Biomedical subjects

R Bruening

Publications and source records attributed to R Bruening.

25 records · Page 2Linked to original sources

PubMed1998

Preoperative 3D-reconstructions of ultrafast-CT images for the planning of minimally invasive direct coronary artery bypass operation (MIDCAB).

BACKGROUND: The direct left internal mammary artery (LIMA) bypass to the left anterior descending (LAD) without the use of extracorporal circulation through a small anterolateral thoracotomy has become established among the minimally invasive techniques in cardiac surgery. Technical difficulties may occur in patients with an enlarged left ventricle and subsequent lateral positioning of the LAD, a small LAD, or a small LIMA. We used electron beam tomography (EBT) for preoperative visualization of the topographical structures to seek out patients with potential technical difficulties. METHODS: Eighteen patients, mean age 62 +/- 13 years, were entered in this study; in all cases the indication for revascularization was a significant stenosis of the LAD. Preoperatively an ECG-triggered EBT was performed. Following the image acquisition, a three-dimensional reconstruction of the data was performed. The LIMA, LAD, first diagonal branch, and chest wall were stained different colors for better visualization. Surgery was performed using a left anterolateral mini-thoracotomy and through this access, the LIMA was dissected and anastomosed using a stabilizer without the use of extracorporal circulation. RESULTS: In all but one of the 18 patients who had a preoperative EBT, the minimally invasive direct coronary artery bypass (MIDCAB) procedure was successfully performed using an anterolateral mini-thoracotomy. Based on the results of the EBT, the 5 centimeter incision was done parasternally in six patients, and more laterally (2-4 cm parasternally) in the other eleven cases. In 13 patients the access penetrated the fourth intercostal space; in four cases the fifth intercostal space was used. In one patient EBT revealed a very laterally positioned and diffusely arteriosclerotic LAD so the patient was operated using a median sternotomy, but without the use of extracorporal circulation. In all 18 patients the preoperatively acquired information of the anatomical topography was confirmed intraoperatively. One case without a preoperative EBT had to be converted to a conventional procedure due to a small, intramyocardial LAD and a very small LIMA. Postoperative angiography revealed patent LIMA grafts and uneventful anastomoses. CONCLUSIONS: For minimally invasive direct coronary artery bypass (MIDCAB) the topography of the LIMA, LAD and intercostal spaces is of major importance. Using the ECG-triggered EBT with subsequent three-dimensional reconstruction these relationships can be visualized. This enables an individual planning of the operation and a minimalization of the skin incision.

Aged↗

PubMed1997

Magnetic resonance imaging of the female pelvis. New circularly polarized body array coil versus standard body coil.

RATIONALE AND OBJECTIVES: The authors compare the value of a new circularly polarized body array coil (BAC) system with a standard body coil (BC) for high-resolution magnetic resonance imaging of the female pelvis. METHODS: Twenty patients with cervical cancer were examined with a BC and BAC. Imaging parameters were kept constant (sagittal T2-weighted turbo spin-echo: repetition time = 4000 mseconds; effective echo time = 99 mseconds; 160 x 160 mm field of view; 256 x 256 matrix; 0.63 x 0.63 mm pixel size; 4-mm slice thickness). Images were scored for lesion-to-organ delineation and overall image quality/ artifacts using a scale from 5 to 1 (excellent to poor). Signal-to-noise (S/N) ratios for different tissues (tumor, uterus, vagina, rectum, muscle, and fat) as well as contrast-to-noise (C/N) ratios between tumor and (1) uterus, (2) vagina, and (3) rectum were calculated. Magnetic resonance tumor staging was performed according to the International Federation of Gynecology and Obstetrics (FIGO) classification. RESULTS: Using the BAC, S/N and C/N ratios increased significantly compared with the BC (S/N: 2.7-3.4-fold increase for all organs evaluated, P < 0.001: C/N: tumor versus uterus 2.4-fold, P < 0.01; tumor versus vagina 6.1-fold, P < 0.001; tumor versus rectum 3.1-fold, P < 0.01). This resulted in an improved overall image quality (average ratings: BAC-4.3 points; BC-2.6 points; P < 0.001). Lesion-to-organ delineation (average ratings: BAC 4.3-4.1 points, BC 3.5-2.7 points for all organs evaluated; P < 0.001) was increased noticeably on BAC images. No significant difference was found for staging accuracy. CONCLUSIONS: Circularly polarized BAC provide superior S/N and C/N ratios and improve lesion conspicuity compared with standard BC.

