Index of content:
Volume 35, Issue 6, June 2008
- Imaging Symposium: Room 342
- Advances in Breast Imaging
35(2008); http://dx.doi.org/10.1118/1.2962601View Description Hide Description
Over the last decade, there have been tremendous advances in breast imaging. As many facilities make the transition from film screen to digital mammography, it is appropriate to examine the accomplishments of the past and to acknowledge current technological limitations. In addition, we should carefully study evolving technologies in breast imaging with the goal of developing highly sensitive and highly specific techniques. This presentation will examine recent progress in digital mammography, including contrast‐enhanced imaging,tomosynthesis, and breast CT, from a breast imager's perspective.
Randomized clinical trials and meta‐analyses have shown that screening mammography results in a decrease in breast cancer mortality. Although mammography is efficacious in most women, we know that mammography is not a perfect test, epecially in women with radiographically dense breasts. Furthermore, false positive and false negative mammograms are difficult to eliminate. As digital mammography replaces film screen mammography in many practice settings, cancer detection rates may rise slightly and call back rates may decrease slightly.
Overlapping densities and areas of dense tissue often make interpretation of film screen mammograms difficult.. Overlapping parenchyma and dense tissue hinder digital mammography less than film screen mammography, but these overlying structures are not eliminated with digital mammography. Major efforts have been made in digital tomosynthesis and breast CT in order to advance beyond projection imaging.Tomosynthesis involves the acquisition of tomographic images in the digital mammography unit, while breast CT is based on a volumetric acquisition with the patient positioned prone in a machine that is similar to a unit used for stereotactic biopsies.
Conventional digital mammography, digital tomosynthesis, and breast CT may be combined with the injection of iodinated contrast material in order to visualize tumor vascularity and increase the conspicuity of breast tumors. These techniques may also be used to monitor response to neoadjuvant chemotherapy.
Over the next decade, tomosynthesis and breast CT will transition from research applications to clinical realities. Further studies are needed in order to determine how to use these emerging tools in an effective, efficacious manner.
1. To review advances in breast imaging over the last decade.
2. To understand the strengths and weaknesses of film screen and digital mammography.
3. To appreciate the potential roles of digital tomosynthesis and breast CT.
4. To understand the application of iodinated contrast material in digital mammography,tomosynthesis, and breast CT.
35(2008); http://dx.doi.org/10.1118/1.2962602View Description Hide Description
Digital tomosynthesis (or “tomo”) is revolutionizing breast imaging. Based on modified full‐field digital mammography systems, breast tomo can achieve limited‐angle cone‐beam CTimaging which produces 3D slice images of the breast. This addresses the problem of overlapping dense tissue which is the most common cause for unnecessary callbacks as well as missed cancers in mammography screening. Tomo can provide 3D images while remaining comparable to mammography in terms of speed, resolution, cost, and dose. For these reasons, tomo may be only imaging technique with the potential to completely replace the current role of mammography as the primary tool in breast cancer screening and diagnosis. FDA approval is imminent, so it is all the more important for medical physicists to understand this new modality's potential as well as limitations.
This presentation will cover both the hype and hope surrounding breast tomosynthesis. What do the initial clinical trials suggest about its performance? What are the on‐going physics issues in terms of clinical implementation, including compression, dose, and QA? What are some of the latest results from different research groups working on optimization of radiographic techniques, acquisition modes, and reconstruction algorithms? What is coming down the road in terms of advanced applications including quantitative imaging,computer aided detection, and contrast enhanced imaging? We will explore the answers to these and other questions together.
The work discussed in this presentation was supported in part by grants from NIH/NCI, US Army Breast Cancer Research Program, Susan G. Komen for the Cure, General Electric Company, Hologic, and Siemens Medical Solutions.
