Nurse assistants' experiences of encountering patients in grief due to the death of a loved one - a qualitative study in municipal health and social care.

PURPOSE: The aim was to explore nurse assistants´ experiences of paying attention to and encountering patients receiving municipal health and social care, who are in grief due to the death of a loved one. METHODS: A qualitative study with focus group interviews (n = 6) was conducted with nurse assistants (NAs) (n = 28) in municipal health and social care (n = 5) in southern Sweden. The data were analysed inductively using qualitative content analysis. RESULTS: Three categories (1) Noticing changes in the patient, (2) Using different strategies to create a dialogue with the patient, (3) Experiencing challenges when encountering patients in grief, included eight sub-categories were identified. The result is captured in the theme of Having to be attentive to signs of grief after patients´ loss of loved ones, sensing the right time to approach and comfort, while having to cope with emotional challenges. CONCLUSIONS: The NAs encountered expressions of strong emotions from patients in grief, and even expressions of a desire to end their lives. Additionally, the NAs had to deal with their own emotions that were evoked when meeting patients in grief. These challenges indicate the need for enhanced conditions in the work culture, and improved training and supervision in health and social care.

Imaging fatigue of interference control reveals the neural basis of executive resource depletion.

Executive control coordinates, prioritizes, and selects task-relevant representations under conditions of conflict. Behavioral evidence has documented that executive resources are separable, finite, and can be temporarily depleted; however, the neural basis for such resource limits are largely unknown. Here, we investigate the neural correlates underlying the fatigue or depletion of interference control, an executive process hypothesized to mediate competition among candidate memory representations. Using a pre/post continuous acquisition fMRI design, we demonstrate that, compared with a nondepletion control group, the depletion group showed a fatigue-induced performance deficit that was specific to interference control and accompanied by a left-to-right shift in the network of active regions. Specifically, we observed decreased BOLD signal in the left inferior frontal gyrus (IFG), striatum, and the cerebellum, along with a corresponding increase in right hemisphere regions including the IFG, insular, and temporal cortex. Depletion-related changes in activation magnitude correlated with behavioral changes, suggesting that decreased recruitment of task-relevant regions, including left IFG, contributes to impaired interference control. These results provide new evidence about the brain dynamics of "process-specific" fatigue and suggest that depletion may pose a significant limitation on the cognitive and neural resources available for executive control.

Evaluation of an attenuation correction method for PET/MR imaging of the head based on substitute CT images.

OBJECT: The aim of this study was to evaluate MR-based attenuation correction of PET emission data of the head, based on a previously described technique that calculates substitute CT (sCT) images from a set of MR images. MATERIALS AND METHODS: Images from eight patients, examined with (18)F-FLT PET/CT and MRI, were included. sCT images were calculated and co-registered to the corresponding CT images, and transferred to the PET/CT scanner for reconstruction. The new reconstructions were then compared with the originals. The effect of replacing bone with soft tissue in the sCT-images was also evaluated. RESULTS: The average relative difference between the sCT-corrected PET images and the CT-corrected PET images was 1.6% for the head and 1.9% for the brain. The average standard deviations of the relative differences within the head were relatively high, at 13.2%, primarily because of large differences in the nasal septa region. For the brain, the average standard deviation was lower, 4.1%. The global average difference in the head when replacing bone with soft tissue was 11%. CONCLUSION: The method presented here has a high rate of accuracy, but high-precision quantitative imaging of the nasal septa region is not possible at the moment.

Cross-camera comparison of ROI-based semi-quantitative ¹²³I-IBZM SPECT data in healthy volunteers using an anthropomorphic phantom for calibration.

