Whole-body x-ray dark-field radiography of a human cadaver

Background!#!Grating-based x-ray dark-field and phase-contrast imaging allow extracting information about refraction and small-angle scatter, beyond conventional attenuation. A step towards clinical translation has recently been achieved, allowing further investigation on humans.!##!Methods!#!After the ethics committee approval, we scanned the full body of a human cadaver in anterior-posterior orientation. Six measurements were stitched together to form the whole-body image. All radiographs were taken at a three-grating large-object x-ray dark-field scanner, each lasting about 40 s. Signal intensities of different anatomical regions were assessed. The magnitude of visibility reduction caused by beam hardening instead of small-angle scatter was analysed using different phantom materials. Maximal effective dose was 0.3 mSv for the abdomen.!##!Results!#!Combined attenuation and dark-field radiography are technically possible throughout a whole human body. High signal levels were found in several bony structures, foreign materials, and the lung. Signal levels were 0.25 ± 0.13 (mean ± standard deviation) for the lungs, 0.08 ± 0.06 for the bones, 0.023 ± 0.019 for soft tissue, and 0.30 ± 0.02 for an antibiotic bead chain. We found that phantom materials, which do not produce small-angle scatter, can generate a strong visibility reduction signal.!##!Conclusion!#!We acquired a whole-body x-ray dark-field radiograph of a human body in few minutes with an effective dose in a clinical acceptable range. Our findings suggest that the observed visibility reduction in the bone and metal is dominated by beam hardening and that the true dark-field signal in the lung is therefore much higher than that of the bone

THE DEVELOPMENT OF A FAR RED TO NEAR INFRARED FLUORESCENT PROBE FOR USE IN OPTICAL IMAGING

New techniques for biological optical imaging are of great interest for the detection and visualization of processes and disease in both clinical and research areas. One major advancement has been the use of far red and near infrared (NIR) light, as it has the ability to penetrate tissues deeper than other parts of the spectrum which are readily scatter and absorbed by the surroundings. In order to improve the signal to noise ratio and resolution of optical images, contrast agents are used. Fluorescent markers can be modified to attach to specific molecular targets, creating small molecular probes. These targets can be disease sites, or biological molecules which play a major role in processes such as tumor growth. It was our goal to create a new novel fluorescent probe, consisting of a cyanine based far red to NIR marker, and an n-hydroxysuccinimide (NHS) derivative to act as a linker, which could then bind with biological species containing primary amides such as proteins and antibodies, in this model system bovine serum albumin (BSA). The dye, a modified pentamethine carbocyanine, was synthesized according to Shao, et al., (Bioconjugate Chem 2008) and was chosen for its previous use for in vivo visualization and preferred spectral properties, as well as its ability to incorporate different functionalities. The linker was an azide functionalized NHS derivative chosen for its crosslinking ability with species containing primary amides. Azide and alkyne functionality were of great interest due to their reactivity in [2+3] dipolar cycloaddition click type reactions, which was used to attach an azide on the NHS derivative and an alkyne on the dye. This species was then bound to protein, BSA, successfully through this NHS moiety

In-vivo X-ray Dark-Field Chest Radiography of a Pig

X-ray chest radiography is an inexpensive and broadly available tool for initial assessment of the lung in clinical routine, but typically lacks diagnostic sensitivity for detection of pulmonary diseases in their early stages. Recent X-ray dark-field (XDF) imaging studies on mice have shown significant improvements in imaging-based lung diagnostics. Especially in the case of early diagnosis of chronic obstructive pulmonary disease (COPD), XDF imaging clearly outperforms conventional radiography. However, a translation of this technique towards the investigation of larger mammals and finally humans has not yet been achieved. In this letter, we present the first in-vivo XDF full-field chest radiographs (32 x 35 cm(2)) of a living pig, acquired with clinically compatible parameters (40 s scan time, approx. 80 mu Sv dose). For imaging, we developed a novel high-energy XDF system that overcomes the limitations of currently established setups. Our XDF radiographs yield sufficiently high image quality to enable radiographic evaluation of the lungs. We consider this a milestone in the bench-to-bedside translation of XDF imaging and expect XDF imaging to become an invaluable tool in clinical practice, both as a general chest X-ray modality and as a dedicated tool for high-risk patients affected by smoking, industrial work and indoor cooking

The role of contrast enhanced ultrasonography in post-operative surveillance of endovascular aortic aneurysm stent graft repair

MD (Res)Abdominal aortic aneurysms are common and responsible for many deaths. They are treated increasingly by EndoVascular Aneurysm Repair (EVAR) rather than conventional surgery. Approximately 25% of EVAR patients require re-intervention to prevent aneurysm enlargement which can rupture despite previous repair. All EVAR patients undergo life-long surveillance for complications such as stent-graft migration or endoleak. Computed Tomography (CT) has been the ‘gold-standard’ for surveillance accounting for 65% of EVAR costs, and exposes patients to cumulative radiation and nephrotoxic contrast. Duplex Ultrasound Scanning (DUS) has been proposed as an alternative for surveillance with lesser cost and patient risk. However, clinical studies have reported varying results. The addition of microbubble contrast significantly improves endoleak detection rates, making it comparable with CT. The physical properties that affect endoleak detection with DUS have not been determined. It is also unknown specifically which endoleaks’ detection are improved by Contrast Enhanced Aortic Duplex UltraSound Scanning (CEADUSS). To investigate the physical properties of endoleaks, I constructed an EVAR phantom model with a simulated endoleak of variable velocity (fast/slow), position (near/far) and plane (anterior/lateral/posterior). Preliminary studies investigated the behavior of microbubble contrast in the phantom system, and then laboratory experiments tested subjects over 36 variable endoleaks using DUS and CEADUSS. These laboratory experiments were translated clinically with a pilot study of CEADUSS in 10 patients with endoleaks on CT not detected by DUS, undefined endoleak type or origin, or a sac enlargement with no endoleak present. My experiments reveal an insight into factors influencing ultrasound endoleak detection. With this knowledge, the use of these modalities for surveillance protocols can be increased, reducing current CT burden, radiation and nephrotoxic contrast exposure, and overall EVAR cost. Clinical assessment of an endoleak, specifically noting physical characteristics (plane, position and velocity) will improve detection and surveillance

Department of Radiology-Annual Executive Summary Report-July 1, 2005 to June 30, 2006

98 page Department of Radiology Annual Executive Summary Report, July 1, 2005 to June 30, 2006, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania, United States