Túlio Augusto Alves Macedo

INDIAM—An e-Learning System for the Interpretation of Mammograms

We propose the design of a teaching system named Interpretation and Diagnosis of Mammograms (INDIAM) for training students in the interpretation of mammograms and diagnosis of breast cancer. The proposed system integrates an illustrated tutorial on radiology of the breast, that is, mammography, which uses education techniques to guide the user (doctors, students, or researchers) through various concepts related to the diagnosis of breast cancer. The user can obtain informative text about specific subjects, access a library of bibliographic references, and retrieve cases from a mammographic database that are similar to a query case on hand. The information of each case stored in the mammographic database includes the radiological findings, the clinical history, the lifestyle of the patient, and complementary exams. The breast cancer tutorial is linked to a module that simulates the analysis and diagnosis of a mammogram. The tutorial incorporates tools for helping the user to evaluate his or her knowledge about a specific subject by using the education system or by simulating a diagnosis with appropriate feedback in case of error. The system also makes available digital image processing tools that allow the user to draw the contour of a lesion, the contour of the breast, or identify a cluster of calcifications in a given mammogram. The contours provided by the user are submitted to the system for evaluation. The teaching system is integrated with AMDI—An Indexed Atlas of Digital Mammograms—that includes case studies, e-learning, and research systems. All the resources are accessible via the Web.

Artifacts and pitfalls in shoulder magnetic resonance imaging

Magnetic resonance imaging has revolutionized the diagnosis of shoulder lesions, in many cases becoming the method of choice. However, anatomical variations, artifacts and the particularity of the method may be a source of pitfalls, especially for less experienced radiologists. In order to avoid false-positive and false-negative results, the authors carried out a compilation of imaging findings that may simulate injury. It is the authors’ intention to provide a useful, consistent and comprehensive reference for both beginner residents and skilled radiologists who work with musculoskeletal magnetic resonance imaging, allowing for them to develop more precise reports and helping them to avoid making mistakes.

Preprocess Enhancement of CT Image for Liver Segmentation with Region Growing Algorithm

Liver cancer, although not being among the most frequent type of cancer in Brazil, but is considered of high complexity to be diagnosed and treated. In order to get a high hit rate of liver segmentation in CT images with the algorithm of region growing are compared several preprocess enhancement techniques, which are: contrast stretching, gamma transformation, laplacian operator, sobel operator. As the result, the better technique is the gamma transformation, reaching 99.99% of correct rate from exam 1, and 78.04% of correct rate from exam 2 (doing comparison with manual segmentation) and using mean squared error rate on same technique, was observed 0.33 for exam 1 and for exam 2 was of 12.05. Doing the comparison of this techniques for enhancement of CT images can be observed which one is better for do the enhancement of liver CT images before the use of segmentation technique, and for slices which radiological contrast reached a great performance.

MR defecography registration for computer-aided diagnosis of pelvic floor disorder

Over the last decades, the interest in the use of the defecography for the investigation of defecation problems and pelvic floor disorders has increased. The MR defecography assists in the diagnosis of pelvic floor weakening, fecal incontinence, painful defection and genital prolapse. To identify an abnormal morphological variation of the structures relevant for the diagnosis, the radiologist derives several static measures at different moments and at different maneuvers during the exam. However, there is a poor agreement between independent observers for the measurement of the anorectal angle, which is a critical parameter for the interpretation of the defecography. With the aim of reducing the inter-observer variability and assisting the radiologist in the interpretation of the MR defecography for the diagnosis of fecal incontinence, we propose calculating dynamic changes of anorectal junction during the defecation activity. To that end we propose to propagate, automatically, the location of pre-defined landmarks throughout the frames of the MR defecography, for each maneuver, via image registration based on variational model. The analysis of the results shows that our proposal was well succeeded in the propagation of the initial landmarks and to calculate the dynamic changes during each maneuver.

Síndrome de Hallervorden Spatz: achados na resonância magnética. Relato de caso

Hallervorden-Spatz syndrome is a neurodegenerative disease, autosomic recessive with two clinical features: early and late onset. Psychiatric, pyramidal and extrapyramidal signs are present in the late subtype. We report the case of a 41-old woman with extrapyramidal signs. Magnetic resonance imaging (MRI) showed the eye-of-the-tiger sign in the medial globus pallidus. This is due to a gliosis (increased signal) and accumulation of surrounding iron (decreased signal intensity) in long TR sequences. There is a strong relationship between MRI findings and the gene mutation responsable for this disease. It makes the MRI sensible for diagnosing this syndrome.

Novel Mahalanobis-based feature selection improves one-class classification of early hepatocellular carcinoma

Detection of early hepatocellular carcinoma (HCC) is responsible for increasing survival rates in up to 40%. One-class classifiers can be used for modeling early HCC in multidetector computed tomography (MDCT), but demand the specific knowledge pertaining to the set of features that best describes the target class. Although the literature outlines several features for characterizing liver lesions, it is unclear which is most relevant for describing early HCC. In this paper, we introduce an unconstrained GA feature selection algorithm based on a multi-objective Mahalanobis fitness function to improve the classification performance for early HCC. We compared our approach to a constrained Mahalanobis function and two other unconstrained functions using Welch’s t-test and Gaussian Data Descriptors. The performance of each fitness function was evaluated by cross-validating a one-class SVM. The results show that the proposed multi-objective Mahalanobis fitness function is capable of significantly reducing data dimensionality (96.4%) and improving one-class classification of early HCC (0.84 AUC). Furthermore, the results provide strong evidence that intensity features extracted at the arterial to portal and arterial to equilibrium phases are important for classifying early HCC.

Histiocitoma fibroso benigno profundo: achados na tomografia computadorizada e histologia

Apresentamos imagens de tomografia computadorizada de um paciente de 83 anos de idade com histiocitoma fibroso benigno profundo, na face lateral da perna esquerda, com evolucao de longa data. A tomografia computadorizada observamos massa bem delimitada, ovalada, e que apresentava intenso realce periferico com uso do meio de contraste iodado. Este e um tumor de partes moles pouco frequente e com raros relatos dos seus aspectos de imagem.

Enxaqueca oftalmoplégica: achados à ressonância magnética. Relato de caso

A enxaqueca oftalmoplegica e sindrome rara em que a cefaleia se associa a oftalmoplegia por paralisia do terceiro, quarto ou sexto nervos cranianos. Ocorre mais frequentemente em criancas e adolescentes. Ao exame de ressonância magnetica (RM), com uso de gadolinio, e observado realce transitorio do nervo afetado. Apresentamos o caso de um adolescente, 16 anos, masculino, com historia tipica e hipersinal nas sequencias ponderadas em T1 pos-infusao venosa do gadolinio na porcao cisternal do nervo oculomotor esquerdo. No exame de controle, realizado 18 meses depois, houve remissao completa das alteracoes na RM. O hipersinal do oculomotor a RM e sempre patologico; entre os diagnosticos diferenciais devemos incluir neoplasias (linfoma, leucemia), infeccoes (SIDA, sifilis), doencas inflamatorias nao-infecciosas (sarcoidose, sindrome de Tolosa-Hunt) e vasculares (aneurisma da arteria comunicante posterior).