Limited Acoustic Windows Research Articles

Skeleton Graph-Based Ultrasound-CT Non-Rigid Registration

Autonomous ultrasound (US) scanning has attracted increased attention, and it has been seen as a potential solution to overcome the limitations of conventional US examinations, such as inter-operator variations. However, it is still challenging to autonomously and accurately transfer a planned scan trajectory on a generic atlas to the current setup for different patients, particularly for thorax applications with limited acoustic windows. To address this challenge, we proposed a skeleton graph-based non-rigid registration to adapt patient-specific properties using subcutaneous bone surface features rather than the skin surface. To this end, the self-organization mapping is successively used twice to unify the input point cloud and extract the key points, respectively. Afterward, the minimal spanning tree is employed to generate a tree graph to connect all extracted key points. To appropriately characterize the rib cartilage outline to match the source and target point cloud, the path extracted from the tree graph is optimized by maximally maintaining continuity throughout each rib. To validate the proposed approach, we manually extract the US cartilage point cloud from one volunteer and seven CT cartilage point clouds from different patients. The results demonstrate that the proposed graph-based registration is more effective and robust in adapting to the inter-patient variations than the ICP (distance error mean <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> SD: <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$5.0\pm \rm{1.9}~mm$</tex-math></inline-formula> vs <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$8.6\pm \rm{6.7}~mm$</tex-math></inline-formula> on seven CTs).

Echocardiographic assessment alone is inadequate for determining elevated left sided filling pressures in patients with cardiogenic shock

Abstract Background Left atrial (LA) filling pressure assessment is of paramount importance in tailoring treatments for patients with cardiogenic shock (CS). ESC guidelines advocate for the use of mitral inflow Doppler and mitral annulus tissue Doppler measurements to predict elevated left atrial pressure in clinical practice. Echocardiographic measurement of LA pressures could reduce the need for invasive monitoring in CS patients, but its utility remains unproven in this population. Purpose We assessed the validity of mitral inflow velocity and mitral annulus velocity indices to determine LA pressures, correlating them with invasive measurement of pulmonary capillary wedge pressure (PCWP) in CS patients admitted to the cardiac intensive care unit (CICU). Methods We prospectively evaluated consecutive patients who underwent pulmonary artery catheter insertion in the CICU, measuring their haemodynamic parameters, including PCWP. This was immediately followed by a transthoracic echocardiography (TTE) performed by a critical care cardiologist, blinded to the invasive measurements. The early (E) and late (A) mitral inflow velocities were measured using mitral inflow Doppler and septal and lateral mitral annulus velocities (e') were measured using tissue Doppler, all in the apical 4-chamber view. TTE images were later reported by a second cardiologist, blinded to the invasive measurements and the patient. Correlations between E; E/A ratio; E/e' ratio and PCWP were evaluated using Pearson's correlation. Results Sixty patients were recruited into the study, aged 58±14 years, 27% female, with 96 assessments undertaken. The majority (55%) of patients were SCAI stage C, with 14% having had a cardiac arrest prior to CICU admission and 27% required mechanical ventilation at the time of assessment. Mean PCWP was 16.0±6.5 mmHg. Full mitral valve Doppler and tissue Doppler profiles were measured in 67 (70%) assessments, limited due to E/A fusion, atrial fibrillation and limited acoustic windows. There was only weak correlation between PCWP and E/A ratio (R=0.33, p=0.01), with no correlation between PCWP and the other measured values (Table 1), including E/e'. The AUC for identifying patients with elevated PCWP (≥15 mmHg) using E/A ratio was 0.67 (p=0.02), although there was no suitable value to use as a cut off with adequate sensitivity and specificity (Figure 1). Conclusion Echocardiographic non-invasive assessment of left sided cardiac filling pressures is technically challenging in patients with CS. Even when possible, there is weak correlation between echocardiographic and invasive measurements, suggesting limited value in this technique. Alternative non-invasive modalities, such as lung ultrasound, should be investigated in this population to assist clinical assessment. Funding Acknowledgement Type of funding sources: None.

