[en] The aim of this study was to investigate whether normoglycemic glucose concentrations interfere with cerebral F-18 fluorodeoxyglucose (FDG) uptake. The analysis was based on 2 sets of paired positron emission tomography (PET) scans in 94 patients who were in complete metabolic remission after the successful completion of treatment for lymphoma. For these 188 PET scans, 2 subgroups were defined according to the plasma glucose level at the time of scanning. Group 1 contained the PET images that were associated with the lower of both normoglycemic plasma glucose levels, whereas group 2 contained the PET images that were associated with the higher of both plasma glucose levels. SUVs (standard uptake values) in the cerebellum between both groups were compared using paired sample T test. Subsequently, SUVs were normalized to a standard glucose concentration and normalized SUVs were again compared. Further, we calculated the coefficient of variation of SUVs in group 1 and 2 both before and after the normalization step. Mean plasma glucose level was 86 mg/dL (standard deviation (SD) of 9 mg/dL) in group 1 and 97 mg/dL (SD of 10 mg/dL) in group 2. Mean SUV was 3.8 (SD of 1.1) for group 1 and 3.5 (SD of 1.1) for group 2. Mean SUV in group 1 was slightly but statistically significantly higher than the mean SUV in group 2 (p<0.01). Mean normalized SUV was 3.6 (SD of 1.1) in group 1 and 3.7 (SD of 1.3) in group 2. A paired comparison between normalized SUVs in both groups indicated that there was no statistically significant difference (p<0.31). The coefficient of variation for the SUVs in group 1 and 2 before normalization was 29 and 30%, respectively. The coefficient of variation for the normalized SUVs in group 1 and 2 was 30 and 34%, respectively. Our results indicated that plasma glucose levels that are within the normoglycemic range have a small but systematic effect on F-18 FDG uptake in the brain (following an inverse relationship). Normalizing plasma glucose levels to a standard glucose concentration successfully reduced the intra-subject variability of SUV measures. Inter-subject variability, however, remained high suggesting that other factors have an influence as well. (author)

[en] For FDG-whole Body PET, as for any other medical imaging technique, resolution is a very important factor. In clinical practice however, most of PET centers use a 4mm pixel size reconstruction despite the fact that software for reconstruction with 2mm pixel size is usually available in the system. The reason is mainly practical, the processing time of 2mm reconstruction is 8 times longer than that of 4mm. In this study we compare the results obtained using 4mm and 2mm pixel size reconstruction. The aim was to evaluate whether the improvement in resolution is obvious enough to justify a longer processing time

[en] The objective of the study was to present a simple method for comparing clinical positron emission tomography (PET) images to a set of increasing quality images. Those different quality images were obtained by varying the activity concentration and the acquisition time. Images of a Jaszczak phantom were acquired with scan times that were calculated with a spreadsheet application for a personal computer to obtain 500, 1000, 2000, 5000, 7000 and 9000 counts/4 mm³ voxel. During a 10-h period, each scan was repeated with longer acquisition times to obtain the same number of counts in the reconstructed images, but with lower count rate. On the second day, the study was repeated, putting the phantom in a water bath to simulate larger patients. The quality of the images obtained with the phantom in water was worse than without, as expected. Phantom data demonstrated clearly the effect of higher counts on image quality. Good quality images were obtained with counts above 5000 counts/voxel. Patient data can be situated to the phantom image set by comparing the counts per voxel and the activity concentration. The counts per voxel in all the regions of interest on patient data, with the exception of the brain, were at sub-optimal level leading to decreased image quality. It is clear that better image quality can be achieved mainly by incrementing the scan time. Our PET system, however, allows doubling our standard injected activity to obtain more image counts without significant contrast loss. This simple test can be performed at any PET center to situate the quality of routine clinical PET images in comparison to the optimal possible for that system. (author)

