Search

STUDY DESIGN:A retrospective cross-sectional study. OBJECTIVE:To assess the sensitivity to change and reliability of various mid-sagittal and axial plane metrics in the assessment of patients with single-level degenerative cervical stenosis on T2-weighted MR imaging. SETTING:A diagnostic MR imaging facility in Sydney (Australia). METHODS:We retrospectively reviewed T2-weighted MR images of 85 consecutive patients (48 M and 37 F) with single-level degenerative cervical stenosis. Canal compromise and cord compression were evaluated using three mid-sagittal plane metrics (M1, M2, and M3) and two axial plane metrics (M4 and M5), at the level of stenosis and nonstenotic cephalad and caudal levels (controls). Sensitivity to change (SC) for each metric was evaluated as the percentage deviation of the measured value from the estimated normal value based on cephalad and caudal controls. Reliability for each metric was evaluated using intraclass correlation coefficients. RESULTS:Degenerative cervical stenosis showed a bimodal distribution peaking at C5-6 (n = 32) and C3-4 (n = 29) levels. The changes in the canal and cord geometry along the rostrocaudal axis were inconsistent. Across all individual subjects (reflecting a range of stenosis severity), M3 (-32.87% ± 10.60%) was more sensitive to change compared with M1 (16.64% ± 16.48%) and M2 (-23.95% ± 11.12%). Similarly, M4 (-24.62% ± 12.17%) was more sensitive to change compared with M5 (-6.71% ± 11.08%). The level of reliability was "moderate" to "excellent" for mid-sagittal plane measurements, and "poor" to "excellent" for axial plane measurements. CONCLUSION:Changes in canal dimensions in the mid-sagittal plane and cord shape in the axial plane are sensitive indicators of degenerative cervical stenosis on T2-weighted MR images.

The astrophysical journal 836(2), 205 (2017). doi:10.3847/1538-4357/836/2/205, B2 1215+30 is a BL-Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes and subsequently confirmed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory with data collected between 2009 and 2012. In 2014 February 08, VERITAS detected a large-amplitude flare from B2 1215+30 during routine monitoring observations of the blazar 1ES 1218+304, located in the same field of view. The TeV flux reached 2.4 times the Crab Nebula flux with a variability timescale of $\lt 3.6\,\mathrm{hr}$. Multiwavelength observations with Fermi-LAT, Swift, and the Tuorla Observatory revealed a correlated high GeV flux state and no significant optical counterpart to the flare, with a spectral energy distribution where the gamma-ray luminosity exceeds the synchrotron luminosity. When interpreted in the framework of a one-zone leptonic model, the observed emission implies a high degree of beaming, with Doppler factor $\delta \gt 10$, and an electron population with spectral index $p\lt 2.3$., Published by IOP Publ., Chicago, Ill. [u.a.]

Contrast agent-enhanced magnetic resonance (MR) imaging is critical for the diagnosis and monitoring of a number of diseases, including cancer. Certain clinical applications, including the detection of liver tumors, rely on both T1 and T2-weighted images even though contrast agent-enhanced MR imaging is not always reliable. Thus, there is a need for improved dual mode contrast agents with enhanced sensitivity. We report the development of a nanodiamond–manganese dual mode contrast agent that enhanced both T1 and T2-weighted MR imaging. Conjugation of manganese to nanodiamonds resulted in improved longitudinal and transverse relaxivity efficacy over unmodified MnCl2 as well as clinical contrast agents. Following intravenous administration, nanodiamond–manganese complexes outperformed current clinical contrast agents in an orthotopic liver cancer mouse model while also reducing blood serum concentration of toxic free Mn2+ ions. Thus, nanodiamond–manganese complexes may serve as more effective dual mode MRI contrast agent, particularly in cancer.

Balanced steady-state free precession is an ultrafast sequence with high signal-to-noise efficiency, but it also generates a strong fat signal which can mask important features. One method of fat suppression is to modify the balanced steady-state free precession spectrum using multiple repetition times to create a wide stopband over the fat frequency. However, with three or more pulse repetition times, the number of parameters creates a vast search space with many local minima of a cost function. We report on the initial results of using simulated annealing to find optimal sequences for two applications of multiple-pulse repetition time balanced steady-state free precession: positive contrast imaging and fat suppression.

MR-encephalography is a technique that allows real-time observation of functional changes in the brain with a time-resolution of 100 ms. The high sampling rate is enabled by the use of undersampled image acquisition with regularized reconstruction. The article describes a novel imaging method for fast three-dimensional-MR-encephalography whole brain coverage based on undersampled, single-shot concentric shells trajectories and the use of multiple small receiver coils. The technique allows the observation of changes in blood oxygenation level dependent signal as a measure of brain physiology at very high temporal resolution.

