Slice selection axis motion artifact correction in MRI

In magnetic resonance imaging using two-dimensional Fourier transform techniques, motion causes ghosting in the phase-encoded direction and loss of image resolution. Although numerous techniques have been proposed to suppress these motion artifacts, they are a continuing problem. In this paper a new technique is presented to reduce the artifact from motion along the slice selection axis. It is shown that such motion causes an amplitude modulation of the data, and an iterative algorithm is developed to reduce this modulation by post-processing the data using signal processing techniques. The algorithm is tested on simulated data, and shown to perform well, even with significant levels of noise added to the data.

Histopathological and ultrastructural changes of lichen sclerosus et atrophicus on the vulva

Studies of 82 skin specimens from 81 cases of lichen sclerosus et atrophicus (LSA) are reported. Typical LSA pathological changes showed atrophy of the epidermis, hydropic degeneration at the basal layer, and homogenization of the collagen fibers in the superficial dermis with inflammatory cell infiltration underneath. Ultrastructural changes showed intercellular spaces enlarged, particularly near basal cells. Some mitochondria were swollen and rough endoplasmic reticula were enlarged. Some basement membranes were thinner, collagen fibers of varying diameters were arranged in irregular shapes and the fine structures had become unclear and had sometimes even disappeared.

A clinically viable technique of fat suppression for abdomen and pelvis

Chemical-shift selective imaging with an improved selective presaturation pulse can be used to suppress the fat signal uniformly across the entire abdominal cavity. The required magnetic field homogeneity is no higher than for a routine diagnostic scan. Therefore, no extra setup time for shimming is needed. The technique has been implemented on our clinical system for routine fat suppression scans.

Comparative study of affective disorders in three Asian countries. II. Differences in prevalence rates and symptom presentation

This study used standardized diagnostic criteria and method to investigate both prevalence rates and nature of symptoms of depressive disorders in three Asian centres--Nagasaki, Shanghai and Seoul. Of the patients who visited a psychiatric clinic in each of the 3 centres for the first time, over 20% suffered from depression. Unlike previous reported prevalence rates for Asian countries, these results suggest that rates in Asia may not be much lower than those reported in Western countries. Although prevalence rates of depression were similar in all 3 centres, differences in symptoms were noted.

Treatment of small cell lung cancer

During a 28-year period, 110 patients with small cell lung cancer were treated at our hospital. Fifty-nine patients received surgery, and 58 patients (including 7 cases after exploratory thoracotomy) received chemotherapy and/or radiotherapy. The 5-year survival rate of the surgically treated group was 17%, while none in the non-surgical group survived for more than 5 years.

A clinical and laboratory study of ciclopirox olamine (8% Batrafen) in the treatment of onychomycosis

Ciclopirox olamine, a new synthetic substituted pyridone derivative, is an antimycotic agent with activity against a broad spectrum of pathogenic and nonpathogenic fungi. The clinical efficacy and safety of 8% ciclopirox olamine nail liquor were evaluated in 100 cases with finger (or great toe) onychomycosis. After 16 weeks and 24 weeks of treatment for finger and great toe onychomycosis, respectively, the overall therapeutic results were excellent in 36 cases, good in 17, fair in 24, and poor in 23. The period of treatment was extended in 31 cases; among them, 10 cases showed further improvement. As for in vitro inhibitory activity, the MIC of ciclopirox olamine against T. rubrum and C. albicans was 1 to 4 mg/L and 1 to 16 mg/L, respectively. This study indicates that 8% ciclopirox olamine nail liquor, with its satisfactory efficacy and lack of side effects, is a good remedy for onychomycosis.

Disruption of cysteine-rich repeats of the p75 nerve growth factor receptor leads to loss of ligand binding

Nerve growth factor (NGF) binds to a low affinity cell surface receptor (p75NGFR) which contains four extracellular repeats, rich in cysteine residues and negatively charged. We have made mutations in the receptor cDNA by inserting linkers in specific domains of the receptor. Nearly all the mutations caused a change in the predicted charge, and resulted in either an insertion or deletion in the primary sequence. Stably transfected fibroblasts were assayed for NGF binding by affinity cross-linking with 125I-NGF. Appropriate expression of the mutated receptors was monitored by rosetting with monoclonal antibodies and by metabolic labeling followed by immunoprecipitation. Although the mutant receptors were recognized by monoclonal antibodies, insertions and deletions in the third and fourth cysteine-rich regions of the receptor had a detrimental effect upon NGF binding. Insertions made outside the cysteine-rich region or in the cytoplasmic domain did not inhibit the ability of 125I-NGF to bind to the receptor, as assessed by affinity cross-linking. A chimeric human-rat NGF receptor transfected into fibroblasts indicates that NGF binding and monoclonal antibody recognition sites are separated but contained within the four cysteine repeats.

