[What kind of medicine will we pay for?].
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Cost Control↗
Biomedical subjects
D Grönemeyer
Publications and source records attributed to D Grönemeyer.
Fetal heart rate variability and complexity in the course of pregnancy.
Aim of this study was the examination of fetal heart rate variability and complexity measures during pregnancy using fetal magnetocardiography. We registered 80 fetal magnetocardiograms in 19 healthy fetuses between the 16th and 41st week of gestation. On the basis of beat to beat intervals, mean RR interval (mRR), its standard deviation (SD), root mean square of successive differences (RMSSD), as well as complexity variables such as dimension (ApD1), entropy (ApEn), Lyapunov exponent (ApML) and trajectory divergence rate (p) were calculated for each recording. Dependency of these variables on gestational age was evaluated with correlation analysis. All variables changed consistently over time. RMSSD showed the strongest dependency on gestational age, followed closely by ApEn, SD and p. ApD1 and mRR showed only weak dependency. We conclude that magnetocardiography is well suited to register fetal cardiac activity with sufficient accuracy to permit detailed analysis of various heart rate variables during the second and third trimester of pregnancy. The observed increases in heart rate variability and complexity of fetuses most likely reflect differing but overlapping aspects of fetal development. They may be linked to the maturation of the autonomic nervous system and could aid in the timely identification of pathological conditions.
Adult↗
[Possibilities of spinal endoscopy within the scope of minimal invasive intervention--an experimental study].
The purpose of the present study was to evaluate, in vitro, a newly designed spinaloscope with a diameter of 1.8 mm, with integrated portals for instruments and irrigation. The 0 degree optical system has a resolution of 6,000 pixels. The instrument portals can be used for surgical lasers, biopsy forceps or burrs. We carried out our evaluations on fresh (unfixed) human lumbar spine specimens. The position of the endoscope was documented by CT scans. The endoscope was introduced into the spinal canal via the hiatus sacralis using a blunt trocar. The various structures and tissues were clearly identifiable and included the dura, the lig. flavum, the lig. long. posterior, spinal nerves, small pieces of disc material and various fibrous bands. The usefulness of the biopsy forceps was also shown.
Biopsy↗
Comparison of electron-beam computed tomography and intracoronary ultrasound in detecting calcified and noncalcified plaques in patients with acute coronary syndromes and no or minimal to moderate angiographic coronary artery disease.
We compared intracoronary ultrasound (ICUS) and electron-beam computed tomography (EBCT) on a coronary segmental basis in 40 consecutive patients with acute coronary syndromes and no or minimal to moderate angiographic disease (53+/-10 years; 34 men, 6 women). ICUS was used to define plaques, and EBCT was used to quantify coronary calcium (using a threshold of a CT density > 130 Hounsfield units in an area > 1.03 mm2). In a site-by-site analysis, coronary segments were defined as normal if both methods were negative, as containing noncalcified plaques if only ICUS was positive, and as containing calcified plaques if both methods were positive. A total of 222 coronary segments were analyzed (5.6+/-1.9 segments per patient). In 36 patients (90%), a total of 95 segments with plaques were identified, whereas in 4 patients (10%), only normal segments were seen. Of the 95 segments with plaques, 61 (64%) were calcified, and 34 (36%) were noncalcified. There was a linear relationship between the number of segments with calcified and with noncalcified plaques (r = 0.86, p <0.0001), but the mean relative frequency of segments with calcified plaques (55+/-38%) was highly variable. Calcium was found in 15 of 16 patients (93%) with 3 or more segments with plaques, while it was found in only 12 of 20 patients (60%) with one or 2 segments with plaques (p = 0.026). Younger age, higher low-density lipoprotein-cholesterol levels, diabetes, and active smoking predicted a higher relative frequency of segments with noncalcified plaques. Thus, in patients with acute coronary syndromes but no angiographically critical stenoses, there is a linear relationship between segments with calcified plaques versus segments with noncalcified plaques. However, while the mean ratio of these segments is close to 1:1, it is highly variable among individual patients.
Acute Disease↗
Tomographic microtherapy.
