65 research outputs found

    A review of the quantification and classification of pigmented skin lesions: from dedicated to hand-held devices

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    In recent years, the incidence of skin cancer caseshas risen, worldwide, mainly due to the prolonged exposure toharmful ultraviolet radiation. Concurrently, the computerassistedmedical diagnosis of skin cancer has undergone majoradvances, through an improvement in the instrument and detectiontechnology, and the development of algorithms to processthe information. Moreover, because there has been anincreased need to store medical data, for monitoring, comparativeand assisted-learning purposes, algorithms for data processingand storage have also become more efficient in handlingthe increase of data. In addition, the potential use ofcommon mobile devices to register high-resolution imagesof skin lesions has also fueled the need to create real-timeprocessing algorithms that may provide a likelihood for thedevelopment of malignancy. This last possibility allows evennon-specialists to monitor and follow-up suspected skin cancercases. In this review, we present the major steps in the preprocessing,processing and post-processing of skin lesion images,with a particular emphasis on the quantification andclassification of pigmented skin lesions. We further reviewand outline the future challenges for the creation of minimum-feature,automated and real-time algorithms for the detectionof skin cancer from images acquired via common mobiledevices

    The role of spectrophotometry in the diagnosis of melanoma

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    Background. Spectrophotometry (SPT) could represent a promising technique for the diagnosis of cutaneous melanoma (CM) at earlier stages of the disease. Starting from our experience, we further assessed the role of SPT in CM early detection. Methods. During a health campaign for malignant melanoma at National Cancer Institute of Naples, we identified a subset of 54 lesions to be addressed to surgical excision and histological examination. Before surgery, all patients were investigated by clinical and epiluminescence microscopy (ELM) screenings; selected lesions underwent spectrophotometer analysis. For SPT, we used a video spectrophotometer imaging system (Spectroshade® MHT S.p.A., Verona, Italy). Results. Among the 54 patients harbouring cutaneous pigmented lesions, we performed comparison between results from the SPT screening and the histological diagnoses as well as evaluation of both sensitivity and specificity in detecting CM using either SPT or conventional approaches. For all pigmented lesions, agreement between histology and SPT classification was 57.4%. The sensitivity and specificity of SPT in detecting melanoma were 66.6% and 76.2%, respectively. Conclusions. Although SPT is still considered as a valuable diagnostic tool for CM, its low accuracy, sensitivity, and specificity represent the main hamper for the introduction of such a methodology in clinical practice. Dermoscopy remains the best diagnostic tool for the preoperative diagnosis of pigmented skin lesions

    Incorporating Colour Information for Computer-Aided Diagnosis of Melanoma from Dermoscopy Images: A Retrospective Survey and Critical Analysis

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    Cutaneous melanoma is the most life-threatening form of skin cancer. Although advanced melanoma is often considered as incurable, if detected and excised early, the prognosis is promising. Today, clinicians use computer vision in an increasing number of applications to aid early detection of melanoma through dermatological image analysis (dermoscopy images, in particular). Colour assessment is essential for the clinical diagnosis of skin cancers. Due to this diagnostic importance, many studies have either focused on or employed colour features as a constituent part of their skin lesion analysis systems. These studies range from using low-level colour features, such as simple statistical measures of colours occurring in the lesion, to availing themselves of high-level semantic features such as the presence of blue-white veil, globules, or colour variegation in the lesion. This paper provides a retrospective survey and critical analysis of contributions in this research direction

