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Biomedical subjects

R Bellotti

Publications and source records attributed to R Bellotti.

At least 19 recordsLinked to original sources
PubMed2006

A completely automated CAD system for mass detection in a large mammographic database.

Mass localization plays a crucial role in computer-aided detection (CAD) systems for the classification of suspicious regions in mammograms. In this article we present a completely automated classification system for the detection of masses in digitized mammographic images. The tool system we discuss consists in three processing levels: (a) Image segmentation for the localization of regions of interest (ROIs). This step relies on an iterative dynamical threshold algorithm able to select iso-intensity closed contours around gray level maxima of the mammogram. (b) ROI characterization by means of textural features computed from the gray tone spatial dependence matrix (GTSDM), containing second-order spatial statistics information on the pixel gray level intensity. As the images under study were recorded in different centers and with different machine settings, eight GTSDM features were selected so as to be invariant under monotonic transformation. In this way, the images do not need to be normalized, as the adopted features depend on the texture only, rather than on the gray tone levels, too. (c) ROI classification by means of a neural network, with supervision provided by the radiologist's diagnosis. The CAD system was evaluated on a large database of 3369 mammographic images [2307 negative, 1062 pathological (or positive), containing at least one confirmed mass, as diagnosed by an expert radiologist]. To assess the performance of the system, receiver operating characteristic (ROC) and free-response ROC analysis were employed. The area under the ROC curve was found to be Az = 0.783 +/- 0.008 for the ROI-based classification. When evaluating the accuracy of the CAD against the radiologist-drawn boundaries, 4.23 false positives per image are found at 80% of mass sensitivity.

Algorithms↗
PubMed2004

Topographic classification of EEG patterns in Huntington's disease.

The aim of this study is to perform a topographic classification of electroencephalographic (EEG) patterns in subjects affected by the Huntington's disease (HD). The alpha activity is a discriminating feature for HD, as its amplitude reduction turns out to be a clear mark of the illness. When used as input variable to a supervised neural network, a good classification of pathological patterns and control ones is achieved with high values of sensitivity and specificity. It should be useful to get more insight into the local discriminating capabilities of the alpha rhythm by implementing a neural network approach to classify EEG patterns extracted from groups of channels corresponding to specific regions of the scalp. Receiver operating characteristic (ROC) curve analysis enables one to label each region with the value of the area under the curve, thus providing a local significance for HD classification. A reduction of the area when processing regions of the scalp, with respect to the whole, suggests that all channels provide significant contribution to HD pattern discrimination. These results can be interpreted as an effect of an abnormal subcortical modulation of the alpha rhythm, due to the dysfunctional action of the thalamus on the cortical activities. In a further study, morphometric features of thalamus and basal ganglia, evaluated by MRI, will be matched with the electrophysiological findings.

Brain Mapping↗
PubMed2004

[Colon recanalization after Hartmann's procedure. A challenge for the surgeon or a strategy to be changed?].

AIM: Restoration of colorectal continuity is the second step of the procedure originally described by H. Hartmann for the treatment of sigmoid colon cancers. It is a safe, but complex procedure, that needs a meticulous surgical technique and is associated with a significant morbidity in as many as 40% of cases. For this reason, many patients are not submitted to reversal of the colostomy. METHODS: The authors report their experience: 32 patients underwent colostomy closure after Hartmann's procedure during the last 8 years. RESULTS: The mortality rate was nil, but post-operative complications occurred in 12 patients (37.5%), namely: wound infection (11 patients) and anastomotic leak (2 patients). CONCLUSION: In light of this, it could be wiser to perform, in the patients affected with benign pathology, and in those affected with limited malignant pathology (T3), resection of the diseased segment of colon and primary anastomosis with temporary ileostomy, reserving Hartmann's procedure to patients unsuitable to one step treatment because of their poor general and local conditions.

Adenocarcinoma↗
PubMed2003

Detection of subclinical brain electrical activity changes in Huntington's disease using artificial neural networks.