1. Understand the difference between breast tomosynthesis and dedicated breast CT.
2. Appreciate the many medical physics issues involved in the development and optimization of breast tomosynthesis.
3. Understand the clinical promise and concerns of using breast tomosynthesis.
35(2008); http://dx.doi.org/10.1118/1.2962603View Description Hide Description
For almost 70 years mammography has given insight into breast morphology, allowing cancer detection based on the gross impact of the disease upon body. The advent of tomographic techniques has allowed visualization of morphologic perturbations at a much smaller scale using various techniques including digital breast tomosynthesis (DBT), computed tomography(CT),ultrasound, and magnetic resonance imaging(MRI).
An alternative strategy to improve early detection is to search for functional changes. In 2007, the American Cancer Society revised their breast cancer screening recommendations. Annual screening by mammography is still recommended for women at low‐to‐medium risk for breast cancer; however, women at high risk for breast cancer are now recommended to have annual mammography and MRI. This recommendation is supported by studies which show that MRI is capable of demonstrating mammographically‐occult breast cancer both in both screening and diagnostic populations.
Contrast‐enhanced (CE) radiographic methods, including CE‐mammography, CE‐DBT and CE‐CT, have the potential to rival breast MRI as a sensitive method for diagnosis and screening of breast cancer. In a pilot study of CE‐DBT conducted at the University of Pennsylvania, suspicious enhancing lesions were demonstrated in 14 of 15 cases of breast cancer. The pre‐contrast tomosynthesisimages demonstrated lesion morphology and border characteristics in greater detail than digital mammography, while the subtracted contrast‐enhanced tomosynthesisimages demonstrated the vascular characteristics of the breast lesions in a manner consistent with breast MRI.
Further advances in CE imaging will be predicated upon shifting our attention from imaging perfusion to imaging specific molecular/cellular events. Research is ongoing in the discovery of specific biological prognostic factors, the development of appropriate imaging technologies and imaging agents, and the adaptation of these technologies to image‐guidance and monitoring of therapeutic interventions.
1. Review the development of contrast‐enhanced breast imaging.
2. Evaluate the results of the existing contrast‐enhanced clinical trials.
3. Examine the clinical roles for contrast‐enhanced imaging.
35(2008); http://dx.doi.org/10.1118/1.2962604View Description Hide Description
Dedicated breast computed tomography(CT)systems were designed and fabricated in our laboratory, and patient scanning commenced in November 2004. The breast CTscanner was designed utilizing several off‐the‐shelf components, including the x‐ray system, the flat‐panel detector, and a position encoder/bearing/motor system. These components were integrated into a custom designed scanner frame and gantry. The breast CTscanners were designed for 33 second acquisition, utilizing 500 projection images acquired over 360° around the breast. The breast CTscanner uses 80 kVp and mAs levels adjusted to the size of the woman's breast. The radiation levels are adjusted such that the mean glandular dose is equal to that of two‐view mammography for each woman. The acquisition protocols requires patient breath hold during the 17 second scan. As of May 2008, 150 patients have been scanned, including healthy volunteers (phase 1) and BIRADS 4 and 5 patients who were suspicious for having breast cancer (phase 2). Of the patients imaged, >20 were imaged with and without contrast agent injection. While our clinical evaluation of breast CT technology is still under way, initial evaluation indicates that high‐quality tomographic images of the breast can be achieved at dose levels comparable to two view mammography. The ultimate utility of breast CT may include breast cancer screening, or for diagnostic studies as part of a comprehensive diagnostic breast examination. The breast CT platform also appears ideal for robotically controlled biopsy and other interventional procedures.
