121 research outputs found
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Detection of calcifications within a medical image
A method of detecting a calcification in a bounding box enclosing a portion of a medical image, including the steps of obtaining the medical image in digital form, filtering at least image data in the bounding box using a difference of Gaussians (DOG) filter, and thresholding the filtered image data to detect, as one or more calcifications, portions of the filtered image data which exceed a threshold. The detected calcification may be classified by segmenting the one or more detected calcifications, extracting at least one feature from the one or more segmented calcifications, and determining a likelihood of malignancy of the one or more detected calcifications
IMCAD: Computer Aided System for Breast Masses Detection based on Immune Recognition
Computer Aided Detection (CAD) systems are very important tools which help radiologists as a second reader in detecting early breast cancer in an efficient way, specially on screening mammograms. One of the challenging problems is the detection of masses, which are powerful signs of cancer, because of their poor apperance on mammograms. This paper investigates an automatic CAD for detection of breast masses in screening mammograms based on fuzzy segmentation and a bio-inspired method for pattern recognition: Artificial Immune Recognition System. The proposed approach is applied to real clinical images from the full field digital mammographic database: Inbreast. In order to validate our proposition, we propose the Receiver Operating Characteristic Curve as an analyzer of our IMCAD classifier system, which achieves a good area under curve, with a sensitivity of 100% and a specificity of 95%. The recognition system based on artificial immunity has shown its efficiency on recognizing masses from a very restricted set of training regions
Quantification and segmentation of breast cancer diagnosis: efficient hardware accelerator approach
The mammography image eccentric area is the breast density percentage
measurement. The technical challenge of quantification in radiology leads to
misinterpretation in screening. Data feedback from society, institutional, and industry
shows that quantification and segmentation frameworks have rapidly become the
primary methodologies for structuring and interpreting mammogram digital images.
Segmentation clustering algorithms have setbacks on overlapping clusters, proportion,
and multidimensional scaling to map and leverage the data. In combination,
mammogram quantification creates a long-standing focus area. The algorithm
proposed must reduce complexity and target data points distributed in iterative, and
boost cluster centroid merged into a single updating process to evade the large storage
requirement. The mammogram database's initial test segment is critical for evaluating
performance and determining the Area Under the Curve (AUC) to alias with medical
policy. In addition, a new image clustering algorithm anticipates the need for largescale
serial and parallel processing. There is no solution on the market, and it is
necessary to implement communication protocols between devices. Exploiting and
targeting utilization hardware tasks will further extend the prospect of improvement in
the cluster. Benchmarking their resources and performance is required. Finally, the
medical imperatives cluster was objectively validated using qualitative and
quantitative inspection. The proposed method should overcome the technical
challenges that radiologists face
DEEP LEARNING BASED SEGMENTATION AND CLASSIFICATION FOR IMPROVED BREAST CANCER DETECTION
Breast Cancer is a leading killer of women globally. It is a serious health concern caused by calcifications or abnormal tissue growth in the breast. Doing a screening and identifying the nature of the tumor as benign or malignant is important to facilitate early intervention, which drastically decreases the mortality rate. Usually, it uses ultrasound images, since they are easily accessible to most people and have no drawbacks as such, unlike in the other most famous screening technique of mammograms where in some cases you may not get a clear scan. In this thesis, the approach to this problem is to build a stacked model which makes predictions on the basis of the shape, pattern, and spread of the tumor. To achieve this, typical steps are pre-processing of images followed by segmentation of the image and classification. For pre-processing, the proposed approach in this thesis uses histogram equalization that helps in improving the contrast of the image, making the tumor stand out from its surroundings, and making it easier for the segmentation step. Through segmentation, the approach uses UNet architecture with a ResNet backbone. The UNet architecture is made specifically for biomedical imaging. The aim of segmentation is to separate the tumor from the ultrasound image so that the classification model can make its predictions from this mask. The metric result of the F1-score for the segmentation model turned out to be 97.30%. For classification, the CNN base model is used for feature extraction from provided masks. These are then fed into a network and the predictions are done. The base CNN model used is ResNet50 and the neural network used for the output layer is a simple 8-layer network with ReLU activation in the hidden layers and softmax in the final decision-making layer. The ResNet weights are initialized from training on ImageNet. The ResNet50 returns 2048 features from each mask. These are then fed into the network for decision-making. The hidden layers of the neural network have 1024, 512, 256, 128, 64, 32, and 10 neurons respectively. The classification accuracy achieved for the proposed model was 98.61% with an F1 score of 98.41%. The detailed experimental results are presented along with comparative data
Novel Computer-Aided Diagnosis Schemes for Radiological Image Analysis
