Assessment of hepatic artery anatomy in pediatric liver transplant recipients: MR angiography versus CT angiography.

During LT screening, children undergo CTA to determine hepatic artery anatomy. However, CTA imparts radiation, unlike MRA. The aim was to compare MRA to CTA in assessing hepatic artery anatomy in pediatric LT recipients. Twenty-one children (median age 8.9 years) who underwent both CTA and fl3D-ce MRA before LT were retrospectively included. Interreader variability between 2 radiologists, image quality, movement artifacts, and confidence scores, were used to compare MRA to CTA. Subgroup analyses for ages <6 years and ≥6 years were performed. Interreader variability for MRA and CTA in children <6 years was comparable (k = 0.839 and k = 0.757, respectively), while in children ≥6 years CTA was superior to MRA (k 1.000 and k 0.000, respectively). Overall image quality and confidence scores of CTA were significantly higher compared to MRA at all ages (2.8/3 vs. 2.3/3, p = .001; and 2.9/3 vs. 2.5/3, p = .003, respectively). Movement artifacts were significantly lower in CTA compared to MRA in children ≥6 years (1.0/3 vs. 1.7/3, p = .010, respectively). CTA is preferred over fl3D-ce MRA for the preoperative assessment of hepatic artery anatomy in children receiving LT, both at ages <6 years and ≥6 years.

Cerebrovascular Autoregulation in Preterm Infants Using Heart Rate or Blood Pressure: A Pilot Study.

BACKGROUND: Cerebrovascular autoregulation (CAR) is often impaired in preterm infants but requires invasive mean arterial blood pressure (MABP) measurements for continuous assessment. We aimed to assess whether using heart rate (HR) results in different CAR assessment compared with using MABP. METHODS: We compared CAR (moving window correlation-coefficient with cerebral oxygenation saturation (rcSO2)), and percentage of time with impaired CAR (%timeCARi) calculated by either HR (TOHRx, tissue oxygenation heart rate reactivity index) or MABP (COx, cerebral oximetry index) during the first 72 h after birth, and its association with short-term cerebral injury. RESULTS: We included 32 infants, median gestational age of 25 + 5/7 weeks (interquartile range 24 + 6/7-27 + 5/7). COx and TOHRx correlation coefficients (cc) were significantly different in the first two days after birth (individual means ranging from 0.02 to 0.07 and -0.05 to 0.01). %TimeCARi using MABP (cc cut-off 0.3), was higher on day 1 (26.1% vs. 17.7%) and day 3 (23.4% vs. 16.9%) compared with HR (cc cutoff -0.3). During 65.7-69.6% of the time, both methods indicated impaired CAR simultaneously. The aforementioned calculations were not associated with early cerebral injury. CONCLUSIONS: In conclusion, HR and MABP do not seem interchangeable when assessing CAR in preterm infants.

Antenatal Magnesium Sulfate and Preeclampsia Differentially Affect Neonatal Cerebral Oxygenation.

INTRODUCTION: Magnesium sulfate (MgSO4) is frequently administered for maternal and fetal neuroprotection in preeclampsia (PE) and imminent preterm birth, respectively. OBJECTIVE: To assess whether MgSO4 affects neonatal cerebral oxygenation, blood flow, and cerebral autoregulation (CAR) during the first postnatal days independently from PE. METHODS: 148 neonates <32 weeks gestational age were included. Cerebral fractional tissue oxygen extraction (cFTOE) was extracted from a daily 2-h period, during which peak systolic blood flow velocity (PSV) and resistance index (RI) of the pericallosal artery were obtained. The percent time of impaired CAR (correlation coefficient between mean arterial blood pressure and cerebral oxygen saturation >0.5) was determined. Linear mixed models were applied. RESULTS: MgSO4 exposure was recorded in 77 neonates. Twenty-nine neonates were born following PE. MgSO4 independently lowered cFTOE (B: -0.026, 95% CI: -0.050 to 0.002, p < 0.05) but did not affect PSV and RI. PE was associated with a lower cFTOE (B: -0.041, 95% CI: -0.067 to -0.015, p < 0.05) and a tendency towards both lower PSV (B: -4.285, 95% CI: -9.067 to 0.497, p < 0.1) and more impaired CAR (B: 4.042, 95% CI: -0.028 to 8.112, p < 0.1), which seemed to be strongly mediated by fetal brain sparing. MgSO4 did not alter CAR. CONCLUSIONS: In contrast to fetal brain sparing in PE, MgSO4 seems to lower cFTOE by lowering cerebral oxygen demands in preterm neonates without affecting the cerebrovasculature.

