Food olfactory cues reactivity in individuals with obesity and the contribution of alexithymia.

Obesity has been associated with increased reward sensitivity to food stimuli, but a few studies have addressed this issue by using odors. This study investigated whether obesity is associated with increased liking and wanting of food odors and whether alexithymia, a psychological construct characterized by diminished affective abilities, contributes to altered responsiveness to food. Liking and wanting for food and pleasant non-food odors were measured through explicit (self-report ratings) and implicit measures (heart rate and skin conductance) in 23 women with healthy weight (HW) and 20 women with overweight/obesity (OW/OB). Differently from the HW group, the OW/OB group explicitly liked food odors less than non-food odors; but, at the implicit level, there were no differences in heart rate response for both types of odors, indicating that they were equally liked. Moreover, at variance with the HW group, the OW/OB group did not exhibit increased skin conductance response for food compared to nonfood odors. Alexithymia was associated with increased implicit liking and explicit wanting of food odors, in particular in the HW group. These findings show that obesity is characterized by high levels of implicit food liking and low levels of implicit food wanting. Moreover, both affective and motivational responses to food reward seem to be affected by alexithymia, which should be taken into account by studies evaluating the effect of cue exposure intervention for obesity treatment.

Functional brain networks during picture encoding and recognition in different odor contexts.

Contextual odors can serve as retrieval cues when applied during encoding and recall/recognition of information. To investigate the neuronal basis of these observations, we collected functional MRI data while participants (n=51) performed an encoding and recognition memory task during which odors (congruent: CO or incongruent: IO) were presented as contextual cues. Recognition performance was not influenced by odor, but there was increased activation in the piriform cortex during successful encoding in the CO group, possibly indicating enhanced retrieval of information previously integrated with an olfactory percept. Moreover, group-independent component analysis revealed a stronger task-modulation of subcortical networks for IO versus CO during the recognition task, pointing to differences in olfactory processing. These observations provide a deeper understanding of the involvement of functional neuronal networks in memory tasks and a basis for further evaluation of the impact of odor contexts.

Self-esteem as an important factor in quality of life and depressive symptoms in anosmia: A pilot study.

OBJECTIVES: Previous research has reported a negative impact of olfactory dysfunction on quality of life (QoL) and depressive symptoms. As self-esteem was identified as a contributing factor to depression, this study aimed to investigate QoL, depressive symptoms and self-esteem in patients with smell loss. DESIGN: Prospective controlled study. SETTING: Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, in co-operation with the Department of Ear, Nose and Throat Diseases, Medical University of Vienna, Austria. PARTICIPANTS: Twenty-two anosmic patients (12 females, 10 males) and 25 healthy controls (15 females, 10 males) participated in this study. MAIN OUTCOME MEASURES: Olfactory performance was assessed using the Sniffin' Sticks battery. In addition, psychological questionnaires that covered the topics quality of life (WHOQOL-BREF), depressive symptoms (BDI-II) and self-esteem (MSWS) were conducted. RESULTS: The results of this study revealed a decrease in QoL and reduced body-related self-esteem in anosmic patients. Furthermore, QoL and self-esteem were correlated with depressive symptoms. CONCLUSION: As self-esteem, QoL and depressive symptoms in anosmia interact with each other, we suggest that self-esteem should be considered in the medical history, in order to provide a personalised intervention, adapted to the patient's needs.

Olfactory training induces changes in regional functional connectivity in patients with long-term smell loss.

Recently, olfactory training has been introduced as a promising treatment for patients with olfactory dysfunction. However, less is known about the neuronal basis and the influence on functional networks of this training. Thus, we aimed to investigate the neuroplasticity of chemosensory perception through an olfactory training program in patients with smell loss. The experimental setup included functional MRI (fMRI) experiments with three different types of chemosensory stimuli. Ten anosmic patients (7f, 3m) and 14 healthy controls (7f, 7m) underwent the same testing sessions. After a 12-week olfactory training period, seven patients (4f, 3m) were invited for follow-up testing using the same fMRI protocol. Functional networks were identified using independent component analysis and were further examined in detail using functional connectivity analysis. We found that anosmic patients and healthy controls initially use the same three networks to process chemosensory input: the olfactory; the somatosensory; and the integrative network. Those networks did not differ between the two groups in their spatial extent, but in their functional connectivity. After the olfactory training, the sensitivity to detect odors significantly increased in the anosmic group, which was also manifested in modifications of functional connections in all three investigated networks. The results of this study indicate that an olfactory training program can reorganize functional networks, although, initially, no differences in the spatial distribution of neural activation were observed.

