The Future of Cardiovascular Computed Tomography: Advanced Analytics and Clinical Insights.

Cardiovascular computed tomography (CCT) has undergone rapid maturation over the last decade and is now of proven clinical utility in the diagnosis and management of coronary artery disease, in guiding structural heart disease intervention, and in the diagnosis and treatment of congenital heart disease. The next decade will undoubtedly witness further advances in hardware and advanced analytics that will potentially see an increasingly core role for CCT at the center of clinical cardiovascular practice. In coronary artery disease assessment this may be via improved hemodynamic adjudication, and shear stress analysis using computational flow dynamics, more accurate and robust plaque characterization with spectral or photon-counting CT, or advanced quantification of CT data via artificial intelligence, machine learning, and radiomics. In structural heart disease, CCT is already pivotal to procedural planning with adjudication of gradients before and following intervention, whereas in congenital heart disease CCT is already used to support clinical decision making from neonates to adults, often with minimal radiation dose. In both these areas the role of computational flow dynamics, advanced tissue printing, and image modelling has the potential to revolutionize the way these complex conditions are managed, and CCT is likely to become an increasingly critical enabler across the whole advancing field of cardiovascular medicine.

Advances in osteoporosis from 1970 to 2018.

In 1970, there were no drugs under study for osteoporosis. Estrogen was used, but little was known about the correct dose for preventing bone loss. At that time, fractures were not even recognized as a disease, but regarded as part of normal aging. From 1970 to this year (2018), there have been extensive advances in the osteoporosis field ranging from fracture epidemiology to the remarkable invention of bone density measurements. There have been major advances in therapeutic options available for patients for prevention and treatment of osteoporosis. In parallel, the advances in the laboratory helped elucidate the process of bone remodeling, not only at the macroscopic level but also at the cellular level. This led to rapid advances in translational research from cellular biology to new therapies exemplified by the development of monoclonal antibodies for osteoporosis. Further understanding of the signaling pathways in bone cells will lead to new small molecules made for osteoporosis treatment, perhaps causing less adverse events. University-based research throughout the world has been a leader in most of these advances, and Pharma support for phase 1 to 4 studies helped bring these discoveries to patients. In the osteoporosis field alone, one sees the tremendous value of grant support for university research by National funding agencies such as the National Institute of Health in this country and similar agencies in other countries. There are clinical challenges that have to be solved with long-term compliance with osteoporosis medication if we want to reduce fracture incidence in the long term.

Current and future diagnostic tools for traumatic brain injury: CT, conventional MRI, and diffusion tensor imaging.

Brain imaging plays a key role in the assessment of traumatic brain injury. In this review, we present our perspectives on the use of computed tomography (CT), conventional magnetic resonance imaging (MRI), and newer advanced modalities such as diffusion tensor imaging. Specifically, we address assessment for immediately life-threatening intracranial lesions (noncontrast head CT), assessment of progression of intracranial lesions (noncontrast head CT), documenting intracranial abnormalities for medicolegal reasons (conventional MRI with blood-sensitive sequences), presurgical planning for post-traumatic epilepsy (high spatial resolution conventional MRI), early prognostic decision making (conventional MRI with diffusion-weighted imaging), prognostic assessment for rehabilitative planning (conventional MRI and possibly diffusion tensor imaging in the future), stratification of subjects and pharmacodynamic tracking of targeted therapies in clinical trials (specific MRI sequences or positron emission tomography (PET) ligands, e.g., diffusion tensor imaging for traumatic axonal injury). We would like to emphasize that all of these methods, especially the newer research approaches, require careful radiologic-pathologic validation for optimal interpretation. We have taken this approach in a mouse model of pericontusional traumatic axonal injury. We found that the extent of reduction in the diffusion tensor imaging parameter relative anisotropy directly correlated with the number of amyloid precursor protein (APP)-stained axonal varicosities (r(2)=0.81, p<0.0001, n=20 injured mice). Interestingly, however, the least severe contusional injuries did not result in APP-stained axonal varicosities, but did cause reduction in relative anisotropy. Clearly, both the imaging assessments and the pathologic assessments will require iterative refinement.