[en] The objective of this study was to investigate the correlation between the F-18 fluorodeoxyglucose (FDG) uptake in the normal testis as assessed by positron emission tomography (PET)-CT and patient age in a pediatric study population. The study population consisted of 22 subjects aged between 9 and 17 years. For these subjects 42 PET-CT scans were available for analysis. The testis was identified on the CT images. Mean standard uptake values and testicular volume were calculated based on manually drawn regions-of-interest over the organ. The correlation between mean standardized uptake value (SUV) and age as well as between testicular volume and age was calculated using Pearson's correlation coefficient. A strong and statistically significant positive correlation between F-18 FDG uptake in the testis and age was documented. The correlation coefficient was 0.406 in the analysis based on 42 PET-CT studies (p=0.005). The correlation between tracer uptake and age was reassessed based on 22 PET-CT studies including the last recorded PET-CT scan per patient. The correlation coefficient was 0.409 (p=0.05). In addition, based on 22 PET-CT scans, a strong and statistically significant positive correlation between testicular volume and age was documented (r=0.67, p<0.001). Whereas it was previously shown that in adult men there was a weak but statistically significant negative correlation between F-18 FDG uptake in the normal testis and age, we found a strong and statistically significant positive correlation in children and teenage boys. (author)

[en] The SPECT is an imaging technique used in neurology. This technique has helped to understand pathologies such Alzheimer dementia, parkinsonism. Study and works about the neurology imaging are explained and the advances in this area are developed. (N.C.)

No abstract available

[en] The aim of our study was to evaluate the value of a pictorial atlas of ¹²³I FP-CIT SPECT images for aid in the visual diagnosis. Patients, materials, methods: Sixty patients, of whom 20 were clinically diagnosed as 'non-parkinsonian' and 40 as having Parkinson's disease or any related disorder, were included in the study. An atlas consisting of 12 ¹²³I FP-CIT SPECT images was constructed first. Validity of the atlas was investigated by performing a receiver operating characteristic (ROC) analysis with the clinical diagnosis as the gold standard. The remaining 48 SPECT images were visually assessed twice by 5 observers, first with and secondly without consulting the atlas, or vice versa. The added value of the atlas was investigated by comparing the diagnostic accuracy and the interobserver variability for both methods. Results: ROC analysis performed on the atlas yielded an area under the curve of 1 for a threshold discriminating between clinically non-parkinsonian and parkinsonian patients that was situated between image 4 and 5 of the atlas, For the diagnostic accuracy, we found that the area under the ROC curve was systematically higher if observers had access to the atlas compared to when they had not (Wilcoxon's test, p<0.05). Also, the interobserver variability was significantly lower when observers used the atlas when compared to when they did not (p = 0.05). Conclusion: Diagnostic accuracy was significantly higher and interobserver variability significantly lower if observers had access to the atlas compared to when they had not. Hence, having a pictorial atlas available may facilitate the visual assessment of ¹²³I FP-CIT SPECT scans. (orig.)

[en] Aim: Sigma receptors which are expressed in the brain as well as in endocrine and immune systems have been the focus of research in the past few years due to their implicated role in psychosis. Many widely used antipsychotics interact with sigma receptors, some exhibit sigma receptor antagonism as their predominant mode of action. There is evidence that sigma receptors modulate several neuroreceptors, including dopaminergic and other catecholaminergic systems. Furthermore there are indications that a decrease of cortical sigma receptors occurs in schizophrenia. They are also present in high densities in various human and rodent cancer cell lines. In light of these findings we report the synthesis and in vivo evaluation of a ¹²³I-labelled selective sigma ligand. Materials and Methods: The ¹²³I-labelled compound was synthesized by electrophilic iododestannylation of the tributyltin derivative. For biodistribution studies 37 kBq of the ¹²³I-labelled compound dissolved in a mixture water/ethanol (99/1) was injected i.v. into the tail vein of NMRI mice. At various time points p.i. the mice were sacrificed and dissected. Biodistribution studies were performed until 48 hours p.i.. For blocking studies the mice were injected with cold product (1mg/kg) 10 minutes before tracer injection. Regional brain distributions were carried out in New Zealand rabbits, for this study 9,25 MBq of the ¹²³I-labelled compound dissolved in a mixture water/ethanol (90/10) was injected i.v. into the ear vein. At various time points up to 1 hour post injection the rabbits were sacrificed and their brain was dissected. Subsequently a regional blocking study was preformed in rabbits using the sigma ligand 1-(3-fluoropropyl)-4-(4-cyanophenoxymethyl)-piperidine (FPS)(0,5 mg/kg) which was injected 5 minutes before tracer injection. Results: Radiochemical yield was 70% ± 5%. Radiochemical purity was >95%. Biodistribution studies showed penetration through the blood brain barrier and accumulation in the brain (ratio brain to blood after 10 min: 10). Pretreatment with cold product resulted in a decrease of accumulation of the tracer in the brain (ratio brain to blood after 10 min: 1.6). As expected the regional brain distribution showed a homogeneous distribution throughout the brain, pretreatment with FPS resulted in a decrease of the uptake in different brain regions (cortex: 91%, striatum: 88% and hypothalamus: 89% decrease). Conclusion: Both biodistribution and blocking studies in mice and rabbits show that ¹²³I-4-iodo-N-(4-(4-(2-methoxyphenyl)-1-piperazinyl)butyl)-benzamide is a potential tracer for in vivo visualization of the sigma receptor

