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J Bogaert

Publications and source records attributed to J Bogaert.

At least 55 records · Page 3Linked to original sources
PubMed1996

Left ventricular radial tagging acquisition using gradient-recalled-echo techniques: sequence optimization.

Myocardial tagging with magnetic resonance (MR) imaging offers unique possibilities for noninvasive left ventricular (LV) strain analysis. True three-dimensional strain analysis can be achieved with tags implemented in cardiac short axis and long axis images. Spin-echo (SE) techniques have been used for these studies. However, this approach is time-consuming: images at different phases of the cardiac cycle have to be obtained in successive measurements and hence the total number of measurements equals the number of time frames. Moreover, the images are often degraded by flow and motion artifacts. The purpose of this study was to optimize a faster and more robust MR tagging sequence for use on a clinical whole-body 1 T MR system with optimal persistence of the tags during the entire cardiac cycle. The tagging pulses were implemented in gradient-recalled-echo (GRE) sequences and compared to SE-based acquisitions. The effects of the use of flow-compensating gradients, the excitation angles, and the angles of the saturation pulses have been studied with MR signal simulations and in comparative measurements in volunteers. GRE acquisitions with flow-compensating gradients are robust techniques for myocardial tagging acquisitions. Use of optimized flip angles and saturation pulses can significantly improve delineation of the tag and can be used up to at least 700 ms after the R-wave. Therefore, LV tagging with GRE acquisitions using optimized MR parameters is a robust and promising technique.

Heart↗
PubMed1996

Integrating digital ICU viewing into the global working environment.

We illustrate that to benefit from the advantages of Picture Archiving and Communication Systems (PACS) for the Intensive Care Unit (ICU), the PACS must be strongly integrated within the overall working environment. This includes adaptation of the PACS toward specific working patterns and integrating it with the Hospital Information System (HIS). This is reflected in our prototype system in different ways. The user interface of the viewing station is centered around often used patterns in ICU viewing. Information about bed occupancy is retrieved from the HIS and exploited in the viewing station. A digital connection between the phosphorplate scanner and the HIS ensures that images are correctly related to other patient information and to previous images. Using minor adaptations to the existing HIS, PACS and HIS have been made to cooperate in integrated presentation of images and radiological reports, as a step towards a multi-media medical information system. We discuss the relation between PACS and the global information environment, emphasizing organizational issues rather than technological aspects.

Computer Systems↗
PubMed1995

Transverse arch hypoplasia predisposes to aneurysm formation at the repair site after patch angioplasty for coarctation of the aorta.

OBJECTIVES: This study used magnetic resonance imaging (MRI) to evaluate the morphology and pathophysiology of aneurysm formation after patch angioplasty for coarctation of the aorta. BACKGROUND: Late aneurysm formation at the repair site is a well known and frequent complication after patch angioplasty. However, because the underlying mechanisms remain unresolved, postoperative outcome is unpredictable and adequate follow-up difficult. METHODS: Seventy-three of 85 patients with patch angioplasty for coarctation of the aorta were screened for aneurysm formation. Magnetic resonance imaging was performed in all 33 patients with an aneurysm, and results were compared with those for 13 control patients and 10 normal subjects. Mean (+/- SD) time between operation and MRI was 12.0 +/- 2.0 years. Aneurysm was defined as the ratio of the diameter of the aorta at the repair site to the diaphragmatic aorta > or = 1.5. Hypoplasia of the transverse arch and recoarctation at the repair site were defined as a ratio < 0.9. Transverse arch ratios on MRI were compared with those on preoperative cineangiography and the pressure gradient between the patient's right and left arm. RESULTS: All 33 patients with an aneurysm had a hypoplastic transverse arch. The 13 patients with a normal ratio at the repair site had a normal transverse arch ratio (chi square, p < 0.0001). Logarithmic regression showed a significant negative correlation (r = 0.62) between the repair site and transverse arch ratios. A significant pressure difference between the patient's right and left arm was found in patients with versus those without aneurysm (p = 0.0009). No significant difference was found between transverse arch ratios on preoperative cineangiography and postoperative MRI (mean 0.014 +/- 0.1, p = 0.4). CONCLUSIONS: Aneurysm formation at the repair site is highly related to hypoplasia of the transverse arch. Sufficient catch-up growth of a hypoplastic transverse arch is rare after late patch angioplasty. Dynamic phenomena, such as flow acceleration and turbulence, originating in a narrow transverse arch, may contribute to aneurysm formation at the repair site after patch angioplasty.

