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The co-occurrence of hepatic cystic echinococcosis (CE) and alveolar echinococcosis (AE) is extremely rare. Here, we present the clinical manifestations and treatment outcomes of three cases with co-occurring CE and AE in the liver. Computed tomography (CT), magnetic resonance imaging and 18FFluorodeoxyglucose Positron Emission Tomography-CT were used for preoperative diagnosis. Specimens were taken intraoperatively and sent for pathological studies to confirm the coexistence of CE and AE by laminated membrane, daughter cysts or germinal layer and infiltration structure. Albendazole was prescribed after operation for 12 months. All patients were completely recovered and showed no recurrence at last follow-up. Therefore, surgical intervention and postoperative application of albendazole are recommended for patients with concurrence of hepatic AE and CE.
Rationale: Presurgical localization of the epileptogenic focus is critical to successful surgery. Traditionally, localization of the epileptogenic focus depends on seizure semiology, scalp video-electroencephalography (vEEG), magnetic resonance imaging (MRI), neuropsychological assessment, and, when needed, intracranial EEG (iEEG). We aimed to explore the role of positron emission tomography (PET) in the presurgical evaluation of patients with refractory epilepsy. Methods: A retrospective review was conducted on patients from London Health Sciences Centre (London, Ontario) with refractory epilepsy who underwent PET from September of 2011 to April of 2016. The accuracy of epileptogenic focus localization was compared between different investigative modalities (MRI, vEEG, iEEG, PET), and the outcomes were documented, including seizure freedom after surgical resection, improvement of seizure frequency, guidance for further investigations, and exclusion of patients from further evaluation. Patients who underwent surgery were followed up at 3 months and onward. Results: We identified 62 patients with refractory epilepsy who underwent PET. The mean age was 34 years (range=20-68). A total of 36 had concordant PET and vEEG findings: 6 had surgical resection and either became seizure-free (29.4%) or had improvement in seizure frequency (5.9%) at 3 months; 11 had surgical resection and either became seizure-free (29.4%) or had improvement in seizure frequency (35.3%) at 3 months, but required iEEG for final verification. Conclusions: PET has an important role in presurgical evaluation of patients with refractory epilepsy. It may allow resection of the epileptogenic focus without the need for iEEG, guiding intracranial electrode placement for further localization of the epileptogenic focus, or exclusion of patients from further evaluation.
Currently it is estimated that about 1 billion people globally have non-alcoholic fatty liver disease (NAFLD), a condition in which liver fat exceeds 5 % of liver weight in the absence of significant alcohol intake. Due to the central role of the liver in metabolism, the prevalence of NAFLD is increasing in parallel with the prevalence of obesity, insulin resistance and other risk factors of metabolic diseases. However, the contribution of liver fat to the risk of type 2 diabetes mellitus and CVD, relative to other ectopic fat depots and to other risk markers, is unclear. Various studies have suggested that the accumulation of liver fat can be reduced or prevented via dietary changes. However, the amount of liver fat reduction that would be physiologically relevant, and the timeframes and dose–effect relationships for achieving this through different diet-based approaches, are unclear. Also, it is still uncertain whether the changes in liver fat per se or the associated metabolic changes are relevant. Furthermore, the methods available to measure liver fat, or even individual fatty acids, differ in sensitivity and reliability. The present report summarises key messages of presentations from different experts and related discussions from a workshop intended to capture current views and research gaps relating to the points above.
