PubMed Health⌕ Search

Biomedical subjects

W Jaschke

Publications and source records attributed to W Jaschke.

At least 19 recordsLinked to original sources
PubMed2002

Diffusion-weighted MRI differentiates the Parkinson variant of multiple system atrophy from PD.

OBJECTIVE AND BACKGROUND: Routine MRI as well as MR volumetry and MRS have been shown to contribute to the differential diagnosis of the Parkinson variant of multiple system atrophy (MSA-P) and PD. However, it is currently unknown whether diffusion-weighted imaging (DWI) discriminates these disorders. METHODS: Ten patients with MSA-P (mean age, 64 years) were studied, 11 with PD (mean age, 64 years), and seven healthy volunteers (mean age, 59 years) matched for age and disease duration. Regional apparent diffusion coefficients (rADC) were determined in different brain regions including basal ganglia, gray matter, white matter, substantia nigra, and pons. RESULTS: Patients with MSA-P had higher putaminal rADC (median 0.791 x 10(3)/mm(2)/s) than both patients with PD (median 0.698 x 10(3)/mm(2)/s, p < 0.001) and healthy volunteers (median 0.727 x 10(3)/mm(2)/s, p < 0.001). There were no significant differences in putaminal rADC between patients with PD and healthy volunteers. Moreover, none of the putaminal rADC values in the PD and control group surpassed the lowest value in the MSA-P group. There were no significant group differences in the rADC values in other brain regions such as pons, substantia nigra, globus pallidus, caudate nucleus, thalamus, or gray and white matter. Putaminal rADC values correlated significantly with Unified PD Rating Scale OFF scores in patients with MSA as measured by the Spearman rank test. CONCLUSION: DWI, even if measured in the slice direction only, is able to discriminate MSA-P and both patients with PD and healthy volunteers on the basis of putaminal rADC values. The increased putaminal rADC values in Parkinson variant of multiple system atrophy are likely to reflect ongoing striatal degeneration, whereas most neuropathologic studies reveal intact striatum in PD. Diffusion-weighted imaging may represent a useful diagnostic tool that can provide additional support for a diagnosis of Parkinson variant of multiple system atrophy.

Aged↗
PubMed2001

Radiographic evaluation of cervical spine trauma. Plain radiography and conventional tomography versus computed tomography.

Different imaging modalities are available for the diagnosis of cervical spine injuries. There is a controversial discussion about whether plain radiography (PR), conventional tomography (CTO) or computed tomography (CT) should primarily be used. PR and CTO are more often available and less costly than CT. Especially in second-care hospitals, CT is not always available. The diagnostic work-up in these centres has to rely on conventional techniques. The aim of this study was to define the role of PR supplemented by CTO in the diagnosis of cervical spine trauma in comparison to CT. Twenty-five patients were identified who underwent plain radiography (PR), conventional tomography (CTO) and computed tomography (CT) for the diagnosis of a cervical fracture. In 19 patients a fracture of the cervical spine was identified. All images were reviewed by two independent observers to estimate the interobserver variability. The highest detection rate was achieved by CT (18/18 fractures detected for observer 1/2), followed by CTO (16/16 fractures) and then PR (15/14 fractures). When the detection rates of PR and CTO are combined, 18 fractures were detected by each of the observers. The results were analysed for the dens and the rest of the cervical spine independently. For PR and CTO the detection rates were lower for fractures of the dens than for the rest of the cervical spine. We conclude that the combination of PR and CTO accurately detects fractures of the cervical spine compared with CT. If a fracture of the dens is suspected, the patients should be referred to CT due to its superior accuracy in this region.

Adolescent↗
PubMed2001

[Color-coded doppler sonographic demonstration of intrahepatic venous collaterals in Budd-Chiari syndrome].

By means of colour Doppler ultrasound, veno-venous shunts were found in 3 cases, leading to the diagnosis of Budd-Chiari Syndrome. Pulsed and colour Doppler ultrasound showed a reduction in venous blood flow and the reversal of blood flow in the venous collaterals. Venous spectral Doppler wave forms in the veno-venous shunts were flattened and aphasic in all cases. Sonographic findings were confirmed by cavography. Our cases show that pulsed and colour Doppler ultrasound are a valuable tool in the initial diagnosis of veno-venous shunts associated with Budd-Chiari Syndrome.

Adult↗
PubMed2001

[Radiation exposure in single slice and multi-slice spiral CT (a phantom study)].

