Artificial Intelligence for Mammography and Digital Breast Tomosynthesis: Current Concepts and Future Perspectives.

Although computer-aided diagnosis (CAD) is widely used in mammography, conventional CAD programs that use prompts to indicate potential cancers on the mammograms have not led to an improvement in diagnostic accuracy. Because of the advances in machine learning, especially with use of deep (multilayered) convolutional neural networks, artificial intelligence has undergone a transformation that has improved the quality of the predictions of the models. Recently, such deep learning algorithms have been applied to mammography and digital breast tomosynthesis (DBT). In this review, the authors explain how deep learning works in the context of mammography and DBT and define the important technical challenges. Subsequently, they discuss the current status and future perspectives of artificial intelligence-based clinical applications for mammography, DBT, and radiomics. Available algorithms are advanced and approach the performance of radiologists-especially for cancer detection and risk prediction at mammography. However, clinical validation is largely lacking, and it is not clear how the power of deep learning should be used to optimize practice. Further development of deep learning models is necessary for DBT, and this requires collection of larger databases. It is expected that deep learning will eventually have an important role in DBT, including the generation of synthetic images.

The Future of Contrast-Enhanced Mammography.

OBJECTIVE: The purpose of this article is to discuss facilitators of and barriers to future implementation of contrast-enhanced mammography (CEM) in the United States. CONCLUSION: CEM provides low-energy 2D mammographic images analogous to digital mammography and contrast-enhanced recombined images that allow assessment of neovascularity similar to that offered by MRI. The utilization of CEM in the United States is currently low but could increase rapidly given the many potential indications for its clinical use.

Immediate Vascular Imaging Needed for Efficient Triage of Patients With Acute Ischemic Stroke Initially Admitted to Nonthrombectomy Centers.

BACKGROUND AND PURPOSE: Current guidelines for endovascular thrombectomy (EVT) used to select patients for transfer to thrombectomy-capable stroke centers (TSC) may result in unnecessary transfers. We sought to determine the impact of simulated baseline vascular imaging on reducing unnecessary transfers and clinical-imaging factors associated with receiving EVT after transfer. METHODS: We identified patients with stroke transferred for EVT from 30 referring hospitals between 2010 and 2016 who had a referring hospitals brain computed tomography and repeat imaging on TSC arrival available for review. Initial Alberta Stroke Program Early CT scores and TSC vascular occlusion level were assessed. The main outcome variable was receiving EVT at TSC. Models were simulated to derive optimal triaging parameters for EVT. RESULTS: A total of 508 patients were included in the analysis (mean age, 69±14 years; 42% women). Application at referring hospitals of current guidelines for EVT yielded sensitivity of 92% (95% confidence interval, 0.84-0.96) and specificity of 53% (95% confidence interval, 0.48-0.57) for receiving EVT at TSC. Repeated simulations identified optimal selection criteria for transfer as National Institute of Health Stroke Scale >8 plus baseline vascular imaging (sensitivity=91%; 95% confidence interval, 0.83-0.95; and specificity=80%; 95% confidence interval, 0.75-0.83). CONCLUSIONS: Our findings provide quantitative estimates of the claim that implementing vascular imaging at the referring hospitals would result in significantly fewer futile transfers for EVT and a data-driven framework to inform transfer policies.

Advances in Digital Breast Tomosynthesis.

OBJECTIVE: Digital breast tomosynthesis (DBT) has rapidly emerged as an important new imaging tool that reduces the masking effect of overlapping fibroglandular tissue, thereby improving breast cancer detection. This article will review key features of DBT including technique, clinical implementation, and benign and malignant imaging findings. We will also present the benefits of DBT in screening, diagnostic workup, and image-guided biopsy. CONCLUSION: Tomosynthesis improves interpretive performance and will likely replace conventional 2D mammography in clinical practice.

[Detection of lung nodules. New opportunities in chest radiography]. / Detektion pulmonaler Rundherde. Neue Möglichkeiten der Thoraxradiographie.

