PubMed Health⌕ Search

Biomedical subjects

U Sechtem

Publications and source records attributed to U Sechtem.

At least 109 records · Page 6Linked to original sources
PubMed1992

[Magnetic resonance tomography image of transmural myocardial infarct in comparison with 99mTc-methoxyisobutylisonitrile SPECT].

To assess the ability of magnetic resonance imaging (MRI) to identify morphologic and functional abnormalities associated with transmural anterior and inferior myocardial infarction, 18 patients with anterior myocardial infarcts and 11 patients with inferior myocardial infarcts confirmed by ECG and cine-ventriculography underwent gradient-echo MRI of transverse and short-axis imaging planes. Myocardial perfusion of corresponding imaging planes was measured by 99mTc-methoxyisobutyl-isonitrile single-photon emission computed tomography (MIBI-SPECT). Transmural scar by MRI was defined as diastolic wall thickness 2.5 SD below corresponding normal values of a healthy control group (n = 21). MIBI-SPECT scar was defined as a MIBI uptake less than 2.5 SD below mean values of a healthy control group (n = 11). By MIBI-SPECT, 231 segments contained normal tissue and 161 contained scarred myocardium. In 352/392 (90%) segments gradings based on diastolic wall thickness and MIBI-SPECT gradings were identical. Diastolic wall thickness was significantly higher in normal than in scarred MIBI-SPECT segments (10.3 +/- 1.5 vs 5.2 +/- 2 mm, p less than 0.0001). Additionally, normal segments by MIBI-SPECT showed significantly higher systolic wall thickening than scar segments (5.5 +/- 1.5 vs 0.6 +/- 1.6 mm, p less than 0.0001). The correlation between MRI and MIBI-SPECT assessed infarct size was r = 0.91 for anterior and r = 0.77 for inferior myocardial infarcts. The agreement between MIBI-SPECT perfusion defect size and regions with reduced diastolic wall thickness on MRI tomograms was significantly better for anterior myocardial infarcts than for inferior myocardial infarcts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Effort-induced myocardial wall motion abnormalities in the magnetic resonance tomogram: a comparison with effort MIBI SPECT].

In 20 patients with an angiographically documented coronary artery stenosis of > or = 70% and normal LV function at rest MRI was performed before and after dipyridamole infusion (0.75 mg/kg BW). In all patients MIBI-SPECT was obtained at rest and after dynamic symptom-limited exercise. In 18 patients MIBI-SPECT showed ischemia and in 18 patients dipyridamole MRI showed a wall motion impairment. In the segments representing the 29 stenosed vessels ischemia in MIBI-SPECT was diagnosed correctly in 24 instances (sensitivity 83%, specificity 90%) and a wall motion abnormality was present in MRI in 23 instances (sensitivity 79%, specificity 90%). Dipyridamole GE-MRI is not superior to MIBI-SPECT in the diagnosis of ischemia.

Aged↗
PubMed1992

[Magnetic resonance tomography in coronary heart disease].

Although magnetic resonance imaging is currently only employed to solve diagnostic problems in a few selected patients, the special features of the technique such as its inherent three-dimensional capabilities and the prospect of angiographic noninvasive imaging suggest that this technique will become more important with future technical improvements. This overview summarizes the present status of magnetic resonance imaging in the depiction of coronary arteries and bypass grafts, the diagnosis of myocardial ischemia, the depiction of chronic myocardial infarcts including the detection of residual viable myocardium, and the diagnosis of complications associated with myocardial infarction.

Coronary Disease↗
PubMed1992

[Assessment with magnetic resonance tomography of anatomy and ventricular function after Mustard correction of transposition of the great arteries].

In order to evaluate postoperative sequelae and ventricular function after Mustard-operation in patients with transposition of the great arteries (TGA), 30 patients were assessed by magnetic resonance imaging in EKG-triggered spin-echo (SE) and gradient-echo (GE) technique. Twenty-three patients, aged 4.7 to 15.8 years, had transposition of the great arteries with intact ventricular septum with or without left-ventricular outflow tract obstruction (TGA+IVS +/- SPS). Seven patients aged 9.5 to 21.7 years had transposition of the great arteries with ventricular septal defect (TGA+VSD). Five patients showed a residual baffle leak, one had a pulmonary venous obstruction, five an obstruction at the caval veins, 13 a left-ventricular outflow tract obstruction, and 14 a tricuspid regurgitation. Right-ventricular enddiastolic volume in patients with TGA+VSD (77.0 +/- 25.5 ml/m2) was significantly higher than in patients with TGA+IVS +/- SPS (61.2 +/- 12.0 ml/m2). In TGA+VSD right-ventricular ejection fraction (47.6 +/- 13.0%) was significantly lower than in patients with TGA+IVS +/- SPS (56.7 +/- 10.7%). The ratio of muscle masses of right to left ventricle was 1.8:1 in patients with TGA+IVS +/- SPS and 2.5:1 in patients with TGA+VSD. In conclusion, after Mustard-operation in patients with transposition of the great arteries (TGA) magnetic resonance imaging provides a comprehensive and noninvasive assessment of postoperative sequelae, residuae, and ventricular function and will, therefore, become the method of choice for postoperative evaluation.

