AN IMAGE BASED SYSTEM TO OBJECTIVEI,Y SCORE THE DEGREE OF REDNESS IN PSORIASIS LESIONS

Nowadays, many skin diseases exist, ranging from hannless such as benign tumors to highly cancerous ones such as malignant melanoma. The visual resemblance of skin lesions requires experienced dennatologists for diagnosis and treatment of skin diseases. One of the most common types of the skin diseases is psoriasis which is chronic inflammatory skin condition, characterized by localized, widespread welldemarcated red plaques often topped by silvery scales. The basic characteristics of psoriasis lesions namely redness, thickness, and scaliness provide a mean of assessing the severity of psoriasis. Dennatologists are using Psoriasis Area and Severity Index (P ASI) score, which takes into account signs such as redness, plaque thickness and scaling in order to assess psoriasis disease severity. The objective of this project is to generate the score of the redness and score of the area covered by psoriasis in order to build automated imaging system capable of classifYing the severity of the disease. This system would assist dennatologists to give the suitable treatment to the different levels of psoriasis severity based on the PASI score. The psoriasis lesion images will be analyzed to classifY the severity based on color, shape, size, and other features by using the Digital Image Processing Tools in MATLAB7 soflware. The entire infonnation obtained through the computer vision and image processing as well as MATLAB7 soflware is applied towards the development of this project. The project will be implemented in two stages .. The first stage (semester 1) involves literature review, research, data gathering, learning and training of the soflware or program and the second stage (semester 2) is analysis of core features, design, testing and analysis of results

Objective Assessment of Area and Erythema of Psoriasis Lesion Using Digital Imaging and Colourimetry

Psoriasis is a non-contagious skin disease which typically consists of red plaques covered by silvery-white scales. It affects about 3% of world population. During treatment, dermatologists monitor the extent of psoriasis continuously to ascertain treatment efficacy. Psoriasis Area and Severity Index (PAS!) is the current gold standard method used to assess the extent of psoriasis. In PAS!, there are four parameters to be scored i.e., the surface area affected, erythema (redness), thickness and scaliness of the plaques. Determining PAS! score is a tedious task and thus it is not used in daily clinical practice. In addition, the PAS! parameters are visually determined and may result in intra-observer and inter-observer variations, even by experienced dermatologists. Objective methods in assessing area and erythema of psoriasis lesion have been developed in this thesis. Psoriasis lesion can be recognized by its colour dissimilarity with normal skin. Colour dissimilarity is represented by colour difference in CIELAB colour space, a widely used colour space to measure colour dissimilarity. Each pixel in CIELAB colour space can be represented by its lightness (L'), hue (hob), and chroma (Cab). Colour difference between psoriasis lesion and normal skin is analyzed in hue-chroma plane of CIELAB colour space. Centroids of normal skin and lesion in hue-chroma space are obtained from selected samples. Euclidean distances between all pixels with these two centroids are then calculated. Each pixel is assigned to the class of the nearest centroid. The erythema of psoriasis lesion is affected by degree of severity and skin pigmentation. In order to assess the erythema objectively, patients are grouped according to their skin pigmentation level. The L* value of normal skin which represents skin pigmentation level is utilized to group the patient into the three skin types namely fair, brown and dark skin types. Light difference (t.L*), hue difference (t.hab), and chroma difference (t.C'ab) of CIELAB colour space between reference lesions and the surrounding normal skin are analyzed. It is found that the erythema score of a lesion can be determined by their hue difference (t.hab) value within a particular skin type group. Out of 30 body regions, the proposed method is able to give the same PAS! area score as reference for 28 body regions. The proposed method is able to determine PAS! erythema score of 82 lesions obtained from 22 patients objectively without being influenced by other characteristic of the lesion such as area, pattern, and boundary

