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Biomedical subjects

Giovanni Pellacani

Publications and source records attributed to Giovanni Pellacani.

28 records · Page 2Linked to original sources
PubMed2004

Is JPEG compression of videomicroscopic images compatible with telediagnosis? Comparison between diagnostic performance and pattern recognition on uncompressed TIFF images and JPEG compressed ones.

Early melanoma diagnosis is an important goal for dermatologists. Polarized light systems are increasingly employed for dermatoscopic diagnosis of melanocytic lesions. For the purpose of teledermoscopy, whose importance is increasingly growing for consultation and teaching purposes, it is of utmost importance to establish whether, after compression, polarized light images maintain their informativeness. The aim of our study was to check the effects of compression on melanocytic lesion images acquired by means of a digital videomicroscope on the identification of morphological details of the image and on diagnostic accuracy. A total of 170 50-fold-magnified pigmented skin lesion images, acquired in Tagged Image File Format (TIFF) by a digital videomicroscope, were compressed using Joint Photographic Experts Group (JPEG) algorithms (compression factor 30). Two experts in videomicroscopy evaluated both original and compressed images twice by describing single lesion features and expressing a diagnosis. Reproducibility in the assessment of dermoscopic parameters and observer performance were studied by kappa statistics and Receiver Operating Characteristic (ROC) analysis. Both intra- and interobserver reproducibility in the assessment of morphological details were higher when TIFF images were considered, indicating a better image quality. Nonetheless, there was no significant difference in the diagnostic accuracy between uncompressed images and compressed ones, although the intraobserver reproducibility in the diagnostic judgement was higher for uncompressed images. Despite loss in image details, factor 30 compressed videomicroscopic images enable a good diagnostic accuracy.

Algorithms↗
PubMed2004

Automated description of colours in polarized-light surface microscopy images of melanocytic lesions.

The aim of this study was to develop a computerized method for the identification and description of colour areas in melanocytic lesion images based on an approach mimicking the human perception of colours. A colour palette comprising six colour groups (black, dark brown, light brown, blue-grey, red and white) was created by selecting single colour components within melanocytic lesion images acquired using a digital videomicroscope, and was implemented in the image analysis program. For each colour region, the area, the distance from the lesion centroid, the spread, the colour area distribution in the internal and the external part of the lesion, and asymmetries were assessed on 604 melanocytic lesion images in our image database. Black, white and blue-grey colour areas were detected more frequently in melanomas compared with naevi. Moreover, significant differences in colour descriptors were observed for each colour group, showing that colour areas are more unevenly distributed in melanomas compared with naevi. Using a discriminant analysis approach, the extension of dark, white and blue-grey areas and some descriptors of the distribution of the colour areas were identified as the most relevant colour parameters for differentiating between benign and malignant lesions. In conclusion, our automatic procedure breaks down the image into the colour areas used in the clinical examination process, and also supplies a description of their extension and distribution, with parameters that correlate with the clinical concepts of regularity and homogeneity.

Automation↗
PubMed2004

Noninvasive imaging of skin tumors.

In this article, the authors review different approaches to the diagnosis of skin tumors using noninvasive diagnostic tools, which are becoming increasingly reliable and, as a consequence, increasingly popular among physicians and patients. Especially in the realm of pigmented skin lesions, dermoscopy and sonography may add useful information to the clinical constellation, improving the diagnostic performance for early diagnosis of melanoma and for differentiating various melanocytic and nonmelanocytic pigmented lesions. More recently, confocal scanning laser microscopy was introduced as a novel technique that enables the in vivo study of the skin at a nearly histologic resolution, being of diagnostic value in various skin disorders, including basal cell carcinoma and pigmented skin lesions. These modalities have various other potential applications besides diagnosis, including lesion's selection for biopsy, determination of appropriate therapeutic modalities, verification of treatment efficacy, and decision of surgical margins. Finally, a hint to the use of cytodiagnosis for basal cell carcinoma is provided.

Basal Cell Carcinoma↗
PubMed2004

Automated extraction and description of dark areas in surface microscopy melanocytic lesion images.

BACKGROUND: Identification of dark areas inside a melanocytic lesion (ML) is of great importance for melanoma diagnosis, both during clinical examination and employing programs for automated image analysis. OBJECTIVE: The aim of our study was to compare two different methods for the automated identification and description of dark areas in epiluminescence microscopy images of MLs and to evaluate their diagnostic capability. METHODS: Two methods for the automated extraction of 'absolute' (ADAs) and 'relative' dark areas (RDAs) and a set of parameters for their description were developed and tested on 339 images of MLs acquired by means of a polarized-light videomicroscope. RESULTS: Significant differences in dark area distribution between melanomas and nevi were observed employing both methods, permitting a good discrimination of MLs (diagnostic accuracy = 74.6 and 71.2% for ADAs and RDAs, respectively). CONCLUSIONS: Both methods for the automated identification of dark areas are useful for melanoma diagnosis and can be implemented in programs for image analysis.

Diagnosis, Differential↗
PubMed2003

Preoperative melanoma thickness determination by 20-MHz sonography and digital videomicroscopy in combination.