- Advances in Cardiovascular Imaging
35(2008); http://dx.doi.org/10.1118/1.2962554View Description Hide Description
Minimally invasive cardiac procedures using endovascular access have enabled treatment of patients that previously would have required open‐heart surgery. Such procedures are typically carried out in the interventional suite, with x‐ray fluoroscopy used to guide the placement of a catheter, followed by a phase of the procedure in which x‐ray fluoroscopy provides little to no information on the treatment. C‐arm CT has been under development since the early 90's, but has now entered a new phase as the ability to visualize soft tissue and low‐contrast lesions improves. By generating 3D images utilizing the x‐ray system in the interventional suite, the error prone and time‐consuming spatio‐temporal registration with prior CT or MRI exams can be avoided. However, C‐arm CTimaging in the presence of cardiac motion remains a challenge due to the slow rotation speed of the gantry, and the slow readout rates of the flat‐panel detectors. Three main data acquisition approaches to circumvent these limitations will be discussed: multi‐sweep retrospective ECG gating for myocardial visualization, single‐ or double‐sweep with volume image fusion for left atrium and pulmonary vein visualization and single‐sweep with retrospective gating for coronary artery visualization. Approaches to improve image quality, both hardware and software, such as optimized acquisition timing, motion compensation approaches and algorithms for non‐idealities such as x‐ray scatter, detector lag, limited field‐of‐view or angular coverage, data insufficiency and noise will be presented. With these developments the ultimate goal is to accomplish faster and more accurate catheter based interventions with an equivalent success rate as surgical procedures (80–90%). The C‐arm CT technology described here could eventually impact many minimally invasive procedures such as RF ablation for atrial fibrillation and coronary stenting, and also future procedures as they become available, such as endocardial injection of stem cells for treatment of myocardial infarction.
1. Learn how 3D cardiac imaging is done in the interventional suite: acquisition protocols, injection protocols, challenges and solutions.
2. Learn how image quality of 3D cardiac images can be improved using hardware and algorithm approaches.
35(2008); http://dx.doi.org/10.1118/1.2962555View Description Hide Description
Dual‐energy CT can be expected to play a new and evolving role in cardiovascular imaging. Clinical uses already reported include 1) direct CTangiography, whereby the dual energy algorithm identifies and removes bone in a 3‐D CT angiographic data set, allowing direct visualization of iodinated vessels without the need for user intervention to remove overlying bony anatomy, 2) removal of smaller hard plaques within vessels, allowing more rapid and clearer visualization of patent lumens in MIP projections, and 3) visualization of the perfused blood volume, also referred to as blood pool imaging, to demonstrate focal perfusion deficits. Dual energy bone and plaque removal techniques can be applied in retrospectively‐gated cardiacimaging, suppressing the appearance of calcified plaque and providing improved visualization of stenotic lumens. Additionally, dual‐energy CT can be used to identify and remove calcified plaque prior to image reconstruction in order to reduce the effects of calcium blooming, which creates artifactual elevation of CT numbers in voxels adjacent to calcified objects, often obscuring the dimensions of the true lumen for large or dense coronary artery calcifications. Finally, using projection‐space dual‐energy methods, mono‐energetic CTimages can be calculated, which greatly reduces beam hardening effects and increases the accuracy of CT number measurements. The use of dual‐energy CT techniques is being explored for the evaluation of myocardial perfusion deficits.
Attendees of this presentation can expect to learn about:
1) the technical approaches to dual‐energy cardiacCT currently implemented or under investigation on commercial CT systems,
2) current clinical uses of dual‐energy CT in cardiovascular imaging and
3) areas of future investigation.
35(2008); http://dx.doi.org/10.1118/1.2962556View Description Hide Description
Coronary arteriography is the standard method for determination of coronary anatomy and assessment of atherosclerosis. However, there are definite limitations to the use of visual estimation to assess the severity of coronary artery disease and luminal stenosis. These limitations include the large intraobserver and interobserver variability that result from subjective visual grading of coronary stenotic lesions. This is especially true in the case of an intermediate coronary lesion (30%–70% diameter stenosis), where coronary arteriography is very limited in distinguishing ischemia‐producing intermediate coronary lesions from non‐ischemia‐producing ones. Furthermore, pathologic findings have shown a lack of correlation between the severity of coronary stenosis as estimated from coronary arteriogram and the actual severity of stenotic lesions measured in postmortem hearts. Because of the major limitations of standard coronary arteriography, a method for functional measure of stenosis severity such as measurement of fractional flow reserve obtainable during cardiac catheterization is desirable. The fractional flow reserve measurement would provide valuable functional information in addition to the anatomical data obtained during routine coronary arteriography.
