Biomedical subjects

S Schaller

Publications and source records attributed to S Schaller.

At least 19 recordsLinked to original sources

PubMed2006

An update on biomarkers of bone turnover and their utility in biomedical research and clinical practice.

BACKGROUND: Maintenance of the structural and functional integrity of the skeleton is a critical function of a continuous remodeling driven by highly associated processes of bone resorption and synthetic activities driven by osteoclasts and osteoblasts, respectively. Acceleration of bone turnover, accompanied with a disruption of the coupling between these cellular activities, plays an established role in the pathogenesis of metabolic bone diseases, such as osteoporosis. During the past decades, major efforts have been dedicated to the development and clinical assessment of biochemical markers that can reflect the rate of bone turnover. Numerous studies have provided evidence that serum levels or urinary excretion of these biomarkers correlate with the rate of bone loss and fracture risk, proving them as useful tools for improving identification of high-risk patients. OBJECTIVE: The aim of the present review is to give an update on biomarkers of bone turnover and give an overview of their applications in epidemiological and clinical research. DISCUSSION: Special attention is given to their utility in clinical trials testing the efficacy of drugs for the treatment of osteoporosis and how they supplement bone mass measurements. Recent evidence suggests that biochemical markers may provide information on bone age that may have indirectly relates to bone quality; the latter is receiving increasing attention. A more targeted use of biomarkers could further optimize identification of high-risk patients, the process of drug discovery, and monitoring of the efficacy of osteoporosis treatment in clinical settings.

Biomarkers↗

PubMed2006

Calcitonin directly attenuates collagen type II degradation by inhibition of matrix metalloproteinase expression and activity in articular chondrocytes.

OBJECTIVE: Calcitonin was recently reported to counter progression of cartilage degradation in an experimental model of osteoarthritis, and the effects were primarily suggested to be mediated by inhibition of subchondral bone resorption. We investigated direct effects of calcitonin on chondrocytes by assessing expression of the receptor and pharmacological effects on collagen type II degradation under ex vivo and in vivo conditions. METHODS: Localization of the calcitonin receptor on articular chondrocytes was investigated by immunohistochemistry, and the expression by reverse transcriptase polymerase chain reaction (RT-PCR). In bovine articular cartilage explants, cartilage degradation was investigated by release of C-terminal telopeptides of collagen type II (CTX-II), induced by tumor necrosis factor-alpha (TNF-alpha) [20 ng/ml] and oncostatin M (OSM) [10 ng/ml], with salmon calcitonin [0.0001-1 microM]. In vivo, cartilage degradation was investigated in ovariectomized (OVX) rats administered with oral calcitonin [2 mg/kg calcitonin] for 9 weeks. RESULTS: The calcitonin receptor was identified in articular chondrocytes by immunohistochemistry and RT-PCR. Calcitonin concentration-dependently increased cAMP levels in isolated chondrocytes. Explants cultured with TNF-alpha and OSM showed a 100-fold increase in CTX-II release compared to vehicle-treated controls (P<0.001). The degradation of type II collagen in these explants was concentration-dependently inhibited by calcitonin, 65% protection at 10 nM calcitonin (P<0.01). TNF-alpha and OSM induced a pronounced increase in matrix metalloproteinase (MMP) activity, which was strongly inhibited by calcitonin. In vivo, administration of salmon calcitonin to OVX rats resulted in significant (P<0.001) decrease in CTX-II levels. CONCLUSION: These results are the first evidence of calcitonin receptor expression on articular chondrocytes and that the chondroprotective effects of calcitonin might involve the inhibition of MMP expression.

Animals↗

PubMed2005

[On the way to isotopic spatial resolution: technical principles and applications of 16-slice CT].

The broad introduction of multi-slice CT by all major vendors in 1998 was a milestone with regard to extended volume coverage, improved axial resolution and better utilization of the tube output. New clinical applications such as CT-examinations of the heart and the coronary arteries became possible. Despite all promising advances, some limitations remain for 4-slice CT systems. They come close to isotropic resolution, but do not fully reach it in routine clinical applications. Cardiac CT-examinations require careful patient selection. The new generation of multi-slice CT-systems offer simultaneous acquisition of up to 16 sub-millimeter slices and improved temporal resolution for cardiac examinations by means of reduced gantry rotation time (0.4 s). In this overview article we present the basic technical principles and potential applications of 16-slice technology for the example of a 16-slice CT-system (SOMATOM Sensation 16, Siemens AG, Forchheim). We discuss detector design and dose efficiency as well as spiral scan- and reconstruction techniques. At comparable slice thickness, 16-slice CT-systems have a better dose efficiency than 4-slice CT-systems. The cone-beam geometry of the measurement rays requires new reconstruction approaches, an example is the adaptive multiple plane reconstruction, AMPR. First clinical experience indicates that sub-millimeter slice width in combination with reduced gantry rotation-time improves the clinical stability of cardiac examinations and expands the spectrum of patients accessible to cardiac CT. 16-slice CT-systems have the potential to cover even large scan ranges with sub-millimeter slices at considerably reduced examination times, thus approaching the goal of routine isotropic imaging.

