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At least 883 records · Page 49Linked to original sources
PubMed2003

Classification of calcaneal fractures by spiral computed tomography: implications for surgical treatment.

The purpose of this study was to evaluate spiral computed tomography and multislice CT (SCT/MSCT) with multiplanar reconstructions (MPR) in the classification of calcaneal fractures according to a modified CT classification and to quantify fragment displacement to guide surgical treatment. Forty-eight calcaneal fractures were examined by spiral CT (1- to 2-mm slice thickness, pitch=1.5) with multiplanar reconstructions (MPR). Fractures were grouped according to a modified Munich classification scheme, differentiating six categories of fractures by joint involvement, number of fragments in the posterior facet, and the presence and extent of displacement. A qualitative and quantitative statement was made for the presence of clinical relevant displacement of the posterior articular facet (A: >2 mm), widening of the heel (B: crossing fibular reference line), reduction in calcaneal height (C: >10%), and axis shift of the calcaneocuboid angle (D: >10 degrees ). Treatment recommendations resulting from the CT classification were retrospectively compared with the treatment given by examining the patients' files. There were 10 extra-articular and 38 intra-articular fractures; 8 were in class I (extra-articular, nondisplaced), 2 in class II (extra-articular, displaced), 1 in class III (intra-articular, nondisplaced), 20 in class IV (two fragments), 9 in class V (three fragments), and 8 in class VI (>4 fragments), one of the latter being uncertain; 34 showed displacement of the articular facet, 35 widening of the heel, 35 reduction in calcaneal height, and 20 a shift of the axis. In 94% of the cases the procedure recommended by the Munich system of classification was followed; there was disagreement in 1 case in class I and 1 in class IV. Spiral CT allowed fracture classification and quantification of relevant displacement of fragments by radiologists. The implemented recommendations for treatment were adopted by surgeons in most cases.

Adolescent↗
PubMed2003

Sub-classification of low-grade cerebellar astrocytoma: is it clinically meaningful?

OBJECTIVES: The objectives were to identify prognostic factors for the survival of children with cerebellar astrocytoma, and to evaluate the reproducibility and prognostic value of histological sub-classification and grading. METHODS: Children aged 0-14 years treated in Denmark for a cerebellar astrocytoma in the period 1960-1984 were included and followed until January 2001 or until their death. The histological specimens from each patient were reviewed for revised grading and classification according to three different classification schemes: the WHO, the Kernohan and the Daumas-Duport grading systems. RESULTS: The overall survival rate was 81% after a follow-up time of 15-40 years. The significant positive prognostic factors for survival were "surgically gross-total removal" of the tumour at surgery and location of the tumour in the cerebellum proper as opposed to location in the fourth ventricle. No difference in survival time was demonstrated when we compared pilocytic astrocytoma and fibrillary astrocytoma. Moreover, we found that the Kernohan and the WHO classification systems had no predictive value and that the Daumas-Duport system is unsuitable as a prognostic tool for low-grade posterior fossa astrocytomas. CONCLUSION: Discordant observations due to interobserver variability make histological sub-classification of low-grade cerebellar astrocytomas in children insufficient for predicting prognosis and biological behaviour. Similar survival rates in a population of paediatric low-grade cerebellar astrocytomas of grades I and II indicate that tumour grade has no prognostic significance within this group of patients. "Surgically gross-total removal", especially if the tumour is located in the fourth ventricle is of the highest importance for long-term survival. Histological sub-classification of the tumours has no predictive value.

Adolescent↗
PubMed2003

Improving reliability in the classification of fractures of the acetabulum.

