Alternative component containing diesel fuel from different waste sources.

Mixtures with high fatty acid content are produced during vegetable oil and animal fat purification and paper production. These waste fractions can be converted into alternative fuels through several steps. The co-hydrogenation of waste polypropylene thermal cracked fraction or waste fatty acid mixture with unrefined gas oils is a potential solution for their conversion into hydrocarbons. The co-processing of these three different fractions was not yet investigated in these ratios. So the aim of the research work was to produce high quality diesel fuels and to study the occurring reactions and the interaction among these different compounds. The catalytic conversion of the mixture of unrefined gas oil, waste polypropylene cracked fraction (20 wt %) and waste fatty acid mixture (10, 20 and 30 wt %) was carried out on a commercial sulphided nickel-molybdenum-alumina catalyst. The effect of the feedstock compositions and the process parameters on the quantity and quality of the products was studied. The favourable process conditions to produce high quality diesel fuel blending components were selected (e.g., 10 wt % fatty acid waste, 360 °C temperature, 1.0 h-1 liquid hourly space velocity). The performance properties of this fuel were better than the conventional diesels', so their usage can be more environmentally friendly and lead to lower pollutant emission.

Postoperative interictal spikes during sleep contralateral to the operated side is associated with unfavourable surgical outcome in patients with preoperative bitemporal spikes.

PURPOSE: To correlate the persistence of contralateral spikes during sleep after unilateral surgery with seizure outcome in a temporal lobe epilepsy (TLE) population and to test the existing hypotheses about the origin of the contralateral spikes in temporal lobe epilepsy. METHODS: In the 19 patients selected for this study unilateral temporal lobe surgery was performed. To investigate the course of bilateral interictal epileptiform discharges observed before surgery in awake or sleep over the temporal lobe contralateral to surgery, 24 h mobile 12 channel EEG recording was performed at minimum two, in average 4.6 (2-10) years after the surgery. RESULTS: The association of postoperative contralateral spikes and non-seizure free outcome was highly significant. The existence of unilateral pathology before surgery was highly predictive for good outcome and disappearance of contralateral spikes. The association between good seizure outcome, disappearance of contralateral spikes and the existence of unilateral pathology before surgery was also significant. Our data partially satisfies the expectations of both the "seizure induced" and mirror type secondary epileptogenesis hypotheses concerning origin of contralateral spikes, but were not completely congruent with either of them. CONCLUSIONS: Unfavourable surgical outcome in a temporal lobe epilepsy group with preoperative independent bilateral interictal spikes was associated with the persistence of postoperative contralateral spikes and lack of unilateral pathology. Compared with seizure outcome the presence/absence and distribution of postoperative interictal spikes in NREM sleep not entirely fit to the predictions of existing secondary epileptogenesis hypotheses.

Ictal SPECT in children with epilepsy: comparison with intracranial EEG and relation to postsurgical outcome.

In order to validate the ability of ictal single photon emission computed tomography (SPECT) to localize the epileptogenic zone (EZ) in children, we compared in 20 patients aged from 10 months to 17 years (mean 6.5 years) the topography of the area of increased ictal perfusion (IPA), determined on the basis of ictal minus interictal scan values, with that of the EZ determined by intracranial EEG recordings and assessed its relationship with the postsurgical outcome. Eighteen patients had symptomatic epilepsy and 10 had extratemporal epilepsy. All patients except one had an ictal injection (mean time lag from clinical seizure onset was 18 s). Ictal and interictal SPECT images were successively co-registered, normalized, subtracted, smoothed and superimposed on MRI. All patients with ictal injection exhibited one or several IPAs. The topography of the 'highest' IPA, i.e. the maximal cerebral blood flow (CBF) change between ictal and interictal SPECT, significantly colocalized with the site of onset of the discharge, and that of the lower IPAs with that of the area of propagation (P < 0.0001). At a threshold of 30% of the maximal CBF change, the IPAs detected the onset of the discharge with a sensitivity of 0.80 and a specificity of 0.70. The highest IPA localized the EZ in 12 out of 15 patients. In the three others it missed the EZ and showed the area of propagation because of rapid seizure propagation or of infraclinical seizure onset. Among the patients with favourable surgery outcome, the highest IPA colocalized with the resected area in 70% of cases. Ictal SPECT could therefore plays an important role as a non-invasive presurgical method of investigation by optimizing the placement of intracranial electrodes, thus improving the postsurgery outcome of paediatric partial epilepsy.