    New Options for Non-invasive Imaging and Non-invasive Treatment of Skin Cancers

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    Tausta Tyvisolusyöpä on maailman yleisin syöpä. Tyvisolusyövällä on eri alatyyppejä, joista pinnallinen tyvisolusyöpä ja ohut nodulaarinen tyvisolusyöpä ovat vähäisen riskin tyyppejä, jotka on mahdollista hoitaa muutoin kuin leikkaamalla. Pinnallinen tyvisolusyöpä on lisääntynyt muita alatyyppejä nopeammin, ja näin ollen myös ei-kirurgisten hoitovaihtoehtojen käyttö todennäköisesti lisääntyy. Valoaktivaatiohoito ja voidehoidot, joita ovat imikimodi ja 5-fluorourasiili, ovat vaihtoehtoja kirurgialle. Valoaktivaatiohoidon etuja ovat erinomainen kosmeettinen lopputulos sekä lyhytkestoisempi hoitoaika ja paikallisreaktion kesto verrattuna voidehoitoihin. Imikimodin teho on kuitenkin parempi kuin valoaktivaatiohoidon. Suuren riskin tyvisolusyöpiä ovat aggressiiviset alatyypit, joille tyypillisiä ovat kasvaimen epätarkkarajaisuus ja kliinisesti näkymättömät kasvainalueet. Lentigo maligna -melanooma on ihomelanooman alamuoto, jolle tyypillisiä ovat myös nämä piirteet. Lentigo maligna on lentigo maligna -melanooman esiastemuoto. Näitä kahta on vaikea erottaa toisistaan silmin ja dermatoskoopilla arvioiden. Epätarkkarajaiset ihosyövät ovat siis kliininen haaste. Kajoamattomilla kuvantamismenetelmillä on mahdollista parantaa ihokasvainten diagnostiikkaa ja arviota. Hyperspektrikuvantaminen on uusi, nopea ja tietokoneavusteinen kuvantamismenetelmä, jolla on laaja kuvausalue. Tavoitteet Väitöskirjassa tutkitaan hyperspektrikuvantamista ja vähäisen riskin tyvisolusyövän valoaktivaatiohoitoa kliinisessä lääketutkimuksessa. Tavoitteena on tutkia hyperspektrikameran kykyä erottaa lentigo maligna -melanooma ja lentigo maligna toisistaan, sekä arvioida hyperspektrikameran kykyä määrittää epätarkkarajaisen tyvisolusyövän rajat ennen leikkausta verrattuna kliiniseen arvioon dermatoskoopin kanssa. Kliinisen lääketutkimuksen tavoitteena on verrata kolmen eri valoherkistäjävoiteen tehoa vähäisen riskin tyvisolusyövän valoaktivaatiohoidossa. Menetelmät Hyperspektrikuvantamista tutkittiin kahdessa pilottitutkimuksessa. Näistä toisessa kuvattiin lentigo malignaa/lentigo maligna –melanoomaa, ja toisessa epätarkkarajaista tyvisolusyöpää. Molemmissa tutkimuksissa kasvaimet arvioitiin ennen kuvantamista kliinisesti dermatoskoopin avulla. Lopuksi kasvaimet leikattiin. Hyperspektrikuvat tuotettiin matemaattisen mallinnuksen avulla tietokoneavusteisesti. Patologi, joka arvioi leikkeet, ei tiennyt, mitä hyperspektrilöydökset olivat. Kameran löydöksiä verrattiin histopatologiaan, ja epätarkkarajaisen tyvisolusyövän tapauksessa myös kliinisesti määritettyihin kasvaimen rajoihin. Kliininen lääketutkimus oli tutkijalähtöinen, prospektiivinen, kontrolloitu, satunnaistettu ja kaksoissokkoutettu. Tutkimuksessa verrattiin kahden uudehkon valoherkistäjävoiteen eli 5-aminolevuliinihapon nanoemulsion ja matalapitoisen heksyyliaminolevulinaatin tehoa laajasti käytettyyn metyyliaminolevulinaattiin. Päätulos oli histologinen paraneminen kolme kuukautta valoaktivaatiohoidon jälkeen. Toissijaisia tuloksia olivat kosmeettinen lopputulos sekä hoidon haittavaikutukset eli kipu ja hoidonjälkeinen paikallisreaktio. Kivunhoitona käytettiin pitkävaikutteista paikallispuudutetta ennen kasvainten käsittelyä valoaktivaatiohoitoa varten. Tutkimuksessa arvioitiin myös valoherkistäjävoiteen fluoresenssia ja kulumista valotuksen aikana (ns. photobleaching) kokeellisella laitteistolla. Diagnoosi ja hoitotulos varmistettiin koepaloin. Tutkimuksessa potilaat ja tulosten arvioijat eivät tienneet, mitä valoherkistäjää oli käytetty. Tulokset Lentigo maligna -melanooman, lentigo malignan ja terveen ihon hyperspektrikäyrät ovat erilaisia. Näin ollen lentigo maligna -melanooma ja lentigo maligna on mahdollista erottaa toisistaan hyperspektrikuvantamisen avulla. Hyperspektrikuvien perusteella oli myös mahdollista paikallistaa invaasioalue. Hyperspektrikamera määritti epätarkkarajaisen tyvisolusyövän rajat tarkemmin kuin kliinisesti oli määritetty, ja histopatologia tuki tätä löydöstä. Valoaktivaatiohoidossa tyvisolusyöpä parani lähes yhtä hyvin matalapitoisella heksyyliaminolevulinaatilla kuin korkeapitoisemmilla 5-aminolevuliinihapon nanoemulsiolla ja metyyliaminolevulinaatilla. Valoherkistäjävoiteiden välillä ei ollut eroja haittavaikutuksissa tai kosmeettisessa lopputuloksessa. Fluoresenssin ja valoherkistäjän kulumisen tuloksissa oli laaja hajonta. Johtopäätökset Hyperspektrikuvantaminen vaikuttaa lupaavalta uudelta menetelmältä, jolla on laaja kuvausalue, ja joka on nopea ja helppokäyttöinen. Lisäksi hyperspektrikamera näyttää pystyvän visualisoimaan silmälle näkymättömiä muutoksia. Heksyyliaminolevulinaatti on mielenkiintoinen uusi vaihtoehto vähäisen riskin tyvisolusyövän valoaktivaatiohoitoon, sillä jo matalalla pitoisuudella saavutetaan vastaava hoitotulos kuin korkeammilla pitoisuuksilla 5- aminolevuliinihapon nanoemulsiota tai metyyliaminolevulinaattia. Kuitenkaan hoidon kosmeettisessa lopputuloksessa tai haittavaikutuksissa