Cardiovascular Diseases↗

PubMed2005

In vitro, ex vivo, and in vivo methodological approaches for studying therapeutic targets of osteoporosis and degenerative joint diseases: how biomarkers can assist?

Although our approach to the clinical management of osteoporosis (OP) and degenerative joint diseases (DJD)-major causes of disability and morbidity in the elderly-has greatly advanced in the past decades, curative treatments that could bring ultimate solutions have yet to be found or developed. Effective and timely development of candidate drugs is a critical function of the availability of sensitive and accurate methodological arsenal enabling the recognition and quantification of pharmacodynamic effects. The established concept that both OP and DJD arise from an imbalance in processes of tissue formation and degradation draws attention to need of establishing in vitro, ex vivo, and in vivo experimental settings, which allow obtaining insights into the mechanisms driving increased bone and cartilage degradation at cellular, organ, and organism levels. When addressing changes in bone or cartilage turnover at the organ or organism level, monitoring tools adequately reflecting the outcome of tissue homeostasis become particularly critical. In this context, bioassays targeting the quantification of various degradation and formation products of bone and cartilage matrix elements represent a useful approach. In this review, a comprehensive overview of widely used and recently established in vitro, ex vivo, and in vivo set-ups is provided, which in many cases effectively take advantage of the potentials of biomarkers. In addition to describing and discussing the advantages and limitations of each assay and their methods of evaluation, we added experimental and clinical data illustrating the utility of biomarkers for these methodological approaches.

Animals↗

PubMed2005

The role of chloride channels in osteoclasts: ClC-7 as a target for osteoporosis treatment.

Chloride ions play a major role in osteoclast biology and bone homeostasis. In addition to its general cellular roles, chloride is involved in the specific bone resorption activity of osteoclasts. The chloride channel ClC-7 has been shown to be mandatory for bone resorption. It is necessary for the acidification of the resorption lacunae. In addition to ClC-7, other chloride channels and exchangers have been identified in osteoclasts. The bicarbonate-chloride exchanger at the plasma membrane of osteoclasts is important for regulating the cytoplasmic pH during bone resorption. The role of the additional chloride channels or putative chloride channels identified in osteoclasts, volume-regulated anion channel, Chlor.62 and CLIC1 has not been established. To date, ClC-7 is the only known chloride channel whose disruption or mutation leads to a bone disease: osteopetrosis, which is characterized by an increased bone mass. Inhibition of ClC-7 constitutes a new potential way to treat osteoporosis. The expression of ClC-7 is restricted to few tissues with very high expression in the osteoclasts in bone. Pharmacologically, inhibitors of acidification of the resorption lacunae have proved to be unique, as inhibition leads to a decrease in bone resorption without affecting bone formation, suggesting that the coupling principle has been challenged. Thus, ClC-7 inhibitors may prove to be potent for prevention and treatment of osteoporosis.

Animals↗

PubMed2004

Aorto-iliac multidetector-row CT angiography with low kV settings: improved vessel enhancement and simultaneous reduction of radiation dose.

The aim of the study was to implement an abdominal CT angiography protocol using 100 kVp and to compare SNR and CNR, as well as subjective image quality, to a standard CT angiography protocol using 120 kVp on a 16 detector-row CT scanner. Forty-eight patients were referred for routine abdominal CT angiography on a 16 detector-row CT scanner. Patients were scanned using either 120 or 100 kVp at constant mAs settings. Vessel opacification was provided by automated contrast injection using similar injection protocols. Density measurements were performed along the aorto-iliac axis with SNR and CNR calculation. In addition, the estimated effective patient radiation dose was calculated. Results of both protocols were compared. The 100-kVp protocol (432+/-80 HU) showed a significantly higher vessel density than the 120-kVp (333+/-90 HU; P<0.001) protocol, corresponding to an average increase in signal intensity of 30.7%. SNR (36.0 vs 37.0) and CNR (31.1 vs 31.7) for the 100-kV protocol were not significantly lower that those for the standard protocol (P=0.79 and P=0.87), whilst the average estimated dose was significantly lower using the 100-kVp protocol (6.7+/-0.4 vs 10.1+/-1.2 mSv; P<0.0001). Tube kVp reduction from 120 to 100 kVp allows for significant reduction of patient dose in abdominal CT angiography, without significant change in SNR,CNR and image quality.

