Biomedical subjects

M Reiser

Publications and source records attributed to M Reiser.

At least 199 records · Page 11Linked to original sources

PubMed2000

[MR angiography of the supraaortic vessels].

PURPOSE: To compare high resolution contrast-enhanced MR angiography (MRA) and digital subtraction angiography (DSA) in the assessment of supraaortic vessel stenosis. METHODS: 14 patients with suspicion of cerebrovascular disease or upper limb ischemia underwent selective DSA and high resolution contrast enhanced MRA employing a new Panoramic-Array coil. Stenosis assessment in comparison to DSA followed NASCET criteria. Additionally signal-/noise ratios (SNR) were evaluated to assess contrast enhancement. RESULTS: Diagnostic image quality was achieved in all patients. Sensitivity and specificity for assessing high-grade stenosis of the supraaortic vessels were 100% and 96% respectively. In the assessment of high-grade common or internal carotid artery stenosis sensitivity and specificity was 100%. CONCLUSION: High resolution contrast enhanced supraaortic MRA combined with new coil systems allow for a reliable assessment of stenoses along the whole vessel course including the aortic arch. Previous stent procedures limit its use in postinterventional follow-up.

Adult↗

PubMed2000

[Stenoses and occlusions of the supraaortic vessels--the interdisciplinary interventional treatment of patients with an increased surgical risk].

PURPOSE: The value of elective PTA in stenoses of the supraaortic vessels and especially of the carotid artery is still under discussion. Stenoses after surgical and/or radiation therapy and a high cardio-vascular risk for a surgical procedure, however, justify minimal-invasive techniques. MATERIAL AND METHODS: In 31 patients with 24 symptomatic and 7 asymptomatic stenoses of the supraaortic arteries (3 Acc, 19 Aci, 5 Ascl, 4 Tr.brc, 2 Aax) minimal-invasive angioplasty and stent-placement was performed. The rationale for the interventional procedure was an elevated medical or technical risk of the respective surgical procedure. All procedures were performed using a coaxial technique with a guiding catheter. An open vascular access was necessary in 7 cases due to an unfavorable anatomical situation. RESULTS: The technical success rate was 100%. Peri-interventionally, a TIA occurred in 2 patients (1 spontaneous relieve, 1 complete remission after rt-PA lysis therapy). During the mean follow-up period of 13 months 3 patients died due to non-cerebrovascular reasons. In 2 patients a moderate restenosis, in 1 a high-grade stenosis, and in 1 and complete occlusion occurred without symptoms. After one year of follow-up, all treated stenoses were patent with a restenosis rate of 10.7% without further neurological symptoms. CONCLUSION: Interventional angioplasty with stent-placement of the supraaortic arteries is a safe and effective alternative in patients are at high risk for classical surgical procedures.

Adult↗

PubMed2000

[Reconstructive endovascular treatment procedures in the area of the a. subclavia and its branches].

PURPOSE: Principles, methods and results of percutaneous therapy in acute and chronic vascular alterations of the subclavian artery and its branches. MATERIAL AND METHODS: 17 arteries in 15 patients have been treated. The patients suffered from stenoses (n = 6), occlusions (n = 7), aneurysms, (n = 2) or acute hemorrhage (n = 2). The lesions were located in the subclavian artery (n = 8), the axillary artery (n = 4) or the vertebral artery (n = 5). In all cases the procedures were performed via via a transfemoral approach. Balloon angioplasty was employed in 13 cases, in 6 cases bare stents and in 4 cases grafted stents were implanted. In one case additionally local lysis was performed. RESULTS: Primary technical success was achieved in all cases. No catheter complications did occur. In 13 Patients complete follow-up examinations could be performed. The life-threatening acute hemorrhages were stopped without recurrent bleeding. The aneurysms could be completely excluded without endoleaks. In 4 Patients of the stenosis-group re-stenosis occurred and following stent-implantation one occlusion after 6 months was observed. 8 patients are without clinical symptoms since the intervention. CONCLUSION: Stenotic and occlusive vascular alterations as well as aneurysms and the acute hemorrhage in supraaortic arteries can be effectively and safely treated by endovascular techniques using percutaneous groin access.

