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Computer Tomography (computer + tomography)
Selected AbstractsImproved understanding of velocity,saturation relationships using 4D computer-tomography acoustic measurementsGEOPHYSICAL PROSPECTING, Issue 2 2005K. Monsen ABSTRACT A recently developed laboratory method allows for simultaneous imaging of fluid distribution and measurements of acoustic-wave velocities during flooding experiments. Using a specially developed acoustic sample holder that combines high pressure capacity with good transparency for X-rays, it becomes possible to investigate relationships between velocity and fluid saturation at reservoir stress levels. High-resolution 3D images can be constructed from thin slices of cross-sectional computer-tomography scans (CT scans) covering the entire rock-core volume, and from imaging the distribution of fluid at different saturation levels. The X-ray imaging clearly adds a new dimension to rock-physics measurements; it can be used in the explanation of variations in measured velocities from core-scale heterogeneities. Computer tomography gives a detailed visualization of density regimes in reservoir rocks within a core. This allows an examination of the interior of core samples, revealing inhomogeneities, porosity and fluid distribution. This mapping will not only lead to an explanation of acoustic-velocity measurements; it may also contribute to an increased understanding of the fluid-flow process and gas/liquid mixing mechanisms in rock. Immiscible and miscible flow in core plugs can be mapped simultaneously with acoustic measurements. The effects of core heterogeneity and experimentally introduced effects can be separated, to clarify the validity of measured velocity relationships. [source] Intravenous extended liposarcoma arising from renal sinusINTERNATIONAL JOURNAL OF UROLOGY, Issue 8 2007Mabumi Matsushita Abstract: Liposarcoma arising from the renal sinus is rare and there have been no reports of intravenous extended liposarcoma of the renal sinus thus far. We report a case of liposarcoma of the renal sinus that extended into the renal venous lumen. A 58-year-old woman was referred to our hospital for an intravascular fatty tumor of the right renal vein incidentally discovered by an abdominal screening ultrasonogram. Computer tomography revealed a fatty tumor extending from the right kidney to the right renal vein with no evidence of metastatic lesions. Total right nephrectomy and extirpation of the intravascular tumor of the right renal vein were carried out. Pathological findings showed well-differentiated liposarcoma of the renal sinus. The tumor invaded to the right renal vein and the renal parenchyma. [source] HTLV-II infection associated with a chronic neurodegenerative disease: Clinical and molecular analysisJOURNAL OF MEDICAL VIROLOGY, Issue 2 2002Edimilson A. Silva Abstract HTLV II is a retrovirus endemic in some Amerindian tribes and spread worldwide with a high prevalence among intravenous drug abusers. It has three different genetic subtypes a, b, and d, defined mainly by the long terminal repeat (LTR) region. HTLV II has been associated with a neurodegenerative disease in few cases. We describe the first well-documented case in Brazil where the virus is endemic in isolated ethnic groups. The patient is a 55-year-old woman with a chronic and painful syndrome characterized by spastic paraparesis, hyperactive reflexes and spastic bladder. Somatosensory evoked potential indicates a thoracic spinal cord lesion. Computer tomography showed periventricular demyelination. Enzyme-linked immunosorbent assay was positive for HTLV I/II whereas the discriminatory Western blot was indeterminate. Molecular analysis of the Tax region revealed a HTLV II pattern that was also confirmed through sequencing the LTR region. Phylogenetic analysis of the LTR sequence shows an HTLV IIa subtype that clustered with the virus isolated from Kayapo Indians and Brazilian urban intravenous drug users. Indeterminate Western blots are frequently found using commercial kits, therefore we recommend that all cases in which a myelopathy is associated with an indeterminate serological result should be evaluated by PCR to determine the actual number of HTLV II associated myelopathy cases. J. Med. Virol. 66:253,257, 2002. © 2002 Wiley-Liss, Inc. [source] The interdental gingiva, a visible guide for placement of mini-implantsORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 1 2009YS Chun Structured Abstract Authors,,, Chun YS, Lee SK, Wikesjö UME, Lim WH Objectives,,, To determine whether the tip of the interdental gingiva can serve as a visible guide for placement of mini-implants. Setting and Sample population,,, Computer tomography (CT) images from 15 males and 15 females (mean age 27 years, range: 23,35 years) were used to evaluate the distance from the tip of the interdental gingiva to the alveolar crest from the central incisor to the 1st molar. The distance from a reference point to the tip of interdental gingiva was recorded from study models using a caliper. The distance between the reference point