Adult↗

PubMed2004

[Current status and future potentials of multislice computed tomography].

This overview article gives a short introduction into present status and future potential of multislice computed tomography. The main benefits of established 4- to 16-slice CT systems are larger volume coverage, better utilization of the X-ray tube output and above all improved transverse resolution. Spiral examinations with 16 submillimeter slices are a breakthrough on the way towards isotropic scanning for routine applications. ECG-controlled CT-examinations of the heart benefit from both the improved temporal and spatial resolution of the new generation of 16-slice CT systems. Compared to 4-slice scanners, cardiac examinations are clinically more robust. The most important potential for improvement of multislice cardiac CT is a further enhancement of temporal resolution which requires increased gantry rotation speed for robust clinical performance. Combined systems such as CT PET scanners will gain increasing importance in the near future. In general radiology the race for more slices will continue, finally leading to the introduction of CT systems with area-detectors.

Angiography↗

PubMed2003

Individually weight-adapted examination protocol in retrospectively ECG-gated MSCT of the heart.

The standard protocol in multislice spiral CT (MSCT) angiography for coronary arteries with fixed tube current-time settings leads to an overexposure and thus to an unnecessary high radiation dose in patients with lower weight when compared to heavier patients. The purpose of this study was to estimate the effect of reducing the radiation dose by adapting the tube current-time settings individually. Fifty patients underwent retrospectively ECG-gated MSCT of the heart. In 25 patients (group A1) a standard protocol with constant tube current-time settings was used (4 x 1-mm collimation, 120 kV, 400 mAs(eff)). Subsequently, artificial image noise was added to the data of these patients simulating a directive for weight-adapted tube current-time settings (group A2). In the other 25 patients (group B) an alternative protocol with individually weight-adapted tube current-time settings was applied. The data of all groups were evaluated by a regression analysis. The image quality was assessed objectively by measuring the CT attenuation in standardised regions of interest and subjectively by three radiologists using a five-point scoring system in a consensus reading. Applying the weight-adapted tube current-time settings the effective radiation dose was reduced by 17.9% for men and 26.3% for women. The standard protocol leads to an overexposure in light patients as seen in the plot of noise vs weight (slope 0.16+/-0.07 HU/kg). By applying the weight-adapted tube current-time settings a weight-independent, constant image noise is achieved (slope 0.04+/-0.1 HU/kg). Diagnostic image quality was preserved in all patients. Individually weight-adapted tube current-time settings allow for a substantial dose reduction when performing retrospectively ECG-gated MSCT angiography for coronary arteries without impairment of diagnostic image quality.

Aged↗

PubMed2003

[Virtual organization in the digital age of radiology - principle and solution for radiologic research?].

The research project "VICORA - Virtual Institute for Computer-Assisted Radiology", funded by the German Federal Ministry of Education and Research, was initiated in the year 2000. Its virtual organization brings together physical science, engineering, information technology, clinical radiology and the medical technology industry. In the German radiology research domain VICORA serves as a model for interdisciplinary collaboration for the changing radiology paradigm illustrated by a "radiologycube". The project does not only aim at scientific goals but also considers the infrastructure, components and human resource management within a virtual organization. The common rapid prototyping platform ILAB 4 ensures user-friendly and time-efficient software that assists with the routine radiology work-flow including full DICOM functionality. By offering a new work environment and collaborative culture based on telematics and knowledge exchange in radiology research, VICORA overcomes limitations of traditional research organization.

Diagnosis, Computer-Assisted↗

PubMed2003

Image reconstruction and image quality evaluation for a 16-slice CT scanner.

