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

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

Hyperspectral Imaging Reveals Spectral Differences and Can Distinguish Malignant Melanoma from Pigmented Basal Cell Carcinomas : A Pilot Study

Pigmented basal cell carcinomas can be difficult to distinguish from melanocytic tumours. Hyperspectral imaging is a non-invasive imaging technique that measures the reflectance spectra of skin in vivo. The aim of this prospective pilot study was to use a convolutional neural network classifier in hyperspectral images for differential diagnosis between pigmented basal cell carcinomas and melanoma. A total of 26 pigmented lesions (10 pigmented basal cell carcinomas, 12 melanomas in situ, 4 invasive melanomas) were imaged with hyperspectral imaging and excised for histopatho-logical diagnosis. For 2-class classifier (melano-cytic tumours vs pigmented basal cell carcinomas) using the majority of the pixels to predict the class of the whole lesion, the results showed a sensitivity of 100% (95% confidence interval 81-100%), specificity of 90% (95% confidence interval 60-98%) and positive predictive value of 94% (95% confidence interval 73-99%). These results indicate that a convolutional neural network classifier can differentiate melanocytic tumours from pigmented basal cell carcinomas in hyperspectral images. Further studies are warranted in order to confirm these preliminary results, using larger samples and multiple tumour types, including all types of melanocytic lesions.Peer reviewe

Differentiating Malignant from Benign Pigmented or Non-Pigmented Skin Tumours—A Pilot Study on 3D Hyperspectral Imaging of Complex Skin Surfaces and Convolutional Neural Networks

Several optical imaging techniques have been developed to ease the burden of skin cancer disease on our health care system. Hyperspectral images can be used to identify biological tissues by their diffuse reflected spectra. In this second part of a three-phase pilot study, we used a novel hand-held SICSURFIS Spectral Imager with an adaptable field of view and target-wise selectable wavelength channels to provide detailed spectral and spatial data for lesions on complex surfaces. The hyperspectral images (33 wavelengths, 477–891 nm) provided photometric data through individually controlled illumination modules, enabling convolutional networks to utilise spectral, spatial, and skin-surface models for the analyses. In total, 42 lesions were studied: 7 melanomas, 13 pigmented and 7 intradermal nevi, 10 basal cell carcinomas, and 5 squamous cell carcinomas. All lesions were excised for histological analyses. A pixel-wise analysis provided map-like images and classified pigmented lesions with a sensitivity of 87% and a specificity of 93%, and 79% and 91%, respectively, for non-pigmented lesions. A majority voting analysis, which provided the most probable lesion diagnosis, diagnosed 41 of 42 lesions correctly. This pilot study indicates that our non-invasive hyperspectral imaging system, which involves shape and depth data analysed by convolutional neural networks, is feasible for differentiating between malignant and benign pigmented and non-pigmented skin tumours, even on complex skin surfaces

Differentiating Malignant from Benign Pigmented or Non-Pigmented Skin Tumours—A Pilot Study on 3D Hyperspectral Imaging of Complex Skin Surfaces and Convolutional Neural Networks

Several optical imaging techniques have been developed to ease the burden of skin cancer disease on our health care system. Hyperspectral images can be used to identify biological tissues by their diffuse reflected spectra. In this second part of a three-phase pilot study, we used a novel hand-held SICSURFIS Spectral Imager with an adaptable field of view and target-wise selectable wavelength channels to provide detailed spectral and spatial data for lesions on complex surfaces. The hyperspectral images (33 wavelengths, 477–891 nm) provided photometric data through individually controlled illumination modules, enabling convolutional networks to utilise spectral, spatial, and skin-surface models for the analyses. In total, 42 lesions were studied: 7 melanomas, 13 pigmented and 7 intradermal nevi, 10 basal cell carcinomas, and 5 squamous cell carcinomas. All lesions were excised for histological analyses. A pixel-wise analysis provided map-like images and classified pigmented lesions with a sensitivity of 87% and a specificity of 93%, and 79% and 91%, respectively, for non-pigmented lesions. A majority voting analysis, which provided the most probable lesion diagnosis, diagnosed 41 of 42 lesions correctly. This pilot study indicates that our non-invasive hyperspectral imaging system, which involves shape and depth data analysed by convolutional neural networks, is feasible for differentiating between malignant and benign pigmented and non-pigmented skin tumours, even on complex skin surfaces

Unsupervised Numerical Characterization in Determining the Borders of Malignant Skin Tumors from Spectral Imagery