Fractional flow reserve was introduced to provide a physiological measure of coronary stenosis by quantifying the reduction in maximum coronary blood flow from a theoretical maximum normal flow in the presence of a lesion. Currently, fractional flow reserve is approximated by dividing the pressure distal to the stenosis by the aortic pressure. The distal pressure is measured using a pressure‐sensing wire that has passed across the stenosis, and the aortic pressure is measured simultaneously at the catheter tip with a pressure transducer. Pressure‐based fractional flow reserve has proven to aid the evaluation of the flow‐limiting potential of stenoses as well as the therapeutic gain of angioplasties. However, an alternative technique that can measure fractional flow reserve using only angiographic images would be a valuable tool in the cardiac catheterization laboratory because the acquired images used for visual assessment of stenosis severity can also be used to quantify physiological alterations imposed by the stenosis. In other words, fractional flow reserve could potentially be measured using only image data without the need to pass a pressure wire across a stenosis. The blood flow through the stenotic lesion is measured with a first pass distribution analysis technique and the theoretical normal blood flow is estimated by using a measurable parameter that correlates well with it. Scaling law relationships indicate that the total coronary arterial volume can be used as a surrogate measure of normal blood flow. The details of the methodology for fractional flow reserve quantification using angiographic image data will be discussed.
This lecture will provide an overview of the emerging techniques for assessment of the physiological significance of coronary lesions measured in the cardiac catheterization laboratory.
1. Understand the current techniques available for measurement of fractional flow reserve in the cardiac catheterization laboratory.
2. Understand the methodology for coronary blood flow measurement using angiographic image data.
3. Understand the methodology for fractional flow reserve measurement using angiographic image data.
35(2008); http://dx.doi.org/10.1118/1.2962557View Description Hide Description
In a recent Medical Physics “Vision 2020” paper (Medical Physics 35(1): 301–309, Jan 2008), the authors reviewed the state of endovascular image‐guided interventions (EIGI) and offered some predictions for the future. Here we review the current status of the field and of some of these advances. First, endovascular devices (such as clot busting tools, stents and their catheter delivery systems, and blood flow modifiers) are becoming finer, more complex, and are enabling the replacement of invasive surgical procedures with minimally invasive EIGI procedures. Innovative methods of actuating motion at the catheter tip, such as the use of external magnetic fields, are being introduced. Second, along with improvements in devices,imagingsystems that provide real‐time high‐resolution image guidance are being developed including a Solid State X‐ray Image Intensifier based on electron multiplying charge coupled devices (EMCCDs) that provide large on‐chip gain to overcome instrumentation noise such as that characteristic of current flat panel detectors. SSXIIs also have very high resolution capable of exceeding 10 lp/mm yet with no lag or ghosting. Third, the new high‐resolution region‐of‐interest (ROI) detectors can be used in combination with large conventional detectors for dual‐detector cone‐beam computer tomography (CB‐CT) to visualize ROIs within larger objects yet with minimal truncation artifact and with reduced integral dose. Fourth, during an interventional procedure, limited projection views can be taken to generate full 3D representations of the vasculature with accurate determination of vessel lumen morphology to enable computer fluid dynamic (CFD) calculations which in turn can be used to plan further EIGI treatment within the patient treatment time. Finally, as EIGI procedures become more complex, the consequent patient dose especially where improved image quality is implemented must be more carefully monitored. For example, we found that patient dose actually increased for certain electro‐physiology (EP) procedures performed in our EP Lab following replacement of a mobile c‐arm with a fixed unit capable of generating improved image quality. In conclusion, while progress is being made toward fulfilling the predictions made by the authors in the Vision 2020 paper published early in 2008, EIGI remains open to continuing exciting advancements.
1. Appreciate the progress being made in improved EIGI devices and imagingsystems.
2. Understand the operation of new high‐resolution micro‐angiographic systems including the SSXII and the operation of dual‐detector ROI CB‐CT systems.
