Biomedical subjects

R P Spielmann

Publications and source records attributed to R P Spielmann.

At least 19 recordsLinked to original sources

PubMed1992

Magnetic resonance imaging and pulsed Doppler sonography of poststenotic jets: correlation between signal void and flow velocity distribution.

To correlate the appearance of poststenotic jets on gradient echo images with features of localized Doppler spectra of the jets, we studied an in vitro model of steady flow-through stenoses of 86, 96, and 99% area reduction. As fluids, water and a 40% glycerol solution in water were used. MRI was performed with a 1.5 T whole body imager and gradient echo images were obtained in planes parallel to the direction of flow. Doppler spectra were acquired separately from the MR measurements at 1 cm intervals for a distance of 10 cm downstream from the stenosis. Poststenotic signal void was observed for water and for the 40% glycerol solution only if the mean velocity within the stenosis exceeded a limit of 50-60 cm/sec. On the MR images, the jets could be divided into two segments: A proximal jet segment of uniform width equal to the diameter of the stenosis, followed by a distal jet segment which was characterized by broadening and then dissipating signal void. Except for the 99% stenosis, a high signal intensity core was present within the proximal jet segment. In the proximal jet segment, the Doppler measurements showed a low temporal fluctuation of the maximal flow velocity and only little flow opposite to the main flow direction. In the distal jet segment, the velocity fluctuation and the intensity of reverse flow increased sharply. The high signal intensity core of the jet was associated with a poststenotic zone of constant maximal flow velocity. The results demonstrate a close relationship between characteristic features of poststenotic jets in MRI and pulsed Doppler sonography.

Blood Circulation↗

PubMed1992

[The femoropatellar gliding motion during active knee stretching. Imaging using motion-triggered MR tomography].

By means of motion-triggered MRT it has been possible for the first time to demonstrate movements in the patello-femoral joint by means of MRT. Patello-femoral movement was studied during active extension of the knee between 30 degrees flexion and complete extension. The knees of 5 normal females and 7 normal males were studied together with 2 women with recurrent lateral patellar luxation. In normal women there was an average 16 degrees (10 to 18 degrees), in men an average of 12 degrees (10 to 14 degrees) of lateralisation of the patella during complete extension of the knee. In 1 patient there was 10 degrees medial displacement of the patella before extension. In 2 knees with recurrent lateral subluxation there was a 20 and 24 degrees displacement of the patella.

Adolescent↗

PubMed1992

[The magnetic resonance tomographic signs of Wegener's granulomatosis in the head area].

MRI of the head was performed in 25 patients suffering from Wegener's granuloma. 23 patients showed evidence of mucosal thickening in the paranasal sinuses, the middle and inner ears and in the mastoid cells; these were characterised by low signal intensity of T1-weighted and high signal intensity of T2-weighted images. In 10 patients there were granulomas in the paranasal sinuses and in the orbits which showed low signal intensity of both T1-weighted and T2-weighted images. In 4 patients, additional images were obtained after the intravenous injection of Gd-DTPA. In 2 patients this resulted in non-homogeneous contrast accumulation in the granuloma. In 7 patients there were signal changes in the brain which were typical of infarcts. The complete extent of bone destruction in the facial skeleton was visible only by CT.

Adult↗

PubMed1992

[Orbital involvement in Wegener's granulomatosis].

BACKGROUND: Granulomas of the orbit can complicate Wegener's granulomatosis (WG). If they compress the optic nerve, blindness of one or both eyes may result. Therefore, early detection and sufficient treatment are important. MATERIAL AND METHODS: Computed tomography (CT) and magnetic resonance imaging (MRI) of the orbit and CNS were performed in patients suffering from WG and orbital granulomas (n = 6). The patients were seen interdisciplinary by internists, ENT-specialists, radiologists and ophthalmologists. RESULTS: 12 out of 121 biopsy proven WG-patients showed orbital granulomas during their disease process. Granulomas of the orbit could be best visualized by MRI. However, MRI and CT taken together were most informative. 6 patients with orbital granulomas are presented as case reports, in four of them WG lead to blindness of one eye. The course of orbital granulomas may be chronic progressive or acutely fulminant. Therapy of first choice is a high dosage, long-term immunosuppression with cyclophosphamide and prednisolone. CONCLUSIONS: The detection of orbital granulomas in WG is most successful using CT and MRI. In addition to that, the analysis of visual acuity and visual field are the most important parameters in the detection and follow-up of orbital granulomas. A high dosage, long-term immunosuppression is the treatment of first choice, but in rapidly progressive cases an early decompression of the orbit has to be discussed additionally.