OBJECTIVE: The aim of this study was to analyze EEG background activity in Huntington's disease (HD) patients and relatives at risk, in relation to CAG repeat size and clinical state, in order to detect an electrophysiological marker of early disease. METHODS: We selected 13 patients and 7 subjects at risk. Thirteen normal subjects, sex- and age-matched, were also evaluated. Artifact-free epochs were selected and analyzed through Fast-Fourier Transform. EEG background activity was tested using both linear analysis and artificial neural network (ANN) classifier in order to evaluate whether EEG abnormalities were linked to functional changes preceding the onset of the disease. RESULTS: The most important EEG classification pattern was the absolute alpha power not correlated with cognitive decline. The ANN correctly classified 11/13 patients and 12/13 normals. Moreover, the neural scores for subjects at risk seemed to be correlated to the expected time before the onset of the disease. CONCLUSIONS: ANN is a very powerful method to discriminate between normals and patients. It could be used as an automatic diagnostic tool. EEG changes in positive gene-carriers for HD confirm an early functional impairment which should be taken into account in the genetic counseling and in the management of the early stages of the disease.

Adult↗
PubMed2000

First Mass-resolved Measurement of High-Energy Cosmic-Ray Antiprotons.

We report new results for the cosmic-ray antiproton-to-proton ratio from 3 to 50 GeV at the top of the atmosphere. These results represent the first measurements, on an event-by-event basis, of mass-resolved antiprotons above 18 GeV. The results were obtained with the NMSU-WIZARD/CAPRICE98 balloon-borne magnet spectrometer equipped with a gas-RICH (Ring-Imaging Cerenkov) counter and a silicon-tungsten imaging calorimeter. The RICH detector was the first ever flown that is capable of identifying charge-one particles at energies above 5 GeV. The spectrometer was flown on 1998 May 28-29 from Fort Sumner, New Mexico. The measured p&d1;/p ratio is in agreement with a pure secondary interstellar production.

Journal Article↗
PubMed2000

[Angiosarcoma of the breast after conservative surgery and radiotherapy for early breast carcinoma. Description of a case].

The occurrence of an angiosarcoma of the residual breast after conservative surgery and adjuvant radiotherapy for early mammary carcinoma is a very rare event. In western countries only 57 cases have been published in the literature (5 in Italy) since the first described case in 1987. Radiotherapy seems to be the most important etiological factor in the development of the neoplasm. Diagnosis is often delayed, owing to the "benign" aspect of the lesion. The only effective treatment is residual mastectomy, because chemotherapy is ineffective. The prognosis is often dismal, because of the aggressive behaviour of the lesion in most cases. The case of a patient with a multicentric secondary angiosarcoma of the breast recently operated on is described.

Aged↗
PubMed1999

Photic driving response in primary headache: diagnostic value tested by discriminant analysis and artificial neural network classifiers.

The aim of this study was to discriminate migraine patients (MWoA) from tension-type headache (TTH) patients and normals in order to confirm that the photic driving response in the medium frequency range is a marker of migraine and to test the hypothesis that MWoA and TTH are separate disorders based on electrophysiological pattern. We recruited 120 MWoA patients, 64 TTH patients, and 51 healthy controls without any history of headache or of migraine inheritance, according to International Headache Society (IHS) criteria. The classification method was discriminant analysis using both linear discriminant analysis with a stepwise selection of predictors and an artificial neural network classifier (NNs). The mean amplitude of the first harmonic elicited by flash stimulation in the 15-27 Hz range was significantly increased over Fp1, C3, C4, P4, O2, and O1 electrodes in MWoA and TTH patients in comparison with normal subjects. Using both classification methods, only the control subjects were correctly distinguished. When only the patient groups were matched, no significant difference was detectable. The increased brain response to visual stimulation detected in both migraine and TTH suggests a common neuronal dysfunction in the two headache subtypes.

Adolescent↗
PubMed1994

Individual housing modulates daily rhythms of hypothalamic catecholaminergic system and circulating hormones in adult male rats.

Circadian rhythms of hypothalamic catecholamines and their metabolites and of prolactin and corticosterone circulating hormones were determined over 24 h in group-housed (six per cage; control) and individually housed, 90-day-old male albino rats adapted to a 12:12 light/dark cycle. After 5 weeks of adaptation, in individually housed rats, norepinephrine (NE) turnover increased, since lower NE (p < 0.01) and higher MOPEG metabolite (p < 0.01) levels were measured. As concerns the dopaminergic system, individually housed rats increased both dopamine (DA) synthesis and turnover as revealed by higher DOPAC (p < 0.01) and HVA (p < 0.05) metabolites without modification of DA levels. Moreover, in individually housed rats, corticosterone (p < 0.01) and prolactin (p < 0.05) mean levels were higher than in the control group.

3,4-Dihydroxyphenylacetic Acid↗