Biomedical subjects

S Göhde

Publications and source records attributed to S Göhde.

3 recordsLinked to original sources

PubMed2004

High spatial resolution whole-body MR angiography featuring parallel imaging: initial experience.

PURPOSE: To combine whole-body multi-station three-dimensional contrast enhanced magnetic resonance angiography (3D CE MRA) using a self-developed rolling table platform with parallel imaging strategies (PAT) in order to increase the spatial resolution of the 3D MRA data sets. MATERIALS AND METHODS: Whole-body multi-station MRA was performed with a rolling table platform (AngioSURF) on 5 volunteers in two imaging series: 1) standard imaging protocol, 2) modified high-resolution protocol employing PAT using the generalized autocalibrating partially parallel acquisitions (GRAPPA) algorithm with an acceleration factor of 3. For an intra-individual comparison of the two MR examinations, the arterial vasculature was divided into 30 segments. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were calculated for all 30 arterial segments of each subject. Vessel segment depiction was qualitatively assessed applying a 5-point scale to each of the segments. Image reconstruction times were recorded for the standard as well as the PAT protocol. RESULTS: Compared to the standard protocol, PAT allowed for increased spatial resolution through a 3-fold reduction in mean voxel size for each of the 5 stations. Mean SNR and CNR values over all specified vessel segments decreased by a factor of 1.58 and 1.56, respectively. Despite the reduced SNR and CNR, the depiction of all specified vessel segments increased in PAT images, reflecting the increased spatial resolution. Qualitative comparison of standard and PAT images showed an increase in vessel segment conspicuity with more detailed depiction of intramuscular arterial branches in all volunteers. The time for image data reconstruction of all 5 stations was significantly increased from about 10 minutes to 40 minutes when using the PAT acquisition. CONCLUSION: The implementation of PAT into the concept of whole-body MRA enabled to increase the spatial resolution in all examined territories, which resulted in more detailed MR angiograms.

Adult↗

PubMed2001

Diagnostic techniques in assessing vessels of the gastrointestinal tract.

Vascular disorders of the gastrointestinal tract include a variety of different underlying diseases, thus requiring different and, in many cases, more than one imaging procedure. Only a knowledge of the newest developments in vascular imaging techniques with all the possibilities and limits will ensure a time- and cost-effective, accurate and reliable diagnosis. In many acute cases and also as a screening procedure, ultrasound in combination with colour Doppler and duplex sonography, plays an important role in setting the right course for further imaging techniques, and can provide the correct diagnosis in many cases.Depending on the most prominent symptoms and the expected disease, the right choice of technique saves valuable time. Computed tomography (CT) and magnetic resonance imaging (MRI) are cross-sectional imaging techniques that not only demonstrate lesion vascularization, but also provide information about neighbouring structures and complications in an understandable and demonstrable way. The use of angiography as an invasive tool should be limited to cases where a high temporal and spatial resolution is necessary to make the diagnosis or where therapeutic interventions are also likely to be performed within the same setting. For the diagnosis of gastrointestinal vascular diseases, often no generally valid recommendation can be given, since the impact of all imaging techniques will depend on the examiner's experience, the technical equipment and on their 24-h availability in a hospital. This chapter tries to give some information about the inherent limits and indications of the different imaging techniques, as well as the newest study results concerning the most frequent vascular diseases of the gastrointestinal tract.

Angiography↗

PubMed1998

[Active instrumental guidance in interventional MR tomography: introduction to a new concept].

PURPOSE: An active MR-based guidance system for visualisation of invasive instruments is described. METHODS: The principle of MR tracking is based on the integration of a miniaturised coil into the tip of the instrument itself. A phantom experiment was designed to demonstrate the localising accuracy of this technique. In addition, biocompatibility and warming effects were evaluated. Preliminary intravascular applications that were performed in animal experiments under MR guidance included embolisation, vascular occlusion as well as transjugular intrahepatic punctures. Percutaneous biopsies, cholecystostomies and laparoscopic applications were also evaluated with MR tracking. RESULTS: Phantom experiments confirmed an excellent localisation accuracy of MR tracking compared top conventional radiography. At a field strength of 0.5 T, the temperature increase remained below 2 degrees C. Results of phantom experiments revealed a potential of significant heating dependent on the sequence parameters employed. MR tracking allowed a robust, simultaneously biplanar visualisation of the instrument tips in real time. Based on MR "road map" images, various intravascular and percutaneous interventions were successfully performed in vivo under MR guidance. CONCLUSIONS: MR tracking is a flexible concept permitting monitoring in the guidance of instruments in an MR environment. Various preliminary in vitro and in vivo experiments demonstrate safety, localisation accuracy and feasibility of this biplanar localisation technique in real time.

Biopsy, Needle↗