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Biomedical subjects

Jan Bogaert

Publications and source records attributed to Jan Bogaert.

At least 19 recordsLinked to original sources
PubMed2006

Amyloidosis of the heart and respiratory system.

Since the incidence of amyloidosis is increasing, the purpose of this article is to review the imaging features of intrathoracic amyloidosis. Amyloidosis forms a heterogeneous group of disorders characterised by the extracellular deposition of a homologous protein complex. The heart is the most commonly involved organ in the chest. Respiratory amyloidal deposition is much less common and may be generalised, when it occurs as a part of a systemic disease, or it may be restricted only to the respiratory system. Although, the abnormalities are considered non-specific, recent literature suggests-especially for cardiac amyloidosis-specific patterns of abnormalities.

Amyloidosis↗
PubMed2006

Autologous bone marrow-derived stem-cell transfer in patients with ST-segment elevation myocardial infarction: double-blind, randomised controlled trial.

BACKGROUND: The benefit of reperfusion therapies for ST-elevation acute myocardial infarction (STEMI) is limited by post-infarction left-ventricular (LV) dysfunction. Our aim was to investigate the effect of autologous bone marrow-derived stem cell (BMSC) transfer in the infarct-related artery on LV function and structure. METHODS: We did a randomised, double-blind, placebo-controlled study in 67 patients from whom we harvested bone marrow 1 day after successful percutaneous coronary intervention for STEMI. We assigned patients optimum medical treatment and infusion of placebo (n=34) or BMSC (n=33). Our primary endpoint was the increase in LV ejection fraction and our secondary endpoints were change in infarct size and regional LV function at 4 months' follow-up, all assessed by MRI. We assessed changes in myocardial perfusion and oxidative metabolism with serial 1-[11C]acetate PET. Analyses were per protocol. This study is registered with , number NCT00264316. FINDINGS: Mean global LV ejection fraction 4 days after percutaneous coronary intervention was 46.9% (SD 8.2) in controls and 48.5% (7.2) in BMSC patients, and increased after 4 months to 49.1% (10.7) and 51.8% (8.8; OR for treatment effect 1.036, 95% CI 0.961-1.118, p=0.36). Compared with placebo infusion, BMSC transfer was associated with a significant reduction in myocardial infarct size (BMSC treatment effect 28%, p=0.036) and a better recovery of regional systolic function. Myocardial perfusion and metabolism increased similarly in both groups. We noted no complications associated with BMSC transfer and all but one patient in the BMSC group completed the 4 months' follow-up. INTERPRETATION: Intracoronary transfer of autologous bone marrow cells within 24 h of optimum reperfusion therapy does not augment recovery of global LV function after myocardial infarction, but could favourably affect infarct remodelling.

Angioplasty, Balloon, Coronary↗
PubMed2005

Cardiac three-dimensional magnetic resonance imaging and fluoroscopy merging: a new approach for electroanatomic mapping to assist catheter ablation.

BACKGROUND: Modern nonfluoroscopic mapping systems construct 3D electroanatomic maps by tracking intracardiac catheters. They require specialized catheters and/or dedicated hardware. We developed a new method for electroanatomic mapping by merging detailed 3D models of the endocardial cavities with fluoroscopic images without the need for specialized hardware. This developmental work focused on the right atrium because of the difficulties in visualizing its anatomic landmarks in 3D with current approaches. METHODS AND RESULTS: Cardiac MRI images were acquired in 39 patients referred for radiofrequency catheter ablation using balanced steady state free-precession sequences. We optimized acquisition and developed software for construction of detailed 3D models, after contouring of endocardial cavities with cross-checking of different imaging planes. 3D models were then merged with biplane fluoroscopic images by methods for image calibration and registration implemented in a custom software application. The feasibility and accuracy of this merging process were determined in heart-cast experiments and electroanatomic mapping in patients. Right atrial dimensions and relevant anatomic landmarks could be identified and measured in all 3D models. Cephalocaudal, posteroanterior, and lateroseptal diameters were, respectively, 65+/-11, 54+/-11, and 57+/-9 mm; posterior isthmus length was 26+/-6 mm; Eustachian valve height was 5+/-5 mm; and coronary sinus ostium height and width were 16+/-3 and 12+/-3 mm, respectively (n=39). The average alignment error was 0.2+/-0.3 mm in heart casts (n=40) and 1.9 to 2.5 mm in patient experiments (n=9), ie, acceptable for clinical use. In 11 patients, reliable catheter positioning and projection of activation times resulted in 3D electroanatomic maps with an unprecedented level of anatomic detail, which assisted ablation. CONCLUSIONS: This new approach allows activation visualization in a highly detailed 3D anatomic environment without the need for a specialized nonfluoroscopic mapping system.

