Troubleshooting Arterial-Phase MR Images of Gadoxetate Disodium-Enhanced Liver.

Gadoxetate disodium is a widely used magnetic resonance (MR) contrast agent for liver MR imaging, and it provides both dynamic and hepatobiliary phase images. However, acquiring optimal arterial phase images at liver MR using gadoxetate disodium is more challenging than using conventional extracellular MR contrast agent because of the small volume administered, the gadolinium content of the agent, and the common occurrence of transient severe motion. In this article, we identify the challenges in obtaining high-quality arterial-phase images of gadoxetate disodium-enhanced liver MR imaging and present strategies for optimizing arterial-phase imaging based on the thorough review of recent research in this field

The equivocal appendix at CT: prevalence in a control population

The purpose of the study was to determine the prevalence of appendices with an equivocal appearance at computed tomography (CT) in a control population. We retrospectively identified a control population of 150 patients who underwent CT of the abdomen and pelvis for evaluation of hematuria (without abdominal pain, fever, or colonic disease). One reader measured the diameter of the appendix and noted if the appendix was either isodense in appearance or airless and fluid filled. Sixty-seven of 150 cases (44.6%) demonstrated appendiceal diameter greater than 6 mm. The appendix was collapsed or isodense in 34/150 cases (22.7%). Only ten of 150 or 6.6% of cases were isodense in combination with diameter greater than 6 mm, and none had diameter greater than 10 mm. Only one of 150 cases (0.67%) demonstrated airless fluid within the lumen, and the appendix measured less than 6 mm. While the diameter of the normal appendix is frequently greater than 6 mm, none measured greater than 10 mm in combination with ambiguous morphology. Furthermore, in the normal appendix, airless fluid filling the lumen is a rare appearance with a prevalence of less than 1%. While appendicitis could undoubtedly occur in an isodense appendix between 6 and 10 mm in diameter, such an appearance can occur in up to 6.6% of the normal populatio

Adenomatoid tumors of the male and female genital tract are defined by TRAF7 mutations that drive aberrant NF-kB pathway activation.

Adenomatoid tumors are the most common neoplasm of the epididymis, and histologically similar adenomatoid tumors also commonly arise in the uterus and fallopian tube. To investigate the molecular pathogenesis of these tumors, we performed genomic profiling on a cohort of 31 adenomatoid tumors of the male and female genital tracts. We identified that all tumors harbored somatic missense mutations in the TRAF7 gene, which encodes an E3 ubiquitin ligase belonging to the family of tumor necrosis factor receptor-associated factors (TRAFs). These mutations all clustered into one of five recurrent hotspots within the WD40 repeat domains at the C-terminus of the protein. Functional studies in vitro revealed that expression of mutant but not wild-type TRAF7 led to increased phosphorylation of nuclear factor-kappa B (NF-kB) and increased expression of L1 cell adhesion molecule (L1CAM), a marker of NF-kB pathway activation. Immunohistochemistry demonstrated robust L1CAM expression in adenomatoid tumors that was absent in normal mesothelial cells, malignant peritoneal mesotheliomas and multilocular peritoneal inclusion cysts. Together, these studies demonstrate that adenomatoid tumors of the male and female genital tract are genetically defined by TRAF7 mutation that drives aberrant NF-kB pathway activation

Data production models for the CDF experiment

The data production for the CDF experiment is conducted on a large Linux PC farm designed to meet the needs of data collection at a maximum rate of 40 MByte/sec. We present two data production models that exploits advances in computing and communication technology. The first production farm is a centralized system that has achieved a stable data processing rate of approximately 2 TByte per day. The recently upgraded farm is migrated to the SAM (Sequential Access to data via Metadata) data handling system. The software and hardware of the CDF production farms has been successful in providing large computing and data throughput capacity to the experiment.Comment: 8 pages, 9 figures; presented at HPC Asia2005, Beijing, China, Nov 30 - Dec 3, 200

Adult living donor liver imaging

Adult living donor liver transplantation (LDLT) is increasingly used for the treatment of end-stage liver disease. The three most commonly harvested grafts for LDLT are left lateral segment, left lobe, and right lobe grafts. The left lateral segment graft, which includes Couinaud’s segments II and III, is usually used for pediatric recipients or small size recipients. Most of the adult recipients need either a left or a right lobe graft. Whether a left or right lobe graft should be harvested from the donors depends on estimated graft and donor remnant liver volume, as well as biliary and vascular anatomy. Detailed preoperative assessment of the potential donor liver volumetrics, biliary and vascular anatomy, and liver parenchyma is vital to minimize risks to the donors and maximize benefits to the recipients. Computed tomography (CT) and magnetic resonance imaging (MRI) are currently the imaging modalities of choice in the preoperative evaluation of potential donors. This review provides an overview of key surgical considerations in LDLT that the radiologists must be aware of, and imaging findings on CT and MRI that the radiologists must convey to the surgeons when evaluating potential donors for LDLT

Ectopic ureter associated with uterine didelphys and obstructed hemivagina: preoperative diagnosis by MRI

Uterine didelphys with obstructed hemivagina and ipsilateral renal anomalies is a rare congenital malformation of the female urogenital tract. While the urinary anomalies almost always involve renal agenesis, we report a rare case of a 17-year-old girl with the malformation associated with ectopic ureteral insertion into the obstructed hemivagina, which was diagnosed preoperatively by MR imaging. To the best of our knowledge, preoperative MR imaging diagnosis of the ectopic ureter associated with this syndrome has not been previously reported. Accurate preoperative diagnosis of ectopic ureteral insertion associated with this syndrome is important for surgical planning