Minimally invasive techniques using endoscopes for image-guided therapy are now common in the field of surgery. Fast real-time radiologic imaging should be integrated into the procedure for increased safety in access and guidance techniques for endoscopes and instruments. The transparency of computed tomography (CT) guidance, magnetic resonance imaging, and electron beam tomography scan techniques allows precise guidance of instruments and endoscopes while permitting their diameter to be minimized. This guarantees safe and transparent access into the body, especially in high-risk areas such as the spine and brain. Combining both technologies has the potential to reduce complications and offers significant advantages in microinvasive operative procedures such as biopsies; local tumor therapy with lasers, radio frequency, or drugs; and percutaneous diskectomies or implants. CT is the golden standard for microtherapeutic procedures because of its precise tip discrimination.
Diagnostic Imaging↗
Measuring the effect of risk factors on coronary atherosclerosis: coronary calcium score versus angiographic disease severity.
OBJECTIVES: This study sought to determine whether noninvasive quantification of coronary calcium is comparable to selective coronary angiography in measuring the effect of cardiovascular risk factors on coronary atherosclerosis. BACKGROUND: Electron beam computed tomography (EBCT) allows the delineation of anatomic coronary atherosclerotic disease and may be useful for noninvasively defining the role of established and new cardiovascular risk factors in selected patient groups. METHODS: A total of 211 consecutive patients, 26 to 79 years old, referred for evaluation of suspected or recently diagnosed coronary artery disease were examined. Selective coronary angiography was used to define five angiographic disease categories: normal coronary arteries, nonobstructive disease and one-, two- or three-vessel disease. EBCT was used to calculate coronary calcium scores, and cardiovascular risk, including lipid variables and fibrinogen levels, was assessed. RESULTS: Coronary calcium score and angiographic disease severity categories were largely predicted by identical risk factors (i.e., age, male gender, total/high density lipoprotein cholesterol ratio, fibrinogen) and, to a lesser degree, hypertension. Only smoking predicted angiographic disease severity but not calcium scores. The risk factors together explained a comparable proportion of the variability in angiographic disease categories and in calcium score quintiles (33% vs. 41%, p=0.16 by bootstrap analysis). An overall risk score composed of these risk factors separated angiographic disease categories and calcium score quintiles with a similar area under the receiver operating characteristic curve ([mean+/-SE] 0.81+/-0.03 vs. 0.83+/-0.03, p=NS). CONCLUSIONS: Quantification of coronary calcium is comparable to selective coronary angiography in measuring the effect of established cardiovascular risk factors on coronary atherosclerosis. Thus, EBCT may be useful for the noninvasive evaluation of the relations between conventional or developing cardiovascular risk factors and coronary atherosclerosis.
Adult↗
Dynamic tracking in interventional MRI using wavelet-encoded gradient-echo sequences.
This work describes a newly developed magnetic resonance imaging (MRI) data-acquisition strategy which replaces the standard Fourier phase-encoding with the spatially localized coefficients of wavelet-encoding and offers a new technique for image guidance when combined with a dynamic tracking algorithm. By using this new technique, only a specific fraction of the entire raw data set needs to be updated and reconstructed to visualize the movement of an interventional device during an MR guided procedure. The combination of wavelet-encoding and a dynamic tracking algorithm was implemented in two-dimensional and three-dimensional gradient-echo sequences on a 0.2-T open C-arm-shaped MR system (Siemens, Erlangen Germany) and tested in phantom and in vitro experiments. When applying the wavelet-encoding direction parallel to the movement of a straight interventional device, only those spatially localized wavelet-coefficients mainly affected by the interventional device are updated. This led to potential increases of the image frame rate by a factor of up to seven.
Animals↗
Coronary artery calcium in acute coronary syndromes: a comparative study of electron-beam computed tomography, coronary angiography, and intracoronary ultrasound in survivors of acute myocardial infarction and unstable angina.
