Traditional Imaging Techniques Research Articles

Microtomography-Based Pore Structure Modelling of Geologic Materials Used as Building and Dimension Stones

In this paper, an initial X-ray Computed Tomography study of sulphate salt degradation of two Portuguese Dimension Stones (“Semi-rijo” and “Mocacreme”) is presented, based on the Standard EN 12370 (1999). This study was performed using a high resolution X-ray Computed Tomography, a 3D X-ray microscopy non-destructive technique, in order to get representative digital information on 3D texture of the external surface and of the interior of visible light opaque objects for imaging and eventually measuring them, at resolutions in the m range. This will produce spatial quantitative information map on the density distribution of the scanned samples, usually associated to different mineral phases and voids’ textures constituting the natural materials. Both types of stones are also being investigated by the combined application of classic methods: Optical Microscopy, Scanning Electron Microscopy and Mercury Injection Porosimetry (MICP). Most of those classic studies use mainly traditional 2D imaging techniques, none of these being able to produce the 3D resolution details that X-ray micro-tomography enables. In order to achieve future better qualitative and quantitative integrated models, it will be important to combine its non destructive and 3D characteristics results with those of 3D MICP models obtained for such complex materials. This enables to qualitatively and/or quantitatively assess the evolution and decay potential of different phases and voids (pores + fissures) textures in different environmental interaction conditions. So, in order to set-up more efficient forecasts of their engineering properties behaviour in a given environment this study is an essential initial complementary step to compare and integrate in near future studies all the advantages and disadvantages of the application of these classic and new methods, based respectively upon visual examination of the samples’ exteriors and on micro-tomographic image models of the samples’ interiors and surfaces, to these geologic materials.

Role of 64-MDCT in Evaluation of Pulmonary Atresia With Ventricular Septal Defect

The purposes of this article are to describe the technical factors in performing 64-MDCT of pulmonary atresia with ventricular septal defect (PA-VSD), to describe the anatomic variations in pulmonary arterial circulation and other associated anomalies, and to describe the postoperative evaluation of this condition. The management of this complex condition has been largely determined by the morphology of pulmonary arteries and the extracardiac sources of pulmonary blood supply. Although echocardiography and catheter angiography are the traditional imaging techniques used to diagnose PA-VSD, 64-MDCT has become a valuable noninvasive imaging technique in comprehensive evaluation of this condition.

Exploitation of capacitive micromachined transducers for nonlinear ultrasound imaging

Capacitive micromachined ultrasonic transducers (CMUTs) present advantages such as wide frequency bandwidth, which could be further developed for nonlinear imaging. However, the driving electrostatic force induces a nonlinear behavior of the CMUT, thus generating undesirable harmonic components in the generated acoustic signal. Consequently, the use of CMUT for harmonic imaging (with or without contrast agents) becomes challenging. This paper suggests 2 compensation approaches, linear and nonlinear methods, to cancel unwanted nonlinear components. Furthermore, nonlinear responses from contrast agent were evaluated using CMUT in transmit before and after compensation. The results were compared with those obtained using a PZT transducer in transmit. Results showed that CMUT nonlinear behavior is highly influenced by the excitation to bias voltage ratio. Measurements of output pressure very close to the CMUT surface allow the estimation of optimal parameters for each compensation approach. Both methods showed a harmonic reduction higher than 20 dB when one element or several elements are excited. In addition, the study demonstrates that nonlinear approach seems to be more efficient because it is shown to be less sensitive to interelement variability and further avoids fundamental component deterioration. The results from contrast agent measurements showed that the responses obtained using CMUT elements in transmit with compensation were similar to those from PZT transducer excitation. This experimental study demonstrates the opportunity to use CMUT with traditional harmonic contrast imaging techniques.

A bio-inspired apposition compound eye machine vision sensor system

The Wyoming Information, Signal Processing, and Robotics Laboratory is developing a wide variety of bio-inspired vision sensors. We are interested in exploring the vision system of various insects and adapting some of their features toward the development of specialized vision sensors. We do not attempt to supplant traditional digital imaging techniques but rather develop sensor systems tailor made for the application at hand. We envision that many applications may require a hybrid approach using conventional digital imaging techniques enhanced with bio-inspired analogue sensors. In this specific project, we investigated the apposition compound eye and its characteristics commonly found in diurnal insects and certain species of arthropods. We developed and characterized an array of apposition compound eye-type sensors and tested them on an autonomous robotic vehicle. The robot exhibits the ability to follow a pre-defined target and avoid specified obstacles using a simple control algorithm.