Abscess↗

PubMed1992

Diagnosis of thoracic aortic dissection. Magnetic resonance imaging versus transesophageal echocardiography.

BACKGROUND: Aortic dissection requires prompt and reliable diagnosis to reduce the high mortality. The purpose of this study was to assess the reliability of both ECG-triggered magnetic resonance imaging (MRI) and transesophageal two-dimensional echocardiography combined with color-coded Doppler flow imaging (TEE) for the diagnosis of thoracic aortic dissection and associated epiphenomena. METHODS AND RESULTS: Fifty-three consecutive patients with clinically suspected aortic dissection were subjected to a dual noninvasive imaging protocol in random order; imaging results were compared and validated against the independent morphological "gold standard" of intraoperative findings (n = 27), necropsy (n = 7), and/or contrast angiography (n = 53). No serious side effects were encountered with either imaging method. In contrast to a precursory screening transthoracic echogram, the sensitivities of both MRI and TEE were 100% for detecting a dissection of the thoracic aorta irrespective of its location. The specificity of TEE, however, was lower than the specificity of MRI for a dissection (TEE, 68.2% versus MRI, 100%; p less than 0.005), which resulted mainly from false-positive TEE findings confined to the ascending segment of the aorta (TEE, 78.8% versus MRI, 100%; p less than 0.01). In addition, MRI proved to be more sensitive than TEE in detecting the formation of thrombus in the false lumen of both the aortic arch (p less than 0.01) and the descending segment of the aorta (p less than 0.05). There were no discrepancies between the two imaging techniques in detecting the site of entry to a dissection, aortic regurgitation, or pericardial effusion. CONCLUSIONS: Both MRI and TEE are atraumatic, safe, and highly sensitive methods to identify and classify acute and subacute dissections of the entire thoracic aorta. TEE, however, is associated with lower specificity for lesions in the ascending aorta. These results may still favor TEE as a semi-invasive diagnostic procedure after a precursory screening transthoracic echogram in suspected aortic dissection, but they establish MRI as an excellent method to avoid false-positive findings. Anatomic mapping by MRI may emerge as the most comprehensive approach and morphological standard to guide surgical interventions.

Adult↗

PubMed1992

[Acute and subacute dissection of the thoracic aorta: diagnostic importance of magnetic resonance tomography].

The purpose of this study was to retrospectively assess the reliability of ECG-triggered magnetic resonance imaging (MRI) for the diagnosis of acute and subacute thoracic aortic dissection and associated clinical epiphenomena. 67 patients were subjected to MRI; the diagnostic results were compared with morphological standards. 25 patients had type A, 12 patients type B dissection. In 30 cases a dissection was excluded. 17 patients with aortic dissection had acute onset of symptoms, 10 patients had subacute onset of symptoms. 17 patients revealed thrombosis of the false lumen, which was found in the descending aorta in 59% of the cases. Aortic regurgitation and pericardial effusion was most often associated with type A dissection (Table 1). Three patients were studied while on mechanical ventilation. Scan time for MRI ranged from 15 to 71 minutes with an average of 46 +/- 18 minutes. In this series no deleterious events were encountered related to MRI diagnostics. In contrast to previously published data using other noninvasive techniques the sensitivity of MRI was 100% for detecting a dissection in the ascending segment of the thoracic aorta. Moreover, the specificity of MRI for a dissection was 100% and thus higher than previously published data using transesophageal echocardiography. Sensitivity and specificity for detection and correct classification of type B dissection was 100% and 100% respectively (Table 2). In addition, MRI proved to be sensitive in detecting the formation of thrombus material in the false lumen of the ascending aorta (92%), the aortic arch (100%) and the descending segment (88%). Specificity for exclusion of suspected thrombus material even proved to be slightly higher with 100% in the ascending and descending aorta and 96.1% in the aortic arch (Table 3). The site of entry to a dissection was detected in 78%, with a sensitivity of 76% in the ascending and 92% in the descending aorta. The involvement of side branches in the dissecting process was identified in 60%. There were no false positive findings concerning side branch involvement. Aortic regurgitation and pericardial effusion were detected in 100% and 100%, respectively (Tables 1 and 2). MRI performed even in acute cases proved to be a atraumatic, safe and highly sensitive method to identify and classify acute and subacute dissections of the entire thoracic aorta. Limited patient access was not associated with an increased risk and mechanical ventilation did not interfere with MRI. These results may establish MRI as a valid and promising noninvasive technique to establish the diagnosis in patients with thoracic aortic dissection.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute Disease↗

PubMed1992

[Detection of dissection of the thoracic aorta: improved specificity by magnetic resonance tomography in comparison with echocardiography techniques].

