Threshold contrast detail detectability measurement of the fluoroscopic image quality of a dynamic solid-state digital x-ray image detector

Solid-state digital x-ray imaging detectors of flat-panel construction will play an increasingly important role in future medical imaging facilities. Solid-state detectors that will support both dynamic (including fluoroscopic) and radiographic image recording are under active development. The image quality of an experimental solid-state digital x-ray image detector operating in a continuous fluoroscopy mode has been investigated. The threshold contrast detail detectability (TCDD) technique was used to compare the fluoroscopic imaging performance of an experimental dynamic solid-state digital x-ray image detector with that of a reference image intensifier television (IITV) fluoroscopy system. The reference system incorporated Plumbicon TV. Results were presented as a threshold detection index, or H(T)(A), curves. Measurements were made over a range of mean entrance air kerma (EAK) rates typically used in conventional IITV fluoroscopy. At the upper and mid EAK rate range (440 and 220 nGy/s) the solid-state detector outperformed the reference IITV fluoroscopy system as measured by TCDD performance. At the lowest measured EAK rate (104 nGy/s), the solid-state detector produces slightly inferior TCDD performance compared with the reference system. Although not statistically significant at this EAK rate, the difference will increase as EAK is lowered further. Overall the TCDD results and early clinical experiences support the proposition that a current design of dynamic solid-state detector produces image quality competitive with that of modern IITV fluoroscopy systems. These findings encourage the development of compact and versatile universal x-ray imaging systems based upon solid-state detector technology to support R & F and vascular/interventional applications.

A close-up look at Io from Galileo's near-infrared mapping spectrometer

Infrared spectral images of Jupiter's volcanic moon Io, acquired during the October and November 1999 and February 2000 flybys of the Galileo spacecraft, were used to study the thermal structure and sulfur dioxide distribution of active volcanoes. Loki Patera, the solar system's most powerful known volcano, exhibits large expanses of dark, cooling lava on its caldera floor. Prometheus, the site of long-lived plume activity, has two major areas of thermal emission, which support ideas of plume migration. Sulfur dioxide deposits were mapped at local scales and show a more complex relationship to surface colors than previously thought, indicating the presence of other sulfur compounds.

Functional overlap between the mec-8 gene and five sym genes in Caenorhabditis elegans

Earlier work showed that the Caenorhabditis elegans gene mec-8 encodes a regulator of alternative RNA splicing and that mec-8 null mutants have defects in sensory neurons and body muscle attachment but are generally viable and fertile. We have used a genetic screen to identify five mutations in four genes, sym-1-sym-4, that are synthetically lethal with mec-8 loss-of-function mutations. The phenotypes of sym single mutants are essentially wild type. mec-8; sym-1 embryos arrest during embryonic elongation and exhibit defects in the attachment of body muscle to extracellular cuticle. sym-1 can encode a protein containing a signal sequence and 15 contiguous leucine-rich repeats. A fusion of sym-1 and the gene for green fluorescent protein rescued the synthetic lethality of mec-8; sym-1 mutants; the fusion protein was secreted from the apical hypodermal surface of the embryo. We propose that SYM-1 helps to attach body muscle to the extracellular cuticle and that another gene that is dependent upon mec-8 for pre-mRNA processing overlaps functionally with sym-1. RNA-mediated interference experiments indicated that a close relative of sym-1 functionally overlaps both sym-1 and mec-8 in affecting muscle attachment. sym-2, sym-3, and sym-4 appear to provide additional functions that are essential in the absence of mec-8(+).

Estimation of injecting drug users in the City of Edinburgh, Scotland, and number infected with human immunodeficiency virus

OBJECTIVES

To estimate (1) the number of current and former injecting drug users (IDU) infected with human immunodeficiency virus (HIV) alive in Edinburgh, and (2) the total number of current injectors in the city.

METHODS

The number of infected IDU was estimated using a local register of HIV infections with correction for incompleteness of the register. The number of injectors was estimated by two independent methods, one based on the HIV register, the other by log-linear modelling of four lists of IDU interviewed in a city-wide survey, and/or attending drug treatment agencies and family doctors because of drug use.

