Anatomic study of the quadrigeminal cistern in patients with 3-dimensional magnetic resonance cisternography

The aim of this study was to demonstrate the anatomy of the quadrigeminal cistern, define the anatomic landmarks, and measure the extension of the cistern in the living by using magnetic resonance (MR) cisternography with 3-dimensional reconstruction.

Effect of Acute Psychological Stress on Prefrontal GABA Concentration Determined by Proton Magnetic Resonance Spectroscopy

Objective Impaired function of the central gamma-aminobutyric acid (GABA) system, which provides the brain’s major inhibitory pathways, is thought to play an important role in the pathophysiology of anxiety disorders. The effect of acute psychological stress on the human GABA-ergic system is still unknown, however. The purpose of this study was to determine the effect of acute stress on prefrontal GABA levels. Method A recently developed noninvasive magnetic resonance spectroscopy method was used to measure changes in the GABA concentration of the prefrontal cortex in 10 healthy human subjects during a threat-of-shock condition and during a safe condition (two sessions on different days). The main outcome measure was the mean GABA concentration within a 3×3×2-cm3 voxel selected from the medial prefrontal cortex. Results Prefrontal GABA decreased by approximately 18% in the threat-of-shock condition relative to the safe condition. This reduction was specific to GABA, since the concentrations of N-acetyl-aspartate, choline-containing compounds, and glutamate/glutamine levels obtained in the same spectra did not change significantly. Conclusions This result appeared compatible with evidence from preclinical studies in rodents, which showed rapid presynaptic down-regulation of GABA-ergic neurotransmission in response to acute psychological stress. The molecular mechanism and functional significance of this reduced inhibitory effect of acute psychological stress in relation to impaired GABA-ergic function in anxiety disorders merit further investigation.

Repeatability of nerve fiber layer thickness measurements in patients with glaucoma and without glaucoma using spectral-domain and time-domain OCT

The aim of this work is to assess the repeatability of spectral-domain-OCT (SD-OCT) retinal nerve fiber layer thickness (RNFL) thickness measurements in a non-glaucoma group and patients with glaucoma and to compare these results to conventional time-domain-OCT (TD-OCT).

Whole Body Postmortem Magnetic Resonance Angiography

Computed tomography (CT) and magnetic resonance (MR) imaging have become important elements of forensic radiology. Whereas the feasibility and potential of CT angiography have long been explored, postmortem MR angiography (PMMRA) has so far been neglected. We tested the feasibility of PMMRA on four adult human cadavers. Technical quality of PMMRA was assessed relative to postmortem CT angiography (PMCTA), separately for each body region. Intra-aortic contrast volumes were calculated on PMCTA and PMMRA with segmentation software. The results showed that technical quality of PMMRA images was equal to PMCTA in 4/4 cases for the head, the heart, and the chest, and in 3/4 cases for the abdomen, and the pelvis. There was a mean decrease in intra-aortic contrast volume from PMCTA to PMMRA of 46%. PMMRA is technically feasible and allows combining the soft tissue detail provided by MR and the information afforded by angiography.

Comparison of arterial and venous coronary artery bypass flow measurements using 3-T magnetic resonance phase contrast imaging

Comparison of arterial and venous coronary artery bypass flow measurements using 3-T magnetic resonance (MR) phase contrast in correlation with intraoperative Doppler flow measurements.

Morphological and functional 3-Tesla magnetic resonance imaging of saphenous vein coronary artery bypass grafts

Evaluation of a novel non-invasive tool for postoperative follow-up of patients postelective saphenous vein coronary artery bypass graft (CABG) was performed. Ten patients were included. Their bypass grafts supplied the right coronary artery (7), marginal branches (1), diagonal branches (2), and the circumflex artery (n=1). Each bypass was examined intraoperatively using Doppler flow measurement. Patients were examined with a 3-Tesla magnetic resonance imaging (MRI) scanner (MAGNETOM Verio, Siemens, Erlangen, Germany) within one week postsurgery using MR-angiography with an intravasal contrast agent and velocity encoded phase-contrast flow measurements. Intraoperative Doppler flow measurements revealed regular flow patterns in all vascular territories supplied. The median intraoperative flow rate was 50 ml/min with an inter-quartile range (IQR) of 42-70 ml/min. The clinical postoperative course was uneventful. MRI showed all grafts to be patent. The median postoperative flow rate was 50 ml/min (IQR: 32-65 ml/min). MRI flow rates agreed well with intraoperative Doppler flow measurements (mean difference: -2.8±20.1 ml/min). This initial study demonstrates that 3-Tesla MRI flow measurements correlated well with Doppler thus reconfirming the graft patency postCABG. Further refinement and broader application of this technique may facilitate follow-up postCABG potentially replacing empiric clinical judgment by reliable non-invasive imaging.

Diffusion-weighted magnetic resonance imaging detects local recurrence after radical prostatectomy: initial experience

Current conventional cross-sectional imaging techniques, such as contrast-enhanced computed tomography and magnetic resonance imaging (MRI), are largely inaccurate in detecting local recurrence after radical prostatectomy. We report on five patients with biochemical recurrence after radical retropubic prostatectomy and pelvic lymph node dissection for whom local recurrence could only be detected with diffusion-weighted (DW) MRI. Prior to DW-MRI, all patients had negative digital rectal examinations, negative or equivocal conventional cross-sectional imaging, and negative bone scans. All suspicious lesions on DW-MRI imaging were histologically proved to be local recurrences of prostate cancer after either transrectal ultrasound-guided or transurethral biopsy. These results should encourage other centres to test our findings.