and the alveolar crest was recorded using CT and added to the model recordings thus providing the distance from the tip of interdental gingiva to the alveolar crest for the various interdental sites. Two-way anova and Student,Newman,Keuls test for multiple comparisons were used for the statistical analysis. Results,,, There was no significant difference in the distance from the tip of interdental gingiva to the alveolar crest between maxilla and mandible. The distance between the tip of interdental gingiva and the alveolar crest at the central/lateral incisors was the shortest compared with that of other sites. There was also a statistically significant difference between the male and female groups except for the maxillary 2nd premolar/1st molar interradicular site. Conclusion,,, The tip of interdental gingiva appears a reasonable visual guide for the placement of mini-implants for orthodontic anchorage. [source] Laser photocoagulation for choroidal neovascular membrane associated with optic disc drusenACTA OPHTHALMOLOGICA, Issue 2 2004Marie N. Delyfer Abstract. Purpose:, To report two cases of choroidal neovascular membrane associated with optic disc drusen which were successfully treated using argon laser photocoagulation. Methods:, Choroidal neovascular complications of optic disc drusen were diagnosed in two of our patients, a 36-year-old woman and a 14-year-old girl. In both cases visual acuity was 20/100 in the affected eye. Fundus examination and angiography revealed a choroidal neovascular membrane. Computer tomography identified bilateral calcified drusen of the optic discs. Photocoagulation of neovascular tissues was immediately performed. Results:, Visual acuity improved progressively, reaching 20/20 10 months after treatment in one case and 20/30 in the other. No recurrence was observed during follow-up. Conclusion:, Early diagnosis and immediate laser photocoagulation of vision-threatening choroidal neovascular membranes associated with optic disc drusen helps stop progression towards the macula and improves longterm visual acuity. [source] Methods for detecting coronary disease: epidemiology and clinical managementACTA PHYSIOLOGICA, Issue 2 2002O. Faergeman ABSTRACT The epidemic of atherosclerotic disease in wealthy countries had probably begun by 1900. Although a few physicians understood how atherosclerosis/thrombosis of the coronary arteries caused angina pectoris and myocardial infarction, the medical community did not accept that relationship until the 1920s. In wealthy countries, the epidemic peaked in mid-century, and it is now advancing in poor countries and in countries becoming affluent. Two recent developments in methods for disease detection, however, will profoundly affect not only our understanding of the epidemic of atherosclerotic disease, but also our management of patients. A redefinition of the clinical diagnosis of myocardial infarction, a well-used but imperfect measure of the epidemic, was published in September 2000. Criteria employed for about 50 years have now been replaced by criteria based on sensitive biochemical markers of necrosis of as little as 1 g of myocardium, accompanied by chest discomfort or electrocardiographic (ECG) changes, or following coronary artery intervention. The new criteria, adopted by the major societies of cardiology in Europe and the United States, is likely to increase the apparent incidence and prevalence of coronary heart disease (CHD). In the beginning of the twentieth century, diagnosis of CHD required an autopsy. In the end it was carried out by angiography as well, but it could not be applied to large proportions of the population. That has now been changed by new, non-invasive methods of computer tomography (CT) and magnetic resonance imaging (MRI), and patients, however, asymptomatic, will expect treatment for a disease that physicians have detected. Coronary artery disease (CAD) will be to CHD what occult cancer is to cancer. [source] Multimodal management of neuroendocrine liver metastasesHPB, Issue 6 2010Andrea Frilling Abstract Background:, The incidence of neuroendocrine tumours (NET) has increased over the past three decades. Hepatic metastases which occur in up to 75% of NET patients significantly worsen their prognosis. New imaging techniques with increasing sensitivity enabling tumour detection at an early stage have been developed. The treatment encompasses a panel of surgical and non-surgical modalities. Methods:, This article reviews the published literature related to management of hepatic neuroendocrine metastases. Results:, Abdominal computer tomography, magnetic resonance tomography and somatostatin receptor scintigraphy are widely accepted imaging modalities. Hepatic resection is the only potentially curative treatment. Liver transplantation is justified in highly selected patients. Liver-directed interventional techniques and locally ablative measures offer effective palliation. Promising novel therapeutic options offering targeted approaches are under evaluation. Conclusions:, The treatment of neuroendocrine liver metastases still needs to be standardized. Management