Effects of chronic peripheral olfactory loss on functional brain networks.

The effects of sensory loss on central processing in various sensory systems have already been described. The olfactory system holds the special ability to be activated by a sensorimotor act, without the presentation of an odor. In this study, we investigated brain changes related to chronic peripheral smell loss. We included 11 anosmic patients (eight female, three male; mean age, 43.5 years) with smell loss after an infection of the upper respiratory tract (mean disease duration, 4.64 years) and 14 healthy controls (seven female, seven male; mean age, 30.1 years) in a functional magnetic resonance imaging experiment with a sniffing paradigm. Data were analyzed using group-independent component analysis and functional connectivity analysis. Our results revealed a spatially intact olfactory network in patients, whereas major aberrations due to peripheral loss were observed in functional connectivity through a variety of distributed brain areas. This is the first study to show the re-organization caused by the lack of peripheral input. The results of this study indicate that anosmic patients hold the ability to activate an olfaction-related functional network through the sensorimotor component of odor-perception (sniffing). The areas involved were not different from those that emerged in healthy controls. However, functional connectivity appears to be different between the two groups, with a decrease in functional connectivity in the brain in patients with chronic peripheral sensory loss. We can further conclude that the loss of the sense of smell may induce far-reaching effects in the whole brain, which lead to compensatory mechanisms from other sensory systems due to the close interconnectivity of the olfactory system with other functional networks.

Intranasal insulin influences the olfactory performance of patients with smell loss, dependent on the body mass index: A pilot study.

BACKGROUND: The application of intranasal insulin in healthy humans has been linked to improved memory function, reduced food intake, and increased olfactory thresholds. There has also been some correlation between the morbidities associated with central nervous system (CNS) insulin resistance, such as type II diabetes mellitus, Alzheimer's disease, obesity, and impaired odour recognition. Given that impaired odour recognition is an important component of olfactory performance, mechanisms that govern these effects may account for impaired olfactory functions in anosmic patients. METHODOLOGY: Ten patients with post-infectious olfactory loss received intranasal administration of 40 IU insulin or a placebo solution, as well as olfactory performance tests before and after administration. RESULTS: When administered insulin, patients exhibited an immediate performance improvement with regard to olfactory sensitivity and olfactory intensity ratings. In addition, more odours were correctly identified. Furthermore, an improvement in the odour identification task was detected in patients with higher body mass index. CONCLUSION: Results of this pilot study shed light on the link between cerebral insulin level and an impaired sense of smell. This research line might provide a better understanding of olfactory loss in relation to eating and dietary behavior, and could offer opportunities to develop faster therapeutic intervention for patients with olfactory dysfunction.

[Clinical assessment of olfactory performance - why patient interviews are not enough : A report on lessons learned in planning studies with anosmic patients]. / Klinische Geruchstestungen - warum Befragungen alleine nicht ausreichen : Ein Bericht über die Erfahrungen in der Studienplanung mit anosmischen Patienten.

BACKGROUND AND AIM: Olfactory dysfunction and loss of smell are mostly associated with an immense decrease in the quality of life. The aim of the presented study was to report on particularities in the acquisition of patients with olfactory dysfunction. METHODS: During July 2011 and May 2014 we were contacted by 300 potential patients with self-reported loss of smell, 95 (54 female, 41 male, mean age 53) of which were invited for clinical testing after phone interviews. RESULTS: Clinical smell testing revealed 46 patients with anosmia, 38 with hyposmia, and 11 with normosmia. Self-assessment of olfactory function only correlated with clinical scores if patients had nearly no olfactory function left. The ability of self-assessment of olfactory function was independent of age or sex. Further, most patients were not able to report on the reason for or the duration of their olfactory dysfunction. DISCUSSION: Our report shows that patients with olfactory dysfunction are hardly ever ably to assess their grade of performance reduction. Awareness among patients with a reduced sense of smell is of great general importance, since it can be an indicator of neurodegenerative diseases. This should especially be noted for patients older than 50 who are not able to indicate a reason for their loss of smell.