Arrhythmias, Cardiac↗
PubMed2005

Detection of pericardial inflammation with late-enhancement cardiac magnetic resonance imaging: initial results.

OBJECTIVE: To examine the value of late-enhancement cardiac magnetic resonance imaging (MRI) for detection of pericardial inflammation. MATERIALS AND METHODS: Late-enhancement cardiac MRI was performed in 16 patients with clinical suspicion of pericardial disease. Pericardial effusion, pericardial thickening and pericardial enhancement were assessed. MRI findings were compared with those of definitive pericardial histology (n=14) or microbiology (n=2). A control group of 12 patients with no clinical evidence of pericardial disease were also imaged with the same MRI protocol. RESULTS: Sensitivity and specificity for late-enhancement MRI detection of pericardial inflammation was of 100%. There was MRI late enhancement of the pericardial layers in all five patients with histological/microbiological evidence of inflammatory pericarditis. MRI demonstrated no pericardial thickening and no MRI late enhancement with or without a pericardial effusion in any of the five patients with histological evidence of a normal pericardium. MRI detected pericardial thickening in the absence of both pericardial effusion and late enhancement in all six patients with histological evidence of chronic fibrosing pericarditis. The 12 control subjects showed no evidence of pericardial MRI late enhancement. CONCLUSIONS: These findings demonstrate that MRI late enhancement can be used to visualize pericardial inflammation in patients with clinical suspicion of pericardial disease.

Adult↗
PubMed2005

Assessment of ventricular coupling with real-time cine MRI and its value to differentiate constrictive pericarditis from restrictive cardiomyopathy.

The purpose of this study was to evaluate the use of respiratory-related ventricular coupling to differentiate patients with constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM). In 18 histologically proven cases of CP, 6 patients with inflammatory pericarditis (IP), 15 RCM patients and 17 normal subjects, real-time cine MRI was performed in the cardiac short-axis (basal half of the ventricles) during operator-guided deep respiration. The images were analyzed for ventricular septal position and shape during early ventricular filling. Early diastolic septal inversion (I) or flattening (F) was found in all CP (I:15,F:3), and in all IP (I:2,F:4), but seldom in normals (F:1) and not in RCM. The septal abnormalities occurred at the onset of inspiration and rapidly disappeared with the next heartbeats. The amount of ventricular coupling was evaluated by quantifying the difference in the maximal septal excursion between inspiration and expiration. This parameter, normalized to the biventricular diameter, was significantly larger in CP (20.0+/-4.5%, P<0.0001) and IP (14.8+/-3.2%, P<0.0001) patients than in normals (7.0+/-2.4%), whereas RCM patients had a trend toward decreased excursion (4.2+/-1.7%, P=0.11). A cut-off value of 11.8% (mean normals +2 SD) enabled to differentiate CP patients from normals and RCM patients completely. Real-time cine MRI can easily depict increased ventricular coupling, which may be helpful to better differentiate between CP and RCM patients, especially in patients with normal or minimally thickened pericardium. The increase in coupling in IP patients is likely caused by decreased compliance of the inflamed pericardial layers.

Aged↗
PubMed2005

Real-time cine MRI of ventricular septal motion: a novel approach to assess ventricular coupling.