Objectives: We examined florbetapir positron emission tomography (PET) amyloid scans across stages of preclinical Alzheimer’s disease (AD) in cortical, allocortical, and subcortical regions. Stages were characterized using empirically defined methods. Methods: A total of 312 cognitively normal Alzheimer’s Disease Neuroimaging Initiative participants completed a neuropsychological assessment and florbetapir PET scan. Participants were classified into stages of preclinical AD using (1) a novel approach based on the number of abnormal biomarkers/cognitive markers each individual possessed, and (2) National Institute on Aging and the Alzheimer’s Association (NIA-AA) criteria. Preclinical AD groups were compared to one another and to a mild cognitive impairment (MCI) sample on florbetapir standardized uptake value ratios (SUVRs) in cortical and allocortical/subcortical regions of interest (ROIs). Results: Amyloid deposition increased across stages of preclinical AD in all cortical ROIs, with SUVRs in the later stages reaching levels seen in MCI. Several subcortical areas showed a pattern of results similar to the cortical regions; however, SUVRs in the hippocampus, pallidum, and thalamus largely did not differ across stages of preclinical AD. Conclusions: Substantial amyloid accumulation in cortical areas has already occurred before one meets criteria for a clinical diagnosis. Potential explanations for the unexpected pattern of results in some allocortical/subcortical ROIs include lack of correspondence between (1) cerebrospinal fluid and florbetapir PET measures of amyloid, or between (2) subcortical florbetapir PET SUVRs and underlying neuropathology. Findings support the utility of our novel method for staging preclinical AD. By combining imaging biomarkers with detailed cognitive assessment to better characterize preclinical AD, we can advance our understanding of who is at risk for future progression. (JINS, 2016, 22, 978–990)
To review our experience of managing patients with a dual diagnosis of metastatic cutaneous squamous cell carcinoma in the head and neck region and low-grade non-Hodgkin lymphoma. The secondary aim was to evaluate the utility of 18F-fluorodeoxyglucose positron emission tomography during diagnosis.
Patients diagnosed with metastatic cutaneous squamous cell carcinoma of the head and neck and low-grade non-Hodgkin lymphoma, in a five-year period, were identified. Patient, tumour and treatment characteristics were identified. 18F-fluorodeoxyglucose positron emission tomography imaging was reviewed and correlated with histopathology findings.
Eight patients were identified. There was a delay in diagnosis of metastatic squamous cell carcinoma in two patients. 18F-fluorodeoxyglucose positron emission tomography differentiated metastatic squamous cell carcinoma from low-grade non-Hodgkin lymphoma with a sensitivity of 88.2 per cent and a specificity of 94.7 per cent. In 38 per cent of patients, compromises in management had to be made.
The management of metastatic squamous cell carcinoma can be challenging in patients with low-grade non-Hodgkin lymphoma. 18F-fluorodeoxyglucose positron emission tomography can be useful in the diagnosis of metastatic squamous cell carcinoma in patients with low-grade non-Hodgkin lymphoma.
The role of fludeoxyglucose F 18 positron emission tomography (PET) in the presurgical evaluation of patients with medically intractable epilepsy continues to be refined. The purpose of this study was to systematically review the literature to assess the diagnostic accuracy and utility of PET in this setting. Thirty-nine studies were identified through MEDLINE and EMBASE databases that met the inclusion criteria. In adult patients, PET hypometabolism showed a 56 to 90% agreement with seizure onset localized by intracranial electroencephalogram (pediatric: 21 to 86%). In temporal lobe epilepsy patients with good surgical outcome, PET displayed moderate to high sensitivity in localizing the seizure focus (range: 71 to 89%). The sensitivity increased by 8 to 23% when PET results were combined with magnetic resonance imaging or electroencephalogram. PET has been shown to affect patient management by improving the guidance of intracranial electrodes placement, altering the decision to perform surgery, or excluding patients from further evaluation.
Anisotropy and compositional and structural heterogeneity in clays are causes of considerable deviations from homogeneous diffusion, in particular in terms of direction-dependent transport rates and preferred transport zones. Conventional diffusion experiments, in which the sample is treated as a homogeneous black box in a concentration gradient, are interminable and insensitive to spatial effects. In contrast, tomographic imaging methods are capable of both reducing the amount of observation time required and revealing space-dependent features of the diffusion process.