ei ole eroja valoherkistäjien välillä.Background Basal cell carcinoma is the most common cancer in the world. The incidence of superficial basal cell carcinoma, a subtype of basal cell carcinoma, is rising at a far steeper rate than the other subtypes, and as a non-aggressive subtype, it can be treated non-invasively. Aggressive subtypes of basal cell carcinoma are often ill-defined, which poses a clinical problem in preoperative margin assessment. Another ill-defined skin cancer type is lentigo maligna. Lentigo maligna is an in situ melanoma, and a precursor of lentigo maligna melanoma. These two forms are clinically challenging to distinguish from each other, which is crucial as melanoma has the worst prognosis of all skin cancers. Non-invasive imaging is an option for increasing the accuracy of preoperative diagnosis and the assessment. Hyperspectral imaging is a novel, fast, and computer-aided imaging modality with a wide field of view. In non-invasive treatment of non-aggressive basal cell carcinomas, photodynamic therapy has many advantages: an excellent cosmetic outcome as well as a shorter application time and recovery period. Notwithstanding these advantages, the efficacy of photodynamic therapy is lower when compared to topical pharmacological options such as imiquimod and 5- fluorouracil. Objectives This dissertation focuses on non-invasive imaging and non-invasive treatment. In non-invasive imaging, the aim is to study the performance of a hyperspectral imaging system in separating lentigo maligna melanoma from lentigo maligna and assessing the preoperative margins of ill-defined basal cell carcinomas compared to clinical delineation assessments performed with a dermoscope. In non-invasive treatment, the aim is to compare the efficacy of three different photosensitisers in photodynamic therapy of non-aggressive basal cell carcinomas. Methods There are two pilot studies with hyperspectral imaging: one on lentigo maligna and lentigo maligna melanoma, and another one on ill-defined basal cell carcinoma. Tumours were preoperatively visually inspected utilising a dermoscope, and thereafter imaged with the hyperspectral imaging system. Next, surgical excision was performed. Hyperspectral images were created with computer-aided mathematical models. Additional mathematical models were subsequently developed. In the results analysis, the findings of the hyperspectral imaging and clinically assessed margins were compared to the histopathology results, where assessment was performed blind to the hyperspectral imaging findings. A non-sponsored, prospective, randomised, controlled and double-blinded trial focused on non-invasive treatment. In this trial, two novel photosensitisers, 5- aminolevulinic acid nanoemulsion and low-concentration hexylaminolevulinate, were compared to the commonly used methylaminolevulinate in photodynamic therapy of non-aggressive basal cell carcinomas, i.e. thin nodular or superficial subtypes. The primary outcome was histological clearance at three months. Secondary outcomes included adverse events such as pain associated with the treatment while using a long-lasting local anaesthetic as pain management, post- treatment reaction, as well as cosmetic outcome, and fluorescence and photobleaching during the illumination. We used an experimental fluorescence imaging system. Punch biopsies were performed prior to treatment and during follow-up. Both patient and observers of outcomes were blind to the photosensitiser that was used. Results Hyperspectral imaging exhibited a unique hyperspectral graph for lentigo maligna melanoma, lentigo maligna, and healthy skin. Based on these results, hyperspectral images were created where hyperspectral data was represented in several abundance maps. The maps showed differing abundances for lentigo maligna melanoma and lentigo maligna, and it was possible to localise the invasion site inside the lesion. For ill-defined basal cell carcinoma, the margins of the tumour were delineated more accurately than by clinical assessment, and the results were confirmed with histopathology. The results of the clinical trial in photodynamic therapy showed that the histological clearance of hexylaminolevulinate was similar compared to 5- aminolevulinic acid nanoemulsion and methylaminolevulinate, with no differences in cosmetic outcome, pain or post-treatment reaction between the arms. In our fluorescence and photobleaching analyses the results were widely spread. Conclusions In conclusion, hyperspectral imaging seems to be a promising and useful new imaging modality with a wide field of view: it is fast, easy to use and it seems to be capable of visualising subclinical findings. In non-invasive treatment, hexylaminolevulinate is an interesting option for photodynamic therapy of non- aggressive basal cell carcinomas. Hexylaminolevulinate at low concentrations achieves a comparable efficacy to 5-aminolevulinic acid nanoemulsion and methylaminolevulinate at higher concentrations. No differences were observed in adverse events or cosmetic outcome between the arms