The purpose of this study was to assess the feasibility of magnetic resonance imaging (MRI) to evaluate in real-time, the effects of respiration in ventricular septal motion and configuration in normal volunteers and cardiac patients. Real-time cine MRI studies, using the steady-state free precession (SSFP) technique, were performed in the cardiac short-axis during operator-guided deep inspiration and expiration in normal volunteers (N = 6), and in patients with constrictive pericarditis (CP; N = 6), restrictive cardiomyopathy (RCM; N = 4), chronic cor pulmonale (N = 5), and pericardial effusion. The respiratory effects on septal position and configuration during early ventricular filling were visually assessed. Results were compared with the short-axis breath-hold cine MRI studies, obtained at end-inspiration. In CP patients, onset of inspiration led to a leftward inversion in four of six patients and flattening of the septum in two of six patients during early ventricular filling. Septal abnormalities progressively disappeared during the following heartbeats. A similar pattern was found in one of six patients with pericardial effusion. The above pattern was absent in RCM patients. Although septal flattening during early inspiration was also found in two of six normal volunteers, flattening was minimal compared to that in CP patients. In all cor pulmonale patients, septal flattening or inversion was present, but this was not influenced by respiratory motion. Real-time cine MRI is a promising technique for determining the influence of respiration on septal motion and might be helpful in differentiating between different causes of impaired ventricular filling.

Adult↗
PubMed2005

Delayed contrast-enhanced MRI: use in myocardial viability assessment and other cardiac pathology.

As in other organs, tissue characterization is important for many cardiac diseases. For example, in ischemic heart disease, differentiation between reversibly and irreversibly damaged myocardium in patients with a prior myocardial infarction is crucial in determining disease severity, functional recovery and patient outcome. With the recent advent of the single inversion-recovery contrast-enhanced magnetic resonance imaging (MRI) sequence (delayed contrast-enhanced MRI), contrast between normal and abnormal tissues could be significantly enhanced compared with the conventional cardiac MRI sequences, enabling even subtle abnormalities to be visualized. Together with other advances in cardiac MRI (e.g. functional imaging, coronary artery imaging), MRI has become one of the preferred non-invasive modalities to study cardiac diseases. In this paper an overview of the versatility of delayed contrast-enhanced MRI for investigating cardiac diseases is given.

Contrast Media↗
PubMed2005

Validation and application of single breath-hold cine cardiac MR for ventricular function assessment in children with congenital heart disease at rest and during adenosine stress.

PURPOSE: To validate the accuracy of ventricular function analysis using a single breath-hold real-time steady sate free precession (SSFP) cine MR method and demonstrate its application during adenosine stress imaging in children with congenital heart disease. MATERIALS AND METHODS: Twenty-eight subjects with congenital heart disease were studied (mean age 12.4 +/- 2.3 years) with MR imaging at 1.5 T. Short-axis images covering the entirety of both ventricles were acquired at rest, with a conventional segmented SSFP cine sequence acquired over multiple breath-holds and a single breath-hold real-time SSFP sequence. Seventeen subjects were given an infusion of adenosine, and the single breath-hold real-time short-axis stack was repeated during stress. Two independent observers performed the ventricular function analysis. Data was compared between the 2 acquisition methods at rest and between the single breath-hold acquisition at rest and during adenosine stress. RESULTS: There was good agreement between the multiple breath-hold and single breath-hold methods for measurement of end-diastolic volume (r = 0.95 and 0.96, p < .0001) and end-systolic volume (ESV) (r = 0.76 and 0.90, p < .0001) for the left and right ventricles respectively, and the left ventricular mass (r = 0.97, p < .0001). Adenosine was administered safely to all subjects. During stress there were significant changes in the heart rate and ESV, which led to a significant increase in cardiac output (mean 1.5 +/- 1.0 L/min, p < .001). CONCLUSION: Single breath-hold real-time SSFP cine imaging is robust and accurate in assessing cardiac function in children with congenital heart disease. An application of this method is the rapid assessment of cardiac function during adenosine stress.

Adenosine↗
PubMed2005

An augmented reality system for patient-specific guidance of cardiac catheter ablation procedures.

We present a system to assist in the treatment of cardiac arrhythmias by catheter ablation. A patient-specific three-dimensional (3-D) anatomical model, constructed from magnetic resonance images, is merged with fluoroscopic images in an augmented reality environment that enables the transfer of electrocardiography (ECG) measurements and cardiac activation times onto the model. Accurate mapping is realized through the combination of: a new calibration technique, adapted to catheter guided treatments; a visual matching registration technique, allowing the electrophysiologist to align the model with contrast-enhanced images; and the use of virtual catheters, which enable the annotation of multiple ECG measurements on the model. These annotations can be visualized by color coding on the patient model. We provide an accuracy analysis of each of these components independently. Based on simulation and experiments, we determined a segmentation error of 0.6 mm, a calibration error in the order of 1 mm and a target registration error of 1.04 +/- 0.45 mm. The system provides a 3-D visualization of the cardiac activation pattern which may facilitate and improve diagnosis and treatment of the arrhytmia. Because of its low cost and similar advantages we believe our approach can compete with existing commercial solutions, which rely on dedicated hardware and costly catheters. We provide qualitative results of the first clinical use of the system in 11 ablation procedures.