442 Myocardial Work Estimation With Ct Aids Evaluation Of Regional Right Ventricular Function

Introduction: Myocardial work (MW) - the area of the myocardial stress-strain loop - can serve as a better metric of myocardial performance than volumetric or strain measures, as MW is independent of loading conditions and has been shown to reflect regional oxygen perfusion and glucose metabolism. In practice, MW has been estimated as the ventricular pressure-myocardial strain area (PSA) using echocardiography. However, the RV’s complex geometry and echo’s limited acoustic windows can limit this approach.

Multi-View 3-D Fusion Echocardiography: Enhancing Clinical Feasibility with a Novel Processing Technique

A novel system for fusing 3-D echocardiography data sets from complementary acoustic windows was evaluated in 12 healthy volunteers and 12 patients with heart failure. We hypothesized that 3-D fusion would enable 3-D echocardiography in patients with limited acoustic windows. At least nine 3-D data sets were recorded, while three infrared cameras tracked the position and orientation of the transducer and chest respiratory movements. Corresponding 2-D planes of the fused 3-D data sets and of single-view 3-D data sets were assessed for image quality and compared with measurements of left ventricular function obtained with contrast 2-D echocardiography. The signal-to-noise ratio in accurately fused 3-D echocardiography recordings improved by 55% in systole (p < 0.001) and 47% in diastole (p < 0.00001) compared with the apical single-view recordings. The 3-D data sets acquired during short breath holds were successfully fused in 11 of 12 patients. The improvement in endocardial border definition (from 11.7 ± 6.0 to 24.0 ± 3.3, p < 0.01) enabled quantitative assessment of left ventricular function in 10 patients, with no significant difference in ejection fraction compared with contrast 2-D echocardiography. In patients with heart failure and limited acoustic windows, the novel fusion protocol provides 3-D data sets suitable for quantitative analysis of left ventricular function.

Design, fabrication, and characterization of broad beam transducers for fragmenting large renal calculi with burst wave lithotripsy.

Burst wave lithotripsy (BWL) is a technology for comminuting urinary stones. A BWL transducer's requirements of high-pressure output, limited acoustic window, specific focal depth, and frequency to produce fragments of passable size constrain focal beamwidth. However, BWL is most effective with a beam wider than the stone. To produce a broad-beam, an iterative angular spectrum approach was used to calculate a phase screen that was realized with a rapid prototyped lens. The technique did not accurately replicate a target beam profile when an axisymmetric profile was chosen. Adding asymmetric weighting functions to the target profile achieved appropriate beamwidth. Lenses were designed to create a spherically focused narrow-beam (6 mm) and a broad-beam (11 mm) with a 350-kHz transducer and 84-mm focal depth. Both lenses were used to fragment artificial stones (11 mm long) in a water bath, and fragmentation rates were compared. The linearly simulated and measured broad beamwidths that were 12 mm and 11 mm, respectively, with a 2-mm-wide null at center. The broad-beam and the narrow-beam lenses fragmented 44 ± 9% and 16 ± 4% (p = 0.007, N = 3) of a stone by weight, respectively, in the same duration at the same peak negative pressure. The method broadened the focus and improved the BWL rate of fragmentation of large stones.

Toward Robot-Assisted Photoacoustic Imaging: Implementation Using the da Vinci Research Kit and Virtual Fixtures

Photoacoustic imaging of the prostate is challenging due to the limited access and limited acoustic windows to the prostate gland. We aim to develop intraoperative prostate photoacoustic imaging using the da Vinci robotic system and a pick-up ultrasound transducer that can be easily picked up and manipulated by the robot. We propose a new approach in which the da Vinci robot is programmed to acquire trajectories in a shared control configuration with “virtual fixtures”; the pick-up transducer is controlled so that it stays parallel to a single axis defined as the tomography axis, and its translation is fixed to a single plane normal to this axis. The surgeon controls the transducer motion on the tissue along this virtual fixture while the laser is fired and photoacoustic data are collected periodically. The RMS errors of the photoacoustic tomography images are 0.06 a.u. This study confirms that intraoperative da Vinci robot-assisted photoacoustic imaging with a pick-up transducer is feasible.

