Mild cognitive impairment classification using combined structural and diffusion imaging biomarkers.

Alzheimer's disease is a multifactorial neurodegenerative disorder preceded by a prodromal stage called mild cognitive impairment (MCI). Early diagnosis of MCI is crucial for delaying the progression and optimizing the treatment. In this study we propose a random forest (RF) classifier to distinguish between MCI and healthy control subjects (HC), identifying the most relevant features computed from structural T1-weighted and diffusion-weighted magnetic resonance images (sMRI and DWI), combined with neuro-psychological scores. To train the RF we used a set of 60 subjects (HC = 30, MCI = 30) drawn from the Alzheimer's disease neuroimaging initiative database, while testing with unseen data was carried out on a 23-subjects Mexican cohort (HC = 12, MCI = 11). Features from hippocampus, thalamus and amygdala, for left and right hemispheres were fed to the RF, with the most relevant being previously selected by applying extra trees classifier and the mean decrease in impurity index. All the analyzed brain structures presented changes in sMRI and DWI features for MCI, but those computed from sMRI contribute the most to distinguish from HC. However, sMRI+DWI improves classification performance in training area under the receiver operating characteristic curve (AUROC = 93.5 ± 8%, accuracy = 88.8 ± 9%) and testing with unseen data (AUROC = 93.79%, accuracy = 91.3%), having a better performance when neuro-psychological scores were included. Compared to other classifiers the proposed RF provide the best performance for HC/MCI discrimination and the application of a feature selection step improves its performance. These findings imply that multimodal analysis gives better results than unimodal analysis and hence may be a useful tool to assist in early MCI diagnosis.

Neuroanatomical features and its usefulness in classification of patients with PANDAS.

OBJECTIVE: An obsessive-compulsive disorder (OCD) subtype has been associated with streptococcal infections and is called pediatric autoimmune neuropsychiatric disorders associated with streptococci (PANDAS). The neuroanatomical characterization of subjects with this disorder is crucial for the better understanding of its pathophysiology; also, evaluation of these features as classifiers between patients and controls is relevant to determine potential biomarkers and useful in clinical diagnosis. This was the first multivariate pattern analysis (MVPA) study on an early-onset OCD subtype. METHODS: Fourteen pediatric patients with PANDAS were paired with 14 healthy subjects and were scanned to obtain structural magnetic resonance images (MRI). We identified neuroanatomical differences between subjects with PANDAS and healthy controls using voxel-based morphometry, diffusion tensor imaging (DTI), and surface analysis. We investigated the usefulness of these neuroanatomical differences to classify patients with PANDAS using MVPA. RESULTS: The pattern for the gray and white matter was significantly different between subjects with PANDAS and controls. Alterations emerged in the cortex, subcortex, and cerebellum. There were no significant group differences in DTI measures (fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity) or cortical features (thickness, sulci, volume, curvature, and gyrification). The overall accuracy of 75% was achieved using the gray matter features to classify patients with PANDAS and healthy controls. CONCLUSION: The results of this integrative study allow a better understanding of the neural substrates in this OCD subtype, suggesting that the anatomical gray matter characteristics could have an immune origin that might be helpful in patient classification.

Colorectal Cancer: Causes and Evidence of Chemopreventive Treatments.

BACKGROUND: Colorectal cancer (CRC) is the second and third most frequent cancer in women and men, respectively; indeed, CRC is placed as the fourth world's most deadly cancer (after lung, liver, and stomach cancer). The incidence of CRC is strongly influenced by nutrition and the high fat/high carbohydrate Western-style diet. CRC is one of the most intensively studied cancer types, partly because of its high prevalence, but also because of the existence of its precursor lesions, tubular or villous adenomas, and more recently serrated adenomas. The morphological steps in the adenomacarcinoma sequence have been elucidated at a molecular level, which allow the identification of the genes responsible for CRC. Review and Conclusions: The main aim of this review is to provide data regarding the pathophysiological characteristics, molecular mechanisms as well as carcinogenic and chemopreventive agents for CRC, with emphasis on evidence supporting their efficacy. These compounds may modulate multiple signaling pathways involved in cell proliferation and apoptosis in transformed cells, they also enhance the host immune system and favor an effective treatment. Despite promising results from experimental studies, only a limited number of these compounds have been tested in clinical trials. The mechanistic spectrum and specificity of the action of phytochemicals represent a complex and evolving field of research.

Automated Classification of Severity in Cardiac Dyssynchrony Merging Clinical Data and Mechanical Descriptors.

