Objective: The layer of fat that accumulates around the heart, called cardiac adipose tissue (CAT), can influence the development of coronary disease and is indicative of cardiovascular risk. While volumetric assessment of magnetic resonance imaging (MRI) can quantify CAT, volume alone gives no information about its distribution across the myocardial surface, which may be an important factor in risk assessment. In this study, a three-dimensional (3D) modeling technique is developed and used to quantify the distribution of the CAT across the surface of the heart.Methods: Dixon MRI scans, which produce a registered 3D set of fat-only and water-only images, were acquired in 10 subjects for a study on exercise intervention. A previously developed segmentation algorithm was used to identify the heart and CAT. Extracted contours were used to build 3D models. Procrustes analysis was used to register the heart models and an iterative closest point algorithm was used to register and align the CAT models for calculation of CAT thickness. Rays were cast in directions specified by a spherical parameterization of elevation and azimuthal angles, and intersections of the ray with the CAT surface were used to calculate the thickness at each location. To evaluate the effects of the spherical parameterization on the thickness estimates, a set of synthetic models were created with increasing major-to-minor axis ratios.Results: Based on the validation in the synthetic models, the average error in CAT thickness ranged from 1.25% to 17.3% for increasing major-to-minor axis ratio.Conclusions: A process was developed, based on Dixon MRI data, to provide 3D models of the myocardial surface and the cardiac fat. The models can be used in future segmentation algorithm development and for studies on changes in cardiac fat as a result of various interventions.
Steel sheet with an insulator to prevent corrosion is used for various purposes including in building and car manufacture. Terahertz waves, for which insulators are highly permeable and metal surfaces are highly reflective, have been studied in order to establish a new inspection technology for these steel plates. In our previous research, spectroscopic measurements in the 1.0-4.0 THz range, generated by a GaP crystal, were carried out in order to collect information on the infrared activity of the metal corrosion products formed on Zn-Al hot-dip galvanized steel sheet. In the previous work, the infrared activity of Fe-based corrosion products was not examined. To examine these products, we conducted THz spectroscopy on goethite (α-FeOOH) in the range from 8.4 to 11.0 THz, generated by a GaSe crystal. The results of Attenuated Total Reflectance (ATR) FTIR spectral measurements and molecular vibration calculations were analyzed, on the basis of which the natural vibration modes of α-FeOOH in the THz frequency range were assigned.
Objective: Increasing evidence suggests a strong link between excess cardiac adipose tissue (CAT) and the risk of a cardiovascular event. Multi-echo Dixon magnetic resonance imaging (MRI), providing fat-only and water-only images, is a useful tool for quantification but requires the segmentation of CAT from a large number of images. The intent of this study was to evaluate an automated technique for CAT segmentation from Dixon MRI by comparing the contours identified by the automated algorithm to those manually traced by an observer. Methods: An automated segmentation algorithm, based on optimal thresholds and custom morphological processing, was applied to the registered fat-only and water-only images to identify CAT in the volume scans. CAT contours in 446 images, from 10 MRI scans, were selected for validation analysis. Cross-sectional area (CSA) and volume were computed and compared using Bland-Altman analysis. In addition, Hausdorff distance and Dice Similarity Coefficient (DSC) were used for assessment.Results: Linear regression analysis yielded correlation of R2 = 0.381 for CSA and R2 = 0.879 for volume. When compared to the observer, the computer algorithm under-estimated CSA by 27.5 ± 40.0% and volume by 26.4 ± 10.4%. The average bidirectional Hausdorff distance was 26.2 ± 16.0 mm while the average unidirectional Hausdorff distances were 24.5 ± 15.7 mm and 12.4 ± 11.7 mm. The average DSC was 0.561 ± 0.100. The time required for manual tracing was 15.84 ± 3.73 min and the time required for the computer algorithm was 2.81 ± 0.12 min.Conclusions: This study provided a technique, faster and less tedious than manual tracing (p < 0.00001), for quantification of CAT in Dixon MRI data, demonstrating feasibility of this approach for cardiac risk stratification.