Imaging techniques in the evaluation and management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiovascular disease, the leading cause of sudden cardiac death in young patients, and an important cause of heart failure symptoms in patients of all ages. This article reviews the role of a number of traditional and advanced imaging techniques that can now be considered in the contemporary evaluation of patients with HCM, with important implications for management strategies.

Surgical anatomy and functional connectivity of the limbic system

The goal in this study was to highlight the potential of currently available imaging techniques for surgical planning of procedures in and around the limbic system. The authors review traditional and newer imaging techniques as applied to neurosurgical planning. Today MR imaging techniques play a preponderant role. The various applications of functional techniques such as diffusion weighted, diffusion tensor, perfusion, and functional MR imaging methods are discussed. In addition to the high-resolution studies of anatomy that can be acquired, especially at higher field strengths (>or= 3 T), MR imaging now also offers the possibility of acquiring functional, metabolic, hemodynamic, and molecular information on normal and pathological brain processes. The knowledge obtained using the various imaging techniques contributes substantially to understanding the disease processes in a way that drastically improves surgical planning.

The Long Shot: Multiphoton Microscopy Offers Deeper, Sharper, Safer Imaging Than Ever Before

Abstract When living cells are far below the surface, they pose particularly complex problems for researchers trying to view dynamic life activities in the laboratory. Many fluorescence imaging systems rely on short-wavelength ultraviolet (UV) or blue light, which is then absorbed by the specimen and emitted as visible light. But living tissue scatters so much short-wavelength light that some of the emitted fluorescence from the region of interest does not reach the detector. The deeper the area of interest, the more severe this problem becomes. Indeed, for every specimen, there is a point at which so much scatter occurs that traditional fluorescence imaging techniques are no longer effective. Raising the intensity of the excitation light in order to get more light out of the system can itself be lethal for living systems, as it causes increased photobleaching and phototoxicity. Adding to the problem is the fact that in deep imaging, regions of the specimen above and below the focal plane that are not of interest are exposed to light, causing unwanted fluorescence. Finally, excessive scattering of the excitation light when imaging deep below the specimen's surface results in an image with poor signal-to-noise ratio. These images tend to look soft and dull instead of crisp and full of contrast. Assuming that the scientist's research protocol will not allow the use of thinner-cut sections, deep imaging is still possible via multiphoton microscopy.

X-ray micro-computed tomography of beech wood and biomorphic C, SiC and Al/SiC composites

The microstructures of beech wood and of beech wood-derived carbon, silicon carbide (SiC), and an aluminum/SiC composite were studied using both scanning electron microscopy (SEM) and synchrotron X-ray micro-computed tomography (µCT). As opposed to traditional two-dimensional imaging techniques, the µCT data allowed nondestructive evaluation of relatively large sample volumes. Nondestructive three-dimensional data analysis led to the observation of microstructural features, such as varying pore-wall topographies not previously seen in SEM, calculations of the volume fraction of porosity and characterization of the interconnectivity of porosity in the SiC material.

Lesions without calcium: lessons from CT angiography

Within the management of patients with known or suspected coronary artery disease (CAD), non-invasive coronary atherosclerosis imaging techniques are gradually gaining their position in addition to the more traditional functional...

Near-Infrared Spectroscopy and Cortical Responses to Speech Production

This research demonstrates near-infrared spectroscopy (NIRS) as a flexible methodology for measuring cortical activity during overt speech production while avoiding some limitations of traditional imaging technologies. Specifically, language production research has been limited in the number of participants and the types of paradigms that can be reasonably investigated using functional magnetic resonance imaging (fMRI) – where a sensitivity to motion has encouraged covert (i.e., nonvocalized) production paradigms – and positron emission tomography (PET), which allows a greater range of motion but introduces practical and ethical limitations to the populations that can be studied. Moreover, for these traditional technologies, the equipment is expensive and not portable, effectively limiting most studies to small, local samples in a relatively few labs. In contrast, NIRS is a relatively inexpensive, portable, noninvasive alternative that is robust to motion artifacts associated with overt speech production. The current study shows that NIRS data is consistent with behavioral and traditional imaging data on cortical activation associated with overt speech production. Specifically, the NIRS data show robust activation in the left temporal region and no significant change in activation in the analogous right hemisphere region in a sample of native, English-speaking adults in a picture-naming task. These findings illustrate the utility of NIRS as a valid method for tracking cortical activity and advance it as a powerful alternative when traditional imaging techniques are not a viable option for researchers investigating the neural substrates supporting speech production.