MAIN OUTCOME MEASURES

Estimates for the period 1992-1994 of number of IDU infected with HIV, total number of IDU, and prevalence of injecting.

RESULTS

The HIV register indicated that 371 infected drug users who had ever injected were alive and resident in Edinburgh. In all, 95% of infected survey respondents appeared in the register, leading to a corrected estimate of 472 infected ever injectors. From this the number of IDU currently injecting (i.e. in the previous 6 months) was estimated to be 1770 (95% CI: 1340-2240), and the prevalence of injecting as 8.0 (95% CI: 4.8-10.8) per 1000 Edinburgh residents aged 15-59 years. Log-linear modelling gave an estimate of 2070 (95% CI: 1360-2800) current injectors.

CONCLUSIONS

The number of HIV-infected IDU in Edinburgh was estimated to be twice that in the larger nearby city of Glasgow, where a higher proportion of young adults currently injected drugs. Knowledge of the high prevalence of HIV in Edinburgh IDU (19.3%), the prescribing of oral substitutes, and counselling by doctors and drug workers are perceived reasons for the reduction in the prevalence of injecting which has occurred in Edinburgh in recent years. Such measures need to be continued to encourage further reduction of injecting.

Technical report: Initial experiences with an experimental solid-state universal digital X-ray image detector

This paper presents a brief technical evaluation and first review of clinical experiences with an experimental direct digital X-ray image detector designed to support both dynamic and snap-shot imaging. Derivatives of this type of image detector can potentially fulfil the majority of the fluoroscopic and radiographic imaging requirements of clinical radiology departments, and initial results suggest that imaging systems using the new technology will provide a high quality dose-efficient solution to the search for a universal digital X-ray image detector.

A comparison of the physical imaging properties of Fuji ST-V, ST-VA, and ST-VN computed radiography image plates

The physical imaging performance of ST-V, ST-VA, and ST-VN computed radiography image plates, read with a Philips AC3 acquisition system, was investigated at 70 kVp with 0.5 mm of copper beam filtration for four different entrance air kerma values: 0.5, 2.6, 26, and 260 micro Gy. Measurements included characteristic response, presampling-modulation transfer function, and Wiener spectrum analysis for (18 x 24) cm2 image plates, sampled at 10 pixels/mm. These results were used to calculate DQE spectral descriptions of system performance. ST-VN image plates exhibited a slightly superior DQE performance for the two lower entrance air kerma values investigated.

High-temperature silicate volcanism on Jupiter's moon Io

Infrared wavelength observations of Io by the Galileo spacecraft show that at least 12 different vents are erupting lavas that are probably hotter than the highest temperature basaltic eruptions on Earth today. In at least one case, the eruption near Pillan Patera, two independent instruments on Galileo show that the lava temperature must have exceeded 1700 kelvin and may have reached 2000 kelvin. The most likely explanation is that these lavas are ultramafic (magnesium-rich) silicates, and this idea is supported by the tentative identification of magnesium-rich orthopyroxene in lava flows associated with these high-temperature hot spots.

Scar quality from partial or complete wound closure using the Cincinnati incision for clubfoot surgery

The method of skin closure in using the Cincinnati incision for clubfoot surgery may influence the quality of the scar obtained and the postoperative outcome. We retrospectively reviewed two groups of patients who underwent either primary skin closure (14 feet in 11 patients) or partial wound closure and healing by secondary intention (15 feet in 11 patients). The quality of the scars from both of these methods were equally acceptable cosmetically, and neither technique predisposed the patient to any long-term wound complications. In addition, we noted that closing the skin may act as a soft tissue tether, and that the initial position of the postoperative splinting of the foot may influence the surgical outcome. Both of these factors may contribute to the recurrence of equinovarus deformity.

Reporting requirements for skeletal digital radiography: comparison of soft-copy and hard-copy presentation

PURPOSE

To assess diagnostic performance and reader preference when reporting results from digital hard-copy and two soft-copy formats of skeletal digital radiography.