in centres of expertise should be strongly encouraged in order to enable a multidisciplinary approach and personalized treatment. Development of molecular prognostic factors to select treatment according to patient risk should be attempted. [source] An interesting case of prehistoric trepanation from Poland: re-evaluation of the skull from the Franki Suchodolskie siteINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 2 2005W. Lorkiewicz Abstract The skull described here was excavated in Central Poland (archaeological site Franki Suchodolskie) in 1951, and was known as one of the oldest cases of healed trepanation. This skull, with later excavations from the Ukraine (cemeteries of Vasilyevka II and Vasilyevka III), was the basis for dating the beginning of the practice of trepanation in the Mesolithic period. The skull was never comprehensively described and dated, although it was scientifically extremely important. The skull has been reassessed by the authors of this paper has brought thorough verification of the knowledge concerning this excavation. According to radiocarbon analysis it is much younger than previously thought and has now been dated to the Late Neolithic or the Bronze Age. Earlier opinions about the healing and survival after the operation have not been confirmed: the hole in the squama of the frontal bone made by scraping and then by grooving has no evidence of healing. Radiological studies as well as computer tomography indicate lack of any healing processes in the bone tissue around the trepanation opening. The results of the analysis significantly modify ideas regarding the earliest skull operations in Central Europe, and change the time of the first trepanation to the Late Neolithic, as for most of the continent. Copyright © 2005 John Wiley & Sons, Ltd. [source] The highly specialized vocal tract of the male Mongolian gazelle (Procapra gutturosa Pallas, 1777 , Mammalia, Bovidae)JOURNAL OF ANATOMY, Issue 5 2003R. Frey Abstract The entire head and neck of a wild adult male Mongolian gazelle (Procapra gutturosa) was dissected with special reference to its enlarged larynx. Two additional adult male specimens taken from the wild were analysed by computer tomography. The sternomandibularis, omohyoideus, thyrohyoideus and hyoepiglotticus muscles are particularly enlarged and improve laryngeal suspension and stabilization. The epiglottis is exceptionally large. A permanent laryngeal descent is associated with the evolution of an unpaired palatinal pharyngeal pouch. A certain momentary descent seems to occur during vocalization. The high lateral walls of the thyroid cartilage are ventrally connected by a broad keel. The large thyroarytenoid muscle is divided into two portions: a rostral ventricularis and a caudal vocalis muscle. A paired lateral laryngeal ventricle projects between these two muscles. The massive vocal fold is large and lacks any rostrally directed flexible structures. It is supported by a large cymbal-like fibroelastic pad. Vocal tract length was measured in the course of dissection and in computer tomographic images. Two representative spectrograms, one of an adult male and one of a juvenile, recorded in the natural habitat of the Mongolian gazelle are presented. In the spectrograms, the centre frequency of the lowest band is about 500 Hz in the adult male and about 790 Hz in the juvenile. The low pitch of the adult male's call is ascribed to the evolutionary mass increase and elongation of the vocal folds. In the habitat of P. gutturosa a call with a low pitch and, thus, with an almost homogeneous directivity around the head of the vocalizing animal may be optimally suited for multidirectional advertisement calls during the rut. The signal range of an adult male's call in its natural habitat can therefore be expected to be larger than the high-pitched call of a juvenile. [source] Generalized Low Areal and Volumetric Bone Mineral Density in Adolescent Idiopathic Scoliosis,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2000J. C. Y. Cheng Abstract Adolescent idiopathic scoliosis (AIS) may be associated with generalized low bone mineral status. The bone mineral density (BMD) of 75 girls of 12,14 years of age and diagnosed as having AIS were compared with 94 age-matched female control subjects. Areal BMD (aBMD) of the lumbar spine (L2-L4) and the bilateral proximal femur were measured using -energy X-ray absorptiometry (DEXA), and volumetric BMD (vBMD) of the nondominant distal radius and bilateral distal tibias was measured with peripheral quantitative computer tomography (pQCT). Relevant anthropometric parameters and the severity of the spinal deformity (Cobb's angle) also were evaluated and correlated with the BMD measurements. Results revealed the presence of a generalized lower bone mineral status in AIS patients. Detailed analysis showed that the aBMD and vBMD measured at the bilateral lower extremities were significantly lower in AIS patients when compared with the same in the normal controls. The most significant effect was seen in the trabecular BMD (tBMD) of the distal tibias. Of all the AIS