Study of the Dependency on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter.

At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution ΔEFWHM =3.7 eV, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterised the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter.

Haematuria: intravenous urography, ultrasound or both?

PURPOSE: To compare the diagnostic value of intravenous urography (IVU), ultrasound (US) and their combination in detecting upper urinary tract malignancies in patients with haematuria. MATERIALS AND METHODS: In a prospective study, 360 consecutive patients who consulted the urologist for haematuria without renal colic were scheduled for IVU and US on the same day. The two procedures were performed by two different radiologists and reported independently. Histology or clinical follow-up of one year served as the gold standard. RESULTS: 63 patients dropped out. Of the remaining 297 patients, 9 (3%) had a malignancy in the upper urinary tract. Sensitivity and specificity with regard to the upper urinary tract pathology were 67% and 91% for IVU and 56% and 94% for US, respectively. For both techniques combined this was 79% and 88%, respectively. CONCLUSION: An acceptable sensitivity for detecting upper urinary tract malignancies is obtained only by combining IVU and US.

Acute whiplash injury: is there a role for MR imaging?--a prospective study of 100 patients.

PURPOSE: To evaluate the findings from magnetic resonance (MR) imaging of the cervical spine and brain after acute whiplash injury. MATERIALS AND METHODS: Within 3 weeks of trauma, 100 patients underwent MR imaging for evaluation of the cervical spine and the brain. In addition, plain radiographs were obtained, including functional images of the cervical spine. RESULTS: Only one patient had an abnormality on the MR image that was related to trauma (ie, prevertebral edema). In 17 patients, functional images showed a kyphotic angle, but no evidence of soft-tissue injury was seen on MR images. CONCLUSION: There is no role for MR imaging in the routine work-up of patients with acute whiplash injury who have normal plain radiographic findings and no evidence of a neurologic deficit. A kyphotic angle seen on functional images of the cervical spine should not be assumed to indicate soft-tissue injury and is most likely attributable to a compensating mechanism of hypermobility at a level of the spine above that at which hypomobility occurs, which is probably the result of a muscle spasm.

Usefulness of cinefluoroscopic detection of coronary artery calcification in the diagnostic work-up of coronary artery disease.

AIM: To determine in which patients (cine)fluoroscopic detection of coronary artery calcifications is recommended for the diagnosis of coronary artery disease and the consequence of this finding for referral for cinecoronary arteriography. MATERIALS AND METHODS: Data were retrospectively obtained from 778 patients who had been referred for cinecoronary arteriography. Excluded were patients with a previous myocardial infarction, a previous abnormal cinecoronary arteriogram and patients with unstable angina. The discriminating value was assessed with the help of the crude likelihood ratio (LR), as well as the LRs stratified for gender, age and symptomatology. The gold standard was the coronary arteriogram. Furthermore, the post-test probability was estimated using logistic regression to take dependence on age, sex and symptomatology into account. RESULTS: The crude LR of a positive and negative test result, with 95% confidence intervals, was, respectively 5.8 (4.1-8.2) and 0.52 (0.47-0.58), but was dependent on the clinical variables. Estimated probabilities of having coronary artery disease (CAD) varied substantially for a negative as well as a positive test result with the categories of clinical variables. CONCLUSION: (Cine)fluoroscopy discriminates between patients with and without disease; the test proved to be especially useful in females with atypical angina and patients of both sexes with non-specific chest pain.

Comparison of the diagnostic value of cinefluoroscopy and simple fluoroscopy in the detection of calcification in coronary arteries.

AIM: Comparison of the diagnostic value of cinefluoroscopy and simple fluoroscopy in the detection of calcification in coronary arteries. PATIENTS AND METHODS: Data were prospectively obtained from 143 patients in whom simple fluoroscopy as well as cinecoronary arteriography were performed. Excluded were patients with a previous myocardial infarction, a previous abnormal cinecoronary arteriogram and patients with unstable angina. With the coronary arteriogram as the gold standard, the likelihood ratios (LR) of simple fluoroscopy were determined, mismatches with cinefluoroscopy were analysed and Kappa, as a measure for inter-test agreement, was calculated. RESULTS: The LRs with 95% confidence intervals for a positive and negative result were 5.3 (2.6-11.0) and 0.43 (0.28-0.69), respectively. There was a mismatch in 12 (8.3%) patients. Kappa with a 95% confidence interval was 0.90 (0.73-1.0). CONCLUSIONS: Both test modalities are almost identical and conclusions with respect of the diagnostic value of cinefluoroscopy also holds for simple fluoroscopy.

Erectile dysfunction: timing of spectral wave-form analysis in the assessment of the function of the cavernosal arteries.

Color Doppler ultrasound seems to be an accurate method to evaluate vascular erectile function, in particular the arterial supply of the penis. Because of its relative noninvasiveness and easy performance, it has to precede more invasive evaluation (cavernosography and invasive angiography). Combination of wave form pattern analysis with peak systolic velocity measurements allows differentiation between arterial and venous insufficiency. Fifty-one patients suffering from erectile dysfunction, were examined with use of color Doppler ultrasound. Nine had adequate vascular function with good penile tumescence. However, during these adequate (late) stages of tumescence, peak systolic velocity fluctuated significantly. We conclude that in the late stages of tumescence, velocity measurements are not reliable as a parameter of arterial function.