BACKGROUND: Chest radiography still represents the most commonly performed X-ray examination because it is readily available, requires low radiation doses and is relatively inexpensive. However, as previously published, many initially undetected lung nodules are retrospectively visible in chest radiographs. STANDARD RADIOLOGICAL METHODS: The great improvements in detector technology with the increasing dose efficiency and improved contrast resolution provide a better image quality and reduced dose needs. METHODICAL INNOVATIONS: The dual energy acquisition technique and advanced image processing methods (e.g. digital bone subtraction and temporal subtraction) reduce the anatomical background noise by reduction of overlapping structures in chest radiography. Computer-aided detection (CAD) schemes increase the awareness of radiologists for suspicious areas. RESULTS: The advanced image processing methods show clear improvements for the detection of pulmonary lung nodules in chest radiography and strengthen the role of this method in comparison to 3D acquisition techniques, such as computed tomography (CT). ASSESSMENT: Many of these methods will probably be integrated into standard clinical treatment in the near future. Digital software solutions offer advantages as they can be easily incorporated into radiology departments and are often more affordable as compared to hardware solutions.

[Report based on Fiscal 2010 Diagnostic X-ray Equipment Questionnaire Survey (conditions of X-ray units and similar equipment)].

On X-ray diagnostic technology, it is important to grasp a change of the X-ray high-voltage equipment and radiographic technique factors. The 1st questionnaire was performed in 1974, and it carried out after that every five years, and conducted 8th investigation. As a result, we requested 656 institutions and got a reply from 103 institutions. The response rate was 15.7%. For X-ray high-voltage equipment, the inverter-type device shifts to 83.6% from 73.4% of last time. X-ray high-voltage equipment will be shifted to inverter-type device the near future. For X-ray tube device, the target angle becomes more smaller than usual, and maximum anode heat content is increasing tendency. The spread of digital devices is being advanced, and especially the flat panel detector (FPD) increases in the devices. The spread of soft copy diagnoses is 73.8% for chest image diagnoses, and 49.5% for breast image diagnosis. For the device management, the ratio of institutions measured at purchase time was 91.2%. But, the ratio of institutions performed an invariability examination was 58.4%. It is required to grasp the performance of an X-ray equipment and peripheral equipment, and to perform accuracy control in order to obtain proper radiographic technique factors and imaging. In order to use it for the improvement in photography technology, we would like to continue to conduct this investigation periodically.

[Development of a digital chest phantom for studies on energy subtraction techniques].

Digital chest phantoms continue to play a significant role in optimizing imaging parameters for chest X-ray examinations. The purpose of this study was to develop a digital chest phantom for studies on energy subtraction techniques under ideal conditions without image noise. Computed tomography (CT) images from the LIDC (Lung Image Database Consortium) were employed to develop a digital chest phantom. The method consisted of the following four steps: 1) segmentation of the lung and bone regions on CT images; 2) creation of simulated nodules; 3) transformation to attenuation coefficient maps from the segmented images; and 4) projection from attenuation coefficient maps. To evaluate the usefulness of digital chest phantoms, we determined the contrast of the simulated nodules in projection images of the digital chest phantom using high and low X-ray energies, soft tissue images obtained by energy subtraction, and "gold standard" images of the soft tissues. Using our method, the lung and bone regions were segmented on the original CT images. The contrast of simulated nodules in soft tissue images obtained by energy subtraction closely matched that obtained using the gold standard images. We thus conclude that it is possible to carry out simulation studies based on energy subtraction techniques using the created digital chest phantoms. Our method is potentially useful for performing simulation studies for optimizing the imaging parameters in chest X-ray examinations.

[Irreversible image compression in radiology. Current status]. / Irreversible Bilddatenkompression in der Radiologie. Aktueller Status.

Due to increasing amounts of data in radiology methods for image compression appear both economically and technically interesting. Irreversible image compression allows markedly higher reduction of data volume in comparison with reversible compression algorithms but is, however, accompanied by a certain amount of mathematical and visual loss of information. Various national and international radiological societies have published recommendations for the use of irreversible image compression. The degree of acceptable compression varies across modalities and regions of interest.The DICOM standard supports JPEG, which achieves compression through tiling, DCT/DWT and quantization. Although mathematical loss due to rounding up errors and reduction of high frequency information occurs this results in relatively low visual degradation.It is still unclear where to implement irreversible compression in the radiological workflow as only few studies analyzed the impact of irreversible compression on specialized image postprocessing. As long as this is within the limits recommended by the German Radiological Society irreversible image compression could be implemented directly at the imaging modality as it would comply with § 28 of the roentgen act (RöV).

Trend of contrast detection threshold with and without localization.