The computer-aided diagnosis (CAD) scheme is a powerful tool in assisting clinicians (e.g., radiologists) to interpret medical images more accurately and efficiently. In developing high-performing CAD schemes, classic machine learning (ML) and deep learning (DL) algorithms play an essential role because of their advantages in capturing meaningful patterns that are important for disease (e.g., cancer) diagnosis and prognosis from complex datasets. This dissertation, organized into four studies, investigates the feasibility of developing several novel ML-based and DL-based CAD schemes for different cancer research purposes. The first study aims to develop and test a unique radiomics-based CT image marker that can be used to detect lymph node (LN) metastasis for cervical cancer patients. A total of 1,763 radiomics features were first computed from the segmented primary cervical tumor depicted on one CT image with the maximal tumor region. Next, a principal component analysis algorithm was applied on the initial feature pool to determine an optimal feature cluster. Then, based on this optimal cluster, machine learning models (e.g., support vector machine (SVM)) were trained and optimized to generate an image marker to detect LN metastasis. The SVM based imaging marker achieved an AUC (area under the ROC curve) value of 0.841 ± 0.035. This study initially verifies the feasibility of combining CT images and the radiomics technology to develop a low-cost image marker for LN metastasis detection among cervical cancer patients. In the second study, the purpose is to develop and evaluate a unique global mammographic image feature analysis scheme to identify case malignancy for breast cancer. From the entire breast area depicted on the mammograms, 59 features were initially computed to characterize the breast tissue properties in both the spatial and frequency domain. Given that each case consists of two cranio-caudal and two medio-lateral oblique view images of left and right breasts, two feature pools were built, which contain the computed features from either two positive images of one breast or all the four images of two breasts. For each feature pool, a particle swarm optimization (PSO) method was applied to determine the optimal feature cluster followed by training an SVM classifier to generate a final score for predicting likelihood of the case being malignant. The classification performances measured by AUC were 0.79±0.07 and 0.75±0.08 when applying the SVM classifiers trained using image features computed from two-view and four-view images, respectively. This study demonstrates the potential of developing a global mammographic image feature analysis-based scheme to predict case malignancy without including an arduous segmentation of breast lesions. In the third study, given that the performance of DL-based models in the medical imaging field is generally bottlenecked by a lack of sufficient labeled images, we specifically investigate the effectiveness of applying the latest transferring generative adversarial networks (GAN) technology to augment limited data for performance boost in the task of breast mass classification. This transferring GAN model was first pre-trained on a dataset of 25,000 mammogram patches (without labels). Then its generator and the discriminator were fine-tuned on a much smaller dataset containing 1024 labeled breast mass images. A supervised loss was integrated with the discriminator, such that it can be used to directly classify the benign/malignant masses. Our proposed approach improved the classification accuracy by 6.002%, when compared with the classifiers trained without traditional data augmentation. This investigation may provide a new perspective for researchers to effectively train the GAN models on a medical imaging task with only limited datasets. Like the third study, our last study also aims to alleviate DL models’ reliance on large amounts of annotations but uses a totally different approach. We propose employing a semi-supervised method, i.e., virtual adversarial training (VAT), to learn and leverage useful information underlying in unlabeled data for better classification of breast masses. Accordingly, our VAT-based models have two types of losses, namely supervised and virtual adversarial losses. The former loss acts as in supervised classification, while the latter loss works towards enhancing the model’s robustness against virtual adversarial perturbation, thus improving model generalizability. A large CNN and a small CNN were used in this investigation, and both were trained with and without the adversarial loss. When the labeled ratios were 40% and 80%, VAT-based CNNs delivered the highest classification accuracy of 0.740±0.015 and 0.760±0.015, respectively. The experimental results suggest that the VAT-based CAD scheme can effectively utilize meaningful knowledge from unlabeled data to better classify mammographic breast mass images. In summary, several innovative approaches have been investigated and evaluated in this dissertation to develop ML-based and DL-based CAD schemes for the diagnosis of cervical cancer and breast cancer. The promising results demonstrate the potential of these CAD schemes in assisting radiologists to achieve a more accurate interpretation of radiological images
Applications of Medical Physics
Applications of Medical Physics” is a Special Issue of Applied Sciences that has collected original research manuscripts describing cutting-edge physics developments in medicine and their translational applications. Reviews providing updates on the latest progresses in this field are also included. The collection includes a total of 20 contributions by authors from 9 different countries, which cover several areas of medical physics, spanning from radiation therapy, nuclear medicine, radiology, dosimetry, radiation protection, and radiobiology
Risk assessment and prevention of breast cancer
One woman in eight develops breast cancer during her lifetime in the Western world.
Measures are warranted to reduce mortality and to prevent breast cancer. Mammography
screening reduces mortality by early detection. However, approximately one fourth of the
women who develop breast cancer are diagnosed within two years after a negative screen.
