Hui Joong Lee

A Proposal for a Thyroid Imaging Reporting and Data System for Ultrasound Features of Thyroid Carcinoma

BACKGROUND Several thyroid ultrasound (TUS) findings have been associated with an increased risk for thyroid cancer; however, there is no consensus as to the format and style for reporting the results of TUS. The objective of this study was to discover the features indicative of malignancy in thyroid nodules based on TUS, generate an equation using these features that would be predictive of malignancy in thyroid nodules, and stratify the results of this equation into TUS categories reflecting the probability of malignancy. METHODS We obtained odds ratios of TUS findings indicative of malignancy and probability of malignancy for each nodule as determined by logistic regression analysis of ultrasound (US) findings in 1694 patients who had US-guided fine-needle aspiration biopsy. We then generated an equation to predict the probability of malignancy based on TUS and developed categories ranging from lowest to highest probability of malignancy. We evaluated the reliability of this equation and the categories using cytology and histopathology information regarding malignancy in the thyroid nodules. RESULTS We characterized 12 aspects of thyroid nodules as seen on TUS and developed an equation to predict P(us), the probability of a nodule being malignant based on these US findings. The equation was P(us) = 1/(1 + e(-z)), where e is the mathematical constant 2.71828 and z is the logit of malignant thyroid nodule. P(us) was stratified into five categories based on the probability of a nodule being malignant as indicated by the findings (TUS 1, benign; TUS 2, probably benign; TUS 3, indeterminate; TUS 4, probably malignant; TUS 5, malignant). There was a significant correlation between the cytological category and the TUS 1 through TUS 5 categories (r = 0.491, p < 0.001). CONCLUSIONS We propose an equation to predict the probability of malignancy in thyroid nodules based on 12 features of thyroid nodules as noted on TUS. This equation, and the stratification of its results into categories, should be useful in reporting the findings of US for thyroid nodules and in guiding management decisions.

Ultrasonography Diagnosis and Imaging-Based Management of Thyroid Nodules: Revised Korean Society of Thyroid Radiology Consensus Statement and Recommendations

The rate of detection of thyroid nodules and carcinomas has increased with the widespread use of ultrasonography (US), which is the mainstay for the detection and risk stratification of thyroid nodules as well as for providing guidance for their biopsy and nonsurgical treatment. The Korean Society of Thyroid Radiology (KSThR) published their first recommendations for the US-based diagnosis and management of thyroid nodules in 2011. These recommendations have been used as the standard guidelines for the past several years in Korea. Lately, the application of US has been further emphasized for the personalized management of patients with thyroid nodules. The Task Force on Thyroid Nodules of the KSThR has revised the recommendations for the ultrasound diagnosis and imaging-based management of thyroid nodules. The review and recommendations in this report have been based on a comprehensive analysis of the current literature and the consensus of experts.

Increased power spectral density in resting-state pain-related brain networks in fibromyalgia.

Summary Higher power spectral density in patients with fibromyalgia may implicate the enhanced resting‐state baseline neural activity in several brain regions associated with pain processing. ABSTRACT Fibromyalgia (FM), characterized by chronic widespread pain, is known to be associated with heightened responses to painful stimuli and atypical resting‐state functional connectivity among pain‐related regions of the brain. Previous studies of FM using resting‐state functional magnetic resonance imaging (rs‐fMRI) have focused on intrinsic functional connectivity, which maps the spatial distribution of temporal correlations among spontaneous low‐frequency fluctuation in functional MRI (fMRI) resting‐state data. In the current study, using rs‐fMRI data in the frequency domain, we investigated the possible alteration of power spectral density (PSD) of low‐frequency fluctuation in brain regions associated with central pain processing in patients with FM. rsfMRI data were obtained from 19 patients with FM and 20 age‐matched healthy female control subjects. For each subject, the PSDs for each brain region identified from functional connectivity maps were computed for the frequency band of 0.01 to 0.25 Hz. For each group, the average PSD was determined for each brain region and a 2‐sample t test was performed to determine the difference in power between the 2 groups. According to the results, patients with FM exhibited significantly increased frequency power in the primary somatosensory cortex (S1), supplementary motor area (SMA), dorsolateral prefrontal cortex, and amygdala. In patients with FM, the increase in PSD did not show an association with depression or anxiety. Therefore, our findings of atypical increased frequency power during the resting state in pain‐related brain regions may implicate the enhanced resting‐state baseline neural activity in several brain regions associated with pain processing in FM.