3. Understand the role of limited view acquisition for providing 3D images.
4. Appreciate the patient exposure burden during EIGI procedures.
[Supported in part by NIH Grants R01 EB002873, R01 NS43924, R01 EB00842501, R01 HL52567, UB Foundation IRDF, and an equipment grant from Toshiba Medical Systems Corp.].
- Advances in X‐ray Imaging
35(2008); http://dx.doi.org/10.1118/1.2962725View Description Hide Description
In the last two decades, there have been rapid advances in projection x‐ray imaging in the areas of x‐ray detector and infrastructures for image management, processing and display. Following the development and commercialization of flat panel detectors, there have also been rapid advances in using the large area detectors to implement reconstructive 3‐D imaging techniques, including the cone beam CT and digital tomosynthesisimaging techniques. In contrast to these advances, the issues of x‐ray scatter and heavy patient attenuation remain the two biggest challenges in our effort to improve the image quality while keeping the patient dose in check. The presence of the x‐ray scatter component in the image signals biases the transmitted x‐ray intensity and results in erroneous x‐ray attenuation measurements which degrades the image quality and prevents accurate quantitative analysis in both projection and reconstructed images. Heavy patient attenuation could result in excessively low photon flux in certain anatomical regions, such as abdomen or retrocardium. This can combine with the lowered detective quantum efficiencies (DQEs) to lead to excessively low and unusable image signal‐to‐noise ratios (SNRs) Along with these two long standing issues is the long awaiting wish to develop a “weightless” x‐ray source that can be digitally controlled to shift without having to move a bulky and heavy housing. The development of a CT or digital tomosynthesisimaging system with no moving parts has become the holy grail of x‐ray imaging research. In this paper, efforts to address the scatter and exposure issues and to develop a “weightless” x‐ray source in the past two decades are reviewed with an educated guess on where we might head to in the future.
1. To review the issues of and solutions to the scatter problem in x‐ray image acquisition.
2. To review the issues of and solutions to the problem of excessive patient attenuation.
3. To review the efforts and potential use of digitally addressable “weightless” x‐ray source
WE‐C‐342‐02: The Future of Flat Panel Imagers: From Active Matrix to Active Pixel Architectures and Many Possibilities in Between35(2008); http://dx.doi.org/10.1118/1.2962726View Description Hide Description
Since the turn of the century, the phrase “Flat Panel Imager” has been increasingly used in modern x‐ray imaging venues ranging from large, institutional cardiac care, radiology and radiotherapy settings to community oral surgery offices. The phrase most commonly refers to those technologies employing a large area, monolithic array consisting of a two‐dimensional grid of imaging pixels fabricated on a thin glass substrate. Individual pixels are made addressable by means of an “active matrix” of switches — usually, in each pixel, taking the form of a single amorphous silicon (a‐Si:H) thin film transistor(TFT) coupled to some form of storage capacitor. Two variations of this relatively simple architecture (based on so‐called indirect or direct detection of the incident radiation by means of a scintillator or a photoconductor, respectively) have become almost ubiquitous for a wide variety of projection (e.g. radiography, fluoroscopy, mammography) and volumetric (e.g., CBCT, tomosynthesis) imaging applications. While offering many advantages, such Active Matrix Flat Panel Imagers (AMFPIs) are restrictive in terms of signal‐to‐noise performance, maximum frame rate, image artifacts, configurability and cost. These limitations are inspiring considerable innovation and creativity in imager development. Some approaches involve: high‐gain photoconductors such as HgI2 or avalanche‐gain with a‐Se (to improve system gain and DQE); active pixel circuits involving the inclusion of amplifiers in each pixel (to increase gain and DQE, frame rate, and to reduce artifacts); thick segmented scintillating converters (to increase x‐ray quantum detection efficiency and DQE at megavoltage energies); flexible substrates (to provide lighter, flexible and more x‐ray transparent substrates); and subtractive and additive printing of a‐Si:H or organic TFTs (to reduce costs). In this talk, a broad overview of the state of conventional AMFPI technology, its limitations, the potential for improvement, and some of the avenues being pursued to achieve these improvements will be presented. In addition, challenges for some of these approaches, along with the long‐term prospects for this general area of technology, will be reviewed, and the effect of large performance improvements on the practical implementation of advanced applications will be discussed.
