STATIC IMAGES WITH DIFFERENT INDUCED INTENSITIES OF HUMAN BODY MOVEMENTS AFFECT SUBJECTIVE TIME

Modulation of subjective time was examined using static images eliciting perceptions of different intensities of body movement. Undergraduate students were exposed to photographs of dancer sculptures in different dance positions for 36 sec. and asked to estimate the exposure duration. Lower movement intensities were related to shorter estimated durations. Mean durations for images of unmoving dancers were underestimated and for dancers taking a ballet step were overestimated. Temporal estimations were also related to the order of presentation of the stimuli, which suggested that subjective time estimations were influenced by the experimental context. Subjective time is related not only to the visual perception of moving images, but also of elicited perceptions of movement in static images, suggesting an embodiment effect on subjective time estimation.

A New Family of Distance Functions for Perceptual Similarity Retrieval of Medical Images

A long-standing challenge of content-based image retrieval (CBIR) systems is the definition of a suitable distance function to measure the similarity between images in an application context which complies with the human perception of similarity. In this paper, we present a new family of distance functions, called attribute concurrence influence distances (AID), which serve to retrieve images by similarity. These distances address an important aspect of the psychophysical notion of similarity in comparisons of images: the effect of concurrent variations in the values of different image attributes. The AID functions allow for comparisons of feature vectors by choosing one of two parameterized expressions: one targeting weak attribute concurrence influence and the other for strong concurrence influence. This paper presents the mathematical definition and implementation of the AID family for a two-dimensional feature space and its extension to any dimension. The composition of the AID family with L (p) distance family is considered to propose a procedure to determine the best distance for a specific application. Experimental results involving several sets of medical images demonstrate that, taking as reference the perception of the specialist in the field (radiologist), the AID functions perform better than the general distance functions commonly used in CBIR.

The fMRI response of the LGN and V1 to cardinal red-green, blue-yellow, and achromatic visual stimuli

We compared the responsiveness of the LGN and the early retinotopic cortical areas to stimulation of the two cone-opponent systems (red - green and blue - yellow) and the achromatic system. This was done at two contrast levels to control for any effect of contrast. MR images were acquired on seven subjects with a 4T Bruker MedSpec scanner. The early visual cortical areas were localised by phase encoded retinotopic mapping with a volumetric analysis (Dumoulin et al, 2003 NeuroImage 18 576 - 587). We initially located the LGN in four subjects by using flickering stimuli in a separate scanning session, but subsequently identified it using the experimental stimuli. Experimental stimuli were sine-wave counterphasing rings (2 Hz, 0.5 cycle deg-1), cardinal for the selective activation of the L/M cone-opponent (RG), S cone-opponent (BY), and achromatic (Ach) systems. A region of interest analysis was performed. When presented at equivalent absolute contrasts (cone contrast = 5% - 6%), the BOLD response of the LGN is strongest to isoluminant red - green stimuli and weakest to blue - yellow stimuli, with the achromatic response falling in between. Area V1, on the other hand, responds best to both chromatic stimuli, with the achromatic response falling below. The key change from the LGN to V1 is a dramatic boost in the relative blue - yellow response, which occurred at both contrast levels used. This greatly enhanced cortical response to blue - yellow relative to the red - green and achromatic responses may be due to an increase in cell number and/or cell response between the LGN and V1. We speculate that the effect might reflect the operation of contrast constancy across colour mechanisms at the cortical level.

Microsurgical Anatomy of the Posterior Cerebral Artery in Three-Dimensional Images

OBJECTIVE: To describe the microsurgical anatomy, branches, and anatomic relationships of the posterior cerebral artery (PCA) represented in three-dimensional images. METHODS: Seventy hemispheres of 35 brain specimens were studied. They were previously injected with red silicone and fixed in 10% formalin for at least 40 days. Four of the studied specimens were frozen at -10 degrees to -15 degrees C for 14 days, and additional dissection was done with the Klingler`s fiber dissection technique at x6 to x40 magnification. Each segment of the artery was measured and photographed to obtain three-dimensional stereoscopic images. RESULTS: The PCA origin was in the interpeduncular cistern at the pontomesencephalic junction level in 23 specimens (65.7%). The PCA was divided into four segments: P1 extends from the PCA origin to its junction with the posterior communicating artery with an average length of 7.7 mm; P2 was divided into an anterior and posterior segment. The P2A segment begins at the posterior communicating artery and ends at the most lateral aspect of the cerebral peduncle, with an average length of 23.6 mm, and the P2P segment extends from the most lateral aspect of the cerebral peduncle to the posterior edge of the lateral surface of the midbrain, with an average length of 16.4 mm; P3 extends from the posterior edge of the lateral surface of the midbrain and ends at the origin of the parieto-occipital sulcus along the calcarine fissure, with an average length of 19.8 mm; and the P4 segment corresponds to the parts of the PCA that run along or inside both the parieto-occipital sulcus and the distal part of the calcarine fissure. CONCLUSIONS: To standardize the neurosurgical practice and knowledge, surgical anatomic classifications should be used uniformly and further modified according to the neurosurgical experience gathered. The PCA classification proposed intends to correlate its anatomic segments with their required microneurosurgical approaches.

