Expertise affects inter-observer agreement at peripheral locations within a brain tumor

Magnetic resonance imaging (MRI) is a crucial tool for clinical brain tumor detection and delineation. Since the process of gross tumor volume delineation resides with clinicians, a better understanding of how they perform this task is required if improvements in life expectancy are to be made. Novice-expert comparison studies have been used to examine the effect of expertise on abnormality detection, but little research has investigated expertise-related differences in brain tumor delineation. In this study, undergraduate students (novices) and radiologists (experts) inspected a combination of T1 and T2 single and whole brain MRI scans, each containing a tumor. Using a tablet and stylus to provide an interactive environment, participants had an unlimited amount of time to scroll freely through the MRI slices and were instructed to delineate (i.e., draw a boundary) around any tumorous tissue. There was no reliable evidence for a difference in the gross tumor volume or total number of slices delineated between experts and novices. Agreement was low across both expertise groups and significantly lower at peripheral locations within a tumor than central locations. There was an interaction between expertise level and location within a tumor with experts displaying higher agreement at the peripheral slices than novices. An effect of brain image set on the order in which participants inspected the slices was also observed. The implications of these results for the training undertaken by early career radiologists and current practices in hospitals are discussed

Multi-scale Nanoparticle Contrast Agents

Nanoparticles have potential biomedical applications because of their special physical properties. Multi-scale nanoparticles contrast agents are those particles that provide contrast in different scale imaging modalities. Such particles are of great interest for monitoring anti-cancer drug delivery, allowing investigations of whole body drug distribution as well as that at the microscopic level. Magnetic nanoparticles in particular have been used as contrast agents in MRI and optical techniques such as confocal microscopy and two photon fluorescence (TPF) microscopy to achieve multiple scale imaging. However, confocal microscopy has a limited optical penetration in biological tissue. Moreover, both techniques, confocal microscopy and TPF microscopy, require labelling of the biological tissue which alters the particle distribution and complicates the biological system under-investigation.King Abdulaziz University, Jeddah, Saudi Arabia