Adult↗

PubMed1996

Echo-planar MR determination of relative cerebral blood volume in human brain tumors: T1 versus T2 weighting.

PURPOSE: Maps related to relative cerebral blood volume (rCBV) were generated with the use of the T1 effects produced by a low-dose bolus passage of gadopentetate dimeglumine. The T1 maps were evaluated in a tumor population and compared with rCBV maps obtained with T2-weighted measurements. METHODS: Imaging was performed in 19 patients with suspected intraaxial brain tumors. For the T1 rCBV maps, a low-dose bolus of contrast material was given during T1-weighted interleaved spin-echo echo-planar MR imaging. This was followed by a second injection during serial T2-weighted imaging for generation of the T2 rCBV maps. RESULTS: Among patients with low-grade lesions (n = 9), T1-based and T2-based rCBV maps showed comparably low rCBV in 7 subjects. In the other 2 patients, with confirmed tumor dedifferentiation, elevation of rCBV values was seen on maps obtained with both techniques. Among patients with high-grade tumors (n = 10), 4 had no evidence of recurrence and 6 did have tumor recurrence (confirmed by follow-up and positron emission tomography). In patients with the high-grade lesions exhibiting conventional contrast enhancement, lesions tended to have higher estimated values on T1 rCBV maps than on the T2 rCBV maps. CONCLUSION: Although the T1 rCBV maps showed less contrast as compared with the T2 rCBV maps, they provided diagnostic information that was comparable to the T2 rCBV maps in our series of 19 patients with primary brain tumors.

Adult↗

PubMed1990

The second riboflavin-binding myeloma IgG lambdaDOT. I. Biochemical and functional characterization.

A human monoclonal immunoglobulin, IgGDOT, with flavin-binding capacity has been obtained from an elderly woman with multiple myeloma who developed yellow skin and yellow hair. The case presented a remarkable similarity with that previously reported by Farhangi and Osserman [N. Engl. J. Med. 294, 177-183 (1976)]. Purified IgGDOT was bright yellow and the ligand was identified as riboflavin and its oxidation products by thin layer chromatography, proton nuclear magnetic resonance and mass spectroscopy. Competitive binding studies with different haptens demonstrated highest affinity for riboflavin, followed by flavin mononucleotide and flavin adenine dinucleotide; no significant binding was detected for several other non-flavin compounds tested. The hapten was associated with the protein in vivo, as well as with the purified antibody. Removal of the already bound riboflavin from the combining site was associated with irreversible denaturation of the monoclonal protein. By the fluorescence quenching technique it was determined that there were 0.68 available combining sites for riboflavin molecule in IgGDOT with a binding constant of 8.5 x 10(8)/M, while FabDOT presented 0.27 available combining sites with a binding constant of 5.1 x 10(8)/M. The fact that 1.2 and 0.81 mol riboflavin/mol protein were already bound to IgGDOT and FabDOT, respectively, is consistent with the usual hapten/antibody stoichiometry. The heavy chain subclass of IgGDOT was identified as gamma 2, as in the previously reported case of riboflavin-binding protein IgGGAR. However, the lambda chain subclass was different and no idiotype cross-reactivity was found.

Aged↗

PubMedDate not supplied

Regional relative blood volume MR maps of meningiomas before and after partial embolization.