Algorithms↗
PubMed2004

MR coronary angiography and late-enhancement myocardial MR in children who underwent arterial switch surgery for transposition of great arteries.

PURPOSE: To prospectively evaluate the feasibility of magnetic resonance (MR) coronary artery imaging and to define myocardial damage with late-enhancement myocardial MR imaging in children who underwent arterial switch surgery for transposition of the great arteries. MATERIALS AND METHODS: The local research ethics committee approved this study, and the subjects and/or a parent or guardian gave informed consent. Sixteen asymptomatic subjects who had undergone arterial switch surgery for transposition of the great arteries were studied (mean age, 10.8 years +/- 1.3; 11 male subjects, five female subjects). MR coronary angiography, late-enhancement MR imaging, global ventricular function, and regional wall motion were assessed. Fifteen children were awake during imaging; one was imaged with the use of general anesthetic. RESULTS: In 23 (72%) of 32 coronary arteries imaged, diagnostic-quality images of the coronary ostium and proximal coronary artery course were acquired; this increased to 100% in subjects older than 11 years. No coronary ostial stenoses were seen. In all subjects, the proximal course of the coronary arteries was visualized. Two subendocardial viability defects were detected, which corresponded to known compromise of the artery that supplied that territory at the time of surgery. Global left and right ventricular function were preserved, with no regional wall abnormalities. CONCLUSION: Diagnostic-quality MR coronary angiography is feasible in subjects who have undergone arterial switch surgery for transposition of the great arteries, with no unexpected areas of myocardial infarction detected.

Adolescent↗
PubMed2004

Decision tree algorithm for detection of spatial processes in landscape transformation.

The conversion of landscapes by human activities results in widespread changes in landscape spatial structure. Regardless of the type of land conversion, there appears to be a limited number of common spatial configurations that result from such land transformation processes. Some of these configurations are considered optimal or more desirable than others. Based on pattern geometry, we define ten processes responsible for pattern change: aggregation, attrition, creation, deformation, dissection, enlargement, fragmentation, perforation, shift, and shrinkage. A novelty in this contribution is the inclusion of transformation processes causing expansion of the land cover of interest. Consequently, we propose a decision tree algorithm that enables detection of these processes, based on three parameters that have to be determined before and after the transformation of the landscape: area, perimeter length, and number of patches of the focal landscape class. As an example, the decision tree algorithm is applied to determine the transformation processes of three divergent land cover change scenarios: deciduous woodland degradation in Cadiz Township (Wisconsin, USA) 1831-1950, canopy gap formation in a terra firme rain forest at the Tiputini Biodiversity Station (Amazonian Ecuador) 1997-1998, and forest regrowth in Petersham Township (Massachusetts, USA) 1830-1985. The examples signal the importance of the temporal resolution of the data, since long-term pattern conversions can be subdivided in stadia in which particular pattern components are altered by specific transformation processes.

Algorithms↗
PubMed2004

Regional right and left ventricular function after the Senning operation: an ultrasonic study of strain rate and strain.