    Computational Methods for Pigmented Skin Lesion Classification in Images: Review and Future Trends

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    Skin cancer is considered as one of the most common types of cancer in several countries, and its incidence rate has increased in recent years. Melanoma cases have caused an increasing number of deaths worldwide, since this type of skin cancer is the most aggressive compared to other types. Computational methods have been developed to assist dermatologists in early diagnosis of skin cancer. An overview of the main and current computational methods that have been proposed for pattern analysis and pigmented skin lesion classification is addressed in this review. In addition, a discussion about the application of such methods, as well as future trends, is also provided. Several methods for feature extraction from both macroscopic and dermoscopic images and models for feature selection are introduced and discussed. Furthermore, classification algorithms and evaluation procedures are described, and performance results for lesion classification and pattern analysis are given

    Dermoscopy, with and without visual inspection, for the diagnosis of melanoma in adults

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    Background: Melanoma has one of the fastest rising incidence rates of any cancer. It accounts for a small percentage of skin cancer cases but is responsible for the majority of skin cancer deaths. Although history-taking and visual inspection of a suspicious lesion by a clinician are usually the first in a series of ‘tests’ to diagnose skin cancer, dermoscopy has become an important tool to assist diagnosis by specialist clinicians and is increasingly used in primary care settings. Dermoscopy is a magnification technique using visible light that allows more detailed examination of the skin compared to examination by the naked eye alone. Establishing the additive value of dermoscopy over and above visual inspection alone across a range of observers and settings is critical to understanding its contribution for the diagnosis of melanoma and to future understanding of the potential role of the growing number of other highresolution image analysis techniques. Objectives: To determine the diagnostic accuracy of dermoscopy for the detection of cutaneous invasive melanoma and atypical intraepidermal melanocytic variants in adults, and to compare its accuracy with that of visual inspection alone. Studies were separated according to whether the diagnosis was recorded face-to-face (in-person) or based on remote (image-based) assessment. Search methods: We undertook a comprehensive search of the following databases from inception up to August 2016: Cochrane Central Register of Controlled Trials; MEDLINE; Embase; CINAHL; CPCI; Zetoc; Science Citation Index; US National Institutes of Health Ongoing Trials Register; NIHR Clinical Research Network Portfolio Database; and the World Health Organization International Clinical Trials Registry Platform. We studied reference lists and published systematic review articles. Selection criteria: Studies of any design that evaluated dermoscopy in adults with lesions suspicious for melanoma, compared with a reference standard of either histological confirmation or clinical follow-up. Data on the accuracy of visual inspection, to allow comparisons of tests, was included only if reported in the included studies of dermoscopy. Data collection and analysis: Two review authors independently extracted all data using a standardised data extraction and quality assessment form (based on QUADAS-2). We contacted authors of included studies where information related to the target condition or diagnostic threshold were missing. We estimated accuracy using hierarchical summary ROC methods. Analysis of studies allowing direct comparison between tests was undertaken. To facilitate interpretation of results, we computed values of sensitivity at the point on the SROC curve with 80% fixed specificity and values of specificity with 80% fixed sensitivity. We investigated the impact of in-person test interpretation; use of a purposely developed algorithm to assist diagnosis; observer expertise; and dermoscopy training. Main results: A total of 104 study publications reporting on 103 study cohorts with 42,788 lesions (including 5700 cases) were included, providing 354 datasets for