BACKGROUND: Plain radiographs of the pelvis are routinely used in the initial assessment of patients with suspected fractures of the acetabulum. It is necessary for orthopaedic resident trainees, emergency physicians as well as orthopaedic surgeons who infrequently treat trauma patients to be able to describe these fracture patterns reliably to traumatologist orthopaedic surgeons who ultimately take over the patient care. Our purpose was two-fold: (1) to determine the reliability of the component parts of the Letournel classification of acetabular fractures involving six anteroposterior (AP) radiographic lines, and (2) to examine whether the addition of oblique radiograph views (Judet views) would improve the reliability. METHODS: Thirty sets of AP and oblique radiographs (Judet views) of the pelvis were selected from a hospital database to represent various types of acetabular fractures. Six reviewers (three orthopaedic trainees and three community orthopaedic surgeons) independently reviewed the radiographs. For each radiograph, the reviewer classified the acetabular fracture according to the Letournel classification. In addition, each reviewer utilized a simplified classification scheme using six radiographic lines on the AP pelvic radiograph. Interobserver reliabilities among reviewers were reported along with the intraclass correlation coefficient (ICC) and kappa values. RESULTS: Agreement for the Letournel classification increased with increasing physician experience (trainees ICC=-0.14 and community surgeons ICC=0.56). Interobserver reliability between trainees and community surgeons improved when the six radiographic lines were used (range kappa=0.09-0.89). The oblique pelvic radiographs (Judet views) did not significantly improve reliability among physicians. CONCLUSIONS: In this study we report the following: (1) the reliability of the Letournel classification improves with level of training, (2) physicians with less experience with acetabular fractures have significantly better agreement in identifying fractures using the six radiographic lines on the AP film than the Letournel classification, and (3) agreement among the reviewers for the AP pelvic radiograph is not improved with additional oblique (Judet) views.

Acetabulum↗
PubMed1998

Neural cell classification by wavelets and multiscale curvature.

A new approach to automatic classification of retinal ganglion cells using multiscale techniques including the continuous wavelet transform, curvature, and standard pattern recognition techniques is described. Each neural cell is represented by its outer contour, and the wavelet transform is calculated from the complex signal defined by the aforementioned contour, leading to the so-called W-representation (Antoine et al. 1996). The normalized multiscale wavelet energy (NMWE) is used to define a set of shape measures associated with the number of details of the shape for a broad range of spatial scales. Next, the more discriminating NMWE coefficients are chosen through a feature ordering technique and fed to statistical classifiers. In addition, the normalized multiscale bending energy (NMBE) is discussed as a means of neural shape description for classification purposes based on the multiscale curvature, i.e. the curvegram, of the neural contour. It is shown that both shape descriptors are suitable for shape classification, presenting similar classification performance. In fact, NMBE has a slightly better recognition rate than NMWE in our experiments. On the other hand, NMWE is less computationally expensive than NMBE, presenting also the potentially useful property of allowing the use of more suitable different analyzing wavelets, depending on the problem under consideration. Therefore, both measures are related and provide a good framework for the design of neural cell description and classification. The methods described in this work have been successfully applied to the classification of two classes of cat retinal ganglion cells, namely alpha and beta (henceforth referred as alpha-cells and beta-cells, respectively), and three statistical classifiers were considered: minimum-distance, k-nearest neighbours and maximum likelihood. The mean recognition rates are near 90%, which is superior to the other shape measures considered. It is argued here that the proposed technique can be adopted as a new general methodology for multiscale shape analysis and recognition, being applicable also to other problems in biological shape characterization in neuroscience and general biomedical image analysis. In the context of analysis of shape complexity, the multiscale energies are coherent with subjective judgements by humans.

Animals↗
PubMed2006

A new international classification of childhood vasculitis.

There has been, for many years, a need for an acceptable classification of childhood vasculitis as well as criteria for classifying specific sub-categories of vasculitic disease affecting the young. Hitherto, there has been, with certain exceptions, much reliance on adult classification systems and criteria that have not proved entirely satisfactory. A recent International Consensus Conference held in Vienna in June 2005 attempted to rectify this state of affairs. It resulted in a new proposal for childhood vasculitis classification and proposals of classification criteria for several important categories of childhood vasculitis including Henoch-Schonlein purpura, Kawasaki disease, polyarteritis nodosa (with additionally definitions for cutaneous and microscopic polyarteritis), Wegener granulomatosis and Takayasu arteritis. The process involved the Delphi technique to gather a wide spectrum of opinion from pediatric rheumatologists and nephrologists followed by the Consensus Conference attended by a group of pediatricians with extensive vasculitis experience where nominal group techniques were utilized to agree on a general classification and classification criteria for individual childhood vasculitides. The consensus that was reached will hopefully provide pediatricians with a valuable tool in the study of childhood vasculitides but will require appropriate validation using patient and control groups.