We present a theoretical overview and a performance evaluation of a novel approximate reconstruction algorithm for cone-beam spiral CT, the adaptive multiple plane reconstruction (AMPR), which has been introduced by Schaller, Flohr et al. [Proc. SPIE Int. Symp. Med. Imag. 4322, 113-127 (2001)] AMPR has been implemented in a recently introduced 16-slice CT scanner. We present a detailed algorithmic description of AMPR which allows for a free selection of the spiral pitch. We show that dose utilization is better than 90% independent of the pitch. We give an overview on the z-reformation functions chosen to allow for a variable selection of the spiral slice width at arbitrary pitch values. To investigate AMPR image quality we present images of anthropomorphic phantoms and initial patient results. We present measurements of spiral slice sensitivity profiles (SSPs) and measurements of the maximum achievable transverse resolution, both in the isocenter and off-center. We discuss the pitch dependence of image noise measured in a centered 20 cm water phantom. Using the AMPR approach, cone-beam artifacts are considerably reduced for the 16-slice scanner investigated. Image quality in MPRs is independent of the pitch and equivalent to a single-slice CT system at pitch p approximately 1.5. The full width at half-maximum (FWHM) of the spiral SSPs shows only minor variations as a function of the pitch, nominal, and measured values differ by less than 0.2 mm. With 16 x 0.75 mm collimation, the measured FWHM of the smallest reconstructed slice is about 0.9 mm. Using this slice width and overlapping image reconstruction, cylindrical holes with 0.6 mm diameter can be resolved in a z-resolution phantom. Image noise for constant effective mAs is nearly independent of the pitch. Measured and theoretically expected dose utilization are in good agreement. Meanwhile, clinical practice has demonstrated the excellent image quality and the increased diagnostic capability that is obtained with the new generation of multislice CT systems.

Algorithms↗

PubMed2003

Image reconstruction and performance evaluation for ECG-gated spiral scanning with a 16-slice CT system.

We present an image reconstruction approach and a performance evaluation for ECG-gate cardiac spiral scanning with recently introduced 16-slice CT equipment. We present an extension of the Adaptive Cardio Volume (ACV) reconstruction approach for ECG-gated multislice spiral scanning. We discuss the image z reformation introduced to control the spiral slice width of the final images and give an overview of the reformation functions chosen. We investigate image quality and discuss the maximum number of slices that can be reconstructed without severe cone-beam artifacts. Slice sensitivity profiles (SSPs) and transverse resolution are evaluated as a function of the patient's heart rate. We demonstrate the influence of slice width on the visualization of stents and plaques and show the impact of reduced gantry rotation time (0.42 s) on temporal resolution. Deviating from general purpose spiral scanning cone-beam reconstruction is not required for ECG-gated cardiac CT with up to 16 slices. Using the ACV approach with image reformation, SSPs are well defined and independent of the patient's heart rate. With 0.75 mm collimated slice width, the measured full width at half-maximum (FWHM) of the smallest reconstructed slice is about 0.83 mm. Using this slice width and overlapping image reconstruction, cylindrical holes 0.6-0.7 mm in diameter can be resolved in a z-resolution phantom. Adequate visualization of the coronary arteries requires reconstruction slice widths not larger than 1.5 mm. Visualization of stents and severe calcifications is significantly improved with sub-mm slice width. Experimental evidence for the theoretically predicted temporal resolution and for the variation of temporal resolution depending on the position in the field of measurement (FOM) is presented. With 0.42 s gantry rotation temporal resolution reaches its optimum of 105 ms in the center of the FOM at 81 bpm. First scans on human subjects demonstrate the potential to expand the range of heart rates accessible to routine clinical examinations. A 16-slice platform can cover the heart with sub-mm slices within short breath-hold times, allowing for improved cardiac imaging due to isotropic sub-mm spatial resolution.

Algorithms↗

PubMed2003

Detection of coronary calcifications: feasibility of dose reduction with a body weight-adapted examination protocol.

OBJECTIVE: The purpose of this study was to assess the applicability of individual body weight-adapted tube current time settings in multidetector CT for detection of coronary calcifications and to evaluate the effect of reducing the radiation dose on the coronary calcium score. SUBJECTS AND METHODS. One hundred patients underwent retrospectively ECG-gated MDCT for detection of coronary calcifications. First, fixed tube current time settings were used in 50 patients. Second, image noise corresponding to body weight-adapted tube current time settings was added to these images. Finally, body weight-adapted tube current time settings were applied to another 50 patients. For each patient group, the radiation dose was calculated. Coronary calcium scores were compared for the patient groups with the fixed tube current time settings with and without artificially added image noise. In all image series, image noise was assessed by a region-of-interest methodology. Image noise was analyzed using a regression analysis. RESULTS: The effective radiation dose was reduced by 11.6% for men and 24.8% for women using the body weight-adapted tube current time settings. There were no statistically significant changes in the coronary calcium score after the addition of artificial image noise (p = 0.84). Adaptation of the tube current time settings did not lead to a relevant increase in image noise. The radiation doses for the plotted noise-to-body weight (slope, 0.081) and noise-to-body mass index (slope, 0.378) ratios for the standard protocol proved relatively high for patients of lower weight. An improved noise-to-body weight (slope, 0.054) and noise-to-body mass index (slope, 0.190) ratio was achieved by application of the body weight-adapted tube current time settings, resulting in nearly constant image noise related to body weight. CONCLUSION: Individual body weight-adapted current time settings are applicable for coronary calcium scoring without a change of the coronary calcium score or relevant increase of the image noise.