Cardiac resynchronization therapy (CRT) improves functional classification among patients with left ventricle malfunction and ventricular electric conduction disorders. However, a high percentage of subjects under CRT (20%-30%) do not show any improvement. Nonetheless the presence of mechanical contraction dyssynchrony in ventricles has been proposed as an indicator of CRT response. This work proposes an automated classification model of severity in ventricular contraction dyssynchrony. The model includes clinical data such as left ventricular ejection fraction (LVEF), QRS and P-R intervals, and the 3 most significant factors extracted from the factor analysis of dynamic structures applied to a set of equilibrium radionuclide angiography images representing the mechanical behavior of cardiac contraction. A control group of 33 normal volunteers (28 ± 5 years, LVEF of 59.7% ± 5.8%) and a HF group of 42 subjects (53.12 ± 15.05 years, LVEF < 35%) were studied. The proposed classifiers had hit rates of 90%, 50%, and 80% to distinguish between absent, mild, and moderate-severe interventricular dyssynchrony, respectively. For intraventricular dyssynchrony, hit rates of 100%, 50%, and 90% were observed distinguishing between absent, mild, and moderate-severe, respectively. These results seem promising in using this automated method for clinical follow-up of patients undergoing CRT.

Neural Modulation in Aversive Emotion Processing: An Independent Component Analysis Study.

Emotional processing has an important role in social interaction. We report the findings about the Independent Component Analysis carried out on a fMRI set obtained with a paradigm of face emotional processing. The results showed that an independent component, mainly cerebellar-medial-frontal, had a positive modulation associated with fear processing. Also, another independent component, mainly parahippocampal-prefrontal, showed a negative modulation that could be associated with implicit reappraisal of emotional stimuli. Independent Component Analysis could serve as a method to understand complex cognitive processes and their underlying neural dynamics.

Normality index of ventricular contraction based on a statistical model from FADS.

Radionuclide-based imaging is an alternative to evaluate ventricular function and synchrony and may be used as a tool for the identification of patients that could benefit from cardiac resynchronization therapy (CRT). In a previous work, we used Factor Analysis of Dynamic Structures (FADS) to analyze the contribution and spatial distribution of the 3 most significant factors (3-MSF) present in a dynamic series of equilibrium radionuclide angiography images. In this work, a probability density function model of the 3-MSF extracted from FADS for a control group is presented; also an index, based on the likelihood between the control group's contraction model and a sample of normal subjects is proposed. This normality index was compared with those computed for two cardiopathic populations, satisfying the clinical criteria to be considered as candidates for a CRT. The proposed normality index provides a measure, consistent with the phase analysis currently used in clinical environment, sensitive enough to show contraction differences between normal and abnormal groups, which suggests that it can be related to the degree of severity in the ventricular contraction dyssynchrony, and therefore shows promise as a follow-up procedure for patients under CRT.

Factor analysis of ventricular contraction using SPECT-ERNA images.

Equilibrium radionuclide angiography images (ERNA) has been established as a useful modality for clinical evaluation of the ventricular function. Tomographic acquisition of ERNA (SPECT-ERNA) improves the quantification of ventricular function with planar ERNA, avoiding both the overlap of structures and the need of defining the best septal view which can be difficult in dilated ventricles. In this work we analyze the contribution and distribution of the most significant factors of dynamic structures (FADS), and propose an index based on the characterization of the normal contraction pattern, to quantify the ventricular contraction normality in a set of patients with clinical diagnosis of pulmonary arterial hypertension (PAH) using SPECT-ERNA. The statistical analysis shows significant differences between normal and PAH subjects in the models of left ventricle (LV) contraction pattern. This comparison shows that the LV has an abnormal contraction as a consequence of the pulmonary arterial hypertension.

Evaluación de la función y sincronía de la contracción ventricular en pacientes con enfermedad de Chagas en estadio de latencia / Evaluation of the function and ventricular synchrony in patients with latency stage of Chagas' disease

OBJECTIVE: To compare the left ventricular function and the ventricular synchrony in patients with Chagas disease in latency stage respect to a control group. METHODS: We analyze a prospective, comparative, transversal and non randomized study of the left ventricular function (LVF) and the ventricular contraction synchronicity (VCS) in 36 subjects with positive serology for Chagas disease (18 males and 18 females), with mean of 15 +/- 5-years-old. The findings were compared with respect to 23 control volunteers (11 males and 12 females) with mean of 28 +/- 5-years-old. LVF and VCS were evaluated using equilibrium radionuclide angiography images (ERNA). The comparison of both Chagas and control populations was carried out by t Student test for independent samples, considering a statistically significant value of p < 0.05. RESULTS: The parameters of the ventricular function and the ventricular synchronicity in subjects with positive serology for Chagas disease were not statistically different with respect to the parameters of the control group. However, although they have a homogeneous contraction, the mean time of contraction for the right and the left ventricle is statistically smaller with respect to the control group. CONCLUSIONS: In clinically incipient stages of Chagas disease we do not found abnormalities in the ventricular function and the ventricular synchronicity. It's necessary to consider the follow up of the studied populations using indices for the identification of abnormalities of the autonomic nervous system.