The purpose of this study was to assess the reliability of conventional transthoracic and transoesophageal two-dimensional echocardiography combined with color-coded Doppler flow imaging (TEE) and ECG-triggered magnetic resonance imaging (MRI) for the diagnosis of thoracic aortic dissection and associated epiphenomena. A total of 53 patients with clinically suspected aortic dissection were subjected to a transthoracic and transoesophageal ultrasound examination and magnetic resonance imaging; the results of each imaging modality were compared and validated against the morphological standards of contrast angiography (n = 53) and/or intraoperative findings (n = 27) or autopsy (n = 7). In this series no deleterious events were encountered with either non-invasive imaging method. In contrast to conventional echocardiography the sensitivities of both MRI and TEE were 100% for detecting a dissection of the thoracic aorta, irrespective of its location. However, the specificity of TEE was lower than the specificity of MRI for a dissection (TEE 68.2% versus MRI 100%; p less than 0.005), which resulted from false positive TEE findings mainly confined to the ascending segment of the aorta (specificity of TEE 78.8% versus 100% by MRI; p less than 0.01). In addition, MRI proved to be more sensitive than TEE in detecting the formation of thrombus in the false lumen of both the aortic arch (p less than 0.01) and the descending segment of the aorta (p less than 0.05). There were no discrepancies between the two imaging techniques in detecting the site of entry to a dissection, aortic regurgitation or pericardial effusion. Both MRI and TEE are atraumatic, safe, and highly sensitive methods to identify and classify acute and subacute dissections of the entire thoracic aorta. However, TEE is associated with lower specificity for lesions in the ascending aorta. These results may still favor TEE after a precursory screening transthoracic echogram in suspected aortic dissection, but will establish MRI as an excellent method to avoid false positive findings. Anatomical mapping by MRI may emerge as a promising comprehensive approach and, eventually, as a morphological standard to guide surgical interventions.

Adult↗

PubMed1992

[Magnetic resonance tomographic characteristics and a follow-up observation in a case of cystic lymphangiomas in the left lower extremity, the retroperitoneum and the mediastinum].

Lymphangiomas are rare benign tumours of the lymphatic system and are mostly manifested in the ENT region. The authors describe a rare localisation of this disease originating in the left lower extremity and extending into the retroperitoneum and mediastinum in a 16-year old female patient. MR enabled the diagnosis and the exact determination of the extent. MR follow-up showed 1 1/2 years after the diagnosis that the lymphangiomas and the lymphangioma in the left thigh had reduced and that the proliferation of lymphangioma in the retroperitoneum and mediastinum had stagnated.

Adolescent↗

PubMed1991

Appearance of poststenotic jets in MRI: dependence on flow velocity and on imaging parameters.

A flow model was used to study the appearance of poststenotic jets in MRI. Jets in CuSO4-doped water and bovine blood were imaged by spin-echo (SE) and fast-field-echo (FFE) pulse sequences at different degrees of stenosis and various flow rates. On flow-compensated FFE images, the jets were characterized by signal void if the mean flow velocity within the stenosis exceeded a limit, which was independent of the degree of the stenosis and the type of the fluid. On SE images and on FFE images without flow compensation, signal void occurred at significantly lower flow velocity. The extension of the poststenotic signal void on flow-compensated FFE images was increased by either reduction of the pixel diameter or by prolongation of the echo time. However, it was independent of the orientation of the imaging plane relative to the direction of flow. The results have an impact on attempts to use signal void for the assessment of turbulent jets with MRI.

Animals↗

PubMed1990

Detection of human collateral circulation by vasodilation-thallium-201 tomography.