BACKGROUND:Human voxel models incorporating detailed anatomical features are vital tools for the computational evaluation of electromagnetic (EM) fields within the body. Besides whole-body human voxel models, phantoms representing smaller heterogeneous anatomical features are often employed; for example, localized breast voxel models incorporating fatty and fibroglandular tissues have been developed for a variety of EM applications including mammography simulation and dosimetry, magnetic resonance imaging (MRI), and ultra-wideband microwave imaging. However, considering wavelength effects, electromagnetic modeling of the breast at sub-microwave frequencies necessitates detailed breast phantoms in conjunction with whole-body voxel models.METHODS:Heterogeneous breast phantoms are sized to fit within radiofrequency coil hardware, modified by voxel-wise extrusion, and fused to whole-body models using voxel-wise, tissue-dependent logical operators. To illustrate the utility of this method, finite-difference time-domain simulations are performed using a whole-body model integrated with a variety of available breast phantoms spanning the standard four tissue density classifications representing the majority of the population.RESULTS:The software library uses a combination of voxel operations to seamlessly size, modify, and fuse eleven breast phantoms to whole-body voxel models. The software is publicly available on GitHub and is linked to the file exchange at MATLAB® Central. Simulations confirm the proportions of fatty and fibroglandular tissues in breast phantoms have significant yet predictable implications on projected power deposition in tissue.CONCLUSIONS:Breast phantoms may be modified and fused to whole-body voxel models using the software presented in this work; user considerations for the open-source software and resultant phantoms are discussed. Furthermore, results indicate simulating breast models as predominantly fatty tissue can considerably underestimate the potential for tissue heating in women with substantial fibroglandular tissue.
Nutcracker syndrome includes all the symptoms associated with the narrowing of the left renal vein (LRV). That narrowing occurs between the aorta and the Superior Mesenteric Artery (anterior) or vertebra (posterior). The symptoms are various and not specific but the patient sometimes presents hematuria with or without left flank pain. We report a case on a 42 years old woman, who was suffering from left flank pain for a long time aggravated during and after each pregnancy. The diagnosis of nutcracker syndrome was initially omitted. Abdominal pelvic Angio CT and venography were performed. We placed a percutaneous stent in the narrowed portion of the renal vein. The result was successful.
Abnormally high levels of neocortical beta-amyloid protein (A+) reflect Alzheimer’s disease (AD) pathology in persons with clinical evidence of dementia or mild cognitive impairment (MCI). The abnormal aggregation of beta-amyloid protein in the brain neuropil may lead to either diffuse plaques and/or concentrated neuritic plaques, with the latter form of deposits often present in the vicinity of the cerebral microvasculature. The A protein, with its crystalline molecular structure, infiltrates the vessel walls and compromises the blood-brain barrier (BBB). The physical basis for this was elegantly shown by Meyer and colleagues, in a 2008 publication showing two-dimensional (2D) confocal laser scanning microscopic imaging of vascular A protein deposits in APP23 transgenic mice. These investigators showed accumulations of “tuft-life structures”, also referred to as “pompons” with protruding spikes on – and embedded within – microvessels. These pompons of beta-amyloid protein “consist of fibrillar structures, [and] can encircle and constrict capillaries, and are often associated with distortion of capillaries”.We were struck by both the heuristic value of the imaging of Meyer and colleagues, in explaining the root cause of both the amyloid-related alterations in the vascular bed, and depicting minute protein deposits that are both geometrically complex, seemingly delicate and fragile, and yet tenacious in their embedding within small vessel walls. We re-created these images with standard 3D printing technology (extruded plastic) for both educational/teaching and artistic purposes.
