 8 vs. 12 ± 4, P < 0.0001; SNR: 13 ± 7 vs. 10 ± 3, P < 0.0001). Four coronary segments were not evaluable on FBP data, whereas all segments showed diagnostic image quality with IR. To detect significant coronary stenosis, sensitivity, specificity, positive predictive value, and negative predictive value were 69% (11/16), 97% (175/180), 69% (11/16), and 97% (175/180) per vessel with FBP data sets, respectively. With IR data sets, the corresponding values were 81% (13/16), 97% (178/184), 68% (13/19), and 98% (178/181). These differences were not statistically significant (P = 0.617). CONCLUSIONS: Raw data-based IR significantly improves image quality in very low-dose prospectively ECG-triggered coronary dual-source CTA when compared with standard reconstruction using FBP.

Multicenter Evaluation Of Coronary Dual-Source CT angiography in patients with intermediate Risk of Coronary Artery Stenoses (MEDIC): study design and rationale.

BACKGROUND: The diagnostic performance of multidetector row CT to detect coronary artery stenosis has been evaluated in numerous single-center studies, with only limited data from large cohorts with low-to-intermediate likelihood of coronary disease and in multicenter trials. The Multicenter Evaluation of Coronary Dual-Source CT Angiography in Patients with Intermediate Risk of Coronary Artery Stenoses (MEDIC) trial determines the accuracy of dual-source CT (DSCT) to identify persons with at least 1 coronary artery stenosis among patients with low-to-intermediate pretest likelihood of disease. METHODS: The MEDIC trial was designed as a prospective, multicenter, international trial to evaluate the diagnostic performance of DSCT for the detection of coronary artery stenosis compared with invasive coronary angiography. The study includes 8 sites in Germany, India, Mexico, the United States, and Denmark. The study population comprises patients referred for a diagnostic coronary angiogram because of suspected coronary artery disease with an intermediate pretest likelihood as determined by sex, age, and symptoms. All evaluations are performed by blinded core laboratory readers. RESULTS: The primary outcome of the MEDIC trial is the accuracy of DSCT to identify the presence of coronary artery stenoses with a luminal diameter narrowing of 50% or more on a per-vessel basis. Secondary outcome parameters include per-patient and per-segment diagnostic accuracy for 50% stenoses and accuracy to identify stenoses of 70% or more. Furthermore, secondary outcome parameters include the influence of heart rate, Agatston score, body weight, body mass index, image quality, and diagnostic confidence on the accuracy to detect coronary artery stenoses >50% on a per-vessel basis. CONCLUSION: The results of the MEDIC trial will assess the clinical utility of coronary CT angiography in the evaluation of patients with intermediate pretest likelihood of coronary artery disease.

Automated attenuation-based selection of tube voltage and tube current for coronary CT angiography: reduction of radiation exposure versus a BMI-based strategy with an expert investigator.

BACKGROUND: Recently developed automated algorithms use the topogram and the corresponding attenuation information before coronary CT angiography (CTA) to allow for an individualized anatomic-based selection of tube current (mAs) and voltage (kV). OBJECTIVES: The value of these algorithms in reducing the associated radiation exposure was evaluated. METHODS: One hundred patients underwent coronary CTA with dual-source CT with prospectively electrocardiogram-triggered axial data acquisition. In all patients, tube parameters (current and voltage) were suggested by both an experienced investigator according to the patient's body mass index (BMI; calculated as weight divided by height squared; kg/m(2)) and by an automated software according to attenuation values of the initial topogram. The first 50 consecutive patients (group 1) underwent coronary CTA with dual-source CT with tube parameters suggested by the experienced investigator (BMI-based tube parameters), whereas in another 50 consecutive patients (group 2) CT data acquisition was performed with tube settings of the automated software. Subsequently, subjective image quality (4-point rating score from 0 = nondiagnostic to 3 = excellent image quality), image noise (SD of CT number within the aortic root), as well as signal- and contrast-to-noise ratios and mean effective radiation doses, were compared between both groups. RESULTS: Both groups showed comparable image quality parameters (group 1 vs 2: noise, 28.1 ± 6.0 HU vs 29.9 ± 5.4 HU, P = .12; signal-to-noise ratio, 16.4 ± 3.9 vs 16.8 ± 4.1, P = .54; contrast-to-noise ratio, 18.6 ± 4.1 vs 19.2 ± 4.3, P = .49; 4-point rating score, 2.8 ± 0.3 vs 2.9 ± 0.3, P = .81). Tube voltage, current, and mean effective radiation dose for groups 1 and 2 were 111 ± 12 kV and 108 ± 12 kV (P = .18), 361 ± 32 mAs and 320 ± 48 mAs (P < .001), and 2.3 mSv (25th; 75th percentile, 1.5; 2.8 mSv) and 1.4 mSv (25th; 75th percentile, 1.1; 1.9 mSv) (P < .001), respectively. CONCLUSIONS: Automated attenuation-based selections of individualized tube parameters are superior to BMI-based selections with expert oversight and show a potential for reduction of radiation exposure in coronary CTA, and image quality is maintained.