Published information on contrast detection threshold is based primarily on research using a location-known methodology. In previous work on testing the Digital Imaging and Communications in Medicine (DICOM) Grayscale Standard Display Function (GSDF) for perceptual linearity, this research group used a location-unknown methodology to more closely reflect clinical practice. A high false-positive rate resulted in a high variance leading to the conclusion that the impact on results of employing a location-known methodology needed to be explored. Fourteen readers reviewed two sets of simulated mammographic background images, one with the location-unknown and one with the location-known methodology. The results of the reader study were analyzed using Reader Operating Characteristic (ROC) methodology and a paired t test. Contrast detection threshold was analyzed using contingency tables. No statistically significant difference was found in GSDF testing, but a highly statistical significant difference (p value <0.0001) was seen in the ROC (AUC) curve between the location-unknown and the location-known methodologies. Location-known methodology not only improved the power of the GSDF test but also affected the contrast detection threshold which changed from +3 when the location was unknown to +2 gray levels for the location-known images. The selection of location known versus unknown in experimental design must be carefully considered to ensure that the conclusions of the experiment reflect the study's objectives.

Our path to a filmless future.

Film-based radiographs are still being used to teach in a conference format, which presents several viewing challenges amongst other problems. In the age of cloud computing, which enables the use of online server storage space, this information could be used more effectively if it were digitized. However, digitizing film-based radiographs and making them available for use in the cloud is not as easy as it seems. In order to address the issue of digitizing the film-based radiograph libraries in our radiology department, we looked at several options. The option that we chose was a consumer-grade scanner, and this decision was based on price, resolution, shades of gray, built-in transparency function, and its physical attributes. Our goal was to digitize the film-based radiograph teaching files so they could be stored in a digital file locker such as Google Picassa for organization and quick access later. These files would constantly be updated in a Google document by residents, and this document would be called the "Living Document" based on its continuous expandability. This method would allow even the smallest radiology department to benefit from the use of modern technology to gain access to valuable information stored in film-based radiographs and give every resident the opportunity to benefit from it.

Digital radiography for the equine practitioner: basic principles and recent advances.

As availability increases and cost decreases, digital radiograph systems become more common in equine practice. Technological advances provide an array of choices for the equine practitioner considering purchase. Two classes of systems are available: computed radiography and flat-panel systems (direct radiography). Image processing encompasses all manipulations performed on an image at acquisition and can have a profound effect on the final digital radiograph. Consideration should be given to the type of display monitor because many options are now available. The type of display monitor and the viewing environment have an effect on interpretation performance.

Consequences of digital mammography in population-based breast cancer screening: initial changes and long-term impact on referral rates.

OBJECTIVES: To investigate the referral pattern after the transition to full-field digital mammography (FFDM) in a population-based breast cancer screening programme. METHODS: Preceding the nationwide digitalisation of the Dutch screening programme, an FFDM feasibility study was conducted. Detection and referral rates for FFDM and screen-film mammography (SFM) were compared for first and subsequent screens. Furthermore, radiological characteristics of referrals in digital screening were assessed. RESULTS: A total of 312,414 screening mammograms were performed (43,913 digital and 268,501 conventional), with 4,473 consecutive referrals (966 following FFDM). Initially the FFDM referral rate peaked, and many false-positive results were noted as a consequence of pseudolesions and increased detection of (benign) microcalcifications. A higher overall referral rate was observed in FFDM screening in both first and subsequent examinations (p < .001), with a significant increase in cancer detection (p = .010). CONCLUSION: As a result of initial inexperience with digital screening images implementing FFDM in a population-based breast cancer screening programme may lead to a strong, but temporary increase in referral. Dedicated training in digital screening for radiographers and screening radiologists is therefore recommended. Referral rates decrease and stabilise (learning curve effect) at a higher level than in conventional screening, yet with significantly enhanced cancer detection.

New and evolving concepts in the imaging and management of urolithiasis: urologists' perspective.

Urolithiasis is a universal problem that has become increasingly prevalent in the United States and has a high rate of recurrence. Imaging of urolithiasis has evolved over the years due to technologic advances and a better understanding of the disease process. Computed tomography (CT) has been the investigation of choice for the evaluation of urinary stone disease. The emergence of multidetector CT and the recent introduction of dual-energy CT have further reinforced the superiority of this modality over other imaging techniques in the management of urolithiasis. Multidetector CT is not limited to simply helping make an accurate diagnosis in patients with stone disease; it is also useful in the assessment of stone burden, composition, and fragility, findings that are helpful in determining appropriate treatment strategies. In addition, multidetector CT is a valuable tool in the follow-up of patients after urologic intervention or institution of medical therapy. Familiarity with recent technologic developments will help radiologists meet the growing expectations of urologists in this setting. In addition, radiologists should be aware of the radiation risks inherent in the imaging of patients with urolithiasis and take appropriate measures to minimize this risk and optimize image quality.