Adult↗

PubMed2000

[The diagnosis of metastases in the bone marrow by MRT].

MRI plays an important role in the diagnostic workup of skeletal metastases. In principle two different applications of MRI can be distinguished: apart from the well known indications of clarifying uncertain lesions seen with other imaging modalities or demonstrating known osseous lesions with high resolution imaging for therapeutic planing, MRI can also be used as a primary screening modality for skeletal metastases. Besides the higher lesion detection rate the major advantage of MRI compared to bone scintigraphy lies in the demonstration of morphology which on the one hand exactly shows the extension of tumorous lesions and on the other hand clearly distinguishes between malign and benign processes. As unclear findings on bone scintigraphy often require additional imaging studies, especially in patients with clinical findings or lab results suggestive for metastatic disease, we think that whole-body-skeletal-MRI is not only an accurate but also a cost effective diagnostic modality in the detection and screening for skeletal metastases, if the indication for the examination is closely related to clinical findings and the therapeutic relevance of the imaging results.

Bone Marrow↗

PubMed2000

[Preoperative marking and biopsy of nonpalpable breast lesions with a guidance system for the open Magnetom].

PURPOSE: MRI-guided interventional maneuvers in the breast, when closed MRI scanners are employed are relatively complex and time consuming. The purpose of our investigations was to develop a special device for the localization and biopsy of breast lesions using an open low-field MRI Scanner (Magnetom Open, Siemens, Erlangen, Germany) permitting free access to the patient. MATERIALS AND METHODS: Due to its particular material and construction characteristics, a newly developed device for localization and biopsy of breast lesions is appropriate to remain within the magnetic field during the examination without degrading image quality. We performed 125 tests in a phantom and 31 investigations in patients including 26 wire-localizations and 5 biopsies. RESULTS: The interventional maneuvers in the phantom could be performed very precisely. In all 125 phantom studies, the needle (14 G coaxial biopsy cannula, Bard) was positioned close to the simulated lesion. In 25 out of 26 patients the needle was positioned within a distance less than 5 mm from the lesion. When using the 14 G coaxial biopsy cannula (Bard, Karlsruhe, Germany) the needle tip was found adjacent next to the lesion in all 12 cases (7 wire-localizations, 5 biopsies). CONCLUSIONS: Our results indicate that our device allows very precise preoperative localization of breast lesions within the Magnetom Open. Using MRI-compatible, large-core needles, biopsy under direct MRI control resulted in good results.

Aged↗

PubMed2000

Effect of superparamagnetic iron oxide on bone marrow.

The goal of this study was to compare the effects of SPIO particles on the signal intensity of the bone marrow of the vertebra spine in patients with and without liver cirrhosis. Forty-eight patients with normal liver tissue and 56 patients with liver cirrhosis were examined before and after intravenous SPIO administration, using a 1.5-T system (Magnetom Vision, Siemens, Erlangen, Germany) with a semiflexible cp-array coil. Three different pulse sequences were applied: a T1-weighted gradient-echo sequence, a T2-weighted fast spin-echo sequence with spectral fat suppression and a T2*-weighted gradient-echo sequence. The signal-to-noise ratio (SNR) of the liver, vertebra bone and paraspinal muscle were obtained. The SNR value change in each patient group and the SNR value difference between the two groups were evaluated. For assessment of statistical significance, Student's t-test with a level of p < 0.05 was applied. No significant differences in the SNR values of the liver and bone marrow between the two groups could be seen with any of the three sequences precontrast. Using the T1-weighted gradient-echo sequence in the noncirrhotic liver group, pre- and postcontrast comparisons of the SNR values of the liver and bone marrow indicated a decrease of approximately -44.3% (p = 0.02) and increase of approximately 15.3% (p = 0.04), respectively. No significant change was seen in the cirrhotic liver group. With the T2-weighted fast spin-echo sequence, a significant decrease of the SNR value of the liver and the bone marrow in both groups was seen. With the T2*-weighted gradient-echo sequence, the signal intensity decrease of the normal liver tissue was approximately -65.6% (p = 0.00), in cirrhotic liver tissue the decrease was -29.9% (p = 0.02). The SNR values of the bone marrow showed a decrease of -27.8% (p = 0.04) in the noncirrhotic liver group, whereas in the cirrhotic liver group it was only -11.3% and statistically not significant. The effect of SPIO particles on the liver and bone marrow is significantly less in patients with liver cirrhosis.