Adolescent↗
PubMed1995

[Spiral CT of the diaphragm].

The diaphragm is a thin musculotendinous structure, which is not or only partially visible with the conventionally used imaging techniques (chest X-ray, ultrasonography, contrast bowel examination, incremental CT). Spiral CT may offer new perspectives to overcome the above mentioned problem. Volumetric data acquisition can be achieved during one apnoea period, which allows to eliminate all respiratory induced artifacts. Reformatting of the axial reconstructed CT data allows furthermore to study the diaphragm in any desired plane. Especially the coronal and sagittal planes are well suited to study the relationship of peridiaphragmatic pathology to the diaphragm. The major limitation of spiral CT is the inability to recognize the diaphragm as a separate structure if the diaphragm is adjacent to another structure with an analogous density such as the liver or the spleen.

Diaphragm↗
PubMed1995

Computed tomography, magnetic resonance imaging, and digital radiography.

There are three milestones in the history of thoracic radiology. Thoracic radiology started in 1897 when Williams developed thoracic fluoroscopy and introduced the basic concepts of roentgenologic interpretation. At the same time, the first chest films were performed allowing decisive improvement in the diagnosis of many chest diseases. Continuous technical improvement is responsible for the fact that, even today, the conventional chest film remains a highly accurate and frequently used imaging modality. A third milestone was the development of digital radiography and its use in the chest. Computerised tomography changed thoracic imaging dramatically; in a first step mainly as a tool to visualise soft tissue abnormalities and, later on, also as a modality to study lung disease. The recent development of the digital chest radiograph has again added new perspectives to the approach and diagnosis of chest disease.

Belgium↗
PubMed1994

Coronary MR angiography: a review.

With the advent of faster magnetic resonance imaging techniques, magnetic resonance angiography (MRA) of the coronary vessels has become a reality. Coronary MRA is a non-invasive imaging technique and preliminary clinical studies appear very promising. Coronary MRA can detect from 63% to 90% of all hemodynamically significant (= 50%) coronary lesions. Typically one can visualize the proximal 5.5 cm of the right coronary artery (RCA), the left main (LM) coronary artery, the proximal 4.5 cm of the left anterior descending (LAD) coronary artery and approximately 1.5 cm of the left circumflex (LCx) coronary artery. The current limitations of coronary MRA include: the inability to visualize the more distal portion of the coronary arteries and coronary artery branches, the need for consistent breath-holding and the need for special patient positioning. Coronary MRA techniques are improving and we feel will become an integral part for the evaluation of patients with ischemic heart disease.

Coronary Angiography↗
PubMed1993

Detection of unsuspected central pulmonary embolism with conventional contrast-enhanced CT.

When fast, nondynamic scanning techniques are used in combination with adequate intravenous injection of contrast material, good-quality images of the pulmonary artery (PA) can be obtained with routine computed tomography (CT). The purpose of this study was to evaluate PA filling defects detected on these CT scans. Twenty-two CT scans from 22 patients with PA filling defects were reviewed. A routine scanning technique was used. Thrombus was unilateral in 12 cases and bilateral in 10. All patients but one had a predisposition for pulmonary embolism (PE). However, only five patients underwent CT because there was a strong suspicion for PE. In 17 cases, PE was not the first choice of clinical diagnosis; in 13 cases, thrombus of the PA was not even considered. Diagnosis was confirmed in 11 patients with ventilation-perfusion scanning (n = 7), angiography (n = 3), and surgery (n = 1). In 11 patients, anticoagulation therapy was started without further diagnostic procedures. Diagnosis of thrombus of the PA is possible with routine nondynamic, contrast material-enhanced CT. Because PE is often unsuspected at clinical examination, every contrast-enhanced CT scan of the chest should be evaluated for the presence of filling defects in the PA.

Adult↗
PubMed1993

Pleomorphic adenoma of the parotid gland.