There is a need to identify the short-term risk of these women to better guide clinical followup.
Another drawback of mammography screening is that it focuses on early detection only
and not on breast cancer prevention. Today, it is known that women attending screening can
be stratified into high and low risk of breast cancer. Women at high risk could be offered
preventive measures such as low-dose tamoxifen to reduce breast cancer incidence. Women at
low risk do not benefit from screening and could be offered less frequent screening.
In study I, we developed and validated the mammographic density measurement tool
STRATUS to enable mammogram resources at hospitals for large scale epidemiological studies
on risk, masking, and therapy response in relation to breast cancer. STRATUS showed similar
measurement results on different types of mammograms at different hospitals. Longitudinal
studies on mammographic density could also be analysed more accurate with less nonbiological
variability.
In study II, we developed and validated a short-term risk model based on mammographic
features (mammographic density, microcalcifications, masses) and differences in occurrences
of mammographic features between left and right breasts. The model could optionally be
expanded with lifestyle factors, family history of breast cancer, and genetic determinants. Based
on the results, we showed that among women with a negative mammography screen, the
short-term risk tool was suitable to identify women that developed breast cancer before or at
next screening. We also showed that traditional long-term risk models were less suitable to
identify the women who in a short time-period after risk assessment were diagnosed with
breast cancer.
In study III, we performed a phase II trial to identify the lowest dose of tamoxifen that could
reduce mammographic density, an early marker for reduced breast cancer risk, to the same
extent as standard 20 mg dose but cause less side-effects. We identified 2.5 mg tamoxifen to be
non-inferior for reducing mammographic density. The women who used 2.5 mg tamoxifen
also reported approximately 50% less severe vasomotor side-effects.
In study IV, we investigated the use of low-dose tamoxifen for an additional clinical use case
to increase screening sensitivity through its effect on reducing mammographic density. It was
shown that 24% of the interval cancers have a potential to be detected at prior screen.
In conclusion, tools were developed for assessing mammographic density and breast cancer
risk. In addition, two low-dose tamoxifen concepts were developed for breast cancer
prevention and improved screening sensitivity. Clinical prospective validation is further needed
for the risk assessment tool and the low-dose tamoxifen concepts for the use in breast cancer
prevention and for reducing breast cancer mortality
A Bottom-Up Review of Image Analysis Methods for Suspicious Region Detection in Mammograms.
Breast cancer is one of the most common death causes amongst women all over the world. Early detection of breast cancer plays a critical role in increasing the survival rate. Various imaging modalities, such as mammography, breast MRI, ultrasound and thermography, are used to detect breast cancer. Though there is a considerable success with mammography in biomedical imaging, detecting suspicious areas remains a challenge because, due to the manual examination and variations in shape, size, other mass morphological features, mammography accuracy changes with the density of the breast. Furthermore, going through the analysis of many mammograms per day can be a tedious task for radiologists and practitioners. One of the main objectives of biomedical imaging is to provide radiologists and practitioners with tools to help them identify all suspicious regions in a given image. Computer-aided mass detection in mammograms can serve as a second opinion tool to help radiologists avoid running into oversight errors. The scientific community has made much progress in this topic, and several approaches have been proposed along the way. Following a bottom-up narrative, this paper surveys different scientific methodologies and techniques to detect suspicious regions in mammograms spanning from methods based on low-level image features to the most recent novelties in AI-based approaches. Both theoretical and practical grounds are provided across the paper sections to highlight the pros and cons of different methodologies. The paper's main scope is to let readers embark on a journey through a fully comprehensive description of techniques, strategies and datasets on the topic
Modern Approaches To Quality Control
Rapid advance have been made in the last decade in the quality control procedures and techniques, most of the existing books try to cover specific techniques with all of their details. The aim of this book is to demonstrate quality control processes in a variety of areas, ranging from pharmaceutical and medical fields to construction engineering and data quality. A wide range of techniques and procedures have been covered
Mammography Techniques and Review
Mammography remains at the backbone of medical tools to examine the human breast. The early detection of breast cancer typically uses adjunct tests to mammogram such as ultrasound, positron emission mammography, electrical impedance, Computer-aided detection systems and others. In the present digital era it is even more important to use the best new techniques and systems available to improve the correct diagnosis and to prevent mortality from breast cancer. The first part of this book deals with the electrical impedance mammographic scheme, ultrasound axillary imaging, position emission mammography and digital mammogram enhancement. A detailed consideration of CBR CAD System and the availability of mammographs in Brazil forms the second part of this book. With the up-to-date papers from world experts, this book will be invaluable to anyone who studies the field of mammography
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