In the previous blogs our focus has been concentrated on the slide reading and evaluation processes of TBDx™. While these processes are fundamental to the technology, there are other technical modules completed that maximize efficiency and provide laboratory workflow intelligence.
Intelligent Case Processing
TBDx™ can be configured to process individual patient cases based on a set of user-defined rules. Examples:
- TB patients currently under treatment are retested on a recurring basis until their sputum is completely free of bacteria. In some cases their drug regimen may have halted the development of further bacteria, but may not have completely eradicated it. The remaining bacteria is non-infectious (it cannot grow in culture), yet it remains in the sputum and can be identified. Neither visually nor algorithmically can the condition of the bacteria be classified as active or passive. Therefore, with a priori knowledge that the individual is under treatment, TBDx™ can flag the case with a unique designation other than TB positive. Valuable intelligence can be derived that may indicate drug resistance or eliminate the expense of culture testing.
- It is well documented that the mortality rate of HIV infected patients can be closely associated with TB co-infection. HIV patients generally exhibit very low TB bacilli counts in their sputum (referred to as scanty cases) making detection very difficult. Knowing the patient has HIV permits the TBDx™ intelligent processing module to increase the number of FOVs captured (from 100 to a user-defined number of FOVs) to increase the probability that bacilli will be captured in the area under analysis.
NOTE: On any given sputum smear there are approximately 5,000 potential FOVs, so detection becomes a matter of probability. This is not an issue in detecting positive cases designated a P+ – P+++. In scanty cases the number of FOVs captured and analyzed is of extreme importance as the probability of detection rises with the increase in FOVs.
Field-of-View (FOV) Flexibility
The TBDx™ technology can be adjusted to acquire the WHO standard of 100 FOVs or any number higher or lower to accommodate any laboratory protocol. While the relationship of the number of FOVs captured to the performance of the detection algorithm is non-linear, internal testing has clearly demonstrated performance improvements in sensitivity (diagnosing positive cases as positive) with only marginal increases in ‘false positives’. This flexibility allows the user to determine the importance of sensitivity when compared to specificity (correctly diagnosing negative cases), adjusting the image capture to maximize the intended outcomes. This can be accomplished with a few simple clicks of the mouse!
In manual sputum microscopy, once the microscopist can determine that the slide represents a positive case of TB (based on WHO standards for the number of bacilli present), he or she stops checking the slide and moves on to the next one. With TBDx™ we’ve added the same form of intelligence by having the technology count bacilli and cease image capture when predetermined thresholds have been met … and move to the next case.
Intelligent Decision Support
One of the significant advantages of digital image capture is the storage of the images with their related detection results. In certain situations it may be advantageous for an expert microbiologist to review the images and diagnostic results, i.e. in the case of patients already under treatment. The ability of the reviewer to parse the data by initiating a set of parameters (only negative FOVs, only positive FOVs, or only positive FOVs with case bacilli counts less than 10 per slide, etc.) provides a flexible decision support system that improves the accuracy and speed of decision-making. The system is a real client-server-based data management system and storage solution developed explicitly for microscopy. Since the images captured are static, the case can be reviewed multiple times, with each reviewer analyzing the same images. This advantage is juxtaposed with separate reviewers analyzing the slide at different times, by visually inspecting the smear (most likely not the same FOVs) looking down the microscope. This advantage can be leveraged further by using these stored images with the Intelligent Decision Support software as a training aid – an extremely valuable module.
Lastly, we have built into the TBDx™ application all of the necessary communications software to allow for immediate results transmission via the Internet, text messaging, or mobile phone messaging. The transport of images and data while maintaining traceability becomes tremendously important, as does the sharing of images and information – independent of time and place. Therefore, the platform assists the user by keeping everything clearly structured, easy to manage and ensures efficient communication of images and data via local networks, Wi-Fi, or even a cloud service.