Child, Preschool↗
PubMed1991

Magnetic resonance imaging of cardiac function and morphology in patients with transposition of the great arteries following Mustard procedure.

In order to assess the diagnostic possibilities of magnetic resonance imaging (MRI), 30 children (mean age 11.5 years) with d-transposition of the great arteries (TGA) corrected by the Mustard procedure were studied. Patient values were compared to those of 10 healthy volunteers. The most important postoperative abnormalities such as baffle leaks, systemic or pulmonary venous obstructions, left ventricular outflow tract (LVOT) stenosis and tricuspid regurgitation were assessed. Cardiac volumes and muscle mass were measured. Baffle leaks were found in 5 and obstruction of the baffle limbs in 6 patients. On gradient echo images 13 patients showed signs of LVOT stenosis and 12 tricuspid incompetence. Right ventricular end diastolic volumes in patients were significantly higher than the left ventricular volumes, but slightly lower than right ventricular volumes in the normals. In patients with TGA and ventricular septal defect (VSD) (n = 7) right ventricular (RV) volumes were found to be higher than in patients with intact ventricular septum (n = 23) and in normals. In contrast to the normal RV function of patients after Mustard surgery only patients with previous VSD showed a diminished RV ejection fraction. The muscular mass in TGA patients showed a ratio of 1.9:1 between right and left ventricles. In normals the ratio was 1:1.5. Magnetic resonance imaging allows a quantitative insight into the ventricular function and the morphology of the heart after inflow correction. Thus, it supplements the noninvasive evaluation of TGA patients.

Adolescent↗
PubMed1991

[Magnetic resonance tomography in patients with a heart valve prosthesis].

Artificial valve prostheses are often regarded as a contraindication for magnetic resonance imaging (MRI), although preliminary in vitro studies suggested, that patients with these metallic implants might safely undergo MR examination. This study reports on the experience with a group of 89 patients with 100 heart valve prostheses who were examined by spin-echo MR and gradient-echo MR. MR examination was performed in all patients without complications. The spin-echo sequence showed advantages in the depiction of anatomical structures like paravalvular abscesses. Anatomical structures adjacent to the artificial valve were clearly visible and the metal components of the valves showed no or only small artifacts. Artifacts were accentuated when using gradient-echo sequences. Gradient-echo sequences provided valuable information regarding the presence of valvular insufficiency. Physiological valvular regurgitation was easy to differentiate from pathological paravalvular or transvalvular regurgitation. These results demonstrate that patients with artificial valve prostheses can be imaged by MR without risk and that prosthesis-induced artifacts do no interfere with image interpretation.

Abscess↗
PubMed1991

[Diagnosis and classification of tricuspid valve insufficiency with dynamic magnetic resonance tomography: comparison with right ventricular angiography].

To evaluate the diagnostic potential of magnetic resonance imaging (MRI) to diagnose and evaluate tricuspid incompetence (TI), right ventricular angiography (RVA) and MRI were compared in 51 patients. For angiographic semi-quantification a 4-grade modified Sellers classification was used. Several MRI-parameters (jet volume, jet area, number of slices with visible jet, duration of the regurgitation and volume of the right atrium) were examined concerning their validity to evaluate TI and compared to the angiographic data. Limits for MRI jet areas and volumes for each angiographic group were defined to obtain the best agreement with angiographic results. Thirty of 34 patients with angiographically visible TI (sensitivity = 88%) were diagnosed correctly with MRI. The 4 remaining patients also showed a small regurgitant jet which was, however, interpreted as physiologic. One of the 17 patients without angiographic TI was diagnosed as mild TI by MRI (specificity = 94%). MRI classification using jet volume (46/51 = 90% correct classifications) was not significantly better than the easier and faster MRI classification using jet area (43/51 = 84%). The other parameters (number of slices, duration of regurgitation and volume of the right atrium) showed considerable overlap between angiographic groups and did therefore not allow a classification into 4 grades. However, simple classification into hemodynamic relevant and irrelevant TI was possible. Thus MRI is able to diagnose TI with good sensitivity and specificity. Classifications based on jet volume and jet area showed good agreement with angiographic results. However, both parameters depend on the magnet and the pulse sequence used and must therefore be specifically determined for each imaging routine.