Child↗
PubMed2001

Neurophysiological classification of ulnar entrapment across the elbow.

Ulnar nerve entrapment across the elbow (UAE), a common entrapment, requires neurophysiological evaluation for a diagnosis, but a standardised neurophysiological classification is not available. The aim of our study was to evaluate the validity of a neurophysiological classification of UAE, developed by us. To this end, we examined whether sensorimotor deficits, as observed by the physician and as referred by the patients, increased with the neurophysiological severity according to the classification. We performed a multiperspective assessment of 63 consecutive arms from 52 patients with a clinical diagnosis of UAE. Neurophysiological, clinical and patient-oriented validated measurements were used. The neurophysiological classification is based on the presence or absence of evoked responses and on the normality or abnormality of conduction findings. A strict relationship was observed between the degree of neurophysiological severity and the clinical findings (sensorimotor deficits). Moreover, a significant positive correlation between hand functional deficit and neurophysiological classification was observed. Conversely, a clear correlation between neurophysiological pattern and symptoms was not found. The neurophysiological classification is easy to use and reliable, but further multicentric studies should be performed.

Adult↗
PubMed2002

Endoscopic evaluation of the remnant stomach after gastrectomy: proposal for a new classification.

BACKGROUND: In Japan, approximately half of gastric cancers are diagnosed in the early stage. Longer survival has been provided for patients with early gastric cancer (EGC). Several new surgical procedures have been employed for some EGCs. To compare the functional results of these techniques with those of classic distal gastrectomy, it is important to evaluate the remnant stomach in relation to quality of life (QOL) and secondary cancers. We propose a new endoscopic classification, regarding several aspects of the remnant stomach, which enables common understanding and description of the condition. METHODS: Of 651 patients who underwent a distal gastrectomy or pylorus-preserving gastrectomy (PPG), 324 had at least one upper gastrointestinal (GI) endoscopy during the follow-up period. Ninety-three of the 324 patients underwent a Roux-en-Y reconstruction (RY); 175, Billroth type 1 (B1); and 56, PPG. Endoscopic findings regarding residual food, gastritis, and bile reflux in the gastric stump were investigated for these patients. We classified the amount of residual food into five grades, the degree and the extent of gastritis into five grades, and bile reflux into two grades. First, we evaluated the consistency of diagnosis between two endoscopists, in the first 200 patients, and then we applied the classification to all 324 patients to examine the usefulness of this classification. RESULTS: Consistency of diagnosis was obtained between two endoscopists who classified the patients independently. The agreement rate was 98.5% for residual food, 93% for gastritis, and 100% for bile reflux. Residual food was observed in 14.0% of the RY group, 22.3% of the B1 group, and 37.5% of the PPG group. These differences were significant (RY versus B1; P < 0.05 and RY versus PPG; P < 0.01). The remnant stomach after B1 showed significantly more severe and extensive gastritis than that after RY and PPG ( P < 0.01). As for bile reflux, there was no significant difference among the three groups. CONCLUSION: The classification (RGB classification: Residue, Gastritis, Bile) can be used easily and is practical. The results suggest some important differences among methods of reconstruction. This classification seems to be useful to describe these findings and to further evaluate these reconstructive methods.

Endoscopy, Gastrointestinal↗
PubMed2006

Characterization of Escherichia coli isolates from different fecal sources by means of classification tree analysis of fatty acid methyl ester (FAME) profiles.