PURPOSE: Our goal was to evaluate the role of relative blood volume (rBV) measurements in monitoring the embolization effect in meningiomas by using maps of susceptibility-weighted first pass MR data. METHOD: Eighteen examinations of nine patients before and following partial embolization were performed on a 1.5 T scanner. Embolization was achieved by injection of particles (45-150 microns). During dynamic imaging a bolus (0.2 mmol/kg) of gadopentetate dimeglumine was injected. RESULTS: The tumor rBV/gray matter rBV ratio was 3.11 +/- 1.40 for untreated tumors and 0.12 +/- 0.09 for successfully embolized tumors. The regional rBV in embolized meningiomas was significantly lower than that in untreated meningiomas (t test, p < 0.001). Vital tumor tissue showed positive enhancement in T1 and high rBV; nonvital tissue lacked T1 enhancement and bolus effect in the first pass, thus leading to low or missing rBV values. However, we also observed lack of bolus formation despite T1 enhancement (6/9 postembolization regions), possibly due to slow collateral flow. One of the patients treated with embolization bled during surgery. CONCLUSION: Maps of relative regional cerebral BV provide hemodynamic information in meningiomas and monitor the treatment effect of embolization in meningiomas more precisely than T1-weighted contrast-enhanced imaging.

Blood Loss, Surgical↗

PubMedDate not supplied

Xenon versus ceramics: a comparison of two CT X-ray detector systems.

PURPOSE: The purpose of this work was to compare image quality in phantom and patient CT scans acquired by xenon and ceramic CT detector systems. METHOD: High and low contrast resolution and image noise were determined with a standard CT phantom for both detector systems. In patient CT images, the effect on image noise was measured in anatomical regions of interest in the head, lumbar spine, chest, and abdomen. RESULTS: In phantom studies, image noise was significantly lower using ceramic versus xenon detectors. Also, in images of the head and lumbar spine, the signal-to-noise ratio was significantly higher with ceramic than with xenon detectors. In chest scans, ceramic significantly reduced beam-hardening artifacts caused by the thoracic spine. However, in abdominal images, the signal-to-noise ratio was not significantly different between ceramic and xenon detector systems. CONCLUSION: For reduced image noise in CT images of the head, lumbar spine, and chest and high resolution CT, ceramic detector systems appear to be superior to xenon detector systems.

Artifacts↗

PubMedDate not supplied

Intraprocedural thrombus formation during coil placement in ruptured intracranial aneurysms: treatment with systemic application of the glycoprotein IIb/IIIa antagonist tirofiban.

BACKGROUND AND PURPOSE: When using detachable coils to treat intracranial aneurysms, thromboembolism is the most feared and frequently reported complication during or after endovascular therapy. The purpose of this study was to document the therapeutic effect of tirofiban on patency of the parent vessel, rate of rebleedings, and outcome of the patients in the setting of acute subarachnoidal hemorrhage. METHODS: A patient data base was retrospectively reviewed to identify patients in whom thrombus occurred during endovascular treatment of ruptured cerebral aneurysms within a 34-month period and who were treated with tirofiban. All patients underwent anticoagulation with heparin during endovascular treatment procedures. Sixteen patients (age range, 52.9 +/- 10.7 years; 10 women, 6 men) were identified with intraprocedural thrombus formation. The patency of the parent vessel was assessed in a retrospective analysis blinded to outcome. Eight patients received ventriculostomy and had a follow-up CT. RESULTS: Local nonocclusive thrombus at the coil surface was detected in 5 patients, in all of whom the thrombus was dissolved. In 10 patients, partial or total occlusion of the parent vessel occurred during the intervention; in 8 of these, the vessel was recanalized completely and in 2 drug administration was assisted by mechanical means. In 1 patient, however, the occlusion persisted. No periprocedural rebleedings of the ruptured aneurysm occurred; 3 of 8 ventriculostomies had clinically silent small local bleedings. CONCLUSION: The use of tirofiban in the setting of endovascular treatment of ruptured intracranial aneurysms to dissolve platelet aggregation seems relatively safe and effective.

Adult↗