PURPOSE: The purpose of study was to compare patient dose applying singleslice- and multislice-spiral CT. METHODS: The examinations were performed with a singleslice-spiral CT (Highspeed Advantage; GE Medical Systems; Milwaukee, USA) and with a multislice CT systems (LightSpeed QX/i GE Medical Systems; Milwaukee, USA). For the determination of the radiation exposure (absorbed dose) a selection of most executed protocols (thorax-helical, abdomen-helical, petrous bone-axial, head-axial) were simulated using an Alderson Rando Phantom. The dose was determined by means of lithiumfluorid-thermoluminiscence dosimeters (TLD-GR 200). RESULTS: For thorax and abdomen protocols higher energy dose values could be found using a multislice CT. On the average the energy dose values were increased by 2.6 on an average in relation to single slice spiral CT. The energy dose values of the multisclice CT using head protocols could be reduced by 30% in relation to single slice spiral CT due to suitable parameter selections. The energy dose applying a petrous bone protocol resulted in an average increase by a factor 1.5 using a multislice CT. CONCLUSION: Using the new multislice CT technique protocol strategies must be optimized regarding the patient doses. Users can operate critically in the sense of the radiation protection only if they are aware of the occurring dose amounts to the patient.

Equipment Design↗
PubMed2001

[Simulation of the heart action: a computer controlled module for the generation of variable flow patterns].

AIM: The development of a computer controlled pump for the generation of variable flow patterns with high reproducibility for simulating the haemodynamics in physiological model circuits. MATERIAL AND METHODS: The module is controlled by an arbitrary function generator. The shape of the flow profile is generated on the PC based on mathematical functions or drawn by hand. The amplified signal drives a DC motor which is coupled magnetically to a geared pumphead. The lack of mechanical coupling ensures smooth running and a complete attenuation of motor vibrations as well as a disturbance-free flow profile. The spectra were analyzed by Doppler-sonography with a 5 - 12 MHz linear probe and with pressure sensors. Silicon tubes were used as simulated vessels and a water-glycerine mixture with particles of cellulose as simulated blood. RESULTS: The generated flow patterns (constant flow and multi-phase patterns) correlate highly with the measured pressure- and velocity profiles. CONCLUSION: The variability and high reproducibility of the flow profiles and the realtime control of the signal parameters make the simulation of dynamic processes and haemodynamic long-time studies feasible. The module developed facilitates detailed studies of high reproducibility with physiological and pathological flow models and with simulated blood.

Computer Simulation↗
PubMed2001

Comparative reject analysis in conventional film-screen and digital storage phosphor radiography.

The purpose of this work was to gather information about the benefits in patient care caused by the introduction of digital radiography. In particular, the possibility of reducing the number of image repeats and thus unnecessary patient radiation was sought. Waste films of conventional radiography were collected--in digital radiography each image delete command at the post-processing workstation was documented. Rejected images were analysed retrospectively. The overall reject rate was 27.6% in the conventional and 2.3% in the digital department. While in the conventional department the main reason for rejection was 'exposure' and 'others' (i.e. problems related to film handling), the main reason in the digital environment was 'positioning'. Reject analysis yields representative data about the current performance of a radiology department. A marked reduction of repeated X rays and consequently reduced radiation exposure of the patient was clearly shown in this study comparing two differently working radiology departments. This is one of several benefits of digital radiography in patient care.

Humans↗
PubMed2001

Comparison of low-contrast detail perception on storage phosphor radiographs and digital flat panel detector images.

A contrast detail analysis was performed to compare perception of low-contrast details on X-ray images derived from digital storage phosphor radiography and from a flat panel detector system based on a cesium iodide/amorphous silicon matrix. The CDRAD 2.0 phantom was used to perform a comparative contrast detail analysis of a clinical storage phosphor radiography system and an indirect type digital flat panel detector unit. Images were acquired at exposure levels comparable to film speeds of 50/100/200/400 and 800. Four observers evaluated a total of 50 films with respect to the threshold contrast for each detail size. The numbers of correctly identified objects were determined for all image subsets. The overall results show that low-contrast detail perception with digital flat panel detector images is better than with state of the art storage phosphor screens. This is especially true for the low-exposure setting, where a nearly 10% higher correct observation ratio is reached. Given its high detective quantum efficiency the digital flat panel technology based on the cesium iodide scintillator/amorphous silicon matrix is best suited for detection of low-contrast detail structures, which shows its high potential for clinical imaging.

Humans↗
PubMed2001

Massive progression of diffuse hepatic lymphangiomatosis after liver resection and rapid deterioration after liver transplantation.