girls, 38% of the aBMD and 36% of the vBMD were below ,1 SD of the normal. BMD was found to correlate better with "years since menarche" (YSM) than with chronological age. When the BMD was evaluated for the 3 YSM groups, aBMD of the proximal femur and tBMD of distal tibias were found to be significantly lower in the AIS patients. Neither the aBMD nor the vBMD of AIS patients was found to be associated with the severity of spinal deformity. In addition, anthropometric measurements showed significantly longer arm span and lower extremities in the AIS girls. We concluded that the AIS girls had generalized lower aBMDs and vBMDs. [source] Intra-abdominal abscess in a patient with tumour necrosis factor receptor-associated periodic syndromeJOURNAL OF INTERNAL MEDICINE, Issue 2 2006S. STJERNBERG-SALMELA Abstract. Tumour necrosis factor (TNF) receptor-associated periodic syndrome (TRAPS) is an autoinflammatory disorder characterized by periodic attacks of fever and inflammation, due to mutations in the gene coding for the TNF type I receptor (TNFRSF1A). A 16-year-old patient with the diagnosis of TRAPS was admitted to hospital because of fever and abdominal pain. Initially, the symptoms were interpreted as manifestations of another TRAPS attack, but the patient's condition worsened, despite treatment with corticosteroids and antibiotics. A repeated computer tomography revealed an intra-abdominal abscess, which necessitated urgent surgical intervention. This case stresses the importance of differential diagnostic vigilance when dealing with patients with rare genetic diseases. [source] The circulatory system in Mysidacea,Implications for the phylogenetic position of Lophogastrida and Mysida (Malacostraca, Crustacea)JOURNAL OF MORPHOLOGY, Issue 4 2007Christian S. Wirkner Abstract The morphology of the circulatory organs in Mysida and Lophogastrida (traditionally combined as Mysidacea) is revisited investigating species so far unstudied. In addition to classical morphological methods, a newly developed combination of corrosion casting with micro computer tomography (MicroCT) and computer aided 3D reconstructions is used. Lophogastrida and Mysida show a highly developed arterial system. The tubular heart extends through the greater part of the thorax and is connected with the ventral vessel via an unpaired descending artery. It is suggested that a distinct ostia pattern supports the monophyly of Mysidacea. The cardiac artery system is more complex in Lophogastrida than in Mysida, consisting of up to 10 pairs of arteries that supply the viscera. In both taxa, an anterior and posterior aorta leads off the heart. In the anterior part of the cephalothorax the anterior aorta forms dilations into which muscles are internalized; these structures are called myoarterial formations. One of these myoarterial formations can also be found in all the other peracarid taxa but not in other Malacostraca. J Morphol., 2007. © 2007 Wiley-Liss, Inc. [source] Use of volumetric computerized tomography as a primary outcome measure to evaluate drug efficacy in the prevention of peri-prosthetic osteolysis: A 1-year clinical pilot of etanercept vs. placeboJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2003Edward M. Schwarz Although total hip replacement (THR) is amongst the most successful and beneficial medical procedures to date, long-term outcomes continue to suffer from aseptic loosening secondary to peri-prosthetic osteolysis. Extensive research over the last two decades has elucidated a central mechanism for osteolysis in which wear debris generated from the implant stimulates inflammatory cells to promote osteoclastogenesis and bone resorption. The cytokine tumor necrosis factor alpha (TNF,) has been demonstrated to be central to this process and is considered to be a leading target for intervention. Unfortunately, even though FDA approved TNF antagonists are available (etanercept), currently there are no reliable outcome measures that can be used to evaluate the efficacy of a drug to prevent peri-prosthetic osteolysis. To the end of developing an effective outcome measure, we evaluated the progression of lesion size in 20 patients with established peri-acetabular osteolysis (mean = 29.99 cm3, range = 2.9,92.7 cm3) of an uncemented primary THR over 1-year, using a novel volumetric computer tomography (3D-CT) technique. We also evaluated polyethylene wear, urine N-telopeptides and functional assessments (WOMAC, SF-36 and Harris Hip Score) for comparison. At the time of entry into the study baseline CT scans were obtained and the patients were randomized to etanercept (25 mg s.q., twice/week) and placebo in a double-blinded fashion. CT scans, urine and functional assessments were also obtained at 6 and 12 months. No serious adverse drug related events were reported, but one patient had to have revision surgery before completion of the study due to aseptic loosening. No remarkable differences between the groups were observed. However, the study was not powered to see significant drug effects. 