The impact of computed tomography slice thickness on the assessment of stereotactic, 3D conformal and intensity-modulated radiotherapy of brain tumors

PURPOSE: To evaluate radiotherapy treatment planning accuracy by varying computed tomography (CT) slice thickness and tumor size. METHODS: CT datasets from patients with primary brain disease and metastatic brain disease were selected. Tumor volumes ranging from about 2.5 to 100 cc and CT scan at different slice thicknesses (1, 2, 4, 6 and 10 mm) were used to perform treatment planning (1-, 2-, 4-, 6- and 10-CT, respectively). For any slice thickness, a conformity index (CI) referring to 100, 98, 95 and 90 % isodoses and tumor size was computed. All the CI and volumes obtained were compared to evaluate the impact of CT slice thickness on treatment plans. RESULTS: The smallest volumes reduce significantly if defined on 1-CT with respect to 4- and 6-CT, while the CT slice thickness does not affect target definition for the largest volumes. The mean CI for all the considered isodoses and CT slice thickness shows no statistical differences when 1-CT is compared to 2-CT. Comparing the mean CI of 1- with 4-CT and 1- with 6-CT, statistical differences appear only for the smallest volumes with respect to 100, 98 and 95 % isodoses-the CI for 90 % isodose being not statistically significant for all the considered PTVs. CONCLUSIONS: The accuracy of radiotherapy tumor volume definition depends on CT slice thickness. To achieve a better tumor definition and dose coverage, 1- and 2-CT would be suitable for small targets, while 4- and 6-CT are suitable for the other volumes (AU)

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Important advances in technology and unique applications to cardiovascular computed tomography.

For the past decade, multidetector cardiac computed tomography and its main application, coronary computed tomography angiography, have been established as a noninvasive technique for anatomical assessment of coronary arteries. This new era of coronary artery evaluation by coronary computed tomography angiography has arisen from the rapid advancement in computed tomography technology, which has led to massive diagnostic and prognostic clinical studies in various patient populations. This article gives a brief overview of current multidetector cardiac computed tomography systems, developing cardiac computed tomography technologies in both hardware and software fields, innovative radiation exposure reduction measures, multidetector cardiac computed tomography functional studies, and their newer clinical applications beyond coronary computed tomography angiography.

Clinical research in individual information of celiac artery CT imaging and gastric cancer surgery

OBJECTIVE: The objective of this study is to acquire CT images of the celiac artery by 64-multi-slice spiral CT angiography (64-MSCTA) in gastric cancer patients to facilitate gastric cancer surgery. METHODS: Preoperative 64-MSCTA was performed to observe the origin, course and anatomical variations of the celiac artery and vascular calcifications in 102 gastric cancer patients. RESULTS: (1) The celiac trunk mostly arose at the level between the 12th thoracic vertebra and the 1st lumbar vertebra; the mean inferior angle with the abdominal aorta was 63.5° (14°-159°), the mean length was 36.29 mm (5.80-73.58 mm), and its course showed many styles. (2) Of 102 gastric cancer patients, 34 patients (33.33 %) were observed with celiac artery variations of whom there were 27 patients with anatomical variations of the hepatic artery, 3 patients with anatomical variation of the left gastric artery and 1 patient with anatomical variation of the splenic artery; in 1 patient, the celiac trunk and the superior mesenteric artery originated from a common trunk. In other cases, it was observed with another variation. (3) The abdominal aortic calcified plaque was observed in 48 patients (47.1 %), and among them, 34 patients were more than 60 years old, and the existence of the abdominal aortic calcified plaque was related to age, significantly (P < 0.01). CONCLUSIONS: The 64-MSCTA largely improves our understanding of the origin, course and anatomical variations of the celiac artery and vascular calcifications in individual patient with gastric cancer. It is recommended that the 64-MSCTA of the celiac artery should be classified as a routine preoperative procedure in gastric cancer patients (AU)

CT dose reduction applications: available tools on the latest generation of CT scanners.