Routine Postoperative Antithrombotic Therapy in Pediatric Liver Transplantation: Impact on Bleeding and Thrombotic Complications.

BACKGROUND: Hepatic artery thrombosis (HAT) and portal vein thrombosis (PVT) are serious causes of morbidity and mortality after pediatric liver transplantation. To reduce thrombotic complications, routine antithrombotic therapy consisting of 1 week heparin followed by 3 months acetylsalicylic acid, was implemented in our pediatric liver transplant program in 2003. This study aimed to evaluate incidences of bleeding and thrombotic complications since the implementation of routine antithrombotic therapy and to identify risk factors for these complications. METHODS: This retrospective cohort study includes 200 consecutive pediatric primary liver transplantations performed between 2003 and 2016. Uni- and multivariate logistic regression analysis, Kaplan-Meier method, and Cox regression analysis were used to evaluate recipient outcome. RESULTS: HAT occurred in 15 (7.5%), PVT in 4 (2.0%), and venous outflow tract thrombosis in 2 (1.0%) recipients. Intraoperative vascular interventions (odds ratio [OR] 14.45 [95% confidence interval [CI] 3.75-55.67]), low recipient age (OR 0.81 [0.69-0.95]), and donor age (OR 0.96 [0.93-0.99]) were associated with posttransplant thrombosis. Clinically relevant bleeding occurred in 37%. Risk factors were high recipient age (OR 1.08 [1.02-1.15]), high Child-Pugh scores (OR 1.14 [1.02-1.28]), and intraoperative blood loss in mL/kg (OR 1.003 [1.001-1.006]). Both posttransplant thrombotic (hazard ratio [HR] 3.38 [1.36-8.45]; p = 0.009) and bleeding complications (HR 2.50 [1.19-5.24]; p = 0.015) significantly increased mortality. CONCLUSION: In 200 consecutive pediatric liver transplant recipients receiving routine postoperative antithrombotic therapy, we report low incidences of posttransplant vascular complications. Posttransplant antithrombotic therapy seems to be a valuable strategy in pediatric liver transplantation. Identified risk factors for bleeding and thrombotic complications might facilitate a more personalized approach in antithrombotic therapy.

Accuracy of noninvasive coronary stenosis quantification of different commercially available dedicated software packages.

PURPOSE: The purpose of this study was to investigate the noninvasive quantification of coronary artery stenosis using cardiac software packages and vessel phantoms with known stenosis severity. MATERIALS AND METHODS: Four different sizes of vessel phantoms were filled with contrast agent and scanned on a 64-slice multidetector computed tomography. Diameter and area stenosis were evaluated by 2 observers blinded from the true measures using 5 different software packages. Measurements were compared with the true measure of the vessel phantoms. The absolute difference in stenosis measurements and intraobserver and interobserver variabilities were assessed. RESULTS: All software packages show a trend toward larger differences for the smaller vessel phantoms. The absolute difference of the automatic measurements was significantly higher compared with that of the manual measurements in all 5 evaluated software packages for all vessel phantoms (P < 0.05). CONCLUSION: Manual stenosis measurements are significantly more accurate compared with automatic measurements, and therefore, manual adjustments are still essential for noninvasive assessment of coronary artery stenosis.

Computed tomographic angiography or conventional coronary angiography in therapeutic decision-making.

AIMS: To evaluate non-invasive angiography using dual-source computed tomography (CT) for the determination of the most appropriate therapeutic strategy in patients with suspected coronary artery disease (CAD). METHODS AND RESULTS: CT angiography (Dual Source CT, Somatom Definition, Siemens Medical Systems, Forchheim, Germany) was performed in 60 consecutive patients [51 men, median age 64 (57-70) years] scheduled for elective coronary angiography. Both techniques were used to evaluate the presence of CAD, significant stenosis, and the need for revascularization therapy. Sensitivity and specificity for the presence of significant stenosis were: per segment (n = 766) 62% (95% CI 50-72) (64/104) and 79% (95% CI 74-84) (526/662), respectively; per patient (n = 60) 100% (95% CI 91-100) (38/38) and 45% (95% CI 24-68) (10/22), respectively. In therapeutic decision-making based on CT angiography, sensitivity, specificity, positive and negative predictive values for intervention were 97% (95% CI 84-100) (36/37), 48% (95% CI 27-69) (11/23), 75% (95% CI 60-86) (36/48), and 92% (95% CI 60-100) (11/12), respectively. If a revascularization procedure was needed, the CT angiographic data indicated the appropriate modality (percutaneous coronary intervention or coronary artery bypass grafting) in 70% (26/36) of patients. CONCLUSION: Although imaging qualities have improved considerably, CT angiography cannot be used for definitive therapeutic decision-making with regard to revascularization procedures in patients with suspected CAD.