Prospective motion correction can prevent motion artifacts in magnetic resonance imaging of the brain. However, for high-resolution imaging, the technique relies on precise tracking of head motion. This precision is often limited by tracking noise, which leads to residual errors in the prospectively-corrected k-space data and artifacts in the image. This work shows that it is possible to estimate these tracking errors, and hence the true k-space sample locations, by applying a two-sided filter to the tracking data after imaging. A conjugate gradient reconstruction is compared to gridding as a means of using this information to retrospectively correct for the effects of the residual errors.

MR-Encephalography (MREG) is a technique that allows real time observation of functional changes in the brain that appears within 100 msec. The high sampling rate is achieved at the cost of some spatial resolution. The article describes a novel imaging method for fast three-dimensional-MR-encephalography whole brain coverage based on rosette trajectories and the use of multiple small receiver coils. The technique allows the observation of changes in brain physiology at very high temporal resolution. A highly undersampled three-dimensional rosette trajectory is chosen, to perform single shot acquisition of k-space data within 23 msec. By using a 32-channel head coil array and regularized nonuniform Fourier transformation reconstruction, the spatial resolution is sufficient to detect even subtle centers of activation (e.g. human MT+). The method was applied to visual block design paradigms and compared with echo planar imaging-based functional MRI. As a proof-of-principle of the method's ability to detect local differences in the hemodynamic response functions, the analyzed MR-encephalography data revealed a spatially dependent delay of the arrival of the blood oxygenation level dependent response within the visual cortex. Magn Reson Med, 2011. © 2011 Wiley-Liss, Inc.

This work presents a new imaging sequence in which multiple slices are simultaneously excited and refocused in a spin-echo train. The multiple spin-echo trains are interleaved in such a manner that (i) the Carr-Purcell-Meiboom-Gill conditions are fulfilled at all times, and (ii) the signals from slices can be separated, preventing aliasing. This paper also demonstrates how the sequence may be used in a novel fat-water Dixon method that enables fast volume coverage. The technique is demonstrated in phantoms and in vivo.

Ruthenium σ-acetylides containing a dangling pyridine were synthesized from the reactions of CpRu(L)2Cl (L = PPh3, 1/2 (C5H4PPh2)2Fe) with 4-ethynylpyridine, (E)-1-(4-ethynylphenyl)-2-(4-pyridyl)et...

Treatment of [NMe4]3[M3(CO)9(μ-OEt)(μ3-OEt)2] (1, M = Mo; 2, M = W) with 3 equiv of (Ph3P)AuCl/TlPF6 affords M3(CO)9(AuPPh3)3(μ-OEt)(μ3-OEt)2 (3, M = Mo; 4, M = W) in 80% and 89% yields, respectively. The molecular structures of 3 and 4 have been determined by X-ray diffraction methods. Complexes 3 and 4 are isomorphous. Variable-temperature 31P{H} and 1H NMR spectra for 3, 4, and related complex [NMe4][W3(CO)9(Au2(μ-dppm))(μ-OEt)(μ3-OEt)2] (6) verify valence isomerization in these complexes at ambient conditions.

Prospective motion correction can prevent motion artifacts in magnetic resonance imaging of the brain. However, for high-resolution imaging, the technique relies on precise tracking of head motion. This precision is often limited by tracking noise, which leads to residual errors in the prospectively-corrected k-space data and artifacts in the image. This work shows that it is possible to estimate these tracking errors, and hence the true k-space sample locations, by applying a two-sided filter to the tracking data after imaging. A conjugate gradient reconstruction is compared to gridding as a means of using this information to retrospectively correct for the effects of the residual errors.

MR-Encephalography (MREG) is a technique that allows real time observation of functional changes in the brain that appears within 100 msec. The high sampling rate is achieved at the cost of some spatial resolution. The article describes a novel imaging method for fast three-dimensional-MR-encephalography whole brain coverage based on rosette trajectories and the use of multiple small receiver coils. The technique allows the observation of changes in brain physiology at very high temporal resolution. A highly undersampled three-dimensional rosette trajectory is chosen, to perform single shot acquisition of k-space data within 23 msec. By using a 32-channel head coil array and regularized nonuniform Fourier transformation reconstruction, the spatial resolution is sufficient to detect even subtle centers of activation (e.g. human MT+). The method was applied to visual block design paradigms and compared with echo planar imaging-based functional MRI. As a proof-of-principle of the method's ability to detect local differences in the hemodynamic response functions, the analyzed MR-encephalography data revealed a spatially dependent delay of the arrival of the blood oxygenation level dependent response within the visual cortex.