Increasing concerns about radiation dose have led CT manufacturers to further develop radiation dose reduction tools in the latest generation of CT scanners. These tools include automated tube current modulation, automated tube potential selection, and iterative reconstruction. This review details the principles underlying each of these 3 dose reduction utilities and their different permutations on each of the major vendors' equipment. If available on the user's equipment, all 3 of these tools should be used in conjunction to enable maximum radiation dose savings.

Achieving routine submillisievert CT scanning: report from the summit on management of radiation dose in CT.

This Special Report presents the consensus of the Summit on Management of Radiation Dose in Computed Tomography (CT) (held in February 2011), which brought together participants from academia, clinical practice, industry, and regulatory and funding agencies to identify the steps required to reduce the effective dose from routine CT examinations to less than 1 mSv. The most promising technologies and methods discussed at the summit include innovations and developments in x-ray sources; detectors; and image reconstruction, noise reduction, and postprocessing algorithms. Access to raw projection data and standard data sets for algorithm validation and optimization is a clear need, as is the need for new, clinically relevant metrics of image quality and diagnostic performance. Current commercially available techniques such as automatic exposure control, optimization of tube potential, beam-shaping filters, and dynamic z-axis collimators are important, and education to successfully implement these methods routinely is critically needed. Other methods that are just becoming widely available, such as iterative reconstruction, noise reduction, and postprocessing algorithms, will also have an important role. Together, these existing techniques can reduce dose by a factor of two to four. Technical advances that show considerable promise for additional dose reduction but are several years or more from commercial availability include compressed sensing, volume of interest and interior tomography techniques, and photon-counting detectors. This report offers a strategic roadmap for the CT user and research and manufacturer communities toward routinely achieving effective doses of less than 1 mSv, which is well below the average annual dose from naturally occurring sources of radiation.

PET/CT today and tomorrow in veterinary cancer diagnosis and monitoring: fundamentals, early results and future perspectives.

Functional imaging using positron emission tomography (PET) plays an important role in the diagnosis, staging, image-guided treatment planning and monitoring of malignant diseases. PET imaging complements conventional anatomical imaging such as computed tomography (CT) and magnetic resonance imaging (MRI). The strength of CT scanning lies in its high spatial resolution, allowing for anatomical characterization of disease. PET imaging, however, moves beyond anatomy and characterizes tissue based on functions such as metabolic rate. Combined PET/CT scanners were introduced commercially in 2001 and a number of technological advancements have since occurred. Radiolabelled tracers such as (18)F-fluorodeoxyglucose (FDG) and (18)F-fluorothymidine (FLT) allow visualization of various metabolic processes within cancer cells. Many studies in human oncology evaluating the utility of PET/CT have demonstrated clinical benefits. Few veterinary studies have been performed, but initial studies show promise for improved detection of malignancy, more thorough staging of canine cancer and determination of early response and disease recrudescence.

Spontaneous dissection of left anterior descending coronary artery: the diagnostic role of dual-source computed tomography.

Spontaneous coronary artery dissection is usually diagnosed by an urgent coronary angiography. We report a case of spontaneous coronary artery dissection of the left anterior descending coronary artery, which was diagnosed by dual-source computed tomography. Subsequent coronary angiography confirmed the result. Computed tomographic coronary angiography can be a complementary diagnostic tool for the assessment of coronary artery dissection.

Correlation of right ventricular dysfunction parameters and pulmonary vascular obstruction score in acute pulmonary embolism in a porcine model.