Dipyridamole Stress and Rest Myocardial Perfusion by 64-Detector Row Computed Tomography in Patients With Suspected Coronary Artery Disease

Recently, stress myocardial computed tomographic perfusion (CTP) was shown to detect myocardial ischemia. Our main objective was to evaluate the feasibility of dipyridamole stress CTP and compare it to single-photon emission computed tomography (SPECT) to detect significant coronary stenosis using invasive conventional coronary angiography (CCA; stenosis >70%) as the reference method. Thirty-six patients (62 +/- 8 years old, 20 men) with previous positive results with SPECT (<2 months) as the primary inclusion criterion and suspected coronary artery disease underwent a customized multidetector-row CT protocol with myocardial perfusion evaluation at rest and during stress and coronary CT angiography (CTA). Multidetector-row computed tomography was performed in a 64-slice scanner with dipyridamole stress perfusion acquisition before a second perfusion/CT angiographic acquisition at rest. Independent blinded observers performed analysis of images from CTP, CTA, and CCA. All 36 patients completed the CT protocol with no adverse events (mean radiation dose 14.7 +/- 3.0 mSv) and with interpretable scans. CTP results were positive in 27 of 36 patients (75%). From the 9 (25%) disagreements, 6 patients had normal coronary arteries and 2 had no significant stenosis (8 false-positive results with SPECT, 22%). The remaining patient had an occluded artery with collateral flow confirmed by conventional coronary angiogram. Good agreement was demonstrated between CTP and SPECT on a per-patient analysis (kappa 0.53). In 26 patients using CCA as reference, sensitivity, specificity, and positive and negative predictive values were 88.0%, 79.3%, 66.7%, and 93.3% for CTP and 68.8, 76.1%, 66.7%, and 77.8%, for SPECT, respectively (p = NS). In conclusion, dipyridamole CT myocardial perfusion at rest and during stress is feasible and results are similar to single-photon emission CT scintigraphy. The anatomical-perfusion information provided by this combined CT protocol may allow identification of false-positive results by SPECT. (C) 2010 Elsevier Inc. All rights reserved. (Am J Cardiol 2010;106:310-315)

Quantification of orientation of pore patterns in X-ray images of deformed clay

The use of X-ray imaging to assess variability in ceramic fabrication is common in archaeological studies aimed at examining ancient pottery technologies. In this paper, a method based on the measurement of individual pores orientation is presented. This method is successfully applied to ceramic specimens of known origin whose structure signified different deformation histories.

Extraction of electrical characteristics from pixels of multifrequency EIT images

Computer modelling has shown that electrical characteristics of individual pixels may be extracted from within multiple-frequency electrical impedance tomography (MFEIT) images formed using a reference data set obtained from a purely resistive, homogeneous medium. In some applications it is desirable to extract the electrical characteristics of individual pixels from images where a purely resistive, homogeneous reference data set is not available. One such application of the technique of MFEIT is to allow the acquisition of in vivo images using reference data sets obtained from a non-homogeneous medium with a reactive component. However, the reactive component of the reference data set introduces difficulties with the extraction of the true electrical characteristics from the image pixels. This study was a preliminary investigation of a technique to extract electrical parameters from multifrequency images when the reference data set has a reactive component. Unlike the situation in which a homogenous, resistive data set is available, it is not possible to obtain the impedance and phase information directly from the image pixel values of the MFEIT images data set, as the phase of the reactive reference is not known. The method reported here to extract the electrical characteristics (the Cole-Cole plot) initially assumes that this phase angle is zero. With this assumption, an impedance spectrum can be directly extracted from the image set. To obtain the true Cole-Cole plot a correction must be applied to account for the inherent rotation of the extracted impedance spectrum about the origin, which is a result of the assumption. This work shows that the angle of rotation associated with the reactive component of the reference data set may be determined using a priori knowledge of the distribution of frequencies of the Cole-Cole plot. Using this angle of rotation, the true Cole-Cole plot can be obtained from the impedance spectrum extracted from the MFEIT image data set. The method was investigated using simulated data, both with and without noise, and also for image data obtained in vitro. The in vitro studies involved 32 logarithmically spaced frequencies from 4 kHz up to 1 MHz and demonstrated that differences between the true characteristics and those of the impedance spectrum were reduced significantly after application of the correction technique. The differences between the extracted parameters and the true values prior to correction were in the range from 16% to 70%. Following application of the correction technique the differences were reduced to less than 5%. The parameters obtained from the Cole-Cole plot may be useful as a characterization of the nature and health of the imaged tissues.

