PubMed Health⌕ Search

Biomedical subjects

T Rupprecht

Publications and source records attributed to T Rupprecht.

At least 19 recordsLinked to original sources
PubMed2005

Ascending arterial blood flow velocities during cardiac diastole in critical care patients--a characteristic flow pattern with a bad prognosis.

AIM: Pulsed Doppler ultrasound is a standard noninvasive investigation to measure the velocity and pulsatility of blood flow within the major intracranial and organ-supplying arteries in critical care patients. The normal arterial flow pattern in organ-supplying vessels is characterised by a systolic-diastolic forward flow which is caused by the aortic "Windkessel" function and the low peripheral resistance of the parenchymatous organs. A variety of well known pathological conditions may cause a change of the vascular characteristics within the perfused organs which are diagnosed by the typical changes of the flow pattern in the supplying arteries. In the cardiac diastole, however, there is always a slow decrease of the flow velocity which is terminated by the onset of the following systole. METHOD AND RESULTS: We report on 11 patients investigated by Doppler ultrasound during their stay in our intensive care unit. All these patients presented a markedly different flow pattern measured in their intra- and/or extracerebral vessels. This very distinctive flow pattern is characterised by a diastolic ascent of the arterial flow velocity and is caused by an excessively increased venous pressure within the draining veins of the affected organs. All patients died due to (multiple) organ failure. CONCLUSION: It is of major importance to be aware of the rare but very characteristic flow pattern described here because of the poor prognosis associated with it.

Arteries↗
PubMed2002

Determination of the pressure gradient in children with coarctation of the aorta by low-field magnetic resonance imaging.

During the past few years magnetic resonance imaging (MRI) has gained increasing importance in the noninvasive examination of congenital heart defects. Practically all existing examinations have been carried out with a magnetic field strength exceeding 1 (T high-field MRI). Flow quantification is considered to be an advanced MRI application and, in the past, has been available for high-field systems only. Therefore until recently, functional examinations such as MRI tomographic flow quantification were reported exclusively for high-field MRI units. From December 1998 to December 1999, nine patients (five girls and four boys, mean age 130 plus minus 3.6 months, range 62-185 months) were investigated by means of MRI after a previous surgical repair or interventional balloon dilatation of a coarctation of the aorta (mean postinterventional time period 23 plus minus 0.4 months). The examination was carried out without sedation in an open low-field unit (Siemens Magnetom Open 0.2 T). Cardiac-triggered spin-echo sequences were used with a 3-mm to 7-mm slice thickness in an axial and a double oblique plane. The measurement of the immediate poststenotic flow velocity was done by flow-sensitive sequences developed for the study (phase-sensitive flow measurement sequences: TE, 6-12 msec; TR, 50 msec; flip angle, 60 degrees; Vmax, 200-1200 cm/sec; two acquisitions). All patients were examined on the same day with comparative echocardiographic procedures. In all cases, an excellent anatomical evaluation of the aortic arch was possible. The diameters of the residual stenosis were measured by MRI and correlated well r = 0.95; p ? 0.001; mean difference 0.44 +/- 2.47 mm) with echocardiographic results. No wall damage was observed in any of the cases studied. The pressure gradient of the stenosis calculated from the flow sequence was between 17 and 50 mmHg and corresponded well (r = 0.93; p = 0.001; mean difference 0.67 +/- 11 mmHg) with the results obtained from echocardiography. The study demonstrates that examination of the aortic arch is possible in a low-field MRI system, with its significant advantages (lower patient discomfort and more cost-effective examination). In addition, a quantitative flow measurement in low-field MRI was realized for the first time. Low-field MRI therefore seems to be a good, noninvasive method for examining patients with a poor echocardiographic representation of the aortic arch.

Adolescent↗
PubMed2002

[Prospective feasibility study of chest X-ray vs. thoracic MRI in breath-hold technique at an open low-field scanner].