Hepatic involvement is an exceptional presentation of lymphangiomatosis. In this case report we describe a patient who underwent liver transplantation secondary to progressive hepatic involvement, which occurred 2 yr after partial hepatectomy. Within 1 yr after liver transplantation the disease condition deteriorated, with rapid progression of pre-existing skeletal lesions and development of pulmonary disease. We conclude that liver transplantation may be a treatment option for hepatic lymphangiomatosis. In the presence of pre-existing extrahepatic lesions, however, liver transplantation seems to be contraindicated.

Adult↗
PubMed2001

Radial nerve palsy associated with humeral shaft fracture: evaluation with US--initial experience.

PURPOSE: To determine the feasibility of using ultrasonography (US) for evaluation of a radial nerve injury associated with humeral shaft fracture. MATERIALS AND METHODS: In a prospective study, 11 consecutive patients with sensorimotor radial deficiency after distal humeral fracture were evaluated with conventional radiography, US, electroneurography, and electromyography. Surgical repair of the fracture and nerve inspection were performed in five patients. The remaining six patients were successfully treated conservatively. The US appearance of the radial nerve was studied in 10 healthy volunteers and in the noninjured arm of the 11 patients for comparison. RESULTS: In five patients, US findings of a severely damaged radial nerve were confirmed at surgical nerve inspection. In one patient, the nerve was entrapped between fragments. One patient had a complete nerve dissection, one had a lacerated nerve from a loose compression plate, and one had a nerve riding on the edge of a bone fragment. In the fifth patient who underwent surgical inspection, the nerve was buried in the callus. In the six patients treated conservatively, US showed continuity of the nerve. CONCLUSION: US may be useful for accurate evaluation of the radial nerve in patients with nerve palsy associated with humeral shaft fracture.

Adult↗
PubMed2001

Psychophysical aspects in medical illumination techniques.

The relation between image and visual perception of the human eye is an important point in digital imaging systems. Research aims should therefore pay attention to psychophysical aspects. Optimising of digital imaging systems can only be reached if the important final steps in the diagnostic process--visual perception and signal detection--are taken into account.

Computer Terminals↗
PubMed2000

Virtual computed tomography colonoscopy: artifacts, image quality and radiation dose load in a cadaver study.

The purpose of our study was to evaluate the interdependency of spatial resolution, image reconstruction artifacts, and radiation doses in virtual CT colonoscopy by comparing various CT scanning protocols. A pig's colon with several artificial polypoid lesions was imaged after air insufflation with helical CT scanning using 1-, 3-, and 5-mm collimation, and pitch values varying from 1.0 to 3.0. Virtual endoscopic images and "fly through" sequences were calculated on a Sun Sparc 20 workstation (Navigator Software, GE Medical Systems, Milwaukee, Wis.). Several reconstruction artifacts as well as overall image quality were evaluated by three independent reviewers. In addition, radiation doses for the different CT protocols were measured as multiple-scan average dose using a 10-cm ion chamber and a standard Plexiglass body phantom. Generally, image quality and reconstruction artifacts were less affected by pitch values than by beam collimation. Thus, narrow beam collimation at higher pitch values (e. g. 3 mm/2.0) seems to be a reasonable compromise between quality of virtual endoscopic images and radiation dose load.

Animals↗
PubMed2000

Transjugular intrahepatic portosystemic shunt (TIPS) augments hyperinsulinemia in patients with cirrhosis.

BACKGROUND/AIMS: Cirrhosis of the liver is characterized by glucose intolerance and hyperinsulinemia. Both increased insulin secretion and decreased insulin clearance appear to contribute to hyperinsulinemia in cirrhotic patients. A decrease in hepatic insulin extraction rate may be due either to hepatocellular dysfunction or to portosystemic shunting with decreased first-pass insulin clearance. METHODS: To specifically address the contribution of portosystemic shunting to the pathogenesis of hyperinsulinemia in cirrhotic patients, we analyzed glycemic control and insulin levels in fasting serum in 23 cirrhotic patients before and after transjugular intrahepatic portosystemic shunt (TIPS). RESULTS: Compared to respective values in healthy controls, C-peptide, insulin and proinsulin concentrations at baseline were increased by 340%, 120% and by 100% in cirrhotic patients (all p<0.05). In cirrhotic patients insulin levels before TIPS averaged 104+/-73 pmol/l and increased by more than 50% to 163+/-118 pmol/l after TIPS (p<0.01), whereas levels of C-peptide and proinsulin showed no significant change. Glucose and fructosamin levels also remained unchanged after TIPS. CONCLUSION: Our data demonstrate that TIPS does not impair glycemic control in cirrhotic patients and that an increase in portosystemic shunting augments hyperinsulinemia, most likely by decreasing hepatic insulin clearance.

Ascites↗
PubMed2000

Color and pulsed Doppler ultrasound findings in normally functioning transjugular intrahepatic portosystemic shunts.