75-Year-Old Man With Chest Pain and Dyspnea

75-Year-Old Man With Chest Pain and Dyspnea

Congenital Extra-Cardiac Vascular Anomalies as Detected on Multislice Computed Tomography Angiography

Background: Accurate evaluation of extra cardiac and intra cardiac anomalies in congenital heart diseases (CHD) is vital for diagnosis and treatment. Trans-thoracic echocardiography (TTE) is the classical choice for children suspected to have CHD because TTE is safe, readily available and its capacity to perform Doppler flow studies therefore can measure hemodynamic parameters. Plus its ability to evaluate intra cardiac abnormalities like atrial septal defect and ventricular septal defect. Therefore, owing to its lower spatial resolution and limited acoustic window; it is not precise in evaluation of extra cardiac abnormalities. Aim of the Work: to evaluate the advantage of recent advances of ECG gated MDCT in diagnosis of congenital heart disease in pediatrics and assessment of associated extra cardiac abnormalities within the great vessels in comparison with echocardiography findings. Patients and Methods: The current study was carried out on 36 patients in Radio-diagnosis Department, Faculty of medicine, Ain Shams University and specialized private radiology centers. The patients were referred from pediatric hospital, cardiology clinic with their echocardiographic reports to radio-diagnosis department, cardiac imaging unit with a view to execute ECG- gated multi-slice CT of the heart & extra-cardiac great vessels. Results: In this study aortic anomalies represent the most common extra-cardiac anomalies accounting for 36.5% of our cases while comprising: Supravalvular aortic stenosis; 4.3%, Aortic CoA; 26.1%, arch anomalies with vascular rings; 52.2% and finally anomalous coronary arteries; 17.4%. By Using MDCT we were able to delineate eight cases of right aortic arch (RAA).Two of them with aberrant left subclavian artery (ALSCA) adding to two cases of left aortic arch with an aberrant right subclavian artery (ARSCA). On the other hand ,TTE failed to identify 6 cases of RAA with a sensitivity 75%, specificity 100%, NPV 96.61% and one case of ALSCA with a sensitivity 50.0%, specificity 100%, NPV 98.41% .Regarding coronary anomalies , Cardiac CTA succeeded in characterization of origin and course of all coronary abnormalities encountered in our study encompassing 4 cases specifically anomalous LAD from right coronary sinus running a prepulmonic course anterior to RVOT , RCA from LAD and single coronary artery adding to LCX- RV coronary fistula. While TTE failed to depict two cases of the coronary anomalies with a sensitivity of 50%, specificity 100%, PPV 100% and NPV 96.83%. Conclusion: CTA can provide the confident detection and exclusion of extra- cardiac vascular abnormalities with superb anatomical description which was feasible with a sensitivity 98.41%, specificity 99.76%, PPV 96.88% and NPV 99.88%.

Utility of Cardiac Magnetic Resonance Imaging in the Management of Adult Congenital Heart Disease.

The increasing number of patients with adult congenital heart disease (ACHD) calls for the development of noninvasive imaging techniques that allow a long-term evaluation of native and postsurgical anatomy and function. Echocardiography remains the imaging modality of choice for congenital heart disease, but it is affected by limited acoustic windows and poor tissue characterization. Cardiac computed tomography and cardiac catheter angiography are 2 valid alternatives for the anatomic and functional assessment of ACHD; however, both use ionizing radiation, and cardiac catheter angiography requires an invasive approach. Cardiac magnetic resonance (CMR), noninvasively and in the absence of ionizing radiation, has the ability to evaluate the biventricular function, quantify flows, characterize tissue, and provide information on cardiac anatomy. Despite the long acquisition time and lower spatial resolution compared with cardiac computed tomography, CMR represents the ideal technique for long-term follow-up of ACHD. CMR is now widely utilized and is well described in the literature with regard to diagnosis, identification of complications, timing of surgery, and postoperative prognosis in ACHD. CMR represents a fundamental technique for the evaluation of patients with ACHD.

