An infrared motion detector system for lossless real-time monitoring of animal preference tests.

Automated behavioural observations are routinely used in many fields of biology, including ethology, behavioural ecology and physiology. When preferences for certain resources are investigated, the focus is often on simple response variables, such as duration and frequency of visits to choice chambers. Here we present an automated motion detector system that use passive infrared sensors to eliminate many drawbacks of currently existing methods. Signals from the sensors are processed by a custom-built interface, and after unnecessary data is filtered by a computer software, the total time and frequency of the subject's visits to each of the choice chambers are calculated. We validate the detector system by monitoring (using the system) and in the same time video recording mating preferences of zebra finches in a four-way choice apparatus. Manual scoring of the video recordings showed very high consistency with data from the detector system both for time and for frequency of visits. Furthermore, the validation revealed that if we used micro-switches or light barriers, the most commonly applied automatic detection techniques, this would have resulted in approximately 22% less information compared to our lossless system. The system provides a low-cost alternative for monitoring animal movements, and we discuss its further applicability.

On the evolution and relative merits of hard X-ray phase-contrast imaging methods.

This review provides a brief overview, albeit from a somewhat personal perspective, of the evolution and key features of various hard X-ray phase-contrast imaging (PCI) methods of current interest in connection with translation to a wide range of imaging applications. Although such methods have already found wide-ranging applications using synchrotron sources, application to dynamic studies in a laboratory/clinical context, for example for in vivo imaging, has been slow due to the current limitations in the brilliance of compact laboratory sources and the availability of suitable high-performance X-ray detectors. On the theoretical side, promising new PCI methods are evolving which can record both components of the phase gradient in a single exposure and which can accept a relatively large spectral bandpass. In order to help to identify the most promising paths forward, we make some suggestions as to how the various PCI methods might be compared for performance with a particular view to identifying those which are the most efficient, given the fact that source performance is currently a key limiting factor on the improved performance and applicability of PCI systems, especially in the context of dynamic sample studies. The rapid ongoing development of both suitable improved sources and detectors gives strong encouragement to the view that hard X-ray PCI methods are poised for improved performance and an even wider range of applications in the near future.

X-ray phase-contrast microscopy and microtomography.

In-line phase contrast enables weakly absorbing specimens to be imaged successfully with x-rays, and greatly enhances the visibility of fine scale structure in more strongly absorbing specimens. This type of phase contrast requires a spatially coherent beam, a condition that can be met by a microfocus x-ray source. We have developed an x-ray microscope, based on such a source, which is capable of high resolution phase-contrast imaging and tomography. Phase retrieval enables quantitative information to be recovered from phase-contrast microscope images of homogeneous samples of known composition and density, and improves the quality of tomographic reconstructions.

Quantitative X-ray projection microscopy: phase-contrast and multi-spectral imaging.

We outline a new approach to X-ray projection microscopy in a scanning electron microscope (SEM), which exploits phase contrast to boost the quality and information content of images. These developments have been made possible by the combination of a high-brightness field-emission gun (FEG)-based SEM, direct detection CCD technology and new phase retrieval algorithms. Using this approach we have been able to obtain spatial resolution of < 0.2 micro m and have demonstrated novel features such as: (i) phase-contrast enhanced visibility of high spatial frequency image features (e.g. edges and boundaries) over a wide energy range; (ii) energy-resolved imaging to simultaneously produce multiple quasi-monochromatic images using broad-band polychromatic illumination; (iii) easy implementation of microtomography; (iv) rapid and robust phase/amplitude-retrieval algorithms to enable new real-time and quantitative modes of microscopic imaging. These algorithms can also be applied successfully to recover object-plane information from intermediate-field images, unlocking the potentially greater contrast and resolution of the intermediate-field regime. Widespread applications are envisaged for fields such as materials science, biological and biomedical research and microelectronics device inspection. Some illustrative examples are presented. The quantitative methods described here are also very relevant to projection microscopy using other sources of radiation, such as visible light and electrons.

Quantitative methods in phase-contrast x-ray imaging.

