1,695 research outputs found
Diagnosis of vertebral fractures in children: is a simplified algorithm-based qualitative technique reliable?
Background Identification of osteoporotic vertebral fractures
allows treatment opportunity reducing future risk. There is no
agreed standardised method for diagnosing paediatric vertebral
fractures.
Objective To evaluate the precision of a modified adult
algorithm-based qualitative (ABQ) technique, applicable to
children with primary or secondary osteoporosis.
Materials and methods Three radiologists independently
assessed lateral spine radiographs of 50 children with
suspected reduction in bone mineral density using a modified
ABQ scoring system and following simplification to include
only clinically relevant parameters, a simplified ABQ score. A
final consensus of all observers using simplified ABQ was
performed as a reference standard for fracture characterisation.
Kappa was calculated for interobserver agreement of the
components of both scoring systems and intraobserver agreement
of simplified ABQ based on a second read of 29 randomly
selected images.
Results Interobserver Kappa for modified ABQ scoring for
fracture detection, severity and shape ranged from 0.34 to
0.49 Kappa for abnormal endplate and position assessment
was 0.27 to 0.38. Inter- and intraobserver Kappa for simplified
ABQ scoring for fracture detection and grade ranged from
0.37 to 0.46 and 0.45 to 0.56, respectively. Inter- and
intraobserver Kappa for affected endplate ranged from 0.31
to 0.41 and 0.45 to 0.51, respectively. Subjectively, observers’
felt simplified ABQ was easier and less time-consuming.
Conclusion Observer reliability of modified and simplified
ABQ was similar, with slight to moderate agreement for fracture
detection and grade/severity. Due to subjective preference
for simplified ABQ, we suggest its use as a semi-objective
measure of diagnosing paediatric vertebral fracture
Diagnostic accuracy of DXA compared to conventional spine radiographs for the detection of vertebral fractures in children
Objectives
In children, radiography is performed to diagnose vertebral fractures and dual energy x-ray absorptiometry (DXA) to
assess bone density. In adults, DXA assesses both. We aimed to establish whether
DXA can replace spine radiographs in assessment of paediatric vertebral fractures.
Methods
Prospectively, lateral spine radiographs and lateral spine DXA of 250 children
performed on the same day were independently scored by three radiologists using
the simplified algorithm based qualitative technique and blinded to results of the
other modality. Consensus radiograph read and second read of 100 random images
were performed. Diagnostic accuracy, inter/intraobserver and intermodality
agreements, patient/carer experience and radiation dose were assessed.
Results
Average sensitivity and specificity (95% confidence interval) in diagnosing one or
more vertebral fractures requiring treatment was 70% (58%-82%) and 97% (94%-
100%) respectively for DXA and 74% (55%-93%) and 96% (95%-98%) for
radiographs. Fleiss’ kappa for interobserver and average kappa for intraobserver
reliability were 0.371 and 0.631 respectively for DXA and 0.418 and 0.621 for
radiographs. Average effective dose was 41.9µSv for DXA and 232.7µSv for
radiographs. Image quality was similar.
Conclusion
Given comparable image quality and non-inferior diagnostic accuracy, lateral spine
DXA should replace conventional radiographs for assessment of vertebral fractures
in children
A Study of Time-Dependent CP-Violating Asymmetries and Flavor Oscillations in Neutral B Decays at the Upsilon(4S)
We present a measurement of time-dependent CP-violating asymmetries in
neutral B meson decays collected with the BABAR detector at the PEP-II
asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The data
sample consists of 29.7 recorded at the
resonance and 3.9 off-resonance. One of the neutral B mesons,
which are produced in pairs at the , is fully reconstructed in
the CP decay modes , , , () and , or in flavor-eigenstate
modes involving and (). The flavor of the other neutral B meson is tagged at the time of
its decay, mainly with the charge of identified leptons and kaons. The proper
time elapsed between the decays is determined by measuring the distance between
the decay vertices. A maximum-likelihood fit to this flavor eigenstate sample
finds . The value of the asymmetry amplitude is determined from