[en] The aim of the study was to determine the accuracy of non-rigid nine-parameter image registrations based on ¹⁵³Gd transmission computed tomography (TCT) images as compared with those based on ^99mTc-ethyl cysteinate dimer (ECD) images and to assess whether normalised mutual information (NMI) or count difference (CD) should be used. TCT and ECD data were acquired in 25 randomly selected patients. Emission images were registered to an ECD template with a CD cost function. The same registration parameters were applied to the transmission images to create a TCT template. All TCT images were registered to the TCT template and the same registration parameters were applied to the ECD images. The procedure was repeated with NMI as cost function. Accuracy of both ECD-based and TCT-based registrations was assessed by comparing the normalisation parameter values and regional activities in the spatially normalised ECD images, using a mixed-model analysis of variance (ANOVA). Scheffe post hoc tests were performed. No significant differences were found between ECD/CD, ECD/NMI and TCT/CD, suggesting that ECD registration can be done with either CD or NMI, and that TCT registration using CD is equally as accurate as ECD registration. The accuracy of TCT registration with NMI was lower, with discrepancies occurring in the frontal inferior region and the cerebellum. The analysis of normalisation parameters indicated that z-scaling is underestimated and yz-rotation overestimated with TCT/NMI registration. We conclude that ECD registrations with CD or NMI are as accurate as TCT registrations with CD and that TCT registrations with NMI should be avoided. (orig.)

[en] The least invasive of all surgical weight-lowering procedures is the adjustable laparoscopic gastric banding (ALGB) technique. A rare complication (0.9%-1.8% of patients) but one that may require surgical revision is leakage of the gastric banding device. This paper reports on the usefulness of technetium-99m scintigraphy for the assessment of gastric band leaks as compared with radiography. Between March 1997 and October 2001, 23 obese patients (20 women and 3 men; mean age 35 years; range 23-60 years; mean body mass index before gastric banding procedure, 39.2 kg/m²; range 29.3-52.1 kg/m²) were referred for exclusion of gastric banding leakage by means of radiography and ^99mTc-pertechnetate scintigraphy. Both procedures were performed on the same day in all patients. Two patients underwent both procedures, respectively two and three times. A total of 27 radiographic and scintigraphic examinations were performed. Radiographs were judged positive for leakage when escape of contrast agent through a defect in the gastric banding device was visualised or when indirect criteria, e.g. smooth passage of barium suspension through the stoma after injection of contrast agent, were present. Scintigraphic images were judged positive when tracer disappearance out of the banding device and uptake in the thyroid gland as well as enhancement of the gastric mucosa were observed 30 min and/or 3 h post injection. Overall sensitivity, specificity and accuracy for radiography and ^99mTc scintigraphy were 81.8% vs 81.8%, 75% vs 100% and 77.7% vs 92.6%. Leakage from the reservoir or the connecting tube is a late complication of ALGB. The presented data suggest that ^99mTc-pertechnetate scintigraphy is more efficient than radiography in determining the presence of such leaks. (orig.)