Adult↗
PubMed1991

Left hemitruncus in adulthood: diagnostic role of magnetic resonance imaging.

The diagnosis of left hemitruncus and large patent ductus arteriosus was made by magnetic resonance imaging in an adult patient with recurrent haemoptysis and dyspnoea on exertion. Previous cardiac catheterization and echocardiography failed to establish the complete diagnosis. Magnetic resonance imaging using spin-echo and gradient-echo pulse sequences is a useful imaging modality to evaluate anatomical and functional abnormalities in patients with complex congenital heart disease.

Adult↗
PubMed1989

[Para-aortic pseudoaneurysm following aortic valve replacement. Its diagnosis by magnetic resonance tomography].

Para-aortic pseudoaneurysms after prosthetic replacement of an aortic valve was diagnosed by magnetic resonance imaging (MRI) in two patients and confirmed at surgery. The abscesses had not been visualized in either case by computed tomography and echocardiography, but in one it had been demonstrated by angiography. MRI can thus precisely define site and extent of a para-aortic pseudoaneurysm after aortic valve replacement without any interference by artefact, noninvasively and without use of contrast media.

Abscess↗
PubMed1989

[Thoracic aorta dissection--the place of MRT and CT in the follow-up after prosthetic aortic replacement].

Dynamic CT and MRT were performed in 21 patients who had undergone prosthetic replacement of the aorta because of dissection of the thoracic aorta. There is no difference between MRI and dynamic CT in the demonstration of a persistent intimal flap, the formation of a thrombus and the assessment of the aortic diameter in patients who underwent surgery for thoraco-abdominal aortic dissection. MRI, however, is superior in the identification of the true and false lumen and the demonstration of the distal anastomotic site. The major advantages of MRI are that there is no need for intravenous contrast agents, that it is highly sensitive to flow phenomena, and that it can demonstrate the aortic arch and the ascending aorta on sagittal oblique sections. The major disadvantages of MRI are the limited access to the patient during the procedure, and the inability to examine patients fitted with pacemakers or who are on assisted ventilation. Today, MRI is considered the method of first choice for the postoperative follow-up of patients who underwent surgery for aortic dissection.

Adult↗
PubMed1989

[Noninvasive assessment of aortocoronary bypass using magnetic resonance tomography].

Forty-four patients with recent cardiac catheterization because of recurrent chest pain after coronary artery bypass surgery were studied by magnetic resonance imaging to evaluate graft patency. To assess the efficacy of this non-invasive method 92 coronary artery bypass grafts were examined by the spin-echo technique. ECG-gated transversal sections were acquired between the diaphragm and the aortic arch. The specificity of magnetic resonance imaging was 83% (48/58) for patent grafts. However, the sensitivity in the detection of occluded bypasses was only 56% (19/34). Despite the good specificity, clinical applications of this method are limited because of its low sensitivity.

Coronary Artery Bypass↗
PubMed1989

[Clinical and magnetic resonance tomography follow-up of surgically treated aortic isthmus stenoses in adults].

Functional impairment and local pathological changes of the aorta especially at the site of correction are well known complications after surgery for coarctation of the aorta. To evaluate the longterm results after this operation, 23 patients were assessed by physical examination, EKG, ergometry, spirometry, and magnetic resonance imaging. The postsurgical interval ranged from 1 to 28 years. The most frequent postoperative symptoms were vertigo, headache, dyspnea on exertion, cardiac arrhythmia, and left thoracic pain. Elevation of the left shoulder was found in 19 patients to be due to left lateral thoracotomy; 14 patients suffered from arterial hypertension; five additional patients showed hypertension on exertion. Magnetic resonance imaging showed pathological changes of the aorta and aortic branches in all patients. The origin of the left subclavian artery was displaced distally in eight patients. The proximal part of the left subclavian artery was dilated in 11 patients. Fourteen patients had a hypoplastic aortic arch. An aneurysm of the ascending aorta was found in five patients. Aneurysmal dilatation of the descending aorta in the region of the anastomosis was present in three patients. Restenosis of the descending aorta occurred in two patients. In conclusion, after surgery of coarctation many patients continued to have symptoms which require regular follow-up. Magnetic resonance imaging provides a complete and noninvasive examination of the heart and the great vessels and is therefore ideally suited for this purpose.

Adolescent↗