Biomedical subjects

D Cavouras

Publications and source records attributed to D Cavouras.

49 records · Page 3Linked to original sources

PubMed1995

The size of the intra- and extraventricular cerebrospinal fluid compartments in children with idiopathic benign widening of the frontal subarachnoid space.

The aim of this study was to quantify the intra- and extraventricular cerebrospinal fluid (CSF) spaces in children with benign enlargement of the frontal subarachnoid space (BE). The infra- and supratentorial CSF compartments were measured in 61 CT examinations of children with BE, 3-27 months old, and compared with those of 96 CT examinations considered normal. Measurements of the ventricular system, and the pontine and chiasmatic cisterns were related to cranial size. In all children with BE the lateral and third ventricles were dilated and the chiasmatic cistern was widened. The subarachnoid space was wider than the upper limits in the control group, in the frontal region (4 mm), and the anterior interhemispheric (4 mm) and Sylvian (3 mm) fissures. The infratentorial CSF compartments, the occipital subarachnoid space, the posterior part of the interhemispheric fissure and, in most cases, the cortical sulci were normal in size in children with BE. The majority were macrocephalic or had rapid head growth but there were also normocephalic children with normal head growth. The size of the posterior fossa was within the normal range in all children with BE. Idiopathic BE is not uncommon in children up to about 3 years old who are healthy or have minimal neurological disturbance and is characterised by a specific pattern of widening of the supratentorial CSF compartments.

Cephalometry↗

PubMed1994

CT evaluation of normal CSF spaces in children: relationship to age, gender and cranial size.

The extent of the cerebrospinal fluid (CSF) spaces was measured in 247 CT examinations, reported as normal, in children aged 3 months to 14 years. The measurements of the CSF compartments were divided by the sum of the transverse and longitudinal internal cranial diameters in the corresponding CT section, in order to take into account the size and shape of the growing skull. All CSF spaces were relatively larger in the younger (< or = 3 years) than in the older children, but did not differ between boys and girls, since the cranial size was taken into account. The CSF compartments increased in a non-uniform manner during the first 3 years of life, but after the age of four they developed uniformly and in parallel with the growing skull. Measurements of the subarachnoid spaces formed an age-related table, which may be of value when interpreting brain CT examinations of children.

Adolescent↗

PubMed1994

Renal parenchymal thickness in children measured by computed tomography.

Renal parenchymal thickness was measured at different regions and levels through the kidney in 162 abdominal computed tomography (CT) examinations of children 5 months to 14 years old. The transverse diameter of the first lumbar vertebra (L1) was also measured, in order to take into account the child's body habitus. All patients were examined with an indication other than renal disease and had no abnormal CT findings in the retroperitoneum. Renal parenchyma increased in parallel with the transverse diameter of L1 and did not depend on age or sex in children of the same body format. There were no significant differences in size between the right and the left kidneys. Renal measurements were tabulated on reference tables, as an aid in the assessment of renal parenchymal thickness in children undergoing abdominal CT examination.

Adolescent↗

PubMed1994

CT assessment of normal splenic size in children.

The size of the normal spleen was estimated by CT in 153 children examined with indication unrelated to splenic disease. In each patient the width, thickness, length and volume of the spleen were calculated. Measurements were also normalized to the transverse diameter of the body of the first lumbar vertebra. The spleen underwent significant growth during the first 4 years of life and reached maximum size at the age of 13. There was no differences in splenic volume between boys and girls. Splenic thickness correlated best with normal splenic volume. The strongest correlation was also found between splenic thickness and volume in a group of 45 children with clinically evident splenomegaly. Splenic thickness, an easy-to-use measurement, may be employed in everyday practice to represent splenic volume on CT.

Adolescent↗

PubMed1993

Pre- and post-nephrectomy kidney enlargement in patients with contralateral renal cancer.

Pre- and post-nephrectomy kidney growth was studied by computed tomography (CT) in 32 patients with contralateral renal cancer. Kidney enlargement was assessed by comparing the size of the unaffected kidney, in 32 pre- and 61 post-nephrectomy CT examinations, with the corresponding normal size, determined from 120 CT examinations of binephric individuals with no renal disease. The unaffected kidney was found to be 36% larger 1 month before nephrectomy and 54, 62 and 47% in the 1st, 2nd, and 3rd postoperative year, respectively. Compensatory renal growth was influenced both by contralateral cancer and nephrectomy and did not depend on the patient's age or sex.

Adult↗

PubMed1992

CT evaluation of compensatory renal growth in relation to postnephrectomy time.

In 27 patients nephrectomized for renal carcinoma, the compensatory hypertrophy of the remaining kidney was assessed by 72 CT examinations performed one month before and during 32 months after nephrectomy. Kidney size was estimated on CT by multiple measurements of the renal parenchymal thickness. Kidney growth was evaluated by comparing the amount of renal parenchyma before and after contralateral nephrectomy. Renal compensatory hypertrophy varied with postnephrectomy time. Kidney enlargement was 15% in the first 3 months, reached maximum 30% about a year later, and was reduced to 5%, 2 1/2 years postoperatively.

Adult↗

PubMed1990

The thickness of the renal parenchyma decreases with age: a CT study of 360 patients.