MATERIALS AND METHODS

The data comprised hand radiographs of patients undergoing renal dialysis. Normal hand radiographs obtained in trauma patients were assessed as control images. One hundred fifteen images acquired with a photostimulable-phosphor computed radiography system were analyzed. Image selection and initial assessment were by consensus of two experienced radiologists, who graded the radiographic changes of hyperparathyroidism with the Ritz scoring system. The images were then presented to four readers in three formats: hard-copy output and soft-copy presentations at 2K2 and 1K2 resolutions. These readers scored pathologic change and image preference. The results were analyzed with the receiver operating characteristic technique.

RESULTS

There was a significant improvement in diagnostic performance for both soft-copy formats relative to the hard-copy format (P < .001). No significant difference in diagnostic performance was found between the two soft-copy formats. There was a significant preference for both soft-copy formats relative to the hard-copy format (P < .01), with the 2K2 soft-copy images preferred to the 1K2 images (P < .01).

CONCLUSION

Soft-copy reporting can provide superior diagnostic performance even for images viewed at a modest (1K2) resolution. The lack of difference between the two soft-copy formats has important economic implications with respect to departmental hardware requirements.

Meningismus, fever and macular rash as presenting features of the primary antiphospholipid syndrome?

We report here, we believe for the first time, the primary antiphospholipid syndrome, presenting with fever, meningismus and skin rash. Serology was positive for antiphospholipid antibodies but negative for antinuclear factor. Such presentations, once meningitis has been excluded, should be screened for antiphospholipid antibodies. If serology proves to be positive, anticoagulation for life should be considered to avoid thrombotic episodes and death due to pulmonary embolism.

Autonomic function in a cohort of children with diabetes

129 diabetic children in Avon County participated in a longitudinal study of the evolution of microvascular disease together with 129 age- and sex-matched controls. Diabetic children had mean (+/- SD) age 12.7 (+/- 3.4) years (range: 3.7-16.8), mean (+/- SD) diabetes duration 3.9 (+/- 3.2) years (range: 0.1-13.4) and mean (+/- SD) HbA1 11.1% (+/- 2.2) (range: 6.5-18.2). Cardiovascular autonomic function was studied by four heart rate (HR) tests using a computerized system of HR monitoring. As a group, diabetic children had higher mean HR (p = 0.0004) and reduced max/min HR ratio while standing (p = 0.001), compared with the control children. HR ratio while standing was the only variable related to diabetes duration (r = -0.20, p = 0.018), while no correlation of HR variables with glycaemic control was found. Twenty diabetic children (15.5%) had one abnormal HR test. Ten diabetic children (7.7%) demonstrated abnormality in two or more HR tests. When compared with the other diabetic children in the cohort, these ten children were found to be younger in age (mean age: 9.4 vs 12.0 yr, p = 0.05), but did not otherwise differ in terms of diabetes duration or glycaemic control. No pubertal or sex effect in the development of diabetic autonomic neuropathy was detected. These findings suggest that autonomic function may be impaired early in childhood diabetes, independent of the duration of the disease or the quality of glycaemic control.

Fatal association between dieldrin-resistant and susceptible Australian sheep blowflies,Lucilia cuprina

A novel phenomenon of interactions between genotypes of the dieldrin-resistance (Rdl) locus of the Australian sheep blowfly (Lucilia cuprina) is described. Susceptible adult flies exposed to dieldrin-resistant (Rdl/Rdl or Rdl/S) adults, raised from larvae grown on media containing sublethal concentrations of dieldrin, display mortality related to the concentration on which the resistant flies developed. The resistant flies excrete quantities of dieldrin that are toxic to susceptible flies. These observations provide an additional mechanism to those previously identified for the rapid evolution of resistance to dieldrin by L. cuprina.