Regional gray matter abnormalities in panic disorder: A voxel-based morphometry study

Although abnonnalities in brain structures involved in the neurobiology of fear and anxiety have been implicated in the pathophysiology of panic disorder (PD), relatively few studies have made use of voxel-based morphometry (VBM) magnetic resonance imaging (MRI) to determine structural brain abnormalities in PD. We have assessed gray matter volume in 19 PD patients and 20 healthy volunteers using VBM. Images were acquired using a 1.5 T MRI scanner, and were spatially normalized and segmented using optimized VBM. Statistical comparisons were performed using the general linear model. A relative increase in gay matter volume was found in the left insula of PD patients compared with controls. Additional structures showing differential increases were the left superior temporal gyrus, the midbrain, and the pons. A relative gray matter deficit was found in the right anterior cingulate cortex. The insula and anterior cingulate abnormalities may be relevant to the pathophysiology of PD, since these structures participate in the evaluation process that ascribes negative emotional meaning to potentially distressing cognitive and interoceptive sensory information. The abnormal brain stem structures may be involved in the generation of panic attacks. (C) 2007 Elsevier Ireland Ltd. All rights reserved.

Primary ciliary dyskinesia: evaluation using cilia beat frequency assessment via spectral analysis of digital microscopy images

Olm MA, Kogler JE Jr, Macchione M, Shoemark A, Saldiva PH, Rodrigues JC. Primary ciliary dyskinesia: evaluation using cilia beat frequency assessment via spectral analysis of digital microscopy images. J Appl Physiol 111: 295-302, 2011. First published May 5, 2011; doi:10.1152/japplphysiol.00629.2010.-Ciliary beat frequency (CBF) measurements provide valuable information for diagnosing of primary ciliary dyskinesia (PCD). We developed a system for measuring CBF, used it in association with electron microscopy to diagnose PCD, and then analyzed characteristics of PCD patients. 1 The CBF measurement system was based on power spectra measured through digital imaging. Twenty-four patients suspected of having PCD (age 1-19 yr) were selected from a group of 75 children and adolescents with pneumopathies of unknown causes. Ten healthy, nonsmoking volunteers (age >= 17 yr) served as a control group. Nasal brush samples were collected, and CBF and electron microscopy were performed. PCD was diagnosed in 12 patients: 5 had radial spoke defects, 3 showed absent central microtubule pairs with transposition, 2 had outer dynein arm defects, 1 had a shortened outer dynein arm, and 1 had a normal ultrastructure. Previous studies have reported that the most common cilia defects are in the dynein arm. As expected, the mean CBF was higher in the control group (P < 0.001) and patients with normal ultrastructure (P < 0.002), than in those diagnosed with cilia ultrastructural defects (i.e., PCD patients). An obstructive ventilatory pattern was observed in 70% of the PCD patients who underwent pulmonary function tests. All PCD patients presented bronchial wall thickening on chest computed tomography scans. The protocol and diagnostic techniques employed allowed us to diagnose PCD in 16% of patients in this study.

Contrast-enhanced magnetic resonance imaging identifies focal regions of intramyocardial fibrosis, in patients with severe aortic valve disease: Correlation with quantitative histopathology

Background Chronic aortic valve disease (AVD) is characterized by progressive accumulation of interstitial myocardial fibrosis (MF). However, assessment of MF accumulation has only been possible through histologic analyses of endomyocardial biopsies. We sought to evaluate contrast-enhanced magnetic resonance imaging (ce-MRI) as a noninvasive method to identify the presence of increased MF in patients with severe AVD. Methods Seventy patients scheduled to undergo aortic valve replacement surgery were examined by cine and ce-MRI in a 1.5-T scanner. Cine images were used for the assessment of left ventricular (LV) volumes, mass, and function. Delayed-enhancement images were used to characterize the regions of MF. In addition, histologic analyses of myocardial samples obtained during aortic valve replacement surgery were used for direct quantification of interstitial MF. Ten additional subjects who died of noncardiac causes served as controls for the quantitative histologic analyses. Results Interstitial MF determined by histopathologic analysis was higher in patients with AVID than in controls (2.7% +/- 2.0% vs 0.6% +/- 0.2%, P =.001). When compared with histopathologic results, ce-MRI demonstrated a sensitivity of 74%, a specificity of 81%, and an accuracy of 76% to identify AVD patients with increased interstitial MF There was a significant inverse correlation between interstitial MF and LV ejection fraction (r = -0.67, P <.0001). Accordingly, patients with identifiable focal regions of MF by ce-MRI exhibited worse LV systolic function than those without MF (45% +/- 14% vs 65% +/- 14%, P <.0001). Conclusions Contrast-enhanced MRI allows for the noninvasive detection of focal regions of MF in patients with severe AVD. Moreover, patients with identifiable MF by ce-MRI exhibited worse LV functional parameters. (Am Heart J 2009; 157:361-8.)