OBJECTIVE: To identify accurately thick melanomas preoperatively by means of a combined approach based on sonography and clinical-videomicroscopic evaluation. DESIGN: Ultrasonographic thickness measurement, obtained by means of a 20-MHz B-scanner, and identification of clinical and videomicroscopic variables useful in distinguishing between thick and thin melanomas were performed on a training set of 40 melanomas. An algorithm based on echographic, clinical, and videomicroscopic criteria was constructed to develop a method for preoperative evaluation of melanoma thickness and was validated on a test set of 48 melanomas. SETTING: University medical department. PATIENTS: Eighty-eight patients affected by primary cutaneous melanoma. MAIN OUTCOME MEASURES: Sensitivity and specificity of the algorithm, with the use of sonographic, clinical, and videomicroscopic data, in thick melanoma identification. RESULTS: Echographic thickness was calculated for each lesion. On the training set, 2 clinical and 7 videomicroscopic features were identified for distinction between thick and thin melanomas: nonpalpability, central pigment network, central brown globules, and blotches were characteristic of thin melanomas; clinical regression, localized peripheral pigment network, veil, grayish polygonal areas, and blood vessels were characteristic of thick ones. A coefficient was attributed to each variable and a score was obtained for each lesion. The algorithm, developed for preoperative thickness prediction, was validated on the test set, enabling the distinction of thick melanomas with an 86.7% sensitivity and a 100% specificity. CONCLUSION: The correct classification of all thin melanomas as such renders this approach suitable in clinical practice.

Algorithms↗
PubMed2003

Polarized light-surface microscopy for description and classification of small and medium-sized congenital melanocytic naevi.

Owing to a lack of well-defined clinical criteria for identifying congenital lesions, the diagnosis of small and medium-sized congenital melanocytic naevi is always uncertain. Our aim was to describe the features of small congenital melanocytic naevi, as observed by digital videomicroscopy, with the purpose of identifying single patterns characteristic of small congenital melanocytic naevi or different morphological subgroups. We could then perform a classification based on their macroscopic and surface microscopic aspects. Digital images referring to 154 small congenital melanocytic naevi and to 150 acquired naevi were examined for pattern analysis. New features characterizing small congenital melanocytic naevi, such as target network, target globules, target vessels and focal thickening of network lines, were identified, and a subdivision of small congenital melanocytic naevi into different subgroups was performed. Discriminant analysis enabled the distinction between congenital and common naevi with a sensitivity of 82.5% and a specificity of 64%. Small congenital melanocytic naevi can be described and classified by digital videomicroscopy and pattern analysis. The most important discriminant features are target network, small globules, follicles and vessels. This classification may represent a useful tool in the follow-up of small congenital melanocytic naevi.

Adolescent↗
PubMed2003

A new algorithm for border description of polarized light surface microscopic images of pigmented skin lesions.

The aim of this study was to provide mathematical descriptors for the border of pigmented skin lesion images and to assess their efficacy for distinction among different lesion groups. New descriptors such as lesion slope and lesion slope regularity are introduced and mathematically defined. A new algorithm based on the Catmull-Rom spline method and the computation of the gray-level gradient of points extracted by interpolation of normal direction on spline points was employed. The efficacy of these new descriptors was tested on a data set of 510 pigmented skin lesions, composed by 85 melanomas and 425 nevi, by employing statistical methods for discrimination between the two populations.

Algorithms↗
PubMedDate not supplied

Skin cancer day in Italy: method of referral to open access clinics and tumor prevalence in the examined population.

Education campaigns to encourage self-examination coupled with rapid access to specialized dermatological clinics is considered the key strategy in the realization of early detection of cutaneous melanoma and non-melanoma skin cancer (NMSC). An alternative to an initial visit to the family doctor is open access to a skin cancer clinic at the decision of the individual. This approach has been followed mainly in countries with high melanoma incidence where the majority of the population is of northern European origin. However, the efficacy of this system has not been well established because there are few studies involving systematic follow up of individuals with positive screening through pathological confirmation of the diagnosis. We report the follow up data focussed on melanoma and NMSC detection rates in more than 1,000 subjects examined at numerous 1-day, open access clinics on the occasion of the Italian nation-wide "Skin Cancer Day" campaign promoted by the Federation of Italian Dermatological Societies. Total body skin examination was performed on all subjects, and surgical excision of a lesion was recommended in 41 of the 1042 subjects (3.9 %). Histologic diagnosis, available for 39/41 lesions, evidenced 3 superficial spreading melanomas (1 in situ, one "thin" lesion, ie. 0.30 mm in thickness, and one "thick" lesion, with a thickness of 4.53 mm) and 6 NMSC (5 BCC and 1 SCC). Thus, the prevalence of skin cancer (melanoma and NMSC) in this group was 0.8 % (9/1042), and the prevalence of melanoma was 3/1042, 0.2 %, rather similar to that found in populations of northern European origin. Open access to skin cancer clinics may represent an alternative approach to melanoma prevention also in southern European populations. Increased public awareness regarding skin cancer probably represents the main effect of this type of campaign.

Adult↗