In Vivo Intracardiac Vector Flow Imaging Using Phased Array Transducers for Pediatric Cardiology.

Two-dimensional blood speckle tracking (ST) has shown promise for measuring complex flow patterns in neonatal hearts using linear arrays and high-frame-rate plane wave imaging. For general pediatric applications, however, the need for phased array probes emerges due to the limited intercostal acoustic window available. In this paper, a clinically approved real-time duplex imaging setup with phased array probes was used to investigate the potential of blood ST for the 2-D vector flow imaging of children with congenital heart disease. To investigate transmit beam pattern and tracking accuracy, straight tubes with parabolic flow were simulated at three depths (4.5, 7, and 9.5 cm). Due to the small aperture available, diffraction effects could be observed when approaching 10 cm, which limited the number of parallel receive beams that could be utilized. Moving to (slightly) diverging beams was shown to solve this issue at the expense of a loss in signal-to-noise ratio. To achieve consistent estimates, a forward-backward tracking scheme was introduced to avoid measurement bias occurring due to tracking kernel averaging artifacts at flow domain boundaries. Promising results were observed for depths <10 cm in two pediatric patients, where complex cardiac flow patterns could be estimated and visualized. As a loss in penetration compared with color flow imaging is expected, a larger clinical study is needed to establish the clinical feasibility of this approach.

Feasibility and accuracy of gated blood pool SPECT equilibrium radionuclide ventriculography for the assessment of left and right ventricular volumes and function in patients with left ventricular assist devices

BackgroundLeft ventricular assist devices (LVADs) require serial assessment of right and left ventricular (RV & LV) volumes and function. Because the RV is not assisted, its function is a critical determinant of the hemodynamic and contributes significantly to postoperative morbidity and mortality. We evaluated the feasibility and the accuracy of tomographic-equilibrium radionuclide ventriculography (t-ERV) for the assessment of patients with LVADs. MethodsTwenty-four patients with LVAD underwent t-ERV. Because of the limited acoustic window, transthoracic echocardiography (TTE) was only feasible in 19 patients. Functional evaluation including six-minute walk test (6MWT) and peak oxygen consumption (POC) was performed in 18 patients. Nine patients underwent a cardiac multidetector computed tomography (MDCT). Eight patients underwent a second evaluation by ERV 4.3 ± 1.4 months later. ResultsReliability between t-ERV and MDCT for LV end-diastolic volume, LV end-systolic volume, LV ejection fraction, RV end-diastolic volume, RV end-systolic volume, and RV ejection fraction (RVEF) was 0.900 (P = .001), 0.911 (P = .001), 0.765 (P = .021), 0.728 (P = .042), 0.875 (P = .004), and 0.781 (P = .023), respectively. There was no correlation between t-ERV and RV systolic parameters assessed by TTE. RVEF was correlated with POC (R = 0.521; P = .027). A cut-off value of 40% for RVEF measured by t-ERV could discriminate patients with poor functional status (P = .048 for NYHA stage; P = .016 for 6MWT and P = .007 for POC). Conclusiont-ERV is a simple, reproducible, and an accurate technique for the assessment of RV function in patients with LVADs and warrants consideration in the evaluation and monitoring of symptomatic patients.