Splice-site mutations in the beta-globin gene can lead to aberrant transcripts and decreased functional beta-globin, causing beta-thalassemia. Triplex-forming DNA oligonucleotides (TFOs) and peptide nucleic acids (PNAs) have been shown to stimulate recombination in reporter gene loci in mammalian cells via site-specific binding and creation of altered helical structures that provoke DNA repair. We have designed a series of triplex-forming PNAs that can specifically bind to sequences in the human beta-globin gene. We demonstrate here that these PNAs, when cotransfected with recombinatory donor DNA fragments, can promote single base-pair modification at the start of the second intron of the beta-globin gene, the site of a common thalassemia-associated mutation. This single base pair change was detected by the restoration of proper splicing of transcripts produced from a green fluorescent protein-beta-globin fusion gene. The ability of these PNAs to induce recombination was dependent on dose, sequence, cell-cycle stage, and the presence of a homologous donor DNA molecule. Enhanced recombination, with frequencies up to 0.4%, was observed with use of the lysomotropic agent chloroquine. Finally, we demonstrate that these PNAs were effective in stimulating the modification of the endogenous beta-globin locus in human cells, including primary hematopoietic progenitor cells. This work suggests that PNAs can be effective tools to induce heritable, site-specific modification of disease-related genes in human cells.

Gamma knife treatments are usually planned manually, requiring much expertise and time. We describe a new, fully automatic method of treatment planning. The treatment volume to be planned is first compared with a database of past treatments to find volumes closely matching in size and shape. The treatment parameters of the closest matches are used as starting points for the new treatment plan. Further optimization is performed with the Nelder-Mead simplex method: the coordinates and weight of the isocenters are allowed to vary until a maximally conformal plan specific to the new treatment volume is found. The method was tested on a randomly selected set of 10 acoustic neuromas and 10 meningiomas. Typically, matching a new volume took under 30 seconds. The time for simplex optimization, on a 3 GHz Xeon processor, ranged from under a minute for small volumes (1000 cubic mm, 2-3 isocenters), to several tens of hours for large volumes (30,000 cubic mm,20 isocenters). In 8/10 acoustic neuromas and 8/10 meningiomas, the automatic method found plans with conformation number equal or better than that of the manual plan. In 4/10 acoustic neuromas and 5/10 meningiomas, both overtreatment and undertreatment ratios were equal or better in automated plans. In conclusion, data-mining of past treatments can be used to derive starting parameters for treatment planning. These parameters can then be computer optimized to give good plans automatically.

A wideband GaInP/GaAs HBT micromixer is demonstrated from DC to 8 GHz with 11 dB single-ended conversion gain. The input return loss is better than 10 dB for frequencies up to 9 GHz. The single-to-differential input stage in Gilbert micromixer renders good wideband frequency response and eliminates the need for common mode rejection. P1dB = -7 dBm and IIP3 = -7 dBm are achieved for a small local oscillator power of –2 dBm when LO=5.35 GHz and RF=5.7 GHz.

Acute transfusion-associated graft-versus-host disease (TA-GVHD) is rare but often fatal. Graft-versus-host disease that occurs as a complication of bone marrow transplantation is more common but has lower mortality. Features of TA-GVHD are nonspecific and can be confused with viral infections and drug reactions. We present a case of probable TA-GVHD in a patient with tuberous sclerosis who survived and was subsequently given irradiated blood without any further adverse events.

On January 1, 1993, the case definition of the acquired immunodeficiency syndrome (AIDS) in adults and adolescents used for monitoring the AIDS epidemic in California was expanded to include persons infected with the human immunodeficiency virus (HIV) with CD4 T-lymphocyte counts of less than 200 x 10(6) per liter (< 200 per mm3), pulmonary tuberculosis, recurrent pneumonia, or invasive cervical cancer. To assess the implications of this revision on AIDS case reporting in California, we compared cases reported through the end of 1994 based on 1 or more of the 4 new AIDS-defining conditions added in 1993 to cases reported based on pre-1993 AIDS-defining opportunistic infections and cancers. The 4 new conditions included in the 1993 expanded AIDS case definition accounted for a 23% increase in cumulative AIDS cases reported in California by the end of 1993, a 170% increase in the number of cases reported during 1993, and an 88% increase in the number of patients with AIDS living at the end of 1993. The number of cases reported in 1993 (19,629) was 124% more than that reported in 1992 (8,780) and 69% more than that reported in 1994 (11,587). The proportion of cases among women, injection-drug users, and African Americans also increased as a result of this change in the case definition. The expansion of the case definition may have resulted in a peak or plateau in the AIDS incidence in California because of reporting earlier in the HIV disease progression. The expanded case definition has enhanced the usefulness of AIDS surveillance data for targeting secondary prevention efforts, but more behavioral and HIV serosurveys are still needed to adequately target primary HIV prevention efforts.