Study design: Prospective case-control study. Objective: Aim of the study was to assess critical values of mechanical stress and strain in the cervical spinal cord based on the Finite Element Method (FEM) simulations of specified clinical cases. Summary of background data: The knowledge about the values and distribution of tension and deformation, which are noted at the moment of traumatic spinal cord injury (tSCI) may enable determination of the range of primary and secondary injury. Methods: Total of 28 patients after cervical spine (C-spine) injury were enrolled, 14 with neurological symptoms of tSCI (study group, SG) and 14 neurologically intact (control group, CG). Both groups were age and sex matched. A three-dimensional (3D) numerical model of the cervical spinal cord containing dura and pia matter together with denticulate ligament was created. The variable boundary conditions were established individually for each case and allowed to reconstruct the moment of the injury in computer environment. Factors differentiating between SG and CG were tested with multiple logistic regression model. The predictors of ASIA scale outcomes were evaluated in the ordinal multinomial probit regression model. Results: There were no correlations between age, sex and the level of injury and the values of stress and strain. The results in longitudinal axis (z), in stress (OR-6.3; 95%CI 3.94-8.78; p < .033) and strain (OR-7.8; 95%CI 3.03-10.19; p < .046) were the risk factors of neurological deficits after tSCI. The cut off value for stress was 8.1 kPa (sensitivity-85.7%; specificity-78.6%; AUC-0.819, p < .001), and for strain 0.0117 (sensitivity-92.9%; specificity-72.5%; AUC-0.645, p < .001). Results in the longitudinal axis (z), in stress and strain correspond with grading in ASIA scale. One grade change in ASIA scale correlates with the decrease in z axis by 4.01 kPa and 0.012 in stress and strain respectively. Conclusions: The severity of damage of osseous and ligament structures of the spine, significantly influences the range of the mechanical stress applied to the spinal cord. Neural tissue of the spinal cord is the most resistant to the mechanical stimulus acting in sagittal direction, distraction appears to be the most destructive component of the injury phenomenon.
Sudden cardiac death (SCD) is the leading cause of death in the U.S., and many of these events are attributable to malignant ventricular arrhythmias such as sustained ventricular tachycardia (VT). Most of the efforts to identify arrhythmia precipitants in these patients are based on imaging to look for myocardial or coronary artery disease. As advances in cardiac computed tomography (CCT) are made, it has demonstrated its usefulness in identifying structural intracardiac pathology and measuring parameters of cardiac anatomy and function. In this article we review the different etiologies of VT/SCD that are identifiable by CCT, and its potential usefulness in the workup for VT/SCD.
Introduction: It has been postulated that renal volume should play a bigger role in selection of donor kidney apart from anatomy and that the larger kidney should be kept for the donor. We attempted to investigate the correlation between donor residual renal volume and post-transplant donor renal function up to 5 years post donation. Material and methods: Retrospective analysis was performed on all living related renal transplant at a tertiary institution from 2005-2013. Pre-operative renal volumes of donors were calculated using computer tomography (CT) images. Serum creatinine and creatinine clearance levels were collected at pre-operative, 6 months, 1 year, and 5 years post donation. Percentage residual renal volume was correlated against the percentage change in serum creatinine and creatinine clearance over the specified time points. Results: Eighty-four donors were analyzed and the left kidney was removed in all patients. Median age was 46 years (22-76), median pre-operative renal volume was 261 cm 3 (142–453) and median percentage of residual renal volume was 44% (29-55). Median serum creatinine at pre-operative, 6 months, 1 year, and 5 years were 65, 96, 99, and 91 μmol/L respectively. Median creatinine clearance at pre-operative, 6 months, 1 year and 5 years were 113, 76, 74 and 81 ml/min respectively. Serum creatinine trend showed improvement up to 5 years but creatinine clearance stabilized after 6 months. When compared against percentage residual renal volume, there were no significant correlations found with percentage change in serum creatinine and creatinine clearance over pre-operative, 6 months, 1 year or 5 years. Discussion: There is no association between donated renal volume and changes in serum creatinine or creatinine clearance. Size of the donated kidney does not matter.