Dual-source cardiac computed tomography angiography (CCTA) in the follow-up of cardiac transplant: comparison of image quality and radiation dose using three different imaging protocols.

OBJECTIVES: To prospectively evaluate image quality (IQ) and radiation dose of dual-source cardiac computed tomography (CCTA) using different imaging protocols. METHODS: CCTA was performed in 150 patients using the retrospective ECG-gated spiral technique (rECG) the prospective ECG-gated technique (pECG), or the prospective ECG-gated technique with systolic imaging and automated tube voltage selection (pECGsys). IQ was rated using a 16-segment coronary artery model. Techniques were compared for overall IQ, IQ of the large and the small coronary artery segments. Effective dose was used for comparison of radiation dose. RESULTS: Overall IQ and IQ of the large segments showed no differences between the groups. IQ analysis of the small segments showed lowered IQ in pECGsys compared to rECG (p = 0.02), but not to pECG (p = 0.6). Effective dose did not differ significantly between rECG and pECG (p = 0.13), but was significantly lower for pECGsys (p < 0.001 vs. rECG and pECG). CONCLUSION: Radiation dose of dual-source CCTA in heart transplant recipients is significantly reduced by using prospective systolic scanning and automated tube voltage selection, while overall IQ and IQ of the large coronary segments are maintained. IQ appears to be lower compared to retrospective techniques with regard to small coronary segments. KEY POINTS: • Cardiac computed tomography angiography is useful for cardiac allograft vasculopathy assessment. • Despite elevated heart rate, dose reduction in cardiac computed tomography is possible. • Prospective systolic gating and automated tube voltage selection enable 50 % dose reduction.

Non-invasive assessment of intratumoral vascularity using arterial spin labeling: A comparison to susceptibility-weighted imaging for the differentiation of primary cerebral lymphoma and glioblastoma.

Using conventional MRI methods, the differentiation of primary cerebral lymphomas (PCNSL) and other primary brain tumors, such as glioblastomas, is difficult due to overlapping imaging characteristics. This study was designed to discriminate tumor entities using normalized vascular intratumoral signal intensity values (nVITS) obtained from pulsed arterial spin labeling (PASL), combined with intratumoral susceptibility signals (ITSS) from susceptibility-weighted imaging (SWI). Thirty consecutive patients with glioblastoma (n=22) and PCNSL (n=8), histologically classified according to the WHO brain tumor classification, were included. MRIs were acquired on a 3T scanner, and included PASL and SWI sequences. nVITS was defined by the signal intensity ratio between the tumor and the contralateral normal brain tissue, as obtained by PASL images. ITSS was determined as intratumoral low signal intensity structures detected on SWI sequences and were divided into four different grades. Potential differences in the nVITS and ITSS between glioblastomas and PCNSLs were revealed using statistical testing. To determine sensitivity, specificity, and diagnostic accuracy, as well as an optimum cut-off value for the differentiation of PCNSL and glioblastoma, a receiver operating characteristic analysis was used. We found that nVITS (p=0.011) and ITSS (p=0.001) values were significantly higher in glioblastoma than in PCNSL. The optimal cut-off value for nVITS was 1.41 and 1.5 for ITSS, with a sensitivity, specificity, and accuracy of more than 95%. These findings indicate that nVITS values have a comparable diagnostic accuracy to ITSS values in differentiating glioblastoma and PCNSL, offering a completely non-invasive and fast assessment of tumoral vascularity in a clinical setting.

Arterial spin-labeling assessment of normalized vascular intratumoral signal intensity as a predictor of histologic grade of astrocytic neoplasms.