Association between cam-type deformities and magnetic resonance imaging-detected structural hip damage: a cross-sectional study in young men

Objective Femoroacetabular impingement may be a risk factor for hip osteoarthritis in men. An underlying hip deformity of the cam type is common in asymptomatic men with nondysplastic hips. This study was undertaken to examine whether hip deformities of the cam type are associated with signs of hip abnormality, including labral lesions and articular cartilage damage, detectable on magnetic resonance imaging (MRI). Methods In this cross-sectional, population-based study in asymptomatic young men, 1,080 subjects underwent clinical examination and completed a self-report questionnaire. Of these subjects, 244 asymptomatic men with a mean age of 19.9 years underwent MRI. All MRIs were read for cam-type deformities, labral lesions, cartilage thickness, and impingement pits. The relationship between cam-type deformities and signs of joint damage were examined using logistic regression models adjusted for age and body mass index. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were determined. Results Sixty-seven definite cam-type deformities were detected. These deformities were associated with labral lesions (adjusted OR 2.77 [95% CI 1.31, 5.87]), impingement pits (adjusted OR 2.9 [95% CI 1.43, 5.93]), and labral deformities (adjusted OR 2.45 [95% CI 1.06, 5.66]). The adjusted mean difference in combined anterosuperior femoral and acetabular cartilage thickness was −0.19 mm (95% CI −0.41, 0.02) lower in those with cam-type deformities compared to those without. Conclusion Our findings indicate that the presence of a cam-type deformity is associated with MRI-detected hip damage in asymptomatic young men.

Characterization of HgCl2 Tridentate Amine Complexes by X-ray Crystallography, NMR and ESI-MS

Two new HgCl2 complexes of tridentate nitrogen ligands were characterized by X-ray crystallography, proton NMR spectroscopy and ESI-MS. The five-coordinate complex [Hg(BMPA)Cl-2] (1) (BMPA = bis(2-pyridylmethyl)amine) crystallized from acetonitrile/m-xylene by slow evaporation in the monoclinic space group P2(1)/n with a = 8.3896(8) , b = 12.8020(13) , c = 13.3526(13) , alpha = 90A degrees, beta A = 90.480(2)A degrees, gamma A = 90A degrees and z = 4. The square pyramidal structure (tau = 0.009) has approximate C (s) symmetry. Despite comparable Hg-N bond lengths in 1, inversion of the central nitrogen was rapid on the chemical shift time scale in dilute solution except at very low temperatures. The related complex [Hg(BEPA)Cl-2] (2) (BEPA = bis(2-{pyrid-2-yl}ethyl)amine) crystallized from acetonitrile/ethyl acetate/hexanes by slow diffusion in the orthorhombic space group Pnma with a = 13.424(3) , b = 14.854(3) , c = 8.118(2) , alpha = 90A degrees, beta A = 90A degrees, gamma A = 90A degrees and z = 4. The mixed geometry structure (tau = 0.56) also has crystallographic mirror symmetry as well as C (s) point group symmetry. In dilute acetonitrile solution, 1 was stable while 2 slowly converted to a more thermodynamically stable complex.

Effect of Pulse Depletion in a Brillouin Optical Time-Domain Analysis System

Energy transfer between the interacting waves in a distributed Brillouin sensor can result in a distorted measurement of the local Brillouin gain spectrum, leading to systematic errors. It is demonstrated that this depletion effect can be precisely modelled. This has been validated by experimental tests in an excellent quantitative agreement. Strict guidelines can be enunciated from the model to make the impact of depletion negligible, for any type and any length of fiber. (C) 2013 Optical Society of America

Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) in Femoacetabular impingement

Femoroacetabular impingement is a well-described pre-arthritic condition with two main types; cam and pincer. Studies using the open treatment for impingement have described patterns of articular cartilage wear specific to cam and pincer impingement. Assessing articular damage in the hip joint is an important component of treatment. Intravenous gadolidium allows radiologists to perform an indirect assessment of articular cartilage glycosaminoglycan (GAG) content by using a technique called dGEMRIC. Using this indirect assessment of articular cartilage, we compared the dGEMRIC indices in a group of six cam and seven pincer patients to a control group (n = 12) of asymptomatic controls that had no plain MRI findings of osteoarthritis. The superior portion of the hip joint was divided into seven regions from 9 to 3 o'clock. These regions were then subdivided into peripheral and central regions. The cam and pincer groups both had statistically lower dGEMRIC values compared to the control group. The cam group demonstrated not only peripheral but also central involvement of the joint and this was concentrated in the anterior portion of the joint. The pincer group exhibited more global hip involvement with all areas of the hip averaging a dGEMRIC index 28% less than controls. With the use of dGEMRIC more specific patterns of cartilage wear can be elicited in patients with impingement, which may improve patient selection and help better understand the progression of osteoarthithis throughout the hip joint.