Diffusion-Weighted Imaging of the Head and Neck: Influence of Fat-Suppression Technique and Multishot 2D Navigated Interleaved Acquisitions.

BACKGROUND AND PURPOSE: DWI of the head and neck can reveal valuable information, but the effects of fat suppression and multishot acquisition on image quality have not been thoroughly investigated. We aimed to comprehensively compare the quality of head and neck DWI at 3T using 2 fat-suppression techniques, STIR, and spectral presaturation with inversion recovery, which were used with both single- and multishot EPI. MATERIALS AND METHODS: Sixty-five study participants underwent 3 DWI sequences of single-shot EPI-STIR, single-shot EPI-spectral presaturation with inversion recovery, and multishot EPI-spectral presaturation with inversion recovery of the head and neck. In multiple anatomic regions, 2 independent readers assessed 5-point visual scores for fat-suppression uniformity and image distortion, and 1 reader measured the contrast-to-noise ratio and ADC. RESULTS: The mean visual score for fat-suppression uniformity was higher in single-shot EPI-STIR than in other sequences (all regions except for the orbital region, P < .05). The mean visual score for image distortion was higher in multishot EPI-spectral presaturation with inversion recovery than in single-shot EPI sequences (all regions, P < .001). Contrast-to-noise ratio was mostly lower in single-shot EPI-STIR than in other sequences (P < .001), and ADC was significantly higher in multishot EPI-spectral presaturation with inversion recovery than in single-shot EPI sequences (P ≤ .001). CONCLUSIONS: Overall, multishot EPI-spectral presaturation with inversion recovery provided the best image quality, with relatively homogeneous fat suppression, less image distortion than single-shot EPI sequences, and higher contrast-to-noise ratio than single-shot EPI-STIR. The measured ADC values can be higher in multishot EPI-spectral presaturation with inversion recovery, which necessitates cautious application of the previously reported ADC values to clinical settings.

Reduction of Oxygen-Induced CSF Hyperintensity on FLAIR MR Images in Sedated Children: Usefulness of Magnetization-Prepared FLAIR Imaging.

BACKGROUND AND PURPOSE: Oxygen-induced CSF hyperintensity on FLAIR MR imaging is often observed in sedated children. This phenomenon can mimic leptomeningeal pathology and lead to a misdiagnosis. The purpose of this study was to investigate whether magnetization-prepared FLAIR MR imaging can reduce oxygen-induced CSF hyperintensity and improve image quality compared with conventional (non-magnetization-prepared) FLAIR MR imaging. MATERIALS AND METHODS: Bloch simulation for magnetization-prepared and non-magnetization-prepared FLAIR sequences was performed for tissue contrast. We retrospectively reviewed 85 children with epilepsy who underwent MR imaging under general anesthesia with supplemental oxygen (41 with non-magnetization-prepared FLAIR and 44 with magnetization-prepared FLAIR). CSF hyperintensity was scored from 0 to 3 points according to the degree of CSF signal intensity and was compared between the 2 sequences. The contrast-to-noise ratios among GM, WM, and CSF were evaluated to assess general image quality from both sequences. To assess the diagnostic accuracy for hemorrhage, we reviewed an additional 25 patients with hemorrhage. RESULTS: Bloch simulation demonstrated that CSF hyperintensity can be reduced on magnetization-prepared FLAIR compared with non-magnetization-prepared FLAIR. CSF hyperintensity scores were significantly lower in magnetization-prepared FLAIR than in non-magnetization-prepared FLAIR (P < .01). The contrast-to-noise ratios for GM-WM, GM-CSF, and WM-CSF were significantly higher in magnetization-prepared FLAIR than in non-magnetization-prepared FLAIR (P < .05). Hemorrhage was clearly demarcated from CSF hyperintensity in the magnetization-prepared group (100%, 12/12) and non-magnetization-prepared group (38%, 5/13). CONCLUSIONS: Magnetization-prepared 3D-FLAIR MR imaging can significantly reduce oxygen-induced CSF artifacts and increase the tissue contrast-to-noise ratio beyond the levels achieved with conventional non-magnetization-prepared 3D-FLAIR MR imaging.

Comment on "Near-edge X-ray absorption fine-structure investigation of graphene".

