677 research outputs found
EFSUMB Recommendations and Guidelines for Gastrointestinal Ultrasound - Part 1: Examination Techniques and Normal Findings (Short version)
Abstract
▼
In October 2014 the European Federation of Societies
for Ultrasound in Medicine and Biology formed
a Gastrointestinal Ultrasound (GIUS) task force
group to promote the use of GIUS in a clinical setting.
One of the main objectives of the task force
group was to develop clinical recommendations
and guidelines for the use of GIUS under the auspices
of EFSUMB. The first part, gives an overview of
the examination techniques for GIUS recommended
by experts in the field. It also presents the
current evidence for the interpretation of normal
sonoanatomical and physiological features as examined
with different ultrasound modalities
EFSUMB Recommendations and Guidelines for Gastrointestinal Ultrasound - Part 1: Examination Techniques and Normal Findings (Long version).
Abstract
▼
In October 2014 the European Federation of Societies
for Ultrasound in Medicine and Biology formed
a Gastrointestinal Ultrasound (GIUS) task force
group to promote the use of GIUS in a clinical setting.
One of the main objectives of the task force
group was to develop clinical recommendations
and guidelines for the use of GIUS under the auspices
of EFSUMB. The first part, gives an overview of
the examination techniques for GIUS recommended
by experts in the field. It also presents the
current evidence for the interpretation of normal
sonoanatomical and physiological features as examined
with different ultrasound modalities
A pilot study of transrectal endoscopic ultrasound elastography in inflammatory bowel disease
BACKGROUND:
Using standard diagnostic algorithms it is not always possible to establish the correct phenotype of inflammatory bowel
disease which is essential for therapeutical decisions. Endoscopic ultrasound elastography is a new endoscopic procedure
which can differentiate the stiffness of normal and pathological tissue by ultrasound. Therefore, we aimed to investigate
the role of transrectal ultrasound elastography in distiction between Crohn's disease and ulcerative colitis. ----- METHODS:
A total 30 Crohn's disease, 25 ulcerative colitis, and 28 non-inflammatory bowel disease controls were included. Transrectal
ultrasound elastography was performed in all patients and controls. In all ulcerative coltis patients and 80% of Crohn's
disease patients endoscopy was performed to assess disease activity in the rectum. ----- RESULTS:
Significant difference in rectal wall thickness and strain ratio was detected between patients with Crohn's disease and
controls (p = 0.0001). CD patients with active disease had higher strain ratio than patients in remission (p = 0.02). In
ulcerative colitis group a significant difference in rectal wall thickness was found between controls and patients with
active disease (p = 0.03). A significant difference in rectal wall thickness (p = 0.02) and strain ratio (p = 0.0001) was
detected between Crohn's disease and ulcerative colitis patient group. Crohn's disease patients with active disease had a
significantly higher strain ratio compared to ulcerative colitis patients with active disease (p = 0.0001). ----- CONCLUSION:
Transrectal ultrasound elastography seems to be a promising new diagnostic tool in the field of inflammatory bowel
disease. Further study on a larger cohort of patients is needed to definitely assess the role of transrectal ultrasound
elastography in inflammatory bowel disease
The wavefront of the radio signal emitted by cosmic ray air showers
Analyzing measurements of the LOPES antenna array together with corresponding
CoREAS simulations for more than 300 measured events with energy above
eV and zenith angles smaller than , we find that the radio
wavefront of cosmic-ray air showers is of approximately hyperbolic shape. The
simulations predict a slightly steeper wavefront towards East than towards
West, but this asymmetry is negligible against the measurement uncertainties of
LOPES. At axis distances m, the wavefront can be approximated by
a simple cone. According to the simulations, the cone angle is clearly
correlated with the shower maximum. Thus, we confirm earlier predictions that
arrival time measurements can be used to study the longitudinal shower
development, but now using a realistic wavefront. Moreover, we show that the
hyperbolic wavefront is compatible with our measurement, and we present several
experimental indications that the cone angle is indeed sensitive to the shower
development. Consequently, the wavefront can be used to statistically study the
primary composition of ultra-high energy cosmic rays. At LOPES, the
experimentally achieved precision for the shower maximum is limited by
measurement uncertainties to approximately g/cm. But the simulations
indicate that under better conditions this method might yield an accuracy for
the atmospheric depth of the shower maximum, , better than
g/cm. This would be competitive with the established air-fluorescence
and air-Cherenkov techniques, where the radio technique offers the advantage of
a significantly higher duty-cycle. Finally, the hyperbolic wavefront can be
used to reconstruct the shower geometry more accurately, which potentially
allows a better reconstruction of all other shower parameters, too.Comment: accepted by JCA
On noise treatment in radio measurements of cosmic ray air showers
Precise measurements of the radio emission by cosmic ray air showers require
an adequate treatment of noise. Unlike to usual experiments in particle
physics, where noise always adds to the signal, radio noise can in principle
decrease or increase the signal if it interferes by chance destructively or
constructively. Consequently, noise cannot simply be subtracted from the
signal, and its influence on amplitude and time measurement of radio pulses
must be studied with care. First, noise has to be determined consistently with
the definition of the radio signal which typically is the maximum field
strength of the radio pulse. Second, the average impact of noise on radio pulse
measurements at individual antennas is studied for LOPES. It is shown that a
correct treatment of noise is especially important at low signal-to-noise
ratios: noise can be the dominant source of uncertainty for pulse height and
time measurements, and it can systematically flatten the slope of lateral
distributions. The presented method can also be transfered to other experiments
in radio and acoustic detection of cosmic rays and neutrinos.Comment: 4 pages, 6 figures, submitted to NIM A, Proceedings of ARENA 2010,
Nantes, Franc
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