Mcm2 and Mcm3, two proteins important for ARS activity, are related in structure and function

MCM2 and MCM3 are essential genes believed to play important roles in the initiation of DNA replication in Saccharomyces cerevisiae. Mutants defective in Mcm2 or Mcm3 are remarkably similar in phenotype. They both show an autonomously replicating sequence (ARS)-specific minichromosome maintenance defect, although their ARS specificities are not identical. In addition, these mutants exhibit a premitotic cell cycle arrest and an increase in chromosome loss and recombination. Genetic studies suggest that the two MCM gene products play interacting or complementary roles in DNA replication. Double mutants of mcm2-1 and mcm3-1 are inviable at the permissive growth temperature (23 degrees C) for each of the single mutants. Furthermore, overproduction of Mcm3 accentuates the deleterious effect of the mcm2-1 mutation, whereas overproduction of Mcm2 partially complements the mcm3-1 mutation. MCM2 encodes a protein of 890 amino acids containing a putative zinc-finger domain that is essential for Mcm2 function. Mcm2 shows striking homology to Mcm3 and three other proteins, Cdc46 of S. cerevisiae, and Nda4 and Cdc21 of Schizosaccharomyces pombe. The phenotypes of mutants defective in these proteins suggest that they belong to a protein family involved in the early steps of DNA replication.

[Pathological observation of experimental asbestosis treated by hydroxy piperquin phosphate in dogs]

The paper presents experimental asbestosis treated with hydroxy piperquin phosphate (HPQP) in dogs. Results showed that the total cell number of bronchoalveolar lavage fluid, the viability of alveolar macrophages and the enzyme activities of lactate dehydrogenase, acid phosphatase and beta-glucuronidase of alveolar macrophages in treated dogs were higher than those in exposed dogs, asbestos fibers contents in the lungs and the mean scores of lung lesions in the treated dogs were markedly less than those in the exposed dogs. These findings support that HPQP may play a role in protecting alveolar macrophages from damage and inhibiting the progression of lung fibrosis, and that the clinical application of HPQP is somehow evidenced by this study.

Chimeric NGF-EGF receptors define domains responsible for neuronal differentiation

To determine the domains of the low-affinity nerve growth factor (NGF) receptor required for appropriate signal transduction, a series of hybrid receptors were constructed that consisted of the extracellular ligand-binding domain of the human epidermal growth factor (EGF) receptor (EGFR) fused to the transmembrane and cytoplasmic domains of the human low-affinity NGF receptor (NGFR). Transfection of these chimeric receptors into rat pheochromocytoma PC12 cells resulted in appropriate cell surface expression. Biological activity mediated by the EGF-NGF chimeric receptor was assayed by the induction of neurite outgrowth in response to EGF in stably transfected cells. Furthermore, the chimeric receptor mediated nuclear signaling, as evidenced by the specific induction of transin messenger RNA, an NGF-responsive gene. Neurite outgrowth was not observed with chimeric receptors that contained the transmembrane domain from the EGFR, suggesting that the membrane-spanning region and cytoplasmic domain of the low-affinity NGFR are necessary for signal transduction.

Image reconstruction from Fourier domain data sampled along a zig-zag trajectory

When the conventional Fourier transform (FT) algorithm is applied to reconstruct a magnetic resonance (MR) image from data sampled along a zig-zag trajectory in the Fourier space, the nonuniform sampling in the spatial frequency direction may give rise to artifacts. In this paper the nature of the artifacts is analyzed and an alternative reconstruction algorithm is developed to produce artifact-free images. Methods for reducing noise level in the reconstructed image are discussed. Our approach is compared with another method based on the interlace sampling theorem.

Motion artifact correction in MRI using generalized projections

An algorithm that suppresses translational motion artifacts in magnetic resonance imaging (MRI) by using post processing on a standard spin-warp image is presented. It is shown that translational motion causes an additional phase factor in the detected signal and that this phase error can be removed using an iterative algorithm of generalized projections. The method has been tested using computer simulations and it successfully removed most of the artifact. The algorithm converges even in the presence of severe noise.

An improved algorithm for 2-D translational motion artifact correction

The quality of magnetic resonance imaging systems has improved to the point that motion is a major limitation in many examinations. Translational motion in the imaging plane causes the phase of the data to be corrupted. An algorithm using computer post-processing is proposed to correct the phase of the data, and hence remove the artifact. This algorithm has superior convergence properties to an earlier algorithm, which is achieved by incorporating additional prior information specific to the situation. The algorithm is verified using a Shepp and Logan phantom with simulated motion in the imaging plane. It is shown that the algorithm can correct both periodic and random motion, and that the algorithm is not significantly degraded when noise is present.