OBJECTIVE: To evaluate blood flow changes inside normally functioning transjugular intrahepatic portosystemic shunts (TIPS), using color Doppler ultrasound (CDUS) and pulsed Doppler ultrasound (PDUS). METHODS: A total of 72 patients (mean age 54, range 36-78 years) underwent TIPS placement, portal angiography, CDUS and PDUS examinations. Measurements inside the stent were taken at the portal side, at the central part and at the venous end of the TIPS. RESULTS: In well functioning TIPS the mean peak velocity (PV) on the portal side was 37 m/s (range 22-65 cm/s), in the area of the incoming intrahepatic portal branch the mean PV was 59 cm/s (range 40-95 cm/s) and at the side of the incoming hepatic vein the mean PV was 135 cm/s (range 88-220 cm/s). In the punctured hepatic and portal veins the mean PV was 25 cm/s (range 15-30 cm/s) and 18 cm/s (10-22 cm/s), respectively. The flow increase from the portal to the mid part (P less than or = 0.001) and to the venous side was statistically significant (P less than or = 0.001). CONCLUSION: A velocity gradient between the portal and the venous side of a TIPS is a normal finding caused by branches of the portal and hepatic vein joining the TIPS from the side and it is characteristic of a normally functioning TIPS.

Adult↗
PubMed2000

Head and neck tumors: fractionated frameless stereotactic interstitial brachytherapy-initial experience.

The authors used a frameless stereotactic navigation system, the Vogele-Bale-Hohner head holder, and a targeting device to reproducibly position brachytherapy needles for fractionated interstitial brachytherapy in 12 patients with inoperable cancers of the head and neck. In all cases, deviations of the needle relative to the planned position were within 1-15 mm depending on the location of the tumor.

Brachytherapy↗
PubMed2000

Computer-assisted neurosurgery by using a noninvasive vacuum-affixed dental cast that acts as a reference base: another step toward a unified approach in the treatment of brain tumors.

OBJECT: The purpose of the study was to evaluate the use of the Vogele-Bale-Hohner (VBH) mouthpiece, which is attached to the patient's upper jaw by negative pressure, for patient-image registration and for tracking the patient's head during image-guided neurosurgery. METHODS: A dynamic reference frame (DRF) is reproducibly mounted on the mouthpiece. Reference points, optimally distributed and attached to the mouthpiece, are used for registration in the patient's absence on the day before surgery. In the operating room, the mouthpiece and DRF are precisely repositioned using a vacuum, and the patient's anatomical structures are automatically registered to corresponding ones on the image. Experimental studies and clinical experiences in 10 patients confirmed repeated (rigid body) localization accuracy in the range of 0 to 2 mm, throughout the entire surgery despite movements by the patient. CONCLUSIONS: Because of its noninvasive, rigid, reliable, and reproducible connection to the patient's head, the VBH vacuum-affixed mouthpiece grants the registration device an accuracy comparable to invasive fiducial markers.

Adult↗
PubMed1999

Sophisticated hospital information system/radiology information system/picture archiving and communications system (PACS) integration in a large-scale traumatology PACS.

Picture archiving and communications system (PACS) in the context of an outpatient trauma care center asks for a high level of interaction between information systems to guarantee rapid image acquisition and distribution to the surgeon. During installation of the Innsbruck PACS, special aspects of traumatology had to be realized, such as imaging of unconscious patients without identification, and transferred to the electronic environment. Even with up-to-date PACS hardware and software, special solutions had to be developed in-house to tailor the PACS/hospital information system (HIS)/radiology information system (RIS) interface to the needs of radiologic and clinical users. An ongoing workflow evaluation is needed to realize the needs of radiologists and clinicians. These needs have to be realized within a commercially available PACS, whereby full integration of information systems may sometimes only be achieved by special in-house solutions.

Ambulatory Care Facilities↗
PubMed1999

Comparative reject analysis in conventional film-screen and digital storage phosphor radiography.

The aim of this study was comparative analysis of rejected radiographs in conventional and digital radiology under the aspects number of rejected images and reasons for rejection. During 2 months waste films of conventional radiography were collected; in digital radiography each image-delete command at the postprocessing workstation was documented. Rejected images were analysed and assigned to four categories. The overall reject rate was 27.6% in the conventional and 2.3% in the digital department. Whereas in the conventional department the main reason for rejection was "exposure" and "others" (i.e. problems related to film handling), the main reason in the digital environment was "positioning". The high exposure tolerance of digital systems markedly reduces the amount of faulty images. This is not only economically rewarding, but may also reduce unnecessary X-ray exposure of patients due to image retake.

Humans↗