Computer-Assisted Diagnosis in Renal Nuclear Medicine: Rationale, Methodology, and Interpretative Criteria for Diuretic Renography

Abstract

The goal of artificial intelligence, expert systems, decision support systems and computer assisted diagnosis (CAD) in imaging is the development and implementation of software to assist in the detection and evaluation of abnormalities, to alert physicians to cognitive biases, to reduce intra and inter-observer variability and to facilitate the interpretation of studies at a faster rate and with a higher level of accuracy. These developments are needed to meet the challenges resulting from a rapid increase in the volume of diagnostic imaging studies coupled with a concurrent increase in the number and complexity of images in each patient data. The convergence of an expanding knowledge base and escalating time constraints increases the likelihood of physician errors. Errors are even more likely when physicians interpret low volume studies such as 99mTc-MAG3 diuretic scans where imagers may have had limited training or experience. Decision support systems include neural networks, case-based reasoning, expert systems and statistical systems. iRENEX (renal expert) is an expert system for diuretic renography that uses a set of rules obtained from human experts to analyze a knowledge base of both clinical parameters and quantitative parameters derived from the renogram. Initial studies have shown that the interpretations provided by iRENEX are comparable to the interpretations of a panel of experts. iRENEX provides immediate patient specific feedback at the time of scan interpretation, can be queried to provide the reasons for its conclusions and can be used as an educational tool to teach trainees to better interpret renal scans. iRENEX also has the capacity to populate a structured reporting module and generate a clear and concise impression based on the elements contained in the report; adherence to the procedural and data entry components of the structured reporting module assures and documents procedural competency. Finally, although the focus is CAD applied to diuretic renography, this review offers a window into the rationale, methodology and broader applications of computer assisted diagnosis in medical imaging.

Radionuclides in Nephrourology, Part 2: Pitfalls and Diagnostic Applications

“…Initial data suggest that the interpretations of RENEX (automated analysis of the quantitative data derived from renogram acquisition) is indistinguishable from the interpretations of expert readers (38); moreover, pilot studies of iRENEX (RENEX plus clinical information) have shown that iRENEX performs comparably to experts with clinical information and can reduce interobserver variability among resident physicians and lead to better agreement with expert interpretations (35,39). Approaches such as iRENEX have the potential to help define the essential interpretative criteria for diuresis renography, foster standardized interpretation, teach trainees to better interpret renal scans, and enhance diagnostic accuracy (40). …”

“…Initial data indicate that decision support systems for diuretic renography have the capacity to identify essential elements, facilitate training of students and residents, encourage standardization of procedures, populate structured reports, and assist in study interpretation (23,28,37–40). These initial results need broader development and evaluation.…”

Overall indices for assessing agreement among multiple raters

“…In the absence of a gold standard, it is generally accepted that the best available interpretation comes from an expert with broad expertise and extensive experience in academic nuclear medicine. Although interobserver variability still exists between different nuclear medicine experts, it is generally considered to be minimal . The vast majority of the 590 000 renal scans performed annually in the United States are interpreted by general radiologists, who have less than 4 months training and experience in interpretations of renal scans and, thus, have marked variability in their interpretations compared to experienced readers .…”

“…In the absence of a gold standard, it is generally accepted that the best available interpretation of renal scans comes from experienced experts, but interobserver variability still exists as their interpretations do not always agree with each other . Practicing radiologists at US hospitals often have marked variability in their interpretations compared to experienced readers due to the fact that their training in nuclear medicine was limited to 3‐4 months . An analysis was thus carried out to quantify the interobserver agreement among practicing radiologists and better understand the nature of diagnostic variability present in a real‐world clinical practice with renal scans.…”

Clustering of time activity curves for uptake pattern assessment in dynamic nuclear medicine imaging

“…Visual inspection method is a subjective method that does not provide any quantitative parameters. Quantitative assessment of TAC parameters is a step closer to objectivization [1][2][3][4]. Normal TACs have typical patterns, but abnormal TAC pattern in a selected ROI indicates a lesion or a functional disorder (Fig.…”