In the present study, positron-emission-tomography (PET) was applied as the most sensitive quantitative spatiotemporal tomographic modality for direct observation of positron-emitting radiotracers in opaque media at reasonable resolution (1 mm) on a laboratory scale (100 mm).
Geoscientific applications of PET, or GeoPET, have revealed anisotropic and heterogeneous effects in diffusion experiments that have been conducted on Opalinus clay samples of different sizes, as well as on other rock types. Applying the Comsol Optimization Module to 2D-image sections of the PET tomograms, effective parameter values were derived, thereby quantifying the anisotropic diffusion.
Objective: The radiological and clinical significance of a dilated Virchow-Robin space (dVRS) in the striatum (STR) remains unclear. We investigated the role of dVRS in STR on parkinsonism and dopamine transporter positron emission tomography (DaT-PET) findings. Methods: Patients with parkinsonism who underwent both brain magnetic resonance imaging and DaT-PET were included. Clinical status was evaluated by Hoehn and Yahr (HY) stage, Korean-Mini Mental Status Examination (K-MMSE), Montreal Cognitive Assessment Korea (MoCA-K), and Frontal Assessment Battery (FAB). dVRS was assessed by semi-quantitative and quantitative scales in each of the three segments of STR (caudate nuclei, anterior and posterior putamen) and was expressed as a dVRS score. DaT-PET was qualitatively assessed as either normal or abnormal in each segment. The relationship between dVRS and DaT-PET abnormality (ab-DaT-PET) was designated in each segment as either concordant or discordant. A concordant segment was defined by the presence of dVRS with ab-DaT-PET [Concordance rate (CR)=number of concordant segments/number of concordant and discordant segments]. Results: Eleven patients were included. There was no significant correlation between the presence of dVRS and ab-DaT-PET. The mean CR was 0.39. CR was not significantly correlated with any clinical or neuroimaging scales. The dVRS score was significantly correlated with K-MMSE, MoCA-K, and FAB (r=−0.675, −0.847, and −0.868, respectively) but not with HY stage. Conclusion: dVRS in STR played no significant role on dopaminergic innervation revealed by DaT-PET and made little contribution to clinical parkinsonism; however, it was correlated with cognitive impairment.
Magnetic seizure therapy (MST), despite being in an early phase of clinical research, has been demonstrated to be associated with antidepressant efficacy. However, safety, tolerability and efficacy data in connection with functional brain activity from larger samples are lacking. The aim of this study was to determine clinical and cognitive effects of MST and the influence of MST on regional brain glucose metabolism.
Twenty-six patients suffering from treatment-resistant depression (TRD) underwent MST. Ten patients underwent a randomized trial and 16 patients an open-label study design. The primary outcome criterion was the severity of depressive symptoms assessed with the Hamilton Depression Rating Scale (HAMD). Depressive symptoms, tolerability and cognitive safety, along with social functioning and quality of life parameters, were assessed using various rating scales. A clinical follow-up visit 6 months following the completion of a course of MST and [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) scans of 12 patients were analysed.
A significant response to MST was demonstrated by 69% of the patient sample, with 46% meeting remission criteria. Anxiety ratings were significantly reduced in responders and their quality of life was improved. Half of the responders relapsed within 6 months. No cognitive side-effects were observed. FDG-PET scans showed a metabolic increase in the frontal cortex bilaterally and a decrease in the left striatum.
Robust antidepressant and anti-anxiety efficacy of MST was demonstrated, and found to be associated with localized metabolic changes in brain areas that are strongly implicated in depression. Thus, MST presents an effective, well-tolerated and safe treatment option for patients unable to respond to other forms of therapy for depression.
Renal metastasis is relatively unusual in patients with differentiated thyroid carcinoma.
The clinicoradiological parameters of a series of patients with differentiated thyroid carcinoma and renal metastasis were assessed, together with follow-up data.
