To determine the accuracy of cone beam CT (CBCT) guidance and CT guidance in reaching small targets in relation to needle path complexity in a phantom.
CBCT guidance combines three-dimensional CBCT ...imaging with fluoroscopy overlay and needle planning software to provide real-time needle guidance. The accuracy of needle positioning, quantified as deviation from a target, was assessed for inplane, angulated and double angulated needle paths. Four interventional radiologists reached four targets along the three paths using CBCT and CT guidance. Accuracies were compared between CBCT and CT for each needle path and between the three approaches within both modalities. The effect of user experience in CBCT guidance was also assessed.
Accuracies for CBCT were significantly better than CT for the double angulated needle path (2.2 vs 6.7 mm, p<0.001) for all radiologists. CBCT guidance showed no significant differences between the three approaches. For CT, deviations increased with increasing needle path complexity from 3.3 mm for the inplane placements to 4.4 mm (p=0.007) and 6.7 mm (p<0.001) for the angulated and double angulated CT-guided needle placements, respectively. For double angulated needle paths, experienced CBCT users showed consistently higher accuracies than trained users 1.8 mm (range 1.2-2.2) vs 3.3 mm (range 2.1-7.2) deviation from target, respectively; p=0.003.
In terms of accuracy, CBCT is the preferred modality, irrespective of the level of user experience, for more difficult guidance procedures requiring double angulated needle paths as in oncological interventions.
Accuracy of CBCT guidance has not been discussed before. CBCT guidance allows accurate needle placement irrespective of needle path complexity. For angulated and double-angulated needle paths, CBCT is more accurate than CT guidance.
The results of a leading-order QCD analysis of neutrino-induced charm production are presented. They are based on a sample of 4111 $\numu$- and 871 $\anumu$-induced opposite-sign dimuon events with ...$E_{\mu 1},E_{\mu 2} 6~{\rm GeV}$, $35 E_{\nu} 290~{\rm GeV}$ and $Q^2 5.5\,{\rm GeV^2}$, observed in the CHARM~II detector exposed to the CERN wideband neutrino and antineutrino beams. The analysis yields the value of \linebreak the charm quark mass $m_c=1.79\pm0.38\,{\rm GeV}/c^2$ and the Cabibbo--Kobayashi--Maskawa matrix element $|V_{cd}|=0.219\pm0.016$. The strange quark content of the nucleon is found to be suppressed with respect to non-strange sea quarks by a factor $\kappa =0.39\pm0.09$.
A new search for decays of heavy isosinglet neutrinos produced by neutral-current neutrino interactions in the CERN wide-band neutrino beam has been conducted by the CHARM-II Collaboration. We ...searched for heavy neutrinos created by scattering muon neutrinos on nucleons and decaying into
μ
+
μ
−
ν
μ
. Production and decay of heavy neutrinos would appear as double events in the detector. Each double event candidate was tested wheather the measured quantities are compatible with the kinematics of this process. No event passed this test. The analysis is based on 2 × 10
7 neutral-current neutrino events collected from 1987–1991. The experiment is sensitive to heavy neutrinos in the mass range 0.3–2.4 GeV/
c
2
. The best limit for the mixing parameter is |
U
μi
|
2 < 3 × 10
−5 for a mass around 2 GeV/
c
2
. The analysis improve order of magnitude previous results derived from wide-band neutrino beam exposures of the CHARM detector.
