Ir(CO)-Catalyzed Benzylic C(sp)-H Silylation of 2-Alkylpyridines with Hydrosilanes Leading to 2-(1-Silylalkyl)pyridines.

The iridium-catalyzed C(sp)-H silylation of 2-alkylpyridines with hydrosilanes at the benzylic position to afford 2-(1-silylalkyl)pyridines is described. The low product yield was markedly improved by adding 3,5-dimethylpyridine. Norbornene is also an essential additive for the reaction to proceed as a hydrogen scavenger.

Signal contributions to heavily diffusion-weighted functional magnetic resonance imaging investigated with multi-SE-EPI acquisitions.

Diffusion-weighted (DW) functional magnetic resonance imaging (fMRI) signal changes have been noted as a promising marker of neural activity. Although there is no agreement on the signal origin, the blood oxygen level dependent (BOLD) effect has figured as one of the most likely sources. In order to investigate possible BOLD and non-BOLD contributions to the signal, DW fMRI was performed on normal volunteers using a sequence with two echo-planar acquisitions after pulsed-gradient spin-echo.

Acoustic noise transfer function in clinical MRI a multicenter analysis.

Rationale And Objectives: Acoustic noise both in terms of its magnitude and frequency during magnetic resonance imaging (MRI) scan is influenced by imaging parameters and pulse sequences. It varies because of many different factors such as structure, materials, and magnetic field strength. The purpose of our study is to evaluate the characteristics of acoustic noise independent of MRI scan protocol by measuring a gradient-pulse-to-acoustic-noise transfer function (GPAN-TF) at various MRI scanners.

In vivo hemodynamic analysis of intracranial aneurysms obtained by magnetic resonance fluid dynamics (MRFD) based on time-resolved three-dimensional phase-contrast MRI.

Introduction: Hemodynamics is thought to play a very important role in the initiation, growth, and rupture of intracranial aneurysms. The purpose of our study was to perform in vivo hemodynamic analysis of unruptured intracranial aneurysms of magnetic resonance fluid dynamics using time-resolved three-dimensional phase-contrast MRI (4D-Flow) at 1.5 T and to analyze relationships between hemodynamics and wall shear stress (WSS) and oscillatory shear index (OSI).

Comparison of hemodynamics of intracranial aneurysms between MR fluid dynamics using 3D cine phase-contrast MRI and MR-based computational fluid dynamics.

Introduction: Hemodynamics is thought to play a very important role in the initiation, growth, and rupture of intracranial aneurysms. The purpose of our study was to compare hemodynamics of intracranial aneurysms of MR fluid dynamics (MRFD) using 3D cine PC MR imaging (4D-Flow) at 1.5 T and MR-based computational fluid dynamics (CFD).

A multi-compartmental SE-BOLD interpretation for stimulus-related signal changes in diffusion-weighted functional MRI.

A new interpretation is proposed for stimulus-induced signal changes in diffusion-weighted functional MRI. T(2)-weighted spin-echo echo-planar images were acquired at different diffusion-weightings while visual stimulation was presented to human volunteers. The amplitudes of the positive stimulus-correlated response and post-stimulus undershoot (PSU) in the functional time-courses were found to follow different trends as a function of b-value.

Calibrated magnetic resonance hydrometry to quantify pancreatic juice: a preliminary study.

Purpose: To investigate the effectiveness of the calibrated MR hydrometry (CMRH) method for accurately measuring pancreatic secretion.

Materials And Methods: All studies were performed on a 1.5-T MR system using a fat-suppressed, single-shot half-Fourier fast spin-echo sequence with a standard body coil.

Magnetic resonance elastography to observe deep areas: comparison of external vibration systems.

MRE methods deform the sample using an external vibration system. We have been using a transverse driver, which generates shear waves at the object surface. One of the problems is that shear waves rapidly attenuate at the surface of tissue and do not propagate into the body.

Isotropic diffusion-weighted MR imaging with tetrahedral gradients in the upper abdomen.

A tetrahedral gradient diffusion sequence for body imaging for a 1.5T scanner was implemented, and we compared the quality of images acquired with the new technique and with the conventional orthogonal technique. Image quality was better using the tetrahedral technique in terms of signal homogeneity in the right liver lobe and signal loss artifact in the left lobe, and the technique was considered useful for magnetic resonance imaging in the upper abdomen.

Visualization of hemodynamics in intracranial arteries using time-resolved three-dimensional phase-contrast MRI.

Purpose: To visualize the hemodynamics of the intracranial arteries using time-resolved three-dimensional phase-contrast (PC)-MRI (4D-Flow).

Materials And Methods: MR examinations were performed with a 1.5T MR unit on six healthy volunteers (22-50 years old, average = 30 years).

Double hepatic arterial phase MRI of the liver with switching of reversed centric and centric K-space reordering.

Objective: The purpose of our study was to evaluate the clinical feasibility and usefulness of a 2D spoiled gradient-recalled echo MR sequence with serial switching of reversed centric and centric k-space reordering for high-spatial-resolution gadolinium-enhanced double hepatic arterial phase (HAP) MRI of the liver.

Subjects And Methods: MR images (frequency, 512; phase encoding without interpolation, 224; 6-mm thickness with 1-mm gap; 30 slices per 18 seconds) were obtained with multiphase imaging in which central k-space line data were filled 10, 21, 49, and 181 seconds after arrival of contrast medium in the abdominal aorta for the early HAP (reversed centric reordering, center of k-space lines acquired at end of acquisition), late HAP (centric reordering, center of k-space lines at beginning of acquisition), portal venous phase (centric reordering), and equilibrium phase (centric reordering), respectively, in 102 consecutive patients with suspected liver disease, including 48 untreated hepatocellular carcinomas (HCCs) in 35 patients. Images were quantitatively assessed for degree of contrast enhancement in the abdominal aorta, spleen, portal trunk, liver parenchyma, hepatic veins, and HCCs.

Efficacy of multislice computed tomography for gastroenteric and hepatic surgeries.

Aim: To determine the efficacy of multislice CT for gastroenteric and hepatic surgery.

Methods: Dual-phase helical computed tomography was performed in 50 of 51 patients who underwent gastroenteric and hepatic surgeries. Twenty-eight, eighteen and four patients suffering from colorectal cancer, gastric cancer, and liver cancer respectively underwent colorectal surgery (laparoscopic surgery: 6 cases), gastrectomy, and hepatectomy.

Inhibition of tumor-promoting effects by poricoic acids G and H and other lanostane-type triterpenes and cytotoxic activity of poricoic acids A and G from Poria cocos.

The structures of two novel 3,4-seco-lanostane-type triterpenes isolated from the sclerotium of Poria cocos were established to be 16alpha-hydroxy-3,4-seco-lanosta-4(28),8,24-triene-3,21-dioic acid (1; poricoic acid G) and 16alpha-hydroxy-3,4-seco-24-methyllanosta-4(28),8,24(24(1))-triene-3,21-dioic acid (2; poricoic acid H) on the basis of spectroscopic methods. These two, and eight other known compounds isolated from the sclerotium, poricoic acid B (3), poricoic acid A (4), tumulosic acid (5), dehydrotumulosic acid (6), 3-epidehydrotumulosic acid (7), polyporenic acid C (8), 25-hydroxy-3-epidehydrotumulosic acid (9), and dehydroabietic acid methyl ester (10), showed potent inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Evaluation of the cytotoxicity of compounds 1 and 4 against human cancer cell lines revealed that 1 was significantly cytotoxic to leukemia HL-60 cells [GI(50) (concentration that yields 50% growth) value 39.