Reduced gray matter volume in ventral prefrontal cortex but not amygdala in bipolar disorder: Significant effects of gender and trait anxiety

Neuroimaging studies in bipolar disorder report gray matter volume (GMV) abnormalities in neural regions implicated in emotion regulation. This includes a reduction in ventral/orbital medial prefrontal cortex (OMPFC) GMV and, inconsistently, increases in amygdala GMV. We aimed to examine OMPFC and amygdala GMV in bipolar disorder type 1 patients (BPI) versus healthy control participants (HC), and the potential confounding effects of gender, clinical and illness history variables and psychotropic medication upon any group differences that were demonstrated in OMPFC and amygdala GMV Images were acquired from 27 BPI (17 euthymic, 10 depressed) and 28 age- and gender-matched HC in a 3T Siemens scanner. Data were analyzed with SPM5 using voxel-based morphometry (VBM) to assess main effects of diagnostic group and gender upon whole brain (WB) GMV. Post-hoc analyses were subsequently performed using SPSS to examine the extent to which clinical and illness history variables and psychotropic medication contributed to GMV abnormalities in BPI in a priori and non-a priori regions has demonstrated by the above VBM analyses. BPI showed reduced GMV in bilateral posteromedial rectal gyrus (PMRG), but no abnormalities in amygdala GMV. BPI also showed reduced GMV in two non-a priori regions: left parahippocampal gyrus and left putamen. For left PMRG GMV, there was a significant group by gender by trait anxiety interaction. GMV was significantly reduced in male low-trait anxiety BPI versus male low-trait anxiety HC, and in high-versus low-trait anxiety male BPI. Our results show that in BPI there were significant effects of gender and trait-anxiety, with male BPI and those high in trait-anxiety showing reduced left PMRG GMV. PMRG is part of medial prefrontal network implicated in visceromotor and emotion regulation. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

Assessment of linear and angular measurements on three-dimensional cone-beam computed tomographic images

Objective. The purpose of this research was to provide further evidence to demonstrate the precision and accuracy of maxillofacial linear and angular measurements obtained by cone-beam computed tomography (CBCT) images. Study design. The study population consisted of 15 dry human skulls that were submitted to CBCT, and 3-dimensional (3D) images were generated. Linear and angular measurements based on conventional craniometric anatomical landmarks, and were identified in 3D-CBCT images by 2 radiologists twice each independently. Subsequently, physical measurements were made by a third examiner using a digital caliper and a digital goniometer. Results. The results demonstrated no statistically significant difference between inter-and intra-examiner analysis. Regarding accuracy test, no statistically significant differences were found of the comparison between the physical and CBCT-based linear and angular measurements for both examiners (P = .968 and .915, P = .844 and .700, respectively). Conclusions. 3D-CBCT images can be used to obtain dimensionally accurate linear and angular measurements from bony maxillofacial structures and landmarks. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: 430-436)

Absence and hypoplasia of the mental foramen detected in CBCT images: a case report

The mental foramen (MF) is an important anatomic landmark of the mandible, through which the mental nerve and blood vessels emerge. The importance of MF in dental practice is especially related to dental implants placement and other surgical procedures in the region. It is fundamental to be careful in order to avoid nerve and vessels injury during procedures. Anatomic variations of the MF can be found, such as occurrence of multiple foramina and unusual location. In very rare occasions, the absence of MF can be detected. The observation of this variation is not always possible using only conventional radiographs. The modern imaging resource cone beam computed tomography (CBCT) allows an accurate three-dimensional assessment of MF, as well as the identification of its variations. The aim of this article is to report MF absence and hypoplasia detected in CBCT images of a 27-year-old daughter and her 63-year-old mother, both from Brazil. Despite the MF anatomic variations, they presented no sensorial disturbance in the regions supplied by the mental nerve.