Stent evaluation in low-dose coronary CT angiography: effect of different iterative reconstruction settings.

BACKGROUND: Different iterative reconstruction (IR) techniques compensate increased noise from lower tube current-time product settings, yet the differences between IR settings remain unclear. OBJECTIVE: Aim of this study was to test whether different IR settings have a clinically relevant influence on image quality and on the diagnostic accuracy of low-dose CT angiography in patients with a stent. METHODS: Forty-two patients with 73 coronary stents were prospectively enrolled. Data were acquired with dual-source CT, and images were reconstructed with standard filtered back projection (FBP) and raw data-based IR with different settings (I3, I4, I5). Quantitative parameters, including CT-attenuation, noise, signal-to-noise ratio, contrast-to-noise ratio, as well as the presence of in-stent stenosis > 50% were determined. All patients had invasive angiography as reference standard. RESULTS: Mean effective dose was 0.32 ± 0.02 mSv. Image noise decreased significantly compared with FBP (I3 = 29%; I4 = 38% and I5 = 45%), whereas signal-to-noise and contrast-to-noise ratios increased significantly (all IR settings P < .01). Subjective image quality was superior with all IR settings (P < .01). FBP sensitivity, specificity, positive predictive value, and negative predictive value were 83%, 71%, 36%, and 96% per stent compared with 100%, 76%, 44%, and 100%, respectively, in IR reconstructions independent of the IR setting applied. CONCLUSION: In low-dose coronary CT angiography, higher IR settings significantly improved subjective and objective image quality but had no effect on accuracy.

Low-dose dual-source CT angiography with iterative reconstruction for coronary artery stent evaluation.