BACKGROUND: In (123)I-Iolopride (IBZM) SPECT reference values may diverge between camera systems. If multicenter pooling of normal material databases is needed, differences in measured semi-quantitative data due to equipment performance and reconstruction parameters have to be investigated in each instance to determine the comparability. PURPOSE: To explore the differences in (123)I-IBZM measured uptake ratios between two different gamma cameras in healthy controls, the intra-rater reproducibility of the image evaluation method and the possibility to equalize uptake ratios by calibration through an anthropomorphic phantom. MATERIAL AND METHODS: Differences in ROI-based semi-quantitative data from two different gamma camera systems, the three-headed brain dedicated Neurocam and the two-headed multipurpose hybrid system Infinia Hawkeye, were studied using image data from a group of healthy volunteers and an anthropomorphic brain-phantom scanned with both cameras. Several reconstruction methods and corrections were applied. To test the reliability of the ROI method, the intra-observer reproducibility was determined for the ROI method in this study. RESULTS: The ROI method had a high reliability. Differences in mean measured uptake (123)I-IBZM ratios in healthy controls varied between 2.9% and 6.5% depending on reconstruction and correction for attenuation and scatter. After calibration, the differences decreased. There were no statistically significant differences between corrected ratios from the two camera systems in the study when images were reconstructed with attenuation correction. CONCLUSION: The conformity of uptake ratios in attenuation corrected (123)I-IBZM images derived from the two different cameras was improved by using an anthropomorphic phantom for calibration.

Outcomes of external and endonasal dacryocystorhinostomy according to a modified Lacrimal Symptom Questionnaire (Lac-Q).

Background: Nasolacrimal duct obstruction is usually treated using endoscopic or external dacryocystorhinostomy (DCR). The anatomic outcomes of both the endoscopic and external approaches are considered excellent. However, anatomic success does not translate into patient satisfaction. The current study assessed pre- and postoperative lacrimal problems using the symptom-based Lacrimal Symptom Questionnaire (Lac-Q) and investigated patient satisfaction depending on the choice of surgical technique. Methods: A total of 112 eligible patients with lacrimal problems treated using external or endonasal DCR at the ophthalmology and ear, nose, and throat clinics at Skane University Hospital, Scania, Sweden, over a four-year period, were enrolled in this retrospective study. Patients were considered eligible if they experienced preoperative epiphora and had lacrimal duct stenosis. They were offered treatment using either external or endonasal DCR and were allowed to freely choose the technique. Exclusion criteria consisted of previous ipsilateral DCR, congenital NLDO, age < 18 years, presence of cancer, previous orbital trauma, or noncompliance with postoperative follow-up. After surgery, the patients were sent the Lac-Q to evaluate their lacrimal symptoms pre- and postoperatively. Complementary questions were added pertaining to the operative scar and the patients' overall satisfaction with the operation. Results: In total, 67 (60%) patients with ages ranging from 18 to 88 years completed the questionnaire, 33 (49%) of whom underwent external DCR and 34 (51%) endonasal DCR. Of the 67 respondents, 51 (76%) were women and 16 (24%) were men. Patients scored preoperative lacrimal problems highly on the Lac-Q, reporting both symptomatic and social problems due to epiphora. Following surgery, the group that underwent external DCR remained home from work for 2 - 14 days (median, 3.5 days). However, 17 (52%) were retired. After the endonasal DCR, the patients remained home for 0 - 7 days (median, 2 days). Most patients were satisfied after DCR surgery, with both techniques significantly improving total, lacrimal symptom, and social impact scores (all P < 0.001). No differences in postoperative satisfaction were observed between the external DCR and endonasal DCR groups (P > 0.05). A small number of patients expressed scar-related concerns after external DCR. Conclusions: The patients perceived lacrimal problems as a significant symptomatic and social burden. Postoperative satisfaction and symptom relief were good regardless of the surgical approach. Further prospective studies assessing patient satisfaction and its correlation with anatomical and functional success rates after external and endonasal DCR could provide robust, practical, real-world implications.

Reliability and validity of visual analysis of [ 18 F]FE-PE2I PET/CT in early Parkinsonian disease.

