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K W Sievers

Publications and source records attributed to K W Sievers.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Differential diagnostic evaluation of a dysfunctional kidney transplant by magnetic resonance tomography].

Immediate diagnosis of rejection is essential for the prognosis of a renal transplant. To differentiate between rejection and acute tubular necrosis, 48 examinations (31 patients) were evaluated by Magnetic Resonance Imagining and Duplex Doppler ultrasound, and compared to the clinical outcome and histology. Sensitivity of MRI and Duplex Doppler was 82% (14/17), specificity was 77% (24/31) and 84% (26/31), respectively. Even when the results of both methods matched well, due to the extensive financial and technical efforts MRI may only be used as an additional tool for diagnosis.

Adult↗
PubMed1994

[High-resolution 3-D imaging in MR tomographic knee joint diagnosis. Correlation with arthroscopy].

84 knee joints were examined by a 3-dimensional MR method and the results correlated with subsequent arthroscopy. The findings showed good demonstration of the normal anatomical structures and excellent reliability for the diagnosis of meniscus tears (sensitivity 91%, specificity 95%), cruciate ligament lesions (sensitivity 90%, specificity 99%) and serious cartilage damage (sensitivity 100%, specificity 100%). Demonstration of mild cartilage damage (sensitivity 60%, specificity 99%) was better than with a spin echo technique but is not yet optimal. It is concluded that, by using a 3-dimensional technique, time-consuming spin echo sequences can be abandoned. Significant advantages of the 3-D method are the speed of the examination, narrow section thickness, marked flexibility in contrast rendering and the ability for multiplanar reconstruction.

Adolescent↗
PubMed1994

[Primary diagnosis and follow-up after thoracic trauma and lung contusion].

In 212 patients after injury of the thorax (54 males, 158 females; penetrating (15), blunt (197), multiple trauma (128)) 158 cases demonstrated rib fractures and 103 radiological proven pneumo- or hematothoraces or sometimes both, 108 of 138 had to be drained. 96.5% of the effusions and 98% of the pneumothoraces were clinical confirmed. 93.5% of 97 pulmonary contusions (79 unilateral, 18 bilateral) were detected by bronchoscopy within 10 h, 72% by x-ray. Caused by anatomical problems or for additional diagnosis 4 patients underwent thoracic CT. During ICU treatment 31 patients developed septic complications without detection in x-ray studies. In CT (n = 64) we found: 5 empyema, 13 pleural effusions, 4 pneumothoraces, 4 pneumocysts, 72 condensations of a lobe. After CT we performed: 9 resections of the lower lobe, 1 pneumectomy, 1 decortication, 7 thoracotomies with drainage, 8 drainages. To detect a septic focus under treatment the CT proved being an important diagnostic tool in chest trauma and lung contusion.

Adult↗
PubMed1994

[Color velocity imaging for diagnosis in kidney transplants. Methods for interpretation of color coding].

Colour velocity imaging is a new technique in the field of colour-coded sonographic flow measurement. It measures blood flow directly by analysing ultrasound pulses' running time and has advantages over colour Doppler systems. Colour velocity imaging's colour code detects changes in arterial blood flow. Therefore it can be used in the diagnosis of kidney allografts in the same way as duplex ultrasound. Using the presented methods of colour interpretation, sensitivity of 66.6-100% and specificity of 72.7-91.7% are attained. Thus colour velocity imaging combines the attributes of duplex ultrasound and colour Doppler ultrasound.

Blood Flow Velocity↗
PubMed1994

[Flow time analysis in sonographic flow measurements: an in vitro measurement for testing their accuracy].

Flow-time analysis is a new technique for colour coded sonographic flow measurements. The measurements depend on a pattern of ultrasound pulses and have some significant advantages compared with Doppler procedures. The accuracy of the method and possible sources of error have been studied under experimental conditions. Measurements on continuous blood flow showed a correlation of r > 0.99 for duplex sonography and of r > 0.93 for flow-time analysis. For this method, the colour coding parameters must be optimal in order to achieve high accuracy. Under these conditions quantitative measurement of pulsatile flow also becomes possible during colour mode.

Color↗
PubMed1994

["Triggered magnetic resonance tomography". A new procedure for imaging soft tissue movement in dysphagia (initial results)].

In addition to obstruction of the upper digestive pathway caused by foreign bodies, tumors or a diverticula dysfunction of the pharyngeal muscles is one of the main reasons for dysphagia. To complement functional examinations of swallowing disorders, an imaging system is required that has high-time resolution and allows adequate soft tissue visualization. To save this problem a new imaging system is introduced: "triggered" magnetic resonance imaging for visualization of soft tissue movement in patients with dysphagia. First results are presented and explained.

Deglutition Disorders↗
PubMed1993

[Duplex ultrasound evaluation of Basedow struma treated with iodine therapy].

Over a period of 18 months the thyroid gland of 31 patients suffering from Grave's disease was examined by Duplex ultrasound for changes in blood perfusion. In 24 of these patients a follow-up study was achieved immediately after a presurgical iodine therapy. For estimation of the perfusion the "Pulsatile Flow Index (PFI)" was calculated. Compared to the normal group (22 volunteers, mean: 0.46 +/- 0.11) changes of 41 and 22% were highly significant for this pre (mean: 0.65 +/- 0.08, p < 10E-6) and post therapy (0.56 +/- 0.1, p < 5E-5). Therapy was unsuccessful in 3 cases on a single, in one case on both sides. Altogether PFI yielded semiquantitative information on blood perfusion of the gland as well as on the rate of success.