A retrospective analysis of the CT (n = 18) and MR (n = 4) examinations was performed in 21 patients with a histologically proven pleomorphic adenoma of the parotid gland. This group included 15 primary pleomorphic adenomas, 5 tumor recurrences and one carcinoma ex pleomorphic adenoma. There was a clear female predominance (15/21). On CT, pleomorphic adenoma usually presented as a well defined, round or oval-shaped tumor in the superficial part of the parotid gland, round or oval-shaped tumor in the superficial part of the parotid gland, showing an inhomogeneous captation pattern on contrast enhanced CT. CT sialography offered no complementary information. Although not specific for pleomorphic adenoma, the hyperintense appearance on spin-echo (SE) T2-weighted MRI was helpful in the detection of tumor masses, more specifically small recurrent tumor nodules.

Adenocarcinoma↗
PubMed1992

Pictorial essay: right aortic arch.

Right aortic arch is a rare congenital anomaly. It can be either an isolated finding or it can be part of a double aortic arch. This article discusses the radiographic appearance of this congenital anomaly on conventional chest X-ray, angiography, CT, and MRI.

Aorta, Thoracic↗
PubMedDate not supplied

Appearance of the normal pericardium on coronary MR angiograms.

We evaluated the appearance of the normal pericardium on breath-hold MR images used to visualize coronary arteries. A coronary MR angiogram was obtained in 23 subjects (17 healthy volunteers and six patients with no known pericardial disease) using a breath-hold K-space segmented gradient-recalled echo sequence with fat suppression. Each coronary MR angiographic study included imaging planes equivalent to the following echocardiographic planes: four-chamber view, vertical two-chamber view, and two short-axis views (at base and mid ventricular level). The average pericardial thickness was 1.7 mm (range, 1.5-2.0 mm), and an average length of 60 mm (range, 20-110 mm) of pericardium was visualized. A significantly longer portion of the pericardium was seen in the vertical two-chamber view and the basal short-axis view than in the two other views (P < .001). Normal anatomic variations and overlapping structures and image artifacts can alter the appearance of the pericardium. Breath-hold MR imaging techniques used for coronary MR angiography allow routine, time-efficient evaluation of large portions of the pericardium.

Adolescent↗
PubMedDate not supplied

Right atrial tumor arising on an atrial septal aneurysm. Assessment by MR imaging.

An elderly women presenting with transient ischemic events underwent transesophageal echocardiography, which detected an aneurysm of the interatrial septum. A tumor protruding from the right atrial aspect of the aneurysm also was found incidentally. Not only was magnetic resonance (MRI) imaging helpful in better characterizing the aneurysm, but also the use of gadolinium diethylaminetriamine pentaacetic acid permitted differentiation between the tumor and adherent thrombus. To the best of our knowledge, this represents the first report of a tumor arising from an atrial septal aneurysm.

Aged↗
PubMedDate not supplied

Functional recovery of subepicardial myocardial tissue in transmural myocardial infarction after successful reperfusion: an important contribution to the improvement of regional and global left ventricular function.

BACKGROUND: The transmural extent of myocardial necrosis after an acute coronary artery occlusion can vary considerably. The contribution of residual subepicardial viable myocardium to global left ventricular function is largely unknown. METHODS AND RESULTS: We studied 12 patients with single-vessel disease 1 week after successful reperfusion of a first transmural anterior myocardial infarction (MI). With PET, myocardial blood flow (MBF) and glucose metabolism were measured regionally, and the viability was graded as normal, mismatch, or match with severely (<50% of normal) or intermediately (50% to 80% of normal) impaired MBF. Magnetic resonance tagging was used to regionally quantify fiber strains, wall thickening, and ejection fraction in patients 1 week and 3 months after the MI and in age-matched healthy volunteers. From 1 week to 3 months, subepicardial fiber shortening improved significantly in the match region (MBF <50%, -5.1+/-7.0% to -9.9+/-8. 7%; MBF of 50% to 80%, -7.1+/-7.6% to -14.9+/-7.9%). This was associated with an improvement in regional ejection fraction in the infarcted myocardium (29.6+/-21.8% to 43.5+/-15.5%, P<0.0001) and in normal regions (54.3+/-15.1% to 56.5+/-13.1%, P=0.013), contributing to an increase in global ejection fraction from 44.2+/-22.2% to 49. 3+/-17.9% (P<0.0001). CONCLUSIONS: Functional recovery of viable subepicardial regions is a mechanism of late improvement in regional and global ejection fraction after a so-called transmural MI.

Aged↗