Working Memory Impairment in Fibromyalgia Patients Associated with Altered Frontoparietal Memory Network

Background Fibromyalgia (FM) is a disorder characterized by chronic widespread pain and frequently associated with other symptoms. Patients with FM commonly report cognitive complaints, including memory problem. The objective of this study was to investigate the differences in neural correlates of working memory between FM patients and healthy subjects, using functional magnetic resonance imaging (MRI). Methodology/Principal Findings Nineteen FM patients and 22 healthy subjects performed an n-back memory task during MRI scan. Functional MRI data were analyzed using within- and between-group analysis. Both activated and deactivated brain regions during n-back task were evaluated. In addition, to investigate the possible effect of depression and anxiety, group analysis was also performed with depression and anxiety level in terms of Beck depression inventory (BDI) and Beck anxiety inventory (BAI) as a covariate. Between-group analyses, after controlling for depression and anxiety level, revealed that within the working memory network, inferior parietal cortex was strongly associated with the mild (r = 0.309, P = 0.049) and moderate (r = 0.331, P = 0.034) pain ratings. In addition, between-group comparison revealed that within the working memory network, the left DLPFC, right VLPFC, and right inferior parietal cortex were associated with the rating of depression and anxiety? Conclusions/Significance Our results suggest that the working memory deficit found in FM patients may be attributable to differences in neural activation of the frontoparietal memory network and may result from both pain itself and depression and anxiety associated with pain.

Neural correlates of motor imagery for elite archers

Motor imagery is a mental rehearsal of simple or complex motor acts without overt body movement. It has been proposed that the association between performance and the mental rehearsal period that precedes the voluntary movement is an important point of difference between highly trained athletes and beginners. We compared the activation maps of elite archers and nonarchers during mental rehearsal of archery to test whether the neural correlates of elite archers were more focused and efficiently organised than those of nonarchers. Brain activation was measured using functional MRI in 18 right‐handed elite archers and 18 right‐handed nonarchers. During the active functional MRI imagery task, the participants were instructed to mentally rehearse their archery shooting from a first‐person perspective. The active imagery condition was tested against the nonmotor imagery task as a control condition. The results showed that the premotor and supplementary motor areas, and the inferior frontal region, basal ganglia and cerebellum, were active in nonarchers, whereas elite archers showed activation primarily in the supplementary motor areas. In particular, our result of higher cerebellar activity in nonarchers indicates the increased participation of the cerebellum in nonarchers when learning an unfamiliar archery task. Therefore, the difference in cerebellar activation between archers and nonarchers provides evidence of the expertise effect in the mental rehearsal of archery. In conclusion, the relative economy in the cortical processes of elite archers could contribute to greater consistency in performing the specific challenge in which they are highly practised. Copyright

Neural correlates related to action observation in expert archers

A growing body of evidence suggests that activity of the mirror neuron system is dependent on the observers motor experience of a given action. It remains unclear, however, whether activity of the mirror neuron system is also associated with the observers motor experience in sports game. Therefore, the aim of the present study is to investigate differences in activation of the mirror neuron system during action observation between experts and non-archer control subjects. We used video of Western-style archery in which participants were asked to watch the archery movements. Hyperactivation of the premotor and inferior parietal cortex in expert archers relative to non-archer control subjects suggests that the human mirror neuron system could contain and expand representations of the motor repertoire. The fact that dorsomedial prefrontal cortex was more active in expert archers than in non-archer control subjects indicates a spontaneous engagement of theory of mind in experts when watching video of Western-style archery. Compared with the non-archer control subjects, expert archers showed greater activation in the neural system in regions associated with episodic recall from familiar and meaningful information, including the cingulate cortex, retrosplenial cortex, and parahippocampal gyrus. The results demonstrate that expertise effects stimulate brain activity not only in the mirror neuron system but also in the neural networks related to theory of mind and episodic memory.

