Prognostic value of CT attenuation and FDG uptake of adipose tissue in patients with pancreatic adenocarcinoma.

AIM: To investigate the prognostic significance of computed tomography (CT) attenuation and 2-[18F]-fluoro-2-deoxy-d-glucose (FDG) uptake in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) for predicting overall survival (OS) in patients with pancreatic adenocarcinoma. MATERIALS AND METHODS: Data were collected retrospectively from 66 patients with pancreatic adenocarcinoma who had undergone pretreatment combined FDG positron-emission tomography (PET)/CT imaging and subsequent curative or palliative treatment. Metabolic parameters of primary tumour including total lesion glycolysis (TLG) and heterogeneity factor were measured. Volume, CT attenuation (attenuation), and FDG uptake of SAT and VAT were derived from PET/CT acquisitions. Survival analysis using Cox proportional hazard modelling was performed to assess the relationship between both attenuation and FDG uptake of fat tissue and OS. RESULTS: During follow-up, 33 patients (50%) died and the median OS was 12 months. There were significant positive correlations between attenuation and mean standardised uptake values of both SAT (p<0.001, r=0.697) and VAT (p<0.001, r=0.742). Attenuation and FDG uptake of adipose tissue were significantly associated with heterogeneity factor and T stage. Patients with high FDG uptake and attenuation of SAT and VAT had significantly worse OS than those with low values. On multivariate analysis, attenuation of SAT (p=0.047) and VAT (p=0.021), and FDG uptake of VAT (p=0.005) were correlated significantly with OS after adjusting for age, sex, body mass index, TNM stage, and TLG. CONCLUSIONS: CT attenuation of SAT and VAT, and FDG uptake of VAT significantly correlated with OS in patients with pancreatic adenocarcinoma, independent of TNM staging and TLG.

Changes in cognitive function and brain glucose metabolism in elderly women with subjective memory impairment: a 24-month prospective pilot study.

OBJECTIVES: Subjective memory impairment (SMI) may precede mild cognitive impairment (MCI) stage and would offer an earlier therapeutic opportunity than MCI would. However, it is not clear whether complaints of forgetfulness are truly reflective of objective memory dysfunction or of impairments in other cognitive domains. The aim of this current longitudinal study was to investigate changes in various cognitive functions and in regional cerebral metabolic rate of glucose (rCMRglc) among elderly women with SMI. MATERIALS AND METHODS: Clinical evaluation, comprehensive neuropsychological test, and 18 F-fluoro-2-deoxyglucose positron emission tomography scans were conducted on 24 women with SMI at the baseline and 24-month follow-up. Changes in the cognitive domain scores and rCMRglc were assessed, and the relationships between them were analyzed. RESULTS: All participants stayed in SMI all the way till the follow-up, not converted to MCI or dementia. A significant reduction in executive function was found (mean difference in z-score: -0.21, P = 0.02) without changes in other cognitive domains. Declines in rCMRglc were detected in the left superior temporal gyrus, right posterior cingulate gyrus, left parahippocampal gyrus, right lingual gyrus, and right angular gyrus. The change in executive function had a positive correlation with the percent change of rCMRglc in the right posterior cingulate gyrus (ß = 0.43, P = 0.02). CONCLUSIONS: Our findings suggest that elderly women with SMI symptoms should be carefully monitored for declines in executive function and related brain glucose metabolism over time.

Predisposition to and effects of methamphetamine use on the adolescent brain.

Adolescence is a period of heightened vulnerability both to addictive behaviors and drug-induced brain damage. Yet, only limited information exists on the brain mechanisms underlying these adolescent-specific characteristics. Moreover, distinctions in brain correlates between predisposition to drug use and effects of drugs in adolescents are unclear. Using cortical thickness and diffusion tensor image analyses, we found greater and more widespread gray and white matter alterations, particularly affecting the frontostriatal system, in adolescent methamphetamine (MA) users compared with adult users. Among adolescent-specific gray matter alterations related to MA use, smaller cortical thickness in the orbitofrontal cortex was associated with family history of drug use. Our findings highlight that the adolescent brain, which undergoes active myelination and maturation, is more vulnerable to MA-related alterations than the adult brain. Furthermore, MA-use-related executive dysfunction was greater in adolescent MA users than in adult users. These findings may provide explanation for the severe behavioral complications and relapses that are common in adolescent-onset drug addiction. Additionally, these results may provide insights into distinguishing the neural mechanisms that underlie the predisposition to drug addiction from effects of drugs in adolescents.

Alteration of ictal and interictal perfusion in patients with paroxysmal kinesigenic dyskinesia.