1. Review the fundamental concepts behind the technology of flat panel imagers based on active matrix addressing.
2. Provide an understanding of the performance limitations on such active matrix, flat panel imagers (AMFPIs).
3. Outline the general approaches for achieving significant improvements over conventional AMFPI performance.
4. Detail specific improvement strategies involving front‐end enhancement of converter signal and pixel level circuit modifications, which preserve the major advantages of conventional AMFPIs.
5. Discuss the long‐term prospects for, and implications of flat panel imager performance improvement.
35(2008); http://dx.doi.org/10.1118/1.2962727View Description Hide Description
Two major x‐ray‐based techniques used for medical imaging are digital radiography (DR) and computed tomography(CT). Most of their detectors integrate the intensity of x‐ray flux and output gray scale images or projections. Detectors with indirect detection type heavily weigh x‐ray photons with higher energy as they generate more lights. This results in suboptimal contrast of images because the contrast of different tissues reduces in general as the energy of photons increases. In the past few years, there have been strong reviving research interests in an old concept—the use of the photon energy—to improve the quality and accuracy of diagnosis.
Recently, novel photon counting x‐ray detectors (PCXDs) with energy discrimination capabilities have been developed for x‐ray DR and CTimaging. These PCXDs counts the number of x‐ray photons within multiple energy windows. This allows us to improve the quality of the current gray scale images and the accuracy of the material decomposition. We will discuss the state‐of‐the‐art detector technologies and imaging methods unique to these PCXDs.
- Current and Future Research Trends in Nuclear Medicine
35(2008); http://dx.doi.org/10.1118/1.2962407View Description Hide Description
Nuclear Medicine instrumentation continues to progress, both hardware and software. Advances in PET/CT include increased PET sensitivity, respiratory gating, time of flightmeasurement, and improved image reconstruction algorithms that encorporate more physical effects into the acquisition model. Gamma cameras are incorporating new detector materials, and SPECT is being done with new acquisition geometries and reconstructed with new algorithms.
We will discuss new developments in nuclear medicine instrumentation, including ones that are currently available commercially and ones that are on the horizon.
1. Understand three new developments in PET that have the potential to improve image quality.
2. Understand how new detector materials allow new acquisition geometries for SPECT.
3. Understand how physic effects in the acquisition process can be modeled in the image reconstruction process.
Research sponsored by GE Healthcare.
35(2008); http://dx.doi.org/10.1118/1.2962408View Description Hide Description
The quantification of function and activity plays an important role clinically in nuclear medicine. Examples include the analysis of tracer kinetics to quantify dynamic function, the determination of the fraction of the cardiac blood pool ejected during contraction, the comparison of regional localization of uptake within the heart to that of a database to facilitate the recognition of perfusion defects in cardiacimaging, and the localization of F‐18 labeled FDG in potential lesions. Despite the present clinical utility of quantification a number of factors limit current methods. The successful addressing of these factors would expand the clinical utility of quantification and are the subject current and future investigations.
This lecture will provide an introduction to the application of quantification within nuclear medicine. It will point out some current deficiencies, and potential research directions aimed at over coming them.