BACKGROUND AND PURPOSE: Pulsed arterial spin-labeling is a noninvasive MR imaging perfusion method performed with the use of water in the arterial blood as an endogenous contrast agent. The purpose of this study was to determine the inversion time with the largest difference in normalized intratumoral signal intensity between high-grade and low-grade astrocytomas. MATERIALS AND METHODS: Thirty-three patients with gliomas, histologically classified as low-grade (n = 7) or high-grade astrocytomas (n = 26) according to the World Health Organization brain tumor classification, were included. A 3T MR scanner was used to perform pulsed arterial spin-labeling measurements at 8 different inversion times (370 ms, 614 ms, 864 ms, 1114 ms, 1364 ms, 1614 ms, 1864 ms, and 2114 ms). Normalized intratumoral signal intensity was calculated, which was defined by the signal intensity ratio of the tumor and the contralateral normal brain tissue for all fixed inversion times. A 3-way mixed ANOVA was used to reveal potential differences in the normalized vascular intratumoral signal intensity between high-grade and low-grade astrocytomas. RESULTS: The difference in normalized vascular intratumoral signal intensity between high-grade and low-grade astrocytomas obtained the most statistically significant results at 370 ms (P = .003, other P values ranged from .012-.955). CONCLUSIONS: The inversion time by which to differentiate high-grade and low-grade astrocytomas by use of normalized vascular intratumoral signal intensity was 370 ms in our study. The normalized vascular intratumoral signal intensity values at this inversion time mainly reflect the labeled intra-arterial blood bolus and therefore could be referred to as normalized vascular intratumoral signal intensity. Our data indicate that the use of normalized vascular intratumoral signal intensity values allows differentiation between low-grade and high-grade astrocytomas and thus may serve as a new, noninvasive marker for astrocytoma grading.

Altered likelihood of brain activation in attention and working memory networks in patients with multiple sclerosis: an ALE meta-analysis.

Multiple sclerosis (MS) is a chronic neurological disease, frequently affecting attention and working memory functions. Functional imaging studies investigating those functions in MS patients are hard to compare, as they include heterogeneous patient groups and use different paradigms for cognitive testing. The aim of this study was to investigate alterations in neuronal activation between MS patients and healthy controls performing attention and working memory tasks. Two meta-analyses of previously published fMRI studies investigating attention and working memory were conducted for MS patients and healthy controls, respectively. Resulting maps were contrasted to compare brain activation in patients and healthy controls. Significantly increased brain activation in the inferior parietal lobule and the dorsolateral prefrontal cortex was detected for healthy controls. In contrast, higher neuronal activation in MS patients was obtained in the left ventrolateral prefrontal cortex and the right premotor area. With this meta-analytic approach previous results of investigations examining cognitive function using fMRI are summarized and compared. Therefore a more general view on cognitive dysfunction in this heterogeneous disease is enabled.

A systematic investigation of the invariance of resting-state network patterns: is resting-state fMRI ready for pre-surgical planning?

OBJECTIVES: Measurements of resting-state networks (RSNs) have been used to investigate a wide range of diseases, such as dementia or epilepsy. This raises the question whether this method could also serve as a pre-surgical planning tool. Generating reliable functional connectivity patterns is of crucial importance, particularly for pre-surgical planning, as these patterns may directly affect the outcome. METHODS: This study investigated the reproducibility of four commonly used resting-state conditions: fixation of a black crosshair on a white screen; fixation of the center of a black screen; eyes-closed and fixation of the words "Entspann dich!" (Engl., "relax"). Ten healthy, right-handed male subjects (mean age, 25 years; SD 2) participated in the experiment. The spatial overlap for different RSNs across the four conditions was calculated. RESULTS: The spatial overlap across all four conditions was calculated for each seed region on a single subject and at the group level. Activation maps at the single-subject and group levels were highly stable, especially for the reading network (RNW). The lowest consistency measures were found for the visual network (VIN). At the single-subject level spatial overlap values ranged from 0.31 (VIN) to 0.45 (RNW). CONCLUSION: These findings suggest that RSN measurements are a reliable tool to assess language-related networks in clinical settings. Generally, resting-state conditions showed comparable activation patterns, therefore no specific conditions appears to be preferable.

[Advanced MRI techniques of the fetal brain]. / Zukunftsweisende MRT-Techniken des fetalen Gehirns.

CLINICAL/METHODICAL ISSUE: Evaluation of the normal and pathological fetal brain. STANDARD RADIOLOGICAL METHODS: Magnetic resonance imaging (MRI). METHODICAL INNOVATIONS: Advanced MRI of the fetal brain. PERFORMANCE: Diffusion tensor imaging (DTI) is used in clinical practice, all other methods are used at a research level. ACHIEVEMENTS: Serving as standard methods in the future. PRACTICAL RECOMMENDATIONS: Combined structural and functional data for all gestational ages will allow more specific insight into the developmental processes of the fetal brain. This gain of information will help provide a common understanding of complex spatial and temporal procedures of early morphological features and their impact on cognitive and sensory abilities.