3D-CT data from the 19 patients was used to determine the mean increase in lesion size over 48 weeks, which was 3.19 cm3 (p < 0.0013). Analysis of the urine N-telopeptides and functional assessment data failed to identify a significant correlation with wear or osteolysis. In conclusion, volumetric CT was able to measure progression of osteolysis over the course of a year, thus providing a technology that could be used in therapeutic trials. Using the data from this pilot we provide a model power calculation for such a trial. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Regression modelling of weighted , by using generalized estimating equationsJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 1 2000R. Gonin In many clinical studies more than one observer may be rating a characteristic measured on an ordinal scale. For example, a study may involve a group of physicians rating a feature seen on a pathology specimen or a computer tomography scan. In clinical studies of this kind, the weighted , coefficient is a popular measure of agreement for ordinally scaled ratings. Our research stems from a study in which the severity of inflammatory skin disease was rated. The investigators wished to determine and evaluate the strength of agreement between a variable number of observers taking into account patient-specific (age and gender) as well as rater-specific (whether board certified in dermatology) characteristics. This suggested modelling , as a function of these covariates. We propose the use of generalized estimating equations to estimate the weighted , coefficient. This approach also accommodates unbalanced data which arise when some subjects are not judged by the same set of observers. Currently an estimate of overall , for a simple unbalanced data set without covariates involving more than two observers is unavailable. In the inflammatory skin disease study none of the covariates were significantly associated with ,, thus enabling the calculation of an overall weighted , for this unbalanced data set. In the second motivating example (multiple sclerosis), geographic location was significantly associated with ,. In addition we also compared the results of our method with current methods of testing for heterogeneity of weighted , coefficients across strata (geographic location) that are available for balanced data sets. [source] Shape measurement using pulsed optical holography , Fast and precise shape measurement of moving objectsLASER TECHNIK JOURNAL, Issue 1 2006Susanne Frey Dr. The starting point for the development of a new shape measurement system was the request of surgeons working in the field of cranio-facial and reconstructive surgery for an improved system for precise facial measurement. For the planning and documentation of surgical interventions, information on the bone structure of the patient is needed, which is imaged by computer tomography (CT). In particular in facial surgery it is vital to the patient, that not only the functionality of the face is given, but also the appearance of the patient is restored. To account for this aspect in the planning and evaluation of surgery, the outer appearance of a patient has to be documented, hence a surface model of the face has to be generated. [source] Clinic and radiological improvement of lipoid pneumonia with multiple bronchoalveolar lavagesPEDIATRIC PULMONOLOGY, Issue 4 2009Selma M.A. Sias MD Abstract Objective To assess the potential role of multiple bronchoalveolar lavages (BALs) in the treatment of children with lipoid pneumonia (LP). Materials and Methods This prospective study included 10 children (7 female, 3 male) with LP secondary to mineral oil aspiration. The age ranged from 3 months to 7 years and 1,60 days history of mineral oil intake, with a 6 months clinic follow-up. High-resolution computer tomography (CT) was performed 1,7 days prior to treatment and 2,20 days after the last therapeutic BAL, and reviewed by two experienced chest radiologists. Oxygen saturation was measured with digital oximetry. Therapeutic BAL was performed weekly until BAL fluid was nearly transparent and the cell count returned to normal range values. Results In all children, the initial CT scans showed multifocal bilateral consolidation involving mainly the dorsal and central regions. The areas of consolidation had foci of decreased attenuation in eight patients. Following a total of 4,10 therapeutic BALs, the CT scans returned to normal in 3 patients, improved considerably in 5, and showed only slight improvement in 2. Oxygen saturation increased from 88.8,±,3.4% at presentation to 96.2,±,0.8% after treatment (P,<,0.0001). Multiple lavages reduced (P,<,0.003) numbers of lipid-laden macrophages and restored BAL cellularity to normal range values. Conclusion Multiple therapeutic BAL of children with LP results in significant improvement of CT findings, oxygen saturation, restoration of BAL fluid cellularity and clinical recover without any evidence of respiratory distress at the end of treatment and 6 months after the last BAL. Pediatr Pulmonol. 