Microbial source tracking (MST) methods need to be rapid, inexpensive and accurate. Unfortunately, many MST methods provide a wealth of information that is difficult to interpret by the regulators who use this information to make decisions. This paper describes the use of classification tree analysis to interpret the results of a MST method based on fatty acid methyl ester (FAME) profiles of Escherichia coli isolates, and to present results in a format readily interpretable by water quality managers. Raw sewage E. coli isolates and animal E. coli isolates from cow, dog, gull, and horse were isolated and their FAME profiles collected. Correct classification rates determined with leaveone-out cross-validation resulted in an overall low correct classification rate of 61%. A higher overall correct classification rate of 85% was obtained when the animal isolates were pooled together and compared to the raw sewage isolates. Bootstrap aggregation or adaptive resampling and combining of the FAME profile data increased correct classification rates substantially. Other MST methods may be better suited to differentiate between different fecal sources but classification tree analysis has enabled us to distinguish raw sewage from animal E. coli isolates, which previously had not been possible with other multivariate methods such as principal component analysis and cluster analysis.

Animals↗
PubMed1986

Evaluation of malignant lymphomas using three classifications and the working formulation. 482 cases with median follow-up of 11.9 years.

Three classifications and the Working Formulation for non-Hodgkin's lymphomas have been studied in 482 patients with a median follow-up of 11.9 years. Each classification was evaluated independently, and their similar and discrepant aspects were analyzed by comparing subgroups in the different schemes. Clinical staging was essential in the evaluation of some categories. There are several differences between the classifications that are not readily reconcilable. The Rappaport classification's principal groups are heterogeneous. Separation of follicular lymphomas into small and large cleaved cell types (Lukes-Collins) is significant. The addition of a follicular mixed cell type (Rappaport, Working Formulation) detracts from this significance. Centrocytic and lymphoplasmacytic tumors (Kiel) are well-defined categories and important in understanding some deficiencies in the other classifications. The small cleaved cell type, diffuse (Lukes-Collins, Working Formulation) is heterogeneous. Diffuse lymphomas of mixed cell types are poorly defined subgroups. Excluding lymphoblastic types, the presence of plasmacytic differentiation is important in identifying the high-grade lymphomas with the poorest prognosis. These results suggest that adjustments should be made in the classifications and in the Working Formulation.

Adolescent↗
PubMed1993

Interobserver variation using the AO/ASIF classification of long bone fractures.

A comprehensive classification system has been proposed by the AO/ASIF Foundation for the classification of long bone fractures. After an explanatory talk and with the aid of an illustrated pamphlet, 18 orthopaedic surgeons were asked to classify 10 long bone fractures according to the AO system. Three of the participating surgeons had previous experience of the classification system. After individual classification, a consensus classification was derived and the results of the individual and consensus codings were compared. Only 32 per cent of all codings agreed with the final consensus. There was no difference between the surgeons with previous experience of the system (66 per cent) and novice coders (69 per cent) in the number of inaccurate codes when compared with the consensus codes. Reasons for error in coding are discussed. It is recommended that if the AO system is used for the purposes of research and computer-based audit, a consensus of opinion is used as the basis of classification.

Femoral Fractures↗
PubMed1977

Influence of population on the classification of ECG-VCG's using linear regression techniques.

This paper describes the influence of different populations on statistical multivariate classification rules and classification results where the word "population" refers only to the frequency of diagnoses to be expected, the so-called prior probabilities. Using linear regression as a multivariate classification technique and six groups consisting of five pathological conditions and normals as test data, it has been shown: (a) That the population influences to a great extent the selection of the best ECG-VCG measurements for the classification rule. (b) That a mismatch of the populations in the learning and test sets can considerably decrease the number of correct classifications. (c) That a certain correction of the mismatch can be achieved when the prior probabilities in the learning and test sets are known, Further, the paper discusses the change of prior probabilities over the years at the Variety Club Heart Hospital in the University of Minnesota and its effect on the performance of the classification algorithm which has been used.

Electrocardiography↗
PubMed1988

Perceptual sensitivity to dimensional and similarity relations in free and rule-governed classifications.