Adult↗

PubMed2000

Electrical impedance measurement of the breast: effect of hormonal changes associated with the menstrual cycle.

The purpose of this study was to evaluate the influence of hormonal factors on electrical impedance measurement with a new device TS2000, which is a new method in diagnosis of breast disease. Twenty-one healthy pre-menopausal women volunteers (aged 24-39 years) were examined with the TS2000 once/week for two menstrual cycles. On average, at least one spot was present in 47% of images of women not taking oral contraceptives and in 44% of women taking oral contraceptives (OC). The number of spots varied over the menstrual cycle and had a maximum in week 3 and week 5. We found that after 1 week only 15% of spots were present and no spots persisted for three consecutive weeks. These data, if further supported by observations on other populations of women, show that false-positive results are common in pre-menopausal women; however, these false-positive spots do not persist for long periods of time. This information may provide a basis for discrimination between true-positive and false-positive spots on the TS2000 image, since the latter would be expected to disappear on short-term follow up.

Adult↗

PubMed2000

Musculoskeletal MR: knee.

Magnetic resonance imaging is the most sensitive, specific, and accurate noninvasive method for diagnosing internal derangement of the knee. During the past 15 years knowledge of pathologic conditions of the knee had evolved significantly. Beyond the basic principles of imaging knee injuries great impact was made on the understanding of indirect or collateral findings, even in rare diseases. In this article the spectrum of disorders of the knee are reviewed and an overview of the current literature is given. This includes considerations about how to achieve a high-standard MR imaging study of the knee, and principles of imaging anterior cruciate ligament and meniscal tears. A focus is put on distinct diseases including intra-articular and intraosseous ganglion cysts, iliotibial band friction syndrome, transient osteoporosis, osteonecrosis, osteochondritis dissecans, and imaging of the articular cartilage.

Anterior Cruciate Ligament Injuries↗

PubMed2000

Precision of tibial cartilage morphometry with a coronal water-excitation MR sequence.

The aim of this study was to analyze the precision of tibial cartilage morphometry, by using a fast, coronal water-excitation sequence with high spatial resolution, to compare the reproducibility of 3D thickness vs volume estimates, and to test the technique in patients with severe osteoarthritis. The tibiae of 8 healthy volunteers and 3 patients selected for total knee arthroplasty were imaged repeatedly with a water-excitation sequence (image time 6 h 19 min, resolution 1.2 x 0.31 x 0.31 mm(3)), with the knee being repositioned between each replicate acquisition. After 3D reconstruction, the cartilage volume, the mean, and the maximal tibial cartilage thickness were determined by 3D Euclidean distance transformation. In the volunteers, the precision of the volume measurements was 2.3 % (CV%) in the medial and 2.6 % in the lateral tibia. The reproducibility of the mean cartilage thickness was similar (2.6 and 2.5 %, respectively), and that of the maximal thickness lower (6.5 and 4.4 %). The patients showed a considerable reduction in volume and thickness, the precision being comparable with that in the volunteers. We find that, using a new imaging protocol and computational algorithm, it is possible to determine tibial cartilage morphometry with high precision in healthy individuals as well as in patients with osteoarthritis.

Adult↗

PubMed2000

Signal changes in liver and spleen after Endorem administration in patients with and without liver cirrhosis.