OBJECTIVE: [ 18 F]FE-PE2I (FE-PE2I) is a new radiotracer for dopamine transporter (DAT) imaging with PET. The aim of this study was to evaluate the visual interpretation of FE-PE2I images for the diagnosis of idiopathic Parkinsonian syndrome (IPS). The inter-rater variability, sensitivity, specificity, and diagnostic accuracy for visual interpretation of striatal FE-PE2I compared to [ 123 I]FP-CIT (FP-CIT) single-photon emission computed tomography (SPECT) was evaluated. METHODS: Thirty patients with newly onset parkinsonism and 32 healthy controls with both an FE-PE2I and FP-CIT were included in the study. Four patients had normal DAT imaging, of which three did not fulfil the IPS criteria at the clinical reassessment after 2 years. Six raters evaluated the DAT images blinded to the clinical diagnosis, interpreting the image as being 'normal' or 'pathological', and assessed the degree of DAT-reduction in the caudate and putamen. The inter-rater agreement was assessed with intra-class correlation and Cronbach's α . For calculation of sensitivity and specificity, DAT images were defined as correctly classified if categorized as normal or pathological by ≥4/6 raters. RESULTS: The overall agreement in visual evaluation of the FE-PE2I- and FP-CIT images was high for the IPS patients ( α = 0.960 and 0.898, respectively), but lower in healthy controls (FE-PE2I: α = 0.693, FP-CIT: α = 0.657). Visual interpretation gave high sensitivity (both 0.96) but lower specificity (FE-PE2I: 0.86, FP-CIT: 0.63) with an accuracy of 90% for FE-PE2I and 77% for FP-CIT. CONCLUSION: Visual evaluation of FE-PE2I PET imaging demonstrates high reliability and diagnostic accuracy for IPS.

Brain activation patterns in major depressive disorder and work stress-related long-term sick leave among Swedish females.

Deficits in executive functioning and working memory associated with frontal lobe dysfunction are prominent in depression and work-related long-term sick leave (LTSL). This study used functional magnetic resonance imaging (fMRI) to investigate potential differences in brain activation patterns in these conditions. In addition, the function of the hypothalamic-pituitary-adrenal (HPA) axis was examined and compared between groups. Since there is a clear overrepresentation of women in these diagnostic groups, and to ensure a more homogenous sample population, only women were included. To examine the neural correlates of relevant cognitive processes in patients on sick leave >90 days due to work-related LTSL, recently diagnosed patients with major depression Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV criteria, untreated), and healthy controls (n = 10, each group), a 2-back working memory task and a visual long-term memory task were administered during fMRI scanning. HPA axis functioning was investigated using a diurnal curve of saliva cortisol and a dexamethasone suppression test. Task performance was comparable among the three groups. Multivariate image analysis revealed that both memory tasks engaged a similar brain network in all three groups, including the prefrontal and parietal cortex. During the 2-back task, LTSL patients had significant frontal hypoactivation compared to controls and patients with depression. Saliva cortisol measurements showed a flattening of the diurnal rythmicity in LTSL patients compared to patients with depression and healthy contols. Taken together, these findings indicate that work stress-related LTSL and major depression are dissociable in terms of frontal activation and diurnal cortisol rhythmicity.

VNTR polymorphism in the SLC6A3 gene does not influence dopamine transporter availability measured by [18F]FE-PE2I PET or [123I]FP-Cit SPECT.

OBJECTIVE: To investigate the potential impact of polymorphism in the 3'-untranslated region (3'UTR) of the SLC6A3 gene (DAT1) on normal variation in dopamine transporter (DAT) imaging with [18F]FE-PE2I PET and [123I]FP-Cit SPECT. METHODS: Thirty-six individuals (mean age 70.4±5.4 years) with normal [18F]FE-PE2I PET and [123I]FP-Cit SPECT were genotyped for variable number of tandem repeats (VNTR) in the 3'UTR of the DAT1 gene. The DAT-availability in the caudate and putamen as measured with [18F]FE-PE2I PET and [123I]FP-Cit SPECT, as well as in the substantia nigra with [18F]FE-PE2I PET were compared between the participants carrying one or two 9-repeat alleles (i.e. 9R+10R or 9R+9R; 47%) and the participants without a 9R allele (i.e. 10R+10R or 10R+11R; 53%). Nonparametric tests, linear regression analysis and mixed model analysis were used to assess any statistical difference in measured DAT availability between the two allele groups. RESULTS: The measured DAT-availability in PET- and SPECT-imaging tended to be slightly higher in the 9R-group; however, the difference did not reach statistical significance in either the caudate or the putamen or the substantia nigra. Instead, age did have a significant effect on the DAT level (P < 0.05) notwithstanding the genotype. CONCLUSION: No significant effect of DAT1-genotype was detectable in imaging with [18F]FE-PE2I PET or [123I]FP-Cit, instead, age accounted for the normal variation in DAT-PET and DAT-SPECT.