PURPOSE: MR investigations using a breath-hold sequence at an open low-field MR had to be compared to chest X-rays in patients with a wide spectrum of cardio-thoracic pathologies. MATERIAL AND METHODS: 114 patients and three volunteers who actually received a chest X-ray due to different indications underwent triplanar breath-hold (17 - 20 s) True-FISP sequence using a 0.2 T low-field MR (Siemens Magnetom Open, TR/TE/alpha: 7.3/3.5/80 degrees, SD: 10 mm, Pixel: 2.81 x 1.41 mm) a mean of 5.1 (+/- 8.2) days later. RESULTS: Signal-to-noise ratio as basics for pattern recognition was 3.2 in nodule, 5.0 in infiltration, and 12.0 in effusion, and therefore True-FISP is usable for the detection of these findings. MRI demonstrated nodules (89 % vs. 57 %), infiltration (81 % vs. 71 %), pleural effusions (86 % vs. 75 %), pericardial effusions (100 % vs. 21 %) and pulmonary congestion (90 % vs. 80 %) clearly more frequently compared to chest X-ray. DISCUSSION: MRI of the lung has been implemented successfully at an open low-field MR system. Diagnostic safety and accuracy are at least comparable to those of chest X-ray. The lack of superimposition led to a major improvement in the detection of pericardial effusions and nodules, and an increase in identification of infiltration, pleural effusion, and pulmonary congestion.

Adolescent↗
PubMed2001

A fast magnetic resonance imaging technique for children with mediastinal lymphoma: work in progress.

BACKGROUND: Mediastinal lymphoma often presents as a large tumor at the time of diagnosis. Usually chest X-ray filming is the first imaging modality and it is used for routine follow-up during the course of the disease. A new and very fast MRI technique has been developed at our center as an alternative. Results in three patients with mediastinal lymphoma during a pilot study are promising. PROCEDURE: After diagnosis the above patients were additionally investigated in a 0.2 T low-field MR-scanner by a modified true FISP sequence (see text) with an acquisition time of 3.6-4.6 sec. Follow-up was performed by both, X-ray filming and MRI. After diagnosis the patients, again, had both X-ray filming and MRI investigation for follow-up: one patient 2, one patient 3, and one patient 5 times. Images were evaluated and compared by two pediatric radiologists. RESULTS: Total investigation times for radiography and MRI were comparable. The tumor was better visualized by MRI on seven of nine images and gave additional information about the structure and the localization of the tumor as well as concomitant problems such as pericardial effusion. CONCLUSIONS: True FISP MRI may prove to be a good alternative to X-ray filming in the diagnosis and follow-up of mediastinal lymphoma.

Adolescent↗
PubMed2001

[Low-field magnetic resonance tomography in pediatric radiology. Possibilities, limitations and prospects].

MRI has been used in pediatric imaging for several years. It provides excellent anatomic detail and tissue characterization combined with the advantage that it is not associated with the application of ionizing radiation to the radiation sensitive infant organism. Low field MRI provides some additional advantages like a lower rate of sedations, easier monitoring of sedated patients and the option of interventional examination and therapy. The disadvantages, however, are the slightly prolonged examination times and the lower signal-to-noise ratio compared to high-field MR scanners. In the future, new techniques using modern gradient echo sequences will provide fast imaging methods with a very high signal-to-noise ratio which could partially replace conventional x-ray imaging. In the presented article we report our experiences in low-field MR imaging of pediatric patients. The possibilities as well as the limitations of this imaging modality are pointed out.

Adolescent↗
PubMed2001

Low field thoracic MRI--a fast and radiation free routine imaging modality in children.

Radiography of the chest is the most frequently performed radiological examination in pediatric imaging. However, it is associated with the application of ionizing radiation. In order to avoid ionizing radiation in children a new and very fast MRI technique has been developed at our center as an alternative to the pediatric chest X-ray. 100 patients who had received a chest X-ray were additionally investigated in a 0.2 T low-field MR-scanner by a modified true FISP sequence with an acquisition time of 3.6-4.6 s for a coronal triple-slice scan. X-ray and MR images were independently evaluated and later compared by two pediatric radiologists. Total investigation times (door-to-door time) for X-ray and MRI were comparable. The signal-to-noise ratio for lung parenchyma was 4.6-7.3. Of 189 pathologic findings 165 were depicted on MR images as well as radiographs, 18 were noted on MRIs only, 6 on X-rays only. Overall kappa was 0.87. True FISP MRI may be a good alternative to conventional chest X-ray. The main advantages are: fast imaging free of ionizing radiation, easy performance, no need for special equipment, optional imaging in all 3 planes, good image quality, and a high diagnostic value.