Adolescent↗
PubMed1993

[The value of dynamic MRT in the perfusion evaluation of pelvic tumors under hyperthermia].

For the purpose of assessing perfusion of deep seated pelvic tumours 22 dynamic MR studies were carried out and correlated with relevant CT studies as well as with the intratumoural distribution of temperature under hyperthermia in different areas. Using changes of signal intensity, dynamic MR could thus distinguish between well and poorly perfused tumours, besides supplying reliable information on inhomogeneities in tumour perfusion. Altogether, a correlation of 0.92 (p < 0.001) was found between MR and CT and 0.72 (p < 0.001) between MR and the steady state determination of intratumoural temperature. Thus, dynamic MR provides prognostic information concerning therapeutic temperatures (> = 42 degrees C) in tumours and therefore their response to hyperthermia.

Chemotherapy, Cancer, Regional Perfusion↗
PubMed1993

Changes of soft-tissue water examined with magnetic resonance and electrical impedance tomography: an in vivo experiment.

The purpose of this study was the examination of short-term changes in soft-tissue water under in vivo conditions. In 12 healthy volunteers the water distribution of a selected slice of the lower limb was examined after change of position and rapid infusion of 0.9% saline solution. Two methods were used for data acquisition: magnetic resonance imaging (MRI) (Repetition Time (TR) = 1600 msec, Inversion Time (TI) = 300 msec, Echo Time (TE) = 22 msec) and electrical impedance tomography (EIT). In orthostatic equilibrium all 12 volunteers demonstrated changes of MR signal intensity and resistivity in the range of 12% and 7%, respectively. After infusion, mean changes of signal intensity and resistivity were 7% and 4%, respectively. The overall correlation of MRI and EIT was -0.96 (p < 0.001). Results indicate that inversion recovery sequences are a sensitive method of detecting in vivo changes of water distribution in selected areas of the body.

Adult↗
PubMed1992

[Diagnostic aspects of isolated sphenoid sinusitis].

The clinical occurrence of isolated sphenoid sinusitis is rare. Due to a long history and few initial symptoms, diagnosis of this potentially fatal infections can be difficult. Radiological aspects in 10 patients are presented (e.g. type and design of examination and whether inflammatory or destructive changes could be shown), as well as clinical aspects (cranial nerve palsy, concurrent inflammation, duration of disease and therapy). CT proved to be superior in diagnosing the extent of any bony changes, while MRI was more useful in detecting inflammation.

Adolescent↗
PubMed1991

[Computerized tomography in persisting stapedial artery].

About 30 cases of a persistent stapedial artery have been described in the literature so far. It is usually associated with other malformations, suggesting an inhibition of normal embryonic development. For the first time, it was possible to demonstrate this using high-resolution computed tomography.

Adult↗
PubMed1990

[The pulsatile flow index (PFI) in the diagnosis of dysfunctional kidney transplants].

In 61 patients (167 examinations) the pulsatile flow index (PFI) was used to diagnose the cause of renal transplant dysfunction. The results were correlated with histology and clinical course and outcome, angiography or quantitative radionuclide renography. Renal transplant rejection was diagnosed by PFI with a sensitivity of 85%. The specificity was 81% and the diagnostic accuracy 83%. The positive predictive value was found to be 76%, whereas the negative predictive value was 89%. In presence of acute tubular necrosis (ATN) the PFI was normal in 89% of examinations and therefore distinguishable from acute rejection.

Adolescent↗
PubMed1989

Duplex Doppler ultrasound in determination of renal artery stenosis.

Twenty-six cases of renal artery stenosis were evaluated with Doppler ultrasound using the pulsatile flow index (PFI). To establish normal values, the PFI in 60 renal arteries in 30 healthy volunteers was obtained. Normal values by PFI ranged between 0.48 and 0.71 (mean +/- SD: 0.6 +/- 0.06). In renal artery stenosis the PFI range was 0.72-0.79. The normal upper limit was 0.71. The PFI failed in three patients; however, an ultrasound examination showed secondary renal disease (two patients with stenosis on both sides with a shrunken kidney on one side, and one patient with hypernephroma on the opposite side). The PFI was normal (14 of 14 patients) in patients without angiographic evidence of stenosis or after successful dilatation.

Humans↗
PubMed1989

Pulsatile flow index for qualitative measurements of blood flow with duplex ultrasound. An experimental study.

We determined the accuracy of Doppler blood flow measurements in an experimental investigation using a tissue-simulating phantom, pulsatile flow pumps and heparinized blood. A new index for qualitative assessment of blood flow, the pulsed flow index (PFI) is described. The PFI takes advantage of the area under the flow velocity curve between the true zero line and the diastolic baseline. Under conditions of continuous flow, the PFI ranged from 0.82 to 0.94 (mean value 0.90). The PFI was found to be relatively independent of the transducer/vessel angle (+/- 8%) and the inter/intra-operator variation was small (+/- 7.5%, or +/- 7%, respectively).

Blood Flow Velocity↗