Objective: Magnetic field (B 0 ) homogeneity is important for the performance of a magnetic resonance imaging (MRI) system. Traditionally, B 0 homogeneity was measured using the spectral peak or phase-mapping methods. However, these procedures are not generally accessible to the MRI operator and are rarely performed routinely. This study proposes a novel method for measuring B 0 homogeneity that can be implemented in daily quality control (QC). Methods: When a uniformly mixed water/oil phantom was imaged using a gradient recalled echo (GRE) pulse sequence, the signal intensity dynamically changed with echo time (TE). From this, the resonant frequency was calculated with a simplex curve-fitting algorithm on a pixel-by-pixel basis. The standard deviation of resonant frequency (SD) was used as the index of B 0 homogeneity. The appropriate TE pattern and feasibility of B 0 homogeneity evaluation were examined. Results: Over seven TEs (choosing nominal in-phase, out-phase, and the midpoints of both) were required to measure stable SD in a 1.5-T scanner. As B 0 homogeneity worsened, the SD became larger at the off-center position. Although a positive correlation was observed with the width of the spectral peak obtained by the phase-difference method, the SD value was about 5 × 10 4 times greater. Therefore, SD can be used only as an index of B 0 homogeneity. Similar results were obtained using a 0.3-T scanner. A map and SD can be obtained by acquiring several GRE images of a water/oil mixed phantom within a few minutes. Conclusions: In-out signal cycle mapping can be easily implemented for daily QC in all MRI scanners.
Oropharyngeal infections can sometimes be complicated by Lemierre syndrome (LS), which is a septic thrombophlebitis of the internal jugular vein. This is a diagnostic and therapeutic emergency. It must be systematically suspected in a patient presenting oropharyngeal infection, clinical signs of sepsis and cervical swelling and pain. Cervical and thoracic computed tomography is absolutely necessary with a triple interest; diagnosis, prognosis and therapy.
Swyer-James syndrome (SJS) is a relatively uncommon type of postinfectious obliterative bronchiolitis as a result of respiratory tract infection (RTI) in early childhood. Vascular ring (VR) is usually an underlying cause of RTI. When VR complicated with SJS, both diseases can be a relationship of cause and result, but have not been published in the past. Herein, we described an 8-year-old female school-age child who had history of recurrent RTI since age of 6 months. After screening echocardiographic findings of hypoplastic left pulmonary artery and aberrant right subclavian artery (ARSCA), confirmed by multisliced CT and functional evaluation by bronchoscopy and manometry. After she underwent aortopexy for ARSCA and balloon dilatation of constrictive bronchus and tracheal stenosis, and her growth pattern and pulmonary function improved progressively. Early detection by echocardiography and elimination of the associated underlying airway obstruction were mandatory for improvement of pulmonary function.
Purpose: To study the effectiveness of image-guided percutaneous ethanol injection (PEI) to ablate malignant hepatic lesions. Methods: It was a hospital based prospective study. Study included 15 patients (8 men, 7 women); aged 40-75 years (mean age 58.3 years); involving 4 hepatocellular carcinoma (HCC) (ranging from 2.8 cm-8.0 cm in diameter) and 18 liver metastases (ranging from 0.78 cm-4.5 cm in diameter). Forty eight sessions (18 sessions for 3 HCCs and 30 for 11 liver metastases) using 99.9% ethanol injection were done under image guidance to treat 21 tumours in 14 patients. Under local anaesthesia, absolute ethanol (99.9%) was instilled into the tumour via 22 gauge spinal needle. Triple phased Contrast enhanced computed tomography (CECT) was used in all the cases to assess the treatment response. Results: The 3 patients having solitary HCC tumours measuring 2.8 cm, 6.5 cm and 8 cm were assigned into complete response, partial response and progressive disease categories respectively after PEI. Treatment response was not assessed in 1 patient. Among 11 liver metastases patients; complete response, partial response, stable disease and progressive disease was assigned in 5 (45.5%), 1 (6.6%), 2 (18.1%) and 3 (27.2%) patients respectively. Conclusions: PEI is a safe and effective technique for treating smaller liver neoplasms and less than 3 lesions for each patient as per BCLC criteria.