1. Understand the various types of quantification employed in nuclear medicine.
2. Recognize some of the limitations to robust application of quantification clinically.
3. Appreciate some of the proposed methods to overcome these limitations.
35(2008); http://dx.doi.org/10.1118/1.2962409View Description Hide Description
Advances in our understanding of the molecular biology of cancer and other diseases have identified molecules and signaling pathways that we can now visualize, in vivo, for diagnosis, staging, and to identify optimal therapy and monitor patient response to therapy. These advances have also helped identify targets for targeted radionuclide therapy, making it possible to target radiation at the cellular and molecular level. Planning for this treatment approach is similar, in principle, to external beam radiotherapytreatment planning, but substantially different in practice. Dosimetry for systemic or locoregional administration of a therapeuticradiopharmaceutical requires an understanding of its biodistribution and pharmacokinetics, this must be coupled with a methodology for translating total number of radionuclide disintegration in a particular anatomical volume to the absorbed dose to the volume. Advances in imaging and computing technology over the past 20 to 30 years have fostered corresponding advances in the implementation of the basic radionuclide dosimetry scheme outlined above. Dosimetry in nuclear medicine is evolving from a standard anatomical model‐based calculation that provides mean absorbed dose over a target organ volume to a calculation that provides the spatial distribution of absorbed dose over the individual patient target and organ geometry and that also incorporates radiobiological modeling as a step towards assessing the biological consequences of the dose distribution. The evolution of nuclear medicinedosimetry as well as recently approved and emerging radionuclide‐based therapeutics will be reviewed.
- Image Display, Processing and Analysis (CAD)
35(2008); http://dx.doi.org/10.1118/1.2962877View Description Hide Description
Medical imaging is rapidly expanding in the manner in which images are acquired and thus the manner in which they are displayed has also become a very important issue. The presentations in this session will discuss some of the issues associated with three important links in the imaging chain with respect to the display of radiographicimages:Image Display, Processing and Analysis(CAD). In each area the key to success is to develop ways to present image data to the human observer in the most efficient and informative manner, taking into account the perceptual and cognitive capabilities of the human observer. The ultimate goal is to facilitate the decision‐making process and enhance patient care — improving the radiologist's ability to render correct diagnoses with a minimum of errors. Another important consideration is how Image Display, Processing and Analysis(CAD) tools affect workflow. Radiologists are being faced with an ever increasing number of images to interpret overall and within a given case. To the extent possible, these tools should make the interpretation process more efficient rather than prolong the process.
The three presentations will focus on the state‐of‐the‐art in Image Display, Processing and Analysis(CAD). Specific imaging applications will be discussed, but the underlying principles extend to medical imaging applications in general.
1. Understand the role of the display in the interpretation process and why optimization is important.
2. Understand how image processing or the rendering of image data in new ways can improve the radiologists' interpretation process.
3. Understand the basic nature of CAD and the various ways it is being used (e.g., detection and discrimination) to improve diagnostic accuracy of radiologists.
35(2008); http://dx.doi.org/10.1118/1.2962878View Description Hide Description
TH‐C‐342‐03: Quantitative Medical Image Analysis for Early Detection, Diagnosis, Outcome Prediction, and Treatment35(2008); http://dx.doi.org/10.1118/1.2962879View Description Hide Description
Medical imaging and image analysis has revolutionized the patient care as well as many research activities in biology and healthcare. Stet‐of‐the‐art methods and approaches for medical image segmentation, quantitative analysis, and their use for computer‐aided diagnosis and disease progression prediction will be the main target of this presentation. Special focus will be given to several high‐complexity projects in the areas of coronary image analysis via fusion of intravascular ultrasound and angiography, coronary plaque analysis, plaque progression prediction, cardiovascular risk factor assessment via analysis of carotid and brachial ultrasoundimages, pulmonary CTimage analysis, computer‐aided diagnosis of congenital aortic disease, cartilage MR image analysis, and liver surgery planning. The talk will be accompanied by live demonstrations of the software tools developed for the above‐referenced purposes.
35(2008); http://dx.doi.org/10.1118/1.2962880View Description Hide Description
Computer‐aided diagnosis(CAD) has been developed over the last few decades as a tool to improve diagnostic performance. Computer‐aided detection (CADe) promises to help radiologists detect some of the subtle cancers that radiologists tend to miss. After CADe systems are introduced into clinical practice, many clinical studies have been conducted to assess the clinical effect of CADe. Like laboratory observer studies, many of these clinical studies show that CADe helps radiologists detect more cancers. However, all clinical studies do not agree. Controversies have recently arisen that question whether CADe helps radiologists detect more cancers or does more harm by increasing the number of false positives. While laboratory observer studies are very good at controlling biases, potential biases in clinical studies are far less understood and could fundamentally influence the clinical evaluation of CADe. In this presentation, we will review the concept of CAD and summarize laboratory and clinical studies of CADe. We will discuss the pros and cons of various types of clinical studies and discuss their limitations. We will identify some pitfalls that must be overcome to determine the true clinical effect of CAD.