Adolescent↗
PubMed2001

Impaired compliance of the intracranial vessels in complicated childhood migraine. Demonstration by transcranial Doppler-sonography--a vascular model approach.

AIM: To increase the diagnostic value of Doppler sonography a uniform lumped parameter model of pulsatile blood flow in human arteries was derived from the serial and/or parallel connection of parallel oscillatory circuits. METHODS AND PATIENTS: In this setting the current (I) in the ohmic resistor (R) represents the volume flow in the vessel, the voltage (V) the blood pressure. The vessel compliance corresponds to the capacitance (C), the inductivity (L) represents the accelerated mass. The flow velocity (v) which is assessable non-invasively is given by v = I/A, where A is the cross-sectional area of the vessel. Mathematically, the model represents a two-dimensional Fourier-series of the input signal by the segments. Thus it seems to be evident that almost all forms of flow and pressure pulses can be generated. The equations of the model were solved numerically. Doppler-sonographically measured flow velocities in the ascending aorta were used as input signal. The parameters for A, R, L and C were optimized to gain the measured flow spectrum in the target vessel as model response. RESULTS: Application in 14 children (aged 3-16 yrs.) with complicated migraine during a symptom-free interval revealed a significantly lowered cross sectional area of the middle cerebral artery on the side of the higher flow velocities. For both middle and posterior cerebral arteries, a decreased vessel compliance (C) (mean -30%) was found, whereas values for R and L were within normal limits. CONCLUSION: These findings suggest an altered vascular compliance even between attacks. This may contribute to the pathogenesis of migraine through increased cerebral impedance resulting in impaired cerebral perfusion.

Adolescent↗
PubMed2000

Laryngeal mucosa of head and neck cancer patients shows increased DNA damage as detected by single cell microgel electrophoresis.

Major risk factors for cancer of the oral cavity, pharynx and larynx are smoking and excess alcohol consumption. Since long-term survival rates of head and neck cancer patients have not substantially been improved, new preventive strategies including the use of cancer chemopreventive agents have to be developed. With the aim of developing biomarkers which can verify the efficacy of chemopreventive interventions, a standardised alkaline microgel electrophoresis (MGE) assay was applied as a sensitive and rapid tool to detect DNA damage on a single cell level. Macroscopically normal laryngeal mucosa biopsies obtained by surgery from head and neck cancer patients (n=29) and from hospital controls (n=22) were analysed by MGE in a pilot study. As compared to controls, cells from head and neck cancer patients showed a significantly elevated DNA damage without any further genotoxic treatment (P<0.01). We conclude that this increased background DNA damage in laryngeal epithelia could result from genetic alterations caused by smoking and alcohol leading, in accord with the field cancerisation hypothesis, to a gradual decrease of genomic stability and malignancy. MGE should now be explored as a rapid screening method in larger clinical studies: (i) to identify high-risk subjects carrying cells with decreased genomic stability and (ii) to verify the efficacy of chemopreventive regimens to prevent or slow down the development of head and neck cancer in high-risk persons.

Adult↗
PubMed2000

Sedation and monitoring of paediatric patients undergoing open low-field MRI.

