Measurement Techniques, Modeling Strategies and Pitfalls to Avoid when Implementing a Mini MLC in a Non Dedicated Planning System*

BACKGROUND AND PURPOSE: Ghent University Hospital investigated the feasibility of the Pinnacle system for planning intracranial stereotactic treatments. The aim was to perform precise dose computation using the collapsed cone engine for treatment delivery with the Moduleaf mini-MLC mounted on an Elekta accelerator. MATERIAL AND METHODS: The Moduleaf was commissioned using dose rate corrected data recorded by a diamond detector and using data measured by cylindrical chambers each limited to restricted field sizes. RESULTS: Automatic modeling resulted in clinical relevant dose errors up to 10%. Using manual modeling in Pinnacle, for clinical applicable fields a 2%/2 mm agreement between modeled data and measurements was obtained. CONCLUSION: The overall accuracy of the collapsed cone algorithm is within tolerances for single fraction stereotactic treatments.     

Comparison of uptake of99mTc-MIBI,99mTc-tetrofosmin and99mTc-012 into human breast cancer cell lines

Technetium-99m hexakis-2-methoxyisobutylisonitrile (MIBI),^99mTc-tetrofosmin and^99mTc-Q12 were all introduced for myocardial imaging but found additional applications as they are taken up by different tumours, enabling imaging of these lesions in patients. The aim of this study was to compare the uptake characteristics of these compounds in vitro in the human adenocarcinoma breast cell lines MCF-7 and ZR-75. It was shown that^99mTc-MIBI had the highest cellular uptake (15.9%±0.5% dose/mg protein after 60 min in MCF-7, and 14.2%±0.4% dose/mg protein in ZR-75), followed by^99mTc-tetrofosmin (6.8%±0.6% dose/mg protein in MCF-7, and 8.2%±0.2% dose/mg protein in ZR-75) and^99mTc-Q12 (3,2%±0. I% dose/mg protein in MCF-7, and 3.5%±0.3% dose/mg protein in ZR-75 cells). For all three compounds tenfold differences in specific activity did not influence total cell-associated radioactivity. Uptake of^99mTc-MIBI and^99mTc-tetrofosmin was obviously lower at 4° C than at 37° C, whereas^99mTc-Q12 uptake showed only slight temperature dependence. When uptake was compared in cells grown to different cell densities (1 mg/ml cellular protein versus 0.3 mg/ml), no differences in uptake were detected when uptake was corrected for the amount of cellular protein present in the dishes. Furthermore, for all compounds it was shown that cellular radioactivity decreased rapidly after washing. Apart from the differences in cellular uptake of the three compounds after 60 min, no differences in residual cellular radioactivity after washing were found between the different compounds when expressed as a percentage of their 60-min uptake, suggesting that the efflux process of the radiolabelled compounds was similar. The differences in cell-associated activity after 60 min were thus presumably caused by differences in uptake. It was concluded that of the Tc-labelled compounds tested,^99mTc-MIBI had the highest cellular retention in both human breast tumour cell lines. However, for imaging in vivo not only radioactivity in the target organ is important, but also the ratio of radioactivity in the target versus that in the background. Therefore, further studies in vivo need to be performed to investigate which compound is the optimal imaging agent     

Pre-reading and Pre-arithmetic Instruction in Infant Education in the Netherlands: A Multilevel Analysis Approach

This article describes the results of a study into the relationship between teacher and pupil characteristics in Dutch infant classes 1 and 2 (4-6 year-olds) of primary education. The study discerns three groups of variables: pupils' socio-ethnic background; pre-reading and pre-arithmetic test results; teaching strategy (intensity of guided/programmed activities). The main question is whetherthe pupils' test results vary as a result of the teaching strategy used after controlling for socio-ethnic background at individual as well as class level. The sample consists of 446 teachers and 5,490 pupils. The results of the multilevel analyses show that the teaching method used is of no relevance in explaining test results. The most important factor is the socio-ethnic background of the pupils. The fact that a Dutch or immigrant pupil is from a working-class background has a negative effect on the pre-reading and pre-arithmetic test results. The teaching method effects (i.e., the lack of effects) do not differ for classes with or without immigrant pupils. This does not alter the fact, however, that pupils in classes with a relatively high number of working-class children do less well, quite apart from their individual socio-ethnic background.     