BACKGROUND: Quantification of coronary artery calcified plaques by electron-beam CT (EBCT) may predict cardiovascular events. However, whereas advanced coronary atherosclerotic plaques can be identified, mildly stenotic lipid-rich (soft) plaques may be difficult to detect. The value of EBCT in a subgroup of patients has therefore been questioned. To investigate this, we evaluated patients with acute coronary syndromes by EBCT and compared the results with coronary angiography and, in patients with an indeterminate angiogram, intracoronary ultrasound (ICUS). METHODS AND RESULTS: EBCT was performed in 118 consecutive patients (57+/-11 years of age) with previous myocardial infarction (n=101) or unstable angina (n=17). A standard protocol requiring a CT density >130 Hounsfield units in an area > or =1.03 mm2 was used for the definition of coronary artery calcium. We found that 110 patients had moderate to severe coronary artery disease by coronary angiography, and 8 had either mildly stenotic plaques at a single site (4 patients, confirmed by ICUS) or nonatherosclerotic causes of the unstable coronary syndrome (4 patients). One hundred and five of the 110 patients (96%) with moderate to severe angiographic disease but only 1 of the 8 other patients (13%) had a positive EBCT. Patients with acute coronary syndromes and negative EBCTs were significantly younger than patients with positive EBCTs (46+/-12 versus 58+/-10 years, P<.001), and a higher percentage was actively smoking (100% of the smokers versus 46%, P<.05). CONCLUSIONS: The vast majority of patients with acute coronary syndromes and at least moderate angiographic disease have identifiable coronary calcium by EBCT. Those patients with negative EBCTs have minimal or no atherosclerotic plaque formation. They are younger and tend to be active cigarette smokers.
Acute Disease↗
Technology and principles of tomographic image-guided interventions and surgery.
Image guidance of instruments can be performed by fluoroscopy, ultrasound imaging, computed tomography (CT), magnetic resonance imaging (MRI), and by stereotactic navigation. During the last year, there has been significant progress in MRI instrument guidance in the field of interventional radiology. Our first 168 clinical cases of MRI-guided interventional procedures, e.g., aspiration biopsy of neoplasms and tomographic microtherapy with local interstitial chemo-ablation, confirm the feasibility of MRI guidance. An expansion of MRI guidance during surgical endoscopic procedures is currently under evaluation and the initial results of this development are presented. Tomographic-guided surgery and the implementation of MRI or CT scanning within the environment of an operating room (OR) entail specific technological requirements and OR design considerations. Fast sequences, interventional protocols, in-room monitor, as well as MR-compatible probes, cannulae, catheters, instruments, endoscopes, and auxiliary equipment that are necessary for this combined surgical image-guided approach are described.
Endoscopes↗
[Fetal heart rate variability in pregnancy. Spectral analysis based on magnetocardiography].
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Cardiotocography↗
[Analysis of the complexity of fetal heart rate. Determining the dimension].
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Adult↗
Equipment configuration and procedures: preferences for interventional microtherapy.
Magnetic resonance imaging (MRI), computed tomography, and electron beam tomography scanners are built for radiologic diagnosis. With increasing frequency they are being used in the field of interventional Microtherapy to permit transparent visualization of the therapeutic field. Each of these scanners can be combined with endoscopy, fluoroscopy/digital subtraction angiography, and ultrasound units for hybrid imaging techniques as well as with therapeutic systems like lasers or radiofrequency. MRI affords 3D localization without x-ray exposure. Open access and keyhole imaging allow nearly real time guidance of instruments. Minimally invasive techniques using endoscopes and hybrid tomographic guidance result in improved tip tracking of microinstruments and reduced complications. This safer access into the body will lead to interdisciplinary cooperation with the potential for large cost reductions. This report summarizes our experience regarding which of the hybrid imaging suites is best suited for procedures including among others drug instillations, prosthesis (stent) implantation, or microoperations (endoscopic diskectomy/sequestrectomy), and physiological measurements simultaneously.
Diagnostic Imaging↗
Non-invasive assessment of coronary Palmaz-Schatz stents by contrast enhanced electron beam computed tomography.