Results and conclusion:
The series comprised 4 male patients over the age of 45 years with extensive disease at the primary site. Retro-sternal extension of a large goitre was observed in three patients. The primary tumour was 4 cm or larger in all patients (range, 4–14 cm), and three patients had associated lymph node metastasis. None had any genito-urinary symptoms at presentation. Two patients had isolated renal metastases with no other distant metastases, while the others had extensive multi-organ involvement. The bilateral occurrence of lesions was a hallmark, being observed in all cases. Ultrasound-guided fine needle aspiration cytology and 131I scintigraphy were pivotal in confirming the diagnosis. Evidence of ‘flip-flop’ between 131I study and fluoro-deoxyglucose positron emission tomography was noted in one patient, while the other three demonstrated concordant lesions in both modalities. At a minimum follow-up period of four years after diagnosis, three patients demonstrated stable disease with radioiodine therapy, and one had expired due to a poorly differentiated lung carcinoma which developed subsequently.
Previous work has shown that hunger and food intake are lower in individuals on high-protein (HP) diets when combined with low carbohydrate (LC) intakes rather than with moderate carbohydrate (MC) intakes and where a more ketogenic state occurs. The aim of the present study was to investigate whether the difference between HPLC and HPMC diets was associated with changes in glucose and ketone body metabolism, particularly within key areas of the brain involved in appetite control. A total of twelve men, mean BMI 34·9 kg/m2, took part in a randomised cross-over trial, with two 4-week periods when isoenergetic fixed-intake diets (8·3 MJ/d) were given, with 30 % of the energy being given as protein and either (1) a very LC (22 g/d; HPLC) or (2) a MC (182 g/d; HPMC) intake. An 18fluoro-deoxyglucose positron emission tomography scan of the brain was conducted at the end of each dietary intervention period, following an overnight fast (n 4) or 4 h after consumption of a test meal (n 8). On the next day, whole-body ketone and glucose metabolism was quantified using [1,2,3,4-13C]acetoacetate, [2,4-13C]3-hydroxybutyrate and [6,6-2H2]glucose. The composite hunger score was 14 % lower (P= 0·013) for the HPLC dietary intervention than for the HPMC diet. Whole-body ketone flux was approximately 4-fold greater for the HPLC dietary intervention than for the HPMC diet (P< 0·001). The 9-fold difference in carbohydrate intakes between the HPLC and HPMC dietary interventions led to a 5 % lower supply of glucose to the brain. Despite this, the uptake of glucose by the fifty-four regions of the brain analysed remained similar for the two dietary interventions. In conclusion, differences in the composite hunger score observed for the two dietary interventions are not associated with the use of alternative fuels by the brain.
The present review describes brain imaging technologies that can be used to assess the effects of nutritional interventions in human subjects. Specifically, we summarise the biological relevance of their outcome measures, practical use and feasibility, and recommended use in short- and long-term nutritional studies. The brain imaging technologies described consist of MRI, including diffusion tensor imaging, magnetic resonance spectroscopy and functional MRI, as well as electroencephalography/magnetoencephalography, near-IR spectroscopy, positron emission tomography and single-photon emission computerised tomography. In nutritional interventions and across the lifespan, brain imaging can detect macro- and microstructural, functional, electrophysiological and metabolic changes linked to broader functional outcomes, such as cognition. Imaging markers can be considered as specific for one or several brain processes and as surrogate instrumental endpoints that may provide sensitive measures of short- and long-term effects. For the majority of imaging measures, little information is available regarding their correlation with functional endpoints in healthy subjects; therefore, imaging markers generally cannot replace clinical endpoints that reflect the overall capacity of the brain to behaviourally respond to specific situations and stimuli. The principal added value of brain imaging measures for human nutritional intervention studies is their ability to provide unique in vivo information on the working mechanism of an intervention in hypothesis-driven research. Selection of brain imaging techniques and target markers within a given technique should mainly depend on the hypothesis regarding the mechanism of action of the intervention, level (structural, metabolic or functional) and anticipated timescale of the intervention's effects, target population, availability and costs of the techniques.