Gender differences in HIV risk behaviour of injecting drug users in Edinburgh

A multi-site sample of currently-injecting drug users (IDUs) comprising 344 men and 136 women was recruited in Edinburgh. Sixty-seven per cent of the sample said they had at some time used injecting equipment already used by another person and 25% admitted doing so in the 6 months before interview. Whereas women who injected with used equipment obtained it predominantly from a sexual partner, for men the source was more often a close friend or someone whose HIV status they were unlikely to know. In the 6 months before interview, 40% of men, compared with 20% of women, had more than one heterosexual partner. This difference was associated with a higher proportion of men with steady partners also having casual partners. Women IDUs were more likely to have regular partners who injected (57% vs 26%). Though sharing of injecting equipment has already diminished in Edinburgh, further measures are needed to eliminate it. For injectors here, the risk of infection from unprotected heterosexual intercourse may now be greater than that from sharing injecting equipment, particularly for women. Other methods of encouraging changes in sexual behaviour need to be investigated and successful ones promoted.

Asymmetry--where evolutionary and developmental genetics meet

The mechanisms responsible for the fine tuning of development, where the wildtype phenotype is reproduced with high fidelity, are not well understood. The difficulty in approaching this problem is the identification of mutant phenotypes indicative of a defect in these fine-tuning control mechanisms. Evolutionary biologists have used asymmetry as a measure of developmental homeostasis. The rationale for this was that, since the same genome controls the development of the left and right sides of a bilaterally symmetrical organism, departures from symmetry can be used to measure genetic or environmental perturbations. This paper examines the relationship between asymmetry and resistance to organophosphorous insecticides in the Australian sheep blowfly, Lucilia cuprina. A resistance gene, Rop-1, which encodes a carboxylesterase enzyme, also confers a significant increase in asymmetry. Continued exposure of resistant populations to insecticide has selected a dominant suppressor of the asymmetry phenotype. Genetic evidence indicates that the modifier is the L. cuprina Notch homologue.

Genetic analysis of the lozenge gene complex in Drosophila melanogaster: adult visual system phenotypes

Mutations at the lozenge (lz) locus are pleiotropic, primarily affecting the sense organs for sight, smell and taste. To better understand the role that lz plays in the visual system, we investigated its complex genetics and the effect mutations have on the structure of the compound eye. Complementation analysis within the lz locus reveals two functional units necessary for a normal eye, cistrons A and B. Previous recombination studies identified four subloci spanning 0.14 m.u. Cistron A mutations map to the distal-most spectacle sub-locus, which has been identified as an insertion point for P-elements. Southern blotting and chromosomal in situ hybridization show that P-allele lzmu2 contains a single P-element; a cosmid clone derived from lzmu2 confirms that the P-element is defective. Mutants of both cistrons perturb lens structure and eye pigmentation. However, the extent of the defects differs between the most severe mutations of the two cistrons. Within the eye, failure to form the fenestrated membrane permits photoreceptor neurons to "fall" into the brain disrupting neural structure. Our analysis shows that lz exerts control over the identity of cone cells, pigment cells and photoreceptor neurons.

Scalloped wings is the Lucilia cuprina Notch homologue and a candidate for the modifier of fitness and asymmetry of diazinon resistance

The Scalloped wings (Scl) gene of the Australian sheep blowfly, Lucilia cuprina, is shown to be the homologue of the Drosophila melanogaster Notch gene by comparison at the DNA sequence and genetic levels. A L. cuprina genomic fragment, which shows strong identity with the Notch (N) gene at the molecular level, hybridizes to the location of the Scl gene on polytene chromosomes. The two genes are functionally homologous; the dominant and recessive Notch-like phenotypes produced by mutations in the Scl gene allow these alleles to be classed as N-like or Abruptex-like. The Scl gene is under investigation as a candidate for the fitness and asymmetry Modifier (M) of diazinon resistance. We show that M affects the penetrance of wing and bristle phenotypes associated with two Scl alleles in a manner consistent with the M being an allele of Scl. In addition, we report a phenotypic interaction between the diazinon-resistance mutation, Rop-1, and the same alleles of Scl. We propose that the product of Rop-1, an esterase, may be involved in cell adhesion in developmental processes involving the Scl gene product.