Psychological aspects of Psoriasis

Psoriasis is a skin condition characterised by raised, red, scaling patches that cover the body to varying degrees, with a prevalence of 1-3% in Caucasian populations. There is evidence that sufferers hospitalised for treatment of then psoriasis are more depressed and more anxious than controls (e.g. Fava et al, 1980; Lyketsos et al, 1985), but conflicting evidence about whether psoriasis outpatients are also more depressed and anxious. The research presented in this thesis examined depression and anxiety in a group of psoriasis outpatients and found statistically significantly higher depression and anxiety levels than in a group of matched controls. The relationship over tune between area of coverage of psoriasis, depression and anxiety was examined in another group of psoriasis outpatients. Using multiple regression analysis, change in area of coverage between two assessments was a significant predictor of depression and anxiety at the second assessment, once levels at the first assessment had been accounted for. Self- esteem was also examined in this way and was found to be significantly related to psoriasis area of coverage, where worsening psoriasis was associated with a lowering of self-esteem. There were statistically significant differences between males and females. Pain had not previously been examined systematically in psoriasis outpatients, but was higher than pain in matched controls in the first study reported in this thesis. Consequently the quality of pain was examined further, and found not only to be significantly related to psoriasis area of coverage, but also was described in terms which suggested a distinct character to psoriasis pain. Fluctuations in sleep quality were also found to be significantly associated with psoriasis area of coverage. Visual assessment of psoriasis area of coverage was shown to be unreliable, so a computer program (SKINMAP) was developed to allow psoriasis lesions to be mapped onto a computer which then calculates area of coverage. SKINMAP estimates were shown to be statistically significantly more accurate and reliable than visual estimates. Informal conversations with psoriasis sufferers suggested that they held firm views about their condition which often did not coincide with medical views. Lay beliefs about psoriasis in a group of sufferers were therefore investigated in detail. Sufferers showed quite high levels of knowledge about the condition, but the nature of some common misconceptions was investigated through the use of semi-structured interviews, and the results highlighted the need for better patient education

AN IMAGE BASED SYSTEM TO OBJECTIVEI,Y SCORE THE DEGREE OF REDNESS IN PSORIASIS LESIONS

Nowadays, many skin diseases exist, ranging from hannless such as benign tumors to highly cancerous ones such as malignant melanoma. The visual resemblance of skin lesions requires experienced dennatologists for diagnosis and treatment of skin diseases. One of the most common types of the skin diseases is psoriasis which is chronic inflammatory skin condition, characterized by localized, widespread welldemarcated red plaques often topped by silvery scales. The basic characteristics of psoriasis lesions namely redness, thickness, and scaliness provide a mean of assessing the severity of psoriasis. Dennatologists are using Psoriasis Area and Severity Index (P ASI) score, which takes into account signs such as redness, plaque thickness and scaling in order to assess psoriasis disease severity. The objective of this project is to generate the score of the redness and score of the area covered by psoriasis in order to build automated imaging system capable of classifYing the severity of the disease. This system would assist dennatologists to give the suitable treatment to the different levels of psoriasis severity based on the PASI score. The psoriasis lesion images will be analyzed to classifY the severity based on color, shape, size, and other features by using the Digital Image Processing Tools in MATLAB7 soflware. The entire infonnation obtained through the computer vision and image processing as well as MATLAB7 soflware is applied towards the development of this project. The project will be implemented in two stages .. The first stage (semester 1) involves literature review, research, data gathering, learning and training of the soflware or program and the second stage (semester 2) is analysis of core features, design, testing and analysis of results

Improving our understanding of childhood psoriasis: Identifying opportunities for early intervention for the prevention of long-term harm

1.1 Introduction Psoriasis is an immune-mediated chronic inflammatory disease affecting the skin and joints of adults and children. This PhD focused on psoriasis in children because it is especially for this age group that both a research need and an opportunity to improve long-term health outcomes exist. There is a deficiency of paediatric specific research to guide optimal management and, for many individuals, the persistence of psoriasis into adulthood has a negative cumulative effect over their lifetime. Difficulties can arise because of the physical, psychological, and social burden of psoriasis, including the development of psoriatic arthritis. 1.2 Research aim The aim of this research was to identify opportunities to intervene early in the disease course of children with psoriasis and juvenile psoriatic arthritis, in order to prevent long-term harm from these conditions. Specifically the research aims of each study were: 1. To determine current clinical practice in the assessment and management of childhood psoriasis. 2. To understand current clinical practice in the assessment of juvenile psoriatic arthritis and psoriasis. 3. To map the evidence and identify research gaps in the epidemiology of childhood psoriasis. 4. To identify studies which have developed or validated diagnostic criteria for psoriasis. 5. To derive expert agreed diagnostic criteria for plaque psoriasis in children. 6. To design a diagnostic accuracy study to develop DIagnostic criteria for PSOriasis in Children (DIPSOC Study) 1.3 Methods The initial studies focused on identifying deficiencies in current practice and exploring barriers in the detection of psoriasis and juvenile psoriatic arthritis. This research was undertaken as a multi-centre audit and case-note review, and qualitative descriptive interviews with paediatric rheumatologists and dermatologists. Framework and thematic content analysis were used to ascertain and explore the approach clinicians’ take to assess skin and joint disease. The subsequent studies have mapped the volume, nature, and characteristics of epidemiological studies and appraised the literature to inform the development of diagnostic criteria for psoriasis in children. This research was undertaken as a scoping review on the epidemiology of childhood psoriasis and a systematic review on diagnostic criteria for psoriasis. The studies in the systematic review were appraised for risk of bias using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. The final studies focused on developing diagnostic criteria for psoriasis in children. An electronic Delphi (eDelphi) consensus study with the International Psoriasis Council (IPC) used sequential online questionnaires and scoring to reach agreement on a list of expert-derived criteria. These five studies informed the design of a multi-centre case-control diagnostic accuracy study (DIPSOC study) to test the consensus agreed criteria and develop the best predictive criteria. 1.4 Results The audit of the care of 285 children with psoriasis showed that compliance with national guidelines was variable. Only half of children were assessed annually for juvenile psoriatic arthritis and a third of children with psoriasis were potentially misdiagnosed with having other skin diseases in primary care. Exploring this further, paediatric rheumatologists’ and dermatologists’ current approach for assessing skin and joint disease, respectively, may not detect psoriasis and juvenile psoriatic arthritis. Reviewing the evidence base, most epidemiological data originates from case-series and cross-sectional studies, and there were few case-control and cohort studies investigating risk factors for disease onset, comorbidities, and long-term health outcomes in paediatric psoriasis. This work highlighted a need to improve the recognition of psoriasis in children and for new studies using standardised methodologies and definitions. Currently, no clinical examination-based diagnostic criteria for psoriasis have been developed, tested, or validated. To address this evidence gap, experts collectively agreed on 16 diagnostic features, divided into three major and thirteen minor criteria, which are important for the clinical diagnosis of plaque psoriasis in children. These consensus agreed criteria will be tested in the DIPSOC study. The design of DIPSOC aims to minimise bias in the four key domains proposed by the QUADAS-2 tool, but uses a case-control design to ensure the recruitment target is feasible within the resources available. 1.5 Discussion The research in this PhD makes an important contribution to the field of paediatric psoriasis and culminates in the design of the DIPSOC study to test and refine a list of diagnostic criteria for psoriasis in children. The criteria are intended to improve the recognition and early diagnosis of psoriasis in children, as well as offer a standardised disease definition for clinical trials and observational research. Improved diagnostic accuracy and increasing the quality of evidence from research studies will provide opportunities for early intervention to prevent long-term harm in children with psoriasis