Human impulsivity is a complex multidimensional construct encompassing cognitive, emotional, and behavioural aspects. Previous animal studies have suggested that striatal dopamine receptors play a critical role in impulsivity. In this study, we investigated the relationship between self-reported impulsiveness and dopamine D2/3 receptor availability in striatal subdivisions in healthy subjects using high-resolution positron emission tomography (PET) with [11C]raclopride.
Twenty-one participants completed 3-T magnetic resonance imaging and high-resolution PET scans with [11C]raclopride. The trait of impulsiveness was measured using the Barratt Impulsiveness Scale (BIS-11). Partial correlation analysis was performed between BIS-11 scores and D2/3 receptor availability in striatal subregions, controlling for the confounding effects of temperament characteristics that are conceptually or empirically related to dopamine, which were measured by the Temperament and Character Inventory.
The analysis revealed that the non-planning (p = 0.004) and attentional (p = 0.007) impulsiveness subscale scores on the BIS-11 had significant positive correlations with D2/3 receptor availability in the pre-commissural dorsal caudate. There was a tendency towards positive correlation between non-planning impulsiveness score and D2/3 receptor availability in the post-commissural caudate.
These results suggest that cognitive subtrait of impulsivity is associated with D2/3 receptor availability in the associative striatum that plays a critical role in cognitive processes involving attention to detail, judgement of alternative outcomes, and inhibitory control.
Positron emission tomography (PET) and more recently PET/computed tomography (CT) has been utilized as a measure of functional imaging for many decades. The manufacture of PET radiotracers for imaging molecular processes in the human brain begins with the production of the PET radioisotope using a cyclotron. A nuclear reaction takes place in the target between the particle and the atom of the target material that gives rise to the PET radioisotope. The radioisotope is then sent to the radiopharmacy where it is used in the preparation of a radiopharmaceutical. Different patient protocols for PET imaging with 18F fluorodeoxyglucose (18F-FDG) are present for oncological and cardiac indications. PET regional cerebral blood flow (rCBF) imaging with 15O-water can be quantified using a mathematical model using a diffusible tracer technique method. Software has been developed to assess imaging more quantitatively with comparison to normal subjects.
This chapter reviews the techniques currently applied to study brain function during sleep deprivation (SD) as opposed to the consequence of SD. It provides a bird's eye view of functional imaging studies performed on healthy young adult volunteers to date and comment on how this research has evolved the conceptualization of how SD modulates behavior. The first functional imaging studies involving SD utilized positron emission tomography (PET). Based on the initial findings, cognitive domain and task difficulty was proposed as determinants of the neural response to SD. It was postulated that changes in dopamine signaling in the SD state contributed to the change in functional connectivity, an idea reprised when discussing risky decision making in SD. The interaction of SD and circadian effects, including the effects of chronotype, could be a further target of functional neuroimaging studies, including the effect of countermeasures such as naps and stimulants.
This chapter reviews the neuroimaging findings devoted to the effects of treatment in narcolepsy. These studies involved functional neuroimaging methods such as single photon emission computed tomography (SPECT), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI). The majority of them focused on modafinil, with also early reports on amphetamines and methylphenidate. In narcoleptic patients single-dose treatment effects were also studied with fMRI. PET and SPECT were used to investigate brain activity changes induced by a prolonged administration of modafinil in narcoleptic patients. An 18F-fluorodeoxyglucose (18F-FDG) PET study evaluated brain glucose metabolism (CMRglu) during baseline wakefulness in eight patients and eight controls before and after two weeks of treatment with modafinil. Decreased CMRglu was observed in the brainstem, hypothalamus, thalamus, and mesiotemporal areas in narcoleptics compared to controls, both before and after treatment.