Introduction of an improved direct agglutination test for the detection of Leishmania infantum infection in southern France.

An improved direct agglutination test (DAT) is assessed for the detection of Leishmania infantum antibodies in man and in the canine reservoir in Southern France. The test performance in 32 human visceral leishmaniasis patients was in agreement with the parasitological diagnosis and the immunofluorescence (IFAT) results. In six patients diagnosed earlier as kala-azar cases, both DAT and IFAT revealed negative results. The specificity of the DAT was reproduced in this study by the absence of cross-reactions with sera from other patients. In the dog reservoir, the DAT results were compared with those obtained by IFAT, the enzyme-linked immunosorbent assay (ELISA), cross-over electrophoresis and the latex agglutination test. All 34 dogs with parasitologically positive lymph node aspirates also had positive DAT titres (less than or equal to 1:640); the sensitivity in the other four tests was relatively low. Positive DAT and IFAT results were found in 16 unconfirmed cases of canine leishmaniasis, most probably due to prepatent L. infantum infections.

Application of a direct agglutination test for detection of specific anti-Leishmania antibodies in the canine reservoir.

A direct agglutination test (DAT) for detection of visceral leishmaniasis in humans has been developed. In this study, it was evaluated for applicability to detection of infections in dogs, a reservoir species. The reliability of the test was improved by treating the test sera with 0.2 M 2-mercaptoethanol and incubating them at 37 degrees C. Sensitivity was 100% and specificity was 98.9% when the test was used on serum samples from 220 dogs, including 26 with parasitologically confirmed canine leishmaniasis, 12 with suspected but unconfirmed leishmaniasis, and 182 with other conditions. The DAT detected specific antibodies in 10 dogs with canine leishmaniasis diagnosed by case history, clinical signs of leishmaniasis, and seropositivity in an immunofluorescence test using either promastigotes or amastigotes, as well as in 2 dogs suspected of having leishmaniasis. The performance of an antigen prepared from a homologous isolate of Leishmania infantum in the DAT was compared with that of an antigen from a laboratory-adapted strain of L. donovani (sensu lato). The homologous antigen compared favorably with the standard antigen, and the results provided further evidence of the potential of the DAT for detection of Leishmania infection in the canine reservoir host. The results of this study, together with those of our previous studies in human visceral leishmaniasis, demonstrate that the DAT is highly suitable for wide-scale epidemiological and ecological field work. This technique could also facilitate diagnosis of leishmaniasis in dogs in veterinary health services.

High-throughput replica optics.

Some simple formulas are derived to calculate the maximum effective area that can be obtained by Kirkpatrick-Baez, Wolter, and conical x-ray telescopes in those cases for which that area is limited by the focal length. Electroforming and epoxy replication techniques are reviewed, and the design and production technology chosen for the high throughput telescopes to be flown on the European X-Ray Spectroscopy Mission are presented.

EXOSAT x-ray imaging optics.

The European X-ray Observatory, EXOSAT, to be launched in 1981 will carry two Wolter I x-ray telescopes, each having a geometric area of ~100 cm(2). A qualification model of the Wolter I optics has been manufactured and extensively tested in optical and x-ray beams. The influence of manufacturing tolerances on the resolution of the optics is discussed, and mechanical and optical measurements of those deviations are presented. Finally, the x-ray imaging quality of the optics is presented, and the correlation with the achieved tolerances is shown.

Efficiency and resolution measurements of x-ray transmission gratings between 7.1 and 304 A.

Efficiency and resolution measurements are reported of an x-ray transmission grating to be flown on board the European X-ray Observatory Satellite (EXOSAT). By optimizing the thickness of the grating bars, very high efficiencies can be obtained over a limited energy range. An absolute efficiency of 20% at 7.1 A decreasing to 10% above 15 A has been achieved, including all effects of support structure and mounting necessary to withstand space qualification. This means that 10% of the incoming radiation at 7.1 A results in the minus first spectral order and 10% in the plus first order. The measured resolution at the short wavelength end of the range (lambda > 20 A) is determined by the mirror resolution; at the longer wavelengths (300 A), the effects of coma and astigmatism dominate. The measured resolution at 304 A for the EXOSAT-mirror-grating system is 4.5 A in agreement with theoretical predictions.

Assessment of surface roughness by x-ray scattering and differential interference contrast microscopy.

X-ray scattering measurements at 8.3 A and 13.3 A are employed to study surface roughness down to 2.5-A rms. The x-ray setup is described, and its sensitivity is discussed. The scattering data are analyzed by electromagnetic scattering theory to give information about the surface roughness. Micrographs of the same surfaces are made by differential interference contrast microscopy. A good correlation between these micrographs and the results from the x-ray scattering measurements is established, which indicates that differential interference contrast microscopy is a very useful tool for the evaluation of highly polished surfaces.