Although previous cerebral blood flow studies have suggested that the basal ganglia or thalamus are involved in the pathogenesis of paroxysmal kinesigenic dyskinesia (PKD), the precise anatomic substrate or pathophysiological networks associated with PKD remain unclear. Here, ictal and interictal single photon emission computed tomography (SPECT) in 2 patients with idiopathic PKD compared to 6 age-matched normal controls and the perfusion findings of subtraction ictal SPECT co-registered to MRI (SISCOM) in 1 patient are reported. The interictal and ictal perfusion changes were different in each of the patients and there were no consistent anatomic substrates observed. 2 patients had significant perfusion changes in the left frontal/temporal cortices compared to controls, whereas the others showed an increased uptake of 99mTc-ethyl cysteinate dimer (ECD) in the left occipital area on subtraction SPECT imaging. The results of this study suggest that the pathophysiology of PKD cannot be simply explained by lesions of the basal ganglia or thalamus, and that other associated areas of the cortex are likely involved in these movement disorders.

Brain activation by visual erotic stimuli in healthy middle aged males.

The objective of the present study was to identify brain centers, whose activity changes are related to erotic visual stimuli in healthy, heterosexual, middle aged males. Ten heterosexual, right-handed males with normal sexual function were entered into the present study (mean age 52 years, range 46-55). All potential subjects were screened over 1 h interview, and were encouraged to fill out questionnaires including the Brief Male Sexual Function Inventory. All subjects with a history of sexual arousal disorder or erectile dysfunction were excluded. We performed functional brain magnetic resonance imaging (fMRI) in male volunteers when an alternatively combined erotic and nonerotic film was played for 14 min and 9 s. The major areas of activation associated with sexual arousal to visual stimuli were occipitotemporal area, anterior cingulate gyrus, insula, orbitofrontal cortex, caudate nucleus. However, hypothalamus and thalamus were not activated. We suggest that the nonactivation of hypothalamus and thalamus in middle aged males may be responsible for the lesser physiological arousal in response to the erotic visual stimuli.

Role of TrkB in the anxiolytic-like and antidepressant-like effects of vagal nerve stimulation: Comparison with desipramine.

A current hypothesis regarding the mechanism of antidepressant (AD) action suggests the involvement of brain-derived neurotrophic factor (BDNF). Consistent with this hypothesis, the receptor for BDNF (and neurotrophin 4/5 (NT-4/5)), Tropomyosin-related kinase B (TrkB), is activated in rodents by treatment with classical AD drugs. Vagal nerve stimulation (VNS), a therapy for treatment resistant depression (TRD), also activates TrkB in rodents. However, the role of this receptor in the therapeutic effects of VNS is unclear. In the current study, the involvement of TrkB in the effects of VNS was investigated in rats using its inhibitor, K252a. Anxiolytic-like and AD-like effects were analyzed using the novelty suppressed feeding test (NSFT) and forced swim test (FST), respectively. K252a blocked the anxiolytic-like effect of chronic VNS treatment and the AD-like effect of acute VNS treatment. By contrast, blocking TrkB did not prevent either the anxiolytic-like or AD-like effect of chronic treatment with desipramine (DMI), a selective noradrenergic reuptake inhibitor; it did, however, block the acute effect of DMI in the FST. To examine whether the activation of TrkB caused by either VNS or DMI is ligand-dependent, use was made of TrkB-Fc, a molecular scavenger for ligands of TrkB. Intraventricular administration of TrkB-Fc blocked the acute activation of TrkB induced by either treatment, indicating that treatment-induced activation of this receptor is ligand-dependent. The behavioral results highlight differences in the involvement of TrkB in the chronic effects of an AD drug and a stimulation therapy as well as its role in acute versus chronic effects of DMI.

Evaluation of 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography in rat models with hepatocellular carcinoma with liver cirrhosis.

Liver cirrhosis is a predominant risk factor for hepatocellular carcinoma (HCC). However, the exact mechanism of the progression from cirrhosis to cancer remains unclear. The uptake of 2-[(18)F]-fluoro-2-deoxy-D-glucose ((18)F-FDG) is widely used as a marker of increased glucose metabolism to monitor the progression of cancer with positron emission tomography (PET)/computed tomography (CT). Here we investigated the feasibility of using (18)F-FDG PET/CT in the diethylnitrosamine (DEN) mediated experimental hepatocellular carcinoma model. Rats received weekly intraperitoneal injections of DEN for 16 weeks for induction of HCC. We recorded starting from 0 days or 0 weeks after the last DEN injection. The weight and survival rate of rats were then measured. Also, an (18)F-FDG PET scan and serum analysis were performed at minus 2, 0, plus 2, and plus 4 weeks after the last DEN injection. The body weight of rats was maintained between 350 g and 370 g during 14 and 20 weeks, and the rats were euthanized at 35 days after the last DEN injection. The serum levels of alanine transaminase (ALT), aspartate transaminase (AST), and alkaline phosphate (ALP) were significantly higher at zero weeks after the last DEN injection. The (18)F-FDG uptake for the quantitative evaluation of HCC was done by measuring the region of interest (ROI). At minus two weeks after the last DEN injection, the ROI of rats had significantly increased compared to the normal group, in a time-dependent manner. These results suggest that FDG uptake serves as a good screening test to evaluate the feasibility of DEN-induced HCC.

