Figure 6 - uploaded by Rodrigo Donizete Santana de Pádua
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Tomographic sections representative of myocardial perfusion SPECT of a male patient demonstrating a reversible perfusional defect on the septal, anterior, infero-posterior and apical walls. The two upper series represent the initial gross images, and the two lower series show the fusion of the initial images with the perfusional defects projections automatically identified through statistical comparison with the corresponding template images of the atlas.
Source publication
OBJECTIVE: To develop an atlas of myocardial perfusion scintigraphy and evaluating its applicability in computer-aided detection of myocardial perfusion defects in patients with ischemic heart disease.
MATERIALS AND METHODS: The atlas was created with rest-stress myocardial perfusion scintigraphic images of 20 patients of both genders with low prob...
Contexts in source publication
Context 1
... first and third range of images on Figure 6 demonstrate three orthogonal axis of, respectively, rest/stress cardiac SPECT projections of the male patient already aligned with the template images of mean perfusion uptake for male individuals (Fig- ure 4). The second range demonstrates the same projections overlapped by the perfu- sion defect image where arrows indicate the areas with myocardial perfusion abnor- mality. ...
Context 2
... Figure 6, Figure 7 demonstrates the female patient's images already aligned with the corresponding template images (Figure 5), besides presenting the areas with myocardial perfusion defect indicated by the arrows. Also, in complete agreement with the visual analysis results, the auto- Figure 4. Tomographic sections illustrating the atlas of male myocardial per- fusion SPECT scintigraphy demonstrating template images of mean and stan- dard-deviation under physiological stress and rest conditions. ...
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Citations
... For the application of the alignment stage, templates proposed by [Pádua et al. 2008] were used in an attempt to reduce uncertainty of heart areas' position and improve automation of the process. Templates were built from 20 images of patients, 10 male and 10 female, with approximated weight and height (in rest condition, obtained from volunteers without cardiac defect). ...
... In tests performed by [Pádua et al. 2008], the images had to be corrected manually by a specialist, since the objective was to create templates that would represent the mean of functional activity among normal patients. This means that templates were useful for the present study, but the methodology of alignment had to be modified, because the inferior junction of the left to the right ventricle was not correctly adjusted, and the polar map created had a rotated aspect compared to the gold standard. ...
This paper describes a technique for an automatic polar map creation
from myocardial perfusion SPECT images. This exam is widely used in
post-infarction patient evaluations, in order to foretell the outcome and left ventricular
function. This exam is difficult to interpret, since it is a 3D representation
of the heart. Use of polar maps intends to simplify analysis of the exam,
converting the 3D image into a 2D plot. The technique developed is based on
a combination of image registration and feature detection. For this study, an
overall of 31 cases were tested, with the results compared with the gold standard
software. The correlation calculated between techniques was 0.76 in the
worst case and 0.98 in the best case.
The acute myocardial infarction (AMI) is considered the main cause of ischemic heart syndrome, one of the first causes of death in developed countries. One effective way to realize follow-up on patient that suffered AMI is the analysis of polar maps. This work presents an automated registration technique for myocardial scintigraphy images. The purpose of this algorithm is the positioning of the SPECT image according to a known pattern, allowing the automatic creation of bull's-eye maps for easier visualization. The developed method for the structure based registration utilizes different image processing techniques, like thresholding and feature extraction, to improve the result of the model based image registration. After the model based image registration, a technique for rotation adjustment in both long axes was applied, where the wall of the myocardium is detected based on its shape. Following, the technique for rotation adjustment in the short axis was applied, using information obtained through the SIFT technique. The proposed technique was appraised through comparison with the ideal alignment realized manually in 15 cases of patients with and without heart defect. The rate of success obtained was roughly 86% for the analyzed cases. The results obtained indicate that the proposed techniques were capable of realizing the registration automatically, even though using methods that have little computational costs.
Objective: This paper presents a model for integration of computer-aided diagnosis algorithms into the picture archiving and communication systems workflow that has been developed on the basis of the dcm4che2 open source toolkit. Materials and Methods: The proposed integration model consists of an image processing server and communication services. The data management follows the workflow defined by the post-processing workflow profile (PWF) developed by Integrating the Healthcare Enterprise (IHE) and utilizes the DICOM secondary capture functionality. An application for diffuse lung disease has been utilized as proof of concept. Results: Based on a cross validation method, the standard classification algorithm presented 78% accuracy. The integration enables the visualization of processed images as a new series in the original study. Conclusion: The proposed integration model is based on IHE profiles and allows the establishment of standardized procedures. The principles used to integrate the workflow are applicable to any non-interactive post-processing task.
By reducing the specificity associated with loss of information, the influence of attenuation of the breasts is very important in myocardial perfusion studies. However, although several studies have been conducted over the past years, little has been developed to determine accurately the influence of the characteristics of the breasts on the quality of myocardial scintigraphy, avoiding additional exposure to radiation.
The purpose of this study is to quantify the attenuation of photons by the breasts, in myocardial perfusion studies with (99m)Tc according to different sizes and compositions.
Each breast was assumed to be a cube composed of fibroglandular and adipose tissue. The data related to (99m)Tc photons were analyzed in a Monte Carlo model. We varied the thickness and composition of breasts and analyzed the interference in attenuation. The EGS 4 software was used in the simulations.
Setting the thickness of a breast, the variation of its composition causes a maximum increase of 2.3% in the number of photons attenuated. By contrast, maintaining a fixed composition of breast tissue, the difference in photon attenuation was 45.0%, averaging 6.0% for each additional centimeter in the breast thickness.
Monte Carlo simulation showed that the influence of the thickness of the breasts in the attenuation of photons in myocardial scintigraphy with (99m)Tc is much greater than the influence of their compositions.