2009; 44:309,315. © 2009 Wiley-Liss, Inc. [source] Bullous pemphigoid as a dermadrome associated with spindle cell carcinoma of the gallbladderTHE JOURNAL OF DERMATOLOGY, Issue 3 2010Ayano UMEKOJI Abstract Skin disorders that appear in association with internal malignancies are called dermadromes. Bullous pemphigoid (BP), which is a major autoimmune disease of the skin, is considered to be a dermadrome, although there have been conflicting reports. We report a case of BP that preceded the diagnosis of an internal malignancy. Although we could not detect any malignancies on chest, abdominal or pelvic computer tomography on the first hospital admission, intensive screening on the third admission revealed a gallbladder malignancy. Laparoscopic cholecystectomy was performed. Histopathology showed a spindle cell carcinoma of the gallbladder. To the best of our knowledge, this is the first report of a spindle cell carcinoma of the gallbladder in a patient with BP. [source] Management of Neck Metastasis with Carotid Artery Involvement,THE LARYNGOSCOPE, Issue 1 2004Stephen B. Freeman MD Abstract Objectives To demonstrate aggressive management of neck metastasis adherent to the internal or common carotid artery using sound oncologic principles while minimizing the significant risk of complications. Study Design Our 13 year experience of treating patients with recurrent or residual neck metastasis adherent to the internal or common carotid artery was retrospectively reviewed. Methods Angiography was used in patients who demonstrated fixation of the carotid artery on examination or imaging, followed by balloon test occlusion and single photon emission computer tomography (SPECT) scanning. The majority of carotid resections were reconstructed with a vein graft, especially if there was insufficient collateral cerebral circulation. Radical resection of the soft tissue including the carotid artery was performed followed by 15 to 20 Gray of electron beam delivered directly to the deep tissue. More recently, the carotid has been permanently occluded preoperatively, if possible. The assessment of the cerebral circulation and management of the carotid artery were analyzed as was survival, site of recurrence, and complications. Results Fifty-eight charts were reviewed. The majority of patients (41) had their carotid artery reconstructed at time of resection, and the remaining had either the artery ligated or permanently occluded preoperatively. Strokes occurred in 11 patients. The median disease-specific survival was 12 months, with 24% of patients dying from distant metastasis. Conclusions The high risk of complications, loss of life's quality, and mortality must be balanced against the natural history of the disease if left untreated. The decision is a heavy burden for the patient, family, and head and neck surgeon. [source] Measurement of total body composition changes of common carp by computer tomographyAQUACULTURE RESEARCH, Issue 12 2003Csaba Hancz Abstract The crude fat and protein content of the total body was estimated by X-ray computer tomography (CT) and determined by chemical analyses during a feeding experiment with sexually matured common carp. Between 21 and 35 serial scans were taken of altogether 41 fish and samples from the homogenized body were prepared for chemical analyses. Experimental fish with an average body weight of 1453 g originated from a commercial stock of mirror carp. Two feeding regimes (carp feed and carp feed+ad libitum maize) were applied for 57 days and followed by a fasting period of 27 days. Both feeding regimes significantly increased the crude fat content of the whole body that did not decrease during fasting in spite of high water temperature (22°C). No significant changes were observed in crude protein content. The variables used for producing the prediction equations were taken from the density values of the Hounsfield scale, on a range between ,90 and +160, by summing the frequencies within each interval of 10 values. Whole body fat content could be estimated with R2=0.89,0.91 accuracy with the principal component analysis using data of all (seven) body regions and only dorsal fin region respectively. Adequate linear regression model could not be calculated by the same procedure for crude protein. Three-dimensional ,volumetric' estimation of fat tissue was also carried out on the basis of fat index showing high correlation with measured fat content. The changes of body composition of individual fish can be followed by sequential CT scanning. [source] Estimation of the ROC Curve under Verification BiasBIOMETRICAL JOURNAL, Issue 3 2009Ronen Fluss Abstract The ROC (receiver operating characteristic) curve is the most commonly used statistical tool for describing the discriminatory accuracy of a diagnostic test. Classical estimation of the ROC curve relies on data from a simple random sample from the target population. In practice, estimation is often complicated due to not all subjects undergoing a definitive assessment of disease status (verification). Estimation of the ROC curve based on data only from subjects with verified disease status may be badly biased. In this work we investigate the properties of the doubly robust (DR) method for estimating the ROC curve