[en] Twenty-three children with acute lymphocytic leukemia (ALL) were examined with cranial CT at least twice with a minimal interval of 10 months. The first CT was performed at the time of diagnosis in 11 children and during therapy in 12; all but two were normal on the first CT examination. These two had slight enlargement of the ventricular system and subarachnoid space at the time of diagnosis. These findings were unchanged on the second CT examinations. Seven patients, all in remission from leukemia of the central nervous system manifested abnormal findings on later CTs. Low density areas in the periventricular white matter were seen in the brains of three, with increasing subcortical calcification in one of these cases. Five children had slight enlargement of the ventricular system and subarachnoid space, especially of the basal and Sylvian cisterns. Later CT examinations in five, plus brain autopsy in two cases, revealed unchanged or progressive conditions. The CT findings have been related to the treatment and some characteristics of the disease. The frequency of CT abnormalities was higher in patients who had received therapeutic irradiation and intraventricular methotrexate treatment. The possible reasons for the CT abnormalities are discussed. (orig.)

[en] In September 1975 some unusual variations in X-ray emission from a star cluster were observed by the Dutch astronomic satellite. These were called 'X-ray bursters' and similar phenomena were observed, always from star clusters, and especially from their centres, near the centre of the Milky Way. These were later also visually identifies with weak blue stars. Energy calculations indicate that the source of the X-radiation must be a neutron star and a number of models for the origin of the radiation are briefly discussed. (JIW)

[en] We report the detection of five coincident optical/X-ray bursts from 4U/MXB 1636-53. The optical observations were made with the Danish 1.5 m telescope at the European Southern Observatory (E.S.O.) and the X-ray observations were made with the Hakucho X-ray observatory. We have analyzed these bursts in terms of a simple general mathematical model, in which the optical emission (both during and between the bursts) is that of a blackbody and the result of thermally reprocessed X-ray. One expects that the optical burst is a delayed and sneared verison of the X-ray burst. We estimate that the optical radiative delay is smaller than the observed values, which we believe are therefore mainly due to the geometry of the system. For the delay and smearing of the optical burst and the maximum temperature of the reprocessing region, we find values of approx.2.5 s, <4 s, and approx.75 x 10³ K, respectively. The reprocessing region surrounding the X-ray source has a projected area of approx.6 x 10²¹ cm² corresponding to a linear size of approx.1.5 lt-sec independent of any assumption about its geometry. An accretion disk around a compact object is one plausible model for the reprocessing region. The derived restrictions on the parameters of the reprocessing region also constrain the parameters of a consistent low-mass close binary system containing an approx.1.4 M/sub sun/ neutron star. The radius of the accretion disk is >1.5 1t-sec, the mass of the Roche lobe filling companion star is <2.0 M/sub sun/ corresponding to a binary period between approx.1 hour and approx.10 hours

[en] The CT findings of 15 benign supratentorial astrocytomas in children less than 15 years of age are compared with the CT findings of 19 supratentorial tumors of other histological types in the same age group. Astrocytomas were more often hypodense, lacked calcification and showed greater contrast enhancement than other tumors. Seven of the 15 astrocytomas were hypodense, without calcification and showed contrast enhancement of more than 10 Hounsfield units, whereas this coexistence was not present in any of the 19 tumors of the other histological types. (orig.)

[en] A case where an encapsulated permanent epidural catheter for continuous analgesia caused pressure on the dural sac is presented. The clinical findings and postmyelographic computerised tomography (CT) imitated an epidural metastasis, until an epidurography via the epidural catheter revealed its true nature. (orig.)

[en] The effect of the angiotensin-converting enzyme (ACE) inhibitor captopril on regional cerebral blood flow (rCBF) was studied in 12 patients within 5 days after their first acute stroke. rCBF was studied by xenon-133 inhalation and single-photon emission computed tomography (SPECT) scan before and 1 h after oral administration of 25 mg captopril. No increase in rCBF was observed in any of the 12 patients included in the study. In only one patient was there a slight redistribution of blood flow in favor of the low-flow area, but the absolute flow value did not increase. Captopril did not cause any significant change in mean hemispheric blood flow, mean arterial blood pressure (MAP), or end-expiratory CO2 fraction (FECO2). The assumption that ACE inhibition might increase cerebral blood flow in the periinfarct zone and preserve some still viable brain tissue could not be verified in the present study

[en] Computed tomography of the brain (CT) was carried out at the early stages of subacute sclerosing panencephalitis (SSPE) in three children. The lateral ventricles were very small and the hemispheric sulci and interhemispheric fissures were not visible in all three patients in contrast to severe atrophy found at a later stage in one patient. The early CT abnormalities were revealed at the same time as the titres of measles antibodies in blood and cerebrospinal fluid were elevated, and the characteristic periodic complexes in the electroencephalogram established the diagnosis of SSPE. The CT changes indicating brain swelling reflect the reactive changes of this slow virus infection. (orig.)

[en] The CT findings of 11 malignant primary supratentorial tumors in children are compared with those of 38 benign tumors. The malignant tumors were more often laterally placed and surrounded by edema. Irregular tumor shape and high or 'mixed' density were more frequent in the malignant group where larger tumor volume was found. The contrast enhancement pattern was also different. Thus, ring enhancement with central lucency was more often seen in the malignant tumors. Seven of the malignant tumors had both irregular shape and edema, while this combination was not present in any of the 38 benign tumors. (orig.)

[en] In a study of the radio pulsar of period 6.13369 ms, the second shortest pulsar period known, deep images have been obtained of the field in different colour bands using the European Southern Observatory charge-coupled device camera at the 1.5 m Danish telescope at La Silla. At least three objects are visible inside the radio error box, and their astrometry and photometry are reported here. (author)

[en] Optical photometry of the transient X-ray source 0748-676 in January 1988 showed the system to be bright (V ∼ 17.5), which suggests that after it was discovered in 1985 it has remained active for most of the time. The orbital optical light curve is similar to that of other eclipsing low-mass X-ray binaries, e.g. 4U 2129+47 and Her X-1. This light curve consists of an approximately sinusoidal component (amplitude ∼ 0.3 mag) with a rather sharp cusp (depth ∼ 0.3 mag) centered on the time of the X-ray eclipse. The first component, which is similar to the optical light curves observed for non-eclipsing low-mass X-ray binaries, is likely due to aspect variations of the X-ray heated parts of the surface of the secondary star. The second component is probably caused by partial eclipse of an accretion disk