Intracranial EEG Seizure-Offset Termination Patterns: Relation to Outcome of Epilepsy Surgery in Temporal Lobe Epilepsy

Summary: Purpose: Studies using stereo-EEG (SEEG) and electrocorticography (ECoG) should not only identify a patient's epileptogenic zone, but also should provide prognostic information for surgical outcome. In this respect, seizure-offset patterns have so far been the subject of only one study, in which they were shown to be associated with poor outcome when recorded over cortical areas outside the temporal lobe of seizure onset. To clarify whether seizure-offset patterns are reliable in predicting seizure outcome, we studied SEEG/ECoG in a similar group of patients with temporal lobe epilepsy (TLE). Methods: SEEGECoG records of 44 patients with refractory TLE were analyzed. The areas of seizure termination were classified as ipsilateral or contralateral (mesial and/or lateral) temporal, (temporal and) frontal, and diffusehilateral. Patients were classified with respect to seizure outcome as either seizure-free (UCLA class la) or not seizure free (UCLA class 2–4); both groups were correlated with specific seizure-offset categories using Fisher's exact probability test and analysis of variance (ANOVA). Results: Of the 44 patients, the majority (n = 36) had at least part of their seizure offsets in the ipsilateral temporal lobe, whereas 8 patients manifested no seizure offsets in this lobe. Only 9 patients (20%) showed exclusive offsets in the ipsilateral temporal lobe. No statistically significant difference was evident between patients with all seizure offsets in the ipsilateral temporal lobe and those with offsets elsewhere. Similarly, no statistically significant difference was evident between patients with a diffuse seizure offset and those with seizure offsets of a different category. Conclusions: Seizure-offset patterns in SEEGECoG are unreliable in predicting seizure outcome after resective activity surgery for TLE.     

Automated flow cytometry analysis of peritoneal dialysis fluid.

BACKGROUND: Recently, the Sysmex UF-100 flow cytometer has been developed to automate urinalysis. We have evaluated this instrument to explore the possibilities of flow cytometry in the analysis of peritoneal dialysis fluid (PD) and have compared the obtained data with those of counting chamber techniques, biochemical analysis and bacterial culture. METHODS: UF-100 data were correlated with microscopy and biochemical data in 135 PD samples. Microbiological analysis was performed in 63 suspected cases of peritonitis. RESULTS: Good agreement (P < 0.001) was obtained between UF-100 and microscopy data for leukocytes (r = 0.825). UF-100 bacterial count correlated (P < 0.001) with UF-100 leukocyte count (r = 0.549). UF-100 bacterial counts were unreliable in samples where interference by blood platelets was observed. Another major problem was the UF-100 'bacterial' background signal in sterile PD samples. Yeast cells were detected by the flow cytometer in spiked samples. CONCLUSIONS: Flow cytometry of PD with the UF-100 offers a rapid and reliable leukocyte count. Sensitivity of the 'bacterial' channel count in predicting positive culture exceeds the sensitivity of conventional Gram stain. Furthermore, additional semi-quantitative information is provided regarding the presence of yeasts.     

18F-FDG PET in detecting metastatic infectious disease.

Timely identification of metastatic complications of bloodstream infections due to spreading of the microorganisms to distant sites, although critical, is often difficult. As 18F-FDG accumulates in activated leukocytes in infectious lesions, 18F-FDG PET represents a promising imaging technique in these patients. The aim of this study was to assess the value of 18F-FDG PET in detecting infectious foci in patients at high risk of metastatic complications. METHODS: The results of all 18F-FDG PET scans ordered because of suspected metastatic infection from October 1998 to September 2004 were analyzed retrospectively. These results were compared with conventional investigation techniques and the final clinical diagnosis. RESULTS: The results of 40 18F-FDG PET scans were evaluated. In 60% of all episodes, Gram-positive bacteria were cultured, in 18% Gram-negative bacteria, in 20% Candida spp., and in 3% the infection was polymicrobial. Metastatic complications were diagnosed in 75% of all episodes. A median number of 4 diagnostic procedures to search for metastatic infection had been performed before 18F-FDG PET was ordered. 18F-FDG PET diagnosed a clinically relevant new focus in 45% of cases and confirmed abnormalities already diagnosed in 30% of cases. The positive predictive value of 18F-FDG PET was 91% and the negative predictive value was 100%. CONCLUSION: 18F-FDG PET is a valuable imaging technique in patients at high risk of metastatic infectious disease, even when the results of other diagnostic procedures are normal.     