A new method for extracting quantitative information from phase-contrast x-ray images obtained with microfocus x-ray sources is presented. The proposed technique allows rapid noninvasive characterization of the internal structure of thick optically opaque organic samples. The method does not generally involve any sample preparation and does not need any x-ray optical elements (such as monochromators, zone plates, or interferometers). As a consequence, samples can be imaged in vivo or in vitro, and the images are free from optical aberrations. While alternative techniques of x-ray phase-contrast imaging usually require expensive synchrotron radiation sources, our method can be implemented with conventional, albeit microfocus, x-ray tubes, which greatly enhances its practicality. In the present work, we develop the theoretical framework, perform numerical simulations, and present the first experimental results, demonstrating the viability of the proposed approach. We believe that this method should find wide-ranging applications in clinical radiology and medical research.

Phase-contrast radiography.

For the past 100 years, the paradigm for radiography has been premised on absorption as the sole means of contrast formation and on ray optics as the basis for image interpretation. A new conceptual approach to radiography has been developed that includes phase (ie, refractive) contrast and requires wave optics for proper treatment. This new approach greatly increases the amount of information that can be obtained with radiographic techniques and is particularly well suited to the imaging of soft tissue and of very small features in biologic samples. A key feature of the present technique of phase-contrast radiography is the use of a microfocus x-ray source about an order of magnitude (< or = 20 microm) smaller than that used in conventional radiography. Phase-contrast radiography offers a number of improvements over conventional radiography in a clinical setting, especially in soft-tissue imaging. These improvements include increased contrast resulting in improved visualization of anatomic detail, reduced absorbed dose to the patient, inherent image magnification and high spatial resolution, use of harder x rays, and relative ease of implementation. More technologically advanced detectors are currently being developed and commercialized, which will help fully realize the considerable potential of phase-contrast imaging.

Noninvasive evaluation of suspected thoracic aortic disease by contrast-enhanced computed tomography.

Traditionally, suspected thoracic aortic disease has been evaluated by aortography, which has associated risks because it is invasive. With the introduction of computed tomography (CT), a noninvasive alternative has become available. In the present retrospective study, the potential clinical value of CT in providing correct diagnoses and pertinent information required for current therapies is evaluated. For this purpose, results of CT in 200 patients examined for suspected thoracic aortic disease were compared with "hard" (surgical and autopsy findings) or "soft" (follow-up clinical information) evidence of the true diagnoses. Aortographic results, available in 51 patients (26%), were also compared with available clinical evidence. Excluding inadequate examinations, the diagnostic accuracy of the independently and blindly interpreted results of CT and aortography were similar (86% and 87%, respectively) in patients with true diagnoses confirmed by hard evidence. When patients evaluated for aortic damage from acute blunt chest trauma were also excluded, the accuracy was 90% for CT and 86% for aortography. Specifically, CT was 83% and 67% accurate in proved (i.e., confirmed by hard evidence) type A and type B dissections, respectively (75% for both type A and B by aortography). In the 183 patients suspected of having thoracic aortic disease not attributable to acute blunt chest trauma and with follow-up information, 91% would have been managed appropriately based on their CT evaluation alone. In the subset of patients who underwent aortographic evaluation as well, 91% would have been managed appropriately based on aortography alone. The accuracy for combined CT and aortography was 94%.(ABSTRACT TRUNCATED AT 250 WORDS)

Extrahepatic extraction of salicylamide in dogs.

Extrahepatic conjugation may be an important mechanism for the metabolism of many phenolic compounds. We have observed dose-dependent sulfoconjugation of salicylamide (SAM) in the lung, kidney and forelimb of dogs during steady-state infusions. The lungs alone accounted for more than one-half the total elimination at the lowest infusion rate (0.3 microgram/min/kg). The limbs appeared to play an important secondary role in SAM elimination whereas the kidneys made only a minor contribution to total elimination. At the highest infusion rate (500 micrograms/min/kg), extrahepatic extraction approached zero and elimination by the three extrahepatic sites fell to less than 31% of total elimination. Dose-dependent elimination at the three extrahepatic sites was responsible for most of the dose dependence observed in these studies. Extrahepatic extraction was insensitive to plasma inorganic sulfate. Clearance significantly, but only slightly, increased on coinfusing sodium sulfate at a rate that increased plasma inorganic sulfate from one-sixth (after depletion by SAM infusion) to two times normal.