dermoscopy. The risk of bias was mainly low for the index test and reference standard domains and mainly high or unclear for participant selection and participant flow. Concerns regarding the applicability of study findings were largely scored as ‘High’ concern in three of four domains assessed. Selective participant recruitment, lack of reproducibility of diagnostic thresholds and lack of detail on observer expertise were particularly problematic. The accuracy of dermoscopy for the detection of invasive melanoma or atypical intraepidermal melanocytic variants was reported in 86 datasets; 26 for evaluations conducted in-person (dermoscopy added to visual inspection) and 60 for image-based evaluations (diagnosis based on interpretation of dermoscopic images). Analyses of studies by prior testing revealed no obvious effect on accuracy; analyses were hampered by the lack of studies in primary care, lack of relevant information and the restricted inclusion of lesions selected for biopsy or excision. Accuracy was higher for in-person diagnosis compared to image-based evaluations (relative diagnostic odds ratio (RDOR) of 4.6; 95% CI 2.4, 9.0, P<0.001). Accuracy was compared for (a) in-person evaluations of dermoscopy (26 evaluations; 23,169 lesions and 1664 melanomas) versus visual inspection alone (13 evaluations; 6740 lesions and 459 melanomas) and for (b) image-based evaluations of dermoscopy (60 evaluations; 13,475 lesions and 2851 melanomas) versus image-based visual inspection (11 evaluations; 1740 lesions and 305 melanomas). For both comparisons, meta-analysis found dermoscopy to be more accurate than visual inspection alone, with RDORs of (a) 4.7 (95% CI: 3.0 to 7.5; P < 0.001) and (b) 5.6 (95% CI: 3.7 to 8.5; P < 0.001). These effects correspond to predicted differences in sensitivity of (a) 16% (95% CI: 8%, 23%) (92% for dermoscopy+visual inspection vs 76% for visual inspection) and (b) 35% (95% CI 24% to 46%) (81% for dermoscopy vs 47% for visual inspection) at a fixed specificity of 80%; and topredicted differences in specificity of (a) 20% (95% CI 7%, 33) (95% for dermoscopy plus visual inspection vs 75% for visual inspection) and (b) 40% (95% CI 27, 57) (82% for dermoscopy vs 42% for visual inspection) at a fixed sensitivity of 80%. Using the median prevalence of disease in each set of studies ((a) 12% for in-person and (b) 24% for image-based) for a hypothetical population of 1000 lesions, an increase in sensitivity of (a) 16% (in-person) and (b) 35% (image-based) from using dermoscopy at a fixed specificity of 80% equates to a reduction in the number of melanomas missed of (a) 19 and (b) 81 with (a) 176 and (b) 152 false positive results. An increase in specificity of (a) 20% (in-person) and (b) 40% (image-based) at a fixed sensitivity of 80% equates to a reduction in the number of unnecessary excisions from using dermoscopy of (a) 176 and (b) 304 with (a) 24 and (b) 48 melanomas missed. The use of a named or published algorithm to assist dermoscopy interpretation (as opposed to no reported algorithm or reported use of pattern analysis) had no significant impact on accuracy either for in-person (RDOR 1.4, 95% CI 0.34, 5.6; P=0.17) or image-based (RDOR 1.4, 95% CI 0.60, 3.3; P=0.22) evaluations. This result was supported by subgroup analysis according to algorithm used. Higher accuracy for observers reported as having high experience and for those classed as ‘expert consultants’ in comparison to those considered to have less experience in dermoscopy was observed, particularly for image-based evaluations. Evidence for the effect of dermoscopy training on test accuracy was very limited but suggested associated improvements in sensitivity. Authors' conclusions: Despite the observed limitations in the evidence base, dermoscopy is a valuable tool to support the visual inspection of a suspicious skin lesion for the detection of melanoma and atypical intraepidermal melanocytic variants, particularly in referred populations and in the hands of experienced users. Data to support its use in primary care is limited however it may assist in triaging suspicious lesions for urgent referral when employed by suitably trained clinicians. Formal algorithms may be of most use for dermoscopy training purposes and for less expert observers, however reliable data comparing approaches using dermoscopy in-person are lacking
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