OBJECTIVES: The purpose of this study was to evaluate the image quality and diagnostic accuracy of very low-dose, dual-source computed tomography (DSCT) angiography for the evaluation of coronary stents. BACKGROUND: Iterative reconstruction (IR) leads to substantial reduction of image noise and hence permits the use of very low-dose data acquisition protocols in coronary computed tomography angiography. METHODS: Fifty symptomatic patients with 87 coronary stents (diameter 3.0 ± 0.4 mm) underwent coronary DSCT angiography (heart rate, 60 ± 6 beats/min; prospectively electrocardiography-triggered axial acquisition; 80 kV, 165 mA, 2 × 128 × 0.6-mm collimation; 60 ml of contrast at 6 ml/s) before invasive coronary angiography. DSCT images were reconstructed using both standard filtered back projection and a raw data-based IR algorithm (SAFIRE, Siemens Healthcare, Forchheim, Germany). Subjective image quality (4-point scale from 0 [nondiagnostic] to 3 [excellent image quality]), image noise, contrast-to-noise ratio as well as the presence of in-stent stenosis >50% were independently determined by 2 observers. RESULTS: The median dose-length product was 23.0 (22.0; 23.0) mGy · cm (median estimated effective dose of 0.32 [0.31; 0.32] mSv). IR led to significantly improved image quality compared with filtered back projection (image quality score, 1.8 ± 0.6 vs. 1.5 ± 0.5, p < 0.05; image noise, 70 Hounsfield units [62; 80 Hounsfield units] vs. 96 Hounsfield units [82; 113 Hounsfield units], p < 0.001; contrast-to-noise ratio, 11.0 [9.6; 12.4] vs. 8.0 [6.2; 9.3], p < 0.001). To detect significant coronary stenosis in filtered back projection reconstructions, the sensitivity, specificity, positive predictive value, and negative predictive value were 97% (32 of 33), 53% (9 of 17), 80% (32 of 40), and 90% (9 of 10) per patient, respectively; 89% (43 of 48), 79% (120 of 152), 57% (42 of 74), and 96% (121 of 126) per vessel, respectively; and 85% (12 of 14), 69% (51 of 73), 32% (11 of 34), and 96% (51 of 53) per stent, respectively. In reconstructions obtained by IR, the corresponding values were 100% (33 of 33), 65% (11 of 17), 85% (33 of 39), and 100% (11 of 11) per patient, respectively; 96% (46 of 48), 84% (129 of 152), 66% (47 of 71), and 98% (127 of 129) per vessel, respectively; and 100% (14 of 14), 75% (55 of 73), 44% (14 of 32), and 100% (55 of 55) per stent, respectively. These differences were not significant. CONCLUSIONS: In selected patients, prospectively electrocardiography-triggered image acquisition with 80-kV tube voltage and low current in combination with IR permits the evaluation of patients with implanted coronary artery stents with reasonable diagnostic accuracy at very low radiation exposure.

CT predictors of post-procedural aortic regurgitation in patients referred for transcatheter aortic valve implantation: an analysis of 105 patients.

Cardiac computed tomography (CT) allows accurate and detailed analysis of the anatomy of the aortic root and valve, including quantification of calcium. We evaluated the correlation between different CT parameters and the degree of post-procedural aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI) using the balloon-expandable Edwards Sapien prosthesis. Pre-intervention contrast-enhanced dual source CT data sets of 105 consecutive patients (48 males, mean age 81 ± 6 years, mean logEuroSCORE 34 ± 13%) with symptomatic severe aortic valve stenosis referred for TAVI using the Edwards Sapien prosthesis (Edwards lifesciences, Inc., CA, USA) were analysed. The degrees of aortic valve commissural calcification and annular calcification were visually assessed on a scale from 0 to 3. Furthermore, the degree of aortic valve calcification as quantified by the Agatston score, aortic annulus eccentricity, aortic diameter at the level of the sinus of valsalva and at the sinotubular junction were assessed. Early post-procedural AR was assessed using aortography. Significant AR was defined as angiographic AR of at least moderate degree (AR ≥ 2). Visual assessment of the degree of aortic annular calcification as well as the Agatston score of aortic valve calcium correlated weakly, yet significantly with the degree of post-procedural AR (r = 0.31 and 0.24, p = 0.001 and 0.013, respectively). Compared to patients with AR < 2, patients with AR ≥ 2 showed more severe calcification of the aortic annulus (mean visual scores 1.9 ± 0.6 vs. 1.5 ± 0.6, p = 0.003) as well as higher aortic valve Agatston scores (1,517 ± 861 vs. 1,062 ± 688, p = 0.005). Visual score for commissural calcification did not differ significantly between both groups (mean scores 2.4 ± 0.5 vs. 2.5 ± 0.5, respectively, p = 0.117). No significant correlation was observed between the degree of AR and commissural calcification, aortic annulus eccentricity index or aortic diameters. The extent of aortic valve annular calcification, but not of commissural calcification, predicts significant post-procedural AR in patients referred for TAVI using the balloon-expandable Edwards Sapiens prosthesis.

Patient-specific predictors of image noise in coronary CT angiography.

