68 resultados para estimation of parameters
Resumo:
In 1996, a cadaver in adipocere condition was discovered in a bay of the Brienzer See in Switzerland. The torso was named "Brienzi" following the "Iceman" Ötzi. Several outer parts of the body were incrusted; the incrustation was in blue color. Further investigations showed that the bluish covering of parts of the adipocere torso were a mineral known as Vivianite. Vivianite (Fe(3)(PO(4))(2-)(H(2)O)(8)) is an iron phosphate mineral with needle lengths between 100 and 150μm. It is normally associated in a context with organic archaeological and geological materials (some hundreds to millions of years old). Hitherto, it is only described in three cases of human remains. We were able to reconstruct the following facts about 'Brienzi': The man drowned in Lake Brienz or in one of its tributaries during the 1700s. The body was subsequently covered with sedimentation and thus buried under water. An earthquake produced an underwater landslide which eventually exposed the corpse.
Resumo:
The Estimation of Physiologic Ability and Surgical Stress score was designed to predict postoperative morbidity and mortality in general surgery. Our study aims to evaluate its use and accuracy in estimating postoperative outcome after elective pancreatic surgery.
Resumo:
Low back pain is associated with plasticity changes and central hypersensitivity in a subset of patients. We performed a case-control study to explore the discriminative ability of different quantitative sensory tests in distinguishing between 40 cases with chronic low back pain and 300 pain-free controls, and to rank these tests according to the extent of their association with chronic pain. Gender, age, height, weight, body mass index, and psychological measures were recorded as potential confounders. We used 26 quantitative sensory tests, including different modalities of pressure, heat, cold, and electrical stimulation. As measures of discrimination, we estimated receiver operating characteristics (ROC) and likelihood ratios. Six tests seemed useful (in order of their discriminative ability): (1) pressure pain detection threshold at the site of most severe pain (fitted area under the ROC, 0.87), (2) single electrical stimulation pain detection threshold (0.87), (3) single electrical stimulation reflex threshold (0.83), (4) pressure pain tolerance threshold at the site of most severe pain (0.81), (5) pressure pain detection threshold at suprascapular region (0.80), and (6) temporal summation pain threshold (0.80). Pressure and electrical pain modalities seemed most promising and may be used for diagnosis of pain hypersensitivity and potentially for identifying individuals at risk of developing chronic low back pain over time.
Resumo:
Full axon counting of optic nerve cross-sections represents the most accurate method to quantify axonal damage, but such analysis is very labour intensive. Recently, a new method has been developed, termed targeted sampling, which combines the salient features of a grading scheme with axon counting. Preliminary findings revealed the method compared favourably with random sampling. The aim of the current study was to advance our understanding of the effect of sampling patterns on axon counts by comparing estimated axon counts from targeted sampling with those obtained from fixed-pattern sampling in a large collection of optic nerves with different severities of axonal injury.
Resumo:
OBJECTIVE: Computed tomography (CT) and magnetic resonance imaging (MRI) are introduced as an alternative to traditional autopsy. The purpose of this study was to investigate their accuracy in mass estimation of liver and spleen. METHODS: In 44 cases, the weights of spleen and liver were estimated based on MRI and CT data using a volume-analysis software and a postmortem tissue-specific density factor. In a blinded approach, the results were compared with the weights noted at autopsy. RESULTS: Excellent correlation between estimated and real weights (r = 0.997 for MRI, r = 0.997 for CT) was found. Putrefaction gas and venous air embolism led to an overestimation. Venous congestion and drowning caused higher estimated weights. CONCLUSION: Postmortem weights of liver and spleen can accurately be assessed by nondestructive imaging. Multislice CT overcomes the limitation of putrefaction and venous air embolism by the possibility to exclude gas. Congestion seems to be even better assessed.
Resumo:
Knowledge of the time interval from death (post-mortem interval, PMI) has an enormous legal, criminological and psychological impact. Aiming to find an objective method for the determination of PMIs in forensic medicine, 1H-MR spectroscopy (1H-MRS) was used in a sheep head model to follow changes in brain metabolite concentrations after death. Following the characterization of newly observed metabolites (Ith et al., Magn. Reson. Med. 2002; 5: 915-920), the full set of acquired spectra was analyzed statistically to provide a quantitative estimation of PMIs with their respective confidence limits. In a first step, analytical mathematical functions are proposed to describe the time courses of 10 metabolites in the decomposing brain up to 3 weeks post-mortem. Subsequently, the inverted functions are used to predict PMIs based on the measured metabolite concentrations. Individual PMIs calculated from five different metabolites are then pooled, being weighted by their inverse variances. The predicted PMIs from all individual examinations in the sheep model are compared with known true times. In addition, four human cases with forensically estimated PMIs are compared with predictions based on single in situ MRS measurements. Interpretation of the individual sheep examinations gave a good correlation up to 250 h post-mortem, demonstrating that the predicted PMIs are consistent with the data used to generate the model. Comparison of the estimated PMIs with the forensically determined PMIs in the four human cases shows an adequate correlation. Current PMI estimations based on forensic methods typically suffer from uncertainties in the order of days to weeks without mathematically defined confidence information. In turn, a single 1H-MRS measurement of brain tissue in situ results in PMIs with defined and favorable confidence intervals in the range of hours, thus offering a quantitative and objective method for the determination of PMIs.
Resumo:
This paper addresses the problem of estimating postoperative cup alignment from single standard X-ray radiograph with gonadal shielding. The widely used procedure of evaluation of cup orientation following total hip arthroplasty using single standard anteroposterior radiograph is known inaccurate, largely due to the wide variability in individual pelvic position relative to X-ray plate. 2D-3D image registration methods have been introduced to estimate the rigid transformation between a preoperative CT volume and postoperative radiograph(s) for an accurate estimation of the postoperative cup alignment relative to an anatomical reference extracted from the CT data. However, these methods require either multiple radiographs or a radiograph-specific calibration, both of which are not avaiable for most retrospective studies. Furthermore, these methods were only evaluated on X-ray radiograph(s) without gonadal shielding. In this paper, we propose to use a hybrid 2D-3D registration scheme combining an iterative landmark-to-ray registration with a 2D-3D intensity-based registration to estimate the rigid transfromation for a precise estimation of cup alignment. Quantitative and qualitative results evaluated on clinical and cadaveric datasets are given which indicate the validity of our approach.