This paper aims to non-invasively determine right ventricular dysfunction parameters (RVDP) in acute pulmonary embolism (APE) and to correlate these parameters with a computed tomography (CT)-based pulmonary artery obstruction score (OS). In seven domestic pigs, magnetic resonance imaging (MRI) was performed before (n = 7) and after (n = 5) APE was induced. Analysis of relative changes in right ventricular stroke volume (RVSV%), output (RVO%), end-systolic (RVESV%), end-diastolic volume (RVEDV%), and heart rate (HR%) was performed. Additionally, for the determination of the OS, all animals underwent contrast-enhanced CT-pulmonary angiography. The CT-based OS correlated strongly with RVSV% (r = 0.9576; p = 0.0104) and RVO% (r = 0.9703; p = 0.0061). Contrarily, almost no correlation could be demonstrated for the OS and the increase of RVESV % (r = 0.3850; p = 0.5222), RVEDV% (r = 0.1830; p = 0.7683), and HR% (r = 0.5494; p = 0.3375). The results of this experimental study underline that the CT-based OS correlates with RVDP as determined by cardiac MRI and might be a helpful tool for the severity assessment in APE.

Validez diagnóstica de la TAC helicoidal frente a la ecografía en el cólico renoureteral / Diagnostic validity of helical CT compared to ultrasonography in renal-ureteral colic

OBJETIVO: La TAC helicoidal (TACh) sin contraste se evalúa como técnica diagnóstica en el cólico renoureteral. Permite un diagnóstico rápido de obstrucción ureteral y de otras patologías de sintomatología similar. Este estudio pretende evaluar la validez de la TACh frente a la ecografía en el diagnóstico de estos pacientes y plantear su inclusión, como una prueba más, en el algoritmo diagnóstico de esta patología.MÉTODOS: Estudio de evaluación de pruebas diagnósticas realizado entre enero de 2004 y diciembre de 2006 en pacientes valorados por cólico renoureteral no resuelto con atención estándar, estudiándolos de forma ciega mediante ecografía y TACh y siguiéndolos hasta confirmar el diagnóstico con un “patrón oro”. Las variables cualitativas se resumen con su distribución de frecuencias e IC95% y las cuantitativas con medidas de posición y dispersión. Se utilizó el test de χ2 para comparar variables cualitativas. Se calcularon los índices de validez diagnóstica con sus IC95% y se compararon con la prueba de McNemar.RESULTADOS: Se estudió a 124 pacientes, presentando litiasis el 59,7% y otros diagnósticos el 40,3%. Las 92 ecografías efectuadas diagnosticaron un 22,8% de litiasis frente al 59,7% obtenido con 124 TACh. Los índices de validez para la TACh fueron superiores al 95%, con una sensibilidad y valor predictivo positivo (VPP) de 100%. La ecografía presentó una especificidad y un VPP de 100% pero sensibilidad y valor predictivo negativo de 29,6% (p<0,05).CONCLUSIÓN: La TACh puede ser considerada una prueba más a utilizar en el diagnóstico del cólico renoureteral(AU)

OBJECTIVES: Helical CT without contrast is currently being evaluated for the diagnosis of renoureteral colic. Ureteral obstruction and other pathologies with similar symptoms can be rapidly identified. This study intends to evaluate the validity of CTh for these patients and to compare it with the ultrasound technique in order to consider the CTh as an efficient diagnostic alternative for these pathologies.METHODS: A diagnostic evaluation study was carried out between January 2004 and December 2006 in evapatientswith persistent renoureteral colic after standard care. They were blindly evaluated by ultrasound and CTh, maintaining the follow up until the “gold standard” confirmation. Qualitative variables were described by frequency and 95%CI and quantitative variables by position and dispersion measures. The χ2 test was used to compare qualitative variables. Validity indicators and 95% CI were calculated and compared with McNemar test.RESULTS: 124 patients were studied. Lithiasis and the other diagnosis had frequencies of 59.7% and 40.3% respectively. The percentage of lithiasis obtained by ultrasound (92) was 22.8% and by CTh (124) was 59.7%.Validity indicators for CTh were superior to 95%, with 100% sensitivity and positive predictive value. Ultrasound specificity and positive predictive value were 100%, but sensitivity was only 29.6% (p<0.05).CONCLUSION: CTh can be considered a good alternative diagnostic technique in the renoureteral colic management(AU)

C-arm cone-beam CT: general principles and technical considerations for use in interventional radiology.