BACKGROUND: Systemic right ventricular dysfunction is a major concern in the follow-up of patients who underwent an atrial redirection procedure for transposition (concordant atrio-ventricular and discordant ventriculo-arterial connections). No good non-invasive method is currently available for quantifying right ventricular function. AIMS: We have used ultrasonically based imaging of strain rate and strain to quantify regional deformation in the right ventricle after the Senning operation, comparing properties of regional deformation of the right ventricle with right ventricular ejection fraction as measured using magnetic resonance imaging. METHODS: In 20 asymptomatic patients who had undergone the Senning procedure, we measured peak systolic strain rate and systolic strain values in the right ventricular free wall, the septum and the left ventricular lateral wall using colour Doppler myocardial imaging, comparing the data with findings obtained in 30 healthy subjects. Global right ventricular ejection fraction was assessed using magnetic resonance imaging. RESULTS: Properties of deformation of the right ventricular free wall were reduced and homogeneous after the Senning procedure compared to normals, with significantly lower values for peak systolic strain rate and systolic strain (-1.1 +/- 0.4 vs. -2.5 +/- 0.9 s(-1); p < 0.05 and -16 +/- 7% vs. -38 +/- 13%; p < 0.05, respectively). There was a significant correlation between regional longitudinal right ventricular systolic strain values and right ventricular ejection fraction (r = -0.87, p < 0.001). In the septum, peak systolic strain rate was again reduced and homogeneous (-1.2 +/- 0.4 vs. -1.8 +/- 0.5 s(-1); p < 0.05 vs. normals). Also in the left ventricle, the lateral wall peak systolic strain rate and systolic strain values were reduced (-1.5 +/- 0.5 vs. -2.1 +/- 0.9 s(-1); p < 0.05 and -20 +/- 6% vs.-25 +/- 9%; p < 0.05, vs. normals, respectively). CONCLUSIONS: Properties of regional longitudinal deformation of the systemic right ventricle are reduced after the Senning procedure compared to normal controls, and correlate well with global right ventricular performance. These findings suggest that ultrasonic strain rate and strain imaging could be used in the non-invasive follow-up of ventricular function in these patients.

Adolescent↗
PubMed2004

Role of computed tomography in lung cancer staging.

PURPOSE OF REVIEW: Computed tomography has always been an important imaging technique in lung cancer staging but, due to its well-known limitations, additional imaging and/or invasive tests are usually performed. Purpose of this review is to determine whether new developments in CT and in the other staging techniques have changed the role of CT. RECENT FINDINGS: Despite important technical improvements and the availability of new CT applications, the recent literature confirms the limitations of CT in staging patients with NSCLC. Most attention was given however to other invasive and noninvasive staging techniques and their accuracy in comparison with CT. It was shown that FDG-PET is very useful in the preoperative patient with NSCLC and that it is, especially in N-staging, more accurate than CT. Also combining CT or FDG-PET with EUS-FNA biopsy seems to be a good approach in some indications. Finally, the first reports on the use of integrated PET-CT scanners in lung cancer staging were published and very promising results were shown. SUMMARY: Computed tomography stays nevertheless the routine imaging procedure for staging patients with NSCLC although performing a PET scan in addition to this CT examination seems to be a good approach that can reduce but certainly not always avoid invasive staging procedures. Mediastinoscopy is still generally considered the standard of care when tissue needs to be obtained from suspicious nodes on FDG-PET and/or CT, although minimally invasive biopsy techniques could replace to a large extent this more invasive technique in the near future.

Humans↗
PubMed2003

Clinically suspected constrictive pericarditis: MR imaging assessment of ventricular septal motion and configuration in patients and healthy subjects.

PURPOSE: To assess ventricular septal motion and quantify the septal configuration in patients clinically suspected of having constrictive pericarditis (CP), and to compare these patients with healthy subjects and with patients who have other diastolic heart abnormalities such as restrictive cardiomyopathy (RCM). MATERIALS AND METHODS: In 41 patients clinically suspected of having CP and 12 healthy subjects, magnetic resonance (MR) imaging yielded information about cardiac morphology and function. On short-axis cine MR images, septal motion was assessed, and the septal and left ventricular free wall (LVFW) radii of curvature were quantified and normalized to end systole. Abnormal diastolic septal motion was expressed in terms of the largest difference in normalized radius between the septum and the LVFW. Analysis of variance was used to identify significant differences in septal shape among subject groups. RESULTS: Left-sided septal flattening was identified in 17 of the 21 patients with surgically proven CP, in none of the 20 patients without CP, and in none of the healthy subjects. CP without septal flattening was present on the left side (n = 1), on the right side (n = 1), and at the atrioventricular grooves (n = 2). Abnormal septal motion yielded a sensitivity of 81% (17 of 21 patients), specificity of 100% (20 of 20 patients), accuracy of 90% (37 of 41 patients), positive predictive value of 100% (17 of 17 patients), and negative predictive value of 83% (20 of 24 patients) in the detection of CP. The maximal difference in normalized radius of curvature between the septum and the LVFW in the patients with CP was significantly different from that in the patients without CP (P <.001) and that in the healthy subjects (P <.001). CONCLUSION: Abnormal diastolic septal motion is a frequent phenomenon of CP. If present in patients suspected of having CP, this finding is helpful in distinguishing CP from RCM.