[Evaluation of the function and ventricular synchrony in patients with latency stage of Chagas' disease]. / Evaluación de la función y sincronía de la contracción ventricular en pacientes con enfermedad de Chagas en estadio de latencia.

OBJECTIVE: To compare the left ventricular function and the ventricular synchrony in patients with Chagas disease in latency stage respect to a control group. METHODS: We analyze a prospective, comparative, transversal and non randomized study of the left ventricular function (LVF) and the ventricular contraction synchronicity (VCS) in 36 subjects with positive serology for Chagas disease (18 males and 18 females), with mean of 15 +/- 5-years-old. The findings were compared with respect to 23 control volunteers (11 males and 12 females) with mean of 28 +/- 5-years-old. LVF and VCS were evaluated using equilibrium radionuclide angiography images (ERNA). The comparison of both Chagas and control populations was carried out by t Student test for independent samples, considering a statistically significant value of p < 0.05. RESULTS: The parameters of the ventricular function and the ventricular synchronicity in subjects with positive serology for Chagas disease were not statistically different with respect to the parameters of the control group. However, although they have a homogeneous contraction, the mean time of contraction for the right and the left ventricle is statistically smaller with respect to the control group. CONCLUSIONS: In clinically incipient stages of Chagas disease we do not found abnormalities in the ventricular function and the ventricular synchronicity. It's necessary to consider the follow up of the studied populations using indices for the identification of abnormalities of the autonomic nervous system.

Myocardial perfusion and ventricular function assessed by SPECT and Gated-SPECT in end-stage renal disease patients before and after renal transplant.

BACKGROUND: Cardiovascular disease is a major cause of morbidity and mortality in end-stage renal disease (ESRD). Renal transplant is known to improve left ventricle hypertrophy and systolic dysfunction in selected groups of patients. METHODS: We assessed myocardial perfusion, wall motion and functional parameters by single photon emission computed tomography (SPECT) and Gated-SPECT in 30 consecutive ESRD patients with normal coronary angiograms before and after renal transplantation. RESULTS: Uremic cardiomyopathy improved significantly after the transplant. The proportion of patients with angina decreased from 26 to 0%; the frequency of cardiomegaly decreased from 57 to 20% (p <0.01); the frequency of segments with perfusion defects decreased from 42.7 to 10.2% (p <0.001); the proportion of patients with low left ventricular ejection fraction (LVEF) dropped from 53.3 to 20% (p <0.001); and mean LVEF increased from (48.0 +/- 9.7% to 58.2 +/- 8.2%). Similarly, the proportion of segments showing systolic wall thickening, hypokinesia and dyskinesia also decreased significantly after renal transplant (p <0.01). CONCLUSIONS: Uremic cardiomyopathy may be potentially reversible in patients with normal angiographic coronary arteries after renal transplant in a relatively short period of time. SPECT and Gated-SPECT are objective gateway methods to determine myocardial perfusion, hypokinesia, dyskinesia, and functional parameters (left ventricular ejection fraction and systolic wall thickening) and may be useful to establish diagnostic, coronariographic, prognostic, and therapeutic indications.

Analysis of ventricular contraction by factorial phase imaging with equilibrium radionuclide angiography.

Equilibrium radionuclide angiography (ERNA) imaging of the heart is used to visualize and quantify the cardiac function. Phase image analysis has been used for the localization of several conduction and contraction abnormalities and has been proposed to evaluate cardiac resynchronization therapy. The ventricular contraction has been described with indices like mean, standard deviation, mode, synchrony and entropy with Fourier phase imaging (FoPI). Factorial phase imaging (FaPI) has been used for wall motion abnormalities analysis and on a cardiac phantom, but not for synchrony quantification. In this paper a comparison of several indices obtained with FoPI and FaPI for a normal population is presented. These indices were computed inside regions corresponding to left ventricle, right ventricle and the total ventricular area. A set of ERNA images from 23 normal volunteers was analyzed. The comparison of indices was carried out by paired Student's t test with a significance level of (p<0.05). The results show significant differences among FoPI and FaPI on the analysis of ventricular contraction in normal individuals and consequently, on the quantification of the synchrony of contraction. The indices obtained from FaPI can be used to characterize a normal subject population for the evaluation of ventricular contraction synchrony.

Software phantom for the synthesis of equilibrium radionuclide ventriculography images.

This paper presents the novel design of a software phantom for the evaluation of equilibrium radionuclide ventriculography systems. Through singular value decomposition, the data matrix corresponding to an equilibrium image series is decomposed into both spatial and temporal fundamental components that can be parametrized. This parametric model allows for the application of user-controlled conditions related to a desired dynamic behavior. Being invertible, the decomposition is used to regenerate the radionuclide image series, which is then translated into a DICOM ventriculography file that can be read by commercial equipment.