BACKGROUND: Coronary computed tomography (CT) angiography can be associated with high radiation exposure. Reduction of tube voltage from 120 kV to 100 kV can reduce the dose by up to 40%, but it also increases image noise. OBJECTIVE: We aimed to find a patient-specific predictor of image noise to determine the use of reduced tube voltage. METHODS: Contrast-enhanced coronary dual-source CT angiography data sets [prospectively electrocardiogram (ECG)-triggered axial and retrospectively ECG-gated spiral acquisition, rotation of 280 milliseconds, 2 × 128 × 0.6 mm collimation, 100 kV, 320 mAs] of 165 patients (age, 54 ± 13 years) for the detection of coronary artery stenoses were analyzed. Image noise was measured in the aortic root. Influence of body weight, height, body mass index, thoracic cross sectional area, as well as the area of the thoracic solid tissue were analyzed. RESULTS: Mean image noise in the aorta was 35.1 ± 8.9 HU. Mean dose length product was 207 ± 184 cm · cGy with an average effective dose of 2.9 ± 2.6 mSv. The patient cohort was divided into tertiles according to image noise. Numerous parameters, including BMI and body weight, were significantly different between the highest and lowest tertiles. In multivariable regression analysis, the area of the thoracic solid tissue was the only independent predictor of image noise (P < 0.0001). CONCLUSIONS: The area of the thoracic solid tissue at the level of the aortic root predicts image noise and may hence be used for the decision to reduce tube voltage from 120 kV to 100 kV.

Very low-dose coronary artery calcium scanning with high-pitch spiral acquisition mode: comparison between 120-kV and 100-kV tube voltage protocols.

BACKGROUND: Effective radiation dose from a single coronary artery calcification CT scan can range from 0.8 to 10.5 mSv, depending on the protocol. Reducing the effective radiation dose to reasonable levels without affecting diagnostic image quality can result in substantial dose reduction in CT. OBJECTIVES: We prospectively compared tube voltages of 120 and 100 kV in a low-dose CT acquisition protocol for measuring coronary artery calcified plaque with prospectively electrocardiogram (ECG)-triggered high-pitch spiral acquisition. METHODS: In 150 consecutive patients, measurement of coronary artery calcified plaque was performed with prospectively ECG-triggered high-pitch spiral acquisition. Imaging was first done with tube voltage of 120 kV voltage and subsequently repeated with 100 kV and otherwise unchanged parameters. CT was performed with a dual-source CT system with 280 milliseconds of rotation time, 2 × 128 slices, pitch of 3.4, triggered at 60% of the R-R interval. Tube current for both protocols was set at 80 mAs. With the use of a medium sharp reconstruction kernel (Siemens B35f), cross-sectional images were reconstructed with 3.0-mm slice thickness and 1.5-mm increment. Agatston scores were determined per patient for both scan settings by 2 independent readers with the use of a standard threshold of 130 HU for calcium detection. In addition, the Agatston score was calculated with a previously proposed threshold of 147 HU for 100-kV acquisitions. RESULTS: Mean image noise was 20 ± 5 and 27 ± 7 for 120 and 100 kV, respectively (P < 0.0001). Mean dose length product was 24 ± 6 cm · cGy for the 120-kV protocol and 14 ± 4 cm · cGy for the 100-kV protocol, corresponding to average estimated effective doses of 0.3 and 0.2 mSv (P < 0.0001). Five patients were excluded from the analysis. In the remaining 145 patients, using the standard tube voltage of 120 kV, any coronary calcium was detected in 76 identical patients by both observers. In 75 of these patients, calcium was also identified by both observers in 100-kV data sets, whereas 1 patient was scored negative by 1 reader and was assigned an Agatston score of 0.7 (threshold, 130 HU) and 0.2 (threshold, 147 HU) by the other. Interobserver disagreement for assigning a patient a zero Agatston score was the same for both scan settings (each 4 patients). The mean Agatston scores for 120-kV and 100-kV (threshold, 147 HU) scans were 105 ± 245 (range, 0-1865) and 116 ± 261 (range, 0-1917), respectively (P < 0.0001). Bland-Altman analysis indicated a systematic overestimation of the Agatston score with tube voltage of 100 kV and threshold of 147 HU (mean difference, 11; 95% limits of agreement, 62 to -40). Similar results were observed for coronary calcium volume scores. CONCLUSION: High-pitch spiral acquisition allows coronary calcium scoring with effective doses below 0.5 mSv. The use of 100-kV tube voltage further reduces effective radiation dose compared with the standard of 120 kV; however, it leads to significant overestimation of the Agatston score when the standard threshold of 130 HU is used. Adjusting the threshold to 147 HU leads to a better agreement compared with standard 120 kV protocols yet with a remaining systematic bias toward overestimation of the Agatston score. For high-pitch spiral acquisition mode, effective radiation dose reduction when using a 100-kV setting is minimal compared with the standard 120-kV setting and may be considered nonsignificant in a clinical setting.