Influence of COMT gene polymorphism on fMRI-assessed sustained and transient activity during a working memory task.

The catechol O-methyltransferase (COMT) gene--encoding an enzyme that is essential for the degradation of dopamine (DA) in prefrontal cortex (PFC)--contains a single nucleotide polymorphism (val/met) important for cognition. According to the tonic-phasic hypothesis, individuals carrying the low-enzyme-activity allele (met) are characterized by enhanced tonic DA activity in PFC, promoting sustained cognitive representations in working memory. Val carriers have reduced tonic but enhanced phasic dopaminergic activity in subcortical regions, enhancing cognitive flexibility. We tested the tonic-phasic DA hypothesis by dissociating sustained and transient brain activity during performance on a 2-back working memory test using mixed blocked/event-related functional magnetic resonance imaging. Participants were men recruited from a random sample of the population (the Betula study) and consisted of 11 met/met and 11 val/val carriers aged 50 to 65 years, matched on age, education, and cognitive performance. There were no differences in 2-back performance between genotype groups. Met carriers displayed a greater transient medial temporal lobe response in the updating phase of working memory, whereas val carriers showed a greater sustained PFC activation in the maintenance phase. These results support the tonic-phasic theory of DA function in elucidating the specific phenotypic influence of the COMT val(158)met polymorphism on different components of working memory.

Pre- and postsynaptic dopamine SPECT in the early phase of idiopathic parkinsonism: a population-based study.

PURPOSE: The aim of this study was to assess the diagnostic contribution of pre- and postsynaptic dopamine SPECT in drug-naïve patients with early idiopathic parkinsonism and to investigate possible differences between idiopathic Parkinson's disease (PD) and atypical parkinsonian syndromes (APS) and possible differences in motor subtypes of parkinsonism. METHODS: A group of 128 newly diagnosed idiopathic parkinsonian patients and 48 healthy controls was studied. Presynaptic baseline SPECT with (123)I-FP-CIT was performed in all patients and in 120 patients also a baseline postsynaptic SPECT with (123)I-IBZM. Clinical diagnoses were reassessed after 12 months. RESULTS: Presynaptic uptake in the putamen and caudate was significantly reduced in patients compared to controls. Presynaptic uptake ratios were not different between PD patients and patients with APS, and postsynaptic uptake in APS was not significantly reduced compared to PD or controls. In half of the APS patients both pre- and postsynaptic uptake ratios were reduced on the same side in the striatum. Impaired motor performance was associated with decreased presynaptic uptake in the putamen in PD. The postural instability and gait difficulty (PIGD) subtype of PD had lower presynaptic uptake ratios than patients with tremor-dominated (TD) symptoms. CONCLUSION: Not only presynaptic putamen uptake ratios, but also caudate ratios were reduced in a majority of the patients in our study. At baseline scan, i.e. in an early stage of the disease, the accuracy of excluding APS in the whole study population was 85% using a combination of pre- and postsynaptic SPECT. Already at baseline, lower presynaptic SPECT ratios were seen in PD with PIGD at onset compared to those with TD subtype.

Temporal dynamics of basal ganglia under-recruitment in Parkinson's disease: transient caudate abnormalities during updating of working memory.

Using hybrid-blocked/event-related fMRI and the 2-back task we aimed to decompose tonic and phasic temporal dynamics of basal ganglia response abnormalities in working memory associated with early untreated Parkinson's disease. In view of the tonic/phasic dopamine hypothesis, which posits a functional division between phasic D(2)-dependent striatal updating processes and tonic D(1)-dependent prefrontal context-maintenance processes, we predicted that newly diagnosed, drug-naïve Parkinson's disease patients, with selective striatal dopamine deprivation, would demonstrate transient rather than sustained activation changes in the basal ganglia during 2-back performance. Task-related activation patterns within discrete basal ganglia structures were directly compared between patients and healthy elderly controls. The obtained results yielded uniquely transient underactivation foci in caudate nuclei, putamen and globus pallidus in Parkinson's disease patients, which indicates suboptimal phasic implementation of striatal D(2)-dependent gating mechanisms during updating. Sustained underactivation was only seen in the anterior putamen, which may reflect initial signs of tonic control impairment. No significant changes were exhibited in prefrontal cortex. The present findings resonate well with the tonic/phasic dopamine account and suggest that basal ganglia under-recruitment associated with executive dysfunction in early Parkinson's disease might predominantly stem from deficiencies in phasic executive components subserved by striatum.