Coronary arteriolar vasodilation may provoke redistribution of flow to collateral-dependent jeopardized myocardium. To assess the physiologic significance of collaterals, 80 consecutive post-infarction patients (age 58 +/- 8 years) underwent vasodilation-redistribution thallium-201 tomographic imaging after administration of 0.56 mg of intravenous dipyridamole/kg body weight. Circumferential profile analysis of thallium-201 uptake and redistribution in representative left ventricular tomograms provided quantitative assessment of transient and fixed defects and separation between periinfarctional and distant inducible hypoperfusion. Tomographic perfusion data were correlated to wall motion and collateral circulation between distinct anatomic perfusion territories. Patients were grouped according to presence (59%) or absence (41%) of angiographically visible collateral channels to jeopardized myocardium. In the presence of collaterals, distant reversible defects were larger than in absence of collaterals (p less than 0.05); the extent of combined periinfarctional and distant redistribution was also larger in collateralized patients (p less than 0.025), whereas the size of the persistent perfusion defect was similar in both groups. By prospective analysis the tomographic perfusion pattern of combined periinfarctional and distant redistribution revealed a sensitivity of 85% and a specificity of 78% for the detection of significant collateral circulation in this group of patients. Thus, using the exhausted flow reserve as a diagnostic tool, vasodilation-thallium-201 tomography has the potential to identify and quantitate collateralized myocardium in post-infarction patients and may guide diagnostic and therapeutic decision-making.

Cardiac Catheterization↗

PubMed1990

Syncope in hypertrophic cardiomyopathy: multivariate analysis of prognostic determinants.

Twenty-nine consecutive patients with symptomatic hypertrophic cardiomyopathy and a mean age of 44.8 +/- 12.2 years (range 21 to 63) underwent complex invasive and noninvasive testing to identify a risk profile for syncope. Clinical, morphologic, electrophysiologic and hemodynamic variables at rest and at a symptom-limited pacing rate were analyzed for a significant association with syncope. Exact stepwise logistic regression analysis identified three variables as significant independent predictors of syncope in hypertrophic cardiomyopathy: 1) age less than 30 years (beta = 4.803; p = 0.0007); 2) left ventricular end-diastolic volume index less than 60 ml/m2 (beta = 3.302; p = 0.006); and 3) nonsustained ventricular tachycardia on 72 h ambulatory electrocardiographic monitoring (beta = 2.5909; p = 0.03). The combined occurrence of all three variables had a sensitivity and specificity of 100% in identifying eight patients with syncopal events. Thus, the risk for syncope in hypertrophic cardiomyopathy is high in young patients with the combination of low left ventricular filling volume and episodes of nonsustained ventricular tachycardia. This finding might also explain the mechanism of syncope in hypertrophic cardiomyopathy as low input-low output failure induced by a sudden increase in heart rate in the presence of a low filling volume.

Adult↗

PubMed1990

[Computed tomographic differential diagnosis of primary pelvic osteo-, chondro- and Ewing's sarcomas].

The value of CT for the differential diagnosis of primary malignant tumours in the pelvis was investigated in the case of three types of tumour: osteosarcomas, chondrosarcomas and Ewing's sarcomas. A total of 78 CT examinations in 29 patients was used. The results show that CT, using suitable techniques (high resolution etc.) constitutes a valuable diagnostic method for differentiating these bone tumours. This applies not only for the localisation of the tumour and for defining its extent, but also for showing the morphology of intra- and extra-osseous soft tissue components and their patterns of calcification. It is possible to recognise patterns of growth and of tissue destruction that are typical of individual tumours.

Bone Neoplasms↗

PubMed1990

[A comparison of digital luminescence radiography and the conventional film-screen technic in pulmonary coin lesions--a clinical study].

The aim of this investigation is the evaluation of DLR for the radiological diagnosis of intrapulmonary coin lesions. For this, a DLR system was used which had been specially developed for chest radiography. Early results were unsatisfactory and therefore specific image parameters were developed. The scope for dose reduction was also investigated. Oncology patients were examined by DLR and by our reference system. Results show that DLR is better than conventional images if edge enhancement is carried out, using the specific parameters. The superiority of the optimised digital images is apparent particularly in those portions of the lung that are obscured by the cardiac or diaphragmatic shadows. Because of image noise, a dose reduction of only 28% is possible, compared with our reference system.

Evaluation Studies as Topic↗

PubMed1990

[MRT of acute soft tissue hematomas at 1.5 T: animal experimental results].