Image quality of ultra-low radiation exposure coronary CT angiography with an effective dose <0.1 mSv using high-pitch spiral acquisition and raw data-based iterative reconstruction.

OBJECTIVES: We evaluated the potential of prospectively ECG-triggered high-pitch spiral acquisition with low tube voltage and current in combination with iterative reconstruction to achieve coronary CT angiography with sufficient image quality at an effective dose below 0.1 mSv. METHODS: Contrast-enhanced coronary dual source CT angiography (2 × 128 × 0.6 mm, 80 kV, 50 mAs) in prospectively ECG-triggered high-pitch spiral acquisition mode was performed in 21 consecutive individuals (body weight <100 kg, heart rate ≤60/min). Images were reconstructed with raw data-based filtered back projection (FBP) and iterative reconstruction (IR). Image quality was assessed on a 4-point scale (1 = no artefacts, 4 = unevaluable). RESULTS: Mean effective dose was 0.06 ± 0.01 mSv. Image noise was significantly reduced in IR (128.9 ± 46.6 vs. 158.2 ± 44.7 HU). The mean image quality score was lower for IR (1.9 ± 1.1 vs. 2.2 ± 1.0, P < 0.0001). Of 292 coronary segments, 55 in FBP and 40 in IR (P = 0.12) were graded "unevaluable". In patients with a body weight ≤75 kg, both in FBP and in IR, the rates of fully evaluable segments were significantly higher in comparison to patients >75 kg. CONCLUSIONS: Coronary CT angiography with an estimated effective dose <0.1 mSv may provide sufficient image quality in selected patients through the combination of high-pitch spiral acquisition and raw data-based iterative reconstruction.

A method to determine suitable fluoroscopic projections for transcatheter aortic valve implantation by computed tomography.

BACKGROUND: In transcatheter aortic valve implantation (TAVI), optimal selection of fluoroscopic projections that permit orthogonal visualization of the aortic valve plane is important but may be difficult to achieve. OBJECTIVE: We developed and validated a simple method to predict suitable fluoroscopic projections on the basis of cardiac CT datasets. METHODS: In 75 consecutive patients that underwent TAVI, angulations in which a 35-mm thick maximum intensity projection would render all aortic valve calcium into 1 plane were determined by manual interaction with contrast-enhanced dual-source CT datasets. TAVI operators used the predicted angulation for the first aortic angiogram and performed additional aortic angiograms if no satisfactory view of the aortic valve plane was obtained. Predicted angulations were compared with the angulation used for valve implantation. Radiation exposure and contrast use was compared between patients with accurate prediction of fluoroscopic angulations by CT and patients in whom CT failed to predict a suitable view. RESULTS: The mean difference between the predicted angulation according to CT and the angulation used for implantation was 3 ± 6 degrees. CT predicted a suitable angulation (<5-degree deviation) in 63 of 75 cases (84%). The mean number of aortic angiograms acquired in patients with correct prediction (1.02 ± 0.1) was significantly lower than in patients with incorrect prediction of the implantation angle by CT (3.0 ± 1.7; P < 0.001). Contrast agent required for the entire TAVI procedure was lower in patients with correct prediction (72 ± 36 mL vs 106 ± 39 mL; P = 0.001). CONCLUSION: CT permits prediction of suitable angulations for TAVI in most cases.