SPECT equilibrium radionuclide ventriculography for the assessment of ventricular volumes and function in patients with left ventricular assist devices

Objectives Left ventricular assist devices (LVADs) require serial assessment of right and left ventricular (RV & LV) volumes and function. Transthoracic echocardiography (TTE) is limited by acoustic window and cardiac multidetector computed tomography (MDCT) is considered as the best tool to monitor patients with LVADs. We evaluated the feasibility and the accuracy of tomographic equilibrium radionuclide ventriculography (t-ERV) for the assessment of LV and RV volumes and function in patients with LVADs. Materials and methods Twenty-four patients with LVAD (23 HeartMate II and 1 HeartWare) underwent ERV. Because of limited acoustic window, TTE was only feasible in 19 patients. Functional evaluation including six-minutes walk test (6MWT) and peak oxygen consumption (POC) was performed in 18 patients. Nine patients underwent a cardiac MDCT. Eight patients underwent a second evaluation by ERV 4.3 ± 1.4 months later for inter-scan reliability assessment. Results Reliability between t-ERV and MDCT for LV end-diastolic volume, LV end-systolic volume, LV ejection fraction, RV end-diastolic volume, RV end-systolic volume and RV ejection fraction (RVEF) was 0.900 (P = 0.001), 0.911 (P = 0.001), 0.765 (P = 0.021), 0.728 (P = 0.042), 0.875 (P = 0.004) and 0.781 (P = 0.023), respectively. There was no correlation between t-ERV and RV systolic parameters assessed by TTE. RVEF was correlated with POC (R = 0.521; P = 0.027). A cut-off value of 40% for RVEF measured by ERV could discriminate patients with poor functional status (P = 0.048 for NYHA stage; P = 0.016 for 6MWT and P = 0.007 for POC). Intra-, inter-rater and inter-scan reliabilities were over 0.9 for the assessment of LV and RV volumes and function by t-ERV. Conclusions t-ERV is a simple, reproducible and accurate technique for the assessment of RV function in patients with LVADs. Because of its good correlation with functional parameters and good inter-scan reliability, t-ERV warrants consideration in the evaluation and monitoring of symptomatic patients with LVADs.

Myocardial tissue phase mapping reveals impaired myocardial tissue velocities in obesity.

Although obesity is linked to heart failure on a population level, not all obese subjects develop cardiac failure. As a result, identifying obese subjects with subclinical changes in myocardial velocities may enable earlier detection of those susceptible to developing overt heart failure. As echocardiography is limited in obesity due to limited acoustic window, we used phase contrast magnetic resonance imaging to assess myocardial velocities in obese and normal weight subjects. Normal weight (BMI 23 ± 3; n = 40) and obese subjects (BMI 37 ± 7; n = 59) without identifiable cardiovascular risk factors underwent MRI (1.5 Tesla) to determine left ventricular myocardial velocities using phase contrast tissue phase mapping. Systolic function was not different between normal and obese subjects (LVEF 67 ± 5 vs 68 ± 4, p = 0.22). However, obesity was associated with significantly impaired peak radial and longitudinal diastolic myocardial velocity (by 13 and 19 % respectively, both p < 0.001). In addition time-to-peak longitudinal diastolic velocity was delayed in obesity (by 39 ms, p < 0.001). In addition, peak longitudinal diastolic strain was 20 % lower in obesity (p = 0.015) and time-to-peak longitudinal diastolic strain rate significantly delayed in obesity (by 92 ms, p < 0.001).Although peak radial systolic velocity was similar between obese and normal weight subjects (p = 0.14) peak longitudinal systolic velocity was 7 % lower in the obese cohort (p = 0.02). In obesity without co-morbidities, tissue phase mapping has shown subclinical changes in systolic and diastolic function. Given the link between obesity and heart failure, early detection of changes may become clinically important to prevent disease progression.