Adult↗
PubMed2003

MRI and CT revealing carcinoid heart disease.

Carcinoid heart disease is a frequent complication of the carcinoid syndrome, usually presenting as right-sided valvular heart disease. Although the diagnosis is most often made with cardiac ultrasound, MRI and CT are valuable techniques for diagnosing carcinoid heart disease.

Aged↗
PubMed2003

Evolution of regional performance after an acute anterior myocardial infarction in humans using magnetic resonance tagging.

Regional remodelling after a left ventricular myocardial infarction is the first step in a cascade that may lead to heart failure and death. To understand better the mechanisms underlying this process, it is important to study not only the evolution in local deformation parameters but also the corresponding loading conditions. Using magnetic resonance (MR) myocardial tagging, we measured the regional contribution to ejection (regional ejection fraction) and loading (systolic blood pressure x radius of curvature (mean of short and long axes)/wall thickness) in 32 regions throughout the left ventricle (LV) in patients 1 week (1W) and 3 months (3M) after a first anterior infarction. Using positron emission tomography (PET), the LV was divided into infarct, adjacent and remote regions. In the remote regions the average deformation decreased between 1W and 3M (from 59.3 +/- 5.6 to 57.9 +/- 6.7 %, P < 0.05) due to an increase in loading conditions only (from 730 +/- 290 to 837 +/- 299 mmHg, P < 0.05). In the adjacent myocardium, no change in function was observed (49.0 +/- 10.8 to 49.0 +/- 6.5 %, P = n.s.), although loading increased (806 +/- 297 to 978 +/- 287 mmHg, P < 0.05). In the infarct region only, an increase in deformation was seen (30.7 +/- 14.2 to 37 +/- 6.9 %, P < 0.05), together with a higher loading level (1229 +/- 422 to 1466 +/- 284 mmHg, P < 0.05), which indicates a true improvement in function. The fact that MR tagging can identify both regional deformation and loading permits us to differentiate between changes due to alterations in regional loading conditions and true changes in function. After an acute myocardial infarction (MI), an improvement can be observed in the deformation-loading relation in the adjacent and infarct regions, but the improvement is mainly in the infarct region. Using this technique, types of intervention leading to even more functional gain could be evaluated.

Adult↗
PubMed2003

Coronary artery imaging with real-time navigator three-dimensional turbo-field-echo MR coronary angiography: initial experience.

PURPOSE: To examine the value of a commercially available three-dimensional (3D) real-time navigator magnetic resonance (MR) coronary angiographic examination for detection of significant coronary artery stenoses, with conventional coronary angiography as the standard of reference. MATERIALS AND METHODS: Twenty-one patients underwent 3D navigator MR coronary angiography immediately before catheterization. Two observers independently graded image quality on a scale from 1 (unreadable) to 5 (excellent), quantified coronary artery visualization, and evaluated the presence of significant (ie, >50% narrowing) stenoses. kappa statistics were used to assess interobserver agreement, and receiver operating characteristic (ROC) analysis was used to assess stenosis detection. RESULTS: For two of 21 patients, MR coronary angiogram quality was insufficient for analysis (mean score < 2). For the remaining 19 patients, the mean image quality scores assigned by observers 1 and 2 were 3.3 +/- 1.0 (SD) and 3.2 +/- 0.9, respectively. A mean of 71% of all coronary artery segments were visible at MR coronary angiography, and there was 91% agreement between the observers (kappa = 0.78). Observers 1 and 2 detected significant stenoses (n = 29) at MR coronary angiography with sensitivities of 44.4% and 55.5%, respectively; specificities of 95.1% and 83.7%, respectively; and 80% agreement (kappa = 0.35). Areas under the ROC curve were 0.817 and 0.795 for observers 1 and 2, respectively. CONCLUSION: Large portions of the coronary arteries can be visualized with MR coronary angiography. Imaging results are not consistently reliable, however. The examination is premature for routine clinical assessment of significant coronary artery stenosis owing to low sensitivity and large observer variability.

Adult↗