Functional imaging in the work-up of childhood epilepsy.

In children with medically intractable lesional epilepsy, surgery is deemed successful if the epileptogenic focus can be removed while major neurological functions are spared. Current techniques rely on invasive intracranial recordings. The new developments in functional imaging offer the possibility of localizing the epileptogenic focus noninvasively (PET/SPECT) and mapping cognitive functions (fMRI). Ictal SPECT shows hyperperfusion in the focus and has proved to have better localizing value than interictal PET or SPECT, which show focal hypometabolism or hypoperfusion. Ictal SPECT is useful for deciding on the placement of intracranial electrodes in extratemporal epilepsies, particularly in young children. Functional MRI has proved highly accurate for localizing motor and language networks, thus offering the possibilities of replacing the Wada test (language hemispheric lateralization) and studying postlesional brain plasticity. Despite the difficulties of functional imaging in children owing to the limited cooperation that can be expected, ethical constraints, and poor normative data, SPECT/PET and fMRI provide clinically useful information for presurgical work-up of childhood epilepsies.

Ictal perfusion changes during occipital lobe seizures in infancy: report of two serial ictal observations.

Serial-ictal single-photon-emission computed tomography (SPECT) examinations are presented in two infants (ages 1 and 2 years), with early ictal and ictal in one, and ictal and late ictal images in the other. Both had pharmacoresistant occipital epilepsy, due to focal cortical dysplasia. In the first case, size of ictal hyperperfusion increased in the course of the seizure from early ictal to ictal state. A concomitant ictal hypoperfusion was observed around the hyperperfused area. In the second patient, there was a dramatic difference between ictal and late ictal images. In the late ictal state, the previous occipital ictal hyperperfusion and extraoccipital ictal hypoperfusion disappeared, together with homolateral posterotemporal and contralateral occipital hyperperfusion, corresponding to seizure propagation. Ictal extratemporal blood-flow changes are therefore highly dynamic, particularly in very young children.

[Ictal SPECT in the epileptic child. Contribution of subtraction interictal images and superposition of with MRI]. / SPECT ictal chez l'enfant épileptique. Intérêt de la soustraction avec les images interictales et de la superposition avec l'IRM.

Ictal SPECT is a highly sensitive method to localize the epileptogenic focus in refractory temporal lobe epilepsy in adults. In extratemporal epilepsy, sensitivity can be improved by subtracting interictal from ictal images and superimposing subtraction images on MRI. In children, such a procedure is potentially interesting because most epilepsies are extratemporal and ictal SPECT not yet routinely developed. The aim of this study was to test the feasibility of ictal SPECT with subtraction image processing in a pediatric population. Twenty-six children with refractory partial epilepsy and aged from 3 months to 18 years underwent ictal ECD-SPECT (20 mCi/1.73 m2) combined with video-EEG and interictal ECD-SPECT plus 3D-MRI two days later. Ictal-interictal subtraction images were computed by registering and normalizing the ictal to the interictal SPECT scans for each child. The ictal, interictal SPECT and subtraction images were registered to the children's MRI. Difference images were then superimposed to MRI for anatomical localization of the perfusion changes (overlay images). Looking for perfusion changes, overlay images allowed to detect at least one hyperperfused focus in 92 p. 100 of the 26 children compared to 73 p. 100 visually comparing ictal and interictal scans separately. Seizure onset was suspected on clinical and/or EEG and/or MRI in 19 children. Positive overlay images were concordant (n = 11) or larger (n = 7) than the suspected focus in 17/19 (90 p. 100), whereas they failed to show any abnormality in 1 child and were discordant with MRI in another one. In the 7 remaining patients, images showed cortical localization in 6 cases. Ictal SPECT is therefore faisable in very young children. Ictal-interictal subtraction SPECT images co-registered to MRI improves sensitivity compared to classical visual analysis. It seems therefore to be a helpful technique to localize the onset of seizure and to guide the intracranial recording in childhood epilepsy.