Value of Speckle-tracking Echocardiography and MRI-based Feature Tracking Analysis in Adult Patients after Fontan-type Palliation

Patients are commonly affected by ventricular dysfunction and heart failure after Fontan palliation. Reliable quantification of ventricular function is of interest but hampered by complex ventricular anatomy and physiology. We aimed to assess myocardial function using a novel cardiac magnetic resonance imaging (CMR)-based feature-tracking (FT) technique and to study its clinical utility in Fontan patients. Retrospective study in consecutive patients attending our service. We included 15 adult Fontan patients (age 27 ± 7 years) who underwent a standardized transthoracic echocardiographic investigation (TTE) with measurement of global strain using speckle tracking. Thirteen patients also underwent CMR, with assessment of myocardial deformation by FT, providing longitudinal and circumferential global strain for the single ventricle. The value of TTE-based strain measurements was limited by the fact that in 63% of patients at least one myocardial segment could not be adequately quantified due to limited acoustic windows. In contrast, CMR allowed for a complete visualization of all wall segments. Not surprisingly, there was poor agreement between the techniques but good or moderate interobserver variability for FT (coefficients of variability 6.6% and 14.3% for circumferential and longitudinal strain). Unlike ejection fraction, FT parameters correlated significantly with age at Fontan completion, New York Heart Association (NYHA) class, and peak oxygen uptake on cardiopulmonary exercise testing. Assessment of myocardial function using CMR cine-based feature tracking is feasible in Fontan patients. Unlike echocardiographic techniques, FT is independent of inadequate acoustic windows and FT measurements relate to clinical parameters, suggesting that this approach could have clinical relevance in future.

Apport de l’imagerie cardiaque dans le diagnostic des péricardites chroniques constrictives

Constrictive pericarditis is a rare heart disease. The diagnosis remains a challenge. In fact, this illness can mimic restrictive cardiomyopathy. Echo-Doppler evaluation helps to establish the diagnosis of constriction; however, this technique is limited in its ability to image the entire pericardium because of its limited acoustic windows by air or bone of thorax. In addition, it is an operator-dependent exploration. Scanner and magnetic resonance imaging provide a large field of view and excellent images, showing the increased pericardial thickness and septal motion abnormalities. This review will consider the emerging role of these imaging modalities in the constrictive pericarditis diagnosis.

Echocardiography: frontier imaging in cardiology

This article reviews the recent developments in echocardiography that have maintained this technology at the forefront of day-to-day imaging in clinical cardiology. The primary reason for most requests for imaging in cardiovascular medicine is to assess left ventricular structure and function. As our understanding of left ventricular mechanics has become more intricate, tissue Doppler and speckle tracking modalities have been developed that deliver greater insights into diagnosis of cardiomyopathy and earlier warning of ventricular dysfunction. Increased accuracy has been achieved with the dissemination of real-time three-dimensional echocardiography, which has also acquired a central role in the pre-operative assessment of patients prior to reparative valvular surgery. The use of contrast has broadened the indications for transthoracic echocardiography and has increased the accuracy of stress echocardiography, while reducing the number of patients who cannot be scanned because of a limited acoustic window. Finally, echocardiography will be seen in the future not only as a diagnostic tool in those affected by cardiovascular disease but also as a method for prediction of risk and perhaps activation of targeted treatment.

A rare case of massive papillary fibroelastoma of the right ventricular free wall

A 51-year-old previously healthy woman was referred to our institution with atypical chest pain. Physical examination and laboratory findings were normal. The electrocardiogram demonstrated sinus rhythm of 70 beats/min with a right bundle branch block. Routine chest X-ray showed calcifications projecting on the heart. Transthoracic echocardiography was hampered by a limited acoustic window. Cardiovascular magnetic resonance revealed a well-demarcated mass in the right ventricle in conjunction with the right ventricular free wall (Fig. 1). Dimensions were 9.5 × 4.5 × 4.5 cm. Computed tomography of the thorax demonstrated a densely calcified mass located in the right ventricle but showed no evidence of pulmonary embolism or intrapulmonary masses (Fig. 2a and b). Finally, transvenous biopsy of the tumour led to the histological diagnosis of papillary fibroelastoma (Fig. 2d). To our knowledge, this is the first well-documented case of a large calcified papillary fibroelastoma of the right ventricular free wall [1, 2]. Fig. 1 Cardiovascular magnetic resonance (CMR) demonstrates a large mass in the right ventricle in conjunction with the right ventricular free wall. On cine-imaging, the mass exhibited a somewhat lower signal than the left ventricular myocardium (a and b). T1 ... Fig 2 Axial (a) and (b) coronal CT image show a large and heavily calcified mass at the right ventricular free wall. Coronary angiography (c) shows a large non vascularised calcified mass. Histological examination (d) in haematoxylin and eosin stain reveals ...

