The diagnostic value of 124I-PET in patients with differentiated thyroid cancer

Background The purpose of this prospective study was to evaluate the clinical diagnostic value of iodine- 124 ( I-124)positron emission tomography ( PET) in patients with advanced differentiated thyroid carcinoma ( DTC) and to compare the I-124- PET imaging results with the I-131 wholebody scan ( WBS). Materials and methods Twenty patients with histologically proven advanced DTC ( including T4, extra- nodal tumour growth, or distant metastases) underwent diagnostic (IWBS)-I-131, I-124- PET scan, and post-treatment I-131- WBS 4 months after ablation. The findings on the I-124- PET were compared with the findings on the diagnostic and post-therapeutic I-131- WBS and were also correlated with radiologic and/ or cytological investigations. Results I-124- PET vs diagnostic I-131- WBS. Eleven patients showed uptake on the I-124- PET. Only 3 of these 11 patients also showed uptake on the diagnostic I-131 scan, but the uptake was more clearly visible and the abnormalities were more extensive on the I-124- PET. I-124- PET vs post-treatment I-131- WBS. Eleven patients showed uptake on the I-124- PET, which was also visible on the post-treatment scan in nine patients; in the other two patients, no uptake was observed on the post-treatment scan and no anatomical localisation could be confirmed. Two patients showed only uptake on the post-treatment scan without uptake on the I-124- PET: in one, the uptake was confirmed by MRI, and in the other, no anatomical localisation was found. In seven patients, no uptake was observed on both the scans. Conclusion I-124- PET proved to be a superior diagnostic tool as compared to low-dose diagnostic I-131 scans and adequately predicted findings on subsequent high-dose post-treatment I-131 scans

Absolute quantitative total-body small-animal SPECT with focusing pinholes

Purpose: In pinhole SPECT, attenuation of the photon flux on trajectories between source and pinholes affects quantitative accuracy of reconstructed images. Previously we introduced iterative methods that compensate for image degrading effects of detector and pinhole blurring, pinhole sensitivity and scatter for multi-pinhole SPECT. The aim of this paper is (1) to investigate the accuracy of the Chang algorithm in rodents and (2) to present a practical Changbased method using body outline contours obtained with optical cameras. Methods: Here we develop and experimentally validate a practical method for attenuation correction based on a Chang first-order method. This approach has the advantage that it is employed after, and therefore independently from, iterative reconstruction. Therefore, no new system matrix has to be calculated for each specific animal. Experiments with phantoms and animals were performed with a highresolution focusing multi-pinhole SPECT system (USPECT-II, MILabs, The Netherlands). This SPECT system provides three additional optical camera images of the animal for each SPECT scan from which the animal contour can be estimated. Results: Phantom experiments demonstrated that an average quantification error of –18.7% was reduced to –1.7% when both window-based scatter correction and Chang correction based on the body outline from optical images were applied. Without scatter and attenuation correction, quantification errors in a sacrificed rat containing sources with known activity ranged from –23.6 to –9.3%. These errors were reduced to values between –6.3 and +4.3% (with an average magnitude of 2.1%) after applying scatter and Chang attenuation correction. Conclusion: We conclude that the modified Chang correction based on body contour combined with window-based scatter correction is a practical method for obtaining small-animal SPECT images with high quantitative accuracy.Radiation, Radionuclides and ReactorsApplied Science

FDG PET and PET/CT: EANM procedure guidelines for tumour PET imaging: version 1.0

The aim of this guideline is to provide a minimum standard for the acquisition and interpretation of PET and PET/CT scans with [18F]-fluorodeoxyglucose (FDG). This guideline will therefore address general information about [18F]-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) and is provided to help the physician and physicist to assist to carrying out, interpret, and document quantitative FDG PET/CT examinations, but will concentrate on the optimisation of diagnostic quality and quantitative information

Phenylketonuria:brain phenylalanine concentrations relate inversely to cerebral protein synthesis