UNLABELLED: The purpose of this study was to determine the need, effectiveness and safety of sedation and monitoring in infants and children in a paediatric open low-field MRI system. Of 274 patients (median age 9 y) examined, only 74 children (median age 25 mo) needed sedation. Sedation was achieved by intravenous administration of midazolam (0.2 mg/kg) and etomidate (0.2 mg/kg). Mean total doses required were 0.28 and 0.27 mgl/kg, respectively. With the exception of eight primarily ventilated patients, all children breathed spontaneously. O2 saturation, arterial blood pressure and ECG were monitored. The low resonance frequency of the MRI system required a specially designed high frequency (HF) shielding of the monitor system to avoid HF artifacts. The overall sedation rate was markedly lower (74/274 = 27%) compared to a control group previously examined in a closed high-field MRI system (52/111 = 47%). This was due to a significant lower need for sedation in patients aged up to 10 y (p < or = 0.0001) in the open MRI unit. General anaesthesia could be avoided in all patients. No significant movement artifacts occurred in any of the MRI examinations and no serious side effects were observed. CONCLUSIONS: MRI of children is easier in an open MRI system and with fewer sedations, as in closed high-field systems. Sedation by a combination of midazolam and etomidate is highly effective and safe. Monitoring devices for high-field systems may have to be modified for low-field systems. An in-house paediatric MRI unit with an open and special paediatric design is of major advantage for imaging paediatric patients.

Child↗
PubMed2000

Paravertebral and intraspinal malposition of transfemoral central venous catheters in newborns.

We report permanent tetraplegia in a newborn resulting from intraspinal malposition of a transfemoral catheter. In 2 other neonates paravertebral malposition of indwelling Silastic lines was detected. We suggest that left-sided transfemoral catheterization and conditions enhancing collateral flow through the vertebrolumbar pathway may predispose to inadvertent paravertebral catheter placement.

Catheterization, Central Venous↗
PubMed1998

Low-field magnetic resonance imaging of the pelvis in patients with anal dynamic graciloplasty: initial experience.

The aim of this study was to determine whether low-field magnetic resonance (MR) imaging can safely and accurately depict inflammatory changes in patients with anal dynamic graciloplasty, in whom high-field MR imaging is contraindicated and ultrasonography and computed tomography are inadequate. A 0.2-T field-strength MR examination was performed in six patients with anal dynamic graciloplasty malfunction in whom reoperation was contemplated. The following sequences were applied: T2-weighted turbo spinecho with fat saturation, T1-weighted conventional spin-echo, and contrast-enhanced T1-weighted conventional spin-echo with fat saturation. Results indicated that none of the patients experienced relevant discomfort, pacemaker malfunction, or electrode dislocation with low-field MR imaging. Inflammatory pelvic changes were visualized in four patients and atrophy of the transposed gracilis muscle in another. Surgery was thus avoided in the four, who underwent conservative treatment for their pelvic inflammation. It was concluded that these preliminary results demonstrate the feasibility of MR imaging with a low field strength in patients with anal dynamic graciloplasty. In such patients, in whom diagnostic imaging had been problematic, the potential for safe and accurate visualization will be a boon to treatment planning.

Adult↗
PubMed1998

Successful percutaneous transluminal angioplasty for treatment of renovascular hypertension in a 15-month-old child.

UNLABELLED: In young children with renal artery stenosis the applicability of percutaneous transluminal angioplasty is limited by the small vessel size. We report our experience in a 15-month-old girl with severe hypertension, who underwent successful balloon dilatation of a tight renal artery stenosis caused by fibromuscular dysplasia. The procedure was performed using the guided co-axial balloon catheter technique with a 6 F right coronary Judkins catheter, a 0.014" guidewire and a 2 mm coronary artery balloon dilatation catheter. Antihypertensive medication was discontinued 6 weeks after the procedure. During a follow up period of 11 months, Doppler sonography revealed no evidence of recurrent renal artery stenosis. CONCLUSION: Percutaneous transluminal angioplasty of renal artery stenosis can be performed safely in young children using equipment originally designed for treatment of coronary artery stenosis in adults.

Angioplasty, Balloon↗
PubMed1997

True fetal mosaicism of an isochromosome of the long arm of a chromosome 20: the dilemma persists.

We report the prenatal findings of mos 46,XY/46,XY,i(20q) after amniocentesis. The propositus presented with two epidermal scalp scars, retrobulbar orbital cysts, and dyssegmentation of the thoracic spine. The abnormal cell line was discovered in cells cultured from the proximal umbilical cord and--by fluorescence in situ hybridization (FISH)--in interphase nuclei from buccal epithelium and urinary sediment but not from the placenta, lymphocytes, or skin fibroblasts.

Adult↗