Neuroimaging in obsessive–compulsive disorder

Many neuroimaging studies have investigated the pathophysiology of obsessive–compulsive disorder. These studies have contributed greatly to the development of contemporary neurocircuitry models of obsessive–compulsive disorder, which emphasize the dysfunction of fronto–striato–thalamocortical circuitry in obsessive–compulsive disorder patients. Specifically, dysfunctions of the orbitofrontal cortex, anterior cingulate cortex, thalamus and caudate nucleus have been revealed through resting state or symptom provocation studies. In addition, dysfunctional activations in the dorsolateral prefrontal cortex and parietal regions have been reported. Recently, these findings have led to the suggestion that the pathogenesis of obsessive–compulsive disorder involves an imbalance between dorsal and ventral fronto–striatal circuits. In this review, we provide updated findings on structural and functional neuroimaging studies performed with obsessive–compulsive disorder patients. The limitations of traditional imaging techniques and recent developments to overcome them will also be discussed.

Coherent-Pulse 2D Crystallography Using a Free-Electron Laser X-Ray Source

Coherent diffractive imaging for the reconstruction of a two-dimensional (2D) finite crystal structure with a single pulse train of free-electron laser radiation at 7.97 nm wavelength is demonstrated. This measurement shows an advance on traditional coherent imaging techniques by applying it to a periodic structure. It is also significant that this approach paves the way for the imaging of the class of specimens which readily form 2D, but not three-dimensional crystals. We show that the structure is reconstructed to the detected resolution, given an adequate signal-to-noise ratio.

Imaging of Integrins as Biomarkers for Tumor Angiogenesis

The integrin family plays important roles during tumor angiogenesis, the formation of new blood vessels from pre-existing vasculature. Traditional structural and functional imaging techniques are not sufficient for early lesion detection, patient stratification, or monitoring the therapeutic efficacy against cancer. Molecular imaging, the visualization, characterization and measurement of biological processes at the molecular and cellular levels in humans and other living systems, can fulfill these goals. In this review article, we will summarize the current state-of-the-art of imaging integrin (alpha(2)beta(1), alpha(3)beta(1), alpha(4)beta(1), alpha(v)beta(3), and alpha(v)beta(6)) expression using either single molecular imaging modality (magnetic resonance imaging, ultrasound, optical, single photon emission computed tomography, and positron emission tomography) or a combination of different modalities. For clinical translation, radionuclide-based imaging will have broad potential applications in cancer patients and the currently available clinical data (exclusively on integrin alpha(v)beta(3) so far) will be discussed in detail. The design, optimization, and characterization of imaging agents targeting integrins will be presented and areas needing extensive future research effort will be discussed. In the new era of personalized medicine, fast clinical translation and incorporation of integrin imaging into anti-cancer clinical trials will be critical for the maximum benefit of cancer patients.

The value of small bowel magnetic resonance imaging in the management of enteropathy associated T‐cell lymphoma

A 50-year-old female with a 9-year history of coeliac disease, presented with an acute jejunal perforation. Resection of the distal jejunem and primary anastomosis was carried out. Histology showed a high grade T-cell lymphoma on a background of coeliac disease [Enteropathy associated T-cell lymphoma (EATCL)]. A computed tomography (CT) scan carried out postoperatively showed no lymphadenopathy or evidence of residual lymphoma mass in the abdomen or pelvis. The patient then received three cycles of CHOP (cyclophosphamide, adriamycin, oncovin and prednisolone), but remained symptomatic with abdominal pain, anorexia and diarrhoea. A CT scan of the abdomen was normal. A magnetic resonance imaging (MRI) small bowel study was then carried out, which clearly demonstrated a residual mass in the small bowel consistent with lymphoma (Fig 1A). Her treatment was escalated and she received three cycles of ESHAP (cisplatin, cytarabine, etoposide, methylprednisolone) with stem cell harvesting on recovery from the first cycle. A repeat MRI after two cycles showed resolution of the mass. Treatment was completed with a BEAM [BCNU (carmustine), etoposide, cytarabine, melphalan] conditioned autologous stem cell transplant, as has been advocated in responding patients who are able to tolerate the procedure (Lennard et al, 2002; Bishton & Haynes, 2006). A further MRI small bowel study, carried out 2 months post-transplant, was normal (Fig 1B) and she remains well after 9 months of follow up. The EATCL is an aggressive lymphoma with a poor prognosis. Traditional radiological imaging techniques, such as CT, can be insensitive at detecting this lymphoma, particularly when disease may be confined to the epithelial layer of the bowel wall and be multi-focal. Positron emission tomography techniques can be of value in imaging EATCL, but false positives do occur (Hoffmann et al, 2003; Bernstein et al, 2005). MRI offers several advantages over these techniques without exposure to radiation. It can provide cross-sectional images in multiple planes with high soft tissue contrast resolution, thus giving functional as well as anatomic information. We believe this case demonstrates an important role for MRI small bowel studies in assessing response to treatment in EATCL.