Body Mass Index↗

PubMed2002

A retrospectively ECG-gated multislice spiral CT scan and reconstruction technique with suppression of heart pulsation artifacts for cardio-thoracic imaging with extended volume coverage.

A method for cardio-thoracic multislice spiral CT imaging with ECG gating for suppression of heart pulsation artifacts is introduced. The proposed technique offers extended volume coverage compared with standard ECG-gated spiral scan and reconstruction approaches for cardiac applications: Thin-slice data of the entire thorax can be acquired within one breath-hold period using a four-slice CT system. The extended volume coverage is enabled by a modified approach for ECG-gated image reconstruction. For a CT system with 0.5-s gantry rotation time, images are reconstructed with 250-ms image temporal resolution. Instead of selecting scan data acquired in exactly the same phase of the cardiac cycle for each image as in standard ECG-gated reconstruction techniques, the patient's ECG signal is used to omit scan data acquired during the systolic phase of highest cardiac motion. With this approach cardiac pulsation artifacts in CT studies of the aorta, of paracardiac lung segments, and of coronary bypass grafts can be effectively reduced.

Aortic Diseases↗

PubMed2002

Strategies for cardiac CT imaging.

We review the scanning techniques for cardiac CT imaging with single slice and multislice scanners. Combined with prospective triggering for transaxial scanning and retrospective gating for helical scanning the potential advantages and the basic limitations are discussed. Based on those theoretical considerations, the major conclusion is that high resolution data sets with isotropic spatial resolution can be acquired with quadslice, spiral scanning, only. First clinical results support this conclusion.

Heart↗

PubMed2002

Defining the optimum upper heart rate limit during exercise: a study in pacemaker patients with heart failure.

AIMS: There is no non-invasive method to determine the individual optimum of maximum exercise heart rate. Knowledge of this value is of particular interest in patients with structural heart disease who are prone to tachycardia intolerance. The purpose of this study was to define the optimal maximum heart rate using cardiopulmonary exercise testing and exercise Doppler echocardiography and to compare the results of both approaches. METHODS AND RESULTS: In 49 pacemaker patients with chronotropic incompetence, the optimum upper heart rate limit was determined using cardiopulmonary exercise testing and exercise Doppler echocardiography. The optimum upper rate limit was given by the highest pacing rate which still produced an increase in oxygen consumption, or by that pacing rate which was linked to the lowest value for the Doppler-derived myocardial performance index. In patients with normal left ventricular ejection fraction (>or=55%) the optimum upper rate limit was 86% of age-predicted maximum heart rate, in patients with left ventriuclar dysfunction (ejection fraction <or=45%) it was 75% of the age-predicted maximum rate (P=0.004). The optimum upper rate limit, as defined by cardiopulmonary exercise testing and exercise Doppler echocardiography, were closely correlated (P<0.0001) with a mean deviation of 6+/-6 beats x min(-1). CONCLUSION: Cardiopulmonary exercise testing and exercise Doppler echocardiography are valuable tools which help to determine the optimum upper rate limit in order to avoid excess heart rates in heart failure patients. The application of these methods is not limited to pacemaker patients but may be helpful in therapeutic interventions with chronotropic drugs.

Adult↗

PubMed2002

[A differentiated approach to the diagnosis of pulmonary embolism and deep venous thrombosis using multi-slice CT].