Noise reduction in MR echo planar image reconstruction

It is shown that the noise level in EPI (echo planar imaging) can increase very significantly if the final image is deconvolved to remove the ghost artifacts. This noise amplification is caused by divisions of small numbers, which scale the noise variance up. The scaling factor is a function of the frequency variable in the uniform sampling direction, and is small for low-frequency components and large for high-frequency components. A window function to provide an inverse scaling of data so that the noise scaling factor is canceled exactly is proposed. Since the signal energy is concentrated in the low-frequency range, it is not reduced significantly when windowing is applied. The window function is compared to the commonly used Hamming window and is shown to have good frequency response. The algorithm has been tested with computer simulations and has been verified to be able to raise the signal-to-noise ratio by 50% in the final image.

An algorithm for the suppression of translational motion artifacts in MRI

The quality of Magnetic Resonance imaging systems has improved to the point that the motion is the most important limitation in many examinations. Gross movements of the patient cause a ghost artifact in the image which can interfere with the diagnosis. In this paper a new method is presented to suppress the translational motion artifact caused by gross movements. The method uses postprocessing on a standard two-dimensional Fourier transform image. It is shown that translational motion causes an additional phase factor in the detected signal and that this phase error can be removed using an iterative algorithm of generalised projections. The method has been tested using computer simulations and successfully removed most of the artifact, even in the presence of noise.

The relation of low frequency restoration methods to the Gerchberg-Papoulis algorithm

In magnetic resonance imaging, low frequency components can be allowed to saturate the analog to digital converter to reduce the quantization noise. These components can be estimated using least squares error estimation based low frequency restoration methods or the iterative Gerchberg-Papoulis algorithm. In this paper, we show the relationship between the closed form estimation methods and the iterative algorithm, propose a method for improving the speed of iteration, and discuss the advantages and disadvantages of two types of methods.

Purification, characterization, and localization of linamarase in cassava

We have purified cassava (Manihot esculenta) linamarase to apparent homogeneity using a simplified extraction procedure using low pH phosphate buffer. Three isozymes of cassava linamarase were identified in leaves based on differences in isoelectric point. The enzyme is capable of hydrolyzing a number of beta-glycosides in addition to linamarin. The enzyme is unusually stable and has a temperature optimum of 55 degrees C. Immunogold labeling studies indicate that linamarase is localized in the cell walls of cassava leaf tissue. Since linamarin must cross the cell wall following synthesis in the leaf for transport to the root, it is likely that linamarin must cross the cell wall in a nonhydrolyzable form, possibly as the diglucoside, linustatin. In addition, we have quantified the levels of linamarin and linamarase activity in leaves of cassava varieties which differ in the linamarin content of their roots. We observed no substantial differences in the steady state linamarin content or linamarase activity of leaves from high or low (root) cyanogenic varieties. These results indicate that the steady state levels of linamarin and linamarase in leaves of high and low cyanogenic varieties are not correlated with the varietal differences in the steady state levels of linamarin in roots.

[Preparation of monoclonal antibodies against Trichinella spiralis and localization of antigens]

BALB/c mice were infected per os with the infective larvae (L1) of Trichinella spiralis, and challenged by injecting 0.2ml soluble L1 antigen 3 days before cell fusion. SP2/0 myeloma and immune spleen cells were fused at the ratio of 1:5 in the presence 30%PEG (MW 4,000). The fusion rate and antibody positive rate were 92.1% and 16.6% respectively using ELISA. Among these the chromosomes of 4 strains were 2n greater than 100 and that of the SP2/0 myeloma cells 2n less than or equal to 70. The titer of McAb in the ascites was found to be 1/640 or 1/1,280. Eight strains were of IgG1, 1 IgG2a and 3 IgM in an agar system. Three strains of McAbs, which could recognize specifically the L1 antigen fractions by immuno-blotting technique, were used as probes to localize the target antigens in sections of T. spiralis L1. Staining was performed using an indirect technique consisting of goat anti-mouse IgG-conjugated horseradish peroxidase on de-paraffin sections, and substrate DAB. The results revealed that the antigens reacted most strongly with the specific McAbs were located in the cuticle and stichosome, followed by the lining of gut. Among the 3 strains of McAbs used, 2E5F11A5 reacted most strongly with the antigen, followed by 2E5E9E4. 2E5E9G5 was the weakest.