Diffusion tensor magnetic resonance imaging in spinal cord injury

AbstractNoninvasive assessment of spinal cord integrity following injury is critical for precise diagnosis, prognosis, and surgical intervention strategies. Diffusion weighted imaging and diffusion tensor imaging are more sensitive to the underlying spinal cord microstructure than traditional imaging techniques. As a result, diffusion imaging is emerging as the clinical technique for imaging the spinal cord after trauma, surgery or during progressive degenerative diseases. This review describes the basic physics of diffusion imaging using magnetic resonance, techniques used to visualize diffusion measurements, and expected changes in diffusion measurements following spinal cord injury. © 2008 Wiley Periodicals, Inc.Concepts Magn Reson Part A 32A: 219–237, 2008.

Predictors for Small Bowel Tumours in Capsule Endoscopy: Are There Any?

Capsule endoscopy (CE) has revolutionized small bowel imaging, allowing for visualization of mucosa not easily assessed by traditional imaging techniques. Small bowel tumours are infrequent and represent only 1 to 3% of all gastrointestinal malignancies. The purpose of this study was to identify any risk factors or patient characteristics that can help predict which patients are likely to have a small bowel tumours on CE. Methods : Patient characteristics and risk factors were prospectively collected on all patients prior to undergoing capsule endoscopy for obscure gastrointestinal bleeding (OGIB) at a single center over a five-year period (2002-07). Results were also noted and exact logistic regression was employed for univariate analysis and factor selection to identify predictors of patients with small bowel tumours. Patient age, gender, comorbidities, medication use (NSAIDs, Plavix, coumadin, selective-serotonin re-uptake inhibitors, and iron supplementation), and gastrointestinal complaints in addition to previous endoscopic procedures and transfusion requirements were analyzed. Results : 569 patients have undergone capsule endoscopy. In 461 patients, the primary indication was for OGIB. 29 patients were found to have small bowel tumours. Of the 431 non-tumour patients, 227 (52.7%) were men and the age was 62.2 years (+17.3) compared to the 29 patients in the tumour group comprising of 13 men (44.8%) and mean age of 61.3 years (+ 16.2) [p = 0.79 and p = 0.41, respectively). There was no other significant difference in medication use, gastrointestinal symptoms, previous endoscopic procedures or transfusion requirements. There was a significant difference in patients with a diagnosis of small bowel tumour being more likely to have previously had a colonic malignancy (10.3% vs 1.6%, p < 0.05). Patients with bright red blood per rectum were less likely to have a small bowel tumour (19.7% vs 6.9%, p = 0.09). Conclusion: There are very few clinical patient selection criteria that help identify which patients with OGIB are more likely to have a small bowel tumour versus other more benign pathology. We found that patients with a past history of colonic malignancy were significantly more likely to have a small bowel tumour while patients presenting with blood per rectum but negative endoscopic investigations were less likely to have a small bowel mitotic lesion.

Imaging of the Inferior Vena Cava with MDCT

The purpose of this pictorial essay is to illustrate the role of MDCT in the diagnosis of disease processes affecting the inferior vena cava (IVC). High-speed MDCT has the potential to replace traditional imaging techniques in the evaluation of pathologic processes involving the IVC. The ability to acquire near-isotropic data allows high-quality reconstructions in the sagittal and coronal planes and thus overcomes one of the major limitations of CT in evaluating the IVC.