Objective: To propose and demonstrate using Bland-Altman plots and Limits of Agreement based on the relative difference(RD) in solid tumor measurements to assess agreement. Methods: A modification to the Bland-Altman plot which involves replacing the difference plotted on the vertical axis withthe relative percent difference between two measurements of tumor burden is discussed. Quantifying tumor burden requiressumming skewed individual tumor measurements. This quantity is the same one used in assessing tumor response to therapeuticagents and is familiar to radiologists and clinicians working with cancer patients. The distribution of the relative difference isexplored and revised equations for the limits of agreement are presented. The methods are then applied to positron emissiontomography data studying two radiotracers. Results: The distribution of the relative difference is highly skewed and can be approximated by a negative shifted lognormaldistribution. The limits of agreement for the RD need to appropriately reflect this distribution. The standard equations for the95% limits of agreement assume the differences are approximately normally distributed and may not be appropriate for therelative difference. Conclusions: The modified Bland-Altman plot is based on a clinically meaningful quantity and provides a method for handlingdata with multiple lesions per patient.
Introduction: Recent advances in technology have seen the introduction of software assisted image post-processing (SAIP)tools to calculate the volume of the liver from Computed Tomography (CT) images. One such SAIP tool is the semi-automatedPhilips liver segmentation and analysis package (Endhoven, The Netherlands). The intra- and inter-rater reliability of the livervolumes of 16 participants calculated using this tool was assessed. Methods: Two CT Technologists accessed Abdominal CT data sets and calculated the volume of the liver using the Philips liversegmentation and analysis package. One technologist repeated their calculation. Results: Results demonstrated high intra-rater reliability (ICC 0.9997) and high inter-rater reliability (ICC 0.99994). Analysiswith Bland Altman plots showed the mean bias for both intra- and inter-rater reliability to be close to zero with acceptable limitsof agreement. Conclusions: This study has shown that liver volume measurements using the Philips SAIP (Endhoven, The Netherlands) can betaken reliably by CT technologists, with confidence that the same results would be obtained between different CT technologists.
In recent years, functional magnetic resonance imaging has been used to determine the interaction between chewing and brainactivity. However, the factors influencing the activity of the motor cortex have not been fully elucidated. Therefore, the presentstudy investigated the influence of the magnitude of bite force on brain activity. Fifteen right-handed healthy subjects (24-32 years; mean age, 27.8 years) were included. Sustained, constant clenching with small and large forces comprised the motortask. The spatial extent of the functional magnetic resonance imaging signal in the primary sensorimotor cortex increased withan increasing bite force in all subjects. These findings indicated the possibility of measuring the activated area in the primarysensorimotor cortex during clenching using functional magnetic resonance imaging, which revealed that the brain activity wasrelated to the magnitude of the bite force.
We propose a method for local, region-based matching of planar shapes, especially as those shapes that change over time. This is a problem fundamental to medical imaging, specifically the comparison over time of mammograms. The method is based on the non-emergence and non-enhancement of maxima, as well as the causality principle of integral invariant scale space. The core idea of our Region Matching Algorithm (RMA) is to divide a shape into a number of “salient” regions and then to compare all such regions for local similarity in order to quantitatively identify new growths or partial/complete occlusions. The algorithm has several advantages over commonly used methods for shape comparison of segmented regions. First, it provides improved key-point alignment for optimal shape correspondence. Second, it identifies localized changes such as new growths as well as complete/partial occlusion in corresponding regions by dividing the segmented region into sub-regions based upon the extrema that persist over a sufficient range of scales. Third, the algorithm does not depend upon the spatial locations of mammographic features and eliminates the need for registration to identify salient changes over time. Finally, the algorithm is fast to compute and requires no human intervention. We apply the method to temporal pairs of mammograms in order to detect potentially important differences between them.