A Comment on the Letter by D. Pacilé et al., Phys. Rev. Lett. 101, 066806 (2008)10.1103/PhysRevLett.101.066806. The authors of the Letter offer a Reply.

Structure determination of new analogues of vardenafil and sildenafil in dietary supplements.

New analogues of vardenafil and sildenafil illegally added to dietary supplements were detected by high-performance liquid chromatography (HPLC) analysis with a photodiode array detector (PDA). These compounds were isolated and their structures elucidated by mass spectrometry (MS), infrared (IR) spectroscopy, one- and two-dimensional nuclear magnetic resonance (NMR). One of the new analogues given the trivial name pseudovardenafil (compound 1) was structurally elucidated and shown to be 1-[[3-(1,4-dihydro-5-methyl-4-oxo-7-propylimidazo[5,1-f][1,2,4]triazin-2-yl)-4-ethoxyphenyl]sulfonyl]-piperidine. It was a vardenafil analogue isolated from a dietary supplement capsule. Compared with vardenafil, the piperidine ring was substituted for the ethylpiperazine group. The second new analogue, trivially named hydroxyhongdenafil (compound 2), was separated from bulk powder used as a raw material for a dietary supplement. The piperazine and phenyl groups were connected through an acetyl group instead of a sulfonyl group, and hydroxyethylpiperazine was substituted for the methylpiperazine of sildenafil. It was structurally elucidated as 5-[2-ethoxy-5-[[4-(2-hydroxyethyl)-1-piperazinyl]acetyl]phenyl]-1,4-dihydro-1-methyl-3-propyl-7H-pyrazolo[4,3-d]pyrimidin-7-one.

Epitaxial growth and surface properties of half-metal NiMnSb films.

We present, herein, an extended study of the half-Heusler alloy NiMnSb, starting with the deposition technique, continuing with the basic structural and magnetic properties of the thin films, and finishing with the electronic and compositional properties of their surfaces. The experimental methods we apply combine magnetization and magnetoresistivity measurements, atomic force microscopy, ferromagnetic resonance, x-ray and neutron diffraction, low energy electron diffraction, angle resolved x-ray photoemission, extended x-ray absorption fine structure spectroscopy, soft x-ray magnetic circular dichroism and spin polarized inverse photoemission spectroscopy. We find that stoichiometric surfaces exhibit close to 100% spin polarization at the centre of the surface Brillouin zone at the Fermi edge at ambient temperatures. There is strong evidence for a moment reordering transition at around 80 K which marks the crossover from a high polarization state (T<80 K) to a more representative metallic ferromagnetic state (T>80 K). The results from the different experimental techniques are successively reviewed, with special emphasis on the interplay between composition and electronic structure of the NiMnSb film surfaces. Surface segregation, consistent with a difference in free enthalpy between the surface and the bulk, is induced by annealing treatments. This surface segregation greatly reduces the surface polarization.

Comparison of radioactivity measurements with radionuclide calibrators in the Republic of Korea.

Recognizing the importance of comparisons of radionuclide calibrators in nuclear medicine and the need to provide access to activity standards that are traceable to the international measurement system, the Korea Food & Drug Administration (KFDA) as a national secondary standard dosimetry laboratory (SSDL), started a comparison program in 2002. The first two comparisons were conducted with (131)I (71 participants) and (99m)Tc (72 participants). The results indicated that only 61% of reported activities for (131)I and 65% for (99m)Tc were within +/-5% of the correct value. These numbers increased to 84% for (131)I and 83% for (99m)Tc when a +/-10% limit was applied. Follow-up action on those calibrators with results outside the +/-10% limits only produced a small improvement. There was also a marked difference in performance between the various calibrator types used. The results have shown that such comparisons are necessary to improve the quality of the measurements and to identify those radionuclide calibrators that are not functioning correctly.

The cerebrovascular response to traditional acupuncture after stroke.