UNLABELLED: The aim of the study was the evaluation of electron beam computed tomography as a non-invasive method to localize coronary stents and to document patency in stented vessel segments. METHODS: Twenty-two patients (16m/6f, 58 +/- 7.8 years) with coronary Palmaz-Schatz stents were examined. Contrast enhanced electron beam computed tomography using an Evolution scanner (Siemens) and coronary angiography were carried out within 7 days of each other. Stent localization was performed using the single-slice mode of the electron beam computed tomography scanner. Patency of the coronary target segment was assessed using the multi-slice mode after peripheral venous injection of a 40 ml bolus of contrast medium (Ultravist 370). Qualitative image analysis of a cine loop of 10 consecutive frames and quantitative analysis of densitometric curves in a region of interest distal to the stented vessel segment were performed. RESULTS: All stented vessel segments were identified. In 20 patients (91%), qualitative assessment of contrast enhancement patterns enabled stent patency to be evaluated. In 18 patients (90%), contrast medium was visualized distal to the stent. Quantitative coronary angiography confirmed that the stented vessel segments were not stenosed. Densitometric curves obtained in 16 of these 18 patients yielded contrast enhancement distal to the stented vessel segment of 63 +/- 6% compared to the aorta. In one patient, qualitative and quantitative analysis showed prolonged contrast enhancement of reduced density, which hinted at a stenosis related to the stented vessel segment. Coronary angiography revealed subtotal occlusion of the stented vessel directly distal to the stent. In another patient, no contrast visualization of the vessel distal to the stent was achieved. Coronary angiography revealed complete stent occlusion in this case. CONCLUSION: Electron beam computed tomography can reliably localize coronary stents and may become a useful tool for providing information on stented vessel segment patency.
Adult↗
Non-invasive visualization of coronary arteries with and without calcification by electron beam computed tomography.
Coronary artery disease (CAD) is one of the leading causes of mortality and morbidity in the western industrialized countries. Recent studies demonstrate the feasability of successful primary and secondary prevention. However, the detection of early stages of coronary artery disease is an unresolved issue. Whereas sensitivity and specificity of traditional risk factor assessment and stress tests are limited, the analysis of coronary calcification allows to obtain a direct sign of coronary atherosclerosis. This concept has been applied using fluoroscopy and conventional computed tomography (CT). However, the exact localization and quantification of coronary calcification only became possible with the advent of electron beam CT (EBCT). This new method showed a high prevalence of coronary calcification in the asymptomatic population. With the definition of a standardized "calcium score" the normal age-specific distribution and amount of coronary calcification was investigated. EBCT proved to be more sensitive in the diagnosis of both non-obstructive and obstructive coronary artery disease than risk factor analysis and stress testing, respectively. Obstructive coronary artery disease, however, cannot yet be predicted with high enough accuracy. A close correlation of EBCT coronary calcification was found to a) the total coronary plaque volume defined by histo-pathology, b) intracoronary ultrasound findings, c) the number of coronary risk factors, d) the coronary prognosis. Using EBCT, a reliable non-invasive identification of persons at risk was obtained for the first time. Guidelines for the use of EBCT in the early diagnosis and treatment of coronary artery disease are being developed.
Adult↗
[Electron beam tomography in coronary disease. Prevalence and distribution of coronary calcifications and their relationship with coronary risk factors in 650 patients].
OBJECTIVE: The extent of coronary calcification demonstrated by electron beam tomography was correlated with the individual cardiac risk profile. PATIENTS AND METHODS: The possible presence of coronary calcifications was studied by electron beam tomography (EBT) in 650 patients (526 men, 124 women; mean age 54 +/- 10 [28-81] years) with known or suspected coronary heart disease. Depending on the degree of density and the size of the lesion a score was calculated according to an international standard. RESULTS: No calcification was shown to be present in 202 patients (score of 0). A score of more than 0 was calculated in 73.8% of men and 48.4% of women. The average score was 227.8 +/- 24.8 in men, compared with 65.3 +/- 26.5 in women (P < 0.001). There were significantly more calcifications in older patients: Men aged 71-75 years had the highest score, 859.4, while the lowest, 9.6, was in those aged 36 to 40 years. The most important variables for the presence of calcification were age (relative risk per age group: 1.6), male sex (relative risk: 4.3), hypertension (relative risk: 2.4) and nicotine consumption (relative risk: 1.8). The median point score in patients without known risk factors was 1.3, with one known factor it was 7.2, and with three it was 48.0. The vessel segment most affected with calcification was the anterior interventricular branch with an average score of 84. CONCLUSION: Together with an evaluation of the risk profile EBT provided a better assessment of individual risk than conventional examination.
Adult↗
[Microinvasive, CT-controlled periradicular therapy in treatment of chronic intervertebral disk-induced functional disorders].