Two experiments were conducted to investigate the perceptual primacy of dimensional and similarity relations in the stimulus classifications of younger and older subjects. In Experiment 1, 4- and 10-year-olds were given free classifications in which they could group stimuli according to overall similarity or identities in size, color, or orientation. Both age groups classified stimuli most frequently according to identities on separate dimensions. In Experiment 2, 4-year-olds and adults were given free classifications followed by rule-governed classifications which required them to group stimuli according to specific relations. In the free classifications, a majority of subjects in both age groups classified the stimuli most frequently according to identities on separate dimensions. In the rule-governed classifications, both age groups were more accurate when a single separate relation was required for solution than when overall similarity was required. These results support a differential-sensitivity view of perceptual development, which asserts that individuals at all ages primarily perceive and use separate relations.

Adolescent↗
PubMed1986

Classification of fetal and neonatal heart rate patterns in relation to behavioural states.

For the assessment of behavioural states in the human fetus, the fetal heart rate (FHR) pattern is one of the state variables. A statistical method is described to classify FHR patterns. FHR recordings were made between 38 and 40 wk gestation. The tachogram was averaged over 3-s intervals. For FHR segments of 3 min duration the parameters of an autoregressive-moving average (ARMA) model were estimated. Simulated FHR patterns, generated by using these estimated ARMA parameters, resembled real recordings. The ARMA parameters were used as features for a retrospective classification of the FHR segments, using a linear discriminant function. The classification by the above method was compared with an independent visual classification of the FHR patterns. The computer/observer classification agreement was 85% (kappa = 0.70). These data were compared with classification results for neonatal heart rate segments. For prospective classification of FHR patterns a moving discriminant function was introduced.

Behavior↗
PubMed1984

A clinicopathologic study in advanced non-Hodgkin's lymphomas treated with sequential non-cross-resistant regimens: comparison of the working formulation with the Rappaport and Kiel classifications.

One-hundred and ninety-four adult patients with histologically proven stage III and IV non-Hodgkin's lymphomas, treated with CVP (cyclophosphamide, vincristine and prednisone) alternated with ABP (adriamycin, bleomycin and prednisone), were analyzed to test the validity of the clinicoprognostic correlation offered by the working formulation in comparison with the Rappaport and Kiel classifications. Actuarial overall survival at 5 yr showed a significant difference among the three prognostic subgroups of the working formulation (low grade, 53.3%; intermediate grade, 47.5%; high grade, 27.7%). Overall survival of favorable subgroups of the Rappaport and Kiel classifications was superior to that of unfavorable prognostic groups. The percentage of systemic symptoms and bulky disease increased in patients with low-grade compared to those with intermediate-grade and intermediate-to-high-grade malignancy. The achievement of complete remission was not related to any of the prognostic groups of the Working Formulation, and no difference could be detected within the various prognostic groups of the Rappaport and Kiel classifications. Within the diffuse histiocytic lymphomas of the Rappaport classification, two groups with a different prognostic outcome were evidenced by the working formulation (G, with an overall survival of 50%, and H, with an overall survival of 26.7% at 5 yr) and by the Kiel classification. The possibility of reporting results in the three different groups of the working formulation instead of two can be considered a step forward. Within the diffuse histiocytic histology, the working formulation allows separation, as does the Kiel classification, into two main different prognostic subgroups.

Adolescent↗
PubMed1985

Cross-validation of the Back Pain Classification Scale with chronic, intractable pain patients.

The current study investigated the utility of the Back Pain Classification Scale with chronic, intractable low back pain and headache patients. Subjects consisted of 50 chronic low back pain and 50 chronic headache patients referred to a university based Pain Center for evaluation. Data indicated that subjects were a representative sample of severely intractable chronic pain patients typically referred for Pain Center evaluation and treatment. Each was administered the Back Pain Classification Scale as part of a thorough physical and psychological/behavioral evaluation. All subjects were classified by blind review of medical records into one of two categories: (1) presence of psychopathologically based pain complaint with little or no pathophysiological findings and (2) presence of pathophysiologically based pain complaints with little or no psychopathological findings. Subjects were also independently classified from blind review of their scores on the Back Pain Classification Scale into one of these two categories. Findings revealed that the Back Pain Classification Scale accurately predicted the actual classification of 80% of the low back pain patients (i.e., 30% above baseline prediction rate) and only 60% of the chronic headache patients (i.e., only equal to the baseline prediction rate). Furthermore, the scale was found to be most accurate in predicting low back pain patients with primary psychopathologically based pain. It was concluded that the Back Pain Classification Scale was an empirically valid instrument to use with chronic low back pain patients, but not with chronic headache patients. This lack of utility with chronic headache patients was also viewed as support for the construct validity of the scale. Wider use of the scale with chronic low back pain patients was suggested.