Improved PET/MRI attenuation correction in the pelvic region using a statistical decomposition method on T2-weighted images.

BACKGROUND: Attenuation correction of PET/MRI is a remaining problem for whole-body PET/MRI. The statistical decomposition algorithm (SDA) is a probabilistic atlas-based method that calculates synthetic CTs from T2-weighted MRI scans. In this study, we evaluated the application of SDA for attenuation correction of PET images in the pelvic region. MATERIALS AND METHOD: Twelve patients were retrospectively selected from an ongoing prostate cancer research study. The patients had same-day scans of [11C]acetate PET/MRI and CT. The CT images were non-rigidly registered to the PET/MRI geometry, and PET images were reconstructed with attenuation correction employing CT, SDA-generated CT, and the built-in Dixon sequence-based method of the scanner. The PET images reconstructed using CT-based attenuation correction were used as ground truth. RESULTS: The mean whole-image PET uptake error was reduced from - 5.4% for Dixon-PET to - 0.9% for SDA-PET. The prostate standardized uptake value (SUV) quantification error was significantly reduced from - 5.6% for Dixon-PET to - 2.3% for SDA-PET. CONCLUSION: Attenuation correction with SDA improves quantification of PET/MR images in the pelvic region compared to the Dixon-based method.

Striatal dopamine D2 binding is related to frontal BOLD response during updating of long-term memory representations.

Multi-modal brain imaging was used to examine the relation between individual differences in resting-state striatal dopamine D2 binding and the magnitude of prefrontal BOLD activation during updating of long-term memory (LTM) representations. Increased activity in the left prefrontal cortex was observed when LTM updating was required, and there was a positive correlation between striatal D2 activity and the magnitude of left prefrontal activity during updating. These findings support predictions from neurocomputational models of a relation of dopaminergic neurotransmission to transient cognitive operations and related brain activity.

Idiopathic normal pressure hydrocephalus: increased supplementary motor activity accounts for improvement after CSF drainage.

In patients with idiopathic normal pressure hydrocephalus (INPH), the changes in brain function that take place in conjunction with improved behavioural performance after CSF drainage is still unknown. In this study, we use functional MRI (fMRI) to investigate the changes in cortical activity that accompany improved motor and cognitive performance after long-term external lumbar drainage (ELD) of CSF in patients with INPH. Eighteen INPH patients were initially included together with age- and sex-matched controls. Data from 11 INPH patients were analysed both before and after ELD. The average drain volume for these 11 patients was 400 ml/3 days. Brain activation was investigated by fMRI before and after the procedure on a 1.5T Philips scanner using protocols taxing motor performance (finger tapping and reaction time) and cognitive functioning (memory and attention). Behavioural data were compared using non-parametric tests at a significance level of 0.05, whereas fMRI data were analysed by statistical parametric mapping including conjunction analysis of areas with enhanced activity after drainage in patients and areas activated in controls (P < 0.005, uncorrected). Improved regions were defined as areas in the INPH brain that increased in activity after ELD with the requirement that the same areas were activated in control subjects. Following ELD, right-hand finger tapping improved from 104 +/- 38 to 117 +/- 25 (mean +/- SD) (P = 0.02). Left-hand finger tapping showed a tendency to improve, the number of keystrokes increasing from 91 +/- 40 to 105 +/- 20 (P = 0.12). Right-hand reaction time improved from 1630 +/- 566 ms to 1409 +/- 442 ms, whereas left-hand reaction time improved from 1760 +/- 600 ms to 1467 +/- 420 ms (both P-values = 0.01). Significant improvements in motor performance were accompanied by bilateral increased activation in the supplementary motor area. No improvement was found in cognitive functioning. The results suggest that motor function recovery in INPH patients after CSF removal is related to enhanced activity in medial parts of frontal motor areas considered crucial for motor planning; a finding consistent with INPH being a syndrome related to a reversible suppression of frontal periventricular cortico-basal ganglia-thalamo-cortical pathways.