Objective: A low-cost microscope slide scanner was constructed for the purpose of digital imaging of newborn piglet brain tissue and to quantify fluorescent microspheres in tissue. Methods: Using a standard digital single-lens reflex (DSLR) camera, fluorescent imaging of newborn piglet brain tissue was performed. A computer algorithm available for download was created to detect fluorescent microspheres in the brain tissue slides and to calculate regional cerebral blood flow (rCBF). The precision of the algorithm was tested by comparing with manual counting of the fluorescent microspheres. Finally, bright-field imaging was tested by adding light diffuser film. Results: Cost of the slide scanner was a fraction of the cost of a commercial slide scanner. The slide scanner was able to image a large number of tissue slides in a semiautomatic manner and provided a large field of view (FOV) of 101 mm 2 combined with a resolution of 2.9 μm. The mean difference (SD) between manual and automatic counts was in absolute numbers 0.32 (1.5) microspheres ranging from -5 to 5 microspheres per slide. The relative total difference between automatic and manual counts was -3.1%. Conclusions: A slide scanner was constructed and an automatic algorithm to detect fluorescent microspheres in tissue was developed and validated and showed an acceptable difference to “gold standard” manual counting. The slide scanner can be regarded as a low-cost alternative for researchers when digital slide imaging and quantification of fluorescent microspheres are needed.
Objective: It is often difficult to pinpoint the affected nerve root/roots from clinical symptoms and Magnetic Resonance Imaging (MRI) alone in patients with chronic cervical radiculopathy and multilevel degenerative changes. MRI often shows degenerativechanges at more than one level. Degenerative changes can occur in patients without symptoms and clinical diagnosis. Analysesof referred pain distribution from cervical nerve roots have shown only 50% correlation to the classical sensory dermatome. Surgical treatment of patients with cervical radiculopathy attributed to degenerative disease is associated with moderate outcomeresults. Our aim was to assess the diagnostic value of cervical selective nerve root blocks (SNRB) in our Trust in surgical decisionmaking. Methods: The data was collected retrospectively from electronic hospital records on CRIS, PACS and NOTIS on consecutivepatients who underwent cervical nerve root blocks for diagnostic purpose between 1st Jan 2011 and 31st December 2011. Results: Total of 50 patients had cervical SNRB for diagnostic reasons. It influenced surgical decision making in 84% (42) ofthese patients and not in 2% cases. 10% did not have any follow up after cervical SNRB. Decision in favour of surgery wasmade in 71.5% of these 42 patients. Conclusions: In chronic cervical brachialgia, cervical SNRB is extremely influential in surgical decision making, in bothwhether to operate and which levels scenario.
The retina can provide evidence of diseases originating in other parts of the body. Among the eye diseases that can be diagnosed through a retinal examination, age-related macular degeneration, glaucoma, and diabetic retinopathy are the most common, and they cause vision loss. Although these diseases can be diagnosed by examining blood vessels and the optic disk in retinal images, assessment of blood vessels on colored fundus images is a time-consuming and subjective process. Here, we present an automated blood vessel segmentation algorithm that facilitates the evaluation of diabetic retinopathy through assessment of blood vessel abnormalities. The blood vessels are extracted using a random forest classification model combined with wavelet features and local binary pattern texture information. Discriminant analysis is modified and used for feature selection to train the proposed classification model. The boundary of the optic disk is identified using low-pass filtering, fuzzy c-means clustering, and template matching so that it may be removed and not confound the segmentation analysis. Validation test results using three publicly available retinal image datasets demonstrated that our proposed method achieves as good or better blood vessel segmentation accuracy than the other supervised model approaches examined. Results show that the proposed scheme is able to segment the blood vessels and optic disk structures accurately (Accuracy Index) in 95.80%, 95.20%, and 97.10% of the testing Digital Retinal Images for Vessel Extraction (DRIVE), Structured Analysis of the Retina (STARE), and CHASE_DB1 image datasets respectively. The main advantage of our proposed model is that it provides robust and computationally efficient segmentation of blood vessels and the optic disk. The proposed model aims to provide supportive information for cases in which a diagnosis remains unclear following a clinical examination.