Muscular sarcoidosis: Ga-67 scintigraphy and magnetic resonance imaging.

Ga-67 scintigraphy is helpful in the assessment of active extrapulmonary sarcoidosis. Muscular involvement of sarcoidosis is often asymptomatic or nonspecific, and laboratory examinations do not provide convincing evidence of muscular involvement. The authors report a case of muscular sarcoidosis detected by Ga-67 scintigraphy. In a patient who had fever and arthralgia of both knee joints, Ga-67 scintigraphy showed mediastinal and hilar involvement of sarcoidosis with unexpected extensive muscular uptake. Magnetic resonance imaging revealed in detail intramuscular infiltration of sarcoid granuloma. Ga-67 scintigraphy is useful in detecting inflammatory muscular involvement of sarcoidosis and other multiorgan involvement.

A new reference line for the brain CT: the tuberculum sellae-occipital protuberance line is parallel to the anterior/posterior commissure line.

BACKGROUND AND PURPOSE: CT and MR imaging of the brain have diverged reference lines. Modified Talairach anterior/posterior commissure (ACPC) line is widely accepted as the standard for clinical brain MR imaging, while orbitomeatal line (OML) is used for CT. This study sought to determine an appropriate reference line for brain CT parallel to the ACPC line. MATERIALS AND METHODS: We measured the angles between the ACPC line and the OML, the line connecting the tuberculum sellae and the internal occipital protuberance (TS-IOP line), and the line connecting the tuberculum sellae and the external occipital protuberance (TS-EOP line) on midsagittal brain MR images of 223 patients. In addition, with the hard palate as the basis, the angles to the ACPC line in the brain MR images and new reference line on the brain CT images from the same patient were measured, and the difference between the 2 angles was calculated in 30 patients. In the same method, the angles to the OML in the brain CT images and the ACPC line on the brain MR images were measured, and their difference was calculated in 30 patients. Then the 2 difference values were compared with verification of the new reference line. RESULTS: The angles between the ACPC line and both the TS-IOP line (0.0 degrees +/- 4.0 degrees ) and the TS-EOP line (0.8 degrees +/- 3.2 degrees ) were significantly smaller than the angles between the ACPC line and the OML (-12.6 degrees +/- 4.2 degrees ; P < .05). In actual scanned images, the angle differences between the TS-OP (TS-IOP + TS-EOP) line and the ACPC line (0.3 degrees +/- 4.5 degrees ) were statistically smaller than the angles between the OML and the ACPC line (-6.6 degrees +/- 3.9 degrees ; P < .05). CONCLUSIONS: TS-OP lines are nearly parallel to the ACPC line.

Evidence of thalamic disinhibition in patients with hemichorea: semiquantitative analysis using SPECT.

OBJECTIVES: Hemichorea sometimes occurs after lesions that selectively involve the caudate nucleus, putamen, and globus pallidus. Some reports have hypothesised that the loss of subthalamic nucleus control on the internal segment of the globus pallidus, followed by the disinhibition of the thalamus may contribute to chorea. However, the pathophysiology is poorly understood. Therefore, clinicoradiological localisation was evaluated and a comparison of the haemodynamic status of the basal ganglia and thalamus was made. METHODS: Six patients presenting with acute onset of hemichorea were assessed. Neuroimaging studies, including MRI and SPECT examinations in addition to detailed biochemical tests, were performed. A semiquantitative analysis was performed by comparing the ratio of blood flow between patients and normal controls. In addition, the ratio of perfusion asymmetry was calculated as the ratio between each area contralateral to the chorea and that homolateral to the chorea. The comparison was made with a two sample t test. RESULTS: The causes of hemichorea found consisted of four cases of acute stroke, one non-ketotic hyperglycaemia, and one systemic lupus erythematosus. Brain MRI indicated lesion sites in the contralateral putamen, globus pallidus, caudate nucleus, and subthalamic nucleus. A significant decrease in the ratio of blood flow in the basal ganglia contralateral to the chorea and a significant increase in the thalamus was found when comparing the perfusion asymmetries, which were calculated as the ratio of cerebral blood flow (CBF) for each region to that in the homolateral occipital area (p<0.05). CONCLUSION: An alteration in CBF in both the contralateral thalamus and basal ganglia reflect the loss of pallidal inhibitory input from the pallidum to the thalamus. This change in CBF may be one of epiphenomena, which implicates an occurrence of hemichorea in humans.