under verification bias originally developed by Rotnitzky, Faraggi and Schisterman (2006) for estimating the area under the ROC curve. The DR method can be applied for continuous scaled tests and allows for a non-ignorable process of selection to verification. We develop the estimator's asymptotic distribution and examine its finite sample properties via a simulation study. We exemplify the DR procedure for estimation of ROC curves with data collected on patients undergoing electron beam computer tomography, a diagnostic test for calcification of the arteries. [source] Ultrasonically measured horizontal eye muscle thickness in thyroid associated orbitopathy: cross-sectional and longitudinal aspects in a Danish seriesACTA OPHTHALMOLOGICA, Issue 2 2003Hans C. Fledelius Abstract. Purpose:, To analyse horizontal extraocular muscle findings by ultrasound and exophthalmometry in a tertiary endocrinology centre series of patients with thyroid associated orbitopathy (TAO). Methods:, The 90 thyroid patients included underwent ultrasonic measurement of horizontal eye muscle thickness by a B-scan based technique carried out in addition to their general ophthalmic evaluation. As an indicator of mainly advanced TAO, longterm prednisone or cyclosporine A was given to many of the patients, and drug-resistant visual loss indicated decompression surgery in four of the 90 patients. Thirty-four patients underwent repeated muscle recordings over 15,49 months; this allowed for cross-sectional analysis and the outlining of longitudinal trends. Results and Conclusions:, (A) Although marginally overlapping, all four muscle groups were significantly thicker in the study group than in normal control subjects. The mean of the sum of all four muscles was 16.8 mm (range 13.6,21.7 mm) in the control group versus 22.6 mm (range 15.5,36.4 mm) in the thyroid group. (B) Using the clinical NOSPECS grading, more advanced eye involvement was found to generally result in a higher exophthalmometric measurement of protrusion and eye muscle thickness. However, slender rectus muscles and/or normal exophthalmometric values might occur even in advanced orbitopathy. (C) Over a period of 2,4 years, only a few of 34 patients with satisfactory serial ultrasonic measurements returned to their premorbid ophthalmic status. Typically, the extraocular muscles kept their abnormal size after having become clinically quiescent (fibrotic). (D) We found no safe indication regarding disease stage, active or late, from the ultrasonic appearance of the muscle tissue. (E) Discrepancies between various normative eye muscle studies are discussed with regard to computer tomography and magnetic resonance imaging. [source] Bone reactions to controlled loading of endosseous implants: a pilot studyCLINICAL ORAL IMPLANTS RESEARCH, Issue 11 2008H. W. Anselm Wiskott Abstract Objectives: To validate an experimental setup designed to apply load onto bone tissue using osseointegrated implants in a rabbit model. Specifically, (1) to design an apparatus capable of generating controlled forces, (2) to assess implant placement, maintenance and loading and (3) to evaluate outcome variables using three radiological methods. Material and methods: New Zealand White rabbits were used. Two dental implants were inserted 15,18 mm apart in the animals' tibiae. After 3 months of healing, the implants were loaded normal to their long axes using a pneumatically activated device. A 15 min load regimen at 1 Hz was applied 5 days per week. Every week the applied load was increased by 5 N up to week 8 and by 10 N up to 100 N by week 14. Groups of animals (n=3) were sacrificed at load levels 25, 50 and 100 N. One unloaded controlateral implant in each group provided the baseline data. The rabbits were computer tomography (CT) scanned and radiographed using conventional frames every 4,5 weeks. After sacrifice, a volume of interest (VOI) located in the inter-implant zones and a VOI set as a ring surrounding the distal implant were analyzed using micro computer tomography (,CT). Results: A variety of osseous responses was observed, ranging from minor alterations to significant increases in porosity and lamelling of the cortical layer. ,CT data of the inter-implant VOI demonstrated an initial increase in total volume (upto 50 N) followed by stabilization. Concomitantly, bone volumetric density first decreased and then augmented until the end of the experiment. This phenomenon was not observed in the peri-implant VOI, for which volumetric density augmented from the beginning to the end of the experiment. Conclusions: 1. In future trials the loading devices must be constructed so as to sustain heavy cyclic loads over prolonged periods. 2. When properly handled, rabbits are cooperative animals in this application. In a third of the sites, signs of inflammation were observed. 3. In the inter-implant VOI, the cortical bone tended to react in two phases: first, as an increase in porosity and lamelling and second, as an augmentation of bone volumetric density. The peri-implant VOI adapted only by augmenting volumetric density. [source] | |||||||||||||||||||