Imaging of Musculoskeletal Bacterial Infections by [124I]FIAU-PET/CT

BackgroundTraditional imaging techniques for the localization and monitoring of bacterial infections, although reasonably sensitive, suffer from a lack of specificity. This is particularly true for musculoskeletal infections. Bacteria possess a thymidine kinase (TK) whose substrate specificity is distinct from that of the major human TK. The substrate specificity difference has been exploited to develop a new imaging technique that can detect the presence of viable bacteria.Methodology/Principal FindingsEight subjects with suspected musculoskeletal infections and one healthy control were studied by a combination of [124I]FIAU-positron emission tomography and CT ([124I]FIAU-PET/CT). All patients with proven musculoskeletal infections demonstrated positive [124I]FIAU-PET/CT signals in the sites of concern at two hours after radiopharmaceutical administration. No adverse reactions with FIAU were observed.Conclusions/Significance[124I]FIAU-PET/CT is a promising new method for imaging bacterial infections.

Rapid prototyping in the assessment, classification and preoperative planning of acetabular fractures

To evaluate the use of rapid prototyping in the assessment, classification and preoperative planning of acetabular fractures. The complex three-dimensional anatomy of the pelvis and acetabulum make assessment, classification and treatment of fractures of these structures notoriously difficult. Conventional imaging only provides two-dimensional images of these fractures. While interpretation of traditional imaging techniques becomes better with experience, novel techniques may assist in the understanding of these complex injuries. Twenty patients with acetabular fractures were studied. Life size three-dimensional models were manufactured from standardised CT scans, using the rapid prototyping process, selective laser sintering. Each model was presented to the operating surgeon prior to surgery. The surgeons found that the models greatly assisted in their understanding of the personality of the fracture. Three consultant orthopaedic surgeons and three senior trainees were asked to classify each fracture using conventional radiographs (AP pelvis, Judet views and CT scans) and then using the model. The kappa statistic was used to evaluate inter- and intraobserver agreement. Interobserver agreement was not absolute using either conventional radiographs or the models. For the consultants the kappa statistic using conventional radiographs was 0.61 while the kappa value using the model was 0.76 (p<0.05). For the trainees the kappa value was 0.42, using conventional radiographs and 0.71 using the model (p<0.01). Full sized models of acetabular fractures greatly assisted surgeons understand the personality of complex fractures prior to surgery and have been shown in this study to significantly reduced the degree of interobserver variability in fracture classification. This effect is particularly evident for less experienced surgeons. This technique is available and relatively inexpensive. The use of these models should prove invaluable as a tool to aid clinical practice.

Clinical applications of computerized tomography 3-D reconstruction imaging for diagnosis and surgery in children with large liver tumors or tumors at the hepatic hilum

The present study assessed the benefits of 3-D reconstruction of spiral computerized tomography (CT) scans for the diagnosis of and surgical guidance to large liver tumors or tumors at the hepatic hilum. We retrospectively analyzed the cases of 18 children with large liver tumors or with tumors at the hepatic hilum treated in past 5 years. The ages ranged from 45 days to 14 years. Ten cases were examined using the three-dimensional reconstruction using 64 slice spiral CT and eight patients underwent conventional CT or conventional enhanced CT scanning. In 16 cases, the volume of tissue removed exceeded one-third the entire volume of the liver (considered "large" tumors). The largest tumor removed weighed 4.8 kg. In two cases, the excised tissue represented less than one-third of the total liver volume, but in these cases the location of the tumor was considered "complex" due to the proximity to major hepatic vessels. Seven tumors were located in the right lobe, three in the left lateral segment, three in medial segment, three extended beyond the right lobe and two extended beyond the left lateral segment. Pathological diagnoses included hepatoblastoma (n = 9), hepatocellular carcinoma (n = 2), mesenchymal hamartoma (n = 4), teratoma (n = 1) and adenoma (n = 2). The 3-D reconstructed images could be rotated to view the image from several sides, were semitransparent and allowed for the measurement of tumor size and determination of spatial relation to blood vessels. All 18 children had curative resections as indicated by "tumor-free" microscopic margins. No major intra- or postoperative complications were encountered. Three-dimensional CT imaging can provide high quality images of the tumors and location of the tumor relative to vital hepatic blood vessels. This technique offers a kind of comparatively accurate method compared with traditional imaging techniques, it could help the surgeon identify the tumor borders accurately and devise a comparative safe surgical strategy. With its help the surgeon could identify vital hepatic blood vessels before operation, so they can avoid massive hemorrhaging and avoid massive hemorrhaging during operation. This technique should be more widely applied in the resection of large or complex liver tumors.