Renal parenchymal thickness was estimated by using CT in 360 patients with no evidence of renal disease. In each patient, the measurements were normalized to the transverse diameter of the vertebral body and a reference table was formulated. The renal parenchymal thickness decreases about 10% per decade of increasing age in both men and women. These findings are consistent with previously reported findings based on autopsy material. The proposed table may be useful as a criterion for assessing normal renal parenchyma on CT.

Adult↗

PubMedDate not supplied

Interposition of the colon between the kidney and the psoas muscle: a normal anatomic variation studied by CT.

The position of the bowel in the pararenal space was examined in relation to the kidney and the psoas muscle in 1203 abdominal computed tomographic (CT) examinations. The ascending colon was found between the lower kidney pole and the psoas muscle in 1.7% and the descending colon in 0.7% of the patients. This variation appeared more frequently in women, young adults, and individuals with less intrabdominal fat. Lateral displacement of the lower kidney pole was observed in 40% of the patients with this normal variation. These findings may be of value when interpreting urographic and abdominal CT examinations.

Adult↗

PubMedDate not supplied

A study of the variation of colonic positioning in the pararenal space as shown by computed tomography.

In a review of 1708 consecutive CT examinations of the abdomen the position of the ascending and descending colon in relation to the posterior and lateral edge of the kidney was studied. It was found that part of the colon was positioned posterior or posterolateral to the kidney's edge in percentages that varied between 14.2% and 0.9% in the different sex groups at the levels of upper, mid- and lower poles of the right and left kidney. It is concluded that this anatomical variation should be known if colon perforation is to be avoided during percutaneous nephrostomy or biopsy.

Adult↗

PubMedDate not supplied

Image analysis methods for solitary pulmonary nodule characterization by computed tomography.

Computer software was designed for classifying solitary pulmonary nodules (SPNs) into benign and malignant from their CT images, using image analysis methods. The system made use of three features, computed from the CT density matrix of the SPN, and a class-discriminating algorithm. System evaluation was performed on 51 histologically confirmed SPNs of indeterminate CT diagnosis. Overall classification accuracy in distinguishing benign and malignant SPNs was 90.2%, while 83.3% of the benign and 93.9% of the malignant SPNs were correctly classified. The proposed system may be of value to the radiologist in assessing the probability of malignancy in patients with a solitary pulmonary nodule.

Adult↗

PubMedDate not supplied

Computer-based grading of haematoxylin-eosin stained tissue sections of urinary bladder carcinomas.

PURPOSE: A computer-based image analysis system was developed for assessing the malignancy of urinary bladder carcinomas in a more objective manner. Tumours characterized in accordance with the WHO grading system were classified into low-risk (grades I and II) and high-risk (grades III and IV). MATERIALS AND METHODS: Images from 92 haematoxylin-eosin stained sections of urinary bladder carcinomas were digitized and analysed. An adequate number of nuclei were segmented from each image for morphologic and textural analysis. Image segmentation was performed by an efficient algorithm, which used pattern recognition methods to automatically characterize image pixels as nucleus or background. Image classification into low-risk or high-risk tumours was performed by means of the quadratic non-linear Bayesian classifier, which was designed employing 36 textural and morphological features of the nucleus. RESULTS: Automatic segmentation of nuclei on all images was about 90% on average. Overall system accuracy in correctly classifying tumours into low-risk or high-risk was 88%, employing the leave-one-out method and the best combination of three textural and one morphological feature. Classification accuracy for low-risk tumours was 88.8% and for high-risk tumours 86.2%. CONCLUSION: The proposed image analysis system may be of value to the objective assessment of the malignancy of urine bladder carcinomas, since it relies on nuclear parameters that are employed in visual grading and their prognostic value has been proved.

Algorithms↗

PubMedDate not supplied

Computer image analysis of brain CT images for discriminating hypodense cerebral lesions in children.

A computer software system was designed for the automatic discrimination of focal oedemas from local glioses in brain CT examinations. Image analysis methods were applied to the images of 77 CT examinations of children with focal oedemas (42) or local glioses (35). Textural features derived from the co-occurrence matrix of the lesion's image and a neural network classifier (the multilayer perceptron) were employed for the design of the system. Best classification accuracy (89.6%) was achieved by two textural features (contrast-difference entropy), one hidden layer and three hidden nodes of the classifier. The proposed software system provides new textural information and may be of value to the radiologist in differentiating focal oedemas from local glioses, especially in small lesions, where other radiological criteria are not evident.

Brain↗

PubMedDate not supplied

A network-based training environment: a medical image processing paradigm.

The capability of interactive multimedia and Internet technologies is investigated with respect to the implementation of a distance learning environment. The system is built according to a client-server architecture, based on the Internet infrastructure, composed of server nodes conceptually modelled as WWW sites. Sites are implemented by customization of available components. The environment integrates network-delivered interactive multimedia courses, network-based tutoring, SIG support, information databases of professional interest, as well as course and tutoring management. This capability has been demonstrated by means of an implemented system, validated with digital image processing content, specifically image enhancement. Image enhancement methods are theoretically described and applied to mammograms. Emphasis is given to the interactive presentation of the effects of algorithm parameters on images. The system end-user access depends on available bandwidth, so high-speed access can be achieved via LAN or local ISDN connections. Network based training offers new means of improved access and sharing of learning resources and expertise, as promising supplements in training.

Computer Communication Networks↗