For accurate removal of malignant skin tumors, it is crucial to assure the complete removal of the lesions. In the case of certain ill-defined tumors, it is clinically challenging to see the true borders of the tumor. In this paper, we introduce several computationally efficient approaches based on spectral imaging to guide clinicians in delineating tumor borders. First, we present algorithms that can be used effectively with simulated skin reflectance data. By using simulated data, we gain detailed information about the sensitivity of the different approaches and how variables defined by algorithms act in the skin model. Second, we demonstrate the performance of the algorithms with spectral images taken in-vivo and representing two types of skin cancers with ill-defined borders, namely lentigo maligna and aggressive basal cell carcinoma. The results can be used as a guideline for developing software for the fast delineation of skin cancers.peerReviewe

Ihokasvainten diagnostiikka paranee kajoamattominkin keinoin

Vertaisarvioitu.• Ihosyövät ovat maailman yleisimpiä syöpiä. Niiden ilmaantuvuus on kasvanut jatkuvasti vuosikymmenten ajan – myös Suomessa. • Ihokasvainten diagnostiikkaa voidaan parantaa ja nopeuttaa oleellisillaesitiedoilla, kliinisellä tutkimuksella, dermatoskopialla ja muilla kajoamattomilla kuvantamisilla. • Ihomuutoksesta otetun koepalan histopatologinen tutkimus on tärkeädiagnoosin varmentamiseksi, mikäli esitiedot ja kajoamattomat tutkimukset eivät riitä.Peer reviewe

Ablative Fractional Laser Enhances Artificial or Natural Daylight Photodynamic Therapy of Actinic Field Cancerization: A Randomized and Investigator-initiated Half-side Comparative Study

Artificial daylight photodynamic therapy is a near-painless treatment for actinic keratoses, which can be performed indoors using a controlled light dose. Daylight photodynamic therapy is approved only for treatment of grade I–II actinic keratoses. The aim of this study was to evaluate whether fractional laser pre-treatment improves the outcomes of daylight photodynamic therapy for actinic keratoses of all grades. In addition, the study compared the outcomes of artificial and natural daylight photodynamic therapy. This randomized single-blinded split-side comparative study included 60 patients with  ≥ 2 actinic keratoses of the head. Fractional laser pre-treatment was assigned randomly for actinic keratoses on 1 side of the head and, subsequently, the entire treatment area was treated with artificial or natural daylight photodynamic therapy. Fractional laser-mediated daylight photodynamic therapy achieved significantly higher complete clearance (50.0% vs 30.3%, p = 0.04), partial clearance (78.6% vs 50.0%, p < 0.01) and lesion-specific clearance (86.2% vs 70.2%, p < 0.01) than daylight photodynamic therapy alone at the 6-month follow-up. No significant differences were found in the outcomes of artificial vs natural daylight photodynamic therapy or grade I lesions vs grade II–III lesions. Thus, fractional laser pre-treatment appears to significantly increase the efficacy of artificial and natural daylight photodynamic therapy, and to be suitable for treatment of actinic keratoses of all grades

Hyperspectral Imaging for Non-invasive Diagnostics of Melanocytic Lesions

Malignant melanoma poses a clinical diagnostic problem, since a large number of benign lesions are excised to find a single melanoma. This study assessed the accuracy of a novel non-invasive diagnostic technology, hyperspectral imaging, for melanoma detection. Lesions were imaged prior to excision and histopathological analysis. A deep neural network algorithm was trained twice to distinguish between histopathologically verified malignant and benign melanocytic lesions and to classify the separate subgroups. Furthermore, 2 different approaches were used: a majority vote classification and a pixel-wise classification. The study included 325 lesions from 285 patients. Of these, 74 were invasive melanoma, 88 melanoma in situ, 115 dysplastic naevi, and 48 non-dysplastic naevi. The study included a training set of 358,800 pixels and a validation set of 7,313 pixels, which was then tested with a training set of 24,375 pixels. The majority vote classification achieved high overall sensitivity of 95% and a specificity of 92% (95% confidence interval (95% CI) 0.024–0.029) in differentiating malignant from benign lesions. In the pixel-wise classification, the overall sensitivity and specificity were both 82% (95% CI 0.005–0.005). When divided into 4 subgroups, the diagnostic accuracy was lower. Hyperspectral imaging provides high sensitivity and specificity in distinguishing between naevi and melanoma. This novel method still needs further validation.peerReviewe

Discriminating Basal Cell Carcinoma and Bowen’s Disease with Novel Hyperspectral Imaging System and Convolutional Neural Networks

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Differentiating Malignant from Benign for Melanocytic and Non-melanocytic Skin Tumors : A Pilot Study on Hyperspectral Imaging and Convolutional Neural Networks

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