Digital flat-panel detector cone-beam computed tomography (CBCT) has recently been adapted for use with C-arm systems. This configuration provides projection radiography, fluoroscopy, digital subtraction angiography, and volumetric computed tomography (CT) capabilities in a single patient setup, within the interventional suite. Such capabilities allow the interventionalist to perform intraprocedural volumetric imaging without the need for patient transportation. Proper use of this new technology requires an understanding of both its capabilities and limitations. This article provides an overview of C-arm CBCT with particular attention to trade-offs between C-arm CBCT systems and conventional multi-detector CT.

Positron emission tomography/computed tomography.

Accurate anatomical localization of functional abnormalities obtained with the use of positron emission tomography (PET) is known to be problematic. Although tracers such as (18)F-fluorodeoxyglucose ((18)F-FDG) visualize certain normal anatomical structures, the spatial resolution is generally inadequate for accurate anatomic localization of pathology. Combining PET with a high-resolution anatomical imaging modality such as computed tomography (CT) can resolve the localization issue as long as the images from the two modalities are accurately coregistered. However, software-based registration techniques have difficulty accounting for differences in patient positioning and involuntary movement of internal organs, often necessitating labor-intensive nonlinear mapping that may not converge to a satisfactory result. Acquiring both CT and PET images in the same scanner obviates the need for software registration and routinely provides accurately aligned images of anatomy and function in a single scan. A CT scanner positioned in line with a PET scanner and with a common patient couch and operating console has provided a practical solution to anatomical and functional image registration. Axial translation of the couch between the 2 modalities enables both CT and PET data to be acquired during a single imaging session. In addition, the CT images can be used to generate essentially noiseless attenuation correction factors for the PET emission data. By minimizing patient movement between the CT and PET scans and accounting for the axial separation of the two modalities, accurately registered anatomical and functional images can be obtained. Since the introduction of the first PET/CT prototype more than 6 years ago, numerous patients with cancer have been scanned on commercial PET/CT devices worldwide. The commercial designs feature multidetector spiral CT and high-performance PET components. Experience has demonstrated an increased level of accuracy and confidence in the interpretation of the combined study as compared with studies acquired separately, particularly in distinguishing pathology from normal, physiologic tracer uptake and precisely localizing abnormal foci. Combined PET/CT scanners represent an important evolution in technology that has helped to bring molecular imaging to the forefront in cancer diagnosis, staging and therapy monitoring.

Technological development and advances in single-photon emission computed tomography/computed tomography.

Single-photon emission computed tomography/computed tomography (SPECT/CT) has emerged during the past decade as a means of correlating anatomical information from CT with functional information from SPECT. The integration of SPECT and CT in a single imaging device facilitates anatomical localization of the radiopharmaceutical to differentiate physiological uptake from that associated with disease and patient-specific attenuation correction to improve the visual quality and quantitative accuracy of the SPECT image. The first clinically available SPECT/CT systems performed emission-transmission imaging using a dual-headed SPECT camera and a low-power x-ray CT subsystem. Newer SPECT/CT systems are available with high-power CT subsystems suitable for detailed anatomical diagnosis, including CT coronary angiography and coronary calcification that can be correlated with myocardial perfusion measurements. The high-performance CT capabilities also offer the potential to improve compensation of partial volume errors for more accurate quantitation of radionuclide measurement of myocardial blood flow and other physiological processes and for radiation dosimetry for radionuclide therapy. In addition, new SPECT technologies are being developed that significantly improve the detection efficiency and spatial resolution for radionuclide imaging of small organs including the heart, brain, and breast, and therefore may provide new capabilities for SPECT/CT imaging in these important clinical applications.