Magnetic resonance methods in fetal neurology.

Fetal magnetic resonance imaging (MRI) has become an established clinical adjunct for the in-vivo evaluation of human brain development. Normal fetal brain maturation can be studied with MRI from the 18th week of gestation to term and relies primarily on T2-weighted sequences. Recently diffusion-weighted sequences have gained importance in the structural assessment of the fetal brain. Diffusion-weighted imaging provides quantitative information about water motion and tissue microstructure and has applications for both developmental and destructive brain processes. Advanced magnetic resonance techniques, such as spectroscopy, might be used to demonstrate metabolites that are involved in brain maturation, though their development is still in the early stages. Using fetal MRI in addition to prenatal ultrasound, morphological, metabolic, and functional assessment of the fetus can be achieved. The latter is not only based on observation of fetal movements as an indirect sign of activity of the fetal brain but also on direct visualization of fetal brain activity, adding a new component to fetal neurology. This article provides an overview of the MRI methods used for fetal neurologic evaluation, focusing on normal and abnormal early brain development.

Watching the fetal brain at 'rest'.

Functional magnetic resonance imaging (fMRI) has allowed insights into the spatiotemporal distribution of human brain networks. According to the neurophysiological property of the fetal brain to generate spontaneous activity, we aimed to determine the feasibility of investigating the maturation of intrinsic networks, beginning at gestational week 20 in healthy human fetuses by combining resting-state fMRI and an analytical approach, independent component analysis (ICA). In this study, functional images of 16 fetuses with morphologically normal brain development, from 20 to 36 gestational weeks of age, were acquired on a 1.5T unit (Philips Medical Systems, Best, The Netherlands) using single-shot, gradient-recalled echo-planar imaging. After preprocessing (motion correction, brain extraction), images were analyzed using single-subject ICA. We visualized a bilateral occipital network and medial and lateral prefrontal activity pattern that involved the future Brodmann areas 9-11. Furthermore, there was one either predominantly right (3/7 cases) or left (4/7 cases) hemispheric lateralized network that involved the superior temporal cortical regions (Brodmann areas 22 and 39). Frequency oscillations were in the range of 0.01-0.06Hz for all networks. This study shows that resting-state networks (RSNs) are shaped and are detectable in utero. Further investigations of resting-state measurements in the fetus may therefore allow developmental brain activity monitoring and may provide insights into early brain function.

Susceptibility-weighted angiography (SWAN) of cerebral veins and arteries compared to TOF-MRA.

PROBLEM: High resolution, non-contrast imaging of both cerebral veins and arteries by use of gradient echo T2 star weighted angiography (SWAN) is a new method for susceptibility-weighted imaging with short acquisition times. We assessed the potential of this sequence for the depiction of both cerebral veins and arteries. METHODS: 15 healthy volunteers were included in the study. MRI was performed on a 3T MR scanner using the following sequences: (1) a 3D multi-echo gradient echo T2 star weighted angiography (SWAN), (2) an arterial 3D TOF MR angiography and (3) a venous 2D TOF. With regard to the SWAN sequence, both MinIP and MIP images were reconstructed and systematically compared to MIP reconstructions of the artTOF and the venTOF. To suggest possible clinical implications of our findings, we additionally included two illustrative cases. RESULTS: With regard to the visualization of the cerebral veins, the MinIP reconstructions of the SWAN sequence were considerably superior compared to the venTOF. Concerning the depiction of the main segments of the big cerebral arteries the value of the MIP reconstructions of the SWAN was comparable to that of the artTOF with limitations in the homogenity and in the depiction of smaller arteries. CONCLUSIONS: SWAN allows for high-resolution visualization of both cerebral veins and arteries in one sequence without application of contrast agent and with significantly shortened scan time compared to the combined scan time of TOF-MRA and TOF-MRV. By use of either MinIP or MIP reconstructions, the arteries can be distinguished from the veins.

Mirror therapy in lower limb amputees--a look beyond primary motor cortex reorganization.