Tai Chi for Osteopenic Women: Design and Rationale of a Pragmatic Randomized Controlled Trial

Background: Post-menopausal osteopenic women are at increased risk for skeletal fractures. Current osteopenia treatment guidelines include exercise, however, optimal exercise regimens for attenuating bone mineral density (BMD) loss, or for addressing other fracture-related risk factors (e.g. poor balance, decreased muscle strength) are not well-defined. Tai Chi is an increasingly popular weight bearing mind-body exercise that has been reported to positively impact BMD dynamics and improve postural control, however, current evidence is inconclusive. This study will determine the effectiveness of Tai Chi in reducing rates of bone turnover in post-menopausal osteopenic women, compared with standard care, and will preliminarily explore biomechanical processes that might inform how Tai Chi impacts BMD and associated fracture risks. Methods/Design: A total of 86 post-menopausal women, aged 45-70y, T-score of the hip and/or spine -1.0 and -2.5, have been recruited from primary care clinics of a large healthcare system based in Boston. They have been randomized to a group-based 9-month Tai Chi program plus standard care or to standard care only. A unique aspect of this trial is its pragmatic design, which allows participants randomized to Tai Chi to choose from a pre-screened list of community-based Tai Chi programs. Interviewers masked to participants' treatment group assess outcomes at baseline and 3 and 9 months after randomization. Primary outcomes are serum markers of bone resorption (C-terminal cross linking telopeptide of type I collagen), bone formation (osteocalcin), and BMD of the lumbar spine and proximal femur (dual-energy X-ray absorptiometry). Secondary outcomes include health-related quality-of-life, exercise behavior, and psychological well-being. In addition, kinetic and kinematic characterization of gait, standing, and rising from a chair are assessed in subset of participants (n = 16) to explore the feasibility of modeling skeletal mechanical loads and postural control as mediators of fracture risk. Discussion: Results of this study will provide preliminary evidence regarding the value of Tai Chi as an intervention for decreasing fracture risk in osteopenic women. They will also inform the feasibility, value and potential limitations related to the use of pragmatic designs for the study of Tai Chi and related mind-body exercise. If the results are positive, this will help focus future, more in-depth, research on the most promising potential mechanisms of action identified by this study. Trial registration: This trial is registered in Clinical Trials.gov, with the ID number of NCT01039012

Low-loss surface modes and lossy hybrid modes in metamaterial waveguides

We show that waveguides with a dielectric core and a lossy metamaterial cladding (metamaterial-dielectric guides) can support hybrid ordinary-surface modes previously only known for metal-dielectric waveguides. These hybrid modes are potentially useful for frequency filtering applications as sharp changes in field attenuation occur at tailorable frequencies. Our results also show that the surface modes of a metamaterial-dielectric waveguide with comparable electric and magnetic losses can be less lossy than the surface modes of an analogous metal-dielectric waveguide with electric losses alone. Through a characterization of both slab and cylindrical metamaterial-dielectric guides, we find that the surface modes of the cylindrical guides show promise as candidates for all-optical control of low-intensity pulses.Comment: 15 pages, 11 figures. Accepted by Photonics and Nanostructures - Fundamentals and Applications. This version: Title is extended. Section 3 (Modes) and 4 (Characterization) are revised. The abstract, discussion and summary are also revised accordingl

Fetal tracheolaryngeal airway obstruction: prenatal evaluation by sonography and MRI

We reviewed the sonographic and MRI findings of tracheolaryngeal obstruction in the fetus. Conditions that can cause tracheolaryngeal obstruction include extrinsic causes such as lymphatic malformation, cervical teratoma and vascular rings and intrinsic causes such as congenital high airway obstruction syndrome (CHAOS). Accurate distinction of these conditions by sonography or MRI can help facilitate parental counseling and management, including the decision to utilize the ex utero intrapartum treatment (EXIT) procedure

Transmembrane helix dynamics of bacterial chemoreceptors supports a piston model of signalling.

Transmembrane α-helices play a key role in many receptors, transmitting a signal from one side to the other of the lipid bilayer membrane. Bacterial chemoreceptors are one of the best studied such systems, with a wealth of biophysical and mutational data indicating a key role for the TM2 helix in signalling. In particular, aromatic (Trp and Tyr) and basic (Arg) residues help to lock α-helices into a membrane. Mutants in TM2 of E. coli Tar and related chemoreceptors involving these residues implicate changes in helix location and/or orientation in signalling. We have investigated the detailed structural basis of this via high throughput coarse-grained molecular dynamics (CG-MD) of Tar TM2 and its mutants in lipid bilayers. We focus on the position (shift) and orientation (tilt, rotation) of TM2 relative to the bilayer and how these are perturbed in mutants relative to the wildtype. The simulations reveal a clear correlation between small (ca. 1.5 Å) shift in position of TM2 along the bilayer normal and downstream changes in signalling activity. Weaker correlations are seen with helix tilt, and little/none between signalling and helix twist. This analysis of relatively subtle changes was only possible because the high throughput simulation method allowed us to run large (n = 100) ensembles for substantial numbers of different helix sequences, amounting to ca. 2000 simulations in total. Overall, this analysis supports a swinging-piston model of transmembrane signalling by Tar and related chemoreceptors