The disease of the spinal column is number 2 of common diseases world-wide and leads to high business- and commerce-related losses as well as to high expenses for the health care systems. An effective treatment of this disease is given by the microinvasive. CT controlled periradicular therapy (micro PRT). Under visibility, the tip of a canula is led directly and high precisely in close neighbourhood to the prolaps, then locally NaCl and cristaline cortisone (40 mg Volon A) is instillated. The periradicular distribution and the distribution into the epidural space is documented via contrast medium. A retrospective study with 220 patients and a prospective randomized double blind study with 40 patients (10 mg vs. 40 mg Volon A) were carried out. The average age of the retrospective collective was 53.1 +/- 12.4 years, average treatment period 18.4 weeks, and the mean follow-up 17 months. The mean value of successful treatment of lumbal spine was at 60% (spine 88.5%) with protrusion, with prolaps at 75% (spine 94%), with sequester at 94%, and with stenoses at 69% (spine 60%). With 78.8% of the patients, the percentual result was constantly good at the time of questionnaire as to the end of the treatment. 7.7% still took analgesics, 5.9% were post-operated. 1.8% of the patients made a pension application. The average age of patients within the prospective randomized double-blind-study was 47.2 +/- 11.9 years. At 27.5% of the patients, the start of pain was about more than 5 years ago and goes back to about 23 years (72.5% had pain more than 1 year). The mean value of visits was 4 physicians per patient, and 5 months of follow-up. There is a high significant improvement in results within the group with 40 mg Volon A (p = 0.0351479). The entire improvement, subjectively estimated (visual analogical scale) within this group was at 90%. After end of therapy, 83.3% (n = 30) had stopped the taking of analgesics and the neurologic deficit decreased significantly. Furthermore, significant reduction of prolapses could be observed at 60% of the patients in both study groups (n = 156). The CT scopic micro PRT with 40 mg Volon A leads to a significant improvement of pain and neurologic symptoms caused by chronical disk herniation.
Adult↗
[Noninvasive evaluation of the patency of coronary vessel stents using electron beam tomography segment images with administration of contrast media].
The implantation of intracoronary stents is increasingly employed in interventional cardiology. Even with high-resolution x-ray equipment the tiny struts of stainless steel stents can usually not be visualized. Coronary angiography is required to prove stent patency, and correct localization and deployment of the stent can only be assessed with intravascular ultrasound. In this setting a non-invasive diagnostic method would be of great advantage to document patency of the stented vessel segment. Herein we describe two patients with stent implantation in whom contrast-medium-enhanced electron beam tomographic scanning was applied to check for vessel patency. A pathological finding with reduced contrast enhancement could be distinguished from a normal finding, as was confirmed subsequently as a highly obstructed and a patent stented vessel segment by angiography. Thus, for the first time an alternative non-invasive diagnostic method may provide information on patency of stented vessel segments and may be useful for sequential follow-up investigations.
Angina Pectoris↗
How reliable is lumbar nerve root sheath infiltration?
To determine the reliability of lumbar nerve root sheath infiltration, a prospective study was performed. Ninety-four patients were randomized into three groups. In the first group of 33 patients, 0.5 cc of dye (Telebrix N, 30 g) was applied at nerve root L4, in the second group of 30 patients, 1.0 cc, and in the third group of 31 patients, 2.0 cc. The infiltration was guided by computer tomography. The diffusion of the dye was documented with computed tomography of the affected segment L4-5. The images were evaluated by an unbiased observer. The results showed that in the first group the dye diffused to the adjacent ipsilateral nerve roots L3 and/or L5 in nine patients. In the second and third groups this diffusion was seen in 9 and 11 patients, respectively. A diffusion into the psoas muscle was documented in 4, 10 and 22 patients, respectively. These latter differences were statistically significant (P < 0.01). Diffusion into the psoas muscle is especially important because the nerve roots converge in this muscle to become a plexus, and they are no longer surrounded by their dural sheaths. Diagnostic lumbar nerve root sheath infiltration should be performed by an experienced examiner. To guarantee high reliability, the tip of the needle should be placed as near as possible to the affected nerve root. The amount of local anaesthetic should be as small as possible, 0.5 cc or preferably less.
Anesthetics, Local↗