The role of coronary artery calcification score in clinical practice.

BACKGROUND: Coronary artery calcification (CAC) measured by electron-beam computed tomography (EBCT) has been well studied in the prediction of coronary artery disease (CAD). We sought to evaluate the impact of the CAC score in the diagnostic process immediately after its introduction in a large tertiary referral centre. METHODS: 598 patients with no history of CAD who underwent EBCT for evaluation of CAD were retrospectively included into the study. Ischemia detection test results (exercise stress test, single photon emission computed tomography or ST segment analysis on 24 hours ECG detection), as well as the results of coronary angiography (CAG) were collected. RESULTS: The mean age of the patients was 55 +/- 11 years (57% male). Patients were divided according to CAC scores; group A < 10, B 10 - 99, C 100 - 399 and D >or= 400 (304, 135, 89 and 70 patients respectively). Ischemia detection tests were performed in 531 (89%) patients; negative ischemia results were found in 362 patients (183 in group A, 87 in B, 58 in C, 34 in D). Eighty-eight percent of the patients in group D underwent CAG despite negative ischemia test results, against 6% in group A, 16% in group B and 29% in group C. A positive ischemia test was found in 74 patients (25 in group A, 17 in B, 16 in C, 16 in D). In group D 88% (N = 14) of the patients with a positive ischemia test were referred for CAG, whereas 38 - 47% in group A-C. CONCLUSION: Our study showed that patients with a high CAC score are more often referred for CAG. The CAC scores can be used as an aid in daily cardiology practice to determine further decision making.

Measurement of coronary calcium scores or exercise testing as initial screening tool in asymptomatic subjects with ST-T changes on the resting ECG: an evaluation study.

BACKGROUND: Asymptomatic subjects at intermediate coronary risk may need diagnostic testing for risk stratification. Both measurement of coronary calcium scores and exercise testing are well established tests for this purpose. However, it is not clear which test should be preferred as initial diagnostic test. We evaluated the prevalence of documented coronary artery disease (CAD) according to calcium scores and exercise test results. METHODS: Asymptomatic subjects with ST-T changes on a rest ECG were selected from the population based PREVEND cohort study and underwent measurement of calcium scores by electron beam tomography and exercise testing. With calcium scores > or =10 or a positive exercise test, myocardial perfusion imaging (MPS) or coronary angiography (CAG) was recommended. The primary endpoint was documented obstructive CAD (>/=50% stenosis). RESULTS: Of 153 subjects included, 149 subjects completed the study protocol. Calcium scores > or =400, 100-399, 10-99 and <10 were found in 16, 29, 18 and 86 subjects and the primary endpoint was present in 11 (69%), 12 (41%), 0 (0%) and 1 (1%) subjects, respectively. A positive, nondiagnostic and negative exercise test was present in 33, 27 and 89 subjects and the primary endpoint was present in 13 (39%), 5 (19%) and 6 (7%) subjects, respectively. Receiver operator characteristics analysis showed that the area under the curve, as measure of diagnostic yield, of 0.91 (95% CI 0.84-0.97) for calcium scores was superior to 0.74 (95% CI 0.64-0.83) for exercise testing (p = 0.004). CONCLUSION: Measurement of coronary calcium scores is an appropriate initial non-invasive test in asymptomatic subjects at increased coronary risk.

Quantitative image analysis for the detection of motion artefacts in coronary artery computed tomography.

Multi detector-row CT (MDCT), the current preferred method for coronary artery disease assessment, is still affected by motion artefacts. To rule out motion artefacts, qualitative image analysis is usually performed. Our study aimed to develop a quantitative image analysis for motion artefacts detection as an added value to the qualitative analysis. An anthropomorphic moving heart phantom with adjustable heart-rate was scanned on 64-MDCT and dual-source-CT. A new software technique was developed which detected motion artefacts in the coronaries and also in the myocardium, where motion artefacts are more apparent; with direct association to the qualitative analysis. The new quantitative analysis managed to detect motion artefacts in phantom scans and relate them to artefact-induced vessel stenoses. Quantifying these artefacts at corresponding locations in the myocardium, artefact-induced vessel stenosis findings could be avoided. In conclusion, the quantitative analysis together with the qualitative analysis rules out artefact-induced stenosis.

Measurement of coronary calcium scores by electron beam computed tomography or exercise testing as initial diagnostic tool in low-risk patients with suspected coronary artery disease.