Radiotracer imaging methods such as single-photon emission computed tomography (SPECT) and positron emission tomography (PET) are well suited to provide information about the functional, metabolic, and molecular status of tissues and organs. Brain SPECT has a well-established role for a number of clinical indications. Cerebral perfusion studies are used in the evaluation of dementias, epilepsy, cerebrovascular disease, trauma, brain death, and to assist with neuropsychiatric evaluation. Brain function is evaluated at baseline, before and after pharmacotherapy or psychotherapy, and following a number of activation tasks to examine a large number of psychiatric conditions. The integration of SPECT and CT in a single imaging device facilitates anatomical localization of the radiopharmaceutical to differentiate physiological uptake from that associated with disease. SPECT and SPECT/CT is continuing to evolve with the introduction of new technologies that have the potential to improve performance beyond that possible with Anger's pioneering approach.
This chapter focuses on the principles of advanced neuroimaging and their current clinical applications and limitations. Xenon enhanced computed tomography imaging (Xe-CT) is used for the quantification of cerebral blood flow (CBF). Advanced magnetic resonance imaging (MRI) techniques enhance the evaluation of brain structure and/or function. Magnetic resonance angiography (MRA) is used for assessment of the integrity of arteries and veins in the human body. Magnetic resonance spectroscopy data are used to evaluate the composition and metabolic activity of the brain. Diffusion tensor imaging (DTI) is a special form of diffusion-weighted MRI that allows the assessment and visualization of white matter and its constituents on a millimeter-level scale. Arterial spin labeling allows for the characterization and direct visualization of blood low within brain tissue. Information derived from positron emission tomography (PET) data may prove useful in correlating functional and structural abnormalities, and identifying pathophysiological disturbances despite apparently normal brain structure.
It took almost a century and several discoveries in the seemingly unrelated field of quantum physics to allow researchers to be able to use changes in blood flow and volume to identify areas of neural activity. The most widely used techniques to do so include positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). In addition to measuring task-induced changes in cerebral blood flow (CBF) or cerebral metabolism, PET imaging can be used to directly and selectively assess the action of different neurotransmitters in the human brain in vivo. The change in the BOLD signal triggered by a brief neural event is known as the hemodynamic response (HDR). It is important to keep in mind that, as is the case with any experimental method, there are limitations and potential pitfalls that one needs to consider when designing, analyzing, or interpreting experiments using PET or fMRI.
The psychobiological model of personality by Cloninger and colleagues originally hypothesized that interindividual variability in the temperament dimension ‘harm avoidance’ (HA) is explained by differences in the activity of the brain serotonin system. We assessed brain serotonin transporter (5-HTT) density in vivo with positron emission tomography (PET) in healthy individuals with high or low HA scores using an ‘oversampling’ study design.
Subjects consistently in either upper or lower quartiles for the HA trait were selected from a population-based cohort in Finland (n = 2075) with pre-existing Temperament and Character Inventory (TCI) scores. A total of 22 subjects free of psychiatric and somatic disorders were included in the matched high- and low-HA groups. The main outcome measure was regional 5-HTT binding potential (BPND) in high- and low-HA groups estimated with PET and [11C]N,N-dimethyl-2-(2-amino-4-methylphenylthio)benzylamine ([11C]MADAM). In secondary analyses, 5-HTT BPND was correlated with other TCI dimensions.
5-HTT BPND did not differ between high- and low-HA groups in the midbrain or any other brain region. This result remained the same even after adjusting for other relevant TCI dimensions. Higher 5-HTT BPND in the raphe nucleus predicted higher scores in ‘self-directedness’.
This study does not support an association between the temperament dimension HA and serotonin transporter density in healthy subjects. However, we found a link between high serotonin transporter density and high ‘self-directedness’ (ability to adapt and control one's behaviour to fit situations in accord with chosen goals and values). We suggest that biological factors are more important in explaining variability in character than previously thought.