Use of subtraction ictal SPECT co-registered to MRI for optimizing the localization of seizure foci in children.

UNLABELLED: Ictal SPECT studies are increasingly used to localize seizure foci in children with refractory epilepsy, but few studies have reported on ictal-interictal subtraction images co-registered to MRI at this age. METHODS: Twenty-seven children with partial epilepsy (aged 3 mo-18 y) underwent ictal ethyl cysteinate dimer (ECD) SPECT (20 mCi/1.73 m2) combined with video-electroencephalography (EEG) and interictal ECD SPECT followed 2 d later by three-dimensional MRI. Ictal-interictal and interictal-ictal subtraction images were computed by registering and normalizing the ictal to the interictal SPECT scans for each child. The ictal, interictal SPECT and subtraction images were registered to each child's MRI. Difference images (ictal-interictal) were then superimposed on MRI for anatomic localization of the perfusion changes. Intra- and interobserver reproducibility and "facility of interpretation" of overlay images were compared with standard analysis of the non-coregistered ictal and interictal scans. RESULTS: Overlay images allowed the detection of at least one hyperperfused focus in 93% of the children, compared with 74% using ictal and interictal scans separately. Seizure onset was suspected clinically, on EEG or on MRI in 20 children. Overlay images were concordant (n = 11) or larger (n = 7) than the suspected focus in 18 of 20 (90%), whereas these images failed to show any abnormality in 1 child and were discordant with MRI in another patient. In the remaining 7, images showed cortical localization in 6 patients. Among the 5 patients who underwent electrocorticography, overlay images were concordant in 3, larger in 1 and absent in 1. The intra- and interobserver reproducibility and facility of interpretation were significantly higher using overlay images than standard analysis, even when ictal and interictal SPECT were co-registered. CONCLUSION: The co-registration of ictal-interictal subtraction SPECT images to MRI seems to be a helpful technique in localizing the onset of seizure and guiding the intracranial recording in childhood epilepsy. Moreover, this method improves sensitivity, enhances intra- and interobserver reproducibility and makes interpretation easier.

[First Hungarian experiences with positron emission tomography (PET) studies. Members of the PET working group]. / Elsö hazai tapasztalatok pozitron emissziós tomográfiás (PET) vizsgálatokkal. PET munkacsoport tagjai.

Diagnostic investigations commenced on the 28th of June 1994 in Hungary's and Central Europe's first PET Centre at the University Medical School of Debrecen. The Centre is equipped with a GE 4096 Plus whole body PET scanner. A metabolic tracer, 18F-deoxy-D-glucose (FDG), was used in the investigations. During the first 15 months 249 PET investigations were made in the Centre of which 242 were diagnostic and 7 normal subjects served as control for the patient studies with brain scans. The number of oncological indications (intra- and extracranial tumours, Hodgkin's lymphomas) was n = 105 (43.4% of the 242 diagnostic examinations), neurological investigations (without intracranial tumours) formed the dominant group (n = 117; 48.3%), whereas the number of cardiological indications was 20 (8.3%). The oncological studies included those of intracranial tumours (n = 76; 31.4%); thyroid tumours (n = 9; 3.7%); Hodgkin's lymphomas (n = 7; 2.9%) and other extracranial tumours (n = 13; 5.4%). The distribution of different neurological and psychiatric investigations was as follows: localization of focal epileptogen zone (n = 60; 24.8%); differential diagnosis of dementias (n = 30; 12.4%); exploration of cerebrovascular diseases (n = 10; 4.1%); and other neurological diseases (n = 17; 7.0%). The main objective of the cardiological PET investigations was the exploration of viable myocardium. The present paper overviews both the procedures (including administrative issues, as well) and the results of the first 249 FDG-PET investigations.