Comparative study of donor lung injury in heart-beating versus non-heart-beating donors.

OBJECTIVE: The use of non-heart-beating donors (NHBD) has been advocated as an alternative to overcome the critical organ shortage in lung transplantation despite the warm ischemic period that may result in primary graft dysfunction. On the contrary, brain death in the heart-beating donor (HBD) may be an underestimated risk factor for donor lung injury. We postulated that 60 min of warm ischemia in the NHBD is less detrimental to the lung than the pathophysiological changes after brain death in the HBD. In this study we compared the quality of lungs from HBD versus NHBD in an isolated reperfusion model. METHODS: Pigs (n=10 per group) were divided into three groups. In group I (HBD), brain death was induced by acute inflation of an intracranial epidural balloon catheter. In group II (CONTROL), the balloon was not inflated. In group III (NHBD), cardiac arrest was induced by myocardial fibrillation. After 5 h of in situ mechanical ventilation, lungs in HBD and CONTROL were preserved with a cold antegrade flush. In NHBD, unflushed grafts were explanted after 1 h of warm ischemia and 4 h of topical cooling in the cadaver. Graft performance was evaluated during 1 h in an isolated ventilation and reperfusion model. Extravascular lung water content (EVLW) was calculated. All data are reported as mean+/-SEM. RESULTS: A significant autonomic storm was observed in HBD following balloon inflation. During ex vivo assessment, pulmonary vascular resistance (PVR) at 60 min in HBD (2634+/-371 dynes cm(-5)) was significantly higher as compared with that of CONTROL and NHBD (1894+/-137 dynes s cm(-5) and 1268+/-111 dynes s cm(-5), respectively; p<0.05). Plateau airway pressure (Plateau AwP) was also higher in HBD (17+/-1cmH2O) compared with that of CONTROL (12+/-1 cmH2O; p<0.05) and NHBD (14+/-1 cmH2O; not significant). No significant differences were observed between HBD, CONTROL and NHBD in EVLW (79+/-1%, 79+/-0% and 78+/-1%, respectively), and in PO2/FiO2 (564+/-58 mmHg, 622+/-14 mmHg and 578+/-26 mmHg, respectively). CONCLUSIONS: These data indicate that 1-h warm ischemic lungs in our model are less susceptible to ischemia-reperfusion injury than lungs retrieved 5 h after brain death. This study further supports the use of lungs from NHBD for pulmonary transplantation.     

Effect of azithromycin on bronchiectasis and pulmonary function in a heart-lung transplant patient with severe chronic allograft dysfunction: a case report.

Azithromycin has been shown to be beneficial in several diseases with chronic neutrophilic inflammation of the airways, such as cystic fibrosis and bronchiolitis obliterans syndrome (BOS) after lung transplantation. Up to now, however, its healing effect on bronchiectasis has never been demonstrated. We report a heart-lung transplant patient who developed chronic rejection (BOS stage 3) with the appearance of gross bronchiectasis on a spiral computed tomography (CT) chest scan. Within 2 weeks after starting azithromycin, the patient's forced expiratory volume in 1 second increased significantly and a repeat spiral CT chest scan 5 months later, showed a major improvement of the bronchiectasis. This case report illustrates that bronchiectasis may greatly improve after treatment with azithromycin and no longer needs to be considered an endstage finding in patients with severe BOS.     

Impaired disengagement from threatening cues of impending pain in a crossmodal cueing paradigm.

This paper reports an experimental investigation of attentional engagement to and disengagement from cues of impending pain. Pain-free volunteers performed a cueing task in which they were instructed to detect somatosensory and tone targets. Target stimuli were preceded by visual cues informing participants of the modality of the impending stimuli. Participants were randomly assigned to a pain group (n = 54) or to a control group (n = 53). Somatosensory targets consisted of painful electrocutaneous stimuli in the pain group and non-painful vibrotactile targets in the control group. Analyses revealed a similar amount of attentional engagement to both cues signalling somatosensory targets, irrespective of their threat value. However, participants had significantly more difficulty in disengaging attention from a threatening cue of impending pain compared to a cue signalling the non-painful vibrotactile target. Our findings provide further evidence that pain cues demand attention, particularly resulting in impaired disengagement.