Markov-Gibbs Random Field Approach for Modeling of Skin Surface Textures

Medical imaging has been contributing to dermatology by providing computer-based assistance by 2D digital imaging of skin and processing of images. Skin imaging can be more effective by inclusion of 3D skin features. Furthermore, clinical examination of skin consists of both visual and tactile inspection. The tactile sensation is related to 3D surface profiles and mechanical parameters. The 3D imaging of skin can also be integrated with haptic technology for computer-based tactile inspection. The research objective of this work is to model 3D surface textures of skin. A 3D image acquisition set up capturing skin surface textures at high resolution (~0.1 mm) has been used. An algorithm to extract 2D grayscale texture (height map) from 3D texture has been presented. The extracted 2D textures are then modeled using Markov-Gibbs random field (MGRF) modeling technique. The modeling results for MGRF model depend on input texture characteristics. The homogeneous, spatially invariant texture patterns are modeled successfully. From the observation of skin samples, we classify three key features of3D skin profiles i.e. curvature of underlying limb, wrinkles/line like features and fine textures. The skin samples are distributed in three input sets to see the MGRF model's response to each of these 3D features. First set consists of all three features. Second set is obtained after elimination of curvature and contains both wrinkle/line like features and fine textures. Third set is also obtained after elimination of curvature but consists of fine textures only. MGRF modeling for set I did not result in any visual similarity. Hence the curvature of underlying limbs cannot be modeled successfully and makes an inhomogeneous feature. For set 2 the wrinkle/line like features can be modeled with low/medium visual similarity depending on the spatial invariance. The results for set 3 show that fine textures of skin are almost always modeled successfully with medium/high visual similarity and make a homogeneous feature. We conclude that the MGRF model is able to model fine textures of skin successfully which are on scale of~ 0.1 mm. The surface profiles on this resolution can provide haptic sensation of roughness and friction. Therefore fine textures can be an important clue to different skin conditions perceived through tactile inspection via a haptic device

Detektion und quantitative Analyse von entzündlichen und strukturellen Veränderungen im Vergleich zur MRT