Percutaneous removal of renal staghorn calculi.

Using a percutaneous approach, 18 of 20 staghorn calculi were completely removed from the upper urinary tract. The initial nephrostomy was performed in the radiology department with local anesthesia. Tract dilatation and stone removal ensued on the next day in the operating room under general anesthesia. Minor complications, including postoperative temperature spikes and pyelonephritis, occurred in seven patients. Two major complications, urosepsis and hemorrhage requiring transfusion, were encountered.

Radiologic intervention in oriental cholangiohepatitis.

Interventional radiologic techniques can make a useful contribution to the management of patients with recurrent symptoms following surgical palliation of oriental cholangiohepatitis. Percutaneous removal of multiple, soft, pigmented biliary stones that form in this disease can be achieved by a combination of basket retrieval and crushing, as well as suction and irrigation techniques. Ducts that are obstructed by strictures can be drained by percutaneous catheters. Complete or partial symptomatic relief was obtained in six of eight patients, obviating additional surgical intervention.

Esophageal rupture: complication of balloon dilatation.

Recent studies have emphasized the safety of fluoroscopically guided balloon dilatation for treatment of severe esophageal strictures. A case of esophageal rupture that followed dilatation of a distal esophageal stricture with a 20-mm balloon catheter is reported.

Peripheral vascular disease: correlation of MR imaging and angiography.

The capability of magnetic resonance (MR) imaging for detecting aortic, iliac, and femoral stenoses and occlusions was evaluated. Multisection spin-echo studies at 0.35 tesla were obtained of the infrarenal aorta to the femoral bifurcation in 24 patients, all of whom had undergone intraarterial angiography within 14 days of imaging. Transaxial MR images were compared with the angiograms. Arterial stenoses and occlusions in these vessels detected by MR imaging correlated with angiographic findings in 91% of the instances. Protrusional atherosclerotic plaques and occlusions and stenoses in the aortoiliac region were demonstrated accurately on MR images; complications of previous vascular surgery, such as aneurysms at sites of previous anastomoses or endarterectomy, were also identified. Due to the limited spatial resolution, MR images failed to demonstrate some femoral stenoses. MR imaging may be used for evaluation of aortoiliac vascular disease and for follow-up study after surgical revascularization. However, the limited spatial resolution, noncomposite display of the aortoiliofemoral circulation, and lack of evaluation of peripheral runoff provided by current MR imaging techniques militate against its replacing angiography prior to vascular intervention.

Septic endarteritis after percutaneous transluminal angioplasty.

A case of septic endarteritis leading to septic arthritis and septic emboli occurred after percutaneous transluminal angioplasty. To our knowledge, this is the first reported instance of arterial wall infection potentially caused by percutaneous transluminal angioplasty. Treatment consisted of long-term intravenous antibiotics and drainage of the septic joint.

Percutaneous drainage techniques. Alternatives to surgical therapy.

Percutaneous drainage techniques are widely used to relieve biliary and urinary obstructions as well as to evacuate abdominal abscesses. These drainage techniques are less expensive, safer, and in many cases more effective than comparable surgical procedures. Proper follow-up care of catheters is essential, however, to achieve maximum effectiveness.

Abdominal abscess with low-output fistula: successful percutaneous drainage.

Abdominal abscesses in 72 patients were drained percutaneously. Sinograms were obtained at the time of drainage and repeated three to six days later. In 32 patients, a low-output fistulous communication to the alimentary canal, biliary tract, or pancreatic duct was demonstrated. Percutaneously placed drainage catheters provided successful treatment in 27 of these 32 patients. We conclude that low-output fistulous communications to abdominal cavities occur frequently, but can be managed successfully with percutaneous techniques in the majority of patients.