The goal of this study was compare the effect of Endorem on the signal intensity of the spleen in patients with normal liver tissue and in patients with liver cirrhosis. Thirty patients with normal liver tissue and 47 with liver cirrhosis were examined before and after i.v. Endorem administration. The patients were examined with a 1.5-T magnet system (Magnetom Vision) using a semiflexible cp-array coil. Three different pulse sequences were used: a T1-weighted gradient-echo sequence, a T2-weighted fast spin-echo sequence with spectral fat suppression, and a T2*-weighted gradient-echo sequence. The signal-to-noise ratios (SNRs) of two areas of the liver and spleen were determined. The mean SNRs of the liver and spleen in patients with and without liver cirrhosis were compared. For assessment of statistical significance, the t-test at a level of P < 0.05 was applied. After i.v. administration of Endorem, no differences were seen with the T1-weighted gradient-echo sequence for the liver and spleen and, with the T2-weighted fast spin-echo sequence, no differences were found for the spleen. Significant differences between both groups were seen for the liver with the T2-weighted fast spin-echo sequence. The SNR in the noncirrhotic liver group was 57.4% lower than the SNR in the cirrhotic liver group. With the T2*-weighted gradient-echo sequence, the SNRs of the liver and spleen in the noncirrhotic liver group, compared with the cirrhotic liver group, were 126.8% and 45.6% less, respectively. The effect of Endorem on the liver in patients with Child C-stage liver cirrhosis was 32.1% less than in patients with Child B-stage liver cirrhosis. Likewise, the Endorem effect on the spleen was 27.1% less in patients with Child C-stage compared with Child B-stage liver cirrhosis. Hepatic and splenic uptake of Endorem is significantly decreased in patients with liver cirrhosis.

Adult↗

PubMed2000

Transferability of workload measurements between three different types of ergometer.

The aim of this study was to test the transferability of workload measurements between three different types of bicycle ergometer. Two common ergometers (Lode Excalibur and Avantronic Cyclus 2) were compared with a powermeter (Schoberer SRM system) that enables the measurement of power output during road cycling. Twelve well-trained subjects participated in this study. Within 12 h, each subject carried out three separate graded incremental exercise tests on each of the ergometric devices, and their oxygen uptake (VO2) and heart rate were determined. The three test protocols were identical: after warm-up, four stages of 4 min each at exercise intensities of 100, 150, 200, and 250 W. Pedalling frequency was controlled and there was no difference between the three ergometers. Tests were administered in a random order. Neither VO2 nor heart rate was affected by the type of ergometer used. For a given intensity, the same values were found in the two laboratory tests and in the field test (VO2: P = 0.425; heart rate: P = 0.845). Thus, the transferability of workload measurements between two different laboratory cycling ergometers and an ambulatory device was proven. Equivalency was determined using VO2 and heart rate as indices of metabolic and cardiovascular strain, respectively.

Adult↗

PubMed2000

Influence of nitric oxide synthase activity on amino acid concentration in the quinolinate lesioned rat striatum: a microdialysis and histochemical study.

The influence of nitric oxide synthase (NOS) activity on the KCl-evoked amino acid concentrations was investigated by in vivo microdialysis in the striatum in a rat model of excitotoxic lesion. Basal microdialysate levels of amino acids decreased during the quinolinic acid-induced neurodegeneration process, except for glutamine that increased initially and returned to control values 30 days after quinolinic acid exposure. KCl-evoked increase of extracellular amino acid concentration was reduced due to NOS activity in the striatum of both controls and lesioned animals, except for 120 days after quinolinic acid injection. These changes of amino acid concentrations in microdialysates correlated with the known biochemistry of the consecutive domineered cell types during the lesion process as revealed by histochemistry for NOS, NADPH-diaphorase, GFAP and isolectin B4. The present data provide direct evidence that NOS activity can modulate extracellular amino acid concentrations in the striatum not only under physiological conditions, but also during a pharmacologically induced lesion process and, thus, suggests that nitric oxide affects neurodegeneration via this pathway.

Amino Acids↗

PubMed2000

Patellar cartilage deformation in vivo after static versus dynamic loading.