PURPOSE: To establish a differentiated protocol for multi-slice CT (MSCT) examinations in cases of clinically suspected pulmonary embolism (PE) using pulmonary CT-angiography (CTA) and indirect CT-phlebography (CTP). MATERIALS AND METHODS: 161 patients with suspected PE were examined using an MSCT (SOMATOM Volume Zoom; Siemens, Forchheim, Germany). After intravenous administration of 120 ml of contrast material, a thin collimation chest-CT scan was performed (120 kV, 100 mAs, collimation: 4 x 1 mm). If PE was present, or previous examinations and clinical signs suggested deep venous thrombosis (DVT), a CTP was subsequently completed. CTPs were performed using a 4 x 5 mm protocol (120 kV, 170 mAs). Venous phase scanning, starting from the pelvic crest, was completed in the popliteal fossa three minutes after contrast material injection. In 73 extremities, CTP were compared to the results of ultrasound, phlebography and autopsy. Scan ranges were documented in all patients. Cumulative doses were calculated for male and female subgroups. RESULTS: 62 patients in our series suffered from PE and in 47 of these patients deep venous thrombosis was seen additionally. Of the 99 patients without PE, 47 also received indirect CTP. CTP confirmed the suspicion and extent of DVT in 8 patients. Only in 2 of 39 patients (5.1 %) was previously unknown DVT found, despite the exclusion of PE. Regarding DVT, sensitivity was 94.3 % and specificity was 92.1 % for indirect CTP. Cumulative chest CT doses averaged 3.3 mSv for males and 4.2 mSv for females, the calculated CTP dosage was 9.3 mSv (according to ICRP 60). CONCLUSIONS: The examination protocol presented is suitable for clinical usage in patients with suspected PE. If PE is confirmed, indirect CTP is justified, so that detailed information of the venous system can be obtained. However, the relatively high radiation dosage of an additional CTP requires a strict indication regiment in patients with a negative CTA.

Adult↗

PubMed2002

[Visualization of coronary arteries in CT as assessed by a new 16 slice technology and reduced gantry rotation time: first experiences].

PURPOSE: First evaluation of image quality of a new 16-slice multidetector-row computed tomography (MDCT) for the assessment of coronary artery disease and lesion detection of the coronary arteries. MATERIALS AND METHODS: On a newly developed 16-slice CT scanner (SOMATOM Sensation 16, Siemens, Forchheim, Germany) a calcium score as well as a contrast-enhanced CT angiography (CTA) were performed on 4 patients with retrospective ECG-gating and a gantry rotation time of 420 ms to exclude or follow-up coronary heart disease. CTA was performed after injecting 120 ml contrast media intravenously. After medication with a ss-Blocker, the heart rate was between 55 and 67 bpm. RESULTS: The scan time for calcium score was 12 s, for CTA 18 s (scan range 15 and 12 cm, respectively). Volume score was between 0 and 256.4. In the CT angiography the entire coronary tree could be visualized in all patients up to the very distal subsegmental branches. In two patients a complete occlusion of the RCA and the LAD were depicted, respectively. In one of these patients, a large aneurysm of the left anterior ventricular wall was also delineated. CONCLUSION: Considering our first experiences with the new 16-slice technology, an excellent visualization of the entire coronary tree including the very distal and side branches due to substantially increased spatial resolution seems to be achievable. In these patients the acquired image quality raises the hope for improved, non-invasive cardiac diagnostics. In larger studies, the clinical impact of this new technology needs to be further investigated.

Aged↗

PubMed2002

New technical developments in multislice CT--Part 1: Approaching isotropic resolution with sub-millimeter 16-slice scanning.

The introduction of multislice CT was a breakthrough with regard to increased scan speed, improved axial resolution and better utilization of the tube output. The new generation of multislice CT scanners offering simultaneous acquisition of up to 16 sub-millimeter slices represents an important leap on the way towards true isotropic scanning. We present an evaluation of a state-of-the-art 16-slice CT system (SOMATOM Sensation 16, Siemens AG, Forchheim, Germany). After an introduction to the detector design we discuss dose utilization and finally elaborate on multislice spiral scanning with 16 slices. Due to the increased number of slices dose utilization is improved compared to current 4-slice CT scanners, and sub-millimeter collimation needs no longer be restricted to special applications. For CT systems with 8 or more slices, the cone-beam geometry causes severe artifacts if not corrected for by a so-called cone-correction, which thus becomes mandatory in this case. With the Adaptive Multiple Plane Reconstruction AMPR, cone beam artifacts are effectively suppressed, while the benefits of Adaptive Axial Interpolation are maintained: free selection of the spiral pitch according to the clinical needs of an examination, slice width independent of the pitch, full dose utilization at all pitch values. Clinical practice will have to demonstrate the application spectrum that is opened with the new generation of multislice CT systems.

Artifacts↗