Is there a need for attenuation correction in the 99mTc-DMSA scans on pediatric patients?

Introduction: The quantification of th e differential renal function in adults can be difficult due to many factors - on e of the se is the variances in kidney depth and the attenuation related with all the tissue s between the kidney and the camera. Some authors refer that t he lower attenuation i n p ediatric patients makes unnecessary the use of attenuation correction algorithms. This study will com pare the values of differential renal function obtained with and with out attenuation correction techniques . Material and Methods: Images from a group consisting of 15 individuals (aged 3 years +/ - 2) were used and two attenuation correction method s were applied – Tonnesen correction factors and the geometric mean method . The mean time of acquisition (time post 99m Tc - DMSA administration) was 3.5 hours +/ - 0.8h. Results: T he absence of any method of attenuation correction apparently seems to lead to consistent values that seem to correlate well with the ones obtained with the incorporation of methods of attenuation correction . The differences found between the values obtained with and without attenuation correction were not significant. Conclusion: T he decision of not doing any kind of attenuation correction method can apparently be justified by the minor differences verified on the relative kidney uptake values. Nevertheless, if it is recognized that there is a need for a really accurate value of the relative kidney uptake, then an attenuation correction method should be used.

Comparative study between two distinct methods for attenuation correction and the use of no-attenuation correction for the assessment of relative uptake of 99mTc-DMSA on pediatric patients

Introduction: Although relative uptake values aren’t the most important objective of a 99mTc-DMSA scan, they are important quantitative information. In most of the dynamic renal scintigraphies attenuation correction is essential if one wants to obtain a reliable result of the quantification process. Although in DMSA scans the absent of significant background and the lesser attenuation in pediatric patients, makes that this attenuation correction techniques are actually not applied. The geometric mean is the most common method, but that includes the acquisition of an anterior (extra) projection, which it is not acquired by a large number of NM departments. This method and the attenuation factors proposed by Tonnesen will be correlated with the absence of attenuation correction procedures. Material and Methods: Images from 20 individuals (aged 3 years +/- 2) were used and the two attenuation correction methods applied. The mean time of acquisition (time post DMSA administration) was 3.5 hours +/- 0.8h. Results: The absence of attenuation correction showed a good correlation with both attenuation methods (r=0.73 +/- 0.11) and the mean difference verified on the uptake values between the different methods were 4 +/- 3. The correlation was higher when the age was lower. The attenuation correction methods correlation was higher between them two than with the “no attenuation correction” method (r=0.82 +/- 0.8), and the mean differences of the uptake values were 2 +/- 2. Conclusion: The decision of not doing any kind of attenuation correction method can be justified by the minor differences verified on the relative kidney uptake values. Nevertheless, if it is recognized that there is a need for an accurate value of the relative kidney uptake, then an attenuation correction method should be used. Attenuation correction factors proposed by Tonnesen can be easily implemented and so become a practical and easy to implement alternative, namely when the anterior projection - needed for the geometric mean methodology – is not acquired.

Post-MAPS: An interactive acquisition platform for gastroenterology

Post-MAPS is a web platform that collects gastroenterological exam data from several european hospital centers, to be used in future clinical studies and was developed in partnership with experts from the gastroenterological area and information technology (IT) technicians. However, although functional, this platform has some issues that are crucial for its functioning, and can render user interaction unpleasant and exhaustive. Accordingly, we proposed the development of a new web platform, in which we aimed for an improvement in terms of usability, data uni cation and interoperability. Therefore, it was necessary to identify and study different ways of acquiring clinical data and review some of the existing clinical databases in order to understand how they work and what type of data they store, as well as their impact and contribution to clinical knowledge. Closely linked to the data model is the ability to share data with other systems, so, we also studied the concept of interoperability and analyzed some of the most widely used international standards, such as DICOM, HL7 and openEHR. As one of the primary objectives of this project was to achieve a better level of usability, practices related to Human Computer-Interaction, such as requirement analysis, creation of conceptual models, prototyping, and evaluation were also studied. Before we began the development, we conducted an analysis of the previous platform, from a functional point of view, which allowed us to gather not only a list of architectural and interface issues, but also a list of improvement opportunities. It was also performed a small preliminary study in order to evaluate the platform's usability, where we were able to realize that perceived usability is different between users, and that, in some aspects, varies according to their location, age and years of experience. Based on the information gathered during the platform's analysis and in the conclusions of the preliminary study, a new platform was developed, prepared for all potential users, from the inexperienced to the most comfortable with technology. It presents major improvements in terms of usability, also providing several new features that simplify the users' work, improving their interaction with the system, making their experience more enjoyable.