Hepatic Perfusion Disorder Associated with Focal Liver Lesions: Contrast-enhanced US Patterns—Correlation Study with Contrast-enhanced CT

To retrospectively compare the detection and characterization of hepatic perfusion disorder (HPD) associated with focal liver lesions (FLLs) at contrast material-enhanced ultrasonography (US) by using contrast-enhanced computed tomography (CT) as the reference standard. The study was approved by the local institutional ethics committee, and informed consent was waived. Three hundred fifty patients (mean age, 50 years ± 11 [standard deviation]; age range, 19-82 years; 168 women, 182 men) underwent contrast-enhanced US and contrast-enhanced CT between April 2008 and July 2010. Two independent readers reviewed contrast-enhanced US images for the detection and characterization of HPD. The largest lesion or the lesion best identified at contrast-enhanced US per patient was used for statistical analysis. Contrast-enhanced CT was used as the reference standard. Contrast-enhanced US and CT interreader agreement of diagnoses was assessed by using the weighted κ coefficient, and influences of lesion size, enhancement covering rate, and liver cirrhosis were evaluated by using logistic regression analysis and the paired χ(2) test. Sensitivity, specificity, positive and negative predictive values, and accuracy of contrast-enhanced US for HPD detection were calculated. Contrast-enhanced US results showed HPD features similar to those of CT imaging. CT depicted 50 HPDs in 350 patients, and contrast-enhanced US depicted 55 HPDs in 350 patients. The agreement for HPD diagnosis between US and CT was good (κ = 0.749). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of contrast-enhanced US were 84.0%, 95.7%, 76.4%, 97.3%, and 0.945, respectively. Rapid enhancement coverage (P < .001) and lesion size (P = .002) were significant predictors of the occurrence of HPD. Liver cirrhosis did not have significant influence for HPD detection (P = .087). Image zooming, limited acoustic window, lesion diameter greater than 5 cm, attenuation, and blurred images were the main reasons for the false-positive diagnosis of HPD at contrast-enhanced US. The HPD in FLLs can reliably be detected with contrast-enhanced US, which correlated well with contrast-enhanced CT images.

Impact of acoustic window on accuracy of longitudinal global strain: a comparison study to cardiac magnetic resonance

To evaluate the impact of acoustic window on the feasibility and accuracy of longitudinal global strain (global-ε) by speckle tracking for assessing left ventricular (LV) systolic function. The study included 70 patients (57 ± 17 years, 64% men), 28 selected patients with a suboptimal image quality (IQ) defined by three or more segments (4 ± 3 segments/patient) with wall motion score not analysable visually and 42 patients with an optimal two-dimensional (2D) echocardiography IQ. Left ventricular ejection fraction (LVEF) by Simpson's biplane method (2D-EF), global-ε by speckle tracking, and peak systolic mitral annulus velocity [systolic tissue Doppler imaging (S-TDI)] were compared with LVEF by cardiac magnetic resonance (EF-CMR; 45 ± 18%, range 9-76%). Speckle-tracking analysis was feasible in all segments with an optimal acoustic window and in 85% (103/121) of segments poorly visualized. Global-ε similarly correlated with LVEF by CMR in patients with and without optimal IQ (r = 0.81 vs. 0.82 for good vs. poor IQ). In contrast, 2D-EF (r = 0.76) and S-TDI (r = 0.64) less correlated with LVEF by CMR in patients with a suboptimal IQ. Importantly, IQ only impacted on 2D-EF inter-observer reproducibility (9 ± 5 vs. 24 ± 22% for good vs. poor IQ) but not on global-ε reproducibility (9 ± 1 vs. 8 ± 7% for good vs. poor IQ). In patients with a limited acoustic window, longitudinal strain by speckle tracking remains accurate and reproducible for assessing global and regional LV systolic function.