Whole-Body Biodistribution and Dosimetry of the Dopamine Transporter Radioligand 18F-FE-PE2I in Human Subjects.

18F-(E)-N-(3-iodoprop-2-enyl)-2ß-carbofluoroethoxy-3ß-(4'-methyl-phenyl) nortropane (18F-FE-PE2I) was recently developed and has shown adequate affinity and high selectivity for the dopamine transporter (DAT). Previous studies have shown promising results for 18F-FE-PE2I as a suitable radioligand for DAT imaging. In this study, we investigated the whole-body biodistribution and dosimetry of 18F-FE-PE2I in healthy volunteers to support its utility as a suitable PET imaging agent for the DAT. Methods: Five healthy volunteers were given a mean activity of 2.5 MBq/kg, and 3 PET scans, head to thigh, were performed immediately after injection followed by 4 whole-body PET/CT scans between 0.5 and 6 h after injection. Blood samples were drawn in connection with the whole-body scans, and all urine was collected until 6 h after injection. Volumes of interest were delineated around 17 organs on all images, and the areas under the time-activity curves were calculated to obtain the total number of decays in the organs. The absorbed doses to organs and the effective dose were calculated using the software IDAC. Results: The highest activity concentration was observed in the liver (0.9%-1.2% injected activity/100 g) up to 30 min after injection. At later time points, the highest concentration was seen in the gallbladder (1.1%-0.1% injected activity/100 g). The activity excreted with urine ranged between 23% and 34%, with a mean of 28%. The urinary bladder received the highest absorbed dose (119 µGy/MBq), followed by the liver (46 µGy/MBq). The effective dose was 23 µSv/MBq (range, 19-28 µSv/MBq), resulting in an effective dose of 4.6 mSv for an administered activity of 200 MBq. Conclusion: The effective dose is within the same order of magnitude as other commonly used PET imaging agents as well as DAT agents. The reasonable effective dose, together with the previously reported favorable characteristics for DAT imaging and quantification, indicates that 18F-FE-PE2I is a suitable radioligand for DAT imaging.

Dopamine transporter imaging with [18F]FE-PE2I PET and [123I]FP-CIT SPECT-a clinical comparison.

BACKGROUND: Dopamine transporter (DAT) imaging may be of diagnostic value in patients with clinically suspected parkinsonian disease. The purpose of this study was to compare the diagnostic performance of DAT imaging with positron emission computed tomography (PET), using the recently developed, highly DAT-selective radiopharmaceutical [18F]FE-PE2I (FE-PE2I), to the commercially available and frequently used method with [123I]FP-CIT (FP-CIT) single-photon emission computed tomography (SPECT) in early-stage idiopathic parkinsonian syndrome (PS). METHODS: Twenty-two patients with a clinical de novo diagnosis of PS and 28 healthy controls (HC) participating in an on-going clinical trial of FE-PE2I were analyzed in this study. Within the trial protocol, participants are clinically reassessed 2 years after inclusion. A commercially available software was used for automatic calculation of FP-CIT-specific uptake ratio (SUR). MRI-based volumes of interest combined with threshold PET segmentation were used for FE-PE2I binding potential relative to non-displaceable binding (BPND) quantification and specific uptake value ratios (SUVR). RESULTS: PET with FE-PE2I revealed significant differences between patients with a clinical de novo diagnosis of PS and healthy controls in striatal DAT availability (p < 0.001), with excellent accuracy of predicting dopaminergic deficit in early-stage PS. The effect sizes were calculated for FE-PE2I BPND (Glass's Δ = 2.95), FE-PE2I SUVR (Glass's Δ = 2.57), and FP-CIT SUR (Glass's Δ = 2.29). The intraclass correlation (ICC) between FE-PE2I BPND FP-CIT SUR was high in the caudate (ICC = 0.923), putamen (ICC = 0.922), and striatum (ICC = 0.946), p < 0.001. Five of the 22 patients displayed preserved striatal DAT availability in the striatum with both methods. At follow-up, a non-PS clinical diagnosis was confirmed in three of these, while one was clinically diagnosed with corticobasal syndrome. In these patients, FE-PE2I binding was also normal in the substantia nigra (SN), while significantly reduced in the remaining patients. FE-PE2I measurement of the mean DAT availability in the putamen was strongly correlated with BPND in the SN (R = 0.816, p < 0.001). Olfaction and mean putamen DAT availability was correlated using both FE-PE2I BPND and FP-CIT SUR (R ≥ 0.616, p < 0.001). CONCLUSION: DAT imaging with FE-PE2I PET yields excellent basic diagnostic differentiation in early-stage PS, at least as good as FP-CIT SPECT.