PURPOSE: Phantom pain in upper limb amputees is associated with the extent of reorganization in the primary sensorimotor cortex. Mirror visual feedback therapy has been shown to improve phantom pain. We investigated the extent of cortical reorganization in lower limb amputees and changes in neural activity induced by mirror therapy. MATERIALS AND METHODS: Eight lower limb amputees underwent 12 sessions of MVFT and functional magnetic resonance imaging (fMRI) of the brain before the first and after the last MVFT session. FMRI sessions consisted of two runs in which subjects were instructed to perform repetitive movement of the healthy and phantom ankle. RESULTS: Before MVFT, the mean phantom pain intensity was 4.6 ± 3.1 on a visual analog scale and decreased to 1.8 ± 1.7 (p = 0.04). We did not observe a consistent pattern of cortical activation in primary sensorimotor areas during phantom limb movements. Following MVFT, increased activity was obtained in the right orbitofrontal cortex during phantom ankle movements. Comparison of cortical activity during movements of the phantom ankle and the intact ankle showed significantly higher activity in the left inferior frontal cortex (pars triangularis). CONCLUSION: These results question the known association between phantom pain and primary sensorimotor reorganization and propose reorganizational changes involving multiple cortical areas in lower limb amputees. Finally, reduction of phantom pain after mirror visual feedback therapy was associated with increased prefrontal cortical activity during phantom ankle movements.

Model-free fMRI group analysis using FENICA.

Exploratory analysis of functional MRI data allows activation to be detected even if the time course differs from that which is expected. Independent Component Analysis (ICA) has emerged as a powerful approach, but current extensions to the analysis of group studies suffer from a number of drawbacks: they can be computationally demanding, results are dominated by technical and motion artefacts, and some methods require that time courses be the same for all subjects or that templates be defined to identify common components. We have developed a group ICA (gICA) method which is based on single-subject ICA decompositions and the assumption that the spatial distribution of signal changes in components which reflect activation is similar between subjects. This approach, which we have called Fully Exploratory Network Independent Component Analysis (FENICA), identifies group activation in two stages. ICA is performed on the single-subject level, then consistent components are identified via spatial correlation. Group activation maps are generated in a second-level GLM analysis. FENICA is applied to data from three studies employing a wide range of stimulus and presentation designs. These are an event-related motor task, a block-design cognition task and an event-related chemosensory experiment. In all cases, the group maps identified by FENICA as being the most consistent over subjects correspond to task activation. There is good agreement between FENICA results and regions identified in prior GLM-based studies. In the chemosensory task, additional regions are identified by FENICA and temporal concatenation ICA that we show is related to the stimulus, but exhibit a delayed response. FENICA is a fully exploratory method that allows activation to be identified without assumptions about temporal evolution, and isolates activation from other sources of signal fluctuation in fMRI. It has the advantage over other gICA methods that it is computationally undemanding, spotlights components relating to activation rather than artefacts, allows the use of familiar statistical thresholding through deployment of a higher level GLM analysis and can be applied to studies where the paradigm is different for all subjects.

Potential impact of a 32-channel receiving head coil technology on the results of a functional MRI paradigm.

PURPOSE: The authors investigated the potential of a 32-channel (32ch) receiving head coil for functional magnetic resonance imaging (fMRI) compared to a standard eight-channel (8ch) coil using a motor task. MATERIAL AND METHODS: Brain activation was analyzed in 14 healthy right-handed subjects performing finger tapping with the right index finger (block design) during two experimental sessions, one with the 8ch and one with the 32ch coil (applied in a pseudorandomized order). Additionally, a phantom study was performed to compare signal-to-noise ratios (SNRs) of both coils. RESULTS: During both fMRI sessions, analysis of motor conditions resulted in an activation of the left "hand knob" (precentral gyrus). Application of the 32ch coil obtained additional activation clusters in the right cerebellum, left superior frontal gyrus (SMA), left supramarginal gyrus, and left postcentral gyrus. The phantom study revealed a significantly higher SNR for the 32ch coil compared to the 8ch coil in superficial cortical areas located near the surface of the brain. CONCLUSION: The 32ch technology has a potential impact on fMRI studies, especially in paradigms that result in activation of cortical areas located near the surface of the brain.