The objective of this study was to test the hypothesis that static loading (squatting at a 90 degrees angle) and dynamic loading (30 deep knee bends) cause different extents and patterns of patellar cartilage deformation in vivo. The two activities were selected because they imply different types of joint loading and reflect a realistic and appropriate range of strenuous activity. Twelve healthy volunteers were examined and the volume and thickness of the patellar cartilage determined before and from 90 to 320s after loading, using a water excitation gradient echo MR sequence and a three-dimensional (3D) distance transformation algorithm. Following knee bends, we observed a residual reduction of the patellar cartilage volume (-5.9+/-2.1%; p<0.01) and of the maximal cartilage thickness (-2.8+/-2.6%), the maximal deformation occurring in the superior lateral and the medial patellar facet. Following squatting, the change of patellar cartilage volume was -4.7+/-1.6% (p<0.01) and that of the maximal cartilage thickness -4.9+/-1.4% (p<0.01), the maximal deformation being recorded in the central aspect of the lateral patellar facet. The volume changes were significantly lower after squatting than after knee bends (p<0.05), but the maximal thickness changes higher (p<0.05). The results obtained in this study can serve to validate computer models of joint load transfer, to guide experiments on the mechanical regulation of chondrocyte biosynthesis, and to estimate the magnitude of deformation to be encountered by tissue-engineered cartilage within its target environment.

Adult↗

PubMed2000

Glenohumeral translation during active and passive elevation of the shoulder - a 3D open-MRI study.

Despite its importance for the understanding of joint mechanics in healthy subjects and patients, there has been no three-dimensional (3D) in vivo data on the translation of the humeral head relative to the glenoid during abduction under controlled mechanical loading. The objective was therefore to analyze humeral head translation during passive and active elevation by applying an open MR technique and 3D digital postprocessing methods. Fifteen healthy volunteers were examined with an open MR system at different abduction positions under muscular relaxation (30-150 degrees of abduction) and during activity of shoulder muscles (60-120 degrees ). After segmentation and 3D reconstruction, the center of mass of the glenoid and the midpoint of the humeral head were determined and their relative position calculated. During passive elevation, the humeral head translated inferiorly from +1.58mm at 30 degrees to +0. 36mm at 150 degrees of abduction, and posteriorly from +1.55mm at 30 degrees to -0.07mm at 150 degrees of abduction. Muscular activity brought about significant changes in glenohumeral translation, the humeral head being in a more inferior position and more centered, particularly at 90 and 120 degrees of abduction (p<0.01). In anterior/posterior direction the humeral head was more centered at 60 and 90 degrees of abduction during muscle activity. The data demonstrate the importance of neuromuscular control in providing joint stability. The technique developed can also be used for investigating the effect of muscle dysfunction and their relevance on the mechanics of the shoulder joint.

Biomechanical Phenomena↗

PubMed2000

Induction of cell proliferation arrest and apoptosis in hepatoma cells through adenoviral-mediated transfer of p53 gene.

BACKGROUND/AIM: Loss of p53 function is common in hepatocellular carcinoma and is associated with an extremely poor prognosis. The aim of the study was to evaluate the biologic effect of adenoviral-mediated gene transfer of wild-type p53 gene in four hepatoma cell lines with different p53 genetic makeup. METHODS: Recombinant adenovirus expressing wild-type p53 was used. Recombinant adenoviruses with either an empty expression cassette or expressing beta-galactosidase gene served as controls. RESULTS: High-level expression of wild-type p53 was achieved with adenoviral-mediated gene transfer. The expressed p53 protein showed nuclear localization and its expression was associated with an induction of p21 and bax expression. Expression of the p53 gene was associated with inhibition of tumor cell proliferation and induction of apoptosis. Expression of p53 was also associated with an upregulation of CD95 (Apo-1/Fas) gene expression, which may predispose the tumor cells to undergo apoptosis induced by the Fas Ligand/Fas cytolytic pathway. An additional anti-tumor effect, in terms of allowing the replication-defective adenovirus to replicate, was observed in hepatoma cells with homozygous deletion of p53 genes and to a lesser extent, hepatoma cells with mutated p53 genes. CONCLUSIONS: These data showed that adenoviral-mediated gene transfer is effective in delivering p53 gene to tumor cells, and the multiple pathways involved in their antitumor activities.