Die Magnetresonanztomographie (MRT) ist ein etabliertes Verfahren in der Arthritisdiagnostik. Entzündliche Veränderungen können dargestellt und mittels dynamischer kontrastverstärkter MRT (DCE-MRT) auch quantitativ bewertet werden. Bei der differenzierten Bewertung von strukturellen Veränderungen im Rahmen der rheumatoiden Arthritis besitzt die MRT jedoch eine geringe Spezifität. Dagegen zeigt die Computertomographie (CT) deutliche Vorteile bei der Detektion von knöchernen Läsionen. Die Durchführbarkeit der CT in der Detektion von entzündlichen Veränderungen ist daher Gegenstand der aktuellen Forschung. Zielsetzung: Ziel dieser Arbeit war es den diagnostischen Stellenwert der kontrastverstärkten CT in der Arthritisbildgebung zu untersuchen. Die Durchführbarkeit der CT-Subtraktion wurde in der Detektion von entzündlichen Veränderungen evaluiert und mittels quantitativer Analyse der Perfusion in der dynamischen kontrastverstärkten CT (DCE-CT) und DCE-MRT nachgewiesen. Ein Teilaspekt der Auswertung war die suszeptibilitätsgewichtete Sequenz (SWI) für die Erosiondetektion. Methoden: 37 Patienten mit Verdacht oder gesicherter rheumatoiden Arthritis der Hand wurden prospektiv in der kontrastverstärkten ultra-niedrigdosierten CT und MRT untersucht. Aus den gewonnenen CT-Bilddaten wurde zur Darstellung von Synovialitis und Tenosynovialitis die CT-Subtraktion berechnet und mit der MRT als Referenz verglichen. Durch Berechnung der Perfusionsparameter aus der DCE-CT und DCE-MRT wurde die Perfusion quantitativ zwischen den beiden Modalitäten verglichen. Das MRT-Protokoll beinhaltete zusätzlich zum Standardprotokoll eine SWI Sequenz. Die Bewertung der Erosion, Synovialitis und Tenosynovialitis fand durch drei Bewerter nach den etablierten Rheumatoid Arthritis Magnetic Resonance Scores (RAMRIS) Kriterien statt. Ergebnisse: Die CT-Subtraktion erzielte in der Detektion von Synovialitis eine Spezifität von 88%. Es wurde eine gute Korrelation zwischen der CT-Subtraktion und der MRT gezeigt (Pearson’s r = 0,94). Zusätzlich waren die Perfusionsparameter in beiden Modalitäten vergleichbar. Mittels DCE-CT konnte zudem die Entzündungsaktivität differenziert werden. Die SWI führte zu einer verbesserten Darstellbarkeit von Erosionen im Vergleich oder in Ergänzung zu herkömmlichen Sequenzen. Schlussfolgerung: Die CT-Perfusion stellt in der Arthritisbildgebung eine neue Modalität dar, die mit einer hohen Sicherheit entzündliche Veränderungen an Gelenken, sowie an Sehnenscheiden abbilden kann und ebenso auf quantitativer Ebene mit der DCE-MRT vergleichbare Perfusionsanalyse liefert. Zusätzlich ist sie als Goldstandard in der Detektion von knöchernen Läsionen bisher nicht zu übertreffen.Magnetic resonance imaging (MRI) is an established imaging modality in the field of arthritis imaging. Inflammatory lesions can be detected and also quantitatively assessed using dynamic contrast-enhanced MRI (DCE-MRI). However, MRI has a low specificity in the differentiated assessment of structural changes in the context of rheumatoid arthritis. In contrast, computed tomography (CT) shows obvious advantages in the detection of bony lesions. The feasibility of CT in the detection of inflammatory lesions is therefore the subject of current research. Objective: The aim of this work was to investigate the diagnostic importance of contrastenhanced CT in arthritis imaging. The feasibility of CT-subtraction in the detection of inflammatory lesions was evaluated and demonstrated by quantitative analysis of the perfusion using dynamic contrast-enhanced CT (DCE-CT) and DCE-MRI. A partial aspect was to evaluate the use of the susceptibility-weighted imaging sequence (SWI) in erosion detection. Methods: 37 patients with suspected or proven diagnosis of rheumatoid arthritis of the hand prospectively underwent contrast-enhanced ultra-low-dose CT and MRI. CTsubtraction was calculated from the obtained CT image data to represent synovitis and tenosynovitis and compared with MRI as a reference. By assessing the perfusion parameters using DCE-CT and DCE-MRI, the perfusion was compared quantitatively between these two modalities. In addition to standard protocol, the MRI protocol included the SWI sequence. The evaluation of erosion, synovitis and tenosynovitis was performed by three readers according to the established Rheumatoid Arthritis Magnetic Resonance Scores (RAMRIS) criteria. Results: CT-subtraction performed with a specificity of 88% in detection of synovitis. There was shown a good correlation between CT-subtraction and MRI (Pearson’s r = 0,94). In addition, the perfusion parameters were comparable in both modalities. Inflammatory activity was also differentiated using DCE-CT. The SWI let to an improved detection of erosions compared to or in addition to conventional sequences. Conclusion: CT-perfusion represents a new modality in arthritis imaging, which can detect inflammation of the joints and tendons with a high degree of certainty and also provides a quantitative perfusion analysis comparable to that of DCE-MRI. In addition, CT has so far not been surpassed as the gold standard in the detection of bony lesions