Adult↗
PubMed1996

Classification systems of soft tissue disorders of the neck and upper limb: do they satisfy methodological guidelines?

A critical appraisal of existing classifications of soft tissue disorders of the neck and upper limb was performed utilizing methodological criteria including appropriateness for purpose, validity, reliability, feasibility, and generalizability. Five classifications were assessed independently by three raters using standardized forms. For those criteria that can be assessed by inspection of the classification itself, none of the classification systems appeared acceptable for reasons such as failure to be comprehensive, overlap of categories, and lack of demonstration that the criteria for inclusion into the categories are valid and reliable. No judgement could be passed about those criteria that require formal testing, such as reliability and construct validity, because of the absence of data. The overall interrater reliability of the critical appraisal was high, with an intraclass correlation coefficient of 0.82. The validity of studies that have relied upon existing classifications of soft tissue disorders of the neck and upper limb to group the entities under study is questioned in light of the findings of this study. Future work should be directed toward improving existing classification systems and/or developing new ones that fulfil basic measurement criteria.

Arm↗
PubMed2004

Brain tumor classification based on long echo proton MRS signals.

There has been a growing research interest in brain tumor classification based on proton magnetic resonance spectroscopy (1H MRS) signals. Four research centers within the EU funded INTERPRET project have acquired a significant number of long echo 1H MRS signals for brain tumor classification. In this paper, we present an objective comparison of several classification techniques applied to the discrimination of four types of brain tumors: meningiomas, glioblastomas, astrocytomas grade II and metastases. Linear and non-linear classifiers are compared: linear discriminant analysis (LDA), support vector machines (SVM) and least squares SVM (LS-SVM) with a linear kernel as linear techniques and LS-SVM with a radial basis function (RBF) kernel as a non-linear technique. Kernel-based methods can perform well in processing high dimensional data. This motivates the inclusion of SVM and LS-SVM in this study. The analysis includes optimal input variable selection, (hyper-) parameter estimation, followed by performance evaluation. The classification performance is evaluated over 200 stratified random samplings of the dataset into training and test sets. Receiver operating characteristic (ROC) curve analysis measures the performance of binary classification, while for multiclass classification, we consider the accuracy as performance measure. Based on the complete magnitude spectra, automated binary classifiers are able to reach an area under the ROC curve (AUC) of more than 0.9 except for the hard case glioblastomas versus metastases. Although, based on the available long echo 1H MRS data, we did not find any statistically significant difference between the performances of LDA and the kernel-based methods, the latter have the strength that no dimensionality reduction is required to obtain such a high performance.

Artificial Intelligence↗
PubMed2004

Diagnosis of gastric carcinoma by classification on feature projections.

A new classification algorithm, called benefit maximizing classifier on feature projections (BCFP), is developed and applied to the problem of diagnosis of gastric carcinoma. The domain contains records of patients with known diagnosis through gastroscopy results. Given a training set of such records, the BCFP classifier learns how to differentiate a new case in the domain. BCFP represents a concept in the form of feature projections on each feature dimension separately. Classification in the BCFP algorithm is based on a voting among the individual predictions made on each feature. In the gastric carcinoma domain, a lesion can be an indicator of one of nine different levels of gastric carcinoma, from early to late stages. The benefit of correct classification of early levels is much more than that of late cases. Also, the costs of wrong classifications are not symmetric. In the training phase, the BCFP algorithm learns classification rules that maximize the benefit of classification. In the querying phase, using these rules, the BCFP algorithm tries to make a prediction maximizing the benefit. A genetic algorithm is applied to select the relevant features. The performance of the BCFP algorithm is evaluated in terms of accuracy and running time. The rules induced are verified by experts of the domain.

Adolescent↗