Adenoviridae↗

PubMed2000

Successful treatment of chronic Budd-Chiari syndrome with a transjugular intrahepatic portosystemic shunt.

Budd-Chiari syndrome is characterized by obstruction of the hepatic venous outflow tract. Therapeutic options for chronic Budd-Chiari syndrome are limited. We report the case of a 28-year-old woman who presented with recurrence of chronic Budd-Chiari syndrome with total obstruction of all major hepatic veins. Due to worsening liver function over the course of 1 year, she had to be listed for liver transplantation. Because of therapy-refractory ascites, declining renal function and severe esophageal varices, a transjugular intrahepatic portosystemic shunt (TIPS) was placed, planned as a bridge to transplantation. Following TIPS, a marked recovery of liver function could be observed, accompanied by disappearance of ascites, esophageal varices, and normalization of kidney function. Therefore, the patient could be removed from the waiting list for liver transplantation. This case demonstrates for the first time that the use of TIPS in chronic Budd-Chiari syndrome may result in marked recovery of liver function.

Adult↗

PubMed2000

Magnetic resonance imaging (MRI) controlled outcome of side effects caused by ionizing radiation, treated with 780 nm-diode laser -- preliminary results.

BACKGROUND AND OBJECTIVE: Ionizing radiation therapy by way of various beams such as electron, photon and neutron is an established method in tumor treatment. The side effects caused by this treatment such as ulcer, painful mastitis and delay of wound healing are well known, too. Biomodulation by low level laser therapy (LLLT) has become popular as a therapeutic modality for the acceleration of wound healing and the treatment of inflammation. Evidence for this kind of application, however, is not fully understood yet. This study intends to demonstrate the response of biomodulative laser treatment on the side effects caused by ionizing radiation by means of magnetic resonance imaging (MRI). STUDY DESIGN/PATIENTS AND METHODS: Six female patients suffering from painful mastitis after breast ionizing irradiation and one man suffering from radiogenic ulcer were treated with lambda=780 nm diode laser irradiation at a fluence rate of 5 J/cm2. LLLT was performed for a period of 4-6 weeks (mean sessions: 25 per patient, range 19-35). The tissue response was determined by means of MRI after laser treatment in comparison to MRI prior to the beginning of the LLLT. RESULTS: All patients showed complete clinical remission. The time-dependent contrast enhancement curve obtained by the evaluation of MR images demonstrated a significant decrease of enhancement features typical for inflammation in the affected area. CONCLUSION: Biomodulation by LLLT seems to be a promising treatment modality for side effects induced by ionizing radiation.

Adult↗

PubMed2000

Effects of 780 nm diode laser irradiation on blood microcirculation: preliminary findings on time-dependent T1-weighted contrast-enhanced magnetic resonance imaging (MRI).

Laser therapy by low light doses shows promising results in the modulation of some cell functions. Various clinical studies indicate that laser therapy is a valuable method for pain treatment and the acceleration of wound healing. However, the mechanism behind it is still not completely understood. To explore the effect of a low-power diode laser (lambda = 780 nm) on normal skin tissue, time-dependent contrast enhancement has been determined by magnetic resonance imaging (MRI). In the examinations, six healthy volunteers (four male and two female) have been irradiated on their right planta pedis (sole of foot) with 5 J/cm2 at a fluence rate of 100 mW/cm2. T1-weighted magnetic resonance imaging is used to quantify the time-dependent local accumulation of Gadolinium-DPTA, its actual content in the local current blood volume as well as its distribution to the extracellular space. Images are obtained before and after the application of laser light. When laser light is applied the signal to noise ratio increases by more than 0.35 +/- 0.15 (range 0.23-0.63) after irradiation according to contrast-enhanced MRI. It can be observed that, after biomodulation with light of low energy and low power, wound healing improves and pain is reduced. This effect might be explained by an increased blood flow in this area. Therefore, the use of this kind of laser treatment might improve the outcome of other therapeutic modalities such as tumour ionizing radiation therapy and local chemotherapy.

Female↗