Interobserver agreement for the detection of atherosclerotic plaque in coronary CT angiography: comparison of two low-dose image acquisition protocols with standard retrospectively ECG-gated reconstruction.

BACKGROUND: We compared the interobserver variability concerning the detection of calcified and non-calcified plaque in two different low-dose and standard retrospectively gated protocols for coronary CTA. METHODS: 150 patients with low heart rates and less than 100 kg body weight were randomised and examined by contrast-enhanced dual-source CT coronary angiography (100 kV, 320 mAs). 50 patients were examined with prospectively ECG-triggered axial acquisition, 50 patients with prospectively ECG-triggered high pitch spiral acquisition, and 50 patients using spiral acquisition with retrospective ECG gating. Two investigators independently analysed the datasets concerning the presence of calcified and non-calcified plaque on a per-segment level. RESULTS: Mean effective dose was 1.4 ± 0.2 mSv for axial, 0.8 ± 0.07 mSv for high-pitch spiral, and 5.3 ± 2.6 mSV for standard spiral acquisition (P < 0.0001). In axial acquisition, interobserver agreement concerning the presence of atherosclerotic plaque was achieved in 650/749 coronary segments (86.8%). In high-pitch spiral acquisition, agreement was achieved in 664/748 segments (88.8%, n.s.). In standard spiral acquisition, agreement was achieved in 672/738 segments (91.0%, P < 0.0001). Interobserver agreement was significantly higher for calcified than for non-calcified plaque in all data acquisition modes. CONCLUSION: Low-dose coronary CT angiography permits the detection of coronary atherosclerotic plaque with good interobserver agreement. KEY POINTS: • Low-dose CT protocols permit coronary plaque detection with good interobserver agreement. • Image noise is a major predictor of interobserver variability. • Interobserver agreement is significantly higher for calcified than for non-calcified plaque.

Influence of heart rate and phase of the cardiac cycle on the occurrence of motion artifact in dual-source CT angiography of the coronary arteries.

BACKGROUND: Coronary CT angiography allows visualization of the coronary arteries. However, motion artifact can impair delineation of the coronary artery lumen and detection of coronary artery stenoses. OBJECTIVE: We investigated the influence of heart rate and the segment of the cardiac cycle during which images are reconstructed on the occurrence of motion artifacts. METHODS: We evaluated coronary CT angiography datasets obtained by 64-slice dual-source CT in 100 consecutive patients. Data were reconstructed at 13 time instants during the cardiac cycle and evaluated for the presence of motion artifact. RESULTS: Mean heart rate was 66±14 beats/min. Overall, 98 of 100 patients had evaluable datasets. For heart rates ≤60 beats/min, optimal image quality was uniformly found during late diastole (100% of cases with evaluable image quality during a time window between 65% and 75% of the cardiac cycle). With increasing heart rates, images reconstructed during late systole more frequently provided best image quality. However, image reconstruction could not be restricted to a systolic time period. To achieve evaluable image quality in 95% of cases, data acquired between 25% and 75% of the cardiac cycle had to be available for patients with heart rates >60 beats/min. CONCLUSION: Dual-source CT provides high image quality across a wide range of heart rates. Although data acquisition may be limited to diastole for patients with heart rates ≤60 beats/min, the availability of data acquired both during systole and diastole is necessary for patients with higher heart rates.

Left ventricular thrombus attenuation characterization in cardiac computed tomography angiography.