A subfamily of Drosophila homeodomain (HD) transcription factors (TFs) controls the identities of individual muscle founder cells (FCs). However, the molecular mechanisms by which these TFs generate ...unique FC genetic programs remain unknown. To investigate this problem, we first applied genome-wide mRNA expression profiling to identify genes that are activated or repressed by the muscle HD TFs Slouch (Slou) and Muscle segment homeobox (Msh). Next, we used protein-binding microarrays to define the sequences that are bound by Slou, Msh and other HD TFs that have mesodermal expression. These studies revealed that a large class of HDs, including Slou and Msh, predominantly recognize TAAT core sequences but that each HD also binds to unique sites that deviate from this canonical motif. To understand better the regulatory specificity of an individual FC identity HD, we evaluated the functions of atypical binding sites that are preferentially bound by Slou relative to other HDs within muscle enhancers that are either activated or repressed by this TF. These studies showed that Slou regulates the activities of particular myoblast enhancers through Slou-preferred sequences, whereas swapping these sequences for sites that are capable of binding to multiple HD family members does not support the normal regulatory functions of Slou. Moreover, atypical Slou-binding sites are overrepresented in putative enhancers associated with additional Slou-responsive FC genes. Collectively, these studies provide new insights into the roles of individual HD TFs in determining cellular identity, and suggest that the diversity of HD binding preferences can confer regulatory specificity.
Atherosclerotic carotid artery disease is responsible for a variety of clinical presentations, ranging from asymptomatic to cerebral ischemic events. Considering the upcoming use of noninvasive ...imaging modalities, plaque characteristics could serve as a marker in the selection of patients eligible for carotid endarterectomy (CEA). This would be more likely if characteristics corresponded with clinical manifestations and were predictive of future events. In this study, we hypothesized that plaque characteristics correlate with the clinical presentation of carotid artery disease.
We included 404 patients undergoing a carotid endarterectomy (CEA). Ipsilateral clinical symptoms and duplex measurements were recorded. Patients could be asymptomatic (23.5%) or symptomatic with stroke (26.5%), transient ischemic attack (TIA) (36.1%), or amaurosis fugax (AFX) (13.9%). Plaques were stained and semi-quantitatively analyzed for the presence of macrophages, smooth muscle cells, collagen, calcifications, and thrombus. Plaques were categorized in three phenotypes by their overall presentation and the amount of fat. In addition, plaque matrix metalloproteinase (MMP) activity and cytokines expressions were measured.
Fibrous, fibro-atheromatous, and atheromatous plaques were observed in 30.2%, 35.6%, and 34.2%, respectively. Atheromatous plaques were more prevalent in patients with stroke and TIA compared with asymptomatic patients or patients with AFX (P = .001). Collagen staining was less evident in patients with TIA and stroke compared with asymptomatic patients or patients with AFX (P < .001). Plaques of patients with TIA and stroke showed significantly higher activity levels of MMP-8 and MMP-9 and higher levels of interleukin-8 compared with asymptomatic and AFX patients.
Plaque phenotype of patients with TIA is comparable to that of patients with stroke; whereas, the plaque phenotype of patients with AFX resembles the plaque phenotype of asymptomatic patients. Follow-up studies should be encouraged to determine whether plaque characteristics visualized by imaging techniques might help to identify patients most likely to benefit from CEA.
The H1 forward proton spectrometer at HERA van Esch, P.; Kapichine, M.; Morozov, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2000, Letnik:
446, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The forward proton spectrometer is part of the H1 detector at the HERA collider. Protons with energies above 500
GeV and polar angles below 1
mrad can be detected by this spectrometer. The main ...detector components are scintillating fiber detectors read out by position-sensitive photo-multipliers. These detectors are housed in the so-called Roman Pots which allow them to be moved close to the circulating proton beam. Four Roman Pot stations are located at distances between 60 and 90
m from the interaction point.
We report new bounds on electromagnetic properties of the muon neutrino obtained from a study of neutrino-electron scattering. The results are based on the analysis of differential cross section data ...collected with the CHARM II detector. The 90% C.L. limit on the magnetic moment of the muon-neutrino
μ
ν
μ
< 3 · 10
−9
μ
B
confirms limits obtained at much lower energies. The limit on the anomalous charge radius of the muon neutrino |〈
r
2〉
anom| < 6.0 · 10
−33 cm
2 im earlier results by nearly a factor three.
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