Constrictive pericarditis in B cell chronic lymphatic leukaemia

We report a case of B-cell chronic lymphatic leukaemia (B-CLL) complicated by constrictive pericarditis. The pericardial involvement was confirmed histologically to be leukaemic in nature. We draw attention to this complication which is amenable to surgical correction. To our knowledge this has been described only once before as an autopsy finding and has not been encountered ante-mortem.

How valuable are IgA and IgM anti-HIV tests for the diagnosis of mother-child transmission of HIV in an African setting?

BACKGROUND

Babies born to HIV-infected mothers retain anti-HIV of maternal origin until 15-18 months of age. Because of this, HIV proviral DNA and p24 antigen measurements have become the methods of choice for timely diagnosis of HIV infection in infancy. They are, however, too expensive for widespread use in the developing world.

OBJECTIVE

To evaluate a simple, inexpensive serological method for diagnosing mother-child transmission of HIV, in an African population, which takes account of the effects of placental transfer of maternal antibody and continued exposure to HIV through breast-feeding.

STUDY DESIGN

Plasma specimens for a prospective study of mother-to-infant transmission of HIV in rural Zaire were collected at birth, 3, 6, 9, 12, 18 and 24 months from 21 infected infants (PP group), 21 uninfected infants (PN group) born to seropositive mothers and 21 control infants (NN group) born to uninfected mothers. The specimens were retrospectively tested for IgG, IgM and IgA anti-HIV by immunoglobulin class-specific capture EIAs, and by a commercial anti-HIV EIA.

RESULTS

In neonatal specimens, IgA and IgM anti-HIV were present, respectively, in 13 of 14 (97%) and 8 of 14 (57%) of the PP group and in 6 of 11 (55%) and 2 of 11 (18%) of the PN group. Later, at 3 months and older, IgA and IgM anti-HIV were only detected in the PP group. They peaked at 18 months (93%) and 24 months (67%) respectively. Of the 21 PP group children, 8 (38%) were transiently IgG anti-HIV-negative in the first year, indicating that infection had probably taken place after birth; four of the 8 had no detectable IgA anti-HIV during the first year. None of the specimens collected from the NN group babies were reactive for IgA, IgM or IgG anti-HIV.

CONCLUSIONS

IgA and IgM anti-HIV may be passively transferred across the placenta. Where breast-feeding is prevalent, about half of the transmissions may occur after birth, thus delaying the diagnosis of mother-child transmission. Nevertheless, this simple, cheap IgA anti-HIV, EIA identified 65% of transmissions by 9 months of age, and 93% at 18 months of age. It is a more useful marker than IgM anti-HIV, and gave a much more rapid answer than did tests for IgG anti-HIV seroreversion.

Effect of L-NMMA, cromakalim, and glibenclamide on cerebral blood flow in hypercapnia and hypoxia

Sulfonylureas reduce cerebral blood flow (CBF) during hypoxia but not during hypercapnia, whereas blockers of nitric oxide (NO) synthesis reduce hypercapnic CBF. However, the effect of NO blockers on hypoxic CBF is uncertain. CBF was measured in the cortex of 51 enflurane-anesthetized rats by the hydrogen clearance technique during eucapnia, hypercapnia (arterial PCO2 65 Torr), and hypoxia (arterial PO2 40 Torr). CBF increased twofold in both hypercapnia and hypoxia from eucapnia. Intracortical (ic) NG-monomethyl-L-arginine (L-NMMA, 100 microM-5 mM) attenuated both the hypercapnic and hypoxic dilations by 60-70%, and L-arginine (300 mg/kg iv) partially reversed these effects. Glibenclamide (10 microM ic) and L-NMMA gave no further attenuation of the hypoxic dilation than L-NMMA alone. Cromakalim (10 microM, ic) increased CBF in eucapnia, but this was not seen in the presence of glibenclamide. The adenosine antagonist 8-phenyl-theophylline did not attenuate the hypoxic dilation. This suggests that NO synthesis plays a major role in the regulation of CBF in hypercapnia and hypoxia. But the combined effects of glibenclamide and L-NMMA do not further attenuate CBF in hypoxia.