BACKGROUND: Because of their similar visual appearance, differentiation of left ventricular thrombotic material and myocardial wall can be difficult in contrast-enhanced coronary computed tomography (CT) angiography. OBJECTIVE: We identified typical thrombi attenuation of left ventricular thrombi with the use of CT measurement. METHODS: Over a time period of 6 years, we retrospectively identified 31 patients who showed a left ventricular thrombus in CT angiography datasets. Patients underwent routine contrast cardiac CT to investigate coronary artery disease. CT attenuation of each thrombus was assessed in the 4-chamber view. CT densities were also determined in the ascending aorta, left ventricle, and myocardial wall both in the mid-septal and mid-lateral segments. The mean CT attenuation of thrombi and the difference between attenuation in thrombi, left ventricular cavity, and myocardial wall were determined. The ratio of attenuation values in thrombus versus aorta and myocardium versus aorta were also determined. RESULTS: Mean (±SD) CT attenuation of all left ventricular thrombi in 31 patients was 43.2 ± 15.3 HU (range, 25-80 HU). Mean CT densities of septal and lateral myocardial wall were 102.9 ± 23.1 HU (range, 63-155 HU) and 99.3 ± 28.7 HU (range, 72-191 HU), respectively, and were thus significantly higher than the CT attenuation of thrombi (P < 0.001). A threshold of 65 HU yielded a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively, to differentiate thrombus from the myocardial wall. The mean ratio between CT attenuation of thrombus and CT attenuation within the ascending aorta was 0.11 ± 0.05 (range, 0.04-0.23), which was significantly lower compared with the mean ratio between CT attenuation of the myocardial wall and the CT attenuation within the ascending aorta. CONCLUSION: CT attenuation within left ventricular thrombi was significantly lower than myocardial attenuation in CT angiography datasets. Assessment of CT attenuation may contribute to the differentiation of thrombi.

Accuracy of dual-source CT to identify significant coronary artery disease in patients with uncontrolled hypertension presenting with chest pain: comparison with coronary angiography.

It has been previously reported that the sensitivity and specificity of multislice CT for detecting significant CAD (coronary artery disease) is high. Chest pain is a common presentation in patients with uncontrolled hypertension. We investigated the sensitivity and specificity of dual-source CT to detect and rule out significant CAD in patients presenting with uncontrolled hypertension accompanied by chest pain. 260 consecutive patients presenting with acute chest pain in the context of stage 2 hypertension (systolic pressure ≥160 and/or diastolic pressure ≥100) were enrolled in the study. After admission, control of blood pressure and risk stratification, 82 patients were excluded due to renal insufficiency, prior coronary revascularisation or refused participation in the study. 90 further patients with low pre-test probability of CAD were also excluded. 88 remaining patients were subjected to CT coronary angiography using dual-source CT (Definition, Siemens Medical Solutions, Forchheim, Germany) within 24 h before invasive coronary angiography. A contrast-enhanced volume dataset was acquired (120 kV, 400 mAs/rot, collimation 2 × 64 × 0.6 mm, retrospective ECG gating). Data sets were evaluated concerning the presence or absence of significant coronary stenoses and validated against invasive coronary angiography. A significant stenosis was assumed if the diameter reduction was ≥50%. 88 patients (mean age 66 ± 11 years, mean heart rate 61 ± 9 bpm) were evaluated regarding the presence or absence of significant CAD (at least one stenosis ≥50% diameter reduction). Mean systolic blood pressure on presentation was 203 ± 20 mmHg and mean diastolic blood pressure was 103 ± 13 mmHg. On a per patient basis, the sensitivity and specificity for dual-source CT to detect significant CAD in vessels >1.5 mm diameter was 100% (36/36, 95% CI 90-100) and 90% (47/52, 95% CI 79-97), respectively with a negative predictive value (NPV) of 100% (47/47, 95% CI 92-100) and a positive predictive value (PPV) of 88% (36/41, 95% CI 74-96). On a per artery basis, 352 vessels were evaluated (left main, left anterior descending, left circumflex and right coronary artery in 88 patients, 12 vessels could not be assessed due to either motion artefacts or heavy calcification and were considered positive for stenoses) with a sensitivity of 84% (54/64, 95% CI 72-95) and specificity of 94% (272/288, 95% CI 88-100); NPV was 96% (272/282, 95% CI 90-100) and PPV was 77% (54/70, 95% CI 62-91). Our study demonstrates high sensitivity, specificity and negative predictive value of dual-source CT to detect significant CAD in patients presenting with uncontrolled hypertension accompanied by chest pain. Dual-source CT angiography may be useful to safely rule out coronary artery stenoses and avoid invasive angiograms in these patients.