In phenylketonuria, elevated plasma phenylalanine concentrations may disturb blood-to-brain large neutral amino acid (LNAA) transport and cerebral protein synthesis (CPS). We investigated the associations between these processes, using data obtained by positron emission tomography with L-[1-C-11]-tyrosine (C-11-Tyr) as a tracer. Blood-to-brain transport of non-Phe LNAAs was modeled by the rate constant for C-11-Tyr transport from arterial plasma to brain tissue (K-1), while CPS was modeled by the rate constant for C-11-Tyr incorporation into cerebral protein (k(3)). Brain phenylalanine concentrations were measured by magnetic resonance spectroscopy in three volumes of interest (VOls): supraventricular brain tissue (VOI 1), ventricular brain tissue (VOI 2), and fluid-containing ventricular voxels (VOI 3). The associations between k(3) and each predictor variable were analyzed by multiple linear regression. The rate constant k(3) was inversely associated with brain phenylalanine concentrations in VOls 2 and 3 (adjusted R-2 = 0.826, F = 19.936, P = 0.021). Since brain phenylalanine concentrations in these VOls highly correlated with each other, the specific associations of each predictor with k(3) could not be determined. The associations between k(3) and plasma phenylalanine concentration, K-1, and brain phenylalanine concentrations in VOI 1 were nonsignificant. In conclusion, our study shows an inverse association between k(3) and increased brain phenylalanine concentrations

Men Versus Women on Sexual Brain Function: Prominent Differences During Tactile Genital Stimulation, but not During Orgasm

Biological differences in male and female sexuality are obvious in the behavioral domain, but the central mechanisms that might explain these behavioral gender differences remain unclear. In this study, we merged two earlier positron emission tomography data sets to enable systematic comparison of the brain responses in heterosexual men and women during sexual tactile genital (penile and clitoral) stimulation and during orgasm. Gender commonalities were most evident during orgasm, a phase which demonstrated activations in the anterior lobe of the cerebellar vermis and deep cerebellar nuclei, and deactivations in the left ventromedial and orbitofrontal cortex in both men and women. During tactile genital stimulation, deactivations in the right amygdala and left fusiform gyrus were found for both genders. Marked gender differences were seen during this phase: left fronto-parietal areas (motor cortices, somatosensory area 2 and posterior parietal cortex) were activated more in women, whereas in men, the right claustrum and ventral occipitotemporal cortex showed larger activation. The only prominent gender difference during orgasm was male-biased activation of the periaqueductal gray matter. From these results, we conclude that during the sexual act, differential brain responses across genders are principally related to the stimulatory (plateau) phase and not to the orgasmic phase itself. These results add to a better understanding of the neural underpinnings of human sexuality, which might benefit treatment of psychosexual disorders. Hum Brain Mapp 30:3089-3101, 2009. (C) 2009 Wiley-Liss, Inc

Nursing documentation and its relationship with perceived nursing workload: a mixed-methods study among community nurses

BACKGROUND: The time that nurses spent on documentation can be substantial and burdensome. To date it was unknown if documentation activities are related to the workload that nurses perceive. A distinction between clinical documentation and organizational documentation seems relevant. This study aims to gain insight into community nurses' views on a potential relationship between their clinical and organizational documentation activities and their perceived nursing workload. METHODS: A convergent mixed-methods design was used. A quantitative survey was completed by 195 Dutch community nurses and a further 28 community nurses participated in qualitative focus groups. For the survey an online questionnaire was used. Descriptive statistics, Wilcoxon signed-ranked tests, Spearman's rank correlations and Wilcoxon rank-sum tests were used to analyse the survey data. Next, four qualitative focus groups were conducted in an iterative process of data collection - data analysis - more data collection, until data saturation was reached. In the qualitative analysis, the six steps of thematic analysis were followed. RESULTS: The majority of the community nurses perceived a high workload due to documentation activities. Although survey data showed that nurses estimated that they spent twice as much time on clinical documentation as on organizational documentation, the workload they perceived from these two types of documentation was comparable. Focus-group participants found organizational documentation particularly redundant. Furthermore, the survey indicated that a perceived high workload was not related to actual time spent on clinical documentation, while actual time spent on organizational documentation was related to the perceived workload. In addition, the survey showed no associations between community nurses' perceived workload and the user-friendliness of electronic health records. Yet focus-group participants did point towards the impact of limited user-friendliness on their perceived workload. Lastly, there was no association between the perceived workload and whether the nursing process was central in the electronic health records. CONCLUSIONS: Community nurses often perceive a high workload due to clinical and organizational documentation activities. Decreasing the time nurses have to spend specifically on organizational documentation and improving the user-friendliness and intercommunicability of electronic health records appear to be important ways of reducing the workload that community nurses perceive