We determined the efficiency of a screening protocol based on coronary calcium scores (CCS) compared with exercise testing in patients with suspected coronary artery disease (CAD), a normal ECG and troponin levels. Three-hundred-and-four patients were enrolled in a screening protocol including CCS by electron beam computed tomography (Agatston score), and exercise testing. Decision-making was based on CCS. When CCS>or=400, coronary angiography (CAG) was recommended. When CCS<10, patients were discharged. Exercise tests were graded as positive, negative or nondiagnostic. The combined endpoint was defined as coronary event or obstructive CAD at CAG. During 12+/-4 months, CCS>or=400, 10-399 and <10 were found in 42, 103 and 159 patients and the combined endpoint occurred in 24 (57%), 14 (14%) and 0 patients (0%), respectively. In 22 patients (7%), myocardial perfusion scintigraphy was performed instead of exercise testing due to the inability to perform an exercise test. A positive, nondiagnostic and negative exercise test result was found in 37, 76 and 191 patients, and the combined endpoint occurred in 11 (30%), 15 (20%) and 12 patients (6%), respectively. Receiver-operator characteristics analysis showed that the area under the curve of 0.89 (95% CI: 0.85-0.93) for CCS was superior to 0.69 (95% CI: 0.61-0.78) for exercise testing (P<0.0001). In conclusion, measurement of CCS is an appropriate initial screening test in a well-defined low-risk population with suspected CAD.

Non-invasive cardiac assessment in high risk patients (The GROUND study): rationale, objectives and design of a multi-center randomized controlled clinical trial.

BACKGROUND: Peripheral arterial disease (PAD) is a common disease associated with a considerably increased risk of future cardiovascular events and most of these patients will die from coronary artery disease (CAD). Screening for silent CAD has become an option with recent non-invasive developments in CT (computed tomography)-angiography and MR (magnetic resonance) stress testing. Screening in combination with more aggressive treatment may improve prognosis. Therefore we propose to study whether a cardiac imaging algorithm, using non-invasive imaging techniques followed by treatment will reduce the risk of cardiovascular disease in PAD patients free from cardiac symptoms. DESIGN: The GROUND study is designed as a prospective, multi-center, randomized clinical trial. Patients with peripheral arterial disease, but without symptomatic cardiac disease will be asked to participate. All patients receive a proper risk factor management before randomization. Half of the recruited patients will enter the 'control group' and only undergo CT calcium scoring. The other half of the recruited patients (index group) will undergo the non invasive cardiac imaging algorithm followed by evidence-based treatment. First, patients are submitted to CT calcium scoring and CT angiography. Patients with a left main (or equivalent) coronary artery stenosis of > 50% on CT will be referred to a cardiologist without further imaging. All other patients in this group will undergo dobutamine stress magnetic resonance (DSMR) testing. Patients with a DSMR positive for ischemia will also be referred to a cardiologist. These patients are candidates for conventional coronary angiography and cardiac interventions (coronary artery bypass grafting (CABG) or percutaneous cardiac interventions (PCI)), if indicated. All participants of the trial will enter a 5 year follow up period for the occurrence of cardiovascular events. Sequential interim analysis will take place. Based on sample size calculations about 1200 patients are needed to detect a 24% reduction in primary outcome. IMPLICATIONS: The GROUND study will provide insight into the question whether non-invasive cardiac imaging reduces the risk of cardiovascular events in patients with peripheral arterial disease, but without symptoms of coronary artery disease. TRIAL REGISTRATION: Clinicaltrials.gov NCT00189111.

A comparison of echocardiographic and electron beam computed tomographic assessment of aortic valve area in patients with valvular aortic stenosis.

The purpose of this study was to compare electron beam computed tomography (EBT) with transthoracic echocardiography (TTE) in determining aortic valve area (AVA). Thirty patients (9 females, 21 males) underwent a contrast-enhanced EBT scan (e-Speed, GE, San Francisco, CA, USA) and TTE within 17 +/- 12 days. In end-inspiratory breath hold, a prospectively ecg-triggered scan was acquired with a beam speed of 50-100 ms, a collimation of 2 x 1.5 mm and an increment of 3.0 mm. The AVA was measured with planimetry. A complete TTE study was performed in all patients, and the AVA was computed using the continuity equation. There was close correlation between AVA measured with EBT and AVA assessed with TTE (r = 0.60, P < 0.01). The AVA measured with EBT was 0.51 +/- 0.46 cm(2 )larger than the AVA calculated with TTE measurements. EBT appeared to be a valuable non-invasive method to measure the AVA. EBT measures the anatomical AVA, while with TTE the functional AVA is calculated, which explains the difference in results between the methods.