In 16 Göttingen minipigs 31 soft-tissue haematomas of different location were produced by reinjection of freshly drawn arterial and venous blood. Immediately after the injection, MRI of the haematomas was performed and continued for 2-3 h. The MRI appearance of the haematomas depended on the site of the injection. Intramuscular haematomas demonstrated on T2-weighted gradient-echo images a decrease in signal intensity within a few minutes after injection. With the same scan parameters, subcutaneous haematomas had a high signal intensity still at 3 h after injection. When section of the cadaver was performed, the subcutaneous haematomas consisted of compact clot, whereas with intramuscular injection diffuse infiltration of the muscle was present.

Acute Disease↗

PubMed1990

[Magnetic resonance tomographic diagnosis of retrobulbar neuritis using inversion recovery sequences].

Inversion recovery sequences with short inversion periods (STIR sequences) are particularly suitable for the examination of the intra-orbital and intracanalicular portion of the optic nerve, since they selectively suppress interference from neighbouring fat. This technique makes possible direct demonstration of retrobulbar neuritis that had to be diagnosed exclusively by clinical criteria up to now. As evidence of inflammatory changes in 15 out of 18 patients with acute retrobulbar neuritis, there were areas of increased signal intensity in the affected nerve; in six cases the nerve was also swollen. In eight normals and five patients with healed retrobulbar neuritis, the signal and calibre of the optic nerves were normal.

Adult↗

PubMed1990

[MR of acute aortic dissection].

Acute aortic dissection is an emergency which requires a fast and reliable diagnosis. We performed MRI in 9 cases of acute aortic dissection. The information obtained with MRI is described and compared to the results of 2-dimensional echocardiography and contrast enhanced CT.

Aortic Dissection↗

PubMed1990

Assessment of post-infarction jeopardized myocardium by vasodilation--thallium-201 tomography: impact on risk stratification.

For the purpose of risk stratification 80 consecutive patients (mean age 58 +/- 7 years) with a chest pain syndrome after documented myocardial infarction underwent tomographic vasodilation-redistribution thallium-201 perfusion imaging, using 0.56 mg kg-1 intravenous dipyridamole. Tomograms were analysed for size and location of reversible and fixed perfusion defects and correlated to angiographic characteristics, left ventricular ejection fraction and wall motion, collateral status and 1-year prognosis, as measured by cardiac events within 12 months. No serious side-effects were noted with the diagnostic use of intravenous dipyridamole. According to the perfusion pattern three subgroups of post-infarction patients were identified: (1) by ischaemia at a distance with redistribution in non-infarct related territories (n = 48); (2) by peri-infarctional ischaemia with redistribution in the territory of the 'infarct artery' (n = 9); and (3) by exclusively fixed defects without redistribution (n = 23). Ischaemia at a distance was associated with a larger reversible defect than peri-infarctional ischaemia (P less than 0.05) and the pattern without redistribution (P less than 0.005); the fixed defect size, however, was similar in all three subgroups. In addition, the severity of coronary artery disease (Gensini score and number of diseased vessels) and the degree of collateralization was higher in the presence of a redistribution pattern (P less than 0.05), although no significant differences in global and regional function were noted as a function of thallium-201 redistribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

[Dipyridamole-thallium 201 tomography following acute myocardial infarct: significance for stratifying cardiac risk factors].

For the purpose of risk stratification 80 consecutive patients (mean age 58 +/- 7) with a chest pain syndrome after documented myocardial infarction underwent tomographic vasodilation-redistribution thallium-201 perfusion imaging, using 0.56 mg/kg intravenous dipyridamole. Tomograms were analyzed for size and location of reversible and fixed perfusion defects and correlated to angiographic characteristics, left ventricular ejection fraction and wall motion, collateral status, and 1-year prognosis as measured by cardiac events within 14 +/- 3 months. No serious side effects were noted with the diagnostic use of intravenous dipyridamole. According to the perfusion pattern three subgroups of post-infarction patients were identified: 1) by ischemia at a distance with redistribution in non-infarct related territories (n = 48), 2) by peri-infarctional ischemia with redistribution in the territory of the "infarct artery" (n = 9), and 3) by exclusively fixed defects without redistribution (n = 23). Ischemia at a distance was associated with a larger reversible defect than peri-infarctional ischemia (p less than 0.05) and the pattern without redistribution (p less than 0.005); the fixed defect size, however, was similar in all three subgroups. In addition, the severity of coronary artery disease (Gensini score and number of diseased vessels) and the degree of collateralization was higher in presence of a redistribution pattern (p less than 0.05), although no significant differences in global and regional function were noted as a function of thallium-201 redistribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