Evaluation of pulmonary arterial hypertension: invasive or noninvasive?

In medical research animal models have demonstrated their value in elucidating (1) mechanisms of disease, (2) factors implicated in morbidity and mortality of the disease, and (3) new therapeutic avenues to treat the disease. For acute as well as chronic diseases, models for translational medicine have been developed and applied with great benefit. The use of experimental animals should comply with both the Animal Welfare Act and the Guide for the Care and Use of Laboratory Animals in which researchers demonstrate that they have carefully considered the three R’s of animal testing alternatives: (1) Reduction of the numbers of animals used, (2) Refinement of techniques and procedures to reduce pain and distress, and (3) Replacement of animals by other models than living animals. Particularly the condition to reduce the number of animals necessary to test a hypothesis is difficult to meet, but the use of animal models and techniques that allow longitudinal measurements from the same animals may lead to a wealth of data from a limited number of animals. In translational research of cardiovascular disease the use of echocardiography allows longitudinal studies of natural history and therapeutic success. In the current issue of the International Journal of Cardiovascular Imaging, Koskenvuo and coworkers [1] used echocardiography in a rat model of monocrotaline-induced pulmonary arterial hypertension (PAH). The authors evaluated whether invasive measurements of blood pressures, vascular resistances, right ventricular (RV) wall thickness and RV cavity size could be replaced accurately by corresponding echocardiographic measurements. The authors succeeded to acquire echocardiographic images that produced parameters of PAH with low ( 25 mmHg, the authors found a sensitivity of 86.4%, a specificity of 97.6%, a positive predictive value of 92.3%, and a negative predictive value of 93.8%. At day 21, noninvasive assessment of PAH demonstrated large differences between invasively measured systolic PAP and echocardiographically assessed systolic PAP (39.5 ± 15.5 and 66.4 ± 18.8 mmHg, respectively) and between invasively measured total pulmonary vascular resistance (TPVR) and echocardiographically assessed TPVR (3.5 ± 2.3 and 7.7 ± 2.8 104*dyn.s.cm−5). The authors held these large differences responsible to the absence of significant tricuspid valve regurgitation (TR) jet in several rats with developing PAH. This seems a very likely explanation as at day 35 both invasively measured systolic PAP and TPVR approached echocardiographically assessed systolic PAP and TPVR much better. Of note, TPVR has not previously been studied in rodents using echocardiography. It was concluded that the use of non-invasive parameters may replace invasive measurements in detecting successful disease induction and to complement invasive data in the evaluation of PAH severity in a rat model. The difficulty of performing invasive measurements in animals with advanced PAH is an important limitation of all invasive parameters and underscores the importance of innovative noninvasive measurements. The highly vulnerable status of the RV and more generally of the heart in rats with severe PAH often hampers extensive characterization of RV function with the pressure-conductance catheter as we have experienced ourselves [2–4]. As a result, echocardiography may have a specific new role in evaluating PAH. The main disadvantage of electrocardiographic assessment of PAH is to accurately assess the functional characteristics of RV. In the present study, in 13 out of 75 (17%) studies no adequate echocardiographic RV measurements could be performed. Generally, assessment of the RV is cumbersome by echocardiography due to limited acoustic window and the abnormal shape of the RV [5–16]. These limitations might be to a certain extent overcome by using transesophageal or 3D-echocardiography [17–21], but magnetic resonance imaging often provides a better visualization of the RV, allowing improved quantification [22–33]. In the current study [1], however, it was clearly shown that employment of echocardiography in animals allows assessment of in vivo RV function without additional harm to the animals. In addition, echocardiography enabled longitudinal measurements thereby lowering the number of animals included in the study. Knowledge and experience in echocardiography of small rodents, so elegantly shown by the authors, is hard to acquire but this is certainly the way to go in future translational research of chronic cardiovascular diseases.