Workflow efficiency comparison of a new CR system with traditional CR and DR systems in an orthopedic setting.

Workflow efficiency is a crucial factor in selecting computed radiography (CR) versus digital radiography (DR) systems for digital projection radiography operations. DR systems can be more efficient, but present higher costs and limitations in performing some radiographic exams. A newly developed CR system presents a good alternative with its faster line-by-line instead of pixel-by-pixel image plate-scanning technology and a more efficient workstation. To evaluate workflow characteristics, a time-motion study was conducted to compare radiographic exam times of the new CR system with traditional CR and DR systems in a high-volume orthopedic operation. Approximately 200 exams for each modality were documented from the moment when a patient entered the X-ray room to the moment when all images were sent to the PACS archive using a timer and speech-recognition software. Applying Welch ANOVA and Tamhane's T2 tests, average exam times for the new CR system were significantly faster (18-42%; P ≤ 0.025) than for the traditional CR system. Average exam times for the DR system were also faster than for the new CR system by 22-36% (P<0.001) with one exception. In the case where the new CR system was located outside the X-ray room, using a one-technologist workflow model, average single-study exam times were not significantly different from those found when using DR. Therefore, the new CR system may be comparable in efficiency with the DR system for this particular setting and operation.

The caBIG annotation and image Markup project.

Image annotation and markup are at the core of medical interpretation in both the clinical and the research setting. Digital medical images are managed with the DICOM standard format. While DICOM contains a large amount of meta-data about whom, where, and how the image was acquired, DICOM says little about the content or meaning of the pixel data. An image annotation is the explanatory or descriptive information about the pixel data of an image that is generated by a human or machine observer. An image markup is the graphical symbols placed over the image to depict an annotation. While DICOM is the standard for medical image acquisition, manipulation, transmission, storage, and display, there are no standards for image annotation and markup. Many systems expect annotation to be reported verbally, while markups are stored in graphical overlays or proprietary formats. This makes it difficult to extract and compute with both of them. The goal of the Annotation and Image Markup (AIM) project is to develop a mechanism, for modeling, capturing, and serializing image annotation and markup data that can be adopted as a standard by the medical imaging community. The AIM project produces both human- and machine-readable artifacts. This paper describes the AIM information model, schemas, software libraries, and tools so as to prepare researchers and developers for their use of AIM.

[Ultra-low dose radiology, an innovative technology]. / La radiologie ultra-basse dose, une technologie novatrice.

Ultra-low dose radiology is an innovative system of digital imaging combining technological performance and the well-being of the child. This technique preserves the health status of children whilst offering spectacular, extremely high-quality images. Its use is radically changing practices and facilitating care.

Tomosynthesis imaging: at a translational crossroads.

Tomosynthesis is a decades-old technique for section imaging that has seen a recent upsurge in interest due to its promise to provide three-dimensional information at lower dose and potentially lower cost than CT in certain clinical imaging situations. This renewed interest in tomosynthesis began in the late 1990s as a new generation of flat-panel detectors became available; these detectors were the one missing piece of the picture that had kept tomosynthesis from enjoying significant utilization earlier. In the past decade, tomosynthesis imaging has been investigated in a variety of clinical imaging situations, but the two most prominent have been in breast and chest imaging. Tomosynthesis has the potential to substantially change the way in which breast cancer and pulmonary nodules are detected and managed. Commercial tomosynthesis devices are now available or on the horizon. Many of the remaining research activities with tomosynthesis will be translational in nature and will involve physicist and clinician alike. This overview article provides a forward-looking assessment of the translational questions facing tomosynthesis imaging and anticipates some of the likely research and clinical activities in the next five years.

Coronary CT angiography (CCTA) and advances in CT plaque imaging.

The goal of this review is to highlight current advances in the non-invasive detection of clinically significant atherosclerotic disease including the so-called vulnerable plaque with computed tomography. Atherosclerotic disease encompasses stages of plaque progression, stabilization, and even regression. Traditionally, the focus of diagnostic imaging has been the detection of lumen-occluding atheroma. However, advances in our understanding of the pathophysiology of atherosclerotic plaque have shown that, in certain stages of plaque progression, plaque is "vulnerable" and able to cause acute coronary syndromes despite "non-significant" vascular occlusion at baseline. This provides a rationale to improve our non-invasive imaging technology. Presented here are improvements in soft-tissue resolution with technical advancements as well as contrast-enhancement and lately even nanotechnology-based technology which are geared to detect the clinically elusive vulnerable plaque and provide an opportunity for preventative therapy.