Which concentration to choose in dual flow cardiac CT?: dual flow cardiac CT.

PURPOSE: An extensive number of protocols have been suggested to allow for functional diagnostics; however, no data is available about the minimal amount of contrast medium to achieve reliable imaging properties. None of the plethora of existing studies report a rational why the specific concentration was chosen. MATERIALS AND METHODS: A total of 40 patients were included in this prospective, controlled study. They were divided up into four equal groups getting a different concentration (10%, 20%, 30% or 40%) of a second contrast medium bolus. Corresponding septal and right ventricular ROIs were compared. A visual score was established. Coronary attenuation was measured in the right and left coronary artery. Streak artifacts in the right atrium/ventricle were assessed. RESULTS: In the 10% contrast medium (CM) group only in 5/10 (50%) patients full septal delineation was reached. In all other groups full septal visualization was obtained. No group showed a relevant difference of mean density measured in HU units of the left ventricle or the coronary arteries. All study groups except of group 1 (10% CM) showed streak artifacts in the right atrium. CONCLUSION: The dual flow protocol with a minimum concentration of 20% improves septal visualization as basis for left ventricular functional assessment, however, does not allow for reliable right ventricular or atrial visualization. There is no significant difference between the different concentration protocols in terms of coronary attenuation.

Detection of coronary artery stenoses by low-dose, prospectively ECG-triggered, high-pitch spiral coronary CT angiography.

OBJECTIVES: We sought to evaluate the diagnostic accuracy of a new prospectively electrocardiogram (ECG)-triggered high-pitch scan mode for coronary computed tomography angiography (CTA), which allows an effective dose of less than 1 mSv. BACKGROUND: Coronary CTA provides increasingly reliable image quality, but the associated radiation exposure can be high. METHODS: Seventy-five patients with suspected coronary artery disease and in sinus rhythm were screened for participation. After exclusion of 25 patients for body weight >100 kg or failure to lower heart rate to ≤ 60 beats/min, 50 patients were studied by prospectively ECG-triggered high-pitch spiral computed tomography (CT). Coronary CTA was performed using a dual-source CT system with 2 × 128 × 0.6-mm collimation, 0.28-s rotation time, a pitch of 3.4, 100-kVp tube voltage, and current of 320 mA. Data acquisition was prospectively triggered at 60% of the R-R interval and completed within 1 cardiac cycle. Diagnostic accuracy for detection of coronary artery stenoses ≥ 50% diameter stenosis was determined by comparison to invasive coronary angiography. Per-patient diagnostic performance was the primary form of analysis. RESULTS: In all 50 patients (34 males, 59 ± 12 years of age), imaging was successful. For the detection of 16 patients with at least 1 coronary artery stenosis, CT demonstrated a sensitivity of 100% (95% confidence interval [CI]: 79% to 100%) and specificity of 82% (95% CI: 65% to 93%). The positive predictive value was 72% (95% CI: 49% to 89%) and the negative predictive value was 100% (95% CI: 87% to 100%). Sensitivity was 100% (95% CI: 88% to 100%) and specificity was 94% (95% CI: 89% to 97%) on a per-vessel basis. Per-segment sensitivity was 92% (95% CI: 80% to 97%), and specificity was 98% (95% CI: 96% to 98%). Mean dose-length product for coronary CTA was 54 ± 6 mGy · cm, the effective dose was 0.76 ± 0.08 mSv (0.64 to 0.95 mSv). CONCLUSIONS: In nonobese patients with a low and stable heart rate, prospectively ECG-triggered high-pitch spiral coronary CTA provides high diagnostic accuracy for the detection of coronary artery stenoses.