1. Understand the basic concept of CAD.
2. Understand the common types of laboratory and clinical studies of CADe.
3. Understand the limitations of current clinical studies.
Conflict of Interest Statement: Y Jiang receives research funding from Hologic (Bedford, MA).
- Innovations in CT
35(2008); http://dx.doi.org/10.1118/1.2962939View Description Hide Description
The introduction of helical/spiral CT nearly 20 years ago enables, for the first time in CT history, the coverage of an entire human organ in a single breath‐hold. It offers a more uniform sampling along the patient long axis and allows clinicians to follow the contrast uptake in an organ. Nearly ten years later, the introduction of multi‐slice CT offers a truly isotropic spatial resolution any time and anywhere. Operator is no longer forced to make a choice between coverage and spatial resolution along the z‐axis. Its debut has changed the way radiologists scan patients and visualize images. With a significantly improved coverage, CTimaging has moved beyond the three‐dimensional spatial domain and included the fourth dimension of temporal domain.
Multi‐slice helical/spiral CT also found its way into the cross‐modality imaging devices such as PET/CT or SPECT/CT. CT has become such an integral part of these devices that nearly all of the PET scanners built today include CT. These advancements inspired many new clinical applications such as cardiacimaging, perfusion, and more recently dual energy acquisitions. If the past ten years of CT history can be characterized by the “slice war”, new technological advancements nowadays are no longer constrained to the simple slice count. Many new frontiers, such as functional or physiological imaging, are now appearing on the horizon and are actively pursued by researcher around the world.
In this talk, we will briefly review technological advances, technical challenges, and clinical impact associated with the helical/spiral scanning, multi‐slice CT, and PET/CT. We will discuss recent advances in the areas of cardiacimaging, dual energy imaging, 4DCT, and perfusion. We will conclude with a futuristic look at the CT.
35(2008); http://dx.doi.org/10.1118/1.2962940View Description Hide Description
Physicians from nearly every medical specialty rely on CT for its ability to rapidly and reliably define anatomic morphology. The tremendous advances in CT technology over the past decade have allowed many new techniques to move into mainstream clinical use. CardiacCT,CTangiography,CT enterography and CT colonography have, in many cases, become accepted replacements for invasive alternatives such as catheter angiography or endoscopy. The use of 3‐ or 4‐D image displays allows a more intuitive demonstration of imaging findings to the referring physician and the patient, resulting in more than 100% growth per year in the numbers of exams using these techniques. The use of 4D CT joint kinematics may allow for the assessment of orthopedic motion abnormalities, just as 4D cardiacimaging allows for the assessment of cardiac motion abnormalities. New interventional CT procedures allow for outpatient spine fracture stabilization, tumor ablation, and complicated biopsies. CT perfusion exams in oncology patients may allow assessment of the therapeutic effect of anti‐angiogenic drugs. And, material composition information is becoming available with the reintroduction of dual‐energy CT. Dual energy CT has been shown to provide > 93% accuracy for the identification of uric acid kidney stones; to be able to differentiate gout from calcium pyrophosphate dihydrate deposits; to facilitate rapid bone removal from CTangiographydata sets; and to be able to remove iodine from contrast‐enhanced data sets. Clinical adoption of these and other dual‐energy applications is anticipated to increase as more commercial dual‐energy CT products are brought to the marketplace. In spite of these and other advances in CT capabilities, the pressure to keep patient dose as low as possible (consistent with the imaging task) remains. Dose management strategies are thus a necessary consideration for the development and clinical implementation of any new CTimaging capability. The participant will learn about these and other new CT clinical applications.