The claustrum/insula region integrates conceptually related sounds and pictures.

The brain is able to create coherent percepts from multisensory input. This phenomenon, known as multisensory integration (MSI), is a ubiquitous feature of everyday life and has been found to be essential for a reliable interaction with the environment. Recent functional neuroimaging studies suggest that several different networks are engaged in various forms of MSI depending on the nature of information being integrated. However, little is known about the neural basis of a fundamental form of MSI in natural conditions; integration of common auditory and visual objects which are conceptually related, such as when we look at a cat and hear a meowing sound. Here we used event-related fMRI to compare the brain response to conceptually related and unrelated pairs of audio-visual stimuli denoting common objects. Our protocol was designed to preclude contamination of the results by cognitive processes additional to those needed for MSI. The results indicate that higher-order temporal and occipital areas respond to coincident sounds and pictures regardless of their semantic relationship; whereas, the right claustrum/insula region is differentially activated in association with multisensory integration of conceptually related common objects. This observation has important implications for understanding how multimodal information about common objects is represented in the brain.

Reduced functional brain activity response in cognitively intact apolipoprotein E epsilon4 carriers.

The apolipoprotein E epsilon4 (APOE epsilon4) is the main known genetic risk factor for Alzheimer's disease. Genetic assessments in combination with other diagnostic tools, such as neuroimaging, have the potential to facilitate early diagnosis. In this large-scale functional MRI (fMRI) study, we have contrasted 30 APOE epsilon4 carriers (age range: 49-74 years; 19 females), of which 10 were homozygous for the epsilon4 allele, and 30 non-carriers with regard to brain activity during a semantic categorization task. Test groups were closely matched for sex, age and education. Critically, both groups were cognitively intact and thus symptom-free of Alzheimer's disease. APOE epsilon4 carriers showed reduced task-related responses in the left inferior parietal cortex, and bilaterally in the anterior cingulate region. A dose-related response was observed in the parietal area such that diminution was most pronounced in homozygous compared with heterozygous carriers. In addition, contrasts of processing novel versus familiar items revealed an abnormal response in the right hippocampus in the APOE epsilon4 group, mainly expressed as diminished sensitivity to the relative novelty of stimuli. Collectively, these findings indicate that genetic risk translates into reduced functional brain activity, in regions pertinent to Alzheimer's disease, well before alterations can be detected at the behavioural level.

Gaussian prefiltering of 123I DAT SPECT images when using depth-independent resolution recovery.

Previously we have investigated a depth-independent compensation for collimator detector response (CDR) included in the OSEM reconstruction, intended for SPECT images that have been corrected for scatter and septal penetration using convolution-based methods. In this work, the aim was to study how different filtering strategies affect contrast as a function of noise when using Gaussian smoothing filters in combination with the above-described CDR compensation. The evaluation was performed for (123)I dopamine transporter (DAT) SPECT images. Prefiltering with 2D Gaussian filter kernels, where the deterioration in resolution is included in the depth-independent CDR compensation, was compared to conventional postfiltering with 3D Gaussian filter kernels. Images reconstructed without filtering are also included in the comparison. It was found that there is little benefit in noise reduction when using CDR compensation. However, this variant of prefiltering gives consistently higher contrasts as a function of noise compared with the postfiltering alternative, and that could be of interest when using other types of filters with contrast improving properties.