Altered white matter microstructural integrity revealed by voxel-wise analysis of diffusion tensor imaging in welders with manganese exposure.

Chronic exposure to manganese (Mn), which can be an occupational hazard or can result from liver failure, is associated with adverse motor and cognitive outcomes. Evidence from previous neuroimaging and magnetic resonance spectroscopy studies suggested alteration of function in Mn-exposed brains. However, the effect of chronic exposure of the human brain to Mn on white matter (WM) structure has not yet been determined. In the present study, we used diffusion tensor imaging (DTI) to investigate whether welders exposed to Mn demonstrate differences in WM integrity, compared with control subjects. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were measured on a voxel-wise basis in 30 male welders with exposure to Mn and in 19 age- and gender-matched control subjects. Direct comparison between welders and controls using investigator-independent Statistical Parametric Mapping (SPM) voxel-wise analysis of DTI metrics revealed a reduction of FA in the corpus callosum (CC) and frontal WM in Mn-exposed welders. Further, marked increases in RD and negligible changes in AD suggested that the microstructural changes in the CC and frontal WM result from compromised radial directionality of fibers in these areas, caused primarily by demyelination. Correlation analysis with neurobehavioral performance also suggested that the microstructural abnormalities were associated with subtle motor and cognitive differences in welders.

Alterations in cortical activity of male methamphetamine abusers performing an empathy task: fMRI study.

We investigate possible differences in neural correlates of empathy processing between abstinent methamphetamine (MA) abusers and healthy subjects using functional magnetic resonance imaging (fMRI).

Reduced corpus callosum white matter microstructural integrity revealed by diffusion tensor eigenvalues in abstinent methamphetamine addicts

The purpose of the current study was to determine whether abstinent methamphetamine (MA) abusers demonstrate differences in white matter (WM) integrity of the corpus callosum (CC) due to possible neurotoxic effects of long-term MA abuse, compared with control subjects. In addition to fractional anisotropy (FA), the eigenvalues of the diffusion ellipsoid were used to evaluate the microstructural source of abnormal change in abstinent MA abusers if there occurred a difference in white matter integrity of the CC between healthy controls and abstinent MA abusers. Results showed significantly reduced FA in the genu of the corpus callosum in MA-dependent subjects compared with controls. Furthermore, the eigenvalues offered a unique opportunity to assess the microstructural source of abnormal changes in the genu of the CC. The relationships between Wisconsin Card Sorting Test (WCST) performance and the values of tensor measures also suggest that altered myelination is a possible source of FA reduction observed in the genu of the CC in MA abusers.

The differences in neural network activity between methamphetamine abusers and healthy subjects performing an emotion-matching task: functional MRI study

Methamphetamine (MA) abusers commonly exhibit socially problematic behaviors, such as diminished empathy, decreased emotional regulation and interpersonal violence, which may be attributable to alterations in emotional experience. However, few studies have used functional MRI to examine directly the emotional experience of threatening or fearful non‐face images in MA abusers. In this study, we investigated possible differences in neural correlates of negative emotional experiences between abstinent MA abusers and healthy subjects using complex visual scenes depicting fear or threat derived from the International Affective Picture System. In within‐group analyses, healthy subjects and MA abusers activated a similarly distributed cortical network, prominently including the amygdala, fusiform gyrus, parahippocampal gyrus, ventrolateral prefrontal cortex and inferior frontal cortex. In between‐group analyses, however, MA abusers showed a reduced activation in the bilateral dorsolateral prefrontal cortex and insula, and increased activation in the fusiform gyrus, hippocampus, parahippocampal gyrus and posterior cingulate cortex, relative to healthy subjects. Hypoactivation of the insula in MA abusers relative to healthy subjects suggests that the ability to have an emotional response to threatening scenes and empathy for anothers pain could be compromised in MA abusers. Hyperactivity in the fusiform gyrus, parahippocampal gyrus and posterior cingulate cortex in MA abusers relative to healthy subjects indicates that threatening and fearful images from the International Affective Picture System may remind MA abusers of episodic memory related to similar experiences. Therefore, functional impairment of these neural networks in MA abusers may contribute to altered emotional experience in social interactions, which could lead to increased negative mood and stress in interpersonal communication. Copyright