a simultaneous maximum-likelihood fit to the time-difference distribution of
the flavor-eigenstate sample and about 642 tagged decays in the
CP-eigenstate modes. We find , demonstrating that CP violation exists in the neutral B meson
system. (abridged)Comment: 58 pages, 35 figures, submitted to Physical Review
Measurement of the quasi-elastic axial vector mass in neutrino-oxygen interactions
The weak nucleon axial-vector form factor for quasi-elastic interactions is
determined using neutrino interaction data from the K2K Scintillating Fiber
detector in the neutrino beam at KEK. More than 12,000 events are analyzed, of
which half are charged-current quasi-elastic interactions nu-mu n to mu- p
occurring primarily in oxygen nuclei. We use a relativistic Fermi gas model for
oxygen and assume the form factor is approximately a dipole with one parameter,
the axial vector mass M_A, and fit to the shape of the distribution of the
square of the momentum transfer from the nucleon to the nucleus. Our best fit
result for M_A = 1.20 \pm 0.12 GeV. Furthermore, this analysis includes updated
vector form factors from recent electron scattering experiments and a
discussion of the effects of the nucleon momentum on the shape of the fitted
distributions.Comment: 14 pages, 10 figures, 6 table
Measurement of the Branching Fraction for B- --> D0 K*-
We present a measurement of the branching fraction for the decay B- --> D0
K*- using a sample of approximately 86 million BBbar pairs collected by the
BaBar detector from e+e- collisions near the Y(4S) resonance. The D0 is
detected through its decays to K- pi+, K- pi+ pi0 and K- pi+ pi- pi+, and the
K*- through its decay to K0S pi-. We measure the branching fraction to be
B.F.(B- --> D0 K*-)= (6.3 +/- 0.7(stat.) +/- 0.5(syst.)) x 10^{-4}.Comment: 7 pages, 1 postscript figure, submitted to Phys. Rev. D (Rapid
Communications
Study of e+e- --> pi+ pi- pi0 process using initial state radiation with BABAR
The process e+e- --> pi+ pi- pi0 gamma has been studied at a center-of-mass
energy near the Y(4S) resonance using a 89.3 fb-1 data sample collected with
the BaBar detector at the PEP-II collider. From the measured 3pi mass spectrum
we have obtained the products of branching fractions for the omega and phi
mesons, B(omega --> e+e-)B(omega --> 3pi)=(6.70 +/- 0.06 +/- 0.27)10-5 and
B(phi --> e+e-)B(phi --> 3pi)=(4.30 +/- 0.08 +/- 0.21)10-5, and evaluated the
e+e- --> pi+ pi- pi0 cross section for the e+e- center-of-mass energy range
1.05 to 3.00 GeV. About 900 e+e- --> J/psi gamma --> pi+ pi- pi0 gamma events
have been selected and the branching fraction B(J/psi --> pi+ pi- pi0)=(2.18
+/- 0.19)% has been measured.Comment: 21 pages, 37 postscript figues, submitted to Phys. Rev.
Measurement of Branching Fraction and Dalitz Distribution for B0->D(*)+/- K0 pi-/+ Decays
We present measurements of the branching fractions for the three-body decays
B0 -> D(*)-/+ K0 pi^+/-B0 -> D(*)-/+ K*+/- using
a sample of approximately 88 million BBbar pairs collected by the BABAR
detector at the PEP-II asymmetric energy storage ring.
We measure:
B(B0->D-/+ K0 pi+/-)=(4.9 +/- 0.7(stat) +/- 0.5 (syst)) 10^{-4}
B(B0->D*-/+ K0 pi+/-)=(3.0 +/- 0.7(stat) +/- 0.3 (syst)) 10^{-4}
B(B0->D-/+ K*+/-)=(4.6 +/- 0.6(stat) +/- 0.5 (syst)) 10^{-4}
B(B0->D*-/+ K*+/-)=(3.2 +/- 0.6(stat) +/- 0.3 (syst)) 10^{-4}
From these measurements we determine the fractions of resonant events to be :
f(B0-> D-/+ K*+/-) = 0.63 +/- 0.08(stat) +/- 0.04(syst) f(B0-> D*-/+ K*+/-) =
0.72 +/- 0.14(stat) +/- 0.05(syst)Comment: 7 pages, 3 figures submitted to Phys. Rev. Let
Evidence for the Rare Decay B -> K*ll and Measurement of the B -> Kll Branching Fraction
We present evidence for the flavor-changing neutral current decay and a measurement of the branching fraction for the related
process , where is either an or
pair. These decays are highly suppressed in the Standard Model,
and they are sensitive to contributions from new particles in the intermediate
state. The data sample comprises
decays collected with the Babar detector at the PEP-II storage ring.
Averaging over isospin and lepton flavor, we obtain the branching
fractions and , where the
uncertainties are statistical and systematic, respectively. The significance of
the signal is over , while for it is .Comment: 7 pages, 2 postscript figues, submitted to Phys. Rev. Let
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