Acupuncture is useful in treating the nausea and vomiting related to chemotherapy, adult postoperative surgery pain and postoperative dental pain. We obtained single-photon emission computed tomography (SPECT) brain perfusion images of six patients with middle cerebral artery occlusion obtained before and after acupuncture and compared the changes in regional cerebral blood flow (rCBF) to those in normal control. Images were obtained before and after acupuncture at six traditional acupoints (LI 4, 10, 11, 15 and 16 and TE5) in the affected arm. The baseline image was subtracted from the postacupuncture image, to produce a subtraction image displaying only voxels with values >2 SD from the mean and those voxels were coregistered to the baseline SPECT or T2-weighted MRI. Similar images were obtained before and after acupuncture of eight normal volunteers. Statistical parametric mapping with a threshold of P =0.001 and a corrected P of 0.05 was performed for group comparison between postacupuncture and baseline SPECT. Focally increased CBF was seen in all patients especially in the hypoperfused zone surrounding the ischaemic lesion, the ipsilateral or contralateral sensorimotor area, or both. Normal subjects showed increased rCBF mainly in the parahippocampal gyrus, premotor area, frontal and temporal areas bilaterally and ipsilateral globus pallidus. Acupuncture stimulation after stroke patients appears to activate perilesional or use-dependent reorganised sites and might be a way of looking at brain reorganisation.

Immunological characterization of 130 kDa phospholipase C-beta 4 isozyme in rat cerebellar Purkinje cells.

We have developed a monoclonal antibody, beta4-22-9 that recognizes an epitope on pleckstrin homology (PH) domain (1-136 amino acids) located at the amino terminus of rat 130 kDa phospholipase C-beta4 (PLC-beta4). Tissue distribution of 130 kDa PLC-beta4 was determined with this monoclonal antibody. One hundred and thirty kiloDalton PLC-beta4 was exclusively expressed in the nervous tissues including cerebellum and cerebrum, especially at very high levels in cerebellum. The expression of 130 kDa PLC-beta4 in cerebellum was gradually increased from 5 days after birth to adulthood. In the adult cerebellum, especially high level of 130 kDa PLC-beta4 was localized on the periphery of Purkinje cells in the patch-like pattern. These data implies that 130 kDa PLC-beta4 may a role in cerebellar Purkinje cells.

Intrinsic mutagenicity and electrophilicity of 1-sulfooxy-3-methylcholanthrene: implications for metabolic activation of the carcinogen 3-methylcholanthrene.

Hydroxylation of a meso-anthracenic carbon atom with subsequent formation of a reactive ester bearing a good leaving group (e.g., sulfate) has been proposed as a possible biochemical mechanism responsible for DNA binding, mutagenicity and tumorigenicity of 3-methylcholanthrene, one of the most potent carcinogenic polycyclic aromatic hydrocarbons in experimental animals. In support of this supposition, the chemically synthesized sulfuric acid ester, 1-sulfooxy-3-methylcholanthrene (1-SMC) was directly mutagenic in bacteria and covalently bound to DNA without metabolic activation. The intrinsic mutagenicity of this reactive ester was significantly potentiated by addition of extra acetate or chloride anions to the media. Reduced glutathione and ascorbic acid protected against 1-SMC-induced mutagenesis. These findings suggest 1-SMC as a potential ultimate electrophilic and tumorigenic metabolite of 3-methylcholanthrene.

Bioactivation of 5-hydroxymethyl-2-furaldehyde to an electrophilic and mutagenic allylic sulfuric acid ester.

5-Hydroxymethyl-2-furaldehyde (HMF), a ubiquitous food contaminant, has been proposed to be metabolically activated through sulfonation of its allylic hydroxyl functional group. In support of this idea, we have found the strong direct mutagenicity of chemically synthesized sulfuric acid ester, 5-sulfooxymethylfurfural (SMF), in Salmonella typhimurium TA104. The intrinsic mutagenicity of this reactive ester was significantly inhibited by glutathione and glutathione S-transferase activity in dialyzed rat liver cytosol. The metabolic formation of SMF was elucidated by enhanced mutagenicity of HMF in the presence of rat hepatic cytosol enriched with the sulfo-group donor, 3'-phosphoadenosine-5'-phosphosulfate (PAPS). The PAPS- and cytosol-dependent mutagenicity of HMF was markedly lessened by sulfotransferase inhibitors such as 2,6-dichloro-4-nitrophenol and dehydroepiandrosterone. These results suggest that HMF can be metabolically activated to an allylic sulfuric acid ester which may play a role as an ultimate electrophilic metabolite in toxification of the parent compound in vivo.